Method for producing a solar cell

Abstract

The invention relates to a method for producing a solar cell comprising a self-organizing monolayer (61), having the following steps: a) preconditioning a solar cell precursor (60) in a preconditioning zone, and b) coating the preconditioned solar cell precursor (60) with the self-organizing monolayer (61) in a coating zone (33), wherein the solar cell precursor (60) is transported through the preconditioning zone and the coating zone (33) one after the other by means of a horizontal transport system while at least partly contacting said transport system on one face, thereby being preconditioned in the preconditioning zone and then coated in the coating zone (33) on one face.

Description

[0001] Title: Method for producing a solar cell

[0002] Description:

[0003] The invention relates to a method for producing a solar cell. The solar cell can be a single-junction solar cell or a multi-junction solar cell, also referred to as a tandem solar cell. A tandem solar cell comprises several solar cells, also referred to as subcells, which are stacked one above the other. A distinction is made between mechanically stacked tandem solar cells, in which the subcells are manufactured separately, and monolithic tandem solar cells, in which all subcells are constructed on the same substrate.

[0004] Solar cells featuring a SAM (self-assembled monolayer) are known. However, the SAM has so far only been realized on a laboratory scale and with low throughput. However, there is a need to produce a solar cell with a SAM on an industrial scale.

[0005] It is an object of the invention to provide a method for producing a solar cell with which a solar cell with a self-organizing monolayer can be produced on an industrial scale.

[0006] According to the invention, the object is achieved by a method having the features of patent claim 1. Advantageous further developments and modifications are specified in the subclaims.

[0007] In this process, the solar cell precursor is transported through various zones of a system using a horizontal transport system and treated with single-sided treatment steps. The focus here is on the formation of the SAM on the solar cell precursor, which is part of the layer structure of the solar cell. The process is a strictly single-sided process.The invention relates to a method for producing a solar cell with a self-assembling monolayer, comprising the following steps: a) preconditioning a solar cell precursor in a preconditioning zone, b) coating the preconditioned solar cell precursor with the self-assembling monolayer in a coating zone, wherein the solar cell precursor is transported successively through the preconditioning zone and the coating zone by means of a horizontal transport system, at least partially touching one side thereof, and is preconditioned on one side in the preconditioning zone and subsequently coated in the coating zone.

[0008] The method according to the invention enables the coating of the solar cell precursor with the SAM in mass production. The applied SAM is part of the structure of the manufactured solar cell. Using the method, not only one solar cell precursor can be coated, but a large number of solar cell precursors can be transported and coated one after the other and / or side by side through the various zones of the system. By integrating several process steps in the system, the method simplifies the entire process flow of coating the solar cell precursor with the SAM, including upstream and, if necessary, downstream surface conditioning. Preconditioning is essential to ensure good chemical bonding of the SAM molecules to the surface of the solar cell precursor to be coated. The advantage of the method is its easy scalability and the strict single-side treatment of the solar cell precursor.This allows very low consumption, even of a SAM precursor, and all process steps are advantageously integrated into the system. The sequence of the process steps can be adapted via the configuration of the system. This also makes it possible to omit or add individual process steps. The method is used to produce a single-junction solar cell or a multi-junction solar cell. The single-junction solar cell is designed as a single solar cell, while the multi-junction solar cells have several sub-cells. The method is preferably designed to produce a plurality of solar cells with a self-assembling monolayer, wherein the plurality of solar cell precursors are transported one behind the other and / or next to one another through the preconditioning zone and then through the coating zone by means of the horizontal transport system, at least partially touching one side of the system.

[0009] The system designed to carry out the method is preferably an inline system containing the horizontal transport system. The zones are preferably designed as exchangeable and / or modifiable system modules, each having an assigned function. The horizontal transport system is preferably designed to transport a plurality of solar cell precursors sequentially and / or side by side through the entire system. System zones are preferably designed to carry out a full-surface treatment of the solar cell precursor on one side of the solar cell precursor. Its treatment is carried out exclusively on one side.

[0010] In a preferred embodiment, step a) comprises a pre-cleaning of the solar cell precursor, in which the solar cell precursor is transported through a pre-cleaning zone and pre-cleaned on one side. The pre-cleaning preferably comprises washing the solar cell precursor on one side with ethanol. This ensures good preconditioning. Following the pre-cleaning, the solar cell precursor is preferably dried to remove cleaning solution from the pre-cleaned solar cell precursor.

