Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
  • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/02—Details
  • H01L31/0224—Electrodes
  • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
  • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy

Definitions

• the invention relates to a photovoltaic element which is used in particular as a solar cell in photovoltaic systems in order to obtain electrical energy by absorbing sunlight.
• Highly efficient solar cells are known, for example, from “Solar Energy: Photovoltaics” (BG Teubner Verlag, Stuttgart, 1997) or “Research Association Solar Energy Topics 95/96, Photovoltaics 3".
• Highly efficient photovoltaic elements then have a "p-base” photon absorber, which consists of monocrystalline, zoned and p-doped (approx. 1.5 x 10 16 cm “3 ) silicon.
• the photon absorber has an electrical conductivity of approx. 1 ⁇ ⁇ cm "1 and a thickness of approx. 200 ⁇ m.
• the front of the photon absorber facing the light is textured with the help of recessed, inverted pyramids.
• the front of the photon absorber is covered with a thermally grown silicon dioxide layer, the thickness of which is approximately 100 nm.
• An emitter layer is arranged under the SiO 2 layer with a doping of approx. 1 x 10 19 cm “3 - 1 x 10 20 cm “ 3 and a penetration depth of approx. 0.5 - 3 ⁇ m.
• Metal conductors which consist of Ti-Pd-Ag, are arranged on the front of the photon absorber in order to supply and remove the electrons set in motion by the absorption of light quanta. Aluminum is vapor-deposited as a back contact on the underside of the photon absorber.
• BESTATIGUNGSKOPIE The evaporated aluminum is connected to a back surface field (BSF) via point contacts. With the help of the point contacts and the BSF, the electrical contact between the evaporated aluminum and the photon absorber is guaranteed.
• BSF back surface field
• the object of the invention is to provide an easily producible photovoltaic element or a photovoltaic device in which or in which the efficiency is improved.
• the object is achieved according to the invention by a photovoltaic element with the features of claim 1 and by a photovoltaic device with the features of claim 16.
• a photovoltaic element according to the invention in which an electrically conductive active element is at least partially embedded in a photon absorber.
• the photon absorber which is, for example, the absorber layer of a conventional solar cell, is in particular p-doped and is therefore designed as a "p-base".
• the active element is separated from the photon absorber by a phase boundary, ie the active element is not a doping of the photon absorber or alloy of the photon absorber, but an element which has different physical properties compared to the photon absorber.
• the active element also has a higher electron mobility than the photon absorber.
• the electrical conductivity of the active element is higher than that of the photon absorber.
• the electrical conductivity of the active element is preferably more than 1.4 ⁇ ⁇ cm “1 , particularly preferably more than 1.6 ⁇ ⁇ cm " 1 , in particular more than 2.0 ⁇ ⁇ cm “1 and in particular even more than 8.0 ⁇ ⁇ cm “1 .
• the active element has a large surface area and a large surface area in comparison to the volume.
• the active element is in particular elongated, for example as an elongated cylinder or cuboid.
• the ratio of surface area to volume is in particular greater than 2.5, preferably greater than 4.0 and particularly preferably greater than 6.5.
• the volume ratio of the photon absorber to the conductors is preferably in the range 2-7. A volume ratio of about 4 is particularly preferred.
• the active element can be, for example, a conductor, so that, compared to conventional photovoltaic elements, the conductor is not arranged outside but within the photon absorber. It was surprisingly found that the active element is electrically insulated in a preferred embodiment, ie the active element is neither connected to a plus pole nor to a minus pole, but at least partially arranged within the photon absorber.
• the active element can thus be a conductor which is neither connected to a positive pole nor to a negative pole, but is embedded in the photon absorber without contact with a voltage source.
• the embedded part of the active element has a certain reinforcing property.
• the electrons set in motion by light quanta can apparently easily transmit their electrical impulse to the electrons within the active element.
• This electrical impulse is reflected within the active element at the phase boundaries to the electrically denser medium with a higher ohmic resistance, namely in particular the photon absorber or the environment, until sufficient energy is stored in the active element in order to pass an energy-rich electrical pulse out of the active element to be able to transmit the photon absorber through to an electrical conductor.
• the conductors do not necessarily have to be part of the photovoltaic element according to the invention, but can also be, for example, an outer contact surface of a photovoltaic device receiving the photovoltaic element.
• the effect is believed to be due to a resonance phenomenon that results in an amplifier effect.
• the active element is therefore an amplifier element or an electrical resonance body.
• the active element thus produces an electron resonance with a wave characteristic that has a frequency bandwidth of approximately 75 Hz - 85 Hz.
