Absorber, solar cell, and method for manufacturing absorber

Abstract

The invention relates to an absorber (15) of a solar cell, which has a molecular formula of (Cs, AZ) PbI3, (Cs, AZ) Pb (I, Br) 3, (Cs, AZ) Pb (I, Cl) 3 or (Cs, AZ) Pb (I, Br, Cl) 3, and has a perovskite structure, in which AZ represents azetidinium. The invention also relates to a solar cell comprising an absorber (15). The invention also relates to a method for producing an absorber, comprising: a) providing a substrate (1); b) thermally evaporating CsI and / or CsBr and / or CsCl to form a first vapour jet (4), the jet being generated starting from a first evaporation source (7); c) thermally evaporating PbI2 and / or PbBr2 and / or PbCl2 to form a second vapor jet (3), which is generated starting from a second evaporation source (6); d) thermally evaporating AZI, where AZI = azetidine hydroiodide or azetidinium iodide, forming a third steam jet (2), which is generated by a third evaporation source (5); wherein steps b), c) and d) are carried out simultaneously such that the first steam jet (4), the second steam jet (3) and the third steam jet (2) at least partially overlap, thereby forming an absorber on the provided substrate (1).

Description

Technical Field

[0001] The present invention relates to an absorber, a solar cell, and a method for preparing the absorber. In particular, the present invention relates to an absorber having a perovskite structure, a solar cell containing the absorber, and a method for preparing the absorber. Background Art

[0002] Solar cell absorbers with a perovskite structure are known. In the simplest case, the process by which the perovskite structure is formed by condensation on a substrate is represented by the following chemical formula:

[0003] AX(g)+BX 2 (g) →ABX 3 (s) (1),

[0004] When two gaseous starting materials AX and BX 2 ((g) represents gaseous state) When reacting, solid product ABX is generated 3 ((s) indicates solid) and deposited on a substrate. For example, A=CH 3 NH 3 + , B=Pb 2+ , X = halogen ion, such as chloride ion, bromide ion or iodide ion, the gaseous methylammonium halide reacts with the gaseous lead diiodide to form a solid methylammonium lead trihalide.

[0005] In a further development, multiple components of the same type may be used, so that the above chemical formula (1) becomes:

[0006] AX(g)+A'X(g)+BX 2 (g)→(A,A')BX 3 (s) (2) or

[0007] AX'(g)+A'X(g)+BX 2 (g)→(A,A')B(X,X') 3 (s) (3) or

[0008] AX'(g)+AX”(g)+A'X(g)+BX 2 (g)→(A,A')B(X,X',X') 3 (s) (4).

[0009] Among them, the material composition is mainly selected from PbI 2 and / or PbBr 2 and / or PbCl 2 As BX 2 , where B = Pb 2+, X = iodide, bromide or chloride; and CsI and / or CsBr and / or CsCl as AX, AX' or AX", wherein A = Cs + , X = iodide, bromide or chloride, X' = bromide, iodide or chloride, X" = bromide, iodide or chloride, and X, X' and X" are different from each other, even if they are all selected from the same group of halides; and also include organic components MAI (methylammonium iodide) and / or MABr (methylammonium bromide) and / or MACl (methylammonium chloride) or FAI (formamidine iodide) and / or FABr (formamidine bromide) and / or FACl (formamidine chloride), where A' = MA (methylammonium) or FA (formamidine), these materials are wet-chemically processed by co-evaporation. According to chemical formula (2), (3) or (4), depending on the starting materials used, the following organometallic halide perovskites can be formed: (CsMA)PbI 3 、(CsMA)Pb(I,Br) 3 、(CsMA)Pb(I,Cl) 3 、(CsMA)Pb(Br,Cl) 3 、(CsMA)Pb(I,Br,Cl) 3 、(CsMA)PbBr 3 、(CsMA)PbCl 3 、(CsFA)PbI 3 、(CsFA)Pb(I,Br) 3 、(CsFA)Pb(I,Cl) 3 、(CsFA)Pb(Br,Cl) 3 、(CsFA)Pb(I,Br,Cl) 3 、(CsFA)PbBr 3 or (CsFA)PbCl 3 The preparation methods of these absorbers generally involve wet chemical processes, such as spin coating. At present, this technology is still basically in the laboratory research and development stage. Therefore, there is still a need for a solar cell absorber suitable for large-scale industrial production. Summary of the invention

[0010] The object of the present invention is to provide an absorber, a solar cell and a method for producing an absorber which can be produced industrially on a large scale.

