First-Principle Calculation of High Absorption-TlGaTe(2) for Photovoltaic Application

We use first-principle calculations based on hybrid functional and the Bethe-Salpeter equation method to investigate the electronic and optical properties of dichalcogenide TlGaTe(2). Based on theoretical studies, TlGaTe(2) has until recently been considered as an indirect band gap material, however; by employing more accurate hybrid functional model, we showed that although TlGaTe(2) has an indirect band gap of 1.109 eV, it also exhibits a fundamental direct band gap of 1.129 eV. Our finding was further confirmed by the optical studies on TlGaTe(2), which show that the absorption peak is registered at a photon energy of 1.129 eV. It was also shown that TlGaTe(2) has high optical absorption peaks in the visible region. Based on phonon and elastic constant calculations, it was shown that TlGaTe(2) is dynamically and mechanically stable. Our findings show that TlGaTe(2) is a potential candidate for photovoltaic application.