High-Quality Patterning of CsPbBr3 Perovskite Films through Lamination-Assisted Femtosecond Laser Ablation toward Light-Emitting Diodes

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

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-1PbnX3n+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.

Crosslinkable Ligands for High-Density Photo-Patterning of Perovskite Nanocrystals

Perovskite nanocrystals (PNCs) are promising luminescent materials for electronic color displays due to their high luminescence efficiency, widely-tunable emission wavelengths, and narrow emission linewidth. Their application in emerging display technologies necessitates precise micron-scale patterning while maintaining good optical performance. Although photolithography is a well-established micro-patterning technique in the industry, conventional processes are incompatible with PNCs as the use of polar solvents can damage the ionic PNCs, causing severe luminescence quenching. Here, we report the rational design and synthesis of a new bidentate photo-crosslinkable ligand for the direct photo-patterning of PNCs. Each ligand contains two photosensitive acrylate groups and two carboxylate groups, and is introduced to the PNCs via an entropy-driven ligand exchange process. In a close-packed thin film, the acrylate ligands photo-polymerize and crosslink under ultraviolet light, rendering the PNCs insoluble in developing solvents. A high-density crosslinked PNC film with an optical density of 1.1 is attained at 1.4 µm thickness, surpassing industry requirements on the absorption coefficient. Micron-scale patterning is further demonstrated using direct laser writing, producing well-defined 20 µm features. This study thus offers an effective and versatile approach for micro-patterning PNCs, and may also be broadly applicable to other nanomaterial systems.

Recent Advances in Patterning Strategies for Full-Color Perovskite Light-Emitting Diodes

Metal halide perovskites have emerged as promising light-emitting materials for next-generation displays owing to their remarkable material characteristics including broad color tunability, pure color emission with remarkably narrow bandwidths, high quantum yield, and solution processability. Despite recent advances have pushed the luminance efficiency of monochromic perovskite light-emitting diodes (PeLEDs) to their theoretical limits, their current fabrication using the spin-coating process poses limitations for fabrication of full-color displays. To integrate PeLEDs into full-color display panels, it is crucial to pattern red-green-blue (RGB) perovskite pixels, while mitigating issues such as cross-contamination and reductions in luminous efficiency. Herein, we present state-of-the-art patterning technologies for the development of full-color PeLEDs. First, we highlight recent advances in the development of efficient PeLEDs. Second, we discuss various patterning techniques of MPHs (i.e., photolithography, inkjet printing, electron beam lithography and laser-assisted lithography, electrohydrodynamic jet printing, thermal evaporation, and transfer printing) for fabrication of RGB pixelated displays. These patterning techniques can be classified into two distinct approaches: in situ crystallization patterning using perovskite precursors and patterning of colloidal perovskite nanocrystals. This review highlights advancements and limitations in patterning techniques for PeLEDs, paving the way for integrating PeLEDs into full-color panels.