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Issue 45, 2020
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Effects of polymer crystallinity on non-fullerene acceptor based organic solar cell photostability

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Abstract

While there has been rapid progress made in the performance of organic photovoltaic (OPV) cells in recent years, the device stability remains a major bottleneck for commercialization. In this work, we blended a stable acceptor (O-IDTBR) with two photostable donors (PTB7-Th and PffBT4T-2OD) having different polymer crystallinity, and the resulting devices show a significant difference in the OPV degradation rate. The OPV devices employing a highly crystalline polymer PffBT4T-2OD as an active layer show a good resistance against light soaking, maintaining 80% of the initial power conversion efficiency (PCE) up to 100 hours, while the devices employing an amorphous polymer PTB7-Th as an active layer show a significant PCE loss in the initial 20 hours mainly due to a rapid loss of the fill factor. By carrying out a comprehensive analysis of the device degradation mechanisms, we conclude that the origin for the PTB7-Th:O-IDTBR device degradation is the formation of mid-gap states under continuous sunlight illumination, leading to a significant drop in electron mobility. Device simulation revealed that deep traps act as charge recombination centers and increase the trap-assisted recombination rate, lowering the FF and Jsc.

Graphical abstract: Effects of polymer crystallinity on non-fullerene acceptor based organic solar cell photostability

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Supplementary files

Article information


Submitted
20 Aug 2020
Accepted
13 Oct 2020
First published
13 Oct 2020

J. Mater. Chem. C, 2020,8, 16092-16099
Article type
Paper

Effects of polymer crystallinity on non-fullerene acceptor based organic solar cell photostability

X. Yi, C. H. Y. Ho, B. Gautam, L. Lei, A. H. Chowdhury, B. Bahrami, Q. Qiao and F. So, J. Mater. Chem. C, 2020, 8, 16092
DOI: 10.1039/D0TC03969A

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