Ultra‐Stable Luminescent Smart Textiles Embedded With Thermally Responsive Copper Iodide Clusters

Copper iodide clusters have emerged as a promising candidate for flexible optoelectronic devices due to their structural versatility and exceptional photoluminescence (PL) properties, yet their practical application is hindered by insufficient mechanical fragility and environmental stability. Herein, a scalable wet-spinning strategy is presented to fabricate ultrastable Cu₄I₄(L)₄@CA fibers (L₁ = 4-benzylpyridine; L₂ = 4-tert-butylpyridine; CA = calcium alginate). The molecular encapsulation preserves high photoluminescence quantum yields (PLQYs >85%) at an ultralow 1 wt% doping while enabling fully reversible thermochromic switching: white to yellow (L₁) and blue-purple to orange (L₂) transitions across 80-300 K. The fibers demonstrate textile-grade flexibility and ultrahigh environmental stability (>98% PL retention under humidity/UV/solvents). Leveraging these properties, a dual-authentication encryption platform is pioneered featuring triple-state information switching (ambient, UV, and cryogenic states) and DNA-inspired binary photonic encoding using programmable Y-/cross-shaped spinnerets for data transcription. By harmonizing stimuli-responsive optoelectronics with textile processability, this work establishes a synergistic material platform for next-generation secure wearables, stealth luminescent textiles, and hierarchical anti-counterfeiting systems.