A multi-zoned white organic light-emitting diode with high CRI and low color temperature.

Tao Zhang,Zheng-Hong Lu,Deng-Ke Wang,Shou-Jie He,Nan Jiang

doi:10.1038/srep20517

Tao Zhang, Zheng-Hong Lu + Show 3 more

Open Access

https://doi.org/10.1038/srep20517

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Journal: Scientific Reports	Publication Date: Feb 4, 2016
Citations: 29	License type: CC BY 4.0

Affiliation: Yunnan University, University of Toronto

Abstract

White organic light emitting diodes (WOLEDs) is becoming a new platform technology for a range of applications such as flat-panel displays, solid-state lightings etc., and are under intensive research. For general solid-state illumination applications, a WOLED’s color rendering index (CRI) and correlated color temperature (CCT) are two crucial parameters. This paper reports that WOLED device structures can be constructed using four stacked emission layers which independently emit lights at blue, green, yellow and red color respectively. The intensity of each emission layer is then engineered by funneling excitons to the targeted emission layer to achieve an ultrahigh 92 CRI at 5000 cd/m2, and to reduce CCT to below 2500 K.

Highlights

Organic light emitting diodes (OLEDs) have received a broad attention for their enormous applications in the field of flat-panel displays and solid-state lightings[1,2,3,4]
A four emission zone White organic light emitting diodes (WOLEDs) is demonstrated to be capable of achieving an ultrahigh color rendering index (CRI) > 92 at high 5000 cd/m2 luminance with an extremely low correlated color temperature (CCT) ~ 2500 K, while maintaining a high efficiency of ~25 lm/W without optical coupling
The turn-on voltage of the device with CBP layer thickness of 3 nm is almost the same as that of device without a spacer layer, the maximum current and power efficiencies of this device are 26.4 cd/A and 24.8 lm/W respectively without using any out-coupling enhancement techniques. This increase in device efficiency is attributed to a reduced exciton quenching as the spacer layer separates excitons in the blue fluorophore from other triplet emitters

Summary

Introduction

Organic light emitting diodes (OLEDs) have received a broad attention for their enormous applications in the field of flat-panel displays and solid-state lightings[1,2,3,4]. The optimized structure of the ultrahigh CRI white OLED is ITO/MoO3(1 nm)/CBP(20 nm)/CBP: Ir(piq)2(acac) (3 wt.%,4 nm)/CBP: Ir(DMP)3(5 wt.%,4 nm)/CBP: Ir(ppy)2(acac)(7 wt.%,5 nm)/CBP(x nm)/Bepp[2]: BCzVBi(50 wt.%,40 nm)/Bepp2(20 nm)/LiF(1 nm)/Al(100 nm).

Results

Conclusion