EP3055712A1

EP3055712A1 - Conversion film for converting ionizing radiation, radiation detector, and method for production

Info

Publication number: EP3055712A1
Application number: EP14816175.5A
Authority: EP
Inventors: Patric Büchele; David Hartmann; Oliver Schmidt; Sandro Francesco Tedde; Joachim Wecker
Original assignee: Siemens Healthcare GmbH
Current assignee: Siemens Healthcare GmbH
Priority date: 2013-12-18
Filing date: 2014-12-10
Publication date: 2016-08-17
Also published as: CN105829914A; US20160327655A1; WO2015091145A1

Abstract

The invention relates to a conversion film for converting ionizing radiation into light and for producing charge carriers by means of the produced light. The conversion film comprises a conversion layer having a plurality of scintillator particles embedded into a binder, wherein the binder contains at least one first organic semiconductor material. The invention further relates to a radiation detector for detecting ionizing radiation having such a conversion film and to a method for producing such a conversion film. The method for producing the conversion film according to the invention comprises the following steps: - producing a mixture from a plurality of scintillator particles and a binder containing an organic semiconductor material, - producing a stratiform structure from the mixture, and - forming a conversion layer by solidifying the stratiform structure.

Description

description

Conversion film for conversion of ionizing radiation, radiation detector and method of manufacture

The invention relates to a conversion film with a Kon ^¬ version layer for the conversion of ionizing radiation in light. Furthermore, it relates to a radiation detector for detecting ionizing radiation with such a conversion film and to a process for producing such a conversion film.

Conversion films are known which contain a multiplicity of scintillator particles in order to convert incidental ionizing radiation into visible light. Such conversion films are used in medical imaging imaging for the detection of X-rays. The conversion films are used to increase the density of a photosensitive film or the signal of a photo sensor in comparison to a response to the unconverted Rönt ^{¬-radiation,} because the films or photosensors much more sensitive to the light emitted by the scintillator visible light as the original Rönt ^¬ radiation. In addition, in the scintillator, each quantum of X-radiation is converted to a plurality of quantum of visible light by fluorescence of the scintillator material. For this reason, such conversion films are also referred to as intensifying screens. Known conversion or intensifying screens typically consist of a conversion layer having embedded in a Binderma ^¬ TERIAL scintillator, wherein the conversion layer is applied to a carrier film. This carrier substrate can consist, for example, of polyester or cellulose triacetate, that is to say of similar materials as the classical X-ray films. Between the conversion layer and the carrier film is often still a reflective or backscattering layer, for example made of titanium dioxide ange- assigned to direct the light to this page back to the convergence ^¬ sion layer. The decoupling of the fluorescence light generated by the scintillator the substrate takes place on the side facing abge ^¬. On this page, the light is coupled into a film or a photosensor that is as close as possible. For this purpose, an adapted refractive index Kopp ^¬ lung emulsion may be interposed between the conversion layer and film or photosensor. The scintillator is typically embedded in the form of a luminous ^¬ material powder in a transparent binder material as possible. Typical binder materials are resins, thermoplastic elastomers ^¬ or other transparent organic compounds. On the light-outcoupling side, the conversion layer can again be as transparent as possible

Be provided protective layer.

Such conversion films are for example in the

DE 41 42 150 C2 and EP 0 126 564 A2. For manufacturing position a binder, and often an additional dispersant Dis a ^¬ persion is from the powdery phosphor prepared which is then wound onto the carrier substrate ^¬ wear. The dispersion can be filled into pre-structured cells. Thereafter, the dispersion is hardened. Suitable binder materials are a number of casting resins and transparent polymerizable organic compounds, including polymethylmethacrylate beschrie ^¬ ben. A disadvantage of the known conversion films is the problem of optical distortion. For the most complete possible absorption and conversion of X-rays into visible light, a layer thickness of the conversion layer in the Be is ^¬ ranging from about 100 to 800 ym ym required. Above all, at the upper end of this thickness range, the thickness of the conversion layer causes an optical expansion of the emitted fluorescent light. The reason for this is the isotropic Ausbrei ^¬ processing of the light emitted from the point of interaction in the Scintillator material. The propagation thus follows undirected and is not channeled in the direction of the film or the photosensor. The higher the layer thickness of the conversion layer ^¬ and the greater therefore the mean distance between the location of the interaction and the formation of the fluorescent light, the more the light is expanded within the layer. Thus, at higher thicknesses of the Kon ^¬ version layer results in a blurred image. The problem of optical distortion is an unsolved problem. In practice, this problem is mitigated by the fact that is used depending on the requirements of the diagnosti ^¬ rule application either a thinner film with a lower conversion efficiency, but higher image sharpness, or a thicker film higher Umwandlungsef ^¬ ciency, but less sharpness. Thus, there must always be a compromise between the efficiency - and thus the radiation ^{burden on} the patient - and the quality of the imaging.

A second approach to solving the problem is to pattern the scintillator material in a kind of needle or columnar shape to effect channeling of the emitted light toward the photosensor. This is possible with Csl-based scintillators in which doped Csl can be grown by gas phase deposition in columnar structures. However, this type of production is very expensive, and corresponding conversion layers are very expensive compared to the classical conversion films.

Another known approach to X-ray detection is the use of hybrid organic photodiodes with embedded scintillator particles. Here, a hybrid photoactive layer is disposed between an electrode and a substrate. The hybrid photoactive layer comprises a plurality of scintillators and a photoactive material in the form of a bulk heterojunction. The bulk heterojunction absorbs the scintillating radiation to form of electron-hole pairs, which are then electrically detected.

In this context, the term "bulk heterojunction" refers to a phase-separated mixture of an electron donor material and an electron acceptor material, these two components of the mixture each forming an interpenetrating network. In particular, this network may be a bicontinuous network that is transported to an interface between donor and acceptor so that a carrier pair, of this Grenzflä ^¬ surface by a contiguous possible transport path in the donor material to one side of the layer, and by a contiguous possible transport path can be transported in the acceptor material to another side of the layer. Typically, electrons are mounted on two opposite sides of the hybrid photoactive layer, via which the separate charge carriers, ie the electrons and the holes, can be detected electrically.

The preparation of the hybrid photoactive layers in such known photodiodes can be effected by a common deposition of the scintillator and the materials of the bulk heterojunction, wherein the scintillator in a suspension and the materials of the bulk heteroj unction are present in a solution. In particular, these two materials can be sprayed simultaneously onto the substrate. However, this type of preparation with liquid starting materials is relatively expensive and material-intensive, since during application usually a high loss of material is produced, and an entry of Mate ^¬ rial over the dimensions of the substrate to be coated also takes place.

