Method for producing a nitrogen-doped titania layer, nitrogen-doped titania layer and tbc cell

Abstract

The application provides a preparation method of a nitrogen-doped titanium dioxide layer, the nitrogen-doped titanium dioxide layer and a TBC battery, and relates to the technical field of solar cells. The preparation method of the nitrogen-doped titanium dioxide layer comprises the following steps: performing precursor introduction, first purification, oxidation and second purification on the surface of a to-be-deposited substrate in a cycle deposition mode, and performing annealing treatment after the cycle deposition is completed to obtain the nitrogen-doped titanium dioxide layer; wherein the precursor introduction comprises introducing a titanium-containing precursor gas; and the oxidation comprises introducing an oxidant and a nitrogen-containing gas. The nitrogen-doped titanium dioxide layer prepared by the method has good electron contact effect and appropriate optical characteristics; and the nitrogen-doped titanium dioxide layer is introduced between a doped polysilicon layer and a metal electrode to improve the back surface passivation performance of the TBC battery and improve the conversion efficiency of the battery.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a method for preparing a nitrogen-doped titanium dioxide layer, the nitrogen-doped titanium dioxide layer, and a TBC cell. Background Technology

[0002] On the back of a TBC battery, the P-poly and N-poly regions in the P-region and N-poly regions are in direct contact with the metal electrode. At the sintering temperature, the paste forms an alloy phase with silicon and diffuses rapidly within the silicon. Pure silver paste diffuses to nanometer-level depths, while micro-aluminum paste can reach micrometer-level depths, leading to contact recombination between the metal electrode and the P-poly and N-poly layers. Therefore, during sintering, this inevitably penetrates into the polycrystalline silicon layer, resulting in a decrease in the passivation quality of the polycrystalline silicon structure on the back of the TBC battery. Furthermore, to improve optical performance, the polycrystalline silicon is typically made thinner, which further exacerbates the passivation damage caused by the metal paste, worsening the problem.

[0003] In view of this, the present invention is hereby proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a nitrogen-doped titanium dioxide layer, the nitrogen-doped titanium dioxide layer, and a TBC (Transfer-Based Cell) battery. The nitrogen-doped titanium dioxide layer prepared by this invention exhibits good electronic contact properties and appropriate optical characteristics. Furthermore, introducing this nitrogen-doped titanium dioxide layer between the doped polycrystalline silicon layer and the metal electrode on the back side of the TBC battery can improve the thermal stability of the metallized polycrystalline silicon contacts and provide effective protection for the doped polycrystalline silicon layer, avoiding passivation degradation caused by sintering heat treatment, thus improving the back passivation performance of the TBC battery and thereby increasing the battery conversion efficiency.

[0005] To achieve the above objectives, the following technical solution is proposed:

[0006] In a first aspect, the present invention provides a method for preparing a nitrogen-doped titanium dioxide layer, the method comprising:

[0007] The surface of the substrate to be deposited is subjected to a cycle of deposition, including precursor introduction, first purification, oxidation, and second purification, followed by annealing after the cycle deposition is completed to obtain the nitrogen-doped titanium dioxide layer; wherein, the precursor introduction includes the introduction of a titanium-containing precursor gas; the oxidation includes the introduction of an oxidant and a nitrogen-containing gas.

[0008] Furthermore, the preparation method employs the ALD method.

[0009] Furthermore, the thickness of the nitrogen-doped titanium dioxide layer is 5–50 nm.

[0010] Furthermore, the temperature of the cyclic deposition is 80–250°C; the pressure of the cyclic deposition is 200–400 mtor.

[0011] Furthermore, the time for each single precursor introduction, first purification, oxidation, and second purification is independently 5–25 s.

[0012] Furthermore, the number of cyclic depositions is 100 to 500 times.

[0013] Furthermore, the titanium-containing precursor gas includes any one or a combination of at least two of titanium tetrachloride, tetraisopropyl titanate, tetra(dimethylamino)titanium, or tetra(ethylmethylamino)titanium.

[0014] Furthermore, the pulse duration of the titanium-containing precursor gas is 0.1–2 s.

[0015] Furthermore, the oxidant includes any one or a combination of at least two of water vapor, ozone, oxygen, or excited-state oxygen molecules.

[0016] Furthermore, the nitrogen-containing gas includes ammonia.

[0017] Furthermore, the pulse duration of the oxidant is 0.1–1 s;

[0018] Furthermore, the pulse duration of the nitrogen-containing gas is 0.1 to 1 second.

[0019] Furthermore, the first purification and the second purification each independently include introducing a purified gas for purification treatment.

[0020] Furthermore, the purifying gas includes nitrogen and / or argon.

[0021] Furthermore, the flow rate of the purified gas is 10-20 slm.

[0022] Furthermore, the time for each of the first and second purification processes is independently 5 to 20 seconds.

[0023] Furthermore, the annealing temperature is 400–600°C; the annealing time is 0.5–2 hours.

[0024] Furthermore, the annealing process includes processing with nitrogen gas.

[0025] Furthermore, the flow rate of the nitrogen gas is 1000–5000 sccm.

[0026] In a second aspect, the present invention provides a nitrogen-doped titanium dioxide layer, wherein the nitrogen-doped titanium dioxide layer is prepared by the preparation method described in the first aspect.

[0027] Thirdly, the present invention provides a TBC battery, the TBC battery comprising a nitrogen-doped titanium dioxide layer as described in the second aspect; wherein the nitrogen-doped titanium dioxide layer is located between a doped polycrystalline silicon layer and a metal electrode on the back side of the TBC battery.

[0028] Furthermore, the TBC battery comprises: an N-type crystalline silicon substrate;

[0029] The back surface of the N-type crystalline silicon substrate includes a P-region, an N-region, and an isolation region located between the P-region and the N-region, with the P-region and N-region being spaced apart. The P-region includes, from the inside out, a tunneling oxide layer, a P-type doped polycrystalline silicon layer, a nitrogen-doped titanium dioxide layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer. The N-region includes, from the inside out, a tunneling oxide layer, an N-type doped polycrystalline silicon layer, a nitrogen-doped titanium dioxide layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer. A P-region electrode is disposed in the P-region, and an N-region electrode is disposed in the N-region.

[0030] The front side of the N-type crystalline silicon substrate has a pyramidal textured surface; the front side of the N-type crystalline silicon substrate includes an aluminum oxide passivation layer, a silicon nitride passivation layer, and a silicon oxide passivation layer arranged from the inside out.

[0031] Fourthly, the present invention provides a method for preparing a TBC battery, the method comprising:

[0032] (1) Deposit a tunneling oxide layer and an intrinsic amorphous silicon layer on the back side of an N-type crystalline silicon substrate;

[0033] (2) Boron diffusion is performed on the back side of the silicon substrate obtained in step (1) to form a boron-doped polycrystalline silicon layer;

[0034] (3) The silicon substrate of boron diffusion in step (2) is subjected to the following steps in sequence: first patterning, BSG removal, alkaline polishing, deposition of tunneling oxide layer and intrinsic amorphous silicon layer, phosphorus diffusion, second patterning, PSG removal, texturing, deposition of nitrogen-doped titanium dioxide layer, passivation treatment, electrode printing and light injection to obtain the TBC battery.

