Hydrogen passivation composite film for solar cell, solar cell, assembly of solar cell and power station

Abstract

The utility model relates to the technical field of solar cells, and discloses a hydrogen passivation composite film for a solar cell, the solar cell, an assembly of the solar cell and a power station. The hydrogen passivation composite film for the solar cell comprises a silicon wafer and a silicon nitride film arranged on the surface of the silicon wafer, a first TiOx layer is arranged on the surface of the silicon nitride film, and the molar ratio of titanium atoms to oxygen atoms in the first TiOx layer is 0.1-0.5; a selective second TiOx layer is also arranged in a local area of the surface of the first TiOx layer, and the molar ratio of titanium atoms to oxygen atoms in the second TiOx layer is 1.5-3. According to the hydrogen passivation composite film for the solar cell, the first TiOx layer and the selective second TiOx layer are sequentially arranged on the silicon nitride film, so that the problem that hydrogen in the silicon nitride film overflows outwards can be solved, the function of preventing the hydrogen from overflowing is achieved, and the chemical passivation effect of a silicon wafer of the solar cell is improved; the method has the advantages of simple process, low cost, good blocking effect on metal slurry, reduction of the thickness of the polycrystalline silicon layer, reduction of parasitic absorption, and improvement of the double-sided rate, the open-circuit voltage and the cell efficiency.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of solar cell, concretely relates to a hydrogen passivation composite film for solar cell, solar cell and its assembly and power station. BACKGROUND

[0002] For a solar cell (such as a TOPCon cell), a silicon nitride film (SiNx film) not only has a light antireflection effect, but also is a main source place of [H] (hydrogen) when hydrogen passivation of crystalline silicon is performed. However, some research reports show that, during heat treatment (for example, sintering), [H] in the SiNx film has a kinetic advantage of overflowing to the outside of the cell, which causes a large amount of [H] to be unable to reach the crystalline silicon, which is very unfavorable for chemical passivation of the crystalline silicon, and also reduces the performance of the cell, such as open-circuit voltage and cell efficiency.

[0003] Currently, in the industry, to prevent hydrogen overflow of the SiNx film, the content of [H] in the SiNx film is generally adjusted by adjusting the proportion of reactants during preparation of the SiNx film, so as to improve the defect that the chemical passivation effect of the crystalline silicon is poor due to excessive hydrogen overflow of the SiNx film. For example, the hydrogen content adjusting structure of the back surface of the crystalline silicon substrate shown in a film layer structure for a crystalline silicon solar cell provided in CN218548445U includes a hydrogen-rich layer (such as a silicon nitride film) and a hydrogen barrier layer (such as an intrinsic polysilicon layer) arranged on the back surface and the front surface of the hydrogen-rich layer, so as to improve the passivation performance by means of the hydrogen content adjusting structure.

[0004] However, the effect of the hydrogen barrier layer (such as the intrinsic polysilicon layer) of the prior art such as CN218548445U on preventing hydrogen overflow of the SiNx film still needs to be improved; and if the effect of preventing hydrogen overflow is to be improved, the thickness of the hydrogen barrier layer such as the intrinsic polysilicon layer has to be increased, but the thicker hydrogen barrier layer such as the intrinsic polysilicon layer will also cause serious parasitic absorption, which reduces the bifacial rate and the cell efficiency; and the hydrogen barrier layer such as the intrinsic polysilicon layer is also difficult to have a good blocking effect on the metal paste used for preparing a metal electrode subsequently. CONTENT OF THE UTILITY MODEL

[0005] The utility model aims at overcoming the defects of the prior art, and provides a hydrogen passivation composite film for a solar cell, a solar cell, an assembly thereof, and a power station.

[0006] Based on this, the utility model discloses a hydrogen passivation composite film for a solar cell,

[0007] The utility model discloses a hydrogen passivation composite film for a solar cell,

[0008] The surface of the silicon nitride film is provided with a first TiOx layer, and the molar ratio of titanium atoms to oxygen atoms in the first TiOx layer is 0.1-0.5.

[0009] The local area of the surface of the first TiOx layer is further provided with a selective second TiOx layer, and the molar ratio of titanium atoms to oxygen atoms in the second TiOx layer is 1.5-3.

[0010] Preferably, the molar ratio of titanium atoms to oxygen atoms in the first TiOx layer is 0.3, and the molar ratio of titanium atoms to oxygen atoms in the second TiOx layer is 2.