Furthermore, glass substrates are often used for the production of known organic photodiodes, which are provided with regular arrangements of transistors for driving the individual picture elements. These transistor substrates are typically with regularly structured arrays of Provided partial electrodes, which serve for the extraction of charge carriers for individual portions of the photoactive layers. Conventional deposition of the photoactive layers directly on the transistor substrates can lead to an undesirably high waste of expensive transistor ^substrates . Each additional process step in such a complex and integrated detector production decreases the overall yield based on the material used. Object of the present invention is therefore to provide a conversion film for the conversion of ionizing radiation, which avoids the disadvantages mentioned. Another object is to provide a radiation detector with such a conversion foil and a production method for such a conversion foil.

These objects are achieved by the conversion foil described in claim 1, the radiation detector described in claim 14 and the method described in claim 15.

The conversion film according to the invention is designed for the conversion of ionizing radiation into light and for the generation of charge carriers by the resulting light. They environmentally summarizes a conversion layer having a plurality of embedded in a binder scintillator, wherein the binder contains at least a first organic semiconductor materials ^¬ rial. The embedded in the binder scintillator be ^¬ effect the conversion of ionizing radiation into light by excitation of fluorescence upon absorption of ionizing radiation. This light may be in view ^¬ cash range of the wavelength spectrum in particular, but it can alternatively or additionally also the adjacent regions of the infrared and / or ultraviolet light include. The conversion layer is designed in such a way that, in the surroundings of the scintillator particles, the generated light causes a generation of light. tion of free charge carriers can be effected. In particular, this generation can take place in the binder and / or in an additional coating of the scintillator particles. The emitted light can cause the formation of an excited state in a material surrounding the scintillator particles, which in turn results in the formation of separate positive and negative charges. Thus, a so-called charge carrier pair is formed. The conversion ^¬ layer is formed so that this charge carrier pair can be separated overall. For this purpose, the conversion layer we ^¬ nigstens comprises a first organic semiconductor material. This organic semiconductor material may suitably be either a material acting as an electron donor material for the transport of positive charge carriers (holes) or it may be acting as an electron acceptor material for transport of ne ^¬ negative charge carriers (electrons). Thus, at least one of the two types of charge carriers (electrons or holes) can be transported in the first organic semiconductor material. The oppositely charged other charge carrier type can expediently be transported in a further material present in the conversion layer. This further material may alternatively be formed as a further organic semiconductor or else quite generally as a conductive material, for example as an inorganic semiconductor or as a hybrid material with inorganic and organic components.

A significant advantage of the conversion film of the invention compared to conventional conversion foils or films comparison amplifier that scintillator material and another material for generating charge carriers separated by the light emitted by the scintillator in a layer are inte grated ^¬. From this layer, the separated La ^¬ makers can be extracted by means of additional electrodes. These electrodes, when used in a radiation detector, may be integrated into an electrical circuit configured to provide an electrical signal generate, which depends on the amount of the extracted charge carriers.

The advantage of the integration of light generation and charge separation within a conversion layer is that the problems of optical distortion described above are avoided at higher layer thicknesses. The conversion layer can be formed with a sufficiently high layer thickness for a good absorption of the X-ray radiation, without resulting in a loss of image sharpness due to optical distortion. The generation of the separated charge carriers pairs by the emitted light is very close to the place of origin of the light instead of embedding the scintillator in the Halbleiterma ^¬ TERIAL. The subsequent transport of the charge carriers to opposite surfaces of the conversion layer can be done very carefully by applying a voltage to electrodes applied there. This advantageously avoids a spatial widening of the charge carriers and thus a loss of image sharpness.

In comparison to known hybrid organic photodiodes, the advantage of the conversion film ^{according to} the invention is that the film is formed as an independent, flexible component. The conversion foil may expediently be free of switching elements, in particular free of readout transistors. It may be provided as a modular component to be subsequently connected to an array of readout transistors. In particular, the conversion film can be connected as a self-supporting film after its production with a Transis ^¬ torsubstrat.

By producing the conversion foil without an underlying transistor ^substrate, it is possible to select process parameters which are not compatible with a transistor substrate. In particular temperature and pressure ranges can be ge ^¬ selected, the damage to the transistor substrates or at least lead to a yield loss in a Pro ^¬ zessierung on transistor substrates.

The modularity of the conversion foil makes it possible to simplify the production of an organic photodiode with a hybrid conversion layer. For example, the Kon ^¬ version layer can be made entirely without the use of a Trägerub ^¬ strats, thereby completely new manufacturing ^¬ treatment methods are possible. In contrast to conventional coating methods, in which a substrate is coated with a liquid solution and / or a suspension of a solid in a liquid, an intrinsically stable film can also be rolled or extruded without substrate from high-viscosity starting materials. These starting materials may be, for example, dispersions of solid scintillator particles in a polymer or in one or more starting materials for a polymer.

Alternatively, the starting materials for the conversion layer may also be present in the form of a mixture of solids or of a moistened powder mixture. In the production of the conversion film, this conversion layer can rest on a temporary substrate, from which it can be redissolved, for example, after solidification of the conversion layer.

In the preparation of the conversion layer of highly viscous and / or solid starting materials, the material utilization can be significantly improved compared to the production of low-viscosity liquid phase.

The radiation detector according to the invention for the detection of ionizing radiation comprises at least one erfindungsge ^¬ Permitted conversion film. The advantages of radiation detector are analogous to the above-described advantages of the inventive ^¬ SEN conversion foil. The process for producing the conversion film according to the invention comprises the following steps:

- Preparation of a mixture of a variety of

Scintillator particles and a binder containing an organic semiconductive material,

- Making a layered structure of the mixture and

- Formation of a conversion layer by solidification of the layered structure.

An advantage of the method is that with this, the conversion film of the invention can be prepared in simp ^¬ che and material-saving manner. Wei ^¬ tere advantages result similar to the above-described benefits of the conversion foil. Thus, in particular the drive Ver ^¬ be simplified to manufacture a radiation detector according to the invention, since the entire manufacturing process can be split in several independent modular sub-processes. The production of a freely bearing conversion layer as a supplier part for the ^{Strahlungsdetek ¬} gate is possible.

