Halide perovskite thin films for thermoelectrics*

Halide perovskites have emerged as promising candidates for photovoltaics and light-emitting diodes. Recently, promising thermoelectric performance has been reported for single nanocrystals of a halide perovskite, but there is not yet a good understanding of how thermoelectric performance can be optimised in these materials, especially in thin films where a diverse range of structures and morphologies are accessible. In this presentation I will report a record thermoelectric figure of merit (ZT) for halide perovskites, using the example of CsSnI₃ thin films. This result is in part due to the ultralow thermal conductivity of our films (0.38 W/mK at room temperature), as well as high electrical conductivity enabled by self-doping of the films through controlled Sn oxidation. I will also discuss the potential role of mixed-halide films in developing these materials further.
Finally I will demonstrate how thin film morphology and composition can be used to further reduce the thermal conductivity in vapour- and solution-deposited CH₃NH₃PbI₃.