Impact of Light on the Thermal Stability of Perovskite Solar Cells and Development of Stable Semi-transparent Cells

The stability of perovskite cells has been the major challenge to the commercialization of the technology. Here, we study the thermal stability of mesoporous perovskite cells using poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) for the hole transport layer. We find evidence that gold diffusion into the perovskite active layer is prevented by the PTAA layer when the cell is aged at 85 °C in the dark, but not under light. This seriously affects the operational stability of perovskite cells. We therefore develop thermally stable semi-transparent perovskite cells, which retain more than 90% of the initial efficiency after >160 hours operating at 85 °C under light.