Synthesis and characterization of undoped and Co-Doped Bismuth Ferrite nanoparticles for photovoltaic applications

Abstract In this paper, we reported the structural, vibrational, and optical absorption properties of chemically synthesized multiferroic bismuth iron oxide (BiFeO3) (BFO) and cobalt-doped bismuth iron oxide (BFCO) nanoparticles. The nanoparticles were synthesized via sol–gel methods and annealed at 450 °C for a duration of two hours. Characterization was conducted through techniques such as UV–Vis spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), and Scanning Electron Microscope (SEM). XRD analysis revealed average crystallite sizes of 19.1 nm and 20.8 nm for BFO and BFCO, respectively, with no secondary phase observed in the cobalt-doped BFO nanoparticles. Structural analysis via XRD indicated a transformation from rhombohedral to orthorhombic symmetry in the doped BFO nanoparticles. The optical band gap energies were determined to be 2.43 eV for BFO and 2.33 eV for BFCO. The reduction in the band gap in BFCO may be help for relevant for the photovoltaic application. FTIR spectroscopy identified characteristic peaks, including the O–H single bond at 3417 cm−1 and vibrations corresponding to metal–oxygen/Fe–O, Bi–O stretching, and O–Fe–O bending vibrations in BFO and BFCO within the spectral range of 400–1000 cm−1. The morphology and crystallinity of these materials were assed using a SEM, revealing a progressively complex arrangement of flower structures in both BFO and BFCO.