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@article{faucris.108247964,
abstract = {The performance of organic solar cells is determined by the delicate, meticulously optimized bulk-heterojunction microstructure, which consists of finely mixed and relatively separated donor/acceptor regions. Here we demonstrate an abnormal strong burn-in degradation in highly efficient polymer solar cells caused by spinodal demixing of the donor and acceptor phases, which dramatically reduces charge generation and can be attributed to the inherently low miscibility of both materials. Even though the microstructure can be kinetically tuned for achieving high-performance, the inherently low miscibility of donor and acceptor leads to spontaneous phase separation in the solid state, even at room temperature and in the dark. A theoretical calculation of the molecular parameters and construction of the spinodal phase diagrams highlight molecular incompatibilities between the donor and acceptor as a dominant mechanism for burn-in degradation, which is to date the major short-time loss reducing the performance and stability of organic solar cells.},
author = {Li, Ning and Perea, José Darío and Kassar, Thaer and Richter, Moses and Heumüller, Thomas and Matt, Gebhard and Hou, Yi and Güldal, Nusret Sena and Chen, Haiwei and Chen, Shi and Langner, Stefan and Berlinghof, Marvin and Unruh, Tobias and Brabec, Christoph},
doi = {10.1038/ncomms14541},
faupublication = {yes},
journal = {Nature Communications},
peerreviewed = {Yes},
title = {{Abnormal} strong burn-in degradation of highly efficient polymer solar cells caused by spinodal donor-acceptor demixing},
volume = {8},
year = {2017}
}
@article{faucris.210192939,
abstract = {Mesoscale-structured materials offer broad opportunities in extremely diverse
applications owing to their high surface areas, tunable surface energy, and
large pore volume. These benefits may improve the performance of materials
in terms of carrier density, charge transport, and stability. Although metal
oxides–based mesoscale-structured materials, such as TiO2, predominantly
hold the record efficiency in perovskite solar cells, high temperatures (above
400 °C) and limited materials choices still challenge the community. A novel
route to fabricate organic-based mesoscale-structured interfaces (OMI) for
perovskite solar cells using a low-temperature and green solvent–based process
is presented here. The efficient infiltration of organic porous structures
based on crystalline nanoparticles allows engineering efficient “n-i-p” and
“p-i-n” perovskite solar cells with enhanced thermal stability, good performance,
and excellent lateral homogeneity. The results show that this method
is universal for multiple organic electronic materials, which opens the door to
transform a wide variety of organic-based semiconductors into scalable n- or
p-type porous interfaces for diverse advanced applications.
halides are attracting intense research interests due to their promising
stability and high efficiency. A tremendous amount of 3D and 2D perovskite
compositions and configurations are causing a strong demand for high
throughput synthesis and characterization. Furthermore, wide bandgap
(≈1.75 eV) perovskites as promising top-cell materials for perovskite–silicon
tandem configurations require the screening of different compositions to
overcome photoinduced halide segregation and still yielding a high opencircuit
voltage (Voc). Herein, a home-made high throughput robot setup is
introduced performing automatic perovskite synthesis and characterization.
Subsequently, four kinds of compositions (i.e., cation mixtures of Cs–methylammonium
(MA), Cs– formamidinium (FA), MA–FA, and FA–MA) with an
optical bandgap of ≈1.75 eV are identified as promising device candidates.
For Cs–MA and Cs–FA films it is found that the Br–I phase segregation
indeed can be overcome. Moreover, Cs–MA, MA–FA, and Cs–FA based
devices exhibit an average Voc of 1.17, 1.17, 1.12 V, and their maximum values
approached 1.18, 1.19, 1.14 V, respectively, which are among the highest Voc
(≈1.2 V) values for ≈40% Br perovskite. These findings highlight that the high
throughput approach can effectively and efficiently accelerate the invention of
novel perovskites for advanced applications.},
author = {Chen, Shi and Hou, Yi and Chen, Haiwei and Tang, Xiaofeng and Langner, Stefan and Li, Ning and Stubhan, Tobias and Levchuk, Ievgen and Gu, Ening and Osvet, Andres and Brabec, Christoph},
doi = {10.1002/aenm.201701543},
faupublication = {yes},
journal = {Advanced Energy Materials},
peerreviewed = {unknown},
title = {{Exploring} the {Stability} of {Novel} {Wide} {Bandgap} {Perovskites} by a {Robot} {Based} {High} {Throughput} {Approach}},
url = {http://onlinelibrary.wiley.com/doi/10.1002/aenm.201701543/abstract},