[0011] Preferably, the front surface and the back surface of the silicon wafer are both provided with a silicon nitride film; the front surface of the silicon nitride film on the front surface of the silicon wafer is sequentially provided with the first TiOx layer and the selective second TiOx layer, and / or the back surface of the silicon nitride film on the back surface of the silicon wafer is sequentially provided with the first TiOx layer and the selective second TiOx layer.

[0012] Further preferably, a passivation contact structure is further provided between the silicon wafer and the silicon nitride film on the back surface.

[0013] More preferably, the passivation contact structure comprises a tunneling silicon oxide provided on the back surface of the silicon wafer and a doped polysilicon layer located between the tunneling silicon oxide and the silicon nitride film on the back surface.

[0014] Further preferably, an aluminum oxide film is further provided between the silicon wafer and the silicon nitride film on the front surface.

[0015] Preferably, the local area corresponds to a metal electrode contact area.

[0016] The utility model discloses still a kind of solar cells, it includes the hydrogen passivation composite film for solar cell of the utility model content above-mentioned described above;The front surface and the back surface of the silicon wafer are both provided with metal electrode, and the one end of the metal electrode on the front surface of the silicon wafer is in ohmic contact with the silicon wafer, and the one end of the metal electrode on the back surface of the silicon wafer is in ohmic contact with the doped polysilicon layer on the back surface of the silicon wafer.

[0017] The utility model discloses still a kind of solar cell module, it includes the solar cell of the utility model content above-mentioned described above.

[0018] The utility model discloses still a kind of photovoltaic power station, it includes the solar cell module of the utility model content above-mentioned described above.

[0019] Compared with prior art, the utility model at least includes following beneficial effects:

[0020] The utility model discloses a hydrogen passivation composite film for solar cell, which sequentially sets a first TiOx layer (the molar ratio of titanium atom to oxygen atom is 0.1-0.5) and a selective second TiOx layer (the molar ratio of titanium atom to oxygen atom is 1.5-3) on a silicon nitride film (SiNx film) of a solar cell (such as a TOPCon cell), to solve the problem of hydrogen overflow in the silicon nitride film, realize the role of blocking hydrogen overflow, and improve the chemical passivation effect of a silicon wafer (such as a crystalline silicon) of the solar cell. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is the cross section structure schematic drawing of the silicon wafer after step 2 in the manufacturing method of a hydrogen passivation composite film for solar cell of embodiment 1.

[0022] Figure 2 It is the cross section structure schematic drawing of the silicon wafer after step 32 in the manufacturing method of a hydrogen passivation composite film for solar cell of embodiment 1.

[0023] Figure 3 It is the cross section structure schematic drawing of the silicon wafer after step 33 in the manufacturing method of a hydrogen passivation composite film for solar cell of embodiment 1.

[0024] Figure 4 It is the cross section structure schematic drawing of a solar cell of embodiment 1.

[0025] Figure 5 It is the cross section structure schematic drawing of the silicon wafer after step 2 in the manufacturing method of a hydrogen passivation composite film for solar cell of embodiment 2.

[0026] Figure 6 It is the cross section structure schematic drawing of the silicon wafer after step 32 in the manufacturing method of a hydrogen passivation composite film for solar cell of embodiment 2.

[0027] Figure 7 It is the cross section structure schematic drawing of the silicon wafer after step 33 in the manufacturing method of a hydrogen passivation composite film for solar cell of embodiment 2.

[0028] Figure 8 It is the cross section structure schematic drawing of a solar cell of embodiment 2.

[0029] Brief Description of Drawings: silicon wafer 1; tunneling silicon oxide 2; doped polysilicon layer 3; aluminum oxide film 4; silicon nitride film 5; first TiOx layer 6; second TiOx layer 7; metal electrode 8. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easily understood, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Embodiment 1

[0032] The hydrogen passivation composite film for solar cells of the present embodiment, as shown in Figure 4 and Figure 8 includes a silicon wafer 1 and a silicon nitride film 5 provided on the surface of the silicon wafer 1; the surface of the silicon nitride film 5 is provided with a first TiOx layer 6, and the molar ratio of titanium atoms to oxygen atoms in the first TiOx layer 6 is 0.1-0.5 (preferably 0.3); and a selective second TiOx layer 7 is further provided in a partial region of the surface of the first TiOx layer 6, and the molar ratio of titanium atoms to oxygen atoms in the second TiOx layer 7 is 1.5-3 (preferably 2). In practice, the silicon wafer 1 is crystalline silicon for solar cells; and the partial region corresponds to the contact region of the metal electrode.

