Fast-Switching Vis-IR Electrochromic Covalent Organic Frameworks

Bessinger, Derya; Muggli, Katharina; Beetz, Michael; Auras, Florian und Bein, Thomas (2021): Fast-Switching Vis-IR Electrochromic Covalent Organic Frameworks. In: Journal of the American Chemical Society, Bd. 143, Nr. 19: S. 7351-7357

Abstract

Electrochromic coatings are promising for applications in smart windows or energy-efficient optical displays. However, classical inorganic electrochromic materials such as WO3 suffer from low coloration efficiency and slow switching speed. We have developed highly efficient and fast-switching electrochromic thin films based on fully organic, porous covalent organic frameworks (COFs). The low band gap COFs have strong vis-NIR absorption bands in the neutral state, which shift significantly upon electrochemical oxidation. Fully reversible absorption changes by close to 3 OD can be triggered at low operating voltages and low charge per unit area. Our champion material reaches an electrochromic coloration efficiency of 858 cm(2) C-1 at 880 nm and retains >95% of its electrochromic response over 100 oxidation/reduction cycles. Furthermore, the electrochromic switching is extremely fast with response times below 0.4 s for the oxidation and around 0.2 s for the reduction, outperforming previous COFs by at least an order of magnitude and rendering these materials some of the fastest-switching frameworks to date. This combination of high coloration efficiency and very fast switching reveals intriguing opportunities for applications of porous organic electrochromic materials.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Chemie und Pharmazie > Department Chemie
• Fakultätsübergreifende Einrichtungen: Center for NanoScience (CENS)
• Themengebiete: 500 Naturwissenschaften und Mathematik > 540 Chemie ; 500 Naturwissenschaften und Mathematik > 500 Naturwissenschaften
• ISSN: 0002-7863
• Sprache: Englisch