品牌商线上销售渠道的防伪模式选择研究

以电商防伪体系建立为研究对象，研究供应链中品牌厂商及平台销售商的防伪投资决策机制。分别针对平台转售模式与代理模式，建立产品品牌商与平台销售商的防伪技术投资决策，得出不同渠道模式下的均衡防伪可信度、均衡防伪投资阈值以及均衡利润，并进行比较分析。研究发现，建立防伪体系时，代理模式下始终存在一个代理费用比例的取值区间，使品牌商和平台利润高于转售模式下的利润；建立防伪溯源机制后品牌商在两种模式下的利润始终要优于未建立防伪体系时的利润，而平台的利润在假货渗透率、质量差异的双重限制下才能高于防伪体系建立之前的利润。研究还表明，在一定条件下选择建立防伪溯源机制可以使供应链总利润提高。     

Rare earth doped double perovskite nanocrystals with controllable emission wavelength and model for high-level anti-counterfeiting

Fluorescent anti-counterfeiting technology has become one of the most commonly used anti-counterfeiting technologies because of its simple preparation, low cost and high safety. However, there are still some key technical problems to be solved in developing multi-mode and polychromatic fluorescent materials for high-level anti-counterfeiting. Herein, Yb³⁺/Er³⁺ codoped Cs₂AgIn_0.99Bi_0.01Cl₆ double perovskite nanocrystals (DPNCs) with dual-mode polychromatic emission were developed. Under the irradiation of 365 nm ultraviolet (UV) light, the DPNCs emitted a bright downshifting (DS) yellow light, which comes from the self-trapping excitons (STEs) recombination. While the DPNCs produced upconversion (UC) green fluorescence under the 980 nm laser excitation, which is attributed to the transitions of ²H_11/2 → ⁴I_15/2 and ⁴S_3/2 → ⁴I_15/2 of Er³⁺ ions. In view of its dual-mode and polychromatic fluorescence characteristics, a high-level anti-counterfeiting based on this fluorescent material is designed. Moreover, the brightness of the anti-counterfeiting pattern based on this material decreases very little after three months. These results indicated that the dual-mode and polychromatic DPNCs reported have potential application in information encryption and identity recognition.     

新型长余辉纳米材料的制备及应用研究进展

长余辉材料是一种储能型发光材料,其可以将吸收的一部分能量储存在陷阱中,在外部刺激下以光的形式缓慢释放出来。近年来,新型的长余辉纳米材料在可控制备方法和独特的光学性能方面取得了的突破,在新型涂料、建筑节能、信息防伪及生物医学等领域中引起了广泛关注。综述了新型长余辉纳米材料的制备方法、光物理性质的调控策略及在不同领域中的应用研究进展,并对下一代长余辉纳米材料的未来研究方向和挑战进行了展望。     

Engineering Orthogonal Upconversion through Selective Excitation in a Single Nanoparticle

Orthogonal upconversion with color-switchable emissions under different excitation conditions provides new chances to diverse frontier applications of luminescent materials. However, the previous orthogonal upconversion systems compulsorily require the precise control of spatial distributions of dopants and host compositions to avoid spectral cross-talk, greatly limiting their synthesis and application. Herein, a conceptual design is presented to realize the orthogonal upconversion by selectively activating sensitizers and activators in nanostructure. In detail, the 915 nm laser, instead of the mostly used 980 nm, is adopted to activate the sensitizer Yb³⁺ because of the broad ²F_5/2←²F_7/2 absorption band; while it is non-responsive to Er³⁺, consequently avoiding the spectral cross-talk due to the simultaneous activation of both Er³⁺ and Yb³⁺ under 980 nm irradiation as shown in the previous works. Such a selective excitation strategy is able to realize the red/green, blue/red, and blue/green orthogonal upconversion in a single nanoparticle by simply altering the excitation wavelength from 915 to 1530 nm. More interestingly, it further allows for full-color output by temporal control of the upconversion dynamics. The findings suggest a facile but effective approach to the design of smart luminescent materials, showing great potential in multi-level anti-counterfeiting, information security and biological applications.     

