Solar cell and method for manufacturing the same

Abstract

The present invention provides a solar cell and a method for manufacturing a solar cell. The solar cell includes a solar cell according to at least some embodiments of the present disclosure, and includes a silicon substrate, a first passivation layer provided on the first side of the silicon substrate, and a first doping conductive layer provided on the first passivation layer such that the first passivation layer is located between the silicon substrate and the first doping conductive layer. The first doping conductive layer contains oxygen and carbon and contains Si-O chemical bonds and Si-C chemical bonds.

Description

[Technical Field]

[0001] This application claims priority to Chinese Patent Application No. 202310322839.6, filed on March 29, 2023, with the title of the invention "Solar Cell and Method for Manufacturing the Same," and hereby incorporates the contents disclosed in said Chinese Patent Application as part of this application.

[0002] This disclosure relates to solar cells and methods for manufacturing solar cells. [Background technology]

[0003] Crystalline silicon heterojunction batteries are semiconductor devices capable of converting solar energy into electrical power for output. Typically, heterojunction batteries are manufactured using an n-type silicon substrate, which includes the silicon substrate, two passivation layers on either side of the silicon substrate, and doping conductive layers on each of the passivation layers.

[0004] The manufacturing process involves depositing hydrogenated amorphous silicon layers on both sides of a textured silicon substrate, depositing phosphorus and boron-doped silicon layers on the surfaces of the hydrogenated amorphous silicon layers, depositing a transparent conductive ITO layer on the surface of the doped silicon layers, and finally forming electrodes on the ITO layer. Heterojunction batteries have many advantages, including high battery efficiency, no decay, fewer process steps, and low energy consumption in the manufacturing process (all temperatures are below 300 degrees Celsius). Currently, the main factor limiting heterojunction batteries from capturing a large market share is their slightly higher manufacturing cost compared to other solar cell products. Therefore, improving the photoelectric conversion efficiency of heterojunction batteries and enhancing their cost-effectiveness remains the direction for their development. [Overview of the Initiative] [Means for solving the problem]

[0005] At least some embodiments of the present disclosure provide a solar cell comprising a silicon substrate, a first passivation layer provided on a first side of the silicon substrate, and a first doping conductive layer provided on the first passivation layer such that the first passivation layer is located between the silicon substrate and the first doping conductive layer. The first doping conductive layer comprises oxygen and carbon and comprises Si-O chemical bonds and Si-C chemical bonds.

[0006] For example, in some embodiments, the total molar content of carbon and oxygen is 20-30%.

[0007] For example, in some embodiments, the first doping conductive layer contains silicon, oxygen, carbon, and hydrogen, and the molar content of carbon is proportional to 3-15%.

[0008] For example, in some embodiments, carbon is present by forming Si-C chemical bonds, C-C chemical bonds, C-O chemical bonds, and C-H chemical bonds, with the molar ratios of Si-C, C-C, C-O, and C-H chemical bonds relative to the total carbon content being 40% to 60%, 30% to 50%, 5% to 18%, and 2% to 10%, respectively.

[0009] For example, in some embodiments, the first doping conductive layer contains silicon, oxygen, carbon, and hydrogen, with the molar content of oxygen being 10-30%.

[0010] For example, in some embodiments, oxygen is present by forming Si-O chemical bonds, C-O chemical bonds, and P-O chemical bonds, with the molar ratios of Si-O, C-O, and P-O chemical bonds relative to the total oxygen content being 70% to 90%, 6% to 18%, and 2% to 10%, respectively.

[0011] For example, in some embodiments, the band gap width of the first doping conductive layer is in the range of 1.9 to 2.4 eV.

[0012] For example, in some embodiments, the thickness of the first doping conductive layer is in the range of 6 to 14 nm.

[0013] For example, in some embodiments, the molar content of carbon in the first doping conductive layer gradually decreases, the molar content of oxygen in the first doping conductive layer gradually increases, and the molar content of the doping element in the first doping conductive layer gradually decreases in the direction toward the silicon substrate.

[0014] For example, in some embodiments, the doping element content of the first doped conductive layer is 2 × 10 18 ~3×10 21 Each atom is within the range of a cubic centimeter.

[0015] For example, in some embodiments, at least a portion of the silicon component of the first doped conductive layer is crystallized.

[0016] For example, in some embodiments, the crystallinity of the first doped conductive layer is in the range of 40% to 70%.

[0017] For example, in some embodiments, the first doped conductive layer is a hydrogenated amorphous silicon layer in which crystallized silicon is embedded. The first doped conductive layer is a microcrystalline silicon layer, which can be said to be partially crystallized.

[0018] For example, in some embodiments, the crystallinity of the first doping conductive layer gradually decreases in the direction toward the silicon substrate.

[0019] For example, in some embodiments, the first doping conductive layer is an n-type conductive layer containing silicon, oxygen, carbon, hydrogen, and phosphorus.

[0020] For example, in some embodiments, the silicon substrate is an n-type silicon substrate.

