|
|||||
|
|
Significant Enhancement of the Upconversion Emission in Highly Er3+-Doped Nanoparticles at Cryogenic Temperatures |
|
| Authors: | Dr Langping Tu Kefan Wu Prof Yongshi Luo Enhui Wang Jun Yuan Dr Jing Zuo Prof Ding Zhou Prof Bin Li Prof Jiajia Zhou Prof Dayong Jin Prof Hong Zhang |
| Institution: | 1. State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin, 130033 China;2. Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam, 1098XH The Netherlands;3. Key Laboratory of Automobile Materials (Ministry of Education), College of Materials Science and Engineering, Jilin University, Changchun, 130025 China;4. Institute for Biomedical Materials and Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW Australia |
| Abstract: | Relatively low efficiency is the bottleneck for the application of lanthanide-doped upconversion nanoparticles (UCNPs). The high-level doping strategy realized in recent years has not improved the efficiency as much as expected. It is argued that cross relaxation (CR) is not detrimental to upconversion. Here we combine theoretical simulation and spectroscopy to elucidate the role of CR in upconversion process of Er3+ highly doped (HD) UCNPs. It is found that if CR is purposively suppressed, upconversion efficiency can be significantly improved. Specifically, we demonstrate experimentally that inhibition of CR by introducing cryogenic environment (40 K) enhances upconversion emission by more than two orders of magnitude. This work not only elucidates the nature of CR and its non-negligible adverse effects, but also provides a new perspective for improving upconversion efficiency. The result can be directly applied to cryogenic imaging and wide range temperature sensing. |
| Keywords: | Cross Relaxation High-Level Doping Monte Carlo Simulations Temperature Upconversion Nanoparticle |