US20110168244A1 - Method and means for a high power solar cell - Google Patents
Method and means for a high power solar cell Download PDFInfo
- Publication number
- US20110168244A1 US20110168244A1 US13/051,097 US201113051097A US2011168244A1 US 20110168244 A1 US20110168244 A1 US 20110168244A1 US 201113051097 A US201113051097 A US 201113051097A US 2011168244 A1 US2011168244 A1 US 2011168244A1
- Authority
- US
- United States
- Prior art keywords
- solar cell
- photons
- photon
- layer
- filter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 32
- 230000006870 function Effects 0.000 claims description 12
- 230000005611 electricity Effects 0.000 claims description 11
- 239000013078 crystal Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 5
- 239000011248 coating agent Substances 0.000 claims description 3
- 239000010410 layer Substances 0.000 description 191
- 239000000463 material Substances 0.000 description 31
- 238000001228 spectrum Methods 0.000 description 30
- 239000006117 anti-reflective coating Substances 0.000 description 16
- 238000004519 manufacturing process Methods 0.000 description 10
- 229910052782 aluminium Inorganic materials 0.000 description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 9
- 238000001914 filtration Methods 0.000 description 9
- 230000004044 response Effects 0.000 description 9
- 238000010586 diagram Methods 0.000 description 8
- 230000009102 absorption Effects 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 7
- 239000010408 film Substances 0.000 description 7
- 230000003287 optical effect Effects 0.000 description 7
- 239000012071 phase Substances 0.000 description 7
- 239000004065 semiconductor Substances 0.000 description 7
- 230000008901 benefit Effects 0.000 description 6
- 239000011888 foil Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 230000003667 anti-reflective effect Effects 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000010248 power generation Methods 0.000 description 5
- 229910052710 silicon Inorganic materials 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- 230000003595 spectral effect Effects 0.000 description 5
- 229910005540 GaP Inorganic materials 0.000 description 4
- GPXJNWSHGFTCBW-UHFFFAOYSA-N Indium phosphide Chemical compound [In]#P GPXJNWSHGFTCBW-UHFFFAOYSA-N 0.000 description 4
- 230000004907 flux Effects 0.000 description 4
- HZXMRANICFIONG-UHFFFAOYSA-N gallium phosphide Chemical compound [Ga]#P HZXMRANICFIONG-UHFFFAOYSA-N 0.000 description 4
- WPYVAWXEWQSOGY-UHFFFAOYSA-N indium antimonide Chemical compound [Sb]#[In] WPYVAWXEWQSOGY-UHFFFAOYSA-N 0.000 description 4
- 230000003993 interaction Effects 0.000 description 4
- 229910002601 GaN Inorganic materials 0.000 description 3
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 3
- 239000004411 aluminium Substances 0.000 description 3
- 230000036755 cellular response Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910052738 indium Inorganic materials 0.000 description 3
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 3
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 description 2
- KTSFMFGEAAANTF-UHFFFAOYSA-N [Cu].[Se].[Se].[In] Chemical compound [Cu].[Se].[Se].[In] KTSFMFGEAAANTF-UHFFFAOYSA-N 0.000 description 2
- CJOBVZJTOIVNNF-UHFFFAOYSA-N cadmium sulfide Chemical compound [Cd]=S CJOBVZJTOIVNNF-UHFFFAOYSA-N 0.000 description 2
- 229910052980 cadmium sulfide Inorganic materials 0.000 description 2
- 238000002109 crystal growth method Methods 0.000 description 2
- 238000001413 far-infrared spectroscopy Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 238000004943 liquid phase epitaxy Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- MARUHZGHZWCEQU-UHFFFAOYSA-N 5-phenyl-2h-tetrazole Chemical compound C1=CC=CC=C1C1=NNN=N1 MARUHZGHZWCEQU-UHFFFAOYSA-N 0.000 description 1
- 229910004613 CdTe Inorganic materials 0.000 description 1
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- MDPILPRLPQYEEN-UHFFFAOYSA-N aluminium arsenide Chemical compound [As]#[Al] MDPILPRLPQYEEN-UHFFFAOYSA-N 0.000 description 1
- 229910021417 amorphous silicon Inorganic materials 0.000 description 1
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- HVMJUDPAXRRVQO-UHFFFAOYSA-N copper indium Chemical compound [Cu].[In] HVMJUDPAXRRVQO-UHFFFAOYSA-N 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- ZZEMEJKDTZOXOI-UHFFFAOYSA-N digallium;selenium(2-) Chemical compound [Ga+3].[Ga+3].[Se-2].[Se-2].[Se-2] ZZEMEJKDTZOXOI-UHFFFAOYSA-N 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 1
- 238000001451 molecular beam epitaxy Methods 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000009304 pastoral farming Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Images
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 at least one potential-jump barrier or surface barrier
-
- 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 at least one potential-jump barrier or surface barrier
- H01L31/072—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 at least one potential-jump barrier or surface barrier the potential barriers being only of the PN heterojunction type
- H01L31/0725—Multiple junction or tandem solar cells
-
- 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
- H01L31/0232—Optical elements or arrangements associated with the device
-
- 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
- H01L31/054—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means
-
- 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
- H01L31/054—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means
- H01L31/0543—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means comprising light concentrating means of the refractive type, e.g. lenses
-
- 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
- H01L31/054—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means
- H01L31/0547—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means comprising light concentrating means of the reflecting type, e.g. parabolic mirrors, concentrators using total internal reflection
-
- 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
- Y02E10/52—PV systems with concentrators
Definitions
- the invention relates to methods and means for improving the power generated and efficiency of solar cells.
- Photovoltaic solar cells are the most recently discovered new method of producing energy, dating from the 1950's Soviet and US satellite power systems. Photovoltaic solar cells produce electricity with very low environmental impact, and are because of this desired by the public. The problem with present photovoltaic solar cells is that they do not produce enough energy for their cost and/or surface area to make them economically viable.
- EP 1724841 A1 describes a multilayer solar cell, wherein plural solar cell modules are incorporated and integrally laminated, so that different sensitivity wavelength bands are so that the shorter the centre wavelength in the sensitivity wavelength band is, the more near the module is located to the incidental side of sunlight. This document is cited here as reference. It is currently not known, which are all the factors that cause a shortcoming in the efficiency of the multilayer solar cell. However, based on the studies of the applicant, the general tandem solar cell is hampered the most by the photon-phonon processes that take place outside the band of maximum quantum efficiency of the solar cell, i.e. this is where in frequency space the cell generates a lot of heat. Individual factors pertaining to the disadvantages are also listed in the columns 1 and 2 of U.S. Pat. No. 6,689,949, which is cited here as reference.
- U.S. Pat. No. 6,689,949 discloses a photovoltaic reflective cavity with several solar cells in the cavity.
- the solar cells inside the cavity are under filters that filter the light so that the incoming photon flux is more appropriate for the quantum efficiency of the solar cell, i.e. more appropriate for its response or detector response.
- NASA and JPL Jet Propulsion Laboratory have also proposed an alternative technique, called “Rainbow” where beam splitters and concentrators are used to split the solar spectrum into different bands and focus the different bands of light to different discrete solar cells that can handle the splitted and focused spectrum the best.
- This scheme requires a very complicated optical arrangement, and has not materialised to anything practical so far.
- U.S. Pat. No. 5,021,100 discloses a tandem solar cell that has a reflective film between the first and the second solar cell (incident cell on sunlight side in this publication), where the reflective film is supposed to reflect high energy photons to the second solar cell and let low energy photons to the first solar cell (behind the second solar cell in this publication). This document is cited here as reference.
- U.S. Pat. No. 5,021,100 has a serious problem in that the reflective film is a bidirectional, i.e. any reflected photons in the first solar cell will leak back to the second solar cell through the reflective film, and cause phonons and heat, as these photons cannot get absorbed in the second solar cell.
- the invention under study is directed towards a system and a method for effectively solving the problems of the prior art and realising a more powerful solar cell.
- a more particular object of the invention is to present the aforementioned solar cell system, which has high capital cost in design, but ultimately a low production cost with large economies of scale.
- the invention introduces a tandem solar cell where each solar cell layer works with photons at energies where that solar cell layer has the highest quantum efficiency.
- One aspect of the invention involves a solar cell with a photon reflector on the side opposite to the incident side of sunlight.
- the reflector is arranged to reflect photons with wavelengths suitable to the quantum efficiency function of the solar cell back to the solar cell.
- a tandem solar cell with two solar cell layers.
- the solar cell that is incident to sunlight is exposed, and this solar cell layer typically has the band gap that is of the higher energy.
- the solar photons enter this first solar cell, and the higher energy part of the solar spectrum is likely to get converted to photocurrent.
- Some high energy photons do not interact with the semiconductor, and just pass through or get dissociated into photons and phonons of lesser energy by the photon-phonon process.
- Those photons that are still of high enough energy to get converted to photocurrent in the first layer i.e.
- the energy of the photon (E) E>E bg1 is greater than the band gap (E bg1 ) of first solar cell, are reflected back into the first solar cell layer by the photon filter. These photons will get a second chance to get converted into photocurrent.
- the first solar cell layer is very thin and very pure, so that there is less time and space for non-absorbing processes, i.e. heat conversion by photons that do not match the band gap.
- the photons with energy E ⁇ E bg1 band gap are now passed through by the filter to the second solar cell layer that has a lower band gap E bg2 . A large portion of these photons can now interact with the second band gap.
- the photon filter will collect the lower energy photons and then focus the lower energy photons into the second solar cell layers through very small apertures on the other side of the filter. These small apertures are permeable to photons.
- the rest of the area on the other side of the photon filter is also covered with a reflector material. This is because on the bottom of the second solar cell layer there is also a reflector that reflects photons capable of converting into photocurrent in the second solar cell layer back to the second solar cell layer. Some photons that get reflected from this reflector are still unabsorbed after having passed through the second solar cell layer the second time on their return journey. These photons are sent back by the reflector material surrounding the small apertures just said.
- the reflectors on the opposite side of the sunlight incident side of the photon filter and at the bottom of the tandem solar cell system trap the photons capable of producing photocurrent in the second solar cell layer, i.e. photons typically of E>E bg2 . These photons bounce back and forth until they get absorbed or dissociate into photons of energy less than E bg2 .
- the entrapment of the photons into the second solar cell results from the first photon filter being unidirectional. I.e. apart from the very small possibility of leaked photons back through the small apertures, the majority of the photon population is bouncing between two reflectors in a second solar cell that has a band gap favourable for photoelectric absorption and current generation.
- the photon filter described above relies on a technique developed by the inventor, and named by the inventor, as spatiospectral modulation.
- a unidirectional photon filter may also be realised in the above example by two reflective photon filters with an antireflective coating and/or coarsening between them in accordance with the invention.
- the materials of the solar cells and photon filters may be selected so that the unidirectional filtration of photons is achieved based on the refractive indices of the materials in accordance with the invention. These photon filters in contrast suffer some losses in ideal unidirectionality in the form of leaking photons from stray angles.
- the tandem solar cell comprises several solar cell layers, and in between two layers there is a photon filter.
- the photon filters are tuned so, that they will trap only those photons that are at an energy where the solar cell layer is working at a good quantum efficiency (QE), ideally close to 1.
- QE quantum efficiency
- the rest of the photons are simply passed to the next layer by the photon filter.
- quantum efficiency we mean its general meaning as defined in Larousse Dictionary of Science and Technology: quantum efficiency (Phys): “Number of electrons released in a photocell per photon of incident radiation of specified wavelength”. Inventor further points out that this parameter can be normalised to yield the typical 100-0% scale when necessary.
- the quantum efficiency is an extremely good measure of how good the photocell is in converting photons into electricity.
- the detector response or response is the quantum efficiency as a function of wavelength, i.e. it tells how the photocell responds to incoming photons at different energies.
- QE quantum efficiency
- the band of spectrum that might be worth holding onto in a particular solar cell layer is when the QE exceeds 10%, i.e. the overall QE of present wholesale market solar cells.
- roughly 30-50% should be regarded as the threshold QE, if the tandem solar cell is going to economically replace oil and gas in the current market conditions. Photons at energies where the solar cell layer has a QE less than 30-50% should be moved to other solar cell layers that have higher QEs, as will be described later in the application.
- a Nokia E71 mobile phone has an area of 72 cm 2 and a battery of 1.5 Ah, with a voltage of 3.7 V. If the inventive solar cell achieves an efficiency of 50% and covers the surface of the phone with an area of 72 cm 2 , assuming a solar flux of 1000 W/m 2 this will mean that the battery will fully charge in approximately 1.5 hours of exposure according to the calculations of the applicant. Quite clearly, 1.5 hours of exposure over the battery life of roughly a week is beginning to be at the reach of the market, if it provides the added benefit of not having to use an electric grid charger most of the time.
- Some or all of the aforementioned advantages of the invention are accrued in one embodiment where there can be many, for example a hundred solar cell layers of different band gaps separated by reflecting photon filters as just described.
- a semiconductor junction can maintain high quantum efficiency only at a very narrow band. The further the departure from the optimum energy, the smaller the QE gets.
- the photon filters are set so that the first solar cell layer will have photons of energy 150-160 nm in wavelength space, the second 160-170 nm, the third 170-190 nm, and so on.
- the first solar cell layer only needs to be efficient in the 150 nm-160 nm band, which is easier to achieve.
- it should disturb the photons with wavelengths longer than 160 nm as minimally as possible.
- These photons will pass to the layers that follow with each being trapped as explained above into their own 10-20 nm bands with a solar cell layer that is at its best efficiency at that band.
- a tandem solar cell in accordance with the invention is defined by the subject matter claimed and comprises at least two layers of solar cells, the first and the second layer and is characterised in that,
- the above photon filter is also arranged to reflect back the returning photons from the second solar cell, and prevent them from entering the first solar cell, thereby realising unidirectionality of the photon filter in accordance with the invention.
- a method of producing the aforementioned tandem solar cell is in accordance with the invention.
- a photon filter is arranged to reflect photons with wavelengths shorter than ⁇ x from its first side and arranged to be transparent to photons of wavelengths longer than ⁇ x by focussing the said longer wavelength photons out of small area apertures on the other side opposite to the first side of the photon filter and the other side of the photon filter is arranged to reflect at least some of the said photons of wavelength longer than ⁇ x .
- a tandem solar cell comprises at least two solar cell layers is characterised in that the said tandem solar cell is arranged to transport an incoming photon to the solar cell layer that has the highest quantum efficiency (QE) at the energy of the said incoming photon in comparison to the other said solar cell layers in the tandem solar cell.
- QE quantum efficiency
- a tandem solar cell in accordance with the invention comprises at least two layers of solar cells, the first and the second layer and is characterised in that,
- a tandem solar cell in accordance with the invention comprises at least two layers of solar cells, the first solar cell layer and the second solar cell layer and is characterised in that, at least one unidirectional photon filter is arranged between the first and the second solar cell layers.
- “unidirectional photon filter” in the context of this application means a photon filter which is arranged to reflect a group of photons, and arranged to pass a group of photons through one way, but also arranged to NOT allow passed photons to return back again through the said photon filter.
- the invention presents four unidirectional photon filters, the spatiospectrally modulating filter, the antireflective coating filter, the coarse antireflective filter and/or the refractive index filter. These filters are construed as unidirectional in this application, while acknowledging the practical bounds of these filters filtering photons unidirectionally.
- a tandem solar cell in accordance with the invention comprises at least two layers of solar cells, the first solar cell layer with a band gap energy of E bg and the second solar cell layer and is characterised in that, the second solar cell has a lower refractive index than the first solar cell layer at photon energies equal or higher than E bg .
- the second solar cell typically also has a higher refractive index than the first solar cell layer at photon energies lower than E bg in accordance with the invention, and a band gap lower than E bg .
