Synthesis and Opto-Electronic Properties of Functionalized Pyrimidine-Based Conjugated Polymers

Side chain engineering has been used for tuning the opto-electronic properties of organic semiconductors. In this work, a series of pyrimidine-based donor-acceptor (D-A) conjugated polymers functionalized with electron-withdrawing or electron-donating side chains were synthesized. The opto-electronic properties of the pyrimidine D-A conjugated polymers were investigated focusing on the dependence on the electron withdrawing strength of the acceptor moiety, while maintaining the same donor moiety. Fine-tuning of the energy levels was achieved by introducing electron donating (alkoxy [—OR] and alkylthio [—SR]) or electron withdrawing (alkylsulfinyl [—SOR] and alkylsulfonyl [—SO₂R]) side chains onto the acceptor moiety. The effects of side chain modification have been investigated through DFT calculations, UV–vis analysis, and electrochemical measurements.