[0035] The nitrogen-doped titanium dioxide layer is deposited using the preparation method described in the first aspect.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The preparation method described in this invention can prepare a nitrogen-doped titanium dioxide layer with good electronic contact and appropriate optical properties.

[0038] (2) The TBC battery of the present invention introduces the nitrogen-doped titanium dioxide layer between the doped polycrystalline silicon layer on the back and the metal electrode. The titanium dioxide layer can improve the thermal stability of the metallized polycrystalline silicon contacts and provide effective protection for the polycrystalline silicon layer, avoiding passivation degradation caused by sintering heat treatment, improving the passivation performance of the back of the TBC battery and improving the battery conversion efficiency. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the structure of the TBC battery described in this invention.

[0041] Figure 2 This is a process flow diagram of the TBC battery preparation method described in this invention.

[0042] Figure 3 This is a schematic diagram of the structure of the battery cell obtained by boron diffusion in the preparation method of the TBC battery described in this invention.

[0043] Figure 4 This is a schematic diagram of the structure of the battery cell obtained by the first graphical representation in the preparation method of the TBC battery described in this invention.

[0044] Figure 5 This is a schematic diagram of the structure of the battery cell obtained by BSG winding plating and alkaline polishing in the preparation method of the TBC battery of the present invention.

[0045] Figure 6 This is a schematic diagram of the structure of the battery cell obtained by phosphorus diffusion in the preparation method of the TBC battery of the present invention.

[0046] Figure 7 This is a schematic diagram of the structure of the battery cell obtained by the second patterning in the preparation method of the TBC battery of the present invention.

[0047] Figure 8 This is a schematic diagram of the structure of the battery cell obtained by PSG removal and texturing in the preparation method of the TBC battery of the present invention.

[0048] In this diagram, 10 represents the N-type crystalline silicon substrate, 20 represents the tunneling oxide layer, 31 represents the P-type doped polycrystalline silicon layer, 32 represents the N-type doped polycrystalline silicon layer, 40 represents the BSG layer, 41 represents the PSG layer, 50 represents the nitrogen-doped titanium dioxide layer, 60 represents the alumina passivation layer, 61 represents the silicon nitride passivation layer, 62 represents the silicon oxide passivation layer, 71 represents the P-region electrode, and 72 represents the N-region electrode. Detailed Implementation

[0049] Unless otherwise defined herein, scientific and process terms used in conjunction with this invention should have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms should be clear; however, in any case of potential ambiguity, the definitions provided herein take precedence over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0050] It should be noted that specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many ways other than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0051] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] In a first aspect, the present invention provides a method for preparing a nitrogen-doped titanium dioxide layer, the method comprising:

[0053] The surface of the substrate to be deposited is subjected to a cycle of deposition, including precursor introduction, first purification, oxidation, and second purification, followed by annealing after the cycle deposition is completed to obtain the nitrogen-doped titanium dioxide layer; wherein, the precursor introduction includes the introduction of a titanium-containing precursor gas; the oxidation includes the introduction of an oxidant and a nitrogen-containing gas.

[0054] In this invention, the cyclic deposition step includes: firstly, introducing a titanium-containing precursor gas for chemical adsorption on the substrate surface to form a monolayer Ti-O bonded layer, laying the lattice basis of titanium dioxide and controlling the thickness accuracy of titanium dioxide; further, performing a first purification to remove unreacted titanium-containing precursor gas and / or byproducts, avoiding gas-phase side reactions and ensuring interlayer purity; next, introducing an oxidant and a nitrogen-containing gas to achieve uniform doping, reacting with the Ti source adsorbed on the surface to form a nitrogen-containing oxide layer, where nitrogen atoms (N) replace lattice oxygen sites (O), forming substitutional doping (Ti-N bonds); further, performing a second purification to remove unreacted oxidant and / or byproducts, and preventing excessive nitrogen doping or the formation of amorphous nitrides; simultaneously, using a cyclic deposition method to progressively form nitrogen-doped titanium dioxide layers to achieve the preparation of a highly uniform, dense, and defect-free nitrogen-doped titanium dioxide layer. Finally, annealing is performed after the cyclic deposition is completed to activate nitrogen-doped sites and promote crystallization, thereby eliminating defects in the nitrogen-doped titanium dioxide layer and promoting nitrogen atom entry into the crystal lattice. Therefore, the nitrogen-doped titanium dioxide layer prepared by the method described in this invention has good electronic contact and appropriate optical properties, enabling it to be introduced into a TBC cell as an interlayer between the doped polycrystalline silicon layer and the metal electrode on the back side, thus improving the passivation performance of the TBC cell.

[0055] As an optional implementation, the preparation method employs the ALD method.

[0056] As an optional implementation, the substrate to be deposited includes an N-type crystalline silicon substrate.

[0057] As an optional implementation, the surface of the substrate to be deposited is located on the back side of the N-type crystalline silicon substrate.

[0058] As an optional implementation, the surface of the substrate to be deposited is located on the surface of the doped polycrystalline silicon layer on the back side of the N-type crystalline silicon substrate.

[0059] As an optional implementation, the doped polysilicon layer includes a P-type doped polysilicon layer and / or the N-type doped polysilicon layer.

[0060] As an optional implementation, the thickness of the nitrogen-doped titanium dioxide layer is 5 to 50 nm, for example, it can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, etc.

[0061] As an optional implementation, the temperature of the cyclic deposition is 80 to 250°C, for example, it can be 80°C, 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, 220°C, 240°C, 250°C, etc.

[0062] As an optional implementation, the pressure of the cyclic deposition is 200 to 400 mtor, for example, 200 mtorr, 220 mtorr, 240 mtorr, 260 mtorr, 280 mtorr, 300 mtorr, 320 mtorr, 340 mtorr, 360 mtorr, 380 mtorr, 400 mtorr, etc.

[0063] As an optional implementation, the time for a single introduction of the precursor is 5 to 25 seconds, for example, 5 seconds, 7 seconds, 9 seconds, 11 seconds, 13 seconds, 15 seconds, 17 seconds, 19 seconds, 21 seconds, 23 seconds, 25 seconds, etc.

[0064] As an optional implementation, the time for a single first purification is 5 to 25 seconds, for example, 5 seconds, 7 seconds, 9 seconds, 11 seconds, 13 seconds, 15 seconds, 17 seconds, 19 seconds, 21 seconds, 23 seconds, 25 seconds, etc.

[0065] As an optional implementation, the oxidation time for a single cycle is 5 to 25 seconds, for example, 5 seconds, 7 seconds, 9 seconds, 11 seconds, 13 seconds, 15 seconds, 17 seconds, 19 seconds, 21 seconds, 23 seconds, 25 seconds, etc.

[0066] As an optional implementation, the time for a single second purification is 5 to 25 seconds, for example, 5 seconds, 7 seconds, 9 seconds, 11 seconds, 13 seconds, 15 seconds, 17 seconds, 19 seconds, 21 seconds, 23 seconds, 25 seconds, etc.

[0067] As an optional implementation, the number of cyclic depositions is 100 to 500 times, for example, 100 times, 120 times, 140 times, 160 times, 180 times, 200 times, 220 times, 240 times, 260 times, 280 times, 300 times, 320 times, 340 times, 360 times, 380 times, 400 times, 420 times, 440 times, 460 times, 480 times, 500 times, etc.

