Nitrogen-doped mesoporous carbon as low-cost counter electrode for high-efficiency dye-sensitized solar cells

We demonstrate an excellent performance of nitrogen-doped mesoporous carbon (NMC) as a low-cost counter electrode for dye-sensitized solar cells. NMC materials are prepared using melamine-formaldehyde resin as carbon precursor and silica nanoparticles as template. Nitrogen adsorption analysis shows that the as-prepared NMC samples had a high surface area, large pore volume and bimodal mesopore structure with maxima at ∼3.5 nm and ∼16 nm. Electrochemical impedance spectroscopy tests reveal a low charge-transfer resistance of 1.45 Ω cm2 for NMC electrode in iodide/triiodide redox electrolyte. Such excellent electrocatalytic activity for iodide/triiodide redox reaction of NMC electrode can be attributed to a unique combination of nitrogen doping, bimodal mesopore structure and high surface area. A power conversion efficiency of 7.02% is achieved for the dye-sensitized solar cell with NMC counter electrode, which is comparable to that of the device with Pt counter electrode. These results reveal that NMC electrode is a promising low-cost alternative to Pt counter electrode in dye-sensitized solar cells.