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Impact of Bimolecular Recombination on the Fill Factor of Fullerene and Nonfullerene-Based Solar Cells: A Comparative Study of Charge Generation and Extraction

Seyed Mehrdad Hosseini, Steffen Roland, Jona Kurpiers, Zhiming Chen, Kai Zhang, Fei Huang, Ardalan Armin Orcid Logo, Dieter Neher, Safa Shoaee

The Journal of Physical Chemistry C, Volume: 123, Issue: 11, Pages: 6823 - 6830

Swansea University Author: Ardalan Armin Orcid Logo

Abstract

Power conversion efficiency of nonfullerene organic solar cells have now increased beyond the record of their fullerene-based counterparts. There remain many fundamental questions about their working principles such as charge generation and extraction and losses in these systems. Herein, we present...

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Published in: The Journal of Physical Chemistry C
ISSN: 1932-7447 1932-7455
Published: 2019
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa49632
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Abstract: Power conversion efficiency of nonfullerene organic solar cells have now increased beyond the record of their fullerene-based counterparts. There remain many fundamental questions about their working principles such as charge generation and extraction and losses in these systems. Herein, we present a comparative study of bulk heterojunction solar cells composed of a recently introduced nappthothiadiazole-based polymer (NT812) as the electron donor and two different acceptor molecules, namely PCBM[70] and ITIC. A comparison between photovoltaic performance of these two types of solar cells reveals that the open circuit voltage (Voc) of NT812:ITIC based solar cell is larger but the fill factor (FF) lower than that of NT812:PCBM[70] device. We find the key reason behind this reduced FF in the ITIC-based device to be faster non-geminate recombination relative to NT812:PCBM[70] system, which has previously been assigned to sub-optimum morphology. Nevertheless, NT812:ITIC system is more emissive than NT812:PCBM[70] resulting in smaller non-radiative Voc-loss. Suppression of bimolecular recombination together with reduced non-radiative Voc-loss can be considered as a key optimization route in the development of non-fullerene-based solar cells.
College: College of Science
Issue: 11
Start Page: 6823
End Page: 6830