[0068] It should be noted that cyclic deposition refers to completing one cycle in the order of precursor introduction, first purification, oxidation and second purification, and then completing the next cycle in the same order. The number of cyclic deposition cycles here refers to the total number of cycles.

[0069] As an optional implementation, the titanium-containing precursor gas includes any one or a combination of at least two of titanium tetrachloride (TiCl4), tetraisopropyl titanate (TTIP), tetra(dimethylamino)titanium (TDMAT), or tetra(ethylmethylamino)titanium (TEMAT).

[0070] As an optional implementation, the pulse time of the titanium-containing precursor gas is 0.1 to 2 s, for example, it can be 0.1 s, 0.2 s, 0.4 s, 0.6 s, 0.8 s, 1 s, 1.2 s, 1.4 s, 1.6 s, 1.8 s, 2 s, etc.

[0071] As an optional implementation, the oxidant includes any one or a combination of at least two of water vapor (H2O), ozone (O3), oxygen (O2), or excited-state oxygen molecules (O2*).

[0072] As an optional implementation, the nitrogen-containing gas includes ammonia (NH3).

[0073] As an optional implementation, the pulse time of the oxidant is 0.1 to 1 s, for example, it can be 0.1 s, 0.2 s, 0.4 s, 0.6 s, 0.8 s, 1 s, 1.2 s, 1.4 s, 1.6 s, 1.8 s, 2 s, etc.

[0074] As an optional implementation, the pulse time of the nitrogen-containing gas is 0.1 to 1 s, for example, it can be 0.1 s, 0.2 s, 0.4 s, 0.6 s, 0.8 s, 1 s, etc.

[0075] As an optional implementation, the first purification includes introducing a purification gas for a first purification treatment to remove unreacted Ti-containing precursor gases and / or byproducts.

[0076] As an optional implementation, the second purification includes introducing a purified gas for a second purification treatment to remove unreacted oxidants and / or byproducts.

[0077] As an optional implementation, the purifying gas includes nitrogen (N2) and / or argon (Ar).

[0078] As an optional implementation, in the first purification, the flow rate of the purified gas introduced is 10 to 20 slm, for example, it can be 10 slm, 11 slm, 12 slm, 13 slm, 14 slm, 15 slm, 16 slm, 17 slm, 18 slm, 19 slm, 20 slm, etc.

[0079] As an optional implementation, in the second purification process, the flow rate of the purified gas introduced is 10 to 20 slm, for example, it can be 10 slm, 11 slm, 12 slm, 13 slm, 14 slm, 15 slm, 16 slm, 17 slm, 18 slm, 19 slm, 20 slm, etc.

[0080] As an optional implementation, the time for a single first purification is 5 to 20 seconds, for example, 5 seconds, 7 seconds, 9 seconds, 11 seconds, 13 seconds, 15 seconds, 17 seconds, 19 seconds, 20 seconds, etc.

[0081] As an optional implementation, the time for a single second purification is 5 to 20 seconds, for example, 5 seconds, 7 seconds, 9 seconds, 11 seconds, 13 seconds, 15 seconds, 17 seconds, 19 seconds, 20 seconds, etc.

[0082] As an optional implementation, the annealing temperature is 400-600℃, for example, 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 560℃, 580℃, 600℃, etc.

[0083] As an optional implementation, the annealing time is 0.5 to 2 hours, for example, 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2 hours, etc.

[0084] As an optional implementation, the annealing process includes processing with nitrogen gas.

[0085] As an optional implementation, during the annealing process, the flow rate of the nitrogen gas introduced is 1000 to 5000 sccm, for example, it can be 1000 sccm, 1500 sccm, 2000 sccm, 2500 sccm, 3000 sccm, 3500 sccm, 4000 sccm, 4500 sccm, 5000 sccm, etc.

[0086] In a second aspect, the present invention provides a nitrogen-doped titanium dioxide layer, wherein the nitrogen-doped titanium dioxide layer is prepared by the preparation method described in the first aspect.

[0087] Thirdly, the present invention provides a TBC battery, the TBC battery comprising a nitrogen-doped titanium dioxide layer as described in the second aspect; wherein the nitrogen-doped titanium dioxide layer is located between a doped polycrystalline silicon layer and a metal electrode on the back side of the TBC battery.

[0088] In this invention, since the nitrogen-doped titanium dioxide layer has good electronic contact and appropriate optical properties, introducing an additional nitrogen-doped titanium dioxide layer between the polycrystalline silicon layer and the metal electrode can improve the thermal stability of the metallized polycrystalline silicon contacts. The nitrogen-doped titanium dioxide layer can provide effective protection for the polycrystalline silicon layer, avoid passivation degradation caused by sintering heat treatment, improve the passivation performance of the back side of the TBC battery, and improve the battery conversion efficiency.

[0089] As an optional implementation method, such as Figure 1 As shown, the TBC battery includes: an N-type crystalline silicon substrate 10; wherein, the back side of the N-type crystalline silicon substrate 10 includes a P-region, an N-region, and an isolation region located between the P-region and the N-region, the P-region and the N-region being spaced apart; the P-region includes, from the inside out, a tunneling oxide layer 20, a P-type doped polycrystalline silicon layer 31, a nitrogen-doped titanium dioxide layer 50, an aluminum oxide passivation layer 60, and a silicon nitride passivation layer 61; the N-region includes, from the inside out, a tunneling oxide layer 20, an N-type doped polycrystalline silicon layer 32, a nitrogen-doped titanium dioxide layer 50, an aluminum oxide passivation layer 60, and a silicon nitride passivation layer 61. An aluminum passivation layer 60 and a silicon nitride passivation layer 61 are provided; a P-region electrode 71 is provided in the P-region, and an N-region electrode 72 is provided in the N-region; and a nitrogen-doped titanium dioxide layer 50 is respectively disposed between the P-type doped polycrystalline silicon layer 31 and the P-region electrode 71, and between the N-type doped polycrystalline silicon layer 32 and the N-region electrode 72; wherein, the front side of the N-type crystalline silicon substrate 10 has a pyramidal textured surface structure; the front side of the N-type crystalline silicon substrate includes an aluminum oxide passivation layer 60, a silicon nitride passivation layer 61, and a silicon oxide passivation layer 62 disposed from the inside out.

[0090] Fourthly, the present invention provides a method for preparing a TBC battery, the method comprising:

[0091] (1) Deposit a tunneling oxide layer and an intrinsic amorphous silicon layer on the back side of an N-type crystalline silicon substrate;

[0092] (2) Boron diffusion is performed on the back side of the silicon substrate obtained in step (1) to form a boron-doped polycrystalline silicon layer;

[0093] (3) The silicon substrate of boron diffusion in step (2) is subjected to the following steps in sequence: first patterning, BSG removal, alkaline polishing, deposition of tunneling oxide layer and intrinsic amorphous silicon layer, phosphorus diffusion, second patterning, PSG removal, texturing, deposition of nitrogen-doped titanium dioxide layer, passivation treatment, electrode printing and light injection to obtain the TBC battery.

[0094] The nitrogen-doped titanium dioxide layer is deposited using the preparation method described in the first aspect.

