DFT and experimental investigations on CdTe1-xSex for thermoelectric and optoelectronic applications

Abstract

The optical and electronic characteristics of CdTe-based semiconductors play an important role in modern optoelectronic devices. In the current study, pure and Se doped CdTe compositions were theoretically investigated through density functional theory within the framework of Wien2k code using a modified Becke–Johnson technique. Experimentally CdTe1−xSex (x = 0, 3.125 %, 6.25 %, and 12.5 %) uniform and evenly distributed thin films were successfully deposited through a chemically derived sol-gel-based spin coating technique. The morphological, electronic, thermoelectric, and optical properties were studied through comparative simulations and experimental investigations. Ab-initio and experimental results reveal the similarities and correlation among the findings. The experimental energy band gap was found to reduce from 1.84 eV for pure CdTe to 1.55 eV by incorporation of Se in the pristine CdTe structure. The thermoelectric response in terms of electrical conductivity, Seebeck coefficient, thermal conductivity, and specific heat was recorded and a significant variation was observed. The optical parameters show an enhanced trend in the visible regime with the incorporation of Se content in structure. Absorption coefficient and real epsilon were shown to a sharp increase with increment of Se content. The outcomes of this work are considered that Se containing CdTe composition are promising candidates for enhanced thermoelectric and optoelectronic applications.