[0011] Alternatively or additionally, step a) preferably comprises a pretreatment of the solar cell precursor, in which the solar cell precursor is transported through a pretreatment zone and pretreated on one side. The pretreatment preferably comprises a one-sided exposure of the solar cell precursor to ozone, UV radiation, O2 and / or N2 plasma. The pretreatment preferably comprises a one-sided exposure of the solar cell precursor to ozone and / or UV radiation. This achieves good preconditioning.

[0012] In a preferred embodiment, the solar cell precursor is preconditioned in step a) by washing with ethanol, water, or ethanol / water mixtures and ozone pretreatment. This further ensures good preconditioning.

[0013] The solar cell precursor is treated on one side in the treatment zones, particularly coated on one side in the coating zone. This does not preclude the possibility that chemicals or processes may inadvertently reach the non-treated side of the solar cell precursor, particularly the side being coated, via the transport rollers of the transport system.

[0014] Preferably, in step b), the solar cell precursor is coated over its entire surface on one side, on the side opposite the side that contacts the transport system. Preferably, the solar cell precursor is dried after coating to remove any solvent from the coating material.

[0015] Preferably, a coating material used in step b) for coating the solar cell precursor with the self-assembling monolayer is selected from the group consisting of: 2PACz ([2-(9H-carbazol-9-yl)ethyl]phosphonic acid), MeO-2PACz ([2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid), Me-4PACz ([4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid), Me-2PACz ([2-(3,6-dimethyl-9H-carbazol-9-yl)ethyl]phosphonic acid), Br-2PACz ([2-(3,6-dibromo-9H-carbazol-9-yl)ethyl]phosphonic acid). Preferably, 2PACz is used in step b). The self-assembled monolayer acts preferentially as a hole-conducting layer in a tandem solar cell.In a preferred embodiment, following step b), a step c) of thermally treating the solar cell precursor coated with the self-assembled monolayer is carried out in an annealing zone. The solar cell precursor is transported through the annealing zone by means of the horizontal transport system, touching the transport system on one side, and is thermally treated. This allows the solvent used during the coating process to be removed.

[0016] Additionally, following step b) or c), a step d) of post-cleaning the solar cell precursor coated with the self-assembled monolayer can be performed in a post-cleaning zone. The solar cell precursor is transported through the post-cleaning zone by means of the horizontal transport system, touching the transport system on one side, and is post-cleaned on one side in the post-cleaning zone. The post-cleaning preferably includes washing the solar cell precursor. This removes excess material used to coat the solar cell precursor.

[0017] Preferably, step b) comprises a doctor blade coating, slot-die deposition, and / or spray coating and / or droplet coating. In step b), spray and / or slot-die systems and / or droplet strips are preferably used to achieve a one-sided coating.

[0018] In a preferred embodiment, the horizontal transport system has a plurality of transport rollers, wherein the transport rollers rotate in a direction of rotation, so that a solar cell precursor resting on them is transported in the transport direction through the preconditioning zone, the coating zone and, if applicable, the annealing zone and, if applicable, the post-cleaning zone.

[0019] The solar cell to be produced is preferably a tandem solar cell. In a preferred embodiment, the solar cell precursor comprises a lower sub-cell of the tandem solar cell, on which a recombination layer is arranged, which is preconditioned in step a) and coated in step b).

[0020] The lower subcell preferably has a silicon-based absorber. The recombination layer is preferably formed as a TCO (transparent conductive oxide) layer, more preferably as an ITO (indium tin oxide) layer.

[0021] Preferably, the lower sub-cell of the tandem solar cell has a layer structure in the specified order:

[0022] - an electrically conductive layer,

[0023] - an absorber such as a silicon substrate in the form of a p-type or n-type Cz-Si substrate,

[0024] - a backside passivation,

[0025] - a backside metallization, wherein the backside metallization has local contacts with the absorber due to the backside passivation, wherein the recombination layer to be coated by the method according to the invention is arranged on the electrically conductive layer.

[0026] Preferably, a perovskite absorber, for example Cso,o5(MAo,83, FAo,i7)o,95Pb(lo,83, Bro,17)3, is deposited on the self-assembling monolayer following step b), optionally c) or d).

[0027] The method preferably further comprises a loading step in which the solar cell precursor is loaded onto the horizontal transport system. The loading step takes place before step a). The method preferably further comprises an unloading step in which the solar cell precursor is unloaded from the horizontal transport system. The unloading step represents the final method step. The method is preferably carried out in a system configured such that the transport system transports the solar cell precursor through the system during the entire execution of the method. The transport system preferably transports a plurality of solar cell precursors through the system side by side and / or one after the other.

