Novel bipolar host for highly efficient green, yellow, orange, red and deep-red phosphorescent organic light-emitting devices

A novel bipolar host tris（4-（pyrimidin-5-yl）phenyl）amine （TPMTPA） constructed by incorporating triphenylamine as the electron-donating core and pyrimidine as the electron-accepting peripheries was designed and synthesized. TPMTPA achieves excellent bipolar charge transport properties and has high enough triplet energy level to sensitize green, yellow, orange, red and deep-red phosphors. By using TPMTPA as a host, high performance green, yellow, orange, red and deep-red phosphorescent organic light-emitting devices （PhOLEDs） were demonstrated with maximum external quantum efficiencies of 20.4%, 17.6%, 15.1%, 15.3% and 15.7% respectively. These results suggested that TPMTPA is a versatile high performance host for PhOLEDs of different emission colors.