WO2022134994A1

WO2022134994A1 - Solar cell, production method, and photovoltaic module

Info

Publication number: WO2022134994A1
Application number: PCT/CN2021/132488
Authority: WO
Inventors: 李华; 刘继宇
Original assignee: 泰州隆基乐叶光伏科技有限公司
Priority date: 2020-12-25
Filing date: 2021-11-23
Publication date: 2022-06-30
Also published as: CN114695583A; CN114695583B

Abstract

The present disclosure relates to the technical field of solar photovoltaics, and provides a solar cell, a production method, and a photovoltaic module. The solar cell comprises: a silicon substrate, a first titanium nitride layer, and a second titanium nitride layer; the first titanium nitride layer has hole selectivity, and the second titanium nitride layer has electron selectivity. The first titanium nitride layer and the second titanium nitride layer are located on the light-facing surface and the backlight surface of the silicon substrate, respectively; or are located in a first region and a second region of the backlight surface of the silicon substrate, respectively. In the present application, the first titanium nitride layer and the second titanium nitride layer are used for charge carrier separation, and the silicon substrate does not need to be doped, thereby avoiding adverse factors caused by doping techniques. At the same time, since the production process of the first titanium nitride layer and the second titanium nitride layer is generally at the relatively low temperature of less than or equal to 500 degrees Celsius, impurities are reduced, thus reducing additional recombination centers brought in by impurities so that the service life of minority carriers is long, and further reducing the recombination rate of the solar cell and increasing the efficiency of the solar cell.

Description

Solar cell and production method, photovoltaic module

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of the Chinese patent application with the application number 202011569070.0 and titled "Solar Cells and Production Methods, Photovoltaic Modules" filed with the China Patent Office on December 25, 2020, the entire contents of which are incorporated into this application by reference .

technical field

The present disclosure relates to the technical field of solar photovoltaics, and in particular, to a solar cell, a production method, and a photovoltaic assembly.

Background technique

With the continuous consumption of traditional energy and its negative impact on the environment, the development and utilization of solar energy, as a pollution-free and renewable energy source, has developed rapidly, especially solar cells with high conversion efficiency have become focus of the current research.

A distinguishing feature of solar cells is their ability to direct light-generated electrons and holes into asymmetrically conductive paths, that is, to separate charge carriers and then collect them through the positive and negative electrodes, thereby outputting electrical energy. Traditional crystalline silicon solar cells have two structures, homojunction and heterojunction. Solar cells with homojunction structure use diffusion doping to form p-type hole selective contact and n-type electron selective contact; The solar cell with junction structure uses intrinsic amorphous silicon as passivation layer, p-type heavily doped amorphous silicon as hole selective contact, and n-type heavily doped amorphous silicon as electron selective contact, so that The photogenerated electrons generated after receiving light in the P-N junction area move to the selective contact of electrons, and the photogenerated holes move to the selective contact of holes, thereby forming positive and negative charge accumulation on both sides of the -PN junction, generating photoelectromotive force and generating current.

However, in the current scheme, on the one hand, the doping technology of the silicon matrix is bound to cause unfavorable factors such as Auger recombination, narrowing of the forbidden band, bulk/surface recombination, and free carrier absorption; on the other hand, the doping of the silicon matrix Impurities often need to be diffused and annealed at higher temperatures, and high-temperature processes will introduce more impurities and affect the lifetime of minority carriers, resulting in lower solar cell efficiency.

Overview

The present disclosure provides a solar cell, a production method, and a photovoltaic module, aiming at solving the problems of complex process and low efficiency caused by high preparation temperature of the solar cell.

In a first aspect, embodiments of the present disclosure provide a solar cell, the solar cell comprising:

a silicon substrate, a first titanium nitride layer and a second titanium nitride layer;

the first titanium nitride layer has hole selectivity, and the second titanium nitride layer has electron selectivity;

the first titanium nitride layer and the second titanium nitride layer are respectively located on the light-facing surface and the backlight surface of the silicon substrate;

or,

The first titanium nitride layer and the second titanium nitride layer are respectively located in the first area and the second area of the backlight surface of the silicon substrate.

Optionally, the work function of the first titanium nitride layer is 4.7-5.5 electron volts, and the work function of the second titanium nitride layer is 4.0-4.6 electron volts.

Optionally, the ratio of the number of nitrogen atoms to the number of titanium atoms in the first titanium nitride layer is greater than 1.5, and the ratio of the number of nitrogen atoms to the number of titanium atoms in the second titanium nitride layer is 0.7- in the range of 0.9.

Optionally, the thicknesses of the first titanium nitride layer and the second titanium nitride layer are both 1-500 nanometers.

Optionally, the second titanium nitride layer includes titanium nitride, and a doping element doped in the titanium nitride, the doping element including: any one of arsenic, aluminum, phosphorus and zinc one or more.

Optionally, the solar cell further includes:

a first electrode and a second electrode;

The first electrode is arranged on the side of the first titanium nitride layer away from the silicon substrate, and the second electrode is arranged on the side of the second titanium nitride layer away from the silicon substrate;

Wherein, the first electrode and the second electrode are both selected from: aluminum electrode, silver electrode, aluminum/silver composite electrode, nickel/copper/tin composite electrode, chromium/palladium/silver composite electrode and nickel/copper/silver composite electrode Any of the composite electrodes.

Optionally, a first passivation tunneling layer is disposed between the silicon substrate and the first titanium nitride layer;

And/or, a second passivation tunneling layer is disposed between the silicon substrate and the second titanium nitride layer.