[0021] For example, in some embodiments, the first doped conductive layer is a p-type conductive layer and contains silicon, oxygen, carbon, hydrogen, and boron.

[0022] For example, in some embodiments, this solar cell further includes a second doped conductive layer provided on the first doped conductive layer such that the first doped conductive layer is located between the first passivation layer and the second doped conductive layer.

[0023] For example, in some embodiments, the content of the doping element in the second doped conductive layer is within the range of 10 19 ~10 21 atoms per cubic centimeter. <0000\\089>

[0024] For example, in some embodiments, this solar cell further includes a second passivation layer provided on the second side of the silicon substrate, and a third doped conductive layer provided on the second passivation layer such that the second passivation layer is located between the silicon substrate and the third doped conductive layer. At least the first side is the light-receiving side.

[0025] At least some embodiments of the present disclosure provide a method for manufacturing a solar cell, including the steps of providing a silicon substrate, forming a first passivation layer on the first side of the silicon substrate, and forming a first doped conductive layer on the first passivation layer such that the first passivation layer is located between the silicon substrate and the first doped conductive layer. When forming the first doped conductive layer, an oxygen-containing reaction gas and a carbon-containing reaction gas are used so that the first doped conductive layer contains Si—O chemical bonds and Si—C chemical bonds.

[0026] For example, in some embodiments, the oxygen-containing reaction gas is one or more selected from N2O, O2, CO2, and CO.

[0027] For example, in some embodiments, the carbon-containing reaction gas is CH4, C2H6, C3H 10It is one or more species selected from the group consisting of , and C2H4.

[0028] For example, in some embodiments, when forming the first doped conductive layer, phosphine gas is used to dope the first doped conductive layer with phosphorus.

[0029] For example, in some embodiments, when forming the first doping conductive layer, PH3 gas and SiH4 gas are used, and the flow rate ratio of the PH3 gas to the SiH4 gas is 0.02 to 0.1.

[0030] For example, in some embodiments, a first doped conductive layer is formed using plasma-enhanced chemical vapor deposition, in which a high-frequency (RF) or very high-frequency (VHF) power supply is used as the plasma excitation source, and the energy density of the ion source is 100-600 mW / cm². 2 The deposition pressure is in the range of 0.4 to 5 Torr, and the deposition temperature is 130 to 230°C. [Brief explanation of the drawing]

[0031] [Figure 1] Figure 1 shows a portion of the light-receiving side of a solar cell. [Figure 2] Figure 2 shows a portion of the light-receiving side of another solar cell. [Figure 3] Figure 3 shows the effect of using gases with different oxygen / silicon ratios and carbon / silicon ratios on the phosphorus content in a microcrystalline silicon doped conductive layer when forming it. [Figure 4] Figure 4 shows a schematic diagram of a solar cell according to one embodiment of the present disclosure. [Figure 5] Figure 5 shows the thickness and band gap values ​​of four doped conductive layer samples formed using different reaction gases. [Figure 6] Figure 6 shows the phosphorus doping concentrations in samples 3 and 4 of Figure 5. [Figure 7]Figure 7 shows the results of analyzing carbon and silicon in the first doped conductive layer of the solar cell according to Embodiment 1 using X-ray photoelectron spectroscopy (XPS) spectra. [Figure 8] Figure 8 shows the results of analyzing carbon and silicon in the first doped conductive layer of the solar cell according to Embodiment 1 using X-ray photoelectron spectroscopy (XPS) spectra. [Figure 9] Figure 9 shows a performance comparison of solar cells according to Comparative Example 1 and Embodiment 2. [Modes for carrying out the invention]

[0032] The solar cell and its manufacturing method according to the embodiments of this disclosure will be described in detail below with reference to the drawings.

[0033] Figure 1 shows a portion of the light-receiving side of a solar cell. This solar cell is a silicon-based heterojunction cell. As shown in Figure 1, this solar cell includes a silicon substrate 101, an intrinsically hydrogenated amorphous silicon passivation layer 102 provided on one surface of the silicon substrate 101, and an amorphous silicon doped conductive layer 103 deposited on the intrinsically hydrogenated amorphous silicon passivation layer 102. The inner intrinsically hydrogenated amorphous silicon passivation layer passivates the surface of the silicon substrate 101, and the outer amorphous silicon doped conductive layer 103 bends the energy band through self-doping, completing the extraction and transport of corresponding carriers. The band gap of the amorphous silicon material is approximately 1.6 to 1.7 eV, and since it is a material similar to a direct band gap, the amorphous silicon layer has a strong absorption effect on short-wavelength light rays. When an amorphous silicon-doped conductive layer 103 is used on the light-receiving side of a heterojunction battery, current is clearly lost due to light absorption by the amorphous silicon-doped conductive layer 103. Reducing light absorption by using a wide-bandwidth material on the light-receiving side of a heterojunction battery is an effective way to improve the conversion efficiency of the battery.

