Improved performance of CH3NH3PbBr3 perovskite solar cells utilizing PbI2 precursors

Highlights: • Uniform and compact CH₃NH₃PbBr₃ films obtained via the two-step deposition method. • PbI₂ precursor led to improved film quality and enhanced photovoltaic performance. • Halide anion exchange between PbI₂ and CH₃NH₃Br occurred. • Suitable precursor seed induced high-quality perovskite crystal growth. High-quality CH₃NH₃PbBr₃ films have been made utilizing the PbI₂ precursor via a two-step sequential deposition method. The use of the PbI₂ precursor has significantly improved the film quality. UV–Vis results show that the PbI₂ precursor leads to moderately enhanced absorptions. XRD and SEM characterizations suggest that compact and uniform films with large grain sizes and high crystallinity can be obtained utilizing PbI₂. The power conversion efficiency of the FTO/compact-TiO₂/MAPbBr₃/Spiro-OMeTAD/Ag device increased from 5.3% to 7.6% after changing the PbBr₂ precursor to PbI₂. The reaction between PbI₂ and excess MABr generated MAPbBr₃ through halide anion exchange.