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.

Solution-processed hybrid organic–inorganic lead halide perovskites have potential for next generation X-ray imaging applications. Here, we discuss the effect of Pb replacement by Cu or Sn on the optical and scintillation properties of the high-light-yield and fast crystal scintillators of BA₂PbBr₄. By replacing Pb with Cu or Sn, the measured bandgap shifts from 3.59 to 3.90 and 3.44 eV, while the photoluminescence decay time slows down from 3.0 ns to 1.3 and 8.5 μs, respectively. The bandgaps and the structures are also validated by density functional theory calculations. Although BA₂CuBr₄ and BA₂SnBr₄ have large Stokes shifts of 2.06 and 1.13 eV, respectively, both crystals show no radioluminescence (RL) at room temperature (RT). Temperature-dependent RL measurements demonstrate that BA₂PbBr₄ has negative thermal quenching, while Pb replacement by Cu or Sn results in strong thermal quenching, affecting the light yields at RT. Despite slow decay times and low light yields for BA₂CuBr₄ and BA₂SnBr₄, this study opens new understanding for lead-free perovskite crystals and the trends in their scintillation properties.

Scintillators convert high‐energy radiation into detectable photons and play a crucial role in medical imaging and security applications. The enhancement of scintillator performance through nanophotonics and nanoplasmonics, specifically using the Purcell effect, has shown promise but has so far been limited to ultrathin scintillator films because of the localized nature of this effect. This study introduces a method to expand the application of nanoplasmonic scintillators to the bulk regime. By integrating 100‐nm‐sized plasmonic spheroid and cuboid nanoparticles with perovskite scintillator nanocrystals, nanoplasmonic scintillators are enabled to function effectively within bulk‐scale devices. Power and decay rate enhancements of up to (3.20 ± 0.20) and (4.20 ± 0.31) folds are experimentally demonstrated for plasmonic spheroid and cuboid nanoparticles, respectively, in a 5‐mm thick CsPbBr₃ nanocrystal‐polymer scintillator at RT. Theoretical modeling also predicts similar enhancements of up to (2.26 ± 0.31) and (3.02 ± 0.69) folds for the same nanoparticle shapes and dimensions. Moreover, a (2.07 ± 0.39) fold increase in light yield under ²⁴¹Am γ‐excitation is demonstrated. These findings provide a viable pathway for utilizing nanoplasmonics to enhance bulk scintillator devices, advancing radiation detection technology.

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.