Multichromic polymers based on 5-[3,5-di(carbazol-9-yl)phenyl]benzene-1,3-dicarbonitrile and dithiophene derivatives for rapid switching electrochromic devices

Abstract

A dicarbonitrile-substituted homopolymer (P(dCzCN)) and four dCzCN-containing copolymers (P(dCzCN-co-bTP), P(dCzCN-co-TF), P(dCzCN-co-CPDT), P(dCzCN-co-CPDTK)) were polymerized electrochemically on an indium tin oxide (ITO) glass substrate. The P(dCzCN) film was light gray, yellowish gray, and greenish gray at 0.0 V, 1.2 V, and 1.5 V, respectively. The electrochromic switching of the polymer films revealed that P(dCzCN-co-bTP) showed a high transmittance change (ΔT = 61.0% at 1000 nm), and P(dCzCN-co-CPDTK) exhibited a high coloration efficiency (η = 292.4 cm2 C−1 at 950 nm). Moreover, dual-layer electrochromic devices (ECDs) were constructed using P(dCzCN), P(dCzCN-co-bTP), P(dCzCN-co-TF), P(dCzCN-co-CPDT), and P(dCzCN-co-CPDTK) as the anodic layers and PEDOT as the cathodic layer. The P(dCzCN-co-bTP)/PEDOT ECD revealed a high ΔT (38.0% at 630 nm), a high coloration efficiency (η = 531.4 cm2 C−1 at 630 nm) and a fast switching time ( ≤0.3 s). The abovementioned electrochromic performances imply that dicarbonitrile-substituted polycarbazoles provide high transmittance changes and fast switching in electrodes for ECDs. P(dCzCN-co-bTP) copolymers were electrocoated onto ITO-coated glass substrates. A dual-type complementary electrochromic device (ECD) was fabricated using P(dCzCN-co-bTP) as anodically coloring electrochromes and PEDOT as the cathodically coloring electrochrome. The P(dCzCN-co-bTP)/PEDOT ECD revealed a high ΔT (38.0% at 630 nm), a high coloration efficiency (η = 531.4 cm2 C−1 at 630 nm) and a fast switching time ( ≤ 0.3 s). P(dCzCN-co-bTP)/PEDOT ECD showed yellow at 0.0 V and blue at 1.8 V.