Luminescent Photoelectrochemical Cells. 4. Electroluminescent Properties of Undoped and Tellurium-Doped Cadmium Sulfide Electrodes

摘要

An understanding of electrochemistry at semiconductor electrodes requires knowledge of the role intraband gap states play in mediating interfacial charge transfer. Reference to surface states is especially prevalent in the photoelectrochemical cell (PEC) literature. The existence of intraband gap states has been supported in part by electroluminescence (EL) studies: Electrolyte species capable of hole injection into the valence bands of n-type, semiconducting TiO2, SrTiO3, CdS, GaP, ZnO, and GaAs yielded luminescence at sub-band gap energies. Since the valence band edges of these materials are generally at very positive potentials, valence band hole injection requires a potent oxidizing species. Aqueous alkaline peroxydisulfate (OH(-)/S2O8(2-)) electrolyte has been the medium of choice for observing the effect.