阅读说明：本技术 异质结电池的制作方法、异质结电池以及太阳能电池组件 (Manufacturing method of heterojunction cell, heterojunction cell and solar cell module ) 是由 张生利 王永谦 林纲正 陈刚 于 2021-09-14 设计创作，主要内容包括：本发明属于太阳能电池技术领域,尤其涉及异质结电池的制作方法、异质结电池以及太阳能电池组件,制作方法包括以下步骤：在硅片的正反面均依次沉积本征非晶硅和掺杂非晶硅,形成半成品电池；在半成品电池的正面沉积正导电膜,以及在半成品电池的反面沉积TCO-(1)、M-(x)和TCO-(2)的复合叠层背导电膜；分别在正导电膜和复合叠层背导电膜上制作金属电极。在复合叠层背导电膜内引入超薄金属层,极大提高背膜的导电性能,同时由于等离子增强效应提高长波长透射光的内反射,增加其在硅片中的吸收几率,以产生更多的光电流；另外,由于超薄金属层的插入可以极大的提高背膜导电率,可以使得背面图案仅保留焊接主栅,从而大大降低背面银浆耗量,降低生产成本。(The invention belongs to the technical field of solar cells, and particularly relates to a manufacturing method of a heterojunction cell, the heterojunction cell and a solar cell module, wherein the manufacturing method comprises the following steps: depositing intrinsic amorphous silicon and doped amorphous silicon on the front and back surfaces of the silicon wafer in sequence to form a semi-finished battery; depositing a positive conductive film on the front side of the semi-finished cell, and depositing a TCO on the back side of the semi-finished cell 1 、M x And TCO 2 The composite laminated back conductive film of (1); and respectively manufacturing metal electrodes on the front conductive film and the composite laminated back conductive film. The ultra-thin metal layer is introduced into the composite laminated back conductive film, so that the conductivity of the back film is greatly improved, and simultaneously, the plasma enhancement effect is improvedThe internal reflection of the high and long wavelength transmission light increases the absorption probability of the transmission light in the silicon chip so as to generate more photocurrent; in addition, due to the fact that the ultrathin metal layer is inserted, the conductivity of the back film can be greatly improved, the back pattern only remains a main welding grid, and therefore the consumption of back silver paste is greatly reduced, and production cost is reduced.)

1. A method for fabricating a heterojunction battery, comprising the steps of:

depositing intrinsic amorphous silicon and doped amorphous silicon on the front and back surfaces of the silicon wafer in sequence to form a semi-finished battery;

depositing a positive conductive film on the front side of the semi-finished cell toAnd depositing TCO on the reverse side of the semi-finished cell₁、M_xAnd TCO₂The composite laminated back conductive film of (1);

respectively manufacturing metal electrodes on the positive conductive film and the composite laminated back conductive film;

wherein, TCO₁And TCO₂Is aluminum-doped zinc oxide, tin-doped indium oxide, indium-doped zinc oxide, gallium-doped zinc oxide, indium-gallium-doped zinc oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide or zirconium-doped indium oxide, M_xIs silver, aluminum, copper or silver-copper alloy.

2. Method for manufacturing a heterojunction cell according to claim 1, wherein said deposition of TCO on the opposite side of said semi-finished cell₁、M_xAnd TCO₂The step of forming the composite laminated back conductive film specifically includes the steps of:

TCO (transparent conductive oxide) is sequentially arranged in chain type magnetron sputtering cavity₁Target material, M_xTarget material and TCO₂After the target material is fed, the semi-finished battery is controlled to pass through the chain type magnetron sputtering cavity so as to deposit TCO on the back surface of the semi-finished battery₁、M_xAnd TCO₂The composite laminated back conductive film of (1).

3. The method of claim 2, wherein the method is performed on a TCO₁、M_xAnd TCO₂During the deposition process of the composite laminated back conductive film, the TCO₁Target material, the M_xTarget material and TCO₂The vertical distance between the target material and the surface of the semi-finished battery is in the range of 4-12 cm, and the deposition pressure is in the range of 0.4-3 Pa.

