Search

X‐ray detectors have obtained great attention in medical diagnostics, security checks, and space exploration. However, ion migration of X‐ray detectors results in dark current drift, low signal‐to‐noise ratio, and degradation of detection performance. Here, ion migration properties of Li2ZrTeO6 and ZrTe3O8 are comprehensively investigated by theoretical analysis and experimental results. ZrTe3O8 single crystal exhibits a high migration barrier of O2− ion (1.89 eV), a high ion activation energy (992.6 meV), and an ultralow dark current drift (3.16 × 10−9 nA cm−1 s−1 V−1) due to the absence of Li+ cations and the disconnecting of adjacent ZrO6 octahedra, which is better than Li2ZrTeO6 single crystal. These results show that the absence of low atomic number elements and the disconnecting of adjacent octahedra in crystal structure can inhibit ion migration essentially. Owing to a high resistivity, a high mobility lifetime product, suppressed ion migration, and the lone‐pair electrons enhancement effect of detection performance for Te4+ cations, ZrTe3O8 X‐ray detector shows a high sensitivity of 348 µC Gy−1 cm−2 and an ultralow detection limit of 15.4 nGyair s−1. This work proposes an effective strategy to inhibit ion migration and proves the enhancement effect of detection performance for the cations containing lone‐pair electrons. [ABSTRACT FROM AUTHOR]

Lead‐free hybrid perovskites (HPs) are considered as environmentally friendly photodetection materials. However, there are few studies on self‐powered photodetection in lead‐free HPs, and most of them are achieved through the introduction of chiral ammonium cations induced bulk photovoltaic effect (BPVE). Notably, enantiomeric pure chiral ammonium cations are difficult to synthesize, the quantity is small and the price is high. Therefore, choosing achiral ammonium cations to induce BPVE in lead‐free HPs is crucial. Herein, achiral cations 1,3‐bis(aminomethyl)cyclohexane (1,3‐BMACH) is exploited to induce bulk photovoltaic through confinement effect in (1,3‐BMACH)BiI5, then self‐powered X‐ray detection is successfully realized. Due to the large space in zero‐dimensional (0 D) (MXD)BiI5 (MXD is meta‐xylylenediammonium), the confinement effect is not obvious, resulting in the disorderly arrangement of MXD2+ cations and a centrosymmetry structure of (MXD)BiI5. Benefiting from the large photovoltage (1.0 V) of (1,3‐BMACH)BiI5 under X‐ray, its single crystal devices exhibit ultra‐high sensitivity of 170 µC Gy−1 cm−2 and extremely low detection limit of 49 nGy s−1 under self‐powered mode, which almost surpassing most low‐dimensional single‐phase lead‐free HPs at 0 V bias. This work has promoted the application of lead‐free HPs in the field of self‐powered X‐ray detection. [ABSTRACT FROM AUTHOR]

Dion–Jacobson (DJ) double perovskites have emerged as environmentally friendly candidates for X‐ray detection, owing to their prominent optoelectronic performance and highlighted structural rigidity. Despite considerable efforts, the exploration of polar DJ‐type double perovskites for self‐powered X‐ray detection remains scarce. Herein, by introducing a diamine spacer to increase the structural rigidity, the study has successfully designed a new polar 2D DJ‐type double perovskite of (HIA)2AgBiBr8 (1, HIA = histamine), and centimeter‐size crystals are successfully obtained for effective X‐ray detection. Structurally, 1 features the quantum‐confined motif comprised of the directionally arranged inorganic perovskite sheets and alternating organic spacing cations, which endows a large mobility‐lifetime (µτ) product up to 1.23 × 10−3 cm2 V−1 on the par with typical X‐ray sensing candidates (MAPbI3 wafers, µτ = 2 × 10−3 cm2 V−1). This attribute gives rise to a high sensitivity of 118 µCGyair−1 cm−2 to X‐ray illumination. Moreover, based on its polar structure, bulk photovoltaic effect with the photovoltage of ≈0.45 V is obtained in 1, which affords the driving source toward the self‐powered X‐ray photodetection. This work highlights the potential of DJ‐type double perovskites in high‐energy ray detection and opens avenues for exploring new functionalities of DJ double perovskites as smart photoelectric candidates. [ABSTRACT FROM AUTHOR]

