Co-sensitising cadmium selenide and cadmium telluride quantum dots on titanium dioxide nanorods via the SILAR method

Abstract

Co-sensitised CdSe/ CdTe quantum dots (QDs) on the surface of TiO2 nanorods were fabricated via different cycles of successive ionic layer adsorption and reaction (SILAR) method. The deposition of the QDs onto TiO2 nanorods were confirmed with transmission electron microscopy. A higher number of SILAR cycles has led to QDs aggregation and overgrowth on the top layer of the TiO2 nanorods layer. Furthermore, the higher number SILAR cycles also lowered the charge transfer resistance as observed in the electrochemical impedance spectroscopy analysis. Based on the observation, 5 cycles were selected to be the optimized number of SILAR cycle. The sequential deposition of CdTe QDs increased the absorption intensity and extended the absorption spectra, demonstrating co-sensitisation effects, which increase the short circuit current density from 0.103 mA cm−2 to 0.158 mA cm−2 is shown to enhance the CdSe quantum dots sensitised solar cells (QDSSC) efficiency from 0.009 % to 0.018 %.