Design, Synthesis, and Characterization of Weil-Defined Amorphous Molecules for Use in Organic LEDs

摘要

Two strategies are presented for making amorphous organic chromophores with well-defined dimensions that exploit the superior qualities of polymers and small molecules with respect to LED fabrication. These qualities are resistance to crystallization, purity, high luminescence efficiency, and high solubility required for spin casting. Tetrakis(4-(4'-(3",5"-dihexyloxystyryl)styryl)stilbenyl)methane (T-4R-OC_6H_(13)) exemplifies a strategy consisting of four oligophenylenevinylene fragments ("arms") connected to a tetrahedral point of convergence. Bulk samples are amorphous and the film-forming qualities are useful for the fabrication of LEDs with low turn-on voltages. In a related strategy, tris[l-(N-ethylcarbazolyl)-1 -(3' ,5' -hexyloxybenzoyl) methane]-(phenanthroline) europium was designed using a modular approach. It incorporates functionalities for electron and hole transport, solubility, and resistance to crystallization. LEDs were fabricated and studied.