Electronic and Optical Response of Chalcopyrites Cu₂InMSe₄ (M = Al, Ga): First Principles Investigation for Use in Solar Cells

Abstract

We report systematic investigations of opto-electronic behavior of promising semiconducting chalcopyrite compounds Cu₂In(Al,Ga)Se₄ within the framework of density functional theory. In view to explore their possible utilization in opto-electronic devices, we have firstly performed calculations using one of the most accurate prescriptions, namely full-potential linearized augmented plane wave method. For a better accuracy, computations have been carried out using different exchange–correlation potentials including the most accurate modified Becke–Johnson potential with hybrid functional features. Computations have been performed for various electronic and optical properties such as energy bands, total and partial density of states, real and imaginary parts of dielectric tensors, absorption spectra, reflection, refraction and energy loss spectra for both chalcopyrite compounds. We have compared our data with the existing experimental and theoretical calculations for both compounds, which validates the accuracy of present computations. Both chalcopyrites are observed to have a direct band gap nature (Cu₂InAlSe₄: 1.14 eV and Cu₂InGaSe₄: 0.96 eV). Energy peaks recorded in the imaginary part of dielectric tensors are well interpreted by means of inter-band transitions. Significant intensities observed in absorption spectra within the energy range of solar spectra unambiguously depict feasibility of these compounds in optoelectronic devices.