Zinc Selenide Photoelectrodes. Efficient Radiative Recombination in a Stable Photoelectrochemical Cell.
WISCONSIN UNIV-MADISON DEPT OF CHEMISTRY
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Photoluminescence PL and electroluminescence EL from single-crystal, n-type, A1-doped ZnSe ZnSeA1 electrodes have been studied. These samples exhibit both edge emission lambdamax 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 PECs can be constructed from n-ZnSeA1 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 ZnSeA1 electrodes is observed.
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