New type of thin-film electroluminescent device having a multilayer structure

Abstract

A new kind of multilayered thin-film electroluminescent (EL) device is proposed. The device consists of multiple alternate layers in which the functions of carrier acceleration and light emission are separated. One big advantage of the proposed structure is that the light emitting phosphor can be selected independently of the carrier accelerating material, thus permitting a variety of color emissions. Therefore, one can optimize the device performance by selecting combinations of materials and cell structure design parameters. For example, a device employing ZnS and Y2O3:Eu thin films as the carrier accelerator and light emitter, respectively, emits a red color, and a brightness level of 40-ft lambert has been obtained under sinusoidal voltage excitation of 5 kHz. This value is several times higher than that reported for EL in powdered layers of Y2O3:Eu.