Inorganic perovskite solar cells with very high voltage and excellent stability against thermal and environmental degradation

We report on inorganic CsPbBr
3
solar cells with very high open circuit voltages and excellent environmental stability. The cells were fabricated using vapor deposition. We show that by using an interfacial n-doped CdS (CdS:In) layer between the cell TiO2, we can obtain voltages of ∼1.68 V, the highest ever reported in vapor deposited CsPbBr3 material. A surprising phenomenon was that the crystal structure of the material, and the apparent bandgap, changed when a thicker CdS:In layer was used as the n layer. We also show that there is little environmental degradation in performance for a cell kept for 600 hours in room air, and even for a cell kept at 200 °C for 24 hours in air. The cells were deposited using sequential deposition in vacuum followed by anneals at 450 °C. We study both organic p layers (P3HT) and inorganic p layers (paste coated C).