Metal halide perovskite single crystals are promising for hard X‐ray detection, but growth of large‐sized thin single crystals and inhibition of halide ion migration under high bias are challenging. Herein, the preparation of dense stacking of oriented millimeter‐sized perovskite single crystals with capability of large‐area fabrication, controlled thickness, and high ion migration activation energy (Ea)is reported. The oriented growth results in absence of grain boundaries parallel with the substrates, leading to large carrier mobility‐lifetime (µτ) product of 2.7 × 10−3 cm2 V−1, which is comparable to values of many perovskite bulk single crystals. Under low bias, hard X‐ray detectors exhibit high sensitivity of 1.2 × 104 µC Gy−1 cm−2 and low detection limit of 87.5 nGy s−1, which are comparable to those of many single‐crystal hard X‐ray detectors under high bias. Moreover, combination of low bias and high Ea results in weak halide ion migration and small dark current drift of 3.2 × 10−4 nA cm−1 s−1 v−1. Benefited from the superior detector performance, high‐contrast hard X‐ray imaging can be obtained at a low dose rate of 1.26 µGy s−1. The work may promote the application of perovskite hard X‐ray detectors in practical imaging area. [ABSTRACT FROM AUTHOR]

Surface defects are crucial to perovskite single crystals (SCs) for versatile optoelectronic applications, whereas suffers from the intricate post‐treatments and unsatisfactory reproducibility within solution growth strategy due to the residue solvent corrosion and adsorbed precursors deposition. Here, an ionic liquid, 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI) is demonstrated, assisted solution growth approach for fabricating high‐quality self‐cleaning perovskite single crystals with no need for any post‐treatment. Benefiting from the in situ assembling in crystalline surface, BMITFSI can effectively decrease the crystallographic trap density by simultaneously introducing the self‐cleaning effect and optimizing the crystalline growth process. Particularly, as fabricated MAPbI3 single crystal exhibits an impressive photodetection performance with a specific detectivity of 2.83 × 1012 Jones in visible‐IR spectrum and a sensitivity of 7.24 × 104 µC Gyair−1 cm−2 in X‐ray detection, which is as good as the conventionally fabricated crystal with elaborate post‐treatments. Based on the chemical composition independent universality, this work paves an easy but efficient route to improve the current crystallization methodology toward high‐quality perovskite SCs fabrication. [ABSTRACT FROM AUTHOR]

The anomalous photovoltaic (APV) effect in organic–inorganic hybrid perovskites (OIHPs) has attracted massive interest for developing high‐performance optoelectronic devices. However, exploring the ionizing radiation responsive APV effect remains blank, let alone its potential applications. Herein, the unprecedented APV behavior in a 1D lead‐free OIHP, (4‐AMP)BiI5 (ABI, 4‐AMP = 4‐(aminomethyl)pyridine) under X‐ray irradiation is reported, exhibiting a large above‐bandgap bulk photovoltage of ≈10 V. Such a strong APV effect is closely related to the intrinsic electric polarization in polar ABI, which acts as the driving force for X‐ray‐generated carriers' separation and transport, thus allowing it to be self‐powered. As a result, sensitive self‐powered X‐ray detectors based on high‐quality ABI single crystals are successfully fabricated, possessing a high sensitivity of 66.84 µC Gy−1 cm−2, a low detection limit of 482 nGy s−1, and superior operational stability. This work first demonstrates the ionizing radiation‐responsive APV effect in OIHPs, which further enables passive radiation detection. [ABSTRACT FROM AUTHOR]

