Solvothermal synthesis of CdS nanorods and photovoltaic characteristics of CdS/PVK composite system

Large quantities of CdS nanorods are successfully synthesized through Cd(CH3COO)(2)center dot 2H(2)O reacting with Na2S center dot 9H(2)O and EDA in aqueous solution. XRD result shows that the sample is of hexagonal structure. And TEM result shows that the morphologies of the resulting CdS are mainly in three-armed rod-like structure with a diameter of 10-15 nm and a length of 100 nm. The nanocomposites of CdS/PVK with different molar ratios are prepared by spin coating method on tin-doped indium oxide (ITO) substrate. A notable decrease of photoluminescence (PL) efficiency and a significant enhancement of surface photovoltage signal have been observed in CdS/PVK composites when the molar fraction of CdS increases. We interpret these results as the energy level matching between CdS and PVK in nanocomposites. This energy level matching facilitates fast interfacial charge transfer then increases the separation efficiency of electron-hole pairs and the carrier generation efficiency. The detailed charge transfer process has also been demonstrated.