WO2024198647A1 - Silane coupling agent, linking method therefor, and solar cell - Google Patents

Abstract

Provided in the present application are a silane coupling agent, a linking method therefor, and a solar cell. The silane coupling agent is used for linking inorganic silicon and a polymer and is represented by Y-R-SiX₃, where Y represents a monomer that forms the polymer, R is an alkylene group, and SiX₃ can be hydrolyzed and linked to the surface of the inorganic silicon. According to the silane coupling agent provided by the present application, an inorganic silicon and a polymer formed by polymerization can each be linked by covalent bonds, so that compared with relying on a hydrogen bond linking approach in the existing technology, the bonding strength can be significantly increased.

Description

Silane coupling agent, connection method thereof and solar cell

This application claims the priority of the Chinese patent application filed with the Chinese Patent Office on March 28, 2023, with application number 202310320147.8 and titled “A silane coupling agent, a connection method thereof and a solar cell”, and the priority of the Chinese patent application filed with the Chinese Patent Office on March 28, 2023, with application number 202310317880.4 and titled “An organic-crystalline silicon heterojunction cell and a method for forming a hole transport layer on a silicon substrate”, the entire contents of which are incorporated by reference into this application.

Technical Field

The present application relates to the technical field of organic silicon compounds, and in particular to a silane coupling agent and a connection method thereof, and a solar cell.

Background Art

In photovoltaic cells, silane coupling agents, as an inorganic and organic interface adhesive, are gradually being used in the interface connection of photovoltaic cells, for example: the connection between crystalline silicon and the hole transport layer in crystalline silicon cells, mainly to meet the surface passivation of crystalline silicon cells.

Silane coupling agent is a chemical agent developed by Union Carbide Corporation, mainly used for glass fiber reinforced plastics. The molecular structure of silane coupling agent is generally YR-SiX ₃ , where the hydrolyzed groups of SiX ₃ can passivate and connect the crystalline silicon surface, R is an alkyl group, and Y is an organic group that usually undergoes organic reactions. Therefore, when the silane coupling agent is between the interface of inorganic (such as crystalline silicon) and organic (such as hole transport layer), a bonding layer of organic matrix-silane coupling agent-inorganic matrix can be formed.

At present, the silane coupling agent connection method proposed in patent CN105742506B and the paper "Nanostructured Si/Organic Heterojunction Solar Cells with High Open-Circuit Voltage via Improving Junction Quality" (Adv.Funct.Mater.2016,26,5035-5041) (hereinafter referred to as "existing literature") (see Figure 6) can effectively passivate and connect the crystalline silicon surface, and can rely on hydrogen bonds to connect with the hole transport layer. However, due to the insulation of the silane coupling agent itself, the photogenerated carriers in the crystalline silicon cannot be fully diffused to the hole transport layer, resulting in a loss of conversion efficiency of the photovoltaic cell; in addition, the weak bond energy of the hydrogen bond also reduces the stability of the interface connection.

Summary of the invention

In order to solve the problems in the prior art, a silane coupling agent and a connection method thereof and a solar cell are provided. The technical solution of this application is as follows:

1. A silane coupling agent used to connect inorganic silicon and polymers.

The silane coupling agent is YR-SiX ₃ , wherein:

Y represents a monomer forming the polymer,

R is an alkylene group,

SiX ₃ can hydrolyze and connect to the surface of the inorganic silicon.

2. The silane coupling agent as described in item 1, wherein the polymer is a polymer that can serve as a hole transport layer; preferably, the polymer is a thiophene polymer.

3. In the silane coupling agent as described in item 2, Y is selected from one of EDOT, 3HT, 3OHT, 3ODDT and thiophene in thiophene compounds.

4. The silane coupling agent as described in item 2, wherein R is a methylene group or an ethylene group.

5. A method for connecting inorganic silicon and a polymer, comprising:

A pretreatment step, pretreatment to make the surface of the inorganic silicon have hydroxyl groups;

an alkylation reaction step, wherein the silane coupling agent described in any one of items 1 to 4 is used to undergo a substitution reaction with the pretreated inorganic silicon to obtain a silicon interface modified by the silane coupling agent;

The polymerization step is to carry out a polymerization reaction on the surface of the inorganic silicon after the alkylation reaction to form the polymer on the silicon interface modified by the silane coupling agent.

6. According to the method described in item 5, the inorganic silicon is crystalline silicon, and the polymer is a polymer that can serve as a hole transport layer; preferably, the surface of the crystalline silicon is passivated.

7. The method according to item 6, wherein the inorganic silicon pretreatment step comprises:

The crystalline silicon is immersed in the Piranha solution for more than 12 hours, wherein the mass percentage of H ₂ O ₂ in the Piranha solution is greater than 5% and less than or equal to 40%; preferably, the crystalline silicon is immersed in the Piranha solution for more than 24 hours.

8. The method as described in item 6, wherein the alkylation reaction step comprises: immersing the pretreated crystalline silicon in an organic solution of a silane coupling agent as described in any one of items 1 to 4, preferably for 6 to 12 hours.

9. The method according to item 6, wherein the polymerization step comprises:

The crystalline silicon after the alkylation reaction is placed in an organic solution containing an oxidant and a polymer monomer. Polymerizing on the silicon interface modified by the silane coupling agent to form a hole transport layer;

Preferably, the polymerization reaction is carried out at 80 to 130° C., and after uniform stirring for 30 to 60 minutes, a hole transport layer with a thickness of 200 to 1000 nm is formed.

10. The method according to item 6, wherein the polymerization step comprises:

Under vacuum conditions, oxidants and polymer monomers are evaporated on the crystalline silicon after the alkylation reaction, and polymerized on the silicon interface modified by the silane coupling agent to form a hole transport layer;

Preferably, the evaporation is performed at 80 to 130° C., and after 1 to 2 hours of evaporation, a hole transport layer with a thickness of 200 to 1000 nm is formed.

11. A solar cell comprising a cell absorption layer and a hole transport layer formed of a polymer;

Wherein, the battery absorption layer and the hole transport layer are connected by the silane coupling agent described in any one of items 1 to 4; or, the battery absorption layer and the hole transport layer are connected by the method described in any one of items 5 to 10.

12. The solar cell as described in item 11, wherein the solar cell comprises the hole transport layer, the alkyl coupling agent layer, the battery absorption layer, and the electron transport layer in sequence.

13. In the solar cell as described in item 11, at least one side of the solar cell absorption layer has been passivated.

The silane coupling agent provided by the present application can connect inorganic silicon and the polymer generated by polymerization through covalent bonds, thereby significantly improving the bonding force compared with the connection method relying on hydrogen bonds in the prior art; in addition, when the connected polymer is a polymer as a hole transport layer, the silane coupling agent can firmly connect the inorganic (such as crystalline silicon) and organic (such as hole transport layer) interfaces in the solar cell; when R is a methylene or ethylene group, the influence on the conductivity of the hole transport layer generated by polymerization is also small, thereby improving the conversion efficiency of the solar cell and being able to passivate the crystalline silicon surface well. At the same time, the present application also provides a method and a solar cell for connecting the corresponding silane coupling agent to the polymer generated by polymerization.

