We investigated the suitability of aromatic amine-containing polymers as active layers in organic electroluminescent devices. Polymers used in this study include poly(N-vinylcarbazole) (PVK), poly(N-substituted methacrylamide)s, poly(methacrylate) and poly(arylene ether)s. The device structures are a double-layer-type and a single-layer type. The double-layer-type devices consist of a polymer hole transport layer and an electron-transporting emitter layer. High luminance of over 14,000 cd/m 2 was observed for some double-layer devices using the polymer hole transport layer. Single-layer devices with dye-dispersed PVK emitted white light with a luminance of over 4000 cd/m 2 . This demonstrates that dye-dispersed polymer systems are quite useful to obtain white light.Organic electroluminescent (EL) devices are the subject of study by many researchers because of their potential application as light-emitting devices which operate at low drive voltages. These devices are injection-type, in which carriers, such as electrons (radical anions) and holes (radical cations), are injected into the organic emitter layer where they recombine. It is, therefore, necessary for the component organic materials to possess carrier-transporting properties as well as fluorescence properties.Although electroluminescence in organic molecules have been known since the 1960's (7), a major breakthrough was made in the 80's by Tang and VanSlyke who developed a device exhibiting practical brightness (2). Their device consisted of a double layer structure with an organic hole transport layer and a luminescent metal complex layer. The hole transport layer plays an important role in transporting holes and blocking electrons, thus preventing electrons from moving into the electrode without recombining with holes. Aromatic diamine derivatives, such as yV^V-diphenyl-,^V-bis(3-methylphenyl)-l,r-biphenyl-4,4'-diamine (TPD), have been widely used as a hole transport layer because of their high hole mobilities (10" 3 cm 2 /Vs) and good
A poly(arylene ether) containing hole-transporting tetraphenylbenzidine units and electron-transporting 1,3,4-oxadiazole units was synthesized and examined as an emitter layer in organic electroluminescent device. The device structure of glass substrate / indium-tin oxide / polymer / Mg:Ag was employed. The EL device exhibited blue green light originating from the polymer emitter layer with a maximum luminance of 26 cd/m2 at 12 volt.
Electroluminescent devices were fabricated using a holetransporting polymer, hole transport layer and the emitter layer, respectively. A device structure of glass substratelindium-tin-oxide/ PTPDMAIAlqIMg : Ag was employed. Hole injection from the electrode through the PTPDMA layer to the Alq layer and concomitant electroluminescence from the Alq layer were observed. Bright green luminescence with a luminance of 20,000 cd/m' was obtained at a drive voltage of 14 V .
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