101 / 2026-10-16 20:20:16

Redox-Bipolar Electrochromic Covalent Organic Frameworks

electrochromic,covalent organic framework

Electrochromic materials that reversibly regulate light transmission are promising for energy-efficient windows and adaptive displays. Covalent organic frameworks (COFs) offer molecularly designable, porous structures, yet many COF electrochromic systems are limited by micropore-restricted ion transport and monopolar redox activity, which constrain charge compensation and optical modulation. Here, we report a mesoporous, two-dimensional bipolar COF that integrates electron-rich triphenylamine-derived TAAB donors with electron-deficient naphthalene dianhydride (NTCDA) acceptors in a hexagonal conjugated framework. The complementary redox centers support oxidation and reduction within one material, while the mesoporous architecture facilitates electrolyte-ion access. Their combination promotes coupled charge transfer and bidirectional ion compensation, enabling bias-dependent multicolor switching. The COF achieves optical modulation from the visible to the near-infrared. In a symmetric device, both electrodes participate in charge compensation, supporting broad spectral control and stable cycling. This work highlights how integrating complementary redox units with an ion-accessible porous structure can expand the electrochromic functionality of COFs. The design offers a versatile platform for durable, multistate electrochromic devices, with potential for adaptive solar control and information display.