High‐Resolution Patterning of 2D Perovskite Films through Femtosecond Laser Direct Writing

Abstract 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.