[0095] As an optional implementation, in step (1), the deposition of the tunneling oxide layer and the intrinsic amorphous silicon layer includes: depositing the tunneling oxide layer and the intrinsic amorphous silicon layer sequentially on the back side of the silicon substrate by LPCVD.

[0096] As an optional implementation, in step (1), the thickness of the tunneling oxide layer is 1.0 to 2.5 nm, for example, it can be 1.0 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2.0 nm, 2.1 nm, 2.2 nm, 2.3 nm, 2.4 nm, 2.5 nm, etc.; the temperature for depositing the tunneling oxide layer is 500 to 650 °C, for example, it can be 500 °C, 520 °C, 540 °C, 550 °C, 560 °C, 580 °C, 600 °C, 620 °C, 640 °C, 650 °C, etc.; the time for depositing the tunneling oxide layer is 20 to 80 min, for example, it can be 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, etc.

[0097] As an optional implementation, in step (1), the thickness of the intrinsic amorphous silicon layer is 200-400 nm, for example, it can be 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, 320 nm, 340 nm, 360 nm, 380 nm, 400 nm, etc., the deposition temperature of the intrinsic amorphous silicon layer is 500-650 °C, for example, it can be 500 °C, 520 °C, 540 °C, 550 °C, 560 °C, 580 °C, 600 °C, 620 °C, 640 °C, 650 °C, etc., and the deposition time of the intrinsic amorphous silicon layer is 50-100 min, for example, it can be 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, etc.

[0098] As an optional implementation, in step (2), the boron diffusion includes: introducing a mixed gas of BCl3, O2 and N2 into the silicon substrate after deposition in step (1) to carry out phosphorus diffusion, thereby obtaining a silicon substrate with a boron-doped polycrystalline silicon layer.

[0099] As an optional implementation, in step (2), the process parameters for boron diffusion include: BCl3 flow rate of 200–400 sccm, for example, 200 sccm, 220 sccm, 240 sccm, 260 sccm, 280 sccm, 300 sccm, 320 sccm, 340 sccm, 360 sccm, 380 sccm, 400 sccm, etc.; O2 flow rate of 700–1000 sccm, for example, 700 sccm, 720 sccm, 740 sccm, 760 sccm, 780 sccm, 800 sccm, 820 sccm, 840 sccm, 860 sccm, 880 sccm, 900 sccm, 920 sccm, 940 sccm, 960 sccm, 980 sccm, 1000 sccm, etc.; N2 flow rate of 2500–3000 sccm, for example, ... These include 2500 sccm, 2550 sccm, 2600 sccm, 2650 sccm, 2700 sccm, 2750 sccm, 2800 sccm, 2850 sccm, 2900 sccm, 2950 sccm, and 3000 scccmm; the deposition temperature is 800–1000℃, for example, 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, and 940℃. Temperatures include 0℃, 960℃, 980℃, and 1000℃; deposition time is 1–2 hours, for example, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, and 2 hours; sheet resistance is 100–200 Ω, for example, 100 Ω, 110 Ω, 120 Ω, 130 Ω, 140 Ω, 150 Ω, 160 Ω, 170 Ω, 180 Ω, 190 Ω, and 200 Ω.

[0100] As an optional implementation, in step (3), the first patterning includes: removing part of the BSG layer on the back side of the silicon substrate obtained in step (2) (the subsequent BSG layer of the Gap region + N region) to form a patterned groove.

[0101] As an optional implementation, the first patterning is performed using a picosecond laser.

[0102] As an optional implementation, the depth of the patterned groove formed in the first patterning is 30-80nm, for example, it can be 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, etc.

[0103] As an optional implementation, the width of the patterned groove formed in the first patterning is 400-600μm, for example, it can be 400μm, 420μm, 440μm, 460μm, 480μm, 500μm, 520μm, 540μm, 560μm, 580μm, 600μm, etc.

[0104] As an optional implementation, in step (3), the removal of BSG plating and alkaline polishing includes: chain-type wet removal of the BSG plating on the front side, and tank-type polishing to remove the P-type doped polysilicon layer and tunneling oxide layer in the patterned groove area on the front side and the back side. The depth of the patterned groove is increased to 2-3 μm, for example, it can be 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm, etc.

[0105] As an optional implementation, in step (3), the deposition of the tunneling oxide layer and the intrinsic amorphous silicon layer includes: depositing the tunneling oxide layer and the intrinsic amorphous silicon layer in a secondary manner by LPCVD.

[0106] As an optional implementation, in step (3), the thickness of the tunneling oxide layer is 1.0 to 2.5 nm, for example, it can be 1.0 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2.0 nm, 2.1 nm, 2.2 nm, 2.3 nm, 2.4 nm, 2.5 nm, etc.

[0107] As an optional implementation, in step (3), the temperature at which the tunneling oxide layer is deposited is 500 to 650°C, for example, 500°C, 520°C, 540°C, 550°C, 560°C, 580°C, 600°C, 620°C, 640°C, 650°C, etc.

[0108] As an optional implementation, in step (3), the time for depositing the tunneling oxide layer is 20 to 80 minutes, for example, it can be 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, etc.

[0109] As an optional implementation, in step (3), the thickness of the intrinsic amorphous silicon layer is 100-300nm, for example, it can be 100nm, 120nm, 140nm, 160nm, 180nm, 200nm, 220nm, 240nm, 260nm, 280nm, 300nm, etc.

[0110] As an optional implementation, in step (3), the temperature for depositing the intrinsic amorphous silicon layer is 500 to 650°C, for example, 500°C, 520°C, 540°C, 550°C, 560°C, 580°C, 600°C, 620°C, 640°C, 650°C, etc.

[0111] As an optional implementation, in step (3), the time for depositing the intrinsic amorphous silicon layer is 50 to 100 minutes, for example, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, etc.

[0112] As an optional implementation, in step (3), the phosphorus diffusion includes: introducing a mixture of POCl3, O2 and N2 gas into the silicon substrate after secondary deposition to carry out phosphorus diffusion, thereby obtaining a silicon substrate with a phosphorus-doped polycrystalline silicon layer.

[0113] As an optional implementation, in step (3), during the phosphorus diffusion process, the flow rate of POCl3 is 1000-2000 sccm, for example, it can be 1000 sccm, 1100 sccm, 1200 sccm, 1300 sccm, 1400 sccm, 1500 sccm, 1600 sccm, 1700 sccm, 1800 sccm, 1900 sccm, 2000 sccm, etc.; the flow rate of O2 is 500-1000 sccm, for example, it can be 500 sccm, 550 sccm, 600 sccm, etc. 0 sccm, 650 sccm, 700 sccm, 725 sccm, 750 sccm, 775 sccm, 800 sccm, 825 sccm, 850 sccm, 875 sccm, 900 sccm, 925 sccm, 950 sccm, 975 sccm, 1000 sccm, etc.; the flow rate of N2 is 500-1500 sccm, for example, it can be 500 sccm, 550 sccm, 600 sccm, 650 sccm, 700 sccm, 750 sccm, 800 sccm, 850 sccm, etc. The phosphorus diffusion temperatures are 800–1000°C, for example, 800°C, 820°C, 840°C, 850°C, 860°C, 880°C, 890°C, 900°C, 920°C, 940°C, 950°C, 960°C, 980°C, 1000°C, etc.; the phosphorus diffusion time is 1–3 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.5 hours, etc. h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.5h, 2.6h, 2.8h, 3h, etc.; the thickness of the PSG layer is 30-80nm, for example, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, etc.; the sheet resistance of the silicon substrate with the phosphorus-doped polycrystalline silicon layer is 20-80Ω, for example, 20Ω, 25Ω, 30Ω, 35Ω, 40Ω, 45Ω, 50Ω, 55Ω, 60Ω, 65Ω, 70Ω, 75Ω, 80Ω, etc.