year = {2017}
}
@article{faucris.106799044,
abstract = {Solution-processed oxo-functionalized graphene (oxo-G) is employed to substitute hydrophilic PEDOT:PSS as an anode interfacial layer for perovskite solar cells. The resulting devices exhibit a reasonably high power conversion efficiency (PCE) of 15.2% in the planar inverted architecture with oxo-G as a hole transporting material (HTM), and most importantly, deploy the full open-circuit voltage (V) of up to 1.1 V. Moreover, oxo-G effectively slows down the ingress of water vapor into the device stack resulting in significantly enhanced environmental stability of unpackaged cells under illumination with 80% of the initial PCE being reached after 500 h. Without encapsulation, ∼60% of the initial PCE is retained after ∼1000 h of light soaking under 0.5 sun and ambient conditions maintaining the temperature beneath 30 °C. Moreover, the unsealed perovskite device retains 92% of its initial PCE after about 1900 h under ambient conditions and in the dark. Our results underpin that controlling water diffusion into perovskite cells through advanced interface engineering is a crucial step towards prolonged environmental stability.},
author = {Chen, Haiwei and Hou, Yi and Halbig, Christian Eberhard and Chen, Shi and Zhang, Hong and Li, Ning and Guo, Fei and Tang, Xiaofeng and Gasparini, Nicola and Levchuk, Ievgen and Kahmann, Simon and Ramírez Quiroz, César Omar and Osvet, Andres and Eigler, Siegfried and Brabec, Christoph},
doi = {10.1039/c6ta03755k},
faupublication = {yes},
journal = {Journal of Materials Chemistry A},
keywords = {Engineering controlled terms: Cell engineering; Conducting polymers; Open circuit voltage; Perovskite; Slow light; Solar cells Environmental stability; Functionalized graphene; High power conversion; Hole-transporting materials; Interface engineering; Interfacial design; Inverted architectures; Solution-processed Engineering main heading: Perovskite solar cells},
pages = {11604-11610},
peerreviewed = {unknown},
title = {{Extending} the environmental lifetime of unpackaged perovskite solar cells through interfacial design},
volume = {4},
year = {2016}
}
@article{faucris.120979804,
abstract = {A power conversion efficiency of 11.8% is demonstrated for planar perovskite solar cell based on acid water-free poly(3,4-ethylenedioxythiophene) (PEDOT) as the hole-transporting layer. This efficiency is further improved to 14.2% using a pH neutralized PEDOT, which reduces the sub-gap defects at the surface of perovskite. All the active layers reported are solution-processed at temperatures below 140 °C making it compatible with roll-to-roll production.},
author = {Hou, Yi and Zhang, Hong and Chen, Wei and Chen, Shi and Ramírez Quiroz, César Omar and Azimi, Seyed Hamed and Osvet, Andres and Matt, Gebhard and Zeira, Eitan and Seuring, Jan and Kausch-Busies, Nina and Loevenich, Wilfried and Brabec, Christoph},
doi = {10.1002/aenm.201500543},
faupublication = {yes},
journal = {Advanced Energy Materials},
keywords = {low-temperature processing; perovskite solar cells; stabilities; water-free poly(3,4-ethylenedioxythiophene)},
peerreviewed = {unknown},
title = {{Inverted}, {Environmentally} {Stable} {Perovskite} {Solar} {Cell} with a {Novel} {Low}-{Cost} and {Water}-{Free} {PEDOT} {Hole}-{Extraction} {Layer}},
volume = {5},
year = {2015}
}
@article{faucris.106802784,
abstract = {An experiment was conducted to demonstrate that low-temperature processed NiO-based nanocrystal ink (LT-NiO) has the potential to form an almost loss-free hole selective interface for flat heterojunction perovskite-based solar cells. First, The patterned ITO substrates were ultrasonic cleaned with acetone and isopropanol for 10 min each. On cleaned ITO substrate, a dense and smooth layer of LT-NiO was deposited by spin coating and followed by annealing at 70?230°C for 10 min in air to remove organic components. The as-prepared perovskite precursor solution was filtered using 0.45 μm PTFE syringe filter and coated onto the ITO/LT-NiO substrate at a speed of 4000 r.p.m. for 35 s. J-V characteristics of all the devices were measured using a source measurement unit from BoTest. FTPS:FTPS-EQE measurements were carried out using a Vertex 70 from Brucker optics, equipped with QTH lamp, quartz beam splitter and external detector option. A major improvement in open circuit voltage is found by replacing PEDOT:PSS with LT-NiO. A detailed analysis reveals that LT-NiO significantly reduces non-radiative recombination at the PEDOT:PSS/perovskite interface and further enhances the radiative LED efficiency towards unity which brings open circuit voltage closer to the radiative limit.},
