All-inorganic perovskites for four-dimensional dynamic encryption

In an era marked by increasing demand for advanced anticounterfeiting measures, we introduce a four-dimensional (4D) dynamic physical unclonable function that uses defect-engineered photoluminescence blinking in all-inorganic CsPbBr₃ perovskite quantum dots (QDs) embedded within a polymethylmethacrylate matrix. Even within a single z-axis layer, this system achieves an unprecedented theoretical encoding capacity of more than 10^216,742, while each device can generate up to 25 billion distinct codes. The QDs exhibit stochastic transitions between emissive and nonemissive states, enabling binary encoding across both spatial and temporal dimensions. The mechanism reveals that surface lead interstitials predominantly mediate nonradiative Auger recombination, whereas cesium vacancies act as effective Shockley-Read-Hall recombination centers, jointly governing the blinking of CsPbBr₃. Alkali metal doping modulates this blinking behavior, providing precise control over the emission dynamics. Practical utility is demonstrated through a dual-mode authentication strategy that enables rapid field verification via standard smartphones while retaining high-security 4D verification via microscopy. We further establish a spatial-temporal dual-model authentication framework that integrates convolutional neural network (CNN)-based spatial matching with a temporal-branch dynamic check and decision-fusion assessment. The framework resists 14 adversarial attacks spanning replay, impersonation, temporal and local manipulation, Z-stack modification, projection forgery, and synthetic forgery attack, showing robust sequence-level security beyond frame-level CNN recognition. This work transforms what was once considered a detrimental phenomenon-QD blinking-into a valuable asset for dynamic, high-capacity encryption, opening new avenues for ultrasecure cryptographic systems.