TCO thin film and heterojunction solar cell

Abstract

The present disclosure relates to the technical field of crystalline silicon solar cells. Disclosed are a TCO thin film and a heterojunction solar cell. The TCO thin film comprises a multilayer film structure, wherein the multilayer film structure comprises a conductive oxide layer undoped with a hydrocarbon and a conductive oxide layer doped with a hydrocarbon, which layers are alternately stacked.

Description

TCO thin films and heterojunction solar cells

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority benefit of Chinese patent application No. 202321864362.6 filed on July 14, 2023, and incorporates the entirety of the application into this document. Technical Field

[0003] The present disclosure relates to the technical field of crystalline silicon solar cells, and in particular to a TCO thin film and a heterojunction solar cell. Background Art

[0004] Crystalline silicon heterojunction solar cells (HJT) are made by depositing amorphous silicon thin films on crystalline silicon. They combine the advantages of crystalline silicon cells and thin-film cells, and have the advantages of high conversion efficiency, low process temperature, high stability, low attenuation rate, and double-sided power generation. They are an important direction for the future development of crystalline silicon cells.

[0005] The typical structure of an HJT is to use an N-type monocrystalline silicon wafer as the substrate light absorption region. On the front of the monocrystalline silicon wafer, an intrinsic amorphous silicon layer (ia-Si:H) and a doped N-type amorphous silicon layer (Na-Si:H) are sequentially deposited to form a pn heterojunction with the silicon substrate. On the back of the monocrystalline silicon wafer, ia-Si:H and a doped P-type amorphous silicon layer (Pa-Si:H) are sequentially deposited to form a back surface field. Transparent conductive oxide (TCO) films are then deposited on the surfaces of the amorphous silicon layers on both sides, and finally, metal electrodes are formed on the top layers on both sides by screen printing. The TCO film can enhance the charge transport capability, effectively solving the problem of the amorphous silicon layer presenting a long-range disordered structure as a whole and the low carrier mobility within the layer, which results in the battery current not being fully collected by the metal electrodes.

[0006] HJT requires extremely high optical transmittance of the front-side TCO film in the 300-1100nm band, coupled with high carrier mobility. This results in high long-wavelength transmittance, reducing the battery's electrical and optical losses and improving the battery's short-circuit current density and fill factor. Early TCO film materials primarily consisted of single-layer ITO (tin-doped indium oxide), ICO (cerium-doped indium oxide), and IWO (tungsten-doped indium oxide). Coating methods primarily used PVD equipment under high-purity argon and high-purity oxygen conditions, resulting in low transmittance, high sheet resistance, and work function mismatch with the amorphous silicon layer and metal electrodes. Existing technologies include adding hydrogen and water vapor during the TCO film coating process, as well as improved methods using multiple TCO layers. For example, doping ITO with hydrogen to improve carrier mobility has been shown to be ineffective, and the resulting TCO film still suffers from low transmittance in the 300-1100nm band.

[0007] Therefore, there is an urgent need to provide an improved TCO film with higher light transmittance and carrier mobility, which is of great significance for improving the performance of HJT.

[0008] Summary of the Invention

[0009] The present disclosure addresses the problems of low light transmittance in the 300-1100nm wavelength range and need to improve carrier mobility of TCO films in existing crystalline silicon heterojunction solar cells, and provides a TCO film and a heterojunction solar cell.

[0010] To achieve the above objectives, the first aspect of the present disclosure provides a TCO thin film, which includes a multilayer film structure; wherein the multilayer film structure includes alternately stacked undoped carbon-hydrogen transparent conductive oxide layers and carbon-hydrogen doped transparent conductive oxide layers.

[0011] Preferably, the single layer thickness of the carbon-hydrogen doped transparent conductive oxide layer is 20-80 nm.

[0012] Preferably, the single layer thickness of the carbon-hydrogen-undoped transparent conductive oxide layer is 3-20 nm.

