Cation-Induced Strategy toward an Hourglass-Shaped Cu₆I₇^– Cluster and Its Color-Tunable Luminescence

We have designed and synthesized a series of two-dimensional materials featuring with a (3,6)-connected kgd layer, in which an unprecedented anionic Cu6I7– cluster was first trapped through a cation-induced synthetic strategy. The emission colors of these cluster-based luminophores gradually shift from blue to yellow as the monovalent cations (Li+, Na+, NH4+, K+, TEA+) located between the neighboring layers changed. SCXRD analyses discover that the variation of the emission may be attributed to the transformation of the hourglass-shaped Cu6I7– cluster. The bright, tunable, and broad luminescent emissions make them promising candidates as phosphors for light-emitting diodes (LEDs). Particularly, compound 1-TEA emitting intensive yellow light with high luminescence quantum efficiency (QY = 79.9%) shows extremely high thermal, pH, organic solvent, and mechanical photostabilities. By employing it as a yellow phosphor, we fabricate a series of white lighting materials with high color rendering index (CRI).