Significant progress is achieved in the development of hybrid lead halide perovskite‐based X‐ray detectors. An in‐depth understanding of the impact of X‐ray irradiation on charge carrier behaviors is essential to assess the long‐term operational reliability of these devices. In this study, high‐quality methylammonium lead bromide (MAPbBr3) single crystals with good environmental stability are grown by an inverse temperature method, and the evolution of their carrier transport capacity is investigated by tracking the optoelectronic properties of MAPbBr3 single crystal devices under X‐ray irradiation with different fluence. Notably, the carrier transport capacity is enhanced when the X‐ray fluence is between 1.2 × 1017 and 1.8 × 1017 photons, as evidenced by improved optoelectronic properties and reduced trap state density. Conversely, a larger X‐ray fluence of 3.6 × 1017 photons causes unrepaired decomposition of the MAPbBr3 single crystals and severe degradation of their carrier transport capacity. These findings provide valuable insights for the application of hybrid lead perovskite single crystals in X‐ray detection, emphasizing the importance of optimizing X‐ray fluence levels for sustained device performance. [ABSTRACT FROM AUTHOR]

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]

Scintillation semiconductors play increasingly important medical diagnosis and industrial inspection roles. Recently, two‐dimensional (2D) perovskites have been shown to be promising materials for medical X‐ray imaging, but they are mostly used in low‐energy (≤130 keV) regions. Direct detection of MeV X‐rays, which ensure thorough penetration of the thick shell walls of containers, trucks, and aircraft, is also highly desired in practical industrial applications. Unfortunately, scintillation semiconductors for high‐energy X‐ray detection are currently scarce. Here, This paper reports a 2D (C4H9NH3)2PbBr4 single crystal with outstanding sensitivity and stability toward X‐ray radiation that provides an ultra‐wide detectable X‐ray range of between 8.20 nGyair s−1 (50 keV) and 15.24 mGyair s−1 (9 MeV). The (C4H9NH3)2PbBr4 single‐crystal detector with a vertical structure is used for high‐performance X‐ray imaging, delivering a good spatial resolution of 4.3 lp mm−1 in a plane‐scan imaging system. Low ionic migration in the 2D perovskite enables the vertical device to be operated with hundreds of keV to MeV X‐ray radiation at high bias voltages, leading to a sensitivity of 46.90 μC Gyair−1 cm−2 (−1.16 V μm−1) with 9 MeV X‐ray radiation, demonstrating that 2D perovskites have enormous potential for high‐energy industrial applications. [ABSTRACT FROM AUTHOR]

Inorganic Bi‐based perovskites have shown great potential in X‐ray detection for their large absorption to X‐rays, diverse low‐dimensional structures, and eco‐friendliness without toxic metals. However, they suffer from poor carrier transport properties compared to Pb‐based perovskites. Here, we propose a mixed‐halogen strategy to tune the structural dimensions and optoelectronic properties of Cs3Bi2I9−nBrn (0≤n≤9). Ten centimeter‐sized single crystals are successfully grown by the Bridgman technique. Upon doping bromine to zero‐dimensional Cs3Bi2I9, the crystal transforms into a two‐dimensional structure as the bromine content reaches Cs3Bi2I8Br. Correspondingly, the optoelectronic properties are adjusted. Among these crystals, Cs3Bi2I8Br exhibits negligible ion migration, moderate resistivity, and the best carrier transport capability. The sensitivities in 100 keV hard X‐ray detection are 1.33×104 and 1.74×104 μC Gyair−1 cm−2 at room temperature and 75 °C, respectively, which are the highest among all reported bismuth perovskites. Moreover, the lowest detection limit of 28.6 nGyair s−1 and ultralow dark current drift of 9.12×10−9 nA cm−1 s−1 V−1 are obtained owing to the high ionic activation energy. Our work demonstrates that Br incorporation is an effective strategy to enhance the X‐ray detection performance by tuning the dimensional and optoelectronic properties. [ABSTRACT FROM AUTHOR]

