Detection layer comprising perovskite crystals, method for producing a detection layer, coated scintillator particle, method for producing a detector, and detector

Abstract

Detector, in particular for X-rays, comprising at least two electrodes and at least one detection layer placed between the at least two electrodes, comprising perovskite crystals of type ABX3, wherein A is at least one monovalent, divalent or trivalent element from the 4th atom onwards.A period of the periodic table and / or mixtures thereof, preferably Sn, Ba, Pb, Bi; B represents a monovalent cation whose volume parameter for the respective element A satisfies perovskite lattice formation, preferably monovalent, amino-group-containing, positively charged carbon compounds, more preferably amidinium ions, guanidinium ions, isothiuronium ions, formamidinium ions, as well as primary, secondary, tertiary, and quaternary organic ammonium ions, particularly preferably with 1 to 10 carbons; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide, and iodide as well as mixtures thereof, wherein the layer has a thickness of at least 10 µm, preferably at least 20 µm, and more preferably at least 100 µm.

Description

[0001] The present invention relates to a detection layer on a substrate comprising perovskite crystals of type ABX3 and / or AB2X4, wherein A represents at least one monovalent, divalent or trivalent element from the 4th period of the periodic table, preferably Sn, Ba, Pb and Bi; B represents a monovalent cation whose volume parameter for the respective element A satisfies perovskite lattice formation; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide and iodide as well as mixtures thereof, a method for producing the detection layer, particles coated with the perovskite crystals and detectors with the detection layers according to the invention.

[0002] The invention addresses a novel manufacturing method for digital X-ray detectors, such as those used in medical diagnostics. These detectors typically measure between 20 × 20 cm. 2and 43 × 43 cm 2 The current state of the art is represented by detectors based on amorphous silicon (indirect conversion) and amorphous selenium (direct conversion). The principles for direct conversion (I) and indirect conversion (II) are described in Fig. 1 shown. In the direct conversion I, an X-ray quantum excites 1 a particle 2 on, where electron / hole pairs 2a , 2b are generated, which then go to the electrodes 4 (Anode or cathode, for example pixel electrodes) migrate and are detected there. In indirect conversion II, the X-ray quantum excites 1 the particle 2 on, which in turn radiation 2‘ emits lower energy (e.g., visible light, UV or IR radiation), which is then detected by a photodetector 3 (e.g., photodiode) is detected.

[0003] Indirect X-ray conversion involves combining a scintillator layer (e.g., Gd₂O₂S or CsI with various dopants such as terbium, thallium, europium, etc.; layer thicknesses typically 0.1–1 mm) and a photodetector (preferably a photodiode). The emission wavelength of the scintillator light through X-ray conversion is matched to the spectral sensitivity of the photodetector.

[0004] In the case of direct X-ray conversion, the X-rays are directly converted into electron / hole pairs, which are then read out electronically (e.g., amorphous selenium). Direct X-ray conversion in selenium is typically performed with layers up to 1 mm thick, which are reverse-biased in the kV range. While indirectly converting detectors have become prevalent, primarily due to their ease and cost-effectiveness, direct converters offer significantly better resolution.

[0005] An alternative to the aforementioned inorganic semiconductor-based X-ray detectors are hybrid-organic detectors, which are typically manufactured by liquid-phase application. This allows for particularly easy processing on large areas of up to 43 × 43 cm. 2 or more. Detector fabrication typically involves incorporating inorganic absorber materials, such as quantum dots or typical scintillator materials, into an organic matrix. Organic semiconductors can be easily applied from the liquid phase to large areas, and the direct incorporation of the inorganic scintillator grains significantly minimizes optical crosstalk.

[0006] Organic semiconductors, unlike inorganic semiconductors, exhibit lower conductivity. This limited conductivity becomes problematic when, as in X-ray absorption, very thick layers are required to achieve sufficient sensitivity. On the one hand, this reduces the efficiency of the photodiode because charge carrier extraction is hindered; on the other hand, it decreases the photodiode's speed, limiting its use in medical devices, for example, in mammography, where only soft X-rays with shallow penetration depth are used.

[0007] Organic semiconductors are predominantly applied from the liquid phase or evaporated under vacuum. All currently known methods for incorporating inorganic absorber materials utilize liquid-phase processing. US 6483099 B1 describes the possibility of X-ray detection using a scintillator layer on an OPD (organic photodiode). Further details include X-ray detection by admixture of scintillators into an OPD, using the scintillator as a substrate, or as part of the electrode. However, no information is provided on how a scintillator can be homogeneously incorporated into a thick OPD layer or how, for example, a 100 µm thick hybrid diode can be fabricated.

[0008] DE 101 37 012 A1 discloses an embodiment of a light-sensitive polymeric absorber layer with embedded scintillator grains. The conductivity of the polymer layer increases through absorption of light from the scintillator. The mean spacing of the scintillator grains in the layer corresponds to the mean free path of the photons from the scintillator in the polymer.

[0009] German patent DE 10 2008 029 782 A1 describes an X-ray detector based on quantum dots mixed into an organic semiconductor matrix. In this concept, the quantum dots are dispersed in the organic semiconductor solution. Oleic acid or similar substances are used, which can influence the electrical properties of the organic semiconductor.

[0010] DE 10 2010 043 749 A1 relates to an X-ray detector based on the concept described above, wherein scintillators are either dispersed directly into the organic semiconductor solution or are sprayed on simultaneously with the organic semiconductor material in a “co-spray process”.

[0011] In the first case of liquid-phase application, the challenge lies in producing a stable dispersion, which proves particularly difficult for large scintillator particles. For small particles, dispersants are typically added to prevent clumping, but these negatively affect the electrical properties of the organic semiconductors.

[0012] Both processes (liquid-phase application and vacuum evaporation) have the disadvantage that the application of very thick layers (100 µm or more) requires the release of enormous quantities of solvents, and the layers exhibit high surface roughness. Complete solvent evaporation is not only a technical challenge but also poses a critical health and environmental problem.

[0013] Some initial publications show that materials processed from a solution form perovskite lattice layers. Examples from publications include: • MeNH3I:PbI2 • (CH3NH3)Pb(I, Br)3 (Dirin et al. 2014, DOI: 10.1021 / ja5006288) • CH3NH3SnI3 (Noel et al. 2014, DOI: 10.1039 / c4ee01076k) • (CH3CH2NH3)PbI3 (Im et al. 2014, DOI: 10.1186 / 1556-276X- 7-353)

[0014] These materials exhibit significantly higher charge carrier mobility than organic semiconductors and possess a high X-ray absorption cross-section. However, the materials known from the literature are used in processes developed for solar cell research (e.g., spin coating, doctor blade coating, slot coating, spray coating, or vapor deposition) and typically only have a layer thickness between 100 and 500 nm. Processing these methods into thicker layers quickly reaches technological and economic limits.

[0015] Polycrystalline or monocrystalline perovskite absorber layers for use in solar cells are typically applied from the liquid phase (e.g., spin coating, doctor blade application, or spraying) or deposited in a vacuum process (e.g., PVD). In both cases, the crystalline structure forms directly on the substrate during drying or deposition. Furthermore, the incorporation of inorganic absorber materials (scintillators) into the liquid phase or into a polycrystalline perovskite powder has not yet been described.

[0016] Previously known methods for producing absorber powders and for mixing in inorganic absorbers relate to organic materials.

[0017] For example, DE 10 2013 226 339.2 presents a process ("soft sintering") in which an organic photodiode is processed from a dry powder. This process avoids the disadvantages mentioned above. In contrast to this process, the objective of the invention formulated here is to provide an X-ray-sensitive material that can be processed using the sintering process.

[0018] German patent application DE 10 2014 212 424.7 describes a process which, in a first step, involves the production of core-shell powders and, in a second step, the pressing of the powders into a homogeneous film. These powders consist of particles that have a coating of organic semiconductor materials.

[0019] It is therefore an object of the present invention to provide a detection layer, in particular for an X-ray detector, with increased efficiency and good conductivity in the detection layer, which leads to improved images even at lower irradiation and is therefore gentler on the objects or subjects to be examined.

[0020] The inventors have discovered that a material crystallized in a perovskite lattice layer, in addition to absorbing visible light and X-rays, also exhibits good electrical conductivity of the generated charge carrier pairs and high mobility, for example up to 50 cm. 2 / Vs, shows.

[0021] They discovered, in particular, that this effect can be used in a detection layer. The detection layer can comprise a material based on a homogeneous, mono- or polycrystalline powder crystallizing in a perovskite lattice; or on a homogeneous powder consisting of scintillators, for example, inorganic X-ray absorbers such as quantum dots and / or other known scintillators, and a material that, in its modified form as a perovskite lattice structure, adhesively encapsulates the scintillators or X-ray absorbers; or on a homogeneous powder consisting of a mixture of two types of particles: on the one hand, scintillators, for example, inorganic X-ray absorbers such as quantum dots or other known scintillators, and on the other hand, homogeneous, mono- or polycrystalline particles crystallizing in a perovskite lattice.

[0022] The detection layers according to the invention can absorb not only visible light but also X-rays and convert them into an electrical signal.

[0023] In addition, an effective method for producing the detection layers using these powders was found through a solvent-free sintering process ("soft sintering"), which makes it easy to provide the detection layers for use in detectors such as x-ray sensitive diodes.

