X-ray detector, material for X-ray detection and its use for X-ray detection, as well as methods for its manufacture

Abstract

The invention relates to X-ray detectors comprising X-ray detector materials whose material composition includes salts of sulfonium cations, wherein the anions are preferably bismuth halides or bismuth-silver halides, in particular iodides. The invention further relates to the X-ray detector materials and their use for X-ray detection, together with a method for their production.

Description

background

[0001] High-performance, long-life semiconductor X-ray and gamma-ray detectors (X / y detectors) are well-established technologies and are used in medical imaging, non-destructive testing, security technology, the nuclear industry, and scientific research. Materials such as amorphous selenium (a-Se) and cadmium-zinc (Cd)Te, as described by A. Owens, are commonly used for the direct conversion of X-rays and gamma rays. These materials are known for their complex crystal growth processes and operational requirements, such as strong electric fields. Particularly in medical imaging, there is a significant need for detectors with improved sensitivity and lower detection limits compared to the current state of the art, as these would allow for the use of lower radiation doses and thus reduce patient exposure.Key performance indicators (KPIs) for X-ray detectors include sensitivity, limit of detection (LoD), mobility-life product (µτ), and resistivity. Sensitivity refers to the detector's ability to convert X-ray photons into an electrical signal, while the limit of detection (LoD) indicates the minimum detectable radiation above the background noise. Since 2013, there has been a resurgence in the field of novel X-ray detector materials, following the description of lead-based metal halide perovskites as promising alternatives for X-ray detection due to their high resistivity, excellent µτ products, high atomic numbers (Z), and ease of synthesis, as outlined by Y. He et al. However, their instability under ambient conditions remains a significant limitation (S. Shrestha).

[0002] An X-ray detector material within the meaning of the invention is any solid material, in particular any semiconductor, which is capable of converting X-rays either into electrical charge (electronic signal) or into photons that can be detected.

[0003] Organic-inorganic hybrid materials based on bismuth (Bi-based) have emerged as a promising alternative, offering superior thermal and humidity stability compared to lead-based perovskites (Y. Xu et al., M. Daum et al.). These materials are frequently synthesized using low-temperature and non-vacuum methods, making them a cost-effective option. In particular, Bi halides exhibit favorable band gaps (1.8–2.5 eV) and high atomic numbers (Z = 83 for Bi, Z = 53 for I), contributing to low thermal noise and high X-ray absorption.

[0004] Among the best-studied bi-halides is Cs₂AgBiBr₆, a double perovskite known for its indirect band gap, long charge carrier lifetime, and excellent stability. Cs₂AgBiBr₆ has been investigated as an X-ray detector in the form of single crystals (W. Pan), films (Y.C. Kim), and thick pellets (B. Yang), exhibiting sensitivities up to 1974 µC·Gy. air -1 ·cm -2 in single-crystal detectors. Furthermore, other Bi-based materials such as MA3Bi2I9, BiOl, Cs3Bi2I9 and Rb3Bi2I9 have shown promising properties, with reported sensitivities of up to 10620 µC·Gy. air -1 ·cm -2for MA3Bi2I9 in single-crystal form. Single crystals (SCs) generally outperform amorphous or polycrystalline materials due to their superior crystal quality, absence of grain boundaries, and minimal defects (Y. Song et al.). However, scaling up single crystals for practical applications remains a challenge due to the difficulty of growing large crystals using conventional techniques such as the Bridgman and Czochralski methods, which are both time-consuming and expensive, thus limiting their scalability for practical use.

[0005] In contrast, polycrystalline pellets (cylindrical bodies of densified polycrystalline material) represent a practical alternative for flat-panel X-ray detectors because they can be produced quickly and cost-effectively by hydraulic compression, enabling the fabrication of thick X-ray detector materials essential for effective X-ray absorption. Although pellets generally exhibit lower performance than single crystals due to the presence of grain boundaries, which are known sites of recombination loss, recent studies have shown that pellet-based bi-based materials nevertheless exhibit promising sensitivities and levels of detection (LoD), often outperforming traditional materials such as α-Se and Cd(Zn)Te.Furthermore, lead-based perovskites such as MAPbI3 in pellet form have shown comparable results, which further promotes research in this area, although the materials are harmful to the environment and health.

