An insulator MnO as an electron injecting and transporting material introduced into organic light-emitting diodes to increase electroluminescence efficiency also can eliminate the problem of the oxidation of reactive dopants to improve stability of devices. (C) 2008 Optical Society of America

Two phenothiazine-based polymers were synthesized by the Heck reaction of 3,7-divinyl-N-octylphenothiazine with 3,7-diiodo-N-octyl-phenothiazine and 5,8-dibromo-2,3-diethylquinoxaline. The polymers were characterized by the measurements of (1)H-NMR, IR, TG, GPC, CV, UV–Vis, and FL. The results indicated that the introduction of quinoxaline group makes the absorption, PL, and EL emission maxima red-shifted. The EL emission maximum and the CIE 1931 coordinate value are stabilized at a constant value with the increase in operating voltages. Therefore, the polymers have a stable electroluminescent emission property. Copyright (c) 2008 John Wiley & Sons, Ltd.

An electroluminescent polymer was synthesized by Wittig condensation and characterized by the measurements of H-1-NMR, IR, gel permeation chromatography (GPC), UV-Vis, PL, and cyclic voltammetry (CV). The polymer can be dissolved in common organic solvents such as tetrahydrofuran (THF), chloroform, and dichloromethane. The electroluminescent investigation showed that the non-doped devices with a double-layer configuration (ITO/PEDOT:PSS/Polymer/Mg:Ag) have a stable green emission property. The maximum luminance of the annealed device reaches 2317 cd/m(2). The emission maximum and the CIE 1931 coordinate values are respectively stabilized at 552 nm and near (x, y) =(0.43, 0.55) with different voltages. Copyright (C) 2008 John Wiley & Sons, Ltd.

The optical upconversion of infrared light to visible light has been achieved in photosensitizer-doped organic light-emitting diodes, where poly(N-vinylcarbazole) doped with infrared photosensitizer of 2,4,7-trinitro-9-fluorenylidene malonitrile was used as hole-transporting layer, and tris(8-hydroxyquinoline) aluminum acted as both emitting and electron-transporting layers. Both electroluminescent intensity and current were enhanced under infrared illumination. The enhancement ratio was obtained as 2.45 times for electroluminescent emission and 1.45 times for current. This work brought forth a prototype design for novel flexible organic optical upconversion device used in near infrared field. (c) 2007 American Institute of Physics.