Dye-sensitized solar cells based on carbon counter electrode

We used a new method to make carbon catalyst counter electrodes for dye-sensitized solar cells (DSSCs) by coating a fluorine-doped tin oxide (FTO)-glass with carbon nanoparticles from an aqueous colloidal suspension of the blend of carbon nanoparticles (particle size ≪50 nm and surface area ≫ 100 m²/g ) and TiO2. Z-907 dye was used as the sensitizer. The electrolyte effects on device performance were investigated using two systems: electrolyte 1 is a mixture of 0.5M LiI and 0.05M I2 in propylene carbonate; electrolyte 2 is a mixture of 0.60M BMII, 0.03M I2, 0.10M GuSCN, 0.5 M tertbutylpyridin in a mixing solvent of acetonitrile and valeronitrile. Electrolyte 2 could prevent back charge transfer from TiO2 to the triodide in the electrolyte. Devices from electrolyte 2 showed a significant improvement in Voc and device efficiency. Overall we achieved an external energy conversion efficiency of 4.3 % using electrolyte 2 with a short circuit current density (Jsc) of 15.71 mA/ cm² and an open circuit voltage (Voc) of 0.71 V under an AM 1.5 illumination (100 mW/cm²).