Intrinsically low lattice thermal conductivity and thermoelectric performance of 2D Cu₂Te

Abstract

In this study, we employed density functional theory to investigate the structural, mechanical, dynamical, electronic, and thermal transport properties of 2D Cu2Te in the hexagonal P6/mm structure. Our results demonstrate that this structure is both mechanically and dynamically stable, and has a direct band gap, indicating its potential as a semiconductor. The high Grüneisen parameter value of 2D Cu2Te resulted in a lower lattice thermal conductivity compared to its bulk counterpart due to increased phonon scattering in the 2D structure. Furthermore, we observed that the Seebeck coefficient in 2D Cu2Te is higher in the p-type region, while the electrical conductivity is higher in the n-type region at lower temperatures. Two different approaches were used to calculate the lattice thermal conductivity, and it was found that the thermal conductivity decreases with dimension reduction in Cu2Te. Additionally, ultralow thermal conductivity was observed. Moreover the lattice thermal conductivity plays a dominant role in the thermoelectric performance. The maximum ZT value for 2D Cu2Te was obtained as 1.28 at 700 K. Overall, our results suggest that 2D Cu2Te is a potential new candidate for high thermoelectric performance.