[0033] It should be noted that the molar ratio content of oxygen atoms in the first TiOx layer 6 is relatively high, which can effectively bind the hydrogen in the SiNx film and effectively prevent hydrogen overflow, thereby improving the chemical passivation effect of the silicon wafer 1 (such as crystalline silicon). This is because: for a strict atomic molar ratio of titanium dioxide (TiO2) structure, there are 6 oxygen atoms around each titanium atom to form a stable octahedral structure. If the molar ratio of titanium atoms to oxygen atoms is less than 0.5, the molar content of oxygen atoms in the crystal structure is more than that of titanium atoms, which causes a part of the outer electron orbitals of the oxygen atoms to be left without bonding, and this part of the electrons can effectively combine with the hydrogen [H] in the SiNx film, thereby preventing hydrogen overflow.

[0034] Moreover, the molar ratio of titanium atoms in the selective second TiOx layer 7 is relatively high, and the content of metallic titanium is relatively high, so the selective second TiOx layer 7 has good conductivity, which can effectively block the metal paste and effectively reduce the thickness of the polysilicon layer, reduce parasitic absorption, improve the bifaciality, and has great application potential in subsequent thin-layer polysilicon cells. At the same time, compared with the existing hydrogen barrier layer such as intrinsic polysilicon layer, the appropriate thickness of the TiOx layer does not reduce the bifaciality of the cell, which helps to improve the efficiency of the solar cell.

[0035] The two increased TiOx layers (i.e. the first TiOx layer 6 and the optional second TiOx layer 7) have the effect of blocking the metal paste used to prepare the metal electrode 8 from continuing to penetrate, and the solar cell with the hydrogen passivation composite film has good application prospects in thin-layer polycrystalline silicon cells, and can further improve the performance (such as open-circuit voltage) and cell efficiency of the solar cell.

[0036] The silicon wafer 1 has a silicon nitride film 5 on the front surface and the back surface. Specifically, the first TiOx layer 6 and the optional second TiOx layer 7 can be sequentially arranged on the front surface of the silicon nitride film 5 on the front surface of the silicon wafer 1; or the first TiOx layer 6 and the optional second TiOx layer 7 can be sequentially arranged on the back surface of the silicon nitride film 5 on the back surface of the silicon wafer 1; or the first TiOx layer 6 and the optional second TiOx layer 7 can be sequentially arranged on the front surface of the silicon nitride film 5 on the front surface of the silicon wafer 1 and on the back surface of the silicon nitride film 5 on the back surface of the silicon wafer 1, so as to further improve the double-sided rate, chemical passivation effect, open-circuit voltage and cell efficiency.

[0037] The silicon wafer 1 and the back surface silicon nitride film 5 further have a passivation contact structure. The passivation contact structure includes a tunneling silicon oxide 2 on the back surface of the silicon wafer 1 and a doped polysilicon layer 3 between the tunneling silicon oxide 2 and the back surface silicon nitride film 5, so as to improve the passivation performance and contact performance of the solar cell and improve the cell efficiency.

[0038] The silicon wafer 1 and the front surface silicon nitride film 5 further have an aluminum oxide film 4, so as to improve the antireflection and passivation effect of the front surface of the silicon wafer 1 to sunlight.

[0039] The method for manufacturing the solar cell hydrogen passivation composite film of the embodiment includes the following steps:

[0040] Step 1: Select a silicon wafer 1 with a silicon nitride film 5 (SiNx film) on the surface.

[0041] In step 1, the silicon wafer 1 is preferably crystalline silicon, such as N-type single crystal silicon or polycrystalline silicon. Referring to Figure 1 , the silicon wafer 1 selected in step 1 is preferably: the front surface of the silicon wafer 1 sequentially has an aluminum oxide film 4 and a silicon nitride film 5, and the back surface of the silicon wafer 1 sequentially has a tunneling silicon oxide 2, a doped polysilicon layer 3 (such as an N++ doped polysilicon layer) and a silicon nitride film 5.

[0042] Step 2: Prepare a first TiOx layer 6 (such as shown in Figure 1 ) on the entire back surface of the silicon nitride film 5 of the silicon wafer 1.

