CN108666377A - A kind of p-type back contact solar cell and its preparation method - Google Patents

Abstract

The invention relates to a p-type back-contact solar cell and a preparation method thereof, which comprise from top to bottom: a front passivation and anti-reflection film, a p-type silicon substrate, an n-type heterojunction region, a back passivation film and battery electrodes; From top to bottom, the n-type heterojunction region is the rear passivation tunnel layer and n-type doped film layer; the electrodes include positive and negative electrodes, the positive electrode includes positive electrode fine grid lines and positive electrode connection electrodes, and the negative electrode includes negative electrode fine grid wire and the negative connection electrode; the positive fine grid line is locally in contact with the p-type silicon substrate; the negative fine grid line is locally in contact with the n-type doped film layer; the positive fine grid line is connected to the positive connection electrode, The current is derived through the positive connecting electrode, the negative thin grid wire is connected with the negative connecting electrode, and the current is derived through the negative connecting electrode. The invention greatly reduces the generation of leakage current and improves the reliability and performance of the battery.

Description

A kind of p-type back contact solar cell and its preparation method

technical field

The invention relates to the technical field of solar cells, in particular to a p-type back-contact solar cell and a preparation method thereof.

Background technique

At present, with the gradual depletion of fossil energy, solar cells are used more and more widely as a new energy alternative. A solar cell is a device that converts the sun's light energy into electrical energy. Solar cells use the principle of photovoltaics to generate carriers, and then use electrodes to extract the carriers, which is beneficial to the effective use of electrical energy.

Back contact battery, that is, back contact battery, among which the interdigitated back contact solar cell is also called IBC battery. The full name of IBC is Interdigitated back contact, which means interdigitated back contact. The biggest feature of the IBC battery is that the emitter and the metal contact are on the back of the battery, and the front is not affected by the shielding of the metal electrode, so it has a higher short-circuit current Jsc, and the back can allow wider metal grid lines to reduce the series resistance Rs. Improve the fill factor FF; and this kind of battery with no shielding on the front not only has high conversion efficiency, but also looks more beautiful, and at the same time, the assembly of the full back electrode is easier to assemble. IBC battery is one of the technical directions to realize high-efficiency crystalline silicon battery at present.

Currently used interdigitated back contact solar cells usually use n-type sheets as the base material, and silver paste is usually used on the back side, so when preparing IBC cells, it is necessary to do a higher concentration of doping in the emitter and back field regions. In order to make the electrode contact better in the subsequent electrode preparation process, the cost is relatively high. And because at least two different doping processes of different doping types are required, the process flow is longer, especially when silicon wafers are p-type doped, higher temperature and time are required, which affects the minority carrier lifetime of the silicon substrate. It causes a relatively large negative impact, and additionally brings that the edge pn junction is difficult to remove, increases the complexity of the process, prolongs the process flow, and is unfavorable to industrial production.

Contents of the invention

In view of the above problems, the present invention provides a p-type back-contact solar cell and a preparation method thereof, which can better solve the above problems.

For realizing the above object, technical solution of the present invention is:

A p-type back contact solar cell, comprising from top to bottom: front passivation and anti-reflection film, p-type silicon substrate, back passivation tunneling layer, n-type doped film layer, back passivation film and battery electrodes ; The interval between the n-type doped film layers is arranged on the lower surface of the passivation tunneling layer on the back;

The battery electrode includes a positive electrode and a negative electrode, the positive electrode includes a positive electrode fine grid line and a positive electrode connection electrode, and the negative electrode includes a negative electrode fine grid line and a negative electrode connection electrode; the positive electrode fine grid line passes through the film opening area on the back passivation film Form contact with the p-type silicon substrate; the negative electrode fine grid line forms contact with the n-type doped film layer; the positive electrode fine grid line is connected to the positive electrode connection electrode, and the current is derived through the positive electrode connection electrode, and the negative electrode fine grid line is connected to the negative electrode The connecting electrode is connected and the current is conducted through the negative connecting electrode.

