Luminescent transport layers

Electron-Deficient Polymers — Luminescent Transport Layers... 

Electron-Deficient Polymers - Luminescent Transport Layers 16 Other Electron-Deficient PPV Derivatives 19 Electron-Deficient Aromatic Systems 19 Full Color Displays - The Search for Blue Emitters 21 Isolated Chromophores - Towards Blue Emission 21 Comb Polymers with Chromophores on the Side-Chain 22 Chiral PPV - Polarized Emission 23 Poly(thienylene vinylene)s —... 

The /3-diketonate [Nd(dbm)3bath] (see figs. 41 and 117) has a photoluminescence quantum efficiency of 0.33% in dmso-7r, solution at a 1 mM concentration. It has been introduced as the active 20-nm thick layer into an OLED having an ITO electrode with a sheet resistance of 40 il cm-2, TPD as hole transporting layer with a thickness of 40 nm, and bathocuproine (BCP) (40 nm) as the electron injection and transporting layer (see fig. 117). The electroluminescence spectrum is identical to the photoluminescence emission the luminescence intensity at 1.07 pm versus current density curve deviates from linearity from approximately 10 mA cm-2 on, due to triplet-triplet annihilation. Near-IR electroluminescent efficiency <2el has been determined by comparison with [Eu(dbm)3bath] for which the total photoluminescence quantum yield in dmso-tig at a concentration of 1 mM is Dpi, = 6% upon ligand excitation, while its external electroluminescence efficiency is 0.14% (3.2 cdm-2 at 1 mAcm-2) ... 

TAZ) shown in Figure 11.5, is often added between the layer of luminescent material and the electron-transport layer or the metallic electrode, to balance the charge injection and transport rates. Then the recombination of electrons and holes is confined to the emitting layer and consequently a high electroluminescent efficiency can be obtained. Some hole-injection materials are shown in Figure 11.6. 

In 1990, Kido etal. [16] first reported the europium complex tris(thienyltrifluoro-acetonato) europium [Eu(TTA)3], based OLED in which the complex was molecularly dispersed in holetransporting poly(methylphenylsilane) (PMPS). Luminescence started at 12 V, and a maximum intensity of 0.3cdm at 18 V was achieved when the device was operated in continuous DC mode (biased ITO positive) with the configuration ITO/PMPS-Eu(TTA)3/PBD/Mg/Ag [PBD = 2-(4-biphenyl)-5-(4-tert-butylphenyl)-l,3,4-oxadiazole, the structure shown in Eigure 11.4, being used as the electron-transporting layer]. Since then, many Eu(III) complexes and related electroluminescent devices have been studied extensively. 

Table 3.15 Chemical Structures of Compounds Used in Carrier Transport Layers and Luminescent Layers of Organic Electroluminescent Devices...

Other requirements are placed on electroluminescent devices in addition to supporting efficient hole and electron transport (1) the exciton energy in the transport layer has to be higher than the exciton energy in the luminescent layer (2) the formation of molecular complexes between the fluorescent layers should be precluded (3) the luminescent layer has to possess a high fluorescence quantum yield and (4) the film should be processed readily. 

Tanase, C., Wildeman, J., and Blom, R W. M. 2005. Luminescent poly-(p-phenylenevinylene) hole transport layers with adjustable solubility. Adv. Fund. Mater. 15 2011-2015. 

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