Ab-initio study of halogen inter-substituted perovskite cesium lead halides for photovoltaic applications. (February 2022) - Kumari, Anuja
Abstract: We report the ab-initio study of structural, electronic and optical properties of perovskite cesium lead halides within density functional theory. The lattice constants computed from energy-volume plots are employed to compute band structure within improved Becke-Johnson potential modified by Tran and Blaha for exchange and LDA as for correlation effects. The computed band gap values for pristine CsPbCl3, CsPbBr3 and CsPbI3 are in good agreement with the experimental reports. The obtained band structure has been employed for obtaining optical properties of the studied halides CsPbX3 (X = Cl, Br, I) within RPA. The effect of halide inter-substitution in CsPbX3- x Y x (X, Y = Cl, Br, I) system has also been studied. We find that CsPbCl2 I and CsPbBr2 I have high absorption peaks in real and imaginary parts of dielectric function indicating high absorption and capacity to store electrostatic energy. The Born stability conditions indicate that CsPbCl2 I is stable whereas CsPbBr2 I is not. Our study also finds the possibility of auxetic character in inter-substituted halide perovskites as reflected from negative Poisson's ratio. Therefore, CsPbCl2 I seems best suited for optoelectronic devices and photovoltaic applications. Highlights: The perovskite CsPbX3- x Y x (X, Y = Cl, Br, I) system is studied within improved Becke-Johnson exchange potential. The structural, electronic and optical properties computed within random phase approximation are in good agreement with existing reports. The Born stability conditions indicate that all the studied compositions except CsPbBr2 I, CsPbCl2 Br and CsPbI2 Br are stable. CsPbCl2 I and CsPbBr2 I have high absorption peaks in real and imaginary part of dielectric function indicating high absorption. CsPbCl2 I seems best suited for optoelectronic devices and photovoltaic applications.