Modified glass powder, method of preparation and use thereof

Abstract

The application provides a modified glass powder, a preparation method and application thereof. The modified glass powder comprises glass oxide and Ni x Re 1‑x MnO3 composite powder, wherein Re is selected from one or more of rare earth elements. The application uses the Ni x Re 1‑x MnO3 composite powder to improve the conductivity and stability of the glass powder. The modified glass powder provided by the application is applied to a solar cell conductive silver paste, which can reduce the contact resistance between the conductive silver paste and a silicon substrate, and improve the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] This invention relates to the field of photovoltaics, and in particular to a modified glass powder, its preparation method, and its application. Background Technology

[0002] Solar energy is an inexhaustible and renewable energy source for humankind. Among solar energy utilization projects, solar cells have been one of the fastest-growing, most dynamic, and attractive projects in recent years. Currently, the solar cell industry is developing rapidly, and the industry is already showing signs of oversaturation. Reducing the cost of solar cells and improving their efficiency have become current research topics.

[0003] Conductive silver paste for solar cells can be used to form silver grid lines on the surface of the silicon substrate of solar cells. Its components include conductive powder, glass powder, organic carrier, and additives. After the glass powder melts at high temperature, it can bind the silver powder, so that the conductive silver paste and the silicon substrate can form a good bond. In addition, it can also etch the anti-reflection layer on the silicon substrate to achieve good contact between the silver powder and the silicon substrate.

[0004] However, existing glass powders are generally non-conductive. During high-temperature sintering, some of the glass powder melts and deposits on the surface of the silicon substrate, forming a glass layer. This creates a partially insulating region between the grid lines and the silicon substrate, hindering the electrical connection between the silver paste and the silicon substrate. This increases the contact resistance between the silver paste and the silicon substrate, leading to a decrease in the photoelectric conversion efficiency of the solar cell. Therefore, the conductivity of this glass layer has a significant impact on the photoelectric conversion efficiency. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to solve the technical problems of high contact resistance between existing solar cells and silver grid lines, resulting in low photoelectric conversion efficiency. It provides a modified glass powder, its preparation method, and its application to further reduce the contact resistance between the solar cell and the silver grid lines, thereby improving the photoelectric conversion efficiency of the solar cell.

[0006] The technical solution of the present invention:

[0007] A modified glass powder comprising glass oxide and Ni x Re 1-x MnO3 composite powder; wherein Re is selected from one or more rare earth elements.

[0008] In some implementations, x is any number from 0.7 to 0.9.

[0009] In some embodiments, the Ni is calculated with the total mass of the modified glass powder as 100%. x Re 1-x The content of MnO3 composite powder is 1-5 wt%;

[0010] In some embodiments, preferably, the Ni x Re 1-x The content of MnO3 composite powder is 3-5 wt%, which gives the modified glass powder better electrical conductivity.

[0011] In some embodiments, Re is selected from one or more of lanthanum (La), cerium (Ce), and samarium (Sm). Rare earth doping can effectively reduce the resistivity of composite powders and glass oxides. In particular, when the rare earth element is La, the resulting glass powder has the highest conductivity, and the fabricated solar cell has a lower back field resistance and higher photoelectric conversion efficiency.

[0012] In some embodiments, the Ni x Re 1-x The preparation methods of MnO3 composite powder include:

[0013] Mix nickel nitrate, manganese nitrate, rare earth raw materials and water evenly, adjust the pH to acidic, add ethylene glycol dropwise, heat in a water bath while stirring until viscous, and let stand to form a gel.

[0014] The gel is dried, and the resulting dry gel is placed in a muffle furnace for heat treatment to form combustion products;

[0015] The combustion products were ground, then subjected to high-temperature heat treatment, and finally cooled to room temperature to obtain the Ni. x Re 1-x MnO3 composite powder.

[0016] In some embodiments, the rare earth raw material is at least one of nitrates, chlorides, and acetates containing rare earth elements.

