CN112582095A - Conductive paste and solar cell containing same - Google Patents

Abstract

Translated fromChinese

本发明提供了一种导电浆料及含有其的太阳能电池。该导电浆料包括各自独立包装的微米浆和纳米浆，其中，微米浆与纳米浆的质量比为(50‑99)∶(1‑50)；以纳米浆各原料组成的总质量为100％计，纳米浆的原料组成包括(5‑85)％的纳米金属粉，(0‑10)％的纳米添加剂，(15‑95)％的有机相。该导电浆料没有印刷不良的问题。本发明还提供了含有上述导电浆料的太阳能电池，该太阳能电池具有较高的光电转化效率。The present invention provides a conductive paste and a solar cell containing the same. The conductive paste includes micro-paste and nano-paste separately packaged, wherein the mass ratio of micro-paste to nano-paste is (50-99):(1-50); the total mass of each raw material of nano-paste is 100% In total, the raw material composition of the nanopaste includes (5-85)% of nanometer metal powder, (0-10)% of nanometer additive, and (15-95)% of organic phase. This conductive paste has no problem of poor printing. The present invention also provides a solar cell containing the above conductive paste, and the solar cell has high photoelectric conversion efficiency.

Description

Conductive paste and solar cell containing same

Technical Field

The invention relates to a conductive paste for a solar cell, in particular to a nano conductive paste with good dispersibility, belonging to the technical field of solar cells.

Background

The nano material is a material with at least one dimension in the nano level in the three-dimensional space scale, and is a new generation material consisting of nano particles with the sizes between atoms, molecules and a macroscopic system. Due to the fact that the size of a composition unit is small, an interface occupies quite large components, a system formed by nanoparticles has many special properties different from a common bulk macroscopic material system, when the size of particles is reduced to a nanometer level, new characteristics of sound, light, electricity, magnetism and thermal properties are caused, and the system has the characteristics of surface effect, small-size effect, macroscopic quantum tunneling effect and the like, and is widely applied to various fields.

The nano electronic paste also has wider research and application, and the nano material is actively developed and introduced in the electronic paste in the field of solar cells, so that better performance is expected. Such as adding nano metal powder, nano oxide, etc. The solid content (the ratio of the conductive metal powder to the inorganic additive powder) of the front electrode silver paste of the solar cell generally reaches more than 85%, and in order to improve the conversion efficiency, the solid content can reach 90-93% or higher. In the slurry with high solid content, all or part of the added nano metal powder and/or nano inorganic powder is difficult to be uniformly and stably dispersed in an organic phase and is easy to settle and agglomerate, so that the problems of obvious grid breakage or EL grid breakage exist in the screen printing of the solar cell, the qualification rate of the cell is reduced, and the photoelectric conversion efficiency of the cell is influenced.

Therefore, although the prior art has been largely studied and developed to introduce nano-powder, the problem of poor printing due to the dispersibility of nano-powder has been a problem, and thus it has not been possible to develop the nano-powder industrially.

Disclosure of Invention

In order to solve the above problems, an object of the present invention is to provide a conductive paste, in which a nanomaterial is added, so that electrical properties can be improved, and at the same time, a nanomaterial can be ensured to have good dispersibility even at a high solid content, and a problem of poor printing does not occur.

In order to achieve the technical purpose, the invention provides conductive paste which comprises micrometer paste and nanometer paste which are respectively and independently packaged, wherein the mass ratio of the micrometer paste to the nanometer paste is (50-99): (1-50);

the raw material composition of the nano-slurry comprises (5-85)% of nano-metal powder, (0-10)% of nano-additive and (15-95)% of organic phase, wherein the total mass of the raw material compositions of the nano-slurry is 100%.

According to the conductive paste, the nano paste and the conductive paste (the micro paste) are mixed according to a certain proportion, so that the problem of poor printing of the nano material with high solid content is solved.

In one embodiment of the present invention, the mass ratio of the micropulp to the nanoplasmate is (80-99): (1-20).

In one embodiment of the present invention, the particle size D50 of the slurry is 1.0 μm to 2.0. mu.m.

In one embodiment of the present invention, the nano-slurry has a particle size D50 of 50nm to 300 nm.

Further, the particle size D50 of the nano-slurry is 100nm-200 nm.

In one embodiment of the present invention, the raw material composition of the micropulp comprises (85-93)% of the micrometer metal powder, (1-10)% of the micrometer glass powder composition, and (5-25)% of the organic phase, based on 100% of the total mass of the raw material composition of the micropulp.

