Future space science and human exploration missions require solar power photovoltaic PV systems with significantly higher performance such as higher efficiency, higher radiation tolerance, and lower…

This federal contract award, with an ID of NNX15AN18A and a ceiling value of $748,233.56, was granted by the National Aeronautics and Space Administration (NASA) to the University of Arkansas System, doing business as the University of Arkansas at Little Rock (UALR). The contract aims to develop the next generation of high-efficiency four-junction solar cells for space applications, which are critical for future space science and human exploration missions. The project involves researchers from three Arkansas institutions collaborating with experts from three NASA research centers and four industry partners, with NASA Glenn Research Center and SolAero (formerly Emcore) as the key research and manufacturing sites. This contract is not designated as a set-aside. The project seeks to leverage the team's expertise in germanium-tin (GeSn) materials and devices to develop SiGeSn-based photovoltaic (PV) devices that can be monolithically integrated with existing triple-junction cells, providing both improved performance and a lower-cost manufacturing route. Additionally, the research plans to explore SiGeSn two-junction thermophotovoltaic devices for radioisotope power systems. This contract supports NASA's long-term goals and has potential applications beyond just PV, including integrated optoelectronics for imaging, sensing, and optical communications.

Future space science and human exploration missions require solar power photovoltaic PV systems with significantly higher performance such as higher efficiency, higher radiation tolerance, and lower cost than the state of art technology based on triple junction solar cells. Although the recently published space power and energy storage roadmap by NASA has set an aggressive goal for space PV to reach 35 percent, 40 percent, and 45 percent efficiency after 5, 10 and 15 years, respectively, the prevailing triple junction PV technology has reached its efficiency upper limit. This project aims to address this issue by developing the next generation high efficiency four junction solar cells for space applications. The research team includes four researchers from three arkansas institutions and is supported by four experts from three NASA research centers and four industry partners, in which NASA glenn research center and solaero formerly emcore are the key research and manufacture sites for space PV in US. The team has been historically supported by NASA which resulted in fruitful outcomes and strong collaborations among members leading to this proposal. The team members are world leading researchers on gesn materials and devices currently maintain almost all world records in this area ranging from material growth to device performance. The team proposes to utilize their world leading research expertise on gesn materials and devices to develop sigesn based PV devices, which could be monolithically integrated with the existing triple junction cells by providing an optimized 1EV bandgap cell. This approach provides both boosted performance and a low cost manufacture route. The additional benefit is the high radiation tolerance due to the use of sigesn material system. The team proposes to extend the concept of MJ solar cells to develop sigesn two junction thermophotovoltaic devices, which could provide much higher energy conversion efficiency in radioisotope power systems than thermoelectric converters. A systematic research plan includes device design and simulation sigesn material growth and characterization; optical characterization of sigesn materials; development of sigesn photoconductor; development of sigesn PN junctions. The proposed research is strongly relevant to nasas current missions and is expected to bring significant impacts to nasas long term goals. The short term relevance is achieved by aligning the major research tasks in this project with that of current NASA contacts and NASA contractors. The research has much broader impacts beyond just PV applications. Since silicon now is a platform for both integrated circuits and integrated photonics, a SI based optoelectronic material such as sigesn with broad wavelength coverage could lead to the implementation of a new vision of silicon based longwave integrated optoelectronics with a variety of applications such as imaging, sensing, and optical communications, which are highly desirable for future NASA missions. In addition to the research activities, this project also includes intensive interactions among arkansas researchers, NASA experts, and industry partners. The project aims not only to develop long term partnerships with NASA research centers to contribute to NASA missions but also to promote state economic growth and work force development through technology transfer to industry. The project will foster the growth of the overall research infrastructure and therefore enable the team to emerge as a nationally outstanding group to obtain substantial supports from sources outside of the NASA epscor program. A solid sustainability plan within and after the award period is presented with a clear strategy to approach different funding agencies. The team plans to work closely with arkansas space grant consortium to seamlessly integrate the research with a large variety of education and outreach activities.