Electronic sensitization by Mg doping gradient-induced functional interfaces: Large photocurrent in PbS/Zn1-xMgxO solar cells

Abstract

We investigated doping gradient-mediated charge separation and carrier extraction in PbS/ZnMgO photovoltaic (PV) devices. We fabricated PbS/Zn(Mg)O/Al solar cells in which the Mg composition was systematically changed to form the PbS/Zn0.85Mg0.15O and PbS/ZnO interfaces where charge separation and extraction occur, respectively, during PV operation. The short-circuit current increased significantly with the Mg-doping gradient electron transport layer (ETL). The increased short-circuit current is attributed to the suppression of carrier recombination at the PbS/ Zn0.85Mg0.15O interface and the enhanced carrier extraction at the ZnO/Al interface resulting from the formation of Mg doping gradient in the ETL. The presented results provide insights into the synergistic effect of the doping gradient ETL and interface modification for the electronic sensitization of PbS colloidal quantum dot PV devices.