[0011] This object is achieved according to the invention by an absorber having the features of claim 1, a solar cell having the features of claim 3 and a method having the features of claim 5. Advantageous developments and variants are reflected in the dependent claims.

[0012] The invention is based on a novel perovskite absorber formed by a co-evaporation process. 3 、CsAZPb(I,Br) 3 、CsAZPb(I,Cl) 3 or CsAZPb(I,Br,Cl) 3 , where AZ = azetidinium, whose molecular formula is C 3 H 8 N + In this case, the perovskite structure is a crystal structure consisting of Cs, AZ, and Pb cations and I, optional Br, and optional Cl anions.

[0013] The present invention relates to novel compositions of absorbers, which are absorbers which can be prepared according to the invention by a co-evaporation process. Co-evaporation is the process of mixing absorber starting materials in the form of CsI (cesium iodide) and / or CsBr (cesium bromide) and / or CsCl (cesium chloride) with PbI 2 (lead diiodide) and / or PbBr 2 (lead dibromide) and / or PbCl 2 (Lead dichloride) and AZI (azetidine hydroiodide or azetidinium iodide) are simultaneously thermally evaporated to form an absorber having a crystal structure called a perovskite structure. The absorber is a hybrid material composed of organic and inorganic materials, i.e., an organometallic halide perovskite, in which electrons can be released from bound states and excited to higher energy levels under sunlight, while leaving behind positively charged empty states, i.e., "holes". The absorber is preferably used in solar cells.

[0014] The basic idea of ​​the present invention is to form the perovskite structure using raw materials that are more suitable for the evaporation process than the materials known in the prior art. This choice can be based on the vapor pressure of the material itself, or the vapor pressure of the individual ions in the material molecule. The choice of AZI as the raw material for the manufacture of the absorber of the present invention is mainly based on the following parameters: the vapor pressure of the components in the form of AZ (azetidine) and HI (hydrogen iodide), the molecular size, and the dipole moment / polarity of the molecule. CsAZPbI deposited in the co-evaporation process 3 、CsAZPb(I,Br) 3 、CsAZPb(I,Cl) 3 or CsAZPb(I,Br,Cl) 3 The absorber can be directly crystallized into the corresponding perovskite phase. Compared with the conventional perovskite absorber prepared in the laboratory according to the prior art, CsAZPbI 3 、CsAZPb(I,Br) 3 、CsAZPb(I,Cl) 3and CsAZPb(I,Br,Cl) 3 In terms of thermal stability and electrical properties (photoluminescence), the results are comparable or even better in some aspects.

[0015] The perovskite structure is a crystal structure in which Pb(X, possibly X', possibly X") 6 Octahedrons (where X = iodine ion, possible X' = bromide ion, possible X" = chloride ion) form a framework, in the gaps of which cesium (Cs) and AZ cations are embedded. The structure is preferably based on components with a high binding ratio of AX in the form of CsI, and / or AX' in the form of CsBr, and / or AX" in the form of CsCl, with the binding ratio preferably being greater than 60%, to form the basic structure; low binding ratio components A'X with a binding ratio of less than 40% are embedded in the basic structure, distorting the crystal structure. In this way, the absorber exhibits a distorted perovskite structure because Cs and AZ cations of different radii or diameters are embedded in the octahedrons.