[0043] In step 2, the molar ratio of titanium atoms (Ti) to oxygen atoms (O) in the first TiOx layer 6 is 0.1 to 0.5 (preferably 0.3). The first TiOx layer 6 is preferably prepared by deposition, more preferably by PVD (physical vapor deposition), and the specific deposition steps are as follows:

[0044] Step 21: During the deposition process, the cavity pressure of the loading chamber in the PVD setup is set to 10. -3 ~10 -2 Pa (preferably 10) -3 The target material used for deposition is elemental Ti, and the deposition power is 20,000 to 30,000 W (preferably 20,000 W). The silicon wafer 1 from step 1 is placed into the loading cavity set by PVD, and the cavity is heated to 260 to 300°C (preferably 275°C).

[0045] Step 22: After the cavity temperature stabilizes, the silicon wafer 1 is transferred to the first PVD deposition chamber, and oxygen (O2) at 60-100 sccm (preferably 80 sccm) is introduced. The belt speed of the first deposition chamber is set to 60-80 cm / min (preferably 80 cm / min) to deposit the first TiOx layer 6 on the entire back side of the silicon nitride film 5.

[0046] In step 22, when the O2 flow rate is below 60 sccm, the deposited elemental metal Ti layer cannot be completely oxidized, forming a dead layer and affecting the battery efficiency; when the O2 flow rate is above 100 sccm, the molar ratio of oxygen atoms in the obtained first TiOx layer 6 is too large, which will reduce the overall conductivity of the film.

[0047] In step 22, when the belt speed is below 60 cm / min, the first TiOx layer 6 formed is too thick, which will cause more severe parasitic absorption and affect the bifaciality of the cell; when the belt speed is above 80 cm / min, the first TiOx layer 6 formed is too thin and uneven, and cannot cover the back side of the silicon nitride film 5 of the entire silicon wafer 1, affecting the open circuit voltage and efficiency of the cell.

[0048] Step 3: Prepare a selective second TiOx layer 7 (e.g., on a localized region of the back side of the first TiOx layer 6) Figure 3 As shown in the figure, this local area corresponds to the metal electrode contact area.

[0049] In step 3, the molar ratio of titanium atoms (Ti) to oxygen atoms (O) in the second TiOx layer 7 is 1.5 to 3 (preferably 2). The second TiOx layer 7 is preferably prepared by deposition, and more preferably by PVD (physical vapor deposition). Step 3 includes the following specific steps:

[0050] Step 31, the cavity pressure of the loading cavity of the PVD device during deposition is set to 10 -3 ~10 -2 Pa (such as 10 -3 ), the target material used for deposition is elemental Ti, and the deposition power is 20000-30000W (such as 20000W); the silicon wafer 1 of step 1 is placed in the loading cavity of the PVD device, and the cavity temperature is raised to 260-300℃ (such as 275℃).

[0051] Step 32, after the cavity temperature is stabilized, the silicon wafer 1 is transferred to the plating cavity two of the PVD device, and 10-45sccm (preferably 30sccm) of oxygen (O2) is introduced, the speed of the plating cavity two is set to 100-150cm / min (preferably 120cm / min), so as to deposit a second TiOx layer 7 (as shown in Figure 2 ) on the entire back surface of the first TiOx layer 6.

[0052] In step 32, when the O2 flow is less than 10sccm, the deposited elemental metal Ti layer cannot be oxidized, forming a dead layer that affects the battery efficiency; when the O2 flow is greater than 45sccm, the molar ratio of Ti atoms in the prepared second TiOx layer 7 is too large, and the blocking effect of the second TiOx layer 7 on the metal paste will be weakened.

[0053] In step 32, when the speed of the plating cavity two is less than 100cm / min, the second TiOx layer 7 formed is thicker, which will bring additional parasitic absorption and affect the double-sided rate of the battery; when the speed is higher than 150cm / min, the second TiOx layer 7 formed is too thin and uneven, and cannot cover the entire back surface of the first TiOx layer 6, which affects the open-circuit voltage and efficiency of the battery

[0054] Step 33, the second TiOx layer 7 of the non-metal electrode contact area is removed, while the second TiOx layer 7 of the metal electrode contact area is retained (as shown in Figure 3 ), so as to obtain a selective second TiOx layer 7.

[0055] In step 33, it is preferred to use laser etching to remove the second TiOx layer 7 of the non-metal electrode contact area.

[0056] A method for preparing a solar cell according to the present embodiment includes the following preparation steps:

[0057] Step one, use the above steps 1-3 of the present embodiment to improve the hydrogen passivation effect of the solar cell silicon wafer 1.

[0058] Step two, prepare a metal electrode 8 (as shown in Figure 4 ) on the front and back surfaces of the silicon wafer 1 treated in step one.

