Tuning photoelectric conversion in hybrid perovskites by thermal cycling†

The successful commercialization of perovskite photovoltaics requires comprehension of the effects of fatigue aging on the photoelectric performance of the devices through frequency of temperature variation tests. In this study, the effects of thermal cycling between room temperature (RT) and 60 °C (RT-thermal cycling) on the photoelectric performance of classical methylammonium lead iodide (MAPbI₃) perovskite films are investigated. After the first thermal cycle, the films exhibit a moderate compressive strain of 1.08% along the [110] direction, resulting in a minimal bandgap (1.585 eV), reduced defect density, and an extended carrier lifetime (16.27 ns). The photovoltaic device using this perovskite film as the absorber layer demonstrates a maximum photocurrent of 35.63 μA. Theoretical calculations suggest that a moderate compressive strain along the [110] direction in the tetragonal MAPbI₃ phase reduces both the bandgap and effective carrier mass while increasing the formation energy of iodine vacancies. These changes enhance the light-absorption and carrier-transport efficiency. Strain engineering through RT-thermal cycling can facilitate large-scale market-oriented applications of perovskite-based photoelectric devices.