Abstract

Phonon-assisted up-conversion photoluminescence can boost energy of an emission photon to be higher than that of the excitation photon by absorbing vibration energy (or phonons) of the emitter. Here, up-conversion photoluminescence power-conversion efficiency (power ratio between the emission and excitation photons) for CdSe/CdS core/shell quantum dots is observed to be beyond unity. Instead of commonly known defect-assisted up-conversion photoluminescence for colloidal quantum dots, temperature-dependent measurements and single-dot spectroscopy reveal the up-conversion photoluminescence and conventional down-conversion photoluminescence share the same electron-phonon coupled electronic states. Ultrafast spectroscopy results imply the thermalized excitons for up-conversion photoluminescence form within 200 fs, which is 100,000 times faster than the radiative recombination rate of the exciton. Results suggest that colloidal quantum dots can be exploited as efficient, stable, and cost-effective emitters for up-conversion photoluminescence in various applications.

Up-conversion photoluminescence in colloidal quantum dots is generally believed to be mediated by thermal activation from defect states. Here, the authors reveal that highly-efficient up-conversion photoluminescence instead is related to electron-phonon coupling.

Details

Title
Phonon-assisted up-conversion photoluminescence of quantum dots
Author
Ye Zikang 1   VIAFID ORCID Logo  ; Lin, Xing 2   VIAFID ORCID Logo  ; Wang, Na 1 ; Zhou Jianhai 3 ; Zhu Meiyi 1 ; Qin Haiyan 1   VIAFID ORCID Logo  ; Peng Xiaogang 1   VIAFID ORCID Logo 

1  Zhejiang University, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Hangzhou, China (GRID:grid.13402.34) (ISNI:0000 0004 1759 700X) 
2  Zhejiang University, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Hangzhou, China (GRID:grid.13402.34) (ISNI:0000 0004 1759 700X); Zhejiang University, College of Information Science and Electronic Engineering, Hangzhou, China (GRID:grid.13402.34) (ISNI:0000 0004 1759 700X) 
3  Najing Technology Corporation LTD, Hangzhou, China (GRID:grid.13402.34) 
Publication year
2021
Publication date
2021
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1038/s41467-021-24560-4
ProQuest document ID
2550943953
Copyright
© The Author(s) 2021. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.