First-Principle Study of Lead-Free K_۳TlCl_۶ Material Using Density-Functional Theory (DFT) Method for Opto-Photovoltaic Applications

Less toxicity and tunable electrical characteristics make lead-free perovskites a potential material for next-generation optoelectronic and renewable energy devices. Despite recent advances, the study of a perovskite-type compound, K₃TlCl₆, has not been reported thus far, and thus its mechanical stability and optoelectronic potential remain absent in available literature. In this work, the structural, mechanical, electrical, and optical characteristics of K₃TlCl₆ were reported. Band structure, electron density, elastic behavior, and optical responses were calculated by using the CASTEP code within the generalized gradient approximation with the Perdew-Burke-Ernzerhof functional. The material exhibits a direct bandgap of ۲.۱۶ eV, which is primarily contributed by the Tl-۶p, Cl-۳p, and K-۳p states near the Fermi level, reflecting improved visible–UV absorbance (~۱۰⁴–۱۰⁵ cm⁻¹) compared to many halide perovskites. All the advanced optical parameters, such as reflectivity, conductivity, refractive index, extinction coefficient, and dielectric response are superior to the standard parameters of perovskites. Mechanical and elastic studies confirm a structurally stable crystalline framework. Thus, K₃TlCl₆ would be a robust and efficient material for visible/UV photodetectors, and optoelectronic applications.

کلیدواژه ها:

DFT ، PDOS ، Band Structure ، ۳D EDD ، MECHANICAL ، Optical characteristics