Synthesis and Properties of Benzodipyrrolidone (BDP)-Based Donor-Acceptor Copolymers

New donor−acceptor copolymers PBDP-36CZ and PBDP-27CZ incorporating both the electron-withdrawing benzodipyrrolidone (BDP) unit and the strong electron-donating carbazole unit were synthesized via Suzuki cross coupling with Pd(dppf)Cl2 as the catalyst. The photophysical and electrochemical properties of the resulting polymers were fully characterized. The UV-Vis absorption spectra showed that both PBDP-36CZ and PBDP-27CZ possess obvious intramolecular charge transfer (ICT) transition absorption and the maxima of absorption wavelength in chloroform were at 511 and 517 nm for PBDP-36CZ and PBDP-27CZ, respectively, while the monomer BDP exhibited an absorption maximum at 468 nm. Further, the low energy gaps of the polymers PBDP-36CZ and PBDP-27CZ, estimated from their electrochemical curves, were 1.83 eV and 1.53 eV, respectively.