Substituent effects of iridium complexes for highly efficient red OLEDs

摘要

This study reports substituent effects of iridium complexes with 1-phenylisoquinoline ligands.The emission spectra and phosphorescence quantum yields of the complexes differ from that of tris(l-phenylisoquinolinato-C~2,N)iridium(III)(Irpiq)depending on the substituents.The maximum emission peak,quantum yield and lifetime of those complexes ranged from 598-635 nm,0.17-0.32 and 1.07-2.34 us,respectively.This indicates the nature of the substituents has a significant influence on the kinetics of the excited-state decay.The substituents attached to phenyl ring have an influence on a stability of the HOMO.Furthermore,those substituents have effect on the contribution to a mixing between ~3pi-pi-pi and ~3MLCT for the lowest excited states.Some of the complexes display the larger quantum yield than Irpiq,which has the quantum yield of 0.22.The organic light emitting diode(OLED)device based on tris [1-(4-fluoro-5-methylphenyl)isoquinolinato-C~2,N]iridium(III(Ir4F5Mpiq)yielded high external quantum efficiency of 15.5% and a power efficiency of 12.41m W~(-1)at a luminance of 218 cd m~(-2).An emission color of the device was close to an NTSC specification with CIE chromaticity characteristics of(0.66,0.34).