Events Calendar

Physics Colloquium - Graduate Student Presentations

This is a past event.

Virtual Event

Thursday, April 22, 2021, 4 pm

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This is a past event.

Thursday, April 22 @ 4pm – Zoom

Jeff Kabel  [Advisor: Dr. Yoke Khin Yap] will present: 

Molybdenum Disulfide Quantum Dot-Sensitized Solar Cells based on Sustainable Oxide Thin Films

Thin-film solar cells show promise for light-weight, low-cost, large area, flexible devices. Unlike competing materials, zinc oxide (ZnO) and molybdenum trioxide (MoO3) are relatively abundant, environmentally stable, biologically compatible, and have been proven effective for use in quantum dot-sensitized solar cells. The surfaces of nanostructures are often dominated with dangling bonds capable of trapping charges and limiting effective charge transport after electron-hole separation. Thus, it is anticipated that quantum dot-sensitized ZnO solar cells will be more efficient than devices constructed with traditional ZnO nanostructures. Molybdenum disulfide (MoS2) has attractive features, including its semiconducting nature and indirect-to-direct band gap transition when cleaved from bulk to monolayer. MoS2 quantum dots have been shown to have broad absorption bands, and good biocompatibility, potentially making them invaluable for environmentally friendly QD-sensitized photovoltaic devices. In this work, initial results of MoS2 QD-Sensitized ZnO thin film solar cells will be discussed.



Oindabi Mukherjee [Advisor: Dr. Robert Nemiroff] will present: 

A Search for Dark Matter Gravitational Millilensing in Fermi GRBs

If the Universe was filled with a significant fraction of compact dark matter, gravitational lens echoes would be expected in the light curve immediately following a Gamma-Ray Burst (GRB). Dark matter, acting as a lens, would cause some light rays from the GRB to arrive at a delayed time and hence such an echo should be detected in the background of the GRB. However, this would depend on the relative observer, lens, and source orientation as well as the mass of the compact dark matter. Although the theory has been well established, no such gravitational echo has yet been detected in the light curves of a GRB. The non-detection of an echo in the background of the light curves of sources such as GRBs can lead us to improve limits on the nonexistence of compact dark matter within a specific mass range. 430 GRBs from the FERMI satellite have been used to search for such echoes utilizing the Chi-square method. Based on the present dark matter density parameter (0.3), the fractional density of compact dark matter lenses that should be found is computed and is then compared with the results obtained from the statistical tests. Preliminary results are presented limiting the existence of compact dark matter with a mass ranging from 106 Mʘ to 1010 Mʘ. I will also be presenting some preliminary analysis on a recent claim of a lensing event in GRB data from 1995.

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*If you have registered in the past for the Physics Colloquium series, please use your orignal zoom link from Dr. Nakamura (, or request him to send the registration confirmation email to you again.

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