TW202349735A - A solar cell comprising a plurality of porous layers and charge conducting medium penetrating the porous layers - Google Patents

Abstract

The present invention relates to a solar cell (1a) comprising a stack of porous layers, a support substrate (2) for supporting the stack, and a charge conducting medium (7) penetrating through the porous layers. The stack comprises a porous light-absorbing layer (3), a porous first conductive layer (4) including conductive material for extracting photo-generated electrons from the light-absorbing layer, a porous counter electrode (6) including conductive material, and a separating layer (5) made of porous electrically insulating material and arranged between the conductive layer (4) and the counter electrode (6), and where the conductive layer (4) is arranged closer to the light-absorbing layer (3) than the counter electrode (6). The support substrate (2) is porous, and the charge conducting medium (7) is penetrating through the support substrate (2).

Description

Solar cell including a plurality of porous layers and a charge conducting medium penetrating the porous layers

The present invention relates to a solar cell for converting light energy into electrical energy, which includes a plurality of porous layers and a charge conduction medium penetrating the porous layers.

Solar cells containing multiple porous layers for converting light into electrical energy are well known in the art.

It is known that a dye-sensitized solar cell (DSSC) including a porous light-absorbing layer, a porous conductive layer and a porous isolation layer is manufactured using methods such as screen printing, inkjet printing or slot coating. The method has high potential for industrial-scale manufacturing.

Industrial-scale manufacturing of dye-sensitized solar cells involves large-area processing of thin layers of solar cell modules. These components undergo various process steps during manufacturing, such as printing, heat treatment, vacuum treatment, and chemical treatment. This means that in order to handle the processing of solar cells, the architecture of the solar cells is important in order to be able to mechanically handle the components and perform various processes without damaging the underlying components. The architecture of the solar cell is also important to the overall performance of the solar cell.

A known procedure for manufacturing dye-sensitized solar cells is through a roll-to-roll process. In EnergyTrend 20180614 "Keys to Flexible Solar cell's Mass Production: Cell Encapsulation and Durability", researchers describe production by a reel-to-reel manufacturing process. Flexible DSSCs can be commercialized due to the efficiency of the production method.

In roll-to-roll processes, solar cells include a physical substrate, such as a flexible conductive foil, which can be placed on a conveyor belt and serve as a mechanically stable substrate for positioning other components of the solar cell. US8658455 describes a roll-to-roll process with a flexible substrate with a _TiO2 layer formed on it and a _TiO2 layer sintered, provided with dye and loaded with electrolyte, after which a second flexible substrate is added on top for sealing the package Clip-on DSSC. It is also said that the sealing step involved in the reel-to-reel process increases the risk of liquid electrolyte leakage or evaporation.

Flexible conductive foils are known as titanium, stainless steel, or other metal foils or coated foils of conductive polymers or films such as conductive glass.

One problem with reel-to-reel manufacturing of dye-sensitized solar cells involves the fact that some of the processes, such as heat treatment or vacuum processing, must be performed as the conveyor belt rolls through an oven or chemical treatment chamber. These processes require space and time.

Another way of making dye-sensitized solar cells is described in EP2834823B1, which shows a monolithic dye-sensitized solar cell in which all layers of the module are porous. A porous insulating substrate made of woven and non-woven fiberglass serves as a support structure during fabrication, and a porous conductive metal layer is printed onto both sides of the porous insulating substrate. A layer of _TiO2 is printed on one side of the porous conductive layer, and on the other side, the porous conductive layer is provided with a catalyst. The _TiO2 layer is immersed in dye, and electrolyte is added when the cell is cut into suitable pieces for lamination of protective foils. During process steps involving heat treatment, vacuum treatment or various chemical treatments, the workpieces in operation are completely porous and several workpieces can be pinned on top of each other without impeding the escape of, for example, released gases. The porous insulating substrate used as a support substrate during fabrication will serve as the insulating layer between the working and counter electrodes in the final solar cell. The thickness of the porous insulating substrate will therefore be a compromise between making the insulating layer thin enough to reduce resistive losses in the solar cell and making the porous substrate thick enough to achieve sufficient mechanical properties to serve as a support structure. During manufacturing, the support structure must be rotated in order to print on both sides of the support.

EP1708301 discloses a dye-sensitized solar cell having a structure including a stack of porous layers arranged on top of each other, an electrolyte integrally positioned in the pores of the porous layers, and a structure for supporting the stack of porous layers. Support structure made of ceramic, metal, resin or glass.

Another problem with dye-sensitized solar cells involves evaporation or depletion of the electrolytic solution or possible electrolytic leakage, especially during long-term use of the solar cell.

The object of the present invention is to at least partially overcome the above problems and provide an improved solar cell.

This object is achieved by a solar cell as defined in claim 1 of the patent application.

A solar cell includes a stack of porous layers arranged on top of each other, a charge conducting medium penetrating the porous layers, and a support substrate for supporting the porous layers. The plurality of porous layers include: a light absorption layer; a first conductive layer including a conductive material for extracting photogenerated electrons from the light absorption layer; a counter electrode including a conductive material; and a separation layer made of porous electrically insulating material and is disposed between the first conductive layer and the opposite electrode. The stack of porous layers is disposed on top of a support substrate that is porous and with the charge conducting medium penetrating the porous support substrate.

