PEDOT: PSS / n-Si solar cell with MoOx multifunctional interface layer and preparation method thereof

Abstract

The invention discloses a PEDOT: PSS / n-Si solar cell with a MoOx multifunctional interface layer and a preparation method of the PEDOT: PSS / n-Si solar cell. Comprising the following steps: (1) preparing a photovoltaic device by adopting a monocrystalline silicon wafer; (2) adding DMSO and a surfactant Triton X-100 into the PEDOT: PSS aqueous solution, and carrying out magnetic stirring to prepare a precursor solution; (3) removing surface oxides from the n-type silicon wafer by using an HF solution; then, deionized water is used for cleaning the HF acid solution left on the silicon wafer, and finally nitrogen is used for purging and drying the silicon wafer; (4) spin-coating the PEDOT: PSS precursor solution prepared in the step (2) on the surface of the silicon wafer, and then annealing to form a film; (5) depositing a layer of MoOx film on the PEDOT: PSS film obtained in the step (4) by adopting a thermal evaporation method; (6) preparing an Ag grid line electrode on the PEDOT: PSS / MoOx thin film; and (7) depositing a layer of metal electrode on the back surface of the sample obtained in the step (6). According to the invention, Ag is in contact with MoOx to form an Ag / MoOx electrode, so that the contact potential barrier between PEDOT: PSS / Ag is reduced. The solar cell manufacturing method is simple and easy to implement, and can be used for large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of solar cells, and particularly to a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer and a preparation method thereof. Background Art

[0002] PEDOT:PSS / n-Si heterojunction solar cells have continuously received extensive attention from researchers due to advantages such as simple preparation and low cost. For a long time, in order to improve the photoelectric conversion efficiency of PEDOT:PSS / Si solar cells, researchers have focused on how to modify the PEDOT:PSS solution, solving problems such as poor wettability, poor conductivity, and unsatisfactory work function of PEDOT:PSS, resulting in a relatively high improvement in the cell efficiency. Currently, the relatively high contact barrier between PEDOT:PSS and the Ag electrode has led to the difficulty in further improving the photovoltaic performance of solar cells, which has become an urgent problem to be solved. In this regard, Zhu et al. introduced a high-work-function WO3 thin film between PEDOT:PSS and the Ag electrode to form a selective emitter structure, reducing the PEDOT:PSS / Ag interface contact barrier, and successfully fabricating a PEDOT:PSS / n-Si solar cell with a photoelectric conversion efficiency of 11.65%. However, WO3 has a relatively high resistivity, which will lead to an increase in the contact resistance between PEDOT:PSS and Ag, inhibiting the improvement of the fill factor of solar cells. Therefore, it is necessary to find more suitable thin film materials and structures to improve the photoelectric conversion efficiency of solar cells. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem of too high contact resistance and contact barrier at the PEDOT:PSS / Ag interface in current PEDOT:PSS / Si silicon solar cells, and to propose a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer and a preparation method thereof.

[0004] Specifically, the technical solution of the present invention is as follows:

[0005] On the one hand, the present invention provides a preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer, including the following steps

[0006] (1) Using a single-crystalline silicon wafer to prepare a photovoltaic device;

[0007] (2) Adding DMSO and a surfactant to an aqueous PEDOT:PSS solution, and magnetically stirring to obtain a precursor solution;

[0008] (3) Removing the surface oxide of the n-type silicon wafer with an HF solution; then washing the residual HF acid solution on the silicon wafer with deionized water, and finally purging and drying the silicon wafer with nitrogen;

[0009] (4) Spin-coat the PEDOT:PSS precursor solution prepared in (2) on the surface of the silicon wafer, and then anneal to form a film.

[0010] (5) Deposit a MoOx film on the PEDOT:PSS film obtained in step (4) by thermal evaporation.

[0011] (6) Fabricate Ag grid electrodes on the PEDOT:PSS / MoOx film.

[0012] (7) Deposit a metal electrode on the back of the sample obtained in step (6).

[0013] Among them, the step (1) uses a single-crystalline silicon wafer to prepare a photovoltaic device, including the following steps:

[0014] (1.1) Perform double-sided polishing and cleaning on the original silicon wafer.

[0015] (1.2) Deposit an oxide layer on both sides of the polished N-type silicon by thermal oxidation or PECVD. Any one side is defined as the tunneling oxide layer, and the oxide layer on the other side protects the silicon wafer surface.

[0016] (1.3) Prepare a phosphorus-doped amorphous silicon thin film on the tunneling oxide layer by PVD in-situ doping or LPCVD + ion implantation, and then anneal to form an (n+)-poly-Si layer; during the annealing process, the vacuum degree of the annealing furnace is 500 - 950 mbar, the annealing time is 20 - 60 min, and the annealing temperature is 800 - 900 °C.