[0013] Preferably, the ratio of the single layer thickness of the undoped carbon-hydrogen transparent conductive oxide layer to the single layer thickness of the carbon-hydrogen doped transparent conductive oxide layer is 1:(1-4).

[0014] Preferably, the total thickness of the multilayer film structure is 80-120 nm.

[0015] Preferably, the total number of layers of the multilayer film structure is 2-10 layers.

[0016] Preferably, the undoped carbon-hydrogen transparent conductive oxide layer is selected from an ITO film, an AZO film, an ICO film or an IWO film.

[0017] Preferably, the carbon-hydrogen doped transparent conductive oxide layer is selected from a carbon-hydrogen doped ITO film, a carbon-hydrogen doped AZO film, a carbon-hydrogen doped ICO film or a carbon-hydrogen doped IWO film.

[0018] Preferably, in the carbon-hydrogen doped transparent conductive oxide layer, the C content is 0.1-1.5 wt %, and the H content is 0.02-0.15 wt %.

[0019] Preferably, in a light transmittance test, the average light transmittance of the TCO film in the 300-1100 nm wavelength range is 90-92.5%.

[0020] Preferably, the refractive index of the TCO film is 1.5-1.85.

[0021] Preferably, the carrier mobility of the TCO film is ≥40 cm 2 / (V·s).

[0022] A second aspect of the present disclosure provides a heterojunction solar cell, comprising: an N-type single-crystal silicon wafer substrate; a first intrinsic amorphous silicon layer, an N-type amorphous silicon layer, a first conductive layer, and a first metal electrode disposed in sequence from near to far on a front surface of the substrate; and a second intrinsic amorphous silicon layer, a P-type amorphous silicon layer, a second conductive layer, and a second metal electrode disposed in sequence from near to far on a back surface of the substrate.

[0023] Wherein, the first conductive layer and the second conductive layer are each independently the TCO film described in the first aspect.

[0024] Preferably, the photoelectric conversion efficiency of the heterojunction solar cell is ≥24.4%.

[0025] Preferably, the short-circuit current density of the heterojunction solar cell is ≥39 mA / cm 2 .

[0026] Through the above technical solution, the beneficial technical effects achieved by the present disclosure are as follows:

[0027] 1) The TCO film provided by the present disclosure has a multilayer film structure comprising alternating layers of undoped carbon-hydrogen transparent conductive oxide layers and carbon-hydrogen doped transparent conductive oxide layers. For the carbon-hydrogen doped transparent conductive oxide layers, hydrogen doping improves the passivation of amorphous silicon and increases carrier mobility, while the presence of carbon doping can regulate the refractive index of the doped layer. This multilayer structure, comprising alternating layers of undoped carbon-hydrogen transparent conductive oxide layers and carbon-hydrogen doped transparent conductive oxide layers, can effectively increase the average light transmittance of the TCO film in the 300-1100nm wavelength range to over 90% (up to 92.5%), reducing light loss and enhancing sunlight absorption. It can also increase carrier mobility to 40cm / s. 2 / (V·s) or above, better balance between light loss and electrical loss;

[0028] 2) The TCO film provided by the present disclosure can be prepared without the need for additional targets of different materials and coating equipment, which can reduce the impact of equipment failure risks on preparation. Compared with TCO films without hydrocarbon doping, the overall amount of TCO can be reduced, effectively reducing costs and improving yields.

[0029] 3) Compared with heterojunction solar cell products using conventional TCO thin films, the heterojunction solar cell provided by the present disclosure has higher photoelectric conversion efficiency and higher short-circuit current density, and its performance is significantly improved. It can be widely used in photovoltaic power stations, solar cars and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1 is a schematic structural diagram of a TCO film according to an embodiment of the present disclosure.

[0031] FIG2 is a schematic structural diagram of a TCO film according to another embodiment of the present disclosure.