Advantageous embodiments and further developments of the invention are based on the claims dependent on claim 1. The features of these embodiments and developments can be advantageously combined with the features of the radiation detector according to the invention and the manufacturing ^¬ method according to the invention and vice versa. Accordingly, the conversion film may additionally have the following features:

The conversion layer can be formed intrinsically stable. It can therefore be made so stable that it is freely supported even without a substrate. It can be handled as an independent, substrate-free layer and / or further processed. This is not precluded that it may for example be applied during the manufacturing process on a temporary sub ^¬ strat, but it is then so inherently stable in any case that they destructively from such a substrate is again solvable again. As an alternative or in addition to such a substrate during production, the conversion layer may in turn be connected to further supporting foils or other sub-strates prior to their use for radiation detection. It just depends on that the conversion layer is so inherently stable that it allows a handle lo ^¬ environment, transport and / or further processing without additional supporting carrier substrate. The conversion layer includes a plurality of embedded in a bin ^¬ DEMITTEL scintillator. Here the binder is particularly stable so selected that the convergence ^¬ immersion layer receives the required intrinsic stability. The bin ^¬ mediate can thus cause a sufficiently stable cohesion of Szintillatorpartikel. Alternatively or additionally, a cohesion between the adjacently arranged scintillator particles can be so pronounced that the conversion layer obtains its inherent stability even without a reinforcing effect of the binder.

Due to the intrinsically stable configuration of the conversion layer only this layer may for example be made as a separate Zvi ^¬'s factor, stored and used as needed to continue Her ^¬ position of a radiation detector according to the invention. The conversion layer is advantageous me ^¬ mechanically and chemically stable enough to be stored for periods of Mo ^¬ nate or years and to be brought as a separate product on the market. In this way, the production process of the radiation detector can be decoupled into various independent sub-processes, which can be carried out, for example, with a time interval and / or at different locations.

The conversion layer can be arranged on a carrier film. In particular, this carrier film may also be part of the Kon ^¬ version foil and give the actual conversion layer additional mechanical stability. In a Ver ^¬ use of the conversion film in a radiation detector can such support film either remain associated with the conversion layer, or it may be dissolved by the conversion layer as a temporary substrate such as the ^¬. In any case, it is expedient in these embodiments, if between the conversion layer and the carrier film, a flat

Electrode is arranged, which allows the extraction of ^{Ladsträ ¬} like to the adjacent surface of the conversion layer. The carrier film may preferably comprise, for example, a polymeric material and / or a metallic foil. In this case, the function of the planar electrode can also be taken over by the carrier foil, for example in the case of a metallic foil.

The conversion layer can be contactable over the entire surface. In other words, at least on one of its two main surfaces, a planar electrical contact to the organic semiconductor material containing can be created. For this purpose, the conversion layer can for example be freely accessible at least ei ^¬ ner of its two major surfaces. Then, a flat contact with a contact surface of another component can be created on this freely accessible side. For example, the freely accessible side can be electrically connected to con tact surfaces ^¬ a structured transistor substrate. Alternatively, the conversion layer can already be provided with a flat electrode on at least one of its two main surfaces. In particular, this planar electrode may be tert approaches in partial electrodes un ^¬ which can be for example connected to the contact surfaces of a structured transistor substrate. In embodiments in which the conversion layer is arranged on a carrier foil, the surface of the conversion foil which can be contacted in a planar manner is expediently the side facing away from the carrier foil. The binder may comprise at least two different organic semiconductor materials, of which the first semiconductor material is an electron donor and the second semiconductor material is an electron acceptor. So that's the first one Especially makers semiconductor material for transporting positive La ^¬ and the second semiconductor material is particularly suitable for transporting negative charge carriers. In this embodiment, therefore, both types of charge carriers of the charge carriers separated in the conversion foil are transported by organic semiconductor materials. The absorption of the light generated by the scintillator can take place either in the material of the electron donor and / or in the material of the electron acceptor and / or in another material of the Kon ^¬ version layer present in the environment of the scintillator particles. Here, so-called excitons are formed in the absorption mate ^¬ rial representing contiguous La ^¬ carrier pairs in an excited state. These excitons can diffuse to the interface between donor and acceptor materials and are advantageously separated at this interface into the two different charge carriers, which can then be transported away from each other in the two different materials. The binder of the conversion layer can be formed as a interpenetrating network of electron donor and domains of the domains of the Elektronenak ^¬ zeptors at least in a partial area. In other words, the binder may comprise a so-called bulk heterojunction. Particularly advantageously, the interpenetrating networks of the two materials form a common bicontinuous network ^¬ factory, that is, in each of the two domains are from the interfaces between the domains contiguous paths toward at least one surface of the CONVERSION layer. Here should not be ruled out that to ^¬ can additionally also be one of the islands domain or both domains. However, for a large part of the interface formed between the domains of the two materials, it is advantageous for such a connected path to be formed in each of the two materials. Such a bulk heterojunction can be formed by phase separation of a mixture of the materials involved. The binder may have an average absorption coefficient of at least 10 ³ cm ^-1 for the light generated by the scintillator particles. In the middle Absorptionskoef ^¬ coefficient is one over the various components of the binder and the different wavelengths of the emitted light averaged value. Particularly advantageously, the average absorption coefficient can be at least 10 ⁴ cm ^-1 . Such a high absorption coefficient shows a large difference to the properties of the binder material in BE ^¬ known cantilevered conversion or intensifying screens. In conventional intensifying screens, the bonding material must be transparent as possible so that as high a percentage of the emitted light to outside of the film located light ^¬ sensors can get. In the case of the present invention, it is however advantageous if the binder absorbs strongly as possible so that an exciton may be formed as close as possible at the site of Lichtent ^¬ stehung and hence possible close liehst a separation of the charge carriers can take place. This spatial proximity of the place of origin of the getrenn ^¬ charges imparted to the origin of the light, unnecessary optical expansion and therefore a blurring of the resulting image is advantageously avoided.

The average particle size of the scintillator can before ^¬ part way between 0.1 ym and ym are 500, especially before ^¬ some way it can be between 1 .mu.m and 50 .mu.m are. Towards the bottom, the advantageous values for the size of the scintillator particles are determined by the interaction length of the

X-ray-triggered high-energy electrons limited. In addition, it has been found that small Szin ^¬ tillatorpartikel typically have higher defect densities due to the unfavorable volume-to surface ratio ^¬ and thus non-radiative recombination of an excited state is observed. At too low Parti ^¬ kelgrößen the strength of light emission is therefore too low. At the top, the size of the scintillator particles is one Limited on the one hand by the thickness of the conversion layer and on the other hand by a desired high efficiency of the charge carrier transport. The particle sizes of the scintillator may be subject to Frequently ^¬ figkeitsverteilung. For example, the half width of such a distribution may advantageously be at least 30% of the average particle size. Advantageously, the size distribution can essentially follow the so-called Fuller curve:

D_i = (d_i / d_max) ^A n Where d_i describes a predetermined particle size, D_i d_i the cumulative percentage of the particles up to this size, d_max the maximum particle size and n the distribution module. The distribution module represents a geometry factor that assumes a value of 0.5 for spheres and decreases for elongated or flattened particles. Accordingly, for a distribution ^modulus of 0.35 and a maximum particle size of 10 μm, approximately half of the particles of the mixture should have a size smaller than 1.4 μm. With such a distribution can be a particularly high

Packing density of the scintillator be achieved because the smaller particles can fill the gaps between larger particles inevitably. A high packing density of the scintillator advantageously leads to a particularly high absorption and conversion of ionizing radiation at the lowest possible total thickness of the conversion layer and thus with lower consumption of Bin ^¬ dermaterials and expensive organic semiconductor material ^¬ lien.

