Computational Prediction of High Thermoelectric Performance in Hole Doped Layered GeSe

Thermoelectric materials enable direct conversion between thermal and electrical energy and provide a viable route for power generation and electric refrigeration. In this paper, we use first-principles based methods to predict a very high figure of merit (ZT) performance in hole doped GeSe crystals along the crystallographic b-axis, with maximum ZT ranging from 0.8 at 300 K to 2.5 at 800 K. This extremely high thermoelectric performance is due to a threefold synergy of properties in this material: (1) the exceptionally low lattice thermal conductivity in GeSe due to anharmonicity of vibrational modes, (2) the increased electrical conductivity due to hole doping and increased carrier concentration, and (3) an enhanced Seebeck coefficient via a multiband effect induced by hole doping. The predicted ZT results of hole-doped GeSe are higher than that of hole doped SnSe, which we have recently reported as having experimentally observed record-breaking thermoelectric efficiency. The overall ZT of hole doped GeSe crystals outperforms all current state-of-the-art thermoelectric materials, and this work provides an urgent computational materials prediction that is in need of experimental testing.