Tl₄CdI₆ - Wide band gap semiconductor: First principles modelling of the structural, electronic, optical and elastic properties

A novel infrared optoelectronic material Tl₄CdI₆ was studied using the density functional theory (DFT)-based techniques. Its structural, electronic, optical and elastic properties were all calculated in the generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) and the local density approximation (LDA) with the Ceperley-Alder-Perdew-Zunger (CA-PZ) functionals. The studied material is a direct band gap semiconductor with the calculated band gaps of 2.043 eV (GGA) and 1.627 eV (LDA). The wavelength dependence of the refractive index was fitted to the Sellmeier equation in the spectral range from 400 to 2000 nm. Good agreement between the GGA-calculated values of refractive index and experimental data was achieved. To the best of our knowledge, this is the first consistent theoretical description of the title compound, which includes calculations and analysis of the structural, electronic, optical and elastic properties.