Alternatively, however, it is also possible to use a scintillator particle having a relatively uniform size, for example, a half-width of the distribution of highest 10% in order to achieve the most uniform and defined packing, for example, so can be formed with spherical scintillator particles a kind of regular ball package.

Alternatively, a mixture of scintillator with two prevailing, relatively uniform sizes can be used, wherein the particles of smaller size are to geeig ^¬ net to the interstices in the closest possible parity ckung the larger particles fill.

The conversion layer may be a powder sintered layer. Such a sintering process is particularly suitable for producing a stable layer with a high density of scintillator particles, since the sintering process solidifies and compacts the starting material used. The powder used for this can be in particular a dry powder containing a mixture of the Szintilla ^¬ torpartikeln and one or more organic semiconductor materials. Alternatively, the powder may also be a slightly wetted powder with such a mixture and a liquid wetting this mixture. The production process of sintering is a compaction of the used Pul ^¬ vers under the influence of pressure and optionally temperature tur. The sintering pressure may advantageously be between 0.5 and 200 MPa, more preferably between 1 and 50 MPa. The pressure can be exerted on the powder layer, for example by means of a stamp, a roller or a rolling system. In this case, stamp, roller and / or rollers may be coated with a non-stick coating, for example with Teflon, so that the sintered layer can be well detached from the tool after the process. In addition, with such coated tools to achieve very homogeneous and smooth surfaces. The sintering of the layer can take place either on a layer that is free from the outset, for example in a rolling system, or else by pressing on a temporary substrate, from which the finished sintered layer can subsequently be released again. A temperature of the sintering process may advantageously be between 30 ° C and 300 ° C, more preferably between 50 ° C and 200 ° C. Depending on the choice of temperature, solid-phase sintering, ie material compaction without melting of the organic material, or else liquid-phase sintering, that is to say material compaction via at least partial melting of the organic material, is conceivable. As a result of the compression of the materials by means of pressure and, if appropriate, temperature, the interstices are minimized and compacted, so that when an electrical voltage is applied, electrical charge transport becomes possible, for example via hopping or redox processes between the individual organic molecules and / or polymer strands. In this way homogeneous or- ganic material layers of predetermined thickness without expensive vacuum process technology at high throughput and without health risks caused by possible solvents are realizable ^¬ bar. Due to the high pressures and temperatures that can occur during sintering, direct application of the conversion layer to a substrate is often difficult. In ^¬ example, plates with thin-film transistors made of amorphous silicon on glass substrates can be damaged by the action of pressure and / or temperature. The present invention enables the separate production of the conversion film and subsequent contacting with the Ausle ^¬ sesubstrat. Conversion layers produced by sintering can be detected and characterized on the basis of the morphology as well as the surface quality of the sintered layer, for example by detecting isolated or full-surface melted areas of the compressed starting powder. It may also be possible to indirectly draw conclusions about a sintering process, for example due to the absence of solvent traces and / or additives. Examples of methods of investigation are: optical microscopy, scanning electron microscopy, atomic force microscopy, secondary ion mass spectroscopy, gas chromatography, cyclic voltammetry. A plurality of the scintillator particles may comprise a shell having at least one photoactive material. In particular ^¬ sondere the photoactive material can be an organic Halbma ^¬ TERIAL. Such a covering or sheath may be conveniently achieved by coating the scintillator used particulate before production of the conversion layer ^¬ the. An essential advantage of such a coating is that a conversion layer with a high volume fraction of scintillator particles can be produced, wherein nevertheless the interstices between directly adjacent scintillator particles are at least partially filled with organic semiconductor material. Thus, absorption of the emitted light and separation of charges in these spaces can take place in these intermediate spaces. By maintaining a predetermined distance between the scintillator particles due to the coating, conductive

Form channels in the at least one organic semiconductor material, can be transported by the separated charge carriers to the respective surfaces of the conversion layer.

Particularly advantageously a plurality of the scintillator ^¬ particle is coated with a mixture of an organic donor and an organic acceptor material, the training a structure in the manner of a bulk Heteroj unction det. Then in this bulk heteroj unction the light of the

Scintillator be absorbed, it can be ^¬ separated charge carriers are generated, and the separated charge carriers can be transported through the domains of the respective donor or acceptor components to different surfaces or different areas on a surface of the conversion foil. Advantageously, the interstices between the ^coated scintillator particles can also be at least partially filled with another material. In particular, the coated scintillator particles may be embedded in a binder containing at least a first organic semiconductor material. The binder may also preferably comprise a mixture of an electron donor and an electron acceptor in the manner of a bulk heterojunction.

Alternatively, however, the inventive binder of the scintillator can be formed ^¬ be already made of the material of the coating or wrapping. For example, coated scintillator particles can be densified by a sintering process in such a way that the coating of the individual scintillator particles results in a stable coherent structure by pressing and / or fusing. Before ^¬ part way we can nigstens a portion of the directly adjacent scintillator located torpartikel be spaced apart by an interposed layer of Ma terials ^¬ the envelope ^¬ also at such a sintered layer. In this embodiment, gaps between the coated

Optionally, scintillator particles may be filled with another material that may contribute to the mechanical strength of the conversion film, but need not contain any further organic semiconductor material itself. For example, such an additional filler material can be a non-conductive poly ^¬ mermaterial. The required conductivity for the Trans ^¬ port of the separated charge carriers, in this exemplary form be guaranteed solely by the coating material ausgebil ^¬ Deten channels.

The enclosure of photoactive material may be the Szintilla ^¬ torpartikel on average at least 80%, particularly preferably cover at least 95% of its entire outer surface.

The coating of the scintillator particles can advantageously have an average thickness of 15 nm to 1500 nm, particularly preferably between 150 nm and 600 nm. The average thickness of the sheath can furthermore preferably correspond to a maximum of 2.5 times the penetration depth of the emitted radiation of the scintillator particles, so that the mean direct spacing of sheathed scintillator particles advantageously corresponds to a maximum of five times the penetration depth of the radiation.

