Nature Communications, Published online: 12 June 2026; doi:10.1038/s41467-026-74341-0 Bi-based chalcogenides and oxychalcogenides host interesting topological, ferroelectric and optoelectronic properties, but a generable synthesis method of this material family is still missing. Here, the authors report the growth of mm-sized Bi-based chalcogenide and oxychalcogenide crystals on K+-free mica surfaces, showing high-performance transistors and photodetectors.