Thermally Induced Phase Transition and Defect‐Assisted Nonlinear Absorption and Optical Limiting in Nanorod Morphology V2O5 Thin Films

Abstract

Vanadium pentoxide (V2O5) thin films are greatly favorable materials for optoelectronic applications due to their broad optical bandgap and considerable thermal and chemical stability. Herein, the influence of thermal treatment on the microstructure related to the nonlinear optical, optical limiting, and phase transition behaviors of V2O5 thin films produced via ultrasonic spray deposition method onto FTO/glass substrates is systematically examined by Z‐scan experiments. Homogenous and crack‐free V2O5 thin films with nanorod morphology are obtained after thermal treatment. OA Z‐scan results indicate that the whole V2O5 thin films exhibit defect‐assisted nonlinear absorption behavior, and annealing at 450 °C increases the nonlinear absorption and optical limiting behavior. Higher annealing temperatures, in contrast, lead to a decrease in these behaviors. CA Z‐scan trace shows that the sign of nonlinear refractive index inverted by thermal process. The phase transition is associated with crystalline V2O5 thin films via thermal process. V2O5 thin films annealed at 450 °C are promising optical limiters within the 500–700 nm visible range due to their high linear transmittance (> 80%) and low optical limiting threshold.