4. The method of claim 2, wherein the sequential installation of TCOs in a chained magnetron sputtering chamber₁Target material, M_xTarget material and TCO₂After the target material is fed, the semi-finished battery is controlled to pass through the chain type magnetron sputtering cavity so as to deposit TCO on the back surface of the semi-finished battery₁、M_xAnd TCO₂The step of forming the composite laminated back conductive film specifically includes the steps of:

mounting TCO in a first deposition chamber₁Introducing high-purity argon doped with hydrogen as sputtering gas;

installing M in the second deposition chamber_xIntroducing high-purity argon as sputtering gas into the target;

installing TCO in third deposition chamber₂Introducing high-purity argon doped with hydrogen or oxygen as sputtering gas;

controlling the semi-finished product cell to sequentially pass through the first deposition chamber, the second deposition chamber and the third deposition chamber, controlling the temperature of the semi-finished product cell to be lower than 200 ℃ when the semi-finished product cell passes through the first deposition chamber, controlling the temperature of the semi-finished product cell to be in the range of 40-200 ℃ when the semi-finished product cell passes through the second deposition chamber, and controlling the temperature of the semi-finished product cell to be lower than 200 ℃ when the semi-finished product cell passes through the third deposition chamber so as to deposit TCO on the reverse side of the semi-finished product cell₁、M_xAnd TCO₂The composite laminated back conductive film of (1).

5. The method of claim 4, wherein TCO is controlled in the first deposition chamber₁The sputtering power of the target material is 0.4 to 2W/cm²Within the second deposition chamber, controlling M_xDeposition rate in the range of 1 to 10nm/min, TCO being controlled in the third deposition chamber₂The sputtering power of the target is 1.5 to 8W/cm²Within the range.

6. The method of fabricating a heterojunction cell as in claim 1 wherein the TCO₁In the range of 5 to 30nm, M_xIn the range of 5 to 20nm, TCO₂Is in the range of 30 to 90 nm.

7. The method of fabricating a heterojunction cell as in claim 1 wherein the TCO₁Has a carrier concentration of 1E20/cm or less³，TCO₂Is less than 5E-4ohm cm.

8. The method of fabricating a heterojunction cell according to claim 1,

al of the aluminum-doped zinc oxide₂O₃In the range of 0.5% to 4%;

said tin-doped indium oxide SnO₂In the range of 1% to 12%;

in of the indium-doped zinc oxide₂O₃In the range of 2% to 8%;

ga of the gallium-doped zinc oxide₂O₃In the range of 1.2% to 6%;

in of the indium gallium doped zinc oxide₂O₃In the range of 0.8 to 6% by mass, Ga₂O₃In the range of 0.4% to 5%;

the tungsten-doped indium oxide of WO₃In the range of 0.5% to 3%;

the MoO of the molybdenum-doped indium oxide₃In the range of 0.8% to 4%;

the zirconium-doped indium oxide ZrO₂Is in the range of 0.4% to 2.2%.

9. A heterojunction battery prepared by the method of manufacturing a heterojunction battery according to any one of claims 1 to 8, comprising:

a silicon wafer;

intrinsic amorphous silicon and doped amorphous silicon which are respectively arranged on the front side and the back side of the silicon wafer;

a positive conductive film disposed on the doped amorphous silicon on the front surface, and a TCO disposed on the doped amorphous silicon on the back surface₁、M_xAnd TCO₂The composite laminated back conductive film of (1);

metal electrodes respectively provided on the front conductive film and the composite laminated back conductive film;

wherein, TCO₁And TCO₂Is aluminum doped zinc oxide, tin doped indium oxide, indium doped zinc oxide, gallium doped zinc oxide, indium doped gallium zinc oxide, tungsten doped indium oxide, molybdenum doped indium oxide or zirconium doped indium oxide, and Mx is silver, aluminum, copper or silver-copper alloy.

