Defect Regulation of Low-Temperature-Processed CsPbI2Br Solar Cells Based on Silane Additives

The development of inverted all-inorganic perovskite solar cells (PSCs) is limited by the defect-induced nonradiative recombination. Herein, a strategy to enhance the efficiency and stability of p-i-n type CsPbI₂Br solar cells by introducing (3-glycidyloxypropyl)trimethoxysilane (GOPTS) into the CsPbI₂Br precursor solution is reported. The incorporation of GOPTS significantly reduces voids and grain boundaries in CsPbI₂Br films fabricated at low temperatures (150 °C). The alkoxy, epoxy, and ether groups in GOPTS effectively passivate uncoordinated Pb, diminishing the nonradiative recombination centers associated with perovskite defects. Density functional theory simulations suggest that GOPTS increases the vacancy formation energies of Cs and I, leading to the reduced nonradiative recombination. Furthermore, GOPTS mitigates photoinduced phase segregation and further enhances the performance and stability of the PSCs. This modification results in an increase in the power conversion efficiency of the p-i-n type CsPbI₂Br solar cells, from 11.83% to 13.32%, when self-assembled monolayers are used as the hole transport layer. This study underscores the potential of silane-based additives in defect passivation for all-inorganic perovskites, providing a viable route for the advancement of high-efficiency CsPbI₂Br solar cells.