A sandwiched luminescent heterostructure based on lanthanide‐doped Gd₂O₂S@NaYF₄ core/shell nanocrystals

Abstract

Lanthanide (Ln3+) oxysulfide nanocrystals (NCs) have great prospect in many advanced technologies; however, they suffer from a low photoluminescence efficiency due to the volatility of sulfur and deleterious surface quenching effect. Herein, we report a novel sandwiched luminescent heterostructure based on Ln3+‐doped Gd2O2S@NaYF4 core/shell NCs with tunable sulfur content in the sandwich layer. By means of Eu3+ as the sensitive structural probes, we unravel the ligand‐mediated structure control of the NCs from Gd2O3: Ln3+@NaYF4 to Gd2O2S: Ln3+@NaYF4 with tailored S2– deficiency. Such a sandwich‐type core/shell heterostructure enables us to achieve efficient and multicolor downshifting and upconversion luminescence (UCL), with up to 208.8 folds of enhancement in UCL intensity as compared to that of their core‐only counterparts. These findings provide a general approach for the controlled synthesis of lanthanide oxysulfide@fluoride heterostructure, which offers a new way for the materials design towards diverse emerging applications.

Photophysics and its application in photon upconversion

“…In principle, the upconversion mechanisms involving lanthanides can be mainly categorized into five classes: excited-state absorption, energy transfer upconversion, cooperative upconversion and photon avalanche. 19,[64][65][66][67][68] Here, we focus on the mechanisms of energy transfer upconversion. Fluorescence upconversion of lanthanides (e.g., Er 3+ , Tm 3+ , and Ho 3+ ) is usually realized via ETU, 19,20 where long-lived intermediate states exist to store energy (Fig.…”

Preparation of rare earth-doped nano-fluorescent materials in the second near-infrared region and their application in biological imaging

“…However, at the nanoscale, their application is greatly limited due to the volatility of sulfur and harmful surface quenching. Qilin Zou et al 64 and Dengfeng Yang et al 65 epitaxially grew a layer of inert NaYF 4 shell on the surface of Gd 2 O 2 S NPs (Fig. 4b).…”

Understanding of Lanthanide-Doped Core–Shell Structure at the Nanoscale Level

“…Zhang et al reported a multilayered core-shell nanostructure, NaGdF 4 : Yb/Tm/Er@NaGdF 4 : Eu@NaYF 4 , which emits emission covering the entire visible range and can be combined to produce white light by optimizing the photon leap paths of specific lanthanide ions [92]. Yang and his research team proposed an innovative rare-earth sulfide/fluoride heterostructure design, which achieves efficient multicolor upconversion and downshift luminescence of rare-earth ions at a single excitation wavelength by skillfully doping different kinds of rare-earth ions [93].…”