Nanostructure modification and enhanced photoluminescence of In3+ doped WO3-x synthesized by solvothermal method

Tungsten trioxide (WO 3 ) is a promising functional oxide for optoelectronic and photonic applications; however, simultaneously controlling its morphology and defect structure remains a significant challenge. Herein, we demonstrate a facile hydrothermal strategy to synthesize indium-doped WO 3-x nanostructures and systematically investigate the correlation between dopant concentration, morphological evolution, and photoluminescence (PL) properties. By tuning the In 3+ content from 0 to 20 at%, the morphology progressively transforms from slender nanowires to nanorods and finally nanosheets, accompanied by lattice distortion and defect generation. The optical bandgap decreases from 3.23 eV to 2.73 eV, while the PL emission intensity exhibits a remarkable non-monotonic increase, reaching a maximum enhancement of approximately 10-times at 15 at% In 3+ . This enhancement is attributed to the synergistic effects of defect-induced radiative recombination centers and morphology-optimized light–matter interactions. Our findings establish a clear structure–property relationship for In-doped WO 3-x nanostructures and provide new insights into defect and morphology engineering for advanced WO 3 -based optoelectronic and photonic devices.