High thermal energy storage of the two-dimensional Al2Te3 semiconductor: DFT study of stability, electronic, phonon, thermal, and optical properties based on GGA and HSE06

Abstract

The present study investigates the structural, electronic, thermal, and optical properties of a novel two-dimensional Al₂Te₃ using GGA and HSE06 functional in the framework of density functional theory. The formation energy, the phonon dispersion, and AIMD calculations confirm the structural, dynamical, and thermal stability of Al₂Te₃, respectively. The electronic band structure and partial density of states indicate the semiconducting characteristics of 2D Al₂Te₃ with band gap values of 1.92 eV (GGA) and 2.78 eV (HSE06). The thermal properties of Al₂Te₃ reveal a high heat capacity due to a very high phonon density of states. This property signifies the material's growing ability to store thermal energy. Thus the entropy demonstrates a continuous increase with temperature, adhering to the second law of thermodynamics. The analysis of optical properties of Al₂Te₃ demonstrates strong light interaction in the ultraviolet, UV, region, and the optical band gap is found to be larger than the electronic band gap for both GGA and HSE06 functional due to indirect behavior of the band gap. Furthermore, the static dielectric function, refractive index, and optical conductivity are found to be smaller in the case of HSE06 compared to the GGA which may be due to reduced transition probability, and less screening effects including in the HSE06 functional. These findings offer valuable insights into the potential applications of Al₂Te₃ in various fields, including thermal energy storage and optoelectronics.