This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Summary Achieving solar-to-electric energy conversion using inexpensive, abundant and nontoxic materials is an important goal. While silicon is a material that fits most of these criteria, highest efficiency solar cells are made from expensive single crystal wafers. Solar cells based on thin films of semiconductors are emerging as inexpensive alternatives to silicon but the two materials that yield the highest efficiency thin film solar cells, CdTe and CuInGaSe2 (CIGS), have toxic and rare elements (In and Cd). Finding abundant and nontoxic replacements for In and Cd in CIGS solar cells, without sacrificing the high efficiencies reached with these technologies, is a challenge. This work attempts to address this problem.
Intellectual Merit - Copper zinc tin sulfide (Cu2ZnSnS4 or CZTS) is a potential material that has promising attributes for efficient, inexpensive solar cells made from abundant and nontoxic elements. This proposal aims at developing well-controlled deposition methods for CZTS that will result in high quality absorber material for CZTS-based solar cells. We propose to use a synergistic combination of combinatorial deposition methods and careful characterization of films that are found to yield high efficiency solar cells to elucidate the fundamental principles that lead to improvements in efficiency and film quality. The proposed research is on a new material with very high potential for use in solar cells. Very little is known about the properties of CZTS and even less about the process-structure-property-performance relationships for its use in solar cells. The proposed research will result in knowledge on how to deposit high quality CZTS films and to make high efficiency CZTS based solar cells. It will establish the relation between film deposition conditions and electrical, optical and structural properties of the CZTS film. The proposed approach balances the need to establish the fundamental science behind the CZTS solar cell technology and the practical requirement of rapidly moving towards the region of the parameter space that produces high efficiency films relevant to solving a very challenging energy problem.
Broader Impacts - First, the proposed research could provide a solution to the issue related to providing energy to approximately ten billion people using a sustainable technology. Second, this project serves as a vehicle for educating next generation of scientist and engineers who must be trained broadly to function in the increasingly interdisciplinary work place. The project cuts across traditional boundaries between chemistry, physics and engineering and the students involved with this research will be educated in a culture that values interdisciplinary collaboration. Third, the research will be integrated into the outreach and educational activities beyond the training of graduate students. The plan includes five components: (i) continued interactions with Science Museum of Minnesota and Twin Cities Public Television, (ii) continued mentoring of undergraduate students, particularly those from underrepresented groups, (iii) continued mentoring of high school teachers for developing science content for their classrooms, (iv) insertion of PV content into a regional center for technical education in nanotechnology and (iv) volunteering for outreach opportunities that arise in the PIs? local community.
