Color stable white polymer light-emitting diodes with single emission layer

Abstract

We report color stable white polymer light-emitting diodes achieved with single emission layers. The emitting layers are blending films of blue-, green- and red-emitting polymers based on color-stabilized backbones of poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene)) (PCPP) and poly(5,5,10,10-tetrakis(2-ethylhexyl)-5,10-dihydroindeno[2,1-a]indene-2,7-diyl) (PININE). The white emission is realized with a combination of energy transfer and charge carrier trapping between the polymers in the devices. The devices exhibit a high color quality of white light with CIE coordinates of (0.31, 0.32) and excellent color stability as the driving voltage increases. (C) 2009 Elsevier B.V. All rights reserved.