Double-Protected All-Inorganic Perovskite Nanocrystals by Crystalline Matrix and Silica for Triple-Modal Anti-Counterfeiting Codes

Abstract

Novel fluorescence with highly covert and reliable features is quite desirable to combat the sophisticated counterfeiters. Herein, we report a simultaneously triple-modal fluorescent characteristic of CsPbBr@CsPbBr/SiO by the excitation of thermal, ultraviolet (UV) and infrared (IR) light for the first time, which can be applied for the multiple modal anti-counterfeiting codes. The diphasic structure CsPbBr@CsPbBr nanocrystals (NCs) was synthesized via the typical reprecipitation method followed by uniformly encapsulation into silica microspheres. Cubic CsPbBr is responsible for the functions of anti-counterfeiting, while CsPbBr crystalline and SiO are mainly to protect unstable CsPbBr NCs from being destroyed by ambient conditions. The as-prepared CsPbBr@CsPbBr/SiO NCs possess improved stability and are capable of forming printable ink with organic binders for patterns. Interestingly, the fluorescence of diphasic CsPbBr@CsPbBr/SiO capsule patterns can be reversibly switched by the heating, UV, and IR light irradiation, which has been applied as triple-modal fluorescent anti-counterfeiting codes. The results demonstrate that the perovskite@silica capsules are highly promising for myriad applications in areas such as fluorescent anti-counterfeiting, optoelectronic devices, medical diagnosis, and biological imaging.

Single‐Solvent, Ligand‐Free, Gram‐Scale Synthesis of Cs4PbBr6 Perovskite Solids with Robust Green Photoluminescence

“…The results indicated that the intensities of PL emission were ever‐decreases with increasing the temperature. This is in accordance with the reported luminescent materials because the nonradiative transition was enhanced at a high temperature . The green emission of Cs 4 PbBr 6 was completely quenched at 175 °C (Figure a).…”

“…To elucidate this, experiments were performed respectively using DMSO and toluene as a substitute for DMF. As shown in Figure S6, Cs 4 PbBr 6 perovskites solids with a bright green luminescence were readily produced if DMSO was used as DMF substitute because of their similar solubility for CsBr and PbBr 2 (Sample 2 in Figure S6) . Whereas, the yellow products composed of Cs 4 PbBr 6 , CsBr and PbBr 2 were obtained after 30 min by toluene, a poor solvent for CsBr and PbBr 2 .…”

Ultrathin, Core–Shell Structured SiO2 Coated Mn2+‐Doped Perovskite Quantum Dots for Bright White Light‐Emitting Diodes

“…Meanwhile, the emission colors under UV excitation were changed from brilliant yellow for uncoated QDs to dark yellow (100 µL), brilliant yellow (200 µL), and dark yellow (300 µL) (Figure S7, Supporting Information). This phenomenon can be explained that SiO 2 could restrain the activated nonradiative deactivation of Mn 2+ and exciton emissions in the CsPbX 3 QDs . The absolute PLQYs of 54.7%, 47.9%, 50.5%, and 33.5% for the pure CsPbMnX 3 , CsPbMnX 3 @SiO 2 (100 µL), CsPbMnX 3 @SiO 2 (200 µL), and CsPbMnX 3 @SiO 2 (300 µL), respectively, are obtained.…”

Zero-Dimensional Cesium Lead Halides: History, Properties, and Challenges

“…30 In addition, another LED based on silica encapsulation of the Cs 4 PbBr 6 -passsivated CsPbBr 3 NCs was also reported. 38 Moreover, several groups have used transmission electron microscopy (TEM) to identify the presence of green luminescent CsPbBr 3 NCs in Cs 4 PbBr 6 microcrystals, as well as in Cs 4 PbBr 6 NC solutions (Figure 2e). 30,31,34,62 …”