Synthesis of carbazole-based light-emitting polymers incorporating 2,5-bis(phenylethenyl)-4-decyloxyanisole as collateral fluorophore
2008
Takagi, Kōji | Nakagawa, Tsuyoshi | Takao, Hidenobu
The Suzuki coupling polymerization between bis(carbazole) monomer (CzDB) and 9,9-dihexylfluorene-2,7-diboronic acid was carried out to obtain PFCz-PEDA0 having the number-averaged molecular weight of 7000. The absorption and emission maximum wavelengths were observed at 344 and 408 nm, respectively. The quantum yield (QY) was relatively low (0.12) because of the photo-induced electron transfer. Subsequently, CzPEDA-bearing 2,5-bis(phenylethenyl)-4-decyloxyanisole (PEDA) segment sandwiched with 3-bromocarbazole units was copolymerized to give PFCz-PEDAn (n = 05, 10, 20, 35, and 50). The content of PEDA segment in polymer could be controlled by the monomer feed ratio. In CHCl₃ solution, the absorbance at around 400 nm became larger with one isosbestic point at 370 nm, and the emission peak at 448 nm became prominent with increasing the PEDA content. The QY of polymer was increased as the PEDA content, which was a consequence of the fluorescence resonance energy transfer from carbazole-containing chromophore (energy donor) to PEDA fluorophore (energy acceptor). In spin-coated film, the maximum QY was obtained in PFCz-PEDA05 having the most appropriate molar balance of energy donor and acceptor units.
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