The 2nd QLC seminar was held at the Tohoku University Katahira Campus.

The 2nd QLC seminar
Date&Time: 2019/08/02 (Fri) 14:00-16:00
Place: IMRAM West 1st Building Seminar Room (2F), Katahira campus,
Tohoku University (B06)
Title: Role of Organic Molecules in the Physics of Organic-Inorganic
Lead Iodide Perovskites
Speaker: Prof. Seung-Hun Lee
Affiliation: Department of Physics, University of Virginia

The realization of economical renewable energy technologies is critical
for securing long term prosperity of mankind and mitigating the threat
of climate change. Power from the Sun is the most abundant source of
renewable energy. In just one hour, more solar energy hits the Earth’s
surface than humanity uses in an entire year. Therefore, development of
solar cells that can produce electrical power at a cheaper rate than
fossil fuel based electricity is highly desirable. However, only about 1
percent of the world’s energy production currently comes from solar
cells. This is because the conventional technologies, mostly based on
silicon solar cells, are too expensive to be competitive with energy
generated by burning fossil fuels. What is needed is research on new
solar cell materials that can be fabricated into solar cells with
high-efficiency and low-cost simultaneously.

Hybrid Organic-Inorganic perovskites (HOIPs) have recently been
discovered as one of the most promising next generation solar cell
materials. Solar cells based on HOIPs have achieved high efficiency that
rivals that of the conventional silicon solar cells. At the same time,
HOIPs can be deposited on surfaces from ink solutions which enable
low-cost and high-throughput manufacturing of solar cells as if printing
out newspapers. In this talk, I will present our recent research that
revealed microscopic mechanism of the photovoltaic properties of HOIPs.[1-3]

1. Origin of Long Lifetime of Band-Edge Charge Carriers in
Organic-Inorganic Lead Iodide Perovskites, Tianran Chen, Wei-Liang Chen,
Benjamin J. Foley, Jooseop Lee, Jacob Ruff, J. Y. Peter Ko, Craig M.
Brown, Leland W. Harriger, Depei Zhang, Changwon Park, Mina Yoon,
Yu-Ming Chang, Joshua J. Choi, and Seung-Hun Lee, Proc. Natl. Acad. Sci.
114, 7519-7524 (2017).
2. Entropy Driven Structural Transition and Kinetic Trapping in
Formamidinium Lead Iodide Perovskite, Tianran Chen, Benjamin J. Foley,
Changwon Park, Craig M. Brown, Leland W. Harriger, Jooseop Lee, Jacob
Ruff, Mina Yoon, Joshua J. Choi, and Seung-Hun Lee, Science Advances 2,
e1601650 (2016).
3. Rotational dynamics of organic cations in CH3NH3PbI3, T. Chen, B. J.
Foley, B. Ipek, M. Tyagi, J.R.D. Copley, C. M. Brown, J. J. Choi, S.-H.
Lee, Phys. Chem. Chem. Phys. 17, 31278-31286 (2015).