% Encoding: UTF-8
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@article{faucris.262424201,
abstract = {Van der Waals (vdW) heterostructures composing of organic molecules with inorganic 2D crystals open the door to fabricate various promising hybrid devices. Here, a fully ordered organic self-assembled monolayer (SAM) to construct hybrid organic–inorganic vdW heterojunction phototransistors for highly sensitive light detection is used. The heterojunctions, formed by layering MoS2 monolayer crystals onto organic [12-(benzo[b]benzo[4,5]thieno[2,3-d]thiophen-2-yl)dodecyl)]phosphonic acid SAM, are characterized by Raman and photoluminescence spectroscopy as well as Kelvin probe force microscopy. Remarkably, this vdW heterojunction transistor exhibits a superior photoresponsivity of 475 A W−1 and enhanced external quantum efficiency of 1.45 × 105%, as well as an extremely low dark photocurrent in the pA range. This work demonstrates that hybridizing SAM with 2D materials can be a promising strategy for fabricating diversified optoelectronic devices with unique properties.},
author = {Zhao, Baolin and Gan, Ziyang and Johnson, Manuel and Najafidehaghani, Emad and Rejek, Tobias and George, Antony and Fink, Rainer and Turchanin, Andrey and Halik, Marcus},
doi = {10.1002/adfm.202105444},
faupublication = {yes},
journal = {Advanced Functional Materials},
keywords = {charge transfer; organic–inorganic hybrid; photodetection; self-assembled monolayer; transition metal dichalcogenides; van der Waals heterojunction},
note = {CRIS-Team Scopus Importer:2021-08-06},
peerreviewed = {Yes},
title = {{2D} van der {Waals} {Heterojunction} of {Organic} and {Inorganic} {Monolayers} for {High} {Responsivity} {Phototransistors}},
year = {2021}
}
@article{faucris.213286224,
abstract = {We report on a novel technique for the fabrication of metallic nanostructures via soft X-ray irradiation of precursor molecules supplied from the gas phase. With this technique we were able to produce localized Co nanostructures with a growth rate and purity competitive with electron beam induced deposition. We demonstrate that our approach exhibits significant selectivity with respect to incident photon energy leading to enhanced growth for resonant absorption energy of the precursor molecule. Based on this finding we propose a unique new pathway of selective deposition from precursor mixtures. Furthermore, we investigated the growth rate with respect to precursor pressure and growth time and discuss the potential resolution limits of this new technique.},
author = {Späth, Andreas and TU, Fan and Vollnhals, Florian and Drost, Martin and Krick Calderon, Sandra and Watts, Benjamin and Fink, Rainer and Marbach, Hubertus},
doi = {10.1039/C6RA18214C},
faupublication = {yes},
journal = {RSC Advances},
note = {EAM Import::2019-03-13},
pages = {98344-98349},
peerreviewed = {Yes},
title = {{Additive} fabrication of nanostructures with focused soft {X}-rays},
volume = {6},
year = {2016}
}
@article{faucris.108424844,
abstract = {Further progress in the spatial resolution of X-ray microscopes is currently impaired by fundamental limitations in the production of X-ray diffractive lenses. Here, we demonstrate how advanced thin film technologies can be applied to boost the fabrication and characterization of ultrahigh resolution X-ray optics. Specifically, Fresnel zone plates were fabricated by combining electron-beam lithography with atomic layer deposition and focused ion beam induced deposition. They were tested in a scanning transmission X-ray microscope at 1.2 keV photon energy using line pair structures of a sample prepared by metalorganic vapor phase epitaxy. For the first time in X-ray microscopy, features below 10 nm in width were resolved. © 2009 Elsevier B.V. All rights reserved.},
author = {Fink, Rainer and Raabe, Jörg and David, Christian and et al.},
author_hint = {Vila-Comamala J., Jefimovs K., Raabe J., Pilvi T., Fink R.H., Senoner M., Maassdorf A., Ritala M., David C.},
doi = {10.1016/j.ultramic.2009.07.005},
faupublication = {no},
journal = {Ultramicroscopy},
pages = {1360-1364},
peerreviewed = {Yes},
support_note = {Author relations incomplete. You may find additional data in field 'author{\_}hint'},
title = {{Advanced} thin film technology for ultrahigh resolution {X}-ray microscopy},
volume = {109},
year = {2009}
}
@article{faucris.119560584,
abstract = {A major bottleneck delaying the further commercialization of thin-film solar cells based on hybrid organohalide lead perovskites is the interface losses in state-of-the-art devices. We present a generic interface architecture that combines solution-processed, reliable, and cost-efficient hole-transporting materials, without compromising efficiency, stability or scalability of perovskite solar cells. Tantalum doped tungsten oxide (Ta-WOx)/conjugated polymer multilayers offer a surprisingly small interface barrier and form quasi-ohmic contacts universally with various scalable conjugated polymers. Using a simple regular planar architecture device, Ta-WOx doped interface-based perovskite solar cells achieve maximum efficiencies of 21.2% and combined with over 1000 hours of light stability based on a self-assembled monolayer. By eliminating additional ionic dopants, these findings open up the whole class of organics as scalable hole-transporting materials for perovskite solar cell},
author = {Hou, Yi and Du, Xiaoyan and Scheiner, Simon and McMeekin, David P. and Wang, Zhiping and Li, Ning and Killian, Manuela and Chen, Haiwei and Richter, Moses and Levchuk, Ievgen and Schrenker, Nadine and Spiecker, Erdmann and Stubhan, Tobias and Luechinger, Norman A. and Hirsch, Andreas and Schmuki, Patrik and Steinrück, Hans-Peter and Fink, Rainer and Halik, Marcus and Snaith, Henry J. and Brabec, Christoph},
doi = {10.1126/science.aao5561},
faupublication = {yes},
journal = {Science},
pages = {1-9},
peerreviewed = {Yes},
title = {{A} generic interface to reduce the efficiency-stability-cost gap of perovskite solar cells},
year = {2017}
}
@article{faucris.108946024,
abstract = {We investigate the resistivity switching in individual Ag-TCNQ wires with on/off-ratios of up to 103. Raman and soft X-ray absorption microspectroscopy studies disclose reverse charge transfer. Quantifying of the fraction of neutral TCNQ within the switched material yields values up to 22.3%. These findings expedite the understanding of the switching process in Ag-TCNQ nanowires.},
author = {Rösner, Benedikt and Ran, Ke and Butz, Benjamin and Schmidt, Ute and Spiecker, Erdmann and Fink, Rainer},
doi = {10.1039/c5cp02207j},
faupublication = {yes},
journal = {Physical Chemistry Chemical Physics},
month = {Jan},
pages = {18278-18281},
peerreviewed = {Yes},
title = {{A} microspectroscopic insight into the resistivity switching of individual {Ag}-{TCNQ} nanocrystals},
volume = {17},
year = {2015}
}
@article{faucris.284491858,
abstract = {Many European sculptures and altarpieces from the Middle Ages were decorated with Zwischgold, a bilayer metal leaf with an ultra-thin gold face backed by silver. Zwischgold corrodes quickly when exposed to air, causing the surface of the artefact to darken and lose gloss. The conservation of such Zwischgold applied artefacts has been an obstinate problem. We have acquired quantitative, 3D nanoscale images of Zwischgold samples from 15th century artefacts and modern materials using ptychographic X-ray computed tomography (PXCT), a recently developed coherent diffractive imaging technique, to investigate the leaf structure and chemical state of Zwischgold. The measurements clearly demonstrate decreasing density (increasing porosity) of the leaf materials and their corrosion products, as well as delamination of the leaves from their substrate. Each of these effects speak to typically observed issues in the conservation of such Zwischgold applied artefacts. Further, a rare variant of Zwischgold that contains extremely thin multiple gold layers and an overlapping phenomenon of Zwischgold with other metal leaves are observed through PXCT. As supportive data, scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) coupled with energy dispersive X-ray analysis (EDX) were performed on the medieval samples.},
author = {Wu, Qing and Soppa, Karolina and Mueller, Elisabeth and Mueller, Julian and Odstrcil, Michal and Tsai, Esther Hsiao Rho and Späth, Andreas and Holler, Mirko and Guizar-Sicairos, Manuel and Butz, Benjamin and Fink, Rainer and Watts, Benjamin},
doi = {10.1039/d2nr03367d},
faupublication = {yes},
journal = {Nanoscale},
note = {CRIS-Team Scopus Importer:2022-11-04},
pages = {15165-15180},
peerreviewed = {Yes},
title = {{A} modern look at a medieval bilayer metal leaf: nanotomography of {Zwischgold}},
volume = {14},
year = {2022}
}
@article{faucris.114565924,
abstract = {The C 1s and N 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of three prototype tetraphenyl porphyrin (TPP) molecules are discussed in the framework of a combined experimental and theoretical study. We employ time-dependent density-functional theory (TDDFT) to compute the NEXAFS spectra of the open- and closed-shell metalloporphyrins CoTPP and ZnTPP as well as the free-base 2HTPP in realistic nonplanar conformations. Using Becke's well-known half-and-half hybrid functional, the computed core excitation spectra are mostly in good agreement with the experimental data in the low-energy region below the appropriate ionization threshold. To make these calculations feasible, we apply a new, simple scheme based on TDDFT using a modified single-particle input spectrum. This scheme is very easy to implement in standard codes and allows one to compute core excitation spectra at a similar cost as ordinary UV/vis spectra even for larger molecules. We employ these calculations for a detailed assignment of the NEXAFS spectra including subtle shifts in certain peaks of the N 1s spectra, which depend on the central coordination of the TPP ligand. We furthermore assign the observed NEXAFS resonances to the individual molecular subunits of the investigated TPP molecules. © 2010 American Institute of Physics.},
author = {Schmidt, Norman Anja and Fink, Rainer and Hieringer, Wolfgang},
doi = {10.1063/1.3435349},
faupublication = {yes},
journal = {Journal of Chemical Physics},
peerreviewed = {Yes},
title = {{Assignment} of near-edge x-ray absorption fine structure spectra of metalloporphyrins by means of time-dependent density-functional calculations},
volume = {133},
year = {2010}
}
@article{faucris.288299978,
abstract = {Two-dimensionally (2D) extended thin films of p-type organic semiconductor C13-BTBT (BTBT = [1]benzothieno[3,2-b]-[1]benzothiophene) were fabricated via self-controlled growth at the liquid-liquid interface. Depicting a compound class originally developed for further functionalization and subsequent realization of self-assembled monolayers (SAMs), the potent BTBT core unit commonly excels in high-quality structure formation as well as charge-transport characteristics. Utilizing a manifold spectromicroscopic toolbox, we observe extraordinarily crystalline C13-BTBT films with an upright standing configuration of the backbone unit accounting for superior intermolecular orbital overlap. The well-defined morphology and internal structure of the film are being underpinned by charge-transport parameters that are in the range of comparable organic electronic devices based on bisubstituted BTBT films from the same processing technique. The inherently favorable membrane-like bilayer molecular arrangement is confirmed by unambiguous representation of the unit cell as derived from electron tomography.},
author = {Hawly, Tim and Johnson, Manuel and Zhao, Baolin and Wu, Mingjian and Späth, Andreas and Streller, Fabian and Nickles Jäkel, Hannah and Halik, Marcus and Spiecker, Erdmann and Watts, Benjamin and Nefedov, Alexei and Fink, Rainer},
doi = {10.1021/acsaelm.2c01095},
faupublication = {yes},
journal = {ACS Applied Electronic Materials},
note = {CRIS-Team WoS Importer:2023-01-27},
pages = {5914-5921},
peerreviewed = {Yes},
title = {{Asymmetry} {Matters}: {Structure} {Elucidation} and {Application} {Potential} of {Solution}-{Processed} {Monoalkylated} {BTBT} {Thin} {Films}},
volume = {4},
year = {2022}
}
@article{faucris.289302661,
