Orthogonal anthracene and pyrene derivatives for efficient pure deep-blue organic light-emitting diodes

Abstract

Two new deep-blue emitters based on anthracene and pyrene moieties (9,10-di(pyren-1-yl)anthracene (PyAnPy) and 1,1′-(2,6-di-tert-butylanthracene-9,10-diyl)dipyrene (PyTAnPy)) were designed and synthesized for application in highly efficient triplet-triplet annihilation (TTA)-based organic light-emitting diodes (OLEDs). The twisted conformation between the central anthracene and two pyrene groups effectively interrupts the π-conjugation of the molecules, showing intense deep-blue emission with high photoluminescence quantum yields almost independent of the solvent polarity, due to the absence of the intramolecular charge transfer. The deep-blue TTA OLEDs utilizing PyAnPy and PyTAnPy as the emitters exhibited maximum external quantum efficiencies of 4.78% and 5.48% with Commission Internationale de l'Eclairage coordinates of (0.16, 0.10) and (0.15, 0.06), which perfectly matched the stringent European Broadcasting Union (EBU) blue standard, indicative of very pure deep-blue electroluminescence.