Optionally, the thicknesses of the first passivation tunneling layer and the second passivation tunneling layer are both 0.1-5 nanometers;

The materials of the first passivation tunneling layer and the second passivation tunneling layer include: intrinsic amorphous silicon, silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, hydrogenated amorphous silicon, carbide Any one or more of silicon.

Optionally, when the first titanium nitride layer and the second titanium nitride layer are located in the first area and the second area of the backlight surface of the silicon substrate, respectively, the first titanium nitride layer The layer is electrically insulated from the second titanium nitride layer.

Optionally, the thickness of the first titanium nitride layer is 2-20 nanometers;

The thickness of the second titanium nitride layer is 1-15 nanometers.

Optionally, the solar cell further comprises: a metal layer in the contact area;

The contact area metal layer is disposed on the side of the first titanium nitride layer away from the silicon substrate;

Wherein, the first titanium nitride layer is disposed on the light-facing surface of the silicon substrate, and the thickness of the first titanium nitride layer is less than 5 nanometers.

In a second aspect, embodiments of the present disclosure provide a method for producing a solar cell, the method comprising:

The first titanium nitride layer and the second titanium nitride layer are respectively prepared on the light-facing surface and the backlight surface of the silicon substrate; or, the first nitride layer is respectively prepared on the first area and the second area of the backlight surface of the silicon substrate. a titanium layer and a second titanium nitride layer;

The first titanium nitride layer has hole selectivity, and the second titanium nitride layer has electron selectivity.

Optionally, the step of preparing the first titanium nitride layer includes:

Using a titanium chloride precursor as a titanium source and ammonia as a nitrogen source, thermal atomic deposition is performed in a temperature range of 300-500 degrees Celsius to form the first titanium nitride layer.

Optionally, the step of preparing the second titanium nitride layer includes:

The organic precursor of titanium is used as the titanium source, and the ammonia gas is used as the nitrogen source, and thermal atomic deposition is performed in the temperature range of 100-300 degrees Celsius to generate the second titanium nitride layer;

or,

Using titanium palladium, in an atmosphere of nitrogen and ammonia, physical vapor deposition reaction sputtering is performed to generate the second titanium nitride layer;

Wherein, the organic precursor of titanium includes: any one or more of TDMAT, TDEAT and TEMAT.

Optionally, the generation rate of the second titanium nitride layer is 5-20 times the generation rate of the first titanium nitride layer.

Optionally, the first titanium nitride layer and the second titanium nitride layer are respectively prepared on the light-facing surface and the backlight surface of the silicon substrate; or, the first area and the second area on the backlight surface of the silicon substrate are respectively prepared After the steps of the first titanium nitride layer and the second titanium nitride layer, the method further includes:

A first electrode is provided on the side of the first titanium nitride layer away from the silicon substrate;

A second electrode is provided on the side of the second titanium nitride layer away from the silicon substrate.

Optionally, after the steps of preparing the first titanium nitride layer and the second titanium nitride layer on the light-facing surface and the backlight surface of the silicon substrate, respectively, the method further includes:

preparing a contact area metal layer on the side of the first titanium nitride layer away from the silicon substrate;

annealing the first titanium nitride layer and the metal layer in the contact area, and the first titanium nitride layer reacts with the metal in the metal layer in the contact area to form a titanium nitride composite film;

In a third aspect, an embodiment of the present disclosure provides a photovoltaic assembly, wherein the photovoltaic assembly includes any one of the aforementioned solar cells.

Based on the above-mentioned solar cell, production method, and photovoltaic module, the present application has the following beneficial effects: the solar cell in the present application includes: a silicon substrate, a first titanium nitride layer and a second titanium nitride layer; the first titanium nitride layer has a hollow space hole selectivity, the second titanium nitride layer has electron selectivity; the first titanium nitride layer and the second titanium nitride layer are respectively located on the light-facing surface and the backlight surface of the silicon substrate; or, the first titanium nitride layer and the The titanium dioxide layers are respectively located in the first area and the second area of the backlight surface of the silicon substrate. In the present application, the first titanium nitride layer with hole selectivity and the second titanium nitride layer with electron selectivity are used for carrier separation without doping the silicon substrate to form a carrier for separation Hole-selective contact and electron-selective contact, thus avoiding unfavorable factors such as Auger recombination, band gap narrowing, bulk/surface recombination, and free carrier absorption caused by doping technology. The production process of the titanium layer and the second titanium nitride layer is usually less than or equal to 500°C, and the temperature is lower, which reduces impurities, thereby reducing the extra recombination centers brought in due to impurities, making the lifetime of minority carriers longer, Further, the recombination rate of the solar cell is reduced, and the efficiency of the solar cell is improved.

Brief Description of Drawings

In order to illustrate the technical solutions of the embodiments of the present disclosure more clearly, the following briefly introduces the drawings that are used in the description of the embodiments of the present disclosure. Obviously, the drawings in the following description are only some embodiments of the present disclosure. , for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative labor.

FIG. 1 shows a schematic structural diagram of a first solar cell in an embodiment of the present disclosure;

FIG. 2 shows a schematic structural diagram of a second type of solar cell in an embodiment of the present disclosure;

FIG. 3 shows a schematic structural diagram of a third type of solar cell in an embodiment of the present disclosure;

FIG. 4 shows a schematic structural diagram of a fourth solar cell in an embodiment of the present disclosure;

FIG. 5 shows a schematic structural diagram of a fifth solar cell in an embodiment of the present disclosure;

FIG. 6 shows a schematic structural diagram of a sixth solar cell in an embodiment of the present disclosure;

FIG. 7 shows a schematic structural diagram of a seventh solar cell in an embodiment of the present disclosure;

FIG. 8 shows a schematic structural diagram of an eighth solar cell in an embodiment of the present disclosure;

FIG. 9 shows a flow chart of steps of a method for producing a solar cell in an embodiment of the present disclosure; and

FIG. 10 shows a flow chart of steps of another method for producing a solar cell in an embodiment of the present disclosure.