The stack of porous layers is an active layer, which means that it participates in generating electricity. It is necessary that the charge-conducting medium can penetrate the stack of active porous layers to enable charge transfer between the light-absorbing layer and the counter electrode. The support substrate is not an active layer in the solar cell, that is, it does not participate in power generation. The main function of the support substrate is to act as a support for the stack of active layers.

The supporting substrate is porous, and the charge conductive medium penetrates the pores of the substrate and the pores of the porous layer of the solar cell. Due to the porosity of the support substrate, the pores of the support substrate act as reservoirs for the charge-conducting medium. Therefore, the total volume of the charge-conducting medium in the solar cell increases. Therefore, if the charge-conducting medium in a solar cell is reduced due to leakage or evaporation, the time before the total content of charge-conducting medium in the solar cell reaches a minimum level and the solar cell stops operating is extended. The thicker the substrate and the higher the porosity, the larger the reservoir for the charge-conducting medium. Since the supporting substrate does not participate in power generation, the thickness of the supporting substrate is not important and does not affect power generation.

Another advantage of porous substrates is that uniform filling of the charge-conducting medium in the solar cell is easier to achieve during fabrication of the solar cell. This is a problem when making thin and wide solar cells. For example, the area of the solar cell may be 1 m ² and the thickness of the solar cell may be 0.2 mm. The charge-conducting medium must penetrate into the porous layer of the larger solar cell, and preferably, all pores in the porous layer of the solar cell are filled with the charge-conducting medium. Due to the porous substrate in the bottom of the solar cell, the charge conducting medium can be introduced from the bottom side of the solar cell and fill most of the pores in the porous layer in the stack with the charge conducting medium by capillary forces.

Another advantage of the porous substrate is that there is no need for vacuum filling of the cell with a conductive medium, as in the prior art. Vacuum filling is time-consuming and requires additional equipment.

Another advantage of the porous substrate is that the porous substrate retains the conductive medium through capillary force and thereby prevents the conductive medium from escaping. Therefore, in the event of solar cell damage, the conductive medium will be retained in the porous substrate and will not escape.

Another advantage of having the porous layer stacked on a porous support substrate rather than a physical support substrate as in the prior art is that it facilitates the fabrication of large-sized solar cells, since it allows the use of Gases are emitted by the substrate during air sintering, where the combustion gases must be removed at a later stage when the layer containing titanium dioxide _TiO2 is air-sintered, and the combustion gases from organic matter must be removed by combustion. Therefore, the production of solar cells is accelerated.

The solar cell is preferably a single cell. A characteristic feature of monolithic solar cells is that all porous layers are deposited directly or indirectly on the same supporting substrate.

By having a porous support substrate at the bottom of the porous active layer, the fabrication of monolithic solar cell structures can benefit from an advantageous process of stapling the workpieces during the fabrication process. Another advantage is that the support substrate on which the active layer is formed at and above the base of the active layer eliminates the need to rotate the workpiece during operations during the manufacturing process.

Another advantage of the present invention is that the separation layer made of porous electrically insulating material is not defined by the supporting substrate. The porous separation layer between the porous conductive layers can be formed by a cost-effective printing process and made of a variety of materials. The thickness of the separation layer can be designed to optimize the efficiency of the solar cell.

According to one aspect, a solar cell includes an encapsulation body encapsulating a porous layer, a support substrate, and a conductive medium, and the porous layer is disposed on one side of the support substrate, and an opposite side of the support substrate faces the encapsulation body.

Each of the porous layer and the support substrate has pores. The charge conductive medium penetrates the porous layer and the pores of the supporting substrate. The charge conductive medium is integrally positioned in the pores of the porous layer and the pores of the supporting substrate.

According to one aspect, the average size of the pores of the plurality of porous layers is smaller than the average size of the pores of the supporting substrate, so that the capillary force in the pores of the porous layer is stronger than the capillary force in the supporting substrate. Due to the fact that the pore size in the porous layer on top of the support substrate is smaller than the pore size in the support substrate, the capillary force of the porous layer will better pump the charge conducting medium upward, where the capillary force is greater than the capillary force in the support substrate Strong. This action is similar to capillary pump action. This means that in the event of leakage of the charge conducting medium in the upper active layer, the charge conducting medium will be better pumped upward from the reservoir to the active layer, and the support substrate will act as a reservoir supplying the charge conducting medium to the active layer. collector.

The size of the pores in the substrate and the porous layer can be measured, for example, using a scanning electron microscope (SEM).

According to one aspect, at least 80% of the pores in the support substrate are larger than 3 µm, and at least 80% of the pores in the porous layer are smaller than 3 µm. Preferably, at least 90% of the pores in the support substrate are larger than 3 μm, and at least 90% of the pores in the porous layer are smaller than 3 μm. Preferably, at least 80% of the pores in the support substrate are between 3 µm and 10 µm, and most preferably, at least 90% of the pores in the support substrate are between 3 µm and 10 µm . Thus, the pores in the porous layer are typically in the sub-meter range, that is, less than 3 µm, and the pores in the support substrate are typically in the micron range, that is, between 3 µm and 10 µm. The difference in pore size between the support substrate and the porous layer causes the capillary forces in the porous layer to be stronger than those in the support substrate, and therefore, if the amount of charge-conducting medium in the active layer of the solar cell is reduced, the charge-conducting medium Will be pumped upward to the active layer.

According to one aspect, the thickness of the support substrate is at least 20 µm, preferably at least 30 µm, and most preferably at least 50 µm. The thicker the substrate, the larger the reservoir of charge-conducting medium.

