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ACS Appl Mater Interfaces. 2018 Feb 14;10(6):5714-5722. doi: 10.1021/acsami.7b18202. Epub 2018 Feb 5.

[1,2,4]Triazolo[1,5-a]pyridine as Building Blocks for Universal Host Materials for High-Performance Red, Green, Blue and White Phosphorescent Organic Light-Emitting Devices.

Author information

1
School of Chemistry and Chemical Engineering, Queen's University , Belfast BT7 1NN, U.K.
2
Shanghai Taoe Chemical Technology Co., Ltd , Shanghai 200030, PR China.

Abstract

The electron-accepting [1,2,4]triazolo[1,5-a]pyridine (TP) moiety was introduced to build bipolar host materials for the first time, and two host materials based on this TP acceptor and carbazole donor, namely, 9,9'-(2-([1,2,4]triazolo[1,5-a]pyridin-2-yl)-1,3-phenylene)bis(9H-carbazole) (o-CzTP) and 9,9'-(5-([1,2,4]triazolo[1,5-a]pyridin-2-yl)-1,3-phenylene)bis(9H-carbazole) (m-CzTP), were designed and synthesized. These two TP-based host materials possess a high triplet energy (>2.9 eV) and appropriate highest occupied molecular orbital/lowest unoccupied molecular orbital levels as well as the bipolar transporting feature, which permits their applicability as universal host materials in multicolor phosphorescent organic light-emitting devices (PhOLEDs). Blue, green, and red PhOLEDs based on o-CzTP and m-CzTP with the same device configuration all show high efficiencies and low efficiency roll-off. The devices hosted by o-CzTP exhibit maximum external quantum efficiencies (ηext) of 27.1, 25.0, and 15.8% for blue, green, and red light emitting, respectively, which are comparable with the best electroluminescene performance reported for FIrpic-based blue, Ir(ppy)3-based green, and Ir(pq)2(acac)-based red PhOLEDs equipped with a single-component host. The white PhOLEDs based on the o-CzTP host and three lumophors containing red, green, and blue emitting layers were fabricated with the same device structure, which exhibit a maximum current efficiency and ηc of 40.4 cd/A and 17.8%, respectively, with the color rendering index value of 75.

KEYWORDS:

[1,2,4]triazolo[1,5-a]pyridine; high efficiency; high triplet energy; phosphorescent organic light-emitting diodes (PhOLEDs); universal host materials; white organic light-emitting diode

PMID:
29368499
DOI:
10.1021/acsami.7b18202

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