Preparation and optimization of SnOx thin film by solution method at low temperature

SnOx films were prepared by sol-gel spin coating technology on glass substrates at low temperature. Through the optimization of the solution process, the quality of the film was effectively improved. And the effects of rotating speed, substrate pretreatment and precursor concentration and other parameters on the films were emphatically discussed. It is found that the formation of the impurity particles and holes can be reduced and the film roughness can be decreased by treating the substrate with plasma. Adding a low-speed spin coating process before high-speed spin coating can significantly reduce the roughness of film. The roughness of film decreases, and the edge shrinkage phenomenon of film is improved with the increasing spin-coating speed. The thickness of the film increases linearly with the solution concentration, but the high concentration of precursor is easy to lead to the cracks of films. Based on the optimized solution process, SnOx films with flat, smooth surface (Rq = 0.25 nm) and high transparency (visible light transmittance >90%) can be prepared at low temperature, which is expected to be used in devices based on transparent films. •High-quality SnOx film was prepared at low temperature by optimized solution process.•The roughness of SnOx film was significantly reduced by optimizing the parameters of the solution method, which was 0.25 nm.•The SnOx film exhibits excellent transparency of 97% in visible region.