Stepwise cosensitization through chemically bonding organic dye to CdS quantum-dot-sensitized TiO2 electrode

An organic dye (JK218) with thiol moiety as an anchoring group was synthesized and explored to assemble a cosensitized TiO2 electrode in combination with an inorganic CdS quantum-dot. Due to the selective adsorption of JK218 on the surface of CdS through thiol group, the developed cosensitized electrode demonstrates cascade architecture with CdS coating on TiO2 while JK218 functions as a covering on CdS. Most importantly, the energy levels of the TiO2-CdS-JK218 electrode were also found to be stepwise aligned, which accordingly makes electrons efficiently inject from JK218 to CdS under illumination and finally collect to TiO2. This constructed cosensitized electrode with an organic sensitizer (JK218) and an inorganic quantum-dot (CdS) being selectively bonded together is expected to be valuable for the interface design of next generation solar cells. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3533906]