[0006] An X-ray detector according to the invention comprises at least one X-ray detector material and any means for converting an electronic signal or light from the X-ray detector material caused by the incidence of X-rays. The simplest form of an X-ray detector consists of an X-ray detector material between two electrically contacted metal plates that transmit any signal from the material and may apply a bias voltage. The electrodes can be made, for example, from a material of the group consisting of Au, Ag, Al, Pt, Pd, In, C, graphene, graphite, carbon nanotubes (CNTs), carbon black, ITO (indium tin oxide), FTO (fluorine-doped tin oxide), IZO (indium zinc oxide), AZO (aluminum-doped zinc oxide), Cr, Ni, Cu, Mo, W, Ti, Bi, and Sn.

[0007] Based on the above-mentioned prior art, the objective of the present invention is to provide more environmentally friendly X-ray detector materials that can be produced by simple, scalable and solvent-free processes and that exhibit high sensitivity and low detection limits, particularly at low X-ray doses and low photon energies, while also showing long-term operational stability.

[0008] This objective is achieved by the subject matter of the independent claims, with further advantageous embodiments being described in the dependent claims, examples, figures and the general description. Summary of the invention

[0009] In the search for materials that would solve the problem addressed by the invention, the applicant surprisingly identified materials whose composition includes sulfonium salts. The anions are preferably bismuth halides or bismuth-silver halides; iodides are particularly advantageous for the anions, since iodine is a good absorber (high Z) and, moreover, is not radioactive.

[0010] A characteristic feature of the X-ray detector material according to the invention is the incorporation of sulfonium [R3S] + , for example triethylsulfonium [Et3 S] + , which accounts for the remarkable performance with sensitivities of up to 15,190 µC·Gy air -1 ·cm -2 and detection limits of 78 nGy air ·s -1

[0011] For the crystalline substance with the formula [Et3 S]AgBiI5, a sensitivity of up to 7.5·10⁻⁵ was found. 5 µC·Gy air-1 ·cm -2 proven.

[0012] The claimed X-ray detector materials show good performance when using different X-ray energy sources (Cu and W, using different energies and “radiation types”, pulsed vs. continuous), making the materials ideally suited for a wide range of applications, including low energy ranges (scientific instruments) and medical imaging.

[0013] In the context of the "hard-soft acid base" (HSAB) theory, sulfonium cations (R3S) + Soft Lewis acids, while ammonium cations are hard. Since iodobismuthate anions are dominated by soft iodide ligands, soft sulfonium-ilodide interactions are expected to be more favorable than the hard interactions with ammonium. Without committing to the theory, it is assumed that sulfonium cations (R3S) +The soft Lewis acids interact favorably with the soft iodide ligands of the iodobismuth anions, which can contribute to closer ion pairing and improved structural and environmental stability. This is consistent with the improved moisture resistance and long-term X-ray sensitivity observed for the sulfonium-based Ag / Bi-I and Bi-I materials according to the invention. Significantly, the positively charged sulfur atom interacts directly with the iodide atoms, which likely promotes the favorable detector properties. Description of the solution

[0014] The solution for the above-mentioned objective of the invention is provided in a first aspect by an X-ray detector comprising an X-ray detector material containing salts of sulfonium cations [R3 S] +with bismuth halides or bismuth-silver halides, especially iodides, as anions. In particular, the X-ray detector materials are comprised of materials of the formula [R3S]6Bi e I 30 or [R3S]AgBiI3, in particular [Et3S]6Bi8I 30 or [Et3S]AgBiI5. The solution to the problem is provided in a second aspect by the X-ray detector material defined above itself, and in a third aspect by its use for X-ray detection, particularly for X-rays in the range of 100 eV to 120 keV. The X-ray detector materials according to the invention are particularly well suited for energies in the range of 100 eV to 40 keV, since they are superior to prior art X-ray detector materials, especially in this range.

