Article Title

The impact of fluorination on both donor polymer and non-fullerene acceptor: The more fluorine, the merrier

Authors

Nicole Bauer, Department of Chemistry, University of North Carolina at Chapel Hill, North Carolina 27599, USA
Qianqian Zhang, Department of Chemistry, University of North Carolina at Chapel Hill, North Carolina 27599, USA
Jeromy James Rech, Department of Chemistry, University of North Carolina at Chapel Hill, North Carolina 27599, USA
Shuixing Dai, Department of Materials Science and Engineering, College of Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry Education, Peking University, Beijing 100871, China
Zhengxing Peng, Department of Physics and ORaCEL, North Carolina State University, Raleigh, North Carolina 27695, USA
Harald Ade, Department of Physics and ORaCEL, North Carolina State University, Raleigh, North Carolina 27695, USA
Jiayu Wang, Department of Materials Science and Engineering, College of Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry Education, Peking University, Beijing 100871, China
Xiaowei Zhan, Department of Materials Science and Engineering, College of Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry Education, Peking University, Beijing 100871, China
Wei You, Department of Chemistry, University of North Carolina at Chapel Hill, North Carolina 27599, USA

Keywords

organic solar cells, non-fullerene acceptors, fluorination, bulk heterojunction

Abstract

Fluorination of the donor polymer or non-fullerene acceptor (NFA) in an organic photovoltaic device is an effective method to improve device efficiency. Although there have been many studies on donor polymer fluorination, blends containing both a fluorinated donor and fluorinated NFA have rarely been reported. In this study, we use two donor polymers (4’-FT-HTAZ and 4’-FT-FTAZ) and two NFAs (ITIC-Th and ITIC-Th1) with different amounts of fluorine (from 2F to 6F) to investigate how the degree of fluorination in a blend impacts device performance. We find that fluorinating the NFA leads to a higher short-circuit current density (Jsc) and fill factor (FF), however, the open-circuit voltage (Voc) is decreased due to a depressed lowest unoccupied molecular orbital (LUMO) level. Adding additional fluorine to the donor polymer does not have a large effect on the Jsc or FF, but it does lead to an improved Voc. By fluorinating the NFA and having more fluorine on the donor polymer, we obtain both a high Jsc and Voc simultaneously, leading to a power conversion efficiency over 10% in the case of 4’-FT-FTAZ:ITIC-Th1, which has the most amount of fluorine (6F).

Graphical Abstract

DOI

https://doi.org/10.1007/s12274-019-2362-3

Publisher

Tsinghua University Press

Recommended Citation

Nicole Bauer,Qianqian Zhang,Jeromy James Rech,Shuixing Dai,Zhengxing Peng,Harald Ade,Jiayu Wang,Xiaowei Zhan,Wei You, The impact of fluorination on both donor polymer and non-fullerene acceptor: The more fluorine, the merrier. NanoRes.2019, 12(9): 2400–2405