Donor polymer fluorination doubles the efficiency in non-fullerene organic photovoltaics. Issue 43 (18th October 2017)

• Record Type: Journal Article
• Authors: Bauer, Nicole; Zhang, Qianqian; Zhu, Jingshuai; Peng, Zhengxing; Yan, Liang; Zhu, Chenhui; Ade, Harald; Zhan, Xiaowei; You, Wei
• Is Part Of: Journal of materials chemistry. Volume 5:Issue 43(2017)
• Page Start: 22536
• Page End: 22541
• Publication Date: 2017-10-18
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c7ta07882j
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Donor polymer fluorination in ITIC-based device led to a large increase in the current and an efficiency twice that of the non-fluorinated polymer based device. Abstract : Donor polymer fluorination has proven to be an effective method to improve the power conversion efficiency of fullerene-based polymer solar cells (PSCs). However, this fluorine effect has not been well-studied in systems containing new, non-fullerene acceptors (NFAs). Here, we investigate the impact of donor polymer fluorination in NFA-based solar cells by fabricating devices with either a fluorinated conjugated polymer (FTAZ) or its non-fluorinated counterpart (HTAZ) as the donor polymer and a small molecule NFA (ITIC) as the acceptor. We found that, similar to fullerene-based devices, fluorination leads to an increased open circuit voltage ( V oc ) from the lowered HOMO level and improved fill factor (FF) from the higher charge carrier mobility. More importantly, donor polymer fluorination in this NFA-based system also led to a large increase in short circuit current ( J sc ), which stems from the improved charge transport and extraction in the fluorinated device. This study demonstrates that fluorination is also advantageous in NFA-based PSCs and may improve performance to a higher extent than in fullerene-based PSCs. In the context of other recent reports on demonstrating higher photovoltaic device efficiencies with fluorinated materials, fluorination appears to be a valuable strategy in the design and synthesis of future donors and acceptors for PSCs.