In order to solve the problem that the existing method of chemically pretreating the surface of the silicon substrate to promote the interface uniformity during spin coating cannot cope with the structural hydrophobicity caused by the small size of the nanostructure, so that the liquid cannot enter the nanostructure, the present application provides an organic-crystalline silicon heterojunction battery and a method for forming a hole transport layer on a silicon substrate. The technical solution of the present application is as follows:

1. An organic-crystalline silicon heterojunction battery, comprising:

A silicon substrate, wherein a textured surface is formed on at least one surface of the silicon substrate;

An organic and silicon-free hole transport layer, the hole transport layer being located on a surface of the suede and extending to the bottom of the channel of the suede;

The electron transport layer is located on the opposite side of the hole transport layer of the silicon substrate.

2. In the organic-crystalline silicon heterojunction cell as described in item 1, the material of the hole transport layer is a polymer; preferably, the material of the hole transport layer is selected from one or a combination of more than two of PEDOT, P3HT, P3OHT and P3ODDT.

3. In the organic-crystalline silicon heterojunction cell as described in item 2, the hole transport layer extending to the bottom of the channel of the velvet surface is formed by polymerization of monomers forming the hole transport layer initiated by an oxidant filled in the channel.

4. The organic-crystalline silicon heterojunction cell as described in item 2,

The silicon substrate and the hole transport layer are connected by a silane coupling agent;

The silane coupling agent is YR-SiX ₃ , wherein Y represents a monomer of the polymer of the hole transport layer, R represents an alkylene group, and SiX ₃ can be hydrolyzed and connected to the surface of the silicon substrate.

5. In the organic-crystalline silicon heterojunction cell as described in item 1, the hole transport layer comprises: a first hole transport layer located at the bottom of the channel of the velvet surface; and a second hole transport layer attached to the upper surface of the velvet surface and the first hole transport layer.

6. In the organic-crystalline silicon heterojunction cell as described in item 5, the material of the first hole transport layer is selected from one or a combination of two or more of PEDOT, P3HT, P3OHT and P3ODDT; the material of the second hole transport layer is selected from one or a combination of two or more of PEDOT:PSS and PEDOT:F.

7. In the organic-crystalline silicon heterojunction cell as described in any one of items 1 to 6, the conductivity σ of the hole transport layer is >10 S/cm, the thickness of the hole transport layer is 400 to 1100 nm, and the transmittance T of the hole transport layer is >90%.

8. A method for forming a hole transport layer on a silicon substrate, comprising: a coating step, coating oxidant particles on at least one of the velvet surfaces of crystalline silicon, wherein the particle size D50 of the oxidant particles is ≤100 nm; a polymerization step, adding monomers for forming a hole transport layer on the velvet surface coated with the oxidant particles and performing a polymerization reaction to generate the hole transport layer.

9. The method as described in item 8, wherein the coating step comprises scraping and physical vapor deposition; preferably, the oxidant particles are coated by physical vapor deposition; further preferably, the oxidant particles are The coating thickness is 5 to 20 nm.

10. According to the method described in item 8, the particle size D50 of the oxidant particles is ≤40nm.

11. The method as described in item 8, wherein the polymerization step comprises: forming a monomer of a hole transport layer on a velvet surface coated with oxidant particles by chemical vapor deposition and performing a polymerization reaction; preferably, in the chemical vapor deposition polymerization, the reactor contains an organic solution of a polar Lewis acid and 0.2 to 2 M monomers of the hole transport layer polymer, and the chemical vapor deposition polymerization is reacted at a temperature of 110°C to 150°C for 1 to 2 hours.

12. The method as described in item 8, wherein the monomer of the hole transport layer polymer is selected from one or more of EDOT, 3HT, 3OHT and 3ODDT.

13. The method as described in item 8,

Before the coating step, the method further comprises:

A silane coupling agent modification step, wherein the silane coupling agent modification step comprises:

A pretreatment sub-step, pretreatment to make the surface of the silicon substrate have hydroxyl groups;

an alkylation reaction sub-step, using a silane coupling agent to undergo a substitution reaction with the pretreated silicon substrate to obtain a silicon interface modified by the silane coupling agent;

The silane coupling agent is YR-SiX ₃ , wherein:

Y represents a monomer forming the polymer of the hole transport layer,

R is an alkylene group,

SiX ₃ can hydrolyze and connect to the surface of the silicon substrate.

14. The method as described in any one of items 8 to 13, further comprising washing away impurities in the hole transport layer after chemical vapor deposition polymerization; preferably, 6 to 12 M hydrochloric acid is used to wash away impurities in the hole transport layer.

15. The method as described in item 14, after washing away the impurities in the hole transport layer, further doping the hole transport layer by means of an acidic solution or steam.

16. A method for forming a hole transport layer on a silicon substrate, comprising:

A filling step, disposing particles of a material of a first hole transport layer at the bottom of a trench of at least one velvet surface of the silicon substrate, wherein the particle size D50 of the material of the first hole transport layer is ≤100 nm;

The forming step is to form a second hole transport layer on the suede surface on which the nano-sized particles of the first hole transport layer material are arranged.

17. The method of claim 16, wherein the filling step comprises scraping or physical vapor deposition; Preferably, physical vapor deposition is used to fill nano-scale particles of the material of the first hole transport layer; further preferably, the filling thickness of the nano-scale particles of the material of the first hole transport layer is 5 to 20 nm.

18. In the method described in item 16, the particle size D50 of the material of the first hole transport layer is ≤40 nm.

19. According to the method described in item 16, the material of the first hole transport layer is selected from one or a combination of two or more of PEDOT, P3HT, P3OHT and P3ODDT; the material of the second hole transport layer is selected from one or a combination of two or more of PEDOT:PSS and PEDOT:F.

20. According to the method described in item 16, the forming step is to form the second hole transport layer by spin coating.

By the organic-crystalline silicon heterojunction cell provided by the present application, it can form a scheme of a hole transport layer by initiating polymerization in an oxidant in the channel, or by a first hole transport layer located at the bottom of the channel of the velvet, a second hole transport layer attached to the velvet, the scheme of the upper surface of the first hole transport layer, so that the hole transport layer is located at a velvet surface and extends to the bottom of the channel of the velvet, so that the hole transport layer and the silicon substrate (crystalline silicon) are coated evenly, without pores, and effective contact is formed, thereby improving the battery efficiency, and at the same time, the polymer used has no water absorption, so that the stability of the device can be greatly improved. In particular, when the silane coupling agent provided by the present application is YR-SiX ₃ , the connection strength between the silicon substrate and the hole transport layer can be increased, and the influence on the conductivity of the hole transport layer generated by polymerization can be further avoided and the conversion efficiency of the solar cell can be improved. In addition, the present application provides a method for forming a hole transport layer on a silicon substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

Figure 1: Schematic diagram of crystalline silicon pretreatment steps and alkylation reaction steps;

Figure 2: Polymerization steps using the liquid phase method;

Figure 3: Polymerization steps using a gas phase process;

Figure 4: Schematic diagram of the structure of a solar cell containing a silane coupling agent;

Figure 5: Schematic diagram of a solar cell structure without a silane coupling agent;

Figure 6: Schematic diagram of the connection between inorganic and organic interfaces by silane coupling agents in the prior art;

FIG7 is a schematic diagram of a silicon substrate and a hole transport layer structure provided by the present application;

Figure 8: Schematic diagram of setting an oxidant provided by the present application;

FIG9 is a schematic diagram of a process for forming a hole transport layer on a silicon substrate surface provided by the present application;

FIG10 is a schematic diagram of the structure of an organic-crystalline silicon heterojunction cell in one embodiment provided in the present application;

FIG11 is a schematic diagram of the structure of an organic-crystalline silicon heterojunction cell in a comparative example provided in the present application;

FIG12 is an electron microscope image of a silicon substrate and a hole transport layer in the prior art;

FIG13 is a schematic diagram of liquid phase spin coating in the prior art;

FIG. 14 is a schematic diagram showing the structure of forming a hole transport layer by liquid phase spin coating on the surface of a silicon substrate in the prior art.

