Solar cell

Abstract

The utility model discloses a solar cell which comprises the following components: a photoelectric conversion unit which comprises a light receiving surface and a backlight surface which are oppositely arranged; the transparent conducting layer comprises a first transparent conducting layer located on the light receiving surface of the photoelectric conversion unit and a second transparent conducting layer located on the backlight surface of the photoelectric conversion unit; the electrodes comprise a first electrode electrically contacted with the first transparent conductive layer and a second electrode electrically contacted with the second transparent conductive layer; wherein the second transparent conductive layer comprises a second optical dominant layer and a second electrode contact layer which are sequentially stacked on the backlight surface of the photoelectric conversion unit, the thickness of the second electrode contact layer is larger than or equal to 15 nm, and the mobility of the second electrode contact layer is smaller than that of the second optical dominant layer. By optimizing the structure, the thickness, the mobility and the like of the transparent conducting layer on the back surface of the cell, higher optical gain and electrical gain can be obtained, and the photoelectric conversion efficiency of the solar cell is effectively improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of solar energy, and in particular relates to a solar cell. Background Art

[0002] Heterojunction cell (HJT) is a hybrid solar cell made of crystalline silicon substrate and amorphous silicon thin film. It has many advantages such as simple preparation process, low process temperature, high open circuit voltage, high photoelectric conversion efficiency and low temperature coefficient. It is one of the most widely used high-efficiency crystalline silicon solar energy technologies.

[0003] With the introduction of P-side microcrystals in heterojunction cells, the back of the cell needs to meet more than just electrical requirements. Similar to the N-side transparent conductive layer (TCO layer), a suitable optical window can further improve the cell efficiency. At the same time, in order to ensure good contact with the electrode, a high carrier concentration design is usually used in the TCO layer in contact with the electrode to ensure contact. In order to avoid the increase in optical loss caused by high carrier concentration, the film thickness of this layer is usually designed to be reduced (≤10nm).

[0004] During the experiment, it was found that the electrode contact resistivity was not only affected by the TCO layer in contact with the electrode. The low-temperature silver paste had a certain corrosion depth when in contact with the TCO layer. In order to achieve independent regulation of the optical advantage layer and the electrode contact layer, different film thicknesses were designed on the back of the battery to increase the thickness of the optical advantage layer and ensure the required depth of contact between the low-temperature paste and the TCO layer, so as to obtain better photoelectric conversion efficiency.

[0005] Therefore, in view of the above technical problems, it is necessary to provide a solar cell. Utility Model Content

[0006] In view of this, the purpose of the utility model is to provide a solar cell, which improves the photoelectric conversion efficiency of the cell by optimizing the thickness and mobility of the transparent conductive layer on the back side of the cell.

[0007] In order to achieve the above purpose, the technical solution provided by an embodiment of the present utility model is as follows:

[0008] A solar cell, comprising:

[0009] The photoelectric conversion unit comprises a light receiving surface and a backlight surface which are arranged opposite to each other;

[0010] The transparent conductive layer includes a first transparent conductive layer located on the light-receiving surface of the photoelectric conversion unit and a second transparent conductive layer located on the backlight surface of the photoelectric conversion unit;

[0011] Electrodes, including a first electrode electrically contacting the first transparent conductive layer and a second electrode electrically contacting the second transparent conductive layer;

[0012] The second transparent conductive layer includes a second optical advantage layer and a second electrode contact layer stacked sequentially on the backlight surface of the photoelectric conversion unit, the thickness of the second electrode contact layer is greater than or equal to 15 nm, and the mobility of the second electrode contact layer is less than the mobility of the second optical advantage layer.

[0013] In one embodiment, the thickness of the second transparent conductive layer is 80 nm to 120 nm, the thickness of the second optically advantageous layer is 30 nm to 100 nm, and the thickness of the second electrode contact layer is 15 nm to 50 nm.

[0014] In one embodiment, the ratio of the mobility of the second electrode contact layer to the mobility of the second optically advantageous layer is (0.7-0.9):1; and / or,

[0015] The mobility of the second optically advantageous layer is 35 cm 2 / V·s~100cm 2 / V·s, the mobility of the second electrode contact layer is 25cm 2 / V·s~90cm 2 / V·s.

[0016] In one embodiment, the carrier concentration of the second electrode contact layer is greater than the carrier concentration of the second optically advantageous layer.

