Investigation of electronic structure and optical properties of thallium lead halides: First principle calculations

Abstract

Using first principle calculations, we comprehend the electronic structure and optical constant of thallium lead halides TI3PbX5 (X = Cl, Br, I), which are viewed as potential materials for mid-infrared and near-infrared applications. The generalized gradient approximation function given by Perdew-Burke-Ernzerhof is used for geometry optimization and properties calculations. The calculated Mulliken charges are more positive for Pb than TI in the TI3PbCl5 system demonstrating a high electronic density contribution from the Pb-Cl bonds in contrast to the TI-Cl bonds. Similarly, the TI3PbCl5 configuration displays the smallest enthalpy value suggesting a more stable structure among different TI3PbX5 species studied in this work. The band gap value for TI3PbCl5 has been calculated as 3.52 eV, which decreases to 3.14 eV and 2.64 eV for the TI3PbBr5 and TI3PbI5, respectively. Additionally, the TI3PbI5 exhibits a high magnitude of real component of static dielectric function ε1(k) in contrast to TI3PbBr5 and TI3PbCl5. The optical absorption results display a redshift when TI3PbCl5 is doped with Br and I sequentially. These outcomes suggest that the concentration of halide elements can be adjusted to enhance the optical properties of TI3PbX5 for optoelectronic device applications.