Abstract
Fluorescent 2,3,6,7,9,10-hexaphenylanthracene-based derivatives (HPhAn) were synthesized to serve as deep-blue dopants in organic electroluminescent (EL) devices. The fluorescent emissions of HPhAn fluorophores, fine-tuned from 462 to 449 nm with varied fluorinated phenyl rings attached to the central carbons of the anthracene core, produced photoluminescence quantum yields of 82-88% in the solid state. Unlike the known monostyrylamine deep-blue dopant, these blue dopants in dilute solutions showed no pronounced spectral red shift with increasing solvent polarity; the emission color of HPhAn dopants is thus insensitive to the polarity of the medium. The highest-occupied molecular orbital (HOMO) and lowest-unoccupied molecular orbital (LUMO) energy levels calculated from the oxidation potentials and optical energy gaps are 5.61-5.70 eV and 2.73-2.89 eV, respectively. These thermally robust compounds undergo thermal decomposition at temperatures greater than 300 °C. The relationships among current density, voltage and luminance, the EL efficiency and the operational stability of devices based on the blue HPhAn dopants were examined. These HPhAn-doped EL devices are activated at voltages less than 3.5 V and attained an external quantum efficiency as much as 5.3% in the deep-blue light region with Commission Internationale d'Eclairage (CIE) coordinates (0.14, 0.10), near the National Television System Committee (NTSC) standard blue coordinates (0.14, 0.08). c 2011 The Royal Society of Chemistry.