3-Terminal Tandem Photovoltaic Unit

Abstract

The present invention relates to a three-terminal tandem photovoltaic unit (1), which comprises: a first absorber layer (7) made of a perovskite-type compound; a second absorber layer (11, 11'); first and second interdigital front contacts (5a, 5b) arranged on the front side of the first absorber layer (7), the first front contact (5a) having a first polarity and the second front contact (5b) having a second polarity; back contacts (17, 17') having first and second polarities arranged on the back side of the second absorber layer (11, 11'); and an interface layer (9, 90, 9', 90') arranged between the second absorption layer (11, 11'), the interface layer (9, 90, 9', 90') including a first semiconductor sublayer (9a, 90a, 9a', 90a') doped according to a first polarity and a second sublayer (9b, 90b, 9b', 90b') doped according to a second polarity, and configured to transport carriers associated with a polarity different from that of the back contact (17, 17') from the second absorption layer (11, 11') to the first absorption layer (7) and collect them at a front contact (5a, 5b) having a polarity different from that of the back contact (17, 17').

Description

Technical Field

[0001] The present invention relates to the generation of solar power energy, and more particularly to a solar power unit capable of converting solar energy into electricity.

Background Art

[0002] With climate change, global warming, and the depletion of fossil fuels, many technologies for using alternative resources, particularly renewable energy resources, have been developed over the past few years.

[0003] One of the main technologies is to use photovoltaic cells to convert solar energy into electricity.

[0004] A solar cell includes a PN junction where light is absorbed to create pairs of electrons and holes, and counter electrodes that collect electrons on one side and holes on the other side.

[0005] One way to improve the efficiency of solar cells is to stack multiple solar cells to form a multi-junction, i.e., a tandem solar cell.

[0006] Although various forms of tandem solar cells have been developed, each configuration may have some drawbacks. For example, in a two-terminal (2T) configuration, current matching is required due to the series-connected sub-cells. Also, in a four-terminal (4T) configuration, more layers are required, which may increase the cost and may cause additional parasitic losses.

[0007] The three-terminal (3T) configuration may reduce the drawbacks provided by 2T and 4T terminals. However, in a 3T configuration, a comb-shaped back contact (IBC) is usually required, which requires high-quality materials such as n-type materials with long diffusion lengths, thus preventing the use of low-cost passivation emitter and rear cell (PERC), which are mass-produced products.

[0008] Accordingly, an object of the present invention is to provide a solar power generation unit with high efficiency and at the same time suppress the manufacturing cost of such a solar power generation unit.

Summary of the Invention

[0009] The present invention relates to a three-terminal tandem solar power generation unit, which - a first absorption layer made of a compound having a perovskite crystal structure and having a front side and a back side, - a second absorption layer having a front side and a back side, - first and second comb-shaped front contacts disposed on the front side of the first absorption layer, the first front contact having a first polarity and the second front contact having a second polarity, the first and second comb-shaped front contacts, - a back contact disposed on the back side of the second absorption layer and having a first or second polarity, - an interface layer disposed between the first and second absorption layers, including a first semiconductor sublayer doped according to the first polarity and a second sublayer doped according to the second polarity, and transporting carriers related to a polarity different from that of the back contact from the second absorption layer to the first absorption layer, and an interface layer configured to be collectable by a front contact having a polarity different from that of the back contact.

[0010] According to another aspect of the present invention, the interface layer is a tunnel junction layer.

[0011] According to a further aspect of the present invention, the interface layer is a recombination layer made of two sublayers of a transparent conductive oxide.

[0012] According to an additional aspect of the present invention, the second absorption layer is made of crystalline silicon.

[0013] According to another aspect of the present invention, the second absorption layer - a III-V semiconductor alloy, - a compound having a perovskite crystal structure, - copper indium gallium selenide "CIGS", - It is made from one of the alloys of cadmium telluride "CdTe".

[0014] According to a further aspect of the present invention, the first polarity corresponds to a p-type polarity having holes as the associated carriers, and the second polarity corresponds to an n-type polarity having electrons as the associated carriers.

[0015] According to an additional aspect of the present invention, the back contact has the first polarity and includes a back surface electric field, and the second absorption layer is doped according to the first polarity.

