Electrical Chiral Assembly Switching of Soluble Conjugated Polymers from Propylenedioxythiophene-Phenylene Copolymers

A π-conjugated polymer of propylenedioxythiophene-phenylene (ProDOT-Ph) with a chiral alkyl substituent on the propylene bridge of ProDOT was prepared to explore reversible multiswitching chiral conjugated polymers (CCPs) capable of electrochromic, electrofluorochromic, and chirality switching. The chiral assembly of the yellow colored poly­(ProDOT-Ph)­s (YPCr) was optimized by annealing the YPCr films at 120 °C. From the thermally annealed YPCr films, we demonstrated the electrical switching of chirality, color, and fluorescence in a single device, for the first time, which was precisely controlled electrochemically to achieve highly efficient and reversible switching of chiral assembly at a low working potential. The YPCr films showed electrochromism with a high coloration efficiency of 690 cm<sup>2</sup> C<sup>–1</sup> by changing color between yellow and blue. The film also exhibited fluorescence switching with a quantum yield change from 3.8 to 0.21 during the reversible electrochemical switching. The chirality of the YPCr, which showed a negative bisignate Cotton effect, was switched reversibly with 97% change in the anisotropy factor (<i>g</i><sub>abs</sub>). The multiswitching properties were correlated to the electrochemical switching in chiral assembly of conjugated polymers according to the electrochemical doping/dedoping process. To the best of our knowledge, the change in Cotton effect during the switching is the highest reported value of a chirality tunable polymer without any chiral inducer. In addition, the YPCr showed a sustainable memory effect for both chirality and coloration.