2D perovskites have been considered as promising candidates for optoelectronic devices due to their good optical and electronic properties compared to 3D perovskites with significantly higher stability. Considering the commercial applications involving displays, image sensors, and fluorescent anti‐counterfeiting labels, the patterning technique of 2D perovskites is urgently required. However, existing patterning approaches still have challenges in high‐resolution fabrication. Here, a facile femtosecond laser direct writing method to fabricate arbitrarily patterned 2D perovskite films with well‐defined profiles and uniform fluorescence properties is developed. The flexible, fine, and non‐thermal diffused patterning abilities of femtosecond laser facilitate diverse 2D perovskite patterns exhibiting bright emission without any pinholes and cracks, as well as high resolution of approximate 2 µm line width. Based on this efficient patterning technique, this study demonstrates fluorescent anti‐counterfeiting labels (quick response code embedded with microlines) based on 2D perovskite films with high humidity stability, which can be identified from 43% to 96% relative humidity. This high‐resolution, reliable, efficient, and facile patterning technique for 2D perovskites with high humidity stability provides a promising technical route for 2D perovskite‐based optoelectronic applications.

Metal halide perovskites have exhibited promising potential for practical applications such as image sensors and displays benefiting from their outstanding optoelectronic properties. However, owing to the instability of the perovskite materials, producing patterned perovskite films with adequately high quality and high precision for such practical applications poses a challenge for existing patterning methods. Herein, the lamination-assisted femtosecond laser ablation (LA-FsLA) technique was successfully applied to fabricate patterned CsPbBr3 films with sufficiently high quality and high precision. A sandwich-laminated structure (glass/CsPbBr3/glass) was introduced to avoid the impact of debris on the patterned perovskite film. As a result, arbitrarily patterned perovskite films with high quality, submicron precision, and well-defined edges were successfully prepared. Moreover, the light-emitting diodes (LEDs) based on the patterned perovskite films also exhibit good emission characteristics. This work provides a promising strategy for the fabrication of patterned perovskite films with adequately high quality and high precision toward perovskite-based optoelectronic devices.

Femtosecond laser ablation (FsLA) technology has been demonstrated to achieve programmable ablation and removal of diverse materials with high precision. Owing to the cross-scale and digital processing characteristics, the FsLA technology has attracted increasing interest. However, the moderate repeatability of FsLA limits its application in the fabrication of advanced micro-/nanostructures due to the nonidentity of each laser pulse and fluctuation of environment. Fortunately, moderate repeatability combined with programmable ablation and high precision perfectly matches with the technical requirements of a physical unclonable fluorescent anticounterfeiting label. Herein, we applied FsLA to quantum dot (QD) films to fabricate a physical unclonable multilevel fluorescent anticounterfeiting label. Visual Jilin University logos, quick response (QR) codes, microlines, and microholes have been achieved for the multilevel anticounterfeiting functions. Of particular significance, the microholes with a macroidentical and microidentifiable geometry guarantee the physical unclonable functions (PUFs). Moreover, the fluorescent anticounterfeiting label is compatible with deep learning algorithms that facilitate authentication to be convenient and accurate. This work shows a fantastic future potential to be a core anticounterfeiting technique for commercial products and drugs.