SYNTHESIS, STRUCTURAL AND PHOTO PHYSICAL PROPERTIES OF PEROVSKITE OXIDE (KNbO_3)_(t-x) + (La2NiMnO_6)_x FOR PHOTOVOLTAIC APPLICATION

摘要

Solid solutions of perovskite oxides (KNbO_3)_(1-x) + (La_2NiMnO_6)_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 La_2NiMnO_6 in the solid-solution increases, the crystal structure of host KNbO_3 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 KNbO_3. 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 KNbO_3. The overall structural and optical studies suggest the promising photovoltaic possibility in KNbO_3/La2NiMnO_6 solid solution.