Rubidium chloride doping TiO2 for efficient and hysteresis-free perovskite solar cells with decreasing traps

Adjusting the electron transport layer (ETL) is an effective method to improve the power conversion efficiency (PCE) of perovskite solar cells (PSCs) as well as suppress their hysteresis. In this study, we report that RbCl doping TiO 2 can enhance the crystallinity of perovskite and reduce hysteresis as well. As RbCl crystallite has a polyhedral structure and lattice parameters similar to those of the perovskite by calculation confirmed. According to the seed-mediated growth theory, seed-mediated perovskite formation results in a dense and uniform active layer with excellent crystallinity and low trap density, which can reduce the interfacial charge accumulation and carrier recombination. Consequently, the PSCs with the RbCl-doping ETL show remarkably enhanced performance (from 18.67% to 20.75%). Impressively, negligible hysteresis, high fill factor (FF, over 80%) can be observed for the perovskite with the modified ETL. This work is expected to provide a viable path to design a simple-processing ETL for efficient PSCs.