Detailed Description

The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, but not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

A solar cell, a production method, and a photovoltaic photovoltaic module provided by the present disclosure are described in detail below by listing several specific embodiments.

FIG. 1 shows a schematic structural diagram of a first solar cell provided by an embodiment of the present disclosure. Referring to FIG. 1 , the solar cell may include: a silicon substrate 10 , a first titanium nitride layer (TiN _x ) 20 and a second nitrogen Titanium oxide layer (TiN _x ) 30, it should be noted that x in the chemical formula can be determined by those skilled in the art according to actual needs. Wherein, the first titanium nitride layer 20 and the second titanium nitride layer 30 may be respectively located on the light-facing surface and the backlight surface of the silicon substrate 10 to form a double-sided solar cell. FIG. 2 shows a schematic structural diagram of a second type of solar cell provided by an embodiment of the present disclosure. Referring to FIG. 2 , the first titanium nitride layer 20 and the second titanium nitride layer 30 may also be located on the back side of the silicon substrate 10 , respectively. The first region and the second region form a back contact solar cell.

Since the first titanium nitride layer 20 has hole selectivity, which facilitates the collection of holes generated in the silicon substrate 10, the second titanium nitride layer 30 has electron selectivity, which facilitates the collection of electrons generated in the silicon substrate 10. Therefore, , the silicon substrate 10 in the solar cell generates carriers under the irradiation of sunlight, the holes in the carriers move to the first titanium nitride layer 20 with hole selectivity, and the electrons in the carriers move to the first titanium nitride layer 20 with hole selectivity. The electron-selective second titanium nitride layer 30 moves to effectively separate and extract carriers. Since holes are collected on the side close to the first titanium nitride layer 20, electrons are collected near the second titanium nitride layer. 30, therefore, the first titanium nitride layer 20 and the second titanium nitride layer 30 may serve as a carrier separation structure or a power generation structure. The silicon substrate 10 does not need to be doped to form hole-selective contacts and electron-selective contacts for carrier separation, thereby avoiding Auger recombination, band gap narrowing, and bulk/surface recombination caused by doping techniques. and free carrier absorption and other unfavorable factors, at the same time, the production process of the first titanium nitride layer 20 and the second titanium nitride layer 30 is usually less than or equal to 500 ° C, the temperature is lower, and impurities are reduced, thereby reducing the amount of impurities due to impurities. The extra recombination center brought in increases the lifetime of minority carriers and reduces the recombination rate of the solar cell, thereby improving the efficiency of the solar cell, and eliminating the high temperature treatment process in the solar cell process, thereby improving the efficiency of the solar cell. battery performance.

In addition, since titanium nitride is a metalloid material, the first titanium nitride layer and the second titanium nitride layer are both conductive and can be used as electrodes for current collection and conduction. Titanium has high thermal and chemical stability, so that the first and second titanium nitride layers with high electrical conductivity and low contact resistivity can be utilized as electrodes for carrier transport and collection , without the need to separately arrange electrodes, thereby simplifying the structure of the battery and greatly simplifying the fabrication process of the solar cell.

In an embodiment of the present disclosure, a solar cell includes: a silicon substrate, a first titanium nitride layer, and a second titanium nitride layer; the first titanium nitride layer has hole selectivity, and the second titanium nitride layer has a hole selectivity. Electron selectivity; the first titanium nitride layer and the second titanium nitride layer are respectively located on the light-facing surface and the backlight surface of the silicon substrate; or, the first titanium nitride layer and the second titanium nitride layer are respectively located on the backlight of the silicon substrate the first area and the second area of the surface. In the present application, the first titanium nitride layer with hole selectivity and the second titanium nitride layer with electron selectivity are used for carrier separation without doping the silicon substrate to form a carrier for separation Hole-selective contact and electron-selective contact, thus avoiding unfavorable factors such as Auger recombination, band gap narrowing, bulk/surface recombination, and free carrier absorption caused by doping technology. The production process of the titanium layer and the second titanium nitride layer is usually less than or equal to 500°C, and the temperature is lower, which reduces impurities, thereby reducing the extra recombination centers brought in due to impurities, making the lifetime of minority carriers longer, Further, the recombination rate of the solar cell is reduced, and the efficiency of the solar cell is improved.

Optionally, since the interfaces between the first titanium nitride layer and the second titanium nitride layer and the silicon substrate have different conduction band offsets and valence band offsets, separation and extraction of carriers can be promoted. Wherein, the first titanium nitride layer is titanium nitride with high work function, and the work function of the first titanium nitride layer can be 4.7-5.5 electron volts. If the silicon substrate is n-type, the high work function nitridation The titanium layer/n-type silicon substrate interface has a small conduction band offset and a large valence band offset, so the first titanium nitride layer can act as a selective contact for carriers with hole conduction and electron blocking effect; the second titanium nitride layer is titanium nitride with a lower work function, and the work function of the second titanium nitride layer can be 4.0-4.6 electron volts. If the silicon substrate is n-type, the low work function nitridation The titanium layer/n-type silicon substrate interface has a large conduction band offset and a small valence band offset, so the second titanium nitride layer can serve as a selective contact for carriers with electron conduction and hole blocking effect.

