Multicomponent open shell donor-acceptor diradical polymers: design, synthesis, and characterization

Organic semiconductor polymers can be classified into unary, binary, ternary, and quaternary conjugated polymers based on the types of their structural units. The binary polymers based on the Donor (D)-Acceptor (A) architecture have witnessed significant progress, and ternary and quaternary polymers have been sporadically reported, conjugated polymers with five or more components have yet to be reported. In this study, we designed and successfully synthesized multi-component conjugated polymers, exemplified by a ten-component system. We systematically characterized the chemical structures, electrochemical behavior, photophysical properties, and photothermal conversion performance of these materials using ¹H NMR, UV-vis-NIR absorption spectroscopy, cyclic voltammetry, electron spin resonance, and photothermal performance testing. A transition from a relatively closed-shell to an open-shell ground state as the molecular bandgap decreased. Notably, P10-FTBBT exhibited distinct open-shell diradical character, reduced fluorescence quantum yield, and enhanced photothermal conversion efficiency.