Low‐dimensional copper‐based halide single crystals are considered excellent scintillators for indirect X‐ray detection, but their potential in direct X‐ray detection has not been investigated. Herein, high‐quality pure Cs3Cu2I5 and Li‐doped Cs3Cu2I5:Li single crystals are grown by the Bridgman method. The Li+ dopant enhances the photoelectric properties of the Cs3Cu2I5 single crystal by extending the carrier lifetime, improving the carrier mobility from 6.49 to 9.52 cm2 V−1 s−1, and increasing the mobility‐lifetime (µτ) product from 1.4 × 10−4 to 2.9 × 10−4 cm2 V−1. The sensitive direct X‐ray detector with a vertical device configuration of Au/Cs3Cu2I5:Li single crystal/PCBM/Au is fabricated and demonstrated to have a high sensitivity of 831.1 µC Gyair−1 cm−2 and low detection limit of 34.8 nGyair s−1. Furthermore, the detector shows negligible baseline current drift and excellent stability upon X‐ray radiation. [ABSTRACT FROM AUTHOR]

Scintillators, which can convert high‐energy ionizing radiation (e.g., X‐ or γ‐rays) into ultraviolet‐visible light, have been widely applied in medical and industrial fields. Developing new scintillation materials with high performance and low cost is very desirable in order to address the growing application demands. Among them, single‐crystal scintillators of organic‐inorganic hybrid metal halides (OIMHs) have attracted much attention because of their excellent optical transparency, suppressed light scattering, and facile solution preparation methods. Herein, three new centimeter‐sized (2‐DMAP)2MnX4 (2‐DMAP+ = 2‐dimethylaminopyridinium, X = Cl, Br, I) single crystals with high crystal quality are synthesized via the solvent evaporation method. Benefiting from the high optical transparency and remarkable luminescence property, (2‐DMAP)2MnBr4 delivers a high X‐ray light yield of 22 000 photons MeV−1, a low limit of detection of 9.50 nGy s−1, and an excellent X‐ray imaging spatial resolution of 20–25 lp mm−1. Moreover, the regulation of single‐crystal thickness from 0.31 mm to 3.03 mm can be easily achieved via a simple solution post‐treatment method, which has a significant influence on the transmittance, spatial imaging resolution, and detection limit. This work demonstrates a promising single‐crystal scintillator for the application of high‐resolution X‐ray imaging with low preparation cost and tunable thickness. [ABSTRACT FROM AUTHOR]

Lead halide perovskites have made great advance in direct X‐ray detection, however the presence of toxic lead and the requirement of high working voltages severely limit their applicability and operational stability. Thus, exploring "green" lead‐free hybrid perovskites capable of detecting X‐rays at zero bias is crucial but remains toughly challenging. Here, utilizing chiral R/S‐1‐phenylpropylamine (R/S‐PPA) cations, a pair of 0D chiral‐polar perovskites, (R/S‐PPA)2BiI5 (1R/1S) are constructed. Their intrinsic spontaneous electric polarization induces a large bulk photovoltage of 0.63 V, which acts as a driving force to separate and transport photogenerated carriers, thus endowing them with the capability of self‐driven detection. Consequently, self‐driven X‐ray detectors with a low detection limit of 270 nGy s−1 are successfully constructed based on high‐quality, inch‐sized single crystals of 1R. Notably, they show suppressed baseline drift under the self‐driven mode, exhibiting superior operational stability. This study realizes self‐driven X‐ray detection in a single‐phase lead‐free hybrid perovskite by exploiting the intrinsic bulk photovoltaic effect, which sheds light on future explorations of lead‐free hybrid perovskites toward "green" self‐driven radiation detectors with high performance. [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]

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]