[0017] In some embodiments, the water bath heating temperature is 70–85°C.

[0018] In some embodiments, the heat treatment temperature is 180–220°C, and the resulting combustion product is a fluffy powder.

[0019] In some embodiments, the high-temperature heat treatment includes first holding the ground combustion product at 600-700°C for 4-6 hours, and then calcining it at 1100-1300°C for 5-7 hours.

[0020] In some embodiments, the glass oxide can be a glass oxide of various commonly used glass powder systems, such as oxides of zinc, silicon, boron, lead, bismuth, copper, cobalt, nickel, chromium, etc. Further, the glass oxide is one or more combinations of oxides of zinc, silicon, boron, and lead. Even further, the glass oxide is a ZnO-B₂O₃-SiO₂ glass oxide or a PbO-SiO₂-B₂O₃ glass oxide; preferably, the glass oxide is a ZnO-B₂O₃-SiO₂ glass oxide.

[0021] The present invention also provides a method for preparing the modified glass powder, comprising: Ni x Re 1-x MnO3 composite powder and glass oxide are mixed evenly in a certain proportion, heated and melted, and then water-quenched and filtered to obtain glass beads. The glass beads are then ball-milled to obtain modified glass powder.

[0022] The present invention also provides a conductive silver paste for solar cells, wherein, based on the total mass of the conductive silver paste for solar cells being 100%, the conductive silver paste for solar cells contains 85-95 wt% silver powder, 1-10 wt% organic carrier and 1-10 wt% modified glass powder; wherein the modified glass powder is the modified glass powder provided above.

[0023] In some embodiments, the silver powder is flake silver powder or nano silver powder; the flake silver powder has a purity greater than 99.90% and an average particle size of 1-10 μm, preferably 2-5 μm; the nano silver powder has a purity greater than 99.80% and an average particle size of 10-500 nm, preferably 30-300 nm, more preferably 30-100 nm.

[0024] In some embodiments, the organic carrier is an organic system commonly used in existing conductive silver pastes, including but not limited to one or more of thickeners, binders, and organic solvents.

[0025] Beneficial effects:

[0026] This invention utilizes glass oxide combined with Ni x Re 1-x MnO3 composite powder was used to prepare modified glass powder to improve various properties of the glass powder. Ni x Re 1-xMnO3 composite powder can exist in the glass layer between the silver paste and the silicon substrate, improving the conductivity of the glass layer and increasing the conductive pathway between the silver paste and the silicon substrate. Furthermore, the addition of Ni can increase the dispersion stability of the modified glass powder. Adding Ni and rare earth composite powder to the glass powder can simultaneously increase the conductivity and stability of the modified glass powder, with better results than pure Ni or pure rare earth elements. Applying the modified glass powder provided by this invention to conductive silver paste for solar cells can reduce the contact resistance between the sintered conductive silver paste and the silicon substrate, while simultaneously improving the photoelectric conversion efficiency of the solar cell. Detailed Implementation

[0027] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0028] Unless otherwise specified, all chemical reagents used in this invention are commercially available analytical grade reagents.

[0029] Preparation of Ni 0.9 La 0.1 MnO3 composite powder

[0030] Weigh 1 mol manganese nitrate, 0.9 mol nickel nitrate and 0.1 mol lanthanum nitrate into a beaker, add 50 mL of deionized water to dissolve, stir evenly in a water bath at 50 °C, add citric acid to adjust the pH to 5, and add ethylene glycol dropwise until a transparent solution is formed. Heat the water bath to 85 °C and stir until a viscous solution is formed. Let stand until a gel is formed.

[0031] The gel was dried in a drying oven to obtain a dry gel. The dry gel was then placed in a muffle furnace and heated at 210°C, resulting in self-propagating combustion of the dry gel to obtain combustion products. The combustion products were ground in a mortar, and the ground combustion product powder was first kept at 700°C for 5 hours, then calcined at 1200°C for 6 hours, and allowed to cool naturally to room temperature to obtain Ni. 0.9 La 0.1 MnO3.