[0024] According to one aspect, the present invention relates to a detection layer on a substrate, in particular for X-rays, comprising perovskite crystals of type ABX3 and / or AB2X4, wherein A comprises at least one monovalent, divalent or trivalent element from the 4th atom onwards.A represents a period of the periodic table, preferably Sn, Ba, Pb, Bi; B represents a monovalent cation whose volume parameter for the respective element A satisfies perovskite lattice formation, preferably monovalent, amino-group-containing, positively charged carbon compounds, more preferably amidinium ions, guanidinium ions, isothiuronium ions, formamidinium ions, as well as primary, secondary, tertiary, and quaternary organic ammonium ions, particularly preferably with 1 to 10 carbons; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide, and iodide, as well as mixtures thereof, wherein the layer has a thickness of at least 10 µm, preferably at least 20 µm, and more preferably at least 100 µm.

[0025] According to a further aspect, the present invention relates to a method for producing a detection layer, in particular for X-rays, comprising perovskite crystals of type ABX3 and / or AB2X4, wherein A comprises at least one monovalent, divalent or trivalent element from the 4th atom onwards.period of the periodic table, preferably Sn, Ba, Pb, Bi; B represents a monovalent cation whose volume parameter for the respective element A satisfies perovskite lattice formation, preferably monovalent, amino-group-containing, positively charged carbon compounds, more preferably amidinium ions, guanidinium ions, isothiuronium ions, formamidinium ions, as well as primary, secondary, tertiary, and quaternary organic ammonium ions, particularly preferably with 1 to 10 carbons; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide, and iodide, as well as mixtures thereof, on a substrate, wherein the detection layer is produced by means of a sintering process, comprising . a) Providing a powder comprising perovskite crystals of type ABX3 and / or AB2X4; b) Applying the powder to the substrate; c) Applying pressure and optionally temperature to compress the powder.

[0026] Another aspect of the present invention relates to a coated scintillator particle, wherein the scintillator particle is enveloped with a shell of perovskite crystals.

[0027] An additional aspect of the invention relates to a detector, in particular for X-rays, comprising at least two electrodes and at least one detection layer placed between the at least two electrodes according to the present invention.

[0028] Further aspects of the present invention can be found in the dependent claims and the detailed description.

[0029] The accompanying drawings are intended to illustrate embodiments of the present invention and to provide a further understanding of it. In conjunction with the description, they serve to explain the concepts and principles of the invention. Other embodiments and many of the advantages mentioned will become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale. Identical, functionally equivalent, and similarly acting elements, features, and components are designated with the same reference numerals in the figures of the drawings, unless otherwise indicated.

[0030] Fig. Figure 1 schematically compares the concepts of direct X-ray conversion and indirect X-ray conversion.

[0031] Fig. Figure 2 schematically shows a mono- or polycrystalline particle with a perovskite lattice structure.

[0032] In Fig. Figure 3 schematically and abstractly represents a coated scintillator particle with a mono- or polycrystalline perovskite lattice structure as its shell.

[0033] Fig. Figure 4 schematically shows a powder mixture of scintillators and mono- or polycrystalline perovskite particles.

[0034] In Fig. 5 to Fig. Figure 7 schematically illustrates the production of mono- or polycrystalline particles with a perovskite lattice structure according to an exemplary embodiment of the present invention.

[0035] Fig. 8 to Fig. Figure 10 schematically shows the production of scintillator particles with a mono- or polycrystalline perovskite lattice structure as a shell according to an exemplary embodiment of the present invention.

[0036] Fig. Figure 11 represents an exemplary layer structure of an X-ray detector based on sintered perovskite powder according to an exemplary embodiment of the present invention.

[0037] The in Fig. The exemplary layer structure shown in Figure 12 can also be used in an exemplary embodiment of an X-ray detector according to the present invention, wherein sintered scintillator particles with perovskite coating according to the invention are used.

[0038] Fig. Figure 13 schematically shows an exemplary layer structure of an X-ray detector according to the present invention, in which sintered scintillator particles and perovskite particles are used in the detection layer.

[0039] Fig. Figure 14 schematically represents another exemplary layer structure of an X-ray detector according to the present invention.

[0040] Fig. Figure 15 shows the results of the measurement of the relative absorption of a perovskite layer compared to a hybrid organic absorption layer (BHJ + scintillator, volume fraction ~50%).

[0041] According to a first aspect, the present invention relates to a detection layer on a substrate, in particular for X-rays, comprising perovskite crystals of type ABX3 and / or AB2X4, wherein A comprises at least one monovalent, divalent or trivalent element from the 4th atom onwards.A represents a period of the periodic table, preferably Sn, Ba, Pb, Bi; B represents a monovalent cation whose volume parameter for the respective element A satisfies perovskite lattice formation, preferably monovalent, amino-group-containing, positively charged carbon compounds, more preferably amidinium ions, guanidinium ions, isothiuronium ions, formamidinium ions, as well as primary, secondary, tertiary, and quaternary organic ammonium ions, particularly preferably with 1 to 10 carbons; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide, and iodide, as well as mixtures thereof, wherein the layer has a thickness of at least 10 µm, preferably at least 20 µm, and more preferably at least 100 µm.

[0042] According to the invention, the detection layer is not particularly limited in its application and can, for example, detect X-rays, gamma rays, or UV radiation. In certain embodiments, the detection layer according to the invention serves to detect X-rays and is therefore an X-ray detection layer.

[0043] According to the invention, the area of ​​the detection layer is adapted to the application; for human medical applications, for example, it is between 2 × 2 cm. 2 (e.g. for dental images), 20 × 20cm 2 (e.g. for mammography) up to 43 × 43 cm 2 (e.g., for lung imaging). For applications in industrial metrology or veterinary medicine, the detector area can also be smaller or larger.

[0044] The substrate is not particularly restricted and can include all substrates commonly used in X-ray detectors, gamma detectors, or UV detectors. For example, it can include glass coated with indium tin oxide (ITO), aluminum zinc oxide, doped zinc oxides, silicon, etc. Substrates such as metal foils or polymer films can also be considered.

[0045] According to the invention, the perovskite crystals of type ABX3 and / or AB2X4 are not particularly limited, insofar as A represents at least one mono-, di- and / or trivalent, positively charged element from the 4th period of the periodic table and / or mixtures thereof, thus also including the 5th, 6th and 7th periods including the lanthanides and actinides, wherein the 4th period of the periodic table begins with K and includes the transition metals from Sc; B represents a monovalent cation whose volume parameter in the respective element A is sufficient for perovskite lattice formation; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide and iodide as well as mixtures thereof.

[0046] According to certain embodiments, A comprises or is a divalent and / or trivalent element from the 4th period of the periodic table onwards. According to certain embodiments, A in the above formulas preferably comprises or is Sn, Ba, Pb, Bi, or mixtures thereof. The perovskite crystals can therefore comprise mixtures of different elements from the fourth period onwards, for example, two different divalent elements or a mixture of monovalent and trivalent elements. According to certain embodiments, the perovskite crystals comprise only one element from the 4th period onwards. Particularly preferably are Sn, Ba, and Pb, as well as mixtures thereof, especially divalent cations of these elements.

[0047] B represents a monovalent cation whose volume parameters, when combined with the respective element A, are sufficient for perovskite lattice formation. The corresponding volume parameters for perovskite lattice formation are well known, both theoretically and from, for example, X-ray crystallographic investigations, as are the volume parameters of monovalent cations and the cations defined under A. Therefore, the corresponding monovalent cation B can be determined after identifying elements A and, if necessary, C, for example, using computer models and, if necessary, simple experiments. In the formulas above, B preferably represents a monovalent, amino-containing, positively charged carbon compound, where a carbon compound is a compound containing at least one carbon atom and thus includes both organic and inorganic compounds.According to certain embodiments, B is selected from the group consisting of amidinium ions, guanidinium ions, isothiuronium ions, formamidinium ions, and primary, secondary, tertiary, and / or quaternary organic ammonium ions, which particularly preferably have 1 to 10 carbon atoms, in particular 1 to 4 carbon atoms, wherein they may be aliphatic, olefinic, cycloaliphatic, and / or aromatic carbon linkages.

[0048] X is selected from the anions of halides and pseudohalides and is preferably selected from the anions chloride, bromide, and iodide, as well as mixtures thereof. Thus, for example, various halide ions can be contained in the perovskite crystals; however, according to certain embodiments, only one halide ion, such as iodide, is present.

[0049] Materials of the general formulas ABX3 and AB2X4 can crystallize in the perovskite lattice, in particular, if A is a divalent element from the 4th period onwards in the periodic table, B is any monovalent cation whose volume parameter is sufficient for perovskite lattice formation in the respective element A, and X corresponds to the halide anions iodide, bromide, or chloride, or mixtures thereof. According to the invention, it is not excluded that both perovskite crystals of the general formula ABX3 and the general formula AB2X4 are present in the detection layer; however, it is also possible that only crystals according to one of the two formulas are present.

[0050] Materials mixed in molar ratios are particularly suitable for perovskite crystals: – CH3-NH3I:PbI2 = PbCH3NH3I3 – CH3-CH2-NH3I:PbI2 = PbCH3NH3I3 – HO-CH2-CH2-NH3:PbI2 = PbHO-CH2-CH2-NH3I3 – Ph-CH2-CH2-NH3I:PbI2 = Pb(Ph-CH2-CH2-NH3)2I4

[0051] The perovskite crystals are not particularly limited in their size or shape. They can be monocrystalline or polycrystalline. According to certain embodiments, the perovskite crystals are also homogeneous. Furthermore, the perovskite crystals can also exist as mixed crystals, although preferably they are not mixed crystals.

