Origins of three‐dimensional charge and two‐dimensional phonon transports in Pnma phase PbSnSe₂ thermoelectric crystal

Abstract

Recently, PbSnSe2 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 PbSnSe2 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 PbSnSe2 at a doping concentration of 7 × 1020 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 × 105 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 × 1019 cm−3, which represents a theoretical upper limit for an idealized PbSnSe2 crystal. This work interprets the origins of three‐dimensional charge and two‐dimensional phonon transport behavior in PbSnSe2 and demonstrates that such crystals are promising high‐performance thermoelectric semiconductors.

Influence of High-Pressure Induced Lattice Dislocations and Distortions on Thermoelectric Performance of Pristine SnTe

“…[3,4] Here 𝜎𝑆 2 is the power factor (PF), (𝜅e + 𝜅 ph ) represents the total thermal conductivity 𝜅, which is the sum of the carrier thermal conductivity 𝜅e and the lattice thermal conductivity 𝜅 ph . [5,6] Thus, achieving a higher power factor and lower thermal conductivity is imperative for enhancing the performance of thermoelectric materials. Typically, the electrical properties of materials can be enhanced through strategies such as introducing resonance levels, [7,8] adjust-ing band structures, [9,10] energy filtering effect, [11] and alloying methods.…”