Semiconductor‐based X‐ray detectors with low detectable thresholds become critical in medical radiography applications. However, their performance is generally limited by intrinsic defects or unresolved issues of materials, and developing a novel scintillation semiconductor for low‐dose X‐ray detection is a highly urgent objective. Herein, a high‐quality rare‐earth iodate Tm(IO3)3 single crystal grown through low‐cost solution processing is reported with a wide bandgap of 4.1 eV and a large atomic number of 53.2. The roles of IO and TmO groups for charge transport in the Tm(IO3)3 are revealed with the structural difference between the [101] and [1¯01]$[{\bar{1}}01]$ crystal orientations. Based on anisotropic responses of material properties and detection performances, it is found that the [1¯01${\bar{1}}01$] orientation, the path with fewer IO groups, achieves a high resistivity of 1.02 × 1011 Ω cm. Consequently, a single‐crystal detector exhibits a low dark current and small baseline drifting due to the wide bandgap, high resistivity and less ion migration of Tm(IO3)3, resulting in a low detection limit of 85.2 nGyair s−1. An excellent X‐ray imaging performance with a high sensitivity of 4406.6 µC Gyair−1 cm−2 is also shown in the Tm(IO3)3 device. These findings provide a new material design perspective for high‐performance X‐ray imaging applications. [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]

Organic–inorganic hybrid copper(I)‐based halides have attracted great interest in the field of optoelectronics due to their low cost, non‐toxicity, large Stokes shift, and high photoluminescence quantum yields (PLQYs). Here, bulk zero‐dimensional (0D) organic‐inorganic hybrid copper(I)‐based (R,S‐2‐mpip)2Cu2I6 (mpip = methylpiperazinium, C5H14N22+) single crystals have been grown with equal stoichiometric ratios of R‐ and S‐2‐mpip ligands by chirality–racemization strategy for the first time. Interestingly, (R,S‐2‐mpip)2Cu2I6 single crystals exhibit strong blue–green photoluminescence (PL) located at 520 nm with large Stokes shift of about 230 nm and high PLQY of about 65.96%, which originates from self‐trapped excitons (STEs). More importantly, (R,S‐2‐mpip)2Cu2I6 single crystals also exhibit the strong radioluminescence (RL) at 520 nm, the fast X‐ray scintillation response with a light yield of about 47 000 photon MeV−1 and low detection limit of 6.48 nGyairs−1 when exposed to X‐ray irradiation condition, which is superior to that of other copper(I) iodide‐based hybrids. Based on the excellent characteristics, X‐ray imaging systems based on (R,S‐2‐mpip)2Cu2I6 single crystals exhibit the clear images of "QFNU" logo and crystal symbol pattern. This work not only deepens the understandings of material design and fundamental properties of these racemate systems, but also provides guidance for the further applications in the multi‐functional optoelectronics. [ABSTRACT FROM AUTHOR]

Organometal halide perovskite single crystals are one of the most promising radiation detection materials due to their unique advantages of high absorption coefficient, long carrier diffusion length, and low defect density. However, the severe ion migration in perovskites deteriorates the X‐ray detection performance under longtime and high‐field operating conditions. This work reports an effective additive of chenodeoxycholic acid (CDCA), which can suppress the ion migration and improve the performance and the operational stability of FAPbBr3 single crystals (SCs) in X‐ray detection significantl. The CDCA molecules in precursors effectively suppress the decomposition of FA ions, resulting in a better crystal orientation and stoichiometry. The trace amounts of CDCA residues in FAPbBr3 SCs improve the thermal stability and effectively suppress the ion migration. The resulting detector shows an impressive X‐ray sensitivity up to 21 386.88 µC Gyair−1 cm−2 under −500 V and a detection limit of 15.23 nGyair s−1. The response current of the detector at 225 V cm−1 field is barely changed under the 7200 s irradiation with a dose rate of 1.949 mGyair s−1. This work provides insights for the additive selection and improving the operational stability of perovskite single crystals for commercial applications. [ABSTRACT FROM AUTHOR]

