Experimental investigation of blue and green colour emission in CsPbX3 (X= Cl & Br) quantum dots with theoretical insight

In recent years, Cesium lead tri-halide based wide energy gap inorganic perovskites becomes as an emerging material for novel photovoltaic and optoelectronic devices due to their room temperature stability. Herein, synthesis and characterization of CsPbX₃ (X= Cl & Br) quantum dots (QDs) have been performed to examine the structural, photophysical and electronic nature. X-ray diffraction (XRD) pattern indicates the high crystalline behavior of these synthesized compounds. Photoluminescence (PL) plots for these synthesized compounds correspond to the emission of Blue and Green color for CsPbCl₃ and CsPbBr₃ respectively. Further, the theoretical calculation has been also performed using Density functional theory (DFT) to validate our experimental results. Optimization has been done to bring the geometry in the ground state and lattice parameter has been obtained for CsPbCl₃ (5.58 Å) and CsPbBr₃ (5.82 Å) compounds which are consistent with the experimental results. Electronic band structure shows a direct bandgap behaviour for CsPbCl₃ (3.07 eV) and CsPbBr₃ (2.29 eV) compounds. Moreover, to examine the optical behavior of these QDs, the optical absorption coefficient has been computed. The optical behavior of these QDs shows significant optical absorption in both visible and ultraviolet regions. The calculated results using DFT show a very good agreement with our experimental characterized results. This study suggests applications of these QDs as a promising compound for Blue and Green LEDs.