Systems and methods for radio photovoltaic cells

Abstract

A device may include a semiconductor photovoltaic body having an incident surface and a rear surface. A device may include a microhole in the semiconductor body formed at least in the incident surface. A device may include a plurality of nanoparticles positioned in the microhole. A device may include a charge collection layer proximate to the rear surface of the semiconductor photovoltaic body and configured to receive charge from the semiconductor photovoltaic body.

Description

SYSTEMS AND METHODS FOR RADIO PHOTOVOLTAIC CELLSGOVERNMENTAL RIGHTS

[0001] N / A.PRIORITY

[0002] The present application claims priority to and the benefit of United States Provisional Patent Application Serial No. 63 / 631197 entitled SYSTEMS AND METHODS FOR NUCLEAR PHOTOVOLTAIC CELLS, filed April 8, 2024, the disclosure of which is incorporated herein by reference in its entirety.BACKGROUND

[0003] Dry storage facilities for used nuclear fuel have been constructed on small parcels of land at several nuclear power plants that have run out of space in their spent fuel pools. The United States Nuclear Regulatory Commission (USNRC) has determined that dry storage of spent fuel at reactor sites is safe for at least 100 years, and generally considers dry storage safer than pool storage. These independent spent fuel storage installation (ISFSI) canisters hold as few as two and up to 80 spent fuel assemblies, depending on the type of assembly. With water and air removed, each canister is filled with inert gas and sealed shut.BRIEF SUMMARY

[0004] In some aspects, the techniques described herein relate to a nuclear photovoltaic (nPV) cell including: a semiconductor photovoltaic body having an incident surface and a rear surface; a microhole in the semiconductor body formed at least in the incident surface; a plurality of nanoparticles positioned in the microhole; a first charge collection layer proximate to the incident surface; and a second charge collection layer proximate to the surfaces of the semiconductor photovoltaic body and configured to receive charge from the semiconductor photovoltaic body.

[0005] In some aspects, the techniques described herein relate to a system for producing electrical power, the system including: a cask configured to contain a radioactive material and attenuate radiation incident on an interior surface of the cask; and a nuclear photovoltaic (nPV) cell positioned in the cask and including: a semiconductor photovoltaic body having an incident surface and a rear surface, a first charge collection layer proximateto the incident surface, and a second charge collection layer proximate to the rear surface of the semiconductor photovoltaic body and configured to receive charge from the semiconductor photovoltaic body.

[0006] In some aspects, the techniques described herein relate to a method of manufacturing a nuclear photovoltaic (nPV) cell, the method including: forming a semiconductor photovoltaic body with an incident surface and a rear surface on a charge collection layer; forming a plurality of microholes in the semiconductor photovoltaic body; and positioning a plurality of nanoparticles in at least one of microhole of the plurality of microholes.

[0007] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0008] Additional features and advantages will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the teachings herein. Features and advantages of the disclosure may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Features of the present disclosure will become more fully apparent from the following description and appended claims or may be learned by the practice of the disclosure as set forth hereinafter.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to describe the manner in which the above-recited and other features of the disclosure can be obtained, a more particular description will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. For better understanding, the like elements have been designated by like reference numbers throughout the various accompanying figures. While some of the drawings may be schematic or exaggerated representations of concepts, at least some of the drawings may be drawn to scale. Understanding that the drawings depict some example embodiments, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0010] FIG. 1 is a side cross-sectional view of an nPV cell, according to at least some embodiments of the present disclosure.

[0011] FIG. 2 illustrates an embodiment of an nPV cell with a first semiconductor photovoltaic body in a first layer and a second semiconductor photovoltaic body in a second layer, according to at least some embodiments of the present disclosure.

[0012] FIG. 3 is a flowchart illustrating a method of operation of some embodiments of nPV cells, according to at least some embodiments of the present disclosure.

[0013] FIG. 4 is an example of a storage cask with a liner on at least a portion of an interior surface of the storage cask, according to at least some embodiments of the present disclosure.

[0014] FIG. 5 is a side cross-sectional view of a block of waste material with a liner including at least one nPV cell around the block of waste material, according to at least some embodiments of the present disclosure.

[0015] FIG. 6 is a flowchart illustrating a method of manufacturing at least some embodiments of nPV cells, according to at least some embodiments of the present disclosure.

[0016] FIG. 7 is a side cross-sectional view of an nPV cell with dielectric layers in microholes, according to at least some embodiments of the present disclosure.DETAILED DESCRIPTION

[0017] The present disclosure relates generally to systems and methods for generating electricity. More particularly, the present disclosure relates to generating electricity from high-energy radiation (e.g., gamma radiation). For example, the high-energy radiation may be emitted during decay of radioactive waste material. In some embodiments, a nuclear photovoltaic (nPV) cell generates electricity by producing electron-hole pairs from the energy of the incident radiation. In some embodiments, the nPV receives energy from the incident radiation directly through a photovoltaic body and indirectly through secondary photons produced by a secondary material.

[0018] It should be understood that the semiconductor cells are described herein as nuclear photovoltaic cells as the photovoltaic cells receive photons of radiation and convert the energy thereof to electricity. In other examples, the semiconductor cells may be known as and / or referred to by other names, such as radiovoltaic (RV) cells and radiophotovol tai c (RPV) cells. It should be understood that the photons of radiation described herein may be of any energy level, although this disclosure will specifically refer to photons of gamma radiation from radioactive waste material.

[0019] FIG. l is a side cross-sectional view of an embodiment of an nPV cell 100 according to the present disclosure. In some embodiments, the nPV cell 100 includes a semiconductor photovoltaic body 102 that is connected to a pair of charge collection layers 104-1, 104-2. The semiconductor photovoltaic body 102 is configured to receive photons of electromagnetic radiation and generate an electrical charge therefrom. The electrical charge is collected at the charge collection layers 104-1, 104-2 to produce an electrical current. In some embodiments, at least one of the charge collection layers 104-1, 104-2 generates an electrical field in the semiconductor photovoltaic body 102 to drift the electrical charge toward the charge collection layers 104-1, 104-2.

[0020] In some embodiments, the semiconductor photovoltaic body 102 is monocrystalline silicon. In some embodiments, the semiconductor photovoltaic body 102 is poly crystalline silicon. In some embodiments, the semiconductor photovoltaic body 102 is a thin-film photovoltaic that is epitaxially grown on the charge collection layer 104. In some embodiments, the semiconductor photovoltaic body 102 includes cadmium telluride, copper indium gallium diselenide, gallium oxide, diamond, etc. In some embodiments, the semiconductor photovoltaic body 102 is a single-junction body. In some embodiments, the semiconductor photovoltaic body 102 is a multi -junction body.

[0021] Photons of electromagnetic radiation excite electrons in the semiconductor photovoltaic body 102. When an electron of the semiconductor photovoltaic body 102 is sufficiently excited, an electron-hole pair is created, and electrical charge is free to flow, for example, in a p-n junction. The electron-hole pair is collected at the charge collection layers 104-1, 104-2 (one for the electron, and one for the hole), and the electrical charge is available for other uses, such as to power other electrical devices and / or be stored for later use.

[0022] In some embodiments, the electromagnetic radiation imparting energy to the nPV cell 100 is gamma radiation. For example, gamma radiation emitted by nuclear fuel waste may penetrate into and interact with the semiconductor material of the semiconductor photovoltaic body 102 and impart energy to the atoms thereof. In some examples, the photons of gamma radiation are relatively high-energy relative to other parts of the electromagnetic spectrum and penetrate the nPV cell 100 farther than lower energy photons. In some embodiments, an nPV cell 100 according to the present disclosure captures energy from photons through direct reception of the incident radiation and through capture of lower-energy photons (e.g., lower energy than the incident radiation) that are emitted from a secondary material upon excitation by the incident radiation.

[0023] For example, the secondary material is positioned in microholes 106 in the semiconductor photovoltaic body 102. In some embodiments, the microholes 106 have nanoparticles 108 of the secondary material positioned therein. The incident radiation (e.g., photons of gamma radiation) may impart energy to the nanoparticles 108, which, in turn, emit lower-energy photons (e.g., visible light photons). In some embodiments, the lower- energy photons are incident upon the semiconductor photovoltaic body 102 through a wall(s) of the microhole 106 further imparting energy to the semiconductor photovoltaic body 102.