[0052] The perovskite crystals can be present in the detection layer in various ways, including, for example, the following three possibilities, which are based on powders of perovskite crystals, powders of scintillator particles coated with a perovskite crystal shell, and mixed powders of perovskite crystal particles and scintillator particles: For example, according to certain embodiments, the perovskite crystals can be present in the detection layer as perovskite crystal particles, as described in Fig. 2 are shown schematically as examples. The in Fig. 2 exemplary perovskite crystal particles 11 can exist as mono- or polycrystalline particles with a perovskite lattice structure, the structure being as shown in Fig. 2 shown, can be regular and uniform in all directions, resulting in a cube-shaped or spherical crystal particle, but other regular or irregular crystal particle shapes are also conceivable.

[0053] Furthermore, according to certain embodiments, the perovskite crystals can be present in the detection layer in encapsulated scintillator particles (“core-shell particles”), as exemplified in Fig. 3 are shown schematically. According to Fig. 3 is a scintillator particle. 12 from a perovskite crystal shell 13 surrounded by the perovskite crystal shell 13 may exhibit a mono- or polycrystalline perovskite lattice structure. As in Fig. The scintillator particle can be shown in section 3. 12 spherical and the perovskite crystal shell 13 They may be irregular, but other shapes for the scintillator particles are also possible. 12 and the perovskite crystal shell 13 This is intended to be the case. This allows both the scintillator particles to be used. 12 as well as the perovskite crystal shell 13 due to a crystalline basic structure of the two materials, it can be irregular, as in Fig. 3 for the perovskite crystal shell 13 While exaggerated in their depiction, they can also be nearly uniform and, for example, result in an almost spherical shape, both for the core and the shell. Various forms with only partial encapsulation are also conceivable, with the scintillator particle being the preferred candidate. 12 however completely with the perovskite crystal shell 13 is enveloped.

[0054] Furthermore, according to certain embodiments, the detection layer can also be a mixed layer containing scintillator particles. 14 and perovskite crystal particles 15 are included in the mixture, such as in Fig. 4 schematically represented. The mixture can be homogeneous or heterogeneous, and it is not excluded that further components are included in the detection layer, as is not the case in the two previous exemplary embodiments. Preferably, however, the detection layer contains only perovskite crystal particles or scintillator particles with a perovskite crystal shell or mixtures of scintillator particles and perovskite crystal particles, as shown in Fig. 2 to Fig. Figure 4 shows the powders used to produce the detector layers. The respective powders for this purpose can be suitably provided.

[0055] All three powders are suitable for use in detectors such as X-ray detectors and enable, on the one hand, the production of thicker absorber layers (e.g., 10–1500 µm) from mono- or polycrystalline perovskite powder and, on the other hand, the conversion to visible light by a scintillator and subsequent absorption of the visible light by the perovskite lattice structure, whereby the perovskite crystals can also simultaneously absorb X-rays. At the same time, the conversion rate of the absorber layer is increased by the direct absorption of the X-rays by the material crystallized in the perovskite lattice.

[0056] The preferably suitable polycrystalline perovskite crystal powders can be prepared from the corresponding starting materials, such as PbI2 and a corresponding organic ammonium iodide, by successive dissolution in ultrasound using a first solvent, as exemplified in Fig. 5 to Fig. 7 is shown. At time t1 ( Fig. 5), the introduction of the starting materials into the first solvent, for example a first starting material 34 such as PbI2 and a second starting material 35 such as a suitably chosen organic ammonium iodide, e.g. methylammonium iodide MeNH3I, into a vessel 31 introduced with a first solvent, for example a polar solvent, e.g. with 1 to 5 carbon atoms, such as methanol, possibly with a water bath 32 tempered and treated with an ultrasonic bath 33 treated. At time t2 ( Fig. 6), at the time of perovskite crystal formation, the perovskite crystals form from a certain concentration in the solution, at which point they settle to the bottom of the container. 31 decrease. The subsequent further crystallization in the perovskite lattice of the remaining starting materials at time t3 ( Fig. 7) Precipitation is achieved, for example, by adding a second solvent, e.g., a nonpolar solvent such as an ether, which can also be aromatic or cyclic. Diethyl ether is an example of a nonpolar solvent. Simultaneous application of ultrasound from an ultrasonic bath 33 Homogeneous microcrystallineity can be ensured.

[0057] By appropriately selecting the second solvent, the yield of the respective reaction product in perovskite structure can be maximized to > 99% after, for example, filtration under inert conditions and drying of the powder. The powder can then be used to produce a detection layer or a detector, whereby the particle size in the powder after production can be, for example, in the range of 1–100 µm, preferably 1–10 µm.

[0058] A corresponding process can also be used to produce particles in which a scintillator particle is enclosed by a photo- and electrically active crystalline layer with a perovskite lattice structure, as exemplified in Fig. 8 to Fig. 10 is shown. According to Fig. 8. At time t1, a scintillator particle is added as a further starting material. 37 such as Gd2O2S:Tb, which emits green light under X-ray excitation, added to the first solvent. During crystal formation at time t2 ( Fig. 9) a coated scintillator particle is then formed 38 , in which the scintillator particle 37The scintillator is encased in a crystalline layer with a perovskite structure, for example, consisting of the perovskite phase of the mixture MeNH3I:PbI2. The absorption of the crystalline encasement is preferably adapted to the emission spectrum of the scintillators. The crystalline encasement performs both the absorption of the light emitted by a scintillator and the direct generation of charge carrier pairs and the transport of the separated charge carriers to the corresponding contacts.

[0059] The production of the particles with a scintillator core (see Fig. 8 to Fig. 10) is carried out analogously to the one in Fig. 5 to Fig. The process shown in section 7. The scintillator particles 37 and the starting materials 34 , 35Scintillator particles are homogeneously dispersed in a first solvent using ultrasound to form a perovskite lattice structure. By using ultrasound to disperse the scintillator, the need for a ligand coating to prevent clumping is eliminated. 37 They also serve as crystallization nuclei, on whose surface the crystalline layer in the perovskite lattice modification is adhesively deposited. By adding a second solvent at time t3 ( Fig. 10) and ultrasonic treatment yields a highly homogeneous particulate material in a rapidly settling suspension. After solvent removal under inert conditions and drying in an inert gas stream, a grey-black powder, for example, can be obtained in a yield > 99%, which can then be used for component manufacturing.

[0060] The weight fraction of the scintillator particles compared to the starting materials can determine the "gray value" of the powder and can vary, for example, from greater than 0:1 to 30:1, preferably from greater than 0:1 to 2:1. According to certain embodiments, the thickness of the absorbing crystalline shell is adapted to the absorption length of a photon in this layer. For example, the absorption length of green light in this crystalline layer is typically ~250 nm. A thicker shell would therefore not improve the absorption properties.

[0061] The powder produced according to the previously described method, consisting of mono- or polycrystalline perovskite crystals ( Fig. 2) can also be mixed with the pure scintillator particles to create a homogeneous mixture of both powders ( Fig. 4), which can also be used to manufacture detectors such as X-ray-sensitive components. Mixtures of perovskite crystal particles, perovskite-coated scintillator particles, and / or scintillator particles are also possible, with the mixing ratios being appropriately adjusted based on the materials used. For example, the material of the perovskite crystal shell in the coated scintillator particle can differ from that of another perovskite crystal particle to cover a broader X-ray absorption spectrum. The same applies to different scintillator particles. Multiple perovskite crystal particles and / or scintillator particles can also be used.

[0062] According to certain embodiments, the layer has a thickness of up to 1500 µm, preferably up to 1000 µm. With thicker layers, for example, the radiation to be detected can no longer penetrate far enough, so that no further increase in efficiency can be achieved and losses may also occur.

[0063] The perovskite crystals in the detection layer according to the invention can, according to certain embodiments, have a crystal size of essentially 1–10 µm. The crystal size here is the mean crystal diameter, as it can be determined, for example, by measurement methods such as scanning electron microscopy. The deviation from the mean crystal diameter in any direction can, according to certain embodiments, be less than 50% of the mean crystal diameter. For example, when producing perovskite powder with the composition CH3NH3PbI3, a size distribution of 3–8 µm with a mean crystal diameter of 5 µm is obtained.

[0064] Although the detection layer according to the invention may only comprise perovskite crystals for the detection of radiation such as X-rays, or may even consist essentially of perovskite crystals, it may, according to certain embodiments, further include scintillators. The scintillators are not particularly limited in this respect and can be tailored to the application, for example, for the detection of X-rays.

[0065] According to certain embodiments, the perovskite crystals absorb radiation in a wavelength range in which the scintillator particles emit radiation. According to certain embodiments, the perovskite crystals also have at least one absorption maximum at a wavelength corresponding to an emission wavelength of the scintillator particle, preferably the emission wavelength of a maximum of the scintillator particle's emission.