In a specific embodiment of the present invention, the micron metal powder may be one or a combination of two or more of gold powder, platinum powder, palladium powder, aluminum powder, silver powder, and copper powder.

In one embodiment of the present invention, the D50 of the microglass frit composition used is 0.5 μm to 2.5 μm.

In one embodiment of the present invention, the micropulp can be prepared according to the following steps:

uniformly mixing micron metal powder, micron glass powder composition and organic phase by stirring, rolling and other processes; can be mixed uniformly at the same time or gradually mixed by components, or the micron metal powder and the micron glass powder composition are respectively mixed uniformly with the organic phase and then mixed to obtain semi-solid slurry-micron slurry.

In one embodiment of the present invention, the nanopaste may contain a nano-glass frit composition. Wherein the D50 of the nano glass frit composition may be 50nm to 200 nm.

In one embodiment of the present invention, the nano-additive in the nano-slurry is other inorganic nano-material besides nano-metal powder. The nano additive can improve the sintering performance of the slurry, enhance the bonding performance, improve the welding tension and the like.

In a specific embodiment of the present invention, the nano metal powder may be one or a combination of two or more of gold powder, platinum powder, palladium powder, aluminum powder, silver powder, and copper powder.

In one embodiment of the present invention, the nanopaste can be prepared according to the following steps:

mixing nanometer metal powder, nanometer additive and organic phase when containing nanometer glass powder composition, stirring, rolling, and mixing to obtain semi-solid slurry-nanometer slurry.

Wherein, the nano-slurry can also be liquid nano-slurry which is formed in the preparation process of the nano-metal powder and is not separated and dried.

In one embodiment of the present invention, the particle size of the micron metal powder D50: 1.0-2.0 μm.

In one embodiment of the present invention, the particle size D50 of the nano metal powder is: 50nm-300 nm; further, the particle size D50 of the nano metal powder: 100nm-200 nm.

In the conductive paste of the present invention, the raw material composition of the organic phase in the nanopaste and the organic phase in the micropulp may be the same or different.

In one embodiment of the present invention, the raw material composition of the organic phase in the nanopaste and the organic phase in the micropulp independently comprises: one or the combination of more than two of solvent, resin, thixotropic agent, organic auxiliary agent and auxiliary agent.

In a further embodiment of the invention, the solvent used comprises one or a combination of two or more of butyl carbitol acetate, alcohol ester dodeca, butyl carbitol, terpineol and ethers.

In a further embodiment of the present invention, the resin used comprises one or a combination of two or more of cellulose, acrylic, polyester and epoxy resins.

In a further embodiment of the present invention, the thixotropic agent used comprises one or a combination of two or more of polyamide wax, fumed silica, hydrogenated castor oil.

In a further embodiment of the present invention, the adjuvant used comprises one or a combination of two or more of silicone oil and surfactant.

In a specific embodiment of the invention, the organic phase of the nano-slurry contains 0.1% -20% of the organic auxiliary agent, based on 100% of the total raw material composition of the organic phase of the nano-slurry.

In one embodiment of the present invention, the organic auxiliary agent used is spherical gel particles; preferably soft gel particles.

In one embodiment of the present invention, the spherical gel fine particles are one or a combination of two or more of an acrylic compound, an acrylamide compound, an N-vinylpyrrolidone polymer, and an epoxy resin polymer.

In one embodiment of the present invention, the spherical gel particles have a particle size of 10nm to 200 nm; preferably, the spherical gel fine particles have a particle diameter of 50nm to 100 nm.

In one embodiment of the present invention, the spherical gel particles can be prepared by conventional solution polymerization, emulsion polymerization, microemulsion polymerization, soap-free emulsion polymerization, non-aqueous dispersion polymerization, or precipitation polymerization.

The conductive paste can be used for preparing a solar cell, and when the conductive paste is used for preparing the solar cell, the conductive paste is prepared according to the following steps:

mixing the micrometer slurry and nanometer slurry, stirring at rotation speed of 400-800 rpm and revolution speed of 400-800 rpm for 120-600 s (preferably 120-200 s), and screen printing.

In one embodiment of the invention, the nanopaste is mixed with the micropulp within 5 hours (preferably within 2 hours, most preferably within 30 minutes) before screen printing.

In one embodiment of the present invention, the mixing and stirring of the micropulp and the nanoplasma can be performed by using a centrifugal stirrer, and the stirring tank rotates and revolves simultaneously. For example, a centrifugal mixer RBT-X1500 manufactured by Luobanhan precision machinery (Suzhou) Inc. may be used.

