Adjusting White OLEDs with Yellow Light Emission Phosphor Dye and Ultrathin NPB Layer Structure

Jun Wang,Weizhi Li

doi:10.1155/2013/639843

Abstract

High efficiency white organic light emission devices were demonstrated with phosphor material dye bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2′]iridium (acetylacetonate) and ultrathin layer structure. The ultra thin layer be composed of 4,4′-bis[N-1-naphthyl-N-phenyl-amino]biphenyl (NPB) or 4,4′-N,N′-dicarbazole-biphenyl : NPB mixed layer with blue light emission. The emission spectra of devices could be adjusted by different phosphor doping concentrations and ultra thin layer structure. Warm white light emitting device could be obtained with 5 wt% doping concentration and power efficiency of 9.93 lm/W at 5 V. Pure white light with Commission Internationale de l'Eclairage (CIE) coordinates of (0.33, 0.30) and external quantum efficiency of 4.49% could be achieved with ultra thin layer device structure and 3 wt% phosphor doped device.

Highlights

Organic light-emitting diodes (OLEDs) represent a promising technology for large, flexible, flat-panel displays, and solid state lighting [1,2,3]
Efficient white OLEDs were reported by Reineke et al and Cheng et al with three doped layers in the whole devices structure [6, 7], and some organic devices with white light emission included two doped layers [8, 9]
We demonstrated a white OLEDs (WOLEDs) using a low ionization potential phosphorescent material bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2󸀠]iridium

Summary

Introduction

Organic light-emitting diodes (OLEDs) represent a promising technology for large, flexible, flat-panel displays, and solid state lighting [1,2,3]. Efficient white OLEDs were reported by Reineke et al and Cheng et al with three doped layers in the whole devices structure [6, 7], and some organic devices with white light emission included two doped layers [8, 9]. High efficiency white phosphorescent organic device doped with greenish-blue and red-emitting dye with a power efficiency of 10 lm/W at a current density of 0.01 mA/cm and CIE coordinates of (0.35, 0.36) has been achieved [16]. Ultrathin mixed fluorescent layer with blue light emission emitter was seldom reported as emitter in WOLEDs. In this work, we demonstrated a WOLEDs using a low ionization potential phosphorescent material bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2󸀠]iridium (acetylactonate). High efficiency WOLEDs with blue and yellow lights combined could be obtained with this ultrathin layer structure

Device Fabrication

Experiment Results

Conclusion