Deep Blue Fluorescent Material with an Extremely High Ratio of Horizontal Orientation to Enhance Light Outcoupling Efficiency (44%) and External Quantum Efficiency in Doped and Non-Doped Organic Light-Emitting Diodes.

A novel bis-4Ph-substituted 9,10-dipehnylanthracene deep blue [1931 CIE (0.15, 0.08)] fluorescent compound, , has been synthesized and characterized for organic light-emitting diode (OLED) applications. Our experimental study of excludes the possibility of triplet-triplet annihilation, hybridized local and charge transfer, or thermally activated delayed fluorescent characteristics of the material. Since the solid-state photoluminescence quantum yield of was determined to be 48%, assuming a 100% for the charge recombination efficiency, the light outcoupling efficiency (η) of an non-doped OLED achieving an external quantum efficiency (EQE) of 5.3% is at least 44%, which is more than twofold higher than 20% for conventional OLEDs. Both grazing incidence wide-angle X-ray scattering (GIWAXS) and angle-dependent photoluminescence (ADPL) measurements reveal having a high value of order parameter () of 0.61 for a ππ stacking along the normal direction and an orientation order parameter () for a horizontal emitting dipole moment of -0.50 or Θ (horizontal-dipole ratios) of 100%, respectively. Otherwise, a refractive index () measurement provides a = 1.80 for thin films. Based on η = 1.2 × , the calculated η is 37%, which is also in accordance with the results of GIWAXS and ADPL. We have also fabricated the classical fluorescent -doped OLEDs, which display a true blue [1931 CIE (0.15 and 0.16)] electroluminescence with a high efficiency (EQE = 6.9%), surpassing the conventional ∼5% EQE. Based on an η of 42% for -doped OLEDs, our studies suggest that the extremely horizontally aligned host material exerts the same horizontal alignment on the dopant molecules.