[0017] (1.4) Deposit a SiNx passivation and antireflection film on the (n+)-poly-Si layer.

[0018] (1.5) Print an n+ metal electrode 11 with silver paste in the n+ doping region and sinter at high temperature.

[0019] Among them, in step (1), the resistivity of the silicon wafer is 1 - 5 Ω·cm, and the thickness is 160 ± 30 μm.

[0020] Among them, in step (2), the concentrations of DMSO and surfactant Triton X-100 are 1 - 10 wt.% and 1 - 0.05 wt.%, respectively, and the optimal values are 5 wt.% and 0.2 wt.%, respectively.

[0021] Among them, in step (3), an HF solution with a ratio of deionized water to HF of 1:8 is used to remove the oxide.

[0022] Among them, in step (4), the spin coating process needs to adopt a two-step method. The first step lasts for 3 - 8 s and the rotation speed is 400 - 600 rpm; the second step lasts for 10 - 50 s and the rotation speed is 1000 - 2500 rpm. Among them, during annealing, the temperature and duration are 90 - 120 °C and 5 - 20 min respectively.

[0023] Among them, in step (5), when using the thermal evaporation method, a MoOx thin film with a thickness of 1 - 5 nm is deposited, and the evaporation rate is 0.1 - 0.3 nm / s.

[0024] Among them, in step (6), the thickness of the Ag electrode deposited on the PEDOT:PSS / MoOx thin film is 80 - 200 nm. Among them, during thermal evaporation, the process is divided into two steps. In the first step, 5 - 10 nm is deposited at an evaporation rate of 0.1 - 0.2 nm / s, and in the second step, 80 - 90 nm is deposited at an evaporation rate of 0.3 - 0.6 nm / s.

[0025] Among them, in step (7), the metal electrode includes but is not limited to metal materials such as Al, Ag, Au, etc. and their combinations, and the preparation method includes but is not limited to magnetron sputtering, evaporation deposition, etc.

[0026] On the other hand, the present invention provides a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer. A PEDOT:PSS thin film is provided at the bottom of the silicon wafer, and a MoOx thin film is deposited on the PEDOT:PSS thin film to form a PEDOT:PSS / MoOx thin film; a whole-surface silver electrode is deposited on the surface of the PEDOT:PSS / MoOx thin film.

[0027] The silicon wafer uses an n-type silicon wafer (resistivity 1 - 5 Ω·cm, thickness 160 ± 30 μm) with a TOPCon structure (SiO2 and (n+)-poly-Si layer), a SiNx passivation and antireflection thin film, and metal grid lines on one side for the preparation of photovoltaic devices.

[0028] Technical effects and advantages of the present invention:

[0029] (1) Ag contacts with MoOx to form an Ag / MoOx electrode, reducing the contact barrier between PEDOT:PSS / Ag;

[0030] (2) PEDOT:PSS and MoOx can undergo a redox reaction, and the film contact can promote the improvement of each other's conductivity, reducing the contact resistance between PEDOT:PSS / Ag;

[0031] (3) MoOx can increase the work function of PEDOT:PSS and increase the built-in electric field;

[0032] (4) A work function gradient is formed at the PEDOT:PSS / MoOx interface, which helps to extract hole carriers;

[0033] (5) Significantly improve the conversion efficiency of PEDOT:PSS / Si solar cells by using a simple scheme;

[0034] (6) The manufacturing method of this solar cell is simple and easy to implement, and can be used for large-scale production. Description of the Drawings

[0035] Figures 1 to 4 It is a preparation flow chart of the solar cell.

[0036] Figure 5 It is a schematic diagram of the structure of the solar cell of the present invention.

[0037] Figure 6 They are: (a) PEDOT:PSS (b) MoOx and (c-f) SEM images of PEDOT:PSS / MoOx thin films with different MoOx thicknesses;

[0038] In the figure: 1 is the n-Si layer; 2 is SiNx; 3 is the (n+)-poly-Si layer; 4 is SiO2; 5 is the PEDOT:PSS thin film; 6 is the MoOx thin film; 7, 8 are silver electrodes. Detailed Embodiments

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Embodiment 1

[0041] As a non-stoichiometric material, MoOx can improve the conductivity of MoOx by increasing the Mo / O ratio. The acidic PEDOT:PSS can just be used as a reducing agent for MoOx. Inserting the MoOx thin film as an interface layer between Ag and PEDOT:PSS can not only have the effect of reducing the contact barrier between PEDOT:PSS / Ag similar to WO3, but also the interaction between PEDOT:PSS and MoOx can enhance each other's conductivity, reduce the contact resistance, and improve the carrier collection of the PEDOT:PSS / n-Si solar cell in the lateral and vertical directions. The PEDOT:PSS / MoOx composite thin film with a suitable MoOx thickness has a lower sheet resistance than the PEDOT:PSS thin film, which significantly improves the open-circuit voltage and fill factor of the solar cell.