[0024] In some embodiments, incident radiation interacts with the atoms of the secondary material, exciting electrons of the atoms to a higher energy state. Upon relaxation of the electrons, a lower-energy photon is emitted by the secondary material. The semiconductor photovoltaic body 102 may receive energy from the lower-energy photon emitted by the secondary material. In some embodiments, the semiconductor photovoltaic body 102 receives energy and generates electrical charge from both the incident radiation (e.g., gamma radiation) interacting with the semiconductor photovoltaic body 102 directly and from the lower-energy photons (e.g., visible light photons) emitted by the secondary material after the secondary material is excited by the incident radiation.

[0025] In some embodiments, the nanoparticles include a perovskite secondary material, such as a tin halide crystalline material or lead-based crystalline material. In some embodiments, the nanoparticles are quantum dots. In some embodiments, the quantum dots are or include gold. In some embodiments, the secondary material has a greater atomic weight (Z) than the primary material of the semiconductor photovoltaic body 102.

[0026] In some embodiments, the body thickness 110 is in a range having an upper value, a lower value, or upper and lower values including any of 1 nanometer (nm), 100 nm, 250 nm, 500 nm, 1 micron, 1 millimeter (mm), 1 centimeter (cm), 2 cm, 3 cm, 4 cm, 5 cm, or greater. In some examples, the body thickness 110 is no less than 1 nm. In some examples, the body thickness 110 is no more than 5 cm. In some examples, the body thickness 110 is between 1 nm and 5 cm. In some examples, the body thickness 110 is between 1 micron and 3 cm. In some examples, the body thickness 110 is no less than 1 mm. In some examples, the body thickness 110 is no less than 1 cm. In some embodiments, the body thickness 110 is based at least partially on the energy of the incident radiation to be attenuated by the semiconductor photovoltaic body 102.

[0027] In some embodiments, a hole diameter 112 of at least one microhole 106 is at least a wavelength of the incident radiation. For example, a microhole 106 in an nPV cell 100configured to convert energy from gamma radiation may have a hole diameter 112 of at least 100 picometers (pm). In some embodiments, a hole diameter 112 of at least one microhole 106 is at least twice a wavelength of the incident radiation. For example, a microhole 106 in an nPV cell 100 configured to convert energy from gamma radiation may have a hole diameter 112 of at least 200 pm. In some embodiments, a hole diameter 112 of at least one microhole 106 is no less than 1 nm. In some embodiments, a hole diameter 112 of at least one microhole 106 is no less than 100 nm. In some embodiments, a hole diameter 112 of at least one microhole 106 is no less than 500 nm. While embodiments of microholes 106 are described in relation to a hole diameter 112, it should be understood that in some embodiments, the microholes 106 may be non-circular in cross-section. As used herein, hole diameter 112 should be understood to refer to a minimum transverse dimension of the cross-section of the microhole 106. In some examples, the hole diameter 112 refers to the minor axis of a microhole 106 with an elliptical transverse cross-section. In some examples, the hole diameter 112 refers to the shortest transverse dimension of a microhole 106 with a square transverse cross-section. In some embodiments, each microhole 106 of the plurality of microholes 106 has an equal hole diameter 112. In some embodiments, the hole diameter 112 is different between at least two of the microholes 106.

[0028] In some embodiments, at least one nanoparticle 108 of the plurality of nanoparticles has a nanoparticle size 114 no more than a wavelength of the incident radiation. For example, a nanoparticle 108 of the plurality of nanoparticles has a nanoparticle size 114 of at least 100 pm. In some embodiments, a nanoparticle 108 of the plurality of nanoparticles has a nanoparticle size 114 at least twice a wavelength of the incident radiation. For example, the nanoparticle size 114 may be at least 200 pm. In some embodiments, the nanoparticle size 114 is no less than 1 nanometer (nm). In some embodiments, the nanoparticle size 114 is in a range having an upper value, a lower value, or upper and lower values including any of 100 pm, 250 pm, 500 pm, 1 nm, or greater.

[0029] In some embodiments, the nanoparticle size 114 is no more than the hole diameter 112. In some embodiments, the nanoparticle size 114 is no more than half of the hole diameter 112. For example, four spherical nanoparticles 108 having a nanoparticle size 114 that is one half of the hole diameter 112 may fit in a single layer within the microhole 106.

[0030] In some embodiments, at least one nanoparticle 108 is substantially spherical. In some embodiments, at least one nanoparticle 108 is elliptical. In some embodiments, at least one nanoparticle 108 is cylindrical. In some embodiments, at least one nanoparticle 108 is regular polyhedral (e.g., tetrahedron, cube, dodecahedron). In some embodiments,at least one nanoparticle 108 is a regular polygonal prism (e.g., hexagonal prism, rectangular prism). In some embodiments, at least one nanoparticle 108 is an irregular shape.

[0031] In some embodiments, the nanoparticle size 114 is a spherical diameter of the nanoparticle 108. In some embodiments, the nanoparticle size 114 is a maximum length of the nanoparticle 108. For example, the nanoparticle size 114 may be a major axis of an elliptical nanoparticle 108. In other examples, the nanoparticle size 114 may be the length of an elongated structure such as nanotubes. In some embodiments, the nanoparticle size 114 is an average of a major axis and minor axis of the nanoparticle 108. In some embodiments, the nanoparticle size 114 refers to a mean and / or median nanoparticle size 114 of the plurality of nanoparticles 108. In some embodiments, the nanoparticle size 114 is substantially uniform in a microhole 106. In some embodiments, the nanoparticle size 114 is substantially uniform in the nPV cell 100. In some embodiments, the nanoparticle size 114 varies in a microhole 106. In some embodiments, the nanoparticle size 114 varies in the nPV cell 100. In some embodiments, the nanoparticle size 114 has a bimodal distribution in a microhole 106. In some embodiments, the nanoparticle size 114 has a bimodal distribution across the nPV cell 100.

[0032] In at least one example, a semiconductor photovoltaic body 102 including crystalline silicon has a body thickness 110 of no less than 1 cm attenuates at least 40% of gamma radiation incident thereon. In some embodiments, the secondary material positioned in the microholes 106 of the nPV cell 100 capture and emit energy from the gamma radiation as lower-energy photons, which are received and generate electrical charge in the semiconductor photovoltaic body 102 to increase the efficiency of the nPV cell 100 beyond only direct conversion of the gamma radiation by the silicon semiconductor photovoltaic body 102.

[0033] The microhole 106 has a microhole depth in the semiconductor photovoltaic body 102 relative to the body thickness 110. In some embodiments, the microhole 106 has a depth from the incident surface 116 (e.g., the surface oriented toward the source of the incident radiation). For example, the microhole 106 may have a depth that is the entire body thickness 110 from the incident surface 116 to a rear surface 118 of the semiconductor photovoltaic body 102 (e.g., the microhole 106 is continuous through the semiconductor photovoltaic body 102 from the incident surface 116 to the rear surface 118). In some examples, the microhole 106 has a depth from the incident surface 116 that is less than the entire body thickness 110. In some embodiments, the microhole 106 has a depth from theincident surface 116 that is less than 80% of the body thickness 110. In some embodiments, the microhole 106 has a depth from the incident surface 116 that is less than 60% of the body thickness 110. In some embodiments, the microhole 106 has a depth from the incident surface 116 that is less than 50% of the body thickness 110.

[0034] In some embodiments, the microhole 106 has a height from the rear surface 118 (e.g., the surface proximate a charge collection layer 104). In some examples, the microhole 106 has a height from the rear surface 118 that is less than the entire body thickness 110. In some embodiments, the microhole 106 has a height from the rear surface 118 that is less than 80% of the body thickness 110. In some embodiments, the microhole 106 has a height from the rear surface 118 that is less than 60% of the body thickness 110. In some embodiments, the microhole 106 has a height from the rear surface 118 that is less than 50% of the body thickness 110.