- a tandem solar cell in accordance with the invention comprises at least two layers of solar cells, the first solar cell layer and the second solar cell layer and is characterised in that, at least one said solar cell layer is arranged to have its quantum efficiency (QE) vs. wavelength and its refractive index vs. wavelength functions to reach peak and/or high values at same wavelengths.
- QE quantum efficiency
- a portable electronic device in accordance with the invention comprises at least one solar cell and is characterised in that, said portable electronic device features at least one piezoelectric crystal and/or at least one mechanical means arranged to generate electricity from mechanical movement of said portable electronic device.
- the said solar cell is preferably a tandem solar cell, most preferably the tandem solar cell described in this application, but in some embodiments it may also be a conventional solar cell.
- the best mode of the invention at present is considered to be a double or triple junction tandem solar cell that has one or two photon filters of the invention in between the solar cell layers, respectively.
- This tandem solar cell is used to power a self charging mobile phone, which may have a mechanical/kinetic electricity generator such as piezoelectric crystals or a pendulum/spring system found in e.g. watches as a backup for charging at times when the mobile phone is concealed from light, e.g. in the pocket of the user.
- FIG. 1 demonstrates an embodiment of the photon filter 10 as a block diagram.
- FIG. 2 demonstrates an embodiment of an inventive tandem solar cell with two solar cell layers as a block diagram 20 .
- FIG. 2B demonstrates an embodiment of an inventive tandem solar cell with two solar cell layers with alternative unidirectional photon filters as a block diagram 21 .
- FIG. 2C demonstrates an embodiment of an inventive tandem solar cell with two solar cell layers with alternative unidirectional photon filters as a block diagram 22 and a focusing means on the sunlight incident side.
- FIG. 2D demonstrates an embodiment of an inventive tandem solar cell with two solar cell layers with alternative photon filtration realised by the selection of refractive indices for solar cell materials, as a block diagram 23 .
- FIG. 3 demonstrates an embodiment 30 of an inventive tandem solar cell with four solar cell layers as a block diagram 30 .
- FIG. 4 demonstrates an embodiment 40 of the operation of the inventive tandem solar cell in terms of spectra, i.e. in the energy-wavelength space.
- FIG. 5 demonstrates an embodiment 50 of the operation of the inventive tandem solar cell as a flow diagram.
- FIG. 1 demonstrates an exemplary embodiment of the photon filter 100 in isolation that is to be placed between two solar cell layers in a tandem solar cell.
- the incident sunlight side is assumed up in this figure.
- Photons with ⁇ 2 have higher energy than photons with ⁇ 1 i.e. ⁇ 2 ⁇ 1 in some embodiments, but it is also possible that the filter 100 is configured in reverse, i.e. it reflects low E photons whilst letting high E photons pass in accordance with the invention.
- the photon filter 100 has a reflecting cover 110 on the sun incident side.
- the reflecting cover 110 may be a Rugate filter, or any other optical band pass filter in accordance with the invention.
- the reflecting cover are at least one focusing means for the photons that are not reflected, i.e. the photons that pass through the reflecting cover 110 .
- These focusing means that are typically lenses of any shape, can be and are shown circular in the figure, focus the photon population into a narrowing horn 130 .
- This horn may be covered with reflecting material from the inside so that the photons that pass through it are directed out of at least one small aperture 140 . In some embodiments there may be no horn, but still in these embodiments the photons are focused to a small spot when they exit the filter 100 .
- On the opposite side to incident sunlight most of the area is occupied by another photon reflector 150 .
- the small apertures are embedded into the reflector 150 and occupy only a fraction of the area of the other side of the photon filter 100 .
- the reflector 150 is designed to reflect back the photons that entered the solar cell underneath from the at least one aperture 140 , but did not interact with the solar cell layer, and got instead reflected by another filter on the other side of the second solar cell layer.
- the ratio of the area of reflector 150 to apertures 140 is made as big as possible in accordance with the invention. This is because the smaller the area of the apertures is in comparison to reflector 150 , the smaller the probability for a reflecting photon to leak back to the first solar cell 200 , and thereby violate unidirectionality of the filter.
- the effect of the spatial modulation that allows the reflection by the reflector 150 might be realised by other means besides focusing the entry into small apertures in some embodiments.
- a unidirectionally transparent filter could be used in some embodiments to replace the focusing means 120 and apertures 140 in accordance with the invention.
- the filter 100 it is important that the transparency is indeed unidirectional, the filter 100 must not let those photons filtered through to the next layer to return to the first layer 200 in accordance with the invention.
- the filter 100 , 110 , 150 can be any band pass, short pass, long pass and/or notch filter, a Rugate filter and/or a discrete layer stack filter in accordance with the invention.
- the solar cell layers can be only a few nanometers thick in some embodiments of the invention, it is also possible that the photon filter is very thin, just a few nanometers in thickness in accordance with the invention.
- At least one aperture 140 contains a diffracting or dispersing element that spreads the photons from the apertures effectively into the second solar cell.
- the at least one focusing means 120 , horn 130 , aperture 140 , reflector 110 , and/or 150 can be made from any material in accordance with the invention.
- Optical filter and/or reflector components 110 , 130 , 150 and/or focusing elements 120 , 121 , 140 , 141 can be made of any of the following in accordance with the invention: reflective foil, such as metal foil, ultraviolet/visible/infra red mirror such as aluminium or gold mirror or said mirror or mirror foil with opaque, vacuum-deposited metallic coatings on low-expansion glass substrates, Aluminum/MgF2-mirror, Aluminum/SiO-mirror, Aluminum/dielectric-mirror, Protected Gold-mirror and/or normal mirror and/or any Rugate filter material and/or dielectric stack material and/or any band pass, short pass, long pass and/or notch filter.
- reflective foil such as metal foil, ultraviolet/visible/infra red mirror such as aluminium or gold mirror or said mirror or mirror foil with opaque
- the choice of the reflective and/or focusing material should be based on the reflectance-wavelength function of the material amongst other practical things such as cost and availability in some embodiments of the invention. In some embodiments it is preferred for the reflection and/or focusing to be efficient up to Far-IR, or in any case to the wavelength that equates with the smallest band gap in the solar cell layers.
- the focusing structure can also be replaced with a filter that is a: Rugate filter and/or dielectric stack filter or a filter that combines the said two technologies to realise a unidirectional filter. This could be realised so that total internal reflection is practically always present at the outside face 150 for photons that have passed through the filter preventing them from returning, because of the angle and energy distribution of the photons after the filter 100 . However, when the photons are coming from the other side ( 110 , i.e. those that were not reflected), these photons are aligned to penetrate through face 150 from the inside.
- embodiment 10 can be freely combined and permuted with embodiments 20, 21, 30, 40 and 50 later in the text in accordance with the invention.
- FIGS. 2A , 2 B, 2 C, and 2 D display embodiments of the invention where the two solar cell layers are combined with the photon filters of the invention to realise an inventive tandem solar cell 20 .
- the incident sunlight is at the top of the figures as shown.
- the first solar cell layer 200 or any subsequent solar cell layer mentioned in this application can be typically made of or may contain Si (Silicon), polycrystalline silicon, thin-film silicon, amorphous silicon, Ge (Germanium), GaAs (Gallium Arsenide), GaAlAs (Gallium Aluminum Arsenide), GaAlAs/GaAs, GaP (Gallium Phosphide), InGaAs (Indium Gallium Arsenic), InP (Indium phosphide), InGaAs/InP, GaAsP (Gallium Arsenic Phosphide) GaAsP/GaP, CdS (Cadmium Sulphide), CIS (Copper Indium Diselenide), CdTe (
- first solar cell layer 200 or any subsequent solar cell layer mentioned in this application may feature any element or alloy combination, or any material capable of photoelectric effect described in the publications FI20070264, FI20070743, FI20070801, EP 09154530.1, EP 1724 841 A1, Josuke Nakata, “Multilayer Solar Cell”, U.S. Pat. No. 6,320,117, James P. Campbell et al., “Transparent solar cell and method of fabrication”, Solar Electricity, Thomas Markvart, 2 nd Edition, ISBN 0-471-98852-9 and “An unexpected discovery could yield a full spectrum solar cell, Paul Preuss, Research News, Lawrence Berkeley National Laboratory, which publications are all incorporated into this application by reference in accordance with the invention.
- the first photon filter 100 is arranged in between the solar cell layers 200 and 201 , and the solar cell 200 is arranged with the photon filter 100 on the side opposite to the incident side of sunlight.
- the photon filter 100 is arranged to reflect photons back into the first solar cell 200 with energies that are at energies where the first solar cell 200 has high quantum efficiency ( ⁇ 2 photons).
- the photon filter 100 is arranged to be transparent to photons of other energies or wavelengths ⁇ 1 , and these photons are arranged to enter the second solar cell ( 201 ).
- the photon filter 100 does not allow the ⁇ 1 photons to return back to the first solar cell layer, thereby realising unidirectionality. Therefore the photons that have an energy/wavelength ⁇ 2 that could get converted to photocurrent in first solar cell layer 200 are reflected back to the first solar cell layer 200 by e.g. the reflector 110 , and those that can't are arranged to be transported to another solar cell layer, such as second solar cell layer 201 , where they remain entrapped if at energy higher than the energy band gap of second solar cell layer 201 .
- the solar cell layers are very thin to minimise the scattering cross-section of unwanted photon interactions, i.e. those that happen at energies where the quantum efficiency of the solar cell layer is poor. These interactions heat up the solar cell.
- the sunlight incident side of solar cell 200 is covered by a semi-permeable film, or an anti-reflection coating 167 shown in FIG. 2B .
- incident sunlight is focused on a section of the first solar cell 200 , and the resulting beam is arranged to be dispersed by reflector 110 after it has passed through the first solar cell layer 200 , i.e. the reflector might also have different shapes in some embodiments of the invention.
- the lens 190 focuses the photons to the depletion region
- the reflector has a dispersing means 195 for dispersing photons into the depletion region and further onto reflectors 180 , 181 .
- some sections of the Sun incident surface of the first solar cell 200 are arranged with a photon reflector 180 , 181 in accordance with the invention, especially those sections that no longer have many incident photons on them, as the incident photons have been focused to other sections of the first solar cell 200 .
- the reflectors 180 , 181 are typically for the whole solar band, but can also be specifically designed for ⁇ 2 photons.
- the reflector filter 110 is typically a Rugate filter in some embodiments but can be any other band pass photon filter in accordance with the invention.
- the filter 110 splits the photons into two populations: the reflected photons ⁇ 2 and the photons passed through ⁇ 1 .
- the second solar cell 201 is arranged with a photon filter on the side opposite to the incident side of sunlight 111 and also on the sunlight incident side 150 .
- the photon filter 100 is arranged to focus the photons of other energies that did not get reflected by the reflector 110 , and the said photons enter through small apertures 140 from the photon filter 100 side opposite to the incident side of sunlight.
- these photons enter the second solar cell layer, they are again subject to the aforementioned procedure, but with a different band gap and cut-off wavelengths.
- the ⁇ 1 photons are interacting with the band gap of second solar cell layer 201 , i.e. at least those photons that do have the energy to do so.
- the photon filter of the invention conducts a spatiospectral modulation on the solar spectrum, i.e. it alters the photon signal/population in the spatial (focus on small apertures) space as well as frequency space (filtering) in FIG. 2A .
- the second solar cell 201 is arranged with a second photon filter 101 on the side opposite to the incident side of sunlight.
- the second photon filter 101 splits the ⁇ 1 photon population into two. Let us name the cut-off wavelength here as ⁇ x111 .
- the second photon filter 101 is arranged to reflect photons back into the second solar cell 201 with energies that are energies where the second solar cell 201 has high quantum efficiency. These photons are marked with ⁇ 4 in the FIGS. 2A , 2 B, 2 C, 2 D.
- the first photon filter 100 is also arranged to reflect photons back into the second solar cell 201 with energies that are energies where the second solar cell 201 has high quantum efficiency, with a photon reflector 150 that is on the side opposite to the incident side of sunlight in the first photon filter 100 in some embodiments.
- These photons are marked with ⁇ 5 in the FIG. 2A .
- the photon filters 100 , 101 are arranged to entrap photons into the second solar cell that are at energies where the second solar cell 201 has high quantum efficiency.
- the second photon filter 101 is arranged to be transparent to photons that are not at energies where the second solar cell 201 has a high quantum efficiency, and these said transparent photons are arranged to enter a third solar cell 202 (not shown here), or exit the tandem solar cell system.
- a method of producing the aforementioned solar cell is also in accordance with the invention.
- at least one of the solar cell layers and/or photon filters is produced, manufactured and/or grown by lithography, molecular beam epitaxy (MBE) metalorganic vapour phase epitaxy (MOVPE), Czochralski (CZ) silicon crystal growth method, Edge-define film-fed growth (EFG) method, Float-zone silicon crystal growth method, Ingot growth method and/or Liquid phase epitaxy, (LPE).
- MBE molecular beam epitaxy
- MOVPE metalorganic vapour phase epitaxy
- CZ Czochralski
- Optical filter components; reflector elements 110 , 111 , 130 , 131 , 150 , 151 and/or focusing elements 120 , 121 , 140 , 141 can made of any of the following in accordance with the invention: reflective foil, such as metal foil, ultraviolet/visible/infra red mirror such as aluminium or gold mirror or said mirror or mirror foil with opaque, vacuum-deposited metallic coatings on low-expansion glass substrates, Aluminum/MgF2-mirror, Aluminum/SiO-mirror, Aluminum/dielectric-mirror, Protected Gold-mirror and/or normal mirror and/or any Rugate filter material and/or dielectric stack material and/or any band pass, short pass, long pass and/or notch filter.
- reflective foil such as metal foil, ultraviolet/visible/infra red mirror such as aluminium or gold mirror or said mirror or mirror foil with opaque, vacuum-deposited metallic coatings on low-expansion glass substrates, Aluminum/MgF2-mirror, Aluminum/SiO-
- the choice of the reflective and/or focusing material should be based on the reflectance-wavelength function of the material amongst other practical things such as cost and availability in some embodiments of the invention. In some embodiments it is preferred for the reflection and/or focusing to be efficient up to Far-IR, or in any case to the wavelength that equates with the smallest band gap in the solar cell layers.
- embodiment 20 can be freely combined and permuted with embodiments 10, 21, 22, 23, 30, 40 and/or 50 earlier and later in the text in accordance with the invention.
- FIG. 2B presents an alternative inventive photon filter arrangement for a tandem solar cell of the invention.
- Sunlight enters the first solar cell 200 of the tandem solar cell as explained before.
- the filter 110 is preferably adjusted to reflect high energy and short wavelength ⁇ 2 photons back to the solar cell 200 , and the first solar cell 200 is typically arranged with a high energy band gap and a response or quantum efficiency (QE) function that has a high efficiency at these higher energies.
- QE quantum efficiency
- the filter 100 is arranged to pass lower energy photons with longer wavelengths ⁇ 1 through. These ⁇ 1 photons are arranged to enter the second solar cell 201 , which has a response and a band gap that has higher quantum efficiency at the energies of these photons.
- the second solar cell 201 needs a photon filter 170 at the sunlight incident side, and the ⁇ 1 photons need to be arranged to pass through it to ensure photon entrapment in second solar cell 201 .
- an antireflective coating 160 is arranged between the two filters 110 and 170 .
- the filter 170 is arranged to reflect ⁇ 1 photons on the side incident to the second solar cell 201 back to the second solar cell 201 , so these photons need to be carefully inserted through the filter 170 to the second solar cell 201 , so that the filter 170 does not reflect them back to the first solar cell 200 , because ⁇ 1 photons are not wanted there, as they cannot convert to current in accordance with the invention.
