Affiliation:
1. Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers and iChem Fudan University Shanghai China
2. Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Guangdong‐Hong Kong‐Macau Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Division of Life Science, and State Key Laboratory of Molecular Neuroscience The Hong Kong University of Science and Technology Kowloon Hong Kong China
Abstract
AbstractRecently, lanthanide (Ln) luminescent nanocrystals have attracted increasing attention in various fields such as biomedical imaging, lasers, and anticounterfeiting. However, due to the forbidden 4f–4f transition of lanthanide ions, the absorption cross‐section and luminescence brightness of lanthanide nanocrystals are limited. To address the challenge, we constructed an optical oscillator‐like system to repeatedly simulate lanthanide nanocrystals to enhance the absorption efficiency of lanthanide ions on excitation photons. In this optical system, the upconversion luminescence (UCL) of Tm3+ emission of ~450 nm excited by a 980 nm laser can be amplified by a factor beyond 104. The corresponding downshifting luminescence of Tm3+ at 1460 nm was enhanced by three orders of magnitude. We also demonstrated that the significant luminescence enhancement in the designed optical oscillator‐like system was general for various lanthanide nanocrystals including NaYF4:Yb3+/Ln3+, NaErF4@NaYF4 and NaYF4:Yb3+/Ln3+@NaYF4:Yb3+@NaYF4 (Ln = Er, Tm, Ho) regardless of the wavelengths of excitation sources (808 and 980 nm). The mechanism study revealed that both elevated laser power in the optical system and multiple excitations on lanthanide nanocrystals were the main reason for the luminescence amplification. Our findings may benefit the future development of low‐threshold upconversion and downshifting luminescence of lanthanide nanocrystals and expand their applications.
Funder
National Natural Science Foundation of China
Science and Technology Commission of Shanghai Municipality
Subject
Chemistry (miscellaneous),Biophysics