[0032] FIG3 is a schematic structural diagram of a heterojunction solar cell provided by the present disclosure.

[0033] Description of Reference Numerals

[0034] a. Conductive oxide layer without carbon-hydrogen doping b. Conductive oxide layer with carbon-hydrogen doping

[0035] 1. N-type single crystal silicon wafer substrate 2. First intrinsic amorphous silicon layer 3. N-type amorphous silicon layer

[0036] 4. First conductive layer 5, first metal electrode 6, second intrinsic amorphous silicon layer

[0037] 7. P-type amorphous silicon layer 8. Second conductive layer 9. Second metal electrode DETAILED DESCRIPTION

[0038] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0039] A first aspect of the present disclosure provides a TCO thin film, as shown in FIG1 and FIG2 , wherein the TCO thin film comprises a multilayer film structure; wherein the multilayer film structure comprises alternately stacked undoped carbon-hydrogen transparent conductive oxide layers a and carbon-hydrogen doped transparent conductive oxide layers b.

[0040] In this disclosure, TCO thin films refer to transparent conductive oxide (TCO) thin films, primarily comprising oxides of In, Sb, Zn, or Cd, and their composite multi-element oxide thin film materials. These thin films exhibit high transmittance in the visible spectrum, a wide bandgap, and low resistivity, and are widely used in solar cell applications. The inventors of this disclosure have discovered that designing TCO thin films with a multilayer structure comprising alternating layers of undoped and doped TCO layers can improve light transmittance, particularly in the 300-1100 nm wavelength range. This structure can also enhance carrier mobility, leading to improved solar cell performance.

[0041] In the specific embodiments provided herein, the single-layer thickness of the undoped carbon-hydrogen transparent conductive oxide layer a is preferably 3-20 nm, more preferably 15-20 nm. A single-layer thickness of the undoped carbon-hydrogen transparent conductive oxide layer a falling within this range facilitates production process control and can reduce TCO usage by 10-20% compared to undoped carbon-hydrogen TCO films, effectively reducing costs and improving yield.

[0042] In the specific embodiments provided herein, the monolayer thickness of the carbon-hydrogen-doped transparent conductive oxide layer b is preferably 20-80 nm, more preferably 20-40 nm. When the monolayer thickness of the carbon-hydrogen-doped transparent conductive oxide layer b falls within the above range, the difference between the monolayer thickness of the carbon-hydrogen-doped transparent conductive oxide b and the monolayer thickness of the undoped carbon-hydrogen-doped transparent conductive oxide a is small, thereby minimizing the impact on the light transmittance of the TCO film.

[0043] In the specific embodiment provided in the present disclosure, preferably, the ratio of the single layer thickness of the undoped carbon-hydrogen transparent conductive oxide layer a to the single layer thickness of the carbon-hydrogen doped transparent conductive oxide layer b is 1:(1-4), which can enable the TCO film to obtain higher light transmittance and carrier mobility.

[0044] In the specific embodiment provided by the present disclosure, preferably, the total thickness of the multilayer film structure is 80-120 nm, more preferably 90-105 nm. The total thickness of the multilayer film structure falling within the above range can make the TCO film have a higher light transmittance.

[0045] In the specific embodiments provided herein, preferably, the total number of layers of the multilayer film structure is 2-10, more preferably 4-6. When the total number of layers of the multilayer film structure falls within the above range, the TCO film can have a higher photoelectric conversion efficiency while avoiding the increased production difficulty caused by an excessive number of film layers.

[0046] In the present disclosure, when the single-layer thickness of the undoped carbon-hydrogen transparent conductive oxide layer a, the single-layer thickness of the carbon-hydrogen doped transparent conductive oxide layer b, the total thickness of the multilayer film structure, and the total number of layers meet the above-defined ranges, the TCO film can have a higher light transmittance and a higher carrier mobility.

