Photoluminescence properties of SnO2 nanoparticles doped with group VI elements (Cr, Mo, W) synthesized by pulsed laser ablation in liquid

Tin oxide nanoparticles (SnO₂ NPs), both pure and doped with Group VI (G6) metal ions (Cr⁺³, Mo⁺⁵, and W⁺⁶), were synthesized using pulsed laser ablation in liquid. This study aimed to investigate the effect of G6 doping on the electronic properties of SnO₂ NPs, with an emphasis on enhancing their photoluminescence for optoelectronic applications. Transmission electron microscopy revealed well-crystallized samples with diameters of 3–6 nm, indicating quantum-confinement effects. The optical band gap, determined by UV–Vis spectroscopy, was reduced from 5.1 eV (undoped) to 4.9 eV (Cr-doped) due to defect states, while increasing to 5.3 eV and 5.7 eV for Mo- and W-doped SnO₂, respectively, due to the Moss-Burstein effect. The photoluminescence spectra exhibited a redshift, with strong red emission around 700 nm, which was up to 90 % more intense than that of the undoped SnO₂. This enhancement was attributed to the ²E→⁴A₂ transition and increased defect states.