10. A solar cell module comprising the heterojunction cell of claim 9.

Technical Field

The invention belongs to the technical field of solar cells, and particularly relates to a manufacturing method of a heterojunction cell, the heterojunction cell and a solar cell module.

Background

Currently, a heterojunction battery usually adopts a fully transparent conductive thin film (TCO) Indium Tin Oxide (ITO) as a back conductive channel, and the main preparation method is a magnetron sputtering method, wherein intrinsic amorphous silicon and doped amorphous silicon are sequentially deposited on the front and back sides of a silicon wafer, an ITO layer is deposited on the front and back sides of a semi-finished battery under a low temperature condition, and silver paste is printed to construct a front and back electrode, and the front and back electrodes are sintered at a temperature lower than 250 ℃ to realize ohmic contact.

However, the ITO thin film deposited by low temperature has poor conductivity, resulting in low photoelectric conversion efficiency of the finally manufactured heterojunction cell; in addition, silver paste used in the printing process is expensive, which results in a great increase in production cost.

Disclosure of Invention

The invention provides a manufacturing method of a heterojunction battery, and aims to solve the technical problems that a conductive film of the heterojunction battery manufactured by the existing manufacturing method is poor in conductivity and high in production cost.

The invention is realized in such a way, and provides a manufacturing method of a heterojunction battery, which comprises the following steps:

depositing intrinsic amorphous silicon and doped amorphous silicon on the front and back surfaces of the silicon wafer in sequence to form a semi-finished battery;

depositing a positive conductive film on the front side of the semi-finished cell, and depositing a TCO on the back side of the semi-finished cell₁、M_xAnd TCO₂The composite laminated back conductive film of (1);

respectively manufacturing metal electrodes on the positive conductive film and the composite laminated back conductive film;

wherein, TCO₁And TCO₂Is aluminum-doped zinc oxide, tin-doped indium oxide, indium-doped zinc oxide, gallium-doped zinc oxide, indium-gallium-doped zinc oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide or zirconium-doped indium oxide, M_xIs silver, aluminum, copper or silver-copper alloy.

Further, depositing TCO on the reverse side of the semi-finished cell₁、M_xAnd TCO₂The step of forming the composite laminated back conductive film specifically includes the steps of:

TCO (transparent conductive oxide) is sequentially arranged in chain type magnetron sputtering cavity₁Target material, M_xTarget material and TCO₂After the target material is fed, the semi-finished battery is controlled to pass through the chain type magnetron sputtering cavity so as to deposit TCO on the back surface of the semi-finished battery₁、M_xAnd TCO₂The composite laminated back conductive film of (1).

Further, in TCO₁、M_xAnd TCO₂During the deposition process of the composite laminated back conductive film, the TCO₁Target material, the M_xTarget material and TCO₂The vertical distance between the target material and the surface of the semi-finished battery is in the range of 4-12 cm, and the deposition pressure is in the range of 0.4-3 Pa.

Further, TCO is sequentially installed in the chain type magnetron sputtering cavity₁Target material, M_xTarget material and TCO₂After the target material is fed, the semi-finished battery is controlled to pass through the chain type magnetron sputtering cavity so as to deposit TCO on the back surface of the semi-finished battery₁、M_xAnd TCO₂The step of forming the composite laminated back conductive film specifically includes the steps of:

mounting TCO in a first deposition chamber₁Introducing high-purity argon doped with hydrogen as sputtering gas;

installing M in the second deposition chamber_xIntroducing high-purity argon as sputtering gas into the target;

installing TCO in third deposition chamber₂Introducing high-purity argon doped with hydrogen or oxygen as sputtering gas;

controlling the semi-finished product cell to sequentially pass through the first deposition chamber, the second deposition chamber and the third deposition chamber, controlling the temperature of the semi-finished product cell to be lower than 200 ℃ when the semi-finished product cell passes through the first deposition chamber, controlling the temperature of the semi-finished product cell to be in the range of 40-200 ℃ when the semi-finished product cell passes through the second deposition chamber, and controlling the temperature of the semi-finished product cell to be lower than 200 ℃ when the semi-finished product cell passes through the third deposition chamber so as to deposit TCO on the reverse side of the semi-finished product cell₁、M_xAnd TCO₂The composite laminated back conductive film of (1).

