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Title: Determination of the In-Plane Exciton Radius in 2D CdSe Nanoplatelets via Magneto-Optical Spectroscopy

Abstract

Colloidal, two-dimensional semiconductor nanoplatelets (NPLs) exhibit quantum confinement in only one dimension, which results in an electronic structure that is significantly altered compared to that of other quantum-confined nanomaterials. Whereas it is often assumed that the lack of quantum confinement in the lateral plane yields a spatially extended exciton, reduced dielectric screening potentially challenges this picture. Here, we implement absorption spectroscopy in pulsed magnetic fields up to 60 T for three different CdSe NPL thicknesses and lateral areas. Based on diamagnetic shifts, we find that the exciton lateral extent is comparable to NPL thickness, indicating that the quantum confinement and reduced screening concomitant with few-monolayer thickness strongly reduces the exciton lateral extent. Atomistic electronic structure calculations of the exciton size for varying lengths, widths, and thicknesses support the substantially smaller in-plane exciton extent.

Authors:
 [1];  [1];  [2];  [3];  [3]; ORCiD logo [4];  [1];  [2];  [1]
  1. Northwestern Univ., Evanston, IL (United States)
  2. Univ. of California, Berkeley, CA (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1544703
Alternate Identifier(s):
OSTI ID: 1570238
Report Number(s):
LA-UR-19-23578
Journal ID: ISSN 1936-0851
Grant/Contract Number:  
89233218CNA000001; AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 13; Journal Issue: 8; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; High Magnetic Field Science; nanoplatelet; diamagnetic shift; electronic structure; exciton size; quantum confinement

Citation Formats

Brumberg, A., Harvey, S. M., Philbin, J. P., Diroll, B., Lee, B., Crooker, Scott A., Wasielewski, M., Rabani, E., and Schaller, R. D. Determination of the In-Plane Exciton Radius in 2D CdSe Nanoplatelets via Magneto-Optical Spectroscopy. United States: N. p., 2019. Web. doi:10.1021/acsnano.9b02008.
Brumberg, A., Harvey, S. M., Philbin, J. P., Diroll, B., Lee, B., Crooker, Scott A., Wasielewski, M., Rabani, E., & Schaller, R. D. Determination of the In-Plane Exciton Radius in 2D CdSe Nanoplatelets via Magneto-Optical Spectroscopy. United States. doi:10.1021/acsnano.9b02008.
Brumberg, A., Harvey, S. M., Philbin, J. P., Diroll, B., Lee, B., Crooker, Scott A., Wasielewski, M., Rabani, E., and Schaller, R. D. Mon . "Determination of the In-Plane Exciton Radius in 2D CdSe Nanoplatelets via Magneto-Optical Spectroscopy". United States. doi:10.1021/acsnano.9b02008. https://www.osti.gov/servlets/purl/1544703.
@article{osti_1544703,
title = {Determination of the In-Plane Exciton Radius in 2D CdSe Nanoplatelets via Magneto-Optical Spectroscopy},
author = {Brumberg, A. and Harvey, S. M. and Philbin, J. P. and Diroll, B. and Lee, B. and Crooker, Scott A. and Wasielewski, M. and Rabani, E. and Schaller, R. D.},
abstractNote = {Colloidal, two-dimensional semiconductor nanoplatelets (NPLs) exhibit quantum confinement in only one dimension, which results in an electronic structure that is significantly altered compared to that of other quantum-confined nanomaterials. Whereas it is often assumed that the lack of quantum confinement in the lateral plane yields a spatially extended exciton, reduced dielectric screening potentially challenges this picture. Here, we implement absorption spectroscopy in pulsed magnetic fields up to 60 T for three different CdSe NPL thicknesses and lateral areas. Based on diamagnetic shifts, we find that the exciton lateral extent is comparable to NPL thickness, indicating that the quantum confinement and reduced screening concomitant with few-monolayer thickness strongly reduces the exciton lateral extent. Atomistic electronic structure calculations of the exciton size for varying lengths, widths, and thicknesses support the substantially smaller in-plane exciton extent.},
doi = {10.1021/acsnano.9b02008},
journal = {ACS Nano},
number = 8,
volume = 13,
place = {United States},
year = {2019},
month = {6}
}

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