Structural, Electronic, and Optical Properties of CsPb(Br(1−x)Cl(x))(3) Perovskite: First-Principles Study with PBE–GGA and mBJ–GGA Methods

The effect of halide composition on the structural, electronic, and optical properties of CsPb(Br(1−x)Cl(x))(3) perovskite was investigated in this study. When the chloride (Cl) content of x was increased, the unit cell volume decreased with a linear function. Theoretical X-ray diffraction analyses showed that the peak (at 2θ = 30.4°) shifts to a larger angle (at 2θ = 31.9°) when the average fraction of the incorporated Cl increased. The energy bandgap (E(g)) was observed to increase with the increase in Cl concentration. For x = 0.00, 0.25, 0.33, 0.50, 0.66, 0.75, and 1.00, the E(g) values calculated using the Perdew–Burke–Ernzerhof potential were between 1.53 and 1.93 eV, while those calculated using the modified Becke−Johnson generalized gradient approximation (mBJ–GGA) potential were between 2.23 and 2.90 eV. The E(g) calculated using the mBJ–GGA method best matched the experimental values reported. The effective masses decreased with a concentration increase of Cl to 0.33 and then increased with a further increase in the concentration of Cl. Calculated photoabsorption coefficients show a blue shift of absorption at higher Cl content. The calculations indicate that CsPb(Br(1−x)Cl(x))(3) perovskite could be used in optical and optoelectronic devices by partly replacing bromide with chloride.