- the antireflective coating 160 is typically a quarter wavelength layer with the refraction index of ⁇ (n 110 n 170 ), where n 110 is the refractive index of filter 110 , and n 170 is the refractive index of filter 170 .
- the antireflective coating typically has a thickness of (1 ⁇ 4)* ⁇ 1 , or similar. It should be noted that as the optimum thickness varies as a function of the wavelength, the optimum thickness for the antireflective coating may depart quite significantly from ⁇ 1 in some embodiments of the invention, depending on the secondary photon spectrum that emerges through the photon filter 110 .
- the antireflective coating 160 contains several layers of the aforementioned quarter wavelength layer, typically based on different wavelengths to increase the spectral range of the antireflective coating 160 .
- the refractive index may deviate from ⁇ (n 110 n 170 ), preferably to accommodate other design requirements in accordance with the invention.
- the antireflective coating 160 is designed to achieve a smooth transition of ⁇ 1 photons into the second solar cell layer 201 , and the fact that there is no antireflective coating between filter 170 and the second solar cell layer 201 is designed to prevent any photons now in the second solar cell layer 201 from returning back through the filter 170 towards the first solar cell layer 200 .
- the refractive indices of the materials are adjusted so that there is total internal reflection between filter 170 and second solar cell layer 201 .
- the filter 170 will have a low index of refraction, whereas the second solar cell layer 201 should have a high index of refraction.
- the filter 170 has a low index of refraction in comparison to second solar cell layer 201 , ⁇ for a photon going from filter 170 to second solar cell layer 201 arcsin(high) ⁇ not defined, no total internal reflection, even at grazing angles, the photons will pass through. Coming back however, arcsin(low) ⁇ total internal reflection will occur even for nearly perpendicularly incident returning photons.
- the refractive indices of the materials may be used to realise preferred distribution of photons in accordance with the invention.
- the second solar cell 201 has a high relative refractive index at energies below the energy band gap of the first solar cell 200 , and a low relative refractive index at energies higher than the energy band gap of the first solar cell 200 .
- refractive indices the high energy photons more suitable for the band gap of the first solar cell layer 200 get reflected at the interface of the second solar cell 201 back into the first solar cell 200 .
- the lower energy photons more suitable for the band gap of the second solar cell 201 will now transmit through the interface. Even further, the photons that were transmitted into the second solar cell 201 are typically reflected back from a reflector at the bottom of the second solar cell 201 . When these photons return back to the interface, the likelihood of total internal reflection is very high, because for the returning reflected photon, the interface has a high relative n from and a low relative n to . Consequently, the returning photons are trapped into the second solar cell layer 201 , unless they can pass onto a further third solar cell layer or exit through a similar refractive index interface or some of the other unidirectional filter options mentioned before.
- the disruptive invention that indeed in a tandem solar cell the refractive index wavelength function of a solar cell material should peak in the proximity of the band gap of the said solar cell material, and even more preferably have a low refractive index at energies far away from its band gap. Consequently a solar cell layer in a tandem solar cell should have a QE (quantum efficiency) vs. wavelength function that peaks with the refractive index vs. wavelength function, i.e. the high refractive index would ideally be associated with a high QE in a solar cell layer of the tandem solar cell of the invention.
- QE quantum efficiency
- a tandem solar cell with four solar cell layers may have two interfaces that are realised by choosing individual solar cell layers with appropriate refractive indices, and one interface that has some of the more elaborate unidirectional photon filter arrangement, such as spatiospectral modulation, antireflective coating and/or coarsened interface as explained before.
- a single filter layer between the solar cell layers as is shown in FIG. 2C .
- the ⁇ 1 photons then enter the second solar cell 201 through the filter 170 and ⁇ 4 photons are arranged to be entrapped into the second solar cell 201 , whereas ⁇ 3 photons are arranged to pass through the filter 111 and out of the second solar cell 201 .
- the second solar cell 201 is typically arranged to have high quantum efficiency at energies of photons ⁇ 4 , which are typically the high energy photons of the photon population ⁇ 1 .
- the photons ⁇ 3 have a lower energy and longer wavelength at which wavelength the second solar cell 201 is no longer efficient.
- ⁇ 3 photons are therefore arranged to exit the second solar cell, and possibly enter a third solar cell (not shown), or simply exit the tandem solar cell.
- ⁇ 3 photons typically transmit through the filter 111 in accordance with the invention and reach an antireflective interface 165 , because the ⁇ 3 photons are not wanted in the second solar cell as explained before.
- the antireflective interface 165 has been achieved by coarsening the interface between the two photon filters 111 and 171 .
- the coarsened interface 165 is arranged to prevent total internal reflection and reflection in general by the photon filter 171 . This is because in a coarsened interface the photons cannot escape the interface with a single reflection at an angle of total internal reflection, instead they will meet the photon filter 171 at an incidence angle somewhere in the coarse interface that will typically allow transmission.
- the antireflective coating 160 and/or antireflective interface 165 of FIG. 2B can be used to substitute the spatiospectrally modulating optical filter arrangements ( 120 , 130 , 140 ) of FIG. 2A in some embodiments of the invention.
- tandem solar cell of the invention may feature any number of solar cells with any number of filter arrangements and any type of filter arrangements which may include antireflective coating 160 , antireflective interface 165 , suitably selected refractive indices n to , n from and/or spatiospectral modulation in any combination and/or permutation in accordance with the invention.
- any interface can be coarsened in accordance with the invention to increase antireflection properties, for example the interface arranged to filter photons based on selected refractive indices as explained before can also be coarsened in accordance with the invention.
- the tandem solar cell has the depletion region interface in parallel to incident sunlight in FIGS. 2A , 2 B, 2 C and 2 D. Quite clearly the depletion region interface may also be perpendicular or in fact in any angle to the incident sunlight, as the main point is to get the photons into the photoelectrically active first solar cell 200 in accordance with the invention.
- the depletion region interface between the p-region and the n-region is arranged perpendicular to incident sunlight, but any positioning is possible in accordance with the invention.
- the electrical contacts that collect the generated photocurrent are shown in FIG. 2B as front contact 250 and rear contact 251 , but clearly they can be positioned to accommodate different configurations in accordance with the invention.
- the electrical contacts are typically hidden to minimise shading losses, for example by Angled Buried Contacts, as is shown for the front contact 250 , where the contact is actually at an angle buried under the surface, and thereby does not cause a shade on the incident radiation. Even the buried contact should be made reflective to photons in accordance with the invention.
- any optical concentrators, lenses or the like can be used to focus sunlight, or light from other sources, to the solar cell of the invention, and in particular to the incidence side of the first solar cell 200 in accordance with the invention of which just one example is shown in FIG. 2C .
- embodiment 21 can be freely combined and permuted with embodiments 10, 20, 22, 23, 30, 40 and/or 50 earlier and later in the text in accordance with the invention.
- FIG. 2C shows the embodiment 22 with the focusing means 190 and the entrapping reflectors 180 , 181 on the sunlight incident side.
- the photons are typically focused to the depletion region, and there may be a dispersing reflector 195 at the bottom of the first solar cell layer 200 , to ensure the reflected photons do not reflect out of the solar cell through the aperture they came in from.
- FIG. 2C also shows a single unidirectional filter 100 between the said solar cell layers 200 , 201 , which is a useful embodiment of the invention.
- embodiment 22 can be freely combined and permuted with embodiments 10, 21, 23, 30, 40 and/or 50 earlier and later in the text in accordance with the invention.
- FIG. 2D shows the simplest embodiment of the invention 23 , which however places the hardest criteria on the materials chosen.
- the filter 100 is realised purely by the interface 100 between the two solar cell layers 200 , 201 , which have their band gaps and refractive indices selected as describer earlier.
- embodiment 23 can be freely combined and permuted with embodiments 10, 21, 22, 30, 40 and/or 50 earlier and later in the text in accordance with the invention.
- FIG. 3 demonstrates an embodiment of the invention where there are four solar cell layers 200 , 201 , 202 , and 203 and three or four photon filters 100 , 101 , 102 and 103 .
- QE quantum efficiency
- the QE-wavelength profile of a solar cell layer is of significance to how many solar cell layers are implemented in the design.
- the narrower the band is around the optimum energy the higher the quantum efficiency.
- the tandem solar cell comprises several solar cell layers 200 , 201 , 202 , 203 , and in between two solar cell layers there is a photon filter, 100 , 101 , 102 .
- the photon filters are tuned so, that they will trap only those photons that are at an energy where the solar cell layer is working at a good quantum efficiency (QE), ideally close to 1.
- QE quantum efficiency
- the rest of the photons are simply passed to the next layer by the photon filter.
- the solar cell layers 200 , 201 , 202 are preferably very thin, or otherwise designed so that there is minimal interaction between the solar cell and the photon population at energies where the quantum efficiency is NOT that good, i.e. far from unity.
- the last solar cell layer i.e. 203 in this case, can be thick. It may also have a reflective mirror on the side opposite to the incident side of sunlight, or a photon filter 103 that may be designed to let heat photons out, but trap those photons with photovoltaic band gap absorption potential, i.e. energy enough to be absorbed.
- the first solar cell layer 200 is a GaN layer with a band gap of 3.4 eV (electron volt).
- the second solar cell layer 201 is an InGaP layer with a band gap of 1.93 eV in some embodiments of the invention.
- the third solar cell layer 202 is a polycrystalline silicon layer, with a band gap at 1.1 eV in some embodiments of the invention.
- the last solar cell layer 203 is an InSb layer with a band gap of 0.17 eV. What could be the cut-off wavelengths ⁇ x s ? In the layer 200 photons with less than 3.4 eV are useless, as they cannot be absorbed into photocurrent.
- the third polymorphic silicon solar cell layer 202 at 1.1 eV would require 1128 nm for the ⁇ x102 , i.e. a red-IR mirror.
- the photons longer than 1128 nm or similar threshold would be passed to the fourth layer 203 with an InSb band gap of 0.17 eV ⁇ 7301 nm. In some embodiments of the invention this last layer 203 would be made thick, because all the remaining photons should interact in this layer 203 .
- each solar cell layer is a reasonable multiplier of the wavelength that equates with the band gap, to ensure particle nature of the photons in the solar cell layers.
- the multiplier were 10
- solar cell layers 200 , 201 , 202 and 203 would have thicknesses of 3650 nm, 6430 nm, 11280 nm and 73010 nm respectively.
- the one quarter wavelength antireflective coatings would have thicknesses of roughly 91.25 nm, 160.75 nm, 282 nm, 1825 nm, respectively in preferred embodiments of the invention.
- the structure would be about one millimetre thick in accordance with this embodiment of the invention.
- these parameters can be tuned in accordance with the invention.
- the four layer tandem solar cell is a preferable embodiment, because it samples both the solar spectrum and the resultant secondary spectrum (emerging spectrum after the first solar cell layer), tertiary spectrum (emerging spectrum after the second solar cell layer) and quaternary spectrum (emerging spectrum after the third solar cell layer) so well.
- embodiment 30 can be freely combined and permuted with embodiments 10, 20, 21, 22, 23, 40 and/or 50 earlier and later in the text in accordance with the invention.
- FIG. 4 displays an exemplary embodiment of the invention in energy space—i.e. spectral space.
- the incident solar spectrum 300 runs from 200 nm in the UV to roughly 2400 nm, the spectrum 300 is a AM 1.5 G 1000 W/m 2 solar spectrum typically encountered on Earth.
- the first solar cell layer 200 has a solar cell response that is slightly lower in energy than the GaN and slightly higher in energy than the InGaP. It has a reasonably high QE in between 365-645 nm, i.e. blue light, as shown in the QE plot that is superposed underneath the spectrum 300 .
- the photocurrent power spectrum that shows spectral distribution of collected photocurrent power spectrum 400 and therefore energy and power generated by the first solar cell layer 200 is quite similar in shape to the response of the first solar cell layer 200 .
- the photon spectrum 401 will be quite modified when it reaches the first photon filter 100 .
- the photon filter 100 will spatiospectrally modulate the photon spectrum 401 in some embodiments of the invention, or use another unidirectional filter as explained before.
- the photon filter 100 will preferably reflect the ⁇ 2 photons with higher energies and shorter wavelengths, i.e.
- the photons with a shorter wavelength of ⁇ x100 that should correspond to the energy band gap of the solar cell layer 200 in accordance with the invention will be passed to the second solar cell layer 201 by the focusing means or other spatial modulation means, resulting into the spatial component of the modulation, or by another unidirectional filter, and this layer will again have a different cut-off frequency ⁇ x101 in accordance with the invention in some embodiments.
- the solar cell response 201 converts the photocurrent from this photon population.
- the photon filter 101 will reflect ⁇ 4 photons back to the solar cell layer 201 , and the reflector that does this resides on the side facing in the same direction as the sunlight incident side.
- the photon filter 100 will have a reflector 150 around the small apertures 140 that released the ⁇ 1 photons into the second layer 201 , or another reflecting filter 170 or interface on the solar incident side facing the second solar cell layer as explained before. This reflector will reflect ⁇ 5 photons back again from the side opposite to the sunlight incident side of photon filter 100 , resulting in photon entrapment between photon filters 100 , 101 , for photons that can interact with the band gap of the second solar cell layer.
- the photon filters would be unidirectional, it is probable under practical conditions that they cannot achieve a completely ideal unidirectional filtration result: with spatiospectral modulation small photon leakage will occur through the improbable incidence of returning photons to apertures, in refractive index structures some stray angle photons may remain, at which incidence angle a small group of photons might be able to violate unidirectionality even when they are at an energy where they should be entrapped to the solar cell layer that they are currently at.
- the remaining low energy photons ⁇ 3 are passed onto a third solar cell layer 202 in accordance with the invention in some embodiments, or they are simply released out of the tandem solar cell or left in the lattice in some embodiments of the invention.
- embodiment 40 can be freely combined and permuted with embodiments 10, 20, 21, 22, 23, 30 and/or 50 earlier and later in the text in accordance with the invention.
- FIG. 5 shows an embodiment of the operation of the inventive method and device as a flow diagram 50 .
- the photons have entered the first solar cell layer 200 .
- the photon population traverses through it, with some photons getting absorbed and exciting photocurrent in this solar cell layer.
- the photons After the photons have traversed through the first solar cell layer 200 that is preferably quite thin, they reach the photon filter 100 in phase 600 where the photons with wavelength shorter than ⁇ X100 are reflected back to the first solar cell layer 200 .
- the incident and the reflected photons produce the photopower of solar cell 200 .
- the photons with wavelength longer than ⁇ X100 are focused by the at least one lens 120 .
- the lenses can be of any shape and any material in accordance with the invention, but they can also be replaced by any other focusing means, or in fact by any means capable of splitting the photon populations in the desired way, for example by a unidirectional filter.
- the whole point about focusing the photons passed through is to perform the spatial aspect of the modulation in order to achieve enough reflective surface to the other wall of the photon filter 100 facing the second solar cell layer 201 . It is in accordance with the invention to deploy other equivalent means to focusing and spatial modulation in some embodiments.
- photons with wavelength longer than ⁇ X100 may pass to an antireflective coating or coarse interface as explained in FIG. 2B in some embodiments, or they may pass to an interface with refractive indices adjusted to ensure photon selection and entrapment as shown in FIG. 2D and explained before or to a unidirectional filter 100 as shown in FIG. 2C and explained before.
- phase 620 photons with wavelength longer than ⁇ X100 enter the solar cell 201 through at least one aperture 140 , which are typically very small in order to maximise the reflective area 150 of the other wall of the photon filter 100 facing the second solar cell layer 201 . Some of these incident photons now generate photopower from second solar cell layer 201 .
- phase 630 the photons with wavelength shorter than ⁇ X101 are reflected by the photon filter 101 . These photons are thus simply reflected back to the second solar cell layer 201 . Some of these reflected photons are absorbed and produce photopower of solar cell 201 .
