Synergistic Top-Down Etching Coupled with In Situ Phase Transition: A Strategy for High-Precision Photolithographic Patterning of Perovskite Single Crystals

• • The integrated top-down etching and in situ phase transition achieves high-precision, region-selective growth of CsPbBr3 micropatterns within Cs4PbBr6 single crystals, combining the robust environmental stability of Cs4PbBr6 with the excellent optoelectronic properties of CsPbBr3. • • The process utilizes non-emissive Cs4PbBr6 SCs as both structural templates and reaction sources, enabling spatially selective patterning via precise wet and dry etching followed by ICP-induced phase transition, simplifying photolithography procedures and enabling rapid, large-scale manufacturability. • • Integration with machine learning optimization algorithms enhances microstructural pattern recognition, demonstrating significant application potential in intelligent anti-counterfeiting. • • This approach provides a new fabrication strategy for high-performance perovskite optoelectronic devices through processing of homologous SCs with customized photolithography, expected to promote technological development and breakthroughs in the field.