Design bifunctional nitrogen doped flexible carbon sphere electrode for dye-sensitized solar cell and supercapacitor

Abstract

Developing a highly effective bifunctional electrode material is vital to the self-powered integrated electronics that combine the energy conversion unit of the dye-sensitized solar cell (DSC) and the energy storage unit of the supercapacitor. In this study, a nitrogen doped carbon sphere (NCS) is synthesized to promote the electrode activity as compared with that of the conventional solid carbon sphere (SCS) in both DSC and supercapacitor systems. In the DSC system, the rigid and flexible devices using NCS counter electrodes yield power conversion efficiencies of 8.64% and 6.73%, much higher than those of the devices using SCS counter electrodes (6.96% and 4.57%). As a supercapacitor working electrode, the NCS shows a remarkable specific capacitance of 224.6 F g−1, much higher than the counterpart value of the SCS electrode (124.9 F g−1) under the same conditions, which demonstrates capacitance improvement by 79.8%. Moreover, NCS preserves more than 90.0% of their initial capacitance after long term stability tests, suggesting a perfect cycle life. The enhanced activity of the NCS can be ascribed to the improved conductivity, charge transfer, and mass transport processes caused by nitrogen doping.