[0028] Further advantages and features of the method are explained using preferred embodiments described below. However, the figures are not drawn to scale, but are to be understood purely schematically and as examples.

[0029] They show:

[0030] Fig. 1 is a cross-sectional view of a tandem solar cell that can be produced using the method according to the invention, and

[0031] Fig. 2 shows a plant in which the method according to the invention is carried out.

[0032] Fig. 1 shows a cross-sectional view of a tandem solar cell that can be produced using the method according to the invention. It has the following structure in the order given:

[0033] - a front metallization 11 , which comprises, for example, silver,

[0034] - an electrically conductive layer 12 such as an ITO layer,

[0035] - a buffer and electron conductor layer 13 such as an SnO layer,

[0036] - a passivation and hole blocking layer 14 such as a C60 layer,

[0037] - an absorber 15, e.g. a perovskite absorber such as Cso,o5(MAo,83, FAo,i7)o,95Pb(lo,83, Bro, 17)3,

[0038] - a hole-conducting layer 16, which represents the SAM or self-assembling monolayer, e.g. 2 PACz ([2-(9H-carbazol-9-yl)ethyl]phosphonic acid),

[0039] - a recombination layer 17 such as an ITO layer,

[0040] - a further electrically conductive layer 21, - a further absorber 22 such as a silicon substrate in the form of a p-type or n-type Cz-Si substrate,

[0041] - a backside passivation 23,

[0042] - a backside metallization 24, wherein the backside metallization 24 has local contacts 25 through the backside passivation 23 with the further absorber 22.

[0043] The tandem solar cell comprises an upper subcell 1 with layers 11 to 17 and a lower subcell 2 with layers 22 to 25. Subcell 1 comprises the perovskite-based absorber 15, while subcell 2 comprises the silicon-based absorber 22.

[0044] Fig. 2 shows a system in which the method according to the invention is carried out. To carry out the method, the system has a plurality of zones, each designed to treat a solar cell precursor 60, and a horizontal transport system with transport rollers 40, which is arranged and designed to transport the solar cell precursor 60 lying on one side through the zones. Several solar cell precursors are shown, which are transported through the various zones of the system. The system has a loading zone 30, in which the transport system is loaded with the solar cell precursor 60 so that it touches the transport system with one side. The loading zone 30 is followed by a preconditioning zone. The preconditioning zone has a precleaning zone 31, in which the solar cell precursor 60 is first precleaned on one side by means of a cleaning device 41, e.g.with ethanol, and then dried by means of a drying device 42, and / or a pretreatment zone 32 in which the solar cell precursor 60 is pretreated on one side, for example using ozone.

[0045] The pretreatment zone 32 is followed by a coating zone 33, in which the pretreated solar cell precursor 60 is coated on one side with a self-assembling monolayer 61 by means of a coating device 43 and optionally dried by means of a further drying device 42. The coating zone 33 is followed by an optional annealing zone

[0046] 34, in which the solar cell precursor 60 coated with the self-assembled monolayer 61 is thermally treated in a heat zone 39. The optional annealing zone 34 is followed by an optional post-cleaning zone

[0047] 35, in which the solar cell precursor 60 coated with the self-assembled monolayer 61 is subsequently cleaned using a cleaning device 41 and dried using a further drying device 42. The optional post-cleaning zone 35 is followed by an optional drying zone

[0048] 36, in which the solar cell precursor 60 coated with the self-assembled monolayer 61 is dried. The optional drying zone 36 is followed by a discharge zone 37, in which the solar cell precursor 60 coated with the self-assembled monolayer 61 is discharged from the transport system.

[0049] The system can be used to carry out the method according to the invention for producing a solar cell 60 with a self-organizing monolayer 61, which comprises the following steps:

[0050] A step a) preconditioning a solar cell precursor 60 in the preconditioning zone, i.e. in the pre-cleaning zone 31 and / or the pretreatment zone 32, and a step b) coating the preconditioned solar cell precursor 60 with a self-assembling monolayer 61 in the coating zone 33, wherein the solar cell precursor 60 is transported successively through the preconditioning zone and the coating zone 33 by means of the horizontal transport system, at least partially touching one side thereof, and is preconditioned on one side in the preconditioning zone on the side facing away from the transport system and then coated on one side in the coating zone 33. The solar cell precursor 60 coated with the self-assembling monolayer 61 can then be thermally treated and / or post-cleaned. In this way, for example, the hole-conductor layer 16 of the tandem solar cell shown in Fig. 1 can be produced.List of reference symbols:.

