Emission color tuning of new fluorene-based alternating copolymers containing low band gap dyes

New fluorene-based alternating copolymers (PFPhPhCN, PFPhThCN, and PFThThCN) containing different comonomers have been designed and subsequently synthesized via Pd-catalyzed Suzuki polymerization. The synthesized polymers could be well characterized by 1H NMR, FT-IR, and elemental analyses. These polymers were found to be thermally stable and readily soluble in common organic solvents. The UV-vis absorption maxima of PFPhPhCN, PFPhThCN, and PFThThCN were 399, 456 and 499 nm, and the PL maxima were 484, 539 and 620 nm, respectively. The emitting color of the homopolymer, poly(9,9-dioctylfluorene-2,7-diyl) (PDOF), could be tuned by incorporating various low band gap dyes into the polymer main-chain. The absorption and emission maxima of the copolymers were varied according to the type of incorporated aromatic group (thiophene or phenylene). In particular, PFThThCN exhibited almost pure red emission (chromaticity values x = 0.63, y = 0.37).