Reference numerals:
1. Silicon substrate; 2. Oxidant; 3. Hole transport layer; 4. TOC conductive layer; 5. PEDOT:PSS
solution; 6. pores; 7. electron transport layer; 11. battery absorption layer; 12. first passivation layer; 13. silane coupling agent; 14. second passivation layer.

Specific embodiments

The following embodiments of the present application are only used to illustrate the specific embodiments of the present application, and these embodiments cannot be understood as limiting the present application. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present application are deemed to be equivalent replacement methods and fall within the scope of protection of the present application.

In one embodiment, a silane coupling agent is provided, which can be used to connect inorganic silicon and polymer. The silane coupling agent is YR-SiX ₃ , wherein Y represents a monomer forming the polymer, R is an alkylene group, and SiX ₃ is a surface that can be hydrolyzed and connected to the inorganic silicon.

In this embodiment, there is no particular limitation on the structure of Y, as long as it is a polymerizable monomer and can be polymerized together with the polymer monomer to generate the polymer. In this case, the silane coupling agent can be used to connect the inorganic silicon with the polymer.

In this embodiment, there is no specific limitation on the inorganic silicon to which the silane coupling agent can be connected, as long as it can be pre-treated so that the inorganic silicon surface has hydroxyl groups, and specific examples include crystalline silicon (such as single crystal Silicon, polycrystalline silicon), amorphous silicon, silicon oxide, etc.

In the present embodiment, X in SiX ₃ can be any group as long as it can be hydrolyzed to form silanol (Si(OH) 3 ) and can be combined with inorganic silicon. Specific examples include chloro, methoxy, ethoxy, methoxyethoxy, acetoxy, and the like.

As introduced in the background art, the prior art relies on hydrogen bonds to connect with the hole transport layer, but the bond energy of hydrogen bonds is relatively weak, which reduces the stability of the interface connection.

In the silane coupling agent provided in this embodiment, on the one hand, the hydrolyzed groups of SiX ₃ (siloxane) can passivate and connect (through Si-O covalent bonds (Si-O bond energy is 121 kJ/mol)) the surface of pre-treated (surface with hydroxyl groups) inorganic silicon (such as crystalline silicon); on the other hand, Y is a monomer of a polymer, which can participate in the polymerization reaction between polymer monomers and generate a polymer. The silane coupling agent provided in this embodiment can respectively connect the inorganic silicon and the polymer generated by polymerization through covalent bonds, and its bonding force is much stronger than the connection method relying on hydrogen bonds in the prior art.

In one embodiment, the inorganic silicon is crystalline silicon, and the polymer is a polymer capable of serving as a hole transport layer.

As introduced in the background technology, silane coupling agents have been used in current solar cells to bond the inorganic (such as crystalline silicon) and organic (such as hole transport layer) interfaces, but they rely on hydrogen bonds to connect to the hole transport layer. Since the hydrogen bond energy is weak, the stability of the interface connection is reduced.

In this embodiment, the polymer is limited to the range of polymers that can be used as a hole transport layer, and accordingly, Y represents a monomer of the polymer. The silane coupling agent provided in this embodiment can be used to connect the inorganic (such as crystalline silicon) and organic (such as hole transport layer) interfaces in solar cells, thereby increasing the connection strength of the solar cell, increasing the durability of the solar cell (such as being able to be used in environments with more severe conditions) and the service life.

Specifically, the polymer that can be used as the hole transport layer includes polymers such as thiophene polymers, and accordingly, Y is a monomer of the polymer, and specifically can be a thiophene compound, etc. More specifically, when Y is a thiophene compound, it can be one of EDOT, 3HT, 3OHT, 3ODDT, and thiophene.

In addition, the surface of the crystalline silicon may also be passivated to form a passivation layer, wherein the passivation layer is one of amorphous silicon, silicon oxide, crystalline silicon, and the like.

In one embodiment, R is methylene or ethylene.

As described in the background art, in the prior art solar cells, due to the insulating property of the silane coupling agent itself, the photogenerated carriers in the crystalline silicon cannot be fully diffused to the hole transport layer, resulting in a loss in the conversion efficiency of the solar cell.

In the silane coupling agent provided in this embodiment, the number of carbon atoms in the alkyl group R is less than or equal to 2 (methylene or ethylene), which not only avoids the steric hindrance effect caused by the presence of π electron cloud groups (such as benzene rings, five-membered heterocycles, etc.) in the R group, thereby avoiding the influence on the conductivity of the hole transport layer generated by polymerization, and improving the conversion efficiency of solar cells, but also avoids the influence of the close-packed passivation of _SiX3 and the crystalline silicon surface, and can passivate the crystalline silicon surface well. At the same time, the chain length is very short, thereby further avoiding the influence on the conductivity of the hole transport layer generated by polymerization and improving the conversion efficiency of solar cells.

Preferably, R is -CH ₂ -(methylene), which has low steric hindrance and little effect on the conductivity of the hole transport layer generated by polymerization, thereby improving the conversion efficiency of the solar cell and passivating the crystalline silicon surface well.

In one embodiment, as shown in FIG1 , a method for connecting inorganic silicon and a polymer is provided, comprising:

A pretreatment step, pretreatment to make the surface of the inorganic silicon have hydroxyl groups;

an alkylation reaction step, wherein the above-mentioned silane coupling agent (wherein Y is EDOT and SiX ₃ is -Si(OEt) ₃ ) is used to undergo a substitution reaction with the pretreated inorganic silicon to obtain a silicon interface modified by the silane coupling agent;

The polymerization step is to perform a polymerization reaction on the surface of the inorganic silicon after the alkylation reaction to form a polymer (PEDOT) on the silicon interface modified by the silane coupling agent in the inorganic silicon.

In the present application, the alkylation reaction refers to the reaction of introducing an alkyl group (-R) into atoms such as carbon, nitrogen, and oxygen in organic molecules, referred to as alkylation.

This embodiment provides a method for connecting inorganic silicon and polymer using the above-mentioned silane coupling agent. First, the inorganic silicon is pretreated so that the inorganic silicon surface has hydroxyl groups; then, through an alkylation reaction, the groups hydrolyzed from SiX ₃ (siloxane group) in the silane coupling agent are passivated and connected to the surface of the inorganic silicon (such as crystalline silicon) after pretreatment (with hydroxyl groups on the surface) (replacing -OH), thereby obtaining a silicon interface modified by the silane coupling agent, so that the silane coupling agent provided in this embodiment connects the inorganic silicon through a covalent bond; then, polymerizes on the silicon interface modified by the silane coupling agent to generate a polymer, so that this embodiment The silane coupling agent provided in the embodiment connects the polymer generated by polymerization through covalent bonds.

Through the above method, the silane coupling agent provided in this embodiment can connect the inorganic silicon and the polymer generated by polymerization through covalent bonds, and its bonding force is much stronger than the connection method relying on hydrogen bonds in the prior art.

