High-Performance Solution-Processed Thin-Film Solar Cells: Opportunities and Challenges
David Mitzi, IBM T. J. Watson Research Center
Tuesday, March 5, 2013, 3:30pm
This seminar is part of the Jones Seminars on Science, Technology, and Society series.
The ability to provide an adequate and ever increasing energy supply has been a key driver for technological, economic, and societal change. Given the expected world population increase to above the 8 billion level by mid-century and the necessity to reduce undesirable side effects of burning fossil fuels, there is an acute need for cleaner and more sustainable forms of energy conversion. While the solution to this problem will likely involve a broad portfolio of energy technologies, as cost is progressively reduced, photovoltaic (PV) technology is poised to play a vital role in this story. This talk will focus on two particularly promising thin-film PV technologies based on CuIn1-xGaxSe2-ySy (CIGS) and Cu2ZnSnSe4-ySy (CZTS) compounds as the absorber material. While much of the focus on high-performance PV has been on vacuum-deposition of the component materials, here we will focus on a relatively simple liquid-based deposition process that enables the fabrication of high-performance absorber layers, with resulting device power conversion efficiencies of as high as 15% (for CIGS). The devices have been examined using a variety of physical characterization tools, including electrical transport, external quantum efficiency, photoluminescence and capacitance spectroscopy, leading to a better understanding of factors limiting current-generation device performance. For the relatively new CZTS system, the combination of progressively higher record efficiency, earth abundant metal starting materials, and lower-cost solution-based processing opens opportunities for development of a potentially pervasive PV technology. In addition to CIGS and CZTS, other developing solution-processed inorganic semiconductors are expected to contribute to the evolution of a viable PV industry that can meet required price and performance targets.
About the Speaker
David Mitzi received a B.S.E. in Electrical Engineering from Princeton University in 1985 and a Ph.D. in Applied Physics from Stanford University in 1990. In 1990, he joined the IBM T. J. Watson Research Center and initiated a program examining structure-property relationships, low-cost thin-film deposition techniques, and device applications for a variety of electronic materials (e.g., oxides, organic-inorganic hybrids, chalcogenides). Currently, he manages the Photovoltaic Science and Technology group at IBM and focuses on developing solution-processed high-performance inorganic semiconductors for thin-film PV devices. He holds a number of patents and has authored or coauthored more than 160 papers and book chapters.