[0042] A preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer, comprising:

[0043] (1) Using an n-type silicon wafer with a TOPCon structure (SiO2 and (n+)-poly-Si layer), a SiNx passivation and antireflection thin film, and metal grid lines on one side (resistivity 1-5 Ω·cm, thickness 160±30 μm) to prepare a photovoltaic device;

[0044] (2) Preparing an HF solution with HF:deionized water = 1:8, immersing the n-type monocrystalline silicon wafer in the prepared HF solution to remove the oxide on the blank side of the wafer, then rinsing it thoroughly with deionized water, and finally purging and drying the wafer with nitrogen, as Figure 1 .

[0045] (3) Adding DMSO and surfactant Triton X-100 to a PEDOT:PSS aqueous solution (Haraeus PH1000) with concentrations of 5 wt.% and 0.2 wt.% respectively, and obtaining a PEDOT:PSS precursor solution after stirring for 3 h; spin-coating the prepared PEDOT:PSS solution on the surface of the silicon wafer into a film, and the spin-coating adopts a two-step method. The first step lasts for 6 s and the rotation speed is 550 rpm; the second step lasts for 30 s and the rotation speed is 1500 rpm. Then anneal it in an atmospheric environment, and the annealing temperature and duration are 100 °C and 10 min respectively, as Figure 2 ;

[0046] (4) Evaporating a 2-nm MoOx thin film on the PEDOT:PSS thin film obtained in step (3) by thermal evaporation, and the evaporation rate is 0.1 nm / s, as Figure 3 ;

[0047] (5) Depositing a 100-nm whole-surface Ag electrode on the PEDOT:PSS / MoOx thin film by an evaporation device, and the evaporation process is divided into two steps. The first step deposits 10 nm at an evaporation rate of 0.2 nm / s, and the second step deposits 90 nm at an evaporation rate of 0.4 nm / s; as Figure 4 .

[0048] Wherein, in step (1), the resistivity of the silicon wafer is 1-5 Ω·cm and the thickness is 160±30 μm.

[0049] Wherein, in step (2), an HF solution with HF:deionized water = 1:8 is required to remove the oxide.

[0050] Among them, in step (3), the concentrations of DMSO and surfactant Triton X-100 are 1-10 wt.% and 1-0.05 wt.%, respectively. The spin coating process needs to adopt a two-step method. The first step lasts for 3-8 s and the rotation speed is 400-600 rpm; the second step lasts for 10-50 s and the rotation speed is 1000-2500 rpm. Among them, during annealing, the temperature and duration are 90-120 °C and 5-20 min, respectively.

[0051] Among them, in step (4), when using the thermal evaporation method, a MoOx thin film with a thickness of 1-5 nm is deposited, and the evaporation rate is 0.1-0.3 nm / s.

[0052] Among them, in step (5), the thickness of the Ag electrode deposited on the PEDOT:PSS / MoOx thin film is 80-200 nm. Among them, during thermal evaporation, the process is divided into two steps. In the first step, 5-10 nm is deposited at an evaporation rate of 0.1-0.2 nm / s, and in the second step, 80-90 nm is deposited at an evaporation rate of 0.3-0.6 nm / s. The metal electrode includes but is not limited to metal materials such as Al, Ag, Au, etc. and their combinations. The preparation method includes but is not limited to magnetron sputtering, evaporation deposition, etc.

[0053] Example Two

[0054] As Figure 5 shown, on the other hand, the present invention provides a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer. A PEDOT:PSS thin film is deposited on the bottom of the silicon wafer, and a MoOx thin film is evaporated on the PEDOT:PSS thin film to form a PEDOT:PSS / MoOx thin film; a whole-surface silver electrode is deposited on the surface of the PEDOT:PSS / MoOx thin film.

[0055] The silicon wafer uses an n-type silicon wafer (resistivity 1-5 Ω·cm, thickness 160 ± 30 μm) with a TOPCon structure (SiO2 and (n+)-poly-Si layer), SiNx passivation antireflection thin film and metal grid lines on one side for the preparation of photovoltaic devices.

[0056] Example Three

[0057] Using a single-crystalline silicon wafer to prepare a photovoltaic device, including the following steps:

[0058] (1.1) Double-side polish the original silicon wafer;

[0059] (1.2) Deposit an oxide layer on both sides of the polished N-type silicon by using the method of thermal oxidation or PECVD. One side is defined as the tunneling oxide layer, and the oxide layer on the other side plays a protective role on the silicon wafer surface;

[0060] (1.3) The preparation of the phosphorus-doped amorphous silicon thin film is carried out by in-situ doping with PVD or the method of LPCVD + ion implantation on the tunneling oxide layer, and then annealing is performed to form an (n+)-poly-Si layer; during the annealing process, the vacuum degree of the annealing furnace is 500 - 950 mbar, the annealing time is 20 - 60 min, and the annealing temperature is 800 - 900 °C;

[0061] (1.4) Deposit a SiNx passivation and antireflection film on the (n+)-poly-Si layer;

[0062] (1.5) Print the n+ metal electrode 11 with silver paste in the n+ doping region and sinter it at high temperature.

