Crystal growth. of CdSe quantum dots adsorbed on nanoparticle, inverse opal, and nanotube TiO2 photoelectrodes characterized by photoacoustic spectroscopy

The crystal growth of semiconductor quantum dots (QDs) adsorbed on nanostructured TiO2 photoelectrodes is important not only for crystallographic studies but also for improving the photovoltaic efficiency of semiconductor-sensitized solar cells. In this study, nanoparticle, inverse opal, and nanotube TiO2 electrodes are prepared. These electrodes are then adsorbed with CdSe QDs as photosensitizers to investigate crystal growth. The average diameters of the CdSe QDs can be estimated from the photoacoustic (PA) spectra. When the adsorption time increases, the CdSe QD diameter increases and then shows saturation. Normal solution growth plus suppression (negative growth) can be obtained by PA analysis. Both of them depend on the morphology of TiO2 electrodes and the final solution concentration for the CdSe QD preparation.