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Title: Photophysics of Thermally-Assisted Photobleaching in “Giant” Quantum Dots Revealed in Single Nanocrystals [Thermally-Assisted Photobleaching Mechanisms of "Giant" Quantum Dots Revealed in Single Nanocrystals]

Quantum dots (QDs) are steadily being implemented as down-conversion phosphors in market-ready display products to enhance color rendering, brightness, and energy efficiency. However, for adequate longevity, QDs must be encased in a protective barrier that separates them from ambient oxygen and humidity, and device architectures are designed to avoid significant heating of the QDs as well as direct contact between the QDs and the excitation source. In order to increase the utility of QDs in display technologies and to extend their usefulness to more demanding applications as, for example, alternative phosphors for solid-state lighting (SSL), QDs must retain their photoluminescence emission properties over extended periods of time under conditions of high temperature and high light flux. Doing so would simplify the fabrication costs for QD display technologies and enable QDs to be used as down-conversion materials in light-emitting diodes for SSL, where direct-on-chip configurations expose the emitters to temperatures approaching 100 °C and to photon fluxes from 0.1 W/mm 2 to potentially 10 W/mm 2. Here, we investigate the photobleaching processes of single QDs exposed to controlled temperature and photon flux. In particular, we investigate two types of room-temperature-stable core/thick-shell QDs, known as “giant” QDs for which shell growth ismore » conducted using either a standard layer-by-layer technique or by a continuous injection method. We determine the mechanistic pathways responsible for thermally-assisted photodegradation, distinguishing effects of hot-carrier trapping and QD charging. As a result, the findings presented here will assist in the further development of advanced QD heterostructures for maximum device lifetime stability.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ;  [1] ; ORCiD logo [1] ;  [1] ;  [1] ; ORCiD logo [3] ;  [3] ;  [3] ; ORCiD logo [3] ; ORCiD logo [2] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Vanderbilt Univ., Nashville, TN (United States)
  3. Univ. of Texas at Austin, Austin, TX (United States)
Publication Date:
Report Number(s):
LA-UR-18-28798
Journal ID: ISSN 1936-0851
Grant/Contract Number:
89233218CNA000001
Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 12; Journal Issue: 5; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; Material Science; charging; hot-carrier capture; nanocrystal; photo-oxidation; photobleaching; quantum dot; single quantum dot spectroscopy
OSTI Identifier:
1482957

Orfield, Noah J., Majumder, Somak, McBride, James R., Yik-Ching Koh, Faith, Singh, Ajay, Bouquin, Sarah J., Casson, Joanna Lee, Johnson, Alex D., Sun, Liuyang, Li, Xiaoqin, Shih, Chih -Kang, Rosenthal, Sandra J., Hollingsworth, Jennifer A., and Htoon, Han. Photophysics of Thermally-Assisted Photobleaching in “Giant” Quantum Dots Revealed in Single Nanocrystals [Thermally-Assisted Photobleaching Mechanisms of "Giant" Quantum Dots Revealed in Single Nanocrystals]. United States: N. p., Web. doi:10.1021/acsnano.7b07450.
Orfield, Noah J., Majumder, Somak, McBride, James R., Yik-Ching Koh, Faith, Singh, Ajay, Bouquin, Sarah J., Casson, Joanna Lee, Johnson, Alex D., Sun, Liuyang, Li, Xiaoqin, Shih, Chih -Kang, Rosenthal, Sandra J., Hollingsworth, Jennifer A., & Htoon, Han. Photophysics of Thermally-Assisted Photobleaching in “Giant” Quantum Dots Revealed in Single Nanocrystals [Thermally-Assisted Photobleaching Mechanisms of "Giant" Quantum Dots Revealed in Single Nanocrystals]. United States. doi:10.1021/acsnano.7b07450.
Orfield, Noah J., Majumder, Somak, McBride, James R., Yik-Ching Koh, Faith, Singh, Ajay, Bouquin, Sarah J., Casson, Joanna Lee, Johnson, Alex D., Sun, Liuyang, Li, Xiaoqin, Shih, Chih -Kang, Rosenthal, Sandra J., Hollingsworth, Jennifer A., and Htoon, Han. 2018. "Photophysics of Thermally-Assisted Photobleaching in “Giant” Quantum Dots Revealed in Single Nanocrystals [Thermally-Assisted Photobleaching Mechanisms of "Giant" Quantum Dots Revealed in Single Nanocrystals]". United States. doi:10.1021/acsnano.7b07450.
@article{osti_1482957,
title = {Photophysics of Thermally-Assisted Photobleaching in “Giant” Quantum Dots Revealed in Single Nanocrystals [Thermally-Assisted Photobleaching Mechanisms of "Giant" Quantum Dots Revealed in Single Nanocrystals]},
author = {Orfield, Noah J. and Majumder, Somak and McBride, James R. and Yik-Ching Koh, Faith and Singh, Ajay and Bouquin, Sarah J. and Casson, Joanna Lee and Johnson, Alex D. and Sun, Liuyang and Li, Xiaoqin and Shih, Chih -Kang and Rosenthal, Sandra J. and Hollingsworth, Jennifer A. and Htoon, Han},
abstractNote = {Quantum dots (QDs) are steadily being implemented as down-conversion phosphors in market-ready display products to enhance color rendering, brightness, and energy efficiency. However, for adequate longevity, QDs must be encased in a protective barrier that separates them from ambient oxygen and humidity, and device architectures are designed to avoid significant heating of the QDs as well as direct contact between the QDs and the excitation source. In order to increase the utility of QDs in display technologies and to extend their usefulness to more demanding applications as, for example, alternative phosphors for solid-state lighting (SSL), QDs must retain their photoluminescence emission properties over extended periods of time under conditions of high temperature and high light flux. Doing so would simplify the fabrication costs for QD display technologies and enable QDs to be used as down-conversion materials in light-emitting diodes for SSL, where direct-on-chip configurations expose the emitters to temperatures approaching 100 °C and to photon fluxes from 0.1 W/mm2 to potentially 10 W/mm2. Here, we investigate the photobleaching processes of single QDs exposed to controlled temperature and photon flux. In particular, we investigate two types of room-temperature-stable core/thick-shell QDs, known as “giant” QDs for which shell growth is conducted using either a standard layer-by-layer technique or by a continuous injection method. We determine the mechanistic pathways responsible for thermally-assisted photodegradation, distinguishing effects of hot-carrier trapping and QD charging. As a result, the findings presented here will assist in the further development of advanced QD heterostructures for maximum device lifetime stability.},
doi = {10.1021/acsnano.7b07450},
journal = {ACS Nano},
number = 5,
volume = 12,
place = {United States},
year = {2018},
month = {4}
}