Unique excitation power density and pulse width-dependent multicolor upconversion emissions of Y₂Mo₄O₁₅:Yb³⁺,Ho³⁺ for anti-counterfeiting and information encryption applications

Abstract

Developing smart upconversion materials with novel optical properties is of great significance for applications such as anti-counterfeiting and information encryption, which is always the research frontier and hotspot in this...

Research Progress of Rare Earth Doped Upconversion Luminescent Materials

“…TEM images of NaGdF 4 ∶Yb, Tm@NaGdF 4 ∶Tb core-shell nanocrystals prepared by adding 50 (d) and 25 (e) mg of 15 nm core particles. Using core-shell nanocrystals in [(d), (e)] as seeds and Gd(CH 3 CO 2 ) 3 stock solution as the shell precursor, NaGdF 4 ∶ Yb, Tm@NaGdF 4 ∶ Tb@NaGdF 4 core-shell-shell nanocrystals were prepared according to the inner shell coating process, and the TEM images are (f) and (g) (scale bar: 50 nm) [73] 工程研究--跨学科视野中的工程, 16( 2 同厚度的猪肉组织得到的信号也偏弱(图 8) [90] 。 2012 年 ， Gu 等 [91] 开 发 了 另 一 种 Mn 2+ 掺 杂 的 [74] Figure 7 SLBL synthetic procedure for the Core/Shell UCNPs [74] 别。此外，稀土离子的下转换发光是斯托克斯位移发 光，理论上应具有比上转换发光更高的发光效率。图 9 展示了在近红外二区窗口中归一化后的稀土离子的 发射峰 [92] 。其中 Tm 3+ ，Er 3+ 离子均具有较长的发射波 长，以这两种离子为下转换激活剂的纳米颗粒也已被 广泛报道。 2017 年，Zhong 等 [93] 报道了一种应用于下转换成 像的纳米颗粒：NaYbF 4 ∶Er, Ce@NaYF 4 ，其包覆惰 性核壳的目的是降低水分子对发光的猝灭。如图 11 (a)所示 [94] μl of 2.0 mg/ml PEG-UCNPs [91] 图 10 晶体基质中 Sm 3+ 、Yb 3+ 、Nd 3+ 、Ho 3+ 、Tm 3+ 、Pr 3+ 、Dy 3+ 、Er 3+ 等镧系离子的近红外发光光谱 [92] Figure 10 NIR luminescence spectra of lanthanide ions including Sm 3+ , Yb 3+ , Nd 3+ , Ho 3+ , Tm 3+ , Pr 3+ , Dy 3+ , and Er 3+ in crystals hosts [92] 现了对小鼠脑部的多路复合成像。 相比于更长波长的下转换发光，上转换发光波长 短，穿透性差，但上转换发光的能量更高，是触发光 敏剂实现光动力治疗(photodynamic therapy，PDT)的 理想光源 [96][97][98][99][100] 。将上转换发光和下转换发光通过核 壳结构集成在一起有利于更加精准的光动力治疗。 Zhao 等 [101] 报道了一种通过下转换发光引导的光动力 治疗方案。他们首先合成了一种核-4 层壳结构的纳米 颗粒(CSNPs) ，NaGdF 4 ∶Yb, Tm@NaGdF 4 @NaYbF 4 ∶ Nd@NaGdF 4 ∶Yb, Er, Ce@NaGdF 4 (图 13)。其中上转 [94] 效果，从而推动其临床应用。 2.2 信息存储和防伪应用 稀土元素因其丰富的能级而能够发出绚丽多彩的 光芒，这些不同颜色的发光可以在不同的条件下被触 发，用于信息存储或防伪 [102][103][104][105][106][107][108][109][110] 。近期，Li 等 [111] [95] 合编码也可以获得高等级的防伪效果。如 Lu 等 [113] 心 [119]<...…”

Multimode Dynamic Photoluminescence of Bi3+-Activated ZnGa2O4 for Optical Information Encryption

“…Information security is of great significance in the development of enterprises, social stability, military security, and even personal daily life. − Over the past few decades, a wide variety of technologies, including markering, holograms, magnetism, plasmonic labels, and luminescence, have been investigated for use in anticounterfeiting and information encryption. Among these technologies, luminescence has demonstrated great potential because of its timeliness, simplicity, multiencoding dimensions, and low cost. − So far, diverse luminescent materials featuring photoluminescence (PL), thermoluminescence (TL), upconversion luminescence (UCL), downconversion luminescence (DCL), persistent luminescence (PersL), mechanoluminescence (ML), and photostimulated luminescence (PSL) have been widely developed for high-level encryption. − However, most PL-based anticounterfeiting labels are easily falsified by certain alternatives due to their static luminescence color and intensity, single-emission mode, or simple design . Therefore, dynamic optical materials with multimode luminescence characteristics are highly desired for advanced anticounterfeiting and information encryption applications. − …”

Excitation-Controlled Host–Guest Multicolor Luminescence in Lanthanide-Doped Calcium Zirconate for Information Encryption

“…Although incorporating excitationdependent upconversion has proven to be a robust method, it is obvious that the elaborate construction of a material structure is often necessary in order to prevent cross-relaxationinduced loss of excitation energy, and that excitation lasers of limited wavelengths, such as 808, 980, and 1532 nm, can be selected for upconversion luminescence. In addition, in upconversion-only luminescent systems, modulating the pulse duration or repetition frequency of the excitation laser can tailor the luminescent color efficiently and almost continuously [17,18], but this method undoubtedly relies on a complex excitation light source system.…”