Zinc tin oxide nanocomposites with nanodiamonds – Preparation, characterization and optical properties investigations

As one of the transparent semiconducting oxides (TCOs), zinc tin oxide (ZTO) has gained a tremendous technological importance owing to its large scale applications, particularly, in opto-electronic devices. Nonetheless, the optical band gap of ZTO is always desired to be tuned, and thus optimized for a particular application. Herein we report upon varying the optical band gap of ZTO nanomaterials by using chemically functionalized nanodiamonds (NDs) as reinforcement for the very first time. ZTO nanocomposites with different weight percent (wt.%) i.e., 5wt.%, 10wt.% and 15wt.% of NDs were prepared by simple solution method, employing poly(methyl methacrylate) (PMMA), prepared in-situ, as structure directing agent (SDA). The crystal structure were established by powder X-rays diffraction (PXRD) analysis. Energy dispersive X-rays spectroscopy (EDX) was used to determine the elemental composition of the samples. The impacts of synthesis method and NDs addition upon the morphology of ZTO nanocomposites were studied by scanning electron microscopy (SEM). SEM revealed that the particle size of ZTO nanocomposites varies as a function of NDs contents. The optical energy band gaps of the resulting nanomaterials were studied by UV–vis diffused reflectance spectroscopy (DRS), and it was observed that the band gap increases with increases NDs contents. However, the absorption intensity decreased with increasing NDs contents, particularly, in the visible region. The optical properties were further investigated by photoluminescence (PL) spectroscopy, and it was revealed that the intensity of PL spectra decreases with increasing NDs contents in the resulting ZTO nanomaterials. This was owed to the passivation of excessive Zn⁺ by NDs, decreasing the lattice defects which are responsible for deep level emission (DLE).