Zero-Dimensional Cuprous Iodide Clusters with Near-Unity PLQYs for White Lighting

Low-dimensional cuprous halides have garnered significant attention as promising candidates for high-quality phosphors owing to their intrinsic broadband emissions and direct band transitions enabled by polyhedron-level exciton confinement. Herein, we report the facile synthesis and optical study of two zero-dimensional cuprous iodides, (C₁₁H₉NO)₄Cu₂I₂ and (C₁₁H₉NO)₄Cu₄I₄ clusters, with specific [Cu₂I₂] rhomboid dimer and [Cu₄I₄] cubane tetramer configurations, respectively. Comprehensive photophysical analysis reveals that facilitated by efficient ligand-to-core charge transfer, spatially isolated zero-dimensional [Cu₂I₂] and [Cu₄I₄] can function as independent blue and yellow emission centers with large Stokes shifts (>100 nm), large full widths at half-maximum (>100 nm), and near-unity photoluminescence quantum yields. Therefore, through precise stoichiometric control of the CuI:C₁₁H₉NO ratio in a one-pot synthesis, we are able to design biphasic cuprous iodide clusters with arbitrary (C₁₁H₉NO)₄Cu₂I₂:(C₁₁H₉NO)₄Cu₄I₄ ratios, giving rise to highly efficient white light emissions with tunable correlated color temperatures. Given the nature of wideband emissions and flexible color designability, the study of zero-dimensional cuprous iodide clusters establishes a viable route for the development of high-performance phosphors through rational structural and compositional engineering.