[0066] Exemplary material combinations for a combination of scintillator particles with perovskite crystals for different wavelengths are as follows: Suitable green scintillators include, for example, Gd₂O₂S:Pr,Ce (gadolinium oxysulfide doped with praseodymium and cerium with an emission maximum at approximately 515 nm), Gd₂O₂S:Tb (gadolinium oxysulfide doped with terbium with an emission maximum at approximately 545 nm), Gd₂O₂S:Pr,Ce,F (gadolinium oxysulfide doped with praseodymium or cerium or fluorine with an emission maximum at approximately 510 nm), YAG:Ce (yttrium aluminum garnet doped with cerium with an emission maximum at approximately 550 nm), CsI:Tl (cesium iodide doped with thallium with an emission maximum at approximately 525 nm), CdI₂:Eu (europium-doped cadmium iodide with an emission maximum at approximately 580 nm), or Lu₂O₃:Tb (lutetium oxide doped with terbium, exhibiting an emission maximum at approximately 545 nm) is characterized by an emission maximum in the range of 515–580 nm and is thus well-suited to the absorption spectrum of (CH₃NH₃)PbI₃ at 450–750 nm. The scintillator Bi₄Ge₃O₃ 12BGO (bismuth germanate with an emission maximum at approximately 480 nm) can be well combined with (CH3NH3)BrI3 or (CH3NH3)PbI3 which exhibit good absorption in the 460–510 nm range.

[0067] Suitable blue scintillators should also be mentioned. An attractive material combination with blue emission is Lu₂SiO₅:Ce or LSO (cesium-doped lutetium oxyorthosilicate with an emission maximum at approximately 420 nm), Lu 1.8 Y .2 SiO5:Ce (cerium-doped lutetium oxyorthosilicate with an emission maximum at approximately 420 nm), CdWO4 (cadmium tungstate with an emission maximum at approximately 475 nm), CsI:Na (cesium iodide doped with sodium with an emission maximum at approximately 420 nm), or NaI:Tl (thallium-doped sodium iodide with an emission maximum at approximately 415 nm), Bi4Ge3O 12or BGO (bismuth germanate with an emission maximum at approximately 480 nm), Gd2SiO5 or GSO (gadolinium oxyorthsilicate doped with cerium with an emission maximum at approximately 440 nm), or CsBr:Eu (cesium bromide doped with europium with an emission maximum at approximately 445 nm), which combine well with the aforementioned perovskites.

[0068] Red scintillators such as Lu2O3:Eu (lutetium oxide doped with europium with an emission maximum at approximately 610–625 nm), Lu2O3:Tb (lutetium oxide doped with terbium with an emission maximum at approximately 610–625 nm) or Gd2O3:Eu (gadolinium oxysulfide doped with europium with an emission maximum at approximately 610–625 nm), YGdO:(Eu, Pr) (europium and / or praseodymium-doped yttrium gadolinium oxide with an emission maximum at approximately 610 nm), GdGaO:Cr, Ce (chromium and / or cesium-doped gadolinium gallium oxide), or CuI (copper iodide with an emission maximum at approximately 720 nm) can be well combined with (CH3NH3)PbI3.

[0069] Particularly noteworthy according to preferred embodiments are among these pairs: Gd2O2S:Tb or YAG:Ce in combination with (CH3NH3)PbI3 or (CH3NH3)BrI3, Lu2SiO5:Ce in combination with CH3NH3)PbI3 or (CH3NH3)BrI3 or YGdO:Eu with CH3NH3)PbI3.

[0070] In certain embodiments, the scintillators are homogeneously distributed within the layer. This ensures advantageous absorption by the scintillators.

[0071] According to certain embodiments, the scintillators in the layer can be designed as scintillator particles surrounded by a shell of perovskite crystals.

[0072] According to certain embodiments, the scintillator particle has a diameter of 0.01 to 50 µm, preferably 0.5 to 20 µm, and more preferably 1 to 10 µm. This diameter can be suitably determined and thus adjusted using optical (e.g., dynamic light scattering, DLS), electron microscopic, or electrical analysis methods (e.g., Coulter counter). As the particle diameter decreases, the emissivity generally decreases. According to preferred embodiments, the scintillator particles have a diameter of 0.1–30 µm, preferably 1–10 µm, which is adapted to the interaction length of high-energy electrons triggered by X-ray quanta. For the detection of UV radiation, the decrease in emissivity is less significant, which is why smaller particles with diameters down to 10 nm are also used.

[0073] The perovskite crystal coating covers at least 80%, preferably at least 90%, and more preferably at least 95% of the scintillator particle's total outer surface in the coated scintillator particle according to certain embodiments. In preferred embodiments, the scintillator particle is completely, i.e., 100%, coated, so that the coated scintillator particle is provided with the coating on all sides. This simplifies manufacturing, and, for example, the completion of the manufacturing process can be easily determined by observation after the coating is complete, if the coating has a different color than the scintillator particle.

[0074] Furthermore, according to certain embodiments, the shell or covering of the photoactive material has a thickness of 15 to 1500 nm, preferably 50 to 1000 nm, more preferably 100 to 1000 nm, and particularly preferably 150 to 600 nm.

[0075] According to certain embodiments, the thickness of the shell is at most 2.5 times the penetration depth of the emitted radiation of the scintillator particle, so that two directly adjacent scintillator particles have a distance from each other of at most five times the penetration depth of the emitted radiation of the scintillator particles.

[0076] The penetration depth can be derived from the Lambert-Beer law: I = I_0·exp(–alpha·d) I = transmitted intensity I_0 = initiated intensity alpha = absorption coefficient d = layer thickness / penetrated depth of the medium

[0077] The penetration depth delta is defined as the layer thickness at which the intensity of the electromagnetic radiation has fallen to one-e-th part of the initial value and is thus the reciprocal value of the wavelength-dependent absorption coefficient. delta = 1 / alpha

[0078] It should be noted that the absorption coefficients of perovskite crystals, for example at typical layer thicknesses in solar cell applications, are comparable to those of bulk heterojunction (BHJ) systems consisting of P3HT:PCBM. Therefore, preferred layer thicknesses for encapsulated scintillators are in the same range as for BHJ systems, as can be seen, for example, in Nature Photonics, Volume: 8, Pages: 506–514, 2014, DOI:10.1038 / nphoton.2014.134.

[0079] The quantities required for the production of coated scintillator particles can be derived, for example, from the following considerations: Target shell thickness and required quantities:

[0080] The total volume of an exemplary detection layer consists of the scintillator core V Scintillator as well as the mantle volume of the perovskite crystals V Perowskittogether. To be able to weigh out an optimal ratio, the density of the perovskite crystals ρ is needed. Perowskit as well as the scintillator ρ Scintillator , to adjust to the respective weight W Perowskit and W Scintillator to come.

[0081] Total volume (V Gesamt) the detection layer:

[0082] To clarify the significant differences between volumes and quantities, these are expressed as volume percent and quantity percent compared to the total volume and quantity. The following two formulas illustrate this.

[0083] Volume percent approach of perovskite (V Perowskit %):

[0084] Perovskite quantity percentage approach (W Perowskit %):

[0085] The desired shell volume is obtained via the desired absorption of the perovskite. The absorption can be determined via the layer thickness r. PerowskitThe volume of the shell is adjusted, and therefore the absorption length of the emitted light is determined by the shell volume. The shell volume is composed of the total volume with radii r. Scintillator and r Perowskit minus the inner sphere, the scintillator. It can be calculated as follows.

[0086] Target shell volume (V Perowskit ) and thickness (r Perowskit ) V Perowskit = 4π 3 ((r Scintillator + r Perowskit ) 3 – (r Scintillator ) 3 )

[0087] According to certain embodiments, the detection layer according to the invention, regardless of whether scintillators are included or not, has a thickness such that at least 50%, preferably at least 70%, and more preferably at least 90%, of incident radiation in the range of 3.3 eV to 10 MeV is absorbed. The absorption of the incident radiation can be easily determined for a specific layer material by absorption spectrometry at various thicknesses, and the corresponding layer thickness can then be determined by subsequent calculation using known formulas or by graphical determination.

[0088] According to a further aspect, the present invention relates to a method for producing a detection layer, in particular for X-rays, comprising perovskite crystals of type ABX3 and / or AB2X4, wherein A comprises at least one monovalent, divalent or trivalent element from the 4th atom onwards.period of the periodic table and / or mixtures thereof, preferably Sn, Ba, Pb, Bi; B represents a monovalent cation whose volume parameter for the respective element A satisfies perovskite lattice formation, preferably monovalent amino group-containing positively charged carbon compounds, further preferably amidinium ions, guanidinium ions, isothiuronium ions, formamidinium ions, as well as primary, secondary, tertiary, and quaternary organic ammonium ions, particularly preferably with 1 to 10 carbons; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide, and iodide as well as mixtures thereof, on a substrate, wherein the detection layer is produced by means of a sintering process, comprising . a) Providing a powder comprising perovskite crystals of type ABX3 and / or AB2X4; b) Applying the powder to the substrate; c) Applying pressure and optionally temperature to compress the powder.

[0089] In the inventive method for producing the detection layer, material loss can be reduced to a minimum compared to methods such as spraying or centrifugal coating. The density of the compacted or sintered layer can also be varied by adjusting the pressure. This is a particularly important parameter when considering X-ray-absorbing layers. This method makes it possible to achieve much higher densities compared to spraying, centrifugal coating, or doctor blade coating, which has a positive effect on the required layer thickness. The thinner the layer, the lower the voltage that needs to be applied to achieve a specific electric field strength. Denser layers also exhibit, for example, higher absorption, especially of X-rays, and improved electrical conductivity.