[0032] Preparation of Ni 0.8 La 0.2 MnO3 composite powder

[0033] Ni 0.8 La 0.7 The preparation method of MnO3 is the same as that of Ni. 0.9 La 0.1 The only difference between MnO3 and Ni is that the molar amounts of nickel nitrate and lanthanum nitrate added are 0.8 mol and 0.2 mol, respectively, to obtain Ni. 0.8La 0.7 MnO3.

[0034] Preparation of Ni 0.7 La 0.3 MnO3 composite powder

[0035] Ni 0.7 La 0.3 The preparation method of MnO3 is the same as that of Ni. 0.9 La 0.1 The only difference between MnO3 and Ni is that the molar amounts of nickel nitrate and lanthanum nitrate added are 0.7 mol and 0.3 mol, respectively, resulting in Ni. 0.7 La 0.3 MnO3.

[0036] Preparation of Ni 0.9 Ce 0.1 MnO3 composite powder

[0037] Ni 0.9 Ce 0.1 The preparation method of MnO3 is the same as that of Ni. 0.9 La 0.1 The only difference with MnO3 is that cerium nitrate is used instead of lanthanum nitrate, and the amount added is 0.1 mol, resulting in Ni. 0.9 Ce 0.1 MnO3.

[0038] Preparation of Ni 0.9 Sm 0.1 MnO3 composite powder

[0039] Ni 0.9 Sm 0.1 The preparation method of MnO3 is the same as that of Ni. 0.9 La 0.1 The only difference with MnO3 is that samarium nitrate is used instead of lanthanum nitrate to obtain Ni. 0.9 Sm 0.1 MnO3.

[0040] Preparation of Ni 0.6 La 0.4 MnO3 composite powder

[0041] Ni 0.6 La 0.4 The preparation method of MnO3 is the same as that of Ni. 0.9 La 0.1 The only difference between MnO3 and Ni is that the molar amounts of nickel nitrate and lanthanum nitrate added are 0.6 mol and 0.4 mol, respectively, resulting in Ni. 0.6 La 0.4 MnO3.

[0042] Preparation of Ca 0.9La 0.1 MnO3 composite powder

[0043] Ca 0.9 La 0.1 The preparation method of MnO3 is the same as that of Ni. 0.9 La 0.1 The only difference with MnO3 is that calcium nitrate is used instead of nickel nitrate to obtain Ca. 0.9 La 0.1 MnO3.

[0044] Preparation of NiMnO3 composite powder

[0045] The preparation method of NiMnO3 is as follows: 0.9 La 0.1 The only difference is that the molar amounts of nickel nitrate and lanthanum nitrate added are 1 mol and 0 mol, respectively, to obtain NiMnO3.

[0046] Preparation of LaMnO3 composite powder

[0047] The preparation method of LaMnO3 is the same as that of LaMnO3, except that the molar amounts of nickel nitrate and lanthanum nitrate added are 0 mol and 1 mol, respectively, to obtain LaMnO3.

[0048] Examples 1-5 and Comparative Examples 1-5

[0049] By mass percentage, 64wt% ZnO, 15wt% B2O3, 16wt% SiO2 and 5wt% of the composite powder prepared above were mixed evenly in proportion, placed in a crucible and melted at 1000℃ for 40 min, then cold rolled, and then ball-milled for 5 h, and dried to obtain modified glass powder.

[0050] 90 parts by weight of silver powder (purity 99.9%, average particle size 10 μm), 3 parts by weight of the above-mentioned modified glass powder and 7 parts by weight of organic carrier (ethylene glycol ethyl ether) were mixed evenly and ground in a three-roll mill until the fineness of the final product was less than 10 μm, to obtain the conductive silver paste of Examples 1 to 5 and Comparative Examples 1 to 5.

[0051] The types of composite powders used in each embodiment and comparative example are detailed in Table 1.

[0052] Table 1. Types of composite powders added in the examples and comparative examples.

