Gas-Developing-Guided\nIn Situ Photolithography of\nMAPbBr<sub>3</sub> Perovskite Nanocrystal Micropatterns

Photolithography plays a pivotal role in fabricating\nhigh-resolution\npatterns of lead halide perovskite nanocrystals (PNCs). However, the\nionic nature of PNCs renders them sensitive to the complex solvents\nused during the etching and developing process, posing an enduring\nchallenge in photolithography. Here, we introduce a facile and reproducible\ngas-developing-guided photolithography for the high-resolution micropatterning\nof MAPbBr<sub>3</sub> PNCs based on the intrinsic low formation energy\nof PNCs. Initially, PbBr<sub>2</sub> micropatterns are formed via\nUVC light-driven debromination, subsequently transforming into highly\nphotoluminescent MAPbBr<sub>3</sub> PNC micropatterns upon developing\nmethylamine gas. This system achieves a remarkable resolution of up\nto 2 μm. Furthermore, the resulting MAPbBr<sub>3</sub> PNC micropatterns\nexhibit excellent stability against light, heat, water, and organic\nvapors, maintaining 90% optical performance even after immersion in\nwater for 60 days. These micropatterns have been successfully applied\nin anticounterfeiting with high capacity. The ability to directly\npattern MAPbBr<sub>3</sub> PNCs using a simple gas-developing process,\ncomparable to conventional complicated solvent-based methods, offers\nan alternative pathway for manufacturing thin-film devices.