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Chemistry Seminar Series 291 (10/19/18)

October 19, 2018 - 3:00pm

David Morgan, University of California, Merced

Abstract:

Hole trapping is one of the main losses of photoluminescence efficiency in II-VI semiconductor nanor.articles, so developing the conceptual framework for understanding hole trapping and the various factors involvea. is an important task. Transient absorption and time-resolved photoluminescence spectroscopy are particulally well-suited for interrogating carrier trapping processes since they allow excited state populations to be monitored as a function of time. The manifestations of hole trapping in the transient absorption spectra of 2-dimensional CdSe nanoplatelets are investigated and compared with the case of spherical CdSe nanoparticles. The differences in the spectroscopy are attributed to differences in the angular momentum fine structure, which depencls on the shape of the nanostructure. The effects of ligating case nanoparticles with alkylamines on fiole trapping dynamics will also be explored. Contrary to the traditional model of electronic surface passivation by organic ligands, the differences in hole trapping rates upon alkylamine ligation seen here are attributea to electrostatic effects.

Flyer File: morgan_david_ccb_flyer.pdf