Small Molecular Reddish-White Light Emitting Electrophosphorescent Devices with Solution Processed Emission Layer

Abstract

We compared the electrical characteristics of polymer, poly(N-vinylcarbazole) (PVK) and small molecule, 4,4′-N,N′-dicarbazole-biphenyl (CBP), N,N′-dicarbazolyl-3,5-benzene (mCP), as host material in white organic light-emitting diodes (OLEDs) fabricated by solution process. In order to obtain the white emission, iridium(III) bis(4,6-difluorophenylpyridinato)-picolinate) (Firpic) and iridium(III) bis(2-phenylquinoline)(acetylaceton) [Ir(pq)₂acac] were used as blue and red emitting dopant, respectively. As a result, devices with PVK, CBP, and mCP have the max. luminous efficiencies of 10.5 cd/A, 9.8 cd/A, and 4.2 cd/A, respectively.

Keywords:

• Host
• organic light-emitting diode
• polymer
• small molecule

Acknowledgments

This work was supported by the Korea Research Foundation Grant (KRF-2009-013-C00031) and the Energy Resources Technology Development program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (2007-E-CM11-P-07). Moreover, we would like to thank Strategy Technology Development program from Ministry of Knowledge Economy (MKE) (10030834).