Facile synthesis of high-crystallinity graphitic carbon/Fe₃C nanocomposites as counter electrodes for high-efficiency dye-sensitized solar cells.

Because of the advantages of both rapid electron transport of graphitic carbon and high catalytic performance of Fe3C nanoparticle, highly crystalline graphitic carbon (GC)/Fe3C nanocomposites have been prepared by a facile solid-state pyrolysis approach and used as counter electrode materials for high-efficiency dye-sensitized solar cells (DSSCs). The content of Fe3C in the composites can be modified by different hydrochloric acid treatment time. In comparison with pure highly crystalline GC, the DSSC based on GC/Fe3C nanocomposite with 13.5 wt % Fe3C content shows higher conversion efficiency (6.04%), which indicates a comparable performance to the Pt-based DSSC (6.4%) as well. Moreover, not only does our DSSCs have comparable performance to that of the Pt-based DSSC (6.4%), but also is more cost-effective as well. To evaluate the chemical catalysis and stability of nanocomposite counter electrodes toward I3(-) reduction and the interfacial charge transfer properties, GC/Fe3C nanocomposites have been quantitatively characterized by cyclic voltammetry, electrochemical impedance spectra, and Tafel polarization curve. All the results have revealed that the GC/Fe3C nanocomposite counter electrodes can exhibit high catalytic performance and fast interfacial electron transfer, which can be acted as a very promising and high cost-effective materital for DSSCs.