Highly efficient white organic light-emitting diodes using two emitting materials for three primary colors (red, green, and blue)

Abstract

The authors have demonstrated highly efficient white organic light-emitting diodes (WOLEDs) by using two emissive materials as a dopant, 1,4-bis[2-(7-N-diphenyamino-2-(9,9-diethyl-9H-fluoren-2-yl)) vinyl] benzene (DAF-ph) and iridium(III) bis(5-acetyl-2-phenylpyridinato-N,C2′) acetylacetonate ((acppy)2Ir(acac)). It was found that the OLED fabricated in this study emitted a white color consisting of three primary colors (red, green, and blue). The luminance-voltage (L-V) characteristics of the WOLEDs showed the maximum luminance of 30500cd∕m2 at 14V and the maximum luminous efficiency of 38.0cd∕A, respectively. The CIEx,y coordinates of the WOLED also showed (x=0.33, y=0.40) at 10V.

Performance enhancement of white-electrophosphorescent devices incorporating a mixed-transition layer

“…A number of such materials has now been synthesized, including 4,7-diphenyl-1,10-phenanthroline ͑BPhen͒. 6 This compound has an electron mobility of 5 ϫ 10 −4 cm 2 / V s, similar to the hole mobility in N , NЈ-bis͑naphthalene-1-yl͒-N , NЈ-bis͑phenyl͒-benzidine ͑NPB͒ ͓͑3-6͒ ϫ 10 −4 cm 2 / V s͔. 7 A further approach is to exploit chemical doping.…”

Full phosphorescent white-light organic light-emitting diodes with improved color stability and efficiency by fine tuning primary emission contributions

“…[1][2][3][4][5][6][7][8][9][10][11] Among them, white-light phosphorescent organic light emitting diodes (PhOLEDs) are very promising owing to their higher efficiency than white-light fluorescent OLEDs. 1,4,[9][10][11] Considerable progresses were made in high efficient white-light PhOLED in the last decades, with a great number of color stable white-light PhOLEDs reported. 12,13 However, it is still difficult to obtain both a very stable color and a high efficiency in the same single white PhOLED.…”

“…Complementary color emission scheme in white-light PhOLEDs is a typical example, which has been widely studied due to its simple device structure. 1,4,7,9,10,20 Most reports showed a noticeable color change in their white-light PhOLEDs when driving voltage increased. Only a few reported improvements of both color stability and efficiency, for example, Lee JY et al They attributed the improved performances to charge confinement inside the emitting layer.…”

Cathode Interface Investigation In Polymer/Fullerene Based Organic Solar Cells

“…It is known that some other similar cathodes, such as Liq/Al, Bphen/LiF/Al, Bphen/Liq/Al are widely served in organic light emitting diodes (OLEDs). [9][10][11][12] It is believed that alkali or alkaline-earth cations, chemically reduced via the reaction between Al and the alkali or alkalineearth metal compound, can dope the adjacent electron transporting layer to form complexes leading to improved electron injection from the cathode into the electron transporting layer. Generally speaking, the organic alkali or alkaline-earth metal complex/Al cathode, such as Liq/Al, has better thickness tolerance and lower evaporation temperature compared to the inorganic alkali or alkaline-earth metal compound/Al, such as LiF/Al.…”