[0047] In a specific embodiment provided by the present disclosure, as shown in FIG1 , the TCO film can have an undoped carbon-hydrogen transparent conductive oxide layer a as a starting layer, a carbon-hydrogen-doped transparent conductive oxide layer b stacked on the surface of the starting layer, and then an undoped carbon-hydrogen transparent conductive oxide layer a stacked on the surface of the carbon-hydrogen-doped transparent conductive oxide layer b, and so on, alternately stacked, until the outermost termination layer; in addition, as shown in FIG2 , the TCO film can also have a carbon-hydrogen-doped transparent conductive oxide layer b as a starting layer, an undoped carbon-hydrogen transparent conductive oxide layer a stacked on the surface of the starting layer, and then a carbon-hydrogen-doped transparent conductive oxide layer b stacked on the surface of the undoped carbon-hydrogen transparent conductive oxide layer a, and so on, alternately stacked, until the outermost termination layer. In the present disclosure, in the multi-layer film structure of the TCO film, the outermost termination layer can be either the undoped carbon-hydrogen transparent conductive oxide layer a or the carbon-hydrogen-doped transparent conductive oxide layer b.

[0048] In the specific embodiments provided in the present disclosure, preferably, the undoped carbon-hydrogen transparent conductive oxide layer a can be selected from an ITO film, an AZO film, an ICO film or an IWO film.

[0049] In the specific embodiments provided in the present disclosure, preferably, the carbon-hydrogen doped transparent conductive oxide layer can be selected from a carbon-hydrogen doped ITO film, a carbon-hydrogen doped AZO film, a carbon-hydrogen doped ICO film or a carbon-hydrogen doped IWO film.

[0050] In this disclosure, ITO refers to tin-doped indium oxide, AZO refers to aluminum-doped zinc oxide, ICO refers to cerium-doped indium oxide, and IWO refers to tungsten-doped indium oxide. The ITO film, AZO film, ICO film, or IWO film are all understood according to definitions commonly known in the art.

[0051] In the present disclosure, the carbon-hydrogen-doped transparent conductive oxide layer b refers to a heavily doped semiconductor transparent oxide layer formed by replacing some of the oxygen atoms in the crystal lattice of the transparent conductive oxide contained in a conventional transparent conductive oxide layer (e.g., an ITO film, an AZO film, an ICO film, or an IWO film) with carbon atoms and hydrogen atoms. Preferably, the carbon content of the carbon-hydrogen-doped transparent conductive oxide layer b is 0.1-1.5 wt%, and the hydrogen content is 0.02-0.15 wt%.

[0052] In the present disclosure, the C and H doping amounts in the carbon-hydrogen doped transparent conductive oxide b can be measured by ICP-MS (inductively coupled plasma mass spectrometry).

[0053] In a specific embodiment provided herein, the carbon-hydrogen doped transparent conductive oxide layer b can be deposited on a substrate using a target in the presence of a doping gas and oxygen. The doping gas can be selected from at least one of methane, ethylene, and acetylene; the target can be selected from ITO, AZO, ICO, or IWO; and the coating can be performed using conventional deposition coating processes and parameters in the art, including but not limited to sputtering, evaporation, multi-arc ion plating, and RPD.

[0054] In the specific embodiments provided herein, in the multilayer structure of the TCO thin film, each undoped carbon-hydrogen transparent conductive oxide layer (a) can be made of the same material or different materials; each doped carbon-hydrogen transparent conductive oxide layer (b) can be made of the same material or different materials, and this disclosure does not specifically limit this. For ease of operation and cost considerations, it is preferred that each undoped carbon-hydrogen transparent conductive oxide layer (a) and each doped carbon-hydrogen transparent conductive oxide layer (b) in the TCO thin film be made of the same material.

[0055] In the specific embodiments provided in the present disclosure, preferably, in a light transmittance test, the average light transmittance of the TCO film in the 300-1100 nm band is greater than 90%, and more preferably 90-92.5%.