Self‐powered halide perovskite X‐ray detectors have evoked busting interests because they present outstanding properties such as low power consumption, high sensitivity, and integrability without external power source. Nevertheless, existing self‐powered X‐ray detectors exhibit low sensitivity due to the insufficient charge separation and transport. Herein, a self‐powered photodetector for sensitive X‐ray and photodetection based on single‐crystalline perovskite FAPbBr3/NiOx heterostructure is demonstrated. The built‐in field of FAPbBr3/NiOx heterojunction provides a driving force for separation and transport of photoexcited carriers. Without an external power supply, the photodetector presents excellent photoresponse performance under 450 nm light illumination, including high photoresponsivity (123.6 mA W−1), good detectivity (D = 7.1 × 1011 Jones), and ultrafast response/recovery time (10/200 ns). Simultaneously, the device achieves photovoltaic effect of 0.80 V and a large mobility–lifetime product of 1.1 × 10−3 cm2 V−1, which enable a superior X‐ray sensitivity of 402 µC Gyair−1 cm−2 at zero bias voltage. These results imply that the simple combination of perovskite single crystal and a hole transporting layer provides a flexible platform for the realization of energy‐saving self‐powered photodetector in visible light and X‐rays. [ABSTRACT FROM AUTHOR]

Semiconductor heterostructures underpin the design and performance of virtually all modern optoelectronic systems. The clear interface, high crystalline quality, and suitable energy band match lay the foundation for high‐performance heterojunction optoelectronic devices. Here, a facile solution epitaxial growth method is demonstrated for controllably growing CH3NH3PbBr3 single crystal (SC) on the CH3NH3PbCl3 SC, which forms a pn heterojunction with a well‐defined interface and high single‐crystalline quality. The thickness of the epitaxial layer can be finely controlled by adjusting the growth time. Benefiting from excellent built‐in electrical potential at pn heterojunction, the heterojunction detector shows an obvious rectification behavior and high performance in photo‐imaging and X‐ray detection without any power supply, including high responsivity (26.8 mA W−1), fast response time (8/613 µs), and high sensitivity of 868 µC Gyair−1 cm−2 with a record lowest detectable X‐ray dose rate of 15.5 nGyair s−1. Furthermore, it exhibits high‐fidelity UV photo‐imaging capability at zero bias voltage. In addition, the heterojunction detector shows excellent stability by maintaining 99% of the initial responsivity after 120 days without any encapsulation in the atmosphere. This work enables a significant advance in engineering perovskite SC heterojunction for developing novel and functional devices. [ABSTRACT FROM AUTHOR]

The dark current drift caused by severe ion migration in all‐inorganic perovskite CsPbBr3 degrades the stability of X‐ray detection performance under a high electric field. The halogen doping is an effective method to improve the properties of the perovskites. In this work, the all‐inorganic Cl‐doped perovskites CsPbBr3‐nCln (n=0, 0.1 and 0.5) single crystals were grown by a modified low‐temperature inverse temperature crystallization (ITC) method with the growth temperature lower than the phase transition point. The trap density decreased to 3.05×1010 cm−3 and the carrier mobility increased to 124.75 cm2 V−1 s−1 for the optimum component of CsPbBr2.9Cl0.1. Furthermore, by designing the detector with an asymmetric electrode configuration, CsPbBr2.9Cl0.1 detector showed super low dark current and an outstanding hard X‐ray induced photo‐response under a high voltage of 200 V. Consequently, the CsPbBr2.9Cl0.1 perovskite detector delivers a high sensitivity (5593.24 μC Gyair−1 cm−2) and a low detection limit (0.68 μGyair s−1). Our low temperature solution grown Cl‐doped all‐inorganic perovskite single crystals efficiently improve the photoelectric properties and enhance the X‐ray detection performance. [ABSTRACT FROM AUTHOR]

Despite the rapid progress of hybrid organic–inorganic halide perovskites in optoelectronic applications, their water resistance is still limited because of the interaction of both the organic and inorganic components with water molecules. In this study, a cation engineering protocol to obtain a material with inherent high water resistance by incorporating benzamidinium (BAH) cations into the bismuth halide framework is developed. Analysis of the crystal structure indicates that (BAH)BiI4 exhibits a molecular 1D perovskitoid structure with an edge‐sharing mode and strong noncovalent interactions within the crystal, including I•••I interaction, hydrogen bonding, and π–π stacking between adjacent BAH cations. Such strong noncovalent interactions provide excellent water resistance, with negligible decomposition of crystals during water soaking for two months. The feasibility of the (BAH)BiI4 crystal for X‐ray detection, with a sensitivity as high as 1181.8 µC Gyair−1 cm−2 and a detection limit below 77 nGyair s−1 under 50 V bias is further demonstrated. Such good values are due mainly to efficient charge transport along the π–π stacking between neighboring BAH cations and I•••I interactions between adjacent inorganic chains. These findings provide a new approach to improve the water resistance of perovskite/perovskitoid optoelectronic devices. [ABSTRACT FROM AUTHOR]

