Decaborane Clusters: A New Class of Organic‐Inorganic TADF Materials for X‐Ray Scintillation and Electroluminescence

Polyhedral boron clusters possess unique properties, yet their luminescence applications have largely been confined to carborane derivatives. Here, we introduce decaborane clusters [B 10 H 12 L 2 ] (L = pyridine‐like ligands) as an innovative class of organic‐inorganic TADF materials. These clusters exhibit exceptional air and moisture stability, and are readily accessible. A series of fourteen emitters, displaying tunable green‐to‐orange TADF with the quantum efficiency of up to 99%, was synthesized. Detailed photophysical studies reveal that these clusters adopt a flexible A–D–A architecture [L–B 10 H 12 –L] with a pronounced charge‐transfer character and ultranarrow singlet‐triplet energy splittings (as small as 29 cm −1 , ≈0.0036 eV). Beyond TADF properties, these heavy‐atom‐free emitters demonstrate pronounced X‐ray scintillation (detection limit: 67 µGy air s −1 ) and strong aggregation‐induced emission (AIE) behavior. Their utility is further evidenced by electroluminescence in proof‐of‐concept OLEDs, including a white‐emitting device. This work establishes decaborane clusters as a versatile and readily accessible platform for next‐generation TADF materials, expanding the frontiers of p‐block cluster chemistry.