[0059] In step two, the front metal electrode 8 makes ohmic contact with the front side of the silicon wafer 1; while the back metal electrode 8 makes ohmic contact with the doped polycrystalline silicon layer 3 on the back side of the silicon wafer 1.

[0060] In step two, conventional screen printing and sintering processes can be used to prepare the metal electrode 8. The preferred metal paste used to prepare the metal electrode 8 is silver paste.

[0061] This embodiment of a solar cell is fabricated using the solar cell fabrication method described above. See also... Figure 4 A solar cell according to this embodiment includes a silicon wafer 1. An aluminum oxide film 4 and a silicon nitride film 5 are stacked sequentially on the front side of the silicon wafer 1, while a tunneling silicon oxide 2, a doped polycrystalline silicon layer 3 (such as an N++ doped polycrystalline silicon layer), a silicon nitride film 5, a first TiOx layer 6, and a selective second TiOx layer 7 are sequentially disposed on the back side of the silicon wafer 1. Metal electrodes 8 are also disposed on both the front and back sides of the silicon wafer 1. One end of the metal electrode 8 on the front side passes through the silicon nitride film 5 and the aluminum oxide film 4 in sequence and makes ohmic contact with the silicon wafer 1. One end of the metal electrode 8 on the back side passes through the selective second TiOx layer 7, the first TiOx layer 6, and the silicon nitride film 5 in sequence and makes ohmic contact with the doped polycrystalline silicon layer 3.

[0062] This embodiment provides a solar cell module, which includes the solar cell described above in this embodiment.

[0063] This embodiment of a photovoltaic power station includes a solar cell module as described above.

[0064] Example 2

[0065] This embodiment describes a hydrogen passivation composite film for solar cells. (See also...) Figures 5-8 It not only deposits a first TiOx layer 6 and a selective second TiOx layer 7 sequentially on the back side of the silicon nitride film 5 on the back side of the silicon wafer 1, but also deposits a first TiOx layer 6 and a selective second TiOx layer 7 sequentially on the front side of the silicon nitride film 5 on the front side of the silicon wafer 1.

[0066] This embodiment describes a method for fabricating a hydrogen passivation composite film for solar cells, comprising the following steps:

[0067] Step 1: Select a silicon wafer 1 with silicon nitride film 5 (i.e. SiNx film) on both the front and back sides.

[0068] Step 1 of this embodiment is specifically the same as step 1 of embodiment 1, and therefore will not be repeated here.

[0069] Step 2: Prepare a first TiOx layer 6 on the entire back side of the silicon nitride film 5 on the back side of silicon wafer 1, and prepare a first TiOx layer 6 on the entire front side of the silicon nitride film 5 on the front side of silicon wafer 1 (e.g., ...). Figure 5 (As shown).

[0070] In step 2 of this embodiment, the molar ratio of titanium atoms to oxygen atoms in the first TiOx layer 6, as well as the specific deposition steps of the back side first TiOx layer 6 and the front side first TiOx layer 6, are all the same as step 2 of embodiment 1.

[0071] Step 3: A selective second TiOx layer 7 is fabricated in a localized area on the back side of the first TiOx layer 6 on the back side of silicon wafer 1, and a selective second TiOx layer 7 is fabricated in a localized area on the front side of the first TiOx layer 6 on the front side of silicon wafer 1 (e.g., ...). Figures 6-7 (As shown); this local area corresponds to the metal electrode contact area.

[0072] In step 3 of this embodiment, the molar ratio of titanium atoms to oxygen atoms in the second TiOx layer 7, as well as the specific steps of the back side second TiOx layer 7 and the front side second TiOx layer 7, are all the same as step 3 of embodiment 1.

[0073] This embodiment of a method for preparing a solar cell includes the following preparation steps:

[0074] Step 1: Use steps 1-3 of this embodiment to improve the hydrogen passivation effect of silicon wafer 1 for solar cells.

[0075] Step 2: Fabricate metal electrodes 8 on both the front and back sides of the silicon wafer 1 after the process in Step 1 (e.g., Figure 8 (As shown).

[0076] Step two in this embodiment is specifically the same as step two in embodiment 1.

[0077] This embodiment of a solar cell is fabricated using the solar cell fabrication method described above. See also... Figure 8 The solar cell of this embodiment has the same structure as the solar cell of embodiment 1. The difference between the solar cell of embodiment 1 and the solar cell of embodiment 1 is that the solar cell of this embodiment also has a first TiOx layer 6 and a selective second TiOx layer 7 stacked sequentially on the front side of the silicon nitride film 5. Therefore, one end of the metal electrode 8 on the front side passes through the selective second TiOx layer 7, the first TiOx layer 6, the silicon nitride film 5 and the aluminum oxide film 4 in sequence and makes ohmic contact with the silicon wafer 1.