The n-type doped film layer on the back is composed of one or more of polycrystalline silicon, amorphous silicon, and microcrystalline silicon, and is doped with group V elements.

The back passivation tunneling layer is one of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide and amorphous silicon.

The width of the n-type doped regions is 0.08-3 mm, and the distance between two adjacent n-type doped regions is 0.05-1 mm.

The front passivation and anti-reflection film is made of one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, and amorphous silicon; the back passivation film is made of silicon nitride, One or more of silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, and amorphous silicon.

A hole-doped layer doped with group III elements is arranged in the local contact area between the positive electrode fine grid line and the p-type silicon substrate, and the thickness of the hole-doped layer is 1-15um.

An aluminum-silicon alloy layer is also included between the hole-doped layer and the positive electrode thin grid line, and the thickness of the aluminum-silicon alloy layer is 1-5 um.

The positive electrode fine grid line is an electrode containing aluminum, and the width of the positive electrode fine grid line is 20um-200um.

The negative electrode fine grid line is an electrode containing silver, and the width of the negative electrode fine grid line is 10um˜100um.

The main conductive component of the positive connecting electrode includes one or more of silver, copper, aluminum and nickel; the main conductive component of the negative connecting electrode includes one or more of silver, copper, aluminum and nickel.

The negative electrode fine grid line is disconnected in sections at the positive electrode connection electrode to avoid being connected to the positive electrode connection electrode; the positive electrode fine grid line is segmentally disconnected at the negative electrode connection electrode to avoid being connected to the negative electrode connection electrode; the positive electrode and the negative electrode are isolated and do not cross each other .

The positive connecting electrode and the negative thin grid line are intersected, and an insulator is arranged at the intersection to isolate each other;

A method for preparing a p-type back contact solar cell, comprising the steps of,

1) Cleaning and removing damage to the p-type silicon substrate, and performing surface texturing treatment on the p-type silicon substrate;

2) forming a passivation tunneling layer on the back of the p-type silicon substrate, and forming n-type doped film layers arranged at intervals;

3) Preparation of front passivation and anti-reflection film on the front side of the p-type silicon substrate, and preparation of rear passivation film on the back side of the p-type silicon substrate;

4) Electrode preparation: the positive electrode fine grid line is in contact with the p-type silicon substrate, and the negative electrode fine grid line is in contact with the n-type doped film layer;

Further, the contact between the negative electrode thin grid line and the n-type doped film layer is formed by burning through the passivation film on the back side of the electrode paste, or the direct contact of the electrode paste in the pre-opened film area.

Further, the preparation method of the n-type doped film layer on the back of the silicon substrate can use the in-situ doping chemical vapor deposition method; the preparation method of the n-type doped film layer can also use the first chemical vapor deposition method. Layer, and then cooperate with external doping source thermal propulsion method, ion implantation method, gas-carrying source thermal diffusion method.

Further, the method for preparing the passivation and anti-reflection film on the front side includes chemical vapor deposition, atomic layer deposition, thermal growth, and physical vapor deposition.

Further, the method for preparing the rear passivation film includes: chemical vapor deposition, atomic layer deposition, thermal growth, and physical vapor deposition.

Further, in the electrode preparation step, the positive electrode fine grid line is in contact with the silicon substrate, and the negative electrode fine grid line is in contact with the back n-type doped layer; the contact between the electrode and the doped layer may be electrode paste burn-through The formation of the passivation film on the back side can also be the direct contact of the electrode paste in the pre-opened film area.

Further, the electrode preparation step also includes the preparation process of an insulator between the positive electrode and the negative electrode.

