Introducing Conjugation Spacer in Electrochromic Metallo-Supramolecular Polymer for Enhanced Optical Memory Effect

The excellent optical memory effect of electrochromic materials plays a significant role in the construction of a bistable electrochromic device that has great potential application prospects in the field of energy-saving. Extensive efforts have been devoted to improving the optical memory effect of electrochromic devices by conducting device engineering, whereas fewer efforts focus on molecular engineering at the molecular level. Herein, a scalable method is developed to prepare a new metallo-supramolecular polymer (MSP) with conjugation spacer among the polymeric skeleton, which switches from deep purple to transmissive with excellent electrochromic performance, such as fast switching speed (1.3 and 3.8 s for coloring and bleaching process, respectively), high coloration efficiency (1052.5 cm 2 C −1 at 576 nm) and long-term cycling stability (decreases 14.1% after 1000 cycles). Moreover, due to the introduction of a conjugation spacer in the molecular skeleton, the optical memory effect of PolyFe-PF 6 film is enhanced considerably, which only attenuates 12% after cutting off the external potential for 3600 s. As a demonstration of its potential application, an electrochromic device switching from purple to transmissive is fabricated. These results illustrate the introduction of a conjugation spacer into the molecular skeleton is an effective strategy for improving the optical memory effect of MSPs.