**1. Introduction**

The booming global businesses have largely facilitated the cross-border flow of goods, but meanwhile are threatened by the dramatically increased intellectual property (IP) crimes nowadays. According to the study by Organization for Economic Cooperation and Development (OECD), the value of counterfeit and pirated products is amounted to USD 464 billion in 2019, equal to 2.5% of world trade and more than half of the total value is carried by containerships between countries [1, 2]. The illicit trade hits company profits and nation tax revenue and endangers public health when pharmaceuticals and medical equipment are involved. For these reasons, advanced technologies that combat fake products demand prompt development to ensure reliable flow of goods while maintain its convenience.

Anti-counterfeiting idea was early raised by Philadelphia printer Benjamin Franklin in the 1700s [3], at that time colonies in North America were troubled by the circulation of counterfeit bills. Franklin deliberately misspelled Pennsylvania in the printed bills to baffle less-literate criminals. Meanwhile, he engraved the fine detail of copper on the leaf vein at the back of each bill, making these bills hard to be reproduced by counterfeiters. The unique copper engraving created by blocky lead printer has been regarded as a prototype for contemporary anti-counterfeiting patterning technologies. Since the 1950s, the development of holograms [4–7], ink printing [8–11], and exquisite laser engraving [12–14] have offered practical solutions to protect the market from malicious third parties.

Halide perovskites as an emerging family of semiconductor materials have achieved notable success in photovoltaics and other optoelectronics over the past decade [15–20]. The intriguing photophysical property of perovskites, such as widely tunable bandgaps [21–26], high photoluminescence quantum yield (PLQY) [27–29], and narrow emission width [30–32], are making them promising candidates for fabricating luminescent security tags. Meanwhile, the solution/ink processability of perovskites imparts them feasibility with a variety of printing technologies, enabling high-throughput generation of customized labels with enhanced encoding capacity and lowered processing cost [33–35].

Here, we give a retrospect to the recent advances of halide perovskite-based materials for anti-counterfeiting applications. Low-dimensional perovskites and double perovskites that are structural analogs to three-dimensional (3D) ones as well as other perovskite-like materials are included in the discussion. We summarize the patterning techniques that can lead to precise control of tag fabrication at high dim either flat surface or closed space. The luminescent security tags of perovskites are categorized by different encryption principles, with detailed phase transformation or compositional variation of materials being provided for each chromic case. Integration of luminescent properties that gives rise to multimodal anti-counterfeiting is discussed in respect of goods being strictly confidential. We then survey the special optical readout of security tags that is enabled by the exciton relaxation behavior and carrier dynamic of perovskites.
