Regulating the Quantum Dots Integration to Improve the Performance of Tin–Lead Perovskite Solar Cells

Abstract Despite their advantageous attributes, such as a narrow bandgap and reduced toxicity, tin–lead halide perovskites (TLHPs) have received limited attention due to their lower power conversion efficiency (PCE) relative to lead‐only variants. In this study, a transformative approach is introduced that leverages perovskite quantum dots (PQDs) to optimize TLHP solar cells. While conventional oleyl‐capped PQDs enhance the open circuit voltage ( V OC ), the long‐chain ligands hinder charge transport. To overcome this limitation, a post‐treatment with isopropyl alcohol effectively dissociates these ligands and PQD crystals, resulting in reduced defect density, improved charge transfer, and elevated quasi‐Fermi level splitting in the TLHP device. Consequently, the PCE of the device is notably increased from 19.0% to 23.74% and elevated the V OC from 0.78 to 0.87 V, without compromising the photocurrent or fill factor. The findings highlight PQD modification as a compelling avenue for TLHP solar cell enhancement, particularly in boosting V OC .