Quantum and Nanostructure Enhanced Epitaxial Lift-Off Solar Cells

ABSTRACT: MicroLink and its collaborators, Rochester Institute of Technology and Magnolia Solar, will develop a high-efficiency, single-junction, epitaxial lift-off (ELO) GaAs solar cell by incorporating nano-scale features, such as quantum dots and optically functional textures, within the solar cell structure. The principal technical objective of the project is to increase the AM0 efficiency of a large-area single-junction GaAs solar cell to more than 30%. The major innovative aspect of the proposed work is the use of quantum dots to extend the photon collection wavelength range and to improve the coupling of infrared light into the cell. We will also include bandgap engineering solutions, such as introducing thick InGaAs quantum wells into GaAs base, to reduce dark current in the cell. The nano-scale structures will enhance the absorption and trapping of light by the solar cell. We intend to leverage existing quantum dot epitaxy processes developed by Rochester Institute of Technology and bandgap engineering developed by Magnolia Solar, and to combine these with MicroLink"s expertise in multi-junction cell growth and ELO technology. BENEFIT: During the proposed Phase I program we expect to develop large-area, quantum dot-enhanced, single-junction GaAs epitaxial lift-off (ELO) solar cells with efficiency>30% for 1-sun AM0 illumination. The addition of the quantum dots will substantially enhance the infrared response of the solar cell. Future Air Force applications involving autonomous vehicles and space platforms will benefit from the availability of solar cells that have higher efficiency and that are capable of harvesting energy over a broader wavelength range. Integration of quantum dots into ELO solar cells will result in a class of cells that have higher efficiency, are lighter, and have significantly lower cost than conventional triple-junction-on-germanium cells. Commercial applications of the quantum dot-enhanced ELO cells include spacecraft, unmanned aerial vehicles (UAVs), and terrestrial energy harvesting. Commercialization of the quantum dot-enhanced ELO solar cell will be enhanced by MicroLink"s expertise in this technology area: In the last few years, MicroLink has developed a manufacturing line for large-area ELO solar cells; the company has also developed a technology to encapsulate the cells to form lightweight, flexible, robust, high-efficiency solar sheets.