Given the expected world population increase to above the 8 billion level by mid-century and the associated ever-increasing energy demand, coupled with 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 options, the progressive reduction of cost and ubiquitous "fuel" supply for photovoltaic (PV) technologies suggests that this pathway is poised to play a vital role in this mix. This talk will address several particularly promising thin-film PV technologies based on Cu-In-Ga-S-Se (CIGS) and Cu-Zn-Sn-S-Se (CZTS) compounds as the absorber material and a relatively simple liquid-based film deposition process that enables the fabrication of high-performance absorber layers, with resulting device sunlight-to-electricity power conversion efficiencies of as high as 15%. Key aspects of this story include focus on developing appropriate solution / precursor chemistries, and thin film deposition and defect engineering approaches. 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, the metal-halide-based perovskite compounds, which offer near-ambient temperature solution processing, a high degree of opportunity for chemical tunability, and unprecedented improvement in efficiency to the 20+% level over only a few short years of development, will also be discussed. These three technologies provide outstanding examples of how solution-based processing may, not only lead to an avenue for low cost PV, but also to performance levels that can rival and sometimes even beat vacuum-based deposition, which is crucial if these technologies are to have market penetration.
"Solution Processing of Thin-Film Solar Cells: Opportunities and Challenges", Dr. David Mitzi, Duke University, Department of Mechanical Engineering and Materials Science
Tuesday, January 27, 2015 - 11:40am