[0016] According to the present invention, A'X=AZI (azetidine hydroiodide or azetidinium iodide) is used as an organic component in the process, and the perovskite structure is crystallized and the required thermal stability is achieved by a co-evaporation process. Compared with existing organic perovskite starting materials such as MAI and FAI, the evaporation of AZI is more controllable due to its lower vapor pressure. Compared with similar absorbers with perovskite structure according to the prior art, CsAZPbI 3 ,CsAZPb(I,Br) 3 ,CsAZPb(I,Cl) 3 or CsAZPb(I,Br,Cl) 3 The perovskite absorber is also more stable, especially under thermal stress: for example, it can operate stably at 100°C for more than 10 hours without degradation.

[0017] Furthermore, the absorbers of the invention are relatively stable in air and can be stored in air for more than 3 days without visible changes and / or degradation. When electrically characterized by photoluminescence (PL), the absorbers of the invention show good results comparable to perovskite crystal structures produced in the laboratory according to the prior art. The absorbers of the invention also show no visible changes in the photoluminescence measurements after thermal stress (>10 hours) or storage in air (up to 3 days). Compared to perovskite absorbers prepared in the laboratory according to the prior art, the absorbers of the invention remain stable even under enhanced solar irradiation, such as 10 times the solar irradiance, with no changes in the measured spectra.

[0018] The present invention relates to a (Cs, AZ)PbI 3,(Cs,AZ)Pb(I,Br) 3 ,(Cs,AZ)Pb(I,Cl) 3 or (Cs,AZ)Pb(I,Br,Cl) 3 The absorber has a molecular perovskite structure, where AZ is azetidinium. The absorber has low cost and can be very thin.

[0019] By introducing several components A, A' of the same type, for example according to formula (2), (3) or (4), where A = Cs + , A'=azetidinium, to form a mixed crystal to stabilize the perovskite structure, wherein in this case, X in formulas (2), (3) and (4) is an iodide ion, X' is a bromide ion, and X" is a chloride ion. Preferably, Pb ions form Pb(X, optionally X', optionally X") with X ions such as I ions, and optionally X' ions such as Br ions, and optionally X" ions such as Cl ions. 6 -Octahedral structure into which Cs and AZ ions are incorporated. This results in a distorted perovskite structure. One reason for the distorted perovskite structure is the different radii or diameters of the Cs and AZ cations.

[0020] The absorber is preferably designed as a thin layer with a layer thickness of <1 μm, preferably between 200 and 800 nm, more preferably between 300 and 700 nm, and even more preferably between 400 and 600 nm. Alternatively, the absorber is preferably designed as a wafer.

[0021] The present invention also relates to a solar cell with the absorber of the present invention, which has a low-cost, high-efficiency absorber, and the absorber can be very thin.

[0022] In a preferred embodiment, the solar cell is designed as a thin film solar cell. Alternatively or in addition, the solar cell is preferably designed as a stacked solar cell. The thickness of a thin film solar cell ranges from a few nanometers (nm) to tens of micrometers (μm), while the thickness of a wafer solar cell can reach 250 μm. Therefore, a thin film solar cell is hundreds of times thinner than a wafer solar cell.

[0023] The solar cell preferably has:

[0024] - front metallization as front electrode,

[0025] - an adjacent hole conductor for transporting positively charged holes to the front electrode,

[0026] an absorber according to the invention, which is adjacent to the hole conductor and absorbs solar radiation, thereby generating positive charge carriers ("holes") and negative charge carriers (electrons),

[0027] - an electron conductor adjacent to the absorber for conducting electrons to the back electrode, and

[0028] - Back side metallization as back side electrode.

[0029] The front side is the side facing the light, and the back side is the side facing away from the light.

[0030] Alternatively, the solar cell preferably has:

[0031] - front metallization as front electrode,

[0032] - an adjacent electron conductor for conducting electrons to the front electrode,

[0033] an absorber according to the invention, which is adjacent to the hole conductor and absorbs solar radiation, thereby generating positive charge carriers ("holes") and negative charge carriers (electrons),

[0034] - a hole conductor adjacent to the absorber for conducting the positively charged holes to the back electrode, and

[0035] - Back side metallization as back side electrode.

