Effect of photonic band-gap on photoluminescence of ZnO deposited inside the green synthetic opal

The temperature dependent photoluminescence spectra of ZnO embedded in the voids between the fcc packed SiO2 sub-micron spheres by using a spray pyrolysis were studied. In contrast to ZnO powder, the ZnO inside the green synthetic opal exhibit a broadened dominant excitonic band edge emission and rapidly decreasing deep level emission with decreasing temperature. The overlap between photonic and electronic band-gaps of the opal matrix and ZnO prevents the radiative recombinations through native defects resulting to the suppression of the photoluminescence intensity in the green spectrum. The growth of ZnO inside the green synthetic opal may be useful technique to enhance the UV-blue emission.