It is well known that side chain has a significant impact on its attached conjugated polymer. In addition, charge localization across the conjugated polymer is one of the most important features to control the photophysics including the charge transfer to the molecular acceptors. Herein, we synthesized two azothiazole (ATZ) conjugated polymers coupling with dithiophene (BT) donor using ester and non-ester as side chains. The steady-state measurements of nonester side chain polymer (P1ATZ-BT) shows a strong photoluminance quenching upon successful addition of 1,4-dicyanobenzene (DCB) whereas the ester side chain polymer (P2ATZE-BT) does not exhibit such changes, indicating that the side chain has a significant impact of the photophysical processes of these polymers at the interface with the molecular acceptor. In the effort to explain this behavior, these two polymers were first studied by density functional theory (DFT) calculations and then photo-characterized through steady-state measurements, time-resolved photoluminescence using streak camera, and nanosecond transient absorption spectroscopy. Our DFT results show that introducing the ester chains gives rise to the significant steric effect on the conformation of polymer backbones as well as the localized electron density distributions in P2ATzE-BT. The spectroscopy results confirm that the charge transfer between P2ATzE-BT and DCB is largely suppressed due to the steric hindrance of the polymer backbone induced by the ester side chains.

Photophysics and charge localization of azothiazol-dithiophene conjugated polymers

255th National Meeting (2018)

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