Observation of red intraligand electrophosphorescence from a stilbene-containing Re(I) complex

Abstract

Red organic light-emitting diodes using a rhenium(I) bipyridyl complex, fac-[ClRe(CO)3(trans-4-methyl-4′-(2-4-octadecyloxylphenyl)vinyl)-2,2′-bipyridine] (Re-mopvb), as an emitter were fabricated. The optimized device has a bilayer structure of indium-tin oxide∕poly(N-vinylcarbazole): 2 wt. % Re-mopvb (80 nm)∕2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (50 nm)∕LiF (1 nm)∕Al (150 nm). Although no photoluminescence from Re-mopvb in the room-temperature solution appeared due to photoinduced isomerization, a bright red electrophosphorescence from an intraligand excited state of Re-mopvb was observed at room temperature, indicating the promising future of such a class of electroluminescent materials. The maximum luminance exceeding 120cd∕m2 at 11 V and maximum efficiency of 0.75 cd∕A at 7.5 V were obtained.