CN212676279U

CN212676279U - Laser boron-doped back-passivated solar cell

Info

Publication number: CN212676279U
Application number: CN202021517056.1U
Authority: CN
Inventors: 张鹏; 朱波; 何宇; 眭山
Original assignee: Tongwei Solar Meishan Co Ltd
Current assignee: Tongwei Solar Meishan Co Ltd
Priority date: 2020-07-28
Filing date: 2020-07-28
Publication date: 2021-03-09
Anticipated expiration: 2030-07-28

Abstract

The utility model discloses a laser boron doping back passivation solar cell for improve solar cell's back passivation structure among the prior art, relate to solar cell technical field, this solar cell includes P type silicon, P type silicon openly upwards is equipped with phosphorus doping layer, front passivation antireflection coating and Ag bars finger electrode in proper order, P type silicon back is equipped with passivation layer, back passivation antireflection coating and Al bars finger electrode downwards in proper order, P type silicon back still is equipped with heavily doped region, heavily doped region includes boron heavily doped layer and local contact aluminium doping layer, Al bars finger electrode is connected with P type silicon lower surface through heavily doped region; the utility model discloses a form the heavy doping region at the battery back, can effectively reduce the combined loss in metal contact region, reduce contact resistance and reinforcing passivation ability to keep higher short-circuit current, increase open circuit voltage, promote the fill factor, thereby realize high conversion efficiency, high stability's solar cell.

Description

Laser boron-doped back-passivated solar cell

Technical Field

The utility model relates to a solar cell technical field, in particular to laser boron doping back of body passivation solar cell.

Background

At present, a solar cell mainly uses crystalline silicon as a substrate material, and a large number of dangling bonds (danglingbonds) are generated due to periodic damage on the surface of a silicon wafer, so that a large number of defect energy levels in a band gap exist on the surface of the crystal; in addition, the deposition of dislocations, chemical residues and surface metals can introduce defect energy levels, so that the surface of the silicon wafer becomes a recombination center, a large surface recombination rate is caused, and the conversion efficiency is limited.

Compared with the conventional battery, the back passivated battery has the main advantages of reducing the interface state of the back surface of the battery piece, improving the passivation capability, prolonging the light path, and improving the long-wave response and the short-circuit current, so that the conversion efficiency of the back passivated battery is improved by 1.0-1.2% or even more compared with the conventional battery. At present, the industrial scale production is carried out by AlO_x+SiN_xThe structure is a main back passivation film layer, but the existence of Si-H and-NH bonds easily causes the film layer to loose and gather a large number of pinholes, and after high-temperature annealing, hydrogen is separated from the Si-H bonds to leave unsaturated Si⁺Of these excess Si⁺The bonding occurs between the two layers, and finally, an aggregate of silicon, also called a silicon island, is formed, so that the passivation effect is directly influenced, the efficiency improvement of the back passivation battery is limited, and the economic benefit of the production of the high-efficiency battery is reduced.

The structure of a passivated rear contact (PERC) solar cell in the prior art is shown in FIG. 1, and the main processes are texturing, phosphorus diffusion, back etching, annealing, back plating AlO_xBack side coated SiN_xFront coated SiN_xLaser grooving of the back passivation layer, printing of an electric field of the front and back electrodes, and high-temperature sintering to finally form the back passivation solar cell. Because an insulating passivation layer is deposited on the back of the cell, the interface state of the back is reduced, the passivation effect is improved, the light path is prolonged, the long-wave response and the short-circuit current are improved, then, part of the passivation layer is selectively etched through laser etching to expose a silicon layer, and then, back electric field aluminum paste is printed in a laser etching area to be in direct contact with the silicon layer, so that the conduction is realized; therefore, in the back laser etching area, since part of the passivation layer is removed, the passivation capability is reduced, the whole back passivation effect is directly influenced, and the conversion efficiency of the battery is reduced.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a: the laser boron-doped back passivation solar cell has the advantages that the heavily doped region is formed on the back of the cell, so that the recombination loss of a metal contact region can be effectively reduced, the contact resistance is reduced, the passivation capability is enhanced, the recombination speed of the back surface is obviously reduced, higher short-circuit current is kept, the open-circuit voltage is increased, the filling factor is improved, and the solar cell with high conversion efficiency and high stability is realized.

