Three‐Dimensional Laser Writing Aligned Perovskite Quantum Dots in Glass for Polarization‐Sensitive Anti‐Counterfeiting

Abstract The pursuit of high‐resolution and advanced anti‐forgery technology has stimulated a growing demand for anti‐counterfeiting and encryption strategies with real‐time response and high security. Polarized patterns taking the advantage of high security, rapid response, simple operation, and great selectivity enable real‐time and non‐invasive detection by monitoring in different polarization directions. Here, a new strategy to design and fabricate the polarized CsPbBr 3 quantum dot (QD) line arrays by femtosecond (fs) laser writing in a transparent glass matrix is proposed. The obtained line array structures endow isotropic CsPbBr 3 QDs with macroscopic polarized emission with a polarization degree up to 0.189. Through programable design, the authors have created 2D and 3D polarized luminescent patterns made up of vertical and horizontal lines inside the glass for polarization‐sensitive optical anti‐counterfeiting patterns. The CsPbBr 3 QD line arrays used in anti‐counterfeiting can be well maintained in the water environment. The successful demonstration of the laser writing CsPbBr 3 QD polarization structures in glass highlights the versatility of anti‐counterfeiting and encryption.