Junsheng Luo1 Zhongquan Wan1 Jianxing Xia1 Fei Han1 Lingling Chen2 Xuhui Zhu2 Ruilin Wang3 Chunyang Jia1

1, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
2, South China University of Technology, Guangzhou, Guangdong, China
3, Sichuan University, Chengdu, Sichuan, China

Perovskite solar cells (PSCs) have demonstrated high power conversion efficiency (PCE) but poor long-term stability and remarkable hysteresis. To date, the most efficient PSCs have the n-i-p device architecture and use Li-TFSI/t-BP as standard dopants for hole-transporting layer (HTL). However, such dopants not only induce deleterious effects on stability but also significantly affect the hysteresis of PSCs. Here, we demonstrate that a novel Lewis acid tris(pentafl uorophenyl)borane (B(C6F5)3) can be employed as an effective dopant for PTAA to realize a new record fill factor 0.81 in TiO2-based n-i-p PSCs and a record PCE as high as 19.01% among the ever reported PSCs based on single dopant in HTL, versus 17.77% for the control device with Li-TFSI/t-BP doped PTAA. To the best of our knowledge, it is the first case that PSC based on a single dopant for HTL shows higher efficiency than that of the state-of-the-art Li-TFSI/t-BP. Besides, the B(C6F5)3-based PSC displays lower J-V hysteresis and much better long-term stability up to 70 days in high humidity environment without encapsulation. We believe that this work opens up new avenue for high-efficiency, hysteresis-less and stable PSCs exploring novel dopants as alternatives to Li-TFSI/t-BP.