Characteristic of spontaneous emission from CdSe/ZnS core-shell quantum dots near the surface of self-assembled three-dimensional photonic crystals

Abstract

We investigate experimentally the emission behavior of CdSe/ZnS core-shell quantum dots (QDs) which are intentionally placed near the surface of a self-assembled three-dimensional photonic crystal (PC) by photoluminescence (PL) intensity and PL decay rate measurements. The results show that the spontaneous emission of QDs in the composite with TiO2 films in between PC and QDs (QD-TiO2-PC composite) was largely enhanced over the band gap and electron transfer from CdSe QDs into TiO2 particles was largely inhibited by the surface states of PC. While in the composite without TiO2 films, the spontaneous emission was inhibited in the band gap and enhanced on the long wavelength edge of the band gap of the PC owing to the influence of the band gap of PC and injection of electrons from QDs into the surface modes of PC.