Lithium Chloride-Substituted Methylammonium Lead Tribromide Perovskites for Dual γ/Neutron Sensing

Dual γ/neutron radiation sensors are a critical component of the nuclear security mission to prevent the proliferation of a special nuclear material (SNM). While high-performing semiconductors such as high purity germanium (HPGe) and CdZnTe (CZT) already exist in the nuclear security enterprise, their high cost and/or logistical burdens make widespread deployment difficult to achieve. Metal lead halide perovskites (MHPs) have attracted interest in recent years to address this challenge. In particular, methylammonium lead tribromide (CH₃NH₃PbBr₃, MAPbBr₃, or MAPB) has been widely evaluated for its radiation sensing capabilities. While previous studies have demonstrated low-energy X-ray and α particle sensing of MAPB-based detectors and several studies discuss the potential for γ ray sensing, neutron sensing of this material has been rarely explored. Here, we explore the incorporation of lithium in the form of LiCl into the MAPB structure to add thermal neutron sensitivity. Characterizations of the lithium-doped MAPB crystals demonstrate that quality growths are achievable with single crystals that exhibit high crystallinity, no phase change, and high macroscopic bulk quality. Finally, we report on the first demonstrated γ ray and thermal neutron sensing based on lithium-doped MAPB single crystals, which is a significant milestone in the development of 3D dual γ/neutron MHP sensors.