The beneficial effects of the present invention are:

Currently used interdigitated back contact solar cells usually use n-type sheets as the base material, and silver paste is usually used on the back side, so when preparing IBC cells, it is necessary to do a higher concentration of doping in the emitter and back field regions. In order to make the electrode contact better in the subsequent electrode preparation process, the cost is relatively high. And because at least two different doping processes of different doping types are required, the process flow is relatively long, especially when silicon wafers are p-type doped, higher temperature and time are required, which increases the process cycle. The present invention uses a p-type sheet as the battery substrate, and cancels the process of doping the p-type back field in the process flow, thereby greatly reducing the complexity of the process flow and avoiding the high temperature required for p-type back field doping complex process. In addition, in the battery process, aluminum grid lines are used as the fine grid lines of the positive electrode of the battery, which greatly reduces the cost compared with silver paste as the positive electrode of the battery, and can also form better on the p-type substrate without additional doping. touch. In addition, there is no contact between the emitter and the back field on the back of the battery in the horizontal and vertical directions of the space, completely isolating the emitter and the back field, greatly reducing the generation of leakage current, improving reliability and battery performance Performance.

The preparation method of the present invention uses a p-type sheet as the battery substrate, and cancels the process of doping the p-type back field in the process flow, thereby greatly reducing the complexity of the process flow and avoiding the doping of the p-type back field High-temperature and complex processing processes required by miscellaneous materials.

Description of drawings

Fig. 1 is a schematic diagram of the battery structure of a specific embodiment in the embodiments.

Fig. 2 is a schematic diagram of the battery structure of a specific embodiment in the embodiments.

Fig. 3 is a schematic diagram of the battery structure of a specific embodiment in the embodiments.

FIG. 4 is a schematic diagram of the electrodes of Examples 1 and 3.

FIG. 5 is a schematic diagram of electrodes in Example 2.

Among them, 1 is the p-type silicon substrate, 2 is the front passivation and anti-reflection film, 3 is the passivation tunneling layer, 4 is the n-type doped film layer, 5 is the back passivation film, 6 is the local opening area, 7 8 is a negative fine grid, 9 is a positive electrode connection, 10 is a negative electrode connection, 11 is an insulator, 12 is a hole-doped layer, and 13 is an aluminum-silicon alloy layer.

Detailed ways

As shown in Figures 1 and 2, a p-type back-contact solar cell of the present invention comprises, from top to bottom: front passivation and anti-reflection film 2, p-type silicon substrate 1, back passivation tunneling layer 3, n type doped film layer 4, back passivation film 5 and battery electrode; the n-type doped film layer 4 is arranged on the lower surface of the back passivation tunneling layer 3; The doped film layers 4 are separated.

The battery electrode includes a positive pole and a negative pole, the positive pole includes a positive electrode thin grid line 7 and a positive electrode connection electrode 9, and the negative electrode includes a negative electrode thin grid line 8 and a negative electrode connection electrode 10; the positive electrode fine grid line 7 and the p-type silicon substrate 1 to form a contact; the negative fine grid line 8 is in contact with the n-type doped film layer 4; the positive fine grid line 7 is connected to the positive connecting electrode 9, and the current is derived through the positive connecting electrode 9, and the negative fine grid line 8 It is connected to the negative connection electrode 10 , and a current is drawn out through the negative connection electrode 10 .

As shown in Figure 3, a hole-doped layer 12 doped with Group III elements is provided in the local contact area between the positive electrode thin gate line 7 and the p-type silicon substrate 1, and the thickness of the hole-doped layer 12 is 1-15um. . Preferably, an aluminum-silicon alloy layer 13 is further included between the hole-doped layer 12 and the positive electrode fine grid line, and the thickness of the aluminum-silicon alloy layer 13 is 1-5 um.

As shown in Figure 4, the negative electrode fine grid line 8 is segmented and disconnected at the positive electrode connection electrode 9 to avoid being connected with the positive electrode connection electrode 9; Connected; the positive and negative poles are isolated and do not cross each other.

As shown in Figure 5, the positive electrode connection electrode 9 and the negative electrode thin grid line 8 are intersected, and an insulator 10 is provided at the intersection to isolate each other. Insulated from each other; the positive and negative poles are insulated from each other.

Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Example 1:

The following is an example of a method for preparing a back-contact solar cell using the above-mentioned structure and method, which is the structure shown in FIG. 1 . The preparation method of this back contact solar cell is specifically as follows:

The silicon substrate is subjected to de-damage treatment, surface texturing treatment and cleaning process. Use p-type monocrystalline silicon as the battery substrate, use a 60°C solution containing KOH for damage removal treatment, and use a solution containing KOH for surface texture treatment at 80°C to form a pyramid texture with a pyramid scale of 2-5um , and use a mixed solution of hydrofluoric acid and hydrochloric acid for cleaning, deionized water cleaning and drying.

Preparation of the rear passivation tunneling layer 3 and the rear n-type doped film layer 4 . Deposition of tunneling silicon oxide, n-type in-situ doped polysilicon (polysilicon) deposition was performed using low pressure chemical vapor deposition (LPCVD) in one pass. The thickness of the tunneling silicon oxide layer is 2nm, the thickness of the n-type doped polysilicon is 100nm, and the n-type doping concentration is 2E20 atoms/cubic centimeter. The p-type region is grooved on the back side.

Pattern the n-type heterojunction region. Use the laser to process the p-type area on the back of the battery, locally remove the tunnel oxide layer, n-type poly layer, passivation oxide layer and intrinsic polysilicon layer, and clean the grooved area. The P-type area is distributed in parallel straight lines, the width of the slot line is 300um, and the center distance of the slot line is 1500um. After treatment, the remaining n-type emitter region is also distributed in a straight line with a width of 1200um. After cleaning the slotted area with tetramethylammonium hydroxide solution, wash with hydrochloric acid solution, wash with deionized water, and dry.

Preparation of front passivation and antireflection film 2 and back passivation film 5 . Passivation is performed on the back of the cell, depositing layers of aluminum oxide and silicon nitride. The aluminum oxide and silicon nitride passivation films were deposited by plasma-enhanced chemical vapor deposition PECVD, with a thickness of aluminum oxide of 15 nm, a thickness of silicon nitride of 100 nm, and a refractive index of 2.10. Use enhanced plasma chemical vapor deposition PECVD to deposit a 5-10nm aluminum oxide layer on the light-receiving surface of the battery, and then deposit silicon nitride on it, with a thickness of 80nm and a refractive index of 2.03, to complete the preparation of the front passivation and anti-reflection film 2.

Preparation of battery electrodes. The p-type contact area is prepared in the p-type area on the back of the battery, and the laser is used to open the film in the p-type area. The opening area is distributed in dots, and the dot pattern is distributed in the p-type area in a straight line. 90nm, dot pitch 500um. A laser is used to open holes in the p-type area on the back of the cell. The scanning method is to perform pulsed local laser irradiation treatment on the p-type region, and the scanning direction is along the parallel direction of the doping. The wavelength of the opening laser is 532nm, the spot size is 90um diameter circle, and the scanning speed is 10000mm/s , the frequency is 20kHz, that is, there is a reserved contact hole with a diameter of 90um circular area every 500um on the strip p-type area. The passivation film on the back forms holes in the area irradiated by the laser spot, and no contact holes are formed in the non-irradiated area. After the laser holes are opened in the contact hole area, there is no back passivation film 5 .

An electrode paste layer containing conductive components is formed on the back n area and the back p type area of the battery by screen printing. The electrodes include a positive electrode and a negative electrode, wherein the positive electrode includes a positive fine grid line 7 and a positive connecting electrode 9, and the negative electrode includes a negative fine grid line 8 and a negative connecting electrode 10; the positive fine grid line 7 is made of aluminum, and the negative fine grid is made of Composed of silver, the grid lines of the positive and negative electrodes are not connected to each other; the fine grid of the positive electrode is connected to the connecting electrode of the positive electrode, and the connecting electrode of the negative electrode is connected to the fine grid of the negative electrode; the fine grid line of the positive electrode and the fine grid line of the negative electrode 8 are arranged in segments; the positive connecting electrode 9 is arranged at the 8 segment of the negative thin grid line, and the negative connecting electrode 10 is arranged at the 7 segment of the positive fine grid line; the positive and negative electrodes are insulated from each other. The width of the positive fine grid is 120um, completely covering the set contact opening area, the width of the negative fine grid line 8 is 50um, there are 94 positive connecting electrodes and 104 negative connecting electrodes. A battery electrode as shown in FIG. 4 is formed.

