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.