Cu₂ZnSiTe₄: A Potential Thermoelectric Material with Promising Electronic Transport

Transition metal-based quaternary chalcogenides have attracted a lot of interest for a variety of renewable energy applications, especially thermoelectrics (TE). Although this class of compounds have low symmetry and complex structure which contribute to low lattice thermal conductivity, achieving a high figure of merit (ZT), is still a challenge for this class of materials for use in TE applications due to low values of power factor. Here, we used first-principles calculation to study the TE properties of a novel system, Cu₂ZnSiTe₄, with promising electronic transport. The heavy chalcogen ‘Te’ atom, contributes to the comparatively low bandgap of 0.58 eV. This results in a promising power factor of 3.95 (n-type) and 3.06 (p-type) mWm⁻¹K⁻² at 900 K, together with a favourable electronic band topology. Additionally, ‘Te’ atoms are responsible for the mixing of the optical and acoustic phonon branches, which at high temperature results in low lattice thermal conductivity (about 0.7 mWm⁻¹K⁻¹). The compound yields a promising TE figure of merit (ZT ∼2.67 (n-type) and ∼2.11 (p-type) at 900 K. We predict Cu₂ZnSiTe₄ as a viable option for TE applications. We believe our study will motivate experimentalists to explore this compound for future investigation for TE applications.