Effects of precursor, temperature, surface area and excitation wavelength on photoluminescence of ZnO/mesoporous silica nanocomposite

Abstract

This paper reports on the effects of precursors, annealing temperature, surface area of host and excitation wavelength on photoluminescence (PL) of ZnO/mesoporous silica (MPS) nanocomposite. The samples were characterized with SAXRD, XRD, BET surface area and pore size analyzer, FE-SEM, HR-TEM, UV–vis absorption, FT-IR and PL spectrometers. The absorption band for ZnO nanoparticles embedded in MPS was detected at around 320 nm. A PL band positioned at around 393 nm has been observed in all the samples. Intensity of the PL band increased up to 550 °C and decreased when temperature reached to 700 °C. It is found that emission intensity enhanced along the rise in surface area of the host. This may be due to the enhancement in the density of Zn–O–Si bonds with increase in surface area. In addition, PL band is tuned from 393 nm to 504 nm by changing only the excitation wavelengths from 320 nm to 450 nm. The relationship between luminescence peak position and excitation wavelength is linear. This observation may be attributed to the size distribution of the particles and also a different distribution of different emissive sites on each passivated ZnO nanoparticle.