[0090] In this process, the powder, comprising perovskite crystals according to specific embodiments, is applied as a powder, preferably as a dry powder, to the respective base / substrate to be coated and then compacted under pressure, for example, unidirectionally, e.g., with a punch, a roller, etc., or isostatically, e.g., by a pressurized liquid (e.g., oil), at a specific sintering temperature, e.g., room temperature of 20–25°C, and for a specific sintering or compaction time. During this process, the particles of the starting material compact and the pore spaces are filled. Both solid-phase sintering, i.e., material compaction without melting the powder comprising perovskite crystals of type ABX3 and / or AB2X4, and liquid-phase sintering, i.e., material compaction via, e.g., locally limited, melting of the powder (e.g., directly at the contact surface between the sintering punch and the crystalline surface), are conceivable.By compressing the molecules through pressure and, if necessary, temperature, the interstitial spaces are minimized and compacted to such an extent that, when an electrical voltage is applied, electrical charge transport becomes possible between the individual crystallites or within the fused crystallites. In this way, homogeneous mono- or polycrystalline material layers of high (and also low) thickness can be produced without complex vacuum processing technology, at high throughput, and without health risks from potential solvents.

[0091] The application of pressure is not particularly limited according to the invention and can be achieved by suitable devices. According to certain embodiments, the pressure is applied by using a stamp or a roller, preferably with a non-stick coating, for example Teflon. ®, are coated. By coating with an anti-stick coating, for example PTFE (polytetrafluoroethylene) or comparable materials from the class of polyhaloolefins (e.g. Teflon). ® This allows for particularly homogeneous surface finishes of the coating. Furthermore, the use of stamps and / or rollers is easily implemented from a process engineering perspective. The material of the stamp or roller is not particularly limited and can be, for example, aluminum, steel, PVC, or PTFE (Teflon). ® ) include. According to certain embodiments, the pressure is exerted isostatically by a pressurized liquid (e.g., oil), which can result in simpler processing.

[0092] The applied pressure is not particularly limited, provided sufficient compaction or sintering is achieved. According to certain embodiments, a pressure of 0.1 to 10,000 MPa, more preferably 0.5 to 500 MPa, and particularly preferably 1 to 200 MPa, is applied. The sintering time is also not particularly limited and, according to certain embodiments, ranges from 0.1 s to 60 min, more preferably 1 s to 30 min, and most preferably 5 to 15 min. If the sintering or compaction time is too long, no better results are achieved and the material properties may deteriorate, whereas sintering or compaction times that are too short cannot achieve sufficient compaction / sintering of the layer.

[0093] According to certain embodiments, the substrate can be heated in step c) before or during the application of pressure to compact the powder, for example to a temperature of 30 to 300°C, preferably 50 to 200°C. This can improve the sintering process or the compaction.

[0094] The layers produced according to the invention can be identified and characterized based on the morphology and surface properties of the sintered or densified layer (possibly with isolated or completely molten areas). It may also be possible to indirectly infer a sintering process, for example, from the absence of traces of solvents, additives, and dispersants. Suitable methods for investigation include: optical microscopy, scanning electron microscopy, atomic force microscopy, secondary ion mass spectrometry, gas chromatography, cyclic voltammetry, etc.

[0095] In the inventive method for producing a detection layer, the substrate is not particularly limited and can comprise all substrates commonly used in detectors. For example, it can comprise glass, indium tin oxide (ITO), aluminum zinc oxide, doped tin oxides, silicon, etc. According to certain embodiments, the substrate can have a first electrical contact, such as a metal, for example Cu or Al, ITO, aluminum zinc oxide, doped zinc oxides, etc., and optionally a first intermediate layer, such as those found in detectors, for example, X-ray detectors.

[0096] Alternatively, the layer can be applied to a temporary substrate (e.g., glass or polymer film) and then removed to be further processed as a self-supporting layer. For example, the self-supporting layer can be covered with a metal foil on both the top and bottom surfaces and then baked or sealed.

[0097] According to certain embodiments, additional photoactive material can be added to the coated scintillator particles before applying pressure or sintering in order to better fill the pore spaces between the coated scintillator particles.

[0098] According to certain embodiments, the perovskite crystals of type ABX3 and / or AB2X4 are provided as a powder, the powder not being further limited according to the invention. Preferably, the powder is provided as a dry powder, and according to certain embodiments, it may also be mixed with a small amount of solvent, for example, less than 10 wt.% or less than 5 wt.%, based on the mass of the powder. If the powder contains a small amount of solvent, it can become sticky, which can facilitate its processing, for example, when applying it to the substrate, and may also reduce the need for heating the substrate.

[0099] According to certain embodiments, the powder comprises perovskite crystals of type ABX3 and / or AB2X4, consisting of powder grains with a diameter of 0.01 to 200 µm, preferably 0.5 to 100 µm, and particularly preferably 1 to 10 µm. If the powder grains are too large, compaction may be difficult, whereas if they are too small, processing may be difficult. The best results are obtained with powder grains with a diameter of 1 to 10 µm, the diameter of which can be determined, for example, by sieve analysis, and appropriate sieves with holes of 1 and 10 µm can be used.

[0100] After the layer has been produced in step b) and / or c), a second intermediate layer can optionally be applied in step d), and optionally a second electrical contact (metal such as Al, Cu or ITO, aluminum zinc oxide, doped tin oxides, etc.) can then be applied in step e), and these are preferably sintered or compacted together. Alternatively, a second intermediate layer and then optionally a second electrical contact can also be applied by other process steps such as vapor deposition, spraying, etc. The second electrical contact can also be applied, for example, as a solid layer by bonding. Furthermore, the second electrical contact can also serve as a new sublayer / substrate onto which a new layer can then be applied using the process according to the invention. Thus, multilayer structures are also conceivable according to the invention.It is also possible to apply a layer comprising perovskite crystals of type ABX3 and / or AB2X4 to a layer comprising other powder comprising perovskite crystals of type ABX3 and / or AB2X4, so that multilayers can be created which can be sintered separately or together.

[0101] According to alternative embodiments, the layer comprising perovskite crystals of type ABX3 and / or AB2X4 can also be applied to a substrate which does not include electrode material, such as glass, and electrical contacts can then be placed laterally to the powder in step b) or to the compacted powder in step c), i.e., for example, also on the substrate next to the layer.

[0102] To enable more precise localization of the layer on the substrate, the application of the powder can be locally limited according to certain embodiments, for example, by using a frame, more preferably by using a frame that is coated at least on the inside with an anti-stick coating, for example, PTFE. The shape of the frame is not particularly restricted and can be round / annular, oval, square, rectangular, or another shape. The height of the frame is also not further restricted, but can preferably have a height equal to the thickness of the layer to be produced by the inventive method, or a greater height. Thus, after production according to certain embodiments, the layer can have a thickness of at least 10 µm, preferably at least 20 µm, and more preferably at least 100 µm.The thickness of the layer depends on the intended application, but according to certain embodiments, it can also be several hundred micrometers (e.g., X-ray detectors) or more. The frame material is not particularly limited and can be, for example, aluminum, steel, PVC, or PTFE (Teflon). ® ) include.

[0103] Sintering or compaction can be achieved, for example, using stamps or rollers. The substrate can be applied to a heated plate, topped with a lower electrode (e.g., ITO, Au, Cr, Cu, Ag, Pt), and then the layer comprising perovskite crystals of type ABX3 and / or AB2X4. Pressure can be applied via a printing plate that fits into a filling ring / frame, which can optionally be heated. In the case of roller compaction, which can also be heated, speed, temperature, and pressure are the most important parameters. Before roller compaction, the powder comprising perovskite crystals of type ABX3 and / or AB2X4 can be homogeneously layered onto the substrate in a correspondingly greater thickness, for example, using a doctor blade. In the case of stamping, temperature, pressure, and time are the decisive parameters.

[0104] The pressing process causes the individual particles to touch, creating continuous current paths in the pressed layer, along which the charge carriers generated during absorption can flow to the contacts.

[0105] After sintering, for example, an aluminum cathode (layer thickness approx. 200 nm) can be deposited onto the sintered layer using physical vapor deposition. It is also possible, for example, to incorporate a piece of die-cut aluminum foil as a top contact / upper electrode during the sintering process.

[0106] Alternatively, two different powders containing perovskite crystals of type ABX3 and / or AB2X4 can be layered on top of each other and pressed together.

[0107] According to certain embodiments, in the inventive method for producing a detection layer, the powder can further comprise scintillators. These can, for example, be homogeneously distributed in the powder.

[0108] According to further embodiments, the scintillators in the powder can be formed as scintillator particles surrounded by a shell of perovskite crystals, as shown above. The scintillator particles can have a diameter of 0.01 to 50 µm, preferably 0.5 to 20 µm, and more preferably 1 to 10 µm. Furthermore, the shell of perovskite crystals can have a thickness of 15 to 1500 nm, preferably 50 to 1000 nm, more preferably 100 to 1000 nm, and particularly preferably 150 to 600 nm.

