Highly efficient top-emitting white organic light-emitting diodes with improved contrast and reduced angular dependence for active matrix displays

Highly efficient top-emitting white organic light-emitting diodes (TEWOLEDs) on silicon substrates based on complementary blue and yellow phosphors are demonstrated. The bottom copper anode with medium reflectance, which is compatible with standard complementary metal oxide semiconductor (CMOS) technology, and the semitransparent cathode with a top capping layer, are introduced to facilitate white light emission with improved contrast and reduced angular dependence. Both TEWOLEDs, with and without the capping layers, exhibit nearly lambertian-type emission. The spectrum of TEWOLED with a capping layer is similar to that of the bottom-emitting counterpart. Our TEWOLED reaches high efficiencies of 27.7 cd/A and 17.6 lm/W at a current density of 10 mA/cm(2), and low voltage of 4.4 V at 1000 cd/m(2). (C) 2010 Elsevier B. V. All rights reserved.