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Impact of Shell Crystal Structure on the Thermal Stability and Photophysical Behavior of Blue Quantum dots

Wang, Junfeng ; Chen, Qing ; Huang, Fei ; Meng, Jie LU ; Li, Jiawei ; Lan, Zhenyun ; Zheng, Qian ; Tian, Shuyu ; Zheng, Kaibo LU and Pullerits, Tönu LU , et al. (2025) In Advanced Optical Materials
Abstract

Epitaxial shell is vital for enhancing the optoelectronic performance of semiconductor quantum dots (QDs), especially for the wide bandgap blue QDs, yet the shell crystal structure's impact on thermal stability and photophysical behavior remains unexplored. It is reported that the ligand-directed synthesis of ZnS shells with zinc blende (ZB) or wurtzite (WZ) structure on blue WZ CdZnS cores, where sulfur precursor (Trioctylphosphine-S/octanethiol) dictates crystal phase through their thermal stability and coordination effects. WZ ZnS exhibits a lower Cd2⁺ diffusion barrier than ZB ZnS due to reduced cation density in octahedral vacancies, lowering electrostatic repulsion. Consequently, ZB-shell QDs maintain sharp core-shell... (More)

Epitaxial shell is vital for enhancing the optoelectronic performance of semiconductor quantum dots (QDs), especially for the wide bandgap blue QDs, yet the shell crystal structure's impact on thermal stability and photophysical behavior remains unexplored. It is reported that the ligand-directed synthesis of ZnS shells with zinc blende (ZB) or wurtzite (WZ) structure on blue WZ CdZnS cores, where sulfur precursor (Trioctylphosphine-S/octanethiol) dictates crystal phase through their thermal stability and coordination effects. WZ ZnS exhibits a lower Cd2⁺ diffusion barrier than ZB ZnS due to reduced cation density in octahedral vacancies, lowering electrostatic repulsion. Consequently, ZB-shell QDs maintain sharp core-shell boundary and energy band alignment, improving anti-thermal quenching and structural stability: fluorescence decreased by only 8% versus 17% for WZ-shell QDs with increasing temperature from 200 to 300 K, and retained 81% fluorescence intensity (vs. 36%) after 15 days at 100 °C. The rigid ZB lattice also weakens exciton-phonon coupling (simulated γLO = 39 meV vs. 67 meV for WZ). Conversely, WZ-shell QDs form alloyed interfaces enabling smooth energy band alignment, enhancing carrier delocalization. This suppresses Auger recombination, yielding a biexciton lifetime of 126 ps—nearly double that of ZB-shell QDs (69 ps)—and slower decay kinetics (τav = 16.7 ns vs. 55 ns).

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organization
publishing date
type
Contribution to journal
publication status
epub
subject
keywords
blue quantum dot, carrier dynamics, core-shell interface, ligand directed-phase control, thermal stability
in
Advanced Optical Materials
publisher
John Wiley & Sons Inc.
external identifiers
  • scopus:105017854219
ISSN
2195-1071
DOI
10.1002/adom.202502247
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 Wiley-VCH GmbH.
id
4d6fac6b-2b7d-4f44-804e-bc5cc2fcbc69
date added to LUP
2025-10-28 17:13:05
date last changed
2025-10-31 13:14:41
@article{4d6fac6b-2b7d-4f44-804e-bc5cc2fcbc69,
  abstract     = {{<p>Epitaxial shell is vital for enhancing the optoelectronic performance of semiconductor quantum dots (QDs), especially for the wide bandgap blue QDs, yet the shell crystal structure's impact on thermal stability and photophysical behavior remains unexplored. It is reported that the ligand-directed synthesis of ZnS shells with zinc blende (ZB) or wurtzite (WZ) structure on blue WZ CdZnS cores, where sulfur precursor (Trioctylphosphine-S/octanethiol) dictates crystal phase through their thermal stability and coordination effects. WZ ZnS exhibits a lower Cd<sup>2</sup>⁺ diffusion barrier than ZB ZnS due to reduced cation density in octahedral vacancies, lowering electrostatic repulsion. Consequently, ZB-shell QDs maintain sharp core-shell boundary and energy band alignment, improving anti-thermal quenching and structural stability: fluorescence decreased by only 8% versus 17% for WZ-shell QDs with increasing temperature from 200 to 300 K, and retained 81% fluorescence intensity (vs. 36%) after 15 days at 100 °C. The rigid ZB lattice also weakens exciton-phonon coupling (simulated γLO = 39 meV vs. 67 meV for WZ). Conversely, WZ-shell QDs form alloyed interfaces enabling smooth energy band alignment, enhancing carrier delocalization. This suppresses Auger recombination, yielding a biexciton lifetime of 126 ps—nearly double that of ZB-shell QDs (69 ps)—and slower decay kinetics (τ<sub>av</sub> = 16.7 ns vs. 55 ns).</p>}},
  author       = {{Wang, Junfeng and Chen, Qing and Huang, Fei and Meng, Jie and Li, Jiawei and Lan, Zhenyun and Zheng, Qian and Tian, Shuyu and Zheng, Kaibo and Pullerits, Tönu and Tian, Jianjun}},
  issn         = {{2195-1071}},
  keywords     = {{blue quantum dot; carrier dynamics; core-shell interface; ligand directed-phase control; thermal stability}},
  language     = {{eng}},
  publisher    = {{John Wiley & Sons Inc.}},
  series       = {{Advanced Optical Materials}},
  title        = {{Impact of Shell Crystal Structure on the Thermal Stability and Photophysical Behavior of Blue Quantum dots}},
  url          = {{http://dx.doi.org/10.1002/adom.202502247}},
  doi          = {{10.1002/adom.202502247}},
  year         = {{2025}},
}