The utility model adopts the technical scheme as follows:

in order to realize the above-mentioned purpose, the utility model provides a laser boron doping back of body passivation solar cell, including P type silicon, P type silicon openly upwards is equipped with phosphorus doping layer, front passivation antireflection coating and Ag bars in proper order and indicates the electrode, the P type silicon back is equipped with passivation layer, back passivation antireflection coating and Al bars downwards in proper order and indicates the electrode, the P type silicon back still is equipped with the heavily doped region, the heavily doped region includes boron heavily doped layer and local contact aluminium doping layer, the Al bars indicates that the electrode passes through heavily doped region and P type silicon lower surface connection.

Preferably, the front surface of the P-type silicon is also provided with a heavily doped silicon layer, and the Ag gate finger electrode is connected with the upper surface of the P-type silicon through the heavily doped silicon layer.

Preferably, both the front passivation antireflection layer and the back passivation antireflection layer are SiN_xAnd (5) film layer.

Preferably, the passivation layer is AlO_xAnd (5) film layer.

Preferably, the boron heavily doped layer is connected with the lower surface of the P-type silicon, and the local contact aluminum doped layer is connected with the Al gate finger electrode.

To sum up, owing to adopted above-mentioned technical scheme, the beneficial effects of the utility model are that:

the utility model discloses a set up aluminium oxide layer and silicon nitride layer at the battery back, form passivation subtract anti-lamination, carry out laser cladding simultaneously on borosilicate nanometer film and form the silicon cladding of doping, boron element diffusion entering silicon chip after the laser grooving, form the heavy doping region, can effectively reduce the combined loss in metal contact region, reduce contact resistance and reinforcing passivation ability, the composite velocity of the back of the body surface of significantly reducing, and the hydrogen saturation of atomic state has been increased, the base member surface hangs the key and provides a large amount of fixed charge field passivation effect, and then keep higher short-circuit current, increase open circuit voltage, promote the fill factor, thereby realize high conversion efficiency, high stability's solar cell.

Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a prior art back passivated solar cell;

fig. 2 is a schematic structural diagram of the back passivated solar cell of the present invention.

Labeled as: the solar cell comprises 1-P type silicon, 2-phosphorus doped layers, 3-front passivation antireflection layers, 4-heavily doped silicon layers, 5-Ag gate finger electrodes, 6-passivation layers, 7-back passivation antireflection layers, 8-heavily doped regions, 801-boron heavily doped layers, 802-local contact aluminum doped layers and 9-Al gate finger electrodes.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only some embodiments, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Example 1

Referring to fig. 2, the present embodiment provides a laser boron-doped back-passivated solar cell, which includes a P-type silicon 1, wherein a phosphorus-doped layer 2(N + layer) and an SiN layer are sequentially disposed on the front surface of the P-type silicon 1 upward_xThe front surface of the P-type silicon 1 is also provided with a heavily doped silicon layer 4(N + + layer), the Ag gate finger electrode 5 is connected with the upper surface of the P-type silicon 1 through the heavily doped silicon layer 4, and the back surface of the P-type silicon 1 is downwards sequentially provided with AlO_xPassivation layer 6, SiN_xThe back passivation antireflection layer 7 and the Al gate finger electrode 9, the back of the P type silicon 1 is also provided with a heavily doped region 8, the heavily doped region 8 comprises a boron heavily doped layer 801(P + + layer) and a local contact aluminum doped layer 802(P + layer), the Al gate finger electrode 9 is connected with the lower surface of the P type silicon 1 through the heavily doped region 8, the boron heavily doped layer 801 is connected with the lower surface of the P type silicon 1, and the local contact aluminum doped layer 802 is connected with the Al gate finger electrode 9.

