Journal of the Korean Physical Society

pISSN 0374-4884 eISSN 1976-8524

Article

Application and Devices

Published online September 15, 2006    

Copyright © The Korean Physical Society.

Determination of the Exciton Recombination Zone in White OLEDs Based on a Blue Emitting Layer of 4'4-Bis(2,2'-Diphenyl Vinyl)-1,1'-Biphenyl

So-Young Kim, Hye-Yeon Shim, Ji-Hyun Seo, Young-Kwan Kim and Jun-Ho Kim

J. Korean Phys. Soc. 49(3), 1247 (2006)

Abstract

We fabricated white organic light-emitting diodes (WOLEDs) with three emissive layers consisting of a phosphorescent and two fluorescent materials. The fabricated device structure was ITO / NPB(40 nm) / 1 \% Ir(ppy)$_3$:CBP(5 nm) / DPVBi(10 nm) /BCP (3 nm)/ 1 \% DCM1 : CBP(5 nm) / BCP(10 nm) / Alq$_3$(30 nm) / Liq(2 nm) / Al. In this device, the thin BCP between the DPVBi and the 2 \% DCM1 played the role of retarding the hole flow from the DPVBi layer to the 2 \% DCM1 : CBP layer, resulting in a white emission due to the strong blue emission of DPVBi. The device showed an improved white balance with Commission Internationale d'Eclairage (CIE) coordinates of (0.278, 0.371) and a reduced maximum luminance of 3,440 cd/m$^2$ while the device without the thin BCP layer showed CIE coordinates of (0.311, 0.417) and a maximum luminance of 4,510 cd/m$^2$.