Understanding the Role of Order in Y-Series Non-Fullerene Solar Cells to Realize High Open-Circuit Voltages

Lorena Perdigón-Toro, Le Quang Phuong, Fabian Eller, Guillaume Freychet, Elifnaz Saglamkaya, Jafar Iqbal Khan, Qingya Wei, Stefan Zeiske, Daniel Kroh, Stefan Wedler, Anna Köhler, Ardalan Armin, Frédéric Laquai, Eva M. Herzig, Yingping Zou, Safa Shoaee, Dieter Neher

Research output: Contribution to journalArticlepeer-review

Abstract

Non-fullerene acceptors (NFAs) as used in state-of-the-art organic solar cells feature highly crystalline layers that go along with low energetic disorder. Here, the crucial role of energetic disorder in blends of the donor polymer PM6 with two Y-series NFAs, Y6, and N4 is studied. By performing tempera-ture-dependent charge transport and recombination studies, a consistent picture of the shape of the density of state distributions for free charges in the two blends is developed, allowing an analytical description of the dependence of the open-circuit voltage VOC on temperature and illumination intensity. Disorder is found to influence the value of the VOC at room temperature, but also its progression with temperature. Here, the PM6:Y6 blend benefits sub-stantially from its narrower state distributions. The analysis also shows that the energy of the equilibrated free charge population is well below the energy of the NFA singlet excitons for both blends and possibly below the energy of the populated charge transfer manifold, indicating a down-hill driving force for free charge formation. It is concluded that energetic disorder of charge-separated states has to be considered in the analysis of the photovoltaic properties, even for the more ordered PM6:Y6 blend.
Original languageEnglish (US)
Pages (from-to)2103422
JournalAdvanced Energy Materials
DOIs
StatePublished - Feb 3 2022

Bibliographical note

KAUST Repository Item: Exported on 2022-02-09
Acknowledged KAUST grant number(s): OSR-CARF/CCF-3079
Acknowledgements: This work has been funded by the Alexander von Humboldt Foundation (Sofja Kovalewskaja-Award) and from the Deutsche Forschungsgemeinschaft, DFG, German Research Foundation through the project Fabulous (project number 450968074) and HIOS (project number 182087777 – SFB 951), as well as project number 3923306670. E.M.H. and F.E. acknowledge funding from SolarEraNet (No. NFA4R2ROPV). F.E. thanks the Elite Study Program Macromolecular Science within the Elite Network of Bavaria (ENB) for support. This research used the Soft Matter Interfaces Beamline (SMI, Beamline 12-ID) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No: OSR-CARF/CCF-3079. Q.W. and Y.Z. acknowledge National Natural Science Foundation of China (No. 52125306). A.A. acknowledges support from the Welsh Government's Sêr Cymru II Rising Star and Capacity Builder Accelerator Programs through the European Regional Development Fund, Welsh European Funding Office, and Swansea University Strategic Initiative in Sustainable Advanced Materials.

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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