According to one aspect, the thickness of the support substrate is between 20 µm and 200 µm.

According to one aspect, the porosity of the support substrate is at least 50%, and preferably at least 70%, and most preferably at least 80%. The higher the porosity, the larger the reservoir for the charge-conducting medium.

According to one aspect, the porosity of the support substrate is between 50% and 90%, and preferably between 70% and 90%.

According to one aspect, the support substrate includes woven and/or non-woven microfibers. Microfibers are fibers with a diameter less than 10 µm and greater than 1 nm.

According to one aspect, the support substrate includes inorganic fibers.

According to one aspect, the support substrate includes at least one of the following: glass fiber, ceramic fiber, and carbon fiber.

According to one aspect, the diameter of the microfibers is between 0.2 µm and 10 µm, preferably between 0.2 µm and 5 µm, more preferably between 0.2 µm and 3 µm, and most preferably Between 0.2 µm and 1 µm.

According to one aspect, the support substrate includes a layer of woven microfibers. The woven microfibers are flexible, and therefore, the solar cells become flexible.

According to one aspect, the support substrate includes a non-woven microfiber layer disposed on the woven microfiber layer. The woven microfibers and non-woven microfibers are flexible, and therefore, the solar cell becomes flexible. Non-woven microfibers act as spring pads that effectively absorb and suppress incoming mechanical energy, and also distribute incoming mechanical energy over a larger area, thereby reducing local effects. The advantage of stacking a porous layer on a substrate including a woven microfiber layer and a non-woven microfiber layer is that the supporting substrate becomes shock-absorbing and, therefore, when the solar cell is subjected to conditions such as mechanical bending or twisting or stretching or impact hammers , has strong mechanical stability. This is an advantage when solar cells are integrated into consumer products such as headsets, remote controls, and cellular phones.

According to one aspect, the nonwoven microfiber layer is disposed closer to the counter electrode than the woven microfiber layer. Preferably, the non-woven microfiber layer is continuously arranged to the opposite electrode.

According to another aspect, the woven microfiber layer is configured to be closer to the counter electrode than the non-woven microfiber layer. Preferably, the braided microfiber layer is continuously disposed to the opposite electrode.

According to one aspect, the woven microfiber layer includes yarns, wherein holes are formed between the yarns, and at least a portion of the non-woven microfibers are accumulated in the holes between the yarns.

According to one aspect, the thickness of the separation layer is between 3 µm and 50 µm, and preferably between 4 µm and 20 µm. It is desirable to make the separation layer as thin as possible to reduce resistive losses in the solar cell and thus improve the efficiency of the solar cell. However, if the separation layer becomes too thin, there is a risk of short circuit between the conductive layer and the counter electrode.

According to one aspect, the separation layer includes porous electrically insulating material. Preferably, the electrically insulating material is made of electrically insulating particles. This separation layer can be made by applying several layers of insulating particles on top of each other to obtain the desired thickness of the separation layer. Therefore, it is possible to control the thickness of the separation layer and optionally select the thickness of the separation layer.

According to one aspect, these electrically insulating particles are composed of insulating material.

According to one aspect, the electrically insulating particles comprise a core of semiconducting material and an outer layer of electrically insulating material covering the core.

According to one aspect, the insulating material of the outer layer of the insulating particles includes one or more materials in the group consisting of: aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), silicon oxide (SiO ₂ ) and aluminosilicates. Aluminosilicates are, for example, Al ₂ SiO ₅ .

According to one aspect, the insulating material of the outer layer of the insulating particles is one or more materials in the group consisting of: aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), silicon oxide (SiO ₂ ) and aluminosilicates. Aluminosilicates are, for example, Al ₂ SiO ₅ .

According to one aspect, the semiconducting material in the core of the insulating particles includes titanium dioxide (TiO ₂ ).

According to one aspect, the semiconducting material in the core of the insulating particles is titanium dioxide (TiO ₂ ).

According to one aspect, the electrically insulating material of the insulating particles includes one or more materials in the group consisting of: aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), silicon oxide (SiO) ₂ ) and aluminum silicate. Aluminosilicates are, for example, Al ₂ SiO ₅ . According to another aspect, the insulating material may be glass.

According to one aspect, the electrically insulating material of the insulating particles is one or more materials in the group consisting of: aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), silicon oxide (SiO ₂ ) and aluminum silicate. Aluminosilicates are, for example, Al ₂ SiO ₅ . According to another aspect, the insulating material may be glass.

According to one aspect, the charge conducting medium is a liquid electrolyte.

Certain conductive media, such as copper complex electrolytes and cobalt complex electrolytes, can have extremely low conductivities, resulting in significant resistive losses. Low conductivity results from the fact that the electrolyte has large ions with low diffusivity. When a liquid electrolyte transports charges, the charges move with Brownian motion, that is, they move randomly due to collisions with fast-moving atoms or molecules in the liquid. Copper and cobalt have relatively large ions, which move slowly and therefore have low electrical conductivity. The efficiency of using such electrolytes is greatly improved by having a short distance between the counter electrode and the light absorbing layer. The invention makes it possible to select the thickness of the separation layer and therefore the appropriate distance between the counter electrode and the light absorbing layer depending on the electrolyte.

