Tuning the Thermoelectric Performance of Hybrid Tin Perovskites by Air Treatment

The intriguing properties of halide perovskites have led to high-performance optoelectronic devices. Recently, tin (Sn) halide perovskites have attracted significant interest for thermoelectrics due to their high electrical conductivity and low thermal conductivity. Herein the thermoelectric performance of Sn and binary tin-lead (Sn-Pb) hybrid perovskites is evaluated. Leveraging the oxidative nature of Sn, air treatment of the perovskite films leads to improved thermoelectric performance due to self-doping. The film conductivity increases significantly with a semiconductor to quasi-metallic transition upon air exposure. In addition, this enhanced electrical conductivity is preserved after controlled air exposure for extended period of time. An increase of 42% and 83% in the thermoelectric power factor of CH3NH3SnI3 and CH3NH3Sn0.75Pb0.25I3 is observed, respectively, after air treatment compared to pristine films at 336K. Apart from thermoelectrics, the implications of this work are relevant to other perovskite devices such as solar cells and light-emitting diodes (LEDs).