Spectroscopic‐grade single crystal detectors can register the energies of individual X‐ray interactions enabling photon‐counting systems with superior resolution over traditional photoconductive X‐ray detection systems. Current technical challenges have limited the preparation of perovskite semiconductors for energy‐discrimination X‐ray photon‐counting detection. Here, this work reports the deployment of a spectroscopic‐grade CsPbBr3 Schottky detector under reverse bias for continuum hard X‐ray detection in both the photocurrent and spectroscopic schemes. High surface barriers of ≈1 eV are formed by depositing solid bismuth and gold contacts. The spectroscopic response under a hard X‐ray source is assessed in resolving the characteristic X‐ray peak. The methodology in enhancing X‐ray sensitivity by controlling the X‐ray energies and flux, and voltage, is described. The X‐ray sensitivity varies between a few tens to over 8000 μC Gyair−1 cm−2. The detectable dose rate of the CsPbBr3 detectors is as low as 0.02 nGyair s−1 in the energy discrimination configuration. Finally, the unbiased CsPbBr3 device forms a spontaneous contact potential difference of about 0.7 V enabling high quality of the CsPbBr3 single crystals to operate in "passive" self‐powered X‐ray detection mode and the X‐ray sensitivity is estimated as 14 μC Gyair−1 cm−2. The great potential of spectroscopic‐grade CsPbBr3 devices for X‐ray photon‐counting systems is anticipated in this work. [ABSTRACT FROM AUTHOR]

Low‐dimensional perovskite halides have shown a great potential as X‐ray detection materials because of efficient exciton emissions originating from strongly spatially localized charge carriers. Nonetheless, most of them have a scintillation yield far below their theoretical limits. Here, it is found that the harvesting efficiency of produced charge carriers can be significantly enhanced via a small amount of In+ doping in these highly localized structures. A bright and sensitive zero‐dimensional Cs3Cu2I5:In+ halide with efficient and tunable dual emission is reported. The radioluminescence emission of Cs3Cu2I5:In+ crystals under X‐ray excitation consists of a self‐trapped exciton emission at 460 nm and an In+‐related emission at 620 nm at room temperature. In+ doping enhances the photoluminescence quantum efficiency (PLQY) of Cs3Cu2I5 from 68.1% to 88.4%. Benefiting from the higher PLQY, Cs3Cu2I5:In+ can achieve an excellent X‐ray detection limit of 96.2 nGyair s−1, and a superior scintillation yield of 53 000 photons per MeV, which is comparable to commercial CsI:Tl single crystals. As a result, a remarkable X‐ray imaging resolution of 18 line pairs mm–1 is demonstrated, which is so far a record resolution for single crystal perovskite‐based flat‐panel detectors. These results highlight the importance of efficient harvesting of carriers (and excitons) in low‐dimensional perovskites for radiation detection applications. [ABSTRACT FROM AUTHOR]

