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.