Proceedings of 6th International Conference on Hybrid and Organic Photovoltaics (HOPV14)
Publication date: 1st March 2014
Dye-sensitized solar cells (DSCs) are a promising technology among the so-called third generation of photovoltaic cells. DSCs use materials fairly abundant/environmentally friendly for lowering production costs and increase sustainability. This technology is now emerging due to its superior performance under more demanding atmospheric conditions and semi-transparency properties [1]. Nevertheless, to turn DSCs a truly cost-competitive alternative to conventional photovoltaic devices in the energy market it is necessary new cost-effective materials. Amongst them it is the replacement of the catalyst material used for the photoelectrochemical reaction that takes place at the counter-electrode side of DSCs.
To date, there was no other material capable of matching both the electrocatalytic activity for the I3−/I− redox couple (the most used electrolyte system), and the high optical transparency of the traditionally used Pt electrodes. Although transparency is not mandatory for a DSC, it is highly appreciated as it increases the product value by enabling its use in building integrated applications (BIPV), as well as in other solutions such as tandem cells.
Here we present the first graphene-based CE capable of replacing Pt (yielding simultaneously high efficiency and transparency) for iodine-based electrolyte systems in liquid-junctions DSCs. When nickel nanoparticles are placed between a FTO substrate and oxidized graphene platelets, they are capable of partially restoring the electronic double bonds along the platelets as well as improving ohmic resistance between the catalytic material and the FTO layer (Figure 1). Both materials and processes should enable the fabrication of a cheaper DSC.
The microstructure and morphology of the prepared counter-electrodes werecharacterized by FE-SEM, TEM, AFM and Raman analysis. TGA/DTA and XPS were used to evaluate the oxygen content at the graphene platelets. The optimization of the graphene-based counter-electrodes involved maximizing its catalytic activity (efficiency) and transparency by creating a sufficient number of active sites while ensuring enough conductivity in the graphene platelets and a good electrical contact with the substrate [2]. This evaluation was carried out using half-cells and complete DSCs [3]; characterization included I-V and EIS analysis.
The use of the graphene/Ni CE was also validated to cobalt complexes electrolytes/ porphyrin dyes systems. This was done because conventionally used Pt/iodide-triiodide/ruthenium dye systems have efficiency limitations [4]; the cobalt complexes/ porphyrin dyes systems have the potential to yield high-efficiency (> 12 %) cells, with graphene being the best suitable material to act as the catalytic layer [5-9].
Highly transparent, low cost and easily scalable CEs for DSCs, comprised of a structured graphene film over nickel nanoparticles (graphene/Ni CE), matched the energy conversion efficiencies of the reference platinum CE for liquid-junction iodine and cobalt-based electrolytes.
1.O'Regan, B. and M. Grätzel, A Low-Cost, High-Efficiency Solar-Cell Based on Dye-Sensitized Colloidal TiO2 Films. Nature, 1991. 353(6346): p. 737-740. 2.Kavan, L., J.H. Yum, and M. Grätzel, Optically Transparent Cathode for Dye-Sensitized Solar Cells Based on Graphene Nanoplatelets. Acs Nano, 2010. 5(1): p. 165-172. 3.Cruz, R., D.A. Pacheco Tanaka, and A. Mendes, Reduced graphene oxide films as transparent counter-electrodes for dye-sensitized solar cells. Solar Energy, 2012. 86(2): p. 716-724. 4.Hamann, T.W., The end of iodide? Cobalt complex redox shuttles in DSSCs. Dalton Transactions, 2012. 41(11): p. 3111-3115. 5.Roy-Mayhew, J.D., et al., Functionalized graphene sheets as a versatile replacement for platinum in dye-sensitized solar cells. ACS Applied Materials and Interfaces, 2012. 4(5): p. 2794-2800. 6.Kavan, L., et al., Graphene nanoplatelet cathode for Co(III)/(II) mediated dye-sensitized solar cells. Acs Nano, 2011. 5(11): p. 9171-9178. 7.Yella, A., et al., Porphyrin-Sensitized Solar Cells with Cobalt (II/III)-Based Redox Electrolyte Exceed 12 Percent Efficiency. Science, 2011. 334(6056): p. 629-634. 8.Stefik, M., et al., Carbon-graphene nanocomposite cathodes for improved Co(ii/iii) mediated dye-sensitized solar cells. Journal of Materials Chemistry A, 2013. 1(16): p. 4982-4987. 9.Ju, M.J., et al., N-Doped Graphene Nanoplatelets as Superior Metal-Free Counter Electrodes for Organic Dye-Sensitized Solar Cells. ACS Nano, 2013. 7(6): p. 5243-5250.
nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.
Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.
International Conference on Hybrid and Organic Photovoltaics
International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.
The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.