A highly luminescent quantum dot/mesoporous TiO₂ nanocomplex film under controlled energy transfer

We have prepared a highly luminescent quantum dot (QDs)-TiO2 nanocomplex film by the dip coating method. Because QDs with 3-mercaptopropionic acid as a ligand adsorb ionized Ti+ cations on the TiO2 particle, the average distance between the QDs can be changed through controlling the porosity in the film. The porosity is controlled using ethyl cellulose (EC). EC is the best material for well dispersing the hydroxyl functional group (-OH) in the chemical structure, and forming pores inside the film under the decomposition temperature (above 698 °F). As the porosity decreases, the average decay time controlled by the porosity increases to the maximum 91.2 ns. On the other hand, the amount of QDs decreased to 50%, hindering the increase of photo-luminescence (PL) intensity. Through this result, we have found that the PL intensity of the QD films is strongly related to the amount of the QDs and the resolution of aggregation. Consequently, we have optimized the porosity of the film and obtained high PL intensities up to approximately 17 times.