Fluorescent White Organic Light-emitting Diodes Research Articles

Extremely low voltage and high bright p-i-n fluorescent white organic light-emitting diodes

Extremely low voltage white organic light-emitting devices (WOLEDs) with fluorescent emitters are realized exploiting p-i-n structure. White light is obtained by two complementary colors system, in which the yellow and the blue emitting components are based on 5,6,11, 12-tetraphenylnaphthacene (rubrene) and 4,4-bis-2, 2-diphenylvinyl-1, 1-spirobiphenyl (Spiro-DPVBi), respectively. The effects on the device performances of various electron blocking layers and hosts for rubrene are discussed. The best device shows a luminance of 1000cd∕m2 at bias of as low as 2.9V, and 10000cd∕m2 at 4.7V with a maximum power efficiency of 8.7lm∕W. The Commission Internationale de 1’Eclairage chromaticity coordinates change from (0.36, 0.45) at 1000cd∕m2 to (0.33, 0.42) at 10000cd∕m2 showing high color stability.

Efficient fluorescent white organic light-emitting diodes using co-host/emitter dual-role possessed di(triphenyl-amine)-1,4-divinyl-naphthalene

Efficient fluorescent white organic light-emitting diodes with low carrier-injection barriers were fabricated with device structure of indium tin oxide/ N,N′-bis-(1-naphthy)- N,N′-diphenyl-1,1′-biphenyl-4-4′-diamine/white emission layer/1,3,5-tris( N-phenyl-benzimidazol-2-yl)benzene/lithium fluoride/aluminium. By blending in the blue host of 1-butyl-9,10-naphthalene-anthracene in the emissive layer an efficient electro-luminescent greenish-blue co-host of di(triphenyl-amine)-1,4-divinyl-naphthalene, with the doping of a trace amount of red dye of 4-(dicyano-methylene)-2-methyl-6-(julolidin-4-yl-vinyl)-4 H-pyran, bright and colour-stable white emission with high power-efficiency of 14.6 lm/W at 100 cd/m 2 or current efficiency of 19.2 cd/A at 300 cd/m 2 or 18.7 cd/A at 10,000 cd/m 2 was obtained. The resulted synergistic increase in brightness and efficiency may be attributed to the presence of cascading new routes with comparatively lower electron injection barrier.

Efficient fluorescent white organic light-emitting diodes with blue-green host of di(4-fluorophenyl)amino-di(styryl)biphenyl

Efficient fluorescent white organic light-emitting diodes are fabricated with the use of an efficient electro-fluorescence blue-green host material di(4-fluorophenyl)amino-di(styryl)biphenyl, doped with red dye 4-(dicyano-methylene)-2-methyl-6-(julolidin-4-yl-vinyl)-4H-pyran. One resulting two-wavelength white emission device shows a maximum external quantum efficiency of 4.8% and a high power efficiency of 14.8 lm/W with 100 cd/m2 at 3.8 V. The high efficiency may be attributed to the high electroluminescence character of the host, relatively high host-to-guest energy transfer efficiency, and effective device architecture.

Efficient, color-stable fluorescent white organic light-emitting diodes with single emission layer by vapor deposition from solvent premixed deposition source

Efficient, color-stable fluorescent white organic light-emitting diodes (OLEDs) with single emission layer were fabricated by vapor deposition from solvent premixed mixtures of 1,4-bis(2,2-diphenylvinyl)biphenyl doped with 4-(dicyanomethylene)-2-methyl-6-(julolidin-4-yl-vinyl)-4H-pyran and/or 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-(1)benzopy-rano(6,7,8-l, j)quinolizine-11-one. The power efficiencies at 100 cd/m2 were 4.6 lm/W for the two-spectrum pure white OLEDs and 7.2 lm/W m2 for the three-spectrum ones with white emission. By using a different host of 10,10′-bis(biphenyl-4-yl)-9,9′-bianthryl and a greenish-blue dye of di(triphenylamine)-1,4-divinylnaphthalene, the three-spectrum OLEDs with a power efficiency of 6.8 lm/W at 100 cd/m2 were obtained.

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.