[0015] In the context of the present invention, ‘sulfonium cation’ refers to a cation of the formula [R1R2R3S] +, where R1, R2 and R3 are independently given by C1-C4 alkyl groups.

[0016] Possible sulfonium cations are given by the following two groups of symmetric and asymmetric sulfonium cations, which together again form a group of sulfonium cations: Symmetric cations (R1=R2=R3): • trimethylsulfonium - [Me3S] + • Triethylsulfonium - [Et3S] + • Tripropylsulfonium - [n-Pr3S] + • Triisopropylsulfonium - [i-Pr3S] + • Tributylsulfonium - [n-Bu3S] + Asymmetric connections (R1, R2, R3 are different): • Dimethylethylsulfonium - [Me2EtS] + • Methyldiethylsulfonium - [MeEt2S] + • Methyl-ethyl-propylsulfonium - [MeEtPrS] + • Methyl-di(n-propyl)sulfonium - [Me(n-Pr)2S] + • Methyl-di(n-butyl)sulfonium - [Me(n-Bu)2S] + • Ethyl-di(n-propyl)sulfonium - [Et(n-Pr)2S] + • Methyl-ethyl-isopropylsulfonium - [MeEt(i-Pr)S] + Methyl-ethyl-butylsulfonium - [MeEt(n-Bu)S] + .

[0017] In Fig. Figure 1 presents the X-ray detector materials known from the prior art, together with examples of the material used in the X-ray detector according to the invention, with respect to their sensitivities and detection limits. The same information is given in Table 1 (at the end of this document).

[0018] The materials in the form of pressed pellets made from polycrystalline powder can be produced by a process that includes at least the following steps: a. Providing powdered precursors BiI3, Agl and sulfonium halide in stoichiometric amounts, b. Mixing or grinding the powders. c. Pressing the mixed or ground powders from step b.

[0019] The sulfonium halide is in particular an iodide, and the sulfonium cation is selected, for example, from one of the groups defined above.

[0020] The pressing of the mixed or milled powders in step c. is carried out at a pressure in the range of 0.2 to 1.2 GPa for a period of 5 seconds to 600 seconds. The milling process mixes the powders, and furthermore, the precursors react at least partially mechanochemically to form the crystallized substances, for example, [Et3S]6Bi6I. 30 or [Et3S]AgBiI3. According to the invention, the grinding is carried out dry and without additives, which is an advantage of the invention.

[0021] The grinding process is carried out in a ball mill at an ambient temperature in the range of 1 °C to 45 °C, with a grinding frequency in the range of 1 Hz to 600 Hz and for a period of time in the range of 1 min to 600 min.

[0022] Any other mill that operates on the principle of grinding, such as hand grinding in a mortar, using a disc mill, or an IsaMill, is also suitable. Using a ball mill is advantageous because it is easy to handle and the parameters can be adjusted over a wide range.

[0023] The pellets obtained in step c), which are to be used in X-ray detectors, advantageously have diameters of 1 mm to 100 mm and a thickness in the range of 0.1 mm to 5 mm.

[0024] The X-ray detector materials according to the invention can be produced by the method described above, which is a straightforward, cost-effective and environmentally friendly process, since no solvents are used.

[0025] Alternatively, single crystals of the desired compounds can be produced using methods known from the prior art, for example from ionic liquids or solutions. Detailed description of the invention

[0026] The invention is further illustrated by the following examples and figures, from which further embodiments and advantages can be derived. These examples serve to illustrate the invention but do not limit its scope. Table 1