[0016] According to another aspect of the present invention, the tunnel junction includes a sublayer doped to a high concentration according to the first polarity and disposed in contact with the front side of the second absorption layer, and a sublayer doped according to the second polarity and disposed in contact with the back side of the first absorption layer.

[0017] According to a further aspect of the present invention, the back contact has the second polarity and the second absorption layer is doped according to the second polarity.

[0018] According to an additional aspect of the present invention, the tunnel junction includes a sublayer doped to a high concentration according to the second polarity and disposed in contact with the front side of the second absorption layer, and a sublayer doped according to the first polarity and disposed in contact with the back side of the first absorption layer.

[0019] According to another aspect of the present invention, the front and back contacts are passivation contacts.

[0020] According to a further aspect of the present invention, the first and second front contacts each include a hole transport layer "HTL" and an electron transport layer "ETL".

[0021] According to another aspect of the present invention, the hole transport layer is - nickel oxide "NiO X " 、 - molybdenum oxide "MoO X ", - tungsten oxide "WOX ", - 2,2’,7,7’-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9’-spirobifluorene “Spiro-OMeTAD”, - poly(triarylamine) “PTAA”, - poly(3-hexylthiophene) “P3HT”, - poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonic acid) “PEDOT:PSS”, - copper(I) thiocyanate “CuSCN”, - cobalt oxide “CoO X ”, - chromium oxide “CrO X ”, - copper(I) iodide “CuI”, - copper sulfide “CuS”, - copper oxide “CuO X ”, - vanadium oxide “Vo X ” and is made from one of the following, The electron transport layer is, - tin oxide “SnO X ”, - titanium oxide “TiO X ”, - zinc oxide “ZnO X ”, - carbon, C 60 and derivatives, - zirconia “ZrO X ”, - graphite, - graphene, - reduced graphene oxide “rGO” and is made from one of the following.

[0022] According to an additional aspect of the present invention, the front and back contacts include a metal grid or a transparent conductive oxide grid.

[0023] The present invention also relates to a manufacturing process for a three-terminal tandem solar power generation unit, - providing a light-transmissive substrate having a front and a back surface, - Depositing a back contact having a first or second polarity on the surface of the substrate; - Depositing a second absorption layer on the back contact; - Depositing a first highly doped semiconductor sublayer of a tunnel junction on the second absorption layer; - Depositing a second doped semiconductor sublayer of the tunnel junction on the first sublayer; - Depositing a first absorption layer made of a compound having a perovskite crystal structure on the second sublayer; - Depositing first and second comb-shaped front contacts on the first absorption layer, wherein the first front contact has a first polarity and the second front contact has a second polarity.

[0024] The present invention also relates to a manufacturing process of a three-terminal tandem photovoltaic unit, - Providing a crystalline silicon-based photovoltaic cell, the crystalline silicon-based photovoltaic cell comprising a crystalline silicon layer having a front side configured to face a side where light hits the crystalline silicon layer and a back side opposite to the front side, a first set of layers disposed on the back side of the crystalline silicon layer, and a second set of layers disposed on the front side of the crystalline silicon layer; - Removing the second set of layers of the crystalline silicon photovoltaic cell; - Depositing a first highly doped semiconductor sublayer of a tunnel junction on the front side of the crystalline silicon layer; - Depositing a second doped semiconductor sublayer of the tunnel junction on the first sublayer; - Depositing a first absorption layer made of a compound having a perovskite crystal structure on the second sublayer; - Depositing first and second comb-shaped front contacts on the first absorption layer, wherein the first front contact has a first polarity and the second front contact has a second polarity.

[0025] According to another aspect of the present invention, the step of removing the second set of layers includes an etching step and / or a polishing step using hydrofluoric acid or a mixture of hydrofluoric acid and nitric acid.

[0026] The present invention also relates to a method of operating a three-terminal tandem solar power generation unit, wherein the current generated between the first and second comb-shaped front contacts is adjusted so that the current generated in the first absorption layer and the current generated in the second absorption layer are balanced.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0028] The following results are examples. This specification refers to one or more embodiments, but each reference does not necessarily refer to the same embodiment, and furthermore, the features are not necessarily applicable only to one embodiment. It is also possible to combine the simple features of different embodiments to provide other embodiments.

