Highly Stable Organic Antimony Halide Crystals for X‑ray Scintillation

Scintillators
are utilized for X-ray detection in many important
fields ranging from homeland security to health care. Developing low-cost,
high-performance scintillation materials to address the issues of
existing commercially available ones is of great interest. Recently,
organic metal halide hybrids have emerged as highly promising luminescent
materials with excellent optical properties and low-temperature solution
processability. Herein, we report a zero-dimensional organic metal halide hybrid, (PPN)2SbCl5 (PPN = bis­(triphenylphosphoranylidene)­ammonium cation),
as an X-ray scintillation material with high light yield and exceptional
environmental stability. Our study shows that (PPN)2SbCl5 single crystals prepared by solution growth exhibit visible
photoluminescence with a quantum efficiency of 98.1%. When excited
by X-rays, (PPN)2SbCl5 single crystals exhibit
radioluminescence with a near-perfect linearity over a large range
of X-ray dose rates and a light yield of ∼49000 ph MeV–1, which is comparable to that of a commercial CsI­(Tl)
scintillator (∼54000 ph MeV–1). Moreover,
the detection limit of (PPN)2SbCl5 (191.4 nGyair s–1) is much lower than the required
value for regular medical diagnostics (5.5 μGyair s–1). (PPN)2SbCl5 single
crystals also display remarkable stability, with little-to-no change
in properties after storage under ambient conditions for 2 years.