Color tuning and highly efficient blue emitters of finite diphenylamino-containing oligo(arylenevinylene) derivatives using fluoro substituents

Abstract

New fluoro derivatives of Ph2N-containing (Ph: phenyl) oligo(arylenevinylene) derivatives are prepared by using double Heck-coupling reactions or Horner-Wadsworth-Emmons reactions. These oligomers are highly fluorescent (fluorescence quantum yields Φ = 0.93-0.68) with emissions in a broad wavelength region (448-579 nm), depending on the position of the fluoro substituents. The highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) energy levels of these oligomers are characterized by electrochemistry and UV spectroscopy. The effects of the fluoro substituents on the energy levels are rationalized with HOMO-LUMO simulations. In a classical organic light emitting diode (OLED), one representative (5a) shows a remarkable external quantum efficiency value ηext = 4.87%) at J = 20 mA cm-2; the maximum brightness at 10.2 V is 22 506 cd m-2 (λ = 458 nm; Commission Internationale de l'Eclairage (CIE) coordinates x = 0.14, y = 0.14) with a full width at half-maximum of 54 nm, demonstrating the superiority of these fluoro-containing oligomers in OLED devices. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.