[0029] The present invention relates to a tandem photovoltaic unit having three terminals. Such a tandem cell includes two different absorption layers arranged in series, these absorption layers having different bandgaps and being configured to absorb different portions of the light spectrum. The three terminals are obtained by using two comb-shaped contacts having different polarizations on one side of the tandem photovoltaic unit. In this case, the comb-shaped contacts are arranged on the front side of the tandem photovoltaic unit, thereby making it possible to use an existing standard cell as the back cell of the tandem photovoltaic unit. Further, one of the absorption layers is made of a compound having a perovskite-type crystal structure that provides high efficiency at limited cost.

[0030] FIG. 1 shows the different layers of a tandem photovoltaic unit 1 according to a first embodiment of the present invention. Arrow 3 represents the direction of light incidence. The front side of each layer corresponds to the side where the light first hits. Thus, the light reaches the front layer first with respect to the back layer.

[0031] The tandem photovoltaic unit 1 comprises - comb-shaped front contacts 5a and 5b, - a first absorption layer 7, - an interface layer 9 arranged on the back side of the first absorption layer 7, - a second absorption layer 11 arranged on the back side of the interface layer 9, - a back surface field layer 13, - a passivation layer 15, - a back contact layer 17.

[0032] Next, the possible compositions of the various layers will be described in more detail.

[0033] The comb-shaped surface contacts 5a, 5b can be made by two alternately arranged combs 50a, 50b having a first polarity and a second polarity different from the first polarity, respectively. The first and second polarities refer to n-type and p-type materials. The first and second alternately arranged combs 50a, 50b may refer to a hole transport layer (HTL) and an electron transport layer (ETL), respectively.

[0034] The p-type layer, i.e., the HTL, is for example - nickel oxide "NiO X " 、 - molybdenum oxide "MoO X ", - tungsten oxide "WO X ", - 2,2’,7,7’-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9’-spirobifluorene "spiro-OMeTAD", - poly(triarylamine) "PTAA", - poly(3-hexylthiophene) "P3HT", - poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonic acid) "PEDOT:PSS", - copper(I) thiocyanate "CuSCN", - cobalt oxide "CoO X ", - chromium oxide "CrO X ", - copper(I) iodide "CuI", - copper sulfide "CuS", - copper oxide "CuO X ", - vanadium oxide "Vo X ", and is made from one of the elements.

[0035] The n-type layer, i.e., the ETL, is for example - tin oxide "SnO X ", - titanium oxide "TiO X ", - zinc oxide "ZnO X ", - Carbon, C 60 and derivatives, - Zirconia "ZrO X ", - Graphite, - Graphene, - Graphene oxide "rGO", is made from one of the elements of.

[0036] The front contacts 5a, 5b also include thin conductive layers 51a, 51b made from a transparent conductive oxide such as indium tin oxide (ITO) or fluorine-doped tin oxide (FTO), or from a metal layer such as a silver layer. The thin conductive layers 51a, 51b are respectively disposed on the front sides of the first and second combs 50a, 50b arranged opposite to each other.

[0037] The first absorption layer 7 is made from a compound having a perovskite crystal structure. The term "perovskite" in the present invention means a material that can be represented by the formula "A""B""X"3, where "A" is at least one cation, "B" is at least one cation, and "X" is at least one anion. The cation "A" may be an organic, inorganic, or organo-inorganic cation. When the cation "A" is organic, the organic cation can have the formula (R1R2R3R4N)n+ or (R5R6N=CH-NR7R8)n+. Here, R is hydrogen, unsubstituted or substituted alkyl, or unsubstituted or substituted aryl, and n is 1 or more (for example, "+CH3NH3" refers to MA, "+HC(NH2)2" refers to FA, and "+C(NH2)3" refers to GA). When the cation "A" is inorganic, the cation can be selected from the group consisting of Ag+, Li+, Na+, K+, Rb+, Cs+, Be2+, Mg2+, Ca2+, Pb2+, Sr2+, Ba2+, Fe2+, Sc3+, Y3+, and La3+. The cation can be used as one or more ions (for example, (Mg, Fe)SiO3), YBaCuO3).

