First principles study of high thermoelectric performance of two-dimensional CuI/GaTe heterostructures

Vertically stacked two-dimensional materials have emerged as a focal point of research due to their potential for effective manipulation of electronic and transport properties. In this study, we integrate first-principles calculations with Boltzmann transport theory to comprehensively assess the thermoelectric characteristics of van der Waals heterostructures, specifically formed by the alternating layering of CuI and GaTe in the out-of-plane orientation. Both ab initio molecular dynamics simulations and phonon dispersion analyses confirm the structural stability of the resulting heterostructures. We methodically evaluate key thermoelectric parameters, including the phonon relaxation time, Seebeck coefficient, electrical conductivity, and lattice thermal conductivity (k_l) for the CuI/GaTe heterostructure. Our analysis suggests that the incorporation of nanostructures can effectively diminish k_l through enhanced phonon boundary scattering at the interfaces. Remarkably, our calculations indicate that the figure of merit (ZT) for the CuI/GaTe heterostructures achieves a noteworthy value of 3.97 at 700 K, exceeding many previously documented ZT values for competing heterostructures. Furthermore, the estimated average ZT value surpassing 1 indicates substantial prospects for practical thermoelectric applications across a diverse temperature spectrum. Collectively, these findings provide critical insights into the design and optimization of advanced thermoelectric materials, paving the way for future investigations in this domain.