Example 2

The embodiment provides a preparation method of a laser boron-doped back passivation solar cell, which comprises the following steps:

(1) adopting alkali to perform texturing, removing a damage layer of a silicon wafer in a groove, and performing texturing to form a pyramid textured surface with the height of 0.5-5 microns;

(2) using phosphorus oxychloride (POCl)₃) High-temperature diffusion is carried out, the reaction temperature is 750-;

(3) forming a heavily doped silicon layer (N + + layer) by laser doping;

(4) adopting wet etching process and HNO₃the/HF mixed solution is used for removing the P-doped N + junction on the back surface of the silicon wafer, polishing the back surface, and annealing at high temperature, wherein the annealing reaction temperature is 750-;

(5) depositing AlO on the back of the silicon wafer in sequence by adopting an Atomic Layer Deposition (ALD) or Plasma Enhanced Chemical Vapor Deposition (PECVD) method_xLayer and SiN_xLayer, forming passivation antireflectionA laminated structure;

(6) adopting a Plasma Enhanced Chemical Vapor Deposition (PECVD) method to deposit SiN on the front surface of the silicon wafer_xA layer;

(7) printing boron-doped silicon nano slurry on a laser grooving pattern on the back surface of a silicon wafer by screen printing, and drying to form a boron-silicon nano film, wherein the particle size of silicon nano particles in the boron-doped silicon nano slurry is 1-5nm, and the mass percentage content of boron element is 10-50%;

(8) performing laser boron doping on the borosilicate nano film, selectively etching off part of the passivation layer by adopting laser, cladding the borosilicate nano film by adopting laser, forming a heavily doped region and exposing the silicon layer, wherein the laser boron doping adopts picosecond laser, the wavelength is 532nm, the pulse width is 10-30ps, the power is 10-30w, and the shape of a light spot is circular or rectangular.

(9) And printing silver paste on the front surface of the silicon wafer, printing aluminum paste and silver paste on the back surface of the silicon wafer according to the screen printing plate pattern design by adopting screen printing, forming ohmic contact after high-temperature sintering, and manufacturing to obtain the laser boron-doped back-passivated solar cell.

Example 3

The embodiment is preferable to the embodiment 2, and the AlO_xPreparation of the layers with TMA and O₂/N₂The reaction temperature of the mixed gas of O is 200-350 ℃, and the thickness is 5-15 nm;

the SiN_xLayer is SiH₄And NH₃The reaction temperature is 300-550 ℃, the thickness is 70-110nm, the refractive index is 1.9-2.2, and the SiN_xThe layers may be single or double or triple layer structures.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the scope of the embodiments of the present invention, and are intended to be covered by the claims and the specification.

Claims

1. The utility model provides a laser boron doping back of body passivation solar cell, includes P type silicon (1), its characterized in that, P type silicon (1) openly upwards is equipped with phosphorus doping layer (2), front passivation antireflection coating (3) and Ag bars finger electrode (5) in proper order, P type silicon (1) back is equipped with passivation layer (6), back passivation antireflection coating (7) and Al bars finger electrode (9) downwards in proper order, P type silicon (1) back still is equipped with heavily doped region (8), heavily doped region (8) are including boron heavily doped layer (801) and local contact aluminium doping layer (802), Al bars finger electrode (9) are connected with P type silicon (1) lower surface through heavily doped region (8).

2. The laser boron-doped back-passivated solar cell according to claim 1, characterized in that the front surface of the P-type silicon (1) is further provided with a heavily doped silicon layer (4), and the Ag gate finger electrode (5) is connected with the upper surface of the P-type silicon (1) through the heavily doped silicon layer (4).

3. The laser boron doped back passivated solar cell according to claim 1 wherein the front passivated antireflective layer (3) and the back passivated antireflective layer (7) are both SiN_xAnd (5) film layer.

4. The laser boron doped back passivated solar cell according to claim 1 wherein the passivation layer (6) is AlO_xAnd (5) film layer.

5. A laser boron doped back passivated solar cell according to claim 1 characterized by that said boron heavily doped layer (801) is connected to the lower surface of P-type silicon (1) and said local contact aluminum doped layer (802) is connected to the Al gate finger electrode (9).