GeI₂ monolayer: a model thermoelectric material from 300 to 600 K

ABSTRACT

In this work, the electronic structure, optical properties and thermoelectric properties of the GeI₂ monolayer are calculated by the first principles with the Boltzmann transport equation. The monolayer is calculated as an indirect band gap semiconductor with an indirect band gap of a value 2.19 eV. This GeI₂ monolayer is good for absorbing low-energy photons, and it is insensitive to high-energy photons. The material is stable at temperatures up to 600 K, so we calculated the thermal conductivity (K_L), Seebeck coefficient (S), power factor (PF) and thermoelectric figure of merit (ZT) of the GeI₂ monolayer at various carrier concentrations from 300 to 600 K. Due to the lower group velocity, the GeI₂ monolayer has a lower thermal conductivity of 0.48 W/m K at 300K. In P-type doping, the power factor can up to 0.11 mW/m K², and its ZT value is 4.04 at 600 K of the GeI₂ monolayer, indicating that the GeI₂ monolayer is a potential thermoelectric material.

KEYWORDS:

• GeI₂ monolayer
• thermoelectric material
• electronic structure
• optical properties
• first-principles calculation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are grateful to the Education Department of Sichuan Province (Grant nos. 18ZA0340), Artificial Intelligence Key Laboratory of Sichuan Province (Grant nos. 2018RYJ07), and Innovation and Entrepreneurship Training Program of Sichuan University of Science & Engineering (Grant nos. cx2019005). This work was supported by Sichuan University of Science & Engineering High Performance Computing Center of Science & Engineering provided computational.