GREEN AND RED ELECTROLUMINESCENCE FROM CDS POWDER ELECTRODES IN AQUEOUS-SOLUTIONS

The room temperature electroluminescence properties of CdS powder (pol ycrystalline) electrodes have been investigated in aqueous solutions u nder various experimental conditions. Red emission is observed from al l the CdS electrodes annealed at 400-600 degrees C, whereas green emis sion, which has previously been observed only from single crystal CdS electrodes, is also observed from the powder electrodes annealed at 60 0 degrees C. Both the red and the green emission intensities increase with an increase in the applied (negative) potential up to a critical value (-1.6 V vs Ag/AgCl); above this value there is a decrease in the intensity. The increase in the green emission is much stronger than t he increase in the red emission at higher applied potentials. The effe cts of several electrolytes (Na2S2O8 and NaOH) on the electroluminesce nt properties of CdS powder electrodes have also been studied. (C) 199 8 Elsevier Science B.V.