CASPER Seminar Series Presents - Andrew Yost, Doctoral Candidate, Department of Physics and Astronomy, University of Wyoming

DateMarch 31, 2017Time2:30 - 3:30 pm
LocationBSB E.125

Andrew J. Yost
Doctoral Candidate, Department of Physics and Astronomy, University of Wyoming

A Microscopic Understanding of Solar Cell Materials Using Scanning Tunneling Microscopy

Abstract: In the face of the world energy crisis and climate change, solar energy is the leading potential resource that can ensure a sustainable energy source free from carbon emission which is also capable of being produced for generations to come. Among the next generation solar cells, organo-metallic mixed halide perovskite solar cells(OMHPSCs) and quantum dot sensitized solar cells (QDSSCs) show promises towards this goal. OMHPSCs have recently drawn plenty of attention due to their low cost and extraordinary power conversion efficiency performance. The efficiency of the solar cells using Pb-based perovskites increased from ~3 % in 2009 to ~21 % in 2016. On the other side, the efficiency of quantum dot sensitized solar cells has increased more slowly, 10.6%, on roughly the same time scale. Many different techniques have been used to improve device performance and overall efficiency. One way to improve the efficiency is to tailor the band-gap of the device materials to be most suitable for charge separation and conduction. There exist many ways to tailor a material's band-gap: one example is changing the stoichiometric ratio of the halides in an OMHP, another example is introducing dopants, more specifically Mn dopants in semiconducting QDs. Understanding how the stoichiometry of a solar cell material or how a dopant influences the band structure are a couple paths toward better band-gap tailoring and thus achieving higher efficiency photovoltaics. In this seminar we will look at how scanning tunneling microscopy is utilized in conjunction with a suite of other characterization tools to study the microscopic electronic band structure in an OMHP and in several Mn doped QD systems.

Bio: Andrew J. Yost is a Ph.D. candidate in the Department of Physics and Astronomy at the University of Wyoming. Before attending the University of Wyoming Andrew graduated from Baylor University in 2011 with a B.S. in Physics. Presently Andrew is a NASA Space Grant graduate research fellow and the assistant editor for Emerging Science Journals, Flexible Electronics.

For more information, contact Sherri Honza at 254-710-1271

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