Novel adamantane-bridged phenanthroimidazole molecule for highly efficient full-color organic light-emitting diodes

Highly efficient deep blue phenanthroimidazole fluorescent material by incorporating an adamantane moiety (AD-BPI) is designed and synthesized. AD-BPI exhibits excellent photophysical properties including a deep blue emission, high triplet energy level and photoluminescence efficiency, fine morphological and thermal stability, and ambipolar nature. Non-doped deep blue organic light-emitting diodes (OLEDs) following the construction of ITO (Indium-Tin Oxide)/TAPC (Bis [44N, N-di (4-tolyl) amino] phenyl]-cyclohexane, 30 nm)/AD-BPI (100 nm)/TPBi (1, 3, 5-tris (2-N-phenylbenzimidazolyl) benzene, 50 nm)/Liq (8-hydroxyquinolatolithium, 2 nm)/Al (100 nm) utilizing AD-BPI as emissive layer achieve the peak external quantum efficiency (EQE) of 5.8% with the CIE coordinates of (0.15, 0.07). Using AD-BPI as universal host, the corresponding green, yellow and red phosphorescent devices are also fabricated and exhibit the maximum EQEs of 23.3%, 16.7% and 19.1% accompanying with negligible efficiency roll-off under ultrahigh luminance. These experimental performances are intensely competitive with the recently reported advanced results of full-color OLEDs. It is the first demonstration of adamantane-based phenanthroimidazole molecule featuring as both host and emitter.