Exploring the optoelectronic structure and thermoelectricity of recent photoconductive chalcogenides compounds, CsCdInQ3 (Q = Se, Te)

Abstract

The photoconductive quaternaries, CsCdInQ₃ (Q = Se, Te), have been recently synthesized and have been shown to be potential materials for hard X-ray and γ-ray detection. These materials have relatively high densities and band gaps in the range of 1.5–3 eV, which make them fulfill the requirement of hard detection devices. In the present work, we investigate the metal chalcogenide, CsCdInQ₃ as deduced from a full potential linearized augmented plane wave method based on density functional formalism. The direct band gaps are estimated at the level of the EV-GGA functional, as 2.11 and 1.75 eV for CsCdInSe₃ and CsCdInTe₃, respectively. These values are in good agreement with the experimental measurements (2.40 and 1.78 eV) obtained from solid-state UV-vis optical spectroscopy. Optical parameters, including the dielectric constant, absorption coefficient, energy loss function reflectivity and refractive index, were also reported to investigate the potential role of these metal chalcogenide compounds for solar conversion application. Our calculated optical band gap was compared to the measured experimental values on a Lambda 1050 UV-vis-IR spectrophotometer in the range of 300–1500 nm. The thermoelectric properties discuss the variation of the electrical and thermal conductivity, Seebeck coefficient and power factor with the temperature variation using the Boltzmann transport theory.