[0036] The solar cell is preferably designed as a stacked solar cell. The stacked solar cell preferably has at least two sub-cells, more preferably two sub-cells. Preferably, the sub-cell with the absorber of the present invention is the upper sub-cell of the stacked solar cell, and the upper sub-cell is the sub-cell closest to the incident light. When manufacturing the stacked solar cell, an integral process can be used to deposit the sub-cells directly on top of each other. Alternatively, the stacked solar cell can be manufactured in a manner that the sub-cells are produced separately from each other and mounted on top of each other in an electrically isolated manner.

[0037] The stacked solar cell preferably has the following structure, in the following order:

[0038] -front metallization,

[0039] - a conductive layer, such as an ITO layer (transparent indium tin oxide layer), for example with a layer thickness of 100 nm,

[0040] - Buffer and electron conductor layers such as SnO 2 layer, for example, a layer thickness of 20 nm,

[0041] - a passivation and hole blocking layer, such as a LiF / C60 layer, for example a LiF layer with a layer thickness of 1 nm and a C60 layer with a layer thickness of 18 nm,

[0042] - an absorber according to the invention, for example with a layer thickness of about 500 nm,

[0043] a hole conductor layer, for example a NiO / 2PACz layer (nickel oxide [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer),

[0044] - another conductive layer, such as an ITO layer, for example with a layer thickness of about 20 nm,

[0045] - TOPCon layer (charge carrier selective contact layer, where TOPCon = tunnel oxide passivation contact),

[0046] - another absorber, such as a silicon substrate, for example a p-type or n-type Cz-Si substrate,

[0047] - doped p + or + The silicon layer

[0048] - back side passivation layer,

[0049] - a back side metallization, wherein the back side metallization is in partial contact with the substrate via a back side passivation layer.

[0050] The present invention also relates to a method for preparing the absorbent body of the present invention, comprising:

[0051] a) Prepare the substrate,

[0052] b) thermally evaporating CsI and / or CsBr and / or CsCl to form a first vapor jet, the vapor jet being generated by a first evaporation source,

[0053] c) PbI 2 and / or PbBr 2 and / or PbCl 2 thermal evaporation to form a second steam jet, the steam jet being generated by a second evaporation source,

[0054] d) thermally evaporating AZI, wherein AZI=azetidine hydroiodide or azetidinium iodide, to form a third vapor jet, the vapor jet being generated by a third evaporation source,

[0055] Steps b), c) and d) are performed simultaneously, so that the first steam jet, the second steam jet and the third steam jet at least partially overlap, thereby forming an absorber on the prepared substrate.

[0056] Since steps b), c) and d) are carried out simultaneously, the deposition of the absorber is completed in one step. It is essential to the method that the steam jets overlap at least partially.

[0057] The thermal evaporation temperature of the starting materials varies: in a preferred embodiment, the thermal evaporation temperature of CsI and / or CsBr and / or CsCl in step b) is between 450 and 600°C.2 and / or PbBr 2 and / or PbCl 2 The thermal evaporation temperature of AZI in step d) is preferably between 100 and 250°C.

[0058] In a preferred embodiment, the method is carried out under high vacuum. The pressure range of high vacuum is preferably <10 - 5 mbar.

[0059] The mixing ratio of CsI and / or CsBr and / or CsCl to AZI is preferably between (75%-90%):(10%-25%). In other words, the mixing ratio of CsI to AZ and / or CsBr to AZI is between the first mixing ratio of 75%:25% and the second mixing ratio of 90%:10%. Preferably, PbI 2 and / or PbBr 2 and / or PbCl 2 Reaction with CsI and / or CsBr and / or CsCl and organic component AZI to convert into CsIAZPbI 3 、CsAZPb(I,Br) 3 、CsAZPb(I,Cl) 3 or CsAZPb(I,Br,Cl) 3 , wherein the mixing ratio of CsI and / or CsBr and / or CsCl to AZI is preferably (75%-90%):(10%-25%). This ensures that the formation basis of the perovskite structure is: a high binding ratio of AX component in the form of CsI and / or AX' component in the form of CsBr and / or AX" component in the form of CsCl, the high binding ratio is preferably >60%, and a low binding ratio of A'X component in the form of AZI, the low binding ratio is preferably <40%. One of the benefits of this is that the proportion of organic components is greatly reduced compared to other organic components such as FAI. In addition, the vapor pressure of AZI is lower than that of FAI, so it is more suitable for evaporation process, so using AZI instead of FAI can increase yield or lower equipment cost.

