We present a new synthetic approach to both phenylquinoxaline polymers and low molar mass glasses. A palladium-catalyzed coupling of arylalkynes and bromobenzenes and subsequent oxidation of the triple bonds lead to the corresponding benziles. Reaction with diaminobenzidine yields poly(phenylquinoxalines) (PPQs), whereas the reaction with 1,2-diaminobenzenes leads to low molar mass bis(phenylquinoxalines) (BPQs) and tris(phenylquinoxalines) (TPQs). Both PPQs and TPQs carry tert-butyl or CF3− substituents and are fully soluble in chlorinated hydrocarbons. The starburst TPQs are able to form stable, low molar mass glasses. Cyclic voltammetry reveals that the TPQs have low-lying lowest unoccupied molecular orbitals levels at about −3.6 eV and are attractive as electron-transport materials in organic light-emitting diodes (LEDs). Two-layer LEDs with poly(phenylenevinylene) were fabricated that show a maximum brightness of 450 cd/m2.

Deep level transient spectroscopy measurements have been carried out on ITO poly p-phenylenevinylene Al organic light emitting diodes that have a depletion region type Schottky barrier at the polymer metal interface. The very long lived capacitance transients can be successfully described by the de-trapping of p-type majority carriers from a single energy trap level to a Gaussian distribution of transport states. The Gaussian width of 0.10 0.02 eV and trap depth of 0.75 0.05 eV are in excellent agreement with values measured from other unrelated experimental techniques.

No abstract

No abstract

No abstract