Donor–acceptor polymer electrochromes with cyan color: Effect of alkyl chain length on doping processes

A new series of donor–acceptor–donor (D–A–D) type compounds consisting of dialkyl substituted 3,4-propylenedioxythiophene and benzothiadiazole units were synthesized and polymerized chemically and electrochemically to investigate the effect of alkyl chain length on the doping process of the conjugated polymers. It was found that the alkyl chain length plays a key role on both doping processes and the solubility of the polymer. It is also noteworthy that this new series of D–A–D electrochromes transmits or reflects the cyan color of the Cyan–Magenta–Yellow (CMY) color space in the neutral state which can be switched to transmissive grey when oxidized.

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► A new series of low band gap donor–acceptor type electrochromes were synthesized.
► They have cyan and greenish-blue colors in their neutral states.
► The alkyl chain length plays a key role on both doping processes and the solubility.