Issue 31, 2012

Incorporation of a CN group into mCP: a new bipolar host material for highly efficient blue and white electrophosphorescent devices

Abstract

A novel bipolar host material mCPCN has been designed and synthesized by incorporating the electron-accepting CN group into the well-known benchmark host material mCP. Compared to mCP, the incorporation of the simple and small CN group significantly improves thermal/morphological stabilities (Tg = 97 °C and Td = 313 °C) and increases the electron affinity, while keeping electronic transition energies unaltered and maintaining a high triplet energy (ET = 3.03 eV). Characteristics of single-carrier devices containing mCPCN indicate its rather balanced hole/electron injection and transport properties. Highly efficient blue phosphorescent organic light emitting devices (PhOLEDs) with maximum external quantum, current and power efficiencies of 26.4%, 58.6 cd A−1, and 57.6 lm W−1, respectively, were achieved using mCPCN as the bipolar host material and bis[(4′,6′-difluorophenyl)pyridinato-N,C2′]iridium(III) picolinate (FIrpic; ET = 2.65 eV) as the triplet emitter. Furthermore, blue PhOLEDs adopting mCPCN exhibit impressively low efficiency roll-offs, retaining high quantum efficiencies of ∼25% at 1000 cd m−2 and ∼20% even at 8000 cd m−2. mCPCN has also been successfully used in implementing highly efficient white PhOLEDs having external quantum efficiencies in excess of 23%.

Graphical abstract: Incorporation of a CN group into mCP: a new bipolar host material for highly efficient blue and white electrophosphorescent devices

Article information

Article type
Paper
Submitted
30 Apr 2012
Accepted
11 Jun 2012
First published
13 Jun 2012

J. Mater. Chem., 2012,22, 16114-16120

Incorporation of a CN group into mCP: a new bipolar host material for highly efficient blue and white electrophosphorescent devices

M. Lin, S. Yang, H. Chang, Y. Huang, Y. Tsai, C. Wu, S. Chou, E. Mondal and K. Wong, J. Mater. Chem., 2012, 22, 16114 DOI: 10.1039/C2JM32717A

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