In one embodiment, the inorganic silicon is crystalline silicon, and the polymer is a polymer capable of serving as a hole transport layer.

The method provided in this embodiment can be used to connect crystalline silicon and a hole transport layer. More specifically, the method provided in this embodiment can be used to connect crystalline silicon and a hole transport layer in a solar cell. Thus, compared with the connection of crystalline silicon and a hole transport layer through an existing silane coupling agent introduced in the background technology, the silane coupling agent provided in this embodiment connects the crystalline silicon and the hole transport layer respectively through covalent bonds, thereby increasing the connection strength of the solar cell, increasing the durability of the solar cell (such as being able to be used in an environment with more severe conditions) and the service life.

The types of polymers that can be used as the hole transport layer and the corresponding types of Y (monomers of the polymer) have been introduced above and will not be repeated here.

In addition, the surface of the crystalline silicon may also be passivated to form a passivation layer, wherein the passivation layer is one of amorphous silicon, silicon oxide, crystalline silicon, and the like.

In one embodiment, as shown in FIG1 , the inorganic silicon pretreatment (hydroxylation) step includes: immersing the crystalline silicon in a Piranha solution for more than 12 hours, wherein the mass percentage of H ₂ O ₂ in the Piranha solution is greater than 5% and less than or equal to 40%; preferably, immersing the crystalline silicon in the Piranha solution for more than 24 hours to ensure sufficient hydroxylation. In addition, the inorganic silicon pretreatment (hydroxylation) process can be performed once or multiple times to ensure sufficient hydroxylation.

This embodiment mainly provides a specific form of the inorganic silicon pretreatment step, so that -OH can be introduced on the surface of crystalline silicon to facilitate subsequent bonding.

In one embodiment, as shown in FIG. 1 , the alkylation reaction step comprises: immersing the pretreated crystalline silicon in the organic solution of the silane coupling agent, preferably for 6 to 12 hours, so that the alkylation reaction is fully carried out, so that the hydroxyl group (-OH) is fully replaced to obtain a silane coupling agent-silicon interface, so that the silane coupling agent provided in this embodiment can be connected to the crystalline silicon through a covalent bond.

In one embodiment, as shown in FIG2 , a liquid phase method (i.e., in a liquid phase) polymerization step is provided, comprising:

The crystalline silicon after the alkylation reaction is placed in an organic solution containing an oxidant and a polymer monomer, and polymerized on the silicon interface modified by a silane coupling agent to form a hole transport layer;

Preferably, the polymerization reaction is carried out at 80-130° C., and after uniform stirring for 30-60 min, a hole transport layer with a thickness of 200-1000 nm is formed.

This embodiment provides a polymerization reaction in a liquid phase, wherein the polymerization reaction is initiated by an oxidant to the polymer monomer in the liquid phase and Y (polymer monomer) in the silane coupling agent to generate a polymer (hole transport layer). Thus, the silane coupling agent provided in this embodiment can connect the polymer (hole transport layer) generated by polymerization through covalent bonds. This increases the adhesion of the silane coupling agent to the polymer (hole transport layer).

In one embodiment, as shown in FIG3 , a gas phase method (i.e., in the gas phase) is provided as the polymerization step, comprising:

Under vacuum conditions, oxidants and polymer monomers are evaporated on the crystalline silicon after the alkylation reaction, and polymerized on the silicon interface modified by the silane coupling agent to form a hole transport layer;

Preferably, the evaporation is performed at 80 to 130° C., and after 1 to 2 hours of evaporation, a hole transport layer with a thickness of 200 to 1000 nm is formed.

This embodiment provides a polymerization reaction in the gas phase, wherein the polymer monomers of the evaporated polymer and Y (monomer of the polymer) in the silane coupling agent are polymerized by an oxidant to generate a polymer (hole transport layer). Thus, the silane coupling agent provided in this embodiment can connect the polymer (hole transport layer) generated by polymerization through covalent bonds. This increases the adhesion of the silane coupling agent to the polymer (hole transport layer).

In one embodiment, as shown in FIG4 , a solar cell is provided, which includes a cell absorption layer 11 (crystalline silicon) and a hole transport layer 3 formed of a polymer; wherein the cell absorption layer 11 (crystalline silicon) and the hole transport layer are connected by the above-mentioned silane coupling agent 13. The connection of the cell absorption layer 11 (crystalline silicon) and the hole transport layer 3 by the silane coupling agent 13 can be achieved by the above-mentioned liquid phase method or gas phase method.

Specifically, the solar cell includes the hole transport layer 1, the alkyl coupling agent layer 3, the battery absorption layer 11 (crystalline silicon), and the electron transport layer in sequence. In addition, the battery absorption layer 11 (crystalline silicon) can be passivated on at least one side to form a passivation layer, and the passivation layer is one or more of amorphous silicon, silicon oxide, polycrystalline silicon, etc.

From the above content, it can be known that the bonding force between the battery absorption layer 11 (crystalline silicon) connected by the silane coupling agent provided in the above embodiment or the above method and the hole transport layer 3 is much stronger than the connection method relying on hydrogen bonds in the prior art. Thus, the connection strength of the solar cell is increased, and the durability of the solar cell (such as being able to be used in an environment with more severe conditions) and the service life are increased.

Example

The experimental methods used below are conventional methods unless otherwise specified.

Unless otherwise specified, the materials and reagents used below can be obtained from commercial sources.

Example 1

Embodiment 1 provides a solar cell, as shown in FIG4 , which includes, from top to bottom:

The hole transport layer 3 is a PEDOT film with a thickness of 100 nm;

Silane coupling agent 13, whose molecular formula is EDOT-CH ₂ -Si(OEt) ₃ and whose thickness is 3 nm;

The first passivation layer 12 is amorphous silicon with a thickness of 10 nm;

The battery absorption layer 11 is P-type crystalline silicon with a thickness of 160 μm;

The second passivation layer 14 is amorphous silicon with a thickness of 10 nm;

The electron transport layer 7 is TiO2 and has a thickness of 60 nm.

The silane coupling agent is used to connect the hole transport layer 3 and the battery absorption layer 11 through the above-mentioned gas phase method.

The solar cell obtained in the above Example 1 was tested:

1) The first passivation layer 12, the silane coupling agent 13, and the hole transport layer 3 are connected by covalent bonds, and the coating does not fall off after the Scotch Tape test and ultrasonic cleaning.

2) The conductivity of the first passivation layer 12 and the hole transport layer 3 is tested by double probes.

3) The interfacial bonding strength between the first passivation layer 12, the silane coupling agent 13, and the hole transport layer 3 of the battery is measured by Scotch Tape test.

Comparative Example 1

The solar cell provided in Comparative Example 1 is different from the solar cell in Example 1 only in that the silane coupling agent used is a silane coupling agent in existing literature (see FIG. 4 for the structure and FIG. 6 for the connection method).

The solar cell obtained in the above comparative example 1 was tested:

1) Layers 2 and 3 are connected by covalent bonds, and layers 3 and 4 are connected by hydrogen bonds, and can pass the Scotch Tape test appropriately; however, after ultrasonic cleaning, the transmission layers fall off.

2) The conductivity of the first passivation layer 12 and the hole transport layer 3 was tested by double probes. The conductivity was slightly lower than that of Example 1.

3) Through the Scotch Tape test, the interfacial bonding strength between the first passivation layer 12, silane coupling agent 13, and hole transport layer 3 of the battery is slightly lower than that in Example 1.

