Hydrochromic CsPbBr3 Nanocrystals for Anti-Counterfeiting
Xiaoya Yu,# Linzhong Wu,# Di Yang,# Muhan Cao,* Xing Fan, Haiping Lin, Qixuan Zhong, Yong Xu, and Qiao Zhang*
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, SWC for Synchrotron Radiation Research, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, People’s Republic of China
Hydrochromic materials that can reversibly change color upon water treatment have attracted much attention due to their potential applications in diverse fields. Here, 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 nonluminescent 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. Due 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.