Redox-active covalent organic frameworks (COFs) are an emerging class of energy storage materials due to their notably abundant active sites, well-defined channels and highly surface areas. However, their poor electrical conductivity and low electrochemical accessibility to the active sites have severely restricted their practical applications. Here, we demonstrate the fabrication of an anthraquinone-based COFs/graphene composite aerogel (DAAQ-COFs/GA) electrode through electrostatic self-assembly between negatively charged graphene oxide (GO) nanosheets and modified positively charged nanoflower DAAQ-COFs. The obtained freestanding electrode with a 3D crosslinking conductive network efficiently addresses the limitations of sluggish electron transfer and low utilization of the active sites within the organic framework. Owing to the hierarchical porous structure and the rapidly faradaic reactions of redox sites, the electrode exhibits a high specific capacitance of 378 F g⁻¹ at 1 A g⁻¹ and fast kinetics with about 93.4% capacitive contribution at 3 mV s⁻¹. Furthermore, the binder-free DAAQ-COFs/GA and pure graphene aerogel (GA) electrode are assembled into an asymmetric supercapacitor (ASC), showing an energy density up to 30.5 W h kg⁻¹ at a power density of 700 W kg⁻¹. This work demonstrates the great potential of developing high-performance COF-based energy storage devices.

With the wide application of organic semiconductors (OSCs), researchers are now grappling with a new challenge: design and synthesize OSCs materials with specific functions to satisfy the requirements of high-performance semiconductor devices. Strain engineering is an effective method to improve the semiconductor material’s carrier mobility, which is fundamentally originated from the rearrangement of the atomic packing model of materials under mechanic stress. Here, we design and synthesize a new OSC material named AZO-BTBT-8 based on high-mobility benzo[b]benzo[4,5]thieno[2,3-d]thiophene (BTBT) as the semiconductor backbone. Octane is employed to increase molecular flexibility and solubility, and azobenzene at the other end of the BTBT backbone provides photoisomerization properties and structural balance. Notably, the AZO-BTBT-8 photoisomerization leads to lattice strain in thin-film devices, where exceptional device performance enhancement is realized. On this basis, a large-scale flexible organic field-effect transistor (OFET) device array is fabricated and realizes high-resolution UV imaging with reversible light response.