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2D Dion–Jacobson (DJ) perovskites recently have attracted extensive attention for X‐ray detection owing to their structural rigidity and environmental stability. The chemical incorporation of π‐conjugation aromatic spacing cations into DJ phase perovskites will increase the rigidity of cation and electron cloud density between adjacent inorganic slabs, thus facilitating structural rigidity and charge transport. However, it is still a challenge to synthesize high‐quality single crystals of DJ phase perovskite with aromatic spacers for detecting X‐ray applications. Here, a new DJ phase perovskite by introducing π‐conjugated aromatic cation spacer, (4ABA)PbI4 (1, 4ABA = 4‐aminobenzylamine), eliminating the van der Waals gap is designed. High‐quality single crystals of 1 are grown via the facile solution method, exhibiting high resistivity (1.97 × 1011 Ω cm), low trap density (3.36 × 109 cm−3), and large carrier mobility‐lifetime product (1.03 × 10−3 cm2 V−1) under X‐ray illumination. Such remarkable physical characteristics endow single crystal 1 detector with high‐performance X‐ray detection including a high sensitivity of 572 µC Gyair−1cm−2, an ultralow detection limit of 7.50 nGyair s−1 and exceptional radiation stability. The X‐ray detection limit of 1 is over 700 times lower than that of routine medical diagnosis (5500 nGyair s−1), demonstrating potential applications in medical examination. [ABSTRACT FROM AUTHOR]

Cs3Bi2I9 (CBI) is a promising material for direct X‐ray detectors. However, for the solution method, due to the difference in the chemical potential of Cs+, Bi3+, I− ions in the solvent, the composition of CBI single crystals (SCs) prepared by the solution method often deviates from the stoichiometric ratio, resulting in the formation of many defects in the material, which degrades the quality of the SC. Herein, Br− and Cl− are used as dopants to produce CBI SCs by the top seed solution method. It can be speculated that the dopant ions can reduce the VI defects in the CBI by means of density functional theory calculations. The carrier lifetimes of CBI SCs doped with Br− and Cl− have been increased to 41.7 and 13.0 ns, respectively. Meanwhile, the defect densities of the SCs are reduced to 1.02 × 109 and 1.85 × 109 cm−3, respectively. X‐ray detectors based on Br‐doped CBI and Cl‐doped CBI SCs exhibit high X‐ray sensitivity of 23071.3 and 18525.3 μC Gyair−1 cm−2 at an electric field of 40 V mm−1, respectively. In addition, the X‐ray detection limit reaches 1.07 and 1.35 nGyairs−1 at an electric field of 2.5 V mm−1, respectively. [ABSTRACT FROM AUTHOR]

Organic‐inorganic hybrid perovskites are promising candidates for direct X‐ray detection and imaging. The relatively high dark current in perovskite single crystals (SCs) is a major limiting factor hindering the pursuit of performance and stability enhancement. In this study, the contribution of dark current is disentangled from electronic (σe) and ionic conductivity (σi) and shows that the high σi dominates the dark current of MAPbBr3 SCs. A multilayer heterojunctions passivation strategy is developed that suppresses not only the σi by two orders of magnitude but also σe by a factor of 1.6. The multilayer heterojunctions passivate the halide vacancy defects and increase the electron and hole injection barrier by inducing surface p‐type doping of MAPbBr3. This enables the MAPbBr3 SC X‐ray detectors to obtain a high sensitivity of 19 370 µC Gyair−1 cm−2 under a high electric field of 100 V cm−1, a record high sensitivity for bromine self‐powered devices, and a low detection limit of 42.3 nGyair s−1. The unencapsulated detectors demonstrate a stable baseline after storage for 210 days and outstanding operational stability upon irradiation with an accumulated dose of up to 1944 mGyair. [ABSTRACT FROM AUTHOR]

Owing to the large x-ray attenuation coefficient, appropriate bandgap, high resistivity, and high mobility-lifetime (μτ) product, binary II–VI semiconductor CdSe is a promising x-ray detection material and it has exhibited excellent x-ray detection at room temperature (RT). For further improving the characteristics of CdSe x-ray detectors, the electrical properties of CdSe single crystals (SCs) grown through the pressure-assisted vertical Bridgman method and their x-ray detection performance have been investigated at RT and liquid nitrogen temperature (LNT), respectively. The significantly enhanced x-ray photocurrent and the prolonged response time of the devices operating at LNT indicate the photogenerated carrier lifetime could be increased by the enhanced trapping–detrapping effect obviously, and the μτ product of CdSe SCs increases from 1.39 × 10−5 to 5.34 × 10−4 cm2 V−1 with temperature lowering from RT to LNT. Meanwhile, an ultrahigh sensitivity of 5.24 × 106μC Gyair−1 cm−2 and an extremely low detection limit of 3.68 nGyair s−1 have been acquired by the CdSe SC based x-ray detectors at LNT, which is 140 times higher and 5.8 times lower than it has been at RT. Compared with conventional semiconductor x-ray detectors, the ultra-high sensitivity and extremely low detection limit of CdSe SC based detectors make their application prospects very promising. [ABSTRACT FROM AUTHOR]

