Carrier-phonon decoupling in perovskite thermoelectrics via entropy engineering

Thermoelectrics converting heat and electricity directly attract broad attentions. To enhance the thermoelectric figure of merit, zT, one of the key points is to decouple the carrier-phonon transport. Here, we propose an entropy engineering strategy to realize the carrier-phonon decoupling in the typical SrTiO₃-based perovskite thermoelectrics. By high-entropy design, the lattice thermal conductivity could be reduced nearly to the amorphous limit, 1.25 W m^-1 K^-1. Simultaneously, entropy engineering can tune the Ti displacement, improving the weighted mobility to 65 cm² V^-1 s^-1. Such carrier-phonon decoupling behaviors enable the greatly enhanced μ_W/κ_L of ~5.2 × 10³ cm³ K J^-1 V^-1. The measured maximum zT of 0.24 at 488 K and the estimated zT of ~0.8 at 1173 K in (Sr_0.2Ba_0.2Ca_0.2Pb_0.2La_0.2)TiO₃ film are among the best of n-type thermoelectric oxides. These results reveal that the entropy engineering may be a promising strategy to decouple the carrier-phonon transport and achieve higher zT in thermoelectrics.