Comparative Example 2

The solar cell provided in Comparative Example 2 differs from the solar cell in Example 1 only in that the solar cell does not contain the silane coupling agent 13 (see FIG. 5 ), and the hole transport layer 3 is prepared by the existing spin coating method.

The solar cell obtained in the above comparative example 2 was tested:

1) The 2nd and 4th layers are connected by van der Waals forces, and the conditional (more difficult) Scotch Tape test shows coating peeling.

2) The conductivity of the first passivation layer 12 and the hole transport layer 3 was tested by double probes. The conductivity was significantly reduced compared with that of Example 1.

3) Through the Scotch Tape test, the interfacial bonding strength between the first passivation layer 12, the silane coupling agent 13, and the hole transport layer 3 of the battery is greatly reduced compared with that in Example 1.

By comparing the test results of the solar cell obtained by the above-mentioned embodiment 1 with the test results of the solar cell obtained by comparative example 1 and comparative example 2, it can be clearly seen that the use of the silane coupling agent provided by the present application can, on the one hand, respectively connect the inorganic silicon and the polymerized polymer through covalent bonds, so that the connection between the hole transport layer 3 and the first passivation layer 12 can be made more firmly, thereby increasing the durability and service life of the solar cell; on the other hand, the influence on the conductivity of the hole transport layer is also small, thereby improving the conversion efficiency of the solar cell; at the same time, it also improves the interface of the battery. Combination force.

In one embodiment, an organic-crystalline silicon heterojunction cell is provided, as shown in FIG. 7 , FIG. 10 , etc., comprising:

A silicon substrate 1 (crystalline silicon), wherein a textured surface is formed on at least one surface of the silicon substrate 1;

An organic and silicon-free hole transport layer 3, the hole transport layer 3 is located on a surface of the suede and extends to the bottom of the channel of the suede;

The electron transport layer 7 is located on the opposite side of the hole transport layer of the silicon substrate. Specifically, the electron transport layer 7 is prepared by plasma enhanced chemical vapor deposition.

In addition, as required, a TCO conductive layer 4 may be disposed on the surface of the hole transport layer 3 and the electron transport layer 7. The TCO conductive layer 4 may be deposited by reactive ion deposition or sputtering.

As described in the background technology and Figures 12 to 16, in the organic-crystalline silicon heterojunction battery of the prior art, pores (such as the positions indicated by the arrows in Figure 12) are formed between the silicon substrate and the hole transport layer (specifically at the bottom of the channel of the velvet surface, which is the bottom of the valley for the pyramid structure velvet and the pits on the surface of the silicon substrate for the inverted pyramid structure), resulting in a large number of recombination of holes generated by the photoelectric effect at the interface, thereby reducing the open circuit voltage and the battery efficiency.

The organic-crystalline silicon heterojunction cell provided in this embodiment, as shown in FIG. 7 and FIG. 10, is an improvement on the above-mentioned existing organic-crystalline silicon heterojunction cell, in which the hole transport layer is attached to the surface of the velvet surface and extends all the way to the bottom of the channel of the velvet surface (the bottom of the pyramid structure velvet, and the pit on the surface of the silicon substrate for the inverted pyramid structure), and there are no pores between the silicon substrate 1 and the hole transport layer 3. This avoids the large-scale recombination of holes generated by the photoelectric effect at the interface in the prior art, and more carriers are transported from the silicon substrate to the transport layer, thereby increasing the open circuit voltage of the battery and improving the battery efficiency compared with the prior art.

In addition, it should be noted that in this embodiment and the following embodiments and implementations thereof, the silicon substrate may include a passivation layer formed by passivation treatment on its surface, and the passivation layer does not affect the implementation of the embodiments and implementations thereof.

In one embodiment, the material of the hole transport layer is a polymer.

For example, existing polymers such as PEDOT, P3HT, P3OHT and One or a combination of two or more P3ODDTs.

Then, the hole transport layer can be obtained by coating an oxidant (capable of initiating polymerization reaction) with a particle size D50≤100 nm to the channels of the texture surface and polymerizing the monomer of the hole transport layer polymer (generally liquid organic matter) in situ.

It should be noted that the particle size (D50) of the present application is an online particle size distribution measured using a portable aerosol spectrometer (GRIMM, model 11-C).

Preferably, the silicon substrate (crystalline silicon) and the hole transport layer are connected by a silane coupling agent;

Wherein, the silane coupling agent is YR-SiX ₃ , Y represents a monomer of a polymer forming the hole transport layer, R represents an alkylene group, and SiX ₃ can be hydrolyzed and connected to the surface of the silicon substrate.

In this embodiment, the material of the hole transport layer is limited to polymers.

Then, the silicon substrate and the hole transport layer can be connected by the above-mentioned silane coupling agent. On the one hand, the hydrolyzed group of SiX ₃ (siloxane group) can passivate and connect the surface of the pre-treated silicon substrate (so that the surface has hydroxyl groups) (through Si-O covalent bonds (Si-O bond energy is 121kJ/mol)); on the other hand, Y is a monomer of a polymer, which can participate in the polymerization reaction between polymer monomers and generate a polymer. The silane coupling agent provided in this embodiment can be respectively connected to the silicon substrate and the hole transport layer (polymer) generated by polymerization through covalent bonds, thereby enhancing the bonding strength between the silicon substrate and the hole transport layer.

When -R- in the silane coupling agent is an alkylene group, especially a methylene group or an ethylene group, the surface of the silicon substrate can be well passivated. At the same time, the chain length is very short, thereby further avoiding the influence on the conductivity of the hole transport layer generated by polymerization and improving the conversion efficiency of the solar cell. -R- in the coupling agent is preferably a methylene group.

In one embodiment, the hole transport layer includes: a first hole transport layer located at the bottom of the channel of the suede surface; and a second hole transport layer attached to the suede surface and the upper surface of the first hole transport layer.

Similar to the above-mentioned embodiment of forming a hole transport layer by initiating polymerization in an oxidant in the channel, this embodiment provides another way to fill the hole transport layer material at the bottom of the channel. Specifically, the hole transport layer provided in this embodiment includes two parts. The first part is a first hole transport layer, which is located at the bottom of the channel of the velvet surface; and the second hole transport layer is attached to the upper surface of the velvet surface and the first hole transport layer. Therefore, those skilled in the art know that, similar to the above embodiment, compared with the existing organic-crystalline silicon heterojunction battery in FIG. 14, the second hole transport layer is relatively The first hole transport layer fills the pores 6, so that there are no pores (porosity <5%) between the silicon substrate and the hole transport layer in the organic-crystalline silicon heterojunction cell provided in this embodiment. This avoids the large-scale recombination of holes generated by the photoelectric effect in the prior art at the interface, thereby improving the open circuit of the cell and the cell efficiency compared with the prior art.

In this embodiment, there is no specific limitation on the materials of the first hole transport layer and the second hole transport layer, as long as they can function as hole transport layers. The first hole transport layer and the second hole transport layer can be made of the same material or different materials.

Specifically, the material of the first hole transport layer is selected from one or a combination of two or more of PEDOT, P3HT, P3OHT and P3ODDT. The material of the second hole transport layer can be selected from one or a combination of two or more of PEDOT:PSS (water system) and PEDOT:F (alcohol system), so as to facilitate the formation of the second hole transport layer through the existing spin coating process after filling the material of the first hole transport layer.

