Strategic Doping in Metal Halide Perovskites for Thermoelectrics

Metal halide perovskites (MHPs) have not only shown unique merits of ultralow thermal conductivity compared to traditional inorganic thermoelectric (TE) materials, but also featured superior Seebeck effect to organic semiconductors, thereby affording great prospect in TE field. However, their severely poor electrical conductivity significantly hinders TE applications, which results from the restrained doping efficiency due to the limited accommodation capability of heterogeneous dopants and the heavy compensation from interior defects in MHPs. Realizing high-effectiveness electrical doping in MHPs becomes imperative yet remains extremely challenging. This Minireview is therefore intended to sort out the diversified doping strategies and highlight their underlying impacts on both thermal and electrical transportation in MHPs. These strategies are systematically classified into bulk and surface/interface doping as dictated by where the dopants are implemented while unravelling how they critically impact TE properties in distinctive means. A rational guideline is hence derived to strengthen electrical doping towards desirable perovskite TEs.