[0114] As an optional implementation, in step (3), the second patterning includes: retaining the PSG layer in the N-region on the back of the silicon substrate and removing the PSG layer in the remaining region.

[0115] As an optional implementation, the second patterning is performed using a picosecond laser.

[0116] As an optional implementation, in step (3), the removal of PSG coating and texturing includes: retaining the N-type doped polysilicon layer and tunnel oxide layer in the N region on the back side, retaining the P-type doped polysilicon layer and tunnel oxide layer in the P region on the back side, and texturing the remaining front and back areas.

[0117] As an optional implementation, in step (3), the deposition of the nitrogen-doped titanium dioxide layer includes: a cyclic deposition of precursor introduction, first purification, oxidation and second purification on the surface of the substrate to be deposited, and an annealing treatment after the cyclic deposition is completed to obtain the nitrogen-doped titanium dioxide layer; wherein, the precursor introduction includes the introduction of a titanium-containing precursor gas; the oxidation includes the introduction of an oxidant and a nitrogen-containing gas.

[0118] As an optional implementation, in step (3), the passivation process includes: depositing an aluminum oxide passivation layer on both sides of the silicon substrate, depositing a silicon nitride passivation layer on the back side, and depositing a silicon nitride passivation layer and a silicon oxide passivation layer on the front side.

[0119] As an optional implementation, the thickness of the alumina passivation layer is 1 to 10 nm, for example, it can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc.

[0120] As an optional implementation, the thickness of the silicon nitride passivation layer is 70-100 nm, for example, it can be 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, etc.

[0121] As an optional implementation, the thickness of the silicon oxide passivation layer is 5 to 20 nm, for example, it can be 5 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, etc.

[0122] As an optional implementation method, such as Figure 2 As shown, the preparation method of the TBC battery includes the following steps:

[0123] S1, Primary deposition:

[0124] A secondary deposited silicon substrate is obtained by depositing a tunneling oxide layer and an intrinsic amorphous silicon layer on the back side of a double-polished N-type crystalline silicon substrate.

[0125] S2, boron diffusion:

[0126] Boron diffusion is performed on the back side of the silicon substrate obtained in S1 to obtain a silicon substrate with a boron-doped polycrystalline silicon layer.

[0127] like Figure 3As shown, the silicon substrate with boron-doped polycrystalline silicon layer includes an N-type crystalline silicon substrate 10, and a tunneling oxide layer 20, a P-type doped polycrystalline silicon layer 31, and a BSG layer 40 sequentially deposited on the back side of the N-type crystalline silicon substrate 10. It should be noted that, during the boron diffusion, the intrinsic amorphous silicon layer on the back side S1 will form a P-type doped polycrystalline silicon layer 31 through diffusion doping.

[0128] S3, First graphical representation:

[0129] The back portion of the BSG layer of the silicon substrate II with the BSG layer obtained in step S2 is removed by laser to form a patterned groove, thereby obtaining a silicon substrate with a patterned groove.

[0130] like Figure 4 As shown, the silicon substrate with patterned grooves includes an N-type crystalline silicon substrate 10, and a tunneling oxide layer 20, a P-type doped polysilicon layer 31, and a BSG layer 40 sequentially deposited on the back side of the N-type crystalline silicon substrate 10; and a patterned groove is formed at the BSG layer 40 on the back side of the N-type crystalline silicon substrate 10.

[0131] S4, BSG coating removal and alkaline polishing:

[0132] Chain-type wet process removes BSG winding plating on the front side of the silicon substrate with patterned grooves in S3, and tank-type polishing removes the P-type doped polysilicon layer and tunneling oxide layer in the patterned groove area on the front side and the back side. The depth of the patterned groove is increased to 2-3 μm to obtain the silicon substrate.

[0133] like Figure 5 As shown, the silicon substrate includes an N-type crystalline silicon substrate 10, and a first tunneling oxide layer 20, a P-type doped polysilicon layer 31, and a BSG layer 40 sequentially deposited on the back side of the N-type crystalline silicon substrate 10, and the depth of the patterned groove extends into the interior of the N-type crystalline silicon substrate 10.

[0134] S5, Secondary Deposition:

[0135] A tunneling oxide layer and an intrinsic amorphous silicon layer are deposited on the back side of the silicon substrate obtained in step S4 to obtain a secondary deposited silicon substrate.

[0136] S6, Phosphorus diffusion:

[0137] Phosphorus diffusion is performed on the back side of the secondary deposited silicon substrate obtained in S5 to obtain a silicon substrate with a phosphorus-doped polycrystalline silicon layer.

[0138] like Figure 6As shown, the silicon substrate with phosphorus-doped polysilicon layers includes an N-type crystalline silicon substrate 10, and a tunneling oxide layer 20, a P-type doped polysilicon layer 31, a BSG layer 40, a tunneling oxide layer 20, an N-type doped polysilicon layer 32, and a PSG layer 41 sequentially deposited on the back side of the N-type crystalline silicon substrate 10; and a second tunneling oxide layer 21, an N-type doped polysilicon layer 32, and a PSG layer 41 are sequentially deposited at the patterned groove; it should be noted that, during the phosphorus diffusion, an N-type doped polysilicon layer 32 is formed on the intrinsic amorphous silicon layer 30 on the back side.

[0139] S7, Second Graphicalization

[0140] Step S6 yields an N-region PSG layer on a silicon substrate with a phosphorus-doped polycrystalline silicon layer. The remaining PSG layer is then removed to obtain the silicon substrate (e.g., ...). Figure 7 (As shown).

[0141] S8, PSG coating removal and texturing:

[0142] After the second patterning in S7, the N-type doped polysilicon layer and tunnel oxide layer in the N-region of the back side of the silicon substrate are removed, while the P-type doped polysilicon layer and tunnel oxide layer in the P-region of the back side are retained. The remaining front and back areas are then texturized to obtain the texturized silicon substrate (e.g., ...). Figure 8 (As shown).

[0143] S9. Deposit the nitrogen-doped titanium dioxide layer:

[0144] The surface of the substrate after S8 texturing is subjected to a cycle of precursor introduction, first purification, oxidation and second purification deposition, and annealing treatment is performed after the cycle deposition is completed to obtain the nitrogen-doped titanium dioxide layer; wherein, the precursor introduction includes the introduction of titanium-containing precursor gas; the oxidation includes the introduction of oxidant and nitrogen-containing gas.