[0035] In some embodiments, the hole diameter 112 varies along the length (e.g., depth or height) of the microhole 106. In some examples, the hole diameter 112 decreases toward the rear surface 118. In some examples, the hole diameter 112 increases toward the rear surface 118. In some examples, the hole diameter 112 varies along the length linearly. For example, the microhole 106 may taper linearly from the incident surface 116 toward the rear surface 118. In some examples, the hole diameter 112 varies along the length non- linearly. For example, the microhole 106 may taper exponentially from the incident surface 116 toward the rear surface 118 such that the hole diameter 112 decreases more rapidly proximate to the rear surface 118 than proximate to the incident surface. In other examples, the microhole 106 tapers non-linearly with a more rapid decrease in hole diameter 112 proximate to the incident surface 116 than proximate to the rear surface 118.

[0036] In some embodiments, the body of the nPV cell includes a plurality of semiconductor materials. FIG. 2 illustrates an embodiment of an nPV cell 200 with a first semiconductor photovoltaic body 202-1 in a first layer and a second semiconductor photovoltaic body 202-2 in a second layer where the second layer is proximate to an incident surface 216 of the nPV cell 200 and the first semiconductor photovoltaic body 202-1 is proximate to a rear surface 218. In some embodiments, a first pair of charge collection layers 204-1, 204-2 receives charge from the first semiconductor photovoltaic body 202-1, and a second pair of charge collection layers 204-3, 204-4 receives charge from the second semiconductor photovoltaic body 202-2. It should be understood that some embodiments of nPV cells 200 according to the present disclosure have more than two such layers of semiconductor photovoltaic body.

[0037] In some embodiments, the nPV cell 200 has a body thickness 210 in a range having an upper value, a lower value, or upper and lower values including any of 1 nm, 100 nm, 250 nm, 500 nm, 1 micron, 1 mm, 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, or greater. In some examples, the body thickness 210 is no less than 1 nm. In some examples, the body thickness 210 is no more than 5 cm. In some examples, the body thickness 210 is between 1 nm and 5 cm. In some examples, the body thickness 210 is between 1 micron and 3 cm. In some examples, the body thickness 210 is no less than 1 mm. In some examples, the body thickness 210 is no less than 1 cm.

[0038] The body thickness 210 of a multi-layer nPV 200 includes at least a first body layer thickness 220-1 and a second body layer thickness 220-2. In some embodiments, the first body layer thickness 220-1 and second body layer thickness 220-2 are the same. In some embodiments, the first body layer thickness 220-1 and second body layer thickness 220-2 are different. In some embodiments, at least one of the first body layer thickness 220-1 and second body layer thickness 220-2 is in a range having an upper value, a lower value, or upper and lower values including any of 1 nm, 100 nm, 250 nm, 500 nm, 1 micron, 250 microns, 500 microns, 1 mm, 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, or greater. In some examples, at least one of the first body layer thickness 220-1 and second body layer thickness 220-2 is no less than 1 nm. In some examples, at least one of the first body layer thickness 220-1 and second body layer thickness 220-2 is no more than 5 cm. In some examples, at least one of the first body layer thickness 220-1 and second body layer thickness 220-2 is between 1 nm and 5 cm. In some examples, at least one of the first body layer thickness 220-1 and second body layer thickness 220-2 is between 1 micron and 3 cm. In some examples, at least one of the first body layer thickness 220-1 and second body layer thickness 220-2 is no less than 1 mm.

[0039] In some embodiments, at least one of the first semiconductor photovoltaic body 202-1 in a first layer and a second semiconductor photovoltaic body 202-2 in a second layer includes microholes 206-1, 206-2 with nanoparticles 208-1, 208-2 positioned therein as described in relation to FIG. 1. In some embodiments, at least one of the first microholes 206-1 of the first semiconductor photovoltaic body 202-1 is axially aligned with at least one of the second microholes 206-2 of the second semiconductor photovoltaic body 202-2. In some embodiments, all of the first microholes 206-1 of the first semiconductor photovoltaic body 202-1 are axially aligned with the second microholes 206-2 of the second semiconductor photovoltaic body 202-2.

[0040] In some embodiments, at least one of the first microholes 206-1 of the first semiconductor photovoltaic body 202-1 has a first hole diameter 212-1 that is the same as a second hole diameter 212-2 of at least one of the second microholes 206-2 of the second semiconductor photovoltaic body 202-2. In some embodiments, all of the first microholes 206-1 of the first semiconductor photovoltaic body 202-1 have a first hole diameter 212-1 that is the same as a second hole diameter 212-2 of at least one of the second microholes 206-2 of the second semiconductor photovoltaic body 202-2.

[0041] In some embodiments, at least one of the first microholes 206-1 of the first semiconductor photovoltaic body 202-1 has a first hole diameter 212-1 that is different from a second hole diameter 212-2 of at least one of the second microholes 206-2 of the second semiconductor photovoltaic body 202-2. For example, the first hole diameter 212- 1 may be greater than the second hole diameter 212-2. In some examples, the first hole diameter 212-1 is less than the second hole diameter 212-2.

[0042] In some embodiments, at least one of the first nanoparticles 208-1 of the first semiconductor photovoltaic body 202-1 has a first nanoparticle size that is the same as a second nanoparticle size of at least one of the second nanoparticles 208-2 of the second semiconductor photovoltaic body 202-2. In some embodiments, all of the first nanoparticles 208-1 have a first nanoparticle size that is the same as a second nanoparticle size of at least one of the second nanoparticles 208-2 of the second semiconductor photovoltaic body 202- 2.

[0043] In some embodiments, at least one of the first nanoparticles 208-1 of the first semiconductor photovoltaic body 202-1 has a first nanoparticle size that is different from a second nanoparticle size of at least one of the second nanoparticles 208-2 of the second semiconductor photovoltaic body 202-2. For example, the first nanoparticle size may be greater than the second nanoparticle size. In some examples, the first nanoparticle size is less than the second nanoparticle size.

[0044] The first nanoparticles 208-1 and the second nanoparticles 208-2 may be or include the same secondary material. In some embodiments, the first nanoparticles 208-1 and the second nanoparticles 208-2 are or include different secondary materials that are relatively more efficient at different energies of incident radiation. For example, different secondary materials may allow some embodiments of a multi-layer nPV cell 200 to convert incident radiation to electrical charge across a broader spectrum of incident radiation energies.

[0045] In some embodiments, an nPV cell 200 includes at least one scattering layer 222. In some embodiments, the scattering layer 222 scatters at least a portion of the incidentradiation. In some embodiments, a scattering layer 222 is proximate the incident surface 216 of the nPV cell 200. In some embodiments, a scattering layer 222 is located between the first semiconductor photovoltaic body 202-1 and the second semiconductor photovoltaic body 202-2. In some embodiments, an nPV cell 200 includes a plurality of scattering layers 222. Scattering the incident radiation, in some embodiments, increases a path length within the nPV cell 200 to increase the likelihood of conversion to electrical charge. Scattering the incident radiation, in some embodiments, lowers an energy of the incident radiation photons within the nPV cell 200 to increase the likelihood of conversion to electrical charge. In some examples, the scattering layer is or includes aluminum. In some embodiments, the scattering materials are homogeneous or composite assemblies of high Z materials, such as titanium carbide, tungsten, gadolinium, europium, etc.

[0046] In some embodiments, the thickness and / or layers of the scattering layer 222 are selected for deposition based on the nPV materials and leakage radiation spectra with a nominal 600 keV to 900 keV incident fluence. For example, the resulting fluence may be a gamma fluence from waste nuclear material.

[0047] As described herein, some embodiments of nPV cells according to the present disclosure convert energy from at least two different photon energies. FIG. 3 is a flowchart illustrating an embodiment of a method 324 of operation of some embodiments of nPV cells. In some embodiments, the method 324 includes receiving a first incident radiation photon with a semiconductor photovoltaic body of the nPV at 326 and converting energy from the first incident radiation photon to electrical charge with the semiconductor photovoltaic body at 328, such as described in relation to FIG. 1 and FIG. 2.

[0048] In some embodiments, the method 324 further includes receiving a second incident radiation photon with a secondary material of the nPV at 330 and converting energy from the second incident radiation photon to a secondary photon having less energy than the second incident radiation photon at 332. The method 324, in some embodiments, includes converting energy from the secondary photon to electrical charge with the semiconductor photovoltaic body at 334, such as described in relation to FIG. 1 and FIG. 2.

