Synthesis and Characterization of Poly(9,9-dialkylfluorenevinylene benzobisoxazoles): New Solution-Processable Electron-Accepting Conjugated Polymers

We present the synthesis of four new solution-processable, fluorescent poly(arylenevinylene)s containing benzobisoxazole and fluorene moieties. Two different moieties (cis- and trans-benzobisoxazole) and two different alkyl substituents (octyl and 3,7-dimethyloctyl) were used to study the impact of the structure on the electronic, optical, and thermal properties of these polymers. The polymers were characterized using UV-visible and fluorescence spectroscopy, cyclic voltammetry, thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). All of the polymers possess moderate molecular weights, good solubility in aprotic organic solvents, high fluorescence quantum efficiencies in dilute solutions, and high electron affinities. Cyclic voltammetry revealed quasi-reversible reduction for these polymers. Solution-processed light-emitting diodes using dilute blends of the polymer in a poly(N-vinyl carbazole) matrix gave blue emission with luminous efficiencies of up to 1 Cd/A at similar to 470 nm which is very promising for deep blue-emitting polymer LEDs.