High Stability and Strong Luminescence CsPbBr₃/Cs₄PbBr₆ Perovskite Nanocomposite: Large‐Scale Synthesis, Reversible Luminescence, and Anti‐Counterfeiting Application

Abstract

that requires a relatively high temperature, as Kovalenko and co-workers reported, [7] which works only at the laboratory scale but does not apply to scale-up production. Second, because of their inherent ionic nature, IPQDs suffer from low chemical stability, resulting in fast degradation when exposed to moisture, heat, and light irradiance. Last, the PLQY of IPQDs drops sharply when perovskites are extracted from the crude solution to form a condensed solid. This is due to the rapid desorption of the ligands loosely coordinated with the material surface, [8] which accelerates ion migration between inter-particles, increases non-radioactive Auger recombination, and fluorescence quenching. [9][10][11] In short, finding a facile approach to obtain solid CsPbX 3 QDs with high stability and PLQY still requires significant effort.Various strategies have been applied to enhance the structural stability of QDs using the appropriate surface passivation or encapsulate technology. For example, the stabilities of the CsPbBr 3 QDs have been improved by coating them into inert shells (CsBr, [1] Cs 4 PbBr 6 , [12][13][14][15] CdS, [16] and ZnS [17] ), mesoporous materials (silica molecular sieve, [18] mesoporous silica, [19,20] and metal-organic frameworks [21,22] ), inorganic oxides (Al 2 O 3 , [23,24] SiO 2 , [25,26] Al 2 O 3 /SiO 2 , [27] TiO 2 , [28] and ZrO 2 [29] ), and polymer matrixes (polystyrene, [30] polymethyl methacrylate, [31] polyvinylidene fluoride, [32] and thermoplastic polyurethane [33] ). However, these methods require elaborate processes and show the attenuated PLQY. Conversely, recent studies prove that the 0-D cousins (Cs 4 PbBr 6 ) of CsPbBr 3 possess high PLQY and good stability, [34,35] which inspires us to design a CsPbBr 3 /Cs 4 PbBr 6 heterostructure. [12][13][14][15] Meanwhile, using the wide-band-gap Cs 4 PbBr 6 matrix to coat the CsPbBr 3 QDs, more carriers can be easily confined to the CsPbBr 3 region, reducing the probability of electron leakage [16] and improving the optical-electrical properties. Finally, room temperature supersaturation method is very efficient in the synthesis of perovskite.In this paper, we propose a facile low-temperature selfassembly strategy to synthesize the CsPbBr 3 /Cs 4 PbBr 6 nanocomposite with a PLQY of 72% and a product yield of 87%. A series of characterization experiments have been carried out to confirm the formation of the CsPbBr 3 /Cs 4 PbBr 6 nanocomposite. Meanwhile, the PL spectra and time-resolved PL decay curves have been collected. We observed that the Cs 4 PbBr 6In this study, a simple low-temperature self-assembly strategy is used to synthesize the CsPbBr 3 /Cs 4 PbBr 6 nanocomposite with a relatively high photoluminescence quantum yield (PLQY, 72%) and product yield (87%). As expected, the nanocomposite exhibits good photoluminescence (PL) performance and stability. Further, 90% of the PLQY is maintained even when heating at 100 °C for 24 h, and almost no emission degradation is observed after storage in ethanol for 10 days. Furthermore, the prepa...

Highly Stable and Photoluminescent CsPbBr3/Cs4PbBr6 Composites for White-Light-Emitting Diodes and Visible Light Communication

“…The strong absorption peak located at about 311 nm is agrees well with previous reports on bulk Cs 4 PbBr 6 powders, further confirming that the isolated octahedral PbBr 6 4- was formed in Cs 4 PbBr 6 [ 37 ]. Another broad absorption at 510 nm differs from previous reports in that the characteristic absorption band of CsPbBr 3 QD is usually located at 505 nm [ 38 ]. This result can explain, to a certain extent, the fact that CsPbBr 3 has been embedded in Cs 4 PbBr 6 , thereby affecting its absorption.…”

Halide Perovskites as Emerging Anti-Counterfeiting Materials Contribute to Smart Flow of Goods

“…As a result, the green emission pattern turned to dark in moisture condition and recovered when water was removed (Figure 5a). Similar hydrochromic mechanism was also reported for CsPbBr 3 /Cs 4 PbBr 6 nanocomposites, which maintained about half of its initial PL intensity after 10 wetting-drying cycles [80]. Cs 3 Cu 2 I 5 as lead-free perovskite-like material was recently exploited for hydrochromism-based encryption and decryption of security tags [81][82][83].…”

Shape-controlled synthesis of one-dimensional cesium lead halide perovskite nanocrystals: methods and advances

“…68,77,78 The mechanism of this transformation is that Cs 4 PbX 6 NCs in nonpolar solvent lose CsX at a nonpolar solvent/water interface owing to good solubility of CsX in water and thus convert into CsPbX 3 NCs. [79][80][81][82][83][84][85] Employing this principle, CsPbBr 3 NWs or NRs can be produced via direct or indirect transformation from Cs 4 PbX 6 NCs. 36,38,41,49,50 Zhang et al first applied this method and prepared ultrathin CsPbBr 3 NWs with a diameter of 2.5 nm and a length of up to 10 mm.…”