High‐Ranged <i>ZT</i> Value Promotes Thermoelectric Cooling and Power Generation in n‐Type PbTe
Yu Xiao, Haijun Wu, Haonan Shi, Liqing Xu, Yuke Zhu, Yongxin Qin, Guyang Peng, Yang Zhang, Zhen‐Hua Ge, Xiangdong Ding, Li‐Dong Zhao
Abstract
Abstract Excellent thermoelectric cooling and power generation are simultaneously realized in an n‐type PbTe‐based thermoelectric material. The cooling temperature difference (Δ T ) of ≈15.6 K, maximum power density of ≈0.4 W cm −2 and conversion efficiency of ≈1.5% with T C = 295 K and T H = 765 K can be obtained in a single‐leg device composed of PbTe‐30%SnSe‐1.5%Cu. This advanced thermoelectric performance in n‐type PbTe‐30%SnSe‐1.5%Cu mainly originates from its high‐ranged ZT value achieved through optimizing its bandgap, carrier density, and microstructure. The bandgap in PbTe is first reduced by SnSe alloying to facilitate the carrier transport properties at low temperature range (300–573 K). With further tuned carrier density, the average power factor increases from ≈10.2 µW cm −1 K −2 in Pb 0.985 Sb 0.015 Te‐30%SnSe to ≈16.2 µW cm −1 K −2 in PbTe‐30%SnSe‐1.5%Cu at 300–773 K. Moreover, microstructure observation reveals high‐density dislocations in PbTe‐30% SnSe‐1.5% Cu, which can dramatically suppress the room‐temperature lattice thermal conductivity from ≈2.21 Wm −1 K −1 in Pb 0.985 Sb 0.015 Te to ≈0.53 Wm −1 K −1 in PbTe‐30%SnSe‐1.5%Cu. As a result, a room‐temperature ZT value of ≈0.7 and high average ZT value ( ZT ave ) of ≈0.98 can be obtained in PbTe‐30%SnSe‐1.5%Cu at 300–573 K, which makes its performance comparable to the commercial n‐type Bi 2 Te 3 ‐based thermoelectric material.