[0049] Embodiments of nPV cells according to the present disclosure may be used in nuclear waste storage systems to generate electrical current from the radioactive decay of the waste material. FIG. 4 is an example of a storage cask 436 with a liner 438 on at least a portion of an interior surface of the storage cask 436. The liner 438 includes an nPV cell 400 according to any embodiment(s) described herein. In some embodiments, the cask 436is configured to attenuate at least 95% of radiation incident on the interior surface of the cask 436 from the radioactive waste material 440.

[0050] In some embodiments, the waste material 440 produces an incident radiation 442 through the radioactive decay of the waste material 440. The incident radiation 442 interacts with the nPV cell(s) 400 to generate electrical power, which can be transmitted out of the storage cask 436 by one or more electrical conduits 444.

[0051] In some embodiments, the liner 438 and / or nPV cell(s) 400 completely surround the waste material 440 on an interior surface of the storage cask 436. In some embodiments, the liner 438 and / or nPV cell(s) 400 surround the waste material 440 on lateral sides of the waste material 440, such as on the sidewalls of the interior surface of a storage cask 436.

[0052] In some embodiments, the waste material 440 includes a plurality of waste material blocks. FIG. 5 is a side cross-sectional view of an embodiment of a block of waste material 540 with a liner 538 including at least one nPV cell 500 around the block of waste material 540. In some embodiments, each block of waste material 540 in a cask is individually encased in a liner 538 including an nPV cell 500. Each block of waste material 540 and liner 538 has one or more electrical conduit(s) 544 that carry the electrical power from the block of waste material 540. In some embodiments, a plurality of blocks of waste material 540 and liners 538 are connected in series, parallel, or combinations thereof to collect electrical power for a single conduit out of the storage cask (such as that described in relation to FIG. 4.

[0053] While embodiments of nPV cells are described in relation to gamma radiation produced during the radioactive decay of nuclear waste material, nPV cells according to the present disclosure may be used to convert other high-energy radiation to electricity, such as cosmic radiation. In some examples, one or more nPV cells may be positioned on an exterior surface or deployable panel of a satellite, spacecraft, or other extraterrestrial device or system.

[0054] An nPV cell according to at least some embodiments of the present disclosure may be manufactured in a scalable manner. FIG. 6 is a flowchart illustrating an embodiment of a method 646 of manufacturing at least some embodiments of nPV cells according to the present disclosure. In some embodiments, the method 646 includes forming a semiconductor photovoltaic body on a charge collection layer at 648, such as any embodiment of a semiconductor photovoltaic body described herein. In some embodiments, the semiconductor photovoltaic body has a body thickness no less than 1 cm. In some embodiments, the semiconductor photovoltaic body includes a plurality ofsemiconductor photovoltaic body layers, such as described in relation to FIG. 2. In some embodiments, the semiconductor photovoltaic body is monocrystalline. In some embodiments, the semiconductor photovoltaic body is polycrystalline. In some embodiments, the semiconductor photovoltaic body is amorphous. In some embodiments, forming the semiconductor photovoltaic body on the charge collection layer includes depositing the body material on the charge collection layer.

[0055] The method 646 further includes forming a plurality of microholes in the semiconductor photovoltaic body at 650. The microholes may have any hole diameter, transverse cross-sectional shape, depth, height, or profile described in relation to FIG. 1 or FIG. 2. In some embodiments, forming the plurality of microholes includes ablating at least a portion of the semiconductor photovoltaic body with a laser. For example, during testing, a single pulsed laser has demonstrated the capability to produce 10,000 perforated microholes over an area of 20 mm x 10 mm in a silicon photovoltaic body in less than a minute. In some embodiments, the laser ablation removes material up to no less than 1 cm deep in the semiconductor photovoltaic body. In some embodiments, forming the microholes further includes depositing a dielectric material or layer of material on an interior surface of the microholes. For example, the dielectric material or layer may limit and / or prevent electrical conduction across the microhole, limiting current leakage.

[0056] In other embodiments, forming the plurality of microholes is simultaneous with the forming of the semiconductor photovoltaic body at 648. For example, the plurality of microholes may be formed in the semiconductor photovoltaic body during deposition of the body material with no body material removed during forming of the plurality of microholes. In some embodiments, forming the plurality of microholes in the semiconductor photovoltaic body includes both forming at least part of the plurality of microholes during forming of the semiconductor photovoltaic body and removing a portion of the semiconductor photovoltaic body afterward to complete formation of the plurality of microholes.

[0057] The method 646 further includes positioning a plurality of nanoparticles in at least one microhole of the plurality of microholes at 652. In some embodiments, the nanoparticles are semiconductor nanoparticles. In some embodiments, the nanoparticles are semiconductor quantum dots. In some embodiments, the nanoparticles have a nanoparticle size relative to the at least one microhole as described in relation to FIG. 1.

[0058] FIG. 7 is a side cross-sectional view of another embodiment of a nPV cell 700 with a semiconductor photovoltaic body 702 that is connected to a pair of charge collectionlayers 704-1, 704-2. Similar to the structures described in relation to FIG. 1 and FIG. 2, the semiconductor photovoltaic body 702 is configured to receive photons of electromagnetic radiation and generate an electrical charge therefrom. The electrical charge is collected at the charge collection layers 704-1, 704-2 to produce an electrical current. In some embodiments, at least one of the charge collection layers 704-1, 704-2 generates an electrical field in the semiconductor photovoltaic body 702 to drift the electrical charge toward the charge collection layers 704-1, 704-2.

[0059] In some embodiments, the semiconductor photovoltaic body 702 is monocrystalline silicon. In some embodiments, the semiconductor photovoltaic body 702 is polycrystalline silicon. In some embodiments, the semiconductor photovoltaic body 702 is a thin-film photovoltaic that is epitaxially grown on the charge collection layer 704. In some embodiments, the semiconductor photovoltaic body 702 includes cadmium telluride, copper indium gallium diselenide, gallium oxide, diamond, etc. In some embodiments, the semiconductor photovoltaic body 702 is a single-junction body. In some embodiments, the semiconductor photovoltaic body 702 is a multi -junction body.

[0060] As described herein, photons of electromagnetic radiation excite electrons in the semiconductor photovoltaic body 702. When an electron of the semiconductor photovoltaic body 702 is sufficiently excited, an electron-hole pair is created, and electrical charge is free to flow, for example, in a p-n junction. The electron-hole pair is collected at the charge collection layers 704-1, 704-2 (one for the electron, and one for the hole), and the electrical charge is available for other uses, such as to power other electrical devices and / or be stored for later use.

[0061] In some embodiments, the electromagnetic radiation imparting energy to the nPV cell 700 is gamma radiation. For example, gamma radiation emitted by nuclear fuel waste may penetrate into and interact with the semiconductor material of the semiconductor photovoltaic body 702 and impart energy to the atoms thereof. In some examples, the photons of gamma radiation are relatively high-energy relative to other parts of the electromagnetic spectrum and penetrate the nPV cell 700 farther than lower energy photons. In some embodiments, an nPV cell 700 according to the present disclosure captures energy from photons through direct reception of the incident radiation and through capture of lower-energy photons (e.g., lower energy than the incident radiation) that are emitted from a secondary material upon excitation by the incident radiation.

[0062] For example, the secondary material is positioned in microholes 706 in the semiconductor photovoltaic body 702. In some embodiments, the microholes 706 havenanoparticles 708 of the secondary material positioned therein. The incident radiation (e.g., photons of gamma radiation) may impart energy to the nanoparticles 108, which, in turn, emit lower-energy photons (e.g., visible light photons). In some embodiments, the lower- energy photons are incident upon the semiconductor photovoltaic body 702 through a wall(s) of the microhole 706 further imparting energy to the semiconductor photovoltaic body 702.

[0063] As described herein, the microholes 706 may vary in a hole diameter 712 along a length thereof. In some embodiments, a microhole 706 tapers from an incident surface 716 toward a rear surface 718. For example, the microhole 706 may have a greater hole diameter 712 proximate to the incident surface 716 than proximate to the rear surface 718. As described herein, the rate of change of the hole diameter 712 may be linear or non-linear. The rate of change of the hole diameter 712 may be continuous or non-continuous. In some embodiments, the microhole 706 has a greater hole diameter 712 proximate to the rear surface 718 than proximate to the incident surface 716.