The metallization heat treatment process is completed in the sintering furnace. The heating peak temperature is 500-800°C. The preferred heat treatment peak temperature in this embodiment is 700°C. After this step, the battery preparation is completed. During this process, the positive electrode fine grid line 7 passes through the passivation film to form contact with the p-type silicon substrate 1 , and the negative electrode fine gate line 8 passes through the passivation film to form contact with the n-type doped polysilicon. The formed battery structure is shown in Fig. 1 .

Example 2

The following is an example of another method for preparing a back-contact solar cell, which has the structure shown in FIG. 2 . The preparation method of this back contact solar cell is specifically as follows:

The silicon substrate is subjected to de-damage treatment, surface texturing treatment and cleaning process. Use p-type monocrystalline silicon as the battery substrate, use a 60°C solution containing KOH for damage removal treatment, and use a solution containing KOH for surface texture treatment at 80°C to form a pyramid texture with a pyramid scale of 2-5um , and use a mixed solution of hydrofluoric acid and hydrochloric acid for cleaning, deionized water cleaning and drying.

Fabrication of backside n-type heterojunction. Deposition of tunneling silicon oxide, n-type in-situ doped polysilicon (polysilicon) deposition was performed using low pressure chemical vapor deposition (LPCVD) in one pass. The thickness of the tunneling silicon oxide layer is 2nm, the thickness of the n-type doped polysilicon is 100nm, and the n-type doping concentration is 2E20 atoms/cubic centimeter. The p-type region is grooved on the back side.

Patterned n-type heterojunction fabrication. The n-type poly layer on it is partially removed by cleaning with a mask and tetramethylammonium hydroxide, and the passivation tunneling layer 3 is retained. The P-type area is distributed in parallel straight lines, the width of the slot line is 300um, and the center distance of the slot line is 1500um. After treatment, the remaining n-type emitter region is also distributed in a straight line with a width of 1200um. Then, perform hydrochloric acid solution cleaning, deionized water cleaning, drying and the like.

Preparation of front passivation and antireflection film 2 and back passivation film 5 . Passivation is performed on the back of the cell, depositing layers of aluminum oxide and silicon nitride. The aluminum oxide and silicon nitride passivation films were deposited by plasma-enhanced chemical vapor deposition PECVD, with a thickness of aluminum oxide of 15 nm, a thickness of silicon nitride of 100 nm, and a refractive index of 2.10. Use enhanced plasma chemical vapor deposition PECVD to deposit a 5-10nm aluminum oxide layer on the light-receiving surface of the battery, and then deposit silicon nitride on it, with a thickness of 80nm and a refractive index of 2.03, to complete the preparation of the front passivation and anti-reflection film 2.

Preparation of battery electrodes. The p-type contact area is prepared in the p-type area on the back of the battery, and the laser is used to open the film in the p-type area. The opening area is distributed in dots, and the dot pattern is distributed in the p-type area in a straight line. 90nm, dot pitch 500um. A laser is used to open holes in the p-type area on the back of the cell. The scanning method is to perform pulsed local laser irradiation treatment on the p-type region, and the scanning direction is along the parallel direction of the doping. The wavelength of the opening laser is 532nm, the spot size is 90um diameter circle, and the scanning speed is 10000mm/s , the frequency is 20kHz, that is, there is a reserved contact hole with a diameter of 90um circular area every 500um on the strip p-type area. The passivation film on the back forms holes in the area irradiated by the laser spot, and no contact holes are formed in the non-irradiated area. After the laser holes are opened in the contact hole area, there is no back passivation film 5 .