Optionally, the ratio of the number of nitrogen atoms to the number of titanium atoms in the first titanium nitride layer is greater than 1.5, so that the first titanium nitride layer has better hole selectivity; nitrogen in the second titanium nitride layer The ratio of the number of atoms to the number of titanium atoms is in the range of 0.7-0.9, so that the second titanium nitride layer has better electron selectivity.

In the embodiments of the present disclosure, as the thickness of the titanium nitride layer increases, the work function of the titanium nitride layer will also increase accordingly. Therefore, a titanium nitride layer with a larger thickness is more conducive to the selective collection of holes and the Therefore, the thickness of the first titanium nitride layer can be set larger than the thickness of the second titanium nitride layer.

Optionally, the thickness of the first titanium nitride layer is 2-20 nanometers, the first titanium nitride layer within this thickness range has more excellent hole selectivity, and the hole transport distance is small; the second The thickness of the titanium nitride layer is 1-15 nanometers, and the second titanium nitride layer within the thickness range has more excellent electron selectivity and small electron transport distance.

Optionally, the first titanium nitride layer may include titanium nitride, and doped nitrogen elements additionally doped in the titanium nitride, so that the content of nitrogen elements in the first titanium nitride layer is higher than that of the originally prepared nitrogen The content of nitrogen element in the titanium nitride layer makes the first titanium nitride layer have good hole selectivity, and the stoichiometric ratio of nitrogen element and titanium element in the titanium nitride layer is not specifically limited.

In addition, boron difluoride (BF ₂ ) can also be used as a doping source to dope the first titanium nitride layer, so that the first titanium nitride layer has good hole selectivity.

Optionally, the second titanium nitride layer may include titanium nitride, and a doping element doped in the titanium nitride may include: any one or more of arsenic, aluminum, phosphorus and zinc The doping element makes the second titanium nitride layer have good electron selectivity, and the stoichiometric ratio of nitrogen element and titanium element in the titanium nitride is not specifically limited, and the arsenic in the second titanium nitride layer is not limited. The corresponding stoichiometric ratios of aluminum, phosphorus and zinc are also not specifically limited.

In the embodiments of the present disclosure, the above-mentioned doping elements may be doped by means of ion implantation. For example, ion implantation of phosphorus can form phosphorus-induced dipoles through interfacial reactions, thereby significantly reducing the work function of the titanium nitride film, making the second titanium nitride layer have better electron selectivity; nitrogen ion implantation can improve nitrogen The nitrogen-titanium ratio of the titanium nitride film is improved, thereby improving the work function of the titanium nitride film, so that the first titanium nitride layer has better hole selectivity.

It should be noted that when the titanium nitride layer is doped to obtain the second titanium nitride layer, due to environmental factors, oxygen or carbon will inevitably be doped into the titanium nitride layer, and the doped oxygen or carbon will inevitably It will also make the second titanium nitride layer have good electron selectivity, wherein the corresponding stoichiometric ratio of oxygen and carbon in the second titanium nitride layer is also not specifically limited.

Optionally, the solar cell further includes: a first electrode and a second electrode. FIG. 3 shows a schematic structural diagram of a third solar cell provided by an embodiment of the present disclosure. Referring to FIG. 3 , the first titanium nitride layer 20 and the third The titanium dioxide layer 30 is respectively located on the light-facing surface and the backlight surface of the silicon substrate 10 , the first electrode 40 is disposed on the side of the first titanium nitride layer 20 away from the silicon substrate 10 , and the second electrode 50 is disposed on the second titanium nitride layer 10 . The layer 30 is far from the side of the silicon substrate 10 to realize the collection of corresponding carriers; FIG. 4 shows a schematic structural diagram of the fourth solar cell provided by the embodiment of the present disclosure. Referring to FIG. 4 , the first titanium nitride layer 20 and The second titanium nitride layer 30 is located in the first area and the second area of the backlight surface of the silicon substrate 10, respectively. The first electrode 40 is disposed on the side of the first titanium nitride layer 20 away from the silicon substrate 10, and the second electrode 50 is disposed on the side of the first titanium nitride layer 20 away from the silicon substrate 10. The side of the second titanium nitride layer 30 away from the silicon substrate 10 can collect corresponding carriers. Therefore, in the case where the first electrode 40 and the second electrode 50 are provided in the solar cell, the collection and conduction of current are performed through the first electrode 40 and the second electrode 50 .

Optionally, the materials of the first electrode 40 and the second electrode 50 can be any one or more of silver, gold, copper, nickel, aluminum, tin, chromium and palladium. Both electrodes 50 can be selected from any one of aluminum electrodes, silver electrodes, aluminum/silver composite electrodes, nickel/copper/tin composite electrodes, chromium/palladium/silver composite electrodes, and nickel/copper/silver composite electrodes.

In the embodiment of the present disclosure, when exposed to light, the silicon substrate 10 acts as a light absorbing layer to generate electron-hole pairs. Since the first titanium nitride layer 20 has a hole selection effect, the holes are transported to the first titanium nitride layer 20 . In the titanium nitride layer 20, it is then led out by the first electrode 40 corresponding to it; since the second titanium nitride layer 30 has an electron selection effect, the electrons are transported into the second titanium nitride layer 30, and then are carried out by the corresponding first electrode 40. The two electrodes 50 are led out, and the electrons and holes are separated by the solar cell, so that a potential difference is generated between the first electrode 40 and the second electrode 50, that is, a voltage is generated, thereby converting light energy into electrical energy.