abstract = {Advances in organic materials manufacturing have enabled the creation of electronic devices using solution-processing techniques by employing soluble materials with high conductivity grade. In this exploratory study, the use of micro-contact for poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) polymer ink deposition as high-quality structured electrodes for organic field-effect transistors (OFETs) in top-contact geometry is demonstrated. The optimized OFET's solution-processed fabrication is a promising strategy to be realized in the simple, cost-effective roll-to-roll manufacturing processes. The electrical performance of the fabricated devices is comparable to transistors with gold electrodes prepared via vacuum deposition, and even exceeding the values of the charge carriers’ mobilities and featuring lower contact resistance (Rc), due to lower charge-carrier injection barrier for carbon-based organic electrodes. An addition of multi-walled carbon nanotubes to the PEDOT:PSS decreases Rc even further, changing the work function for better energy alignment with semiconductor materials.},
author = {Gubanov, Kirill and Johnson, Manuel and Akay, Melda and Wolz, Benedikt C. and Shen, Dan and Cheng, Xing and Christiansen, Silke and Fink, Rainer},
doi = {10.1002/aelm.202201233},
faupublication = {yes},
journal = {Advanced Electronic Materials},
keywords = {device performance; microcontact printing; microscopy; organic field-effect transistors},
note = {CRIS-Team Scopus Importer:2023-02-17},
peerreviewed = {Yes},
title = {{C8}-{BTBT}-{C8} {Thin}-{Film} {Transistors} {Based} on {Micro}-{Contact} {Printed} {PEDOT}:{PSS}/{MWCNT} {Electrodes}},
year = {2023}
}
@article{faucris.216319487,
abstract = {The growth dynamics of the highly symmetric planar organic molecule NTCDA (1,4,5,6-naphthalene tetra-carboxylic acid dianhydride) on Ag(111) is rather complex, already in the monolayer regime. This dynamics was investigated in situ with high lateral resolution using the aberration-corrected spectro-microscope SMART. Although the molecular structure of NTCDA is very similar to that of the slightly larger molecule PTCDA, the growth behavior of these two molecules is very different. Several differences of the static geometric, electronic, and vibrational structure have been described previously by several authors, but some dynamic properties hardly accessible by other techniques could be observed in the present real time experiments using the SMART. For instance, it is found by direct observation that after decoration of steps and step bunches and depending on substrate temperature and surface morphology, a two-dimensional lattice gas of diffusing NTCDA molecules is formed. This increases in density upon continuous deposition of molecules before islands nucleate which subsequently grow in size while the density of the lattice gas first remains constant and then is reduced. Furthermore, in a certain temperature and coverage range some macroscopic islands (of micrometer size) abruptly change their shape and position on the time scale of few seconds. These "jumping 2-dim droplets" are observable for adsorption as well as for desorption. Moreover, previously observed 2-dimensional phase transitions can now be followed in real time, yielding further insight into an interesting but complex adsorption system.},
author = {Schmidt, Thomas and Marchetto, Helder and Groh, Ullrich and Fink, Rainer and Umbach, Eberhard},
doi = {10.1021/acs.jpcc.8b08523},
faupublication = {yes},
journal = {Journal of Physical Chemistry C},
note = {CRIS-Team WoS Importer:2019-04-23},
pages = {8244-8255},
peerreviewed = {Yes},
title = {{Complex} {Monolayer} {Growth} {Dynamics} of a {Highly} {Symmetric} {Molecule}: {NTCDA} on {Ag}(111)},
volume = {123},
year = {2019}
}
@article{faucris.109388664,
abstract = {One of the most employed morphology optimization methods to design better performing organic photovoltaic devices is ink formulation engineering with additives. In this work, by employing a suboptimal host solvent mixture and 1,8-diiodooctane (DIO) as a very optimal solvent for both components in poly-thieno[3,2b]thiophene-diketopyrrolopyrrole-co-thiophene (DPP-TT-T)-based bulk-heterojunctions (BHJ), an alternative, previously unknown mechanism of additive behavior on BHJ microstructure formation is presented. In situ characterization methods involving grazing incidence X-ray diffraction, white-light reflectometry, laser light scattering and photoluminescence during film drying reveal that the microstructure formation under the influence of DIO is led towards thermodynamic equilibrium during host solvent drying, and the kinetics of morphology formation (i.e. polymer crystallization, fullerene aggregation...) are controlled dominantly by the additive during its evaporation. Ex situ X-ray-based characterization methods, such as scanning transmission X-ray microspectroscopy (STXM) and resonant soft X-ray scattering (R-SoXS), additionally reveal that the microstructure of dried films favors smaller domain sizes with purer domains, smaller fullerene aggregates, bimodal polymer crystallization relative to the substrate and more face-on molecular orientation relative to the donor/acceptor interface, which at the end lead to better performing devices with power conversion efficiencies ranging from 1.25% to 4.68%.},
author = {Güldal, Nusret Sena and Berlinghof, Marvin and Kassar, Thaer and Du, Xiaoyan and Jiao, Xuechen and Meyer, Markus and Ameri, Tayebeh and Osvet, Andres and Li, Ning and Destri, Giovanni Li and Fink, Rainer and Ade, Harald and Unruh, Tobias and Brabec, Christoph},
doi = {10.1039/c6ta07023j},
faupublication = {yes},
journal = {Journal of Materials Chemistry A},
keywords = {Engineering controlled terms: Additives; Fullerenes; Heterojunctions; Interfaces (materials); Light scattering; Microstructure; Molecular orientation; Morphology; Polymers; Solvents; Thiophene; X ray diffraction; X ray scattering Bulk heterojunction (BHJ); Characterization methods; Donor/acceptor interface; Grazing incidence X-ray diffraction; In-situ characterization; Microstructure formation; Organic photovoltaic devices; Power conversion efficiencies Engineering main heading: Polymer films},
pages = {16136-16147},
peerreviewed = {unknown},
title = {{Controlling} additive behavior to reveal an alternative morphology formation mechanism in polymer: {Fullerene} bulk-heterojunctions},
volume = {4},
year = {2016}
}
@article{faucris.124085104,
abstract = {Organic solar cells based on multinary components are promising to further boost the device performance. The complex interplay of the morphology and functionality needs further investigations. Here, we report on a systematic study on the morphology evolution of prototype ternary systems upon adding sensitizers featuring similar chemical structures but dramatically different crystallinity, namely poly(3-hexylthiophene) (P3HT) and indene-C-bis-adduct (ICBA) blends with poly[(4,4′-bis(2-ethylhexyl)dithieno[3,2-b:2′,3′-d]silole)-2,6-diyl-alt-(4,7-bis(2-thienyl)-2,1,3-benzothiadi-azole)-5,5′-diyl] (Si-PCPDTBT) and poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (C-PCPDTBT), employing energy-filtered transmission electron microscopy (EFTEM) and resonant soft X-ray scattering (RSoXS). In addition, a combined density functional theory (DFT) and artificial neuronal network (ANN) computational approach has been utilized to calculate the solubility parameters and Flory-Huggins intermolecular parameters to evaluate the influence of miscibility on the final morphology. Our experiments reveal that the domain spacing and purity of ICBA-rich domains are retained in Si-PCPDTBT-based systems but are strongly reduced in C-PCPDTBT-based ternary systems. The P3HT fiber structure are retained at low sensitizer content but dramatically reduced at high sensitizer content. The theoretical calculations reveal very similar miscibility/compatibility between the two sensitizers and ICBA as well as P3HT. Thus, we conclude that mainly the crystallization of Si-PCPDTBT drives the nanostructure evolution in the ternary systems, while this driving force is absent in C-PCPDTBT-based ternary blends.},
author = {Du, Xiaoyan and Jiao, Xuechen and Rechberger, Stefanie and Perea Ospina, Jose Dario and Meyer, Markus and Kazerouni, Negar and Spiecker, Erdmann and Ade, Harald and Brabec, Christoph and Fink, Rainer and Ameri, Tayebeh},
doi = {10.1021/acs.macromol.6b02699},
faupublication = {yes},
journal = {Macromolecules},
keywords = {Computation theoryDeep neural networksHigh resolution transmission electron microscopyMorphologyNeuronsOrganic solar cellsSiliconSolar cellsSolubilityTernary systemsTransmission electron microscopyX ray scattering},
pages = {2415-2423},
peerreviewed = {Yes},
title = {{Crystallization} of sensitizers controls morphology and performance in {Si}-/{C}-{PCPDTBT}-sensitized {P3HT}: {ICBA} ternary blends},
url = {http://pubs.acs.org/doi/abs/10.1021/acs.macromol.6b02699},
volume = {50},
year = {2017}
}
@article{faucris.114566364,
abstract = {Inverse melting or disordering, in which the disordered phase forms upon cooling, is known for a few cases in bulk systems under high pressure. We show that inverse disordering also occurs in two dimensions: For a monolayer of 1,4,5,8-naphthalene-tetracarboxylic dianhydride on Ag(111), a completely reversible order-disorder transition appears upon cooling. The transition is driven by strongly anisotropic interactions within the layer versus with the metal substrate. Spectroscopic data reveal changes in the electronic structure of the system corresponding to a strengthening of the interface bonding at low temperatures. We demonstrate that the delicate, temperature-dependent balance between the vertical and lateral forces is the key to understanding this unconventional phase transition.},
author = {Schoell, A. and Kilian, L. and Zou, Y. and Ziroff, J. and Hame, S. and Reinert, Friedrich and Umbach, E. and Fink, Rainer},
doi = {10.1126/science.1189106},
faupublication = {yes},
journal = {Science},
pages = {303-305},
peerreviewed = {Yes},
title = {{Disordering} of an organic overlayer on a metal surface upon cooling},
volume = {329},
year = {2010}
}
@article{faucris.109597664,
abstract = {This study addresses a combination of a well-developed and mild dispersion method and high-quality arc discharge single-walled carbon nanotubes (SWCNTs) as starting materials. Thus, we advance in fabrication of transparent, conducting films with extraordinary low material loss during SWCNT processing. The starting material was characterized by means of thermogravimetric analysis, high-resolution transmission electron microscopy and Raman spectroscopy. The quality of the starting material and produced dispersions was evaluated by ultraviolet and visible light absorption spectroscopy and Raman spectroscopy. A transparent conductive film was fabricated by drop-casting, whereas films were obtained with electrical to optical conductivity ratios (σ/ σ) as high as 2.2, combined with a loss of nanotube material during processing well below 20 wt%. High pressure carbon monoxide conversion (HiPCO) SWCNTs, which are very well described in the literature, were used for comparison. This journal is © the Partner Organisations 2014.},
author = {Rösner, Benedikt and Guldi, Dirk Michael and Chen, J. and Minett, A. I. and Fink, Rainer},
doi = {10.1039/c3nr05788g},
faupublication = {yes},
journal = {Nanoscale},
pages = {3695-3703},
peerreviewed = {unknown},
title = {{Dispersion} and characterization of arc discharge single-walled carbon nanotubes-towards conducting transparent films},
volume = {6},
year = {2014}
}
@article{faucris.316363202,
abstract = {Realizing efficient and stable organic solar cells (OSCs) via all-solution processing requires the design of tailored charge extraction interfaces. Herein, we demonstrate a substantially different interface concept for OSC that is based on a low-temperature processed mesoscopic hole transporting layer (HTL) derived from partially covered organic nanoparticles (NPs) in the n-i-p structure. The mesoscopic interface is further doped in a second coating step with an organic salt dopant, BCF-Li. The interactions among the dopant, the solvent for sequential doping, and the semiconductor layer are surprisingly complex. The mesoscopic interface is necessary to evenly wet the semiconductor and prevent the aggregation of the dopant. At the same time, the sequential process reduces the excess acceptor at the interface. Both processes together are necessary to generate an efficiently doped interface for low-Ohmic-charge extraction and stable contacts. Devices with fully solution-processed mesoscopic interfaces show a superb shelf lifetime of over 22000 h without encapsulation and a long-term operational stability under 1 sun illumination for 2000 h (T80). Flexible devices bypass 1000 bending cycles with negligible degradation. Mesoscopic doped interfaces are demonstrated as an alternative to PEDOT:PSS as well as PEDOT related interface concepts for nonfullerene acceptors (NFA) in the n-i-p architecture.},