[0145] S10, passivation treatment, printed electrodes, and light injection:

[0146] An aluminum oxide passivation layer, a silicon nitride passivation layer, and a silicon oxide passivation layer are deposited on the front side of the silicon substrate after S9 deposition; an aluminum oxide passivation layer and a silicon nitride passivation layer are deposited on the back side of the texturized silicon substrate; an N-region electrode is printed on the N-region of the back side of the passivated silicon substrate, and a P-region electrode is printed on the P-region of the back side of the passivated silicon substrate. The substrate is then sintered and light-injected to obtain the TBC cell.

[0147] The present invention will be further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0148] Preparation Example 1

[0149] This preparation example provides a texturized battery cell, which is prepared by the following steps:

[0150] S1, LPCVD1:

[0151] A tunneling oxide layer and an intrinsic amorphous silicon layer were deposited on the back side of a double-sided polished N-type crystalline silicon substrate using LPCVD. The thickness of the tunneling oxide layer was 1.8 nm, the deposition temperature was 580 °C, and the deposition time was 50 min. The thickness of the intrinsic amorphous silicon layer was 300 nm, the deposition temperature was 580 °C, and the deposition time was 75 min.

[0152] S2, Boron Expansion:

[0153] Boron diffusion was performed on the S1-treated solar cells; a mixed gas of BCl3, O2 and N2 was introduced, with a BCl3 flow rate of 300 sccm, an O2 flow rate of 850 sccm and an N2 flow rate of 2750 sccm, a deposition temperature of 900℃, a deposition time of 1.5 h, a BSG layer thickness of 50 nm, and a sheet resistance of 150 Ω.

[0154] S3, Graphical 1:

[0155] The S2-processed battery cells are sequentially patterned for the first time. Specifically, the first patterning step involves removing a portion of the BSG layer (subsequent Gap region + N region BSG layer) on the back side of the S2-processed battery cell to form a patterned groove. The removal is performed using a picosecond laser, and the depth of the patterned groove is 55 nm, and the width of the patterned groove is 550 μm.

[0156] S4, BSG removal + alkaline polishing:

[0157] The S3-treated solar cells are subjected to BSG removal and alkaline polishing. Specifically, the BSG removal and alkaline polishing steps are: chain wet process to remove the BSG coating on the front side, and tank polishing to remove the P-type doped polycrystalline silicon layer and tunnel oxide layer on the front side coating and the patterned groove area on the back side. The depth of the patterned groove is increased to 2.5 μm.

[0158] S5, LPCVD2:

[0159] A tunneling oxide layer and an intrinsic amorphous silicon layer were formed by double-sided deposition of S4-treated solar cells using LPCVD. The thickness of the tunneling oxide layer was 1.8 nm, the deposition temperature was 580 °C, and the deposition time was 50 min. The thickness of the intrinsic amorphous silicon layer was 300 nm, the deposition temperature was 580 °C, and the deposition time was 75 min.

[0160] S6, Phosphorus diffusion:

[0161] The S5-treated solar cells were subjected to phosphorus diffusion; a mixed gas of POCl3, O2, and N2 was introduced, with a POCl3 flow rate of 1500 sccm, an O2 flow rate of 800 sccm, and an N2 flow rate of 1000 sccm. The deposition temperature was 900℃, the deposition time was 2 h, the PSG layer thickness was 50 nm, and the sheet resistance was 30 Ω.

[0162] S7, Graphical Version 2:

[0163] The PSG layer in the N-region on the back of the battery cell after S6 is retained, and the PSG layer in the remaining region is removed; wherein, the removal is performed using a picosecond laser.

[0164] S8, PSG removal + fleece lining:

[0165] The N-type doped polycrystalline silicon layer and tunneling oxide layer in the N region of the back side of the cell after S7 processing are retained, and the P-type doped polycrystalline silicon layer and tunneling oxide layer in the P region of the back side are retained. The remaining front and back areas are texturized to obtain the texturized cell.

[0166] Example 1

[0167] This embodiment provides a solar cell with a nitrogen-doped titanium dioxide layer, which is prepared by the following steps:

[0168] (1) Cyclic deposition: The texturized battery cell obtained in Example 1 was subjected to cyclic deposition using the ALD method; the deposition temperature was 160°C and the deposition pressure was 300 mtor; the following steps were performed: ① precursor introduction, ② first purification, ③ oxidation, and ④ second purification. The number of cycles was repeated 250 times to obtain a nitrogen-doped titanium dioxide layer with a thickness of 20 nm.

[0169] ①Precursor introduction: Introduce TiCl4 precursor gas, set the pulse time of TiCl4 precursor gas to 1s, and the time for a single precursor introduction to 15s;

[0170] ② First purification: Introduce N2, set the N2 flow rate to 15slm, and the purification time for a single cycle to 15s;

[0171] ③ Oxidation: H2O and NH3 are introduced, and the pulse time of H2O is set to 0.5s; the pulse time of NH3 is set to 0.5s, and the time for a single oxidation is 15s;

[0172] ④ Second purification: Introduce N2, set the N2 flow rate to 15slm, and the purification time for each cycle to 15s.

[0173] (2) Annealing treatment:

[0174] N2 was introduced into the solar cell after deposition in step (1) at a flow rate of 2500 sccm, and annealed at 500°C for 1 h to obtain a solar cell with a nitrogen-doped titanium dioxide layer.

[0175] Example 2

[0176] This embodiment provides a solar cell with a nitrogen-doped titanium dioxide layer, which is prepared by the following steps:

[0177] (1) Cyclic deposition: The texturized battery cell obtained in Example 1 was subjected to cyclic deposition using the ALD method; the deposition temperature was 240°C and the deposition pressure was 400 mtor; the following steps were performed: ① precursor introduction, ② first purification, ③ oxidation, and ④ second purification. The number of cycles was 100, resulting in a nitrogen-doped titanium dioxide layer with a thickness of 15 nm.

[0178] ①Precursor introduction: Introduce TTIP precursor gas, set the pulse time of TTIP precursor gas to 0.1s, and the time for a single precursor introduction to 25s;

[0179] ② First purification: Introduce Ar, set the Ar flow rate to 10slm, and the purification time for a single purification cycle to 20s;

[0180] ③ Oxidation: Introduce O2 and NH3, set the pulse time of O2 to 0.1s; the pulse time of NH3 to 0.1s; and the time for a single oxidation is 25s.

[0181] ④ Second purification: Introduce Ar, set the Ar flow rate to 10 slm, and the purification time for a single purification cycle to 20 s.

[0182] (2) Annealing treatment:

[0183] N2 was introduced into the solar cell after deposition in step (1) at a flow rate of 1000 sccm, and annealed at 400°C for 2 h to obtain a solar cell with a nitrogen-doped titanium dioxide layer.

[0184] Example 3

[0185] This embodiment provides a solar cell with a nitrogen-doped titanium dioxide layer, which is prepared by the following steps:

[0186] (1) Cyclic deposition: The texturized battery cell obtained in Example 1 was subjected to cyclic deposition using the ALD method; the deposition temperature was 80°C and the deposition pressure was 200 mtor; the following steps were performed: ① precursor introduction, ② first purification, ③ oxidation, and ④ second purification. The number of cycles was 500, resulting in a nitrogen-doped titanium dioxide layer with a thickness of 25 nm.

[0187] ①Precursor introduction: Introduce TDMAT precursor gas, set the pulse time of TDMAT precursor gas to 2s, and the time for a single precursor introduction to 5s.