[0051] T Transport direction

[0052] 1 upper subcell

[0053] 11 Front metallization

[0054] 12 electrically conductive layer

[0055] 13 Buffer layer

[0056] 14 Electron conductor layer

[0057] 15 absorbers

[0058] 16 hole conductor layer

[0059] 17 Recombination layer

[0060] 2 lower subcell

[0061] 21 additional electrically conductive layer

[0062] 22 additional absorbers

[0063] 23 Backside passivation

[0064] 24 Backside metallization

[0065] 25 local contact

[0066] 3 Appendix

[0067] 30 Loading zone

[0068] 31 Pre-cleaning zone

[0069] 32 Pretreatment zone

[0070] 33 Coating zone

[0071] 34 Annealing zone

[0072] 35 Post-cleaning zone

[0073] 36 dry zone

[0074] 37 Unloading zone

[0075] 39 Heat zone

[0076] 40 transport rollers

[0077] 41 Cleaning device

[0078] 42 Drying device

[0079] 43 Coating device

[0080] 60 solar cell precursors

[0081] 61 self-assembling monolayer

Claims

Patent claims:

1. A method for producing a solar cell with a self-assembling monolayer (61), comprising the following steps: a) preconditioning a solar cell precursor (60) in a preconditioning zone, b) coating the preconditioned solar cell precursor (60) with the self-assembling monolayer (61) in a coating zone (33), wherein the solar cell precursor (60) is transported successively through the preconditioning zone and the coating zone (33) by means of a horizontal transport system, at least partially touching one side thereof, and is preconditioned on one side in the preconditioning zone and subsequently coated in the coating zone (33).

2. Method according to claim 1, characterized in that step a) comprises a pre-cleaning of the solar cell precursor (60), in which the solar cell precursor (60) is transported through a pre-cleaning zone (31) and is pre-cleaned on one side, and / or a pre-treatment of the solar cell precursor (60), in which the solar cell precursor (60) is transported through a pre-treatment zone (32) and is pre-treated on one side.

3. Method according to claim 2, characterized in that the pre-cleaning comprises a one-sided washing of the solar cell precursor (60) with ethanol and / or the pre-treatment comprises a one-sided exposure of the solar cell precursor (60) to ozone, UV radiation, O2 and / or N2 plasma.

4. Method according to one of the preceding claims, characterized in that following step b) a step c) thermally treating the self-assembled monolayer (61 ) coated solar cell precursor (60) in an annealing zone (34), wherein the solar cell precursor (60) is transported through the annealing zone (34) by means of the horizontal transport system, touching the transport system on one side, and is thermally treated. Method according to one of the preceding claims, characterized in that a step d) post-cleaning the solar cell precursor (60) coated with the self-assembled monolayer (61) is carried out in a post-cleaning zone (35), wherein the solar cell precursor (60) is transported through the post-cleaning zone (35) is transported by means of the horizontal transport system on one side, touching the transport system, and is thereby post-cleaned on one side in the post-cleaning zone (35). Method according to one of the preceding claims, characterized in that the solar cell precursor (60) is treated on its side facing away from the transport system. Method according to one of the preceding claims, characterized in that step b) comprises a doctor blade coating, slot die deposition and / or spray coating and / or droplet coating. Method according to one of the preceding claims, characterized in that the horizontal transport system has a plurality of transport rollers (40), wherein the transport rollers (40) rotate in a direction of rotation, so that a solar cell precursor (60) resting on them is transported in a transport direction (T) through the preconditioning zone, the coating zone (33) and optionally the annealing zone (34) and optionallythe post-cleaning zone (35) is transported. Method according to one of the preceding claims, characterized in that the solar cell precursor (60) comprises a lower sub-cell (2) of the solar cell to be produced as a tandem solar cell, on which a recombination layer (17) is arranged, which is preconditioned in step a) and coated in step b), wherein the lower sub-cell (2) preferably comprises a silicon-based absorber (22) and / or the recombination layer (17) is preferably formed as a TCO layer, preferably an ITO layer. Method according to one of the preceding claims, characterized in that it is carried out in a system which is designed such that the transport system transports the solar cell precursor (60) through the system during the complete execution of the method.

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