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 [B₁₀H₁₂L₂] (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-B₁₀H₁₂-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.