Mesoporous TiO2 electron transport layer engineering for efficient inorganic-organic hybrid perovskite solar cells using hydrochloric acid treatment

Abstract

We demonstrated effects of wet chemical processes using hydrochloric on crystallite structures, optical and electronic properties, and surface morphology of TiO2 thin films and enhancement in photovoltaic performance of perovskite solar cell using HCl-treated mesoporous TiO2 electron transport layers (ETLs). By treating mesoporous TiO2 thin films with HCl, hydroxyl groups on the surface were chemically neutralized and the film porosity was enhanced. Furthermore, the crystallite structure analyses indicated that CH3NH3PbI3 perovskite thin films deposited on the HCl-treated compact and mesoporous TiO2 ETLs possessed the relatively high crystallization along with avoiding formation of unexpected PbI2 crystals. As a result, the best power conversion efficiencies of devices using the HCl-treated mesoporous TiO2 ETLs were improved to 18.4% under forward bias scans.