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Tönu Pullerits. Portrait.

Tönu Pullerits

Professor

Tönu Pullerits. Portrait.

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

Author

  • Junfeng Wang
  • Qing Chen
  • Fei Huang
  • Jie Meng
  • Jiawei Li
  • Zhenyun Lan
  • Qian Zheng
  • Shuyu Tian
  • Kaibo Zheng
  • Tönu Pullerits
  • Jianjun Tian
Show all

Summary, in English

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).

Department/s

  • Chemical Physics
  • NanoLund: Centre for Nanoscience

Publishing year

2025

Language

English

Publication/Series

Advanced Optical Materials

Document type

Journal article

Publisher

John Wiley & Sons Inc.

Topic

  • Materials Chemistry

Keywords

  • blue quantum dot
  • carrier dynamics
  • core-shell interface
  • ligand directed-phase control
  • thermal stability

Status

Epub

ISBN/ISSN/Other

  • ISSN: 2195-1071