[0017] In one embodiment, the carrier concentration of the second electrode contact layer is 2.0E20 / cm 3 ~4.0E20 / cm 3 The carrier concentration of the second optically advantageous layer is 0.2E20 / cm 3 ~2.0E20 / cm 3 .

[0018] In one embodiment, the transparent conductive layer is any one of an ITO layer, an IWO layer, an IMO layer, an AZO layer, and a GZO layer.

[0019] In one embodiment, the first transparent conductive layer includes a first optically advantageous layer and a first electrode contact layer sequentially stacked on the light-receiving surface of the photoelectric conversion unit.

[0020] In one embodiment, the thickness of the first electrode contact layer is greater than or equal to 15 nm, and the mobility of the first electrode contact layer is less than the mobility of the first optically advantageous layer; and / or,

[0021] The carrier concentration of the first electrode contact layer is greater than the carrier concentration of the first optically advantageous layer.

[0022] In one embodiment, the thickness of the first transparent conductive layer is 80nm-120nm, the thickness of the first optically advantageous layer is 30nm-100nm, and the thickness of the first electrode contact layer is 15nm-50nm; and / or,

[0023] The ratio of the mobility of the first electrode contact layer to the mobility of the first optically advantageous layer is (0.7-0.9):1; and / or,

[0024] The mobility of the first optically advantageous layer is 35 cm 2 / V·s~100cm 2 / V·s, the mobility of the first electrode contact layer is 25cm 2 / V·s~90cm 2 / V·s; and / or,

[0025] The carrier concentration of the first electrode contact layer is 2.0E20 / cm 3 ~4.0E20 / cm 3 The carrier concentration of the first optically advantageous layer is 0.2E20 / cm 3 ~2.0E20 / cm 3 .

[0026] In one embodiment, the solar cell is a heterojunction cell, and the photoelectric conversion unit includes:

[0027] A substrate, comprising a first surface and a second surface arranged opposite to each other, wherein the substrate is N-type doped or P-type doped;

[0028] A first intrinsic layer, located on a first surface of the substrate, wherein the first intrinsic layer is an intrinsic amorphous silicon layer and / or an intrinsic microcrystalline silicon layer;

[0029] A first doped layer, located on the first intrinsic layer, wherein the first doped layer is an amorphous silicon layer and / or a microcrystalline silicon layer, and the doping type is the same as the doping type of the substrate;

[0030] A second intrinsic layer, located on the second surface of the substrate, wherein the second intrinsic layer is an intrinsic amorphous silicon layer and / or an intrinsic microcrystalline silicon layer;

[0031] The second doped layer is located on the second intrinsic layer. The second doped layer is an amorphous silicon layer and / or a microcrystalline silicon layer. The doping type of the second doped layer is opposite to that of the substrate.

[0032] The utility model has the following beneficial effects:

[0033] The utility model can obtain higher optical gain and electrical gain by optimizing the structure, thickness and mobility of the transparent conductive layer on the back of the battery, thereby effectively improving the photoelectric conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 It is a schematic diagram of the structure of the solar cell in the utility model;

[0036] Figure 2 It is a schematic diagram of the structure of a solar cell in a comparative example of the utility model;

[0037] Figure 3 This is a schematic diagram of the structure of the solar cell in Example 1 of the utility model;

[0038] Figure 4 This is a schematic diagram of the structure of the solar cell in Example 2 of the utility model. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0040] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0041] Ginseng Figure 1 The structure diagram of the solar cell in the utility model is shown, which includes:

[0042] The photoelectric conversion unit 100 includes a light receiving surface and a backlight surface which are arranged opposite to each other;

[0043] The transparent conductive layer includes a first transparent conductive layer (TCO1) 21 located on the light-receiving surface of the photoelectric conversion unit 100 and a second transparent conductive layer (TCO2) 22 located on the backlight surface of the photoelectric conversion unit 100;

[0044] The electrodes include a first electrode 31 electrically contacting the first transparent conductive layer 21 and a second electrode 32 electrically contacting the second transparent conductive layer 22 .

[0045] The second transparent conductive layer 22 in the present invention includes a second optical advantage layer 221 (i.e., an inner transparent conductive layer) electrically contacting the backlight surface of the photoelectric conversion unit 100, and a second electrode contact layer 222 (i.e., an outer transparent conductive layer) electrically contacting the second electrode 32, and the second electrode contact layer 222 is stacked on the second optical advantage layer 221.

