Band gap engineering and optoelectronic properties of europium-doped cesium tin chloride (Eu-doped CsSnCl3) perovskite using a DFT based first-principles GGA+U+SOC approach for PC-LED applications

This research investigates the potential of europium-doped cesium tin chloride perovskite (Eu-doped CsSnCl₃) as phosphor material for LED applications. We conducted computational analysis using first-principles calculations, specifically implementing the GGA+U+SOC methodology through WIEN2k software, to evaluate how europium (Eu) substitutional doping affects the material's electronic and optical behavior. The study compared pure CsSnCl₃ with two europium doping concentrations: a single-atom case Eu-CsSnCl₃ (2.5 %) and a double-atom scenario of 2Eu-CsSnCl₃ (5 %). Our findings demonstrate that Eu incorporation significantly alters the electronic band structure, with the band gap decreasing from 3.2 eV in pristine CsSnCl₃ to 1.009 eV and 0.967 eV for the 2.5 % and 5 % europium concentrations, respectively. This modification occurs through the formation of additional electronic states within both the valence and conduction bands. The research revealed that the 2.5 % europium concentration yielded optimal optical characteristics, particularly within visible light wavelengths, exhibiting improved absorption coefficients and more pronounced optical features compared to both the pristine material and the 5 % Eu variant. Through examination of dielectric properties, optical conductivity, and energy loss patterns, we determined that europium incorporation creates optimal conditions for light absorption and emission processes. These results indicate that precisely controlled Eu doping of CsSnCl₃ represents a viable approach for developing advanced phosphor materials with adjustable color properties and enhanced performance for future LED applications.