- the reflector 150 of photon filter 100 is designed to simply reflect back all the photons or as many photons as possible on as wide a band as possible in accordance with the invention.
- phase 630 there will now be a photon population bouncing back and forth between the photon filters 100 , 101 in accordance with the invention. This photon entrapment gives several opportunities for the photons to get absorbed into the second solar cell layer 201 .
- phase 640 the photons that no longer have a chance of being converted to photocurrent, are focused by the lens 121 or other focusing means. It makes sense to adjust the cut off ⁇ X101 so that it reflects back all those photons that do have a chance of getting absorbed in the second solar cell layer 201 , but naturally ⁇ X101 can be selected otherwise in accordance with the invention, based on other design criteria for example.
- phase 650 the photons with wavelength longer than ⁇ X101 enter the solar cell 202 preferably from small apertures 141 in the wall of the photon filter 101 facing the third solar cell layer 202 .
- the process repeats in the third solar cell layer 202 with the same aforementioned principle albeit at longer wavelengths to generate the photopower of the solar cell 202 .
- embodiment 50 can be freely combined and permuted with embodiments 10, 20, 21, 22, 23, 30 and/or 40 earlier in the text in accordance with the invention.
- the solar cells of the invention need not be necessarily square or flat, indeed they can be realised in any shape, for example spherical shape in some embodiments, as described in FI20070743 Thermodynamically shielded solar cell & counterparts or otherwise.
- the solar cell or tandem solar cell systems of the invention can be realised in any size, from nanometer scale structures to large structures. From power plant size installations to power solutions of very small portable devices, the solar cells and the photon filtration systems find use in many markets in accordance with the invention.
- the invention has been described here so that the highest band gap solar cell and the highest band pass filter is the first incident to the sunlight. It should be noted that the invention can also be implemented in the reverse order, i.e. having the smaller energy solar cell layers and filters first in some embodiments. Indeed the band gaps of the solar cell layers may be in any order in some embodiments of the invention, the main point is that these solar cell layers work with photons that are at an energy at which the solar cell layer has a good QE, and DO NOT work with photons that are at an energy where the QE is poor.
- the highest band gap material first and the conduction of the filtering and band gaps in an order of high-to-low when moving from the incident sunlight side to the back of the tandem solar cell is preferable in some embodiments of the invention, because this produces the smallest number of photoelectric absorptions per the first photoelectric unit of energy generated.
- the use of the bias voltage as described in FI20070264 is preferable in especially the lower solar cell layers in some embodiments of the invention to achieve photoelectric conversion at very low band gaps.
- the optical concentration and convective, conductive and/or radiative shielding solutions of FI20070743 can be implemented in a very useful way to ensure high photon fluxes in accordance with the invention in some embodiments.
- the software design method of FI20070801 can be used to design some of the tandem cells in accordance with the invention.
- Some of the cost reducing embodiments of EP 09154530.1, or other embodiments, can be combined with the embodiments of the present invention. Many useful embodiments can thus be derived from combining the embodiments of these five patent applications from the same inventor that are all directed to the same theme: providing a photoelectric solution to the global energy problem.
- the electrodes collecting photocurrent from the aforementioned solar cell layers may be arranged in any configuration in accordance with the invention.
- the position and/or angle of the p-n junction to the incident solar flux or artificial light may be arranged to any position and/or angle and the system of the invention can be implemented in any geometry.
- the aforementioned invention has a multitude of practical use scenarios.
- the solar cells of the invention can be installed to a power plant for power generation to the grid.
- the inventions can be installed on any building to provide electricity for air conditioning and household appliances, or the like in that building or elsewhere.
- the inventive solar cells can be installed on a vehicle, to power the vehicle motor electrically, charge the battery, or power electric appliances for the vehicle.
- the inventive solar cells have a reasonably high cost of design and manufacture at first, the most advantageous application is probably in the field of portable electronic devices. Laptop computers, mobile phones, electric shavers, epilators, electric toothbrushes, calculators, music players such as MP3 players (e.g.
- At least one solar cell layer of the tandem solar cell is chosen arranged so that it has a band gap and a spectral response that converts electricity efficiently from photons emitted by indoor lights, such as fluorescent lights, LEDs (light emitting diodes) or light bulbs.
- the solar cell layers of the invention can also be arranged to work well in both indoor and outdoor solar light, by choosing the solar cell layer materials with the appropriate spectral responses and band gaps in accordance with the invention.
- the solar cells of the invention can be camouflaged to aesthetically fit any product or building. Also, quite clearly the solar cells of the invention can be coupled with other power generation mechanism, such as kinetic power generation by piezoelectric crystals or the like to increase the battery time of the portable electronic device, or even to get rid of the need for a grid charger in some embodiments of the invention.
- other power generation mechanism such as kinetic power generation by piezoelectric crystals or the like to increase the battery time of the portable electronic device, or even to get rid of the need for a grid charger in some embodiments of the invention.
- a power system including both a solar cell arranged to generate power by photoelectric conversion (from sunlight and indoor lights) and a piezoelectric crystal arranged to generate power from its mechanical movement (for example by the person using and carrying the power system) is in itself an invention. It could be used to realise new devices with considerably longer battery times, or new portable devices even without the restriction of grid charging.
- the combination of a mechanical and photovoltaic power source is especially preferable because the photovoltaic power generation works when the portable device is exposed to light, and the piezoelectric and/or other mechanical power generation system based on e.g. (pendulum and/or springs found in watches) works typically when the portable electronic device is concealed in the pocket of the user, i.e. being moved in the dark.
- the inventive system is charging the portable electronic device nearly all the time.
- the combined power system of a mechanical power generator and a solar cell will feature a solar cell with a band gap at an energy associated with photons emitted from fluorescent lights or other indoor lightning systems, typically at a wavelength of 400-500 nm.
- the inventive tandem solar cell would suit the above mentioned power solution for a portable device perfectly, as it can cope with a variety of incoming light spectra, such as indoor light spectra in some embodiments.
- the invention has been explained above with reference to the aforementioned embodiments and several commercial and industrial advantages have been demonstrated.
- the methods and arrangements of the invention allow the construction of a solar cell where a high number of very thin solar cell layers each work at nearly 100% quantum efficiency, because the inventive photon filters restrict the photon population to the most efficient bands of the solar cell layers, and therefore a practically ideal solar cell delivering power close to the solar constant 1.37 kW/m 2 in space and roughly 1 kW/m 2 on Earth is made possible by the invention.
Abstract
Description
- This application is a new division of co-pending application Ser. No. 12/791,188 filed on Jun. 1, 2010, which claims priority to European Application No. 09162378.5 filed on Jun. 10, 2009. The entire contents of each of the above-identified applications are hereby incorporated by reference.
- The invention relates to methods and means for improving the power generated and efficiency of solar cells.
- Photovoltaic solar cells are the most recently discovered new method of producing energy, dating from the 1950's Soviet and US satellite power systems. Photovoltaic solar cells produce electricity with very low environmental impact, and are because of this desired by the public. The problem with present photovoltaic solar cells is that they do not produce enough energy for their cost and/or surface area to make them economically viable.
- Therefore many technologies have been suggested to improve the efficiency of solar cells. EP 1724841 A1 describes a multilayer solar cell, wherein plural solar cell modules are incorporated and integrally laminated, so that different sensitivity wavelength bands are so that the shorter the centre wavelength in the sensitivity wavelength band is, the more near the module is located to the incidental side of sunlight. This document is cited here as reference. It is currently not known, which are all the factors that cause a shortcoming in the efficiency of the multilayer solar cell. However, based on the studies of the applicant, the general tandem solar cell is hampered the most by the photon-phonon processes that take place outside the band of maximum quantum efficiency of the solar cell, i.e. this is where in frequency space the cell generates a lot of heat. Individual factors pertaining to the disadvantages are also listed in the
columns 1 and 2 of U.S. Pat. No. 6,689,949, which is cited here as reference. - U.S. Pat. No. 6,689,949 discloses a photovoltaic reflective cavity with several solar cells in the cavity. The solar cells inside the cavity are under filters that filter the light so that the incoming photon flux is more appropriate for the quantum efficiency of the solar cell, i.e. more appropriate for its response or detector response.
- NASA and JPL (Jet Propulsion Laboratory) have also proposed an alternative technique, called “Rainbow” where beam splitters and concentrators are used to split the solar spectrum into different bands and focus the different bands of light to different discrete solar cells that can handle the splitted and focused spectrum the best. This scheme requires a very complicated optical arrangement, and has not materialised to anything practical so far.
- U.S. Pat. No. 5,021,100 discloses a tandem solar cell that has a reflective film between the first and the second solar cell (incident cell on sunlight side in this publication), where the reflective film is supposed to reflect high energy photons to the second solar cell and let low energy photons to the first solar cell (behind the second solar cell in this publication). This document is cited here as reference. U.S. Pat. No. 5,021,100 has a serious problem in that the reflective film is a bidirectional, i.e. any reflected photons in the first solar cell will leak back to the second solar cell through the reflective film, and cause phonons and heat, as these photons cannot get absorbed in the second solar cell.
- The invention under study is directed towards a system and a method for effectively solving the problems of the prior art and realising a more powerful solar cell.
- A more particular object of the invention is to present the aforementioned solar cell system, which has high capital cost in design, but ultimately a low production cost with large economies of scale. In order to achieve this, the invention introduces a tandem solar cell where each solar cell layer works with photons at energies where that solar cell layer has the highest quantum efficiency.
- One aspect of the invention involves a solar cell with a photon reflector on the side opposite to the incident side of sunlight. The reflector is arranged to reflect photons with wavelengths suitable to the quantum efficiency function of the solar cell back to the solar cell.
- In one aspect of the invention, there is a tandem solar cell with two solar cell layers. There is a photon filter between the two solar cells. The solar cell that is incident to sunlight is exposed, and this solar cell layer typically has the band gap that is of the higher energy. The solar photons enter this first solar cell, and the higher energy part of the solar spectrum is likely to get converted to photocurrent. Some high energy photons do not interact with the semiconductor, and just pass through or get dissociated into photons and phonons of lesser energy by the photon-phonon process. Those photons that are still of high enough energy to get converted to photocurrent in the first layer, i.e. where the energy of the photon (E) E>Ebg1 is greater than the band gap (Ebg1) of first solar cell, are reflected back into the first solar cell layer by the photon filter. These photons will get a second chance to get converted into photocurrent. Preferably the first solar cell layer is very thin and very pure, so that there is less time and space for non-absorbing processes, i.e. heat conversion by photons that do not match the band gap. The photons with energy E<Ebg1 band gap are now passed through by the filter to the second solar cell layer that has a lower band gap Ebg2. A large portion of these photons can now interact with the second band gap. The photon filter will collect the lower energy photons and then focus the lower energy photons into the second solar cell layers through very small apertures on the other side of the filter. These small apertures are permeable to photons. The rest of the area on the other side of the photon filter is also covered with a reflector material. This is because on the bottom of the second solar cell layer there is also a reflector that reflects photons capable of converting into photocurrent in the second solar cell layer back to the second solar cell layer. Some photons that get reflected from this reflector are still unabsorbed after having passed through the second solar cell layer the second time on their return journey. These photons are sent back by the reflector material surrounding the small apertures just said. The reflectors on the opposite side of the sunlight incident side of the photon filter and at the bottom of the tandem solar cell system trap the photons capable of producing photocurrent in the second solar cell layer, i.e. photons typically of E>Ebg2. These photons bounce back and forth until they get absorbed or dissociate into photons of energy less than Ebg2.
- The entrapment of the photons into the second solar cell results from the first photon filter being unidirectional. I.e. apart from the very small possibility of leaked photons back through the small apertures, the majority of the photon population is bouncing between two reflectors in a second solar cell that has a band gap favourable for photoelectric absorption and current generation. The photon filter described above relies on a technique developed by the inventor, and named by the inventor, as spatiospectral modulation.
- A unidirectional photon filter may also be realised in the above example by two reflective photon filters with an antireflective coating and/or coarsening between them in accordance with the invention. Also, the materials of the solar cells and photon filters may be selected so that the unidirectional filtration of photons is achieved based on the refractive indices of the materials in accordance with the invention. These photon filters in contrast suffer some losses in ideal unidirectionality in the form of leaking photons from stray angles.
- In one aspect of an inventive embodiment the tandem solar cell comprises several solar cell layers, and in between two layers there is a photon filter. The photon filters are tuned so, that they will trap only those photons that are at an energy where the solar cell layer is working at a good quantum efficiency (QE), ideally close to 1. The rest of the photons are simply passed to the next layer by the photon filter. There can be indeed many layers that are preferably very thin, or otherwise designed so that there is minimal interaction between the solar cell and the photon population at energies where the quantum efficiency is NOT that good, i.e. far from unity.
- By quantum efficiency we mean its general meaning as defined in Larousse Dictionary of Science and Technology: quantum efficiency (Phys): “Number of electrons released in a photocell per photon of incident radiation of specified wavelength”. Inventor further points out that this parameter can be normalised to yield the typical 100-0% scale when necessary. The quantum efficiency is an extremely good measure of how good the photocell is in converting photons into electricity. The detector response or response is the quantum efficiency as a function of wavelength, i.e. it tells how the photocell responds to incoming photons at different energies.
- In terms of the solar cell in this application high quantum efficiency (QE) is a QE that is higher than the QE's of other alternative solar cell layers at the same photon energy. In practical terms the band of spectrum that might be worth holding onto in a particular solar cell layer is when the QE exceeds 10%, i.e. the overall QE of present wholesale market solar cells. However, roughly 30-50% should be regarded as the threshold QE, if the tandem solar cell is going to economically replace oil and gas in the current market conditions. Photons at energies where the solar cell layer has a QE less than 30-50% should be moved to other solar cell layers that have higher QEs, as will be described later in the application. As for portable electronic devices, 30-50% could similarly be regarded as a good QE, but this should depend on device requirements in accordance with the invention. For example, a Nokia E71 mobile phone has an area of 72 cm2 and a battery of 1.5 Ah, with a voltage of 3.7 V. If the inventive solar cell achieves an efficiency of 50% and covers the surface of the phone with an area of 72 cm2, assuming a solar flux of 1000 W/m2 this will mean that the battery will fully charge in approximately 1.5 hours of exposure according to the calculations of the applicant. Quite clearly, 1.5 hours of exposure over the battery life of roughly a week is beginning to be at the reach of the market, if it provides the added benefit of not having to use an electric grid charger most of the time.
- Some or all of the aforementioned advantages of the invention are accrued in one embodiment where there can be many, for example a hundred solar cell layers of different band gaps separated by reflecting photon filters as just described. Typically a semiconductor junction can maintain high quantum efficiency only at a very narrow band. The further the departure from the optimum energy, the smaller the QE gets. In one embodiment of the invention there are a hundred solar cell layers that have high QE's at bands that are 10-20 nm wide in the wavelength space. By using these cells it is possible to sample the entire solar spectrum from 150 nm (UV) to 1500 nm (IR) with semiconductor junctions that operate at very high quantum efficiency. The photon filters are set so that the first solar cell layer will have photons of energy 150-160 nm in wavelength space, the second 160-170 nm, the third 170-190 nm, and so on. Naturally the first solar cell layer only needs to be efficient in the 150 nm-160 nm band, which is easier to achieve. In addition, it should disturb the photons with wavelengths longer than 160 nm as minimally as possible. These photons will pass to the layers that follow with each being trapped as explained above into their own 10-20 nm bands with a solar cell layer that is at its best efficiency at that band.
