Origins of three‐dimensional charge and two‐dimensional phonon transports in Pnma phase PbSnSe 2 thermoelectric crystal

• Published in: InfoMat Vol. 5; no. 12
• Main Authors: Wang, Tianyu, Duan, Xinlei, Zhang, Hao, Ma, Jinlong, Zhu, Hangtian, Qian, Xin, Yang, Jia‐Yue, Liu, Te‐Huan, Yang, Ronggui
• Format: Journal Article
• Language: English
• Published: 01.12.2023
• ISSN: 2567-3165; 2567-3165
• DOI: 10.1002/inf2.12481

Abstract Recently, PbSnSe 2 alloy was found to exhibit a large hysteresis effect on transport properties, demonstrating its significant potential for thermoelectric applications. Using ab initio approaches, we studied the carrier transport properties of PbSnSe 2 crystal, which is a special case of the alloy with the shortest‐range order. A peak power factor of 134.2 μW cm −1  K −2 was found along the cross‐plane direction in the n ‐type PbSnSe 2 at a doping concentration of 7 × 10 20  cm −3 at 700 K. This high power factor originates from delocalized p electrons between intra‐plane Pb–Se pairs and between cross‐plane Sn–Se pairs that can build up transport channels for conducting electrons, leading to a high electrical conductivity of 5.9 × 10 5  S m −1 . Introducing Pb atoms into Pnma phase SnSe can decrease the phonon group velocities and enhance the phonon–phonon scatterings, leading to a low thermal conductivity of 0.53 W m −1  K −1 at 700 K along the cross‐plane direction. The calculated peak ZT of ~3 along the cross‐plane direction at an n ‐type doping concentration of around 5 × 10 19  cm −3 , which represents a theoretical upper limit for an idealized PbSnSe 2 crystal. This work interprets the origins of three‐dimensional charge and two‐dimensional phonon transport behavior in PbSnSe 2 and demonstrates that such crystals are promising high‐performance thermoelectric semiconductors.