Carrier-phonon decoupling in perovskite thermoelectrics via entropy engineering
Yunpeng Zheng, Qinghua Zhang, Caijuan Shi, Zhifang Zhou, Yang Lu, Jian Han, Hetian Chen, Yunpeng Ma, Yujun Zhang, Changpeng Lin, Wei Xu, Weigang Ma, Qian Li, Yueyang Yang, Bin Wei, Bingbing Yang, Mingchu Zou, Wenyu Zhang, Chang Liu, Lvye Dou, Dongliang Yang, Jinle Lan, Di Yi, Xing Zhang, Lin Gu, Ce‐Wen Nan, Yuanhua Lin
Abstract
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.