author = {Xu, Junyi and Luo, Junsheng and Gubanov, Kirill and Barabash, Anastasiia and Fink, Rainer and Heumüller, Thomas and Brabec, Christoph},
doi = {10.1021/acsenergylett.3c02087},
faupublication = {yes},
journal = {ACS Energy Letters},
note = {CRIS-Team Scopus Importer:2024-01-12},
pages = {30-37},
peerreviewed = {Yes},
title = {{Doping} of {Mesoscopic} {Charge} {Extraction} {Layers} {Enables} the {Design} of {Long}-{Time} {Stable} {Organic} {Solar} {Cells}},
year = {2024}
}
@article{faucris.124146704,
abstract = {The lateral resolution of a surface sensitive low-energy electron microscope (LEEM) has been improved below 4. nm for the first time. This breakthrough has only been possible by simultaneously correcting the unavoidable spherical and chromatic aberrations of the lens system. We present an experimental criterion to quantify the aberration correction and to optimize the electron optical system. The obtained lateral resolution of 2.6. nm in LEEM enables the first surface sensitive, electron microscopic observation of the herringbone reconstruction on the Au(1. 1. 1) surface. © 2010 Elsevier B.V.},
author = {Schmidt, Th and Marchetto, H. and Levesque, P. L. and Groh, U. and Maier, F. and Preikszas, D. and Hartel, P. and Spehr, R. and Lilienkamp, G. and Engel, W. and Fink, Rainer and Bauer, E. and Rose, H. and Umbach, E. and Freund, H. -J.},
doi = {10.1016/j.ultramic.2010.07.007},
faupublication = {yes},
journal = {Ultramicroscopy},
pages = {1358-1361},
peerreviewed = {Yes},
title = {{Double} aberration correction in a low-energy electron microscope},
volume = {110},
year = {2010}
}
@article{faucris.117434064,
abstract = {The autocatalytic growth of arbitrarily shaped nanostructures fabricated by electron beam-induced deposition (EBID) and electron beam-induced surface activation (EBISA) is studied for two precursors: iron pentacarbonyl, Fe(CO)(5), and cobalt tricarbonyl nitrosyl, Co(CO)(3)NO. Different deposits are prepared on silicon nitride membranes and silicon wafers under ultrahigh vacuum conditions, and are studied by scanning electron microscopy (SEM) and scanning transmission X-ray microscopy (STXM), including near edge X-ray absorption fine structure (NEXAFS) spectroscopy. It has previously been shown that Fe(CO)(5) decomposes autocatalytically on Fe seed layers (EBID) and on certain electron beam-activated surfaces, yielding high purity, polycrystalline Fe nanostructures. In this contribution, we investigate the growth of structures from Co(CO)(3)NO and compare it to results obtained from Fe(CO)(5). Co(CO)(3)NO exhibits autocatalytic growth on Co-containing seed layers prepared by EBID using the same precursor. The growth yields granular, oxygen-, carbon- and nitrogen-containing deposits. In contrast to Fe(CO)(5) no decomposition on electron beam-activated surfaces is observed. In addition, we show that the autocatalytic growth of nanostructures from Co(CO)(3)NO can also be initiated by an Fe seed layer, which presents a novel approach to the fabrication of layered nanostructures.},
author = {Vollnhals, Florian and Drost, Martin and TU, Fan and Carrasco Burgos, Esther and Späth, Andreas and Fink, Rainer and Steinrück, Hans-Peter and Marbach, Hubertus},
doi = {10.3762/bjnano.5.129},
faupublication = {yes},
journal = {Beilstein Journal of Nanotechnology},
keywords = {autocatalytic growth;cobalt tricarbonyl nitrosyl;electron-beam induced deposition;nanofabrication;scanning transmission X-ray microscopy},
pages = {1175-1185},
peerreviewed = {Yes},
title = {{Electron}-beam induced deposition and autocatalytic decomposition of {Co}({CO})(3){NO}},
volume = {5},
year = {2014}
}
@article{faucris.119365664,
abstract = {We present a high-resolution photoelectron spectroscopy investigation of condensed films of benzene, naphthalene, anthracene, tetracene, and pentacene. High spectroscopic resolution and a systematic variation of the molecular size allow a detailed analysis of the fine structures. The line shapes of the C 1s main lines are analyzed with respect to the different contributions of inhomogeneous broadening, vibronic coupling, and chemical shifts. The shake-up satellite spectra reveal trends, which give insight into the charge redistribution within the molecule upon photoexcitation. In particular, the shake-up between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) increases in intensity and moves closer toward the C 1s main line if the size of the aromatic system is increased. An explanation is given on the basis of the delocalization of the aromatic system and its capability in screening the photogenerated core hole. A comparison of the HOMO-LUMO shake-up position to the optical band gap gives additional insight into the reorganization of the electronic system upon photoexcitation. © 2008 American Institute of Physics.},
author = {Rocco, M. L. M. and Haeming, M. and Batchelor, D. R. and Fink, Rainer and Schoell, A. and Umbach, E.},
doi = {10.1063/1.2966356},
faupublication = {yes},
journal = {Journal of Chemical Physics},
peerreviewed = {Yes},
title = {{Electronic} relaxation effects in condensed polyacenes: {A} high-resolution photoemission study},
volume = {129},
year = {2008}
}
@article{faucris.116013744,
abstract = {Stimulated by recent photoemission results which suggest a positive fundamental energy gap in HgSe, we have investigated the electronic structure of molecular beam epitaxially grown HgSe(001) c(2X2) layers by a combination of direct ultraviolet photoemission spectroscopy (UPS) and inverse (IPES) photoelectron spectroscopy. Our UPS results do not support the finding of additional peaks above the valence band maximum (VBM) of Gawlik et al. [Phys. Rev. Lett. 78, 3165 (1997)]. A comparison of angle-integrated UPS and IPES spectra and ab initia calculated density of states of HgSe and HgTe demonstrates dissimilar behavior of the two compounds in the dispersion of the conduction bands between 0 and 2 eV above the VBM. Our results are compatible with the common view that HgSe is a semimetal. ©2000 The American Physical Society.},
author = {Fink, Rainer and Umbach, Eberhard and Landwehr, G. and et al.},
author_hint = {Eich D. , Hübner D. , Fink Rainer, Umbach E. , Ortner K. , Becker C.R. , Landwehr G. , Fleszar A.},
faupublication = {no},
journal = {Physical Review B},
note = {UnivIS-Import:2015-03-06:Pub.2000.nat.dchph.ppc23.electr},
pages = {12666-12669},
peerreviewed = {Yes},
support_note = {Author relations incomplete. You may find additional data in field 'author{\_}hint'},
title = {{Electronic} structure of {HgSe}(001) investigated by direct and inverse photoemission},
url = {http://prola.aps.org/pdf/PRB/v61/i19/p12666{\_}1},
volume = {61},
year = {2000}
}
@incollection{faucris.207385038,
author = {Schmidt, Norman Anja and Graf-Zeiler, Birgit and Scheurer, Andreas and Prakash, Raju and Saalfrank, Rolf and Goering, E. and Fink, Rainer},
booktitle = {BESSY Annual Reports 2006},
faupublication = {yes},
pages = {357 - 358},
peerreviewed = {unknown},
title = {{Electronic} {Structure} of {Molecular} {Magnets}},
year = {2006}
}
@article{faucris.119366104,
abstract = {We present high resolution oxygen K near-edge x-ray absorption spectra of the acenaphthenequinone (ANQ) derivative 3,8-dibromo-5,6-dichloro-ANQ (Br Cl-ANQ). The spectral features exhibit an almost identical vibronic fine structure compared to that shown by ANQ. The unequal distances of the vibronic levels as derived from the least-squares fit analysis of the vibronic progressions allows us to determine the anharmonicity of the excited state potentials involved. We conclude that a single vibrational progression couples to the resonant excitation of O 1s core electrons preferentially. Comparison of the two ANQ derivatives gives a clear indication that the vibronic mode corresponds to a C=O stretching mode, rather than coupling to a C-H mode as suggested previously. These conclusions are supported by density functional theory calculations. © 2011 American Institute of Physics.},
author = {Schmidt, Norman Anja and Clark, Timothy and Urquhart, Stephen G. and Fink, Rainer},
doi = {10.1063/1.3646732},
faupublication = {yes},
journal = {Journal of Chemical Physics},
peerreviewed = {Yes},
title = {{Electron}-vibron coupling in halogenated acenaphthenequinone upon {O} {K}-edge soft x-ray absorption},
volume = {135},
year = {2011}
}
@article{faucris.119366544,
abstract = {Ultrathin pentacene films resemble benchmark and model materials for organic field-effect transistors (OFETs). We employ scanning transmission X-ray microspectroscopy (STXM) and confocal Raman microspectroscopy as highly resolving probes to obtain insight into the correlation of morphology and charge transport in pentacene OFETs. By combining the operation-induced intensity increase in Raman-active bands with micromorphology, we are able to visualize charge-induced effects, in particular charge trapping in pentacene OFETs during operation. The high sensitivity and specificity of Raman microscopy allows to distinguish between orientation and charge-induced effects and thus to locate the trapped charges at grain boundaries.© 2013 Elsevier B.V. All rights reserved.},
author = {Rösner, Benedikt and Zeilmann, Nina and Schmidt, Ute and Fink, Rainer},
doi = {10.1016/j.orgel.2013.12.002},
faupublication = {yes},
journal = {Organic Electronics},
pages = {435-440},
peerreviewed = {Yes},
title = {{Employing} microspectroscopy to track charge trapping in operating pentacene {OFETs}},
volume = {15},
year = {2014}
}
@inproceedings{faucris.314591727,
abstract = {We report on the fabrication of high-quality organic semiconducting thin films from the potent benchmark molecular compounds pentacene and C8-BTBT-C8. For organic films prepared by the floating-lens method, we observe 1D anisotropy in linear NEXAFS dichroism. Based on the molecular orientation contrast in scanning transmission x-ray microspectroscopy (STXM), azimuthal sample rotation and AFM, we can confirm a high degree of long-range molecular order. The experimental results allow for deeper insight into the presumed growth behavior, which appears to crucially depend on the nature, or more specifically, the aromaticity and volatility, of the used solvent.},
author = {Hawly, Tim and Späth, Andreas and Johnson, Manuel and Streller, Fabian and Watts, Benjamin and Raabe, Jörg and Fink, Rainer},
booktitle = {AIP Conference Proceedings},
date = {2022-06-19/2022-06-24},
doi = {10.1063/5.0168224},
editor = {Tzu-Hung Chuang, Bi-Hsuan Lin, Hung-Wei Shiu, Der-Hsin Wei},
faupublication = {yes},
note = {CRIS-Team Scopus Importer:2023-12-01},
peerreviewed = {unknown},
publisher = {American Institute of Physics Inc.},
title = {{Employing} x-ray spectromicroscopy for the understanding of anisotropy in organic thin film growth},
venue = {Virtual, Online, TWN},
volume = {2990},
year = {2023}
}
@article{faucris.108341464,
abstract = {Experimentally determined band offsets of the CdSe/ZnTe/InAs(100) semiconductor heterostructures were presented. The semimagnetic system showed to behave very similar to the Mn-free model system. A stepwise alignment of the valence bands and in the ZnTe interlayer a 1.1 eV conduction band tunnel barrier were found.},
author = {Gleim, Thomas and Weinhardt, L. and Schmidt, Th. and Fink, Rainer and Heske, C. and Umbach, E. and Grabs, P. and Schmidt, G. and Molenkamp, L.W. and Richter, B. and Fleszar, A. and Steinrück, Hans-Peter},
doi = {10.1063/1.1519964},
faupublication = {yes},
journal = {Applied Physics Letters},
pages = {3813-3815},
peerreviewed = {Yes},
title = {{Energy} level alignment at zinc blende {Cd}({Mn}){Se}/{ZnTe}/{InAs}(100) interfaces},
volume = {81},
year = {2002}
}
@article{faucris.114570544,
author = {Vila-Comamala, Joan and Jefimovs, Konstantins and Raabe, Joerg and Pilvi, Tero and Fink, Rainer and Senoner, Mathias and Maassdorf, Andre and Ritala, Mikko and David, Christian},
