Luminescent photoelectrochemical cells. 6. Spatial aspects of the photoluminescence and electroluminescence of cadmium selenide electrodes

Abstract

Samples of single-crystal, n-type CdSe emit when excited with ultraband gap excitation. The emission band (Xmal =» 720 nm) is near the band gap of CdSe (~1 .7 eV); its energy, decay time, and temperature dependence are consistent with its description as edge emission. Photoluminescence (PL) spectra can be dependent on excitation wavelength and show evidence of self-absorption effects: PL spectra obtained with 457.9-nm excitation are broadened in the high-energy portion of the band relative to spectra obtained with more deeply penetrating 632.8-nm excitation. Measured PL efficiencies, , are ~10~4 in air at 295 K. When CdSe is used as the photoanode of photoelectrochemical cells employing aqueous polychalcogenide electrolytes, emission is quenched by the passage of photocurrent resulting from ultraband gap excitation. Electroluminescence (EL) can be observed from CdSe when the semiconductor is used as a dark cathode in aqueous, alkaline peroxydisulfate electrolyte.

Luminescent Properties of Semiconductor Electrodes.

“…Among semiconductor electrodes, n-CdSe has, like n-CdS, been the subject for the extensive use of n-CdSe in PEC's (52). The ability of n-CdS and n-CdSe to form solid solutions of n-CdSxSeI X (0<XOI) prompted us to examine PL properties of these solids as a family, using the *" stabilizing chalcogenide electrolytes for PEC construction (52)(53)(54).…”

“…The ability of n-CdS and n-CdSe to form solid solutions of n-CdSxSeI X (0<XOI) prompted us to examine PL properties of these solids as a family, using the *" stabilizing chalcogenide electrolytes for PEC construction (52)(53)(54).…”

“…13 In concluding this section we note that all of the single-crystal n-Cd;XSel.X samples examined exhibit quenching of their PL intensity when used as PEC electrodes, as illustrated in Fig. 14; the extent of quenching and corresponding properties related to optical energy conversion are summarized in We examined both n-CdS:Te- (46,47,75) and n-CdSxSelX-based PEC's (52,53) for agreement with eq. [7].…”

Photoluminescence and electroluminescence in graded cadmium sulfoselenide electrodes: Applications to photoelectrochemical cells

“…We recently reported on the PL properties of homogeneous CdS xSeI_ samples employed as photoelectrodes in such PECs (8,9). We found that the passage of photocurrent quenched the PL intensity of these samples but did not perturb the spectral distribution.…”

“…Emission due to a dopant was investigated with samples of Te-doped CdS (CdS:Te) (5-7), and edge emission was studied with members of the CdS xSe X (0 < X C 1) series (8,9). Our general finding was that photoluminescence (PL) could be perturbed and electroluminescence (EL) initiated in aqueous electrolytes by interfacial charge-transfer events.…”