The invention also provides a solar cell, and the conductive paste adopted by the solar cell is the conductive paste.

The conductive paste contains the nano material, and can endow the conductive paste with better electrical properties.

The nano material in the conductive paste disclosed by the invention has better dispersibility (for example, when the solid content is 93%) under the condition of high solid content, and the problem of poor printing caused by agglomeration of the conductive paste due to the nano material can be solved, so that the solar cell has higher photoelectric conversion efficiency.

Drawings

FIG. 1 is a graph of EL after printing and firing of the paste of example 1.

FIG. 2 is a graph of EL after printing and sintering of comparative pastes.

Detailed Description

The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.

Example 1

The embodiment provides a conductive paste, which comprises nano-paste and micro-paste which are respectively and independently packaged, wherein the micro-paste is crystalline silver conventional micron-sized front electrode silver paste;

the preparation method of the nano-slurry comprises the following steps: 5 parts of nano silver powder (D50: 100nm) and 95 parts of organic phase are stirred and mixed uniformly. Wherein the organic phase is prepared by the following steps:

73 parts of butyl carbitol acetate, 1 part of ethyl cellulose, 3 parts of polyamide wax, 3 parts of silicone oil, 20 parts of gel (epoxy resin polymer with the particle size of 50nm), and uniformly mixing and stirring in a water bath at 50-90 ℃.

FIG. 1 shows an EL picture printed and sintered with the paste of example 1, which shows no broken grid and is printed well.

FIG. 2 shows the EL photograph of the slurry of example 1 after adding silver nanoparticles directly and brush-sintering, showing severe grid breakage and poor printing.

Example 2

The embodiment provides a conductive paste, which comprises nano-paste and micro-paste which are respectively and independently packaged, wherein the micro-paste is crystalline silver conventional micron-sized front electrode silver paste;

the preparation method of the nano-slurry comprises the following steps: 20 parts of nano silver powder (D50: 150nm) and 80 parts of acrylic microgel (with the particle size of 25nm) are stirred and mixed uniformly.

Example 3

The embodiment provides a conductive paste, which comprises nano-paste and micro-paste which are respectively and independently packaged, wherein the micro-paste is crystalline silver conventional micron-sized front electrode silver paste;

the preparation method of the nano-slurry comprises the following steps: 50 parts of nano silver powder (D50: 200nm) and 50 parts of organic phase are stirred and mixed uniformly. Wherein the organic phase is prepared by the following steps:

60 parts of butyl carbitol acetate, 15 parts of ethyl cellulose, 5 parts of polyamide wax, 5 parts of an auxiliary agent and 15 parts of gel (acrylamide with the particle size of 80nm) are mixed and stirred uniformly in a water bath at the temperature of 50-90 ℃.

Example 4

The embodiment provides a conductive paste, which comprises nano-paste and micro-paste which are respectively and independently packaged, wherein the micro-paste is crystalline silver conventional micron-sized front electrode silver paste;

nano-slurry: 25 parts of the same organic phase as the micron slurry, 5 parts of macromolecular dispersant and 70 parts of nano silver powder (the particle size D50 is 80 nm).

Example 5

The present embodiment provides a conductive paste comprising a nanopaste and a nanopaste, wherein,

and (3) micro-slurry: 89 parts of micron silver powder, 2 parts of micron glass powder composition and 9 parts of organic phase, stirring and mixing uniformly, and grinding by a three-roller machine.

Nano-slurry: 65 parts of nano silver powder (with the grain diameter D50 of 80nm), 25 parts of microgel (N-vinyl pyrrolidone polymer with the grain diameter of 120 nm), 5 parts of dispersing agent, 3 parts of nano glass powder composition and 2 parts of nano additive (nano zinc oxide), and the nano powder is uniformly dispersed by mixing, stirring and three-roll grinding.

