Fluorescent Carbon‐ and Oxygen‐Doped Hexagonal Boron Nitride Powders as Printing Ink for Anticounterfeit Applications

Abstract

Increasing demands for optical anticounterfeiting technology require the development of versatile luminescent materials with tunable photoluminescence properties. Herein, a number of fluorescent carbon‐ and oxygen‐doped hexagonal boron nitride (denoted as BCNO) phosphors are found to offer a such high‐tech anticounterfeiting solution. These multicolor BCNO powders, developed in a two‐step process with controlled annealing and oxidation, feature rod‐like particle shape, with varied luminescence properties. Studies of the optical properties of BCNO, along with other characterization, provide insight into this underexplored material. Anticounterfeiting applications are demonstrated with printed patterns which are indistinguishable to the naked eye under visible light but become highly discernible under UV irradiation. The fabricated patterns are demonstrated to be both chemically stable in corrosive environments and physically robust in mechanical bending testing. These properties render BCNO as promising and versatile anticounterfeiting material a wide variety of environments.

Few-Layered Boron Nitride Nanosheets for Strengthening Polyurethane Hydrogels

“…The HRTEM image (Figure b) reveals that the interlayer lattice spacing is 0.34 nm, corresponding to the 25.7 degree peak in the XRD pattern. This spacing is slightly larger than the 0.33 nm for the (002) plane of crystalline h-BN, which is due to relatively poor crystallization caused by the short dwelling time . The ED pattern is in agreement with the XRD patterns (Figure c).…”

Highly Luminescent Copper Iodide Cluster Based Inks with Photoluminescence Quantum Efficiency Exceeding 98%

“…Currently, various luminescent inks have been prepared by using carbon dots, − rare-earth-doped compounds, , inorganic semiconductor complexes, and organic dyes . However, the luminescent inks based on rare-earth elements and heavy metals are subjected to high cost and potential environmental issues, while those based on carbon dots with excellent biocompatibility suffer from photo bleaching behavior and low photoluminescence quantum efficiency (PLQE), which severely limit their practical applications. ,, Moreover, tedious synthesis processes of most luminescent components hinder their practical applications and lead to some difficulties in large-scale fabrication . These bring about a necessity to develop a cost-effective, environmental-friendly, easily scalable, and strong emissive luminescent ink.…”

Luminescence anti‐counterfeiting: From elementary to advanced

“…Recently, more and more materials with different luminescence modes have been applied into single‐level luminescence anti‐counterfeiting to improve the ability of single‐level luminescence anti‐counterfeiting and increase the difficulty of forgery. [ 19–34 ] According to the difference of luminescence modes, the single‐level luminescence anti‐counterfeiting can be divided into down‐conversion (DC) photoluminescence anti‐counterfeiting, [ 19,21–27,29,31 ] up‐conversion (UC) photoluminescence anti‐counterfeiting, [ 20,28,30,32,34 ] and chemiluminescence anti‐counterfeiting. [ 33 ]…”

“…DC photoluminescence anti‐counterfeiting is realized by absorbing one high‐energy photon and releasing one low‐energy photon. [ 35 ] At present, the materials used in single‐level DC photoluminescence anti‐counterfeiting include organic luminogens, [ 19 ] graphene quantum dots, [ 21 ] Ln‐carbon quantum dots, [ 22 ] cellulose nanofibrils/CdTe quantum dots, [ 23 ] carbon and oxygen co‐doped hexagonal boron nitride, [ 24 ] nitrogen‐doped carbon dots, [ 25 ] carbon dots/Ln‐MOFs hybrids, [ 26 ] Ln‐metal organic frameworks (Ln‐MOFs), [ 29 ] Tb 3+ /Eu 3+ ‐grafted melamine cyanurate, [ 31 ] and SrAl 2 O 4 :Eu 2+[ 36 ] . As shown in Figure 2A, Gao et al.…”