Over 99% Photoluminescence Quantum Yield by Kernel Regulation in 8-Hydroxyquinoline-Based Icosahedral Sn12-Oxo Cluster

Luminescent metal nanoclusters are of great importance as an alternative to rare-earth phosphors for white light-emitting diodes (WLEDs), but they usually show low photoluminescence quantum yield (PLQY) due to a lack of effective control over relaxation and radiation induced by kernel-ligand interaction. Here, a hydrolysis-delayed coordination synthetic strategy is developed in 8-hydroxyquinoline-based tin-oxo clusters covering from doubly vertex-missed icosahedral Sn10 to icosahedral Sn12 and Sn12-Me. 99.29% ultrabright green PLQY is achieved in Sn12, exhibiting a 6.4-fold enhancement compared to 15.43% in Sn10. Femtosecond transient absorption spectroscopy and time-dependent density functional theory reveal a kernel-regulated ligand-centered emission mechanism: the rigid kernel suppresses nonradiative decay through core-to-shell confinement effects, while structural deformation in an unstable kernel disrupts electronic coupling, thereby reducing radiative transitions. Sn12-based WLEDs demonstrate a high color rendering index of up to 87.7, as well as adjustable correlated color temperature. This work provides key insight into high PLQY and suitable solid-state lighting luminescent nanoclusters via kernel regulation.