Suppression of green emission in a new class of blue-emitting polyfluorene copolymers with twisted biphenyl moieties

摘要: The color purity of polyfluorene-based blue-emitting polymers is often compromized by “long-wavelength” green emission bands, attributed to polymer interchain species first and more recently formation emissive fluorenone defects. Here, we study the nature suppression such bands via characterization a new class polyfluorene derivatives modified insertion functional groups at bridging points (position C9), so as increase inter-ring torsion angles. We find that solid-state photoluminescence spectra random copolymers polyfluorenes homopolymer display progressive decrease long-wavelength emission. Electroluminescence also show efficient in with concentration ‘twisted' comonomer units 40 % or greater. Quantum-chemical calculations on model oligomers address influence unit angles, resulting excited-state properties; impact molecular packing explored force-field calculations. conclude intra-biphenyl angles viable strategy for polyfluorenes.