CdSe-SnO₂ coupled semiconductor thin films: Electrochemical and photoelectrochemical studies

Abstract

The coupled OTE/SnO₂/CdSe electrodes have been prepared by sequential deposition of SnO₂ and CdSe colloidal films onto an optically transparent electrode (OTE), and their electrochemical and photoelectrochemical properties have been studied. It is observed that coupling SnO₂ film with CdSe particles has extended its photoresponse into the visible. The incident photon-to-photocurrent conversion efficiency (IPCE) for CdSe film which is doubled when coupled with SnO₂ film, shows a better charge separation in the coupled film. The cyclic voltammetric results of [Fe(CN)₆]^3−/4− with OTE, OTE/CdSe and OTE/SnO₂/CdSe electrodes suggest that the coupling of CdSe with SnO₂ creates an energy barrier that hinders electron flow from SnO₂ to CdSe and into the electrolyte. Photocurrent stability of the cell employing OTE/SnO₂/CdSe electrode has been improved by increasing the thickness of SnO₂ particulate film. The photoelectrochemical performance of the cell has been evaluated and a net conversion efficiency of 2.25% has been obtained