[0109] According to a further aspect, the present invention relates to coated scintillator particles, wherein the scintillator particles are encased with a shell of perovskite crystals of type ABX3 and / or AB2X4, wherein A represents at least one monovalent, divalent, or trivalent element from the 4th period of the periodic table and / or mixtures thereof, preferably Sn, Ba, Pb, Bi; B represents a monovalent cation whose volume parameter for the respective element A is sufficient for perovskite lattice formation, preferably monovalent, amino-group-containing, positively charged carbon compounds, more preferably amidinium ions, guanidinium ions, isothiuronium ions, formamidinium ions, as well as primary, secondary, tertiary, and quaternary organic ammonium ions, particularly preferably with 1 to 10 carbons; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide, and iodide, as well as mixtures thereof.The scintillator particles are not particularly restricted and can be those described above.

[0110] According to certain embodiments, the scintillator particle has a diameter of 0.01 to 50 µm, preferably 0.5 to 20 µm, and more preferably 1 to 10 µm. In preferred embodiments, the scintillator particles have a diameter of 0.1–30 µm, preferably 1–10 µm, which is adapted to the interaction length of high-energy electrons triggered by X-ray quanta. For the detection of UV radiation, the drop in diameter is less significant, which is why smaller particles with diameters of up to 10 nm are also used.

[0111] The coating, comprising perovskite crystals of type ABX3 and / or AB2X4, covers the scintillator particle in the coated scintillator particle according to the invention, according to certain embodiments, to at least 80%, preferably at least 90%, and more preferably at least 95% of its total outer surface. According to preferred embodiments, the scintillator particle is completely, i.e., 100%, coated, so that the coated scintillator particle is provided with the coating on all sides.

[0112] Furthermore, the shell comprising perovskite crystals of type ABX3 and / or AB2X4 according to certain embodiments has a thickness of 15 to 1500 nm, preferably 50 to 1000 nm, more preferably 100 to 1000 nm, and particularly preferably 150 to 600 nm.

[0113] According to certain embodiments, the thickness of the shell / envelope is at most 2.5 times the penetration depth of the emitted radiation of the scintillator particle, so that two directly adjacent scintillator particles have a distance from each other of at most five times the penetration depth of the emitted radiation of the scintillator particles.

[0114] The penetration depth can be derived from the Lambert-Beer law: I = I_0·exp(–alpha·d) I = transmitted intensity I_0 = initiated intensity alpha = absorption coefficient d = layer thickness / penetrated depth of the medium

[0115] The penetration depth delta is defined as the layer thickness at which the intensity of the electromagnetic radiation has fallen to one-e-th part of the initial value and is thus the reciprocal value of the wavelength-dependent absorption coefficient. delta = 1 / alpha

[0116] For the proper functioning of a detector according to the invention, which is manufactured using the coated scintillator particles according to the invention, the entire space between two particles, which is also created, for example, by the coating of the scintillator particles, should be excited by emitted photons. According to the invention, this is ensured when, for example, the intensity has dropped to 10%. In the chosen example, this would be the case at 300 nm, so that, in this case, two particles can even be 600 nm apart, which then corresponds to approximately five times the penetration depth and to a coating of the scintillator particles according to the invention with a thickness of 300 nm. At five times the penetration depth, good absorption of the emitted light from the scintillator particles is thus ensured.

[0117] According to certain embodiments, the respective distance between two scintillator particles corresponds to less than three times the penetration depth of the emitted radiation of the scintillator particle and thus to a coating of the scintillator particles according to the invention with a thickness of less than 1.5 times the penetration depth of the emitted radiation.

[0118] According to preferred embodiments, the distance between two scintillator particles is at most three times the penetration depth of the emitted radiation from the scintillator particles, and according to particularly preferred embodiments, the distance between two scintillator particles is at most twice the penetration depth of the emitted radiation from the scintillator particles, which corresponds to a coating of the coated scintillator particles with a thickness of at most 1.5 times the penetration depth or at most one penetration depth of the emitted radiation from the scintillator particle. In such a case (double penetration depth), the charge transport in the perovskite matrix is ​​efficiently improved by generating conductive channels between two adjacent scintillator particles under X-ray excitation.According to certain embodiments, the scintillator particles have a coating thickness designed such that the conductive zones generated by the emission of the scintillator particles overlap, thus achieving a fast response, for example at a thickness corresponding to a maximum of 2.5 times, 1.5 times, or one time the penetration depth of the emitted radiation of the scintillator particle.

[0119] A special aspect of the present invention is the coating of the scintillator particle with a shell comprising perovskite crystals of type ABX3 and / or AB2X4.

[0120] The invention thus includes, for example, a material in which a scintillator particle is enclosed by a shell comprising perovskite crystals of type ABX3 and / or AB2X4, as described in Fig. Figure 3 is shown schematically. The shell comprising perovskite crystals of type ABX3 and / or AB2X4 is characterized here, by the fact that its absorption properties are matched to the emission of the scintillator particle.

[0121] The absorption of the crystalline coating is preferentially adapted to the emission spectrum of the scintillators. The crystalline coating performs both the absorption of the light emitted by a scintillator and the direct generation of charge carrier pairs, as well as the transport of the separated charge carriers to the corresponding contacts.

[0122] The coating / encapsulation of scintillators with a crystalline shell of perovskite lattice structure is a combination of two X-ray-active materials, so that the X-ray absorption and conversion into an electrical signal by the coated particles is improved compared to the individual materials (scintillator or pure powder of a perovskite lattice structure).

[0123] The size of the scintillator particle is preferably designed to be adapted to the physical interaction mechanisms. For example, in medical X-ray imaging, X-ray energies between 10 and 150 keV are typically used. In this energy range, the photoelectric effect is dominant in the X-ray absorption process; that is, the absorption of an X-ray quantum ejects a high-energy electron from the atomic structure, which then moves within the scintillator crystal. Through multiple collisions, this high-energy electron creates excited states within the scintillator crystal, which, through recombination, generate visible light. The range of the high-energy electron is typically on the order of a few micrometers; accordingly, a particle diameter of 1–10 µm, for example, provides a good starting point.In smaller particles, some of the photoelectron's kinetic energy could be lost; larger particles are conceivable from an optical perspective but would limit the electrical performance of subsequent components. The coating's thickness, for example, is also adapted to the photon's absorption length. The absorption length of green light through the perovskite coating is typically 250 nm–500 nm; a much thicker coating would not improve the absorption properties. The above considerations can be applied analogously to the detection of gamma rays or UV light.

[0124] According to a further aspect, the present invention relates to a process for producing coated scintillator particles, wherein at least starting materials for perovskite crystals are dissolved using at least a first solvent, the scintillator particles are added to the solution, the coated scintillator particles are then precipitated by adding a further substance such as a second solvent, and finally the first solvent and the further substance are removed.

[0125] In certain embodiments of the process for producing coated scintillator particles, the starting materials for the perovskite crystals are dissolved using at least one solvent, the scintillator particles are added to the solution, the coated scintillator particles are then precipitated by adding another substance, for example, a second solvent, and finally the at least first solvent and the other substance are removed, for example, by suction, filtering, or evaporation of the solvents, etc. Suitable substances for dissolving and precipitating are not limited and can be selected appropriately depending on the application and may also include mixtures.

[0126] According to certain embodiments, the scintillator particles are insoluble in the first solvent. In preferred embodiments, the suspension of scintillator particles is continuously mixed / stirred during processing. This can be achieved, for example, by exposing the suspension to ultrasonic waves to ensure better distribution of the scintillator particles.

[0127] However, according to the invention, it is not excluded that the scintillator particles may clump together during precipitation and be obtained as a voluminous mass, since coated scintillator particles are still obtained in this case. According to certain embodiments, the coated scintillator particles can also be obtained individually, which can be controlled, for example, by the concentrations of the reagents used in solution or suspension.

[0128] According to the invention, the manufacturing process for the coated scintillator particles can also include, for example, dispersants, ligands for the scintillator particles, or other additives, which can then be removed from the surface of the scintillator particles before precipitation, for example, by using ultrasound. According to certain embodiments, no additives are added in order to avoid negatively influencing perovskite crystal formation.

[0129] According to certain embodiments, the coated scintillator particles are ground into a powder after the removal of the initial solvent and the remaining substance. In these embodiments, care is taken to separate only contiguous coated particles and to avoid damaging the coating. This can be achieved by selecting a suitable grinding process, such as wet grinding followed by drying. However, it is usually sufficient to simply grind the particle mass obtained after solvent removal in a mortar to produce a free-flowing, homogeneous powder.

[0130] According to certain embodiments, the powder consists of powder particles with a diameter of 0.01 to 200 µm, preferably 0.5 to 100 µm, and particularly preferably 1 to 10 µm. If the powder particles are too large, compaction during the production of detection layers or detectors according to the invention can be difficult, whereas if the powder particles are too small, the process can become too complex. The best results are obtained with particle particles with a diameter of 1 to 10 µm, the particle diameter of which can be determined, for example, by optical (high-resolution microscope, dynamic light scattering / DLS), electron microscopic, or electrical analyses (e.g., Coulter counter).

[0131] In the process according to the invention, the structure is formed in solution. This allows for better control of material usage and opens up new processing possibilities from the dry phase. The process is also characterized by good processability for the production of thick layers in detectors (no drying cracks from escaping solvent), as well as the associated health and environmental benefits.

