Color Variation Improvement by Introducing Double Emission Layers in WPLEDs

Abstract

We have fabricated white polymeric light-emitting devices (WPLEDs) from polyfluorene-based (PFO) blue and MEH-PPV polymer blending systems. A device structure of ITO/PEDOT:PSS/Blending polymer/Blue polymer/LiF/Al was employed. This double emissive structure results in the significant improvement of white color shift phenomenon. A current efficiency of 4.67 cd/A (3,900 cd/m², 6.4 V) and a brightness value of 17,600 cd/m² at 9.4 V with (0.34, 0.35) CIE coordinates at 5 V and (0.29, 0.29) at 9 V were obtained.

Keywords:

• color variation
• double emission structure
• light-emitting devices
• MEH-PPV

Acknowledgments

This research was supported by the Kyung Hee University Research Fund in 2005. (KHU-20051036) The authors gratefully acknowledge SK Corporation. They supplied SKB (Blue emissive material) for this research.