It should be noted that the first titanium nitride layer 20 is disposed between the first electrode 40 and the silicon substrate 10, and the second titanium nitride layer 30 is disposed between the second electrode 50 and the silicon substrate 10, so that the silicon substrate can be avoided. In direct contact with the electrode, the surface recombination rate on the surface of the solar cell is greatly reduced, and the efficiency of the solar cell is improved.

FIG. 5 shows a schematic structural diagram of a fifth solar cell provided by an embodiment of the present disclosure. Referring to FIG. 5 , a first passivation tunneling layer 70 is provided between the silicon substrate 10 and the first titanium nitride layer 20 . The silicon substrate A second passivation tunneling layer 80 is arranged between 10 and the second titanium nitride layer 30; FIG. 6 shows a schematic structural diagram of the sixth solar cell provided by the embodiment of the present disclosure. Referring to FIG. 6, the silicon substrate 10 and A first passivation tunneling layer 70 is disposed between the first titanium nitride layer 20, and no passivation tunneling layer is disposed between the silicon substrate 10 and the second titanium nitride layer 30; FIG. 7 shows an embodiment of the present disclosure A schematic diagram of the structure of the seventh solar cell is provided. Referring to FIG. 7 , a second passivation tunneling layer 80 is provided between the silicon substrate 10 and the second titanium nitride layer 30 , the silicon substrate 10 and the first titanium nitride layer 20 There is no passivation tunneling layer in between. The first passivation tunneling layer 70 and the second passivation tunneling layer 80 mainly play the role of interface passivation and the role of transporting carriers, so that carriers are collected through the tunneling layers according to the tunneling effect.

It should be noted that, only one of the first passivation tunneling layer and the second passivation tunneling layer may be provided, or both, and the size, thickness and material thereof may also be determined according to actual needs. For example, the first titanium nitride layer has hole selectivity, usually the fixed charge density of the first titanium nitride layer is very high, and the first passivation tunneling layer may not be disposed between the silicon substrate and the first titanium nitride layer, The second titanium nitride layer has electron selectivity, and usually the fixed charge density of the second titanium nitride layer is not particularly high. A second passivation tunneling layer can be arranged between the silicon substrate and the second titanium nitride layer, using To reduce interface recombination.

Optionally, the thicknesses of the first passivation tunneling layer and the second passivation tunneling layer are both 0.1-5 nanometers, and the above thicknesses have excellent passivation performance, and the thicknesses are not too high to affect the absorption of carriers. The materials of the first passivation tunneling layer and the second passivation tunneling layer include: any of intrinsic amorphous silicon, silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, hydrogenated amorphous silicon, and silicon carbide One or more, the passivation tunneling layer of the above materials not only has a good passivation tunneling effect, but also is easy to prepare. For example, various structures of the solar cell in this application can be prepared at low temperature, hydrogenated amorphous silicon will not degrade, and the passivation performance of hydrogenated amorphous silicon is very good; the preparation of silicon oxide is more industrialized The potential of promotion, silicon oxide can be easily prepared before growing titanium oxide, and the passivation performance of silicon oxide is also relatively good.

Optionally, when the first titanium nitride layer and the second titanium nitride layer are located in the first area and the second area of the backlight surface of the silicon substrate, respectively, the first titanium nitride layer and the second titanium nitride layer are Electrical insulation between titanium layers.

Referring to FIG. 2 or FIG. 4 , the first titanium nitride layer 20 and the second titanium nitride layer 30 are spaced apart on the backlight surface of the silicon substrate 10 , and there is an electrical connection between the first titanium nitride layer 20 and the second titanium nitride layer 30 . Insulation, the electrical insulation can be achieved by arranging voids, dielectric layers or insulating layers. Furthermore, it is not easy to leak electricity, and the recombination of carriers can be reduced, so as to improve the photoelectric conversion efficiency. Specific isolation methods include using laser isolation, chemical isolation, etc., and can also use a patterned mask to assist in isolation.

In the embodiment of the present disclosure, when the first titanium nitride layer and the second titanium nitride layer are located in the first area and the second area of the backlight surface of the silicon substrate, respectively, the size of the above-mentioned first area and the second area is Without specific limitation, for example, the region corresponding to the titanium nitride layer with minority carrier selectivity in both the first titanium nitride layer and the second titanium nitride layer is more selective than the titanium nitride layer with majority carrier selectivity. The size of the area corresponding to the layer is large.

Optionally, the solar cell may further include: a metal layer in the contact area. FIG. 8 shows a schematic structural diagram of an eighth solar cell provided by an embodiment of the present disclosure. Referring to FIG. 8 , the metal layer 90 in the contact area is provided on the first nitridation The titanium layer 20 is on the side away from the silicon substrate 10 , wherein the first titanium nitride layer 20 is disposed on the light-facing surface of the silicon substrate 10 , and the thickness of the first titanium nitride layer 20 is less than 5 nanometers.

It should be noted that, since titanium nitride is a metalloid material, the first titanium nitride layer and the second titanium nitride layer with high electrical conductivity and low contact resistivity can be used for carrier transport and collected electrodes without the need for separate electrodes. However, since the devices contacted by titanium nitride show strong parasitic absorption in the near-infrared range, which limits the current density of the light-receiving surface, it is preferable to use the titanium nitride layer directly as the electrode of the battery for the backlight surface of the solar cell. That is, the entire second titanium nitride is applied to the backlight surface of the solar cell, thereby simplifying the structure and process flow of the solar cell. On the light-receiving surface of the solar cell, in order to reduce the parasitic absorption of titanium nitride, an ultra-thin first titanium nitride layer with a thickness of less than 5 nanometers and a metal layer in the contact area can be used, so that the After the annealing treatment of the metal layer in the contact area, the first titanium nitride layer can react with the metal in the metal layer in the contact area to form a titanium nitride composite film. On the one hand, titanium nitride can be used to passivate the surface of the silicon substrate to inhibit loading The surface recombination of the carriers; on the other hand, the carriers can be effectively separated and extracted, and the cell efficiency can be improved.