[0046] The thickness of the second electrode contact layer 222 is greater than or equal to 15 nm, and the mobility of the second electrode contact layer 222 is less than the mobility of the second optical advantage layer 221 .

[0047] Preferably, the thickness of the second transparent conductive layer 22 (ie, the sum of the thickness of the second electrode contact layer 222 and the second optical advantage layer 221 ) is 80nm-120nm, the thickness of the second optical advantage layer 221 is 30nm-100nm, and the thickness of the second electrode contact layer 222 is 15nm-50nm.

[0048] Preferably, the ratio of the mobility of the second electrode contact layer 222 to the mobility of the second optically advantageous layer 221 is (0.7-0.9):1, and the mobility of the second optically advantageous layer 221 is 35 cm 2 / V·s~100cm 2 / V·s, and the mobility of the second electrode contact layer 222 is 25cm 2 / V·s~90cm 2 / V·s.

[0049] Furthermore, in the present invention, the carrier concentration of the second electrode contact layer 222 is greater than the carrier concentration of the second optical advantage layer 221 .

[0050] Preferably, the carrier concentration of the second electrode contact layer 222 is 2.0E20 / cm 3 ~4.0E20 / cm 3 The carrier concentration of the second optical advantage layer 221 is 0.2E20 / cm 3 ~2.0E20 / cm 3 .

[0051] The second optical advantage layer 221 and the second electrode contact layer 222 in the second transparent conductive layer 22 of the present invention are made of the same transparent conductive oxide material. The transparent conductive layer can be any one of an ITO layer, an IWO layer, an IMO layer, an AZO layer, a GZO layer, and the like.

[0052] In order to further improve the conductivity of the transparent conductive layer, metal or metal oxide is doped into the transparent conductive layer, and the doping amount may be 0.5 wt % to 10 wt %.

[0053] For example, the ITO layer can be doped with a combination of one or more of SnO2, TiO2, CeO2, Ta2O5, Ga2O3, ZrO2, MoO3, etc. in the In2O3 substrate, the IWO layer is doped with WO2, and the IMO layer is doped with MoO3; the AZO layer is doped with Al2O3 in the ZnO substrate; and the GZO is doped with Ga2O3 in the ZnO substrate.

[0054] The above-mentioned transparent conductive layer only lists some materials. The transparent conductive layer in the present utility model is not limited to the above-mentioned materials. All doped / undoped oxides that can achieve both conductivity and transparency belong to the scope of protection of the present utility model.

[0055] Preferably, the first transparent conductive layer 21 in the present invention includes a first optical advantage layer 211 (i.e., an inner transparent conductive layer) electrically in contact with the light-receiving surface of the photoelectric conversion unit 100, and a first electrode contact layer 212 (i.e., an outer transparent conductive layer) electrically in contact with the first electrode 31, and the first electrode contact layer 212 is stacked on the first optical advantage layer 221.

[0056] In the first transparent conductive layer 21 of the present invention, the structure, material, carrier concentration, mobility, etc. of the first optical advantage layer 211 and the first electrode contact layer 212 are completely the same as those of the second transparent conductive layer 22 and will not be described again here.

[0057] Exemplarily, the solar cell in the present invention is described by taking a heterojunction cell (HJT) as an example, the photoelectric conversion unit 100 is the cell body of the heterojunction cell, the light-receiving surface is the front side (or upper surface) of the cell body, and the backlight surface is the back side (or lower surface) of the cell body.

[0058] Specifically, the photoelectric conversion unit 100 includes:

[0059] The substrate 11 includes a first surface (i.e., a front surface or an upper surface) and a second surface (i.e., a back surface or a lower surface) that are arranged opposite to each other, and the substrate is N-type doped or P-type doped;

[0060] A first intrinsic layer 121, located on the first surface of the substrate 11, and the first intrinsic layer 121 may be an intrinsic amorphous silicon layer or an intrinsic microcrystalline silicon layer;

[0061] A first doping layer 131 is located on the first intrinsic layer 121. The first doping layer 131 may be an amorphous silicon layer or a microcrystalline silicon layer, and the doping type is the same as that of the substrate;

[0062] A second intrinsic layer 122, located on the second surface of the substrate 11, and the second intrinsic layer 122 may be an intrinsic amorphous silicon layer or an intrinsic microcrystalline silicon layer;

[0063] The second doping layer 132 is located on the second intrinsic layer 122 . The second doping layer 132 may be an amorphous silicon layer or a microcrystalline silicon layer, and the doping type of the second doping layer 132 is opposite to the doping type of the substrate.

