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

Abstract

Photoluminescence (PL) and electroluminescence (EL) from single-crystal, n-type, Al-doped ZnSe (ZnSe:Al) electrodes have been studied. These samples exhibit both edge emission (λmax ~ 460 nm) and subbandgap emission when excited at several ultrabandgap wavelengths. The latter PL band is particularly intense, with a measured radiative quantum yield of ~ 10−1 to 10−2; the transition appears to be 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:Al 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 electrolyte, EL from ZnSe:Al electrodes is observed. PL and EL spectral distributions are similar and indicate that the same emissive excited states are populated in the two experiments. Measured EL efficiencies, ~10−4 to 10−6 at −2.2 and −1.8V vs. SCE, respectively, are much smaller than PL efficiencies. Possible sources of the discrepancies are discussed.

Document Type

Article

DOI

https://doi.org/10.1149/1.2115751

Keywords

istry, photoelectrochem-, zinc selenide luminescence

Publication Date

1-1-1984

Journal Title

Journal of the Electrochemical Society

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