Enhanced photocurrent and responsivity of PbS quantum Dot/ZnO nanoparticle films with amine passivation

This study investigated a combination of PbS quantum dots (QDs) and ZnO nanoparticles (NPs) layers in photodiodes for photodetection. Oxygen vacancies in ZnO NPs have been known to be recombination trap sites, hindering carrier transportation. We used various amines to passivate the oxygen vacancy of ZnO NPs. It is found that ethanolamine (EA) is the most effective in reducing the surface oxygen vacancies of ZnO, exhibiting a five-fold increase in electron mobility, enhancing PbS QD photodiode responsivity to 278.8 A/W and achieving an external quantum efficiency (EQE) of 36,700% under bias, and increasing the detectivity ∼ 15.5 folds to 8.14 × 10¹² Jones compared with the pure ZnO device. This demonstrates the potential of amines as passivation agents to improve PbS photodiode performance with ZnO NPs as the electron transport layer (ETL).