Hybrid white organic light-emitting diodes with improved color stability and negligible efficiency roll-off based on blue fluorescence and yellow phosphorescence

We report hybrid white organic light-emitting diodes (WOLEDs) based on yellow phosphorescence of Iridium (III) bis(4-phenylthieno[3, 2-c]pyridinato-N, C-2')acetylacetonate (PO-01) and blue fluorescence of p-bis (p-N,N-diphenyl-amino-styryl) benzene (DSA-Ph). By introducing appropriate thickness of tris (phenylpyrazole) Iridium [Ir(ppz)(3)] as interlayer between the adjacent emission layers, taking advantage of the assistance electron-transporting behavior of guest molecules, efficient WOLEDs with negligible efficiency roll-off and high color stability are obtained. The best device shows a peak current efficiency of 21.0 cd/A at 2,300 cd/m(2) and the value can be maintained as high as 20.1 cd/A at 9,300 cd/m(2). Furthermore, the Commission Internationale de L'Eclairage coordinate of the corresponding device only changes marginally from (0.41, 0.46) to (0.40, 0.46) over 10(3)-10(4) cd/m(2). (C) 2012 Elsevier B.V. All rights reserved.