ENHANCEMENT OF THE ELECTROLUMINESCENT PHOSPHOR BRIGHTNESS AND STABILITY

摘要

To improve characteristics of the modern electroluminescent devices it is necessary to use phosphors of smaller grain size, higher brightness and stability as well as better color properties. In the work phosphor particle size was decreased by optimization of the fabrication conditions. Further reduction of the particles size was achieved by the developed fractionation technique based on gravitational sedimentation in the viscous media. Study of the effects of the activator and co-activators on the phosphor's properties allowed us to control phosphor's color properties in a wide range and to improve EL efficiency. Another improvement of the phosphor brightness was achieved by the electron-beam treatment of the charge flux before the sintering step. We assumed that such kind of treatment is likely to provide more even distribution of the activator ions in the phosphor matrix. To examine surface donor-acceptor properties of the phosphors novel technique was used, viz. measurement of distributions of active surface centers (DAC). This method was shown to enable one to obtain data related to the chemical composition of surface, to detect structural defects and basing on that information to predict phosphor's performance.