[0034] Figure 2 shows a portion of the light-receiving side of another solar cell. As shown in Figure 2, this solar cell includes a silicon substrate 201, an intrinsically hydrogenated amorphous silicon passivation layer 202 provided on one surface of the silicon substrate 201, and a microcrystalline silicon doped conductive layer 203 deposited on the intrinsically hydrogenated amorphous silicon passivation layer 202. In the process of manufacturing the conductive layer, at least a portion of the amorphous silicon doped conductive layer is crystallized and converted into a microcrystalline silicon doped conductive layer 203. In this way, at least a portion of the direct bandgap material is converted into an indirect bandgap material, reducing the absorption of light rays, and the crystallized microcrystalline silicon doped conductive layer 203 can also increase the concentration of doping atoms. This technique is called silicon thin-film microcrystallization technology. For example, when forming a doped conductive layer by plasma chemical vapor deposition (PECVD), crystallization of the amorphous silicon doped conductive layer is achieved by increasing the H2 / SiH4 flow rate ratio, and the crystallization rate increases as the H2 / SiH4 flow rate ratio increases. However, since the band gap of the crystallized microcrystalline silicon-doped conductive layer 203 is close to that of crystalline silicon material, light absorption is also large. Furthermore, by introducing an oxygen-containing gas such as N2O when the microcrystalline silicon-doped conductive layer 203 is deposited, oxygen is introduced into the microcrystalline silicon-doped conductive layer 203, causing at least some of the silicon to form Si-O chemical bonds, and thus the band gap of the microcrystalline silicon-doped conductive layer 203 can be improved.

[0035] Figure 3 shows the effect of using gases with different oxygen / silicon ratios (O2 / SiH4) and carbon / silicon ratios (CH4 / SiH4) when forming the microcrystalline silicon doped conductive layer 203 on the phosphorus content in the microcrystalline silicon doped conductive layer 203. The oxygen / silicon ratio and carbon / silicon ratio of the gases can be broadly considered as the oxygen / silicon ratio and carbon / silicon ratio in the microcrystalline silicon doped conductive layer 203. As shown in Figure 3, the content of doping elements (e.g., phosphorus, boron) in the conductive layer gradually decreases as the oxygen content in the microcrystalline silicon doped conductive layer 203 increases. If the oxygen content is too high, it is unfavorable for carrier extraction and conduction by the microcrystalline conductive layer. For this reason, the oxygen content in the microcrystalline silicon doped conductive layer 203 cannot exceed a certain value. The oxygen content in the microcrystalline silicon doped conductive layer 203 controls the band gap width and the doping concentration of impurities in the conductive layer. A high oxygen content is necessary to reduce light absorption in the conductive layer and increase the band gap of the material, while a low oxygen content is necessary to improve the conductive ability of the conductive layer and increase the amount of doping impurities it contains.

[0036] Embodiments of this disclosure provide a solar cell including a microcrystalline silicon doped conductive layer. The doping of this microcrystalline silicon doped conductive layer with doping elements gives the conductive layer excellent conductivity, and the further inclusion of oxygen and carbon in this conductive layer results in a high band gap and low absorption rate to light. As shown in Figure 3, the carbon content in the conductive layer does not significantly affect the doping element content. By increasing the carbon content and adjusting the ratio of carbon to oxygen, it is possible to increase the band gap and reduce absorption to light while avoiding a decrease in the concentration of doping elements in the conductive layer due to excessively high oxygen content.

[0037] Figure 4 shows a schematic diagram of a solar cell according to one embodiment of the present disclosure. As shown in Figure 4, the solar cell includes a silicon substrate 301, a first passivation layer 302 provided on the first side of the silicon substrate 301, a first doping conductive layer 303 provided on the first passivation layer 302, a second doping conductive layer 304 provided on the first doping conductive layer 303, a first transparent conductive layer 308 provided on the second doping conductive layer 304, a first electrode 3091 provided on the first transparent conductive layer 308, a second passivation layer 305 provided on the second side of the silicon substrate 301, a third doping conductive layer 306 provided on the second passivation layer 305, a second transparent conductive layer 307 provided on the third doping conductive layer 306, and a second electrode 3092 provided on the second transparent conductive layer 307. This first side is the light-receiving side of the solar cell.

[0038] This silicon substrate 301 is an n-type silicon substrate 301. The first passivation layer 302 and the second passivation layer 305 are intrinsic hydrogenated amorphous silicon layers. The first doped conductive layer 303 is a hydrogenated microcrystalline silicon doped conductive layer doped with phosphorus atoms and contains Si-O chemical bonds and Si-C chemical bonds. The second doped conductive layer 304 is a hydrogenated amorphous silicon doped conductive layer doped with phosphorus atoms and basically does not contain Si-O chemical bonds and Si-C chemical bonds. The third doped conductive layer 306 is a hydrogenated amorphous silicon doped conductive layer doped with boron. The first transparent conductive layer 308 and the second transparent conductive layer 307 are ITO layers. The first electrode 3091 and the second electrode 3092 are silver electrodes.

