Asymmetric steric engineering of anthracene emitters through phenyl-p-xylene bridging for deep-blue fluorescent organic light-emitting diodes

초록

We report the molecular design, synthesis, and evaluation of an asymmetric anthracene emitter, namely JNXPAn, with a TTF-compatible (Triplet-Triplet Fusion) molecular architecture aimed at achieving deep-blue emission in fluorescent organic light-emitting diodes (FOLEDs). To limit pi-conjugation extension while maintaining deep-blue emission, the architecture incorporates phenyl-p-xylene linkers. The steric hindrance from the methyl substituents enforces a highly twisted, near-perpendicular geometry between the phenyl unit and adjacent anthracene rings. Modulating intermolecular packing through steric hindrance and molecular twisting has previously proven favorable for TTF activity in anthracene-based fluorescent systems. Owing to the large dihedral angles in JNXPAn, the frontier molecular orbitals are predominantly localized on the central anthracene unit. Nondoped emission JNXPAn layers exhibited maximum external quantum efficiencies of 2.66% with Commission Internationale de L'Eclairage coordinates of (0.18, 0.09), confirming deep-blue emission. These findings offer a concrete design strategy based on steric twisting through phenyl-p-xylene bridging for the development of anthracene-based deep-blue FOLED emitters.

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