[0027] Performance data of X-ray detectors based on materials characterized as compressed pellets or single crystals, together with references. Description of the characters Fig. 1 Performance data of X-ray detector materials of organic-inorganic hybrid materials based on compressed pellets (CP), solution-grown single crystals (SC), commercially available amorphous selenium (a-Se) and polycrystalline CdZnTe with sensitivities and detection limits reported in the literature in comparison to the results obtained in this work for [Et3 S]6 Bi8 I 30 and [Et3 S]AgBiI5, which were pressed into pellets, as well as for [Et3 S]AgBiI3 as a single crystal. Fig. 2. Production and characterization of [Et3 S]6Bi8I 30and [Et3S]AgBiI3. a) Schematic representation of the manufacturing process in which the precursor powders were first synthesized by ball milling and then subjected to a pressure of ~1 GPa using a hydraulic press, followed by the deposition of gold contacts. b) and c) Experimental and simulated powder X-ray diffraction pattern of [Et3S]6Bi8I 30 and [Et3 S]AgBils. Fig. 3 Performance characteristics of the X-ray detector materials according to the invention in X-ray detectors: a) Au / [Et3S]6Bi8I 30 / Au detector - X-ray-induced signal (photocurrent) at different dose rates at a given bias voltage of 20 V. The mean values ​​of the photocurrent and dark current are shown by dashed lines; b) Dose rate-dependent photocurrent (circles) and sensitivity (squares) of the X-ray detectors Au / [Et3S]AgBiI5 / Au (filled symbols) and Au / [Et3S]6Bi8I 30 / Au (open symbols) at a bias voltage of 200 V. Approximations of the dependencies I Signal ~ D Luft α Solid lines represent the X-ray dose-rate-dependent signal-to-noise ratio of the detectors under a bias voltage of 1 to 200 V. The dashed line represents a signal-to-noise ratio of 3, and the detection limits are in the range of (100-200) nGy. air ·s -1 and (50-100) nGy air ·s -1 for the detectors based on [Et3 S]6Bi8I 30 or [Et3 S]AgBiI5. e) and f) Distribution of the limit of detection of two sets of pellets made from [Et3 S]6Bi8I 30 (e) and [Et3 S]AgBiI3 (f) under bias voltages of 100 V and 200 V. Each data point represents the data of one device. The mean values ​​of the detection limit are marked with asterisks. Examples

[0028] In the examples, the powdered precursors BiI3, Agl, and [Et3S]I were mixed in stoichiometric amounts of [Et3S]I : Bil3 = 6:8 and [Et3S]I : Bil3 : Agl = 1:1:1 and milled for one hour according to the following recipe. The precursor salts were mixed in stoichiometric amounts in 10-ml stainless steel vessels for solvent-free mechanosynthesis. The reactions were carried out by pure milling in a vibratory ball mill (Pulverisette 23, Fritsch) at 50 Hz for one hour under ambient conditions to obtain polycrystalline powders of [Et3S]6Bi8I. 30 (e) and [Et3S]AgBil5. This led to the formation of polycrystalline material, which was identified by powder X-ray diffraction (PXRD) ( Fig. 2b and c). The PXRD diffractograms agree with the simulations obtained from the structure refinement of the single-crystal X-ray (SC) data of [Et3S]6Bi8I 30 were won. [Et3S]6Bi8I 30[Et3S]AgBiI5 proved to be phase-pure, while minor crystalline impurities were detected in [Et3S]AgBiI5. To produce compressed pellets from each material, the powders were placed in a 10 mm die set and pressed in a hydraulic press (MP150D, Maassen) for 30 seconds at a pressure of 8 tons. The resulting powders were compressed at room temperature (20 °C) and a pressure of approximately 1 GPa into pellets with a thickness between 0.5 and 5 mm and characterized in X-ray detectors. Fig. Figure 2a illustrates the fabrication process of the X-ray detectors. Single crystals of [Et3S]AgBiI5 were grown in parallel. Band gap estimation using diffuse reflection spectroscopy in combination with the Kubelka-Munk function yielded band gaps of 1.80 eV for [Et3S]AgBiI5 and 1.98 eV for [Et3S]6Bi8I 30, which are optimal for X-ray detection applications. These values ​​indicate effective absorption of X-ray photons and the generation of electron-hole pairs while simultaneously minimizing thermal noise. The following sections describe in detail the evaluation of the performance of these materials as X-ray detectors.

