Carrier-phonon decoupling in perovskite thermoelectrics via entropy engineering

Abstract 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 SrTiO 3 -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 cm 2 V −1 s −1 . Such carrier-phonon decoupling behaviors enable the greatly enhanced μ W / κ L of ~5.2 × 10 3 cm 3 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 0.2 Ba 0.2 Ca 0.2 Pb 0.2 La 0.2 )TiO 3 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.