[0056] In a specific embodiment provided in the present disclosure, preferably, the refractive index of the TCO film is 1.5-1.8.

[0057] In the present disclosure, light transmittance is measured according to the method specified in GB / T 30983-2014 (Test method for optical properties of photovoltaic glass); and refractive index is measured according to the method specified in GB / T 26598-2011 (Specification for transparent conductive films for optical instruments).

[0058] A second aspect of the present disclosure provides a heterojunction solar cell, as shown in FIG3 , comprising: an N-type single crystal silicon wafer substrate 1, a first intrinsic amorphous silicon layer 2, an N-type amorphous silicon layer 3, a first conductive layer 4, and a first metal electrode 5 arranged in sequence from near to far on the front side of the substrate 1, and a second intrinsic amorphous silicon layer 6, a P-type amorphous silicon layer 7, a second conductive layer 8, and a second metal electrode 9 arranged in sequence from near to far on the back side of the substrate 1; wherein the first conductive layer 4 and the second conductive layer 8 are each independently the TCO film described in the first aspect above.

[0059] In the specific embodiment provided in the present disclosure, there is no special limitation on the specification parameters and materials of the N-type single crystal silicon wafer substrate 1, the first intrinsic amorphous silicon layer 2, the second intrinsic amorphous silicon layer 6, the N-type amorphous silicon layer 3, the P-type amorphous silicon layer 7, the first metal electrode 5 and the second metal electrode 9, and conventional selections in the field can be adopted.

[0060] The heterojunction solar cell provided by the present disclosure has higher photoelectric conversion efficiency and higher short-circuit current density compared to heterojunction solar cell products using conventional TCO films.

[0061] The present disclosure will be described in detail below through examples.

[0062] Example 1

[0063] Preparation of TCO thin film:

[0064] A clean glass sheet is placed in a coating machine, and a transparent ITO film not doped with hydrocarbons is coated on the surface of the glass sheet by magnetron sputtering (the mass ratio of In2O3 and SnO2 in the ITO target is 97:3; the gas introduced is a mixture of high-purity argon and high-purity oxygen; the coating temperature is 150°C); then, a transparent ITO film doped with hydrocarbons is coated on the surface of the above transparent ITO film not doped with hydrocarbons (the mass ratio of In2O3 and SnO2 in the ITO target is 97:3; the gas introduced is a mixture of high-purity argon, high-purity oxygen and high-purity acetylene; the coating temperature is 150°C); then, the above conditions are repeatedly switched for coating, and the transparent ITO film not doped with hydrocarbons and the transparent ITO film doped with hydrocarbons are alternately deposited and superimposed to obtain a TCO film (denoted as P1);

[0065] The total thickness of P1 is 102nm, among which the number of layers of the undoped carbon-hydrogen transparent ITO film is 3, and the thickness of a single layer is 20nm; the number of layers of the carbon-hydrogen doped transparent ITO film (wherein the C content is 0.3wt% and the H content is 0.05wt%) is 2, and the thickness of a single layer is 21nm; the outermost layer of P1 is the undoped carbon-hydrogen transparent ITO film.

[0066] Preparation of heterojunction solar cells:

[0067] 1) Cleaning the N-type single crystal silicon wafer and making the clean N-type single crystal silicon wafer into a velvet surface;

[0068] 2) using PECVD to sequentially deposit a first intrinsic amorphous silicon layer and an N-type amorphous silicon layer on the front side of the silicon wafer; and sequentially depositing a second intrinsic amorphous silicon layer and a P-type amorphous silicon layer on the back side of the silicon wafer;

[0069] 3) placing the silicon wafer after the PECVD coating in a magnetron sputtering coating device, and coating the TCO film P1 on the surface of the N-type amorphous silicon layer and the P-type amorphous silicon layer of the silicon wafer respectively by magnetron sputtering;

[0070] 4) placing the coated silicon wafer obtained in step 3) in an annealing furnace for annealing;

[0071] 5) The annealed silicon wafer is placed in a screen printing device, and silver paste is printed. After printing, the paste is cured to obtain a heterojunction solar cell (denoted as B1).

