SBIR Phase II: Closed-Field Magnetron Sputtering with RF Plasma Enhancement for Deposition of Thin Films on Large-Area Flexible Substrates for Photovoltaics Applications

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This Small Business Innovation Research (SBIR) Phase II project seeks to develop a turnkey sputter deposition system to provide low temperature thin film deposition of transparent conductive oxide (TCO) materials. A laboratory scale film deposition system using a closed-field magnetron sputtering with RF plasma enhancement was demonstrated. The thin films were grown at lower temperatures than most competing processes. One key advantage of the deposition process developed is its ability to produce TCOs without the need for post-treatments (to achieve both good resistivity and transparency) thereby simplifying the process compatible for high-volume processing of large flat polymeric substrates. The project will demonstrate the process compatible with alternative TCO materials and with photovoltaic applications. The broader impact/commercial potential from this technology will be innovations in photovoltaic (PV) technology. The ability to tap solar energy more efficiently will lead to major breakthroughs for many devices. For years, silicon (Si) solar cells have been the backbone of the solar industry using monocrystalline Si substrate with multiple layers of p-n junction diodes. However, one of the main limiting factors is the shortage of silicon for PV applications as it competes with the existing requirements in the semiconductor industry. Many different PV alternatives are in active development which utilizes TCO materials to provide the conductive anode, cathode, or both. Thin film solar cells provide a good alternative to Si-based solar cells as long as the fabrication cost can be reduced. Thin film solar cells use layers of semiconducting materials with little micrometer thickness and deposited on glass, stainless steel or flexible substrates. One cost-effective method to produce PV devices is through the use of polymers. However, the current device performance of polymer-based PV devices is low but can further be improved by fabricating metal oxide semiconductors embedded on the polymer-based device structure. Thus, this technology will be cost-competitive if the fabrication of TCO thin films are proven they can be done on large-area flexible substrates at lower temperatures.