Zero‐Dimensional Gua3SbCl6 Crystals as Intrinsically Reabsorption‐Free Scintillators for Radiation Detection

Abstract The search for efficient, re‐absorption‐free scintillators has recently focused the attention on antimony‐based halides, which exhibit largely Stokes shifted luminescence due to radiative recombination of excitons self‐trapped (STE) in strongly Jahn–Teller distorted Sb 3+ color centers. Here, the synthesis of a hybrid structure is reported with chemical formula (C 13 H 14 N 3 ) 3 SbCl 6 consisting of spatially isolated [SbCl 6 ] 3− octahedra separated by organic N,N'‐diphenylguanidinium (Gua) molecules. The optical properties of this material are mainly determined by the inorganic component and are characterized by a pronounced Stokes shift of ≈1.3 eV and a room‐temperature photoluminescence (PL) efficiency of up to 85%. Remarkably, highly efficient radioluminescence (RL) is observed with scintillation light yields of ≈2000 ph MeV −1 using both soft X‐rays and a 124 keV gamma source. Temperature‐dependent PL and RL measurements confirm the minor role of non‐radiative channels, which are completely suppressed below 100 K. Thermally stimulated luminescence measurements suggest that the traps in Gua 3 SbCl 6 crystals have a significantly large energy depth distribution below the absorbing state.