Graphene-Indanthrone Donor-π-Acceptor Heterojunctions for High-Performance Flexible Supercapacitors

To overcome the low energy density bottleneck of graphene-based supercapacitors and to organically endow them with high-power density, ultralong-life cycles, etc., one rational strategy that couple graphene sheets with multielectron, redox-reversible, and structurally-stable organic compounds. Herein, a graphene-indanthrone (IDT) donor-pi-acceptor heterojunction is conceptualized for efficient and smooth 6H(+)/6e(-) transfers from pseudocapacitive IDT molecules to electrochemical double-layer capacitive graphene scaffolds. To construct this, water-processable graphene oxide (GO) is employed as a graphene precursor, and to in situ exfoliate IDT industrial dyestuff, followed by a hydrothermally-induced reduction toward GO and self-assembly between reduced GO (rGO) donors (D) and IDT acceptors (A), affording rGO-pi-IDT D-A heterojunctions. Electrochemical tests indicate that rGO-pi-IDT heterojunctions deliver a gravimetric capacitance of 535.5 F g(-1) and an amplified volumetric capacitance of 685.4 F cm(-3). The assembled flexible all-solid-state supercapacitor yields impressive volumetric energy densities of 31.3 and 25.1 W h L-1, respectively, at low and high power densities of 767 and 38 554 W L-1, while exhibiting an exceptional rate capability, cycling stability, and enduring mechanically-challenging bending and distortions. The concept and methodology may open up opportunities for other two-dimensional materials and other energy-related devices.