[0038] When the cation "A" is organo-inorganic, the cation can be used as one or more ions such as "A" = (M1n(R21-xR3x)(100-n)). Here, R is preferably an organic cation as described above, and M is preferably an inorganic cation contained as described above (for example, FA1-xGax"B""X"3, Csx(MAnFAL-n)(100-x)"B""X"3).

[0039] The cation "B" may be a metal cation selected from the group consisting of Pb2+, Sn2+, Ge2+, Bi2+, Cu2+, Au2+, Ag2+, Sb2+, Nb2+, Ti2+, Mg2+, Si2+, Ca2+, Sr2+, Cd2+, Ni2+, Mn2+, Fe2+, Zr4+, Co2+, Pd2+, Yb2+, Eu2+, Ce4+, and Tb4+.

[0040] The anion "X" may be selected from the group consisting of halide anions containing C1-, Br-, I-, F-, or chalcogenide anions containing O2-, S2-, Se2-, Te2-, or polyvalent anions containing BF4-, PF6-, SCN-. The anion may be used as one or more ions such as "X" = (R1-xRx). Here, R is the above anion. The present invention also includes other types of perovskites that can be refined (cuprate perovskites (La2-xBaxCuO4, YBa2Cu3O7, Ba2Mcu3O7)). Here, M is a rare earth ion such as Pr, Y, Nd, Sm, Gd, Dy, Ho). The metal perovskite may be manufactured based on the RT3M structure. Here, R is a rare earth ion, T is a transition metal ion (Pd, Rh, Ru), and M is a light metalloid (for example, B, C).

[0041] Therefore, the above definition regarding the scope of materials includes, but is not limited to, CH3NH3PbX3, Csx(CH3(NH2)2)1-xPbX3, Csx((CH3NH3)y(CH3(NH2)2)1-y)(1-x)PbX3, AxCsy((CH3NH3)z(CH3(NH2)2)1-z)1-yPbX3 (where A is an alkali metal (Li, Na, K, Rb)), BaTiO3, PbTiO3, CaTiO3, SrTiO3, PbZrO3, SrTiO3, KTaO3, KNbO3, NaNbO3, Pb(Mg1 / 3Nb2 / 3)O3, Pb(Zn1 / 3Nb2 / 3)O3, Pb(Mn1 / 3Sb2 / 3)O3, Pb(Co1 / 3Nb2 / 3)O3, Pb(Mn1 / 3Nb2 / 3)O3, Pb(Ni1 / 3Nb2 / 3)O3, Pb(Sb1 / 2Sn1 / 2)O3, Pb(Co1 / 2W1 / 2)O3, Pb(Mg1 / 2W1 / 2)O3, LiNbO3, LiTaO3, BiTiO3, NaTiO3, NaNbO3, KNbO3, La1-xSrxMnO3, La2NiO4, La2CoO4, GdBaCo2O5, PrBaCo2O5, NdBa1-xSrxCoO2O5, Ba1-xSrxCo1-yFeyO3, BiCr1-xGaxO3, NaNbO3, KNbO3, LaFeO3, LaCoxFe1-xO3, Lal-xSrxCoO3, LaSrNiO4, LaxSrx-1FeyBiy-1O3, La2NiO4, La2-xSrxCuO4, LaSrNi1-xAlxO4, LaMnO3, LaFeO3, LaCoO3, LaTi1-xCuxO3, LiTaO3, NaTaO3, KTaO3, CaTa2O6, SrTa2O6, BaTa2O6, (La1-xSrxCoO3, Pr1-xSrxCoO3, Sm1-xSrxCoO3, Gd1-xSrxCoO3, Tb1-xSrxCoO3, LaCoO3, La1-xSrxMnO3, LaCo1-xNixO3) compounds.

[0042] According to the first embodiment shown in FIG. 1, the interface layer 9 may refer to the tunnel junction layer 9.

[0043] The tunnel junction layer 9 includes a first semiconductor sub-layer 9a doped according to a first polarity and a second semiconductor sub-layer 9b doped at a high density according to a second polarity.

[0044] The first sub-layer 9a is, for example, a p-type layer made of nickel oxide (NiO X ), molybdenum oxide (MoO X ), or tungsten oxide (WO X ).

[0045] The second sub-layer 9b is made of, for example, crystalline silicon and is an n-type layer doped at a high concentration according to the second polarity by doping with, for example, boron or phosphorus.

