Influence of molybdenum and technetium doping on visible light absorption, optical and electronic properties of lead-free perovskite CsSnBr(3) for optoelectronic applications

Lead-free metal halide perovskites have nowadays become familiar owing to their potential use in solar cells and other optoelectronic applications. In this study, we carried out the structural, elastic, electronic, and optical properties of pure and metal (Mo/Tc) doped CsSnBr(3) by using the density functional theory. The metal doping CsSnBr(3) displays a narrowing band gap and as a result the optical functions exhibit high absorption and high conductivity in the visible region. Metal doping samples also reveal a high dielectric constant which indicates a low charge-carrier recombination rate and hence enhances the device performance. The optical absorption spectra of metal doped samples greatly shifted (red-shift) towards the lower energy region compared with the pure sample which creates a high-intensity peak in the visible region. The mechanical parameter reveals a highly ductile, soft, and flexible nature which indicates the suitability for use in thin films. The electronic band structure of metal-doped CsSnBr(3) shows an intermediate state that assists the excited electron to pass on from valence band to conduction band. The overall study suggests that lead-free CsSn(0.875)Tc(0.125)Br(3) perovskite is a promising candidate for solar cells and other optoelectronic applications.