Defect passivation and charge dynamics improvement in mixed-cation perovskites via CdS nanospheres incorporation

Abstract

This work explores the incorporation of hydrothermally synthesized cadmium sulfide nanospheres into mixed-cation perovskite absorber layers to enhance the performance, stability, and charge dynamics of perovskite solar cells. CdS nanospheres, known for their favorable band alignment and defect passivation properties, are embedded at various weight percentages into a FA0.3MA0.6Cs0.1Pb(I0.8Cl0.2)3 perovskite matrix. Structural, optical, and electrical analyses reveal that 0.3 wt% CdS yields the best balance of crystallinity, light absorption, and charge transport. The device incorporating this optimal CdS concentration achieves a power conversion efficiency of 20.0%, significantly outperforming the control cell (16.0%). Additionally, it shows reduced hysteresis, suppressed trap density, enhanced built-in potential, and improved long-term stability. This study demonstrates that CdS nanospheres serve as multifunctional additives that reinforce film quality, passivate defects, and promote efficient charge extraction, offering a viable route toward higher-efficiency and more stable perovskite solar cells.