title: Markedly enhanced up-conversion luminescence by combining IR-808 dye sensitization and core-shell-shell structures.
abstract: Rare-earth-doped up-conversion nanoparticles (UCNPs), which are capable of converting infrared light to shorter-wavelength photons, have attracted worldwide attention due to their unique characteristics. However, the emission brightness of UCNPs is greatly limited by the unsatisfactory absorptivity of lanthanide ions. Herein, we adopted a novel strategy to enhance the up-conversion intensity using NIR dye IR-808 as an antenna to sensitize the core-shell-shell structured NaGdF4:Yb,Er@NaGdF4:Yb@NaNdF4:Yb UCNPs. When excited with 808 nm light, the IR-808 emitted a broadband peak, which perfectly overlapped with the absorption of Nd3+and Yb3+ions. Thus, the active shell of NaNdF4:Yb can efficiently capture the emitted NIR photons and transfer them to the transition layer of NaGdF4:Yb. The transition layer acted as an energy bridge to connect the active shell and up-converting zone, avoiding the energy back-transfer from the activators to Nd3+ions. The optimized dye sensitization combined with the well-designed core-shell-shell structure tremendously enhances the NIR photon absorptivity of UCNPs and eliminates the deleterious cross-relaxation between the activators and sensitizers, eventually leading to dramatic enhancement of the up-conversion intensity. This study provides a new insight into the dye-sensitized up-conversion luminescence of rare earth-based nanoparticles and facilitates their practical applications.
authors.affiliation: Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China. yangpiaoping@hrbeu.edu.cn gaishili@hrbeu.edu.cn.
authors.forename: Jiating
authors.initials: J
authors.lastname: Xu
authors.affiliation: Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China. yangpiaoping@hrbeu.edu.cn gaishili@hrbeu.edu.cn.
authors.forename: Mingdi
authors.initials: M
authors.lastname: Sun
authors.affiliation: Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China. yangpiaoping@hrbeu.edu.cn gaishili@hrbeu.edu.cn.
authors.forename: Ye
authors.initials: Y
authors.lastname: Kuang
authors.affiliation: Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China. yangpiaoping@hrbeu.edu.cn gaishili@hrbeu.edu.cn.
authors.forename: Huiting
authors.initials: H
authors.lastname: Bi
authors.affiliation: Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China. yangpiaoping@hrbeu.edu.cn gaishili@hrbeu.edu.cn.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.affiliation: Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China. yangpiaoping@hrbeu.edu.cn gaishili@hrbeu.edu.cn.
authors.forename: Dan
authors.initials: D
authors.lastname: Yang
authors.affiliation: Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China. yangpiaoping@hrbeu.edu.cn gaishili@hrbeu.edu.cn.
authors.forename: Ruichan
authors.initials: R
authors.lastname: Lv
authors.affiliation: Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China. yangpiaoping@hrbeu.edu.cn gaishili@hrbeu.edu.cn.
authors.forename: Shili
authors.initials: S
authors.lastname: Gai
authors.affiliation: Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China. yangpiaoping@hrbeu.edu.cn gaishili@hrbeu.edu.cn.
authors.forename: Fei
authors.initials: F
authors.lastname: He
authors.affiliation: Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China. yangpiaoping@hrbeu.edu.cn gaishili@hrbeu.edu.cn.
authors.forename: Piaoping
authors.identifier: http://orcid.org/0000-0002-9555-1803
authors.initials: P
authors.lastname: Yang