The scintillator particles can have a weight fraction of the conversion layer between 80% and 98%. Such a high proportion by weight is advantageous in order to achieve a high absorption of the ionizing radiation in the conversion film. At the same time, the proportion of the other components of the conversion film, that is to say in particular the proportion of the ^binder and optionally an additional coating material, should not be unnecessarily high in order to keep the production costs as low as possible. A common proportion by weight of these other components of at least 2% is advantageous in order to enable the most continuous possible network of conductive material for transporting the separated charge carriers to the surface of the conversion foil.

The binder may advantageously be at least one polymer ^¬ material, especially an organic polymer material umfas ^¬ sen. The use of a polymer material can advantageously bring about a particularly high strength and mechanical strength of the conversion film. It is possible that a stable cohesion of the film with a high proportion of scintillator particles is achieved in the first place by the use of a polymeric material as constituent of the binder. Such a polymer material may be a polymeric organic semiconductors, for example, which then preferably simultaneously Wenig ^¬ fulfills the functionality of conductivity least one charge carrier type and functionality of the me chanical ^¬ cohesion. Can guide die in an alternative off the polymeric material, however, also be nichtlei ^¬ and tend only as a support material for one or several ^¬ re serve conductive components present in the binder. Examples of such non-conductive polymer materials are polymethyl methacrylate, polyester or cellulose triacetate.

The layer thickness of the conversion layer may advantageously be between 10 .mu.m and 1 mm, particularly advantageously between 50 .mu.m and 500 .mu.m. A configured in this manner ^¬ conversion layer is thick enough to cause a sufficiently high absorption and conversion of ionizing radiation. On the other hand, it is sufficiently thin to permit efficient extraction of the separated charge carriers by an electric field applied to the outer sides of the foil.

The absorption of the conversion film for X-ray radiation with an energy of 60 keV can advantageously be at least 50%, particularly advantageously at least 70%. This would apply to a vertical passage of the radiation through the film in particular ^¬ sondere.

The light wavelength of at least one emission peak of the scintillator may be within the bandwidth of an Ab ^¬ absorption maximum of the binder. In other Wor ^¬ th, the absorption spectrum of the binder may be advantageously adapted on at least a portion of the emission spectrum of the scintillator. The emission bands of the scintillator particles should therefore have an overlap with at least one ^absorption band of at least one component of the binder. As a result, a high efficiency for the generation of separate charge carriers by the light emitted by the scintillator can be effected.

The choice of particularly suitable materials for the components, in particular the light-absorbing components of the binder thus depends on the choice of the material for the Szintillatorpartikel. Exemplary combinations of materials for a combination of scintillator particles with photoactive organic materials for different wavelengths are as follows: Suitable green scintillators are, for example, Gd ₂ <O ₂ S: Pr, Ce (gadolinium oxysulfide doped with praseodymium and cerium having an emission maximum at approximately 515 nm),

Gd ₂ <0 ₂ S: Tb (gadolinium oxysulfide doped with terbium with an emission maximum at about 545 nm), Gd ₂ Ü ₂ S: Pr, Ce, F

(Gadolinium oxysulfide doped with praseodymium or cerium or fluorine having an emission maximum at about 510 nm),

YAG: Ce (yttrium aluminum garnet doped with cerium having an emission maximum at about 550 nm), CsI: Tl (cesium iodide doped with thallium with an emission maximum at about 525 nm), CdI ₂ : Eu (europium-doped cadmium iodide with a Emission maximum at about 580 nm) or

Lu ₂ Ü3: Tb (terbium lutetium oxide doped with a TERMS ^¬ onsmaximum at about 545 nm). These green scintillators are characterized by an emission maximum in the range of

515-580 nm and are thus well on the absorption maximum of poly (3-hexylthiophen-2, 5-diyl) (P3HT) as an exemplary photoactive material of the organic matrix at 550nm ^¬ out. The scintillator Bi ₄ Ge ₃ Oi 2 or BGO (bismuth germanate with an emission maximum at about 480 nm) can be mixed well with poly [2-methoxy-5- (2-ethylhexyloxy) -1, 4-phenylenevinylene] (MEH-PPV) or poly [2-methoxy-5- (3 ', 7'-dimethyloctyloxy) -1, 4-phenylenevinylene] (MDMO-PPV) which have good absorption in the 460-520 nm range.

Suitable blue scintillators are also mentioned. An attractive material combination with emission in the blue represents Lu ₂ Si05iCe or LSO (cesium-doped lutetium oxyorthosilicate with an emission maximum at about 420 nm), Lui.8Y. ₂ S1O ₅ : Ce (cerium-doped lutetium oxyorthosilicate with an emission maximum at about 420 nm), CdW0 ₄

(Cadmium tungstate with an emission maximum at about 475 nm), CsI: Na (cesium iodide doped with sodium with an emission maximum at about 420 nm), or NaI: Tl (thallium doped sodium iodide with an emission maximum at unge ^¬ ferry 415 nm), Bi ₄ Ge30i ₂ and BGO (bismuth germanate with an emission maximum at about 480 nm), Gd ₂ SiOsbzw. GSO

(Gadolinium oxyorthosilicate doped with cerium with an emission onsmaximum at about 440 nm), or CsBr: Eu (cesium bromide doped with europium with an emission maximum at about 445nm) is that good (with typical wide-band-gap semiconducting ^¬ tern semiconductors with a large bandgap) such as poly [(9, 9 -di-n-octylfluorenyl-2, 7-diyl) -ALT- (benzo [2,1,3] thiadiazole-4,8-diyl)] (F8BT) having an absorption maximum at 460nm or other polyfluorene (PFO) polymers and co-polymers having an absorbance at 380-460 nm can be combined. Red scintillators such as Lu ₂ O 3: Eu (lutetium oxide doped with

Europium with an emission maximum at about 610 to 625 nm), Lu ₂ Ü3: b (lutetium oxide doped with terbium with a TERMS ^¬ onsmaximum at about 610-625 nm) or Gd ₂ <0 _3: Eu

(Gadolinium oxysulfide doped with europium with an emission maximum at about 610-625 nm), YGdO: (Eu, Pr) (europium and / or praseodymium-doped yttrium gadolinium oxide having an emission maximum at about 610 nm), GdGaO: Cr, Ce (chromium and (or cesium-doped gadolinium-gallium oxide), or Cul (copper iodide with an emission maximum at about 720 nm), can be combined well with absorbers such as those developed for organic photovoltaics, for example poly [2,3,1-benzothiadiazole]. 4,7-diyl [4,4-bis (2-ethylhexyl) -4H-cyclopenta [2, 1-b: 3, 4-b '] dithiophene-2, 6-diyl]] (PCPDTBT), squarains (eg Hydrazone end-capped symmetrical squarains with glycolic functionalization or diazulenequarains), polythieno [3,4-b] thiophene (PTT) or poly (5,7-bis (4-decanyl-2-thienyl) thieno (3,4-b ) diathiazolethiophene-2, 5) (PDDTT).