According to one aspect, the conductive medium includes a copper complex. The advantage of using copper complexes for charge transport is that the conductive medium will be non-toxic. The use of copper as a conductive medium has been demonstrated to produce extremely high resulting photovoltages. The solar cell according to the invention allows the use of copper complexes due to the fact that the distance between the counter electrode and the light absorbing layer can be made short.

According to another aspect, the charge conduction medium includes iodide ions (I ^- ) and triiodide ions (I ₃ ^- ).

Another object of the invention is to provide a method for producing solar cells. This method contains: -Provide porous support substrate, - depositing a porous counter electrode on a porous support substrate, - depositing a porous separation layer on the counter electrode, - depositing a porous conductive layer on the separation layer, - depositing a porous light-absorbing layer on the conductive layer, -Introduce the charge conductive medium into the stack and the supporting substrate until the charge conductive medium penetrates the supporting substrate and the stack, -Sealed solar cells.

According to one aspect, depositing a porous counter electrode includes depositing a porous second conductive layer and a porous catalytic layer on top of the second conductive layer.

According to one aspect, the charge-conducting medium is introduced on the side of the support substrate facing away from the stack, so that the support substrate and the stack are impregnated with the charge-conducting medium.

The deposition of the porous counter electrode, the porous separation layer, the porous first conductive layer and the porous light absorbing layer is performed, for example, by spraying or printing techniques such as inkjet printing or screen printing.

Aspects of the invention will be described more fully hereinafter with reference to the accompanying drawings. However, solar cell devices may be implemented in many different forms and should not be construed as limited to those set forth herein. The same numbering in the drawings always refers to the same element.

Figure 1 shows a cross-section through an example of a solar cell la according to the invention. Solar cell la comprises a support substrate 2 and a stack 12 of porous layers 3 - 6 arranged on top of the support substrate 2 . The stack 12 of porous layers includes: a light-absorbing layer 3, which acts as a working electrode; an electrically conductive layer 4, made of a porous conductive material, which acts as a current collector; a separation layer 5, which contains a porous electrically insulating material; and a counter electrode 6, which contains porous conductive materials. The counter electrode 6 is formed on one side of the porous substrate 2 . In this example, the counter electrode is a porous conductive layer. The separation layer 5 is arranged between the counter electrode 6 and the conductive layer 4 . The separation layer 5 is used to physically and electrically separate the conductive layer 4 and the opposite electrode 6 to avoid direct electronic short circuit therebetween. In this example, the separation layer 5 is formed on the counter electrode 6 , and the conductive layer 4 is formed on the separation layer 5 . Light absorbing layer 3 is arranged on top of conductive layer 4 . The first conductive layer 4 includes a conductive material for extracting photogenerated electrons from the light absorbing layer 3 . The light absorbing layer 3 can be produced in different ways. For example, the light absorbing layer may comprise dye molecules, or clusters of dyes, adsorbed on the surface of semiconducting particles, or grains made of semiconducting material, such as silicon.

Porous layers 3-6 are active layers, which means they participate in power generation. The supporting substrate 2 is not an active layer in the solar cell, that is, it does not participate in power generation. The support substrate 2 supports the stack 12 of porous layers 3-6. Furthermore, the support substrate 2 allows the counter electrode 6 to be printed thereon during the manufacture of the solar cell. The porous layer 3 - 6 is arranged on one side of the support substrate 2 .

Each of the porous layers formed on the supporting substrate has a large number of pores. The solar cell further comprises a charge conducting medium 7 which penetrates the pores of the porous layers 3 - 6 to enable the transfer of charges between the light absorbing layer 3 and the counter electrode 6 . The support substrate 2 is also porous and includes pores. The charge conductive medium 7 penetrates the pores of the supporting substrate 2 and the pores of the porous layers 3-6 of the solar cell. Due to the porosity of the support substrate 2, the pores of the support substrate act as reservoirs for the charge conducting medium

In one aspect, the average size of the pores in the porous layers 3 - 6 in the stack 12 is less than the average size of the pores in the support substrate 2 such that the capillary forces in the pores in the porous layers 3 - 6 are smaller than the capillary forces in the support substrate 2 Strong. The difference in pore size between the support substrate 2 and the porous layers 3-6 causes the capillary force in the porous layer to be stronger than the capillary force in the support substrate 2, and therefore, if the amount of charge conduction medium in the active layer of the solar cell is reduced , then the charge conducting medium 7 will be pumped upward to the active layer 3-6.

Preferably, at least 80% of the pores in the supporting substrate 2 are larger than 3 μm, and at least 80% of the pores in the porous layer are smaller than 3 μm. More preferably, at least 90% of the pores in the support substrate 2 are larger than 3 μm, and at least 90% of the pores in the porous layers 3-6 are smaller than 3 μm. For example, at least 80% of the pores in the support substrate 2 are between 3 µm and 10 µm.

The thicker the support substrate 2, the larger the reservoir of charge conductive medium in the solar cell. Typically, the thickness of the support substrate 2 is between 20 µm and 200 µm. Preferably, the thickness of the supporting substrate is at least 30 µm.

The greater the porosity in the support substrate, the greater the reservoir of charge conducting medium 7. Preferably, the support substrate has a porosity of at least 50%, and most preferably at least 70%. If the support substrate is porous, the mechanical strength of the substrate will be too low. Preferably, the porosity of the supporting substrate is between 50% and 90%.

The solar cell further includes an encapsulation body 10 encapsulating the porous layers 3 - 6 , the support substrate 2 and the conductive medium 7 . The stack 12 of porous layers is arranged on one side of the support substrate 2 with the opposite side of the support substrate facing the encapsulation body 10 .

