Zinc Selenide Photoelectrodes. Efficient Radiative Recombination in a Stable Photoelectrochemical Cell

摘要

Photoluminescence (PL) and electroluminescence (EL) from single-crystal, n-type, A1-doped ZnSe (ZnSe:A1) electrodes have been studied. These samples exhibit both edge emission (lambda(max) approx. 460 nm) and subband gap emission when excited at several ultraband gap wavelengths. The latter PL band is particularly intense, with a measured radiative quantum yield of approx. 0.1 to 0.01; the transition seems at least partially self-activated (SA) in origin, based on previously reported PL data. Excited-state communication involving the two emissive states is inferred from time-resolved PL measurements. Stable photoelectrochemical cells (PEC's) can be constructed from n-ZnSe:A1 electrodes and aqueous diselenide or ditelluride electrolytes. Applied potential quenches both of the photoanodes' PL bands roughly in parallel. The extent of PL quenching is consistent with a dead-layer model previously used to describe quenching in Au-ZnSe Schottky diodes. When used as a dark cathode in aqueous, alkaline peroxydisulfate eletrolyte, EL from ZnSe:A1 electrodes is observed.