An Azo-Based Electrode for All-Around High-Performance Flexible Supercapacitors.

The photo-rechargeable supercapacitor enables the self-powering of flexible wearable electronics. However, flexible wearable electronics require supercapacitors not only with excellent flexibility but also with high energy density. P-diaminoazobenzene (P-Azo) as a new type of organic electrode material with N=N is directly connected to the benzene ring and forms a large π-conjugated system, which makes it have a lower lowest unoccupied molecular orbital (LUMO) energy level, is beneficial to transfer of electrons, and increases the conductivity of organic molecules. In addition, N=N can realize the transfer of two electrons, which makes P-Azo have a higher energy density. Asymmetric flexible supercapacitors are fabricated by assembling P-Azo, activated carbon, and an adhesive electrolyte, with 425.2 mW h cm-2 (55.19 Wh kg-1) energy density at a power density of 80 mW cm-2 (10.38 W kg-1), and 90.7% capacitance retention after 80 000 cycles of bending. In this work, supercapacitors and perovskite submodules are coupled to prepare a photo-rechargeable supercapacitor to achieve a 7% overall energy-conversion efficiency. Therefore, this supercapacitor paves a practical route for powering future wearable electronics.