Photoluminescence and Electroluminescence as Probes of Interfacial Charge-Transfer Processes Relevant to Cadmium Sulfo-Selenide-Based Photoelectrochemical Cells.
Abstract
Samples of single-crystal, n-type Cd(X)Se(1-X) (where X is = to 1.000, 0.74, 0.49, 0.26, 0.11, 0.00) emit when excited with ultraband gap excitation. The 295 K band gaps monotoniclly decrease with X from approx. 2.4 eV for CdS to approx. 1.7 eV for CdSe. Photoluminescence (PL) spectra are sharp and have band positions which vary nearly linearly with composition: lumbda(max) (nm) approximately equal to 718-210 X. The energetic proximity to the band gap, temperature dependence and decay times are all consistent with a description of the PL as edge emission. Measured PL efficiencies, phi(r), are approx. 0.0004 in air. When the samples are used as photoanodes in photo-electrochemical cells (PECs) employing aqueous polysulfide electrolyte, the emission of intensity can be quenched by the passage of photocurrent. The extent of quenching can be correlated with the photocurrent quantum efficiency. Electroluminescence (EL) can be initiated by using the CdS(X)Se(1-X) samples as dark cathodes in aqueous, alkaline, peroxydisulfate electrolyte at potentials cathodic of approx.-0.9 to -1.1V vs. SCE. The EL spectral distribution for a given sample is similar to that observed in PL experiments and indicates that the same emissive excited state is involved. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 23, 1982
- Accession Number
- ADA120173
Entities
People
- Arthur B. Ellis
- Holger H. Streckert
- Jiu-ru Tong
- Michael K. Carpenter