Optionally, the metal layer in the contact area can include any one or more of silver thin films, gold thin films, aluminum thin films, copper thin films and palladium thin films. The energy level of the titanium oxide layer is matched with the material, so that the open circuit voltage of the solar cell can be increased, so as to improve the photoelectric conversion efficiency of the solar cell.

Optionally, referring to FIGS. 2 and 4 , the light-facing surface of the silicon substrate 10 can be provided with a textured structure to increase the light trapping of the solar cell and increase the light absorption of the solar cell, and the silicon substrate 10 with the textured structure can be provided with a textured structure. The light-facing surface of the silicon substrate 10 is provided with a front passivation and anti-reflection layer 60, so as to passivate and reduce reflection on the light-facing surface of the silicon substrate 10, thereby improving the efficiency of the solar cell. In addition, the textured structure can also be provided on both sides of the silicon substrate 10 at the same time, and the shape of the remaining structural layers on the silicon substrate 10 is adapted to the textured structure of the light-facing side and the backlighting side of the silicon substrate 10, so that the back of the battery can also be set. Absorb light energy and improve light utilization.

The present disclosure also provides a method for producing a solar cell. Referring to FIG. 9 , it shows a flow chart of the steps of the method for producing a solar cell provided by an embodiment of the present disclosure. The method may include the following steps:

In step 101, a first titanium nitride layer and a second titanium nitride layer are respectively prepared on the light-facing surface and the backlight surface of the silicon substrate; The first titanium nitride layer and the second titanium nitride layer are described.

In this step, a silicon substrate can be obtained first, and then a first titanium nitride layer and a second titanium nitride layer are respectively prepared on the light-facing surface and the backlight surface of the silicon substrate; or, in the first area of the backlight surface of the silicon substrate and the second region to prepare a first titanium nitride layer and a second titanium nitride layer, respectively.

The first titanium nitride layer has hole selectivity, and the second titanium nitride layer has electron selectivity. In addition, the first titanium nitride layer and the second titanium nitride layer also have electrical conductivity, which can be directly used as Electrodes collect and conduct current.

Optionally, for the solar cell shown in FIG. 1 , after obtaining the silicon substrate 10 , the method may further include: texturing the silicon substrate 10 and cleaning.

Referring to FIG. 10 , a flow chart of steps of another method for producing a solar cell provided by an embodiment of the present disclosure is shown, and the method may include the following steps:

Step 201, respectively preparing a first titanium nitride layer and a second titanium nitride layer on the light-facing surface and the backlight surface of the silicon substrate; or, respectively preparing the first and second regions on the backlight surface of the silicon substrate The first titanium nitride layer and the second titanium nitride layer are described.

Optionally, the step of preparing the first titanium nitride layer in step 201 may specifically include:

Sub-step 2011 , using a titanium chloride precursor as a titanium source, using ammonia gas as a nitrogen source, and performing thermal atomic deposition in a temperature range of 300-500 degrees Celsius to form the first titanium nitride layer.

In this step, the first titanium nitride layer may be prepared by thermal atomic deposition.

Specifically, when thermal atomic deposition is used, a chloride precursor of titanium, such as any one of titanium tetrachloride (TiCl ₄ ), titanium trichloride (TiCl ₃ ) and titanium dichloride (TiCl ₂ ), can be used As the titanium source, ammonia gas (NH ₃ ) is used as the nitrogen source, and thermal atomic deposition is performed in the temperature range of 300-500 degrees Celsius, thereby forming the first titanium nitride layer.

Optionally, the step of preparing the second titanium nitride layer in step 201 may specifically include:

Sub-step 2012, using an organic precursor of titanium as a titanium source, using ammonia gas as a nitrogen source, and performing thermal atomic deposition in a temperature range of 100-300 degrees Celsius to generate the second titanium nitride layer; or, using titanium palladium and performing physical vapor deposition reactive sputtering in an atmosphere of nitrogen and ammonia to form the second titanium nitride layer.

In this step, thermal atomic deposition or physical vapor deposition reactive sputtering may be used to prepare the second titanium nitride layer.

Specifically, when thermal atomic deposition is used, organic precursors of titanium can be used, such as: TDMAT (tetrakis(dimethylamino)titanium), TDEAT (tetrakis(diethylamino)titanium) and TEMAT (tetrakis(ethylamino)titanium) Any one or more of base amino) titanium) is used as the titanium source, and ammonia gas is used as the nitrogen source, and thermal atomic deposition is performed in the temperature range of 100-300 degrees Celsius, thereby generating the second titanium nitride layer.

Wherein, the second titanium nitride layer formed by using TDMAT as the titanium source has higher oxygen content and carbon content, so that the electron selectivity of the second titanium nitride layer can be further improved.

Alternatively, when the physical vapor deposition reactive sputtering is used, titanium palladium may be used, and the physical vapor deposition reactive sputtering is performed with a power of 8 kilowatts in an atmosphere of nitrogen and ammonia gas, thereby forming the second titanium nitride layer.