[0188] ② First purification: Introduce Ar, set the Ar flow rate to 20slm, and the purification time for a single purification cycle to 5s;

[0189] ③Oxidation: Introduce O2 and NH3, set the pulse time of O2 to 1s; the pulse time of NH3 to 1s, and the time for a single oxidation is 5s;

[0190] ④ Second purification: Introduce Ar, set the Ar flow rate to 20 slm, and the purification time for each cycle to 5 seconds.

[0191] (2) Annealing treatment:

[0192] N2 was introduced into the solar cell after deposition in step (1) at a flow rate of 5000 sccm, and annealed at 600°C for 0.5 h to obtain a solar cell with a nitrogen-doped titanium dioxide layer.

[0193] Example 4

[0194] This embodiment provides a solar cell with a nitrogen-doped titanium dioxide layer. The only difference from Embodiment 1 is that the deposition pressure is 100 mtor and the number of cycles is 600. The other steps are the same as in Embodiment 1.

[0195] Example 5

[0196] This embodiment provides a solar cell with a nitrogen-doped titanium dioxide layer. The only difference from Embodiment 1 is that the deposition pressure is 500 mtor and the number of cycles is 50. The other steps are the same as in Embodiment 1.

[0197] Example 6

[0198] This embodiment provides a battery cell with a nitrogen-doped titanium dioxide layer. The only difference from Embodiment 1 is that ① TiCl4 precursor gas is introduced and the pulse time of the TiCl4 precursor gas is set to 50ms. The other steps are the same as in Embodiment 1.

[0199] Example 7

[0200] This embodiment provides a battery cell with a nitrogen-doped titanium dioxide layer. The only difference from Embodiment 1 is that ① TiCl4 precursor gas is introduced and the pulse time of the TiCl4 precursor gas is set to 3s. The other steps are the same as in Embodiment 1.

[0201] Example 8

[0202] This embodiment provides a battery cell with a nitrogen-doped titanium dioxide layer. The only difference from Embodiment 1 is that, in step ③, H2O and NH3 are introduced, and the pulse time of H2O is set to 2s; the pulse time of NH3 is set to 50ms. The other steps are the same as in Embodiment 1.

[0203] Example 9

[0204] This embodiment provides a battery cell with a nitrogen-doped titanium dioxide layer. The only difference from Embodiment 1 is that, in step ③, H2O and NH3 are introduced, with the pulse time of H2O set to 50ms and the pulse time of NH3 set to 2s. The other steps are the same as in Embodiment 1.

[0205] Comparative Example 1

[0206] This comparative example provides a battery cell with a nitrogen-doped titanium dioxide layer. The only difference from Example 1 is that the annealing treatment in step (2) is not performed. The other steps are the same as in Example 1.

[0207] Comparative Example 2

[0208] This comparative example provides a battery cell with a titanium dioxide layer. The only difference from Example 1 is that NH3 is no longer introduced during the oxidation process. The other steps are the same as in Example 1.

[0209] Comparative Example 3

[0210] This comparative example provides a battery cell with a titanium nitride layer. The only difference from Example 1 is that, in process ③, H2O is no longer introduced, but CO is introduced instead. The other steps are the same as in Example 1.

[0211] Application Example 1

[0212] This application example provides a TBC battery, which is prepared by the following steps:

[0213] On the front side of the solar cell with a nitrogen-doped titanium dioxide layer obtained in Example 1, a 5 nm alumina passivation layer, an 85 nm silicon nitride passivation layer, and a 10 nm silicon oxide passivation layer are deposited; on the back side of the texturized silicon substrate, a 5 nm alumina passivation layer and an 85 nm silicon nitride passivation layer are deposited; an N-region electrode is printed on the N-region of the back side of the passivated silicon substrate, and a P-region electrode is printed on the P-region of the back side of the passivated silicon substrate. The cells are then sintered and light-injected to obtain the TBC solar cell.

[0214] Application Example 2

[0215] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 2. The other steps are completely the same as in Application Example 1.

[0216] Application Example 3

[0217] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 3. The other steps are completely the same as in Application Example 1.

[0218] Application Example 4

[0219] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 4. The other steps are completely the same as in Application Example 1.

[0220] Application Example 5

[0221] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 5. The other steps are completely consistent with Application Example 1.

[0222] Application Example 6

[0223] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 6. The other steps are completely consistent with Application Example 1.

[0224] Application Example 7

[0225] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 7. The other steps are completely consistent with Application Example 1.

[0226] Application Example 8

[0227] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 8. The other steps are completely consistent with Application Example 1.

[0228] Application Example 9

[0229] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 9. The other steps are completely the same as in Application Example 1.

[0230] Comparative Application Example 1

[0231] This comparative application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the texturized battery cell obtained in Preparation Example 1, while the other steps are completely consistent with Application Example 1.

[0232] Comparative Application Example 2

[0233] This comparative application example provides a TBC battery. The difference from Application Example 1 is that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the battery cell with a nitrogen-doped titanium dioxide layer obtained in Comparative Example 1. The other steps are completely the same as in Application Example 1.

[0234] Comparative Application Example 3

[0235] This comparative application example provides a TBC battery. The difference between this example and application example 1 is that the battery cell with a nitrogen-doped titanium dioxide layer obtained in example 1 is replaced with the battery cell with a titanium dioxide layer obtained in comparative example 2. The other steps are completely the same as in application example 1.

[0236] Comparative Application Example 4

[0237] This comparative application example provides a TBC battery. The difference from Application Example 1 is that the battery cell with a nitrogen-doped titanium dioxide layer obtained in Example 1 is replaced with the battery cell with a titanium nitride layer obtained in Comparative Example 3. The other steps are completely the same as in Application Example 1.

[0238] Test Example 1

[0239] Test samples: TBC batteries provided in Application Examples 1-9 and TBC batteries provided in Comparative Application Examples 1-4;

[0240] Test method: Electrical performance was tested using the Halm test system.

[0241] The specific test results are shown in Table 1:

[0242] Table 1

[0243]

[0244]

[0245] As shown in Table 1, the preparation method of the present invention can prepare a nitrogen-doped titanium dioxide layer with good electronic contact and appropriate optical properties. The TBC battery of the present invention introduces the nitrogen-doped titanium dioxide layer between the doped polycrystalline silicon layer and the metal electrode on the back side. The titanium dioxide layer can improve the thermal stability of the metallized polycrystalline silicon contacts and provide effective protection for the polycrystalline silicon layer, avoiding passivation degradation caused by sintering heat treatment, improving the passivation performance of the back side of the TBC battery, and improving the battery conversion efficiency.

[0246] The comparison between Application Example 1 and Application Examples 4-5 shows that during the cyclic deposition process, the deposition pressure and the number of cycles need to be controlled within a certain range. By controlling the pressure and the number of cycles, a more uniform, dense, and low-defect nitrogen-doped titanium dioxide layer can be obtained, thereby improving the battery conversion efficiency.

[0247] The comparison between Application Example 1 and Application Examples 6-7 shows that the pulse time of the TiCl4 precursor gas needs to be controlled within a certain range in order to obtain a more uniform, dense, and low-defect nitrogen-doped titanium dioxide layer and improve the battery conversion efficiency.

