Inorganic scintillators play a major role in ionizing radiation detection due to their high versatility to detect multiple radiation sources such as X-rays, gamma-rays, alpha, beta, and neutron particles, and their fast and high light yield, making them especially convenient for imaging, spectroscopy, and timing applications. Scintillators-based detection systems are found, among various applications, in medical imaging, homeland security, high-energy physics, industrial control, oil drilling explorations, and energy management. This Review discusses advances and prospects of perovskite scintillators, particularly low-dimensional hybrid organic-inorganic perovskite crystals and all-inorganic perovskite nanocrystals. We highlight the promise of two-dimensional lithium-doped (PEA)₂PbBr₄ crystals and CsPbBr₃ nanocrystals as scintillators with high light yields, exceeding 20 photons/keV, and fast decay times of less than 15 ns. Such a combination may result in fast-spectral X-ray imaging, an output count rate exceeding 30 Mcps/pixel in photon-counting computed tomography, and coincidence timing resolution of less than 100 ps in positron emission tomography. We review recent strategies to further improve light yield, decay time, and coincidence timing resolution through light-matter interactions such as extraction efficiency enhancement and Purcell-enhanced scintillators. These advancements in light yields and decay times of perovskite scintillators will be particularly useful in the medical and security applications.

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.

Quantum-well (QW) hybrid organic-inorganic perovskite (HOIP) crystals, e.g., A₂PbX₄ (A = BA, PEA; X = Br, I), demonstrated significant potentials as scintillating materials for wide energy radiation detection compared to their individual three-dimensional (3D) counterparts, e.g., BPbX₃ (B = MA). Inserting 3D into QW structures resulted in new structures, namely A₂BPb₂X₇ perovskite crystals, and they may have promising optical and scintillation properties toward higher mass density and fast timing scintillators. In this article, we investigate the crystal structure as well as optical and scintillation properties of iodide-based QW HOIP crystals, A₂PbI₄ and A₂MAPb₂I₇. A₂PbI₄ crystals exhibit green and red emission with the fastest PL decay time 3.0 g/cm³ and tunable smaller bandgaps 5 times lower than those for bromides. The lower light yields can be the drawbacks of iodide-based QW HOIP scintillators, but the promising high mass density and decay time results of our study can provide the right pathway for further improvements toward fast-timing applications.

Two-dimensional (2D) hybrid organic-inorganic perovskite (HOIP) crystals show promise as scintillating materials for wide-energy radiation detection, outperforming their three-dimensional counterparts. In this study, we synthesized single crystals of (PEA_2-xBZA_x)PbBr₄ (x ranging from 0.1 to 2), utilizing phenethylammonium (C₆H₅CH₂CH₂NH₃⁺) and benzylammonium (C₆H₅CH₂NH₃⁺) cations. These materials exhibit favorable optical and scintillation properties, rendering them suitable for high light yield (LY) and fast-response scintillators. Our investigation, employing various techniques such as X-ray diffraction (XRD), photoluminescence (PL), time-resolved (TR) PL, Raman spectroscopy, radioluminescence (RL), thermoluminescence (TL), and scintillation measurements, unveiled lattice strain induced by dual-organic cations in powder X-ray diffraction. Density functional theory analysis demonstrated a maximal 0.13 eV increase in the band gap with the addition of BZA cation addition. Notably, the largest Stokes shift of 0.06 eV was observed in (BZA)₂PbBr₄. The dual-organic cation crystals displayed >80% fast component scintillation decay time, which is advantageous for the scintillating process. Furthermore, we observed a dual-organic cations-induced enhancement of electron-hole transfer efficiency by up to 60%, with a contribution of >70% to the fast component of scintillation decay. The crystal with the lowest BZA concentration, (PEA_1.9BZA_0.1)PbBr₄, demonstrated the highest LYs of 14.9 ± 1.5 ph/keV at room temperature. Despite a 55-70% decrease in LY for BZA concentrations >5%, simultaneous reductions in scintillation decay time (12-32%) may work for time-of-flight positron emission tomography and photon-counting computed tomography. Our work underscores the crucial role of dual-organic cations in advancing our understanding of 2D-HOIP crystals for materials science and radiation detection applications.