- A tandem solar cell in accordance with the invention is defined by the subject matter claimed and comprises at least two layers of solar cells, the first and the second layer and is characterised in that,
-
- a first photon filter is arranged in between the first solar cell layer and the second solar cell layer,
- the solar cell is arranged with the photon filter on the side opposite to the incident side of sunlight,
- the photon filter is arranged to reflect photons of certain energy back into the first solar cell,
- the photon filter is arranged to be transparent to photons of other energies not arranged to be reflected, and these photons are arranged to enter the second solar cell.
- The above photon filter is also arranged to reflect back the returning photons from the second solar cell, and prevent them from entering the first solar cell, thereby realising unidirectionality of the photon filter in accordance with the invention. In some embodiments there is a reflector at the bottom of the second solar cell to realise entrapment of photons of suitable energy to the second solar cell layer.
- A method of producing the aforementioned tandem solar cell is in accordance with the invention.
- A photon filter is arranged to reflect photons with wavelengths shorter than λx from its first side and arranged to be transparent to photons of wavelengths longer than λx by focussing the said longer wavelength photons out of small area apertures on the other side opposite to the first side of the photon filter and the other side of the photon filter is arranged to reflect at least some of the said photons of wavelength longer than λx.
- A tandem solar cell, comprises at least two solar cell layers is characterised in that the said tandem solar cell is arranged to transport an incoming photon to the solar cell layer that has the highest quantum efficiency (QE) at the energy of the said incoming photon in comparison to the other said solar cell layers in the tandem solar cell.
- A tandem solar cell in accordance with the invention comprises at least two layers of solar cells, the first and the second layer and is characterised in that,
-
- a first photon filter is arranged in between the first solar cell layer and the second solar cell layer,
- an antireflection coating layer is arranged between the first photon filter and the second solar cell layer,
- a second photon filter is arranged between the said antireflection coating and the second solar cell layer.
- A tandem solar cell in accordance with the invention comprises at least two layers of solar cells, the first solar cell layer and the second solar cell layer and is characterised in that, at least one unidirectional photon filter is arranged between the first and the second solar cell layers. “unidirectional photon filter” in the context of this application means a photon filter which is arranged to reflect a group of photons, and arranged to pass a group of photons through one way, but also arranged to NOT allow passed photons to return back again through the said photon filter. While such an ideal photon filter is difficult if not impossible to produce in real physical life, the invention presents four unidirectional photon filters, the spatiospectrally modulating filter, the antireflective coating filter, the coarse antireflective filter and/or the refractive index filter. These filters are construed as unidirectional in this application, while acknowledging the practical bounds of these filters filtering photons unidirectionally.
- A tandem solar cell in accordance with the invention comprises at least two layers of solar cells, the first solar cell layer with a band gap energy of Ebg and the second solar cell layer and is characterised in that, the second solar cell has a lower refractive index than the first solar cell layer at photon energies equal or higher than Ebg.
- In the above tandem solar cell the second solar cell typically also has a higher refractive index than the first solar cell layer at photon energies lower than Ebg in accordance with the invention, and a band gap lower than Ebg.
- A tandem solar cell in accordance with the invention comprises at least two layers of solar cells, the first solar cell layer and the second solar cell layer and is characterised in that, at least one said solar cell layer is arranged to have its quantum efficiency (QE) vs. wavelength and its refractive index vs. wavelength functions to reach peak and/or high values at same wavelengths.
- A portable electronic device in accordance with the invention comprises at least one solar cell and is characterised in that, said portable electronic device features at least one piezoelectric crystal and/or at least one mechanical means arranged to generate electricity from mechanical movement of said portable electronic device. The said solar cell is preferably a tandem solar cell, most preferably the tandem solar cell described in this application, but in some embodiments it may also be a conventional solar cell.
- In addition and with reference to the aforementioned advantage accruing embodiments, the best mode of the invention at present is considered to be a double or triple junction tandem solar cell that has one or two photon filters of the invention in between the solar cell layers, respectively. This tandem solar cell is used to power a self charging mobile phone, which may have a mechanical/kinetic electricity generator such as piezoelectric crystals or a pendulum/spring system found in e.g. watches as a backup for charging at times when the mobile phone is concealed from light, e.g. in the pocket of the user.
- In the following the invention will be described in greater detail with reference to exemplary embodiments in accordance with the accompanying drawings, in which
-
FIG. 1 demonstrates an embodiment of thephoton filter 10 as a block diagram. -
FIG. 2 demonstrates an embodiment of an inventive tandem solar cell with two solar cell layers as a block diagram 20. -
FIG. 2B demonstrates an embodiment of an inventive tandem solar cell with two solar cell layers with alternative unidirectional photon filters as a block diagram 21. -
FIG. 2C demonstrates an embodiment of an inventive tandem solar cell with two solar cell layers with alternative unidirectional photon filters as a block diagram 22 and a focusing means on the sunlight incident side. -
FIG. 2D demonstrates an embodiment of an inventive tandem solar cell with two solar cell layers with alternative photon filtration realised by the selection of refractive indices for solar cell materials, as a block diagram 23. -
FIG. 3 demonstrates anembodiment 30 of an inventive tandem solar cell with four solar cell layers as a block diagram 30. -
FIG. 4 demonstrates anembodiment 40 of the operation of the inventive tandem solar cell in terms of spectra, i.e. in the energy-wavelength space. -
FIG. 5 demonstrates anembodiment 50 of the operation of the inventive tandem solar cell as a flow diagram. - Some of the embodiments are described in the dependent claims.
-
FIG. 1 demonstrates an exemplary embodiment of thephoton filter 100 in isolation that is to be placed between two solar cell layers in a tandem solar cell. The incident sunlight side is assumed up in this figure. Photons with λ2 have higher energy than photons with λ1 i.e. λ2<λ1 in some embodiments, but it is also possible that thefilter 100 is configured in reverse, i.e. it reflects low E photons whilst letting high E photons pass in accordance with the invention. Thephoton filter 100 has a reflectingcover 110 on the sun incident side. The reflectingcover 110 may be a Rugate filter, or any other optical band pass filter in accordance with the invention. Underneath the reflecting cover are at least one focusing means for the photons that are not reflected, i.e. the photons that pass through the reflectingcover 110. These focusing means that are typically lenses of any shape, can be and are shown circular in the figure, focus the photon population into a narrowinghorn 130. This horn may be covered with reflecting material from the inside so that the photons that pass through it are directed out of at least onesmall aperture 140. In some embodiments there may be no horn, but still in these embodiments the photons are focused to a small spot when they exit thefilter 100. On the opposite side to incident sunlight most of the area is occupied by anotherphoton reflector 150. The small apertures are embedded into thereflector 150 and occupy only a fraction of the area of the other side of thephoton filter 100. Thereflector 150 is designed to reflect back the photons that entered the solar cell underneath from the at least oneaperture 140, but did not interact with the solar cell layer, and got instead reflected by another filter on the other side of the second solar cell layer. In some embodiments the ratio of the area ofreflector 150 toapertures 140 is made as big as possible in accordance with the invention. This is because the smaller the area of the apertures is in comparison toreflector 150, the smaller the probability for a reflecting photon to leak back to the firstsolar cell 200, and thereby violate unidirectionality of the filter. - The effect of the spatial modulation that allows the reflection by the
reflector 150 might be realised by other means besides focusing the entry into small apertures in some embodiments. For example a unidirectionally transparent filter could be used in some embodiments to replace the focusing means 120 andapertures 140 in accordance with the invention. In this embodiment it is important that the transparency is indeed unidirectional, thefilter 100 must not let those photons filtered through to the next layer to return to thefirst layer 200 in accordance with the invention. - The
filter - While the solar cell layers can be only a few nanometers thick in some embodiments of the invention, it is also possible that the photon filter is very thin, just a few nanometers in thickness in accordance with the invention.
- In some embodiments at least one
aperture 140 contains a diffracting or dispersing element that spreads the photons from the apertures effectively into the second solar cell. - The at least one focusing means 120,
horn 130,aperture 140,reflector 110, and/or 150 can be made from any material in accordance with the invention. Optical filter and/orreflector components elements outside face 150 for photons that have passed through the filter preventing them from returning, because of the angle and energy distribution of the photons after thefilter 100. However, when the photons are coming from the other side (110, i.e. those that were not reflected), these photons are aligned to penetrate throughface 150 from the inside. - It should be noted that the
embodiment 10 can be freely combined and permuted withembodiments -
FIGS. 2A , 2B, 2C, and 2D display embodiments of the invention where the two solar cell layers are combined with the photon filters of the invention to realise an inventive tandemsolar cell 20. The incident sunlight is at the top of the figures as shown. The firstsolar cell layer 200 or any subsequent solar cell layer mentioned in this application can be typically made of or may contain Si (Silicon), polycrystalline silicon, thin-film silicon, amorphous silicon, Ge (Germanium), GaAs (Gallium Arsenide), GaAlAs (Gallium Aluminum Arsenide), GaAlAs/GaAs, GaP (Gallium Phosphide), InGaAs (Indium Gallium Arsenic), InP (Indium phosphide), InGaAs/InP, GaAsP (Gallium Arsenic Phosphide) GaAsP/GaP, CdS (Cadmium Sulphide), CIS (Copper Indium Diselenide), CdTe (Cadmium Telluride), InGaP (Indium Gallium Phosphide) AlGaInP (Aluminium Gallium Indium Phosphide), InSb (Indium Antimonide), CIGS (Copper Indium/Gallium diselenide) and/or InGaN (Indium Gallium Nitride) in accordance with the invention. Likewise the firstsolar cell layer 200 or any subsequent solar cell layer mentioned in this application may feature any element or alloy combination, or any material capable of photoelectric effect described in the publications FI20070264, FI20070743, FI20070801, EP 09154530.1, EP 1724 841 A1, Josuke Nakata, “Multilayer Solar Cell”, U.S. Pat. No. 6,320,117, James P. Campbell et al., “Transparent solar cell and method of fabrication”, Solar Electricity, Thomas Markvart, 2nd Edition, ISBN 0-471-98852-9 and “An unexpected discovery could yield a full spectrum solar cell, Paul Preuss, Research News, Lawrence Berkeley National Laboratory, which publications are all incorporated into this application by reference in accordance with the invention. - In the figures the incident photons hit the solar cell p-n junction and excite electrons, thus resulting in photocurrent that can be used to power a load. The
first photon filter 100 is arranged in between the solar cell layers 200 and 201, and thesolar cell 200 is arranged with thephoton filter 100 on the side opposite to the incident side of sunlight. Thephoton filter 100 is arranged to reflect photons back into the firstsolar cell 200 with energies that are at energies where the firstsolar cell 200 has high quantum efficiency (λ2 photons). On the other hand thephoton filter 100 is arranged to be transparent to photons of other energies or wavelengths λ1, and these photons are arranged to enter the second solar cell (201). Thephoton filter 100 does not allow the λ1 photons to return back to the first solar cell layer, thereby realising unidirectionality. Therefore the photons that have an energy/wavelength λ2 that could get converted to photocurrent in firstsolar cell layer 200 are reflected back to the firstsolar cell layer 200 by e.g. thereflector 110, and those that can't are arranged to be transported to another solar cell layer, such as secondsolar cell layer 201, where they remain entrapped if at energy higher than the energy band gap of secondsolar cell layer 201. - In some embodiments the solar cell layers are very thin to minimise the scattering cross-section of unwanted photon interactions, i.e. those that happen at energies where the quantum efficiency of the solar cell layer is poor. These interactions heat up the solar cell. In some embodiments the sunlight incident side of
solar cell 200 is covered by a semi-permeable film, or ananti-reflection coating 167 shown inFIG. 2B . In some embodiments there is a film on the sunlight incident side ofsolar cell 200 that only lets solar photons in, but does not allow them to get out. In some embodiments of the invention this antireflection effect is obtained by coarsening the Sun incident surface of the firstsolar cell 200. - In some embodiments of the invention incident sunlight is focused on a section of the first
solar cell 200, and the resulting beam is arranged to be dispersed byreflector 110 after it has passed through the firstsolar cell layer 200, i.e. the reflector might also have different shapes in some embodiments of the invention. This is shown in more detail inFIG. 2C , where thelens 190 focuses the photons to the depletion region, and the reflector has a dispersing means 195 for dispersing photons into the depletion region and further ontoreflectors solar cell 200 are arranged with aphoton reflector solar cell 200. Thereflectors - The
reflector filter 110 is typically a Rugate filter in some embodiments but can be any other band pass photon filter in accordance with the invention. Thefilter 110 splits the photons into two populations: the reflected photons λ2 and the photons passed through λ1. In some embodiments of the invention there is a cut-off frequency/wavelength/energy λx that splits the populations, in the case of the first photon filter let us name the cut-off λx100. - In
FIG. 2A the secondsolar cell 201 is arranged with a photon filter on the side opposite to the incident side ofsunlight 111 and also on thesunlight incident side 150. Thephoton filter 100 is arranged to focus the photons of other energies that did not get reflected by thereflector 110, and the said photons enter throughsmall apertures 140 from thephoton filter 100 side opposite to the incident side of sunlight. As these photons enter the second solar cell layer, they are again subject to the aforementioned procedure, but with a different band gap and cut-off wavelengths. The λ1 photons are interacting with the band gap of secondsolar cell layer 201, i.e. at least those photons that do have the energy to do so. - It could be summarised that the photon filter of the invention conducts a spatiospectral modulation on the solar spectrum, i.e. it alters the photon signal/population in the spatial (focus on small apertures) space as well as frequency space (filtering) in
FIG. 2A . - In some embodiments the second
solar cell 201 is arranged with asecond photon filter 101 on the side opposite to the incident side of sunlight. Thesecond photon filter 101 splits the λ1 photon population into two. Let us name the cut-off wavelength here as λx111. Thesecond photon filter 101 is arranged to reflect photons back into the secondsolar cell 201 with energies that are energies where the secondsolar cell 201 has high quantum efficiency. These photons are marked with λ4 in theFIGS. 2A , 2B, 2C, 2D. Thefirst photon filter 100 is also arranged to reflect photons back into the secondsolar cell 201 with energies that are energies where the secondsolar cell 201 has high quantum efficiency, with aphoton reflector 150 that is on the side opposite to the incident side of sunlight in thefirst photon filter 100 in some embodiments. These photons are marked with λ5 in theFIG. 2A . In some embodiments the wavelengths are the same i.e. these photons are marked with λ4=λ5, but they may also be different in accordance with the invention in other embodiments. In some embodiments the photon filters 100, 101 are arranged to entrap photons into the second solar cell that are at energies where the secondsolar cell 201 has high quantum efficiency. The photons at these energies will be bouncing between thefilters solar cell layer 201, or go through a photon-phonon process that allows them to escape into the photon population with energy/wavelength λ3 and exit throughfilter 101. In other words, thesecond photon filter 101 is arranged to be transparent to photons that are not at energies where the secondsolar cell 201 has a high quantum efficiency, and these said transparent photons are arranged to enter a third solar cell 202 (not shown here), or exit the tandem solar cell system. - A method of producing the aforementioned solar cell is also in accordance with the invention. In some embodiments of the invention at least one of the solar cell layers and/or photon filters is produced, manufactured and/or grown by lithography, molecular beam epitaxy (MBE) metalorganic vapour phase epitaxy (MOVPE), Czochralski (CZ) silicon crystal growth method, Edge-define film-fed growth (EFG) method, Float-zone silicon crystal growth method, Ingot growth method and/or Liquid phase epitaxy, (LPE). Any fabrication method described in the references FI20070264, An active solar cell and method of manufacture, FI20070743 Thermodynamically shielded solar cell, FI20070801 Method and means for designing a solar cell, EP 09154530.1 Low cost solar cell, EP 1724 841 A1, Josuke Nakata, “Multilayer Solar Cell”, U.S. Pat. No. 6,320,117, James P. Campbell et al., “Transparent solar cell and method of fabrication”, Solar Electricity, Thomas Markvart, 2nd Edition, ISBN 0-471-98852-9 and “An unexpected discovery could yield a full spectrum solar cell, Paul Preuss, Research News, Lawrence Berkeley National Laboratory, U.S. Pat. No. 6,320,117, James P. Campbell et al., “Transparent solar cell and method of fabrication”, U.S. Pat. No. 6,689,949, Ugur Ortabasi, Concentrating photovoltaic cavity converters for extreme solar-to-electric conversion efficiencies, US 2008/0251112 A1, David g. Jenkins, Concentrating photovoltaic kaleidoscope and method, can be applied to produce a solar cell in accordance with the invention.