[0064] Taking an N-type heterojunction battery as an example, the substrate 11 is an N-type substrate, the first doping layer 131 is N-type doped, and the second doping layer 132 is P-type doped.

[0065] The structure and principle of the photoelectric conversion unit in the heterojunction battery are prior art and will not be described in detail here.

[0066] Taking a heterojunction solar cell as an example, the method for preparing the solar cell in the utility model comprises the following steps:

[0067] 1. Prepare the photoelectric conversion unit in the solar cell.

[0068] 1.1. Provide silicon wafers.

[0069] The silicon wafer in the present invention is preferably an N-type single crystal silicon wafer with a resistivity of 0.5Ω.cm to 3Ω.cm, a thickness of 150μm to 200μm, and a size of 182mm.

[0070] 1.2. Cleaning and velveting.

[0071] The oxide layer on the surface of the silicon wafer is removed by using a diluted HF solution with a solubility of 5%, and a shallow pyramid velvet structure is formed on the surface by using a method of KOH or NaOH or tetramethylammonium hydroxide (TMAH) plus alcohol and utilizing anisotropic etching of single crystal silicon.

[0072] 1.3. Deposit an amorphous silicon layer.

[0073] First, SiH4 (silane) gas is introduced into a vacuum chamber, and a first intrinsic amorphous silicon layer is formed on the entire area of ​​the first surface of the N-type single crystal silicon wafer by a plasma CVD process; then SiH4 gas, H2 gas and PH3 (phosphine) gas are introduced into the vacuum chamber, and an N-type doped amorphous silicon layer is formed on the first intrinsic amorphous silicon layer by a plasma CVD process;

[0074] Next, turn it over, change the tray, and then introduce SiH4 (silane) gas into the vacuum chamber, and form a second intrinsic amorphous silicon layer on the entire area of ​​the second surface of the N-type single crystal silicon wafer through a plasma CVD process; then introduce SiH4 gas, H2 gas and PH3 (phosphine) gas into the vacuum chamber, and form a P-type doped amorphous silicon layer on the second intrinsic amorphous silicon layer through a plasma CVD process.

[0075] 2. Depositing a first transparent conductive layer on the light-receiving surface of the photoelectric conversion unit, and depositing a second transparent conductive layer on the backlight surface of the photoelectric conversion unit.

[0076] The amorphous silicon layer on the front and back sides is coated by a physical vapor deposition (PVD) process, which may be a reactive plasma deposition (RPD) process or a magnetron sputtering process. The back side is shielded by the edge of the carrier design (or by a mask), and the specific shielding area around it is ~0.8 mm.

[0077] When preparing the transparent conductive layer, different transparent conductive layers are sequentially deposited on the substrate after depositing the amorphous silicon layer, namely, the optical advantage layer (inner transparent conductive layer) and the electrode contact layer (outer transparent conductive layer).

[0078] The specific method is:

[0079] PVD mass production equipment has at least 4 non-contaminating coating targets, with different target materials installed on the targets; the substrate is placed on a carrier and sequentially coated at different targets to obtain the desired film design. The process parameters are adjusted at different targets to adjust the thickness, mobility, carrier concentration, etc. of the transparent conductive layer to within the preset range.

[0080] The physical vapor deposition process uses a certain amount of energy to bombard the material in the target material, and at the same time introduces the corresponding gas (oxygen O2, hydrogen H2 and argon Ar) to form a certain atmosphere. Different process parameters are selected for different transparent conductive layers, including deposition temperature, deposition time, flow ratio of each gas in the gas, pressure in the deposition chamber, temperature in the deposition chamber, etc.

[0081] 3. Form a first electrode and a second electrode on the first transparent conductive layer and the second transparent conductive layer respectively.

[0082] A layer of low-temperature conductive silver paste is printed on the transparent conductive layer on the front and back sides respectively by screen printing technology, and then sintered and cured at a low temperature of 150°C to 300°C to form a good ohmic contact electrode.

[0083] The optical advantage layer and the electrode contact layer in the utility model adopt the same TCO material, and the two-layer structure can be carried out in the PVD deposition process, and only different process conditions need to be controlled, and no new deposition steps will be added.

