  Solid solutions of perovskite oxides (KNbO3)1-x+(La2NiMnO6)x (x=0, 0.1, 0.2
and 0.3) with a variation of band gap (1.33-3.6 eV) have been introduced as a
promising photovoltaic absorber. The structural characterization of the
prepared samples was carried out using X-ray diffraction (followed by Rietveld
refinement) and Raman experiment. As the doping percentage of the monoclinic
La2NiMnO6 in the solid-solution increases, the crystal structure of host KNbO3
becomes more symmetric from orthorhombic to cubic. A large reduction in the
particle size has also been observed in the solid solutions in comparison to
the pure KNbO3. The band gap (~ 1.33 eV) of the synthesized solid solution
x=0.1 is found to be very close to the Shockley-Queisser band gap value of 1.34
eV, which suggests the promising photovoltaic possibility in this material.
Photoluminescence (PL) emission spectra reveal a strong PL quenching in the
solid-solutions in comparison to the KNbO3. The overall structural and optical
studies suggest the promising photovoltaic possibility in KNbO3/ La2NiMnO6
solid solution.