Stack 12 of porous layers may include other porous layers disposed between porous layers 3-6. For example, there may be a porous catalytic layer arranged between the support substrate 2 and the counter electrode 6 or between the counter electrode 6 and the separation layer 5, as shown in Figure 1b. Furthermore, there may be a porous reflective layer arranged between the conductive layer 4 and the light absorbing layer 3 . The same conditions mentioned above regarding pore size apply to all layers in the stack 12 of porous layers, regardless of the number of layers.

Figure 2 shows a cross-section through another example of a solar cell 1b according to the invention. Solar cell 1 b includes a support substrate 2 and a stack 12 of porous layers 3 - 6 arranged on top of the support substrate 2 . The difference between solar cell 1b and solar cell 1a is that the opposite electrode 6 of solar cell 1b includes a second porous conductive layer 6a and a porous catalytic layer 6b formed on the top of the porous conductive layer 6a.

In this example, the support substrate 2 includes a woven microfiber layer 2a and a non-woven microfiber layer 2b disposed on the woven microfiber layer 2a. The counter electrode 6 is placed on the nonwoven microfiber layer 2b. In this example, the porous conductive layer 6a of the counter electrode 6 is formed on the nonwoven microfiber layer 2b. Alternatively, the catalytic layer 6b is disposed on the non-woven microfiber layer 2b. The woven microfiber layer 2a includes yarns with holes formed between the yarns, and at least a portion of the non-woven microfibers are accumulated in the holes between the yarns. Preferably, the diameter of the microfibers in the non-woven microfiber layer 6b is between 0.2 µm and 5 µm to obtain pores with a size greater than 1 µm. EP2834824B1 discloses a method for manufacturing a substrate 2 containing woven and non-woven microfibers.

The solar cells 1a and 1b are of the single type. This means that all porous layers are deposited directly or indirectly on the same support substrate 2 . The solar cells 1a and 1b may be, for example, dye-sensitized solar cells (DSC).

Figure 3 shows an SEM image of a cross-section through an example of one embodiment of the present invention showing that the support substrate 2 includes a woven microfiber layer 2a on top of a non-woven microfiber layer 2b. A second porous conductive layer 6a is arranged on the support substrate 2, followed by a catalytic layer 6b, and on top of this catalytic layer a separation layer 5. A first conductive layer 4 is disposed on top of the separation layer 5, and on the first conductive layer is a light absorbing layer 3.

Figure 4 shows an SEM image of a cross-section through another example of one embodiment of the invention showing that the support substrate 2 includes a non-woven microfiber layer 2b on top of a woven microfiber layer 2a. A second porous conductive layer 6a is arranged on the support substrate 2, followed by a catalytic layer 6b, and on top of this catalytic layer a separation layer 5. A first conductive layer 4 is disposed on top of the separation layer 5, and on the first conductive layer is a light absorbing layer 3.

Preferably, the pore size of the light absorbing layer 3 is equal to or smaller than the pore size of the first conductive layer 4, the pore size of the first conductive layer 4 is equal to or smaller than the pore size of the separation layer 5, and the pore size of the separation layer 5 is equal to or It is smaller than the pore size of the layer of the counter electrode 6, 6a, 6b. The pore sizes of the counter electrodes 6, 6a, 6b are preferably smaller than the pore sizes of the supporting substrates 2, 2a, 2b.

In one embodiment of the invention, the size of the pores in the stack 12 of porous layers decreases from the counter electrode 6 to the light absorbing layer 3 . For example, the pore size of the light absorbing layer 3 is smaller than the pore size of the first conductive layer 4, the pore size of the first conductive layer 4 is smaller than the pore size of the separation layer 5, and the pore size of the separation layer 5 is smaller than the counter electrodes 6, 6a. ,6b pore size. The pore sizes of the counter electrodes 6, 6a, and 6b are smaller than the pore sizes of the supporting substrates 2, 2a, and 2b. This embodiment will enhance the difference in capillary forces in the porous layer compared to the capillary forces in the support substrate 2.

The light absorbing layer 3 faces the incident light. The light-absorbing layer 3 can be produced in different ways. For example, the light absorbing layer 3 may comprise a porous TiO ₂ layer deposited onto the first conductive layer 4 . The _TiO2 layer may contain _TiO2 particles, which allow dye molecules to adsorb on its surface. In another example, light absorbing layer 3 includes a plurality of grains of doped semiconductive material, such as silicon, which are deposited on conductive layer 4 . The charge-conducting medium is integrally located in the pores formed between the grains. The thickness of the light absorbing layer 3 can vary and depends on the type of light absorbing layer 3 .

The top sides of the solar cells 1a, 1b should face the light to allow the light to hit the light absorbing layer 3. According to some aspects, the light-absorbing layer is a porous _TiO2 nanoparticle layer having adsorbed organic dye or organometallic dye molecules or natural dye molecules. However, the light absorbing layer 3 may also include crystal grains of doped semiconducting material, such as Si, CdTe, CIGS, CIS, GaAs or perovskite.

