Effects of Surface Blocking Layer of Sb₂S₃ on Nanocrystalline TiO₂ for CH₃NH₃PbI₃ Perovskite Solar Cells

Abstract

Sb 2 S 3 layers were inserted at the interface between TiO 2 and CH 3 NH 3 PbI 3 perovskite to create CH 3 NH 3 PbI 3 solar cells using inorganic hole transporting material (CuSCN). The CH 3 NH 3 PbI 3 layer was spin-coated by a one-drop method onto the nanocrystalline TiO 2 layer. The photoenergy conversion efficiencies were improved with Sb 2 S 3 layers (the best efficiency: 5.24%). During the light exposure test without encapsulation, the CH 3 NH 3 PbI 3 solar cells without Sb 2 S 3 deteriorated to zero efficiency in 12 h and were completely changed from black to yellow because the perovskite CH 3 NH 3 PbI 3 was changed to hexagonal PbI 2 . With Sb 2 S 3, on the other hand, the CH 3 NH 3 PbI 3 solar cells became stable against light exposure without encapsulation, which did not change the crystal structure or the wavelength edges of absorption and IPCE. Therefore, it was believed that degradation can occur at the interface between TiO 2 and CH 3 NH 3 PbI 3 .