Stable green phosphorescence organic light-emitting diodes with low efficiency roll-off using a novel bipolar thermally activated delayed fluorescence material as host

Kunping Guo; Hedan Wang; Zixing Wang; Changfeng Si; Cuiyun Peng; Guo Chen; Jianhua Zhang; Gaofeng Wang; Bin Wei

doi:10.1039/c6sc03008d

Stable green phosphorescence organic light-emitting diodes with low efficiency roll-off using a novel bipolar thermally activated delayed fluorescence material as host

Chem Sci. 2017 Feb 1;8(2):1259-1268. doi: 10.1039/c6sc03008d. Epub 2016 Oct 4.

Authors

Kunping Guo^{1

2}, Hedan Wang^{2

3}, Zixing Wang², Changfeng Si², Cuiyun Peng¹, Guo Chen², Jianhua Zhang², Gaofeng Wang⁴, Bin Wei^{1

2}

Affiliations

¹ School of Mechatronic Engineering and Automation , Shanghai University , 149 Yanchang Road , Shanghai , 200072 , P. R. China . Email: bwei@shu.edu.cn.
² Key Laboratory of Advanced Display and System Applications , Ministry of Education , Shanghai University , 149 Yanchang Road , Shanghai , 200072 , P. R. China . Email: zxwang78@shu.edu.cn.
³ Department of Chemistry , Shanghai University , 99 Shangda Road , Shanghai , 200444 , P. R. China.
⁴ Ningbo Intime Technology Co. Ltd , No. 23, Ruhu West Road, Simen Town , Yuyao City , Zhejiang Province 345403 , P. R. China.

Abstract

A novel bipolar hosting material, 11-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-12,12-dimethyl-11,12-dihydroindeno[2,1-a]carbazole (DPDDC), was designed, synthesized, and characterized for green phosphorescent organic light-emitting diodes (PhOLEDs). The DPDDC exhibits excellent hole and electron transport properties, superior thermal stability, a high glass-transition temperature and a small singlet-triplet energy gap for efficient reverse intersystem crossing from triplet to singlet, reducing the triplet density of the host for PhOLEDs. The electrophosphorescence properties of the devices using DPDDC as the host and three green phosphorescent iridium(iii) complexes, bis(2-(4-tolyl)pyridinato-N,C2')iridium(iii) acetylacetonate, bis(2-phenylpyridine)iridium(iii) acetylacetonate, and bis(4-methyl-2,5-diphenylpyridine)iridium(iii) acetylacetonate [(mdppy)₂Iracac] as the emitter were investigated. The green PhOLED with 5 wt% (mdppy)₂Iracac presents an excellent performance, including a high power efficiency of 92.3 lm W^-1, high external quantum efficiency of 23.6%, current efficiency roll-off as low as 5.5% at 5000 cd m^-2 and a twentyfold lifetime improvement (time to 90% of the 5000 cd m^-2 initial luminance) over the reference electrophosphorescent device.