- Optical filter components;
reflector elements elements - It should be noted that the
embodiment 20 can be freely combined and permuted withembodiments -
FIG. 2B presents an alternative inventive photon filter arrangement for a tandem solar cell of the invention. Sunlight enters the firstsolar cell 200 of the tandem solar cell as explained before. Thefilter 110 is preferably adjusted to reflect high energy and short wavelength λ2 photons back to thesolar cell 200, and the firstsolar cell 200 is typically arranged with a high energy band gap and a response or quantum efficiency (QE) function that has a high efficiency at these higher energies. Thefilter 100 is arranged to pass lower energy photons with longer wavelengths λ1 through. These λ1 photons are arranged to enter the secondsolar cell 201, which has a response and a band gap that has higher quantum efficiency at the energies of these photons. However, the secondsolar cell 201 needs aphoton filter 170 at the sunlight incident side, and the λ1 photons need to be arranged to pass through it to ensure photon entrapment in secondsolar cell 201. To do the aforementioned, anantireflective coating 160 is arranged between the twofilters filter 170 is arranged to reflect λ1 photons on the side incident to the secondsolar cell 201 back to the secondsolar cell 201, so these photons need to be carefully inserted through thefilter 170 to the secondsolar cell 201, so that thefilter 170 does not reflect them back to the firstsolar cell 200, because λ1 photons are not wanted there, as they cannot convert to current in accordance with the invention. - The
antireflective coating 160 is typically a quarter wavelength layer with the refraction index of √(n110n170), where n110 is the refractive index offilter 110, and n170 is the refractive index offilter 170. As said the antireflective coating typically has a thickness of (¼)*λ1, or similar. It should be noted that as the optimum thickness varies as a function of the wavelength, the optimum thickness for the antireflective coating may depart quite significantly from λ1 in some embodiments of the invention, depending on the secondary photon spectrum that emerges through thephoton filter 110. - In some embodiments of the invention the
antireflective coating 160 contains several layers of the aforementioned quarter wavelength layer, typically based on different wavelengths to increase the spectral range of theantireflective coating 160. In some embodiments of the invention the refractive index may deviate from √(n110n170), preferably to accommodate other design requirements in accordance with the invention. Theantireflective coating 160 is designed to achieve a smooth transition of λ1 photons into the secondsolar cell layer 201, and the fact that there is no antireflective coating betweenfilter 170 and the secondsolar cell layer 201 is designed to prevent any photons now in the secondsolar cell layer 201 from returning back through thefilter 170 towards the firstsolar cell layer 200. - In one embodiment of the invention, the refractive indices of the materials are adjusted so that there is total internal reflection between
filter 170 and secondsolar cell layer 201. In this embodiment preferably thefilter 170 will have a low index of refraction, whereas the secondsolar cell layer 201 should have a high index of refraction. This would be preferable in accordance with the invention and in view of the critical angle law θ=arcsin(nto/nfrom), where nto is the refractive index of the destination material to which the photon is headed to, and nfrom is the refractive index of the material from which the photon attempts to enter the destination material. So if thefilter 170 has a low index of refraction in comparison to secondsolar cell layer 201, →for a photon going fromfilter 170 to secondsolar cell layer 201 arcsin(high) →not defined, no total internal reflection, even at grazing angles, the photons will pass through. Coming back however, arcsin(low)→total internal reflection will occur even for nearly perpendicularly incident returning photons. In some specific interfaces the refractive indices of the materials may be used to realise preferred distribution of photons in accordance with the invention. - In fact, in some embodiments of the invention there is no need for the
antireflective coating 160, when the refractive indices of the materials are adjusted properly. - In fact, in one embodiment there is no filter between the two solar cell layers 200, 201, rather the refractive indices of the materials at certain wavelengths are chosen so that photon entrapment results to the right solar cell layer at the right photon energy, and the interface between the two solar cell layers 200, 201 realises the unidirectional photon filter of the invention. This embodiment is shown in
FIG. 2D . For example in one embodiment the secondsolar cell 201 has a high relative refractive index at energies below the energy band gap of the firstsolar cell 200, and a low relative refractive index at energies higher than the energy band gap of the firstsolar cell 200. With this choice of refractive indices, the high energy photons more suitable for the band gap of the firstsolar cell layer 200 get reflected at the interface of the secondsolar cell 201 back into the firstsolar cell 200. - Furthermore the lower energy photons more suitable for the band gap of the second
solar cell 201 will now transmit through the interface. Even further, the photons that were transmitted into the secondsolar cell 201 are typically reflected back from a reflector at the bottom of the secondsolar cell 201. When these photons return back to the interface, the likelihood of total internal reflection is very high, because for the returning reflected photon, the interface has a high relative nfrom and a low relative nto. Consequently, the returning photons are trapped into the secondsolar cell layer 201, unless they can pass onto a further third solar cell layer or exit through a similar refractive index interface or some of the other unidirectional filter options mentioned before. Furthermore, from this follows the disruptive invention that indeed in a tandem solar cell the refractive index wavelength function of a solar cell material should peak in the proximity of the band gap of the said solar cell material, and even more preferably have a low refractive index at energies far away from its band gap. Consequently a solar cell layer in a tandem solar cell should have a QE (quantum efficiency) vs. wavelength function that peaks with the refractive index vs. wavelength function, i.e. the high refractive index would ideally be associated with a high QE in a solar cell layer of the tandem solar cell of the invention. - Quite clearly it is in accordance with the invention to have more than one photon filters that are realised by choosing the refractive indices of the solar cell layer materials as explained above. For example a tandem solar cell with four solar cell layers may have two interfaces that are realised by choosing individual solar cell layers with appropriate refractive indices, and one interface that has some of the more elaborate unidirectional photon filter arrangement, such as spatiospectral modulation, antireflective coating and/or coarsened interface as explained before. It is of course also in accordance with the invention to have a single filter layer between the solar cell layers, as is shown in
FIG. 2C . - The λ1 photons then enter the second
solar cell 201 through thefilter 170 and λ4 photons are arranged to be entrapped into the secondsolar cell 201, whereas λ3 photons are arranged to pass through thefilter 111 and out of the secondsolar cell 201. In consistency with what has been said before, the secondsolar cell 201 is typically arranged to have high quantum efficiency at energies of photons λ4, which are typically the high energy photons of the photon population λ1. Typically in accordance with the invention, the photons μ3 have a lower energy and longer wavelength at which wavelength the secondsolar cell 201 is no longer efficient. λ3 photons are therefore arranged to exit the second solar cell, and possibly enter a third solar cell (not shown), or simply exit the tandem solar cell. λ3 photons typically transmit through thefilter 111 in accordance with the invention and reach anantireflective interface 165, because the λ3 photons are not wanted in the second solar cell as explained before. - In this particular case the
antireflective interface 165 has been achieved by coarsening the interface between the twophoton filters interface 165 is arranged to prevent total internal reflection and reflection in general by thephoton filter 171. This is because in a coarsened interface the photons cannot escape the interface with a single reflection at an angle of total internal reflection, instead they will meet thephoton filter 171 at an incidence angle somewhere in the coarse interface that will typically allow transmission. - Quite clearly the
antireflective coating 160 and/orantireflective interface 165 ofFIG. 2B can be used to substitute the spatiospectrally modulating optical filter arrangements (120, 130, 140) ofFIG. 2A in some embodiments of the invention. - Quite clearly the tandem solar cell of the invention may feature any number of solar cells with any number of filter arrangements and any type of filter arrangements which may include
antireflective coating 160,antireflective interface 165, suitably selected refractive indices nto, nfrom and/or spatiospectral modulation in any combination and/or permutation in accordance with the invention. It should be noted that any interface can be coarsened in accordance with the invention to increase antireflection properties, for example the interface arranged to filter photons based on selected refractive indices as explained before can also be coarsened in accordance with the invention. - For clarity, it should be noted that the tandem solar cell has the depletion region interface in parallel to incident sunlight in
FIGS. 2A , 2B, 2C and 2D. Quite clearly the depletion region interface may also be perpendicular or in fact in any angle to the incident sunlight, as the main point is to get the photons into the photoelectrically active firstsolar cell 200 in accordance with the invention. In some embodiments of the invention the depletion region interface between the p-region and the n-region is arranged perpendicular to incident sunlight, but any positioning is possible in accordance with the invention. The electrical contacts that collect the generated photocurrent are shown inFIG. 2B asfront contact 250 andrear contact 251, but clearly they can be positioned to accommodate different configurations in accordance with the invention. The electrical contacts are typically hidden to minimise shading losses, for example by Angled Buried Contacts, as is shown for thefront contact 250, where the contact is actually at an angle buried under the surface, and thereby does not cause a shade on the incident radiation. Even the buried contact should be made reflective to photons in accordance with the invention. Similarly any optical concentrators, lenses or the like can be used to focus sunlight, or light from other sources, to the solar cell of the invention, and in particular to the incidence side of the firstsolar cell 200 in accordance with the invention of which just one example is shown inFIG. 2C . - It should be noted that the
embodiment 21 can be freely combined and permuted withembodiments -
FIG. 2C shows theembodiment 22 with the focusing means 190 and the entrappingreflectors reflector 195 at the bottom of the firstsolar cell layer 200, to ensure the reflected photons do not reflect out of the solar cell through the aperture they came in from. -
FIG. 2C also shows a singleunidirectional filter 100 between the said solar cell layers 200, 201, which is a useful embodiment of the invention. - It should be noted that the
embodiment 22 can be freely combined and permuted withembodiments -
FIG. 2D shows the simplest embodiment of theinvention 23, which however places the hardest criteria on the materials chosen. In this embodiment, thefilter 100 is realised purely by theinterface 100 between the two solar cell layers 200, 201, which have their band gaps and refractive indices selected as describer earlier. - It should be noted that the
embodiment 23 can be freely combined and permuted withembodiments -
FIG. 3 demonstrates an embodiment of the invention where there are four solar cell layers 200, 201, 202, and 203 and three or fourphoton filters - In one embodiment of the
invention 30 the tandem solar cell comprises several solar cell layers 200, 201, 202, 203, and in between two solar cell layers there is a photon filter, 100, 101, 102. The photon filters are tuned so, that they will trap only those photons that are at an energy where the solar cell layer is working at a good quantum efficiency (QE), ideally close to 1. The rest of the photons are simply passed to the next layer by the photon filter. The solar cell layers 200, 201, 202 are preferably very thin, or otherwise designed so that there is minimal interaction between the solar cell and the photon population at energies where the quantum efficiency is NOT that good, i.e. far from unity. In some embodiments the last solar cell layer, i.e. 203 in this case, can be thick. It may also have a reflective mirror on the side opposite to the incident side of sunlight, or aphoton filter 103 that may be designed to let heat photons out, but trap those photons with photovoltaic band gap absorption potential, i.e. energy enough to be absorbed. - In one preferable embodiment of the invention the first
solar cell layer 200 is a GaN layer with a band gap of 3.4 eV (electron volt). The secondsolar cell layer 201 is an InGaP layer with a band gap of 1.93 eV in some embodiments of the invention. The thirdsolar cell layer 202 is a polycrystalline silicon layer, with a band gap at 1.1 eV in some embodiments of the invention. In some further embodiments of the invention the lastsolar cell layer 203 is an InSb layer with a band gap of 0.17 eV. What could be the cut-off wavelengths λxs ? In thelayer 200 photons with less than 3.4 eV are useless, as they cannot be absorbed into photocurrent. Therefore the λx100 should be equivalent to 3.4 eV or similar, i.e. 365 nm, i.e. a UV-mirror that would let photons longer than 365 nm (nm=nanometers) pass through. Consequently, the second InGaPsolar cell layer 201 at 1.93 eV would require the λx101 to be equivalent to 1.93 eV or similar, i.e. 643 nm, i.e. a visible light-mirror that would let photons longer than 643 nm pass through. The third polymorphic siliconsolar cell layer 202 at 1.1 eV would require 1128 nm for the λx102, i.e. a red-IR mirror. The photons longer than 1128 nm or similar threshold would be passed to thefourth layer 203 with an InSb band gap of 0.17 eV→7301 nm. In some embodiments of the invention thislast layer 203 would be made thick, because all the remaining photons should interact in thislayer 203. - In some embodiments of the invention it is preferable to make the solar cell system thin. In some embodiments of the invention the thickness of each solar cell layer is a reasonable multiplier of the wavelength that equates with the band gap, to ensure particle nature of the photons in the solar cell layers. For example if the multiplier were 10, solar cell layers 200, 201, 202 and 203 would have thicknesses of 3650 nm, 6430 nm, 11280 nm and 73010 nm respectively. The one quarter wavelength antireflective coatings would have thicknesses of roughly 91.25 nm, 160.75 nm, 282 nm, 1825 nm, respectively in preferred embodiments of the invention. Assuming the filters have comparative thicknesses the structure would be about one millimetre thick in accordance with this embodiment of the invention. Naturally these parameters can be tuned in accordance with the invention. Clearly the four layer tandem solar cell is a preferable embodiment, because it samples both the solar spectrum and the resultant secondary spectrum (emerging spectrum after the first solar cell layer), tertiary spectrum (emerging spectrum after the second solar cell layer) and quaternary spectrum (emerging spectrum after the third solar cell layer) so well.