[0060] The absorber is preferably designed as a film. Alternatively, the absorber is preferably designed as a wafer.

[0061] In a preferred embodiment, the substrate is coated with the absorber layer in a static manner. Alternatively, the substrate is preferably coated with the absorber layer in an inline production facility. Both methods allow industrial production of the absorber. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The invention will be explained below with the aid of the embodiments shown in the drawings. These drawings are for illustrative purposes only and are not drawn to scale.

[0063] Figure 1 is a simplified diagram of the method of the present invention;

[0064] Figure 2 is a simplified diagram of an absorbent body not belonging to the present invention;

[0065] Figure 3 is a simplified diagram of the absorbent of the present invention;

[0066] Figure 4 The invention relates to a solar cell. DETAILED DESCRIPTION

[0067] Figure 1 is a simplified diagram of the method of the present invention. The method for manufacturing an absorber comprises: step a) preparing a substrate 1. The process is carried out in an inline production facility (not shown), in which the substrate 1 is conveyed in the direction indicated by the arrow. step b) thermally evaporating CsI and / or CsBr and / or CsCl to form a first vapor jet 4, which is generated from a first evaporation source 7; step c) evaporating PbI 2 and / or PbBr 2 and / or PbCl 2 Thermal evaporation is performed to form a second vapor jet 3, which is generated from a second evaporation source 6; step d) thermal evaporation is performed on AZI, wherein AZI = azetidine hydroiodide or azetidine ammonium iodide, to form a third vapor jet 2, which is generated by a third evaporation source 5. Steps b), c) and d) are performed simultaneously, so that the first vapor jet 4, the second vapor jet 3 and the third vapor jet 2 at least partially overlap, thereby forming a (Cs, AZ)PbI 3 ,(Cs,AZ)Pb(I,Br) 3 ,(Cs,AZ)Pb(I,Cl) 3 or (Cs,AZ)Pb(I,Br,CI) 3 Molecular formula of the perovskite structured absorber (not shown).

[0068] Figure 2 This is a schematic diagram of an absorber that does not belong to the present invention. The absorber has a perovskite structure and its molecular formula is CsPbI 3 , where Pb and Cs ions are cations and I ions are anions. The crystal structure is composed of PbI 6 - The basic structure formed by octahedron 31, Cs cation 30 is embedded in PbI 6 - In the gaps 32 between the octahedrons 31. The gaps 32 and PbI 6- The octahedra 31 are of the same size and arranged regularly.

[0069] Figure 3 is a schematic diagram of the absorber of the present invention. The crystal structure of the absorber is PbI 6 -Hybrid structure of octahedron 31, Cs + 30 and AZ + 33 embedded in PbI 6 - in the gaps 32 between the octahedrons 31. The diameter of the Cs cation 30 is smaller than the diameter of the AZ cation 33. Figure 2 Compared with the basic structure shown in FIG. 1 , the gaps 32 in the hybrid structure are distorted, i.e., the sizes are different. 6 -The arrangement of the octahedrons is also uneven, so the crystal structure is distorted. Figure 1 The absorbent body was prepared by the method shown.

[0070] Figure 4 The solar cell of the present invention is shown. It is designed as a stacked solar cell and has the following structure arranged in sequence:

[0071] - front metallization 11,

[0072] - a conductive layer 12, such as an ITO layer (transparent indium tin oxide layer), for example with a layer thickness of 100 nm,

[0073] - Buffer and electron conductor layer 13, such as SnO 2 layer, for example, a layer thickness of 20 nm,

[0074] a passivation and hole blocking layer 14, such as a LiF / C60 layer, for example a LiF layer with a layer thickness of 1 nm and a C60 layer with a layer thickness of 18 nm,

[0075] - Figure 3 The absorber 15 of the present invention shown has a layer thickness of about 500 nm, for example.

