Effect of Metal Doping on the Visible Light Absorption, Electronic Structure and Mechanical Properties of Toxic-Free CsGeCl3 Metal Halide

Toxic-free metal halide perovskites have become forefront for commercialization of the perovskite solar cells and optoelectronic devices. In the present study, for the first time we show that particular metal doping in CsGeCl3 halide can considerably enhance the absorbance both in the visible and ultraviolet light energy range. By using DFT based first principles method Mn and Ni is doped at the Ge-site of CsGeCl3 halide. We investigate the detailed structural, optical, electronic and mechanical properties of all the doped compositions theoretically. The study of optical properties exhibits that the absorption edge of both Ni and Mn-doped CsGeCl3 is shifted toward the low energy region (red shift) relative to the pristine one. An additional peak is observed for both doped profile in the visible light energy region. The study of mechanical properties ensures that both the doped samples are mechanically stable and ductile as the pristine CsGeCl3. The study of electronic properties shows that the excitation of photoelectrons is easier due to the formation of intermediate states in Mn-doped CsGeCl3. As a result Mn-doped CsGeCl3 exhibits higher absorptivity in the visible region than the Ni-doped counterpart. A combinational analysis suggests that CsGe1-xMnxCl3 is the best lead free candidate among the inorganic prsovskite materials for solar cell and optoelectronic applications.