[0029] Single crystals of [Et3S]AgBiI3 were grown according to the following procedure. [Et3S]I (1 Eq.) and I2 (2 Eq.) powders were placed in a 4.5 mL vial and allowed to stand for one minute to form a melt. Subsequently, Agl (0.2 Eq.) and Bil3 (0.2 Eq.) powders were added to the mixture and shaken on a shaker at 80 °C for 30 minutes, after which the mixture was placed in an undisturbed location. After about five months, red rhombohedral crystals with dimensions of approximately 5 × 4 × 1 mm were hand-selected for subsequent characterization in an X-ray detector.

[0030] Sensitivity and limits of detection (LoD) are important key performance indicators (KPIs) for X-ray detectors. The sensitivity of the [Et3S]6Bi6I 30 and [Et3S]AgBiI5-based pellets in X-ray detectors for Cu-Kα X-ray photons (8.04 keV) and synchrotron radiation with photon energies of 8 keV and 12 keV were determined. In practice, it is important that these detectors can detect X-rays with the lowest possible dose rates that the experimental setups used can generate. These are approximately 20 times lower than the typical medical diagnostic dose rate of 5.5 µGy. air ·s -1 (dashed line in Fig. 1) and thus contribute to minimizing radiation exposure. The X-ray photocurrent shows a good on-off response, which increased with both the dose rate and the applied electric field (not shown). The response time was limited only by the switching time of the X-ray source.

[0031] The signal current (I signal ) was calculated by determining the average dark current (I̅ dark ) of the average photocurrent (I̅ photo ) was subtracted. The relationship between I signal and dose rate follows a sublinear power law, I signal ~ D air α with α values ​​of 0.71±0.05 for Au / [Et3S]6Bi8I 30 / Au and 0.69±0.05 for Au / [Et3S]AgBiI5 / Au, which probably indicates charge carrier trapping.

[0032] The X-ray sensitivity S is defined as the current density per unit radiation exposure and was determined for the compressed pellets of both materials as well as for single crystals of [Et3 S]AgBil (5) measured. As expected from the µτ determination in the previous section, the single crystals exhibit a significantly higher sensitivity, approximately 50 times greater than that of the compressed pellets, which corresponds well with the Fig. The trend shown in point 1 is consistent. The sensitivity reached 7.5 x 10⁻⁵. 3 µC·Gy air -1 ·cm -2 for the [Et3S]AgBiI5 single crystal, compared to (1.4-1.5)·10 4 µC·Gy air -1 ·cm -2 for the compressed pellets at low radiation intensities. To our knowledge, the latter sensitivities are the highest reported to date for compressed bismuth-based pellets ( Fig. 1) Despite the significantly better performance of single crystals, the simpler and more readily available

[0033] The production of compressed pellets results in a loss of sensitivity, as they still have a sensitivity of 10. 4 µC·Gy air -1 ·cm -2 They offer output regardless of the dose rate within the range used for medical imaging. This independence simplifies operation and eliminates the need for complex calibration of the signal output to dose rates, thus increasing their potential for medical applications.

[0034] In summary, it can be said that the [Et3S]6Bi8I 30 and [Et3S]AgBil3 based X-ray detectors exhibit a remarkable sensitivity that surpasses other Bi-based materials such as Cs3Bi2I9, Cs2AgBiBr6, BiVO4 and most lead-based perovskites (e.g. MAPbI3 in pellet form) Fig. 1) At 200 V and a dose rate of 321 nGy air ·s -1 The sensitivity is about 40 times higher than that of polycrystalline Cd(Zn)Te (318 µC·Gy). air 1 ·cm -2 ) and about 700 times higher than with a-Se detectors (20 µC·Gy) air 1 ·cm -2 ), which have much stronger electric fields (10,000 V·mm) -1 This can be explained by the presence of photoconductive gain in the X-ray detector materials along with a µτ product that is several orders of magnitude higher than that of α-Se. It is suggested that charge carrier traps within the X-ray detector materials are responsible for inducing this gain under high bias (see Methods for details).

