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, C2′)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/m2 and the value can be maintained as high as 20.1 cd/A at 9, 300 cd/m2. Furthermore, the Commission Internationale de LʹEclairage coordinate of the corresponding device only changes marginally from (0.41, 0.46) to (0.40, 0.46) over 103–104 cd/m2.