All-inorganic perovskite nanocrystal scintillators

Abstract

The rising demand for radiation detection materials in many applications has led to extensive research on scintillators. The ability of a scintillator to absorb high-energy (kiloelectronvolt-scale) X-ray photons and convert the absorbed energy into low-energy visible photons is critical for applications in radiation exposure monitoring, security inspection, X-ray astronomy and medical radiography. However, conventional scintillators are generally synthesized by crystallization at a high temperature and their radioluminescence is difficult to tune across the visible spectrum. Here we describe experimental investigations of a series of all-inorganic perovskite nanocrystals comprising caesium and lead atoms and their response to X-ray irradiation. These nanocrystal scintillators exhibit strong X-ray absorption and intense radioluminescence at visible wavelengths. Unlike bulk inorganic scintillators, these perovskite nanomaterials are solution-processable at a relatively low temperature and can generate X-ray-induced emissions that are easily tunable across the visible spectrum by tailoring the anionic component of colloidal precursors during their synthesis. These features allow the fabrication of flexible and highly sensitive X-ray detectors with a detection limit of 13 nanograys per second, which is about 400 times lower than typical medical imaging doses. We show that these colour-tunable perovskite nanocrystal scintillators can provide a convenient visualization tool for X-ray radiography, as the associated image can be directly recorded by standard digital cameras. We also demonstrate their direct integration with commercial flat-panel imagers and their utility in examining electronic circuit boards under low-dose X-ray illumination.

Light Generation in Lead Halide Perovskite Nanocrystals: LEDs, Color Converters, Lasers, and Other Applications

“…The unique energy diagrams and the resulting high defect tolerance of LHP‐NCs result in superior optical and electrical characteristics even when LHP‐NCs are fabricated by a crude synthesis However, the low luminous efficiency of LHP‐NCs at low excitation densities suggests that there is still considerable loss from trap‐induced nonradiative recombination . Hence, the most efficient LHP‐NCs are crystalline and surrounded by passivating ligands …”

“…c) Multicolor X‐ray scintillation pattern from LHP NCs with different halide species. Reproduced with permission . Copyright 2018, Springer Nature.…”

“…Light emission from lead halide perovskites (LHPs) was reported over a decade ago; however, weak emissions at room temperature hindered the application of LHPs in light‐emitting devices because LHPs did not show any electroluminescence at the time . In the past few years, LHPs have returned to the spotlight in the form of nanoscale emitters because of their superior features in light generation and resulting applications . Low‐cost solution processing techniques are used to fabricate LHP nanocrystals (LHP‐NCs), and impressive achievements have been made in using LHP‐NCs in high‐brightness light‐emitting diodes (LEDs) with high external quantum efficiency (EQE) and as color converters for lighting and full‐color displays that have a wide color gamut and near‐unity luminous efficiency .…”

“…In addition to applications based on efficient luminescence under low excitation density, LHP‐NCs exhibit optically pumped low‐threshold lasing and proof‐of‐principle electrically excited lasing . Nonclassic applications exploiting LHP‐NCs have been extended to the direct detection of ionizing radiation, e.g., X‐rays and γ‐rays in which high‐energy X‐ray photons are converted to bright visible light and to single photon emitters that can be used in quantum technologies for communication, metrology, and encryption …”

Full‐Spectrum Persistent Luminescence Tuning Using All‐Inorganic Perovskite Quantum Dots

“…[7] Specifically, the PL emission of CsPbX 3 PeQDs can be facilely tuned over the entire visible spectral region by adjusting the halide composition. [7] Specifically, the PL emission of CsPbX 3 PeQDs can be facilely tuned over the entire visible spectral region by adjusting the halide composition.…”