[0035] The detection limit ( Fig. 3 e) and f)), another important KPI, particularly for medical imaging and safety controls, was determined according to the IUPAC standard, where the limit of detection is defined as the dose rate at which the signal-to-noise ratio (SNR) is equal to 3. The mean values ​​for the limit of detection were 90 nGy. air ·s -1 for [Et3S]6Bi8I 30 and 78 nGy air ·s -1 for [Et3S]AgBiI5 (pressed pellets), slightly higher than for [Et3S]AgBil5 single crystals (~10-20 nGy) air ·s -1 ), but comparable to other Bi-based detectors based on pressed pellets ( Fig. 1, Table 1). These values ​​are 2-4 times lower than those for Pb-based perovskite pellets and 55-500 times lower than for a-Se and Cd(Zn)Te detectors ( Fig. 1).

[0036] The estimated detection limit of these detectors is approximately 60 to 70 times lower than the threshold required for medical diagnostics, thus enabling a reduction in radiation dose during routine X-ray examinations and consequently lowering the risk of radiation-induced cancers. Increasing the electric field does not significantly improve the detection limit but does increase the sensitivity to 14,100–15,190 µC·Gy. air -1 ·cm -2 at a dose rate of 321 nGy air ·s -1 Even at low bias voltages (e.g., 40 V), the detection limit remains favorable, with the sensitivity only reduced by a factor of four and a high range of 3,000–5,000 µC·Gy. air -1 ·cm -2is maintained. This robust sensitivity at reduced electric fields underscores the suitability of the detectors for low-dose X-ray applications without compromising detection efficiency. The X-ray photocurrent exhibited a good on / off response, which correlated with both the dose rate and the... Fig. 3 a), b) shown, as well as increasing with the applied electric field (not shown). The reaction time was limited only by the switching time of the X-ray source.

[0037] Upon irradiation with a copper X-ray tube, which is commonly used for non-destructive testing, the Bi-based pellets according to the invention – in particular compounds (1) and (2) – exhibit a higher sensitivity to X-ray photons than all other known pellets. Furthermore, the [Et3S]AgBil5 single crystals (3) grown from an ionic liquid outperform all previously described materials, both single crystals and compressed pellets ( Fig. 1, Table 1).

[0038] The exceptional sensitivity and low detection limits observed even at moderate X-ray energies underscore the potential of the X-ray detector materials according to the invention for a wide range of applications, including security checks, elemental analysis, and especially medical imaging. Their performance advantage is likely due to unique structural features, such as the short layer distances between the inorganic components, which have proven crucial for improving X-ray detection capabilities.

[0039] The X-ray detector materials according to the invention [Et3S ] AgBiI5 (1) and [Et3S]6Bi8I 30(2) Compared to other known lead-free compressed pellets, they exhibit lower detection limits and higher sensitivity to X-rays generated by a tungsten tube operated at 70 kV (typical conditions for medical imaging and widely used in X-ray radiography) ( Fig. 1) Its performance is surpassed only by that of the lead-containing compressed pellet MAPbI3. Furthermore, our Bi-based [Et3S]AgBil5 single crystal (3) exhibits a significantly higher sensitivity to photons in this energy range than all previously described compressed pellets or single crystals ( Fig. 1).

[0040] The environmental stability of perovskite-based devices is a known challenge due to performance degradation during aging. However, bi-based detectors have demonstrated promising long-term stability and self-healing properties, which we have demonstrated in the Au / [Et3S]6Bi8I according to the invention. 30 We also investigated / Au and Au / [Et3S]AgBil5 / Au detectors. These detectors were stored for 12 months under ambient conditions (~21 °C, 70% relative humidity) without protective encapsulation. Remarkably, their performance remained stable, with only minimal changes in sensitivity and detection limit over time.

