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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 CsGeCl 3 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 CsGeCl 3 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 CsGeCl 3 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 CsGeCl 3 . The study of electronic properties shows that the excitation of photoelectrons is easier due to the formation of intermediate states in Mn-doped CsGeCl 3 . As a result Mn-doped CsGeCl 3 exhibits higher absorptivity in the visible region than the Ni-doped counterpart. A combinational analysis suggests that CsGe 1-x Mn x Cl 3 is the best lead free candidate among the inorganic prsovskite materials for solar cell and optoelectronic applications.

Non-toxic (lead-free) inorganic perovskites have seized the leading position in the race for the commercialization of solar cells and other photovoltaic devices.

Spinel-type ferrites are widely used in practical applications. A fascinating property of Zn-Ni ferrites which reveals a direction for application is reported. A large negative magnetoresistance effect has been observed in ZnFe2O4 and Ni substituted Zn1−xNixFe2O4 ferrites of spinel structure. These materials are either ferrimagnetic or paramagnetic at room temperature and a spin (cluster) glass transition was found for some compositions at low temperatures. The magnetoresistance is either parabolic or linear with respect to applied field up to 9 T depending on the compositions and temperatures. It was found that the magnetoresistance effect increases as the Ni content increases in Zn1−xNixFe2O4 up to x=0.2 and then again decreases and finally become negligible for x=1.0, i.e., NiFe2O4. This magnetoresistance effect can be explained with the help of spin-dependent scattering and the Yafet-Kittel angle of the Ni-substituted Zn-Ni ferrites.

We report on the cluster glass nature and photoinduced magnetization ͑PIM͒ of ͑Ni, Zn, Fe, Ti͒ 3 O 4 thin films prepared using a pulsed-laser deposition ͑PLD͒ technique. The films exhibit cluster glass behaviors with a spin-freezing temperature T f of approximately 230 K. It was found that the magnetization increases following light irradiation below T f . The experimental results suggest that the electronic transitions induced by photons are intrinsic to the observed PIM rather than the thermal heating effects resulting from light irradiation. The change in the magnetization from the original dark value at 10 K was approximately 40% for the Ni 0.7 Zn 0.3 Fe 1.7 Ti 0.3 O 4 film, and it was approximately 5% for the Ni 0.4 Zn 0.6 Fe 2 O 4 film when the excitation intensity is 1.48 mW/ mm 2 . The analysis of the excitation energy dependence of PIM suggests that an intervalence charge transfer Ti 4+ +Fe 2+ → Ti 3+ +Fe 3+ contributes to the observed enhancement in the PIM of the Ti-substituted films.