[0046] According to the second embodiment shown in FIG. 2, the interface layer 90 refers to the recombination layer 90. The recombination layer 90 includes a first semiconductor sub-layer 90a made of a transparent conductive oxide doped according to a first polarity and a second semiconductor sub-layer 90b made of a transparent conductive oxide doped according to a second polarity. The other layers remain the same as in the first and second embodiments.

[0047] In the embodiments of FIGS. 1 and 2, the second absorption layer 11 has a first polarity. The second absorption layer 11 is made of crystalline silicon, or - a III-V semiconductor alloy, - a compound having a perovskite crystal structure as described above for the first absorption layer 7, - copper indium gallium selenide (CIGS), - an alloy of cadmium telluride (CdTe).

[0048] The back surface field layer 13 may be made of aluminum.

[0049] The passivation layer 15 is aluminum oxide / silicon nitride (AlO x / SiN x ), or silicon oxide / silicon nitride (SiO x / SiNx ) may be made from

[0050] The back contact layer 17 may be made of aluminum and may be obtained by screen printing.

[0051] It should be noted that texturing can be achieved in various layers of the tandem photovoltaic unit (front texture, back texture, or internal texture). All contacts can be passivated, and the tunnel junction layer 9 or the recombination layer 90 may further include other layers. However, when using the first absorption layer made of perovskite, it can be done without passivating the front contact.

[0052] Figure 3 shows a third embodiment of the tandem photovoltaic unit.

[0053] In this third embodiment, the tandem photovoltaic unit 1 includes - comb-shaped front contacts 5a and 5b, - the first absorption layer 7, - an interface layer 9' disposed on the back side of the first absorption layer 7, - a second absorption layer 11' disposed on the back side of the interface layer 9', - an emitter layer 12, - a passivation layer 15', - a back contact layer 17'.

[0054] In this embodiment, the comb-shaped front contacts 5a and 5b, and the first absorption layer 7 may be the same as those in the first and second embodiments shown in FIGS. 1 and 2.

[0055] The interface layer is a tunnel junction layer 9', and includes a first semiconductor sublayer 9a' doped according to the second polarity (n-type) and a second semiconductor sublayer 9b' doped at a high concentration according to the first polarity (p-type).

[0056] The first sublayer 9a' is, for example, tin oxide (SnO x ) or titanium oxide (TiO x)、 or zinc oxide (ZnO x ) is made from.

[0057] The second sub-layer 9b’ is made from, for example, highly doped crystalline silicon.

[0058] According to the fourth embodiment shown in FIG. 4, the interface layer is a recombination layer 90’ including a first semiconductor sub-layer 90a’ made from a transparent conductive oxide doped according to the first polarity, and a second semiconductor sub-layer made from a transparent conductive oxide 90b’ doped according to the second polarity. The other layers remain the same as in the third and fourth embodiments.

[0059] In the embodiments of FIGS. 3 and 4, the second absorption layer 11’ has the second polarity (n-type). The second absorption layer 11’ is made from, for example, crystalline silicon, or perovskite, or copper indium gallium selenide (CIGS), or cadmium telluride (CdTe).

[0060] An emitter layer 12 doped according to the first polarity. The emitter layer 12 is made from, for example, boron.

[0061] Aluminum oxide / silicon nitride (AlO X / SiN X ) or a passivation layer 15’ made from silicon oxide / silicon nitride (SiO X / SiN X ).

[0062] For example, a back contact layer 17’ made of aluminum. Also, the back contact layer 17’ may contain a certain proportion of silicon and can be obtained by physical vapor deposition (PVD).

[0063] Therefore, the tandem solar power generation unit 1 can move carriers related to a polarity different from that of the back contact from the second absorption layer to the first absorption layer, and further collect the carriers at a front contact having a polarity different from that of the back contact.

[0064] In the case of the first and second embodiments shown in FIGS. 1 and 2, the tandem photovoltaic unit 1 is configured such that carriers related to the second polarity (electrons) are transported from the second absorption layer to the first absorption layer, and further, the carriers are collected at the surface contact related to the second polarity (n-type).

[0065] In the case of the third and fourth embodiments shown in FIGS. 3 and 4, the tandem photovoltaic unit 1 is configured such that carriers related to the first polarity (holes) are transported from the second absorption layer to the first absorption layer, and the carriers are collected at the surface contact related to the first polarity (p-type).

