Suppressing Co-Crystallization of Halogenated Non-Fullerene Acceptors for Thermally Stable Ternary Solar Cells

Sandra Hultmark, Sri Harish Kumar Paleti, Albert Harillo, Sara Marina, Ferry Anggoro Ardy Nugroho, Yanfeng Liu, Leif K. E. Ericsson, Ruipeng Li, Jaime Martín, Jonas Bergqvist, Christoph Langhammer, Fengling Zhang, Liyang Yu, Mariano Campoy-Quiles, Ellen Moons, Derya Baran, Christian Müller

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

While photovoltaic blends based on non-fullerene acceptors are touted for their thermal stability, this type of acceptor tends to crystallize, which can result in a gradual decrease in photovoltaic performance and affects the reproducibility of the devices. Two halogenated indacenodithienothiophene-based acceptors that readily co-crystallize upon mixing are studied, which indicates that the use of an acceptor mixture alone does not guarantee the formation of a disordered mixture. The addition of the donor polymer to the acceptor mixture readily suppresses the crystallization, which results in a fine-grained ternary blend with nanometer-sized domains that do not coarsen due to a high Tg ≈ 200 °C. As a result, annealing at temperatures of up to 170 °C does not markedly affect the photovoltaic performance of ternary devices, in contrast to binary devices that suffer from acceptor crystallization in the active layer. The results indicate that the ternary approach enables the use of high-temperature processing protocols, which are needed for upscaling and high-throughput fabrication of organic solar cells. Further, ternary devices display a stable photovoltaic performance at 130 °C for at least 205 h, which indicates that the use of acceptor mixtures allows to fabricate devices with excellent thermal stability.
Original languageEnglish (US)
Pages (from-to)2005462
JournalAdvanced Functional Materials
DOIs
StatePublished - Oct 14 2020

Bibliographical note

KAUST Repository Item: Exported on 2020-10-23
Acknowledged KAUST grant number(s): OSR-2018-CPF-4106
Acknowledgements: .H. and S.H.K.P. contributed equally to this work. The authors acknowledge the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under OSR-2018-CPF-4106 and the Knut and Alice Wallenberg Foundation through the project “Mastering Morphology for Solution-borne Electronics” (2016.0059) for funding. M.C.-Q. and A.H. acknowledge the European Research Council (ERC) for funding under grant agreement no. 648901. The authors thank MCIU for a Ramón y Cajal contract, Ikerbasque Foundation for the Fellow program (J.M) and grants Ref. PGC2018-094620-A-100, SEV-2015-0496 and PGC2018-095411-B-100. L.Y. thanks the National Nature Science Foundation of China (NSFC 21905185) for financial support. The authors thank the National Synchrotron Light Source II, Brookhaven National Lab (Suffolk, Upton, New York, USA) for beamtime.

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