Influence of Molybdenum and Chromium Doping on WO3 Thin Films Fabricated by Spray Pyrolysis: Structural and Optical Characterization
- Popescu A.G.M., Tudose I.V., Mouratis K., Romanițan C., Brîncoveanu O., Pachiu C., Manica D., Manica M., Șchiopu P., Vlădescu M., Ionescu O.N., Pascariu P., Koudoumas E., Suchea M.P. „Influence of Molybdenum and Chromium Doping on WO3 Thin Films Fabricated by Spray Pyrolysis: Structural and Optical Characterization” Surfaces and Interfaces, vol. 72, 107427, 2025.
- https://doi.org/10.1016/j.surfin.2025.107427
- IF – 6.3 CAS Ranking: Tier 1
Abstract
This study explores the structural, morphological, and optical evolution of WO₃ thin films doped with molybdenum (Mo) and chromium (Cr), fabricated by spray pyrolysis on glass and indium tin oxide (ITO)-coated glass substrates. Grazing incidence X-ray diffraction confirms that undoped WO₃ exhibits a monoclinic phase with average crystallite size ∼20 nm. Mo doping up to ∼1.83 at.% enhances crystallinity and maintains phase purity, whereas Cr doping (∼3.42 at.%) induces peak broadening, lattice strain, and crystallite size reduction to ∼14 nm. SEM and AFM investigations reveal that undoped WO₃ forms compact grains (∼50 nm) with smooth surfaces (Rₐ ≈ 24.6 nm), while moderate Mo doping (∼1.06 at.%) leads to porous nanostructures (∼100–120 nm) with decreased roughness (Rₐ ≈ 18.0 nm). Cr doping at ∼2.49 at.% induces anisotropic grain morphologies (nanorods/flakes), increased porosity, and peak surface roughness (Rₐ ≈ 39.3 nm). Raman analysis indicates dopant-induced redshifts and peak broadening linked to oxygen vacancy formation. Optical measurements show that Mo doping narrows the bandgap from 2.85 eV to ∼2.69 eV with increased transmittance (up to 67 %), while Cr doping reduces the bandgap to ∼2.44 eV but decreases transparency to ∼32 %. These results demonstrate that Mo and Cr dopants distinctly modulate WO₃ film properties, enabling tunability for use in gas sensing and electrochromic applications.