Organic light-emitting devices performance

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J. Lee, Y. Park, S.K. Lee, E.J. Cho, D.Y. Kim, H.Y. Chu, H. Lee, L.M. Do, and T. Zyung, Tris-(8-hydroxyquinoline)aluminum-based organic light-emitting devices with Al/CaF2 cathode performance enhancement and interface electronic structures, Appl. Phys. Lett., 80 3123-3125 (2002). 

The enormous progress in the field of electroluminescent conjugated polymers has led to performances of organic light-emitting devices (LEDs) that are comparable and in some aspects superior to their inorganic counterparts [1], Quantum efficiencies in excess of 5% have been demonstrated [2] and show that a high fraction of the injected carriers in a polymeric electroluminescence (EL) device form electronic excitations which recombine radiatively. 

A promising way to improve the performance of organic light emitting devices (OLEDs) is to match suitable electron transporting (ET) and hole transporting (HT) layers in a heterolayer device in order to optimise the recombination in the emissive material [1]. 

S. Tokito, K. Noda, K. Shimada, S. Inoue, M. Kimura, Y. Sawaki, and Y. Taga, Influence of hole transporting material on device performance in organic light-emitting diode, Thin Solid... 

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The development and manufacture of organic light-emitting diodes (OLEDs) have demanded the use of the most advanced microstructural characterization techniques and sophisticated performance measurement devices [1-14], In this chapter, we will briefly describe these techniques and devices and review how scientists and engineers utilize them to improve the performance of OLEDs. 

One of the most common uses for peri-substituted pentacene is as a red emitter in organic light-emitting diodes (OLEDs). Diphenylpentacene, for example, has a fluorescence quantum yield of 30% as a 0.55% dopant in Alq3, yielding OLED devices with efficiencies near the theoretical maximum [34]. Variation of the aryl substituents improves solubility and processing and can increase fluorescence quantum yield (for example, pentacene 25 has a composite fluorescence quantum yield of 32%) [35]. There is one report of the use of diaryl pentacenes in FET devices, but the performance was generally poor (hole mobility for vapor-deposited 23 was of the order of 10-8 cm2 V-1 s-1) [30]. 

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