An electrode paste layer containing conductive components is formed on the back n area and the back p type area of the battery by screen printing. The electrodes include a positive electrode and a negative electrode, wherein the positive electrode includes a positive fine grid line 7 and a positive connecting electrode 9, and the negative electrode includes a negative fine grid line 8 and a negative connecting electrode 10; the positive fine grid line 7 is made of aluminum, and the negative fine grid is made of Composed of silver, the grid lines of the positive and negative electrodes are not connected to each other; the fine grid of the positive electrode is connected to the connecting electrode of the positive electrode, and the connecting electrode of the negative electrode is connected to the fine grid of the negative electrode; an insulator is printed between the connecting electrode of the positive electrode and the fine grid of the negative electrode 10 for isolation, and an insulator 10 is printed between the connecting electrode of the negative electrode and the fine grid of the positive electrode for isolation. The width of the positive electrode fine grid is 120um, the opening area provided on the passivation film, the width of the negative electrode fine grid line 8 is 50um, the number of positive electrode connection electrodes 9 is four, and the number of negative electrode connection electrodes 10 is four. A battery electrode as schematically shown in FIG. 5 was formed.

The metallization heat treatment process is completed in the sintering furnace. The heating peak temperature is 500-800°C. The preferred heat treatment peak temperature in this embodiment is 700°C. After this step, the battery preparation is completed. During this process, the positive electrode fine grid line 7 passes through the passivation film to form contact with the p-type silicon substrate 1 , and the negative electrode fine gate line 8 passes through the passivation film to form contact with the n-type doped polysilicon. The formed battery structure is shown in Fig. 2 .

Example 3:

The following is an example of a method for preparing a back-contact solar cell using the above-mentioned structure and method, which is the structure shown in FIG. 3 . The preparation method of this back contact solar cell is specifically as follows:

The silicon substrate is subjected to de-damage treatment, surface texturing treatment and cleaning process. Use p-type monocrystalline silicon as the battery substrate, use a 60°C solution containing KOH for damage removal treatment, and use a solution containing KOH for surface texture treatment at 80°C to form a pyramid texture with a pyramid scale of 2-5um , and use a mixed solution of hydrofluoric acid and hydrochloric acid for cleaning, deionized water cleaning and drying.

Preparation of the rear passivation tunneling layer 3 and the rear n-type doped film layer 4 . Deposition of tunneling silicon oxide, n-type in-situ doped polysilicon (polysilicon) deposition was performed using low pressure chemical vapor deposition (LPCVD) in one pass. The thickness of the tunneling silicon oxide layer is 2nm, the thickness of the n-type doped polysilicon is 100nm, and the n-type doping concentration is 2E20 atoms/cubic centimeter. The p-type region is grooved on the back side.

Pattern the n-type heterojunction region. Use the laser to process the p-type area on the back of the battery, locally remove the tunnel oxide layer, n-type poly layer, passivation oxide layer and intrinsic polysilicon layer, and clean the grooved area. The P-type area is distributed in parallel straight lines, the width of the slot line is 300um, and the center distance of the slot line is 1500um. After treatment, the remaining n-type emitter region is also distributed in a straight line with a width of 1200um. After cleaning the slotted area with tetramethylammonium hydroxide solution, wash with hydrochloric acid solution, wash with deionized water, and dry.

Preparation of front passivation and antireflection film 2 and back passivation film 5 . Passivation is performed on the back of the cell, depositing layers of aluminum oxide and silicon nitride. The aluminum oxide and silicon nitride passivation films were deposited by plasma-enhanced chemical vapor deposition PECVD, with a thickness of aluminum oxide of 15 nm, a thickness of silicon nitride of 100 nm, and a refractive index of 2.10. Use enhanced plasma chemical vapor deposition PECVD to deposit a 5-10nm aluminum oxide layer on the light-receiving surface of the battery, and then deposit silicon nitride on it, with a thickness of 80nm and a refractive index of 2.03, to complete the preparation of the front passivation and anti-reflection film 2.

Preparation of battery electrodes. The p-type contact area is prepared in the p-type area on the back of the battery, and the laser is used to open the film in the p-type area. The opening area is distributed in dots, and the dot pattern is distributed in the p-type area in a straight line. 90nm, dot pitch 500um. A laser is used to open holes in the p-type area on the back of the cell. The scanning method is to perform pulsed local laser irradiation treatment on the p-type region, and the scanning direction is along the parallel direction of the doping. The wavelength of the opening laser is 532nm, the spot size is 90um diameter circle, and the scanning speed is 10000mm/s , the frequency is 20kHz, that is, there is a reserved contact hole with a diameter of 90um circular area every 500um on the strip p-type area. The passivation film on the back forms holes in the area irradiated by the laser spot, and no contact holes are formed in the non-irradiated area. After the laser holes are opened in the contact hole area, there is no back passivation film 5 .

