EP-4740045-A1 - RADIATION DETECTOR

EP4740045A1EP 4740045 A1EP4740045 A1EP 4740045A1EP-4740045-A1

Abstract

A device (1) for converting incoming radiation into positive and negative electrical charges, the device comprising: a network (2) comprising: a first semiconductor material for transporting positive electrical charges; and a second semiconductor material for transporting negative electrical charges. The first and second semiconductor materials being dispersed within the network to provide a plurality of electrical junctions, wherein, the network further comprises a plurality of nano-structured agglomerates (3) dispersed within the network, the nano-structured agglomerates (3) comprise a plurality of regions and/or interfaces of different relative permittivity capable of creating dielectric inhomogeneities within the nano-structured agglomerates.

Inventors

SILVA, SEMBUKUTTIARACHILAGE RAVI PRADIP

Assignees

Silverray Limited

Dates

Publication Date: 20260513
Application Date: 20240704

Claims (20)

1 .) A device for converting incoming radiation into positive and negative electrical charges, the device comprising: a network comprising: a first semiconductor material for transporting positive electrical charges; and a second semiconductor material for transporting negative electrical charges, the first and second semiconductor materials being dispersed within the network to provide a plurality of electrical junctions, wherein, the network further comprises a plurality of nano-structured agglomerates dispersed within the network, the nano-structured agglomerates comprise a plurality of regions and/or interfaces of different relative permittivity capable of creating dielectric inhomogeneities within the nano-structured agglomerates.
2.) A device as claimed in claim 1 , wherein, the nano-structured agglomerates comprise: a) a plurality of regions and/or interfaces of different relative permittivity comparable to, or within, a wavelength of said incoming radiation; and/or b) a porosity or void fraction of about 0.01 to about 0.99, of about 0.05 to about 0.7, or about 0.1 to about 0.3.
3.) A device as claimed in claim 1 or claim 2, wherein, the nano-structured agglomerates comprise: one or more, or a plurality of, solid nano-particle structures; and one or more, or a plurality of, voids between the one or more, or plurality of, solid nano-particle structures.
4.) A device as claimed in any preceding claims, wherein the nano-structured agglomerates are configured to speed-up and slow-down received radiation, creating one or more, or a plurality of positively or negatively charged puddles within surface structures of the agglomerates.
5.) A device as claimed in any preceding claim, wherein the surface structures of the nano-structured agglomerates, whether external and/or internal surface structures, are configured to interact with incoming radiation to attenuate the radiation and provide improved conversion to positive and negative electrical charges.
6.) A device as claimed in any preceding claim, wherein the plurality of nanostructured agglomerates are configured to: act as local inhomogeneities capable of attracting and concentrating the electric field; and/or convert said radiation into positive and negative electrical charges in radiation-agglomerate interaction events.
7.) A device as claimed in any preceding claim, wherein the plurality of nanostructured agglomerates are doped nano-structured agglomerates, having additional electron-containing or hole-containing elements.
8.) A device as claimed in claim 7, wherein the plurality of nano-structured agglomerates are doped with Caesium (Cs) and/or Lanthanum (La).
9.) A device as claimed in any preceding claim, wherein the plurality of nanostructured agglomerates comprises optimised parameters of one or more of the following group, comprising: nano-particle and/or agglomerate size; nano-particle and/or agglomerate distribution; void fraction of the nano-structured agglomerates; and/or doping.
10.) A device as claimed in any preceding claim, wherein the first and second semiconductor materials comprise: organic-organic transport materials; inorganic-inorganic transport materials; or organic-inorganic transport materials.
11.) A device as claimed in any preceding claim, wherein the nano-particles comprise: high-Z nano-particles; organic nano-particles; or combinations thereof.
12.) A device as claimed in any preceding claim, wherein parameters of the nanostructured agglomerates are configured to be actively optimised for detection of defined wavelengths or forms of radiation intended to be detected by the device.
13.) A device as claimed in any preceding claim, wherein, the first semiconductor material comprises P3HT, the second semiconductor material comprises PCBM, and the nano-particles comprise Bi20s, optionally doped with Caesium (Cs) and/or Lanthanum (La).
14.) A radiation detector comprising: a first electrode; a second electrode; and a device as claimed in any one of claims 1 to 13 located or sandwiched between the first and second electrodes.
15.) A system comprising a plurality of radiation detectors as claimed in claim 14, wherein at least some of the plurality of radiation detectors are configured to: detect multiple different types of radiation; detect one type of radiation; and/or identify or detect different energies of a particular radiation.
16.) A method comprising: using a device as claimed in any one of claims 1 to 13, a radiation detector as claimed in claim 14, or a system as claimed in claim 15 to convert incoming radiation into positive and negative electrical charges; and recording a characteristic generated by the positive and negative electrical charges.
17.) A method as claimed in claim 16, further comprising converting the incoming radiation into free positive and negative electrical charges in radiation-agglomerate interaction events.
18.) A method as claimed in claim 16 or claim 17 comprising generating current in response to application of a voltage across the device and converting recorded current into an estimate of a level of incoming radiation.
19.) A process for providing a network for a device for converting incoming radiation into positive and negative electrical charges, the process comprising: dissolving first and second semiconductors in one or more solvents, the first and second semiconductors being capable of transporting positive and negative electrical charges, respectively; adding a plurality of nano-particles and dispersing the plurality of nanoparticles to form a matrix; and agglomerating the nano-particles in the matrix to form a plurality of nanostructured agglomerates, the nano-structured agglomerates comprising a plurality of regions and/or interfaces of different relative permittivity, being capable of creating dielectric inhomogeneities within the nano-structured agglomerates.
20.) A process as claimed in claim 19 comprising creating: a plurality of regions and/or interfaces of different relative permittivity comparable to, or within, a wavelength of said incoming radiation; one or more, or a plurality of, solid nano-particle structures; and one or more, or a plurality of, voids between the one or more, or plurality of solid nano-particles structures.

