High-efficiency electrophosphorescent organic light-emitting devices based on Schiff base platinum(II) complexes

Abstract

We demonstrate very high-efficiency yellow electrophosphorescence organic light-emitting devices (OLEDs) employing platinum(II) tetradentate Schiff base complexes doping a host of 4,4'-N,N'-dicarbazole-biphenyl (CBP). The OLEDs based on Pt(II) 2 N,N'-bis(salicyli-dene)-1,1,2,2-tetramethylethylenediamine (PtSaltment) give a yellow emission with a peak maximum at 550 nm and a shoulder at 590 nm. The maximum external quantum efficiency (ηext), luminous efficiency (ηL), power efficiency (ηP), turn-on voltage, and brightness of the 4.0 wt% PtSaltment-doped OLED are 11%, 31 cd/A, 14 lm/W, 2.8 V, and 23 000 cd/m2, respectively. Even at a brightness of 10 000 cd/m2, ηext, ηL, and ηP of the OLEDs are 4.1%, 13 cd/A, and 4.0 lm/W, respectively. We attribute the high performance of PtSaltment to its tetramethylethylene group which suppresses the self-quenching behavior.