Further, in the first deposition chamber, TCO is controlled₁The sputtering power of the target material is 0.4 to 2W/cm²Within the second deposition chamber, controlling M_xDeposition rate in the range of 1 to 10nm/min, TCO being controlled in the third deposition chamber₂The sputtering power of the target is 1.5 to 8W/cm²Within the range.

Further, TCO₁In the range of 5 to 30nm, M_xIn the range of 5 to 20nm, TCO₂Is in the range of 30 to 90 nm.

Further, TCO₁Has a carrier concentration of 1E20/cm or less³，TCO₂Is less than 5E-4ohm cm.

Further, Al of the aluminum-doped zinc oxide₂O₃In the range of 0.5% to 4%;

said tin-doped indium oxide SnO₂Mass ofThe fraction is in the range of 1% to 12%;

in of the indium-doped zinc oxide₂O₃In the range of 2% to 8%;

ga of the gallium-doped zinc oxide₂O₃In the range of 1.2% to 6%;

in of the indium gallium doped zinc oxide₂O₃In the range of 0.8 to 6% by mass, Ga₂O₃In the range of 0.4% to 5%;

the tungsten-doped indium oxide of WO₃In the range of 0.5% to 3%;

the MoO of the molybdenum-doped indium oxide₃In the range of 0.8% to 4%;

the zirconium-doped indium oxide ZrO₂Is in the range of 0.4% to 2.2%.

The invention also provides a heterojunction battery, which is prepared by the manufacturing method of the heterojunction battery, and the heterojunction battery comprises:

a silicon wafer;

intrinsic amorphous silicon and doped amorphous silicon which are respectively arranged on the front side and the back side of the silicon wafer;

a positive conductive film disposed on the doped amorphous silicon on the front surface, and a TCO disposed on the doped amorphous silicon on the back surface₁、M_xAnd TCO₂The composite laminated back conductive film of (1);

metal electrodes respectively provided on the front conductive film and the composite laminated back conductive film;

wherein, TCO₁And TCO₂Is aluminum-doped zinc oxide, tin-doped indium oxide, indium-doped zinc oxide, gallium-doped zinc oxide, indium-gallium-doped zinc oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide or zirconium-doped indium oxide, M_xIs silver, aluminum, copper or silver-copper alloy.

The invention also provides a solar cell module comprising the heterojunction cell.

The invention has the beneficial effect that intrinsic amorphous silicon is deposited on the front and back surfaces of the silicon wafer in sequenceDoping amorphous silicon to form a semi-finished product cell, depositing a positive conductive film on the front surface of the semi-finished product cell, and depositing TCO on the back surface of the semi-finished product cell₁、M_xAnd TCO₂Finally, metal electrodes are respectively manufactured on the front conductive film and the composite laminated back conductive film; wherein, TCO₁And TCO₂Is aluminum-doped zinc oxide, tin-doped indium oxide, indium-doped zinc oxide, gallium-doped zinc oxide, indium-gallium-doped zinc oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide or zirconium-doped indium oxide, M_xIs silver, aluminum, copper or silver-copper alloy. The ultrathin metal layer is introduced into the composite laminated back conductive film, so that the conductivity of the back film is greatly improved, and meanwhile, the internal reflection of long-wavelength transmission light is improved due to the plasma enhancement effect, so that the absorption probability of the long-wavelength transmission light in a silicon wafer is increased, and more photocurrent is generated; in addition, due to the fact that the ultrathin metal layer is inserted, the conductivity of the back film can be greatly improved, the back pattern only remains a welding main grid, and a thin grid line is not needed, so that the consumption of back silver paste is greatly reduced, and the production cost is reduced.

