Efficient, color-stable fluorescent white organic light-emitting diodes with an effective exciton-confining device architecture

Abstract

Efficient, chromaticity-stable fluorescent white, including pure white, organic light-emitting diodes are fabricated by having an effective exciton-confining device architecture with a single emission layer via vapor-deposition of the solution-mixed targets of a blue light-emitting host doped with a trace amount of a red and/or a green dye. The used host is 1-butyl-9,10-naphthalene-anthracene. The red and green light-emitting dyes are 4-(dicyanomethylene)-2-methyl-6-(julolidin-4-yl-vinyl)-4H-pyran, and 2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-10-(2-benzothiazolyl) quinolizino[9,9a,1gh]coumarin, respectively. The employed electron-blocking effective hole-transporting material is N,N′-bis-(1-naphthy)-N,N′ diphenyl-1,1′-biphenyl-4-4′-diamine, and the hole-blocking effective electron-transporting material is 2-2′-2″-(1,3,5-benzinetriyl) tris(1-phenyl-1-H-benzimidazole). The best power efficiency of the resulting two-spectrum fluorescent devices is 7.5 lm/W (10.8 cd/A) at 11 cd/m2 with Commission Internationale de l'Eclairage coordinates of (0.423, 0.426), or 6.5 lm/W (9.6 cd/A) at 12 cd/m2with pure white light with coordinates of (0.346, 0.343). The best power efficiency of the three-spectrum counterparts is 6.7 lm/W (9.9 cd/A) at 15 cd/m2 with a nearly pure white light with coordinates of (0.325, 0.374). All color variations are less than (0.007, 0.006) between 100 cd/m2 to 10,000 cd/m2. © 2005 Elsevier B.V. All rights reserved.