[0072] Example 2

[0073] Preparation of TCO thin film:

[0074] According to the method of Example 1, except that the number of layers and the thickness of the single layer of the undoped carbon-hydrogen transparent ITO film and the carbon-hydrogen doped transparent ITO film are changed, the other conditions are the same as those of Example 1, and a TCO film (denoted as P2) is obtained;

[0075] The total thickness of P2 is 102nm, among which the number of layers of the transparent ITO film not doped with hydrocarbons is 2, and the thickness of a single layer is 20nm; the number of layers of the transparent ITO film doped with hydrocarbons (wherein the C content is 0.3wt% and the H content is 0.05wt%) is 1, and the thickness of a single layer is 62nm; the outermost layer of P2 is the transparent ITO film not doped with hydrocarbons.

[0076] Preparation of heterojunction solar cells:

[0077] A heterojunction solar cell (denoted as B2) was obtained by following the method of Example 1, except that the TCO film P1 was replaced by the TCO film P2. Other conditions were the same as those of Example 1.

[0078] Example 3

[0079] Preparation of TCO thin film:

[0080] According to the method of Example 1, except that the number of layers and the thickness of the single layer of the undoped carbon-hydrogen transparent ITO film and the carbon-hydrogen doped transparent ITO film are changed, the other conditions are the same as those of Example 1, and a TCO film (denoted as P3) is obtained;

[0081] The total thickness of P3 is 102nm, among which the number of layers of the undoped carbon-hydrogen transparent ITO film is 2, and the thickness of a single layer is 15nm; the number of layers of the carbon-hydrogen doped transparent ITO film (wherein the C content is 0.3wt% and the H content is 0.05wt%) is 1, and the thickness of a single layer is 72nm; the outermost layer of P3 is the undoped carbon-hydrogen transparent ITO film.

[0082] Preparation of heterojunction solar cells:

[0083] The method of Example 1 is followed, except that the TCO film P1 is replaced by the above-mentioned TCO film P3. Other conditions are the same as those of Example 1, to obtain a heterojunction solar cell (denoted as B3).

[0084] Comparative Example 1

[0085] Preparation of TCO thin film:

[0086] The method of Example 1 was followed, except that the operation of coating the transparent ITO film doped with hydrocarbons was replaced by the operation of coating the transparent ITO film not doped with hydrocarbons. Other operations and conditions were the same as those of Example 1, to obtain a TCO film (denoted as DP1).

[0087] All the film layers contained in DP1 are transparent ITO films not doped with hydrocarbons, with a total thickness of 102 nm.

[0088] Preparation of heterojunction solar cells:

[0089] The method of Example 1 is followed, except that the TCO film P1 is replaced by the above-mentioned TCO film DP1. Other conditions are the same as those of Example 1, to obtain a heterojunction solar cell (denoted as DB1).

[0090] Test Case

[0091] The above TCO films P1, P2, P3 and DP1 were respectively subjected to light transmittance test, refractive index test and carrier mobility test, and the results are shown in Table 1.

[0092] Light transmittance test: At room temperature, with blank glass as the control, the average light transmittance of the TCO film layer was measured using a UV-visible spectrophotometer.

[0093] Refractive index test: At room temperature, the refractive index of the TCO film was measured using an ellipsometer with blank glass as a control.

[0094] Carrier mobility test: At room temperature, the carrier mobility of the TCO film is measured using a Hall effect tester.

[0095] The IV curve tests of the above heterojunction solar cells B1, B2, B3 and DB1 were performed using the steady-state light source method under STC conditions, and the photoelectric conversion efficiency and short-circuit current density of the cells were calculated. The results are shown in Table 2.