doi = {10.1016/j.ultramic.2009.11.012},
faupublication = {yes},
journal = {Ultramicroscopy},
peerreviewed = {Yes},
title = {{Erratum} to "advanced thin film technology for ultrahigh resolution {X}-ray microscopy" [{Ultramicroscopy} 109 (2009) 1360-1364] ({DOI}:10.1016/j.ultramic.2009.07.005)},
volume = {110},
year = {2010}
}
@article{faucris.213410328,
abstract = {Focused soft X-ray beam induced deposition of metallic deposits from metal organic precursors is a promising novel technique for additive nanostructure fabrication. In the present work, the authors present a comparative study for deposition and in situ characterization of Co and Mn nanostructures in a scanning transmission x-ray microscope. The authors detect a significant selectivity of the deposition process with respect to the incident photon energy that arises from the enhanced x-ray absorption cross section of the precursor molecules for near-threshold excitation. This effect has been investigated for the L2,3-edges of the respective metal centers of two different precursor molecules as well as the N and O K-edges of the respective ligands. The authors find a photon-limited growth mode for deposition from cobalt tricarbonyl nitrosyl [Co(CO)3NO], while the process is precursor-limited for methylcyclopentadienyl manganese tricarbonyl [MeCpMn(CO)3] possibly due to a comparably low vapor pressure of the latter precursor.},
author = {TU, Fan and Späth, Andreas and Drost, Martin and Vollnhals, Florian and Krick Calderon, Sandra and Fink, Rainer and Marbach, Hubertus},
doi = {10.1116/1.4979274},
faupublication = {yes},
journal = {Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics},
note = {EAM Import::2019-03-14},
peerreviewed = {No},
title = {{Exploring} the fabrication of {Co} and {Mn} nanostructures with focused soft x-ray beam induced deposition},
volume = {35},
year = {2017}
}
@article{faucris.273562260,
abstract = {Crystalline organic semiconducting thin films from the benchmark molecule C8-BTBT-C8 were obtained using physical vapor deposition and various solution-based methods. Utilizing atomic force microscopy and X-ray spectromicroscopy, we illustrate the influence of the underlying growth mechanism and determine the highly preparation-dependent orientation of the thiophene backbone. We observe a continuous trend for crystalline C8-BTBT-C8 thin film domains to extend into the square millimeter-range under near-equilibrium growth conditions. For such well-defined systems, electron diffraction tomography allows us to precisely determine the unit cell directly after film deposition and to reveal an 8° molecular tilt angle with respect to the surface normal. This finding is in almost perfect accordance with the values derived from near-edge X-ray absorption fine structure linear dichroism. Within this work, we shine a light on both the successes and challenges connected to the realization of potent, thiophene-based semiconducting films, paving the way toward square centimeter-sized ultrathin organic crystals and their application in organic circuitry.},
author = {Hawly, Tim and Johnson, Manuel and Späth, Andreas and Nickles Jäkel, Hannah and Wu, Mingjian and Spiecker, Erdmann and Watts, Benjamin and Nefedov, Alexei and Fink, Rainer},
doi = {10.1021/acsami.2c00097},
faupublication = {yes},
journal = {ACS Applied Materials and Interfaces},
keywords = {2D nanomaterials; electron tomography; molecular self-assembly; organic semiconductors; organic thin films; X-ray microspectroscopy},
note = {CRIS-Team Scopus Importer:2022-04-22},
peerreviewed = {Yes},
title = {{Exploring} the {Preparation} {Dependence} of {Crystalline} {2D}-{Extended} {Ultrathin} {C8}-{BTBT}-{C8} {Films}},
year = {2022}
}
@article{faucris.286195181,
abstract = {We present an in operando near-edge x-ray absorption fine structure (NEXAFS) study on p-type [11-(benzo[b]benzo[4,5]thieno[2,3-d]thiophen-2-yl)dodecyl)] BTBT-based self-assembled monolayer (BTBT-SAM) films. As a 2D-model system, the BTBT-SAM offers direct insight into the active organic semiconductor layer without interfering bulk materials. This allows for the observation of polaronic states caused by charged species at the dielectric/organic interface. Linear NEXAFS dichroism is employed to derive the molecular orientation of the BTBT subunit. Field-induced modifications in the unoccupied molecular orbitals are observed in the NEXAFS spectra. The spectral changes in the on- and off-states are discussed in the context of polaron formation due to charge accumulation induced by the applied electric field. Published under an exclusive license by AIP Publishing.},
author = {Johnson, Manuel and Hawly, Tim and Zhao, Baolin and Halik, Marcus and Nefedov, A. and Fink, Rainer},
doi = {10.1063/5.0105893},
faupublication = {yes},
journal = {Applied Physics Letters},
note = {CRIS-Team WoS Importer:2022-12-02},
peerreviewed = {Yes},
title = {{Field}-induced modification of the electronic structure in {BTBT}-based organic thin films observed by {NEXAFS} spectroscopy},
volume = {121},
year = {2022}
}
@article{faucris.234647936,
abstract = {X-ray tomography has become an indispensable tool for studying complex 3D interior structures with high spatial resolution. Three-dimensional imaging using soft X-rays offers powerful contrast mechanisms but has seen limited success with tomography due to the restrictions imposed by the much lower energy of the probe beam. The generalized geometry of laminography, characterized by a tilted axis of rotation, provides nm-scale 3D resolution for the investigation of extended (mm range) but thin (μm to nm) samples that are well suited to soft X-ray studies. This work reports on the implementation of soft X-ray laminography (SoXL) at the scanning transmission X-ray spectromicroscope of the PolLux beamline at the Swiss Light Source, Paul Scherrer Institut, which enables 3D imaging of extended specimens from 270 to 1500 eV. Soft X-ray imaging provides contrast mechanisms for both chemical sensitivity to molecular bonds and oxidation states and magnetic dichroism due to the much stronger attenuation of X-rays in this energy range. The presented examples of applications range from functionalized nanomaterials to biological photonic crystals and sophisticated nanoscaled magnetic domain patterns, thus illustrating the wide fields of research that can benefit from SoXL.},
author = {Witte, Katharina and Späth, Andreas and Finizio, Simone and Donnelly, Claire and Watts, Benjamin and Sarafimov, Blagoj and Odstrcil, Michal and Guizar-Sicairos, Manuel and Holler, Mirko and Fink, Rainer and Raabe, Jörg},
doi = {10.1021/acs.nanolett.9b04782},
faupublication = {yes},
journal = {Nano Letters},
keywords = {3D imaging; flat and extended specimens; laminography; soft X-rays; X-ray microscopy},
note = {CRIS-Team Scopus Importer:2020-02-21},
pages = {1305-1314},
peerreviewed = {Yes},
title = {{From} {2D} {STXM} to {3D} {Imaging}: {Soft} {X}-ray {Laminography} of {Thin} {Specimens}},
volume = {20},
year = {2020}
}
@article{faucris.113548864,
abstract = {We present high-resolution C Is and O 1s photoemission results of different NTCDA monolayer states adsorbed on a Ag(111) substrate (NTCDA = 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride). The comparison of mono- and multilayer data clearly proves the chemisorptive character of the bonding of this planar aromatic molecule to the metal substrate. The rich fine structures of the monolayer spectra exhibit large differences for the three distinct monolayer states observed, leading to the conclusion of significant differences in their bonding. The fine structures are interpreted in detail on the basis of a thorough peak-fit analysis which allows a consistent assignment of the various photoemission main and satellite lines. As a result, the binding energies of the 1s levels of all C and O atoms and the relative intensities of the most significant satellite lines are extracted, the latter providing important information on the bonding and the dynamic screening process.},
author = {Fink, Rainer and Umbach, Eberhard and Schoell, Achim and Schmidt, Thomas and et al.},
author_hint = {Schöll A., Zou Y., Schmidt T., Fink R., Umbach E.},
doi = {10.1021/jp049005z},
faupublication = {no},
journal = {Journal of Physical Chemistry B},
pages = {14741-14748},
peerreviewed = {Yes},
support_note = {Author relations incomplete. You may find additional data in field 'author{\_}hint'},
title = {{High}-resolution photoemission study of different {NTCDA} monolayers on {Ag}(111): {Bonding} and screening influences on the line shapes},
volume = {108},
year = {2004}
}
@article{faucris.230865780,
abstract = {Metal halide perovskites are known to possess upon photoexcitation long-lived hot carriers. By using femtosecond laser transient absorption spectroscopy, we probed in the current work interfacial charge transfer, that is, hot electrons and holes in methylammonium lead iodide perovskite. The focus was, on the one hand, on titanium dioxide as an electron transporting material and, on the other hand, on several organic semiconducting materials as hole transporting materials in perovskite solar cells. An unexpected carrier loss pathway for hot electrons was found in the form of injection into the low lying LUMOs of several organic semiconducting materials. Of great importance is the fact that the final photocurrents of perovskite solar cells scale with the suppression of this newly discovered loss pathway.},
author = {Jiménez-López, Jesús and Puscher, Bianka and Cambarau, Werther and Fink, Rainer and Palomares, Emilio and Guldi, Dirk Michael},
doi = {10.1039/c9nr06297a},
faupublication = {yes},
journal = {Nanoscale},
note = {CRIS-Team Scopus Importer:2019-12-27},
pages = {23357-23365},
peerreviewed = {Yes},
title = {{Hot} electron injection into semiconducting polymers in polymer based-perovskite solar cells and their fate},
volume = {11},
year = {2019}
}
@article{faucris.205676387,
abstract = {Here, brand new ternary hybrid solar cells comprising perovskite nanocrystals (NCs) with a complementary absorption profile of the organic host matrix are reported. In particular, NH2CHNH2PbI3 (FAPbI3) perovskite NCs are implemented in bulk heterojunction organic solar cells based on the pDPP5T-2 electron donating polymer and a [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) acceptor at various loading amounts and the fabricated hybrid
photovoltaics are thoroughly studied by employing different
optoelectrical characterization methods. Current-voltage measurements
and photoinduced charge carrier extraction by linear increasing voltage (photo-CELIV) reveal improved charge generation and charge transport properties upon incorporation of perovskite NCs into the photo-active layer of the hybrid solar cell. The power conversion efficiency (PCE) of the hybrid solar cell comprising 5% perovskite
NCs is 10% enhanced compared to the organic reference, mainly due to
the enlarged light harvesting and increased short circuit current
density (Jsc). However, results suggest that introducing a higher amount of perovskite content induces bimolecular and trap-assisted recombination in the ternary devices. We perform a comprehensive transient absorption study of the charge
transfer/transport mechanisms by employing femto-second pump-probe
transient absorption spectroscopy (fs-TAS). fs-TAS measurements
demonstrate a slower charge carrier recombination rate due to the introduction of perovskite NCs into the photoactive layer. Results reveal that DPP injects electrons from the singlet excited state into the perovskite NCs, which causes the desired cascading charge carrier transfer. In ternary blends, a small amount of FAPbI3 NCs provides an additional pathway in favor of the charge-separated
state via the NCs, which, despite accelerating the depopulation of
DPP's singlet excited state slightly slows down the charge-separation process between DPP and PC61BM. Interestingly, the loss processes are slowed down; an effect that is more important and, hence, explains the improved solar cell efficiency. © 2018 the Owner Societie},
author = {Soltani, Rezvan and Puscher, Bianka and Katbab, Ali Asghar and Levchuk, Ievgen and Kazerouni, Negar and Gasparini, Nicola and Camaioni, Nadia and Osvet, Andres and Batentschuk, Miroslaw and Fink, Rainer and Guldi, Dirk Michael and Ameri, Tayebeh},