[0064] In some embodiments, a microhole 706 has a dielectric layer 754 lining at least portion of an interior surface of the microhole 706. As described herein, the microhole 706 may have a circular cross-sectional shape or non-circular cross-sectional shape. The dielectric layer 754 may be located on the entire interior surface of the microhole 706 or less than the entire interior surface. In some embodiments, the dielectric layer 754 is located on an interior lateral wall of the microhole 706. In some embodiments, the dielectric layer 754 is located on bottom surface of the microhole 706. For example, the microhole 706 may have a length that is less than a full thickness 710 of the semiconductor body 702, where the microhole 706 terminates at a bottom surface within the semiconductor body 702. In some examples, the microhole 706 may taper to a point without a defined bottom surface within the semiconductor body 702, and the dielectric layer 754 may be located on the interior lateral wall of the microhole 706 to substantially cover the entire interior surface of the microhole 706.INDUSTRIAL APPLICABILITY

[0065] The present disclosure relates generally to systems and methods for generating electricity. More particularly, the present disclosure relates to generating electricity from high-energy radiation (e.g., gamma radiation). For example, the high-energy radiation may be emitted during decay of radioactive waste material. In some embodiments, a nuclear photovoltaic (nPV) cell generates electricity by producing electron-hole pairs from theenergy of the incident radiation. In some embodiments, the nPV receives energy from the incident radiation directly through a photovoltaic body and indirectly through secondary photons produced by a secondary material.

[0066] It should be understood that the semiconductor cells are described herein as nuclear photovoltaic cells as the photovoltaic cells receive photons of radiation and convert the energy thereof to electricity. In other examples, the semiconductor cells may be known as and / or referred to by other names, such as radiovoltaic (RV) cells and radiophotovoltaic (RPV) cells. It should be understood that the photons of radiation described herein may be of any energy level, although this disclosure will specifically refer to photons of gamma radiation from radioactive waste material.

[0067] In some embodiments, the nPV cell includes a semiconductor photovoltaic body that is connected to a pair of charge collection layers. The semiconductor photovoltaic body is configured to receive photons of electromagnetic radiation and generate an electrical charge therefrom. The electrical charge is collected at the charge collection layers to produce an electrical current. In some embodiments, at least one of the charge collection layers generates an electrical field in the semiconductor photovoltaic body to drift the electrical charge toward the charge collection layers.

[0068] In some embodiments, the semiconductor photovoltaic body is monocrystalline silicon. In some embodiments, the semiconductor photovoltaic body is polycrystalline silicon. In some embodiments, the semiconductor photovoltaic body is a thin-film photovoltaic that is epitaxially grown on the charge collection layer. In some embodiments, the semiconductor photovoltaic body includes cadmium telluride, copper indium gallium diselenide, gallium oxide, diamond, etc. In some embodiments, the semiconductor photovoltaic body is a single-junction body. In some embodiments, the semiconductor photovoltaic body is a multi -junction body.

[0069] Photons of electromagnetic radiation excite electrons in the semiconductor photovoltaic body. When an electron of the semiconductor photovoltaic body is sufficiently excited, an electron-hole pair is created, and electrical charge is free to flow, for example, in a p-n junction. The electron-hole pair is collected at the charge collection layers, and the electrical charge is available for other uses, such as to power other electrical devices and / or be stored for later use.

[0070] In some embodiments, the electromagnetic radiation imparting energy to the nPV cell is gamma radiation. For example, gamma radiation emitted by nuclear fuel waste may penetrate into and interact with the semiconductor material of the semiconductorphotovoltaic body and impart energy to the atoms thereof. In some examples, the photons of gamma radiation are relatively high-energy relative to other parts of the electromagnetic spectrum and penetrate the nPV cell farther than lower energy photons. In some embodiments, an nPV cell according to the present disclosure captures energy from photons through direct reception of the incident radiation and through capture of lower-energy photons (e.g., lower energy than the incident radiation) that are emitted from a secondary material upon excitation by the incident radiation.

[0071] For example, the secondary material is positioned in microholes in the semiconductor photovoltaic body. In some embodiments, the microholes have nanoparticles of the secondary material positioned therein. The incident radiation (e.g., photons of gamma radiation) may impart energy to the nanoparticles, which, in turn, emit lower-energy photons (e.g., visible light photons). In some embodiments, the lower-energy photons are incident upon the semiconductor photovoltaic body through a wall(s) of the microhole further imparting energy to the semiconductor photovoltaic body.

[0072] In some embodiments, incident radiation interacts with the atoms of the secondary material, exciting electrons of the atoms to a higher energy state. Upon relaxation of the electrons, a lower-energy photon is emitted by the secondary material. The semiconductor photovoltaic body may receive energy from the lower-energy photon emitted by the secondary material. In some embodiments, the semiconductor photovoltaic body receives energy and generates electrical charge from both the incident radiation (e.g., gamma radiation) interacting with the semiconductor photovoltaic body directly and from the lower-energy photons (e.g., visible light photons) emitted by the secondary material after the secondary material is excited by the incident radiation.

[0073] In some embodiments, the nanoparticles include a perovskite secondary material, such as a tin halide crystalline material or lead-based crystalline material. In some embodiments, the nanoparticles are quantum dots. In some embodiments, the quantum dots are or include gold. In some embodiments, the secondary material has a greater atomic weight (Z) than the primary material of the semiconductor photovoltaic body.

[0074] In some embodiments, the body thickness is in a range having an upper value, a lower value, or upper and lower values including any of 1 nanometer (nm), 100 nm, 250 nm, 500 nm, 1 micron, 1 millimeter (mm), 1 centimeter (cm), 2 cm, 3 cm, 4 cm, 5 cm, or greater. In some examples, the body thickness is no less than 1 nm. In some examples, the body thickness is no more than 5 cm. In some examples, the body thickness is between 1 nm and 5 cm. In some examples, the body thickness is between 1 micron and 3 cm. In someexamples, the body thickness 110 is no less than 1 mm. In some examples, the body thickness 110 is no less than 1 cm. In some embodiments, the body thickness is based at least partially on the energy of the incident radiation to be attenuated by the semiconductor photovoltaic body.

[0075] In some embodiments, a hole diameter of at least one microhole is at least a wavelength of the incident radiation. For example, a microhole in an nPV cell configured to convert energy from gamma radiation may have a hole diameter of at least 100 picometers (pm). In some embodiments, a hole diameter of at least one microhole is at least twice a wavelength of the incident radiation. For example, a microhole in an nPV cell configured to convert energy from gamma radiation may have a hole diameter of at least 200 pm. In some embodiments, a hole diameter of at least one microhole is no less than 1 nm. In some embodiments, a hole diameter 112 of at least one microhole 106 is no less than 100 nm. In some embodiments, a hole diameter 112 of at least one microhole 106 is no less than 500 nm. While embodiments of microholes are described in relation to a hole diameter, it should be understood that in some embodiments, the microholes may be non-circular in cross-section. As used herein, hole diameter should be understood to refer to a minimum transverse dimension of the cross-section of the microhole. In some examples, the hole diameter refers to the minor axis of a microhole with an elliptical transverse cross-section. In some examples, the hole diameter refers to the shortest transverse dimension of a microhole with a square transverse cross-section. In some embodiments, each microhole of the plurality of microholes has an equal hole diameter. In some embodiments, the hole diameter is different between at least two of the microholes.

[0076] In some embodiments, at least one nanoparticle of the plurality of nanoparticles has a nanoparticle size no more than a wavelength of the incident radiation. For example, a nanoparticle of the plurality of nanoparticles has a nanoparticle size of at least 100 pm. In some embodiments, a nanoparticle of the plurality of nanoparticles has a nanoparticle size at least twice a wavelength of the incident radiation. For example, the nanoparticle size may be at least 200 pm. In some embodiments, the nanoparticle size is no less than 1 nanometer (nm). In some embodiments, the nanoparticle size is in a range having an upper value, a lower value, or upper and lower values including any of 100 pm, 250 pm, 500 pm, 1 nm, or greater.

