Laser Fabrication of Multi-Dimensional Perovskite Patterns with Intelligent Anti-Counterfeiting Applications

Abstract

Perovskites have gained widespread attention across various fields such as photovoltaics, displays, and imaging. Despite their promising applications, achieving precise and high-quality patterning of perovskite films remains a challenge. In this study, femtosecond laser direct writing technology is utilized to achieve rapid and highly precise micro/nanofabrication on perovskites. The study successfully fabricates multiple structured and emission-tunable perovskite patterns composed of A₂(FA)_n-1Pb_nX_3n+1 (A represents a series of long-chain amine cations, and X = Cl, Br, I), encompassing 2D, quasi-2D, and 3D structures. The study delves into the intricate interplay between fabrication technology and the growth of multi-dimensional perovskites: higher repetition rates, coupled with appropriate laser power, prove more conducive to perovskite growth. By employing precise halogen element design, the simultaneous generation of two distinct color quick-response (QR) code patterns is achieved through one-step laser processing. These mirrored QR codes offer a novel approach to anti-counterfeiting. To further enhance anti-counterfeiting capabilities, artificial intelligence (AI)-based methods are introduced for recognizing patterned perovskite anti-counterfeiting labels. The combination of deep learning algorithms and a non-deterministic manufacturing process provides a convenient means of identification and creates unclonable features. This integration of materials science, laser fabrication, and AI offers innovative solutions for the future of security features.

Keywords: anti‐counterfeiting; artificial intelligence; femtosecond laser direct writing; perovskite.

Figure 1

The key procedures conducted in this study involved the following steps. Initially, perovskite precursor solutions were prepared with varying ratios of PAN/DMF solution and deposited onto heated glass substrates to create perovskite precursor films. Subsequently, we utilized a 517 nm fs laser processing system to fabricate 2D, quasi‐2D RP, and 3D perovskite patterns, achieving the production of two‐color perovskite patterns in a single processing step. In addition, we incorporated AI‐based techniques for the utilization of perovskites in anti‐counterfeiting applications.

Figure 2

Characterization of 2D, and quasi‐2D RP A₂(FA)_n−1Pb_nBr_3n+1 perovskite patterns. a) The setup of the fs processing system: the 517 nm fs laser is focused through an objective lens, and processing is achieved by computer‐controlled movement of the stage. b)The XRD patterns of (AVA)₂(FA)_n−1Pb_nBr_3n+1 films. c) The PL intensities of (AVA)₂(FA)_n−1Pb_nBr_3n+1 films. d) The (AVA)₂(FA)_n−1Pb_nBr_3n+1 films with n = 1, n = 2, and n = 4 were fabricated by FsLDW on glass substrates under ambient light and 365 nm UV light, scale bar is 1 mm. e) TEM images of (AVA)₂(FA)_n−1Pb_nBr_3n+1 films.

Figure 3

a) 1 × 1 mm squares processed with fs laser at various laser power densities under a repetition rate of 750 kHz. b) 1 ×1 mm squares processed with fs laser at a laser power density of 22.6 kW cm⁻² and a scanning speed of 0.25 mm s⁻¹ under different repetition rates. c) The 1 × 1 mm squares of 2D perovskites were processed with fs laser at different laser powers and scanning speeds under a repetition rate of 750 kHz. d) XRD patterns of (NMA)₂(FA)_n−1Pb_nBr_3n+1 films. e) UV–vis absorption spectra of (NMA)₂(FA)_n−1Pb_nBr_3n+1 films.

Figure 4

a) Periodic grids with spacing of 10, 8, and 5 µm, and b) geometric quasi‐2D RP perovskite patterns fabricated on glass using FsLDW technology. c) SEM images of the geometric patterns, all the scale bars of (a–c) are 25 µm.

Figure 5

a) An emblem pattern processed from the precursor film on a single‐crystal silicon wafer. b) An emblem pattern processed from the precursor film on a flexible PDMS substrate. c) The pattern representing “CRH” was processed on a ticket of China Railway Highspeed using FsLDW, the blue circle indicates the enlarged area and is displayed under 365 nm UV light. d) The samples were processed under 365 nm UV light after replacing the X in the precursor (NMA)₂(FA)_n−1Pb_nX_3n+1 with various other halogen elements, with a scale of 300 µm. e)The various scattered letters are presented, which were processed from precursor films without a substrate.

Figure 6

a,b) Rectangular 2D barcodes, measuring 6.75 mm, fabricated from (NMA)₂FAPb₂Br₅I₃ perovskite films using FsLDW. a) Fabricated on the side facing the laser. b) Fabricated on the side facing the substrate. c) Schematic representation of the convolutional neural network. d) Six anti‐counterfeiting labels representing genuine products in the database. e) Anti‐counterfeiting labels were created on the new film based on the original labels in inset (c). f) The six labels that were not pre‐learned.