Self‐Induced A‐B‐A Structure Enables Efficient Wide‐Bandgap Perovskite Solar Cells and Tandems

Abstract Wide‐bandgap (WBG) perovskite solar cells (PSCs), due to their tunable bandgap, can be integrated into tandem cell configurations with narrow‐bandgap solar cells to overcome the shockley‐queisser (SQ) limitation. However, the main obstacles limiting their performance are poor crystallinity and light‐induced halide segregation. To achieve high performance in WBG PSCs, this study reports a dual‐molecule cooperative strategy involving the introduction of 1‐benzyl‐3‐methylimidazolium bromide (BzMIM Br) as an additive and the introduction of 6‐fluoropyrimidine‐2,4‐ diamine (DMFP) as a passivation layer. DMFP self‐induced penetration to the bottom of the perovskite, forming an A‐B‐A structure with BzMIM Br, through utilizing multisite integration with uncoordinated Pb 2+ , constructing internal molecular bridges. Research findings indicate that the A‐B‐A structure with uniform potential distribution can interact with the perovskite in a step‐like manner, suppressing halide segregation, and replenishing the vacancy defects. Results demonstrate power conversion efficiencies (PCEs) of 22.77% and 18.54% for inverted PSCs with effective areas of 0.043 and 1.0 cm 2 , respectively. Unencapsulated devices retain 95% of initial efficiency after 1500 h of continuous illumination under one‐sun equivalent conditions in a nitrogen atmosphere. Additionally, the PCE of the prepared semi‐transparent WBG devices reached 19.60%, while the PCE of the 4‐terminal all‐perovskite tandem device reached 26.18%.