Self-healable PEDOT-based all-organic films with excellent electrochromic performances

Abstract

Since the cracks or scratches that occur during use can degrade the performances and lifetime of organic film electronic devices, the development of self-healing materials holds great potential for durable and sustainable electrochromic devices. However, the simultaneous self-healing of the structures and functions of electrochromic materials still faces enormous challenges. In this study, a strategy to synthesize intrinsically self-healing electrochromic polymer composite films was introduced by integrating electrochromic poly(3,4-ethylenedioxythiophene) (PEDOT) units with thermally self-healable polyurethane (PU-DA) containing reversible Diels–Alder groups. To adjust the self-healing and electrochromic behavior, the copolymerization of 3,4-ethylenedioxythiophene (EDOT) and its hydroxymethyl derivative (EDTM) was also carried out. In terms of a good balance of morphology, self-healing and electrochromic parameters, the prepared intrinsically conductive P(EDOT-co-EDTM)/PU-DA copolymer film has excellent electrochromic properties including a visible light contrast ratio of 47.24%, a fast response time of 0.8 s, and a coloration efficiency of 324.9 cm² C⁻¹. The visible light contrast can be maintained above 93% after 100 cycles. Moreover, the film after breaking up can be intrinsically self-healed through thermal stimulation (no more than 130 °C), and maintains the optical contrast at 95% of the original state.