- It should be noted that the
embodiment 30 can be freely combined and permuted withembodiments -
FIG. 4 displays an exemplary embodiment of the invention in energy space—i.e. spectral space. The incidentsolar spectrum 300 runs from 200 nm in the UV to roughly 2400 nm, thespectrum 300 is a AM 1.5 G 1000 W/m2 solar spectrum typically encountered on Earth. The firstsolar cell layer 200 has a solar cell response that is slightly lower in energy than the GaN and slightly higher in energy than the InGaP. It has a reasonably high QE in between 365-645 nm, i.e. blue light, as shown in the QE plot that is superposed underneath thespectrum 300. Because the solar cell response practically coincides with the big bump of strong intensity in theincident spectrum 300, the photocurrent power spectrum that shows spectral distribution of collectedphotocurrent power spectrum 400 and therefore energy and power generated by the firstsolar cell layer 200 is quite similar in shape to the response of the firstsolar cell layer 200. However thephoton spectrum 401 will be quite modified when it reaches thefirst photon filter 100. Thephoton filter 100 will spatiospectrally modulate thephoton spectrum 401 in some embodiments of the invention, or use another unidirectional filter as explained before. Thephoton filter 100 will preferably reflect the λ2 photons with higher energies and shorter wavelengths, i.e. the photons with a shorter wavelength of λx100 that should correspond to the energy band gap of thesolar cell layer 200 in accordance with the invention. The λ1 photons will be passed to the secondsolar cell layer 201 by the focusing means or other spatial modulation means, resulting into the spatial component of the modulation, or by another unidirectional filter, and this layer will again have a different cut-off frequency λx101 in accordance with the invention in some embodiments. - The
solar cell response 201 converts the photocurrent from this photon population. Thephoton filter 101 will reflect λ4 photons back to thesolar cell layer 201, and the reflector that does this resides on the side facing in the same direction as the sunlight incident side. Thephoton filter 100 will have areflector 150 around thesmall apertures 140 that released the λ1 photons into thesecond layer 201, or another reflectingfilter 170 or interface on the solar incident side facing the second solar cell layer as explained before. This reflector will reflect λ5 photons back again from the side opposite to the sunlight incident side ofphoton filter 100, resulting in photon entrapment betweenphoton filters - The remaining low energy photons λ3 are passed onto a third
solar cell layer 202 in accordance with the invention in some embodiments, or they are simply released out of the tandem solar cell or left in the lattice in some embodiments of the invention. - It should be noted that the
embodiment 40 can be freely combined and permuted withembodiments -
FIG. 5 shows an embodiment of the operation of the inventive method and device as a flow diagram 50. We start to observe the situation after the photons have entered the firstsolar cell layer 200. Once in the firstsolar cell layer 200 the photon population traverses through it, with some photons getting absorbed and exciting photocurrent in this solar cell layer. After the photons have traversed through the firstsolar cell layer 200 that is preferably quite thin, they reach thephoton filter 100 inphase 600 where the photons with wavelength shorter than λX100 are reflected back to the firstsolar cell layer 200. The incident and the reflected photons produce the photopower ofsolar cell 200. - In
phase 610 the photons with wavelength longer than λX100 are focused by the at least onelens 120. The lenses can be of any shape and any material in accordance with the invention, but they can also be replaced by any other focusing means, or in fact by any means capable of splitting the photon populations in the desired way, for example by a unidirectional filter. The whole point about focusing the photons passed through is to perform the spatial aspect of the modulation in order to achieve enough reflective surface to the other wall of thephoton filter 100 facing the secondsolar cell layer 201. It is in accordance with the invention to deploy other equivalent means to focusing and spatial modulation in some embodiments. For example and alternatively photons with wavelength longer than λX100 may pass to an antireflective coating or coarse interface as explained inFIG. 2B in some embodiments, or they may pass to an interface with refractive indices adjusted to ensure photon selection and entrapment as shown inFIG. 2D and explained before or to aunidirectional filter 100 as shown inFIG. 2C and explained before. - In
phase 620 photons with wavelength longer than λX100 enter thesolar cell 201 through at least oneaperture 140, which are typically very small in order to maximise thereflective area 150 of the other wall of thephoton filter 100 facing the secondsolar cell layer 201. Some of these incident photons now generate photopower from secondsolar cell layer 201. Inphase 630 the photons with wavelength shorter than λX101 are reflected by thephoton filter 101. These photons are thus simply reflected back to the secondsolar cell layer 201. Some of these reflected photons are absorbed and produce photopower ofsolar cell 201. - Some of the reflected photons pass through the second
solar cell layer 201 again, without having been absorbed. Provided their wavelength is shorter than λX101 these photons are reflected again, this time by thereflector 150 ofphoton filter 100. In some embodiments of the invention thereflector 150 of the photon filter on the wall facing the secondsolar cell layer 201 is designed to simply reflect back all the photons or as many photons as possible on as wide a band as possible in accordance with the invention. Inphase 630 there will now be a photon population bouncing back and forth between the photon filters 100, 101 in accordance with the invention. This photon entrapment gives several opportunities for the photons to get absorbed into the secondsolar cell layer 201. Inphase 640 the photons that no longer have a chance of being converted to photocurrent, are focused by thelens 121 or other focusing means. It makes sense to adjust the cut off λX101 so that it reflects back all those photons that do have a chance of getting absorbed in the secondsolar cell layer 201, but naturally λX101 can be selected otherwise in accordance with the invention, based on other design criteria for example. - In
phase 650 the photons with wavelength longer than λX101 enter thesolar cell 202 preferably fromsmall apertures 141 in the wall of thephoton filter 101 facing the thirdsolar cell layer 202. The process repeats in the thirdsolar cell layer 202 with the same aforementioned principle albeit at longer wavelengths to generate the photopower of thesolar cell 202. - It should be noted that the
embodiment 50 can be freely combined and permuted withembodiments - The operation of the
method 50 was explained with spatiospectral modulation providing the unidirectional filtering of photons. It is in accordance with the invention to use the other unidirectional photon filters described earlier to realise the operation of theembodiment 50 mutatis mutandis. - It should also be noted that in all or some embodiments in addition to inter band gap semiconductors, also intra band gap semiconductor junctions, such as quantum cascade semiconductor junctions can be used to achieve the desired photoelectric properties for a particular solar cell layer in accordance with the invention. It should also furthermore be noted that the solar cells of the invention need not be necessarily square or flat, indeed they can be realised in any shape, for example spherical shape in some embodiments, as described in FI20070743 Thermodynamically shielded solar cell & counterparts or otherwise. Furthermore it should be stressed that in some embodiments of the invention the solar cell or tandem solar cell systems of the invention can be realised in any size, from nanometer scale structures to large structures. From power plant size installations to power solutions of very small portable devices, the solar cells and the photon filtration systems find use in many markets in accordance with the invention.
- It should also be noted that the invention has been described here so that the highest band gap solar cell and the highest band pass filter is the first incident to the sunlight. It should be noted that the invention can also be implemented in the reverse order, i.e. having the smaller energy solar cell layers and filters first in some embodiments. Indeed the band gaps of the solar cell layers may be in any order in some embodiments of the invention, the main point is that these solar cell layers work with photons that are at an energy at which the solar cell layer has a good QE, and DO NOT work with photons that are at an energy where the QE is poor.
- However, the highest band gap material first and the conduction of the filtering and band gaps in an order of high-to-low when moving from the incident sunlight side to the back of the tandem solar cell is preferable in some embodiments of the invention, because this produces the smallest number of photoelectric absorptions per the first photoelectric unit of energy generated. In layman terms, the bigger energy photons absorbing themselves first create more energy in a lesser number of absorptions, because the absorptions are of higher energy. This leads to smaller number of second order photons and phonons generated, and we do want to avoid small energy photons, especially if their energy is so small that we are pushed to find a small enough band gap in the consecutive solar cell layers. However, when starting from the low band gap material first, a huge number of absorptions can occur, but at a low unit energy per absorption. The higher energy photons will in this case be producing a lot of secondary photons, and the spectrum will “cool”, i.e. move to lower E photons considerably faster. Once these photons start to approach energies we can no longer photo electrically collect, they begin to be parasitic and thus not preferred.
- It should be noted that the embodiments described here can be used in any combination or permutation with any of the embodiments described in the other patent applications of the inventor FI20070264 An active solar cell and method of manufacture, FI20070743 Thermodynamically shielded solar cell, FI20070801 Method and means for designing a solar cell and EP 09154530.1 Low cost solar cell and/or their international counterparts which are now explicitly incorporated into this application.
- For example the use of the bias voltage as described in FI20070264 is preferable in especially the lower solar cell layers in some embodiments of the invention to achieve photoelectric conversion at very low band gaps. For example the optical concentration and convective, conductive and/or radiative shielding solutions of FI20070743 can be implemented in a very useful way to ensure high photon fluxes in accordance with the invention in some embodiments. Likewise the software design method of FI20070801 can be used to design some of the tandem cells in accordance with the invention. Some of the cost reducing embodiments of EP 09154530.1, or other embodiments, can be combined with the embodiments of the present invention. Many useful embodiments can thus be derived from combining the embodiments of these five patent applications from the same inventor that are all directed to the same theme: providing a photoelectric solution to the global energy problem.
- It should be noted that the electrodes collecting photocurrent from the aforementioned solar cell layers may be arranged in any configuration in accordance with the invention. Furthermore the position and/or angle of the p-n junction to the incident solar flux or artificial light may be arranged to any position and/or angle and the system of the invention can be implemented in any geometry.
- It is currently not known, which are all the factors that cause a shortcoming in the efficiency of the solar cell. However, based on the studies of the applicant, the general tandem solar cell is hampered the most by the photon-phonon processes that take place outside the band of maximum quantum efficiency of the solar cell. The inventive concept presented in this application, i.e. the filtering of the photon population so that all layers of a tandem solar cell work at their optimum quantum efficiencies (QEs) will greatly improve the efficiency of and power generated by solar cells. The unidirectionality of the inventive photon filters realises this advantage as the leakage of unwanted photons back to earlier solar cell layers is minimised.
- The aforementioned invention has a multitude of practical use scenarios. The solar cells of the invention can be installed to a power plant for power generation to the grid. The inventions can be installed on any building to provide electricity for air conditioning and household appliances, or the like in that building or elsewhere. The inventive solar cells can be installed on a vehicle, to power the vehicle motor electrically, charge the battery, or power electric appliances for the vehicle. However, as the inventive solar cells have a reasonably high cost of design and manufacture at first, the most advantageous application is probably in the field of portable electronic devices. Laptop computers, mobile phones, electric shavers, epilators, electric toothbrushes, calculators, music players such as MP3 players (e.g. ipod), palm computers, TV's, radios, screens, monitors, printers, flash memory drives, external hard disk drives, watches and/or any other kind of electric equipment that now needs a charger can be installed with the solar cells of the invention. As the solar cells of the invention are very efficient producing high power per unit area, the solar cells can keep the battery of the device charged pretty much all the time, without increasing the dimensions of the portable device. A further notable advantage of the invention is that it converts electric power very efficiently from artificial light also. In one advantageous embodiment at least one solar cell layer of the tandem solar cell is chosen arranged so that it has a band gap and a spectral response that converts electricity efficiently from photons emitted by indoor lights, such as fluorescent lights, LEDs (light emitting diodes) or light bulbs. The solar cell layers of the invention can also be arranged to work well in both indoor and outdoor solar light, by choosing the solar cell layer materials with the appropriate spectral responses and band gaps in accordance with the invention.
- Quite clearly the solar cells of the invention can be camouflaged to aesthetically fit any product or building. Also, quite clearly the solar cells of the invention can be coupled with other power generation mechanism, such as kinetic power generation by piezoelectric crystals or the like to increase the battery time of the portable electronic device, or even to get rid of the need for a grid charger in some embodiments of the invention.
- In fact a power system including both a solar cell arranged to generate power by photoelectric conversion (from sunlight and indoor lights) and a piezoelectric crystal arranged to generate power from its mechanical movement (for example by the person using and carrying the power system) is in itself an invention. It could be used to realise new devices with considerably longer battery times, or new portable devices even without the restriction of grid charging. The combination of a mechanical and photovoltaic power source is especially preferable because the photovoltaic power generation works when the portable device is exposed to light, and the piezoelectric and/or other mechanical power generation system based on e.g. (pendulum and/or springs found in watches) works typically when the portable electronic device is concealed in the pocket of the user, i.e. being moved in the dark. This way the inventive system is charging the portable electronic device nearly all the time. Especially in one embodiment the combined power system of a mechanical power generator and a solar cell will feature a solar cell with a band gap at an energy associated with photons emitted from fluorescent lights or other indoor lightning systems, typically at a wavelength of 400-500 nm.
- The inventive tandem solar cell would suit the above mentioned power solution for a portable device perfectly, as it can cope with a variety of incoming light spectra, such as indoor light spectra in some embodiments.
- The invention has been explained above with reference to the aforementioned embodiments and several commercial and industrial advantages have been demonstrated. The methods and arrangements of the invention allow the construction of a solar cell where a high number of very thin solar cell layers each work at nearly 100% quantum efficiency, because the inventive photon filters restrict the photon population to the most efficient bands of the solar cell layers, and therefore a practically ideal solar cell delivering power close to the solar constant 1.37 kW/m2 in space and roughly 1 kW/m2 on Earth is made possible by the invention.
- The invention has been explained above with reference to the aforementioned embodiments. However, it is clear that the invention is not only restricted to these embodiments, but comprises all possible embodiments within the scope of the invention and the following patent claims.
-
- FI20070264 An active solar cell and method of manufacture
- FI20070743 Thermodynamically shielded solar cell
- FI20070801 Method and means for designing a solar cell
- EP 09154530.1 Low cost solar cell
- EP 1724 841 A1, Josuke Nakata, “Multilayer Solar Cell”
- U.S. Pat. No. 6,320,117, James P. Campbell et al., “Transparent solar cell and method of fabrication”
- U.S. Pat. No. 6,689,949, Ugur Ortabasi, Concentrating photovoltaic cavity converters for extreme solar-to-electric conversion efficiencies.
- US 2008/0251112 A1, David g. Jenkins, Concentrating photovoltaic kaleidoscope and method.
- Solar Electricity, Thomas Markvart, 2nd Edition, ISBN 0-471-98852-9
- “An unexpected discovery could yield a full spectrum solar cell, Paul Preuss, Research News, Lawrence Berkeley National Laboratory.
- U.S. Pat. No. 5,021,100, Takashi Ishihara et al. Tandem Solar Cell.
