A New Class of Non-Conjugated Bipolar Hybrid Hosts for Phosphorescent Organic Light-Emitting Diodes

Journal Article · Thu Oct 01 04:00:00 EDT 2009 · Journal of Materials CHemistry

DOI:https://doi.org/10.1039/b909787b· OSTI ID:968019

Zeng, L ^[1]; Lee, T Y.-H.; Merkel, P B; Chen, S H

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1. Laboratory for Laser Energetics, University of Rochester, Rochester, NY

Comprising hole- and electron-transporting moieties with flexible linkages, representative non-conjugated bipolar hybrids have been synthesized and characterized for a demonstration of their potential use as host materials for the fabrication of phosphorescent organic light-emitting diodes. The advantages of this material class include solution processing into amorphous films with elevated glass transition temperatures, stability against phase separation and crystallization, and provision of LUMO/HOMO levels and triplet energies contributed by the two independent moieties without constraint by the electrochemical energy gap. While exciplex formation between the hole- and electron-transporting moieties is inevitable, its adverse effects on spectral purity and device efficiency can be avoided by trapping charges on triplet emitters, as demonstrated for Ir(mppy)3 in TRZ-3Cz(MP)2, and TRZ-1Cz(MP)2. With these two bipolar hybrids and hole-transporting Cz(MP)2 as the host, the maximum current efficiency of the bilayer PhOLED is achieved with TRZ-3Cz(MP)2, but the driving voltage decreases monotonically with an increasing TRZ content.

• Research Organization: Laboratory for Laser Energetics, University of Rochester
• Sponsoring Organization: USDOE
• DOE Contract Number: FC52-08NA28302
• OSTI ID: 968019
• Report Number(s): DOE/NA/28302-916; 2009-146; 1899
• Journal Information: Journal of Materials CHemistry, Journal Name: Journal of Materials CHemistry Vol. 19
• Country of Publication: United States
• Language: English