[0063] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer, characterized in that: It includes the following steps: (1) Prepare a photovoltaic device using a single-crystalline silicon wafer. (2) Add DMSO and surfactant Triton X-100 to an aqueous PEDOT:PSS solution, and prepare a precursor solution after magnetic stirring. (3) Remove the surface oxide of the n-type silicon wafer with an HF solution; then wash the residual HF acid solution on the silicon wafer with deionized water, and finally purge and dry the silicon wafer with nitrogen. (4) Spin-coat the PEDOT:PSS precursor solution prepared in (2) on the surface of the silicon wafer, and then anneal to form a film. (5) Deposit a layer of MoOx film on the PEDOT:PSS film obtained in step (4) by thermal evaporation. (6) Prepare an Ag grid electrode on the PEDOT:PSS / MoOx film. (7) Deposit a layer of metal electrode on the back of the sample obtained in step (6).

2. The preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer according to claim 1, characterized in that: The step (1) of preparing a photovoltaic device using a single-crystalline silicon wafer includes the following steps: (1.1) Perform double-sided polishing and cleaning on the original silicon wafer. (1.2) Deposit an oxide layer on both sides of the polished N-type silicon by thermal oxidation or PECVD, where one side is defined as the tunneling oxide layer and the other oxide layer serves as a protection layer. (1.3) Prepare a phosphorus-doped amorphous silicon thin film on the tunneling oxide layer by PVD in-situ doping or LPCVD + ion implantation, and then anneal to form an (n+)-poly-Si layer; during the annealing process, the vacuum degree of the annealing furnace is 500 - 950 mbar, the annealing time is 20 - 60 min, and the annealing temperature is 800 - 900 °C. (1.4) Deposit a SiNx passivation and antireflection film on the (n+)-poly-Si layer. (1.5) Print the n+ metal electrode 11 with silver paste in the n+ doping region and sinter it at a high temperature.

3. The preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer according to claim 1, characterized in that: In step (1), the resistivity of the silicon wafer is 1 - 5 Ω·cm, and the thickness is 160 ± 30 μm.

4. The preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer according to claim 1, wherein: In step (2), the concentrations of DMSO and surfactant Triton X-100 are 1 - 10 wt.% and 1 - 0.05 wt.% respectively, and the optimal values are 5 wt.% and 0.2 wt.% respectively.

5. The preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer according to claim 1, wherein: In step (3), an HF solution with a ratio of deionized water to HF of 1:8 is used to remove the oxide.

6. The preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer according to claim 1, characterized in that: In step (4), the spin-coating process needs to adopt a two-step method. The first step lasts for 3 - 8 s and the rotation speed is 400 - 600 rpm; the second step lasts for 10 - 50 s and the rotation speed is 1000 - 2500 rpm; among them, during annealing, the temperature and time are 90 - 120 °C and 5 - 20 min respectively.

7. The preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer according to claim 1, characterized in that: In step (5), when using thermal evaporation, deposit a MoOx film with a thickness of 1 - 5 nm, and the evaporation rate is 0.1 - 0.3 nm / s.

8. The preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer according to claim 1, characterized in that: In step (6), the thickness of the Ag electrode deposited on the PEDOT:PSS / MoOx film is 80 - 200 nm; among them, during thermal evaporation, the process is divided into two steps. The first step deposits 5 - 10 nm at an evaporation rate of 0.1 - 0.2 nm / s, and the second step deposits 80 - 90 nm at an evaporation rate of 0.3 - 0.6 nm / s.

9. The preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer according to claim 1, characterized in that: In step (7), the metal electrode includes, but is not limited to, metal materials such as Al, Ag, Au, etc. and combinations thereof, and the preparation method includes, but is not limited to, magnetron sputtering, evaporation deposition, etc.

10. The preparation method of a PEDOT:PSS / n-Si solar cell with a MoOx multifunctional interface layer according to any one of claims 1-9, characterized in that, The structure of the solar cell is as follows: a PEDOT:PSS thin film is deposited on the bottom of the silicon wafer, and a MoOx thin film is evaporated on the PEDOT:PSS thin film to form a PEDOT:PSS / MoOx thin film; a full-surface silver electrode is deposited on the surface of the PEDOT:PSS / MoOx thin film.

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