Efficient deep-blue fluorescent emitters from imidazole functionalized anthracenes for simple structure deep-blue electroluminescent devices

Deep-blue organic light emitting diodes (OLEDs) with high color purity are highly desired for high efficiency performing devices. Herein, we report four deep-blue fluorescent small molecules based on anthracene and imidazole moieties, namely mPA-PPPI, mNA-PPPI, mPA-PTPI and mNA-PTPI. These four molecules are composed of either phenyl anthracene (mPA) or naphthyl anthracene (mNA) core, and phenylene-3,5-bis(1-phenylphenanthro imidazole) (PPPI) and phenylene-3,5-bis(1,4,5-triphenyl imidazole) (PTPI) substituents. Their optical, electrochemical, photophysical, and thermal properties have been investigated and their device performances were evaluated. All compounds exhibited deep-blue emission color with excellent thermal and electrochemical stabilities. In particular, the simple structure device based on mPA-PPPI emitted a strong deep-blue color with CIE coordinates of x = 0.15, y = 0.06, low turn on voltage of 3.0 V, high color purity (full width at half maximum of 55 nm) and external quantum efficiency as high as 3.90%.