[0039] In this first doped conductive layer 303, Si-Si chemical bonds, Si-O chemical bonds, and Si-C chemical bonds are used as network-forming elements in the conductive layer, hydrogen is used as a network modifier to saturate and passivate the dangling bonds in the conductive layer, and phosphorus atoms are used as doping elements to give the conductive layer excellent conductivity. This conductive layer has a wide band gap (e.g., Eg = 1.9~2.4 eV) and good carrier conduction capability. For example, the thickness of this first doped conductive layer 303 is in the range of 6~14 nm.

[0040] Since the first doped conductive layer 303 contains Si-O chemical bonds and Si-C chemical bonds, the introduction of carbon avoids a decrease in the concentration of doping elements in the conductive layer due to excessively high oxygen content, resulting in a conductive layer with a high band gap and low absorption rate to light, as well as excellent conductive performance.

[0041] The total carbon and oxygen content in the first doping conductive layer 303 may be in the range of 20-30%. The molar content ratio of carbon may be in the range of 3-15%. The molar content ratio of oxygen may be in the range of 10-30%. By increasing the total carbon and oxygen content in the conductive layer, the band gap width of the conductive layer can be increased and the absorption of incident light rays can be reduced. The total carbon and oxygen content in the conductive layer can be maintained, the carbon content in the conductive layer can be increased, the oxygen content in the conductive layer can be decreased, and the phosphorus doping concentration in the conductive layer can be increased.

[0042] Carbon can be present by forming Si-C chemical bonds, C-C chemical bonds, C-O chemical bonds, and C-H chemical bonds, and the molar ratios of these chemical bonds in the total carbon content may be within the ranges of 40%-60%, 30%-50%, 5%-18%, and 2%-10%, respectively.

[0043] Oxygen can exist by forming Si-O, C-O, and P-O chemical bonds, with the molar ratios of these chemical bonds in the total oxygen content being 70%-90%, 6%-18%, and 2%-10%, respectively.

[0044] The carbon, oxygen, and silicon content in the first doping conductive layer 303 may change gradually. For example, in the direction toward the silicon substrate 301, the molar content of carbon in the first doping conductive layer 303 gradually decreases, the molar content of oxygen in the first doping conductive layer 303 gradually increases, and the molar content of the doping elements in the first doping conductive layer 303 gradually decreases. For example, the phosphorus content in the first doping conductive layer 303 is 2 × 10⁻⁶. 18 ~3×10 21 The range may be within one atom per cubic centimeter.

[0045] In this disclosure, a microcrystalline silicon doped conductive layer refers to a silicon conductive layer in which at least a portion of the silicon component is crystallized. For example, at least a portion of the silicon component of the first doped conductive layer 303 may be crystallized, and the crystallization rate may be in the range of 40% to 70%. The crystallization rate of the first doped conductive layer 303 may gradually decrease in the direction toward the silicon substrate 301. In this embodiment, the first doped conductive layer 303 is a hydrogenated amorphous silicon layer in which crystallized silicon is embedded.

[0046] The second doping conductive layer 304 may be an amorphous conductive layer with a high concentration of phosphorus doping. The second doping conductive layer 304 provides good coverage of the first doping conductive layer 303, and a decrease in phosphorus atom concentration due to the high-temperature process in subsequent processes can be avoided.

[0047] However, this disclosure is not limited thereto. The silicon substrate 301 may be a p-type silicon substrate 301. The first passivation layer and / or the second passivation layer 305 may be other types of passivation layers. For example, the first passivation layer 302 and the second passivation layer 305 may be configured as a passivation stack, and an amorphous silicon layer and a hydrogenated silicon layer may be provided in order in the direction away from the silicon substrate 301. The first doping conductive layer 303 is a hydrogenated microcrystalline silicon doping conductive layer doped with boron atoms and includes Si-O chemical bonds and Si-C chemical bonds. Furthermore, the second doping conductive layer 304 may be omitted. Also, the third doping conductive layer 306 is a hydrogenated microcrystalline silicon doping conductive layer, similar to the first doping conductive layer 303, and can include Si-O chemical bonds and Si-C chemical bonds, which is particularly advantageous when the second side is also the light-receiving side of the solar cell.

[0048] Embodiments of this disclosure provide a method for manufacturing solar cells that can be used in the manufacture of solar cells as described above. This method includes the following steps.

[0049] In step S11, the silicon substrate 301 is provided.

[0050] In step S12, a first passivation layer 302 and a second passivation layer 305 are formed on two opposing surfaces of the silicon substrate 301, respectively.

[0051] In step S13, a first doping conductive layer 303 is formed on the first passivation layer 302 on the first side of the silicon substrate 301 using an oxygen-containing reaction gas and a carbon-containing reaction gas, so that the first doping conductive layer contains Si-O chemical bonds and Si-C chemical bonds.

