@article{964c019586c74ba1b8075839021ba669,
title = "Anisotropic Transient Disordering of Colloidal, Two-Dimensional CdSe Nanoplatelets upon Optical Excitation",
abstract = "Nanoplatelets (NPLs) - colloidally synthesized, spatially anisotropic, two-dimensional semiconductor quantum wells - are of intense interest owing to exceptionally narrow transition line widths, coupled with solution processability and bandgap tunability. However, given large surface areas and undercoordinated bonding at facet corners and edges, excitation under sufficient intensities may induce anisotropic structural instabilities that impact desired properties. We employ time-resolved X-ray diffraction to study the crystal structure of CdSe NPLs in response to optical excitation. Photoexcitation induces greater out-of-plane than in-plane disordering in 4 and 5 monolayer (ML) NPLs, while 3 ML NPLs display the opposite behavior. Recovery dynamics suggest that out-of-plane cooling slightly outpaces in-plane cooling in 5 ML NPLs with recrystallization occurring on indistinguishable time scales. In comparison, for zero-dimensional CdSe nanocrystals, disordering is isotropic and recovery is faster. These results favor the use of NPLs in optoelectronic applications, where they are likely to exhibit superior performance over traditional, zero-dimensional nanocrystals. ",
keywords = "Nanoplatelets, X-ray diffraction, anisotropic disordering, nonequilibrium phenomena, transient heating",
author = "Alexandra Brumberg and Kirschner, {Matthew S.} and Diroll, {Benjamin T.} and Williams, {Kali R.} and Flanders, {Nathan C.} and Harvey, {Samantha M.} and Leonard, {Ariel A.} and Watkins, {Nicolas E.} and Cunming Liu and Kinigstein, {Eli D.} and Jin Yu and Evans, {Austin M.} and Yuzi Liu and Cuthriell, {Shelby A.} and Shobhana Panuganti and Dichtel, {William R.} and Kanatzidis, {Mercouri G.} and Wasielewski, {Michael R.} and Xiaoyi Zhang and Chen, {Lin X.} and Schaller, {Richard D.}",
note = "Funding Information: The authors thank D. C. Hannah, M. J. Wagner, D. Hayes, A. Y. Chang, and C. E. Rowland for their assistance in collecting TR-XRD data on quasi-spherical zinc blende CdSe NCs as well as W. Ji and A. Natraj for their assistance in conducting static XRD on CdSe NPLs. This material is based upon work supported by the National Science Foundation under Grants 1629383 and 1808590, as well as by the National Science Foundation Graduate Research Fellowship Program under Grant DGE-1842165 (A.B., S.M.H., N.E.W., A.M.E., and S.P.). This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-FG02-99ER14999 (M.R.W.). A.B. gratefully acknowledges support from a 3M Graduate Research Fellowship, the Ryan Fellowship, and the International Institute for Nanotechnology at Northwestern University. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facilities operated by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A.A.L., M.S.K., and L.X.C. are partially supported by the Ultrafast Initiative of the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, through Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Parts of this work were performed at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS). DND-CAT is supported by Northwestern University, E.I. DuPont de Nemours & Co., and the Dow Chemical Company. Publisher Copyright: {\textcopyright} 2021 The Authors. Published by American Chemical Society.",
year = "2021",
month = feb,
day = "10",
doi = "10.1021/acs.nanolett.0c03958",
language = "English (US)",
volume = "21",
pages = "1288--1294",
journal = "Nano letters",
issn = "1530-6984",
publisher = "American Chemical Society",
number = "3",
}