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

SnO 2 is a promising electron transport layer (ETL) material for PbS quantum dot (QD) solar cells. Compared to the widely used ZnO ETL, SnO 2 offers improved optoelectronic properties and more favorable energy band alignment with PbS QDs. Despite these advantages, the application of SnO 2 in PbS QD solar cells has been comparatively less explored. Herein, we report an interface engineering strategy to utilize SnO 2 ETLs for efficient PbS QD photovoltaics. Our results show that devices employing bare SnO 2 ETLs exhibit significantly lower performance compared to the ZnO-based counterparts. Interfacial analysis reveals that proton release from the SnO 2 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 SnO 2 -induced degradation reactions. Consequently, a power conversion efficiency of 12.7% was achieved, surpassing that of ZnO-based devices (10.4%).