Modulating Crystallization and Suppressing Phase Segregation in Wide-Bandgap Perovskite Absorbers toward Silicon-Based Tandem Solar Cells

Wide-bandgap (WBG) perovskite solar cells are essential components in tandem photovoltaics. However, the high bromide content in WBG perovskites often leads to complex crystallization processes and poor film quality. Additionally, light-induced phase segregation further constrains the performance and long-term stability of WBG solar cells. To address these challenges, two-dimensional (2D) PMAPbI4 (PAI, 4-pyridinylmethylammonium iodide) perovskite was introduced to modulate the crystallization process of WBG perovskites. The strong interaction between PAI and the three-dimensional (3D) perovskite components slows down the crystallization rate, resulting in enhanced crystal quality and suppressed halide ion segregation. This strategy substantially enhances the photovoltage within a broad bandgap range spanning from 1.67 to 1.85 eV. Moreover, a monolithic two-terminal perovskite/silicon tandem solar cell demonstrates an efficiency of 32.11%. Overall, this study offers comprehensive insights into controlling WBG perovskite crystallization and establishes a foundation for future progress in tandem photovoltaic technologies.