Of particular note according to preferred embodiments among these pairs: Gd ₂ <0 ₂ S: Tb or YAG: Ce in combination with Nati ^¬ on P3HT, Lu ₂ Si0 _5: Ce in combination with F8BT or YGdO: Eu with PCPDTBT. In these examples, the organic semiconductors P3HT, F8BT and PCPDTBT each simultaneously fulfill the function of the absorbing component and the hole-conducting electron donating component of the binder.

Particularly suitable materials for an electron-accepting component of the binder are fullerenes and their Derivatives such as [6, 6] -phenyl-C6i-butanoic acid methyl ester (PCBM).

The conversion film may comprise at least one first electrode, which is preferably arranged on at least one first surface of the conversion layer. Particularly preferably, the conversion foil may comprise at least two electrodes umfas ^¬ sen, which may be expediently arranged on opposite surfaces of the conversion layer. Preferably, these two electrodes are designed for the extraction of the two different types of charge carriers, in other words, it can be an anode and a cathode.

At least one of the two electrodes can be formed over a large area, in other words, it can cover a large part of one of the surfaces of the conversion film. It can also be formed over a large area both electrodes.

It can also be structured, at least one of the electrodes be formed off, in particular it may comprise a regular Anord ^¬ voltage of partial electrodes. For example, at least one electrode may be subdivided into a multiplicity of like sub-electrodes to enable readout of a spatial image of the ionizing radiation in a plurality of pixels. For this purpose it is particularly advantageous when an electrode is formed over a large area and an opposite electrode on the other Be ^¬ te conversion film into individual pixels structured out ^¬ forms is. The structured electrode may be either the anode or the cathode. But it is also possible that both electrodes are divided into individual pixels.

Advantageously, a structured electrode having at least in one or two directions in space has a structure size of between 0.3 .mu.m and 100 .mu.m, especially advantageous ^¬ adhesive is between 0.3 .mu.m and 30 .mu.m. Suitable materials for the electrodes include metals such as aluminum, silver and gold or conductive oxides such as indium tin oxide at ^¬ game. As an alternative or in addition to such electrode layers, the conversion film may be provided on at least one surface with a contact material which is formed as a large-area film with anisotropically conductive properties.

In an alternative embodiment, the conversion foil may be free of electrodes. Suitable electrodes for the extraction of the charge carriers from the conversion layer can then be connected, for example, in a later step as a further constituent of a radiation detector with the conversion ^coefficient .

The conversion foil may optionally additionally comprise at least one intermediate layer between the conversion layer and one of the electrodes. Such an intermediate layer can be used, for example, either as a hole blocking layer or as

Electron blocker layer may be formed.

The conversion foil may optionally comprise one or more additional protective layers which prevent the penetration of

Dust, water and / or oxygen in the film and associated aging prevented. This protective layer may be designed so that it is removed during processing in a detector prior to connection to a substrate or remains in the finished component. For example, remain a first protective film on the upper side as water and Sauer ^¬ material barrier, while a second protection ^¬ film is drawn off on the bottom before the bottom is connected to a substrate, for example a transistor matrix.

The conversion foil may optionally have an adhesion layer which facilitates connection to a substrate. tert. The adhesion layer can be designed, for example, as an anisotropically conductive adhesive and can be coated with a protective film until it is assembled. The radiation detector for detection of ionizing radiation with the conversion film may additionally have the following wide ^¬ re features:

Suitably, it may comprise at least one electrode arranged adjacent to a first surface of the conversion layer. In addition, it can ^encompass a second electrode, which is arranged adjacent to a second surface of the conversion layer. These can advantageously be disposed on opposite surfaces of the electron, re insbesonde- the two major surfaces of the conversion coating at ^¬. Either of these two electrodes or even both electrons can either already be part of the conversion foil, or they can be present in the radiation detector as additional elements which are subsequently connected to the conversion foil.

The electrodes are useful for electrical

Transport of the two separate types of charge carriers from the conversion foil. In this case, an electrode may expediently be in the form of a cathode and the second electrode may be in the form of an anode.

Between the conversion layer and at least one of the electrodes, an additional intermediate ^layer may optionally be additionally arranged. This intermediate layer may be a hole blocker layer which is designed to transport electrons and / or to block holes (positive charge carriers). Alternatively or additionally, it may be an electron blocking layer which is designed to transport holes and / or to block off electrons.

The radiation detector may further be divided into individual image elements, for example by patterning we ^¬ nigstens one of the electrodes in a variety of Teilelek- trodes. In this embodiment, the radiation detector may further comprise a plurality of switching elements for driving and / or reading the individual picture elements. In particular, one or more switching elements can be assigned to each picture element. Be the switching elements Kgs ^¬ NEN such as transistors, particularly thin film transistors made of amorphous silicon.

A particular advantage of such a radiation detector, that no complex process steps must be performed on the emp ^¬-sensitive switching elements by the use of the cantilevered conversion film of the invention. In particular, the production of the conversion layer does not have the sensitive switching elements is carried out but the FER term conversion foil can be subsequently connected to this scarf Tele ^¬ ments. For example, a glass plate having a plurality of thin-film transistors can be subsequently connected to the already finished conversion foil. In this case, the thin-film transistors can already be equipped with an electrode and be connected to a Konversi ^¬ onsfolie which is equipped only on the opposite side with a large-area contact. Alternatively, the conversion foil can already be provided with electrodes during its production, or it can be provided with electrodes subsequently, for example only when it is connected to the transistor substrate. The transistors may be advantageous thin-film transistors made of amorphous silicon or a metal oxide. The subsequent connection of an arrangement of Schaltele ^¬ elements with the finished conversion film in any case has the advantage that the material yield can be significantly improved. In particular, there is no unnecessary waste of transistor plates in the deposition of a complicated layer system of scintillator particles and organic semiconductor materials. The method for manufacturing the conversion film may additionally have the following features in addition to the previously already described variants: the scintillator can be provided with a casing prior to the production of the conversion layer having at least a photoactive material, in particular a pho ^¬ toaktiven organic semiconductor. The conversion layer can be produced by sintering a powdery starting material. In particular, this is a self-stable conversion layer can generate the ^¬. The conversion layer can be prepared by polymerization of at least one constituent of the binder and / or ver ^¬ consolidated.

