Ultrafast nanocomposite scintillators based on Cd-enhanced CsPbCl3 nanocrystals in polymer matrix

Many strategic applications in both science and technology are focused on the detection of ionising radiation. Typically, the detection is performed by scintillator materials. After interaction with ionising radiation, the scintillator emits light which is detected by highly sensitive photodetectors. The fundamental properties of scintillators are the probability of interaction with ionising radiation, scintillation yield, scintillation rate and stability to high doses of absorbed radiation, commonly referred to as radiation hardness. The ability to produce scintillators in large sizes and quantities using cost-effective techniques, both in terms of energy and raw material consumption, is essential for large-scale applications. Recently, lead halide perovskite nanocrystals (LHP-NCs) have emerged as promising nanoscintillators, prized for their tunable optical properties, radiation stability, high average Z-number and defect tolerance, enabling high light yields and resistance to radiation damage up to extreme radiation levels. Mecca et al. recently reported turbo-emulsification synthesis capable of producing large quantities of CsPbBr3 nanocrystals at low cost and room temperature. Most surprisingly, no study to date has addressed the scintillation properties of CsPbCl3 NCs, which exhibit size-tunable ultrafast emission in the UV-blue, thereby extending the spectral tunability of LHP-based nanocomposite scintillators into the typical spectral region of molecular scintillators such as 1, 4-bis(5-phenyloxazol-2-yl) benzene (POPOP) (λEM~410 nm) and para-terphenyl (λEM~350 nm), matching the peak efficiency of photodetectors widely used in high-energy physics experiments. In this talk, I will report on the adaptation of turbo emulsion synthesis for the production of large quantities (150 mg) of CsPbCl3 nanocrystals and the subsequent treatment with CdCl2 conducted directly in monomer solution, obtaining nanocrystals with near unity quantum yield. I will show for the first time the scintillation properties under X-ray stimulation of plastic nanocomposites containing these nanostructures. Radiometry experiments show perfect radiation hardness after a certified γ-ray dose of 1 MGy from a 60Co source. In addition, pulsed X-ray scintillation measurements show ultrafast <60 ps scintillation due to multi-excitonic radiative decay, which is further confirmed by transient absorption measurements. Combining fabrication scalability with ultrafast and stable scintillation under extreme operating conditions provides a valid platform for future advances in radiation detection schemes, particularly time-of-flight radiometry applications in high-energy physics and medical diagnostics.