[0066] The characteristics of the first 7 and second 11, 11' absorption layers, particularly their thicknesses, are selected such that the current generated by the first absorption layer 7 and the current generated by the second absorption layers 11, 11' are substantially the same.

[0067] Furthermore, as shown in FIG. 5, in order to determine whether the current generated by the first absorption layer 7 matches the current generated by the second absorption layers 11, 11', the current I measured between the surface contacts 5a, 5b IFC and the current I between the surface contacts 5a, 5b and the back contacts 17, 17' F-B are monitored. In the case of a difference or mismatch, a part of the current I IFC is extracted or reinjected in order to optimize the overall efficiency of the tandem photovoltaic unit. The present invention also relates to the use or method for operating the three-terminal tandem solar power generation unit 1, and the current generated between the first and second comb-shaped surface contacts is adjusted such that the current generated by the first absorption layer 7 matches the current generated by the second absorption layers 11, 11'.

[0068] FIG. 6 shows a flowchart of different steps of the manufacturing process according to the first embodiment.

[0069] The first step 101 refers to the step of providing a light-transmissive substrate having a back surface and a front surface.

[0070] The second step 102 refers to the step of depositing the back contact layers 17, 17' having the first or second polarity on the surface of the substrate. The back contact layer may refer to an aluminum layer and may be deposited according to the co-evaporation technique. Alternatively, the aluminum layer may be screen printed. Further, the second step 102 may refer to depositing the passivation layers 15, 15' or the emitter layer 12.

[0071] The third step 103 refers to the step of depositing an absorption layer corresponding to the second absorption layers 11, 11' on the front side of the back contact layers 17, 17' (or perhaps on the front side of the passivation layers 15, 15 or the emitter layer 12).

[0072] The fourth step 104 refers to the step of depositing the first highly doped semiconductor sub-layers 9b, 9b', 90b, 90b' of the tunnel junction on the front side of the second absorption layers 11, 11'.

[0073] The fifth step 105 refers to the step of depositing the second doped semiconductor sub-layers 9a, 9a', 90a, 90a' of the tunnel junction on the front side of the first sub-layers 9b, 9b', 90b, 90b'.

[0074] The sixth step 106 refers to the step of depositing an absorption layer corresponding to the first absorption layer 7 made of a compound having a perovskite crystal structure on the front side of the second sub-layers 9a, 9a', 90a, 90a'.

[0075] The seventh step 107 refers to the step of depositing the first and second comb-shaped front contacts 5a, 5b on the front side of the first absorption layer 7, where the first front contact 5a has, for example, the first polarity and the second front contact 5b has, for example, the second polarity.

[0076] Figure 7 represents a flowchart of different steps of the manufacturing process according to the second embodiment. The gist of this embodiment is to modify an existing solar cell in order to obtain a tandem photovoltaic unit according to the present invention. In particular, the existing solar cell is selected for its low cost in order to limit the overall cost and the tandem photovoltaic unit.

[0077] The first step 201 is a step of providing a crystalline silicon-based photovoltaic cell, which comprises an absorption layer made of crystalline silicon, a first set of layers arranged on the back side of the crystalline silicon layer, for example, a back contact layer, and a second set of layers arranged on the front side of the crystalline silicon layer, for example, a front contact layer. Such solar cells are mass-produced and available at low cost.

[0078] The second step 202 refers to the step of removing the second set of layers of the crystalline silicon photovoltaic cell. Such removal is performed by an etching and / or polishing process. The etching product may be hydrofluoric acid or a mixture of hydrofluoric acid and nitric acid.

[0079] The third step 203 refers to the step of depositing a first highly doped semiconductor sublayer of a tunnel junction on the front side of the crystalline silicon layer.

[0080] The fourth step 204 refers to the step of depositing a second doped semiconductor sublayer of a tunnel junction on the first sublayer.

[0081] The fifth step 205 refers to the step of depositing a first absorption layer made of a compound having a perovskite-type crystal structure on the second sublayer.

[0082] The sixth step 206 refers to the step of depositing first and second comb-shaped front contacts on the first absorption layer, the first front contact having a first polarity and the second front contact having a second polarity.

