Solvent-induced structural regulation and luminescence switching of hybrid copper(I) halides for encryption and anti-counterfeiting applications.

Three luminescent copper(I) halides featuring distinct polyhedra were obtained via solvent volatilization, in which consecutive phase transformations of copper(I)-iodide units were triggered by methanol, along with visual luminescence switches, enabling applicability in information encryption and anti-counterfeiting. Such a multiple structural regulation in metal halides provides versatile design principles for photoluminescence tuning.