Applications of polymer coatings consisting of 9,9′-(4,4′-sulfonylbis(4,1-phenylene))biscarbazole and thiophene derivatives in electrochromic devices

A carbazole derivative (9,9′-(4,4′-sulfonylbis(4,1-phenylene))biscarbazole (SpDc)) was synthesized; subsequently, P(SpDc), P(SpDc-co-TP), P(SpDc-co-MTP), P(SpDc-co-PTP), and P(SpDc-co-HTP) films were electrochemically coated on ITO/glass substrates. Electrochromic characterizations show that the P(SpDc) film is pale ochre, dark khaki, moss green, and dark olive green at 0.0, 0.8, 1.0, and 1.1 V, respectively. The square wave potential step absorptiometry of the polymeric coatings shows that the P(SpDc-co-PTP) film exhibits a high transmittance change (ΔT = 52.8%) and a moderate coloration efficiency (η = 120.8 cm² C⁻¹). Furthermore, dual-layer electrochromic devices (ECDs) were fabricated using P(SpDc), P(SpDc-co-TP), P(SpDc-co-MTP), P(SpDc-co-PTP), and P(SpDc-co-HTP) as anodic coatings and PProDOT-Bz₂ as the cathodic coating. P(SpDc-co-TP)/PProDOT-Bz₂ ECD exhibited multicolored electrochromism, a high ΔT (50.9% at 635 nm), a high η (820.5 cm² C⁻¹ at 635 nm), and a fast switching time (less than 0.1 s). Given the adequate electrochromic performance of the organic coatings, it can be inferred that these coatings could be used in promising organic ECD applications.