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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). 

We report on the properties and stability of inorganic perovskite CsPbBr3 fabricated using vapor deposition. We have obtained the highest voltage ever recorded, exceeding 1.6V, in this material. The material was deposited using vapor deposition process, followed by post-deposition anneal at 450 C. Both layer by layer, and sequential anneal processes were sued for growing the material. After growth and anneals, the material was tested for thermal stability at temperatures of 300 C, and the x-ray data showed that there was no degradation of the material even at this high temperature. n-i-p superstrate devices were fabricated on FTO substrates coated with either TiO2 or n-CdS. The p layer was P3HT or PTAA. The devices showed an open-circuit voltage of 1.62V, the highest ever reported in this material. The devices were exposed to humid room air for 25 days, and showed no degradation at all in its performance. Detailed material measurements such as subgap quantum efficiency and deep defects were measured. The Urbach energy for valence band tails is found to be 22 meV and mid-gap defect density in the range of few 1015/cm3.