[0248] The comparison between Application Example 1 and Application Examples 8-9 shows that the pulse time of H2O and NH3 during the oxidation process needs to be controlled within a certain range in order to obtain a more uniform, dense, and low-defect nitrogen-doped titanium dioxide layer and improve the battery conversion efficiency.

[0249] The comparison between Application Example 1 and Comparative Application Example 1 shows that without depositing a nitrogen-doped titanium dioxide layer, the P-Poly in the P region and the N-Poly in the N region on the back of the TBC battery are in direct contact with the metal electrode, which easily leads to contact recombination between the metal electrode and P-Poly and N-Poly.

[0250] The comparison between Application Example 1 and Comparative Application Example 2 shows that without annealing, the nitrogen-doped titanium dioxide layer has certain defects, and the battery conversion efficiency is significantly reduced. Moreover, the effect of not annealing the nitrogen-doped titanium dioxide layer is worse than that of Comparative Application Example 1, which did not have annealing. This may be because the stress cannot be released when annealing is not performed, resulting in microcracks and defects. Alternatively, it may be that when annealing is not performed, nitrogen atoms (N) are not effectively integrated into the TiO2 lattice, but instead form recombination centers.

[0251] The comparison between Application Example 1 and Comparative Application Example 3 shows that nitrogen-doped titanium dioxide layer is more suitable for use as an interlayer between the doped polycrystalline silicon layer and the metal electrode on the back side of TBC battery, compared to pure titanium dioxide layer, in order to improve the passivation performance of the TBC battery back side. On the other hand, the undoped titanium dioxide layer may have some defects recombination and stress cracking problems due to oxygen vacancies becoming recombination centers. The effect of the pure titanium dioxide layer is even worse than that of the undoped Comparative Application Example 1.

[0252] The comparison between Application Example 1 and Comparative Application Examples 1, 3, and 4 shows that the titanium nitride layer has the worst effect. This may be because the titanium nitride layer has certain band mismatch, oxidation brittleness, and stress crack defects, so it is not suitable to be directly set between the doped polycrystalline silicon layer and the metal electrode on the back side as an intermediate layer.

[0253] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A TBC battery, characterized in that, The TBC battery includes a nitrogen-doped titanium dioxide layer; The nitrogen-doped titanium dioxide layer is located between the doped polycrystalline silicon layer and the metal electrode on the back side of the TBC battery. The nitrogen-doped titanium dioxide layer is prepared by the following steps: The surface of the substrate to be deposited is subjected to a cycle of deposition, including precursor introduction, first purification, oxidation, and second purification, followed by annealing after the cycle deposition is completed to obtain the nitrogen-doped titanium dioxide layer; wherein, the precursor introduction includes the introduction of a titanium-containing precursor gas; the oxidation includes the introduction of an oxidant and a nitrogen-containing gas.

2. The TBC battery according to claim 1, characterized in that, The nitrogen-doped titanium dioxide layer was prepared using the ALD method.

3. The TBC battery according to claim 1, characterized in that, The thickness of the nitrogen-doped titanium dioxide layer is 5~50 nm.

4. The TBC battery according to claim 1, characterized in that, The temperature of the cyclic deposition is 80~250℃; the pressure of the cyclic deposition is 200~400 mtor.

5. The TBC battery according to claim 1, characterized in that, The time for each single precursor introduction, first purification, oxidation, and second purification is 5–25 s.

6. The TBC battery according to claim 1, characterized in that, The number of cyclic depositions is 100 to 500.

7. The TBC battery according to claim 1, characterized in that, The titanium-containing precursor gas includes any one or a combination of at least two of titanium tetrachloride, tetraisopropyl titanate, tetra(dimethylamino)titanium, or tetra(ethylmethylamino)titanium.

8. The TBC battery according to claim 1, characterized in that, The pulse duration of the titanium-containing precursor gas is 0.1~2 s.

9. The TBC battery according to claim 1, characterized in that, The oxidant includes any one or a combination of at least two of water vapor, ozone, oxygen, or excited-state oxygen molecules.

10. The TBC battery according to claim 1, characterized in that, The nitrogen-containing gas includes ammonia.

11. The TBC battery according to claim 1, characterized in that, The pulse duration of the oxidant is 0.1~1 s.

12. The TBC battery according to claim 1, characterized in that, The pulse duration of the nitrogen-containing gas is 0.1~1s.

13. The TBC battery according to claim 1, characterized in that, The first purification and the second purification each independently include the introduction of purification gas for purification treatment.

14. The TBC battery according to claim 13, characterized in that, The purification gas includes nitrogen and / or argon.

15. The TBC battery according to claim 13, characterized in that, The flow rate of the purified gas is 10~20 slm.

16. The TBC battery according to claim 1, characterized in that, The time for each of the first and second purification processes is 5 to 20 seconds.

17. The TBC battery according to claim 1, characterized in that, The annealing temperature is 400~600℃; the annealing time is 0.5~2 h.

18. The TBC battery according to claim 1, characterized in that, The annealing process includes the use of nitrogen gas.

19. The TBC battery according to claim 18, characterized in that, The flow rate of the nitrogen gas is 1000~5000 sccm.

20. The TBC battery according to claim 1, characterized in that, include: N-type crystalline silicon substrate; The back surface of the N-type crystalline silicon substrate includes a P-region, an N-region, and an isolation region located between the P-region and the N-region, with the P-region and N-region being spaced apart. The P-region includes, from the inside out, a tunneling oxide layer, a P-type doped polycrystalline silicon layer, a nitrogen-doped titanium dioxide layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer. The N-region includes, from the inside out, a tunneling oxide layer, an N-type doped polycrystalline silicon layer, a nitrogen-doped titanium dioxide layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer. A P-region electrode is disposed in the P-region, and an N-region electrode is disposed in the N-region. The front side of the N-type crystalline silicon substrate has a pyramidal textured surface; the front side of the N-type crystalline silicon substrate includes an aluminum oxide passivation layer, a silicon nitride passivation layer, and a silicon oxide passivation layer arranged from the inside out.

21. A method for preparing a TBC battery according to claim 20, characterized in that, include: (1) Deposit a tunneling oxide layer and an intrinsic amorphous silicon layer on the back side of an N-type crystalline silicon substrate; (2) Boron diffusion is performed on the back side of the silicon substrate obtained in step (1) to form a boron-doped polycrystalline silicon layer; (3) The silicon substrate of boron diffusion in step (2) is subjected to the following steps in sequence: first patterning, BSG removal, alkaline polishing, deposition of tunneling oxide layer and intrinsic amorphous silicon layer, phosphorus diffusion, second patterning, PSG removal, texturing, deposition of nitrogen-doped titanium dioxide layer, passivation treatment, electrode printing and light injection to obtain the TBC battery. The nitrogen-doped titanium dioxide layer is prepared by the following steps: The surface of the substrate to be deposited is subjected to a cycle of deposition, including precursor introduction, first purification, oxidation, and second purification, followed by annealing after the cycle deposition is completed to obtain the nitrogen-doped titanium dioxide layer; wherein, the precursor introduction includes the introduction of a titanium-containing precursor gas; the oxidation includes the introduction of an oxidant and a nitrogen-containing gas.

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