Conductive layer 4 acts as a back contact, which photogenerates charges from the light absorbing layer 3 extract. The porosity of the conductive layer 4 may preferably be between 30% and 85%. Depending on the material used for the conductive layer 4 and the manufacturing method used, the thickness of the conductive layer 4 can vary between 1 µm and 50 µm. For example, the conductive layer 4 is made of a material selected from the group consisting of titanium, titanium alloys, nickel alloys, graphite, and amorphous carbon, or mixtures thereof. Optimally, the conductive layer is made of titanium or titanium alloys or mixtures thereof. In this case, the thickness of the conductive layer 4 is preferably between 4 µm and 30 µm.

The separation layer 5 acts as an electrical separation between the conductive layer 4 and the counter electrode 6 to avoid short circuits therebetween. The distance between the counter electrode 2 and the light absorbing layer 3 depends on the thickness of the separation layer 5 and should be as small as possible, so that the charge transfer between the counter electrode 2 and the light absorbing layer 3 becomes as fast as possible and therefore reduces the cost of the solar cell. The resistance loss. The thickness of the separation layer is, for example, between 3 µm and 50 µm, and preferably between 4 µm and 20 µm. The separation layer contains porous electrically insulating material. For example, the separation layer includes a porous layer of electrically insulating particles. For example, an insulating particle has a core of semiconducting material and an outer layer of electrically insulating material. For example, an insulating oxide layer is formed on the surface of a semiconductive material. Suitably, the semiconducting material is titanium dioxide ( _TiO2 ). The insulating material is, for example, aluminum oxide or silicon oxide. Alternatively, all particles may be of insulating material, such as aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ) or zirconium oxide (ZrO ₂ ).

The counter electrode 6 includes a porous conductive layer 6a. The counter electrode usually also includes a catalytic layer 6b. The counter electrode 6 may have a separate porous catalytic layer 6b or have catalytic particles integrated in the porous conductive layer 6a. The porosity of the counter electrode 6 may preferably be between 30% and 85%. Depending on the material used for the counter electrode 6 and the manufacturing method, the thickness of the counter electrode 6 can vary between 1 µm and 50 µm. For example, the counter electrode 6 is made of a material selected from the group consisting of titanium, titanium alloys, nickel alloys, graphite, and amorphous carbon, or mixtures thereof. Optimally, the counter electrode 6 is made of titanium or titanium alloy or a mixture thereof. In this case, the thickness of the conductive layer 4 is preferably between 10 µm and 30 µm. In order to achieve a catalytic effect, the counter electrode 6 may include platinum-coated particles of conductive metal oxides such as platinum-coated ITO, ATO, PTO and FTO, or particles of platinum-coated carbon black or graphite.

The supporting substrate 2 may be a microfiber-based substrate, such as a glass microfiber substrate or a ceramic microfiber substrate. The support substrate 2 is suitably made of microfibers. Microfibers are fibers with a diameter less than 10 µm and a length greater than 1 nm. Suitably, the support substrate 2 contains woven microfibers. Microfibers can be made from refractory and inert materials such as glass, SiO ₂ , Al ₂ O ₃ and aluminosilicates. Organic microfibers are fibers made of organic materials such as polymers such as polycaprolactone, PET, PEO, etc., or cellulose such as nanocellulose (MFC) or wood pulp. The support substrate 2 may include woven microfibers and non-woven microfibers disposed on the woven microfibers. Suitably, the support substrate 2 contains fiberglass. For example, the porous support substrate can be made from woven fiberglass and non-woven fiberglass. The thickness of the support substrate 2 is suitably between 10 µm and 1 mm. This layer provides the required mechanical strength.

The charge conductive medium 7 is integrally positioned in the pores of the porous layers 3 - 6 and the pores of the supporting substrate 2 , and transfers charges between the counter electrode 6 and the light absorbing layer 3 . The conductive medium 7 may be any suitable conductive medium, such as a liquid, a gel or a solid material, such as a semiconductor. Examples of electrolytes are liquid electrolytes, such as those based on iodide ions (I ⁻ )/triiodide ions (I ₃ ⁻ ) or cobalt complexes, such as redox couples, or gel electrolytes, common polymer electrolytes. Preferably, the conductive medium is a liquid electrolyte, such as an ionic liquid-based electrolyte, a copper complex-based electrolyte, or a cobalt complex-based electrolyte.

Solar cells must be properly sealed to avoid leakage of the charge-conducting medium. For example, the solar cell has an encapsulation body 10 surrounding the solar cell unit. However, the encapsulation must be penetrated in some way to enable the electricity generated by the solar cells to be harvested. Although the penetration is sealed, there is a risk of slow leakage of the charge-conducting medium from the solar cell. Leakage may also occur from the sealing edge of the capsule. The slow leakage of the charge conduction medium will cause the efficiency of the solar cell to slowly decrease. When the amount of charge conduction medium in a solar cell has reached a minimum level, the photoelectric conversion capability of the solar cell will be reduced. This process can take months, or even years, depending on the quality of the encapsulation and seal.

Encapsulation 10 acts as a barrier to protect the solar cell from the surrounding atmosphere and prevent the charge-conducting medium from evaporating or leaking from the interior of the cell. Encapsulation 10 may include an upper sheet covering the top side of the solar cell and a lower sheet covering the bottom side of the solar cell. The upper sheet on the top side of the solar cell covers the light absorbing layer and needs to be transparent to allow light to pass through. The bottom side of the support substrate 2 faces the lower sheet of the encapsulation body 10 . The light absorbing layer 3 faces the upper sheet of the encapsulation body 10 . The upper and lower sheets are made of polymer material, for example. The edges of the upper and lower sheets are sealed.

