A Solar Responsive Battery Based on Charge Separation and Redox Coupled Covalent Organic Framework

Abstract Solar‐responsive battery holds great promise in solar‐to‐electrochemical energy storage, but is impeded by the lack of efficient photoelectrochemical‐cathodes. Herein, a crystalline mesoporous (≈4.0 nm) covalent organic framework (TA‐PT COF) with repeating units consisting of covalently linked triphenylamine (TPA) and perylenetetracarboxylic diimide (PTCDI) is presented. The repeating unit functions as both a donor–acceptor pair and a dual‐redox site to realize a molecule‐level coupling of intramolecular charge separation (τCS = 136.2 ps, τCR = 949 ps) and reversible redox chemistry (C=O/CO−, TPA/TPA+). Equipped with this photoelectrochemical cathode, a reversible aqueous solar‐responsive battery delivered a reliable voltage‐response of 376 mV, an extra round‐trip efficiency of 35% and a good light durability (500 cycles). A photo‐coupled electron/mass transfer mechanism of photoelectrons for Zn 2+ storage and holes for OTf− storage is further revealed, shedding light on a new photoelectrochemical cathode design based on charge separation and redox‐coupled COF for efficient solar‐responsive batteries.