In one embodiment, the conductivity σ of the hole transport layer is greater than 10 S/cm, the thickness of the hole transport layer is 400-1100 nm, and the transmittance T of the hole transport layer is greater than 90%.

The hole transport layer of the organic-crystalline silicon heterojunction cell needs to have high conductivity and high light transmittance. However, the conductivity of the hole transport layer material increases with its thickness, while the light transmittance decreases. When a hole transport layer with the above parameters is used, high conductivity and high light transmittance can be achieved at the same time.

In one embodiment, a method for forming a hole transport layer on a silicon substrate is provided, as shown in FIG9 , comprising:

A coating step, coating oxidant particles on at least one velvet surface of the silicon substrate, wherein the particle size D50 of the oxidant particles is ≤100 nm;

The polymerization step is to add a monomer (generally a liquid organic substance) for forming a hole transport layer polymer onto the velvet surface on which the oxidant particles are arranged and to perform a polymerization reaction to generate a hole transport layer.

In this embodiment, firstly, oxidant particles (capable of initiating polymerization reaction) with a particle size D50≤100nm are coated on the suede surface. Since the upper size of the suede channel is generally micrometer-level (such as 1-2μm), the oxidant can easily reach the bottom of the suede channel, thereby being uniformly coated on the suede surface. A layer of oxidant particles is formed, and then the polymer material monomer of the hole transport layer grows in situ at the oxidant, so that a hole transport layer that is closely attached to the silicon substrate (such as a pyramid structure or an inverted pyramid velvet surface) (without pores) can be formed. Compared with the organic-crystalline silicon heterojunction cell provided in the prior art in which the silicon substrate and the hole transport layer have pores (as shown in Figure 14), the organic-crystalline silicon heterojunction cell with such a silicon substrate and the hole transport layer closely attached avoids the large-scale recombination of holes generated by the photoelectric effect in the prior art at the interface, thereby improving the open circuit of the cell and the cell efficiency compared with the prior art.

The material of the hole transport layer is selected from one or more of PEDOT, P3HT, P3OHT and P3ODDT.

In addition, preferably, the particle size D50 of the oxidant particles is ≤40 nm, so that the oxidant particles can better cover the bottom of the channel from the velvet surface to the velvet surface.

In one embodiment, the coating step comprises knife coating, physical vapor deposition (PVD).

This embodiment provides a specific implementation method of the coating step, wherein physical vapor deposition (PVD) is preferably used to coat the oxidant particles because the film is easily and uniformly deposited and has high deposition efficiency.

The thickness of the oxidant coating is 5 to 20 nm. On the one hand, it can provide sufficient oxidant for polymerization to form a hole transport layer. On the other hand, it also allows the oxidant to fully participate in the reaction, so that the generated hole transport layer fits tightly to the silicon substrate, preventing excessive oxidant residue from affecting battery performance.

In one embodiment, the polymerization step is achieved by chemical vapor deposition polymerization. Through chemical vapor deposition, the polymer monomer can be more uniformly polymerized on the velvet surface of the silicon substrate to form a hole transport layer with a more uniform thickness. In the chemical vapor deposition polymerization, a reactor contains a polar Lewis acid and an organic solution of a polymer monomer of 0.2 to 2M (such as 1.56M) of a hole transport layer material, and the chemical vapor deposition polymerization is reacted at a temperature of 110°C to 150°C for 1 to 2 hours.

In one embodiment, as shown in FIG. 1 and FIG. 3 , before the coating step, the method further comprises:

A silane coupling agent modification step, wherein the silane coupling agent modification step comprises:

A pretreatment sub-step, pretreatment to make the surface of the silicon substrate (crystalline silicon) have hydroxyl groups;

an alkylation reaction sub-step, using a silane coupling agent to undergo a substitution reaction with the pretreated silicon substrate to obtain a silicon interface modified by the silane coupling agent;

Wherein, the silane coupling agent is YR-SiX ₃ , Y represents a monomer of a polymer forming the hole transport layer, R represents an alkylene group, and SiX ₃ can be hydrolyzed and connected to the surface of the silicon substrate.

The embodiment further adds a silane coupling agent modification step before the coating step, so that, first, the surface of the silicon substrate is provided with hydroxyl groups through a pretreatment sub-step, and then the _-SiX3 in the silane coupling agent is hydrolyzed and connected (via covalent bonds) to the silicon substrate through an alkylation reaction sub-step to obtain a silicon interface modified by the silane coupling agent, and then the above-mentioned coating step and polymerization step are performed, and polymerization is performed on the silicon interface modified by the silane coupling agent (-Y in the silane coupling agent participates in the polymerization reaction as a chain end) to form a hole transport layer, so that the silane coupling agent can be connected to the hole transport layer through a covalent bond.

Therefore, the silane coupling agent in this embodiment connects the silicon substrate and the hole transport layer respectively through covalent bonds, thereby increasing the connection strength between the silicon substrate and the hole transport layer.

When -R- in the silane coupling agent is an alkylene group, especially a methylene group or an ethylene group, the surface of the silicon substrate can be well passivated. At the same time, the chain length is very short, thereby further avoiding the influence on the conductivity of the hole transport layer generated by polymerization and improving the conversion efficiency of the solar cell. -R- in the coupling agent is preferably a methylene group.

As for SiX ₃ in the silane coupling agent, any one of them can be hydrolyzed to form silanol (Si(OH) ₃ ) and can be bonded to the silicon substrate (replacing -OH), and specific examples thereof include chloro, methoxy, ethoxy, methoxyethoxy, and acetoxy groups.

The pretreatment (hydroxylation) sub-step specifically includes: immersing the crystalline silicon in a Piranha solution for more than 12 hours, wherein the mass percentage of H ₂ O ₂ in the Piranha solution is greater than 5% and less than or equal to 40%, so that -OH can be introduced on the surface of the crystalline silicon to facilitate subsequent bonding.

The alkylation reaction sub-step specifically includes: immersing the pretreated (hydroxylated) crystalline silicon in the organic solution of the silane coupling agent, preferably for 6 to 12 hours, so that the alkylation reaction is fully carried out, so that the hydroxyl group (-OH) is fully replaced to obtain a silane coupling agent-silicon interface, so that the silane coupling agent provided in this embodiment can be connected to the crystalline silicon through a covalent bond.

In one embodiment, after chemical vapor deposition polymerization, the impurities in the hole transport layer are washed away, such as using 6-12M hydrochloric acid to wash away the impurities in the hole transport layer. Thus, a pure hole transport layer can be obtained, the hole transport efficiency is improved, and it is beneficial to improve the prepared organic-crystalline silicon Performance of heterojunction cells.

In one embodiment, after the impurities in the hole transport layer are washed away, the hole transport layer is doped with an acidic solution or steam. Specifically, the hole transport layer can be doped with an acidic solution or steam such as HCl, HBr and H ₂ SO ₄ (doping ions are Cl ^- , Br ^- , SO ₄ ^2- ), with a maximum theoretical doping degree of 33%. This can increase the carrier concentration and further improve the hole transport efficiency.

In one embodiment, another method for forming a hole transport layer on a silicon substrate is provided, comprising:

A filling step, as shown in FIG8 , is to arrange particles of a material of a first hole transport layer at the bottom of a trench of at least one velvet surface of the silicon substrate, wherein the particle size D50 of the material of the first hole transport layer is ≤100 nm;

The forming step is to form a second hole transport layer on the suede surface on which the nano-sized particles of the first hole transport layer material are arranged.

