Optimization of crystallization dynamics in wide-bandgap bromine–iodine perovskite films for high-performance perovskite–organic tandem solar cells†

Abstract

The development of efficient and stable wide-bandgap (WBG) bromine–iodine halide perovskites (Br > 20%) is crucial for enhancing the performance of tandem solar cells. Nonetheless, phase separation of I–Br in WBG perovskites under illumination and heating significantly hinders the advancement of tandem devices. This phenomenon is primarily attributed to the uneven spatial distribution of halide ions in WBG films. Moroxydine hydrochloride was introduced into 1.85 eV I–Br mixed WBG perovskite films, effectively optimizing the crystallization dynamics of the perovskite and improving the film stability. Through this approach, a 1.85 eV WBG perovskite solar cell (PSC) was successfully fabricated, achieving a power conversion efficiency (PCE) of 18.76%, an open-circuit voltage (V_OC) of 1.387 V, and remarkable operational stability. When applied to perovskite–organic tandem solar cells, this method led to devices with a PCE of 25.98% and a V_OC of 2.210 V, setting a new record for the highest V_OC reported to date.