According to one aspect, the encapsulation body 10 of the solar cells 1a, 1b includes a plurality of penetration openings (not shown in the figure), so that the power generated by the solar cells can be obtained. The penetration opening receives wires for electrical connection to the first conductive layer 4 and the opposite electrode 6 . The penetration opening may be configured to connect to the first conductive layer 4 and the counter electrode 6 . Preferably, the penetration opening is disposed in the side of the encapsulation body disposed below the support substrate 2 .

Figure 5 shows a block diagram of an example of a method of manufacturing a solar cell according to the present invention. The method in Figure 5 includes the following steps: S1: Provide porous support substrate 2, S2: Deposit the porous counter electrode 6 on the porous support substrate 2, S3: Deposit the porous separation layer 5 on the counter electrode 6, S4: Deposit the first porous conductive layer 4 on the separation layer 5, S5: Deposit the porous light absorbing layer 3 on the first conductive layer 4, S6: Introduce the charge conductive medium 7 into the stack 12 and the supporting substrate 2 until the charge conductive medium 7 penetrates the supporting substrate 2 and the stack 12, S7: Sealed solar cell.

According to one aspect, the charge-conducting medium 7 is introduced on the side of the support substrate facing away from the stack 12 , so that the support substrate and the stack are impregnated with the charge-conducting medium.

The deposition in steps S2 to S5 is performed, for example, by spraying or printing techniques such as inkjet printing or screen printing.

An example of how step S3 can be carried out will now be explained in more detail. The separation ink is prepared by mixing a powder of insulating particles with a solvent, a dispersant and a binder. Solvents are, for example, water or organic solvents. The binder is, for example, hydroxypropylcellulose. Dispersants are, for example, Byk 180. The mixture is stirred until the aggregated particles in the powder separate into individual particles and the particles in the ink are well dispersed. The separation ink is deposited on the opposite electrode 6 by spraying or printing technology. The deposition of the separation ink may be repeated two, three or more times until a sufficiently thick layer of insulating particles is deposited on the counter electrode. Preferably, the layer of separation ink is allowed to dry before the lower layer of separation ink is deposited on the previous layer of separation ink. It is advantageous to repeat the deposition of the separation ink two or more times since the underlying layer of ink will repair possible defects in the aforementioned layer of insulating particles. It is important that there are no defects in the separation layer 5 , such as cracks or holes, since this would lead to a short circuit between the counter electrode 6 and the porous first conductive layer 4 .

The solar cell 1a in FIG. 1 is penetrated into the pores of the light absorbing layer 3, the pores of the first conductive layer 4, the pores of the separation layer 5, the counter electrode 6 and the supporting substrate 2. There is a charge conducting medium 7. The charge-conducting medium forms a continuous layer between the conductive layers inside the pores of the conductive layer and inside the pores of the separation layer, thereby enabling charge transfer between the counter electrode 6 and the working electrode, which includes the first conductive layer 4 and light absorbing layer 3. The first porous conductive layer 4 extracts electrons from the light absorbing layer 3 and transmits the electrons to an external circuit connected to the counter electrode 6 (not shown in FIG. 1 ). The counter electrode 6 serves to transfer electrons to the charge conduction medium 7 . The conductive medium 7 transports the electrons back to the light absorbing layer 3, thereby completing the circuit.

Depending on the nature of the charge-conducting medium 7, ions or electrons as well as holes can be transported between the counter electrode and the working electrode.

Electrolytes in dye-sensitized solar cells are generally classified as liquid electrolytes, quasi-solid electrolytes or solid electrolytes. Electrolytes can be in the form of liquids, gels, or solids. There are a large number of electrolytes of any type known in the literature, see for example Chemicals Reviews, January 28, 2015, "Electrolytes in Dye-Sensitized Solar Cells." Electrolytes are expensive components in dye-sensitized solar cells. The counter electrode is usually equipped with a catalytic substance 6b for the purpose of facilitating the transfer of electrons to the electrolyte.

Charge-conducting media exhibit a certain resistance to charge transport. Resistance increases with the distance the charge travels. Therefore, when charges are transferred between the opposite electrode and the light-absorbing layer, there will always be a certain resistive loss in the conductive medium. Resistive losses can be reduced by making the porous substrate thinner. However, as porous substrates become thinner, they also become more mechanically fragile.

The conductive medium is, for example, a conventional I ^- /I ₃ ^-electrolyte or similar electrolyte, or a Cu-/Co-complex electrolyte. Hole conductors based on complexes of solid transition metals or organic polymers are known conductive media.

According to some aspects, the conductive medium includes a copper ion complex. The conductive medium with copper complex as a charge conductor is a non-toxic conductive medium. The use of copper complexes as conductive media has been demonstrated to produce extremely high resulting photovoltages.

The counter electrode 6 can be deposited, for example, on the support substrate 2 by printing using ink containing solid conductive particles. Conductive particles, such as metal hydride particles, can be mixed with liquids to form inks suitable for printing processes. The conductive particles may also be ground or otherwise treated to obtain the appropriate particle size and, therefore, the desired pore size of the porous counter electrode 6 . The solid particles are preferably based on metals and can be pure metals, metal alloys or metal hydrides or metal alloy hydrides or mixtures thereof.