doi = {10.1039/c8cp03743d},
faupublication = {yes},
journal = {Physical Chemistry Chemical Physics},
pages = {23674-23683},
peerreviewed = {Yes},
title = {{Improved} charge carrier dynamics in polymer/perovskite nanocrystal based hybrid ternary solar cells},
volume = {20},
year = {2018}
}
@article{faucris.108353124,
abstract = {We have investigated the influence of As substrate passivation on the electronic level alignment of the heterovalent BeTe/Si(111) interface. Employing photoelectron spectroscopy, we have performed k-resolved measurements at selected excitation energies in the uv range to maximize the contribution from the F point for a correct determination of the valence band maximum. These results are compared with k-integrated data using a density-of-states function from density functional theory. For BeTe(100) and BeTe(111), we find a negligible influence of surface orientation on the position of the valence band maximum. The As passivation increases the valence band offset by 0.24 eV (±0.13 eV) compared to BeTe on an unpassivated Si substrate, thus leading to a significantly increased step in the valence band (0.37±0.13 eV). The results are discussed with respect to the barriers for electron and hole injection in heterostructures and with respect to the interface structure.},
author = {Gleim, Thomas and Weinhardt, L. and Schmidt, Th. and Fink, Rainer and Heske, C. and Umbach, E. and Hansen, L. and Landwehr, G. and Waag, A. and Fleszar, A. and Richter, B. and Ammon, Christian and Probst, Marc and Steinrück, Hans-Peter},
doi = {10.1103/PhysRevB.67.205315},
faupublication = {yes},
journal = {Physical Review B},
pages = {2053151-2053156},
peerreviewed = {Yes},
title = {{Influence} of {As} passivation on the electronic level alignment at {BeTe}/{Si}(111) interfaces},
volume = {67},
year = {2003}
}
@article{faucris.107230024,
abstract = {We characterize individual Ag-TCNQ nanocrystals during switching their resistivity state in operando. Raman and soft X-ray absorption microspectroscopy are employed to disclose the electronic state of the organic component in dependency of applied voltage. Whereas Raman microspectroscopy offers qualitative insight into the conversion of negatively charged TCNQ molecules to their neutral counterpart, quantification of the neutral fraction can be achieved using X-ray absorption spectroscopy. These results allow a detailed investigation of resistivity switching in electrically bistable Ag-TCNQ nanocrystals.},
author = {Rösner, Benedikt and Schmidt, Ute and Fink, Rainer},
doi = {10.1088/1742-6596/849/1/012016},
faupublication = {yes},
journal = {Journal of Physics: Conference Series},
pages = {1-4},
peerreviewed = {unknown},
title = {{In}-operando studies of {Ag}-{TCNQ} nanocrystals using {Raman} and soft x-ray microspectroscopy},
volume = {849},
year = {2017}
}
@inproceedings{faucris.211671585,
abstract = {Turkey red is a traditional pigment for textile dyeing and its use has been proven for various cultures within the last three millennia. The pigment is a dye-mordant complex consisting of Al and an extract from R. tinctorum that contains mainly the anthraquinone derivative alizarin. The chemical structure of the complex has been analyzed by various spectroscopic and crystallographic techniques for extractions from textiles or directly in solution. We present an in-situ study of Turkey red by means of mu-XRF mapping and NEXAFS spectroscopy on textile fibres dyed according to a traditional process to gain insight into the coordination chemistry of the pigment in realistic matrix. We find an octahedral coordination of Al that corresponds well to the commonly accepted structure of the Al alizarin complex derived from ex-situ studies.},
author = {Meyer, Markus and Huthwelker, T. and Borca, C. N. and Meßlinger, Karl and Bieber, M. and Fink, Rainer and Späth, Andreas},
doi = {10.1088/1748-0221/13/03/C03007},
faupublication = {yes},
note = {EVALuna2:35772},
peerreviewed = {Yes},
title = {{In}-situ spectroscopic analysis of the traditional dyeing pigment {Turkey} red inside textile matrix},
volume = {13},
year = {2018}
}
@article{faucris.109979584,
abstract = {Ultrathin pentacene-based organic field-effect transistors (OFETs) on commercially available silicon nitride membranes suitable for transmission X-ray experiments are demonstrated. The devices produced by high-vacuum deposition show excellent electronic performance ( = 0.6 cm V s, I = 10). STXM-experiments recorded with the PolLux microspectroscope correlate structural and electronic properties at highest spatial and spectral resolution while the OFET is operated. Local NEXAFS spectra are used to analyze the different orientations of the pentacene nanocrystals. Spectral changes due to modifications in the electronic structure during OFET operation can hardly be detected with the current setup. © The Royal Society of Chemistry 2010.},
author = {Hub, Christian and Burkhardt, Martin and Halik, Marcus and Tzvetkov, G. and Fink, Rainer},
doi = {10.1039/c0jm00423e},
faupublication = {yes},
journal = {Journal of Materials Chemistry},
pages = {4884-4887},
peerreviewed = {Yes},
title = {{In} situ {STXM} investigations of pentacene-based {OFETs} during operation},
volume = {20},
year = {2010}
}
@article{faucris.114572744,
abstract = {Direct, real-time analytical techniques that provide high-resolution information on the chemical composition and submicrometer structure of various polymer micro- and nanoparticles are in high demand in a range of life science disciplines. Synchrotron-based scanning transmission X-ray microspectroscopy (STXM) combines both local-spot chemical information (assessed via near-edge X-ray absorption fine structure spectroscopy) and imaging with resolution of several tens of nanometers, and thus can yield new insights into the nanoscale properties of these materials. Furthermore, this method allows in situ examination of soft-matter samples in aqueous/gaseous environments and under external stimuli, such as temperature, pressure, ultrasound, and light irradiation. This Minireview highlights some recent progress in the application of the STXM technique to study the temperature-dependent behavior of polymer core-shell microcapsules and to characterize the physicochemical properties of the supporting shells of gas-filled microbubbles in their natural hydrated state. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.},
author = {Graf-Zeiler, Birgit and Fink, Rainer and Tzvetkov, George},
doi = {10.1002/cphc.201100370},
faupublication = {yes},
journal = {ChemPhysChem},
pages = {3503-3509},
peerreviewed = {Yes},
title = {{In} situ synchrotron radiation {X}-ray microspectroscopy of polymer microcontainers},
volume = {12},
year = {2011}
}
@article{faucris.112954864,
abstract = {Zwischgold is a two-sided metal foil made by adhering a gold leaf over a silver leaf to present a gold surface while using less gold than gold foils. Corroded Zwischgold surfaces appear dark, accompanied by gloss loss and possible mechanical stability issues. Zwischgold applied artefacts are commonly found in museums and churches across Europe and they currently face an uncertain future as conservators have little knowledge to base conservation treatments on. We present a comprehensive material analysis of Zwischgold models through advanced characterization techniques including focused ion beam coupled with scanning electron microscopy (FIB-SEM), transmission electron microscopy (TEM), scanning transmission X-ray microscopy (STXM), time-of-flight secondary ion mass spectrometry (TOF-SIMS) and Rutherford backscattering spectrometry (RBS). Complementary information on the foil thickness, sharpness of the gold-silver interface, gold purity, and the formation as well as distribution of corrosion products on Zwischgold models have been obtained, representing a starting point for understanding the morphology and the long-term chemistry of Zwischgold artefacts.},
author = {Wu, Qing and Soppa, Karolina and Scherrer, Nadim and Watts, Benjamin and Yokosawa, Tadahiro and Bernard, Laetitia and Araki, Tohru and Doebeli, Max and Meyer, Markus and Spiecker, Erdmann and Fink, Rainer},
doi = {10.1016/j.culher.2017.12.005},
faupublication = {yes},
journal = {Journal of Cultural Heritage},
keywords = {Zwischgold, Interdiffusion, Gold, Silver, Corrosion, Conservation},
peerreviewed = {Yes},
title = {{Investigation} of the foil structure and corrosion mechanisms of modern {Zwischgold} using advanced analysis techniques},
year = {2018}
}
@article{faucris.213057269,
abstract = {High-resolution C 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of naphthalene are investigated. By comparing the spectral signatures of condensed naphthalene molecules with those of naphthalene in the gas phase, we are able to unambiguously identify spectral features which are affected by the intermolecular interactions in the condensed phase. With the help of calculations using time-dependent density-functional theory and the second-order algebraic-diagrammatic construction scheme for the polarization propagator, resonances in the relevant energy range can be assigned to valence and Rydberg-like excitations. Thus, we obtain a more detailed identification of NEXAFS resonances beyond the present literature.},
author = {Schmidt, Norman Anja and Wenzel, Jan and Dreuw, Andreas and Fink, Rainer and Hieringer, Wolfgang},
doi = {10.1063/1.4972013},
faupublication = {yes},
journal = {Journal of Chemical Physics},
note = {EAM Import::2019-03-12},
peerreviewed = {unknown},
title = {{Matrix} effects in the {C} 1s photoabsorption spectra of condensed naphthalene},
volume = {145},
year = {2016}
}
@article{faucris.254746127,
abstract = {A special gilding material called Zwischgold has been frequently observed in medieval gilded artefacts. As a bilayer metal leaf made from gold and silver, it exhibits similar but slightly paler golden colour tone compared to pure gold. Zwischgold surface can be darkened quickly due to the corrosion of its silver base. Despite its frequent mentions in medieval guild statutes, the production of Zwischgold and its important technological parameters have been under a veil of secrecy since the Middle Ages. Here, we examine the thicknesses and materials proportions of medieval Zwischgold, through high-resolution scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX) on a large number of samples taken from late medieval gilded sculptures. We observe that medieval Zwischgold contains ultra-thin gold layers in a thickness range of ca. 20–50 nm, indicating the employment of high-precision technologies in manufacturing of delicate art materials in the late medieval period. It further clarifies some ambiguity in gilding history, regarding the colour appearance of medieval Zwischgold. As supportive data, Rutherford backscattering spectrometry (RBS) and scanning transmission electron microscopy (STEM) were applied, in order to confirm the precision and accuracy of the sample preparation and the SEM analysis.},
author = {Wu, Qing and Watts, Benjamin and Döbeli, Max and Müller, Julian and Butz, Benjamin and Lombardo, Tiziana and Schmidt-Ott, Katharina and Fink, Rainer and Nolting, Frithjof and Ganz, David},
doi = {10.1016/j.culher.2021.01.010},
faupublication = {yes},
journal = {Journal of Cultural Heritage},
keywords = {Gilding; Medieval; Nanoscale; SEM; Thickness; Zwischgold},
note = {CRIS-Team Scopus Importer:2021-04-09},
peerreviewed = {Yes},
title = {{Medieval} nanotechnology: {Thickness} determination of {Zwischgold} samples},
year = {2021}
}
@article{faucris.119370724,
abstract = {Scanning transmission X-ray microspectroscopy (STXM) and L-edge near-edge X-ray absorption fine structure (NEXAFS) spectroscopy have been applied to study the valence states of metal ions in various Fe-and Mn-containing single-molecule magnet materials, in particular the ligand-stabilized metal complexes NaFe (so-called "ferric wheel"), Fe (so-called "ferric star") and Mn (so-called "manganese wheel"). We compare dose-dependent L-edge absorption spectra with the results of theoretical studies of the involved metal ions to conclude on the change in oxidation state upon increasing the X-ray dose. It is found that even low-intensity irradiation induces the reduction of the weakly interacting metal ions, and that the soft X-ray-induced photoreduction is less pronounced in microcrystalline films. © 2010 Verlag der Zeitschrift für Naturforschung, Tübingen.},
