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Post-annealing effects on the structural and optical properties of nickel vanadate thin films.
Author(s)
Nedkun, Piyanooch
Sangsai, Phannita
Wongrat, Ekasiddh
Chaiworn, Panupat
Tubtimtae, Auttasit
Date Issued
May 15, 2026
Type
Article
Abstract
Abstract This research gap is to understand the post-annealing-temperature-dependent structural transition and defect-mediated optical tuning in NiV₂O₆ thin films deposited using a spin-coating technique. By systematically correlating phase evolution, oxygen vacancy formation, and band gap modulation. The as-prepared thin films were annealed at 200 °C, 300 °C, 400 °C, and 500 °C. The annealing temperature of 400 °C was found for an amorphous structure with the band gap of 2.38 eV, which within an appropriate band gap of ∼ 2.3–2.6 eV for photoelectrochemical and electrochromic applications. Tuning of improved crystallinity with structural rearrangement and a lower band gap of 2.10 eV were obtained at 500 °C, which induced the diffusion of oxygen atoms and led to the formation of oxygen vacancies. This provides a clear processing–structure–optical property correlation and offers a simple-thermal route for band gap engineering without additional doping for enhancing the optical efficiency in solar absorber, optoelectronic, and photonic applications, particularly in broadband optical devices.
Citation
Materials Letters, 411, 2026