[0077] In some embodiments, the nanoparticle size is no more than the hole diameter. In some embodiments, the nanoparticle size is no more than half of the hole diameter. Forexample, four spherical nanoparticles having a nanoparticle size that is one half of the hole diameter may fit in a single layer within the microhole.

[0078] In some embodiments, at least one nanoparticle is substantially spherical. In some embodiments, at least one nanoparticle is elliptical. In some embodiments, at least one nanoparticle is cylindrical. In some embodiments, at least one nanoparticle is regular polyhedral (e.g., tetrahedron, cube, dodecahedron). In some embodiments, at least one nanoparticle is a regular polygonal prism (e.g., hexagonal prism, rectangular prism). In some embodiments, at least one nanoparticle is an irregular shape.

[0079] In some embodiments, the nanoparticle size is a spherical diameter of the nanoparticle. In some embodiments, the nanoparticle size is a maximum length of the nanoparticle. For example, the nanoparticle size may be a major axis of an elliptical nanoparticle. In other examples, the nanoparticle size may be the length of an elongated structure such as nanotubes. In some embodiments, the nanoparticle size is an average of a major axis and minor axis of the nanoparticle. In some embodiments, the nanoparticle size refers to a mean and / or median nanoparticle size of the plurality of nanoparticles. In some embodiments, the nanoparticle size is substantially uniform in a microhole. In some embodiments, the nanoparticle size is substantially uniform in the nPV cell. In some embodiments, the nanoparticle size varies in a microhole. In some embodiments, the nanoparticle size varies in the nPV cell. In some embodiments, the nanoparticle size has a bimodal distribution in a microhole. In some embodiments, the nanoparticle size has a bimodal distribution across the nPV cell.

[0080] In at least one example, a semiconductor photovoltaic body including crystalline silicon has a body thickness of no less than 1 cm attenuates at least 40% of gamma radiation incident thereon. In some embodiments, the secondary material positioned in the microholes of the nPV cell capture and emit energy from the gamma radiation as lower- energy photons, which are received and generate electrical charge in the semiconductor photovoltaic body to increase the efficiency of the nPV cell beyond only direct conversion of the gamma radiation by the silicon semiconductor photovoltaic body.

[0081] The microhole has a microhole depth in the semiconductor photovoltaic body relative to the body thickness. In some embodiments, the microhole 106 has a depth from the incident surface (e.g., the surface oriented toward the source of the incident radiation). For example, the microhole may have a depth that is the entire body thickness from the incident surface to a rear surface of the semiconductor photovoltaic body (e.g., the microhole is continuous through the semiconductor photovoltaic body from the incidentsurface to the rear surface). In some examples, the microhole has a depth from the incident surface that is less than the entire body thickness. In some embodiments, the microhole has a depth from the incident surface that is less than 80% of the body thickness. In some embodiments, the microhole has a depth from the incident surface that is less than 60% of the body thickness. In some embodiments, the microhole has a depth from the incident surface that is less than 50% of the body thickness.

[0082] In some embodiments, the microhole has a height from the rear surface (e.g., the surface proximate a charge collection layer). In some examples, the microhole has a height from the rear surface that is less than the entire body thickness. In some embodiments, the microhole has a height from the rear surface that is less than 80% of the body thickness. In some embodiments, the microhole has a height from the rear surface that is less than 60% of the body thickness. In some embodiments, the microhole has a height from the rear surface that is less than 50% of the body thickness.

[0083] In some embodiments, the hole diameter varies along the length (e.g., depth or height) of the microhole. In some examples, the hole diameter decreases toward the rear surface. In some examples, the hole diameter increases toward the rear surface. In some examples, the hole diameter varies along the length linearly. For example, the microhole may taper linearly from the incident surface toward the rear surface. In some examples, the hole diameter varies along the length non-linearly. For example, the microhole may taper exponentially from the incident surface toward the rear surface such that the hole diameter decreases more rapidly proximate to the rear surface than proximate to the incident surface. In other examples, the microhole tapers non-linearly with a more rapid decrease in hole diameter proximate to the incident surface than proximate to the rear surface.

[0084] In some embodiments, the body of the nPV cell includes a plurality of semiconductor materials. For example, an nPV cell may have a first semiconductor photovoltaic body in a first layer and a second semiconductor photovoltaic body in a second layer where the second layer is proximate to an incident surface of the nPV cell, and the first semiconductor photovoltaic body is proximate to a rear surface. In some embodiments, a first pair of charge collection layers receives charge from the first semiconductor photovoltaic body, and a second pair of charge collection layers receives charge from the second semiconductor photovoltaic body. It should be understood that some embodiments of nPV cells according to the present disclosure have more than two such layers of semiconductor photovoltaic body.

[0085] In some embodiments, the nPV cell has a body thickness in a range having an upper value, a lower value, or upper and lower values including any of 1 nm, 100 nm, 250 nm, 500 nm, 1 micron, 1 mm, 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, or greater. In some examples, the body thickness is no less than 1 nm. In some examples, the body thickness is no more than 5 cm. In some examples, the body thickness is between 1 nm and 5 cm. In some examples, the body thickness is between 1 micron and 3 cm. In some examples, the body thickness is no less than 1 mm. In some examples, the body thickness is no less than 1 cm.

[0086] The body thickness of a multi-layer nPV includes at least a first body layer thickness and a second body layer thickness. In some embodiments, the first body layer thickness and second body layer thickness are the same. In some embodiments, the first body layer thickness and second body layer thickness are different. In some embodiments, at least one of the first body layer thickness and second body layer thickness is in a range having an upper value, a lower value, or upper and lower values including any of 1 nm, 100 nm, 250 nm, 500 nm, 1 micron, 250 microns, 500 microns, 1mm, 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, or greater. In some examples, at least one of the first body layer thickness and second body layer thickness is no less than 1 nm. In some examples, at least one of the first body layer thickness and second body layer thickness is no more than 5 cm. In some examples, at least one of the first body layer thickness and second body layer thickness is between 1 nm and 5 cm. In some examples, at least one of the first body layer thickness and second body layer thickness is between 1 micron and 3 cm. In some examples, at least one of the first body layer thickness and second body layer thickness is no less than 1 mm.

[0087] In some embodiments, at least one of the first semiconductor photovoltaic body in a first layer and a second semiconductor photovoltaic body in a second layer includes microholes with nanoparticles positioned therein as described herein. In some embodiments, at least one of the first microholes of the first semiconductor photovoltaic body is axially aligned with at least one of the second microholes of the second semiconductor photovoltaic body. In some embodiments, all of the first microholes of the first semiconductor photovoltaic body are axially aligned with the second microholes of the second semiconductor photovoltaic body.

[0088] In some embodiments, at least one of the first microholes of the first semiconductor photovoltaic body has a first hole diameter that is the same as a second hole diameter of at least one of the second microholes of the second semiconductor photovoltaic body. In some embodiments, all of the first microholes of the first semiconductor photovoltaic body havea first hole diameter that is the same as a second hole diameter of at least one of the second microholes of the second semiconductor photovoltaic body.

[0089] In some embodiments, at least one of the first microholes of the first semiconductor photovoltaic body has a first hole diameter that is different from a second hole diameter of at least one of the second microholes of the second semiconductor photovoltaic body. For example, the first hole diameter may be greater than the second hole diameter. In some examples, the first hole diameter is less than the second hole diameter.

[0090] In some embodiments, at least one of the first nanoparticles of the first semiconductor photovoltaic body has a first nanoparticle size that is the same as a second nanoparticle size of at least one of the second nanoparticles of the second semiconductor photovoltaic body. In some embodiments, all of the first nanoparticles have a first nanoparticle size that is the same as a second nanoparticle size of at least one of the second nanoparticles of the second semiconductor photovoltaic body.

[0091] In some embodiments, at least one of the first nanoparticles of the first semiconductor photovoltaic body has a first nanoparticle size that is different from a second nanoparticle size of at least one of the second nanoparticles of the second semiconductor photovoltaic body. For example, the first nanoparticle size may be greater than the second nanoparticle size. In some examples, the first nanoparticle size is less than the second nanoparticle size.

[0092] The first nanoparticles and the second nanoparticles may be or include the same secondary material. In some embodiments, the first nanoparticles and the second nanoparticles are or include different secondary materials that are relatively more efficient at different energies of incident radiation. For example, different secondary materials may allow some embodiments of a multi-layer nPV cell to convert incident radiation to electrical charge across a broader spectrum of incident radiation energies.

