Multi-Level Waterproofing Strategy Toward an Ultra-Water-Stable 2D Luminescent Copper(I) Iodide: From Atomic-Level Passivation to Surface-Interface Hydrophobicity

Organic–inorganic hybrid materials face significant barriers to large-scale commercialization, primarily stemming from their intrinsic vulnerability to moisture-triggered hydrolytic degradation. Herein, an ultra-stable 2D copper(I) iodide, Cu 6 I 6 (26dmpz) 3 , is engineered through a synergistic waterproofing strategy that integrates atomic-level passivation and surface-interface hydrophobicity. N-metal coordination in Cu 6 I 6 (26dmpz) 3 (26dmpz = 2,6-dimethylpyrazine) passivates H-bond donors at atomic-level, blocking hydrolytic degradation induced by N─H···O interactions. Its methyl-dominated non-polar surface and “hydrogen-bond-free” contribute to low surface energy (37.68 mJ m −2 ) and polarity (4.09 mJ m −2 ), minimizing water adsorption, as corroborated by a 130.8° contact angle. The 2D corrugated groove structure creates a physical barrier against water penetration at solid–liquid interfaces. This endows Cu 6 I 6 (26dmpz) 3 with exceptional water stability, preserving its structure and luminescence after 30 days in water. Moreover, it shows bright orange–red emission (616 nm) with strong blue-light response, attributed to halide/metal-to-ligand charge transfer. The fabricated white LED exhibits an ultra-high color rendering index (CRI = 89.9), showing tremendous potential for high-quality solid-state lighting.