[0084] The present invention is further described below in conjunction with specific embodiments.

[0085] Comparative Example:

[0086] Ginseng Figure 2 As shown, the solar cell in this comparative example is a heterojunction cell, which includes:

[0087] The substrate 11 comprises a first surface and a second surface which are arranged opposite to each other, and the substrate is N-type doped;

[0088] A first intrinsic layer 121 is located on the first surface of the substrate 11, and the first intrinsic layer 121 is an intrinsic amorphous silicon layer;

[0089] A first doped layer 131 is located on the first intrinsic layer 121 , and the first doped layer 131 is an N-type doped amorphous silicon layer;

[0090] A second intrinsic layer 122, located on the second surface of the substrate 11, and the second intrinsic layer 122 is an intrinsic amorphous silicon layer;

[0091] A second doped layer 132 , located on the second intrinsic layer 122 , the second doped layer 132 is a P-type doped amorphous silicon layer;

[0092] The first transparent conductive layer 21 is an ITO layer doped with SnO2, with a doping amount of 0.5wt% and a carrier concentration of 3.0E20 / cm 3 , thickness is 90nm;

[0093] The second transparent conductive layer 22 is an ITO layer doped with SnO2, with a doping amount of 10 wt % and a carrier concentration of 3.0E20 / cm 3 , thickness is 90nm;

[0094] A first electrode 31, located on the first transparent conductive layer 21 and electrically contacting therewith;

[0095] The second electrode 32 is located on the second transparent conductive layer 22 and is in electrical contact with the second transparent conductive layer 22 .

[0096] In the PVD process of the first transparent conductive layer 21, the O2 flow rate in the gas introduced accounts for 4%, and the pressure of the deposition chamber is 0.55Pa; in the PVD process of the second transparent conductive layer 22, the O2 flow rate in the gas introduced accounts for 4.5%, and the pressure of the deposition chamber is 0.45Pa.

[0097] Embodiment 1:

[0098] Ginseng Figure 3 As shown, the solar cell in this embodiment is a heterojunction cell, which includes:

[0099] The substrate 11 comprises a first surface and a second surface which are arranged opposite to each other, and the substrate is N-type doped;

[0100] A first intrinsic layer 121 is located on the first surface of the substrate 11, and the first intrinsic layer 121 is an intrinsic amorphous silicon layer;

[0101] A first doped layer 131 is located on the first intrinsic layer 121 , and the first doped layer 131 is an N-type doped amorphous silicon layer;

[0102] A second intrinsic layer 122 is located on the second surface of the substrate 11, and the second intrinsic layer 122 is an intrinsic amorphous silicon layer;

[0103] A second doped layer 132 , located on the second intrinsic layer 122 , the second doped layer 132 is a P-type doped amorphous silicon layer;

[0104] The first transparent conductive layer 21 includes a first optically advantageous layer (inner transparent conductive layer) 211 stacked on the first doped layer 131 and a first electrode contact layer (outer transparent conductive layer) 212 stacked on the first optically advantageous layer, wherein the first optically advantageous layer 211 is an ITO layer doped with SnO2, the doping amount is 0.5wt%, and the carrier concentration is 1.1E20 / cm 3 , the mobility is 70cm 2 / V·s, with a thickness of 85nm. The first electrode contact layer 212 is an ITO layer doped with SnO2, with a doping amount of 10wt% and a carrier concentration of 2.5E20 / cm 3 , the mobility is 50cm 2 / V·s, thickness is 12.5nm;

[0105] The second transparent conductive layer 22 is an ITO layer doped with SnO2, with a doping amount of 10 wt % and a carrier concentration of 3.0E20 / cm 3 , thickness is 90nm;

[0106] A first electrode 31, located on the first electrode contact layer 212 and electrically contacting therewith;

[0107] The second electrode 32 is located on the second electrode contact layer 222 and electrically contacts the second electrode contact layer 222 .

[0108] In the PVD process of the first optical advantage layer 211, the O2 flow rate in the gas introduced is 3.5%. The pressure of the deposition chamber is 0.8 Pa, and the temperature of the deposition chamber is 170°C. In the PVD process of the first electrode contact layer 212, the O2 flow rate in the gas introduced is 2%. The pressure of the deposition chamber is 0.55 Pa, and the temperature of the deposition chamber is 145°C.

