Preparation of ZnO-carbon quantum dot composite thin films with superhydrophilic surface

Carbon quantum dots (CQDs)-ZnO composite thin films were prepared via ultrasonic mist vapour deposition (UMVD) method. The effect of different CQDs concentrations (C), substrate temperatures (T-s), nozzle-substrate distances and also post-annealing process on the thin film structure were considered and examined systematically. The effects of these parameters on optical, morphological and surface properties of the layers as well as their wettability were carefully investigated and discussed. It was found that for low T-s and short 'd', CQDs diffuse inside the layer during deposition and then were evaporated after annealing process making drastic changes in layer morphology and optical transmittance. On the other hand, for high T-s and long 'd', most of CQDs inside mist vapour drops are evaporated during deposition process. Therefore, the layer transmittance and morphology did not change notably after annealing. Interestingly, the layer prepared with C = 5 volume %, T-s = 470 degrees C and d = 9 cm was turned to super-hydrophilic surface after annealing process with contact angle of & x2053; 3o. Such a super-hydrophilic CQDS-ZnO thin film is highly beneficial for a wide range of applications which high wettability is required.

Automated summary

The study investigated the effects of different parameters such as CQDs concentrations, substrate temperatures, nozzle-substrate distances, and post-annealing on the structure of CQDs-ZnO composite thin films. It was found that these parameters significantly influenced the optical, morphological, and surface properties of the thin films. The diffusion and evaporation of CQDs during deposition and annealing processes played a key role in determining the final morphology and optical transmittance of the thin films.