Polymer: Nonfullerene Bulk Heterojunction Solar Cells with Exceptionally Low Recombination Rates

Gasparini N, Salvador MF, Heumüller T, Richter M, Classen A, Shrestha S, Matt G, Holliday S, Strohm S, Egelhaaf HJ, Wadsworth A, Baran D, Mcculloch I, Brabec C (2017)

Publication Language: English

Publication Status: Published

Publication Type: Journal article, Original article

Publication year: 2017

Journal

Advanced Energy Materials Wiley

Publisher: Wiley-VCH Verlag

DOI: 10.1002/aenm.201701561

Abstract

Organic semiconductors are in general known to have an inherently lower charge carrier mobility compared to their inorganic counterparts. Bimolecular recombination of holes and electrons is an important loss mechanism and can often be described by the Langevin recombination model. Here, the device physics of bulk heterojunction solar cells based on a nonfullerene acceptor (IDTBR) in combination with poly(3-hexylthiophene) (P3HT) are elucidated, showing an unprecedentedly low bimolecular recombination rate. The high fill factor observed (above 65%) is attributed to non-Langevin behavior with a Langevin prefactor (β/βL) of 1.9 × 10-4. The absence of parasitic recombination and high charge carrier lifetimes in P3HT:IDTBR solar cells inform an almost ideal bimolecular recombination behavior. This exceptional recombination behavior is explored to fabricate devices with layer thicknesses up to 450 nm without significant performance losses. The determination of the photoexcited carrier mobility by time-of-flight measurements reveals a long-lived and nonthermalized carrier transport as the origin for the exceptional transport physics. The crystalline microstructure arrangement of both components is suggested to be decisive for this slow recombination dynamics. Further, the thickness-independent power conversion efficiency is of utmost technological relevance for upscaling production and reiterates the importance of understanding material design in the context of low bimolecular recombination. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Authors with CRIS profile

Nicola Gasparini Institute Materials for Electronics and Energy Technology (i-MEET) Michael Filipe Salvador Institute Materials for Electronics and Energy Technology (i-MEET) Thomas Heumüller Institute Materials for Electronics and Energy Technology (i-MEET) Moses Richter Institute Materials for Electronics and Energy Technology (i-MEET) Andrej Classen Institute Materials for Electronics and Energy Technology (i-MEET) Shreetu Shrestha Institute Materials for Electronics and Energy Technology (i-MEET) Gebhard Matt Institute Materials for Electronics and Energy Technology (i-MEET) Christoph Brabec Institute Materials for Electronics and Energy Technology (i-MEET)

Additional Organisation(s)

Graduiertenkolleg 1896/2 In situ Mikroskopie mit Elektronen, Röntgenstrahlen und Rastersonden Exzellenz-Cluster Engineering of Advanced Materials Interdisziplinäres Zentrum, Center for Nanoanalysis and Electron Microscopy (CENEM)

Involved external institutions

Imperial College London / The Imperial College of Science, Technology and Medicine GB United Kingdom (GB) Bayerisches Zentrum für Angewandte Energieforschung e.V. (ZAE Bayern) DE Germany (DE)

How to cite

APA:

Gasparini, N., Salvador, M.F., Heumüller, T., Richter, M., Classen, A., Shrestha, S.,... Brabec, C. (2017). Polymer: Nonfullerene Bulk Heterojunction Solar Cells with Exceptionally Low Recombination Rates. Advanced Energy Materials. https://dx.doi.org/10.1002/aenm.201701561

MLA:

Gasparini, Nicola, et al. "Polymer: Nonfullerene Bulk Heterojunction Solar Cells with Exceptionally Low Recombination Rates." Advanced Energy Materials (2017).

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