[0083] Note that other steps, particularly the deposition of additional layers, may be added to the manufacturing process disclosed based on FIGS. 6 and 7 without departing from the scope of the present invention.

[0084] Accordingly, with the present invention, it is possible to obtain an efficient 3T tandem solar power generation unit in which the surface solar cell is connected in series with the back surface solar cell. The tandem power generation unit includes a comb-shaped front contact that enables the use of available mass-produced back cells to optimize the overall efficiency / cost ratio while limiting the overall size.

Claims

1. A three-terminal tandem photovoltaic unit (1), comprising: - A first absorption layer (7) made of a compound having a perovskite crystal structure and having a front side and a back side on which light is incident; - A second absorption layer (11, 11') located on the back side of the first absorption layer (7) and having a front side and a back side; - First and second comb-shaped front contacts (5a, 5b) disposed on the front side of the first absorption layer (7), wherein the first comb-shaped front contact (5a) has a first polarity and the second comb-shaped front contact (5b) has a second polarity; - A back contact (17, 17') disposed on the back side of the second absorption layer (11, 11') and having the first or second polarity; - An interface layer (9, 90, 9', 90') disposed between the first (7) and second (11, 11') absorption layers, the interface layer (9, 90, 9', 90') including a first semiconductor sublayer (9a, 90a, 9a', 90a') doped according to the first polarity and a second sublayer (9b, 90b, 9b', 90b') doped according to the second polarity, and transporting carriers related to a polarity different from that of the back contact (17, 17') from the second absorption layer (11, 11') to the first absorption layer (7), the interface layer (9, 90, 9', 90') being configured to be collectable by the first and second comb-shaped front contacts (5a, 5b) having a polarity different from that of the back contact (17, 17');

2. The three-terminal tandem photovoltaic unit (1) according to claim 1, wherein the interface layer (9, 90, 9', 90') is a tunnel junction layer.

3. The three-terminal tandem photovoltaic unit (1) according to claim 1, wherein the interface layer (9, 90, 9', 90') is a recombination layer made of two sublayers of a transparent conductive oxide, and the two sublayers are the first semiconductor sublayer (9a, 90a, 9a', 90a') and the second sublayer (9b, 90b, 9b', 90b').

4. The three-terminal tandem photovoltaic unit (1) according to any one of claims 1 to 3, wherein the second absorption layer (11, 11') is made of crystalline silicon.

5. The second absorption layer (11, 11') is: - A III-V semiconductor alloy; - A compound having a perovskite crystal structure; - Copper indium gallium selenide "CIGS", - Cadmium telluride "CdTe", the three-terminal tandem solar power generation unit (1) according to any one of claims 1 to 3, made from one of them.

6. The three-terminal tandem solar power generation unit (1) according to any one of claims 1 to 5, wherein the first polarity corresponds to a p-type polarity having holes as related carriers, and the second polarity corresponds to an n-type polarity having electrons as related carriers.

7. The three-terminal tandem solar power generation unit (1) according to claim 6, wherein the back contacts (17, 17') have the first polarity, and the second absorption layer (11, 11') is doped according to the first polarity.

8. The three-terminal tandem solar power generation unit (1) according to claim 7, wherein the interface layer (9, 90, 9', 90') is doped according to the first polarity and is in contact with the front side of the second absorption layer (11, 11') and includes a second sub-layer (9b, 90b, 9b', 90b'), and is doped according to the second polarity and is in contact with the back side of the first absorption layer (7) and includes a first semiconductor sub-layer (9a, 90a, 9a', 90a').

9. The three-terminal tandem solar power generation unit (1) according to claim 6, wherein the back contacts (17, 17') have the second polarity, and the second absorption layer (11, 11') is doped according to the second polarity.

10. The three-terminal tandem solar power generation unit (1) according to claim 9, wherein the interface layer (9, 90, 9', 90') is doped according to the second polarity and is in contact with the front side of the second absorption layer (11, 11') and includes a second sub-layer (9b, 90b, 9b', 90b'), and is doped according to the first polarity and is in contact with the back side of the first absorption layer (7) and includes a first semiconductor sub-layer (9a, 90a, 9a', 90a').