[0052] In step S14, a second doping conductive layer 304 is formed on the first doping conductive layer 303 of the silicon substrate 301.

[0053] In step S15, a third doping conductive layer 306 is formed on the second passivation layer 305 on the second side of the silicon substrate 301.

[0054] In step S16, transparent conductive layers are formed on the first doping conductive layer 303 and the third doping conductive layer 306, respectively.

[0055] In step S17, electrodes, such as silver electrodes, are formed on the transparent conductive layers on both sides.

[0056] In step S13, the oxygen-containing reaction gas is selected from the group consisting of N2O, O2, CO2, and CO, and the carbon-containing reaction gas is selected from the group consisting of CH4, C2H6, C3H 10 and C2H4. Further, phosphine gas may be used to dope phosphorus into the first doping conductive layer. More specifically, PH3 gas and SiH4 gas can be used, and the flow rate ratio of PH3 gas to SiH4 gas may be 0.02 to 0.1, thereby at least partially crystallizing the formed hydrogenated amorphous silicon layer.

[0057] In one example, the first doping conductive layer is formed using the PECVD method, where a high-frequency power source (RF) or an ultra-high-frequency power source (VHF) is used as the plasma excitation source, and the energy density of the ion source is 100 to 600 mW / cm 2 and the deposition pressure is within the range of 0.4 to 5 Torr, and the deposition temperature is 130 to 230 °C.

[0058] Figure 5 shows the thickness and band gap values ​​of four doped conductive layer samples formed using different reaction gases. Each sample was formed on a silicon substrate polished by the PECVD method. The reaction conditions for sample 1 were a deposition pressure (i.e., the pressure inside the reaction chamber where the sample was located at the time of deposition) of 133 Pa, a high-frequency power of 2000 W, reaction gases of SiH4, H2, and PH3 with flow rates of 2000 sccm, 2000 sccm, and 200 sccm, respectively, and a deposition time of 8 min. The reaction conditions for sample 2 were a deposition pressure of 153 Pa, a high-frequency power of 4000 W, reaction gases of SiH4, H2, and PH3 with flow rates of 1000 sccm, 50 SLM, and 100 sccm, respectively, and a deposition time of 15 min. The reaction conditions for Sample 3 were a deposition pressure of 163 Pa, a high-frequency power of 4500 W, reaction gases of SiH4, H2, PH3, and CO2, with flow rates of 1000 sccm, 50 SLM, 100 sccm, and 2000 sccm, respectively, and a deposition time of 15 min. The reaction conditions for Sample 4 were a deposition pressure of 183 Pa, a high-frequency power of 5000 W, reaction gases of SiH4, H2, PH3, CH4, and CO2, with flow rates of 1000 sccm, 50 SLM, 100 sccm, 500 sccm, and 1000 sccm, respectively, and a deposition time of 15 min.

[0059] As can be seen from Figure 5, Samples 3 and 4 have wide band widths.

[0060] Figure 6 shows the phosphorus doping concentrations in samples 3 and 4 in Figure 5. As shown in Figure 6, at a doping depth of 0 to approximately 0.13 μm, the doping concentration of sample 4 is approximately 1 × 10⁻⁶. 20 The concentration is atoms / cubic centimeter, and the doping concentration in Sample 3 is approximately 1 × 10⁻¹⁶. 19 The concentration is per atom / cubic centimeter, and sample 4 has a higher concentration of phosphorus doping than sample 3.

[0061] The performance of solar cells according to Comparative Example 1, Comparative Example 2, and the three embodiments of this disclosure (Embodiment 1, Embodiment 2, and Embodiment 3) will be compared below.

[0062] The solar cell used in Comparative Example 1 was fabricated using the following procedure.

[0063] In step S21, a silicon substrate is provided. This silicon substrate is a single-crystal n-type silicon substrate with a volume resistivity of 3.5 Ω·cm.

[0064] In step S22, a surface texturing treatment is performed on the silicon substrate. Specifically, the silicon substrate is anisotropically etched using a sodium hydroxide alkali solution with a mass fraction of 5%, to obtain a textured surface of the silicon substrate with a reflectivity of 12% or less.

[0065] In step S23, a first passivation layer and a second passivation layer are formed on two opposing surfaces of the silicon substrate, respectively. Specifically, using the PECVD method, hydrogenated amorphous silicon layers with a thickness of 10 nm were formed on two opposing surfaces of the silicon substrate as the first and second passivation layers. The pseudo-open circuit voltage of the silicon substrate after double-sided passivation reached 750 mV.

[0066] In step S24, a phosphorus-doped hydrogenated amorphous silicon layer is formed as the first doping conductive layer on the first passivation layer on the first side of the silicon substrate. Specifically, the phosphorus-doped hydrogenated amorphous silicon layer is deposited on the hydrogenated amorphous silicon layer on one side of the silicon substrate using a reaction gas consisting of SiH4, H2, and PH3 by the PECVD method. The thickness of this phosphorus-doped hydrogenated amorphous silicon layer is 15 nm.