The conductive layer 4 can be deposited on the separation layer 5 in the same manner as the counter electrode 6 is deposited on the support substrate 2 . The deposits can be treated by heat treatment steps. During the heat treatment, the particles should also be sintered to increase the conductivity and mechanical stability of the conductive layer. Metal hydrides will transform into metals during heat treatment. By heating in a vacuum or an inert gas, contamination of particles is prevented and electrical contact between particles is improved.

The terminology used herein is for the purpose of describing particular aspects of the invention only and is not intended to be limiting of the invention. As used herein, the singular forms "a/an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The terms "photovoltaic cell" and "solar cell" are synonymous.

Unless otherwise defined, all terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs.

The invention is not limited to the specific examples disclosed, but may be varied and modified within the scope of the following claims. For example, a stack of porous layers may contain other porous layers, and the order of the porous layers in the stack may vary.

1a: Solar cell 1b: Solar cell 2: Support base plate 2a: Braided microfiber layer 2b: Non-woven microfiber layer 3:Light absorbing layer 4: Conductive layer 5:Separation layer 6: Counter electrode 6a: Second porous conductive layer 6b: Porous catalytic layer 7:Conduction medium 10: Encapsulated body 12:Stacking S1: Steps S2: Step S3: Steps S4: Steps S5: Steps S6: Steps S7: Steps

The present invention will now be explained in more detail by describing different specific examples of the invention and with reference to the accompanying drawings. [Fig. 1] shows a cross section through an example of a solar cell according to the present invention. [Fig. 2] shows a cross section through another example of a solar cell according to the present invention. [Fig. 3] A SEM image showing a cross-section through an example of one embodiment of the present invention. [Fig. 4] A SEM image showing a cross-section through another example of one embodiment of the present invention. [Fig. 5] A block diagram showing an example of a method of manufacturing a solar cell according to the present invention.

1a: Solar cell

2: Support base plate

3:Light absorbing layer

4: Conductive layer

5:Separation layer

6: Counter electrode

7:Conduction medium

10: Encapsulated body

12:Stacking

Claims (15)

A solar cell (1a; 1b) comprising a stack (12) of porous layers (3-6), a support substrate (2) for supporting the stack, and a charge conductive medium (7) penetrating the stack, wherein the Stack(12) contains: Porous light absorbing layer (3), A porous first conductive layer (4) comprising a conductive material for extracting photogenerated electrons from the light absorbing layer, a porous counter electrode (6) comprising an electrically conductive material, and A separation layer (5) made of porous electrically insulating material and disposed between the first conductive layer (4) and the counter electrode (6), and wherein the first conductive layer (4) is disposed in a ratio of The opposite electrode (6) is closer to the light absorption layer (3), Wherein the stack of porous layers (3-6) is arranged on top of the support substrate (2) which is porous and the charge conducting medium (7) penetrates the support substrate (2). The solar cell of claim 1, wherein the charge conductive medium (7) is integrally positioned in the pores of the porous layers (3-6) and the pores of the supporting substrate (2), and the porous layers (3-6) The average size of the pores is smaller than the average size of the pores of the supporting substrate (2), so that the capillary force in the pores of the porous layers is stronger than the capillary force in the pores of the supporting substrate. The solar cell of any one of claims 1 to 2, wherein at least 80% of the pores in the porous layers (3-6) have a size less than 3 µm. The solar cell of any one of claims 1 to 2, wherein at least 80% of the pores in the support substrate (2) have a size greater than 3 μm. The solar cell of any one of claims 1 to 2, wherein the porosity of the supporting substrate (2) is at least 50%, and preferably at least 70%, and most preferably at least 80%. The solar cell of any one of claims 1 to 2, wherein the thickness of the support substrate (2) is at least 20 µm, preferably at least 30 µm, and most preferably at least 50 µm. The solar cell of claim 1, wherein the support substrate (2) contains microfibers. The solar cell of claim 7, wherein the support substrate (2) includes a thickness between 0.2 µm and 10 µm, preferably between 0.2 µm and 5 µm, and most preferably between 0.2 µm and 1 µm. diameter of microfibers. The solar cell of claim 1, wherein the support substrate (2) includes woven microfibers and non-woven microfibers. The solar cell of claim 9, wherein the support substrate (2) includes a woven microfiber layer (2a) and a non-woven microfiber layer (2b) arranged on the woven microfiber layer (2a). The solar cell according to any one of claims 1 to 2, wherein the support substrate (2) is flexible. The solar cell of any one of claims 1 to 2, wherein the thickness of the separation layer (5) is between 3 µm and 50 µm, and preferably between 15 µm and 35 µm, and most preferably The ideal range is between 4 µm and 20 µm. The solar cell according to any one of claims 1 to 2, wherein the charge conductive medium (7) is a liquid electrolyte. A method for manufacturing a solar cell as claimed in claim 1, wherein the method includes: Provide porous support substrate (2) (S1), Deposit the porous counter electrode (6) on the porous support substrate (2) (S2), Deposit the porous separation layer (5) on the counter electrode (6) (S3), Deposit the porous first conductive layer (4) on the separation layer (5) (S4), Deposit the porous light-absorbing layer (3) on the conductive layer (4) (S5), Introduce the charge conductive medium (7) into the stack (12) and the support substrate (2) until the charge conductive medium (7) penetrates the support substrate (2) and the stack (12) (S6), The solar cell is sealed (S7). The method of claim 14, wherein depositing the porous counter electrode (6) (S2) includes depositing a porous second conductive layer (6a) and a porous catalytic layer (6b) on top of the second conductive layer (6a).