Emerging Multi‐Level Anti‐Counterfeiting Strategies Based on Versatile Luminescence of Lead‐Free Halide Perovskites

Abstract Counterfeiting poses a severe global threat to economic security and public safety, driving an urgent demand for advanced anti‐counterfeiting technologies that are difficult to replicate. Lead‐free halide perovskites (LFHPs) have emerged as a promising platform, offering eco‐friendly composition, structural versatility, and highly tunable luminescence. This Review systematically summarizes recent advancements in LFHP‐based anti‐counterfeiting strategies, categorized into single‐level, dual‐level, and multi‐level systems. Unlike conventional approaches, LFHPs enable dynamic encryption through excitation‐dependent emission, up/down‐conversion, near‐infrared luminescence, long‐persistent afterglow, and stimuli‐responsive behaviors (e.g., hydrochromism, thermochromism, and mechanochromism). Multi‐level strategies are particularly highlighted that integrate time‐resolved and stimulus‐activated features, significantly enhancing security and information capacity. Despite rapid progress, challenges remain in scalability, environmental stability, and cost‐effective fabrication. This Review not only elucidates the structure–property relationships and underlying mechanisms of LFHPs but also provides a forward‐looking perspective on their practical application potential. Material design principles, performance limitations, and future directions are outlined, such as the development of multi‐modal responsive systems and integration with scalable printing technologies. By addressing these aspects, this Review aims to guide the rational design of next‐generation, high‐security anti‐counterfeiting materials and promote their adoption in next‐generation security systems.