[0078] This embodiment provides a solar cell module, which includes the solar cell described above in this embodiment.

[0079] The photovoltaic power station of the embodiment comprises the solar cell module of the embodiment.

[0080] Embodiment 3

[0081] The hydrogen passivation composite film for the solar cell of the embodiment, as shown in Figures 5-8 , not only has the first TiOx layer 6 and the selective second TiOx layer 7 deposited on the back of the silicon wafer 1 in sequence, but also has the first TiOx layer 6 and the selective second TiOx layer 7 deposited on the front of the silicon wafer 1 in sequence.

[0082] The method for manufacturing the hydrogen passivation composite film for the solar cell of the embodiment comprises the following steps:

[0083] Step 1, select the silicon wafer 1 with the silicon nitride film 5 (i.e. SiNx film) on the front and back.

[0084] Step 1 of the embodiment is specifically referred to Step 1 of Embodiment 1, and thus is not repeated.

[0085] Step 2, prepare the first TiOx layer 6 on the entire back of the silicon nitride film 5 on the back of the silicon wafer 1, and prepare the first TiOx layer 6 on the entire front of the silicon nitride film 5 on the front of the silicon wafer 1 (as shown in Figure 5 ).

[0086] In Step 2 of the embodiment, the molar ratio of titanium atoms to oxygen atoms in the first TiOx layer 6, and the specific deposition steps of the back first TiOx layer 6 and the front first TiOx layer 6 are all referred to Step 2 of Embodiment 1.

[0087] Step 3, prepare the selective second TiOx layer 7 on the local area on the back of the first TiOx layer 6 on the back of the silicon wafer 1, and prepare the selective second TiOx layer 7 on the local area on the front of the first TiOx layer 6 on the front of the silicon wafer 1 (as shown in Figures 6-7 ); the local area corresponds to the metal electrode contact area.

[0088] In Step 3 of the embodiment, the molar ratio of titanium atoms to oxygen atoms in the second TiOx layer 7 is specifically referred to Step 3 of Embodiment 1. In Step 3 of the embodiment, it is preferred to use the method of mask combined with PVD (physical vapor deposition) to prepare the selective second TiOx layer 7 on the metal electrode contact area. Step 3 of the embodiment comprises the following specific steps:

[0089] Step 31 of the embodiment is specifically referred to Step 31 of Embodiment 1, and thus is not repeated.

[0090] Step 32, after the temperature of the cavity is stabilized, the silicon wafer 1 is transferred to a PVD setting film coating cavity two, the film coating cavity two has a mask, the mask covers the non-metal electrode contact area of the surface of the first TiOx layer 6 (such as the front and / or back of the first TiOx layer 6), while 10-45sccm (such as 30sccm) of oxygen (O2) is introduced, the speed of the film coating cavity two is set to 100-150cm / min (such as 120cm / min), so as to prepare a selective second TiOx layer 7 on the local area of the surface of the first TiOx layer 6.

[0091] The solar cell, the preparation method thereof, the solar cell module and the photovoltaic power station of the present comparative example are all referred to the embodiment 2, and thus are not repeated.

[0092] Comparative example 1

[0093] The hydrogen passivation composite film for solar cell and the preparation method thereof of the present comparative example are referred to the steps 1-2 of the embodiment 1 (and the step 3 of the embodiment 1 is omitted).

[0094] The solar cell, the preparation method thereof, the solar cell module and the photovoltaic power station of the present comparative example are referred to the embodiment 1, and the difference between the present comparative example and the embodiment 1 is that:

[0095] In the solar cell prepared by the present comparative example, the back surface of the silicon wafer has the first TiOx layer, and the back surface of the first TiOx layer does not have the selective second TiOx layer; the front surface of the silicon wafer has neither the first TiOx layer nor the selective second TiOx layer.

[0096] Comparative example 2

[0097] The hydrogen passivation composite film for solar cell and the preparation method thereof of the present comparative example are referred to the steps 1, 3 of the embodiment 1 (and the step 2 of the embodiment 1 is omitted).

[0098] The solar cell, the preparation method thereof, the solar cell module and the photovoltaic power station of the present comparative example are referred to the embodiment 1, and the difference between the present comparative example and the embodiment 1 is that:

[0099] In the solar cell prepared by the present comparative example, the back surface of the silicon wafer has the selective second TiOx layer, and does not have the first TiOx layer; the front surface of the silicon wafer has neither the first TiOx layer nor the selective second TiOx layer.