Optionally, the formation rate of the second titanium nitride layer may be 5-20 times the formation rate of the first titanium nitride layer.

Optionally, the deposited titanium nitride layer can be annealed to adjust the work function of the titanium nitride thin film through different annealing atmospheres. Since the nitrogen concentration or more precisely nitrogen vacancies are the reason for the change of the work function of the material, during the annealing process of the titanium nitride layer, nitrogen vacancies will be generated in the titanium nitride layer, so that the electron density of states of the titanium nitride layer is increased, thereby Decreases the work function of the titanium nitride layer, while annealing in an oxygen-rich atmosphere results in an increase in the work function of the titanium nitride layer due to the filling of these nitrogen vacancies with oxygen.

Optionally, after the first titanium nitride layer and the second titanium nitride layer can be respectively prepared on the light-facing side and the backlight side of the silicon substrate, the contact area metal layer can be prepared on the side of the first titanium nitride layer away from the silicon substrate. , and perform annealing treatment on the first titanium nitride layer and the metal layer in the contact area, so that the first titanium nitride layer reacts with the metal in the metal layer in the contact area to form a titanium nitride composite film, wherein the first titanium nitride layer is set On the light-oriented surface of the silicon substrate, the thickness of the first titanium nitride layer is less than 5 nanometers.

In the embodiment of the present disclosure, during the annealing process, when the first titanium nitride layer reacts with the metal in the metal layer in the contact area, the metal layer in the contact area can completely react with the first titanium nitride layer to form a titanium nitride composite Therefore, there is no metal layer in the contact area in the final solar cell; the metal layer in the contact area can also partially react with the first titanium nitride layer to form a titanium nitride composite film, so that there is still a thickness in the final solar cell. The thinned contact area metal layer, correspondingly, the titanium nitride composite film is located between the silicon substrate and the contact area metal layer.

It should be noted that, since titanium nitride is a metalloid material, the first titanium nitride layer and the second titanium nitride layer with high electrical conductivity and low contact resistivity can be used for carrier transport and collected electrodes without the need for separate electrodes.

However, since the devices contacted by titanium nitride show strong parasitic absorption in the near-infrared range, which limits the current density of the light-receiving surface, it is preferable to use the titanium nitride layer directly as the electrode of the battery for the backlight surface of the solar cell. That is, the entire second titanium nitride layer is applied to the backlight surface of the solar cell, thereby simplifying the structure and process flow of the solar cell. On the light-receiving surface of the solar cell, in order to reduce the parasitic absorption of titanium nitride, an ultra-thin first titanium nitride layer with a thickness of less than 5 nanometers and a metal layer in the contact area can be used, so that the After the annealing treatment of the metal layer in the contact area, the first titanium nitride layer can react with the metal in the metal layer in the contact area to form a titanium nitride composite film. On the one hand, titanium nitride can be used to passivate the surface of the silicon substrate to inhibit loading The surface recombination of the carriers; on the other hand, the carriers can be effectively separated and extracted, and the cell efficiency can be improved.

Step 202 , providing a first electrode on the side of the first titanium nitride layer away from the silicon substrate.

In this step, after the first titanium nitride layer is prepared, a first electrode may be disposed on the side of the first titanium nitride layer away from the silicon substrate.

In the embodiment of the present disclosure, the first electrode may be prepared by screen printing. Specifically, the first low-temperature electrode paste is screen-printed on the first titanium oxide layer, and baked at a temperature less than or equal to 500° C. dry to get the first electrode.

It should be noted that, if the first titanium nitride layer in the solar cell is provided with a contact area metal layer on the side away from the silicon substrate, and after annealing treatment is performed on the first titanium nitride layer and the contact area metal layer, the first nitride The titanium layer reacts with the metal in the metal layer in the contact area to form a titanium nitride composite film, then the first electrode is arranged on the side of the titanium nitride composite film away from the silicon substrate, or when the metal layer in the contact area remains, the first electrode is It is arranged on the side of the metal layer in the contact area away from the titanium nitride composite film.

Step 203 , providing a second electrode on the side of the second titanium nitride layer away from the silicon substrate.

In this step, after the second titanium nitride layer is prepared, a second electrode may be disposed on the side of the second titanium nitride layer away from the silicon substrate.

In the embodiment of the present disclosure, the second electrode may be prepared by screen printing. Specifically, the second low-temperature electrode paste is screen-printed on the second titanium oxide layer, and dried at a temperature of less than or equal to 500°C, Get the second electrode.

It should be noted that, the above-mentioned parts of the solar cell and the production method of the solar cell can be referred to, and have the same or similar beneficial effects.

In addition, an embodiment of the present disclosure further provides a photovoltaic assembly, including any one of the aforementioned solar cells, and both sides of the solar cell may be provided with an encapsulation film, a cover plate, a back plate, and the like. It has the same or similar beneficial effects as the aforementioned solar cells.

The embodiments of the present disclosure have been described above in conjunction with the accompanying drawings, but the present disclosure is not limited to the above-mentioned specific embodiments, which are merely illustrative rather than restrictive. Under the inspiration of the present disclosure, many forms can be made without departing from the scope of the present disclosure and the protection scope of the claims, which all fall within the protection of the present disclosure.

