M‐Indolocarbazole Derivative as a Universal Host Material for RGB and White Phosphorescent OLEDs. (6th August 2015)

• Record Type: Journal Article
• Authors: Lai, Cheng‐Chang; Huang, Min‐Jie; Chou, Ho‐Hsiu; Liao, Chuang‐Yi; Rajamalli, Pachaiyappan; Cheng, Chien‐Hong
• Is Part Of: Advanced functional materials. Volume 25:Number 34(2015)
• Page Start: 5548
• Page End: 5556
• Publication Date: 2015-08-06
• Subjects: bipolar -- indolocarbazole -- low roll‐off -- universal host -- white organic light‐emitting diode; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201502079
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract : The host materials designed for highly efficient white phosphorescent organic light‐emitting diodes (PhOLEDs) with power efficiency (PE) >50 lm W ‐1 and low efficiency roll‐off are very rare. In this work, three new indolocarbazole‐based materials (ICDP, 4ICPPy, and 4ICDPy) are presented composed of 6, 7‐dimethylindolo[3, 2‐ a ]carbazole and phenyl or 4‐pyridyl group for hosting blue, green, and red phosphors. Among this three host materials, 4ICDPy‐based devices reveal the best electroluminescent performance with maximum external quantum efficiencies (EQEs) of 22.1%, 27.0%, and 25.3% for blue (FIrpic), green ( fac ‐Ir(ppy)3 ), and red ((piq)2 Ir(acac)) PhOLEDs. A two‐color and single‐emitting‐layer white organic light‐emitting diode hosted by 4ICDPy with FIrpic and Ir(pq)3 as dopants achieves high EQE of 20.3% and PE of 50.9 lm W −1 with good color stability; this performance is among the best for a single‐emitting‐layer white PhOLEDs. All 4ICDPy‐based devices show low efficiency roll‐off probably due to the excellent balanced carrier transport arisen from the bipolar character of 4ICDPy. Abstract : Three new indolocarbazole‐based host materials, ICDP, 4ICPPy, and 4ICDPy, are synthesized and used as hosts for various color phosphorescent organic light‐­emitting diodes. The blue, green, and red devices using 4ICDPy as the host all exhibit very high device efficiencies. In addition, a two‐color white device shows an external quantum efficiency of 20.3% and power efficiency of 50.9 lm W −1 with excellent color stability.