Synthesis and optical properties of nano-ZnO particles/mesostructured SnO2 composite

Through self-assembly approach, ZnO nanoparticles were prepared in the pores of mesostructured SnO2 and the assembled composite of ZnO nanoparticles/mesostructured SnO2 was obtained. Powder X-ray diffraction (XRD) results clearly showed the existence of mesostructure in the assembled composite after calcining at high temperature. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the morphology and showed ZnO nanoparticles in pores of mesostructured SnO2. Room temperature photoluminescence (RTPL) of the assembly solid of ZnO nanoparticles/mesostructured SnO2 was measured. Two emission bands were observed, one being an exciton emission with the peak position of about 406 nm and the other the visible emission with the peak position of about 500 nm. Compare with the nanostructured ZnO bulk, the photoluminescence intensity of the assembled composite of ZnO nanoparticles/mesostructured SnO2 was enhanced. The luminescence intensity of the assembled composite of ZnO nanoparticles/mesostructured SnO2 is five to six times higher than that of nanostructured ZnO bulk. It was suggested that the intensity enhancement of the exciton emission was due to band-edge exciton transition and the green emission was corresponded to the increase of the oxygen defect states in ZnO particle surface.