[0100] Comparative example 3

[0101] The hydrogen passivation composite film for solar cell and the preparation method thereof of the present comparative example are referred to the steps 1-2 of the embodiment 2 (and the step 3 of the embodiment 2 is omitted).

[0102] The solar cell and its preparation method, the solar cell module and the photovoltaic power station of the present comparative example are the same as those of Example 2, except that:

[0103] In the solar cell prepared in the present comparative example, the back surface of the silicon wafer has a first TiOx layer on the back surface of the silicon nitride film, and the back surface of the first TiOx layer does not have a selective second TiOx layer, and the front surface of the silicon wafer has a first TiOx layer on the front surface of the silicon nitride film, and the front surface of the first TiOx layer does not have a selective second TiOx layer.

[0104] Comparative Example 4

[0105] The hydrogen passivation recombination film for a solar cell and its preparation method of the present comparative example are the same as those of Example 2, except that steps 1 and 3 of Example 2 are used (step 2 of Example 2 is omitted).

[0106] The solar cell and its preparation method, the solar cell module and the photovoltaic power station of the present comparative example are the same as those of Example 2, except that:

[0107] In the solar cell prepared in the present comparative example, the back surface of the silicon wafer has a selective second TiOx layer on the back surface of the silicon nitride film, and does not have a first TiOx layer, and the front surface of the silicon wafer has a selective second TiOx layer on the front surface of the silicon nitride film, and does not have a first TiOx layer.

[0108] Performance test

[0109] Table 1

[0110]

[0111] Table 2

[0112]

[0113]

[0114] In Table 1-2, double-sided refers to the front surface of the silicon wafer and the back surface of the silicon wafer; VOC represents open circuit voltage, Isc represents short circuit current, FF represents fill factor, and Eta represents cell efficiency (i.e. the photoelectric conversion efficiency of the cell).

[0115] It can be seen from Table 1-2 that:

[0116] (1) Compared with Example 1 (only the back surface has the first TiOx layer and the selective second TiOx layer), the batteries of Examples 2-3 have the first TiOx layer and the selective second TiOx layer on both surfaces, so the total [H] content of the SiNx film of the batteries of Examples 2-3 is significantly increased, the chemical passivation effect is better, and the open-circuit voltage and the battery efficiency are further improved.

[0117] Moreover, compared with Example 3 which uses the PVD combined with the mask method to prepare the selective second TiOx layer, the batteries of Example 2 (which uses the PVD + laser slotting method to prepare the selective second TiOx layer) have further increased total [H] content of the SiNx film, better chemical passivation effect, and improved open-circuit voltage and short-circuit current, and further improved battery efficiency.

[0118] (2) Comparative Example 1 (only the back surface has the first TiOx layer without the selective second TiOx layer) has significantly improved total [H] content of the SiNx film of the battery compared with Comparative Example 2 because the back surface of the silicon nitride film has the first TiOx layer; but compared with Example 1 (only the back surface has the first TiOx layer and the selective second TiOx layer), the first TiOx layer of Comparative Example 1 lacks the selective second TiOx layer on the back surface, which cannot effectively block the metal paste and prevent the hydrogen in the silicon nitride film from overflowing, and the parasitic absorption is serious and the double-sided rate is not ideal, so the open-circuit voltage, the fill factor, the total [H] content of the SiNx film of the battery, and the short-circuit current are all decreased, and the battery efficiency is decreased.

[0119] Compared with Example 1, Comparative Example 2 (only the back surface has the selective second TiOx layer without the first TiOx layer) has a significantly improved fill factor because the back surface of the silicon nitride film has the selective second TiOx layer; but because the back surface of the silicon nitride film lacks the first TiOx layer between the selective second TiOx layer, it cannot effectively block the hydrogen in the silicon nitride film from overflowing and block the metal paste, so the total [H] content of the SiNx film of the battery is low, the chemical passivation effect is poor, and the open-circuit voltage and the battery efficiency are decreased more obviously than Comparative Example 1.

[0120] Example 2 (both surfaces have the first TiOx layer and the selective second TiOx layer) and Comparative Examples 3 (both surfaces have the first TiOx layer without the selective second TiOx layer) and 4 (both surfaces have the selective second TiOx layer without the first TiOx layer) also have the similar effect rules as Example 1 and Comparative Examples 1 and 2.