[0132] The production of the coated scintillator particles can be exemplified by the example in Fig. 8 to Fig. The process described in section 10, which is already detailed above, will take place.

[0133] The quantities required for the production of coated scintillator particles can be derived, for example, from the following considerations: Target shell thickness and required quantities:

[0134] The total volume of an exemplary detection layer consists of the scintillator core V Szintillator as well as the mantle volume of the perovskite crystals V Perowskit together. To be able to weigh out an optimal ratio, the density of the perovskite crystals ρ is needed. Perowskit as well as the scintillator ρ Szintillator , to adjust to the respective weight W Perowskit and W Szintillator to come.

[0135] Total volume (V Gesamt) the detection layer:

[0136] To clarify the significant differences between volumes and quantities, these are expressed as volume percent and quantity percent compared to the total volume and quantity. The following two formulas illustrate this.

[0137] Volume percent approach of the perovskite shell (V Perowskit %):

[0138] Perovskite shell quantity percentage approach (W Perowskit %):

[0139] The desired shell volume is obtained via the desired absorption of the perovskite crystals. The absorption can be determined via the layer thickness r. Perowskit The volume of the shell is adjusted, and therefore the absorption length of the emitted light is determined by the shell volume. The shell volume is composed of the total volume with radii r. Szintillator and r Perowskit minus the inner sphere, the scintillator. It can be calculated as follows.

[0140] Target shell volume (V Perowskit ) and thickness (r Perowskit )

[0141] As an example of a scintillator with radius r Szintillator = 1.8 µm and a target cladding absorption layer thickness of r Perowskit A fill factor of V = 0.15 µm Perowskit %:V Szintillator % of 37%:63%. At typical densities of ρ Perowskit = 6.1 g / ml and ρ Szintillator = 7.2 g / ml, this results in a weight ratio W Perowskit :W Szintillator of approximately 0.9:1.

[0142] It is particularly important to note that this mass ratio depends on the diameter and density of the scintillator. The larger the particle, the less perovskite crystal is required to meet the aforementioned conditions. The volume ratios are determined by the diameter of the scintillators and the penetration depth of the light into the perovskite crystal shell. The mass ratio can then be calculated using the density according to the formulas above.

[0143] During sintering or compaction of the coated scintillator particles according to the invention, current paths can be created by contacting the individual powder grains, along which the photogenerated charge carriers can be carried to the contacts and detected as photocurrent (or "X-ray current").

[0144] According to a further aspect, the present invention relates to a detector comprising at least two electrodes and at least one detection layer according to the invention placed between the at least two electrodes.

[0145] The detector can be an X-ray detector, gamma detector or UV detector, in particular a detector for X-ray radiation such as an X-ray-sensitive diode.

[0146] The detector according to the invention can further comprise, according to certain embodiments, at least one hole-conducting and / or electron-conducting and / or insulating intermediate layer.

[0147] According to another aspect, the present invention relates to a detector, for example an X-ray detector, gamma detector or UV detector, which comprises the coated scintillator particles according to the invention.

[0148] According to certain embodiments, the detector, for example an X-ray detector, gamma detector or UV detector, comprises a substrate with a first electrical contact and optionally at least one first intermediate layer, a layer comprising the perovskite crystals of type ABX3 and / or AB2X4, for example also the coated scintillator particles, optionally at least one second intermediate layer, and a second electrical contact.

[0149] In the detector manufacturing process, the substrate is not particularly limited and can include all substrates commonly used in detectors such as X-ray detectors, gamma detectors, or UV detectors. For example, it can include glass, indium tin oxide (ITO), aluminum zinc oxide, doped zinc oxides, silicon, etc. According to certain embodiments, the substrate can have a first electrical contact such as a metal, for example Cu, Ag, Pd, Pt, Cr, Au, or Al, ITO, aluminum zinc oxide, doped zinc oxides, etc., and optionally a first intermediate layer such as those found in electroorganic devices.The material of the electrode and / or substrate depends on its application as a detector, for example, X-ray detector, gamma detector, or UV detector. Different materials are used for detecting these different types of radiation, as they need to be transparent to the radiation in certain designs. For example, aluminum is not suitable for UV radiation.

[0150] According to certain embodiments, the electrode and / or substrate material reflects the light emitted by the perovskite crystals and / or optionally scintillator particles. The reflective effect of the contacts on the emitted radiation prevents the emitted light from escaping the active zone. In certain embodiments, the first electrical contact and / or the second electrical contact and / or the substrate thus comprise or consist of a material that reflects the emitted radiation from the perovskite crystals and / or optionally scintillator particles. Examples of such materials include metals like Au, Ag, Pd, Pt, Al, Cr, or Cu; however, a multitude of other materials are known, so the materials of the electrical contacts are not further limited, provided they reflect the emitted radiation from the perovskite crystals and / or optionally scintillator particles.The detected signal can be further improved through appropriate design.

[0151] The detector according to the invention can, in certain embodiments, optionally include interlayers that improve the interface between the active layer and the contact layers, and thus the contact with the sample. These interlayers are generally hole-conducting organic semiconductors or electron-conducting organic semiconductors. Examples of suitable hole conductors include PEDOT:PSS, P3HT, MDMO-PPV, MEH-PPV, and TFB, while PCBM can be used as an electron conductor. The interlayers also serve to reduce the injection of charge carriers from the electrodes into the sintered layer, thereby enabling a low reverse leakage current (dark current).

[0152] For example, inorganic interlayers such as ZnO or TiO can also be used. Very thin (a few nanometers) layers of insulating materials (e.g., Al2O3, SiO2, Si3Ni4) can also serve as interlayers.

[0153] Exemplary schematic designs for the layer structure in detectors are shown in Fig. 7 to Fig. 10 shown.

[0154] In the Fig. The layer structure shown in section 11 is on a substrate 42 between a lower electrode 43 and an upper electrode 44 a perovskite crystal layer 41 depicted with mono- or polycrystalline perovskite after sintering. In the Fig. The layer structure shown in 12 is instead of the perovskite crystal layer. 41 in Fig. 11 a detection layer 45 The system provides for fully encapsulated scintillator particles. Fig. 13 is compared to Fig. 11 instead of the perovskite crystal layer 41 a layer containing a mixture of scintillator particles 47 and perovskite crystal particles 46 depicted.

[0155] In all three layer structures of the Fig. 11 to Fig. 13. Interlayers may be provided below and / or above the detection layer, as exemplified by the one in Fig. The layer structure shown in 14 is illustrated. This differs from the layer structure in Fig. 11 an intermediate shift 48 on, which can be, for example, a hole blocker such as PCBM, as well as an intermediate layer 49 , which may be an electron blocker such as P3HT or PEDOT or PEDOT:PSS.

[0156] In addition to or instead of these intermediate layers, insulating layers may also be provided.

[0157] According to a further aspect, the present invention relates to the use of the coated scintillator particles according to the invention for the detection of high-energy radiation, in particular UV radiation, gamma and / or X-ray radiation.

[0158] The above embodiments, configurations, and further developments can be combined with one another as appropriate. Further possible configurations, further developments, and implementations of the invention also include combinations of features of the invention described previously or subsequently with respect to the exemplary embodiments, even if not explicitly mentioned. In particular, those skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.

[0159] The invention will subsequently be illustrated by means of some exemplary embodiments, which, however, do not limit it.

[0160] Details of the synthesis of exemplary perovskite crystals and the formation of a detection layer according to a first exemplary embodiment are given below.

[0161] For example, all materials and solvents are cleaned and prepared oxygen-free in a glove box or under adequate conditions; likewise, all work up to the finished, usable material mixture is carried out under such conditions.

[0162] By adding a polar solvent, particularly suitable methanol, to a round-bottom flask, the essentially identical stoichiometrically proportioned, preferably stoichiometrically present, starting materials lead(II) halide and a corresponding ammonium halide such as methylammonium iodide are partially dissolved at room temperature (20 to 22°C). A suspension-like mixture forms simultaneously with the formation of deeply colored (mostly black) perovskite crystal particles. The formation of the perovskite crystals is completed by ultrasonic treatment. This results in an almost constant particle size of the resulting powder. To also crystallize any remaining material in solution, a second nonpolar solvent is added, particularly suitable is diethyl ether, which, under ultrasonic conditions, leads to the complete crystallization of the remaining starting materials in solution as black mono- or polycrystalline particles.The addition of the second solvent yields a highly homogeneous suspension produced by ultrasound, which settles quickly and is ideally suited for vacuum filtration. Post-treatment of the dried filtrate with a mortar or vibrating ball mill to limit the particle size distribution is unnecessary, as the resulting powder is sufficiently homogeneous. The yield is > 99%, almost quantitative. After possible comminution, the powder can be applied to a substrate such as glass and pressed into a detection layer using a roller, to which electrodes can then be attached.

[0163] Fig. Figure 15 shows the measurement of the relative absorption of a correspondingly produced perovskite layer with CH3NH3PbI3 compared to an organic absorption layer (P3HT:PCBM:GOS).

