Suppressing Interfacial Deprotonation of Metal Oxides for Efficient PbS Quantum Dot Photovoltaics

SnO2 is a promising electron transport layer (ETL) material for PbS quantum dot (QD) solar cells. Compared to the widely used ZnO ETL, SnO2 offers improved optoelectronic properties and more favorable energy band alignment with PbS QDs. Despite these advantages, the application of SnO2 in PbS QD solar cells has been comparatively less explored. Herein, we report an interface engineering strategy to utilize SnO2 ETLs for efficient PbS QD photovoltaics. Our results show that devices employing bare SnO2 ETLs exhibit significantly lower performance compared to the ZnO-based counterparts. Interfacial analysis reveals that proton release from the SnO2 surface during PbS QD deposition leads to the detachment of QD ligands, resulting in the formation of oxidized Pb species. To address this issue, we introduced a surface passivation strategy to effectively suppress the SnO2-induced degradation reactions. Consequently, a power conversion efficiency of 12.7% was achieved, surpassing that of ZnO-based devices (10.4%).