Direct Photolithography of Fluorescent Copper (I) Iodide Cluster Microarrays

Copper (I) iodide clusters represent a class of promising materials for optoelectronic applications owing to their structural diversity and tunable photophysical properties. Herein, we report a developing free direct photolithography method that enables the in situ growth and patterning of (PPh₃)₄Cu₄I₄ clusters within a polymer matrix through a photoinduced redox reaction. Upon UV irradiation, iodine radicals generated from iodinated organic precursors initiate a redox reaction, triggering the formation of (PPh₃)₄Cu₄I₄ clusters. This approach allows the creation of micro- and nanoscale patterns with a resolution of 6 µm within just 15 min, eliminating the developing step required in conventional photolithography. The resulting patterns exhibit distinct fluorescence under dual-wavelength excitation (310 and 365 nm). Exploiting this characteristic for high-density information encoding, we demonstrate applications in anti-counterfeiting labels and chip encryption. This work provides an efficient and controllable strategy for patterning functional metal-halide clusters, expanding their potential for use in advanced optoelectronic devices.