Luminescent photoelectrochemical cells. Use of tellurium-doped cadmium sulfide photoelectrodes to probe surface recombination during the conversion of optical energy to electricity

Abstract

It is reported that photoelectrochemical cells employing n-type Te-doped CdS (CdS:Te) photoanodes provide a sensitive probe of the manner in which the semiconductor excited state partitions input optical energy. Photoelectrochemical events are presumed to result from separation of a photogenerated conduction band electron and valence band hole, a consequence of the band bending which characterizes the depletion region created by the semiconductor-electrolyte interface. The observation of emission in an operating photoelectrochemical cell signifies that the radiative recombination of electron-hole pairs occurs in direct competition with nonradiative separation leading to electrochemistry. It is demonstrated that this competition is sensitive to the electrode potential of the photoelectrochemical cell, which affects band bending.