Highly transparent and flexible supercapacitors using graphene-graphene quantum dots chelate

Nowadays, transparent and flexible energy storage devices are attracting a great deal of research interest due to their great potential as integrated power sources. In order to take full advantage of transparent and flexible devices, however, their power sources also need to be transparent and flexible. In the present work we fabricated new transparent and flexible micro-supercapacitors using chelated graphene and graphene quantum dots (GQDs) by a simple electrophoretic deposition (EPD) method. Through a chelate formation between graphene and GQDs with metal ions, the GQD materials were strongly adhered on an interdigitated pattern of graphene (ipG-GQDs) and its resulting porous ipG-GQDs film was used as the active material in the micro-supercapacitors. Amazingly, these supercapacitor devices showed high transparency (92.97% at 550 nm), high energy storage (9.09 μF cm^-2), short relaxation time (8.55 ms), stable cycle retention (around 100% for 10,000 cycles), and high stability even under severe bending angle 45° with 10,000 cycles.