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Proceedings Paper

Quantifying energy transfer in semiconductor nanocrystals using coherent phonon manipulation and ultrafast spectroscopy (Presentation Recording)
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Paper Abstract

One potential way to increase photovoltaic efficiency is to take advantage of hot-carriers. Nanocrystal based solar cells aim to take advantage of hot-carrier capture to boost device performance. The crucial parameter for gauging a given nanocrystal material for this application is the electron-phonon coupling. The electron-phonon coupling will dictate the thermalization time of hot-carriers. In this study we demonstrate a method of quantifying the electron-phonon coupling in semiconductor nanocrystals. By employing ultrafast transient absorption spectroscopy with temporal pulse shaping, we manipulate coherent phonons in CdTe_{1-x}Se_{x} nanocrystals to quantify the efficiency of the electron-phonon coupling. The Raman active longitudinal optical phonon (LO) modes were excited and probed as a function of time. Using a temporal pulse shaper, we were able to control pump pulse pairs to coherently excite and cancel coherent phonons in the CdTe_{1-x}Se_{x} nanocrystals, and estimate the relative amount of optical energy that is coupled to the coherent CdSe LO mode which is the dominant thermalization pathway for the hot-electrons in this system.

Paper Details

Date Published: 5 October 2015
PDF: 1 pages
Proc. SPIE 9562, Next Generation Technologies for Solar Energy Conversion VI, 956206 (5 October 2015); doi: 10.1117/12.2186831
Show Author Affiliations
Bryan T. Spann, U.S. Naval Research Lab. (United States)
Purdue Univ. (United States)
Xianfan Xu, Purdue Univ. (United States)

Published in SPIE Proceedings Vol. 9562:
Next Generation Technologies for Solar Energy Conversion VI
Oleg V. Sulima; Gavin Conibeer, Editor(s)

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