Novel cyclopenta[def]phenanthrene based blue emitting oligomers for OLEDs

Abstract

Novel blue emitters, oligo-MCPPs (tri-MCPP, tetra-MCPP, and penta-MCPP), have been synthesized and characterized. The introduction of cyclopenta[def]phenantbrene (CPP) units into the structure of oligo-MCPPs gave LEDs with high efficiency and pure blue emission. UV-visible absorption spectra of the thin films of these compounds appear at 333-354 nm, and their maximum PL emission at 416-447 nm. Multilayer organic EL devices with oligo-MCPPs as an emitting layer showed the turn-on voltage of about 4.8 V, the maximum brightness of 1076 cd/m(2) (at 8.2 V), the maximum luminescence efficiency of 0.81 cd/A, and the CIE coordinates of (0.17, 0.14) with blue color. (C) 2008 Elsevier Ltd. All rights reserved.