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

We report on the properties and stability of inorganic perovskite CsPbBr
3
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 TiO
2
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 10
¹⁵
/cm
³
.