[0096] Table 1

[0097] Table 2

[0098] As can be seen from Tables 1 and 2, the TCO film provided by the present disclosure having a multilayer film structure with an undoped carbon-hydrogen conductive oxide layer and a carbon-hydrogen doped conductive oxide layer alternately stacked has a higher light transmittance than conventional TCO films. The average light transmittance in the 300-1100 nm band can reach more than 90%, and the carrier mobility reaches 40 cm 2 / (V·s) or above, which can better balance the light loss and electrical loss, and improve the photoelectric conversion efficiency and short-circuit current density of heterojunction solar cells.

[0099] The preferred embodiments of the present disclosure are described in detail above, but the present disclosure is not limited thereto. Within the technical concept of the present disclosure, various simple variations of the technical solution of the present disclosure may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed by the present disclosure and fall within the scope of protection of the present disclosure.

Claims

1. A TCO film, wherein: The TCO film comprises a multi-layer film structure; wherein the multi-layer film structure comprises alternately stacked transparent conductive oxide layers not doped with carbon and hydrogen and transparent conductive oxide layers doped with carbon and hydrogen.

2. The TCO film according to claim 1, wherein: The single layer thickness of the undoped carbon-hydrogen transparent conductive oxide layer is 3-20 nm.

3. The TCO film according to claim 1 or 2, wherein: The single layer thickness of the carbon-hydrogen doped transparent conductive oxide layer is 20-80 nm.

4. The TCO film according to any one of claims 1 to 3, wherein: The ratio of the single layer thickness of the undoped carbon-hydrogen transparent conductive oxide layer to the single layer thickness of the doped carbon-hydrogen transparent conductive oxide layer is 1:(1-4).

5. The TCO film according to any one of claims 1 to 4, wherein: The total thickness of the multilayer film structure is 80-120 nm.

6. The TCO film according to any one of claims 1 to 5, wherein: The total number of layers of the multilayer film structure is 2-10 layers.

7. The TCO film according to any one of claims 1 to 6, wherein: The undoped carbon-hydrogen transparent conductive oxide layer is selected from an ITO film, an AZO film, an ICO film or an IWO film.

8. The TCO film according to any one of claims 1 to 7, wherein: The carbon-hydrogen doped transparent conductive oxide layer is selected from a carbon-hydrogen doped ITO film, a carbon-hydrogen doped AZO film, a carbon-hydrogen doped ICO film or a carbon-hydrogen doped IWO film.

9. The TCO film according to any one of claims 1 to 8, wherein: In the carbon-hydrogen doped transparent conductive oxide layer, the C content is 0.1-1.5 wt %, and the H content is 0.02-0.15 wt %.

10. The TCO thin film according to any one of claims 1 to 9, wherein: In a light transmittance test, the average light transmittance of the TCO film in the 300-1100 nm band is 90-92.5%.

11. The TCO thin film according to any one of claims 1 to 10, wherein: The refractive index of the TCO film is 1.5-1.

85.

12. The TCO thin film according to any one of claims 1 to 11, wherein: The carrier mobility of the TCO film is ≥40cm 2 / (V·s).

13. A heterojunction solar cell, wherein: include: N-type single crystal silicon wafer substrate, A first intrinsic amorphous silicon layer, an N-type amorphous silicon layer, a first conductive layer and a first metal electrode are sequentially arranged on the front side of the substrate from near to far, and a second intrinsic amorphous silicon layer, a P-type amorphous silicon layer, a second conductive layer and a second metal electrode are sequentially arranged on the back side of the substrate from near to far; Wherein, the first conductive layer and the second conductive layer are each independently a TCO as described in any one of claims 1 to 12. film.

14. The heterojunction solar cell according to claim 13, wherein: The photoelectric conversion efficiency of the heterojunction solar cell is ≥24.4%.

15. The heterojunction solar cell according to claim 13 or 14, wherein: The short-circuit current density of the heterojunction solar cell is ≥39 mA / cm 2 .

Images