Claims

A solar cell, characterized in that the solar cell comprises:

a silicon substrate, a first titanium nitride layer and a second titanium nitride layer;

the first titanium nitride layer has hole selectivity, and the second titanium nitride layer has electron selectivity;

the first titanium nitride layer and the second titanium nitride layer are respectively located on the light-facing surface and the backlight surface of the silicon substrate;

or,

The first titanium nitride layer and the second titanium nitride layer are respectively located in the first area and the second area of the backlight surface of the silicon substrate.
The solar cell according to claim 1, wherein the work function of the first titanium nitride layer is 4.7-5.5 electron volts, and the work function of the second titanium nitride layer is 4.0-4.6 electron volts.
The solar cell according to claim 1, wherein the ratio of the number of nitrogen atoms to the number of titanium atoms in the first titanium nitride layer is greater than 1.5, and the number of nitrogen atoms in the second titanium nitride layer is greater than 1.5 The ratio to the number of titanium atoms is in the range of 0.7-0.9.
The solar cell according to claim 1, wherein the thicknesses of the first titanium nitride layer and the second titanium nitride layer are both 1-500 nanometers.
The solar cell according to claim 1, wherein,

The second titanium nitride layer includes titanium nitride and doping elements doped in the titanium nitride, the doping elements include: any one or more of arsenic, aluminum, phosphorus and zinc .
The solar cell according to any one of claims 1, wherein the solar cell further comprises:

a first electrode and a second electrode;

The first electrode is arranged on the side of the first titanium nitride layer away from the silicon substrate, and the second electrode is arranged on the side of the second titanium nitride layer away from the silicon substrate;

Wherein, the first electrode and the second electrode are both selected from: aluminum electrode, silver electrode, aluminum/silver composite electrode, nickel/copper/tin composite electrode, chromium/palladium/silver composite electrode and nickel/copper/silver composite electrode Any of the composite electrodes.
The solar cell according to any one of claims 1-6, wherein a first passivation tunneling layer is disposed between the silicon substrate and the first titanium nitride layer;

And/or, a second passivation tunneling layer is disposed between the silicon substrate and the second titanium nitride layer.
The solar cell according to claim 7, wherein the thicknesses of the first passivation tunneling layer and the second passivation tunneling layer are both 0.1-5 nanometers;

The materials of the first passivation tunneling layer and the second passivation tunneling layer include: intrinsic amorphous silicon, silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, hydrogenated amorphous silicon, carbide Any one or more of silicon.
The solar cell according to any one of claims 1-6, characterized in that, the first titanium nitride layer and the second titanium nitride layer are respectively located on the first side of the backlight surface of the silicon substrate. In the case of the region and the second region, the first titanium nitride layer and the second titanium nitride layer are electrically insulated.
The solar cell according to any one of claims 1-6, wherein the thickness of the first titanium nitride layer is 2-20 nanometers;

The thickness of the second titanium nitride layer is 1-15 nanometers.
The solar cell according to any one of claims 1-6, wherein the solar cell further comprises: a metal layer in the contact region;

The contact area metal layer is disposed on the side of the first titanium nitride layer away from the silicon substrate;

Wherein, the first titanium nitride layer is disposed on the light-facing surface of the silicon substrate, and the thickness of the first titanium nitride layer is less than 5 nanometers.
A method for producing a solar cell, characterized in that the method comprises:

The first titanium nitride layer and the second titanium nitride layer are respectively prepared on the light-facing surface and the backlight surface of the silicon substrate; or, the first titanium nitride layer and the second titanium nitride layer are respectively prepared on the first area and the second area of the backlight surface of the silicon substrate. a titanium nitride layer and a second titanium nitride layer;

The first titanium nitride layer has hole selectivity, and the second titanium nitride layer has electron selectivity.
The method according to claim 12, wherein the step of preparing the first titanium nitride layer comprises:

Using a titanium chloride precursor as a titanium source and ammonia as a nitrogen source, thermal atomic deposition is performed in a temperature range of 300-500 degrees Celsius to form the first titanium nitride layer.
The method according to claim 12, wherein the step of preparing the second titanium nitride layer comprises:

The organic precursor of titanium is used as the titanium source, and the ammonia gas is used as the nitrogen source, and thermal atomic deposition is performed in the temperature range of 100-300 degrees Celsius to generate the second titanium nitride layer;

or,

Using titanium palladium, in an atmosphere of nitrogen and ammonia, physical vapor deposition reaction sputtering is performed to generate the second titanium nitride layer;

Wherein, the organic precursor of titanium includes: any one or more of TDMAT, TDEAT and TEMAT.
The method according to any one of claims 12-14, wherein,

The formation rate of the second titanium nitride layer is 5-20 times the formation rate of the first titanium nitride layer.
The method according to any one of claims 12-14, wherein the first titanium nitride layer and the second titanium nitride layer are respectively prepared on the light-facing surface and the backlight surface of the silicon substrate; or, in the After the step of preparing the first titanium nitride layer and the second titanium nitride layer respectively in the first region and the second region of the backlight surface of the silicon substrate, the method further includes:

A first electrode is provided on the side of the first titanium nitride layer away from the silicon substrate;

A second electrode is provided on the side of the second titanium nitride layer away from the silicon substrate.
The method according to any one of claims 12-14, wherein after the step of preparing the first titanium nitride layer and the second titanium nitride layer on the light-facing surface and the backlight surface of the silicon substrate, respectively, the Methods also include:

preparing a contact area metal layer on the side of the first titanium nitride layer away from the silicon substrate;

annealing the first titanium nitride layer and the metal layer in the contact area, and the first titanium nitride layer reacts with the metal in the metal layer in the contact area to form a titanium nitride composite film;

Wherein, the first titanium nitride layer is disposed on the light-facing surface of the silicon substrate, and the thickness of the first titanium nitride layer is less than 5 nanometers.
A photovoltaic module, characterized by comprising the solar cell of any one of claims 1-11.