author = {Schmidt, Norman Anja and Scheurer, Andreas and Sperner, Stefan and Fink, Rainer},
doi = {10.1515/znb-2010-0324},
faupublication = {yes},
journal = {Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences},
keywords = {Single-molecule Magnet (SMM); X-Ray Absorption; X-Ray Microspectroscopy; STXM; Photoreduction},
pages = {390-398},
peerreviewed = {Yes},
title = {{Microspectroscopic} analysis of the {X}-ray-induced photoreduction in {Fe}-and {Mn}-containing {SMMs}},
url = {http://www.znaturforsch.com/s65b/s65b0390.pdf},
volume = {65},
year = {2010}
}
@article{faucris.109980244,
abstract = {Microencapsulated ionic liquids represent a novel type of material with high potential for various applications in chemical synthesis, catalysis or separation processes. We present a detailed morphological analysis of this material by means of two imaging techniques, i.e., scanning transmission X-ray microspectroscopy (STXM) and transmission electron microscopy (TEM). While TEM can be utilized only in the dry state, STXM offers access to high-resolution imaging in liquid surroundings. In either case prolonged illumination leads to degradation of the stabilizing polymer. We discuss potential scenarios, e.g., formation of perforations within the polymer shell, to explain the experimental findings.},
author = {Späth, Andreas and Minami, Hideto and Suzuki, Toyoko and Fink, Rainer},
doi = {10.1039/c3ra45980b},
faupublication = {yes},
journal = {RSC Advances},
pages = {3272-3277},
peerreviewed = {unknown},
title = {{Morphology} changes of ionic liquid encapsulating polymer microcontainers upon {X}-ray irradiation},
volume = {4},
year = {2014}
}
@article{faucris.206488620,
abstract = {Many handmade ancient and recent oriental wool carpets show outstanding brilliance and persistence of colour that is not achieved by common industrial dyeing procedures. Anthropologists have suggested the influence of wool fermentation prior to dyeing as key technique to achieve the high dyeing quality. By means of mu-XRF elemental mapping of mordant metals we corroborate this view and show a deep and homogenous penetration of colourants into fermented wool fibres. Furthermore we are able to apply this technique and prove that the fermentation process for ancient specimens cannot be investigated by standard methods due to the lack of intact cuticle layers. This finding suggests a broad range of further investigations that will contribute to a deeper understanding of the development of traditional dyeing techniques. Spectroscopic studies add information on the oxidation states of the metal ions within the respective mordant-dye-complexes and suggest a partial charge transfer as basis for a significant colour change when Fe mordants are used.},
author = {Meyer, Markus and Borca, Camelia N. and Huthwelker, Thomas and Bieber, Manfred and Meßlinger, Karl and Fink, Rainer and Späth, Andreas},
faupublication = {yes},
journal = {Scanning},
note = {EVALuna2:33356},
peerreviewed = {Yes},
title = {mu-{XRF} {Studies} on the {Colour} {Brilliance} in {Ancient} {Wool} {Carpets}},
year = {2017}
}
@article{faucris.242000630,
abstract = {The top-down lithographic fabrication of functional metal oxide nanostructures enables technologically important applications such as catalysis and electronics. Here, we report the use of molecular vanadium oxides, polyoxovanadates, as molecular precursors for electron beam lithography to obtain functional vanadium oxide nanostructures. The new resist class described gives access to nanostructures with minimum dimensions close to 10 nm. The lithographically prepared structures exhibit temperature-dependent switching behaviour of their electrical resistivity. The work could lay the foundation for accessing functional vanadium oxide nanostructures in the sub-10-nm domain using industrially established nanolithographic methods.},
author = {Rösner, Benedikt and Fallica, Roberto and Johnson, Manuel and Späth, Andreas and Fink, Rainer and Ekinci, Yasin and David, Christian and Anjass, Montaha H. and Streb, Carsten},
doi = {10.1002/cnma.202000425},
faupublication = {yes},
journal = {ChemNanoMat},
keywords = {Metal Oxide; Nanostructure; Polyoxometalates; Self-Assembly; Vanadium Oxide},
note = {CRIS-Team Scopus Importer:2020-08-28},
peerreviewed = {Yes},
title = {{Nanolithographic} {Top}-{Down} {Patterning} of {Polyoxovanadate}-based {Nanostructures} with {Switchable} {Electrical} {Resistivity}},
year = {2020}
}
@article{faucris.120248964,
abstract = {α,ω-Functionalised oligothiophenes are promising materials for organic field effect transistors due to their high degree of molecular ordering, crystallinity and π-π stacking. We employ several complementary microspectroscopic probes to investigate the formation of thermally evaporated films of 5,5‴-bis(N-acetamido-2-ethyl)-2,2′:5′,2″:5″,2‴quaterthiophene on inert substrates. These films were found to grow in a mixed fashion, featuring layer-by-layer domains with thicknesses of several monolayers and needle-shaped three-dimensional crystals. Detailed analysis of atomic force microscopy (AFM) and photoluminescence microscopy reveals the micro- and nanomorphology of the films. Linear dichroism in the near edge x-ray absorption fine structure and polarisation-dependent laser excitation corroborate the findings of AFM, i.e., upright standing molecules in the multilayer regime. The shape of the 3-dimensional crystallites and multilayer domains indicates strongly anisotropic growth favoured by the herringbone-arrangement of the thiophene moieties and additional stabilisation by hydrogen bonding of the acetamide end groups.},
author = {Zeilmann, Nina and Rösner, Benedikt and Späth, Andreas and Schmidt, Ute and Fink, Rainer},
doi = {10.1016/j.tsf.2015.03.066},
faupublication = {yes},
journal = {Thin Solid Films},
keywords = {Quaterthiophene; Organic field effect transistor; Confocal Raman microscopy; Near edge x-ray absorption fine structure spectroscopy; Scanning transmission x-ray microscopy},
pages = {108-114},
peerreviewed = {Yes},
title = {{Nanomorphology} in thin films of acetamide end-functionalised quaterthiophene},
volume = {583},
year = {2015}
}
@article{faucris.119788064,
abstract = {A combined x-ray transmission and scanning force microscope setup (NanoXAS) recently installed at a dedicated beamline of the Swiss Light Source combines complementary experimental techniques to access chemical and physical sample properties with nanometer scale resolution. While scanning force microscopy probes physical properties such as sample topography, local mechanical properties, adhesion, electric and magnetic properties on lateral scales even down to atomic resolution, scanning transmission x-ray microscopy offers direct access to the local chemical composition, electronic structure and magnetization. Here we present three studies which underline the advantages of complementary access to nanoscale properties in prototype thin film samples. © 2012 IOP Publishing Ltd.},
author = {Pilet, Nicolas and Raabe, Joerg and Stevenson, Stephanie E. and Romer, Sara and Bernard, Laetitia and Mcneill, Christopher R. and Fink, Rainer and Hug, Hans J. and Quitmann, Christoph},
doi = {10.1088/0957-4484/23/47/475708},
faupublication = {yes},
journal = {Nanotechnology},
peerreviewed = {Yes},
title = {{Nanostructure} characterization by a combined x-ray absorption/scanning force microscopy system},
volume = {23},
year = {2012}
}
@inproceedings{faucris.109232244,
author = {Fink, Rainer and Raabe, Jörg and Quitmann, Christoph and Hug, Hans J. and et al.},
author_hint = {I. Schmid, J. Raabe, C. Quitmann, S. Vranjkovic, H. J. Hug, R. H. Fink},
booktitle = {Journal of Physics: Conference Series (JPCS) Volume 186/Band 1},
date = {2008-07-21/2008-07-25},
doi = {10.1088/1742-6596/186/1/012015},
faupublication = {no},
publisher = {IOP Publishing},
support_note = {Author relations incomplete. You may find additional data in field 'author{\_}hint'},
title = {{NanoXAS}, a novel concept for high resolution microscopy},
url = {http://iopscience.iop.org/1742-6596/186/1/012015},
venue = {Zürich, Switzerland},
year = {2009}
}
@inproceedings{faucris.107567504,
abstract = {NanoXAS is a novel x-ray microscope installed at the Swiss Light Source combining laterally resolved soft x-ray spectroscopy with scanning probe microscopy. We report on first in situ studies from thin polymer blend films and magnetic materials where topographic and spectroscopic contrast are used and show how complementary imaging modes provide new insight into many materials. In the future the scanning probe tip will be used to collect photoelectrons. By this we expect a spatial resolution in the few-nm range and unique information on surface and bulk properties of nano-materials. © 2011 American Institute of Physics.},
author = {Wenzel, Stephan and Fink, Rainer and Raabe, Jörg and Quitmann, Christoph and Hug, Hans J. and et al.},
author_hint = {Schmid I., Raabe J., Wenzel S., Fink R., Hug H., Quitmann C.},
booktitle = {10th International Conference on X-Ray Microscopy},
date = {2010-08-15/2010-08-20},
doi = {10.1063/1.3625399},
faupublication = {yes},
pages = {449-452},
publisher = {American Institute of Physics},
support_note = {Author relations incomplete. You may find additional data in field 'author{\_}hint'},
title = {{NanoXAS} - {The} in situ combination of scanning transmission {X}-ray and scanning probe microscopy},
venue = {Chicago, IL},
volume = {1365},
year = {2010}
}
@article{faucris.109980464,
abstract = {We present a new experimental set-up for the investigation of large (>128 amu) organic molecules in the gas-phase by means of near-edge X-ray absorption fine structure spectroscopy in the soft X-ray range. Our approach uses a gas cell, which is sealed off against the surrounding vacuum and which can be heated above the sublimation temperature of the respective molecular compound. Using a confined volume rather than a molecular beam yields short acquisition times and intense signals due to the high molecular density, which can be tuned by the container temperature. In turn, the resulting spectra are of very high quality with respect to signal-to-noise ratio and energy resolution, which are the essential aspects for the analysis of fine spectroscopic details. Using the examples of ANQ, NTCDA, and PTCDA, specific challenges of gas phase measurements on large organic molecules with high sublimation temperatures are addressed in detail with respect to the presented set-up and possible ways to tackle them are outlined. © 2011 Published by Elsevier B.V. All rights reserved.},
author = {Holch, Florian and Huebner, Dominique and Fink, Rainer and Schoell, Achim and Umbach, Eberhard},
doi = {10.1016/j.elspec.2011.05.006},
faupublication = {yes},
journal = {Journal of Electron Spectroscopy and Related Phenomena},
pages = {452-456},
peerreviewed = {Yes},
title = {{New} set-up for high-quality soft-{X}-ray absorption spectroscopy of large organic molecules in the gas phase},
volume = {184},
year = {2011}
}
@article{faucris.212756270,
abstract = {We employ Electron beam induced deposition (EBID) in combination with autocatalytic growth (AG) processes to fabricate magnetic nanostructures with controllable shapes and thicknesses. Following this route, different Fe deposits were prepared on silicon nitride membranes under ultra-high vacuum conditions and studied by scanning electron microscopy (SEM) and scanning transmission x-ray microspectroscopy (STXM). The originally deposited Fe nanostructures are composed of pure iron, especially when fabricated via autocatalytic growth processes. Quantitative near-edge x-ray absorption fine structure (NEXAFS) spectroscopy was employed to derive information on the thickness dependent composition. X-ray magnetic circular dichroism (XMCD) in STXM was used to derive the magnetic properties of the EBID prepared structures. STXM and XMCD analysis evinces the existence of a thin iron oxide layer at the deposit-vacuum interface, which is formed during exposure to ambient conditions. We were able to extract magnetic hysteresis loops for individual deposits from XMCD micrographs with varying external magnetic field. Within the investigated thickness range (2-16 nm), the magnetic coercivity, as evaluated from the width of the hysteresis loops, increases with deposit thickness and reaches a maximum value of $∼$160 Oe at around 10 nm. In summary, we present a viable technique to fabricate ferromagnetic nanostructures in a controllable way and gain detailed insight into their chemical and magnetic properties.},
