Timing performance of lead halide perovskite nanoscintillators embedded in a polystyrene matrix

Abstract

Nanocrystals of CsPbBr3 have been incorporated in a polystyrene matrix with 1–10% weight filling factors. Samples were characterized with the main focus on their timing capability under soft X-ray irradiation for application as ultrafast scintillation detectors.

Ultrafast and Radiation-Hard Lead Halide Perovskite Nanocomposite Scintillators

“…Notably, for all samples, we observed a prompt ultrafast decay component modeled with a Gaussian function (relative weight R P ∼ 30% ) and a τ 1 ∼ 0.6 ns long decay component with comparable weight followed by a longer-lived tail of around τ 2 ∼ 10 ns matching the respective PL lifetime, τ PL . The time constant, relative weights and corresponding effective scintillation lifetime, τ EFF extracted as the weighted harmonic average of the decay contributions, are summarized in Table for the five nanocomposites and match well the timing performance recently reported for CsPbBr 3 NCs synthesized by conventional hot-injection method and incorporated into a polystyrene host by solvent evaporation . The ultrafast timing capability demonstrated, in particular, by the prompt kinetic component is of great relevance for TOF technologies.…”

“…By exploiting the efficient and fast scintillation of NCs , in combination with the flexibility of plastic fabrication, nanocomposite scintillators hold promise to bridge the gap between the single crystal and plastic approaches, thus enabling a leap forward in radiation detection schemes. In particular, lead halide perovskites (LHP) NCs, in the inorganic and hybrid forms APbX 3 (where A is methylammonium, formamidinium, or Cs and X is a halogen), have recently emerged as promising nanoscintillators ,,− valued for their tunable fast and efficient scintillation and unique tolerance to structural defects, , enabling competitive LY and radiation hardness up to extreme radiation levels, comparable to the annual dose accumulated in nuclear reactors or high-brightness particle accelerators. , Despite these advantages, the widespread use of nanocomposite scintillators based on LHP-NCs has been hampered mainly by manufacturing constraints. In particular, hot-injection synthesis methods , used for high-optical-quality LHP NCs are not suitable for mass production, and more scalable ligand assisted reprecipitation (commonly referred to as LARP) − techniques, in which NCs growth is initiated by the addition of antisolvents at room temperature, may suffer from concentration gradients in the reaction environment (especially at multi-liter scale) resulting in generally poorer optical performance. , The recently reported kinetically controlled synthesis of spheroidal LHP NCs by Akkerman et al offers exciting possibilities for further development in this respect .…”

“…For ⟨ N ⟩ > 1, the differential TA curves accelerated substantially with respect to the single exciton kinetics, yielding a biexciton lifetime τ XX ∼ 200 ps. Considering a biexciton radiative lifetime, τ XX,Rad = τ X,Rad /4, and a single exciton radiative lifetime of τ X,Rad = 10 ns, we obtain a that the picosecond XX decay is largely dominated by AR, with a biexciton yield Φ XX = τ XX / τ XX,Rad ∼ 0.08 consistent with similar CsPbBr 3 materials. − Further increasing the excitation fluence to ⟨ N ⟩ > 2 resulted in higher order multiexciton lifetime as short as τ MX ∼ 60 ps, in agreement with recent reports on CsPbBr 3 NCs of comparable size . For intermediate excitation fluence (⟨ N ⟩ ≤ 1), the bleach kinetics featured a lifetime of ∼0.8 ns, matching the intermediate timing component of the RL kinetics ( τ 1 ).…”

A new method to characterize low stopping power and ultra-fast scintillators using pulsed X-rays

“…Two nanomaterial samples were measured as proof-ofconcept: lead halide perovskite (CsPbBr 3 ) nanocrystal embedded in polystyrene [28], with a weighted filling factor of 10% and an overall size of 3 × 3 × 0.1 mm 3 and multi-quantum well (MQW) InGaN/GaN [17] grown on a sapphire substrate of 500 μm thickness, with 1 μm thick active layer and cross-section of 3 × 3 mm 2 . The former sample was produced at the Czech Technical University (CTU) in Prague, while the latter was produced at the Institute of Physics of the Czech Academy of Science (FZU) in Prague, Czech Republic.…”

“…We are aware that these ultra-fast Frontiers in Physics frontiersin.org components, together with the need for many decay components, suggest that the exponential model might not be the best one to describe the physical processes generating the scintillation of these materials. A different model to better describe the decay profile of this kind of sample was recently proposed by Děcká et al [28] on the trail of the one used by Gundacker et al [30] to fit Cherenkov emission on top of scintillation. It consists in adding a Dirac-delta contribution to the exponential part to properly account for the (semi-)prompt emission.…”