Pyrrolo[3,4-c]pyridine-1,2-dione: a new electron acceptor for electrochromic conjugated polymers

Abstract

A new pyrrolo[3,4-c]pyridine-1,2-dione (PPyD) electron acceptor was synthesized via the Diels Alder reaction between N-alkyl maleimide dienophile and 1,2,4-triazine moieties. PPyD was subsequently used to construct five donor–acceptor type conjugated polymers, P1–P5, with thiophene-based donors. The electrochromic properties of the five polymers were studied, showing that the polymers exhibit a range of colours from orange to red and magenta in the neutral state, and switch to blue, green, and yellow, upon applying positive voltages. Good optical contrasts of up to 70.5%, fast switching speeds down to 3.2 s and high colouration efficiencies up to 590 C cm⁻² were recorded. This work demonstrates the potential of the novel PPyD acceptor as a promising building block for electrochromic conjugated polymers, and probably other organic electronics.