Comparison of effects of ZnO and TiO2 compact layer on performance of perovskite solar cells

In this work, organic-inorganic perovskite solar cells using compact layers of TiO2 and ZnO have been constructed. The ZnO compact layer was synthesized through the chemical hydrolysis process. The TiO2 compact layer was formed by spin-coating C16H28O6 Ti in n-butanol. AFM and light absorption studies showed that the surface roughness and optical property of TiO2 and ZnO are nearly identical. However, according to the energy level diagram, the conduction band edge of ZnO is lower than that of TiO2, which is beneficial for electron transfer from the light absorption material to the FTO substrate and thus reducing electron-hole recombination. As a result, employing ZnO in the cell improved both the photocurrent and photovoltaic performance in comparison to TiO2. The best conversion efficiency obtained from the device using ZnO as the compact layer is 17.1%, which is attributed to facilitated photo-generated electron transport in the perovskite solar cell.