Structure, electronic and optical properties of chalcopyrite-type semiconducting materials XGaY2 (X = Cu, Ag, Au; Y = S, Se, Te) for solar cell applications: A DFT study

Abstract

Due to a large scale demand of optoelectronics and photovoltaics devices, the study of chalcopyrite-type semiconducting materials has emerged as one of the significant domains for research. In this report, structure and physico-chemical properties of XGaY2 (X = Cu, Ag, Au; Y= S, Se, Te) are examined in terms of Density Functional Theory technique. The energy differences between the Highest Occupied Molecular orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) of these chalcopyrite-type materials range from 2.363 eV to 3.134 eV. The compound AuGaS2 with the maximum energy gap is observed as the most stable system. Chalcopyrite materials with low HOMO-LUMO gap have the highest refractive indices and dielectric constants. Similarly, materials having high HOMO-LUMO gap display a high optical electronegativity, vibrational frequency, infrared and Raman spectra. It is observed that HOMO-LUMO gap, optical electronegativity, vibrational frequency, infrared and Raman spectra gradually decrease from sulphur to selenium to tellurium.