Description

Radiation Detector The present invention relates to radiation detection, in particular radiation detection apparatus and associated method(s). The present invention further relates to a device, apparatus and method for converting incoming radiation into positive and negative electrical charges. The widespread use of ionising (e.g. nuclear) radiation for a range of applications, such as in radiation therapy, security screening and industrial applications such as non-destructive testing (NDT), has necessitated the development of appropriate radiation detection techniques. Here both the terms “ionising radiation” and “nuclear radiation” are considered to extend to alpha particles, beta particles, X-rays, gamma rays and so on. Common nuclear radiation detectors comprise semiconductor devices, typically silicon (Si) or germanium (Ge). These solid-state devices detect nuclear or ionising radiation by measuring the number of charge carriers (electrons and holes) generated in the detector volume in response to incident radiation. When high-energy radiation photons or particles collide with the active semiconductor material in the detector, it causes ionisation and creates charge carriers. Ionisation is created by charge being generated within the device structure as a result of external radiation either displacing electrons from core-shells of the atom or high-speed radiation interacting with solid matter. The generated charge carriers are accelerated under the influence of an electric field generated by an applied voltage bias. This leads to an electric current which can be readily collected at electrodes. Current can be found to be proportional to the radiation dose deposited in the material. Depending upon the energy of the photons of incident radiation and the atomic number (Z) of the material, there are three main mechanisms through which matter is widely attributed to interact with the incoming photons, namely, the photoelectric effect, Compton scattering and pair production. Detectors typically measure the amount of radiation incident, the spatial distribution, the radiation spectrum and other properties. Solid-state inorganic radiation detectors based on silicon are known. Despite the excellent performance of inorganic detectors, they suffer from major drawbacks owing to the crystalline detector materials used, such as the manufacturability of curved geometries, brittle active materials, high manufacturing costs and limited detector size. In comparison to their better established inorganic counterparts, organic semiconductors (e.g. semiconducting polymers) present several advantages which make them an attractive candidate for large area, low-cost electronics. Inks consisting of these organic semiconductors can be prepared by dissolving conjugated polymers, oligomers and small molecules in common organic solvents. These inks can then be simply coated onto substrates using conventional wet processing techniques, leading to the possibility of large area device production at extremely low cost. Owing to their flexible nature, large area organic semiconductor based detector panels can be formed to curved geometries, such as tubes, to place around piping to monitor radioactive fluids, for example. Flexible organic dosimeters can also be used for patient dosimeters, for X-ray diagnostics or cancer therapy, for example, by forming large area pixelated detector tubes around parts of a patient’s body, such as a limb, to provide localised spatial-resolved dose measurements. Some features of known high-energy radiation detectors include low dark current (leakage current), good rectification behaviour, high charge-carrier mobility and high radiation stopping power. Generally, radiation detectors can be subcategorized as ‘direct’ or ‘indirect’ detectors. Previously it has been shown that radiation-induced photocurrent can be achieved using single homogeneous materials such as poly-(triarylamine) (PTAA), poly([9,9-dioctylfluorenyl-2,7-diyl]-co-bithiophene) (F8T2), etc. in a metal/sem iconducting polymer/metal device architecture in direct radiation detectors. Such materials are active polymer materials, but they are only capable of carrying a single type of charge (electron or hole). The mono-carrier nature of devices incorporating single homogeneous materials (single organic semiconductor systems) reduces the overall signal response that can be achieved. The organic semiconductors typically consist of low atomic number (low Z) carbon and hydrogen constituent atoms, which results in a low stopping power (attenuation) for high-energy radiation. Therefore, this means that, for an organic material detector to operate efficiently, it needs to be very thick so there are enough ionisation events created in order to produce a suitable current that can be detected. Yet, as the mobility of the detected carriers is so low within organic materials (typically polymeric materials insulate owing to a lack of free carriers and have a