Insights into the effect of bromine?based organic salts on the efficiency and stability of wide bandgap perovskite

Wide bandgap perovskite solar cells (WB-PSCs) sustained serious deficit of open-circuit voltage (VOC) and instability in the development process, which limited full play their advantages, especially tandem cells. Surface passivation engineering alkyl amine halide salts has been used extensively to improve performance PSCs. Here, photovoltaic FA0.83Cs0.17 Pb(I0.8Br0.2)3 WB-PSCs based on methyl bromide (MABr) guanidine (GABr) was systematically investigated. It proved that both MABr GABr significantly passivate defects, resulting lower trap density. Eventually, efficiency arrives at 18.6% MABr-treated film, an improved VOC up 1.235 V obtained with a VOC-deficit only 415 mV, is one highest value for PSCs 1.65 eV bandgap. noted devices treated exhibited enhanced moisture stability than reference treated. X-Ray Diffraction (XRD) revealed likely cause severer phase transition ?-phase nonperovskite. This paper provides important insight surface strategies, need be considered simultaneously.