[0067] In step S25, a boron-doped hydrogenated amorphous silicon layer is formed as a third doping conductive layer on the second passivation layer on the second side of the silicon substrate. Specifically, the boron-doped hydrogenated amorphous silicon layer is deposited on the surface of the hydrogenated amorphous silicon film on the other side of the silicon substrate using a reaction gas consisting of SiH4, H2, and B2H6 by the PECVD method. The thickness of this boron-doped hydrogenated amorphous silicon layer is 15 nm.

[0068] In step S26, a PVD apparatus is used to deposit 80 nm thick ITO transparent conductive film layers on the phosphorus-doped hydrogenated amorphous silicon layer and the boron-doped hydrogenated amorphous silicon layer on both sides of the silicon substrate.

[0069] In step S27, a low-temperature silver paste is used to print onto the ITO transparent conductive film layers on both sides of the silicon substrate and then cured at 255°C to form silver electrodes.

[0070] The solar cell according to Comparative Example 2 was fabricated in the same manner as the solar cell according to Comparative Example 1, except for step S24. In the manufacturing process of the solar cell according to Comparative Example 2, in step S24, a phosphorus-doped hydrogenated microcrystalline silicon layer is deposited on a hydrogenated amorphous silicon layer on one side of the silicon substrate by PECVD using a reaction gas consisting of SiH4, H2, and PH3 as the first doping conductive layer. In this step, the chamber pressure is set to 153 Pa, the high-frequency power is set to 4000 W, and 1000 sccm of SiH4, 50 SLM of H2, and 100 sccm of PH3 are introduced. The thickness of this phosphorus-doped hydrogenated microcrystalline silicon layer is 15 nm. Next, using a reaction gas consisting of SiH4, H2, and PH3, a phosphorus-doped hydrogenated amorphous silicon layer is deposited on this phosphorus-doped hydrogenated microcrystalline silicon layer by PECVD to form an additional second doping conductive layer. The thickness of this phosphorus-doped hydrogenated amorphous silicon layer is 3 nm.

[0071] The solar cell according to Embodiment 1 was manufactured in the same manner as the solar cell according to Comparative Example 1, except for step S24. In the manufacturing process for the solar cell according to this embodiment, in step S24, a phosphorus-doped hydrogenated microcrystalline carbon oxide silicon layer is deposited on the first passivation layer on one side of the silicon substrate by PECVD using a reaction gas consisting of SiH4, H2, CO2, CH4, and PH3 to form the first doping conductive layer. The thickness of this phosphorus-doped hydrogenated microcrystalline carbon oxide silicon layer is 15 nm. Next, a phosphorus-doped hydrogenated amorphous silicon layer is deposited on this hydrogenated microcrystalline carbon oxide silicon layer by PECVD using a reaction gas consisting of SiH4, H2, and PH3 to form an additional second doping conductive layer. The thickness of this phosphorus-doped hydrogenated amorphous silicon layer is 3 nm.

[0072] Figures 7 and 8 show the analysis results of carbon and silicon in the first doped conductive layer of the solar cell of Embodiment 1 using X-ray photoelectron spectroscopy spectra, respectively. As shown in Figures 7 and 8, this first doped conductive layer contains carbon, silicon, and oxygen, and the oxygen and some of the carbon form Si-O chemical bonds and Si-C chemical bonds.

[0073] The solar cell according to Embodiment 2 was manufactured in the same manner as the solar cell according to Embodiment 1, except for step S24. In the manufacturing process for producing the solar cell according to this embodiment, in step S24, a phosphorus-doped hydrogenated microcrystalline carbon oxide silicon layer is deposited on the first passivation layer on one side of the silicon substrate by PECVD using a reaction gas consisting of SiH4, H2, CO2, CH4, and PH3 to form a first doped conductive layer. The flow rate ratio of CH4 to SiH4 is gradually increased from 0.05 to 1.5 from the inner position closer to the silicon substrate to the outer position further away from the silicon substrate, while the flow rate ratio of CO2 to SiH4 is gradually decreased from 1.5 to 0.5. This forms a first doped conductive layer in which the total carbon and oxygen content does not change, but the carbon content gradually increases and the oxygen content gradually decreases in the direction away from the silicon substrate. The thickness of this phosphorus-doped hydrogenated microcrystalline carbon oxide silicon layer is 15 nm. Next, using a reaction gas consisting of SiH4, H2, and PH3, a phosphorus-doped hydrogenated amorphous silicon layer is deposited on this hydrogenated microcrystalline carbon oxide silicon layer by PECVD to form an additional second doping conductive layer. The thickness of this phosphorus-doped hydrogenated amorphous silicon layer is 3 nm.