author = {TU, Fan and Drost, Martin and Vollnhals, Florian and Späth, Andreas and Carrasco, Esther and Fink, Rainer and Marbach, Hubertus},
doi = {10.1088/0957-4484/27/35/355302},
faupublication = {yes},
journal = {Nanotechnology},
note = {EAM Import::2019-03-08},
peerreviewed = {Yes},
title = {{On} the magnetic properties of iron nanostructures fabricated via focused electron beam induced deposition and autocatalytic growth processes},
volume = {27},
year = {2016}
}
@article{faucris.213434346,
abstract = {There is a strong market driven need for processing organic photovoltaics from eco-friendly solvents. Water-dispersed organic semiconducting nanoparticles (NPs) satisfy these premises convincingly. However, the necessity of surfactants, which are inevitable for stabilizing NPs, is a major obstacle towards realizing competitive power conversion efficiencies for water-processed devices. Here, we report on a concept for minimizing the adverse impact of surfactants on solar cell performance. A poloxamer facilitates the purification of organic semiconducting NPs through stripping excess surfactants from aqueous dispersion. The use of surfactant-stripped NPs based on poly(3-hexylthiophene) / non-fullerene acceptor leads to a device efficiency and stability comparable to the one from devices processed by halogenated solvents. A record efficiency of 7.5% is achieved for NP devices based on a low-band gap polymer system. This elegant approach opens an avenue that future organic photovoltaics processing may be indeed based on non-toxic water-based nanoparticle inks.},
author = {Xie, Chen and Heumüller, Thomas and Gruber, Wolfgang and Tang, Xiaofeng and Classen, Andrej and Schuldes, Isabel and Bidwell, Matthew and Späth, Andreas and Fink, Rainer and Unruh, Tobias and Mcculloch, Iain and Li, Ning and Brabec, Christoph},
doi = {10.1038/s41467-018-07807-5},
faupublication = {yes},
journal = {Nature Communications},
keywords = {microstructure-recombination correlation; organic photovoltaics;
polymer-fullerene nanoparticles; water processed},
peerreviewed = {Yes},
title = {{Overcoming} efficiency and stability limits in water-processing nanoparticular organic photovoltaics by minimizing microstructure defects},
volume = {8},
year = {2018}
}
@article{faucris.119610524,
abstract = {Organic solar cells are promising in terms of full-solution-processing which enables low-cost and large-scale fabrication. While single-junction solar cells have seen a boost in power conversion efficiency (PCE), multi-junction solar cells are promising to further enhance the PCE. In all-solution-processed multi-junction solar cells, interfacial losses are often encountered between hole-transporting layer (HTL) and the active layers and therefore greatly limit the application of newly developed high-performance donor and acceptor materials in multi-junction solar cells. Here, the authors report on a systematic study of interface losses in both single-junction and multi-junction solar cells based on representative polymer donors and HTLs using electron spectroscopy and time-of-flight secondary ion mass spectrometry. It is found that a facile mixed HTL containing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and MoO nanoparticles successfully overcomes the interfacial losses in both single- and multi-junction solar cells based on various active layers by reducing interface protonation, promoting better energy-level alignment, and forming a dense and smooth layer. Solution-processed single-junction solar cells are demonstrated to reach the same performance as with evaporated MoO (over 7%). Multi-junction solar cells with polymers containing nitrogen atoms as the first layer and the mixed PEDOT:PSS and MoO nanoparticles as hole extraction layer reach fill factor (FF) of over 60%, and PCE of over 8%, while the identical stack with pristine PEDOT:PSS or MoO nanoparticles show FF smaller than 50% and PCE less than 5%.},
author = {Du, Xiaoyan and Lytken, Ole and Killian, Manuela and Cao, Jiamin and Stubhan, Tobias and Turbiez, Mathieu and Schmuki, Patrik and Steinrück, Hans-Peter and Ding, Liming and Fink, Rainer and Li, Ning and Brabec, Christoph},
doi = {10.1002/aenm.201601959},
faupublication = {yes},
journal = {Advanced Energy Materials},
keywords = {Interfacial losses; Organic multi-junction solar cells; Organic photovoltaics; Recombination layer; Solution-processing},
peerreviewed = {unknown},
title = {{Overcoming} {Interfacial} {Losses} in {Solution}-{Processed} {Organic} {Multi}-{Junction} {Solar} {Cells}},
year = {2016}
}
@article{faucris.119972644,
abstract = {The application of conjugated polymer and fullerene water-based nanoparticles
(NP) as ecofriendly inks for organic photovoltaics (OPVs) is
reported. A low bandgap polymer diketopyrrolopyrrole–quinquethiophene
(PDPP5T-2) and the methanofullerene PC71BM are processed into three types
of nanoparticles: pristine fullerene NPs, pristine polymer NPs, and mixed
polymer:fullerene NPs, allowing the formation of bulk heterojunction (BHJ)
composites with different domain sizes. Mild thermal annealing is required
to melt the nanospheres and enable the formation of interconnected pathways
within mixed phases. This BHJ is accompanied by a shrinkage of film,
whereas the more compact layers show enhanced mobility. Consistently
reduced recombination and better performance are found for mixed NP, containing
both, the polymer and the fullerene within a single NP. The optimized
solar cell processed by ultrasmall NPs delivers a power conversion efficiency
of about 3.4%. This is among the highest values reported for aqueous processed
OPVs but still lacks performance compared to those being processed
from halogenated solvents. Incomplete crystallization is identified as the main
root for reduced efficiency. It is nevertheless believed that postprocessing
does not cut attraction from printing aqueous organic NP inks as a trendsetting
strategy for the reliable and ecofriendly production of organic solar cells.},
author = {Xie, Chen and Classen, Andrej and Späth, Andreas and Tang, Xiaofeng and Min, Jie and Meyer, Markus and Zhang, Chaohong and Li, Ning and Osvet, Andres and Fink, Rainer and Brabec, Christoph},
doi = {10.1002/aenm.201702857},
faupublication = {yes},
journal = {Advanced Energy Materials},
keywords = {Microstructure-recombination correlation; Organic photovoltaics; Polymer-fullerene nanoparticles; Water processed},
peerreviewed = {unknown},
title = {{Overcoming} {Microstructural} {Limitations} in {Water} {Processed} {Organic} {Solar} {Cells} by {Engineering} {Customized} {Nanoparticulate} {Inks}},
year = {2018}
}
@article{faucris.121246884,
abstract = {We report a general fragmentation-and-re-assembly route which gives access to high-nuclearity, mixed-metal polyoxometalate clusters. Reduced vanadium(iv) precursors are oxidatively dis-assembled into reactive fragments which subsequently re-aggregate under template control in a one-pot reaction. It is shown that the oxidative dis-assembly is required, as the use of vanadium(v)-based precursors results in the formation of smaller clusters. The principle is exemplified by the synthesis of a ca. 1.8 × 1.7 × 1.0 nm, 36-nuclear copper vanadium oxide cluster, (nBu N)[CuVO(NO )(CHCN)]. The cluster is characterized in the solid-state and in solution by single-crystal XRD, ESI-MS and other spectroscopic and electrochemical measurements. Several lines of evidence show that the compound is indeed formed exclusively by fully oxidized vanadium(v) centres. In addition, primary fragmentation products of the type [VO(dmso)] were isolated. The cuprovanadate cluster features pentagonal secondary building units of the type {(V)M} (M = Cu, V) which show similar structural function as the well-known {(Mo)Mo } pentagons observed in giant molybdate clusters. The observation suggests that more complex vanadate clusters might be accessible based on these pentagonal units. © 2013 The Royal Society of Chemistry.},
author = {Forster, Johannes and Rösner, Benedikt and Fink, Rainer and Nye, Leanne and Ivanovic-Burmazovic, Ivana and Kastner, Katharina and Tucher, Johannes and Streb, Carsten},
doi = {10.1039/c2sc20942j},
faupublication = {yes},
journal = {Chemical Science},
pages = {418-424},
peerreviewed = {Yes},
title = {{Oxidation}-driven self-assembly gives access to high-nuclearity molecular copper vanadium oxide clusters},
volume = {4},
year = {2013}
}
@article{faucris.108427704,
abstract = {We report on a comprehensive study of the ZnSe(100)-c(2X2)-Na interface using x-ray and UV photo-emission, and x-ray-induced Auger spectroscopy. Spectra were taken after stepwise Na deposition onto a clean c(2X2)-reconstructed ZnSe(100) surface at room temperature up to a saturation coverage of about 1 ML of Na and after annealing. Based on the analysis of Auger parameters and of the relative intensity evolution of various Na, Zn, and Se species, we present the following model for the ZnSe(100)-c(2X2)-Na interface: below a coverage of 0.5 ML, Na is adsorbed on Zn vacancy sites; above 0.5 ML, a cation exchange reaction occurs between Na and Zn atoms; Zn atoms segregate on top of the Na overlayer forming metallic Zn. In addition, band-bending, surface dipole, valence-band and surface states will be discussed. ©1999 The American Physical Society.},
author = {Fink, Rainer and Umbach, Eberhard and et al.},
author_hint = {Chen Z. H. , Eich D., Winkler U., Fink Rainer, Umbach E},
faupublication = {no},
journal = {Physical Review B},
note = {UnivIS-Import:2015-03-05:Pub.1999.nat.dchph.ppc23.photoe},
pages = {8915-8923},
peerreviewed = {Yes},
support_note = {Author relations incomplete. You may find additional data in field 'author{\_}hint'},
title = {{Photoemission} study of the {Na}/{ZnSe}(100) interface},
url = {http://prola.aps.org/pdf/PRB/v60/i12/p8915{\_}1},
volume = {60},
year = {1999}
}
@article{faucris.114573624,
abstract = {Molecular orientation critically influences the mechanical, chemical, optical and electronic properties of organic materials. So far, molecular-scale ordering in soft matter could be characterized with X-ray or electron microscopy techniques only if the sample exhibited sufficient crystallinity. Here, we show that the resonant scattering of polarized soft X-rays (P-SoXS) by molecular orbitals is not limited by crystallinity and that it can be used to probe molecular orientation down to size scales of 10nm. We first apply the technique on highly crystalline small-molecule thin films and subsequently use its high sensitivity to probe the impact of liquid-crystalline ordering on charge mobility in polymeric transistors. P-SoXS also reveals scattering anisotropy in amorphous domains of all-polymer organic solar cells where interfacial interactions pattern orientational alignment in the matrix phase, which probably plays an important role in the photophysics. The energy and q-dependence of the scattering anisotropy allows the identification of the composition and the degree of orientational order in the domains. © 2012 Macmillan Publishers Limited. All rights reserved.},
author = {Collins, B. A. and Cochran, J. E. and Yan, Hongping and Gann, Eliot and Hub, Christian and Fink, Rainer and Wang, Cheng and Schuettfort, T. and Mcneill, C. R. and Chabinyc, M. L. and Ade, Harald},
doi = {10.1038/nmat3310},
faupublication = {yes},
journal = {Nature Materials},
pages = {536-543},
peerreviewed = {Yes},
title = {{Polarized} {X}-ray scattering reveals non-crystalline orientational ordering in organic films},
volume = {11},
year = {2012}
}
@article{faucris.116419204,