[0093] In some embodiments, an nPV cell includes at least one scattering layer. In some embodiments, the scattering layer scatters at least a portion of the incident radiation. In some embodiments, a scattering layer is proximate the incident surface of the nPV cell. In some embodiments, a scattering layer is located between the first semiconductor photovoltaic body and the second semiconductor photovoltaic body. In some embodiments, an nPV cell includes a plurality of scattering layers. Scattering the incident radiation, in some embodiments, increases a path length within the nPV cell to increase the likelihood of conversion to electrical charge. Scattering the incident radiation, in some embodiments, lowers an energy of the incident radiation photons within the nPV cell to increase thelikelihood of conversion to electrical charge. In some examples, the scattering layer is or includes aluminum, titanium carbide, tungsten, europium, and other materials, or a hybrid combination of materials.

[0094] In some embodiments, the thickness and / or layers of the scattering layer are selected for deposition based on the nPV materials and leakage radiation spectra with a nominal 600 keV to 900 keV incident fluence. For example, the resulting fluence may be a gamma fluence from waste nuclear material.

[0095] As described herein, some embodiments of nPV cells according to the present disclosure convert energy from at least two different photon energies. In some embodiments, the method includes receiving a first incident radiation photon with a semiconductor photovoltaic body of the nPV and converting energy from the first incident radiation photon to electrical charge with the semiconductor photovoltaic body, such as described herein.

[0096] In some embodiments, the method further includes receiving a second incident radiation photon with a secondary material of the nPV and converting energy from the second incident radiation photon to a secondary photon having less energy than the second incident radiation photon. The method, in some embodiments, includes converting energy from the secondary photon to electrical charge with the semiconductor photovoltaic body, such as described herein.

[0097] Embodiments of nPV cells according to the present disclosure may be used in nuclear waste storage systems to generate electrical current from the radioactive decay of the waste material. In some embodiments, a storage cask includes a liner. The liner includes an nPV cell according to any embodiment s) described herein. In some embodiments, the cask is configured to attenuate at least 95% of radiation incident on the interior surface of the cask from the radioactive waste material.

[0098] In some embodiments, the waste material produces an incident radiation through the radioactive decay of the waste material. The incident radiation interacts with the nPV cell(s) to generate electrical power, which can be transmitted out of the storage cask by one or more electrical conduits.

[0099] In some embodiments, the liner and / or nPV cell(s) completely surround the waste material on an interior surface of the storage cask. In some embodiments, the liner and / or nPV cell(s) surround the waste material on lateral sides of the waste material, such as on the sidewalls of the interior surface of a storage cask.

[0100] In some embodiments, the waste material includes a plurality of waste material blocks. In some embodiments, each block of waste material in a cask is individually encased in a liner including an nPV. Each block of waste material and liner has one or more electrical conduit(s) that carry the electrical power from the block of waste material. In some embodiments, a plurality of blocks of waste material and liners are connected in series, parallel, or combinations thereof to collect electrical power for a single conduit out of the storage cask (such as that described herein).

[0101] While embodiments of nPV cells are described in relation to gamma radiation produced during the radioactive decay of nuclear waste material, nPV cells according to the present disclosure may be used to convert other high-energy radiation to electricity, such as cosmic radiation. In some examples, one or more nPV cells may be positioned on an exterior surface or deployable panel of a satellite, spacecraft, or other extraterrestrial device or system.

[0102] An nPV cell according to at least some embodiments of the present disclosure may be manufactured in a scalable manner. In some embodiments, the method includes forming a semiconductor photovoltaic body on a charge collection layer, such as any embodiment of a semiconductor photovoltaic body described herein. In some embodiments, the semiconductor photovoltaic body has a body thickness no less than 1 cm. In some embodiments, the semiconductor photovoltaic body includes a plurality of semiconductor photovoltaic body layers, such as described herein. In some embodiments, the semiconductor photovoltaic body is monocrystalline. In some embodiments, the semiconductor photovoltaic body is polycrystalline. In some embodiments, the semiconductor photovoltaic body is amorphous. In some embodiments, forming the semiconductor photovoltaic body on the charge collection layer includes depositing the body material on the charge collection layer.

[0103] The method further includes forming a plurality of microholes in the semiconductor photovoltaic body. The microholes may have any hole diameter, transverse cross-sectional shape, depth, height, or profile described herein. In some embodiments, forming the plurality of microholes includes ablating at least a portion of the semiconductor photovoltaic body with a laser. For example, during testing, a single pulsed laser has demonstrated the capability to produce 10,000 perforated microholes over an area of 20 mm x 10 mm in a silicon photovoltaic body in less than a minute. In some embodiments, the laser ablation removes material up to no less than 1 cm deep in the semiconductor photovoltaic body. In some embodiments, forming the microholes further includesdepositing a dielectric material or layer of material on an interior surface of the microholes. For example, the dielectric material or layer may limit and / or prevent electrical conduction across the microhole, limiting current leakage.

[0104] In other embodiments, forming the plurality of microholes is simultaneous with the forming of the semiconductor photovoltaic body. For example, the plurality of microholes may be formed in the semiconductor photovoltaic body during deposition of the body material with no body material removed during forming of the plurality of microholes. In some embodiments, forming the plurality of microholes in the semiconductor photovoltaic body includes both forming at least part of the plurality of microholes during forming of the semiconductor photovoltaic body and removing a portion of the semiconductor photovoltaic body afterward to complete formation of the plurality of microholes.

[0105] The method further includes positioning a plurality of nanoparticles in at least one microhole of the plurality of microholes. In some embodiments, the nanoparticles are semiconductor nanoparticles. In some embodiments, the nanoparticles are semiconductor quantum dots. In some embodiments, the nanoparticles have a nanoparticle size relative to the at least one microhole as described herein.

[0106] As described herein, the microholes may vary in a hole diameter along a length thereof. In some embodiments, a microhole tapers from an incident surface toward a rear surface. For example, the microhole may have a greater hole diameter proximate to the incident surface than proximate to the rear surface. As described herein, the rate of change of the hole diameter may be linear or non-linear. The rate of change of the hole diameter may be continuous or non-continuous. In some embodiments, the microhole has a greater hole diameter proximate to the rear surface than proximate to the incident surface.

[0107] In some embodiments, a microhole has a dielectric layer lining at least portion of an interior surface of the microhole. As described herein, the microhole may have a circular cross-sectional shape or non-circular cross-sectional shape. The dielectric layer may be located on the entire interior surface of the microhole or less than the entire interior surface. In some embodiments, the dielectric layer is located on an interior lateral wall of the microhole. In some embodiments, the dielectric layer is located on bottom surface of the microhole. For example, the microhole may have a length that is less than a full thickness of the semiconductor body, where the microhole terminates at a bottom surface within the semiconductor body. In some examples, the microhole may taper to a point without a defined bottom surface within the semiconductor body, and the dielectriclayer may be located on the interior lateral wall of the microhole to substantially cover the entire interior surface of the microhole.

[0108] The present disclosure relates to systems and methods for producing electricity according to at least the examples provided in the sections below:

[0109] Clause 1. A nuclear photovoltaic (nPV) cell comprising: a semiconductor photovoltaic body having an incident surface and a rear surface,; a microhole in the semiconductor body formed at least in the incident surface; a plurality of nanoparticles positioned in the microhole; a first charge collection layer proximate to the incident surface; and a second charge collection layer proximate to the rear surface of the semiconductor photovoltaic body and configured to receive charge from the semiconductor photovoltaic body.

[0110] Clause 2. The nPV cell of any preceding clause, wherein the microhole has a hole diameter of no more than 1 nanometer.

[0111] Clause 3. The nPV cell of any preceding clause, wherein the plurality of nanoparticles includes perovskite.

[0112] Clause 4. The nPV cell of any preceding clause, further comprising a scattering layer proximate to the incident surface of the semiconductor photovoltaic body.

[0113] Clause 5. The nPV cell of any preceding clause, wherein the semiconductor photovoltaic body includes a first semiconductor photovoltaic body layer, and the nPV cell further includes a second semiconductor photovoltaic body layer proximate to the incident surface.