[0164] The relative absorption of the perovskite layer (shown in the graph above with circular measurement points) and, for comparison, an organic absorption layer comprising P3HT:PCBM:GOS in a weight ratio of 1:1:8 (shown in the graph below with square measurement points) was measured at various accelerating voltages from 40 to 120 kV. The relative absorption was calculated for each accelerating voltage for a layer thickness of approximately 200 µm. The entire bremsstrahlung spectrum, including the characteristic radiation of a tungsten anode, was used in the measurements. First, the dose at the sample location without a sample was measured using a dosimeter. Then, the dose behind a sample consisting of 1 mm of glass (which will be used as the substrate in the following samples) and 0.1 mm of glass (which serves as the encapsulation for the perovskite layer) was measured.Finally, the dose downstream of the actual sample, including the substrate and encapsulation, was measured. The relative absorbance is then calculated by subtracting the absorbance in the substrate and encapsulation from the dose absorbed in the sample and dividing the result by the irradiated dose.

[0165] It is applied in Fig. 15 the tube voltage U in kilovolts against the relative absorption A r in %.

[0166] Absorption coefficients for perovskite of 66.5 cm⁻¹ were obtained. –1 and for the comparative measurement with P3HT:PCBM:GOS of 32.2 cm –1 .

[0167] In a second exemplary embodiment, a homogeneous powder is produced, consisting of scintillator particles surrounded by a crystalline perovskite layer for the formation of an X-ray absorber.

[0168] The basic procedures for preparation and production are analogous to the exemplary embodiment, wherein, in addition to the starting materials that form the perovskite lattice, scintillator particles, e.g. Gd2O2S:Tb, are added to the round-bottom flask, for example in the desired mass ratio of 1:1 (based on the amount of perovskite crystals formed).

[0169] The subsequent procedure is the same as in the first exemplary embodiment. The formation of the coated particles begins immediately upon addition of the solvent, resulting in a grey-black, homogeneous particle mixture whose "grey value" depends on the proportion of scintillator.

[0170] The present invention provides a detection layer in which a material crystallized in a perovskite lattice layer, in addition to absorbing visible light and X-rays, also exhibits good electrical conductivity of the generated charge carrier pairs and high mobility up to 50 cm. 2 / Vs shows.

[0171] By encasing a scintillator particle in a thin crystalline shell made of a perovskite-lattice-forming material, which absorbs the incident light generated by the scintillator and conducts the resulting charge carriers to the contacts, a further improvement in detection can be achieved in a detector layer. Simultaneously with the scintillator, the crystalline shell also converts X-rays into charge carriers on its own. The combination of two X-ray-sensitive materials increases absorption and enables detection over a wider wavelength range compared to the two individual layers of scintillator and pure perovskite powder. This allows for the detection of more X-ray photons across a broader energy range.Here too, the structure forms during a prior synthesis and not only during the drying phase on the substrate, as is the case with previously used methods for producing perovskite layers.

[0172] By combining scintillator particles and perovskite crystals, absorption and thus detection over a wider wavelength range is possible in the mixture compared to the individual materials, which improves the efficiency of the detection.

[0173] The photons generated when using a scintillator are absorbed in the adjacent perovskite lattice material and converted into charge carriers. This increase in charge carriers has positive effects on the perovskite lattice material because it increases the conductivity (or mobility) and reduces the detector response times, thus making the detectors faster.

[0174] The advantage of this detection layer manufacturing process, compared to solution-based techniques, lies in the ability to synthesize the material powder in any quantity, both as pure crystalline powder and as a coating around the scintillator. The synthesis is virtually lossless in both cases, and the powders can be stored for any length of time. This allows for better control of material usage and opens up new processing possibilities. Using an ultrasonic device for dispersion results in a more homogeneous, finer mono- or polycrystalline powder compared to manual stirring. The crystallinity of the powder can be optically verified after production, as, for example, in the case of CH3NH3PbI3, crystalline powder with a perovskite lattice structure is black, whereas amorphous powder appears yellowish.

[0175] The powders produced using this method allow for relatively simple processing of particularly thick layers, as no drying cracks occur due to solvent leakage. This also results in health and environmental benefits. Processing with punches or rollers minimizes material loss compared to methods such as spraying or centrifugal coating. The density of the resulting layer can be varied by adjusting the pressure of the punch or roller, which is especially advantageous for X-ray-absorbing coatings. Compared to spraying, centrifugal coating, or doctor blade application, the density can be increased, resulting in a thinner layer thickness required for the same X-ray absorption. This has the advantage that lower voltages are sufficient to generate the same electric field strength in the component. QUOTES INCLUDED IN THE DESCRIPTION

[0176] 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 patent literature

[0177] US 6483099 B1

[0007] DE 10137012 A1

[0008] DE 102008029782 A1

[0009] DE 102010043749 A1

[0010] DE 102013226339

[0017] DE 102014212424

[0018] Cited non-patent literature

[0178] Dirin et al. 2014, DOI: 10.1021 / ja5006288

[0013] Noel et al. 2014, DOI: 10.1039 / c4ee01076k

[0013] Im et al. 2014, DOI: 10.1186 / 1556-276X-7-353

[0013] Nature Photonics, Volume: 8, Pages: 506–514, 2014, DOI:doi:10.1038 / nphoton.2014.134

[0078]

Claims

[1] Detection layer on a substrate, in particular for X-rays, comprising perovskite crystals of type ABX3 and / or AB2X4, wherein A is at least one monovalent, divalent or trivalent element from the 4th atom onwards.A period of the periodic table and / or mixtures thereof, preferably Sn, Ba, Pb, Bi; B represents a monovalent cation whose volume parameter for the respective element A satisfies perovskite lattice formation, preferably monovalent, amino-group-containing, positively charged carbon compounds, more preferably amidinium ions, guanidinium ions, isothiuronium ions, formamidinium ions, as well as primary, secondary, tertiary, and quaternary organic ammonium ions, particularly preferably with 1 to 10 carbons; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide, and iodide as well as mixtures thereof, wherein the layer has a thickness of at least 10 µm, preferably at least 20 µm, and more preferably at least 100 µm. [2] Detection layer according to claim 1, wherein the layer has a thickness of up to 1500 µm, preferably up to 1000 µm. [3] Detection layer according to claim 1 or 2, wherein the perovskite crystals have a crystal size of essentially 1–10 µm. [4] Detection layer according to claim 1 or 2, wherein the layer further comprises scintillators. [5] Detection layer according to claim 4, wherein the scintillators in the layer are formed as scintillator particles surrounded by a shell of perovskite crystals. [6] Detection layer according to claim 5, wherein the scintillator particles have a diameter of 0.01 to 50 µm, preferably 0.5 to 20 µm, more preferably 1 to 10 µm and / or wherein the shell of perovskite crystals has a thickness of 15 to 1500 nm, preferably 50 to 1000 nm, more preferably 100 to 1000 nm, particularly preferably 150 to 600 nm. [7] Detection layer according to one of the preceding claims, wherein the detection layer has a thickness such that at least 50%, preferably at least 70%, more preferably at least 90% of an incident radiation in the range of 3.3 eV to 10 MeV is absorbed. [8] Method for producing a detection layer, in particular for X-rays, comprising perovskite crystals of type ABX3 and / or AB2X4, wherein A comprises at least one monovalent, divalent or trivalent element from the 4th atom onwards.period of the periodic table and / or mixtures thereof, preferably Sn, Ba, Pb, Bi; B represents a monovalent cation whose volume parameter for the respective element A satisfies perovskite lattice formation, preferably monovalent, amino-group-containing, positively charged carbon compounds, more preferably amidinium ions, guanidinium ions, isothiuronium ions, formamidinium ions, as well as primary, secondary, tertiary, and quaternary organic ammonium ions, particularly preferably with 1 to 10 carbons; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide, and iodide as well as mixtures thereof, on a substrate, wherein the detection layer is produced by means of a sintering process, comprising . a) Providing a powder comprising perovskite crystals of type ABX3 and / or AB2X4; b) Applying the powder to the substrate; c) Applying pressure and optionally temperature to compact the powder. [9] Method according to claim 8, wherein the powder further comprises scintillators. [10] Method according to claim 9, wherein the scintillators in the powder are formed as scintillator particles surrounded by a shell of perovskite crystals. [11] Method according to claim 10, wherein the scintillator particles have a diameter of 0.01 to 50 µm, preferably 0.5 to 20 µm, more preferably 1 to 10 µm. [12] Method according to claim 10 or 11, wherein the shell of perovskite crystals has a thickness of 15 to 1500 nm, preferably 50 to 1000 nm, more preferably 100 to 1000 nm, particularly preferably 150 to 600 nm. [13] Coated scintillator particle, wherein the scintillator particle is encased with a shell of perovskite crystals of type ABX3 and / or AB2X4, wherein A represents at least one mono-, di- or trivalent element from the 4th period of the periodic table and / or mixtures thereof, preferably Sn, Ba, Pb, Bi; B represents a monovalent cation whose volume parameter for the respective element A satisfies perovskite lattice formation, preferably monovalent, amino-group-containing, positively charged carbon compounds, more preferably amidinium ions, guanidinium ions, isothiuronium ions, formamidinium ions, as well as primary, secondary, tertiary, and quaternary organic ammonium ions, particularly preferably with 1 to 10 carbons; and X is selected from the anions of halides and pseudohalides, preferably from the anions chloride, bromide and iodide as well as mixtures thereof. [14] Detector, in particular for X-rays, comprising at least two electrodes and at least one detection layer placed between the at least two electrodes according to one of claims 1 to 7. [15] Detector according to claim 14, further comprising at least one hole-conducting and / or electron-conducting and / or insulating intermediate layer.