Example 6

The present embodiment provides a solar cell, which is prepared according to the following steps:

the semiconductor substrate is selected from a boron-doped P-type silicon substrate or a phosphorus-doped N-type silicon substrate, wherein the silicon substrate is a silicon wafer with the thickness of 180-250 mu m and the thickness of 125-125 mm or 156-156 mm or other typical dimensions;

firstly, corroding one side of a silicon substrate by using corrosive solution to prepare a pyramid (single crystal) or rugged (polycrystalline) antireflection suede, or preparing a black silicon nanometer suede by using a wet method or a dry method black silicon technology;

forming an N (P) type diffusion layer on the other side of the P (N) type silicon substrate to prepare a PN junction, wherein the N type diffusion layer can be prepared by a gas phase thermal diffusion method using gaseous phosphorus oxychloride as a diffusion source, a phosphorus ion injection method, a slurry coating thermal diffusion method containing phosphorus pentoxide and the like;

thirdly, depositing a SiNx antireflection layer on one side of the suede surface of the silicon substrate, or adding an aluminum oxide passivation layer, or other similar coatings with good antireflection effects; a passivation layer can also be formed on the back surface of the cell by using SiNx and alumina or silicon oxide as a back reflector to increase the absorption of long wave light.

Fourthly, printing or coating an Al electrode layer and a main grid silver electrode layer on one side of the P or N type silicon substrate,

fifthly, uniformly mixing (80-99) parts of the micron paste and (1-20) parts of the nano paste of the examples 1-5 within 2 hours of the battery screen printing process; in the mixing, the mixture was stirred at a rotation speed of 500 rpm and a revolution speed of 500 rpm for 120 seconds, and then screen-printed. For example, the mixing mass ratio of the micropulp to the nanoplasmate may be 95:5, 90:10, 85:15, 80:20, 92:8, 88:12, 82: 18.

And sixthly, forming vertical and horizontal main grids and fine grids on the antireflection film on one side of the light receiving silicon substrate by the conductive paste in the fifth step through screen printing, coating and the like, and co-firing the conductive paste to form an electrode body under a certain sintering temperature program, wherein the sintering peak temperature is 600-950 ℃, so that the solar cell is obtained.

The conductive pastes of examples 1 to 5 and the solar cells prepared therefrom were subjected to a viscosity test and a photoelectric conversion efficiency test.

Viscosity test method: the results of the Brookfield viscometer, SC4-14/6R adapter, measured at a constant temperature of 25. + -. 1 ℃ and 10 rpm are shown in Table 1.

Viscosity 1: the viscosity values of the micro-slurry and the nano-slurry were measured within 12 hours after the completion of the slurry preparation.

Viscosity before printing 2: the viscosity of the slurry was tested 2h before the cell printing procedure was performed.

Adding nano-rice powder directly: the conductive silver paste is prepared by directly mixing nano powder and micron paste according to the same proportion (6.5:90) in the preparation process of the paste.

Testing the photoelectric conversion efficiency of the cell: the method comprises the steps of printing slurry on the front electrodes of single crystal silicon solar cells in the same batch, sintering, and testing by using a solar simulation electric efficiency tester under standard conditions (atmosphere quality AM1.5, illumination intensity 1000W/m)²And the test temperature is 25 ℃. And taking the average value of the small-batch battery pieces after printing.

The results are shown in table 1, taking the conductive paste of example 5 as an example.

TABLE 1

Item	Micron size	Direct-adding nano rice flour	Mixed slurry
				viscosity/Pa.S	200	220	/
viscosity/Pa.S before printing	220	250	200
				Transformation efficiency%	20.15	20.05	20.25

The above examples illustrate that the nanomaterial in the conductive paste of the present invention has good dispersibility even at a high solid content, and can solve the problem of poor printing caused by agglomeration of the conductive paste due to the nanomaterial contained therein, thereby providing a solar cell with high photoelectric conversion efficiency.

Claims (10)

