High Efficiency InGaN Solar Cells

The SBIR program’s goal is to demonstrate the feasibility of fabricating inherently radiation hard, high efficiency solar cells based on InGaN photovoltaic devices using both MBE for material parameter optimization and MOCVD for manufacturability. Recent results by our SBIR partner at Cornell show that InN has a much narrower bandgap than previously believed: 0.7 eV, compared to earlier estimates of 2 eV. This discovery opened the door to fabrication of photovoltaic devices responsive from the near infrared through UV ranges. Thus, unprecedented efficiencies should be possible. In addition, the inherent robustness of nitrides implies all-nitride-based solar cells have potentially greater radiation resistance and an ability to operate under temperature extremes than those currently available. In this program Structured Materials Industries (SMI) is utilizing its expertise in MOCVD technology, as well as recent success in developing and demonstrating a highly efficient nitride MOCVD system, to carry nitride-based solar cells from laboratory to production. In the ongoing Phase I effort, together with Dr. William Schaff of Cornell University, a pioneer in InN and InGaN technology, we have made outstanding progress in solving key materials issue in the system. Dr. Schaff is using his facility MBE tool and analytic capabilities to focus on material property optimization, especially the crucial issue of improving the quality of In-rich InGaN, including n- and p-type doping and junction interface understanding. SMI is focused on transitioning Cornell development into a solar cell manufacturing-ready process. Fabrication and demonstration of prototype devices and process scale-up will take place in Phase II. Successful completion of this program will enable a new class of radiation-hardened, robust, efficient, economical solar cells for space and terrestrial applications, to be produced in Phase III.