Effect of TiO2 Surface Treatment on the Current–Voltage Hysteresis of Planar-Structure Perovskite Solar Cells Prepared on Rough and Flat Fluorine-Doped Tin Oxide Substrates

Abstract

Herein, we studied the effect of surface treatment of compact TiO2 layer by vacuum ultraviolet (VUV) light and by TiCl4 on the I–V hysteresis of perovskite solar cells prepared on fluorine-doped tin oxide (FTO) substrates with two different surface roughnesses. Initially, the cells prepared on flat FTO substrates show better results than cells prepared on rough FTO, with slightly higher power conversion efficiency (PCE) and less hysteresis in the I–V curves. Treatment of TiO2 prepared on flat FTO has no effect on the I–V hysteresis because of better contact between TiO2/CH3NH3PbI3 layers. Treatment of TiO2 layer on rough FTO has a positive effect on the PCE and I–V hysteresis and stability.