abstract = {The acidic food vacuole exerts several important functions during intraerythrocytic development of the human malarial parasite Plasmodium falciparum. Hemoglobin taken up from the host erythrocyte is degraded in the food vacuole, and the heme liberated during this process is crystallized to inert hemozoin. Several antimalarial drugs target food vacuolar pathways, such as hemoglobin degradation and heme crystallization. Resistance and sensitization to some antimalarials is associated with mutations in food vacuolar membrane proteins. Other studies suggest a role of the food vacuole in ion homeostasis, and release of Ca from the food vacuole may mediate adopted physiological responses. To investigate whether the food vacuole is an intracellular Ca store, which in turn may affect other physiological functions in which this organelle partakes, we have investigated total and exchangeable Ca within the parasite's food vacuole using x-ray microanalysis and quantitative confocal live cell Ca imaging. Apparent free Ca concentrations of ∼90, ∼350, and ∼400 nM were found in the host erythrocyte cytosol, the parasite cytoplasm, and the food vacuole, respectively. In our efforts to determine free intracellular Ca concentrations, we evaluated several Ca-sensitive fluorochromes in a live cell confocal setting. We found that the ratiometric Ca indicator Fura-Red provides reliable determinations, whereas measurements using the frequently used Fluo-4 are compromised due to problems arising from phototoxicity, photobleaching, and the strong pH dependence of the dye. Our data suggest that the food vacuole contains only moderate amounts of Ca, disfavoring a role as a major intracellular Ca store. © 2005 by The American Society for Biochemistry and Molecular Biology, Inc.},
author = {Rohrbach, Petra and Friedrich, Oliver and Hentschel, Joachim and Plattner, Helmut and Fink, Rainer and Lanzer, Michael},
doi = {10.1074/jbc.M500777200},
faupublication = {no},
journal = {Journal of Biological Chemistry},
pages = {27960-27969},
peerreviewed = {Yes},
title = {{Quantitative} calcium measurements in subcellular compartments of {Plasmodium} falciparum-infected erythrocytes},
volume = {280},
year = {2005}
}
@article{faucris.115825424,
author = {Fink, Rainer and Umbach, Eberhard and Hanke, W. and Heske, Clemens and et al.},
author_hint = {Eich D., Fuchs O., Groh U., Weinhardt L., Fink R., Umbach E., Heske C., Fleszar A., Hanke W., Gross E. K. U., Bostedt C., von Buuren T., Franco N., Terminello L. J., Keim M., Reuscher G., Lugauer H., Waag A},
doi = {10.1103/PhysRevB.73.115212},
faupublication = {no},
journal = {Physical Review B},
pages = {115212/1-115212/6},
peerreviewed = {Yes},
support_note = {Author relations incomplete. You may find additional data in field 'author{\_}hint'},
title = {{Resonant} inelastic soft x-ray scattering of {Be} chalcogenides},
volume = {73},
year = {2006}
}
@article{faucris.107234204,
abstract = {Spin‐crossover metal complexes are highly promising magnetic molecular switches for prospective molecule‐based devices. The spin‐crossover molecular photoswitches developed so far operate either at very low temperatures or in the liquid phase, which hinders practical applications. Herein, we present a molecular spin‐crossover iron(II) complex that can be switched between paramagnetic high‐spin and diamagnetic low‐spin states with light at room temperature in the solid state. The reversible photoswitching is induced by alternating irradiation with ultraviolet and visible light and proceeds at the molecular level.},
author = {Rösner, Benedikt and Milek, Magdalena and Witt, Alexander and Gobaut, Benoit and Torelli, Piero and Fink, Rainer and Khusniyarov, Marat},
doi = {10.1002/anie.201504192},
faupublication = {yes},
journal = {Angewandte Chemie},
keywords = {molecular switches, photochromism, photomagnetism, spin‐crossover, X‐ray absorption spectroscopy},
pages = {12976-12980},
peerreviewed = {unknown},
title = {{Reversible} {Photoswitching} of a {Spin}‐{Crossover} {Molecular} {Complex} in the {Solid} {State} at {Room} {Temperature}},
volume = {54},
year = {2015}
}
@article{faucris.203400371,
abstract = {Development of high-quality organic nanoparticle inks is a significant scientific challenge for the industrial production of solution processed organic photovoltaics (OPVs) with eco-friendly processing methods. In this work, we demonstrate a novel, robot-based, high throughput procedure performing automatic poly(3-hexylthio-phene-2,5-diyl) and indene-C-60 bisadduct nanoparticle ink synthesis in nontoxic alcohols. A novel methodology to prepare particle dispersions for fully functional OPVs by manipulating the particle size and solvent system was studied in detail. The ethanol dispersion with a particle diameter of around 80-100 nm exhibits reduced degradation, yielding a power conversion efficiency of 4.52%, which is the highest performance reported so far for water/alcohol-processed OPV devices. By successfully deploying the high-throughput robot-based approach for an organic nanoparticle ink preparation, we believe that the findings demonstrated in this work will trigger more research interest and effort on eco-friendly industrial production of OPVs.},
author = {Xie, Chen and Tang, Xiaofeng and Berlinghof, Marvin and Langner, Stefan and Chen, Shi and Späth, Andreas and Li, Ning and Fink, Rainer and Unruh, Tobias and Brabec, Christoph},
doi = {10.1021/acsami.8b03621},
faupublication = {yes},
journal = {ACS Applied Materials and Interfaces},
keywords = {organic photovoltaics;eco-friendly industrial production;robot-based systems;high-throughput organic nanoparticle synthesis;stable organic nanoparticle inks;organic nanoparticle size control},
pages = {23225-23234},
peerreviewed = {Yes},
title = {{Robot}-{Based} {High}-{Throughput} {Engineering} of {Alcoholic} {Polymer}: {Fullerene} {Nanoparticle} {Inks} for an {Eco}-{Friendly} {Processing} of {Organic} {Solar} {Cells}},
volume = {10},
year = {2018}
}
@article{faucris.276271216,
abstract = {Direct observation of organic molecular nanocrystals and their evolution using electron microscopy is extremely challenging, due to their radiation sensitivity and complex structure. Here, we introduce 4D-scanning confocal electron diffraction (4D-SCED), which enables direct in situ observation of bulk heterojunction (BHJ) thin films. 4D-SCED combines confocal electron optic setup with a pixelated detector to record focused spot-like diffraction patterns with high angular resolution, using an order of magnitude lower dose than previous methods. We apply it to study an active layer in organic solar cells, namely DRCN5T:PC71BM BHJ thin films. Structural details of DRCN5T nano-crystallites oriented both in- and out-of-plane are imaged at ~5 nm resolution and dose budget of ~5 e−/Å2. We use in situ annealing to observe the growth of the donor crystals, evolution of the crystal orientation, and progressive enrichment of PC71BM at interfaces. This highly dose-efficient method opens more possibilities for studying beam sensitive soft materials.
2-based devices, which, however, is not observed for SAM-based devices at these low frequencies. It is experimentally demonstrated that ion migration can be considerably suppressed by carefully engineering SAM interfaces, which allows effectively suppressing hysteresis and unstable diode behavior in the frequency regime between ≈1 and 100 Hz. It is suggested that a reduced density of ionic defects in combination with the absence of charge carrier accumulation at the interface is the main physical origin for the reduced hysteresis.},
author = {Hou, Yi and Scheiner, Simon and Tang, Xiaofeng and Gasparini, Nicola and Richter, Moses and Li, Ning and Schweizer, Peter and Chen, Shi and Chen, Haiwei and Ramírez Quiroz, César Omar and Du, Xiaoyan and Matt, Gebhard and Osvet, Andres and Spiecker, Erdmann and Fink, Rainer and Hirsch, Andreas and Halik, Marcus and Brabec, Christoph},
doi = {10.1002/admi.201700007},
faupublication = {yes},
journal = {Advanced Materials Interfaces},
peerreviewed = {Yes},
title = {{Suppression} of {Hysteresis} {Effects} in {Organohalide} {Perovskite} {Solar} {Cells}},
url = {http://onlinelibrary.wiley.com/doi/10.1002/admi.201700007/abstract},
year = {2017}
}
@article{faucris.114578684,
abstract = {The successful integration of electron detection into an existing scanning transmission x-ray microspectroscope (STXM) at the Swiss Light Source is demonstrated. In conventional x-ray detection using a photomultiplier, STXM offers mainly bulk sensitivity combined with high lateral resolution. However, by implementation of a channeltron electron multiplier, the surface sensitivity can be established by the detection of secondary electrons emitted from the sample upon resonant excitation. We describe the experimental setup and discuss several relevant aspects, in particular the schemes to correct for self-absorption in the specimen due to back illumination in case of thicker films. © 2010 American Institute of Physics.},
author = {Hub, Christian and Wenzel, Stephan and Raabe, J. and Ade, Harald and Fink, Rainer},
doi = {10.1063/1.3360813},
faupublication = {yes},
journal = {Review of Scientific Instruments},
peerreviewed = {Yes},
title = {{Surface} sensitivity in scanning transmission x-ray microspectroscopy using secondary electron detection},
volume = {81},
year = {2010}
}
@article{faucris.111811084,
abstract = {The organic semiconductor silver-tetracyanoquinodimethane (Ag-TCNQ) exhibits electrical switching and memory characteristics. Employing a scanning tunnelling microscopy setup inside a transmission electron microscope, the switching behaviour of individual Ag-TCNQ nanowires (NWs) is investigated in detail. For a large number of NWs, the switching between a high (OFF) and a low (ON) resistance state was successfully stimulated by negative bias sweeps. Fitting the experimental I-V curves with a Schottky emission function makes the switching features prominent and thus enables a direct evaluation of the switching process. A memory cycle including writing, reading and erasing features is demonstrated at an individual NW. Moreover, electronic failure mechanisms due to Joule heating are discussed. These findings have a significant impact on our understanding of the switching behaviour of Ag-TCNQ.},
author = {Ran, Ke and Rösner, Benedikt and Butz, Benjamin and Fink, Rainer and Spiecker, Erdmann},
doi = {10.1088/0957-4484/27/42/425703},
faupublication = {yes},
journal = {Nanotechnology},
keywords = {Ag-TCNQ nanowires;in situ transmission electron microscopy;electrical switching;organic memory device;organic electronics},
peerreviewed = {Yes},
title = {{Switching} behaviour of individual {Ag}-{TCNQ} nanowires: an in situ transmission electron microscopy study},
volume = {27},
year = {2016}
}
@article{faucris.113837504,
abstract = {We report a photoemission study of the systematics of the 4f electronic structure of a family of rare-earth organic compounds. Resonant photoemission has been used to determine the binding energies of the 4f ground states, relative to those of the ligand orbitals, of a number of rare-earth tris-8-hydroxyquinolines (REQ's). Using an empirical model these results have been extrapolated, to the full series (Ce-Lu) of REQ's. It is found that in all cases, with the possible exception of Ce, the energy of the 4f ground state is less than that of the highest occupied molecular orbital, and therefore individual holes on lanthanide sites will not be stable.},
author = {Fink, Rainer and Umbach, Eberhard and et al.},
author_hint = {Thompson J., Arima V., Zou Y., Fink R., Umbach E., Cingolani R., Blyth R.I.R.},
doi = {10.1103/PhysRevB.70.153104},
faupublication = {no},
journal = {Physical Review B},
peerreviewed = {Yes},
support_note = {Author relations incomplete. You may find additional data in field 'author{\_}hint'},
title = {{Systematics} of the 4f energies in a series of rare-earth organic complexes determined by resonant photoemission},
volume = {70},
year = {2004}
}
@article{faucris.257611661,
abstract = {The ability of a series of bridged triarylamines, so‐called N‐heterotriangulenes, to form multilayer‐type 2D‐extended films via a solution‐based processing method was examined using complementary microscopic techniques. We found that the long‐range order, crystallinity, and layer thickness decisively depend on the nature of the substituents attached to the polycyclic backbone. Owing to their flat core unit, compounds exhibiting a carbonyl unit at the bridge position provide a superior building block as compared to thioketone‐bridged derivatives. In addition, nature and length of the peripheral substituents affect the orientation of the aromatic core unit within highly crystalline films. Hence, our results stress the significance of a suitable molecular framework and provide deeper understanding of structure formation in 2D‐confined surroundings for such compounds.