Solution-processed CdS quantum dots on TiO2: light-induced electrochemical properties

Abstract

Mesoporous titanium dioxide (TiO₂) nanostructured thin films, formed by a simple chemical route, namely, the successive ionic layer adsorption reaction (SILAR) technique, were efficiently used to grow a cadmium sulphide (CdS) nanoparticle architecture for device grade applications. CdS nanoparticle have a highly symmetric size and shape that could be varied in a controlled manner (<10 nm size) depending on the number of SILAR immersions without the use of an organic linker molecule. XRD and HR-TEM studies showed the formation of CdS nanoparticles on TiO₂ nanoparticles. Such a nanomorphology showed good optical coverage over the visible region of light, and it revealed a red-shift with respect to the number of CdS layers, which was confirmed by both optical and external quantum efficiency studies. The photoelectrochemical performance of the TiO₂/CdS photoanodes showed that as the particle size of CdS increases with the number of SILAR immersions, the photocurrent density and photovoltage were found to be directly concurrent with the charge transport mechanism, which increases the cell efficiency.