Poly(m-phenylene): Conjugated Polymer Host with High Triplet Energy for Efficient Blue Electrophosphorescence

A poly( m -phenylene) derivative tethering carbazole unit (PmPCz) is reported to have a triplet energy level ( E T ) as high as 2.64 eV, sufficient to host blue electrophosphorescence. To our best knowledge, this is the first conjugated polymer with E T higher than that of state-of-the-art blue phosphorescent dopant, iridium(III) bis(4,6-(difluorophenyl)pyridinato- N, C 2 )picolinate (FIrpic). PmPCz exhibits good thermal stability and excellent miscibility with the blue phosphorescent dopant, FIrpic. Owing to the high E T and good miscibility, blends of PmPCz with FIrpic show no triplet energy back-transfer and exhibit emission exclusively from FIrpic, even at FIrpic concentration as low as 1 wt %. Single-layer blue phosphorescent polymer light-emitting diode based on the blend exhibits a luminance efficiency of 4.69 cd/A.