This Small Business Innovation Research Phase I project will develop a silicon solar cell with unique junction design that provides synergistic benefits as the thickness of the solar cell is reduced. Thin silicon solar cells are currently the subject of intense interest because, in comparison to conventional bulk silicon solar cells: (a) they can be produced by "kerfless" techniques that result in a tiny fraction of silicon usage, as compared to conventional cells, and (b) their reduced recombination volume leads to higher open circuit voltage and therefore higher efficiency. To date, however, the open circuit voltages and efficiencies of thin silicon solar cells have generally not exceeded their bulk silicon counterparts. Our junction design will help fulfill the promise of high open circuit voltage in these systems, ultimately enabling greater than 20% efficiency with less than 5% of the silicon usage of conventional silicon solar cells. The Phase I effort will achieve open circuit voltage greater than 700 mV and efficiency greater than 19% for ultra-thin (10 micron) cells with an industrially feasible solar cell design. In Phase II and beyond, we will transition these findings to pilot-scale production tools and demonstrate greater than 20% efficient ultra-thin silicon solar cells. The broader impact/commercial potential of this project is as follows. If successful, this project will help enable lower-cost generation of electricity by photovoltaics, by radically reducing the amount of silicon used in the solar cell and by boosting cell efficiency. In addition, our process leads to a uniquely physically robust thin Si wafer, which will lead to increased downstream manufacturing yield, further lowering cost. This project will also advance the basic science of solar cells by exploring a novel junction design. In Phase I, our team will present results at prominent conferences devoted to photovoltaics, and publish articles on this technology in peer-reviewed technical journals. Commercially, we plan to partner with manufacturing tool suppliers to demonstrate the new integrated wafer at pilot scale. The solar cells and modules can be readily finished using stranded solar manufacturing assets in the United States. We will further partner with large-scale manufacturers to bring this technology to market. It is uniquely suited to rooftop products, which will create an opportunity to partner with manufacturers who are not presently in the solar products business
