Simple and high efficiency green phosphorescent devices using an intermixed double host of 4, 4', 4"-tris(N-carbazolyl) triphenylamine [TCTA], 1, 3, 5-tris (N-phenylbenzimiazole-2-yl) benzene [TPBI], phosphorescent dye of tris(2-phenylpyridine)iridium(III) [Ir(ppy)3], and selective doping in the TPBI region were fabricated, and their electro luminescent characteristics were evaluated. In the device fabrication, layers of 70Å-TCTA/90Å-TCTA[0.5TPBI0.5/90Å-TPBI doped with Ir(ppy)3 of 8% and an undoped layer of 50Å-TPBI were successively deposited to form an emission region, and SFC137 [proprietary electron transporting material] with three different thicknesses of 300Å, 500Å, and 700Å were used as an electron transport layer. The device with 500Å-SFC137 showed the luminance of 48,300 cd/m2 at an applied voltage of 10 V, and a maximum current efficiency of 57 cd/A under a luminance of 230 cd/m2. The peak wavelength in the electroluminescent spectral and color coordinates on the Commission Internationale de I'Eclairage [CIE] chart were 512 nm and (0.31, 0.62), respectively.

In this study, the basic research verifying possibility of applications as radiology image sensor in Digital Radiography was performed, the radiology image sensor was fabricated using double layer technique tio decrease dark current. High efficiency material in substitution for a-Se have been studied as a direct method of imaging detector in Digital Radiography to decrease dark current by using Hetero junction already used as solar cell, semiconductor. Particle-In-Binder method is used to fabricate radiology image sensor because it has a lot of advantages such as fabrication convenient, high yield, suitability for large area sensor. But high leakage current is one of main problem in PIB method. To make up for the weak points, double layer technique is used, and it is considered that high efficient digital radiation sensor can be fabricated with easy and convenient process. In this study, electrical properties such as leakage current, sensitivity is measured to evaluate double layer radiation sensor material.