[0074] The solar cell according to Embodiment 3 was manufactured in the same manner as the solar cell according to Embodiment 1, except for step S24. In the manufacturing process for the solar cell of Embodiment 3, in step S24, a phosphorus-doped hydrogenated microcrystalline carbon oxide silicon layer is deposited on the first passivation layer on one side of the silicon substrate by PECVD using a reaction gas consisting of SiH4, H2, CO2, CH4, and PH3 to form the first doping conductive layer. The thickness of this phosphorus-doped hydrogenated microcrystalline carbon oxide silicon layer is 15 nm. However, in this solar cell of Embodiment 3, a phosphorus-doped hydrogenated amorphous silicon layer is not deposited on this hydrogenated microcrystalline carbon oxide silicon layer to form an additional second doping conductive layer.

[0075] Figure 9 shows a performance comparison of the solar cells of Comparative Example 1, Comparative Example 2, Embodiment 1, Embodiment 2, and Embodiment 3. As shown in Figure 9, when the cutoff current, open-circuit voltage, curve factor, and photoelectric conversion efficiency of the solar cell according to Comparative Example 1 are all 100%, the cutoff current, open-circuit voltage, curve factor, and photoelectric conversion efficiency of the solar cell according to Comparative Example 2 are 97.81%, 100.40%, 101.501%, and 99.67%, respectively. The cutoff current, open-circuit voltage, curve factor, and photoelectric conversion efficiency of the solar cell according to Embodiment 1 are 101.10%, 100.20%, 101%, and 102.64%, respectively. The cutoff current, open-circuit voltage, curve factor, and photoelectric conversion efficiency of the solar cell according to Embodiment 2 are 101.20%, 100.30%, 101.46%, and 102.98%, respectively. The cutoff current, open-circuit voltage, curve factor, and photoelectric conversion efficiency of the solar cell according to Embodiment 3 are 101.30%, 100.30%, 100.76%, and 101.34%, respectively. The solar cell of Comparative Example 2 has a higher open-circuit voltage and curve factor compared to the solar cell of Comparative Example 1, but lower short-circuit current and photoelectric conversion efficiency. In Comparative Example 2, since the concentration of active phosphorus atoms in the first doping conductive layer is not increased by doping with oxygen and carbon, the passivation performance and curve factor are improved. However, the band gap value of the phosphorus-doped microcrystalline silicon film layer is small, which has an absorption effect on light in the wider wavelength range, thus reducing the short-circuit current. For batteries with excellent passivation, such as heterojunction batteries, current plays a decisive role in the photoelectric conversion efficiency of the battery. As can be seen from Figure 9, simply microcrystallizing does not easily improve battery efficiency, so it is necessary to further dope the first doping conductive layer with oxygen and carbon to increase the band gap value of the microcrystalline film layer. The solar cells of Embodiments 1 to 3 have higher short-circuit current, open-circuit voltage, curve factor, and photoelectric conversion efficiency compared to the solar cell of Comparative Example 1. Furthermore, the solar cells of Embodiments 1 to 3 have higher short-circuit current and photoelectric conversion efficiency compared to the solar cell of Comparative Example 2.Therefore, using a phosphorus-doped hydrogenated microcrystalline carbon oxide silicon layer containing Si-O and Si-C chemical bonds as the first doping conductive layer is advantageous for improving the performance of the battery cell compared to using a phosphorus-doped hydrogenated amorphous silicon layer or a phosphorus-doped hydrogenated microcrystalline silicon layer that does not contain Si-O and Si-C chemical bonds as the first doping conductive layer. The solar cell according to Embodiment 2 has a higher short-circuit current, open-circuit voltage, curve factor, and photoelectric conversion efficiency compared to the solar cell according to Embodiment 1. Therefore, a first doping conductive layer in which the carbon content gradually increases and the oxygen content gradually decreases in the direction away from the silicon substrate is advantageous for improving the performance of the battery cell. The solar cell according to Embodiment 1 has a higher photoelectric conversion efficiency compared to the solar cell according to Embodiment 3. Therefore, forming a second doping conductive layer is advantageous for improving the performance of the battery cell.

[0076] The scope of the present invention is limited not by the embodiments described above, but by the appended claims and equivalents.

Claims

1. It is a solar cell, A silicon substrate and A first passivation layer provided on the first side of the silicon substrate, A first doping conductive layer, comprising a first doping conductive layer provided on the first passivation layer such that the first passivation layer is located between the silicon substrate and the first doping conductive layer, The first doping conductive layer contains oxygen and carbon, and includes Si-O chemical bonds and Si-C chemical bonds, in a solar cell.

2. The solar cell according to claim 1, wherein the total molar content of carbon and oxygen is 20 to 30%.

3. The solar cell according to claim 1 or 2, wherein the first doping conductive layer contains silicon, oxygen, carbon, and hydrogen, and the molar content of the carbon is proportional to 3 to 15%.

4. The solar cell according to any one of claims 1 to 3, wherein the carbon exists by forming Si-C chemical bonds, C-C chemical bonds, C-O chemical bonds and C-H chemical bonds, and the molar ratios of the Si-C chemical bonds, C-C chemical bonds, C-O chemical bonds and C-H chemical bonds to the total carbon content are 40% to 60%, 30% to 50%, 5% to 18%, and 2% to 10%, respectively.

