Exploring the electronic, optical, and thermoelectric properties of Ba2GeX4 (X = S, and Se) novel chalcogenides

Abstract

The significant optical and electronic features of ternary-type chalcogenides garnered notable consideration, especially for the conversion of solar energy. Here, we investigated the optoelectronic, and transport properties of novel Ba2GeX4 (X = S, and Se) materials using first-principles-based calculations within the framework of the density functional theory. The calculations are carried out with PBE-GGA and TB-mBJ potentials to address properly the strongly correlated electronic nature of these materials. A strong covalent nature in the bonds exists due to large band gaps. The electronic state's contributions are discussed from the computed density of states calculations. The Ge-s states account for the majority of its contribution in both materials with some minor role from Ge-p states. Both the tensor components of the imaginary part show an anisotropic trend with sharp peaks that are because of the interband shift from valance band maximum to conduction band minimum. A significant absorption in the UV region was observed suggesting the materials to possess a weak transparent nature. The Seebeck coefficient for both materials exhibit a positive value in the respective temperature range, confirming holes serve as the primary charge carriers. All other significant thermoelectric parameters were discussed in detail, suggesting these materials to be suitable for thermoelectric applications. The present study may primarily support the development of integrated efficient optoelectronic devices and their applications.