Chiroptical Nanocellulose Bio-Labels for Independent Multi-Channel Optical Encryption

Advanced multiplexing optical labels with multiple information channels provide a powerful strategy for large-capacity and high-security information encryption. However, current optical labels face challenges of difficulty to realize independent multi-channel encryption, cumbersome design, and environmental pollution. Herein, multiplexing chiroptical bio-labels integrating with multiple optical elements, including structural color, photoluminescence (PL), circular polarized light activity, humidity-responsible color, and micro/nano physical patterns, are constructed in complex design based on host-guest self-assembly of cellulose nanocrystals and bio-gold nanoclusters. The thin nanocellulose labels exhibit tunable circular polarized structural color crossover the entire visible wavelength and circularly polarized PL with the highest-recorded dissymmetry factor up to 1.05 due to the well-ordered chiral organization of templated gold nanoclusters. Most importantly, these elements can independently encode customized anti-counterfeiting information to achieve five independent channels of high-level anti-counterfeiting, which are rarely achieved in traditional materials and design counterparts. Considering the exceptional seamless integration of five independent encryption channels and the recyclable features of labels, the bio-labels have great potential for the next generation anti-counterfeiting materials technology.     

Hydrochromic Perovskite System with Reversible Blue-Green Color for Advanced Anti-Counterfeiting

The intrinsic instability of halide perovskites toward to external stimulus, has created a competitive advantage for designing stimuli-responsive materials. However, the external environment tuning reversibly fluorescence emission of perovskite system is still limited. In this work, humidity is verified to act as a new option to modulate the emission properties of mixed-halide perovskite. The perovskite nanocrystals (PNCs) photoirradiated in dichloromethane are easily and stably redispersed in water, and emit bright fluorescence which is quite different from the original. Moreover, the perovskites confined on glass slide can reversibly switch their fluorescence between blue and green colors under moisture. It is demonstrated that the factors of different solubilities of CsCl and CsBr in water, the structural transformation of perovskites and the confine of glass matrix play key roles in the reversible transformation. Finally, the combination of hydrochromic CsPb(Br_xCl_y)₃ and water-resistant CsPb(Br_xCl_y)₃-polymethyl methacrylate have been applied in advanced anti-counterfeiting, which greatly improves the information security. This work not only give an insight into the effects of humidity on fluorescence and structures of PNCs, but also offer a new class of hydrochromic PNCs materials based on reversible emission transformation for potential application in sensors, anti-counterfeiting and information encryption.     

Long-Lived Dynamic Room Temperature Phosphorescence from Carbon Dots Based Materials

As a type of room temperature phosphorescence (RTP) material, carbon dots (CDs) always show short lifetime and low phosphorescence efficiency. To counter these disadvantages, several strategies, such as embedding in rigid matrix, introducing of heteroatom, crosslink-enhanced emission, etc., are well developed. Consequently, lots of CDs-based RTP materials are obtained. Doping of CDs into various matrix is the dominant method for preparation of long-lived CDs-based RTP materials so far. The desired CDs@matrix composites always display outstanding RTP performances. Meanwhile, matrix-free CDs and carbonized polymer dots-based RTP materials are also widely developed. Amounts of CDs possessing ultra-long lived, multiple colored, and dynamic RTP emission are successfully obtained. Herein, the recent progress achieved in CDs-based RTP materials as well as the corresponding efficient strategies and emission mechanisms are summarized and reviewed in detail. Due to CDs-based RTP materials possess excellent chemical stability, photostability and low biological toxicity, they exhibit great application potential in the fields of anti-counterfeiting, data encryption, and biological monitoring. The application of the CDs-based RTP materials is also introduced in this review. As a promising functional material, development of long wavelength RTP emitting CDs with long lifetime is still challengeable, especially for the red and near-infrared emitting RTP materials.     

水溶性碳量子点的制备及防伪应用

以壳聚糖为原料,采用水热法一步制备水溶性的荧光碳量子点（CQDs）,考察反应条件（壳聚糖质量浓度、温度和时间）对CQDs产物表面官能团和产率的影响,采用TEM、FTIR、XRD、UV-Vis和PL等技术对其形貌、结构和性能进行了表征,并探究其在防伪领域的应用。结果表明,当壳聚糖质量浓度为10 g/L,温度为180 ℃,时间为12 h时,制得的CQDs结构完整且产率较高;微观表现为球状纳米颗粒,直径约为36.2 nm,表面伴有羟基和氨基官能团;制得的CQDs在293和330 nm处均有吸收峰,表现为蓝色荧光,荧光量子产率约为39.8%。将其配制成墨水后,结合喷墨印刷,在自然光和紫外光下可有效实现加密信息的“显”和“隐”,具有较好的防伪效果。