N-heterocyclic carbazole-based hosts for simplified single-layer phosphorescent OLEDs with high efficiencies

Abstract

Highly efficient single-layer organic light-emitting diodes (OLEDs) are demonstrated using new N-heterocyclic carbazole-based host materials. Phosphorescent OLEDs with a structure of ITO/MoO 3/host/host:dopant/ host/Cs 2CO 3/Al are fabricated in which the new materials act simultaneously as electron-transport, hole-transport, and host layer. Devices with maximum current and external quantum efficiencies of 92.2 cd A -1 and 26.8% are achieved, the highest reported to date for a single-layer OLED. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.