[0041] The X-ray detectors according to the invention, which use the claimed materials, initially exhibit an exponential decrease in dark current under a bias voltage of 200 V, followed by stabilization after approximately 5 minutes, with equilibrium being reached within 20 to 30 minutes. The stabilized dark current averaged 2.71 nA and 6.18 nA for Au / [Et3S]AgBiI5 / Au and Au / [Et3S]6Bi8I, respectively. 30 / Au. Current drift values ​​of ΔI = 7.8·10 were measured. -6 nA·cm -1 ·s -1 ·V -1 for Au / [Et3 S]6Bi8I 30 / Au and ΔI = 1.87·10 -6 nA·cm -1 ·s -1 ·V -1 for Au / [Et3S]AgBil3 / Au, which are practically negligible and in the same range as post-treated materials, such as BiOBr-passivated Cs2AgBiBr6 and BiVO4 pellets. The detectors Au / [Et3S]AgBiI5 / Au and Au / [Et3S]6Bi8I 30 / Au also exhibits good stability under uniform X-ray radiation. Under a pre-voltage of 200 V and an X-ray radiation of 3059,418 µGy air ·s -1 The detectors deliver a stable photocurrent for 2000 s (total X-ray dose of 1260 mGy). air ), which corresponds to the dose of 340 digital mammography examinations with two images.

[0042] Even under long-term synchrotron irradiation, the detectors showed stable performance with high signal-to-noise ratios over a period of 7 hours ( Fig. 3 c) and d)) and minimal baseline deviation. In particular the Au / [Et3 S]6Bi8I 30 The Au detector showed a baseline deviation of 1.07·10 -7 nA·cm -1 ·s -1 ·V -1This is about eight times less than with BiOBr-passivated Cs2AgBiBr6 devices. All detectors maintained a constant signal-to-noise ratio of 17.7 on average and stable light sensitivity throughout the entire test period, highlighting the robustness of the detectors even 12 months after their manufacture.

[0043] The impressive stability of these materials is likely due to their structural properties, with sulfonium cations offering greater stability than ammonium cations by minimizing hydrogen bonding and thus improving moisture stability. Furthermore, short interlayer distances between the inorganic components probably contribute to the robustness of the materials.

[0044] Overall, the X-ray detector materials according to the invention combine long-term stability and cost and energy efficiency with remarkable X-ray sensitivity and, compared to the prior art, show an effective response to both high-energy radiation from a tungsten tube (WT). α = 59.3 keV) as well as low-energy radiation from a copper tube (Cu K α ) = 8.04 keV). Documents cited regarding the state of the art: Owens, A. Semiconductor materials and radiation detection. J Synchrotron Radiat 13, 143-150 (2006). He, Y., Hadar, I. & Kanatzidis, MG Detecting ionizing radiation using halide perovskite semiconductors processed through solution and alternative methods. Nat Photonics 16, 14-26 (2022). Shrestha, S. et al. High-performance direct conversion X-ray detectors based on sintered hybrid lead triiodide perovskite wafers. Nat Photonics 11, 436-440 (2017). Xu, Y. et al. Zero-Dimensional Cs2Tel6 Perovskite: Solution-Processed Thick Films with High X-ray Sensitivity. ACS Photonics 6, 196-203 (2019). Daum, M. et al. Self-Healing Cs3Bi2Br316 Perovskite Wafers for X-Ray Detection. Adv Funct Mater 31, (2021). Pan, W. et al. Cs2AgBiBr6 single-crystal X-ray detectors with a low detection limit. Nat Photonics 11, 726-732 (2017) Kim, Y. C. et al. Printable organometallic perovskite enables large-area, low-dose X-ray imaging. Nature 550, 87-91 (2017) Yang, B. et al. Heteroepitaxial passivation of Cs2AgBiBr6 wafers with suppressed ionic migration for X-ray imaging. Nat Commun 10, 1989 (2019) Song, Y. et al. Atomistic Surface Passivation of CH3NH3Pbl3 Perovskite Single Crystals for Highly Sensitive Coplanar-Structure X-Ray Detectors. Research 2020, (2020) Starkholm, A. “Synthesis and Robotized Screening of Novel Perovskite Materials for Solar Cell Application”, Doctoral thesis, KTH royal institute of technology, Stockholm, Sweden 2021 QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] Y. Xu et al., M. Daum et al.

