A white organic light emitting diode with improved stability

Abstract

A white organic light emitting diode (OLED) has been constructed by employing a new blue material and a red dye directly doped in the blue emitting layer. For comparison, another white cell with a blocking layer has also been made. The configurations of the devices are ITO/CuPc/NPB/JBEM(P):DCJT/Alq/MgAg (device 1) and ITO/CuPc/NPB/TPBi:DCJT/Alq/MgAg (device 2) where copper phthalocyanine (CuPc) is the buffer layer, N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1.1'bipheny1-4-4'-diamine (NPB) is the hole transporting layer, 9,10-bis(3'5'-diaryl)phenyl anthracene doped with perylene (JBEM(P)) is the new blue emitting material, N,arylbenzimidazoles (TPBi) is the hole blocking layer, tris(8-quinolinolato)aluminium complex (Alq) is the electron transporting layer, and DCJT is a red dye. A stable and current independent white OLED has been obtained in device 1, which has a maximum luminance of 14 850 cd m-2, an efficiency of 2.88 Lm W-1, Commission Internationale de l'Eclairage coordinates of x = 0.32, y = 0.38 between 4-200 mA cm-2, and a half lifetime of 2860 h at the starting luminance of 100 cd m-2. Device 1 has a stability more than 50 times better than that of device 2.

White organic light-emitting diodes based on improved polyfluorene derivative

“…Up to now, the white emissions are obtained by mixing three basic-color-lights from different emitting molecules. The conformations of white OLEDs usually can be divided into two kinds, one is the EL devices based on the blend of three basic-color-emitting materials as emitting layer [8][9][10][11][12][13][14] and another is the multi-layer EL devices consisting of three basic-color emitting layers [15][16][17][18][19]. For both of the two kinds, it is required that the red fluorescent dye is dispersed and isolated in host materials to avoid concentration quenching [20].…”

Fabrication of White Organic Light-Emitting Diodes Using Two Complementary Color Methods

“…White-emission methods can be divided into two types. One is the 3-wavelength type [13] that mixes the existing RGB and the other is the 2-wavelength type that mixes blue and either orange or red [14][15][16]. The 2-wavelength type has emerged in order to make up for some drawbacks in the 3-wavelength type, but a substitute for the 2-wavelength method is urgently needed because it still uses the same blue-emitting material in the 3-wavelength method.…”

White light emission on amplified spontaneous emission with dye content controlled polymer system

“…[10][11][12] Among these methods, blending different color dyes or emissive molecules into host organic molecules provides an effective approach to achieve white light emission. [10][11][12] Among these methods, blending different color dyes or emissive molecules into host organic molecules provides an effective approach to achieve white light emission.…”