The synergistic effect of fluorine atom and alkyl chain positions in enhancing organic photovoltaic open-circuit voltage and morphology miscibility

A key to improving the power conversion efficiency (PCE) of Y6 -based non-fullerene based organic solar cells (OSCs) is the development of a high open-circuit voltage ( V oc ) polymer. In recent years, side-chain engineering has become a promising strategy for researchers to modulate and realize hig...

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Published in:Sustainable energy & fuels 2022-05, Vol.6 (1), p.249-2497
Main Authors: Ni, Jianling, Kang, Hui, Xue, Xiaonan, Zheng, Bing, Zhang, Yuan, Huo, Lijun
Format: Article
Language:English
Subjects:
Copolymers
Energy conversion efficiency
Fluorination
Fluorine
Fullerenes
Hole mobility
Miscibility
Open circuit voltage
Photovoltaic cells
Photovoltaics
Polymers
Solar cells
Synergistic effect
Voltage
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Summary:A key to improving the power conversion efficiency (PCE) of Y6 -based non-fullerene based organic solar cells (OSCs) is the development of a high open-circuit voltage ( V oc ) polymer. In recent years, side-chain engineering has become a promising strategy for researchers to modulate and realize high V oc . In this study, we adopted a new side-chain to coordinate the molecular crystallinity and miscibility, affording a copolymer L19 , in which the benzodithiophene (BDT) and dithienobenzothiadiazole (DTBT) units were used as the electron-sufficient and -defective units, respectively. As a comparison, a non-fluorinated analogue L18 was also synthesized. As a result, the OSCs based on L19:Y6 exhibited an impressive V oc than L18 -based devices (0.93 V vs. 0.89 V) due to further fluorination. L19 had the higher hole mobility of 1.6 × 10 −3 cm 2 V −1 s −1 than L18 of 7.13 × 10 −4 cm 2 V −1 s −1 , and better miscibility, thereby achieving a higher PCE of 11.73% for L19 than that of L18 (6.44%). Moreover, the high V oc of 0.93 V is a good reference for Y-series small molecular acceptor systems. These results indicate that the new side-chains of L19 can synergistically regulate the HOMO level and miscibility between the donor and acceptor, providing more options for the development of a high open-circuit voltage polymer for Y-series based non-fullerene systems. We designed and synthesized two new conjugated polymers, L18 and L19 , and used them as polymer donors to blend with Y6 acceptors for high open-circuit voltage photovoltaic polymers.
ISSN:2398-4902
2398-4902
DOI:10.1039/d1se01801a