• the electrons can be stored in the active element and, for example, be released to the photon absorber as a function of temperature, which additionally triggers electron / hole events which lead to additional amplification, which improves the efficiency.
• the absorption of photons in the photon absorber creates electron / hole pairs which can be conducted out of the photon absorber as an electric current via an electric field.
• capacitor plates can be provided on opposite sides of the photon absorber, which are connected to a plus pole or a minus pole.
• an electric field is provided by providing at least one conductor that is at least partially embedded in the photon absorber. This avoids capacitor plates arranged outside the photon absorber.
• the conductor can be embedded in the photon absorber, as a result of which different manufacturing processes are avoided and the manufacturing costs are reduced.
• the conductor can have the same composition as the active element, so that the provision of different material compositions is avoided.
• a large-area photon absorber in which a large number of active elements are embedded.
• the large-area photon absorber can then be divided into several small photon absorbers.
• individual active elements can be designed as conductors. For this purpose, for example, a cable connected to a positive pole or negative pole can be soldered to one of the active elements. Individual active elements are preferably connected in series. As a result, a fully functional solar cell can be produced using structurally simple measures that are particularly suitable for mass production.
• At least two conductors are arranged in the photon absorber, one conductor being a plus conductor connected to a plus pole and the other conductor being a minus conductor connected to a minus pole.
• the plus conductors are arranged in such a way that they end or protrude on a first end face of the photon absorber and the minus conductors in a corresponding embodiment end or protrude on a second end face of the photon absorber. This makes it possible to connect several, in particular all, positive conductors via a first common conductor on the first end face and several, in particular all, minus conductors via a second common conductor on a second end face.
• the photovoltaic element is preferably configured in multiple layers.
• the photovoltaic element has at least two photon absorbers, each of which is in contact via a contact surface.
• the alignment of the photon absorbers is preferably anti-parallel.
• the plus conductors and the minus conductors are arranged in such a way that the plus conductors and the minus conductors are delimited from one another via the contact surface. This results in a greater spatial separation of the plus conductors and the minus conductors.
• both photon absorbers in which, for example, both active elements and conductors are arranged, can be configured identically, the conductors of one photon absorber being connected to the plus pole and the conductors of the other photon absorber being connected to the minus pole.
• the photovoltaic element according to the invention is particularly suitable for mass production.
• the photovoltaic element can preferably have, for example, four layers, the third and fourth layers being antiparallel to the first and second layers, for example. This can increase the degree of absorption. To further increase the degree of absorption, more than four layers can also be provided.
• the photon absorber preferably consists essentially of silicon, in particular of monocrystalline silicon, which may be doped, so that a "p-base" results.
• the active element preferably consists largely, in particular completely, of a metal and is optionally doped or alloyed.
• the metals Pt, Ag and Au are preferably avoided due to the high raw material costs.
• the metal comes especially from the 3rd - 6th main group or the 1st - 8th subgroup according to the periodic table of the elements.
• the metal is preferably a subgroup metal whose electron configuration has an outer d-shell which is occupied by at least ten electrons.
• the invention further relates to a photovoltaic device with a receiving element which has recesses. Photovoltaic elements as described above are arranged in these recesses.
• the photovoltaic device has a first and a second connecting conductor, which are connected to a plus pole and a minus pole, respectively.
• the electrical connection to the photovoltaic elements is guaranteed via the connecting conductor.
• the connecting conductors are connected in particular to the plus conductor or minus conductor and / or, if present, to the corresponding collective conductor.
• a plurality of photovoltaic elements are arranged in a recess, the recess being in contact with at least one photon absorber of the photovoltaic element and being insulated in particular from the conductors.
• the photovoltaic device is designed to be electrically conductive at least in the region of the recesses and is made of a preferably aluminum-containing material, for. B. AIP, which may be endowed, composed.
• the receiving element essentially fulfills an amplification power which can be explained as follows: All electrons from the photo absorber with an energy of at least 0.8 eV, which either originated from the p-base in a photo-induced manner, or which additionally originate from resonance-induced, come under given conditions Geometric conditions in the receiving element and trigger electrical movements there, which produce a reinforcing effect, so that the outflowing electrons return to the photo absorber in about 3 times the amount.
• This proportion of electrons flowing back into the photo absorber from the receiving element is increased by photo-induced electrons of such residual light quantities that strike the receiving element.
• the photovoltaic elements are fitted in the recess of the receiving element, so that there is preferably direct contact between the receiving element and the photovoltaic element.