An electrode paste layer containing conductive components is formed on the back n area and the back p type area of the battery by screen printing. The electrodes include a positive electrode and a negative electrode, wherein the positive electrode includes a positive fine grid line 7 and a positive connecting electrode 9, and the negative electrode includes a negative fine grid line 8 and a negative connecting electrode 10; the positive fine grid line 7 is made of aluminum, and the negative fine grid is made of Composed of silver, the grid lines of the positive and negative electrodes are not connected to each other; the fine grid of the positive electrode is connected to the connecting electrode of the positive electrode, and the connecting electrode of the negative electrode is connected to the fine grid of the negative electrode; the fine grid line of the positive electrode and the fine grid line of the negative electrode 8 are arranged in segments; the positive connecting electrode 9 is arranged at the 8 segment of the negative thin grid line, and the negative connecting electrode 10 is arranged at the 7 segment of the positive fine grid line; the positive and negative electrodes are insulated from each other. The width of the positive electrode fine grid is 120um, which completely covers the set contact opening area, the width of the negative electrode fine grid line 8 is 50um, the number of positive electrode connection electrodes 9 is four, and the number of negative electrode connection electrodes 10 is four. A battery electrode as shown in FIG. 4 is formed.

The metallization heat treatment process is completed in the sintering furnace. The heating peak temperature is 500-800°C. The preferred heat treatment peak temperature in this embodiment is 700°C. After this step, the battery preparation is completed. During this process, the positive electrode fine grid line 7 passes through the passivation film to form contact with the p-type silicon substrate 1 , and the negative electrode fine gate line 8 passes through the passivation film to form contact with the n-type doped polysilicon. In the finally formed solar cell, an aluminum-doped hole layer 12 and an aluminum-silicon alloy layer 13 are formed between the positive fine grid line 7 and the silicon substrate. The formed battery structure is shown in FIG. 3 .

In addition, the above-mentioned embodiment of this invention is an example, and the technical means which have the same technical idea as described in the claim of this invention, and have the same operation effect are included in this invention.

Claims (16)

1. a kind of p-type back contacts solar cell, which is characterized in that include successively from top to bottom：Front passivation and antireflective coating (2), p-type silicon substrate (1), passivating back tunnel layer (3), N-shaped doping film layer (4), backside passivation film (5) and battery electrode；Institute The N-shaped doping film layer (4) stated is arranged at intervals on passivating back tunnel layer (3) lower surface；

The battery electrode includes anode and cathode, and the anode includes just superfine grid line (7) and positive connection electrode (9), The cathode includes the thin grid line of cathode (8) and cathode connection electrode (10)；Just superfine grid line (7) connects with p-type silicon substrate (1) formation It touches；The thin grid line of cathode (8) is formed with N-shaped doping film layer (4) and is contacted；The just superfine grid line (7) connects with positive connection electrode (9) It connects, and by positive connection electrode (9) derived current, the thin grid line of cathode (8) connect with cathode connection electrode (10), and leads to Cross cathode connection electrode (10) derived current.

2. p-type back contacts solar cell according to claim 1, which is characterized in that the back side N-shaped doping film layer (4) It is made of one or more in polysilicon, non-crystalline silicon, microcrystal silicon, and doped with V group element.

3. p-type back contacts solar cell according to claim 1, which is characterized in that the passivating back tunnel layer (3) is One kind in silicon nitride, silica, silicon oxynitride, aluminium oxide, silicon carbide and non-crystalline silicon.

4. p-type back contacts solar cell according to claim 1, which is characterized in that the width of the N-shaped doped region is 0.08~3mm, the spacing between two neighboring N-shaped doped region are 0.05~1mm.