5. The solar cell according to any one of claims 1 to 4, wherein the first doping conductive layer contains silicon, oxygen, carbon, and hydrogen, and the molar content of the oxygen is proportional to 10 to 30%.

6. The solar cell according to any one of claims 1 to 5, wherein the oxygen is present by forming Si-O chemical bonds, C-O chemical bonds and P-O chemical bonds, and the molar ratios of the Si-O chemical bonds, C-O chemical bonds and P-O chemical bonds to the total oxygen content are 70% to 90%, 6% to 18%, and 2% to 10%, respectively.

7. The solar cell according to any one of claims 1 to 6, wherein the band gap width of the first doping conductive layer is in the range of 1.9 to 2.4 eV.

8. The solar cell according to any one of claims 1 to 7, wherein the thickness of the first doping conductive layer is in the range of 6 to 14 nm.

9. The solar cell according to any one of claims 1 to 8, wherein, in the direction toward the silicon substrate, the molar content of carbon in the first doping conductive layer gradually decreases, the molar content of oxygen in the first doping conductive layer gradually increases, and the molar content of the doping element in the first doping conductive layer gradually decreases.

10. The content of the doping element in the first doped conductive layer is 2 × 10 １８ ~3 x 10 ２１ A solar cell according to any one of claims 1 to 9, wherein the atoms are within the range of one atom per cubic centimeter.

11. The solar cell according to any one of claims 1 to 10, wherein the first doping conductive layer has at least a portion of its silicon component crystallized.

12. The solar cell according to claim 11, wherein the crystallinity of the first doped conductive layer is in the range of 40% to 70%.

13. The solar cell according to claim 12, wherein the first doping conductive layer is a hydrogenated amorphous silicon layer in which crystallized silicon is embedded.

14. The solar cell according to any one of claims 11 to 13, wherein the crystallinity of the first doping conductive layer gradually decreases in the direction toward the silicon substrate.

15. The solar cell according to any one of claims 1 to 14, wherein the first doping conductive layer is an n-type conductive layer and contains silicon, oxygen, carbon, hydrogen, and phosphorus.

16. The solar cell according to claim 15, wherein the silicon substrate is an n-type silicon substrate.

17. The solar cell according to any one of claims 1 to 5, 7 to 14, wherein the first doping conductive layer is a p-type conductive layer and contains silicon, oxygen, carbon, hydrogen, and boron.

18. A solar cell according to any one of claims 1 to 17, further comprising a second doping conductive layer, the second doping conductive layer provided on the first doping conductive layer such that the first doping conductive layer is located between the first passivation layer and the second doping conductive layer.

19. The content of the doping element in the second doping conductive layer is 10 １９ ~10 ２１ The solar cell according to claim 18, wherein the atoms are within the range of one atom per cubic centimeter.

20. A second passivation layer provided on the second side of the silicon substrate, A third doping conductive layer, the third doping conductive layer further includes a third doping conductive layer provided on the second passivation layer such that the second passivation layer is located between the silicon substrate and the third doping conductive layer, The solar cell according to any one of claims 1 to 19, wherein at least the first side is a light-receiving side.

21. A method for manufacturing solar cells. The steps include providing a silicon substrate and The steps include forming a first passivation layer on the first side of the silicon substrate, The step of forming a first doping conductive layer includes forming the first doping conductive layer on the first passivation layer such that the first passivation layer is located between the silicon substrate and the first doping conductive layer, A method for manufacturing a solar cell, comprising using an oxygen-containing reaction gas and a carbon-containing reaction gas when forming the first doped conductive layer, such that the first doped conductive layer contains Si-O chemical bonds and Si-C chemical bonds.

22. The oxygen-containing reaction gas is N ２ O, O ２ CO ２ The manufacturing method according to claim 21, wherein one or more types are selected from and CO.

23. The carbon-containing reaction gas is CH ４ , C ２ H ６ , C ３ H １０ and C ２ H ４ The production method according to claim 21 or 22, which is one or more selected from

24. The manufacturing method according to any one of claims 21 to 23, wherein when forming the first doping conductive layer, phosphine gas is used to dope the first doping conductive layer with phosphorus.

25. When forming the first doping conductive layer, PH ３ Gas and SiH ４ Using gas, the PH ３ gas and the SiH ４ The manufacturing method according to any one of claims 21 to 24, wherein the gas flow rate ratio is 0.02 to 0.

1.

26. The first doped conductive layer is formed using plasma-enhanced chemical vapor deposition, a high-frequency (RF) power supply or a very high-frequency (VHF) power supply is used as the plasma excitation source, and the energy density of the ion source is 100 to 600 mW / cm². ２ The manufacturing method according to any one of claims 21 to 25, wherein the deposition pressure is in the range of 0.4 to 5 Torr and the deposition temperature is 130 to 230°C.

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