Bandgap tuning of Mn-doped BiFeO3 thin films for photovoltaic application

The Mn doped BFO thin films were made on the glass substrates by simple spin coating method and its structural and optical properties were examined. The results obtained from X-ray diffraction pattern of Mn doped BFO confirmed the rhombohedral distorted perovskite structure with stress relaxation. The Bi-O and Fe-O bonds were detected in the perovskite structure, the shifting of all the stretching and bending vibrations of pristine BFO was observed from FTIR analysis. The XPS spectra of Mn-doped BFO thin film declared that the valence states of Bi, Fe and Mn from their respective binding energies. A narrow optical band gap energy of 1.65 eV was observed for Mn doped BFO as against the pristine BFO (2.17 eV) that indicated a reduction in the band gap energy between O 2p valence and Fe 3d conduction band upon Mn doping.