Stable High Temperature Operation in Metal Halide Perovskite Solar Cells

FA0.8Cs0.2PbI2.4Br0.6Cl0.02 triple halide perovskite solar cells have been shown to be amongst the most stable metal halide perovskites to date, and while their band gap is too high for use in high efficiency single gap solar cells, these systems have shown considerable promise as the high energy junction in perovskite-perovskite, silicon-perovskite, and CIGS-perovskite tandem solar cells. While in early work we have demonstrated the high radiation tolerance of these systems for potential space power applications, here high temperature data is presented which systematically and statistically demonstrates the high thermal stability of this system at temperatures in excess of 200 °C. Here, device measurements between 300 K and 490 K show that while some loss of performance is evident at higher temperature, this is driven by reversible halide segregation with no evidence of any structural phase transitions over the measurement range probed. Moreover, when the temperature of the device is reduced, then much of the operation conditions are recovered over multiple cycles. The observed stability is attributed to a combination of the high structural and crystallographic purity of this system as well as, the application of an encapsulation layer that inhibits the loss of constituent elements from the system at higher temperatures.