Drawings

Fig. 1 is a block flow diagram of a method of fabricating a heterojunction battery provided by an embodiment of the invention;

fig. 2 is a further flow chart diagram of a method of fabricating a heterojunction battery provided by an embodiment of the invention;

fig. 3 is a schematic diagram of a heterojunction cell provided by an embodiment of the invention;

fig. 4 is an enlarged view of a portion a of fig. 3.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a method for manufacturing a heterojunction cell, which comprises the steps of depositing intrinsic amorphous silicon and doped amorphous silicon on the front and back surfaces of a silicon wafer 10 in sequence to form a semi-finished cell, depositing a positive conductive film 41 on the front surface of the semi-finished cell, and depositing a negative conductive film on the back surface of the semi-finished cellTCO₁、M_xAnd TCO₂Finally, metal electrodes are respectively manufactured on the front conductive film 41 and the composite laminated back conductive film 42; wherein, TCO₁And TCO₂Is aluminum-doped zinc oxide, tin-doped indium oxide, indium-doped zinc oxide, gallium-doped zinc oxide, indium-gallium-doped zinc oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide or zirconium-doped indium oxide, M_xIs silver, aluminum, copper or silver-copper alloy. The ultra-thin metal layer is introduced into the composite laminated back conductive film 42, so that the conductivity of the back film is greatly improved, and meanwhile, the internal reflection of long-wavelength transmission light is improved due to the plasma enhancement effect, so that the absorption probability of the long-wavelength transmission light in the silicon wafer 10 is increased, and more photocurrent is generated; in addition, due to the fact that the ultrathin metal layer is inserted, the conductivity of the back film can be greatly improved, the back pattern only remains a welding main grid, and a thin grid line is not needed, so that the consumption of back silver paste is greatly reduced, and the production cost is reduced.

Example one

Referring to fig. 1, a method for fabricating a heterojunction battery according to an embodiment of the present invention includes the following steps:

s10, sequentially depositing intrinsic amorphous silicon and doped amorphous silicon on the front side and the back side of the silicon wafer to form a semi-finished battery;

s20, depositing a positive conductive film on the front side of the semi-finished cell, and depositing TCO on the back side of the semi-finished cell₁、M_xAnd TCO₂The composite laminated back conductive film of (1);

s30, manufacturing metal electrodes on the front conductive film and the composite laminated back conductive film respectively;

wherein, TCO₁And TCO₂Is aluminum-doped zinc oxide, tin-doped indium oxide, indium-doped zinc oxide, gallium-doped zinc oxide, indium-gallium-doped zinc oxide, tungsten-doped indium oxide, molybdenum-doped indium oxide or zirconium-doped indium oxide, M_xIs silver, aluminum, copper or silver-copper alloy.

In this embodiment, first intrinsic amorphous silicon 21 and first doped amorphous silicon 31 are sequentially deposited on the front side of the silicon wafer 10, and then second intrinsic amorphous silicon 22 and second doped amorphous silicon 32 are sequentially deposited on the back side of the silicon wafer 10 to form a semi-finished productA battery. Then, a positive conductive film 41 is deposited on the front surface of the semi-finished cell with the first doped amorphous silicon 31, and then TCO is deposited on the back surface of the semi-finished cell with the second doped amorphous silicon 32₁、M_xAnd TCO₂The composite laminated back conductive film 42. Finally, a first metal electrode 51 is manufactured on the positive conductive film 41 by means of printing paste, and the TCO₁、M_xAnd TCO₂The second metal electrode 52 is formed on the composite laminated back conductive film 42 by printing paste, and sintering is performed in a low temperature environment to realize good ohmic contact, thereby forming a heterojunction battery.