[0076] - Hole conductor layer 16, such as NiO / 2PACz layer (nickel oxide [2-(9H-carbazole-9-yl)ethyl]phosphonic acid layer)

[0077] - another conductive layer 17, such as an ITO layer, for example with a layer thickness of about 20 nm,

[0078] -TOPCon layer 18,

[0079] - another absorber 19, such as a silicon substrate, for example a p-type or n-type Cz-Si substrate,

[0080] - doped p + or + The silicon layer 34,

[0081] - a back side passivation layer 20,

[0082] A rear-side metallization 21 , wherein the rear-side metallization 21 has local contact 22 with the further absorber 19 via the rear-side passivation layer 20 .

[0083] List of reference numerals:

[0084] 1 substrate

[0085] 2 Third steam jet

[0086] 3 Second steam jet

[0087] 4 First steam jet

[0088] 5 The third evaporation source

[0089] 6 Second evaporation source

[0090] 7. The first evaporation source

[0091] 11 Front metallization

[0092] 12 Conductive layer

[0093] 13. Electron Conductor Layer

[0094] 14 Hole blocking layer

[0095] 15 Absorber

[0096] 16 Hole conductor layer

[0097] 17 Another conductive layer

[0098] 18 TOPCon

[0099] 19 Another Absorber

[0100] 20 Back passivation layer

[0101] 21 Back metallization

[0102] 22 Local contact

[0103] 30 Cs +

[0104] 31 PbI 6 -Octahedron

[0105] 32 Gap

[0106] 33 AZ +

[0107] 34 Silicon layer

Claims

1. An absorber (15) for a solar cell, which has a molecular formula of (Cs,AZ)PbI3, (Cs,AZ)Pb(I,Br)3, (Cs,AZ)Pb(I,Cl)3 or (Cs,AZ)Pb(I,Br,Cl)3 and has a perovskite structure, wherein AZ represents azetidinium.

2. The absorbent body (15) according to claim 1, characterized in that Pb, I and optionally Br and optionally Cl ions form a basic structure, and Cs and AZ ions are embedded in the basic structure.

3. A solar cell having an absorber (15) according to claim 1.

4. The solar cell according to claim 3, characterized in that: Designed as thin-film solar cells and / or tandem solar cells.

5. A method for preparing an absorbent body according to claim 1 or 2, comprising: a) preparing the substrate (1), b) thermally evaporating CsI and / or CsBr and / or CsCl to form a first vapor jet (4), the vapor jet being generated by a first evaporation source (7), c) thermally evaporating PbI2 and / or PbBr2 and / or PbCl2 to form a second vapor jet (3), the vapor jet being generated by a second evaporation source (6), d) thermally evaporating AZI, where AZI=azetidine hydroiodide or azetidinium iodide, to form a third vapor jet (2), which is generated from a third vaporization source (5), Wherein, steps b), c) and d) are performed simultaneously, so that the first steam jet (4), the second steam jet (3) and the third steam jet (2) at least partially overlap, thereby forming an absorber on the prepared substrate (1).

6. The method according to claim 5, characterized in that The thermal evaporation temperature of CsI and / or CsBr and / or CsCl in step b) is between 450 and 600°C, and / or the thermal evaporation temperature of PbCl2 and / or PbBr2 and / or PbCl2 in step c) is between 220 and 350°C, and / or the thermal evaporation temperature of AZI in step d) is between 100 and 250°C.

7. The method according to any one of claims 5 or 6, characterized in that: The method is carried out under high vacuum, preferably the pressure range of high vacuum is less than 10 -5 mbar.

8. The method according to any one of claims 5 to 7, characterized in that: The mixing ratio of CsI and / or CsBr and / or CsCl to AZI is between a first mixing ratio of 75%:25% and a second mixing ratio of 90%:10%.

9. The method according to any one of claims 5 to 7, characterized in that: The absorber is designed as a thin layer or wafer.

10. The method according to any one of claims 5 to 9, characterized in that: The substrate (1) is coated with the absorber layer in a static manner or in an inline production facility.

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