Carbon Nanoparticles for Counter Electrode Catalyst in Dye-Sensitized Solar Cells
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1102-LL01-05
Carbon Nanoparticles for Counter Electrode Catalyst in Dye-Sensitized Solar Cells Prakash Joshi1, Yu Xie1, Jeremiah Mwaura2, Mike Ropp1, David Galipeau1, and Qiquan Qiao1 1 Center for Advanced Photovoltaics, Department of Electrical Engineering, South Dakota State University, 201 Harding Hall, Brookings, SD, 57007 2 Konarka Technologies, Lowell, MA, 01852 Abstract We report dye-sensitized solar cells using low cost carbon nanoparticles as an alternative to platinum as a counter-electrode catalyst for triiodide reduction. The counter carbon-electrode was deposited onto fluorine-doped tin oxide (FTO) by spin coating from an aqueous colloidal suspension of the blend of carbon nanoparticles and TiO2 nanocrystals. DSSC devices were fabricated using a stable Ru complex dye (Z-907) as the sensitizer. The cells based on carbonnanoparticle counter electrode were made and then compared with those cells from platinum counter electrode at similar fabrication conditions. The results have shown that the device performance in terms of short circuit current density (Jsc), open circuit voltage (Voc) and energy conversion efficiency (η) from the cells based on carbon nanoparticle counter electrode were comparable to those from platinum counter-electrode devices. The carbon nanoparticle based cells have achieved an overall energy conversion efficiency of 5.55% under one sun AM 1.5 illumination (100 mW/cm2). The carbon nanoparticles showed significant potential as a low cost alternative to the current widely-used platinum. I. Introduction Solar energy is an environmentally friendly and sustainable source of energy compared with conventional fossil fuel. Solar cells are the devices to directly convert the solar energy into electricity. However, the electricity generated from solar cells is less than 0.1% of the total energy demand of the world. [1] Fabrication of traditional silicon solar cells requires high-purity silicon and high temperature processing, which leads to high cost of such cells. Dye-sensitized solar cells (DSSCs) have the potential to be a low-cost alternative as silicon solar cells due to their low fabrication and material cost, and high power conversion efficiency. [2-11] A typical DSSC consists of a photoanode and counter electrode separated by an electrolyte. The photoanode is a nanocrystaline TiO2 film deposited on a flourine-doped tin dioxide (FTO) substrate. Counter electrode is generally a platinized FTO and electrolyte is typically an iodide/tri-iodide solution. The dye molecules were attached onto TiO2. When dye molecules are illuminated with sunlight, photoelectrons are injected into TiO2 from the dyes. The photoelectrons travel to the bottom FTO through TiO2, then moves to the counter electrode via an external circuit. The electrolyte gets electrons from the counter electrode. Finally, dye molecules regain the lost electrons quickly from the electrolyte. [12] Currently, platinum is a dominant catalyst counter electrode in DSSCs. Even though the amount of platinum needed for desired catalytic eff
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