That is, first, the particles of the material of the first hole transport layer are filled in the channel of the velvet. Since the upper size of the general velvet channel is micron-sized (such as 1 to 2 μm), the particles of the first hole transport layer material with a particle size D50 ≤ 100 nm can easily reach the bottom of the channel of the velvet, so that the bottom of the velvet channel can be well filled. After that, a second hole transport layer is formed on the velvet. Thus, the hole transport layer formed in this embodiment includes two parts, the first part is the first hole transport layer, which is located at the bottom of the channel of the velvet; the second hole transport layer is attached to the upper surface of the velvet and the first hole transport layer. Compared with the existing organic-crystalline silicon heterojunction battery in Figure 14, the second hole transport layer is equivalent to the hole transport layer 3, and the first hole transport layer has a filling effect on the pores.

Then, in the organic-crystalline silicon heterojunction cell having the hole transport layer (including the first hole transport layer and the second hole transport layer) of this embodiment and the silicon substrate, there are no pores between the silicon substrate and the hole transport layer. Thus, a large number of holes generated by the photoelectric effect in the prior art are avoided from being recombined at the interface, thereby improving the open circuit of the cell and the cell efficiency compared with the prior art.

In this embodiment, there is no specific limitation on the materials of the first hole transport layer and the second hole transport layer, as long as they can function as hole transport layers. The first hole transport layer and the second hole transport layer can be made of the same material or different materials.

Specifically, the material of the first hole transport layer is selected from one or a combination of two or more of PEDOT, P3HT, P3OHT and P3ODDT. The material of the second hole transport layer can be selected from one or a combination of two or more of PEDOT:PSS and PEDOT:F, so as to facilitate the formation of the second hole transport layer through the existing spin coating process after filling the material of the first hole transport layer.

Preferably, the particle size D50 of the material of the first hole transport layer is ≤40nm, so that the material particles of the second hole transport layer can be filled to the bottom of the groove of the velvet surface, so that the hole transport layer can more evenly cover the velvet surface of the silicon substrate (crystalline silicon), and the porosity between the interface and the crystalline silicon is <5%.

In one embodiment, the filling step comprises doctor blading, physical vapor deposition.

Example

The experimental methods used below are conventional methods unless otherwise specified.

Unless otherwise specified, the materials and reagents used below can be obtained from commercial sources.

Example 1

Embodiment 1 provides an organic-crystalline silicon heterojunction cell, as shown in FIG10 , which includes, from top to bottom:

TOC conductive layer 4, with a thickness of 200nm, is deposited by reactive ion deposition.

The electron transport layer 7 is NiO with a thickness of 500 nm, prepared by plasma enhanced chemical vapor deposition;

The silicon substrate 1 (the surface is passivated and has a passivation layer SiO2 of 50 nm) is a p-type silicon wafer with a thickness of 150 μm. The surface of the silicon substrate 1 has a positive pyramid structure velvet surface, and the distance between the pyramid tops is 1 to 2 μm.

The hole transport layer 3 is a PEDOT film with a thickness of 1 μm;

TOC conductive layer 4, 200 nm thick, using reactive ion deposition;

The hole transport layer 3 is formed by:

An oxidant 2 (Fe ₂ O ₃ ) with a thickness of 5 to 20 nm is physically vapor deposited (PVD) on the surface of the silicon substrate 1 , and the particle size D50 of the oxidant 2 is less than 100 nm;

Chemical vapor deposition polymerization is used in an acid-resistant and organic solvent-resistant reactor, the reaction temperature range is 110°C to 150°C, and the reaction time is 1 to 2 hours; the reactor contains the reactants: 40 μL of polar Lewis acid and 200 μL of 1.56M organic solution (chlorobenzene) of hole material polymerization monomer (EDOT);

Solid iron oxide is used as an oxidant, which is converted into FeCl ₃ under the dissolution of concentrated hydrochloric acid to initiate a polymerization reaction to synthesize PEDOT. After the reaction is completed, a hole transport layer 3 containing FeCl ₂ impurities is obtained;

The impurities in the hole transport layer 3 are washed away using 12M hydrochloric acid to obtain a pure hole transport layer 3 .

PEDOT is doped using an acidic solution (HCl) or vapor such as HCl, HBr, and H ₂ SO ₄ (doping ions are Cl ^- , Br ^- , SO ₄ ^2- ).

According to tests, the efficiency of the organic-crystalline silicon heterojunction battery obtained in Example 1 is 24-26%, and because PEDOT has no water absorption, the stability of the device is greatly improved.

Comparative Example 1

The difference between Comparative Example 1 and Example 1 is only that the hole transport layer and the formation method of the hole transport layer are different.

The hole transport layer of Comparative Example 1 is a PEDOT:PSS film.

The hole transport layer is formed by spin coating a PEDOT:PSS solution on the surface of the silicon substrate 1 and drying it to form a PEDOT:PSS film with a thickness of 1 μm. The specific structure is shown in FIG11 .

After testing, the efficiency of the battery obtained in Comparative Example 1 is 21%, and due to the water absorption of PEDOT:PSS, the stability of the device is poor.

By comparing the above-mentioned Example 1 with the comparative example 1, it can be known that by forming a hole transport layer through the oxidant-initiated polymerization in the channel of the present application, the hole transport layer and the silicon substrate (crystalline silicon) can be evenly coated without pores, forming an effective contact, thereby improving the battery efficiency. At the same time, the polymer used is not hygroscopic, so the stability of the device can be greatly improved.

In addition, those skilled in the art know that, through the solution that the first hole transport layer of the present application is located at the bottom of the channel of the velvet surface, and the second hole transport layer is attached to the velvet surface and the upper surface of the first hole transport layer, the hole transport layer and the silicon substrate (crystalline silicon) can also be coated evenly without pores (porosity <5%), forming an effective contact. Therefore, it can also have the effect of improving battery efficiency; moreover, the first hole transport layer and the second hole transport layer are also not hygroscopic, so the stability of the device can also be greatly improved.

It should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used above to indicate positions or positional relationships are based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

Claims (33)