[0109] Embodiment 2:

[0110] Ginseng Figure 4 As shown, the solar cell in this embodiment is a heterojunction cell, which includes:

[0111] The substrate 11 comprises a first surface and a second surface which are arranged opposite to each other, and the substrate is N-type doped;

[0112] A first intrinsic layer 121 is located on the first surface of the substrate 11, and the first intrinsic layer 121 is an intrinsic amorphous silicon layer;

[0113] A first doped layer 131 is located on the first intrinsic layer 121 , and the first doped layer 131 is an N-type doped amorphous silicon layer;

[0114] A second intrinsic layer 122, located on the second surface of the substrate 11, and the second intrinsic layer 122 is an intrinsic amorphous silicon layer;

[0115] A second doped layer 132 , located on the second intrinsic layer 122 , the second doped layer 132 is a P-type doped amorphous silicon layer;

[0116] The first transparent conductive layer 21 includes a first optically advantageous layer (inner transparent conductive layer) 211 stacked on the first doped layer 131 and a first electrode contact layer (outer transparent conductive layer) 212 stacked on the first optically advantageous layer, wherein the first optically advantageous layer 211 is an ITO layer doped with SnO2, the doping amount is 0.5wt%, and the carrier concentration is 1.1E20 / cm 3 , the mobility is 70cm 2 / V·s, with a thickness of 75nm. The first electrode contact layer 212 is an ITO layer doped with SnO2, with a doping amount of 0.5wt% and a carrier concentration of 2.5E20 / cm 3 , the mobility is 50cm 2 / V·s, thickness is 20nm;

[0117] The second transparent conductive layer 22 includes a second optically advantageous layer (inner transparent conductive layer) 221 stacked on the second doping layer 132 and a second electrode contact layer (outer transparent conductive layer) 222 stacked on the second optically advantageous layer, wherein the second optically advantageous layer 221 is an ITO layer doped with SnO2, the doping amount is 0.5wt%, and the carrier concentration is 1.1E20 / cm 3 , the mobility is 70cm 2 / V·s, with a thickness of 75nm. The second electrode contact layer 222 is an ITO layer doped with SnO2, with a doping amount of 0.5wt% and a carrier concentration of 2.5E20 / cm 3 , the mobility is 50cm 2 / V·s, thickness is 20nm; the ratio of the mobility of the second electrode contact layer 222 to the mobility of the second optical advantage layer 221 is 0.71:1;

[0118] A first electrode 31, located on the first electrode contact layer 212 and electrically contacting therewith;

[0119] The second electrode 32 is located on the second electrode contact layer 222 and electrically contacts the second electrode contact layer 222 .

[0120] In the PVD process of the first optical advantage layer 211, the O2 flow rate in the gas introduced is 3.5%. The pressure of the deposition chamber is 0.8 Pa, and the temperature of the deposition chamber is 170°C; in the PVD process of the first electrode contact layer 212, the O2 flow rate in the gas introduced is 2%. The pressure of the deposition chamber is 0.55 Pa, and the temperature of the deposition chamber is 145°C;

[0121] In the PVD process of the second optical advantage layer 221, the O2 flow rate in the gas introduced is 3.5%. The pressure of the deposition chamber is 0.8 Pa, and the temperature of the deposition chamber is 170°C; in the PVD process of the second electrode contact layer 222, the O2 flow rate in the gas introduced is 2%. The pressure of the deposition chamber is 0.55 Pa, and the temperature of the deposition chamber is 145°C.

[0122] After testing, the performance parameters of the heterojunction battery in the comparative example and the embodiment are as follows:

[0123]

[0124] It can be seen that through the design of the front TCO layer in Example 1, the open circuit voltage Voc and fill factor FF of the battery are comparable to those of the comparative example, and the current density Jsc and efficiency Eta are improved to a certain extent.

[0125] In Example 2, by optimizing the structure, thickness and mobility of the back TCO layer, the open circuit voltage Voc (passivation performance) is comparable to that of the comparative example, the fill factor FF is increased by 0.23%, and the current density Jsc is increased by 0.52 mA / cm 2 , efficiency Eta increased by 0.40%.

[0126] It can be seen from the above technical solutions that the utility model has the following beneficial effects:

[0127] The utility model can obtain higher optical gain and electrical gain by optimizing the structure, thickness and mobility of the transparent conductive layer on the back of the battery, thereby effectively improving the photoelectric conversion efficiency of the solar cell.