[0114] Clause 6. The nPV cell of clause 5, wherein the first semiconductor photovoltaic body layer and the second semiconductor photovoltaic body layer include different materials.

[0115] Clause 7. The nPV cell of clause 1, wherein the microhole is continuous through the semiconductor photovoltaic body between the incident surface and the rear surface.

[0116] Clause 8. The nPV cell of any preceding clause, wherein at least one nanoparticle in the microhole has a nanoparticle size less than one half a hole diameter of the microhole.

[0117] Clause 9. The nPV cell of any preceding clause, wherein at least one nanoparticle has a nanoparticle size less than 100 picometers.

[0118] Clause 10. The nPV cell of any preceding clause, wherein the microhole has a hole diameter less than 1 nanometer.

[0119] Clause 11. The nPV cell of any preceding clause, wherein the microhole has a hole diameter that varies along an axial length of the microhole.

[0120] Clause 12. A system for producing electrical power, the system comprising: a cask configured to contain a radioactive material and attenuate gamma radiation incident on an interior surface of the cask; and a nuclear photovoltaic (nPV) cell positioned in the cask and including: a semiconductor photovoltaic body having an incident surface and a rear surface, , a first charge collection layer proximate to the incident surface, and a second charge collection layer proximate to the rear surface of the semiconductor photovoltaic body and configured to receive charge from the semiconductor photovoltaic body.

[0121] Clause 13. The system of clause 12, wherein the nPV cell is positioned in the cask on at least a portion of the interior surface of the cask.

[0122] Clause 14. The system of clause 12 or 13, wherein the nPV cell is positioned on a lateral sidewall of the cask around the radioactive material.

[0123] Clause 15. The system of any of clauses 12 through 14, wherein the nPV cell is configured to at least partially enclose a block of the radioactive material.

[0124] Clause 16. The system of any of clauses 12 through 15, wherein the nPV cell further includes: a microhole in the semiconductor photovoltaic body formed at least in the incident surface, and a plurality of nanoparticles positioned in the microhole.

[0125] Clause 17. A method of manufacturing a nuclear photovoltaic (nPV) cell, the method comprising: forming a semiconductor photovoltaic body with a body thickness between an incident surface and a rear surface on a charge collection layer; forming a plurality of microholes in the semiconductor photovoltaic body; and positioning a plurality of nanoparticles in at least one of microhole of the plurality of microholes.

[0126] Clause 18. The method of clause 17, wherein forming the plurality of microholes includes laser ablating at least one of microhole of the plurality of microholes in the semiconductor photovoltaic body.

[0127] Clause 19. The method of clause 17 or 18, wherein at least one of microhole of the plurality of microholes is continuous through the semiconductor photovoltaic body between the incident surface and the rear surface.

[0128] Clause 20. The method of any of clauses 17 through 19, wherein forming the plurality of microholes includes forming at least part of the plurality of microholes during forming of the semiconductor photovoltaic body.

[0129] Clause 21. The nPV cell of any of clauses 1 through 16, further comprising a dielectric layer on an interior surface of the microhole.

[0130] Clause 22. The method of any of clauses 17 through 20, further comprising depositing a dielectric material on an interior surface of the microhole.

[0131] The articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements in the preceding descriptions. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. For example, any element described in relation to an embodiment herein may be combinable with any element of any other embodiment described herein. Numbers, percentages, ratios, or other values stated herein are intended to include that value, and also other values that are “about” or “approximately” the stated value, as would be appreciated by one of ordinary skill in the art encompassed by embodiments of the present disclosure. A stated value should therefore be interpreted broadly enough to encompass values that are at least close enough to the stated value to perform a desired function or achieve a desired result. The stated values include at least the variation to be expected in a suitable manufacturing or production process, and may include values that are within 5%, within 1%, within 0.1%, or within 0.01% of a stated value.

[0132] A person having ordinary skill in the art should realize in view of the present disclosure that equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and alterations may be made to embodiments disclosed herein without departing from the spirit and scope of the present disclosure. Equivalent constructions, including functional “means-plus-function” clauses are intended to cover the structures described herein as performing the recited function, including both structural equivalents that operate in the same manner, and equivalent structures that provide the same function. It is the express intention of the applicant not to invoke means-plus-function or other functional claiming for any claim except for those in which the words ‘means for’ appear together with an associated function. Each addition, deletion, and modification to the embodiments that falls within the meaning and scope of the claims is to be embraced by the claims.

[0133] It should be understood that any directions or reference frames in the preceding description are merely relative directions or movements. For example, any references to “front” and “back” or “top” and “bottom” or “left” and “right” are merely descriptive of the relative position or movement of the related elements.

[0134] The present disclosure may be embodied in other specific forms without departing from its spirit or characteristics. The described embodiments are to be considered as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description. Changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

CLAIMSWhat is claimed is:

1. A nuclear photovoltaic (nPV) cell comprising: a semiconductor photovoltaic body having an incident surface and a rear surface; a microhole in the semiconductor body formed at least in the incident surface; a plurality of nanoparticles positioned in the microhole; a first charge collection layer proximate to the incident surface; and a second charge collection layer proximate to the rear surface of the semiconductor photovoltaic body and configured to receive charge from the semiconductor photovoltaic body.

2. The nPV cell of claim 1, wherein the microhole has a hole diameter of no more than 1 nanometer.

3. The nPV cell of claim 1, wherein the plurality of nanoparticles includes perovskite.

4. The nPV cell of claim 1, further comprising a scattering layer proximate to the incident surface of the semiconductor photovoltaic body.

5. The nPV cell of claim 1, wherein the semiconductor photovoltaic body includes a first semiconductor photovoltaic body layer, and the nPV cell further includes a second semiconductor photovoltaic body layer proximate to the incident surface.

6. The nPV cell of claim 5, wherein the first semiconductor photovoltaic body layer and the second semiconductor photovoltaic body layer include different materials.

7. The nPV cell of claim 1, wherein the microhole is continuous through the semiconductor photovoltaic body between the incident surface and the rear surface.

8. The nPV cell of claim 1, wherein at least one nanoparticle in the microhole has a nanoparticle size less than one half a hole diameter of the microhole.

9. The nPV cell of claim 1, wherein at least one nanoparticle has a nanoparticle size less than 100 picometers.

10. The nPV cell of claim 1, further comprising a dielectric layer on an interior surface of the microhole.

11. The nP V cell of claim 1 , wherein the microhole has a hole diameter that varies along an axial length of the microhole.

12. A system for producing electrical power, the system comprising: a cask configured to contain a radioactive material and attenuate gamma radiation incident on an interior surface of the cask; and a nuclear photovoltaic (nPV) cell positioned in the cask and including: a semiconductor photovoltaic body having an incident surface and a rear surface, a first charge collection layer proximate to the incident surface; and a second charge collection layer proximate to the rear surface of the semiconductor photovoltaic body and configured to receive charge from the semiconductor photovoltaic body.

13. The system of claim 12, wherein the nPV cell is positioned in the cask on at least a portion of the interior surface of the cask.

14. The system of claim 12, wherein the nPV cell is positioned on a lateral sidewall of the cask around the radioactive material.

15. The system of claim 12, wherein the nPV cell is configured to at least partially enclose a block of the radioactive material.

16. The system of claim 12, wherein the nPV cell further includes: a microhole in the semiconductor photovoltaic body formed at least in the incident surface, and a plurality of nanoparticles positioned in the microhole.

17. A method of manufacturing a nuclear photovoltaic (nPV) cell, the method comprising:forming a semiconductor photovoltaic body with a body thickness between an incident surface and a rear surface on a charge collection layer; forming a plurality of microholes in the semiconductor photovoltaic body; and positioning a plurality of nanoparticles in at least one of microhole of the plurality of microholes.

18. The method of claim 17, wherein forming the plurality of microholes includes laser ablating at least one of microhole of the plurality of microholes in the semiconductor photovoltaic body.

19. The method of claim 17, wherein at least one of microhole of the plurality of microholes is continuous through the semiconductor photovoltaic body between the incident surface and the rear surface.

20. The method of claim 17, wherein forming the plurality of microholes includes forming at least part of the plurality of microholes during forming of the semiconductor photovoltaic body.

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