11. The three-terminal tandem solar power generation unit (1) according to any one of claims 1 to 10, wherein the first and second comb-shaped front contacts and back contacts (5a, 5b, 17, 17') are passivation contacts.

12. The three-terminal tandem solar power generation unit according to claim 6, wherein the first comb-shaped front contact (5a) includes a hole transport layer "HTL", and the second comb-shaped front contact (5b) includes an electron transport layer "ETL".

13. The hole transport layer is - Nickel oxide "NiO" Ｘ " 、 - Molybdenum Oxide "MoO Ｘ " - Tungsten Oxide "WO Ｘ ", - 2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene "Spiro-OMeTAD", - poly(triarylamine) "PTAA", - poly(3-hexylthiophene) "P3HT", - poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonic acid) "PEDOT:PSS", - copper(I) thiocyanate "CuSCN", - Cobalt oxide "CoO" Ｘ ", - Chromium oxide "CrO Ｘ ", - copper(I) iodide "CuI", - copper sulfide "CuS", - Copper oxide "CuO" Ｘ ", - Vanadium oxide "Vo Ｘ ", made from one of them, The electron transport layer is - Tin oxide "SnO Ｘ " - Titanium oxide "TiO Ｘ ", - Zinc Oxide "ZnO" Ｘ ", - carbon, C ６０ and derivatives, - Zirconia "ZrO Ｘ " - graphite, - graphene, - reduced graphene oxide "rGO", and is made from one of them, the three-terminal tandem solar power generation unit (1) according to claim 12.

14. The first and second comb-shaped front contacts and back contacts (5a, 5b, 17, 17') include a metal or a transparent conductive oxide, and the three-terminal tandem solar power generation unit (1) according to any one of claims 1 to 13.

15. A manufacturing process of a three-terminal tandem solar power generation unit (1), comprising: - a step (101) of providing a light-transmissive substrate having a front surface and a back surface; - a step (102) of depositing a back contact having a first or second polarity on the front surface of the light-transmissive substrate; - a step (103) of depositing a second absorption layer on the back contact; - a step (104) of depositing a first doped semiconductor sublayer on the second absorption layer; - a step (105) of depositing a second doped semiconductor sublayer for forming a tunnel junction on the first doped semiconductor sublayer; - a step (106) of depositing a first absorption layer made from a compound having a perovskite crystal structure on the second doped semiconductor sublayer; - a step (107) of depositing first and second comb-shaped front contacts on the first absorption layer, wherein the first comb-shaped front contact has a first polarity and the second comb-shaped front contact has a second polarity, and the manufacturing process in which the first absorption layer and the second absorption layer are electrically connected by the tunnel junction.

16. A manufacturing process of a tandem solar power generation unit, comprising - A step of providing a crystalline silicon-based photovoltaic cell, wherein the crystalline silicon-based photovoltaic cell includes a front side configured to face the side where light hits the crystalline silicon layer, and a back side opposite to the front side, a crystalline silicon layer, a first layer disposed on the back side of the crystalline silicon layer, and a second layer disposed on the front side of the crystalline silicon layer, step (201); - A step (202) of removing the second layer of the crystalline silicon photovoltaic cell; - A step (203) of depositing a first doped semiconductor sublayer on the front side of the crystalline silicon layer; - A step (204) of depositing a second doped semiconductor sublayer for forming a tunnel junction on the first doped semiconductor sublayer; - A step (205) of depositing a first absorption layer (7) made of a perovskite crystal structure on the second doped semiconductor sublayer; - A step of depositing first and second comb-shaped front contacts (5a, 5b) on the first absorption layer, wherein the first comb-shaped front contact has a first polarity and the second comb-shaped front contact has a second polarity, step (206), wherein the first absorption layer and the crystalline silicon layer are electrically connected by the tunnel junction, manufacturing process.

17. The manufacturing process according to claim 16, wherein the step (202) of removing the second layer includes an etching step and / or a polishing step using hydrofluoric acid or a mixture of hydrofluoric acid and nitric acid.

18. A method of operating a three-terminal tandem solar power generation unit according to any one of claims 1 to 14, wherein the current generated between the first and second comb-shaped front contacts (5a, 5b) is adjusted so that the current generated in the first absorption layer (7) and the current generated in the second absorption layer (11, 11') are balanced.

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