Luminescence of molecular and block copolymeric 2,7-bis(phenylethenyl)-fluorenones; Identifying green-band emitter sites in a fluorene-based luminophore

2,7-Bis(3,4,5-trimethoxyphenylethenyl)fluorenone (OFOPV) and a segmented oligomer analogue linking OFOPV units with polymethylene flexible spacersalt-poly(2,6-dimethoxylphenylene-4-vinylene-[9-fluorenone-2-yl-7-vinylene]3,5-dimethoxyphenylene-4-[1,6-hexanedioxyl]) (pFOPV)were synthesized and their luminescence properties studied. Solution-phase photoluminescence (PL) of OFOPV and pFOPV shows concentration-dependent relative intensities of a fine-structured higher energy band and a featureless lower energy band, consistent with solution excimer formation. Neat film PL and electroluminescence (EL) spectra using 100% OFOPV and pFOPV emitter layers show red emission bands (λmax ∼ 610 nm). Solid film PL spectra of OFOPV diluted in PMMA or Zeonex are significantly blue-shifted relative to the neat film spectra. PL and EL spectra of 2,7-bis(3,4,5-trimethoxyphenylethenyl)-9,9-diethylfluorene (OFPV) blended with <1% by weight of OFOPV gives significant green region (g-band) emission in addition to the normal blue ...