[0053]

[0054]

[0055] The conductive silver paste for solar cells prepared above was applied to the fine grid on the front side of an N-type solar cell using the following process to obtain the solar cell. The solar cells were then tested as follows, and the results are shown in Table 2:

[0056] Performance testing

[0057] 1. Photovoltaic conversion efficiency: Tested using a dedicated instrument for testing the photovoltaic conversion efficiency of solar cells.

[0058] 2. Contact resistance: Using a contact resistance tester, linear fitting was performed using the TLM method to inversely calculate the sheet resistance and obtain the ohmic contact resistance. The results were recorded in Table 2.

[0059] Table 2 Test Result Data Table

[0060] Contact resistance (Ω) Photoelectric conversion efficiency (%) Example 1 0.40 24.82 Example 2 0.42 24.80 Example 3 0.43 24.81 Example 4 0.56 24.79 Example 5 0.62 24.78 Comparative Example 1 0.92 24.70 Comparative Example 2 2.64 24.45 Comparative Example 3 2.75 24.42 Comparative Example 4 2.69 24.44 Comparative Example 5 2.89 24.40

[0061] As can be seen from the results of Examples 2-5 in Table 2, using Ni... x Re 1-x MnO3 composite powder modified glass powder can significantly reduce the contact resistance between conductive silver paste and silicon substrate, thereby improving photoelectric conversion efficiency. Furthermore, the improvement effect is optimal when Re is La.

[0062] A comparison of Examples 1-3 with Comparative Example 1 shows that when x = 0.7-0.9, it is beneficial to further reduce contact resistance and improve photoelectric conversion efficiency.

[0063] This invention can also be implemented in various other ways. Without departing from the spirit and essence of this invention, those skilled in the art can make various corresponding changes and modifications according to this invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A modified glass powder, characterized in that, include: Glass oxides and Ni x Re 1-x MnO3 composite powder; wherein Re is selected from one or more of lanthanum, cerium, and samarium; and x is any number from 0.7 to 0.

9. The Ni x Re 1-x The preparation methods of MnO3 composite powder include: Mix nickel nitrate, manganese nitrate, rare earth raw materials and water evenly, adjust the pH to acidic, add ethylene glycol dropwise, heat in a water bath while stirring until viscous, and let stand to form a gel. The gel is dried, and the resulting dry gel is placed in a muffle furnace for heat treatment to form combustion products; The combustion products were ground, then subjected to high-temperature heat treatment, and finally cooled to room temperature to obtain the Ni. x Re 1-x MnO3 composite powder.

2. The modified glass powder according to claim 1, characterized in that, Based on the total mass of the modified glass powder being 100%, the Ni x Re 1-x The content of MnO3 composite powder is 1-5 wt%.

3. The modified glass powder according to claim 1, characterized in that, The rare earth raw material is at least one of nitrates, chlorides, and acetates containing rare earth elements.

4. The modified glass powder according to claim 1, characterized in that, The water bath heating temperature is 70-85℃; the heat treatment temperature is 180-220℃; the high-temperature heat treatment includes first keeping the ground combustion product at 600-700℃ for 4-6 hours, and then calcining it at 1100-1300℃ for 5-7 hours.

5. The modified glass powder according to claim 1, characterized in that, The glass oxide is one or more combinations of zinc oxide, silicon oxide, boron oxide, and lead oxide.

6. The method for preparing the modified glass powder according to any one of claims 1 to 5, characterized in that, Including Ni x Re 1-x MnO3 composite powder and glass oxide are mixed evenly in a certain proportion, heated and melted, and then water-quenched and filtered to obtain glass beads. The glass beads are then ball-milled to obtain modified glass powder.

7. A conductive silver paste for solar cells, comprising, based on 100% of its total mass, 85-95 wt% silver powder, 1-10 wt% organic carrier, and 1-10 wt% modified glass powder; wherein, The modified glass powder is the modified glass powder described in any one of claims 1 to 5.

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