Highly Resolved and Robust Dynamic X‐Ray Imaging Using Perovskite Glass‐Ceramic Scintillator with Reduced Light Scattering

Abstract

All‐inorganic perovskite quantum dots (QDs) CsPbX3 (X = Cl, Br, and I) have recently emerged as a new promising class of X‐ray scintillators. However, the instability of perovskite QDs and the strong optical scattering of the thick opaque QD scintillator film imped it to realize high‐quality and robust X‐ray image. Herein, the europium (Eu) doped CsPbBr3 QDs are in situ grown inside transparent amorphous matrix to form glass‐ceramic (GC) scintillator with glass phase serving as both matrix and encapsulation for the perovskite QD scintillators. The small amount of Eu dopant optimizes the crystallization of CsPbBr3 QDs and makes their distribution more uniform in the glass matrix, which can significantly reduce the light scattering and also enhance the photoluminescence emission of CsPbBr3 QDs. As a result, a remarkably high spatial resolution of 15.0 lp mm−1 is realized thanks to the reduced light scattering, which is so far a record resolution for perovskite scintillator based X‐ray imaging, and the scintillation stability is also significantly improved compared to the bare perovskite QD scintillators. Those results provide an effective platform particularly for the emerging perovskite nanocrystal scintillators to reduce light scattering and improve radiation hardness.

Glass‐Crystallized Luminescence Translucent Ceramics toward High‐Performance Broadband NIR LEDs

“…Transparent glass precursors with the compositions of Y 3− x Ca x Al 5− x − y Cr y Si x O 12 ( x = 0.0–1.4, y = 0.00–0.08) were obtained using an aerodynamic levitation furnace equipped with a laser heating system (see Experimental Section and Figure S1 , Supporting Information), which enables containerless melting and rapid cooling at high temperature (up to 2000 °C) without contamination. [ 19 , 21 ] To transform YAG into a glass‐forming material, we introduced the glass network former SiO 2 to establish the required interconnectivity. [ 24 ] Then, CaO was added to ensure the charge balance within the resulting garnet crystals by cosubstitution of (Ca 2+ —Si 4+ ) for (Y 3+ —Al 3+ ), [ 23 , 25 ] avoiding unexpected defects as well.…”

“…These pores stem from the strong contraction during glass crystallization due to the large difference in density between YCAS glass (3.61 g cm −3 ) and YCAS crystal (4.08 g cm −3 ). [ 19 ] Therefore, more attention should be paid to eliminating the residual pores for controllable light scattering in the future, such as optimizing the annealing schedule and using appropriate sintering aids. [ 18 , 29 ]…”

“…[ 30 ] Finally, we also anticipated that it is possible, though very challenging, for glass crystallization to achieve efficient Cr 3+ activated bulk materials with longer peak emission wavelength (>800 nm) as well as extra‐broad emission band, through rational design of the glass composition and fine control of the crystalline phases. [ 19 , 20 , 21 ]…”

“…Traditional powder sintering for the densification of ceramics relies on high pressure and high vacuum techniques, which is expensive and also limited to the preparation of RGB ceramics for high‐power white light sources. [ 17 , 18 ] Instead, we adopted a much simpler and pressureless method, that is, full crystallization of amorphous materials (glasses) into crystalline ones (ceramics), [ 19 ] which has succeeded in developing transparent ceramics without cubic symmetry via introducing structural disorder [ 20 ] and efficient RGB multi‐phase translucent composites. [ 21 ] Considering the large flexibility of garnet crystals in composition, [ 22 ] we selected the well‐known Y 3 Al 5 O 12 (YAG) garnet as the starting material.…”

Highly Efficient and Flexible Scintillation Screen Based on Manganese (II) Activated 2D Perovskite for Planar and Nonplanar High‐Resolution X‐Ray Imaging

“…[21,22,25] Among the perovskite communities, allinorganic CsPbBr 3 nanocrystals have been extensively studied as an exemplary scintillator material, which exhibit near-unity photoluminescence quantum yield (PLQY), fast decay time, low detection limit, and high spatial resolution in X-ray ima ging. [11,13,17,26,27] However, the barriers of CsPbBr 3 nanocrystals are that: 1) the low effective atomic number cannot guarantee sufficient X-ray energy absorption because they are usually dispersed in a solution at a low concentration [13] (when dispersed at a high concentration, cluster formation and massively increased surface/bulk ratio deteriorate the luminescence performance and stability, respectively [26][27][28] ); 2) the unavoidable self-absorption phenomenon caused by the intrinsic small Stokes shift greatly reduces the light output efficiency. [29] As a further development, Tang's group reported a series of MHP scintillator systems with self-trapped excitons (STEs) emission mechanism.…”