Dielectric Changes of Electroluminescent Phosphor During Illumination*

Abstract

Phosphor powder was incorporated in a thin film of plasticized polyvinyl chloride. The dielectric constant and loss of the film was measured at 1000 cps under various intensities of illumination and at different applied voltages. White light from a tungsten lamp was used for some experiments, while others were done with monochromatic light of different wavelengths from a mercury arc.The results of these experiments show a very substantial variation of dielectric constant under illumination. Further, the magnitude of the change of dielectric constant depends critically on the value of the voltage applied during the tests. There is a maximum effect at about 4046A, while the sensitivity falls off noticeably at 3650A and 4358A.