MnBr2-Doped CsPbBr3 Nanocrystal Passivation Layer for High-Efficiency and Stable Perovskite Solar Cells

Perovskite (ABX3) nanocrystals have garnered significant attention as interfacial passivation materials for perovskite solar cells (PSCs) due to their tunable optoelectronic properties. However, single-component systems often suffer from insufficient defect passivation and poor film stability, limiting their practical application. To address these challenges, we develop a MnBr2 doping strategy for CsPbBr3 nanocrystals, which enables precise control over their morphology and phase evolution via B-site Pb2+/X-site Br− stoichiometric regulation. Systematic doping induces a progressive morphological transition from cubic to quasi-spherical geometries, accompanied by a phase transformation from cubic CsPbBr3 to hexagonal Cs4PbBr6. The optimized mixed-phase nanocrystals exhibit synergistic effects in interfacial defect passivation and charge transport enhancement, leading to PSCs modified with CsPbBr3/Cs4PbBr6 heterostructures achieving a champion power conversion efficiency (PCE) of 23.33% along with enhanced stability. This work not only elucidates the fundamental structure–property relationships governing MnBr2-doped nanocrystal evolution but also establishes a new materials design paradigm for high-performance PSC interfaces.