author = {Hou, Yi and Chen, Wei and Baran, Derya and Stubhan, Tobias and Luechinger, Norman A. and Hartmeier, Benjamin and Richter, Moses and Min, Jie and Chen, Shi and Ramírez Quiroz, César Omar and Li, Ning and Zhang, Hong and Heumüller, Thomas and Matt, Gebhard and Osvet, Andres and Forberich, Karen and Zhang, Zhi-Guo and Li, Yongfang and Winter, Benjamin and Schweizer, Peter and Spiecker, Erdmann and Brabec, Christoph},
doi = {10.1002/adma.201504168},
faupublication = {yes},
journal = {Advanced Materials},
keywords = {low temperature processing; nickel oxide; non-radiative voltage loss; perovskite solar cells},
pages = {5112-5120},
peerreviewed = {unknown},
title = {{Overcoming} the {Interface} {Losses} in {Planar} {Heterojunction} {Perovskite}-{Based} {Solar} {Cells}},
year = {2016}
}
@article{faucris.123736844,
abstract = {Photoinduced degradation is a critical obstacle for the real application of novel semiconductors for photovoltaic applications. In this paper, the photoinduced degradation of CHNHPbI in a vacuum and air (relative humidity 40%) is analyzed by ex situ and advanced in situ technologies. Without light illumination, CHNHPbI films slowly degrade under vacuum and air within 24 hours. However, we find that CHNHPbI converts to metallic lead (Pb) when exposed to vacuum and light illumination. Further, a series of lead salts (e.g. PbO, Pb(OH) and PbCO) are formed when CHNHPbI is degraded under environmental conditions, i.e. under the combination of light, oxygen and moisture. Photoinduced degradation is found to be determined by the environmental atmosphere as CHNHPbI films remain very stable under nitrogen conditions. The results from vacuum conditions underpin that the high volatility of the organic component (CHNHI) is in conflict with reaching excellent intrinsic stability due to its role in creating ion vacancies. The degradation in air suggests that both oxygen and water contribute to the fast photodecomposition of CHNHPbI into lead salts rather than water alone. Given these basic yet fundamental understandings, the design of hydrophobic capping layers becomes one prerequisite towards long-term stable perovskite-based devices.},
author = {Tang, Xiaofeng and Brandl, Marco and May, Benjamin and Levchuk, Ievgen and Hou, Yi and Richter, Moses and Chen, Haiwei and Chen, Shi and Kahmann, Simon and Osvet, Andres and Maier, Florian and Steinrück, Hans-Peter and Hock, Rainer and Matt, Gebhard and Brabec, Christoph},
doi = {10.1039/c6ta06497c},
faupublication = {yes},
journal = {Journal of Materials Chemistry A},
keywords = {Engineering controlled terms: Lead; Perovskite; Salts; Slow light Environmental conditions; Intrinsic stability; Light illumination; Organic components; Photo-decomposition; Photoinduced degradation; Photovoltaic applications; Real applications Engineering main heading: Photodegradation},
pages = {15896-15903},
peerreviewed = {unknown},
title = {{Photoinduced} degradation of methylammonium lead triiodide perovskite semiconductors},
volume = {4},
year = {2016}
}
@article{faucris.115870524,
abstract = {A smart photovoltaic window is designed and constructed by solution-processing a layer of thermochromic VO2 nanoparticles on top of a semitransparent organic solar cell. The prepared smart window not only produces electricity using the visible part of the solar spectrum but also saves energy via intelligently modulating the amount of NIR radiation passing through the device in response to ambient temperature.},
author = {Guo, Fei and Chen, Shi and Chen, Zhang and Luo, Hongjie and Gao, Yanfeng and Przybilla, Thomas and Spiecker, Erdmann and Osvet, Andres and Forberich, Karen and Brabec, Christoph},
doi = {10.1002/adom.201500314},
faupublication = {yes},
journal = {Advanced Optical Materials},
pages = {1524-1529},
peerreviewed = {Yes},
title = {{Printed} {Smart} {Photovoltaic} {Window} {Integrated} with an {Energy}-{Saving} {Thermochromic} {Layer}},
volume = {3},
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.108486884,
abstract = {Thin-film solar cell based on hybrid perovskites shows excellent light-to-power conversion efficiencies exceeding 22%. However, the mixed ionic-electronic semiconductor hybrid perovskite exhibits many unusual properties such as slow photocurrent instabilities, hysteresis behavior, and low-frequency giant capacitance, which still question us so far. This study presents a direct surface functionalization of transparent conductive oxide electrode with an ultrathin ≈2 nm thick phosphonic acid based mixed C60/organic self-assembled monolayer (SAM) that significantly reduces hysteresis. Moreover, due to the strong phosphonates bonds with indium tin oxide (ITO) substrates, the SAM/ITO substrates also exhibit an excellent recyclability merit from the perspective of cost effectiveness. Impedance studies find the fingerprint of an ion-based diffusion process in the millisecond to second regime for TiO2-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}
}