• a plurality of first connection conductors are preferably connected to exactly one first current conductor and a plurality of second connection conductors are connected to exactly one second current conductor.
• the second current conductor performs the function of the "back surface field", the "back surface field” being reduced to a "back surface line”. This makes it possible to spatially separate the "back surface line” thus created in order to avoid electrical short-circuit currents or to reduce disturbing electrical fields.
• the use of materials for realizing the back contact is reduced.
• the electrical field required for charge separation is spatially widely distributed and in particular spans the following components of the photovoltaic element:
• the band-shaped / wire-shaped conductor corresponds functionally to the n + emitter.
• the minus board is embedded in a silicon matrix.
• the silicon layers are designed as pairs, each with an anti-parallel orientation.
• the plus board is embedded in a silicon matrix.
• the photovoltaic device has connecting means in order to mechanically and electrically connect at least two photovoltaic devices arranged next to one another.
• the mechanical or electrical connection can be achieved with different as well as with a common connection means.
• An independent invention is a method of making monocrystalline anisotropic silicon. First, a cuboid made of monocrystalline silicon, which is doped, is cut into slices that correspond to the planned layer thickness of a photon absorber for a photovoltaic element.
• This disk is slowly heated to the melting point, for example within 90 minutes, and in particular is kept at this temperature level for about 30 minutes.
• the silicon wafer is then carefully cooled to approximately 300 ° C. over a period of, for example, eight hours, in particular at intervals. From approx. 300 ° C the cooling can take place without control.
• This process results in a preferably circular disk of uniform layer thickness made of monocrystalline anisotropic silicon.
• Three photon absorbers are preferably cut or sawn out of the silicon wafer, which are arranged at a defined angle to one another, preferably radially symmetrically. This process can be used to produce photon absorbers that have a high degree of homogeneity in the orientation of the crystal structure.
• FIG. 1 is a schematic perspective view of a photovoltaic element
• FIG. 2 shows a schematic sectional view of the photovoltaic element along the line II-II from FIG. 1, 3 shows a schematic top view of a second embodiment of the photovoltaic element,
• FIG. 4 shows a schematic sectional view of the photovoltaic element along the line IV-IV from FIG. 3,
• FIG. 5 shows a schematic sectional side view of a multilayer photovoltaic element
• FIG. 6 shows a schematic side view of the photovoltaic element in the direction of arrow VI from FIG. 5,
• FIG. 7 shows a schematic side view of the photovoltaic element in the direction of arrow VII from FIG. 5,
• FIG. 8 shows a schematic top view of a photovoltaic device
• Fig. 9 is a schematic sectional view of the photovoltaic device along the line IX-IX of Fig. 8, and
• FIG. 10 shows a schematic top view of a silicon wafer for producing photon absorbers.
• An electrically conductive active element 12 is embedded in an electrically insulated manner in a photon absorber 10 shown in FIG. 1. Further active elements are designed as positive conductors 14 and as negative conductors 16. For simple soldering, part of the plus conductor 14 projects beyond a first end face 18 of the photon absorber 10. Correspondingly, part of the minus conductor 16 projects beyond a second end face 20 of the photon absorber 10.
• the photon absorber 10 can absorb electromagnetic radiation, in particular in the range from 95 nm to 1220 nm.
• the absorption maxima of the photon absorber 10 are in particular 130 nm ⁇ 15 nm and 720 nm + 15 nm. As a result, a degree of absorption for electromagnetic radiation of approximately 42% can be achieved.
• the active element 12, the plus conductor 14 and the minus conductor 16 are completely embedded in the photon absorber 10. Their surfaces facing away from the photon absorber 10 are flush with the surface of the photon absorber 10 (FIG. 2).
• a plurality of active elements 12, plus conductors 14 and minus conductors 16 are arranged in the photon absorber 10 (FIG. 3). There is a distance between the active elements 12, plus conductor 14 and minus conductor 16 from one another, at which the efficiency is particularly high. This distance can be determined experimentally depending on the material used.
• silicone pads 22 are arranged between the end faces 18, 20 of the photon absorber 10 and the end faces of the active elements 12.
• the active elements 12, the plus conductors 14 and the minus conductors 16 are elongated and are arranged essentially parallel to one another.
• the active elements 12, the plus conductors 14 and the minus conductors 16 are essentially designed as strips arranged next to one another, which essentially have a cuboid geometry.
• the protruding ends of the plus conductor 14 and the minus conductor 16 are connected to a first collecting conductor 24 and a second collecting conductor 26, in particular by soldering (FIG. 4).