Because the optical performance requirement of the heterojunction battery on the back conductive film is not as high as that of the front conductive film, the ultrathin metal layer is introduced into the composite laminated back conductive film 42, so that the conductive performance of the back film is greatly improved, and meanwhile, the internal reflection of long-wavelength transmission light is improved due to the plasma enhancement effect, so that the absorption probability of the long-wavelength transmission light in the silicon wafer 10 is increased, and more photocurrent is generated; in addition, due to the fact that the ultrathin metal layer is inserted, the conductivity of the back film can be greatly improved, the back pattern only remains a welding main grid, and a thin grid line is not needed, so that the consumption of back silver paste is greatly reduced, and the production cost is reduced.

For the first doped amorphous silicon 31 and the second doped amorphous silicon 32, when the first doped amorphous silicon 31 is n-type doped amorphous silicon, the second doped amorphous silicon 32 is p-type doped amorphous silicon; when the first doped amorphous silicon 31 is p-type doped amorphous silicon, the second doped amorphous silicon 32 is n-type doped amorphous silicon.

It should be noted that, when the silicon wafer 10 is obtained, the silicon wafer 10 needs to be cleaned and subjected to texturing on the surface thereof, and a textured surface is engraved on the surface thereof by etching.

With reference to fig. 2, further, the deposition of TCO on the reverse side of the semi-finished cell₁、M_xAnd TCO₂The step of forming the composite laminated back conductive film specifically includes the steps of:

s22, TCO is sequentially arranged in the chain type magnetron sputtering cavity₁Target material, M_xTarget material and TCO₂After the target material, controlling the semi-finished battery to pass through the chainMagnetron sputtering chamber for depositing TCO on the reverse side of the semi-finished cell₁、M_xAnd TCO₂The composite laminated back conductive film of (1).

In this embodiment, the chain magnetron sputtering chamber has a plurality of deposition chambers, and the TCO is sequentially installed in each deposition chamber₁Target material, M_xTarget material and TCO₂Controlling the semi-finished battery to sequentially pass through each deposition chamber in the chain type magnetron sputtering cavity, and adjusting TCO in the passing process₁Target material, M_xTarget material and TCO₂Sputtering power of target material to deposit TCO on the reverse side of semi-finished cell₁、M_xAnd TCO₂The composite laminated back conductive film 42.

In which in TCO₁、M_xAnd TCO₂During the deposition of the composite laminated back conductive film 42, the TCO₁Target material, the M_xTarget material and TCO₂The perpendicular distances of the target materials to the surface of the semi-finished cell are respectively in the range of 4 to 12cm, such as 4cm, 6cm, 8cm, 10cm and 12cm, and the deposition pressure is in the range of 0.4 to 3Pa, such as 1.2Pa, 2Pa and 2.8 Pa.

Specifically, TCO is sequentially arranged in the chain type magnetron sputtering cavity₁Target material, M_xTarget material and TCO₂After the target material is fed, the semi-finished battery is controlled to pass through the chain type magnetron sputtering cavity so as to deposit TCO on the back surface of the semi-finished battery₁、M_xAnd TCO₂The step of forming the composite laminated back conductive film specifically includes the steps of:

mounting TCO in a first deposition chamber₁Introducing high-purity argon doped with hydrogen as sputtering gas;

installing M in the second deposition chamber_xIntroducing high-purity argon as sputtering gas into the target;

installing TCO in third deposition chamber₂Introducing high-purity argon doped with hydrogen or oxygen as sputtering gas;

controlling the semi-finished product battery to sequentially pass through the first deposition chamber and the second deposition chamberThe semi-finished product cell temperature is controlled to be lower than 200 ℃ when the semi-finished product cell passes through the first deposition chamber, the semi-finished product cell temperature is controlled to be in the range of 40-200 ℃ when the semi-finished product cell passes through the second deposition chamber, and the semi-finished product cell temperature is controlled to be lower than 200 ℃ when the semi-finished product cell passes through the third deposition chamber so as to deposit TCO on the reverse surface of the semi-finished product cell₁、M_xAnd TCO₂The composite laminated back conductive film of (1).

