Effect of Quencher, Geometry, and Light Outcoupling on the Determination of Exciton Diffusion Length in Nonfullerene Acceptors

Valentina Belova*, Aleksandr Perevedentsev, Julien Gorenflot*, Catherine S.P. De Castro, Miquel Casademont-Viñas, Sri H.K. Paleti, Safakath Karuthedath, Derya Baran, Frédéric Laquai, Mariano Campoy-Quiles*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The correct determination of the exciton diffusion length (LD) in novel organic photovoltaics (OPV) materials is an important, albeit challenging, task required to understand these systems. Herein, a high-throughput approach to probe LD in nonfullerene acceptors (NFAs) is reported, that builds upon the conventional photoluminescence (PL) surface quenching method using NFA layers with a graded thickness variation in combination with spectroscopic PL mapping. The method is explored for two archetypal NFAs, namely, ITIC and IT-4F, using PEDOT:PSS and the donor polymer PM6 as two distinct and practically relevant quencher materials. Interestingly, conventional analysis of quenching efficiency as a function of acceptor layer thickness results in a threefold difference in LD values depending on the specific quencher. This discrepancy can be reconciled by accounting for the differences in light in- and outcoupling efficiency for different multilayer architectures. In particular, it is shown that the analysis of glass/acceptor/PM6 structures results in a major overestimation of LD, whereas glass/acceptor/PEDOT:PSS structures give no significant contribution to outcoupling, yielding LD values of 6−12 and 8−18 nm for ITIC and IT-4F, respectively. Hence, practical guidelines for quencher choice, sample geometries, and analysis approach for the accurate assessment of LD are provided.

Original languageEnglish (US)
Article number2100822
JournalSolar RRL
Volume6
Issue number8
DOIs
StatePublished - Aug 2022

Bibliographical note

Funding Information:
V.B., A.P., and J.G. contributed equally to this work. The authors acknowledge that this research was financially supported by the European Research Council (ERC) under grant agreement no. 648901. The authors also acknowledge financial support from the Spanish Ministry of Science and Innovation through the Severo Ochoa Program for Centers of Excellence in R&D (CEX2019‐000917‐S) and project PGC2018‐095411‐B‐I00. This publication was based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award no: OSR‐2018‐CARF/CCF‐3079 and award no. OSR‐CRG2018‐3746. The authors thank Anastasia Ragulskaya (The University of Tübingen) for contributing to the development of the computational model.

Funding Information:
V.B., A.P., and J.G. contributed equally to this work. The authors acknowledge that this research was financially supported by the European Research Council (ERC) under grant agreement no. 648901. The authors also acknowledge financial support from the Spanish Ministry of Science and Innovation through the Severo Ochoa Program for Centers of Excellence in R&D (CEX2019-000917-S) and project PGC2018-095411-B-I00. This publication was based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award no: OSR-2018-CARF/CCF-3079 and award no. OSR-CRG2018-3746. The authors thank Anastasia Ragulskaya (The University of Tübingen) for contributing to the development of the computational model.

Publisher Copyright:
© 2021 The Authors. Solar RRL published by Wiley-VCH GmbH.

Keywords

  • exciton diffusion lengths
  • light in- and outcoupling
  • nonfullerene acceptors
  • photoluminescence quenching

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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