[0121] Therefore, the hydrogen passivation composite film for the solar cell has the first TiOx layer (the molar ratio of titanium atoms to oxygen atoms is 0.1-0.5) and the selective second TiOx layer (the molar ratio of titanium atoms to oxygen atoms is 1.5-3) arranged on the silicon nitride film (SiNx film) of the solar cell (such as a TOPCon cell) in sequence, so as to solve the problem of hydrogen overflow in the silicon nitride film, realize the role of blocking hydrogen overflow, and improve the chemical passivation effect of the solar cell silicon wafer (such as a crystalline silicon wafer); in addition, the first TiOx layer and the selective second TiOx layer (especially the selective second TiOx layer) also have the role of blocking metal paste, and can thin the thickness of the polysilicon layer; at the same time, the selective second TiOx layer is prepared in the metal electrode contact area of the first TiOx layer, and can also avoid the serious parasitic absorption caused by the whole second TiOx layer with a high molar ratio of titanium atoms to oxygen atoms; therefore, the hydrogen passivation composite film for the solar cell can improve the bifaciality, open-circuit voltage and cell efficiency of the solar cell.

[0122] In addition, in the utility model, when the first TiOx layer and the selective second TiOx layer are deposited on the silicon nitride film by the PVD (physical vapor deposition) method, stable TiOx layers (namely the first TiOx layer and the selective second TiOx layer) can be obtained by controlling process parameters such as gas flow and deposition speed, the repeatability is good, and the method can be introduced into large-scale industrial production.

[0123] Although the preferred embodiments of the utility model embodiments have been described, those skilled in the art can make other changes and modifications to the embodiments once the basic creative concept is known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the utility model embodiments.

[0124] The above describes the technical solutions provided by the utility model in detail, and the principles and implementation modes of the utility model are described by applying specific examples; the above embodiment description is only used to help understand the method and core idea of the utility model; meanwhile, for those skilled in the art, according to the idea of the utility model, the specific implementation mode and application range can be changed; in conclusion, the content of the specification should not be understood as limiting the utility model.

Claims

1. A hydrogen passivation composite film for solar cells, characterized in that, Includes silicon wafers and silicon nitride films disposed on the surface of the silicon wafers; The surface of the silicon nitride film is provided with a first TiOx layer, wherein the molar ratio of titanium atoms to oxygen atoms in the first TiOx layer is 0.5; A selective second TiOx layer is also provided in a local area on the surface of the first TiOx layer, wherein the molar ratio of titanium atoms to oxygen atoms in the second TiOx layer is 1.5 to 3.

2. The hydrogen passivation composite film for solar cells according to claim 1, characterized in that, The molar ratio of titanium atoms to oxygen atoms in the second TiOx layer is 2.

3. The hydrogen passivation composite film for solar cells according to claim 1, characterized in that, The silicon wafer has a silicon nitride film on both the front and back sides; the silicon nitride film on the front side of the silicon wafer has a first TiOx layer and a selective second TiOx layer sequentially disposed on the front side, and / or the silicon nitride film on the back side of the silicon wafer has a first TiOx layer and a selective second TiOx layer sequentially disposed on the back side.

4. The hydrogen passivation composite film for solar cells according to claim 3, characterized in that, A passivation contact structure is also provided between the silicon wafer and the silicon nitride film on the back.

5. The hydrogen passivation composite film for solar cells according to claim 4, characterized in that, The passivation contact structure includes a tunneling silicon oxide layer disposed on the back side of the silicon wafer and a doped polycrystalline silicon layer located between the tunneling silicon oxide layer and the silicon nitride film on the back side.

6. The hydrogen passivation composite film for solar cells according to claim 3, characterized in that, An aluminum oxide film is also provided between the silicon wafer and the silicon nitride film on the front side.

7. The hydrogen passivation composite film for solar cells according to claim 1, characterized in that, The local area corresponds to the metal electrode contact area.

8. A solar cell, characterized in that, The invention includes a hydrogen passivation composite film for solar cells as described in any one of claims 1-7; the silicon wafer is provided with metal electrodes on both the front and back sides, one end of the metal electrode on the front side of the silicon wafer is in ohmic contact with the silicon wafer, and one end of the metal electrode on the back side of the silicon wafer is in ohmic contact with the doped polycrystalline silicon layer on the back side of the silicon wafer.

9. A solar cell module, characterized in that, It includes a solar cell as described in claim 8.

10. A photovoltaic power station, characterized in that, It includes a solar cell module as described in claim 9.

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