In the embodiment, the chain type magnetron sputtering cavity is provided with at least three deposition chambers. First, TCO is installed in the first deposition chamber₁The method comprises the following steps of (1) introducing high-purity argon doped with hydrogen as sputtering gas into a target, wherein the volume fraction of the hydrogen is not more than 10%; then installing M in the second deposition chamber_xIntroducing high-purity argon as sputtering gas into the target; then installing TCO in a third deposition chamber₂And (3) introducing high-purity argon doped with hydrogen or oxygen as sputtering gas, wherein if the target is doped with the hydrogen, the volume fraction of the hydrogen is not more than 6%, and if the target is doped with the oxygen, the volume fraction of the oxygen is not more than 2%. After the target material is installed, placing a semi-finished product battery on a support plate, controlling the semi-finished product battery to sequentially pass through a first deposition chamber, a second deposition chamber and a third deposition chamber, controlling the temperature of the semi-finished product battery to be lower than 200 ℃ when the semi-finished product battery passes through the first deposition chamber, controlling the temperature of the semi-finished product battery to be within the range of 40-200 ℃ when the semi-finished product battery passes through the second deposition chamber, not heating the semi-finished product battery when the semi-finished product battery passes through the third deposition chamber, and controlling the temperature of the semi-finished product battery to be lower than 200 ℃ so as to deposit TCO on the reverse side of the semi-finished product battery₁、M_xAnd TCO₂The composite laminated back conductive film 42. When the semi-finished battery is controlled to sequentially pass through the deposition chamber, the required sputtering power is matched in time according to the thickness of the lamination, so that the preparation of the composite laminated back conductive film 42 is smoothly realized.

Wherein TCO is controlled in the first deposition chamber₁The sputtering power of the target material is 0.4 to 2W/cm²In the range, for example, 0.6W/cm²、1W/cm²、1.4W/cm²、1.8W/cm²At the secondIn the deposition chamber, control M_xDeposition rate in the range of 1 to 10nm/min, e.g. 2nm/min, 4nm/min, 6nm/min, 8nm/min, 10nm/min, in which third deposition chamber TCO is controlled₂The sputtering power of the target is 1.5 to 8W/cm²In the range, for example, 1.5W/cm²、3W/cm²、4.5W/cm²、6W/cm²、7.5W/cm²。

Wherein, TCO₁In the range of 5 to 30nm, e.g. 8nm, 16nm, 24nm, M_xIn the range of 5 to 20nm, e.g. 5nm, 10nm, 15nm, TCO₂Is in the range of 30 to 90nm, e.g. 40nm, 50nm, 60nm, 70nm, 80 nm.

Wherein, TCO₁Has a carrier concentration of 1E20/cm or less³，TCO₂Is less than 5E-4ohm cm.

Wherein for TCO₁And TCO₂Al of said aluminum-doped zinc oxide₂O₃In the range of 0.5% to 4%; said tin-doped indium oxide SnO₂In the range of 1% to 12%; in of the indium-doped zinc oxide₂O₃In the range of 2% to 8%; ga of the gallium-doped zinc oxide₂O₃In the range of 1.2% to 6%; in of the indium gallium doped zinc oxide₂O₃In the range of 0.8 to 6% by mass, Ga₂O₃In the range of 0.4% to 5%; the tungsten-doped indium oxide of WO₃In the range of 0.5% to 3%; the MoO of the molybdenum-doped indium oxide₃In the range of 0.8% to 4%; the zirconium-doped indium oxide ZrO₂Is in the range of 0.4% to 2.2%.

TCO after multiple tests₁Is tin-doped indium oxide, M_xBeing silver, TCO₂The indium-doped zinc oxide is indium-doped zinc oxide, the thickness of the tin-doped indium oxide is 15nm, the thickness of the silver is 10nm, the thickness of the indium-doped zinc oxide is 50nm, excellent effects can be realized, and the sheet resistance of the laminated structure can be lower than 5 ohm/sq.