Translated fromChinese

1.一种导电浆料，该导电浆料包括各自独立包装的微米浆和纳米浆，其中，微米浆与纳米浆的质量比为(50-99)：(1-50)；1. A conductive paste, the conductive paste comprising a micro-paste and a nano-paste individually packaged, wherein the mass ratio of the micro-paste to the nano-paste is (50-99):(1-50);以所述纳米浆各原料组成的总质量为100％计，所述纳米浆的原料组成包括(5-85)％的纳米金属粉，(0-10)％的纳米添加剂，(15-95)％的有机相。Based on the total mass of each raw material composition of the nanopaste as 100%, the raw material composition of the nanopaste includes (5-85)% nanometer metal powder, (0-10)% nanometer additive, (15-95) % organic phase.2.根据权利要求1所述的导电浆料，其中，以所述微米浆各原料组成的总质量为100％计，所述微米浆的原料组成包括：(85-93)％的微米金属粉，(1-10)％的微米玻璃粉组合物和(5-25)％的有机相。2 . The conductive paste according to claim 1 , wherein, based on the total mass of each raw material composition of the micron pulp as 100%, the raw material composition of the micron paste comprises: (85-93)% of micron metal powder , (1-10)% of the micron glass powder composition and (5-25)% of the organic phase.3.根据权利要求2所述的导电浆料，其中，所述微米金属粉的粒径D50：1.0μm-2.0μm。3 . The conductive paste according to claim 2 , wherein the particle size D50 of the micron metal powder is 1.0 μm-2.0 μm. 4 .4.根据权利要求1所述的导电浆料，其中，所述纳米金属粉的粒径D50：50nm-300nm；优选为100nm-200nm。4 . The conductive paste according to claim 1 , wherein the particle size D50 of the nano metal powder is 50 nm-300 nm; preferably 100 nm-200 nm. 5 .5.根据权利要求2所述的导电浆料，其中，纳米浆中的有机相和微米浆中的有机相的原料组成各自独立的包括：溶剂、树脂、触变剂、有机助剂和助剂中的一种或两种以上的组合；5. The conductive paste according to claim 2, wherein the raw material composition of the organic phase in the nanopaste and the organic phase in the micropaste independently comprises: solvent, resin, thixotropic agent, organic auxiliary agent and auxiliary agent one or a combination of two or more;优选地，所述溶剂包括丁基卡必醇乙酸酯、醇酯十二、丁基卡必醇、松油醇和醚类中的一种或两种以上的组合；Preferably, the solvent comprises one or a combination of two or more selected from butyl carbitol acetate, alcohol ester dodecyl, butyl carbitol, terpineol and ethers;优选地，所述树脂包括纤维素、丙烯酸树脂、聚酯树脂和环氧树脂中的一种或两种以上的组合；Preferably, the resin comprises one or a combination of two or more of cellulose, acrylic resin, polyester resin and epoxy resin;优选地，所述触变剂包括聚酰胺蜡、气相二氧化硅、氢化蓖麻油中的一种或两种以上的组合；Preferably, the thixotropic agent comprises one or a combination of two or more of polyamide wax, fumed silica and hydrogenated castor oil;优选地，所述助剂包括硅油、表面活性剂中的一种或两种以上的组合。Preferably, the auxiliary agent includes one or a combination of two or more of silicone oil and surfactant.6.根据权利要求1或5所述的导电浆料，其中，以纳米浆的有机相的原料组成总量为100％计，纳米浆的有机相中含有0.1％-20％的有机助剂，所述有机助剂为球状凝胶微粒；6. The conductive paste according to claim 1 or 5, wherein the organic phase of the nanopaste contains 0.1%-20% of organic additives based on 100% of the total raw material composition of the organic phase of the nanopaste, The organic auxiliary agent is spherical gel particles;优选为软质凝胶微粒。Soft gel particles are preferred.7.根据权利要求6所述的导电浆料，其中，所述球状凝胶微粒为丙烯酸类化合物、丙烯酰胺类化合物、N-乙烯基吡咯烷酮聚合物、环氧树脂聚合物中的一种或两种以上的组合。7 . The conductive paste according to claim 6 , wherein the spherical gel particles are one or both of acrylic compounds, acrylamide compounds, N-vinylpyrrolidone polymers, and epoxy resin polymers. 8 . more than one combination.8.根据权利要求6或7所述的导电浆料，其中，所述球状凝胶微粒的粒径为10nm-200nm；8. The conductive paste according to claim 6 or 7, wherein the spherical gel particles have a particle size of 10 nm-200 nm;优选地，所述球状凝胶微粒的粒径为50nm-100nm。Preferably, the particle size of the spherical gel particles is 50nm-100nm.9.权利要求1-8任一项所述的导电浆料的应用，该导电浆料用于制备太阳能电池，其中，用于制备太阳能电池时，按照以下步骤进行：9. The application of the conductive paste of any one of claims 1-8, the conductive paste is used to prepare a solar cell, wherein, when used to prepare a solar cell, the steps are as follows:在进行丝网印刷前，将微米浆与纳米浆混合，在400转每分钟-800转每分钟的自转转速，以及400转每分钟-800转每分钟的公转转速下，搅拌120s-600s，然后进行丝网印刷。Before screen printing, mix the micropaste and nanopaste, stir for 120s-600s at the rotation speed of 400-800 rpm and the revolution speed of 400-800 rpm, and then Screen printing.10.一种太阳能电池，该太阳能电池采用的导电浆料为权利要求1-8任一项所述的导电浆料。10. A solar cell, the conductive paste used in the solar cell is the conductive paste according to any one of claims 1-8.

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