[0128] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0129] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A solar cell, characterized in that: The solar cell comprises: The photoelectric conversion unit comprises a light receiving surface and a backlight surface which are arranged opposite to each other; The transparent conductive layer includes a first transparent conductive layer located on the light-receiving surface of the photoelectric conversion unit and a second transparent conductive layer located on the backlight surface of the photoelectric conversion unit; Electrodes, including a first electrode electrically contacting the first transparent conductive layer and a second electrode electrically contacting the second transparent conductive layer; The second transparent conductive layer includes a second optical advantage layer and a second electrode contact layer stacked sequentially on the backlight surface of the photoelectric conversion unit, the thickness of the second electrode contact layer is greater than or equal to 15 nm, and the mobility of the second electrode contact layer is less than the mobility of the second optical advantage layer.

2. The solar cell according to claim 1, characterized in that The thickness of the second transparent conductive layer is 80nm-120nm, the thickness of the second optically advantageous layer is 30nm-100nm, and the thickness of the second electrode contact layer is 15nm-50nm.

3. The solar cell according to claim 1, characterized in that The ratio of the mobility of the second electrode contact layer to the mobility of the second optically advantageous layer is (0.7-0.9):1; and / or, The mobility of the second optically advantageous layer is 35 cm 2 / V·s~100cm 2 / V·s, the mobility of the second electrode contact layer is 25cm 2 / V·s~90cm 2 / V·s.

4. The solar cell according to claim 1, characterized in that The carrier concentration of the second electrode contact layer is greater than the carrier concentration of the second optically advantageous layer.

5. The solar cell according to claim 4, characterized in that: The carrier concentration of the second electrode contact layer is 2.0E20 / cm 3 ~4.0E20 / cm 3 The carrier concentration of the second optically advantageous layer is 0.2E20 / cm 3 ~2.0E20 / cm 3 .

6. The solar cell according to claim 1, characterized in that The transparent conductive layer is any one of an ITO layer, an IWO layer, an IMO layer, an AZO layer, and a GZO layer.

7. The solar cell according to claim 1, characterized in that The first transparent conductive layer includes a first optically advantageous layer and a first electrode contact layer sequentially stacked on the light receiving surface of the photoelectric conversion unit.

8. The solar cell according to claim 7, characterized in that: The thickness of the first electrode contact layer is greater than or equal to 15 nm, and the mobility of the first electrode contact layer is less than the mobility of the first optically advantageous layer; and / or, The carrier concentration of the first electrode contact layer is greater than the carrier concentration of the first optically advantageous layer.

9. The solar cell according to claim 7, characterized in that: The thickness of the first transparent conductive layer is 80nm to 120nm, the thickness of the first optically advantageous layer is 30nm to 100nm, and the thickness of the first electrode contact layer is 15nm to 50nm; and / or, The ratio of the mobility of the first electrode contact layer to the mobility of the first optically advantageous layer is (0.7-0.9):1; and / or, The mobility of the first optically advantageous layer is 35 cm 2 / V·s~100cm 2 / V·s, the mobility of the first electrode contact layer is 25cm 2 / V·s~90cm 2 / V·s; and / or, The carrier concentration of the first electrode contact layer is 2.0E20 / cm 3 ~4.0E20 / cm 3 The carrier concentration of the first optically advantageous layer is 0.2E20 / cm 3 ~2.0E20 / cm 3 .

10. The solar cell according to claim 1, characterized in that: The solar cell is a heterojunction cell, and the photoelectric conversion unit comprises: A substrate, comprising a first surface and a second surface arranged opposite to each other, wherein the substrate is N-type doped or P-type doped; A first intrinsic layer, located on a first surface of the substrate, wherein the first intrinsic layer is an intrinsic amorphous silicon layer and / or an intrinsic microcrystalline silicon layer; A first doped layer, located on the first intrinsic layer, wherein the first doped layer is an amorphous silicon layer and / or a microcrystalline silicon layer, and the doping type is the same as the doping type of the substrate; A second intrinsic layer, located on the second surface of the substrate, wherein the second intrinsic layer is an intrinsic amorphous silicon layer and / or an intrinsic microcrystalline silicon layer; The second doped layer is located on the second intrinsic layer. The second doped layer is an amorphous silicon layer and / or a microcrystalline silicon layer. The doping type of the second doped layer is opposite to that of the substrate.

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