Low‐dimensional perovskites (LDPs) have attracted significant attention due to their high stability, great chemical flexibility, and fertile "playground" for structural modulation, which are expected to herald the next‐generation multifunctional devices. While there is a high diversity of LDPs in the literature, the organic cations in most of the literature are still limited to amines. Here, the preparation of centimeter‐sized LDP single crystals with amidino‐based spacers is described, which enables systematic investigations on how halides initiate different structural stacking and on their physical properties. The 4‐amidinopyridine (4AP) cation in (4AP)PbX4 (X = Br, I) is vertically distributed between the inorganic layers to form a two‐dimensional perovskite. While the Cl‐based exhibits one‐dimensional perovskitoid packing. The change of halogens from Cl to Br and I leads to a lower hydrogen bonding, hardness and activation energy of the crystal. Finally, the potential of these crystals for X‐ray detectors is demonstrated. The (4AP)PbBr4 device achieves the highest sensitivity among three devices (373.1 µC Gyair−1 cm−2, 10 V), benefiting from the balanced charge transport and ionic migration. It is anticipated that this work will lead to further studies on the exploration and physics of novel LDP with properties suitable for radiation detection. [ABSTRACT FROM AUTHOR]

Perovskite single crystals and polycrystalline films have complementary merits and deficiencies in X‐ray detection and imaging. Herein, we report preparation of dense and smooth perovskite microcrystalline films with both merits of single crystals and polycrystalline films through polycrystal‐induced growth and hot‐pressing treatment (HPT). Utilizing polycrystalline films as seeds, multi‐inch‐sized microcrystalline films can be in situ grown on diverse substrates with maximum grain size reaching 100 μm, which endows the microcrystalline films with comparable carrier mobility‐lifetime (μτ) product as single crystals. As a result, self‐powered X‐ray detectors with impressive sensitivity of 6.1×104 μC Gyair−1 cm−2 and low detection limit of 1.5 nGyair s−1 are achieved, leading to high‐contrast X‐ray imaging at an ultra‐low dose rate of 67 nGyair s−1. Combining with the fast response speed (186 μs), this work may contribute to the development of perovskite‐based low‐dose X‐ray imaging. [ABSTRACT FROM AUTHOR]

CsI(Tl) scintillator has been widely used in X-ray flat-panel detectors due to excellent performance characteristics including a suitable Si-photodiode emission wavelength, excellent optical output, and fast decay time. Here, a solution-based space-confined growth method was presented to achieve CsI(Tl) scintillator single-crystal flakes with controllable thickness. The grown CsI(Tl) single-crystal flake exhibits a comparable light yield (∼72,000 photons/MeV) and a lower afterglow level (0.1% @ 21 ms, 0.01% @ 118 ms) in comparison to that by the traditional melting method. This space-confined method allows for the achievement of a single crystal thickness of only 0.27 mm, making it suitable for direct application in X-ray detection and other related fields. It may open up new possibilities for the development of halide scintillator single crystals. A solution-based space-confined growth method enables the growth of high-quality CsI(Tl) single crystal flakes with controlled thickness for X-ray flat-panel detectors. [Display omitted] • A space-confined solution method is used to grown CsI(Tl) single-crystal flakes. • The thickness of the CsI(Tl) flake grown using this method can be controlled to be as thin as approximately 0.27 mm. • The CsI(Tl) flake exhibits a lower afterglow and a comparable light yield in comparison to that by the melting method. [ABSTRACT FROM AUTHOR]

Perovskite X-ray detectors are actively investigated because of their exceptional properties, including their significant attenuation coefficient, low defect density, excellent transport characteristics, easy growth, and high sensitivity to X-ray photons. However, perovskite-based high-energy X-ray detectors on the MeV scale are rarely explored. In this study, we investigate the optoelectronic characteristics and radiation detection capabilities of triple-cation Cs 0.05 FA 0.9 MA 0.05 PbI 3 single crystals (CSC) grown using the inverse temperature crystallization method. The CSCs with a reduced Goldschmidt tolerance factor owing to the presence of Cs and MA ions exhibit exceptional properties, including a bandgap of 1.447 eV, low dark current, and self-powered response to X-ray irradiation. The X-ray absorption rate of 36 keV exceeded 99% with a CSC thickness of 2 mm, demonstrating its strong stopping power. Moreover, the CSC detectors exhibit precise linear responses to varying X-ray doses and dose rates with R2 values close to 1 and relative standard deviation (RSD) values below 3% under all the tested conditions. In addition, the detector effectively detected high-energy X-rays of up to 15 MV with minimal variations in the RSD values. These findings highlight the potential of CSC as promising materials for high-performance X-ray detectors. • Triple-cation lead–halide perovskites for high-energy X-ray detection were studied. • CSC detector has uniform linear response to varying X-ray doses and rates. • CSC detector can detect high-energy X-rays of up to 15 MeV. • CSC demonstrated remarkable promise as excellent self-powered X-ray detectors. [ABSTRACT FROM AUTHOR]

The recently demonstrated Cs3Bi2I9 single crystals (SCs) exhibit superior performance for X‐ray detection. More importantly, they do not contain any toxic lead element. However, compared with lead‐halide perovskites, one challenge for the Cs3Bi2I9 SC for X‐ray detection application is that it is difficult to prepare large‐sized and high‐quality SCs. Here, a liquid diffused separation induced crystallization (LDSC) method is employed to grow Cs3Bi2I9 SCs for eliminating the temperature fluctuation and convection currents caused by the thermal gradient in the growth solution. The resultant Cs3Bi2I9 SC exhibits a microstrain of 1.21 × 10–3, a resistivity of 1.12 × 109 Ω cm, a carrier mobility of 4.57 cm2 V–1 s–1, and a mobility‐lifetime product of 1.87 × 10–3 cm2 V–1. As a result, an X‐ray detector based on the high‐quality Cs3Bi2I9 SC exhibits an excellent dose rate linearity, a sensitivity of 964 µC Gyair–1 cm–2, and a limit of detection (LoD) of 44.6 nGyair s–1. [ABSTRACT FROM AUTHOR]