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

Abstract 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.