• the collecting conductors 24, 26 are arranged on the first end face 18 or on the second end face 20.
• the photovoltaic element according to the invention can be configured in one, two or more layers (FIG. 5).
• the photon absorber 10 has, for example four layers 28, 30, 32, 34, which are each in contact via contact surfaces 36.
• the photon absorber 10 is preferably provided with a textured polycarbonate layer 38 both on the top and on the bottom in the sense of a “light trap”.
• the polycarbonate layer 38 is in turn provided on both sides with a glass layer 40 in order to protect the photovoltaic element according to the invention from damage.
• the first layer 28 and the third layer 32 have an antiparallel anisotropic crystal structure with respect to one another.
• the second layer 30 and the fourth layer 34 likewise have an antiparallel anisotropic crystal structure with respect to one another.
• the multilayer photovoltaic element 44 is held by a receiving element 54.
• the opening or incidence angle for electromagnetic radiation, which can be absorbed by the photon absorber 10 or the layers 28, 30, 32, 34, is thus over 130 ° to about 153 °.
• a negative pressure is preferably generated, which is in particular 0.3-0.5 bar.
• the collecting conductors 24, 26 preferably also extend over several layers (FIG. 6, FIG. 7).
• the collecting conductors 24, 26 are arranged, for example, lengthways. Since the positive conductors 14 and the negative conductors 16 protrude on opposite end faces 18 and 20, the risk of a short circuit is avoided. However, it is preferred not to lay the collecting conductors 24, 26 over the ends of the conductors with opposite charges, in order to avoid possible disturbances due to strong electric fields in this area or short circuits.
• a photovoltaic device 42 according to the invention has a plurality of photovoltaic elements 44 according to the invention (FIG. 8).
• the first collecting conductors 26 of the photovoltaic elements 44 are each connected to a connecting conductor 46.
• common conductors 27 are connected to a connecting conductor 48.
• the latter form the back contact designed as a "back surface line", while the collecting conductors 26 functionally correspond to the n + emitters of conventional photovoltaic systems.
• the connecting conductors 46 and 48 of the individual photovoltaic elements are further electrically connected to the conductors 50, 52 across all the way to the end poles.
• the photovoltaic device 42 has connecting means (not shown) in order to mechanically connect adjacent photovoltaic devices 42.
• the current conductors 50, 52 of adjacent photovoltaic devices 42 are electrically connected to one another. 6 and 7 show a possible construction in the arrangement of downstream conductors. These are connected in series.
• the photovoltaic device 42 has receiving elements 54 with recesses 56 (FIG. 9).
• the photovoltaic elements 44 are inserted into the recesses 56 in the receiving elements 54.
• the receiving element 54 can act as an amplifier in that it is at least partially designed to be electrically conductive and is in contact with both the third layer 32 and the fourth layer. Avoid contact with conductors of the same name.
• the receiving element 44 has an opening 57 below the lowermost layer 34 in a preferred construction, whereby material is saved. Possibly.
• the opening 57 can also be completely closed, for example with AIP.
• the layers 28, 30, 32, 34 are in particular designed as a thick layer system with a total thickness of approximately 3 mm to 18 mm, so that the risk of breakage of the photovoltaic element 44 is reduced.
• a silicon wafer 58 is first made from monocrystalline anisotropic silicon (FIG. 10), from which the Photon absorber 10 are sawn out.
• the photon absorbers 10 to be cut out are preferably at a distance from an edge 60 of the silicon wafer 58 in order to avoid any structural defects that may occur in the atomic lattice in the edge region of the silicon wafer 58.
• the remainder of the silicon wafer 58 remaining after sawing out the photon absorbers 10 can then be melted down and reused, so that a complete recycling of the silicon wafer material is possible.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Electromagnetism (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Photovoltaic Devices (AREA)

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• 2003
  • 2003-10-01 DE DE10345736A patent/DE10345736A1/de not_active Withdrawn
• 2004
  • 2004-09-30 JP JP2006530047A patent/JP2007507868A/ja not_active Ceased
  • 2004-09-30 US US10/573,864 patent/US20070039645A1/en not_active Abandoned
  • 2004-09-30 CN CNB200480028728XA patent/CN100517768C/zh not_active Expired - Fee Related
  • 2004-09-30 WO PCT/EP2004/010916 patent/WO2005034171A2/de active Application Filing
  • 2004-09-30 ZA ZA200602141A patent/ZA200602141B/xx unknown
  • 2004-09-30 EP EP04765705A patent/EP1676293A2/de not_active Withdrawn

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