Claims (22)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/051,097 US20110168244A1 (en) | 2009-06-10 | 2011-03-18 | Method and means for a high power solar cell |
US17/140,158 US20210151620A1 (en) | 2009-06-10 | 2021-01-04 | Method and means for a high power solar cell |
US17/169,482 US20210343890A1 (en) | 2009-06-10 | 2021-02-07 | Method and means for a high power solar cell |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP09162378A EP2261996B8 (en) | 2009-06-10 | 2009-06-10 | High power solar cell |
EPEP09162378.5 | 2009-06-10 | ||
US12/791,188 US8198530B2 (en) | 2009-06-10 | 2010-06-01 | Method and means for a high power solar cell |
US13/051,097 US20110168244A1 (en) | 2009-06-10 | 2011-03-18 | Method and means for a high power solar cell |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/791,188 Division US8198530B2 (en) | 2009-06-10 | 2010-06-01 | Method and means for a high power solar cell |
Related Child Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US17/140,158 Division US20210151620A1 (en) | 2009-06-10 | 2021-01-04 | Method and means for a high power solar cell |
US17/169,482 Division US20210343890A1 (en) | 2009-06-10 | 2021-02-07 | Method and means for a high power solar cell |
Publications (1)
Publication Number | Publication Date |
---|---|
US20110168244A1 true US20110168244A1 (en) | 2011-07-14 |
Family
ID=41503742
Family Applications (4)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/791,188 Active US8198530B2 (en) | 2009-06-10 | 2010-06-01 | Method and means for a high power solar cell |
US13/051,097 Abandoned US20110168244A1 (en) | 2009-06-10 | 2011-03-18 | Method and means for a high power solar cell |
US17/140,158 Abandoned US20210151620A1 (en) | 2009-06-10 | 2021-01-04 | Method and means for a high power solar cell |
US17/169,482 Abandoned US20210343890A1 (en) | 2009-06-10 | 2021-02-07 | Method and means for a high power solar cell |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/791,188 Active US8198530B2 (en) | 2009-06-10 | 2010-06-01 | Method and means for a high power solar cell |
Family Applications After (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US17/140,158 Abandoned US20210151620A1 (en) | 2009-06-10 | 2021-01-04 | Method and means for a high power solar cell |
US17/169,482 Abandoned US20210343890A1 (en) | 2009-06-10 | 2021-02-07 | Method and means for a high power solar cell |
Country Status (12)
Country | Link |
---|---|
US (4) | US8198530B2 (en) |
EP (3) | EP2261996B8 (en) |
JP (1) | JP2012529760A (en) |
KR (1) | KR20120087874A (en) |
CN (1) | CN102428575A (en) |
AT (1) | ATE509375T1 (en) |
AU (1) | AU2010257562A1 (en) |
CA (1) | CA2766686A1 (en) |
DK (1) | DK2261996T3 (en) |
ES (1) | ES2363580T3 (en) |
HK (1) | HK1148865A1 (en) |
WO (1) | WO2010142626A2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2013132297A1 (en) * | 2012-03-08 | 2013-09-12 | Siu Chung Tam | A photovoltaic device |
US20210367091A1 (en) * | 2017-11-21 | 2021-11-25 | Technion Research & Development Foundation Limited | Harvesting of energy from diverse wavelengths |
Families Citing this family (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2302688A1 (en) * | 2009-09-23 | 2011-03-30 | Robert Bosch GmbH | Method for producing a substrate with a coloured interference filter coating, this substrate, interference filter coating, the use of this substrate as coloured solar cell or as coloured solar cell or as component of same and an array comprising at least two of thee substrates |
US8217258B2 (en) | 2010-07-09 | 2012-07-10 | Ostendo Technologies, Inc. | Alternating bias hot carrier solar cells |
EP2523369A1 (en) | 2011-05-12 | 2012-11-14 | Mikko Väänänen | Broadband base station comprising means for free space optical communications |
JP2013179297A (en) * | 2012-02-10 | 2013-09-09 | Tokyo Institute Of Technology | Solar cell having optical control layer |
JP2014060382A (en) * | 2012-08-20 | 2014-04-03 | Toshiba Corp | Photoelectric conversion element, photoelectric conversion system and manufacturing method of photoelectric conversion element |
US9812867B2 (en) | 2015-06-12 | 2017-11-07 | Black Night Enterprises, Inc. | Capacitor enhanced multi-element photovoltaic cell |
US9899550B2 (en) * | 2015-08-12 | 2018-02-20 | Toyota Motor Engineering & Manufacturing North America, Inc. | Electric power transfer system using optical power transfer |
EP3358637A4 (en) | 2015-09-30 | 2019-06-19 | Kaneka Corporation | Multi-junction photoelectric conversion device and photoelectric conversion module |
CN108613412A (en) * | 2017-02-05 | 2018-10-02 | 鞍钢股份有限公司 | A kind of solar energy induces laser aid and method |
CN107800030A (en) * | 2017-10-20 | 2018-03-13 | 鞍钢未来钢铁研究院有限公司 | A kind of solar energy induces laser aid and method |
ES2718705B2 (en) * | 2018-01-03 | 2020-10-02 | Blue Solar Filters Sl | CONFIGURATION METHOD OF A SPECTRAL SEPARATION MULTILAYER FILTER FOR PHOTOVOLTAIC AND THERMAL SOLAR APPLICATIONS, FILTER AND GENERATION CENTER ASSOCIATED WITH SUCH METHOD |
US11709383B2 (en) * | 2018-06-12 | 2023-07-25 | Raymond Hoheisel | Optical communication and power generation device and method |
AU2021378231A1 (en) * | 2020-09-30 | 2023-05-25 | Thermasat, Inc. | Thermasat solar thermal propulsion system |
TWI799118B (en) * | 2022-01-28 | 2023-04-11 | 勝慧科技有限公司 | Electrode coupled double hetrojunction solar cell having double active regions for photoelectric effect and method of manufacturing the same |
Citations (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS58188169A (en) * | 1982-04-27 | 1983-11-02 | Matsushita Electric Ind Co Ltd | Solar battery |
US4597099A (en) * | 1983-04-20 | 1986-06-24 | Tadashi Sawafuji | Piezoelectric transducer |
US5039354A (en) * | 1988-11-04 | 1991-08-13 | Canon Kabushiki Kaisha | Stacked photovoltaic device with antireflection layer |
JPH03224898A (en) * | 1990-01-30 | 1991-10-03 | Mitsubishi Electric Corp | Artificial satellite |
US5260885A (en) * | 1991-08-31 | 1993-11-09 | Ma Hsi Kuang | Solar power operated computer |
US6268558B1 (en) * | 1998-03-25 | 2001-07-31 | Tdk Corporation | Solar battery module |
US20030160251A1 (en) * | 2002-02-28 | 2003-08-28 | Wanlass Mark W. | Voltage-matched, monolithic, multi-band-gap devices |
US20040065363A1 (en) * | 2002-10-02 | 2004-04-08 | The Boeing Company | Isoelectronic surfactant induced sublattice disordering in optoelectronic devices |
US20050030518A1 (en) * | 2003-03-26 | 2005-02-10 | Kazuo Nishi | Multidirectional photodetector, a portable communication tool having thereof and a method of displaying |
US20050199280A1 (en) * | 2004-03-12 | 2005-09-15 | Royer George R. | Solar battery |
US20060043517A1 (en) * | 2003-07-24 | 2006-03-02 | Toshiaki Sasaki | Stacked photoelectric converter |
US7217882B2 (en) * | 2002-05-24 | 2007-05-15 | Cornell Research Foundation, Inc. | Broad spectrum solar cell |
US20080036127A1 (en) * | 2006-08-09 | 2008-02-14 | Tai-Her Yang | Spring device with capability of intermittent random energy accumulator and kinetics release trigger |
US20080163920A1 (en) * | 2005-01-04 | 2008-07-10 | Azur Space Solar Power Gmbh | Monolithic Multiple Solar Cells |
US20090078311A1 (en) * | 2007-09-24 | 2009-03-26 | Emcore Corporation | Surfactant Assisted Growth in Barrier Layers In Inverted Metamorphic Multijunction Solar Cells |
US20090091479A1 (en) * | 2007-10-04 | 2009-04-09 | Motorola, Inc. | Keypad haptic communication |
US20090103165A1 (en) * | 2007-10-19 | 2009-04-23 | Qualcomm Mems Technologies, Inc. | Display with Integrated Photovoltaics |
US20090159123A1 (en) * | 2007-12-21 | 2009-06-25 | Qualcomm Mems Technologies, Inc. | Multijunction photovoltaic cells |
Family Cites Families (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5284435A (en) * | 1976-08-03 | 1977-07-14 | Suwa Seikosha Kk | Battery wrist watch |
US4188238A (en) * | 1978-07-03 | 1980-02-12 | Owens-Illinois, Inc. | Generation of electrical energy from sunlight, and apparatus |
JPS60111478A (en) * | 1983-11-22 | 1985-06-17 | Toshiba Corp | Photovoltaic device |
JP2738557B2 (en) * | 1989-03-10 | 1998-04-08 | 三菱電機株式会社 | Multilayer solar cell |
US5220462A (en) * | 1991-11-15 | 1993-06-15 | Feldman Jr Karl T | Diode glazing with radiant energy trapping |
JPH09162435A (en) * | 1995-12-07 | 1997-06-20 | Toppan Printing Co Ltd | Filter for solar battery |
US6180871B1 (en) | 1999-06-29 | 2001-01-30 | Xoptix, Inc. | Transparent solar cell and method of fabrication |
JP2003101059A (en) * | 2001-09-27 | 2003-04-04 | Sharp Corp | Thin-film solar cell |
US6689949B2 (en) | 2002-05-17 | 2004-02-10 | United Innovations, Inc. | Concentrating photovoltaic cavity converters for extreme solar-to-electric conversion efficiencies |
EP1724841B1 (en) | 2004-03-12 | 2016-11-16 | Sphelar Power Corporation | Multilayer solar cell |
JP2009502027A (en) * | 2005-07-15 | 2009-01-22 | コナルカ テクノロジーズ インコーポレイテッド | Diffraction foil |
US7459880B1 (en) * | 2006-07-24 | 2008-12-02 | George Michel Rosen | Solar generator panel for an electric or hybrid vehicle |
FI20070264A (en) | 2007-04-04 | 2008-10-05 | Suinno Oy | Active solar cell and process for producing the same |
CN101286531A (en) * | 2007-04-09 | 2008-10-15 | 台达电子工业股份有限公司 | Solar battery |
US20080251112A1 (en) | 2007-04-10 | 2008-10-16 | Raytheon Company | Concentrating photovoltaic kaleidoscope and method |
ATE504086T1 (en) * | 2007-05-28 | 2011-04-15 | Consiglio Nazionale Ricerche | PHOTOVOLTAIC DEVICE WITH IMPROVED LIGHT COLLECTION |
WO2009043662A2 (en) * | 2007-10-01 | 2009-04-09 | Suinno Oy | Thermodynamically shielded solar cell |
JP2010016936A (en) * | 2008-07-02 | 2010-01-21 | Casio Comput Co Ltd | Power generating device |
EP2226852B8 (en) | 2009-03-06 | 2011-10-05 | Suinno Solar Oy | Low cost solar cell |
-
2009
- 2009-06-10 EP EP09162378A patent/EP2261996B8/en active Active
- 2009-06-10 ES ES09162378T patent/ES2363580T3/en active Active
- 2009-06-10 EP EP11165416A patent/EP2360742A2/en not_active Withdrawn
- 2009-06-10 DK DK09162378.5T patent/DK2261996T3/en active
- 2009-06-10 AT AT09162378T patent/ATE509375T1/en not_active IP Right Cessation
-
2010
- 2010-06-01 US US12/791,188 patent/US8198530B2/en active Active
- 2010-06-07 CN CN201080021674XA patent/CN102428575A/en active Pending
- 2010-06-07 KR KR1020127000677A patent/KR20120087874A/en not_active Application Discontinuation
- 2010-06-07 JP JP2012514434A patent/JP2012529760A/en active Pending
- 2010-06-07 AU AU2010257562A patent/AU2010257562A1/en not_active Abandoned
- 2010-06-07 CA CA2766686A patent/CA2766686A1/en not_active Abandoned
- 2010-06-07 WO PCT/EP2010/057888 patent/WO2010142626A2/en active Application Filing
- 2010-06-07 EP EP10726456A patent/EP2441092A2/en not_active Withdrawn
-
2011
- 2011-03-18 HK HK11102723.7A patent/HK1148865A1/en not_active IP Right Cessation
- 2011-03-18 US US13/051,097 patent/US20110168244A1/en not_active Abandoned
-
2021
- 2021-01-04 US US17/140,158 patent/US20210151620A1/en not_active Abandoned
- 2021-02-07 US US17/169,482 patent/US20210343890A1/en not_active Abandoned
Patent Citations (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS58188169A (en) * | 1982-04-27 | 1983-11-02 | Matsushita Electric Ind Co Ltd | Solar battery |
US4597099A (en) * | 1983-04-20 | 1986-06-24 | Tadashi Sawafuji | Piezoelectric transducer |
US5039354A (en) * | 1988-11-04 | 1991-08-13 | Canon Kabushiki Kaisha | Stacked photovoltaic device with antireflection layer |
JPH03224898A (en) * | 1990-01-30 | 1991-10-03 | Mitsubishi Electric Corp | Artificial satellite |
US5260885A (en) * | 1991-08-31 | 1993-11-09 | Ma Hsi Kuang | Solar power operated computer |
US6268558B1 (en) * | 1998-03-25 | 2001-07-31 | Tdk Corporation | Solar battery module |
US20030160251A1 (en) * | 2002-02-28 | 2003-08-28 | Wanlass Mark W. | Voltage-matched, monolithic, multi-band-gap devices |
US7217882B2 (en) * | 2002-05-24 | 2007-05-15 | Cornell Research Foundation, Inc. | Broad spectrum solar cell |
US20040065363A1 (en) * | 2002-10-02 | 2004-04-08 | The Boeing Company | Isoelectronic surfactant induced sublattice disordering in optoelectronic devices |
US20050030518A1 (en) * | 2003-03-26 | 2005-02-10 | Kazuo Nishi | Multidirectional photodetector, a portable communication tool having thereof and a method of displaying |
US20060043517A1 (en) * | 2003-07-24 | 2006-03-02 | Toshiaki Sasaki | Stacked photoelectric converter |
US20050199280A1 (en) * | 2004-03-12 | 2005-09-15 | Royer George R. | Solar battery |
US20080163920A1 (en) * | 2005-01-04 | 2008-07-10 | Azur Space Solar Power Gmbh | Monolithic Multiple Solar Cells |
US20080036127A1 (en) * | 2006-08-09 | 2008-02-14 | Tai-Her Yang | Spring device with capability of intermittent random energy accumulator and kinetics release trigger |
US20090078311A1 (en) * | 2007-09-24 | 2009-03-26 | Emcore Corporation | Surfactant Assisted Growth in Barrier Layers In Inverted Metamorphic Multijunction Solar Cells |
US20090091479A1 (en) * | 2007-10-04 | 2009-04-09 | Motorola, Inc. | Keypad haptic communication |
US20090103165A1 (en) * | 2007-10-19 | 2009-04-23 | Qualcomm Mems Technologies, Inc. | Display with Integrated Photovoltaics |
US20090159123A1 (en) * | 2007-12-21 | 2009-06-25 | Qualcomm Mems Technologies, Inc. | Multijunction photovoltaic cells |
Non-Patent Citations (1)
Title |
---|
Gendron et al., Applied Physics Letters, Vol. 85, No. 14, Pages 2824-2826. * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2013132297A1 (en) * | 2012-03-08 | 2013-09-12 | Siu Chung Tam | A photovoltaic device |
US20210367091A1 (en) * | 2017-11-21 | 2021-11-25 | Technion Research & Development Foundation Limited | Harvesting of energy from diverse wavelengths |
Also Published As
Publication number | Publication date |
---|---|
CN102428575A (en) | 2012-04-25 |
WO2010142626A2 (en) | 2010-12-16 |
US20210343890A1 (en) | 2021-11-04 |
ATE509375T1 (en) | 2011-05-15 |
EP2441092A2 (en) | 2012-04-18 |
US20100313934A1 (en) | 2010-12-16 |
AU2010257562A1 (en) | 2012-02-02 |
ES2363580T3 (en) | 2011-08-09 |
CA2766686A1 (en) | 2010-12-16 |
JP2012529760A (en) | 2012-11-22 |
EP2360742A2 (en) | 2011-08-24 |
KR20120087874A (en) | 2012-08-07 |
EP2261996A1 (en) | 2010-12-15 |
EP2261996B8 (en) | 2011-10-19 |
WO2010142626A3 (en) | 2011-08-11 |
EP2261996B1 (en) | 2011-05-11 |
DK2261996T3 (en) | 2011-08-29 |
US20210151620A1 (en) | 2021-05-20 |
US8198530B2 (en) | 2012-06-12 |
HK1148865A1 (en) | 2011-09-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20210343890A1 (en) | Method and means for a high power solar cell | |
US11817524B1 (en) | Concentrator photovoltaic subassembly and method of constructing the same | |
US5902417A (en) | High efficiency tandem solar cells, and operating method | |
KR20090117690A (en) | High efficiency solar cell with a silicon scavenger cell | |
US20080230112A1 (en) | Photovoltaic cells | |
WO2009134552A2 (en) | Lateral ultra-high efficiency solar cell | |
US20130037108A1 (en) | Thermodynamically shielded solar cell | |
US20100170557A1 (en) | High Efficiency Solar Cell With Surrounding Silicon Scavenger Cells | |
US20110186108A1 (en) | Ring architecture for high efficiency solar cells | |
JP2012204673A (en) | Series connection solar cell and solar cell system | |
WO2010048484A2 (en) | Optical spectral concentrator, sensors and optical energy power systems | |
US7994417B1 (en) | Optimal cell selection for series connection in Cassegrain PV module | |
KR20150048841A (en) | Photovoltaic system including light trapping filtered optical module | |
JPH05267703A (en) | Semiconductor device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SOLAR CASCADE OY, FINLAND Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:VAANANEN, MIKKO;REEL/FRAME:029526/0527 Effective date: 20121211 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- AFTER EXAMINER'S ANSWER OR BOARD OF APPEALS DECISION |
|
STCC | Information on status: application revival |
Free format text: WITHDRAWN ABANDONMENT, AWAITING EXAMINER ACTION |
|
STCV | Information on status: appeal procedure |
Free format text: EXAMINER'S ANSWER TO APPEAL BRIEF MAILED |
|
STCV | Information on status: appeal procedure |
Free format text: ON APPEAL -- AWAITING DECISION BY THE BOARD OF APPEALS |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |