Near‐Infrared Electron Acceptors with Fluorinated Regioisomeric Backbone for Highly Efficient Polymer Solar Cells. Issue 52 (6th November 2018)

• Record Type: Journal Article
• Authors: Chen, Fang‐Xiao; Xu, Jing‐Qi; Liu, Zhi‐Xi; Chen, Ming; Xia, Ruoxi; Yang, Yongchao; Lau, Tsz‐Ki; Zhang, Yingzhu; Lu, Xinhui; Yip, Hin‐Lap; Jen, Alex K.‐Y.; Chen, Hongzheng; Li, Chang‐Zhi
• Is Part Of: Advanced materials. Volume 30:Issue 52(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-11-06
• Subjects: near‐infrared absorption -- nonfullerene acceptors -- polymer solar cells -- tandem devices; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201803769
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Solar photon‐to‐electron conversion with polymer solar cells (PSCs) has experienced rapid development in the recent few years. Even so, the exploration of molecules and devices in efficiently converting near‐infrared (NIR) photons into electrons remains critical, yet challenging. Herein presented is a family of near‐infrared nonfullerene acceptors (NIR NFAs, T1–T4) with fluorinated regioisomeric A–Aπ–D–Aπ–A backbones for constructing efficient single‐junction and tandem PSCs with photon response up to 1000 nm. It is found that the tuning of the regioisomeric bridge (Aπ) and fluoro (F)‐substituents on a molecular skeleton strongly influences the backbone conformation and conjugation, leading to the optimized optoelectronic and stable stacking of resultant NFAs, which eventually impacts the performance of derived PSCs. In PSCs, the proximal NFAs with varied F‐atoms (T1–T3) mostly outperform than that of distal NFA (T4). Notably, single‐junction PSC with PTB7‐Th:T2 blend can reach 10.87% power conversion efficiency (PCE), after implementing a solvent additive to improve blend morphology. Moreover, efficient tandem PSCs are fabricated through integrating such NIR cells with mediate bandgap nonfullerene‐based subcells, to achieve a PCE of 14.64%. The results reveal the structural design of organic semiconductor and device with improved photovoltaic performance. Abstract : Near‐infrared nonfullerene acceptors (NIR NFAs, T1 –T4) with fluorinated regioisomeric A –Aπ –D –Aπ –A backbones are developed for high‐performance polymer solar cells (PSCs), in which proximal NFAs with varied F‐atoms (T1–T3) largely outperform distal NFA (T4). Particularly, single‐junction PSCs with a PTB7‐Th:T2 blend can achieve 10.87% power conversion efficiency (PCE), and tandem PSCs through integrating with an ITIC:PBDB‐T blend reach a PCE of 14.64%.