Synthesis and characterization of Ni:ZnO thin films as photoanode for planar perovskite solar cell

Thin films of Ni:ZnO were successfully synthesized by sol-gel spin coating system for 0.5 % and 2.5 % Ni doping concentration on FTO coated substrate. The synthesized films were annealed at 540 °C for 4 h. The annealed thin films were characterized for its electrical, optical and chemical characteristics using UV–Vis, Micro Raman, and FTIR spectroscopy, respectively. The UV–Vis spectra analysis reveals that the energy band gap of deposited films found to be 3.58 eV and 3.51 eV for 0.5 % and 2.5 % Ni:ZnO thin films, respectively. Two significant characteristic peaks identified at 424 cm⁻¹ and 563 cm⁻¹ in Raman spectra. These peaks are attributed to $E_2^{high}$ and LO(A₁ and E₁) modes, which confirms the hexagonal wurtzite phase of Ni:ZnO thin films. Furthermore, the absorption peaks observed at 530 cm⁻¹ and 635 cm⁻¹ in the FTIR spectra are attributed to the characteristic stretching vibrational modes of Zn-O and Ni-O bonds, respectively.