Giant thermoelectric performance of an n-type 2D GaSe0.5Te0.5 alloy

Abstract

Two-dimensional alloy systems can show the possibility for thermoelectric applications because of their low thermal conductivity due to the complex structural effect. Therefore, we investigated the thermoelectric (TE) performance of the GaSe_0.5Te_0.5 alloy monolayer. We found a direct band gap of 2.19 eV by using the HSE06 hybrid functional including the spin–orbit coupling (SOC) effect. Based on this band structure, we explored the TE properties of both n- and p-type systems. The n-type system showed better TE performance than the p-type system. For instance, the n-type maximum ZT was 2.05 at 700 K, and this high ZT had weak carrier concentration dependence. For instance, it was changed by only ∼10% in the range of carrier concentrations of 1–10 × 10¹⁹ electrons per cm³. Moreover, we also observed that the n-type GaSe_0.5Te_0.5 alloy showed better TE performance compared with the ZTs found in pure GaSe and GaTe monolayers. Overall, we proposed that the n-type GaSe_0.5Te_0.5 alloy shows outstanding thermoelectric performance, and this result will provoke further experimental investigations to verify our prediction.