Dual-band modulating electrochromic smart windows with broad temperature adaptability based on triazine-ring-based molecules and hyperbranched polymers

Abstract

Electrochromic smart windows have long been constrained by challenges including dual-band modulation capability, cycling stability, and environmental durability. To address these, three redox centers were constructed using triazine-ring-based molecules to enable multi-level control functionality, demonstrating superior spectral regulation in both visible (Vis, 76.12% modulation efficiency) and near-infrared (NIR, 82.71%) regions. The synthesized molecule 4,4′-(6-(1-3-butenyl)pyridine)-1,3,5-triazine-2,4-diylbis(1-benzylpyridine) (TBBET) suppresses molecular dimerization through steric hindrance, enhancing room-temperature cycling stability. Incorporating hyperbranched polymers (HBPs) forms a robust hydrogen-bond network to anchor TBBET, improving cycling stability at extreme temperatures: optical modulation remains at 97.84% at 70 °C and 99.56% at −50 °C. The synergistic mechanism of HBPs was investigated via physicochemical characterization and molecular dynamics simulations. The present work provides a new insight into enhancing the practicality of electrochromic smart windows.