The conversion film can be produced by an extrusion process. Particularly advantageously a conversion layer and an electrically leit ^¬ capable material can be applied at this from ^¬ design variant, one or more electrodes by co-extrusion. For example, conductive flat silver particles can be coextruded together with the conversion layer. Alternatively or additionally, the conversion layer can also be co-extruded with a carrier film.

The invention will be described below with reference to several preferred embodiments with reference to the attached drawings, of which:

1 shows a schematic cross section of a conversion foil according to a first exemplary embodiment,

Fig. 2 shows a schematic detail view of a conversion ^¬ layer according to a second embodiment, 3 shows a schematic cross section of a conversion foil according to a third exemplary embodiment,

4 shows a schematic cross section of a conversion foil according to a fourth exemplary embodiment,

Fig. 5 illustrates the process of applying a conversion foil to a transistor substrate,

Fig. 6 shows a schematic cross section of a conversion foil according to a fifth embodiment, and

Fig. 7 shows the process of applying a conversion foil

according to a sixth embodiment on a transistor substrate shows.

FIG. 1 shows a schematic lateral cross section through a conversion foil 1 according to a first exemplary embodiment of the invention. Shown is a free-bearing Konver ^¬ sion layer 3, which is formed substrate-free and without further associated electrodes or other laminar layers in this example. In this example, therefore, the conversion film consists solely of the conversion layer 3. The conversion layer 3 has a plurality of scintillator particles 5, which are embedded in a binder 3. The scintillator particles 5 essentially consist of Gd ₂ O ₂ S: Tb, ie of terbium-doped gadolinium oxy sulfide. This scintillator is a good X-ray absorbing material that emits green light when excited by ionizing radiation.

The scintillator particles 5 are embedded in an absorbing in the green region of the spectrum binder 7, which gives the self-supporting ^self-¬ properties of the conversion layer 3 of the sheet. 1 The scintillator particles 5 have a size distribution with two pronounced maxima, so there is a mixture of larger particles 5a with smaller particles 5b. As a result, a particularly high volume of space filling the volume of the conversion layer 3 by the

Scintillator 5 can be achieved. The proportion by weight of the scintillator particles 5 is still much higher than the volume fraction, since the scintillator particles 5 have a substantially higher density than the binder 7, so that the ionizing radiation substantially in the

Scintillator particles 5 is absorbed.

In the illustrated example, the binder 7 is a mixture of the light-absorbing in the green and hole transporting polymer P3HT (poly (3-hexylthiophene-2, 5-diyl)) and the elekt ^¬ Ronen transporting fullerene derivative PCBM ([6, 6] -phenyl C6i-butanoic acid methyl ester). These two materials form a phase-separated bulk heterojunction in the binder 7, in which, after the light absorption by the P3HT, a separation and subsequently a separate transport of the two types of charge carriers to the surfaces of the conversion layer 3 located at the top or bottom in FIG. The poly- mers P3HT material gives the conversion layer 3 while a sufficient strength, to ge ^¬ be handles without a supporting substrate. The conversion layer 3 is made in this example by sintering a powdery mixture of the scintillator particles, P3HT and PCBM.

Fig. 2 shows a detailed view of a conversion layer 3 according to a second embodiment of the invention. In this example, a multiplicity of scintillator particles 5 of similar size are each provided with an envelope 9. The envelope 9 is again a mixture of P3HT and PCBM forming a bulk heterojunction. The conversion foil 3 according to this second exemplary embodiment was also obtained by sintering a mixture of the particles 5 coated in this way, wherein during the sintering process the sheaths 9 of the individual particles merge to form a continuous conductive network. In this case, 9 also affect the amount together Schmolze ^¬ nen servings as a binder but 7. In addition, the further gaps 10 between the coated particles 5 may be filled with further binder 7, for example, in turn, with a P3HT / PCBM mixture or with another, the mechanical strength supporting ^¬ zenden material.

The conversion layer 3 shown in FIG. 1 is not yet provided with electrodes and can be stored as a self-supporting component 1 or placed on the market. In the further course, the conversion layer 3 can also be provided with electrodes. Thus, FIG. 3 shows a schematic cross section through a conversion film 1 according to a third embodiment, in which the conversion ^¬ layer 3 by laminating thin films having two metal electrodes 11 and 13 was provided. These electrodes act as an anode and as a cathode and serve to extract the two types of charge carriers on opposite surfaces of the conversion layer 3. The conversion film can either be stored with or without such electrodes 11 and 13 and / or marketed as a separate product.

FIG. 4 shows a further conversion foil 1 according to a fourth exemplary embodiment of the invention, in which likewise an upper electrode 11 and a lower electrode 13 are applied on opposite sides of the conversion layer 3. In this example, the lower electrode 13 is structured into a plurality of sub-electrodes 13a, of which five are shown by way of example in the figure. The un ^¬ tere surface of the film is in its two spatial directions in a regular arrangement in such partial electrodes 13a structured. The structure of the lower electrode can be obtained example by laser structuring of a laminated film or else by lithographic patterning at ^¬. The division of one of the two electrodes into a plurality of sub-electrodes 13a enables a pixel- lierte reading of the spatial distribution of the ionizing radiation, so for example the generation of an X-ray image. The pixel width is the width 15 of the Given sub-electrodes and the pixel spacing is given by the distance 17 of the sub-electrodes. The so-called pixel pitch, ie the spatial repetition length, results as the sum of width 15 and distance 17. In order to read a pixelated image, it is not necessary for both electrodes to be structured. There must be a separation of the electrical Sig ^¬ Nals by pixels only on one side of the conversion layer. 3 Either the anode can be structured and the cathode can be formed over the entire surface or vice versa. In any case, the conversion ^¬ layer 3 are present as an unstructured flat layer, and it will still receive a locally resolved image that is sharper than when coupled to a conventional image intensifier film with a photo sensor. This is made possible by a spatially directed extraction of the charge carriers upon application of a bias voltage to the opposing electrodes 11 and 13.

