Polymer light-emitting diodes efficiency

Y Yang, Q Pei, and AJ Heeger, Efficient blue polymer light-emitting diodes from a series of soluble poly(paraphenylene)s, J. Appl. Phys., 79 934—939, 1996. 

C Zhang, S Hoger, K Pakbaz, F Wudl, and AJ Heeger, Improved efficiency in green polymer light-emitting diodes with air-stable electrodes, J. Electron. Mater., 23 453 458, 1994. 

Y Cao, G Yu, and AJ Heeger, Efficient, low operating voltage polymer light-emitting diodes with aluminum as the cathode material, Adv. Mater., 10 917-920, 1998. 

Y Cao, Electrically Active Polymer Compositions and Their Use in Efficient, Low Operating Voltage, Polymer Light-Emitting Diodes with Air-Stable Cathodes, U.S. Patent 5,965,281, 1999. 

V. Blyznyuk, B. Ruhstaller, P.J. Brock, U. Scherf, and S.A. Carter, Self-assembled nanocomposite polymer light-emitting diodes with improved efficiency and luminance, Adv. Mater., 11 1257-1261, 1999. 

M.M. Alam, and S.A. Jenekhe, Polybenzobisazoles as efficient electron-transport materials for improving the performance and stability of polymer light-emitting diodes, Chem. Mater., 14 4775-4780, 2002. 

Y-H. Niu, J. Huang, and Y. Cao, High-efficiency polymer light-emitting diodes with stable saturated red emission use of carbazole-based copolymer blends in a poly(p-phenylene vinylene) derivative, Adv. Mater., 15 807-811, 2003. 

P. Herguth, X. Jiang, M.S. Liu, and A.K.-Y. Jen, Highly efficient fluorene and benzothiadiazole-based conjugated copolymers for polymer light-emitting diodes, Macromolecules, 35 6094-6100, 2002. 

Q. Xu, J. Quyang, Y. Yang, T. Ito, and J. Kido, Ultrahigh efficiency green polymer light emitting diodes by nanoscale interface modification, Appl. Phys. Lett., 83 4695-4697 (2003). 

P.K.H. Ho, M. Granstrom, R.H. Friend, and N.C. Greenham, Ultrathin self-assembled layers at the ITO interface to control charge injection and electroluminescence efficiency in polymer light-emitting diodes, Adv. Mater., 10 769-774, 1998. 

G.L. Frey, K.J. Reynolds, R.H. Friend, H. Cohen, and Y. Feldman, Solution-processed anodes from layer-structure materials for high efficiency polymer light-emitting diodes, Am. Chem. Soc., 125 5998-6007, 2003. 

Recent experiments [158] on polymer light emitting diodes using alkoxy derivatives of PPV as the semiconducting and luminescent material have demonstrated that the ratio of the EL quantum efficiency (ihel) to the PL quantum efficiency (t]pl) can be increased to t1el/ 9pl>0 5, well beyond the theoretical limit for singlet and triplet excitons as the low energy excited states. 

ZITO films with composition ZnIn2,oSni,502 have been prepared by CVD experiments employing [In(dpm)3], [Sn(acac)2], and [Zn(hfa)2(diamine)], (hfa = hexafluoroacetylacetonato). Such films were used in the fabrication of polymer light-emitting diodes, which exhibited light outputs and current efficiencies almost 70% greater than those of commercial Sn-doped indium oxide (ITO) films. ... 

Subsequently, Cao et al. [30,31] designed and synthesized polymer 20-22 by similar method and the highly efficient saturated red-phosphorescent polymer light-emitting diodes (PLEDs) were achieved on the basis of copolymer 20. The best device performances are observed with an external quantum efficiency of 6.5% photon/electron (ph/el) at the current density of 38 mA/cm2, with the emission peak at 630 nm (x = 0.65, y = 0.31) and the luminance of 926 cd/m2. 

Another way to introduce Ir(III) complexes into the main-chain of polyfluorenes was realized by Suzuki polycondensation of fluorene segments and /3-diketone ligand chelated with Ir(III) chloride-bridged dimmer (polymer 26 and 27) [34,35]. A saturated red-emitting polymer light-emitting diode was achieved from the device ITO/PEDOT/polymer 27 + PBD (40%)/Ba/Al with the maximum external quantum efficiency of 0.6% at the current density (J) of 38.5 mA/cm2 and the maximum luminance of 541 cd/m2 at 15.8 V. 

Gong X, Wang S, Moses D, Bazan G C and Heeger A J, Multilayer Polymer Light-Emitting Diodes White-Light Emission with High Efficiency Advanced Materials,, 17, 17,(September, 2005),2053-2058... 

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