Aggregation-Controlled Cuprophilic Interactions Enable Blue-Excitable Zero-Dimensional Copper(I) Iodide Phosphors for...

Zero-dimensional (0D) organic-inorganic hybrid metal halides are promising phosphors, yet their wide bandgaps typically require ultraviolet excitation, limiting compatibility with commercial blue light-emitting diode (LED) chips. Here, we present an aggregate-engineering strategy to unlock blue-light excitability in 0D copper(I) iodides by modulating the aggregation architecture of Cu-I motifs within a fixed phosphonium-cation framework. Two homologous compounds, (C₂₆H₂₄OP)₂Cu₂I₄ and (C₂₆H₂₄OP)₂Cu₄I₆, were selectively synthesized through simple stoichiometric regulation. Increasing the nuclearity from a dimer to a tetramer strengthens cuprophilic interactions, narrows the optical bandgap from 2.98 to 2.61 eV, and markedly broadens the excitation window into the blue region. Density functional theory calculations further support the aggregation-induced bandgap narrowing by revealing increased inorganic contributions at the band edges in the tetramer. Notably, the tetramer achieves a high thermal stability and moisture tolerance. Finally, a single-component white LED (WLED) based on the tetramer and a 450 nm chip delivers high-quality white light, and a proof of concept for visible light communication enables high-fidelity audio transmission. This work establishes aggregate engineering as an effective design principle for bridging 0D hybrid halides with practical blue-chip pumping and integrated lighting communication platforms.