Improved, solid-state photoelectrochemical cells for converting solar radiation to electricity have been proposed. (In general, photoelectrochemical cells convert incident light to electricity through electrochemical reactions.) It is predicted that in comparison with state-of-the-art photoelectrochemical cells, these cells will be found to operate with greater solar-to-electric energy-conversion efficiencies.
The proposed cells could be fabricated by layering nanocomposites of active particles with organic binders on flexible polymer substrates. Each cell would contain a dye-sensitized semiconductor electrode, a protonconducting solid electrolyte, and a solid-state proton-intercalation counter electrode. By designing the cells to rely on protons as the charge carriers, it should be possible to enable the cells to sustain rates of transport and concentrations of charge carriers greater than those of state-of-the-art photoelectrochemical cells designed to rely on hole conduction and organic semiconductors. The proposed cell configuration is expected to minimize the incidence of recombination of holes and electrons, thereby minimizing the energy losses associated with them and thereby, further, contributing to greater energy-conversion efficiencies.
This work was done by Sri R. Narayan, Andrew Kindler, and Jay F. Whitacre of Caltech for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Electronics/ Computers category. In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
Innovative Technology Assets Management
JPL
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4800 Oak Grove Drive
Pasadena, CA 91109-8099
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Refer to NPO-40539, volume and number of this NASA Tech Briefs issue, and the page number.
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Nanocomposite Photoelectrochemical Cells
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Overview
The document discusses advancements in nanocomposite photoelectrochemical cells developed by NASA's Jet Propulsion Laboratory. These cells aim to improve solar-to-electric conversion efficiencies significantly compared to traditional systems. The proposed configuration utilizes a dye-sensitized semiconductor electrode, a solid proton-conducting electrolyte, and a solid-state proton intercalation counter electrode. This innovative design allows protons to serve as charge carriers, enhancing the transport rate and concentration of charge carriers, which addresses inefficiencies found in existing systems that rely on hole conduction and organic semiconductors.
The document outlines the limitations of conventional dye-sensitized solar cells, which typically use a liquid electrolyte containing a corrosive redox couple based on iodine. These cells face challenges such as encapsulation, sealing, and stability over time, which hinder their commercialization. Previous attempts to create solid-state configurations have either used gelled electrolytes or solid-state hole conductors, but these approaches have led to increased recombination of charge carriers, resulting in lower efficiencies.
The new cell configuration proposed in the document minimizes loss mechanisms, such as recombination, thereby improving overall efficiency. The dye absorbs light energy, becoming excited and releasing protons and electrons. The energetic electrons are injected into the conduction band of nanoparticle n-type titanium dioxide, performing work as they flow through a load and return to the counter electrode. The protons produced from the dye reaction diffuse through the solid proton-conducting electrolyte, facilitating the overall electrochemical process.
The document emphasizes the potential of this new solid-state photoelectrochemical cell to achieve higher solar-to-electric conversion efficiencies than current state-of-the-art systems, which have reached efficiencies of up to 11%. By addressing the limitations of previous designs and focusing on a solid-state approach, this technology represents a significant step forward in the development of efficient and commercially viable solar energy solutions.
In summary, the document highlights a promising new configuration for photoelectrochemical cells that leverages nanocomposite materials and solid-state components to enhance efficiency and stability, paving the way for more effective solar energy conversion technologies.
