Two-dimensional lead halide perovskites have demonstrated their potential as high-performance scintillators for X- and gamma-ray detection, while also being low-cost. Here we adopt lithium chemical doping in two-dimensional phenethylammonium lead bromide (PEA)₂PbBr₄perovskite crystals to improve the properties and add functionalities with other radiation detections. Li doping is confirmed by X-ray photoemission spectroscopy and the scintillation mechanisms are explored via temperature dependent X-ray and thermoluminescence measurements. Our 1:1 Li-doped (PEA)₂PbBr₄demonstrates a fast decay time of 11 ns (80%), a clear photopeak with an energy resolution of 12.4%, and a scintillation yield of 11,000 photons per MeV under 662 keV gamma-ray radiation. Additionally, our Li-doped crystal shows a clear alpha particle/gamma-ray discrimination and promising thermal neutron detection through⁶Li enrichment. X-ray imaging pictures with (PEA)₂PbBr₄are also presented. All results demonstrate the potential of Li-doped (PEA)₂PbBr₄as a versatile scintillator covering a wide radiation energy range for various applications.

Two-dimensional (2D) hybrid lead bromide perovskites are candidates for high light yield, fast scintillators. In this paper, we discuss the effect of commensurate Lithium (Li)-doping (1 : 1 Li : Pb precursor ratio) on the scintillation properties of two previously reported high light yield 2D-perovskite crystals, PEA₂PbBr₄ and BA₂PbBr₄. The effect of Li, e.g. light yield enhancement, is more prominent in PEA₂PbBr₄ compared to BA₂PbBr₄. Both perovskite crystals show a broadening of the radioluminescence spectrum and a slightly longer afterglow, with residual scintillation below 2% after 5 s for both materials. The effects of Li on the negative thermal quenching exhibited by the perovskites are also discussed. Li doping increases the light yield of PEA₂PbBr₄ by 78% and both perovskite materials show an improvement in their energy resolutions, with a record of 7.7% at 662 keV for the Li-doped PEA₂PbBr₄. Both perovskite crystals also show very fast gamma-ray excited scintillation decays, with average times of 12.9 ns and 8.0 ns for PEA₂PbBr₄ and BA₂PbBr₄, respectively. This work shows that Li doping brings a significant improvement of the perovskite performance, making the perovskites more competitive for fast, high light yield applications in the medical, security or industrial sectors.

Two-dimensional hybrid-organic-inorganic perovskite (2D-HOIP) lead bromide perovskite crystals have demonstrated great potential as scintillators with high light yields and fast decay times while also being low cost with solution-processable materials for wide energy radiation detection. Ion doping has been also shown to be a very promising avenue for improvements of the scintillation properties of 2D-HOIP crystals. In this paper, we discuss the effect of rubidium (Rb) doping on two previously reported 2D-HOIP single crystals, BA₂PbBr₄ and PEA₂PbBr₄. We observe that doping the perovskite crystals with Rb ions leads to an expansion of the crystal lattices of the materials, which also leads to narrowing of band gaps down to 84% of the pure compounds. Rb doping of BA₂PbBr₄ and PEA₂PbBr₄ shows a broadening in the photoluminescence and scintillation emissions of both perovskite crystals. Rb doping also leads to faster γ-ray scintillation decay times, as fast as 4.4 ns, with average decay time decreases of 15% and 8% for Rb-doped BA₂PbBr₄ and PEA₂PbBr₄, respectively, compared to those of undoped crystals. The inclusion of Rb ions also leads to a slightly longer afterglow, with residual scintillation still being below 1% after 5 s at 10 K, for both undoped and Rb-doped perovskite crystals. The light yield of both perovskites is significantly increased by Rb doping with improvements of 58% and 25% for BA₂PbBr₄ and PEA₂PbBr₄, respectively. This work shows that Rb doping leads to a significant enhancement of the 2D-HOIP crystal performance, which is of particular significance for high light yield and fast timing applications, such as photon counting or positron emission tomography.