The excellent optoelectronic properties and structural stability of inorganic cesium lead halide perovskites make them promising candidates for multiple types of optoelectronic devices. However, it remains a challenge to fabricate monocrystalline phase‐pure perovskite microstructures by facile low‐temperature solution‐based methods. Herein, a solution‐based method is demonstrated for controlling the crystallization of cesium halide perovskite microstructures. The structure of perovskite crystals is successfully tuned from non‐corner sharing Cs4PbBr6 (0D) to corner‐sharing CsPbBr3 (3D) to layered CsPb2Br5 (2D) by controlling water (H2O) to dimethylsulfoxide (DMSO) ratios. Molecular dynamics simulations and thermodynamic analysis indicate that the relative stability of Pb2+ and Br− ions in solution is the key factor in determining which crystals form at different H2O/DMSO ratios, with Cs+ simply incorporated as needed. The phase‐pure 0D crystals exhibit a high photoluminescence quantum yield of 41%, whilst the 2D crystals have an onset of absorption at 350 nm. Furthermore, the as‐synthesized, highly uniform 3D perovskite single crystals are coupled with nanofabricated interdigitated electrodes to show excellent X‐ray detection, with a high sensitivity of 8000 μC Gyair−1cm−2 obtained under a 0.5V external bias. This is comparable to many commercial X‐ray detectors (Si, α‐Se) and several times higher than other reported inorganic perovskite materials (CsPbBr3 quantum dots, Cs2AgBiBr6). [ABSTRACT FROM AUTHOR]

Hybrid bismuth halides perovskites have emerged as promising candidates for X‐ray detection, due to the strong absorptivity of high‐energy X‐ray photons, high resistivity, large carrier diffusion length and low toxicity. However, the mostly investigated hybrid bismuth iodides single crystals are usually opaque and require a harsh synthesis process. Herein, novel one‐dimensional (1D) pentamethylenediamine bismuth bromide (PDA)BiBr5 single crystals were synthesized via an antisolvent‐assisted crystallization method at room temperature. Bulk (PDA)BiBr5 single crystals have sizes of 10×1.3×1.5 mm3 and high transparency. They are shown to have low density of defects of 2.0×1010 cm−3 and obvious photoconductivity. Moreover, they exhibit large bulk resistivity of 2.13×1011 Ω cm and good X‐ray attenuation coefficient. Consequently, the vertical structured (PDA)BiBr5 single crystal X‐ray photoconductor produces a sensitivity of 3.8 μC Gyair−1 cm−2. This study provides a facile strategy for synthesizing bulk hybrid bismuth bromides single crystals with potential X‐ray detection application. [ABSTRACT FROM AUTHOR]

Halide perovskites exhibit diverse properties depending on their compositions. However, integrating desired properties into one material is still challenging. Here, a facile solution‐processed epitaxial growth method to grow 2D perovskite single crystal on top of 3D perovskite single crystal, which can passivate the surface defects for improved device performance is reported. Short formamidine (FA+) ions are replaced by long organic cations, which can fully align and cover the single crystal surface to prevent the ions migration or short FA+ ions volatilization. The thickness of epitaxial layer can be finely adjusted by controlling the growth time. The defect density of single crystals heterojunction is only 3.18 × 109 cm−3, and the carrier mobility is 80.43 cm2 V−1 s−1, which is greater than that of the control 3D perovskite single crystal. This study for the first time realized large area 3D/2D perovskite single crystals heterojunction, which suppressed ions migration and exhibited advanced performance in hard X‐rays detection applications. This strategy also provides a way to grow large area 2D perovskite single crystal from solution processes. [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]

Lone-pair Electrons Enhancement Effect: SnTe3O8 Hard X-ray Detection with Stable High-temperature Sensitivity and Ultralow Detection Limit (Adv. Funct. Keywords: 120 keV hard X-ray detections; high-temperature sensitivity; lone-pair electrons enhancement effects; tellurite oxide single crystals; ultralow detection limits; X-ray imaging EN 120 keV hard X-ray detections high-temperature sensitivity lone-pair electrons enhancement effects tellurite oxide single crystals ultralow detection limits X-ray imaging 1 1 1 07/06/23 20230704 NES 230704 B X-Ray Imaging b In article 2301002, Xutang Tao, Zeliang Gao, and co-workers report a novel high-temperature X-ray detection crystal of SnTe SB 3 sb O SB 8 sb . 120 keV hard X-ray detections, high-temperature sensitivity, lone-pair electrons enhancement effects, tellurite oxide single crystals, ultralow detection limits, X-ray imaging. [Extracted from the article]