Side Chain Effect on the Electrochemical and Optical Properties of Tpd Based Donor Acceptor Donor Type Monomers and Polymers

Abstract

In organic π-conjugated materials, side chains play great roles that are far beyond solubility. In this work, we mainly focused on the synthesis of new donor-acceptor-donor (D-A-D) type conjugated monomers and their corresponding polymers appending TPD acceptor with a new side chain, fluorene, to investigate the side chain effect. In this context, to reveal the precise effect of the side chains on the optical and electrochemical properties of the monomers and polymers synthesized in this work, four series of D-A-D monomers, each containing a TPD core unit with a different side chain, have been discussed in comparison to each other. Notably, it was discovered that TPD acceptor unit can be modified by any functional group other than common alkyl chains to impart new functionalities by keeping their superior optoelectronic properties. New kind of side chains can be used to tune the physical characteristics such as solubility, absorption, emission and molecular packing. In this paper, fluorene-appended monomers as a new class of D-A-D type π-conjugated molecules were studied and it was found that E(Fl) and P(Fl) exhibited resonable quantum yields and their corresponding polymers revealed ambipolar character with slightly lower band gap as compared to the previous analougs containing other side chains. Observed experimental results were elucidated by first principle calculations. In this paper, we discussed that using side chain engineering is an effective strategy to improve next-generation organic π-conjugated materials with the desired properties.