Sharp enhancement on thermoelectric figure-of-merit of post-transition metal chalcogenides (PTMCs) using heterostructures with Mexican-hat valence band

TL;DR

This study demonstrates through ab initio calculations that heterostructures of post-transition metal chalcogenides with Mexican-hat valence bands can significantly enhance thermoelectric efficiency, achieving a 50% increase in figure-of-merit at room temperature.

Contribution

The paper reveals that InSe/GaSe heterostructures exhibit Mexican-hat valence bands and predicts a substantial improvement in thermoelectric performance.

Findings

Presence of Mexican-hat valence band in heterostructures confirmed by calculations.

Predicted 50% increase in thermoelectric figure-of-merit (zT) at room temperature.

Potential for improved thermoelectric devices using PTMC heterostructures.

Abstract

Post-transition metal chalcogenides (PTMCs) such as GaSe, GaS, InSe, and InS have been proposed as promising thermoelectric materials due to low lattice conductivity, originating from the atomically layered structure, high Seebeck coefficient, and the anticipation that its figure-of-merit be improved when thinned to few-layers as the band structure turns into Mexican-hat valence band (MHVB). Here we show by ab initio calculations that the MHVB should be present even on thick films of InSe/GaSe type-II heterostructures, and a 50% enhancement on thermoelectric figure-of-merit zT at room-temperature is expected when compared with bulk InSe.