Fig. 5 shows, finally, a possible process step for application of the conversion film 1 of the fourth embodiment 19 of a transistor substrate, the transistor ^¬ substrate 19 includes an arrangement of a plurality of thin film transistors 21 on a glass substrate 23. Here, for example, transistors may be used made of amorphous silicon, as used in the control of flat screens. The inherently stable conversion foil 1 with its structured lower electrode 13 can now be applied to the transistor substrate 19 by means of a roller 25 and be laminated thereon, for example, by the action of pressure and / or elevated temperature. For this purpose, the grid of the thin-film transistors in both spatial directions of the film should be adapted to the grid of the structured electrode 13. However, there does not have to be an exact spatial orientation of the conversion foil 1 to the transistor substrate 19, since only one spatially relatively small contact point 26 of the transistors 19 has to be brought into electrical contact with the respective part electrode 13a. A GeWiS ^¬ ser spatial offset from a center contact or another ideal position can easily be accepted without compromising functionality.

The sub-electrodes 13a on the conversion foil 1 can also be made significantly smaller than the pixel pitch of the transistor matrix. A corresponding fifth exporting ^¬ approximately example is shown in Fig. 6. Here, the Tran ^¬ transistors 21 are each provided with large contact areas 26. The size of the sub-electrodes 13a is smaller in both spatial directions of the surface than the gap 28 between the contact surfaces 26. Thus, the alignment of the two elements is completely uncritical. The typical

Pixel pitch 29 of an ionizing radiation detector is between 30 and 300 microns. The gap 28 between two adjacent pixels is typically between 2 and 20% of the pixel size, typically between 0.6 and 60 microns. With a correspondingly small selected size of the sub-electrodes 13a, for example half of the interspace 28 (ie between 0.3 and 30ym), a problem-free contacting is possible without generating a short circuit between adjacent contact surfaces 27.

Furthermore, it is possible to produce a conversion foil 1 with only one large-area electrode 11 on one side of the conversion layer 3. On the opposite side of the conversion layer 3 can then be contacted freely accessible and sur fa ^¬ chig. More specifically, the conversion can be assembled ^¬ layer 3 then on this side contactable with a transistor matrix, wherein the structured contacts are already on the transistors 21 ^¬ introduced 13a and are conductively connected to the contacting points 26th This process of assembly is shown in Fig. 7 exemplifies a sixth exemplary embodiment of the ^¬ invention. The conversion foil 1 of this sixth exemplary embodiment comprises a conversion layer 3 which is arranged on a carrier foil 32. This carrier film ver ^¬ lends conversion film 1 additional mechanical Stabili ^¬ ty. Between the carrier film 1 and the conversion layer is a large area, unstructured first electrode 11 to ^¬ ordered. On the opposite side the Konversi ^¬ onsschicht 3 is exposed. In the illustrated process step, it is connected on this exposed side with the structured partial electrodes 13 a, which are already applied to a transistor substrate 19 in a regular arrangement on the individual transistors 21. The compound is created in this example by applying by means of a roller 25, for example, again under the action of pressure and / or elevated temperature.

Finally, it is also possible to carry out the contact between the conversion layer 3 and the contact points 26 of the transistors 21 as large-area contact with anisotropic conductive intrinsic properties. The contact may be embodied as an anisotropically conductive film or adhesive. To process a conversion foil with anisotropic contact, the foil is brought into contact with the transistor matrix and the anisotropic contact is produced by exerting pressure and / or temperature. This will be the electrical

Crosstalk between two adjacent contacts is minimized.

The created by the flat connection of conversion foil 1 and transistor substrate 19 radiation detector 30 ER- eventually enables the detection of a locally resolved image of the incident on the conversion sheet 1 ioni ^{¬-stabilizing} radiation. The respective sub-electrodes 13a are each driven and read out by a thin-film transistor 21. A higher-level control and read-out electronics (not shown here) can be used to apply a defined bias voltage between the two electrodes for each pixel, to control the pixels or groups of pixels (for example rows or columns) one after the other and for the individual pixels in each case read out an electrical signal that depends on the number of charge carriers extracted at the respective sub-electrodes 13a. The present invention thus enables a simplified and modular production of a radiation detector 30 with a high process yield. The radiation detector 30 is suitable for obtaining locally high-resolution images with simultaneously high conversion efficiency for the ionizing radiation.

Claims

claims

1. Conversion film (1) for the conversion of ionizing radiation into light and for the generation of charge carriers by the light,

comprising a conversion layer (3) having a plurality of scintillator particles (5) embedded in a binder (7),

wherein the binder (7) contains at least a first organic semiconductor material.

2. Conversion film (1) according to claim 1, wherein the Konversi ^¬ onsschicht (3) is formed intrinsically stable.

3. Conversion film (1) according to any one of claims 1 or 2, wherein the conversion layer (3) on a carrier film (32) is arranged.

4. Conversion film (1) according to one of the preceding claims che, wherein the conversion layer (3) at least on one

Surface is contactable surface.

5. conversion film (1) according to any preceding Ansprü ^¬ che, characterized in that the binder infrequent stops ent ^¬ (7) least two different organic semiconductor materials, of which the first semiconductor material, an electron ^¬ donator and the second semiconductor material is a Elektronenak ^¬ zeptor is.

6. Conversion film (1) according to claim 5, ^wherein the binding medium ^¬ (7) is formed at least in a partial area as a mutually penetrating network of domains of the electron donor and domains of the electron acceptor.

7. conversion film (1) according to any preceding Ansprü ^¬ che, characterized in that the binder (7) has a mean absorption coefficient of at least 10 ³ cm ^-1 for by the scintillator (5) generated light.

8. conversion film (1) according to any preceding Ansprü ^¬ che, in which the average particle size of the particulate scintillator (5) is between 0.1 ym and 500 ym is located.

9. Conversion film (1) according to any one of the preceding Ansprü ^¬ che, characterized in that the conversion layer (3) is a sintered from a powder layer.

10. Conversion film (1) according to one of the preceding claims, characterized in that the Szintillatorpar- particles (5) have a weight fraction of the conversion layer (3) between 80% and 98%.

11. Conversion film (1) according to one of the preceding claims, characterized in that the binder (7) comprises at least one polymer material ^¬ .

12. Conversion film (1) according to any one of the preceding claims, characterized in that the layer thickness (4) of the conversion layer (3) is between 10 ym and 1 mm.

13. Conversion film (1) according to one of the preceding claims, in which at least one first surface of the conversion layer at least one electrode (11,13) angeord ^¬ net is.

14. Radiation detector (30) for detecting ionizing radiation with a conversion film (1) according to any one of claims 1 to 13.

15. A method for producing a conversion film (1) according to any one of claims 1 to 13, comprising at least the fol ^¬ ing steps:

Preparing a mixture of a plurality of scintillator particles (5) and a binder (7) containing an organic semiconducting material, - Making a layered structure of the mixture and

- Formation of a conversion layer (3) by solidification of the layered structure.