A silane coupling agent for connecting inorganic silicon and polymer, wherein: The silane coupling agent is YR-SiX ₃ , wherein: Y represents a monomer forming the polymer, R is an alkylene group, SiX ₃ can hydrolyze and connect to the surface of the inorganic silicon. The silane coupling agent according to claim 1, wherein The polymer is a polymer capable of serving as a hole transport layer; Preferably, the polymer is a thiophene polymer. The silane coupling agent according to claim 2, wherein Y is selected from one of EDOT, 3HT, 3OHT, 3ODDT and thiophene in the thiophene compounds. The silane coupling agent according to claim 2, wherein R is methylene or ethylene. A method for connecting inorganic silicon and a polymer, comprising: A pretreatment step, pretreatment to make the surface of the inorganic silicon have hydroxyl groups; an alkylation reaction step, wherein the silane coupling agent described in any one of claims 1 to 4 is used to undergo a substitution reaction with the pretreated inorganic silicon to obtain a silicon interface modified by the silane coupling agent; The polymerization step is to carry out a polymerization reaction on the surface of the inorganic silicon after the alkylation reaction to form the polymer on the silicon interface modified by the silane coupling agent. The method according to claim 5, wherein The inorganic silicon is crystalline silicon, and the polymer is a polymer that can serve as a hole transport layer; Preferably, the surface of the crystalline silicon is passivated. The method according to claim 6, wherein The inorganic silicon pretreatment step comprises: Immersing the crystalline silicon in a Piranha solution for more than 12 hours, wherein the mass percentage of H ₂ O ₂ in the Piranha solution is greater than 5% and less than or equal to 40%; Preferably, the crystalline silicon is immersed in the Piranha solution for more than 24 hours. The method according to claim 6, wherein The alkylation reaction step comprises: The pretreated crystalline silicon is immersed in a silane coupling agent according to any one of claims 1 to 4. The organic solution is preferably immersed for 6 to 12 hours. The method according to claim 6, wherein The polymerization step comprises: The crystalline silicon after the alkylation reaction is placed in an organic solution containing an oxidant and a polymer monomer, and polymerized on the silicon interface modified by a silane coupling agent to form a hole transport layer; Preferably, the polymerization reaction is carried out at 80 to 130° C., and after uniform stirring for 30 to 60 minutes, a hole transport layer with a thickness of 200 to 1000 nm is formed. The method according to claim 6, wherein The polymerization step comprises: Under vacuum conditions, oxidants and polymer monomers are evaporated on the crystalline silicon after the alkylation reaction, and polymerized on the silicon interface modified by the silane coupling agent to form a hole transport layer; Preferably, the evaporation is carried out at 80-130° C., and after 1-2 hours of evaporation, a hole transport layer with a thickness of 200-1000 nm is formed. A solar cell, wherein The solar cell comprises a cell absorption layer and a hole transport layer formed by a polymer; Wherein, the battery absorption layer and the hole transport layer are connected by the silane coupling agent described in any one of claims 1 to 4; or, The battery absorption layer and the hole transport layer are connected by the method described in any one of claims 5 to 10. The solar cell according to claim 11, wherein The solar cell comprises the hole transport layer, the alkyl coupling agent layer, the battery absorption layer and the electron transport layer in sequence. The solar cell according to claim 11, wherein At least one side of the battery absorption layer is passivated. An organic-crystalline silicon heterojunction battery, comprising: A silicon substrate, wherein a textured surface is formed on at least one surface of the silicon substrate; An organic and silicon-free hole transport layer, the hole transport layer being located on a surface of the suede and extending to the bottom of the channel of the suede; The electron transport layer is located on the opposite side of the hole transport layer of the silicon substrate. The organic-crystalline silicon heterojunction cell according to claim 14, wherein: The material of the hole transport layer is a polymer; Preferably, the material of the hole transport layer is selected from one or a combination of two or more of PEDOT, P3HT, P3OHT and P3ODDT. The organic-crystalline silicon heterojunction cell according to claim 15, wherein: The hole transport layer extending to the bottom of the channel of the textured surface is formed by polymerization of monomers forming the hole transport layer initiated by an oxidant filled in the channel. The organic-crystalline silicon heterojunction cell according to claim 15, wherein: The silicon substrate and the hole transport layer are connected by a silane coupling agent; The silane coupling agent is YR-SiX ₃ , wherein: Y represents a monomer as a polymer of the hole transport layer, R is an alkylene group, SiX ₃ can hydrolyze and connect to the surface of the silicon substrate. The organic-crystalline silicon heterojunction cell according to claim 14, wherein: The hole transport layer comprises: A first hole transport layer, located at the bottom of the channel of the suede surface; The second hole transport layer is attached to the suede surface and the upper surface of the first hole transport layer. The organic-crystalline silicon heterojunction cell according to claim 18, wherein: The material of the first hole transport layer is selected from one or a combination of two or more of PEDOT, P3HT, P3OHT and P3ODDT; The material of the second hole transport layer is selected from one or a combination of two or more of PEDOT:PSS and PEDOT:F. The organic-crystalline silicon heterojunction cell according to any one of claims 14 to 19, wherein: The conductivity σ of the hole transport layer is greater than 10 S/cm, the thickness of the hole transport layer is 400-1100 nm, and the transmittance T of the hole transport layer is greater than 90%. A method for forming a hole transport layer on a silicon substrate, comprising: A coating step, coating oxidant particles on at least one of the velvet surfaces of the crystalline silicon, wherein the particle size D50 of the oxidant particles is ≤100 nm; The polymerization step is to add a monomer for forming a hole transport layer onto the suede surface coated with the oxidant particles and perform a polymerization reaction to form the hole transport layer. The method of claim 21, wherein: The coating step includes blade coating and physical vapor deposition; Preferably, the oxidant particles are coated using physical vapor deposition; More preferably, the coating thickness of the oxidant is 5 to 20 nm. The method of claim 21, wherein: The particle size D50 of the oxidant particles is ≤40 nm. The method of claim 21, wherein: The polymerization step comprises: forming a monomer of a hole transport layer on the velvet surface coated with oxidant particles by chemical vapor deposition and performing a polymerization reaction; Preferably, in the chemical vapor deposition polymerization, the reactor contains a polar Lewis acid and an organic solution of 0.2-2M monomers of the hole transport layer polymer, and the chemical vapor deposition polymerization is reacted at a temperature of 110° C. to 150° C. for 1-2 hours. The method of claim 21, wherein: The monomers of the hole transport layer polymer are selected from one or more of EDOT, 3HT, 3OHT and 3ODDT. The method of claim 21, wherein: Before the coating step, the method further comprises: A silane coupling agent modification step, wherein the silane coupling agent modification step comprises: A pretreatment sub-step, pretreatment to make the surface of the silicon substrate have hydroxyl groups; an alkylation reaction sub-step, using a silane coupling agent to undergo a substitution reaction with the pretreated silicon substrate to obtain a silicon interface modified by the silane coupling agent; The silane coupling agent is YR-SiX ₃ , wherein: Y represents a monomer forming the polymer of the hole transport layer, R is an alkylene group, SiX ₃ can hydrolyze and connect to the surface of the silicon substrate. The method according to any one of claims 21 to 26, wherein: After chemical vapor deposition polymerization, impurities in the hole transport layer are also washed away; Preferably, 6-12M hydrochloric acid is used to remove impurities in the hole transport layer. The method of claim 27, wherein: After the impurities in the hole transport layer are washed away, the hole transport layer is doped with an acidic solution or vapor. A method for forming a hole transport layer on a silicon substrate, comprising: A filling step, disposing particles of a material of a first hole transport layer at the bottom of a trench of at least one velvet surface of the silicon substrate, wherein the particle size D50 of the material of the first hole transport layer is ≤100 nm; The forming step is to form a second hole transport layer on the suede surface on which the nano-sized particles of the first hole transport layer material are arranged. The method of claim 29, wherein: The filling step includes doctor blade coating and physical vapor deposition; Preferably, nano-sized particles of the material of the first hole transport layer are filled by physical vapor deposition; Further preferably, the filling thickness of the nano-scale particles of the material of the first hole transport layer is 5 to 20 nm. The method of claim 29, wherein: The particle size D50 of the material of the first hole transport layer is ≤40 nm. The method of claim 29, wherein: The material of the first hole transport layer is selected from one or a combination of two or more of PEDOT, P3HT, P3OHT and P3ODDT; The material of the second hole transport layer is selected from one or a combination of two or more of PEDOT:PSS and PEDOT:F. The method of claim 29, wherein: The forming step is to form the second hole transport layer by spin coating.