5. p-type back contacts solar cell according to claim 1, which is characterized in that the front passivation and antireflective coating (2) one or more compositions in silicon nitride, silica, silicon oxynitride, aluminium oxide, silicon carbide, non-crystalline silicon are used；The back side Passivating film (5) is using one or more compositions in silicon nitride, silica, silicon oxynitride, aluminium oxide, silicon carbide, non-crystalline silicon.

6. p-type back contacts solar cell according to claim 1, which is characterized in that the just superfine grid line (7) and p The hole doping layer (12) of one layer of group-III element doping, hole doping layer are provided in the partial contact zones of type silicon base (1) (12) thickness is 1~15um.

7. p-type back contacts solar cell according to claim 5, which is characterized in that the hole doping layer (12) and Further include one layer of alusil alloy layer (13) between just superfine grid line, alusil alloy layer (13) thickness is 1~5um.

8. p-type back contacts solar cell according to claim 1, which is characterized in that the just superfine grid line (7) is containing aluminium Electrode, the width of the just superfine grid line (7) is 20um~200um.

9. p-type back contacts solar cell according to claim 1, which is characterized in that the thin grid line of cathode (8) is argentiferous Electrode, the width of the thin grid line of cathode (8) is 10um~100um.

10. p-type back contacts solar cell according to claim 1, which is characterized in that the anode connection electrode (9) is main It includes one or more in silver, copper, aluminium, nickel to want conductive compositions；Cathode connection electrode (10) the main conductive ingredient includes It is one or more in silver, copper, aluminium, nickel.

11. the p-type back contacts solar cell according to claim 1~10 any one, which is characterized in that the cathode is thin Grid line (8) is disconnected in positive connection electrode (9) punishment section, avoids being connected with positive connection electrode (9)；Just superfine grid line (7) exists Cathode connection electrode (10) is punished section and is disconnected, and avoids being connected with cathode connection electrode (10)；Anode and cathode isolation, are not handed over mutually Fork.

12. the p-type back contacts solar cell according to claim 1~10 any one, which is characterized in that the anode is even Receiving electrode (9) and the thin grid line of cathode (8) are arranged in a crossed manner, and infall is provided with insulator (10) and is mutually isolated, the cathode connection Electrode (10) and just superfine grid line (7) are arranged in a crossed manner, and infall is arranged one layer of insulator (10) and is mutually isolated；Anode and cathode phase Mutually insulation.

13. a kind of preparation method of p-type back contacts solar cell, which is characterized in that include the following steps：

1) p-type silicon substrate (1) is cleaned and is gone to damage, p-type silicon substrate (1) carries out surface-texturing processing；

2) passivation tunnel layer (3) is formed at p-type silicon substrate (1) back side, and forms spaced N-shaped doping film layer (4)；

3) positive passivation and the preparation of antireflective coating (2) are carried out in p-type silicon substrate (1) front, p-type silicon substrate (1) back side into The preparation of row backside passivation film (5)；

4) electrode preparation is carried out：Just superfine grid line (7) and p-type silicon substrate (1) form contact, the thin grid line of cathode (8) and N-shaped doping Film layer (4) forms contact.

14. the preparation method of p-type back contacts solar cell according to claim 13, which is characterized in that the thin grid line of cathode (8) it is burnt for electrode slurry with the contact of N-shaped doping film layer (4) with the contact of N-shaped doping film layer (4) and the thin grid line of cathode (8) Backside passivation film (5) is formed or electrode slurry is opened diaphragm area formation and be in direct contact pre-.

15. the preparation method of p-type back contacts solar cell according to claim 13, which is characterized in that the N-shaped doping The preparation method of film layer (4) adulterates chemical vapor deposition method using in situ, or uses first chemical vapor deposition intrinsic layer, The hot propulsion method of external doped source, ion injection method, gas is cooperateed with to take source thermal diffusion method afterwards.

16. the preparation method of p-type back contacts solar cell according to claim 13, which is characterized in that in step 4), also Include the preparation process of insulator between anode and cathode.