Of course, other embodiments can be usedThe preferred results are obtained, for example, in the following embodiments: (1) TCO₁Is tin-doped indium oxide, M_xBeing aluminium, TCO₂Is indium-doped zinc oxide; ② TCO₁Is tin-doped indium oxide, M_xBeing copper, TCO₂Is indium-doped zinc oxide; ③ TCO₁Is tin-doped indium oxide, M_xBeing copper, TCO₂Is aluminum-doped zinc oxide; tetra (TCO)₁Is aluminum-doped zinc oxide, M_xBeing copper, TCO₂Is indium-doped zinc oxide.

Example two

Referring to fig. 3, the second embodiment provides a heterojunction battery prepared by the method of the first embodiment, the heterojunction battery includes:

a silicon wafer 10;

intrinsic amorphous silicon and doped amorphous silicon which are respectively arranged on the front side and the back side of the silicon wafer 10;

a positive conductive film 41 disposed on the doped amorphous silicon on the front surface, and a TCO disposed on the doped amorphous silicon on the back surface₁、M_xAnd TCO₂The composite laminated back conductive film 42;

metal electrodes respectively provided on the front conductive film 41 and the composite laminated back conductive film 42;

wherein, TCO₁And TCO₂Is aluminum doped zinc oxide, tin doped indium oxide, indium doped zinc oxide, gallium doped zinc oxide, indium doped gallium zinc oxide, tungsten doped indium oxide, molybdenum doped indium oxide or zirconium doped indium oxide, and Mx is silver, aluminum, copper or silver-copper alloy.

In this embodiment, the front surface of the silicon wafer 10 is provided with a first intrinsic amorphous silicon 21 and a first doped amorphous silicon 31, the back surface is provided with a second intrinsic amorphous silicon 22 and a second doped amorphous silicon 32, the first doped amorphous silicon 31 is provided with a positive conductive film 41, and the second doped amorphous silicon 32 is provided with a TCO₁、M_xAnd TCO₂The front conductive film 41 of the composite laminated back conductive film 42 is provided with a first metal electrode 51 and TCO₁、M_xAnd TCO₂The second metal electrode 52 is provided on the composite laminated back conductive film 42. The optical performance requirement of the heterojunction cell on the back conductive film is not as good as that of the front conductive filmThe requirement on the optical performance of the electric film is high, an ultrathin metal layer is introduced into the composite laminated back conductive film 42, the conductivity of the back film is greatly improved, and meanwhile, the internal reflection of long-wavelength transmission light is improved due to the plasma enhancement effect, so that the absorption probability of the long-wavelength transmission light in the silicon wafer 10 is increased, and more photocurrent is generated; in addition, due to the fact that the ultrathin metal layer is inserted, the conductivity of the back film can be greatly improved, the back pattern only remains a welding main grid, and a thin grid line is not needed, so that the consumption of back silver paste is greatly reduced, and the production cost is reduced.

Referring to FIG. 4, on the composite laminated back conductive film 42, three layers of TCO are disposed from top to bottom₁、M_xAnd TCO₂。

EXAMPLE III

A third embodiment provides a solar cell module including the heterojunction cell as described in the second embodiment. Because the optical performance requirement of the heterojunction battery on the back conductive film is not as high as that of the front conductive film, the ultrathin metal layer is introduced into the composite laminated back conductive film 42, so that the conductive performance of the back film is greatly improved, and meanwhile, the internal reflection of long-wavelength transmission light is improved due to the plasma enhancement effect, so that the absorption probability of the long-wavelength transmission light in the silicon wafer 10 is increased, and more photocurrent is generated; in addition, due to the fact that the ultrathin metal layer is inserted, the conductivity of the back film can be greatly improved, the back pattern only remains a welding main grid, and a thin grid line is not needed, so that the consumption of back silver paste is greatly reduced, and the production cost is reduced.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.