报告题目（Title）：Silicon-based tandem solar cell research at Arizona State University
报 告 人（Speaker）：Zachary Holman (Arizona State University)
报告时间（Time）：2018年10月24日（周三） 上午 9：00
The historical learning rate for silicon PV modules is approximately 30%, whereas the area-related balance-of-systems learning rate is 10% in the U.S. residential, commercial, and utility markets. This imbalance has created the leveraging effect of module efficiency (or annual energy yield, more accurately) on system cost that has driven cell and module technology advances over the past decade, and it will continue to do so. The path to manufactured single-junction cells with efficiencies up to approximately 27% is foreseeable, but the route beyond is opaque. The most promising approach is to couple silicon with a wider-bandgap top cell to form a tandem, but no appropriate top cell exists and coupling is not trivial.
I will begin this seminar with a methodology for picking top-cell partners to pair with silicon, and demonstrate that it reveals that GaAs—unfortunately, and despite its “wrong” bandgap—is the best-performing top-cell candidate presently available. I will then introduce a generalized PV system analysis that defines the top-cell cost and performance targets that would enable top-cell/silicon tandems to compete in the market. Finally, I will review the present status at ASU of wide-bandgap II-VI (CdMgTe and CdZnTe) and perovskite top-cells, as well as their tandems with silicon heterojunction solar cells. Key results include a record-efficiency CdMgTe monocrystalline top cell (15.2% with 1.2 V Voc), CdMgTe polycrystalline top cell (10.7%), and perovskite/silicon tandem cell (23.6% officially reported, with higher values to be shared soon).
Zachary Holman is an Assistant Professor and an ASU Trustees Professor in the School of Electrical, Computer, and Energy Engineering at Arizona State University. He received his Ph.D. in Mechanical Engineering from the University of Minnesota for his work on plasma-synthesized silicon and germanium nanocrystals, after which he spent two years as a postdoctoral researcher developing high-efficiency silicon solar cells at EPFL in Switzerland. His research group at ASU focuses on new materials and device designs for high-efficiency silicon solar cells and silicon-based tandem solar cells. He is also the co-founder of an advanced materials start-up company, Swift Coat.