Hydrochromic CsPbBr₃ Nanocrystals for Anti‐Counterfeiting

Abstract

Hydrochromic materials that can reversibly change color upon water treatment have attracted much attention owing to their potential applications in diverse fields. Herein, for the first time, we report that space‐confined CsPbBr3 nanocrystals (NCs) are hydrochromic. When CsPbBr3 NCs are loaded into a porous matrix, reversible transition between luminescent CsPbBr3 and non‐luminescent CsPb2Br5 can be achieved upon the exposure/removal of water. The potential applications of hydrochromic CsPbBr3 NCs in anti‐counterfeiting are demonstrated by using CsPbBr3 NCs@mesoporous silica nanospheres (around 100 nm) as the starting material. Owing to the small particle size and negatively charged surface, the as‐prepared particles can be laser‐jet printed with high precision and high speed. We demonstrate the excellent stability over repeated transformation cycles without color fade. This new discovery may not only deepen the understanding of CsPbX3, but also open a new way to design CsPbX3 materials for new applications.

In situpassivation of Pb0traps by fluoride acid-based ionic liquids enables enhanced emission and stability of CsPbBr3nanocrystals for efficient white light-emitting diodes

“…1c show an excitonic peak in the range of 500–510 nm, which is consistent with previous results. 30 The absorption and emission peaks of NCs exhibit a red-shift tendency with the increase of the n [Bmim]BF 4 / n Pb ratio, which can be attributed to the increase of the particle size. The emission intensity of CsPbBr 3 NCs gradually increases with the increase of the n [Bmim]BF 4 / n Pb ratio from 0 to 0.12 (Fig.…”

Instant interfacial self-assembly for homogeneous nanoparticle monolayer enabled conformal “lift-on” thin film technology

“…The conformal functional optical patterning holds promises for various applications, such as soft electronics, solar cells, and anti-counterfeiting security labels ( 49 ) . However, the traditional printing technologies often suffer high cost, limited pattern area, low universality, low efficiency in integrating the fluorescent/optical indicator layer, and low throughput in mass production ( 50 ).…”

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

“…As we mentioned in Section 2.3.2, hybrid perovskites feature hydrochromism due to the formation of hydrated or non-perovskite phases in moisture atmosphere [70,72]. Reversibly decomposition-induced hydrochromism was recently reported for CsPbBr 3 NCs confined in mesoporous silica nanospheres (MSNs) [78]. Orthorhombic CsPbBr 3 will decompose into nonluminescent tetragonal CsPb 2 Br 5 and CsBr in the presence of water, and the dissolved CsBr component can be confined in MSNs.…”