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Title: Revealing the Exciton Fine Structure of PbSe Nanocrystal Quantum Dots Using Optical Spectroscopy in High Magnetic Fields

Abstract

We measure the photoluminescence lifetime τ of excitons in colloidal PbSe nanocrystals (NCs) at low temperatures to 270 mK and in high magnetic fields to 15 T. For all NCs, τ increases sharply below 10 K but saturates by 500 mK. In contrast to the usual picture of well-separated “bright” and “dark” exciton states (found, e.g., in CdSe NCs), these dynamics fit remarkably well to a system having two exciton states with comparable—but small—oscillator strengths that are separated by only 300–900 μeV depending on NC size. Importantly, magnetic fields reduce τ below 10 K, consistent with field-induced mixing between the two states. Magnetic-circular dichroism studies reveal exciton g factors from 2–5, and magnetophotoluminescence shows >10% circularly polarized emission.

Authors:
 [1];  [2];  [1];  [1];  [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. National High Magnetic Field Lab., Los Alamos, NM (United States)
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Advanced Solar Photophysics (CASP)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1065041
DOE Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article
Journal Name:
Phys. Rev. Lett.
Additional Journal Information:
Journal Volume: 105; Related Information: CASP partners with Los Alamos National Laboratory (lead); University of California, Irvine; University of Colorado; Colorado School of Mines; George Mason University; Los Alamos National Laboratory; University of Minnesota; National Renewable Energy Laboratory
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; solar (photovoltaic); solar (fuels); solid state lighting; bio-inspired; electrodes - solar; defects; charge transport; materials and chemistry by design; optics; synthesis (novel materials); synthesis (scalable processing)

Citation Formats

Schaller, Richard D., Crooker, Scott A., Bussian, David A., Pietryga, Jeffrey M., Joo, Jin, and Klimov, Victor I. Revealing the Exciton Fine Structure of PbSe Nanocrystal Quantum Dots Using Optical Spectroscopy in High Magnetic Fields. United States: N. p., 2010. Web. doi:10.1103/PhysRevLett.105.067403.
Schaller, Richard D., Crooker, Scott A., Bussian, David A., Pietryga, Jeffrey M., Joo, Jin, & Klimov, Victor I. Revealing the Exciton Fine Structure of PbSe Nanocrystal Quantum Dots Using Optical Spectroscopy in High Magnetic Fields. United States. https://doi.org/10.1103/PhysRevLett.105.067403
Schaller, Richard D., Crooker, Scott A., Bussian, David A., Pietryga, Jeffrey M., Joo, Jin, and Klimov, Victor I. 2010. "Revealing the Exciton Fine Structure of PbSe Nanocrystal Quantum Dots Using Optical Spectroscopy in High Magnetic Fields". United States. https://doi.org/10.1103/PhysRevLett.105.067403.
@article{osti_1065041,
title = {Revealing the Exciton Fine Structure of PbSe Nanocrystal Quantum Dots Using Optical Spectroscopy in High Magnetic Fields},
author = {Schaller, Richard D. and Crooker, Scott A. and Bussian, David A. and Pietryga, Jeffrey M. and Joo, Jin and Klimov, Victor I.},
abstractNote = {We measure the photoluminescence lifetime τ of excitons in colloidal PbSe nanocrystals (NCs) at low temperatures to 270 mK and in high magnetic fields to 15 T. For all NCs, τ increases sharply below 10 K but saturates by 500 mK. In contrast to the usual picture of well-separated “bright” and “dark” exciton states (found, e.g., in CdSe NCs), these dynamics fit remarkably well to a system having two exciton states with comparable—but small—oscillator strengths that are separated by only 300–900 μeV depending on NC size. Importantly, magnetic fields reduce τ below 10 K, consistent with field-induced mixing between the two states. Magnetic-circular dichroism studies reveal exciton g factors from 2–5, and magnetophotoluminescence shows >10% circularly polarized emission.},
doi = {10.1103/PhysRevLett.105.067403},
url = {https://www.osti.gov/biblio/1065041}, journal = {Phys. Rev. Lett.},
number = ,
volume = 105,
place = {United States},
year = {Wed Aug 04 00:00:00 EDT 2010},
month = {Wed Aug 04 00:00:00 EDT 2010}
}