[0003] Owens, A. Semiconductor materials and radiation detection. J Synchrotron Radiat 13, 143-150 (2006

[0044] He, Y., Hadar, I. & Kanatzidis, M. G. Detecting ionizing radiation using halide perovskite semiconductors processed through solution and alternative methods. Nat Photonics 16, 14-26 (2022

[0044] Shrestha, S. et al. High-performance direct conversion X-ray detectors based on sintered hybrid lead triiodide perovskite wafers. Nat Photonics 11, 436-440 (2017

[0044] Xu, Y. et al. Zero-Dimensional Cs2Tel6 Perovskite: Solution-Processed Thick Films with High X-ray Sensitivity. ACS Photonics 6, 196-203 (2019

[0044] Daum, M. et al. Self-Healing Cs3Bi2Br316 Perovskite Wafers for X-Ray Detection. Adv Funct Mater 31, (2021

[0044] Pan, W. et al. Cs2AgBiBr6 single-crystal X-ray detectors with a low detection limit. Nat Photonics 11, 726-732 (2017

[0044] Kim, Y. C. et al. Printable organometallic perovskite enables large-area, low-dose X-ray imaging. Nature 550, 87-91 (2017

[0044] Yang, B. et al. Heteroepitaxial passivation of Cs2AgBiBr6 wafers with suppressed ionic migration for X-ray imaging. Nat Commun 10, 1989 (2019

[0044] Song, Y. et al. Atomistic Surface Passivation of CH3NH3Pbl3 Perovskite Single Crystals for Highly Sensitive Coplanar-Structure X-Ray Detectors. Research 2020, (2020

[0044] Starkholm, A. „Synthesis and Robotized Screening of Novel Perovskite Materials for Solar Cell Application“, Doctoral thesis, KTH royal institute of technology, Stockholm, Sweden 2021

[0044]

Claims

[1] X-ray detector comprising an X-ray detector material comprising at least one salt of sulfonium cation and bismuth halides or bismuth silver halides as anions. [2] X-ray detector according to claim 1, characterized by that the X-ray detection material contains at least [R3S]6Bi8I 30 or [R3S]AgBil5 comprising, wherein R is at least one of the group formed from trimethylsulfonium [Me3S] + , Triethylsulfonium [Et3S] + , Tripropylsulfonium [n-Pr3S] + , triisopropylsulfonium [i-Pr3S] + , Tributylsulfonium [n-Bu3S] + , dimethylethylsulfonium [Me2EtS] + , Methyldiethylsulfonium [MeEt2S] + , Methyl-ethyl-propylsulfonium [MeEtPrS] + , Methyl-di(n-propyl)sulfonium [Me(n-Pr)2S] + , Methyl-di(n-butyl)sulfonium [Me(n-Bu)2S] + , Ethyl-di(n-propyl)sulfonium [Et(n-Pr)2S] + , Methyl-ethyl-isopropylsulfonium [MeEt(i-Pr)S] +and methyl-ethyl-butylsulfonium [MeEt(n-Bu)S] + includes. [3] X-ray detector according to claim 1 or 2, characterized by that the X-ray detector material is at least [Et3 S]6 Bi8 I 30 or includes [Et3 S]AgBil5. [4] X-ray detector according to any one of the preceding claims, characterized by that the X-ray detector material is in pellet form. [5] X-ray detector according to claim 4, characterized by that the pellet has a thickness in the range of 0.5 to 5 mm. [6] X-ray detector according to claim 1, 2 or 3, characterized by that the material exists as a single crystal. [7] X-ray detection material comprising at least one salt of sulfonium cation and bismuth halides or bismuth silver halides as anions. [8] Use of material for X-ray detection comprising at least one salt of a sulfonium cation with bismuth halides or bismuth silver halides as anions in an energy range of X-rays between 100 eV and 120 keV, in particular 100 eV and 40 keV. [9] Method for producing pressed powder pellets comprising at least one salt of a sulfonium cation and bismuth halides or bismuth silver halides as anions, by the following steps: a. Providing powdered BiI3, Agl and sulfonium halide as precursors in stoichiometric amounts, b. Mixing or grinding the powders, c. Pressing the mixed or ground powders from step b. with a pressure in the range of 0.2 to 1.2 GPa for a period of time in the range of 5 seconds to 600 seconds.

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