Three-dimensional ordered macroporous carbon as counter electrodes in dye-sensitized solar cells

• 3D ordered macroporous carbon (3DOM-C) was synthesized via a cost-effective route.
• The 3DOM-C was applied in dye-sensitized solar cells (DSSC) as counter electrodes.
• The DSSC with 3DOM-C counter electrodes achieved an efficiency of 2.91%.
• The efficiency was 81% of DSSC based on Pt electrodes under similar conditions.
• The 3DOM-C could be one of the promising candidates for counter electrodes of DSSC.

Three-dimensional ordered macroporous carbon (3DOM-C) was synthesized through polystyrene (PS) colloidal crystal templates using carbonized glucose solutions as a carbon source and sulfuric acid as a dehydrating agent. The obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen-sorption isotherm measurement. SEM results showed that the layers of the PS templates were hexagonal close-packed with a large surface area, and the diameter of the PS microspheres was 300–320 nm. SEM and TEM results demonstrated that the 3DOM-C displayed a unique structure of a well-developed 3D-interconnected ordered macroporous framework with a pore diameter of 260–280 nm. The photovoltaic current voltage curves showed that the dye sensitized solar cells (DSSC) fabricated by the 3DOM-C as a counter electrode exhibited an energy conversion efficiency (η = 2.91%), a short circuit current (Jsc = 9.51 mA/cm2), an open circuit voltage (Voc = 0.59 V) with a fill factor (FF = 52%), which were much closed to those of Pt counter electrode-based DSSC (3.59%, 10.05 mA/cm2, 0.59 V, 58%) and better than those of activated carbon-based one. Moreover, the electrochemical impedance spectroscopy analysis demonstrated a low charge-transfer resistance (RCT) for 3DOM-C (3.48 Ω cm2), which was close to that of Pt (1.54 Ω cm2), and much lower than that of activated carbon (15.05 Ω cm2). Finally, the 3DOM-C showed a comparable efficiency compared to a conventional Pt counter electrode.