CN210403742U

CN210403742U - Local emitter homogeneous crystal silicon double-sided solar cell structure

Info

Publication number: CN210403742U
Application number: CN201820330976.9U
Authority: CN
Inventors: 黄海宾; 周浪; 袁吉仁; 高超; 岳之浩
Original assignee: Lattice Power Jiangxi Corp
Current assignee: Lattice Power Jiangxi Corp; Nanchang University
Priority date: 2018-03-12
Filing date: 2018-03-12
Publication date: 2020-04-24
Anticipated expiration: 2028-03-12

Abstract

A local emitter homogeneous crystal silicon double-sided solar cell structure takes an n-type crystal silicon wafer as a substrate, and an emitter surface is divided into an emitter-conductive area and a passivation-light entering area: the metal grid line structure comprises a substrate, a heavily doped p-type crystalline silicon emitter layer, a metal grid line I, a heavily doped n-type crystalline silicon field passivation layer I and a passivated antireflection layer I, wherein the substrate is arranged outwards; the back electric field surface is divided into a passivation-light inlet area and a back electric field-conductive area: the heavily doped n-type crystalline silicon layer II and the passivated antireflection layer II are sequentially arranged on the substrate from the bottom to the outside; the heavily doped n-type crystal silicon layer II and the metal grid line II are sequentially arranged from the substrate to the outside. The utility model discloses keeping crystalline silicon solar cell two-sided entering under the prerequisite of light characteristic, obtained higher open circuit voltage and short-circuit current, furthest's improvement crystalline silicon solar cell's generating capacity.

Description

Local emitter homogeneous crystal silicon double-sided solar cell structure

Technical Field

The utility model belongs to solar cell field and semiconductor device field. Relates to a preparation technology of a solar cell.

Background

For a double-sided crystalline silicon solar cell, a PERT structure has been focused on in the solar cell industry because of high efficiency due to good compatibility with the existing crystalline silicon production line for diffusion junction manufacturing. However, the development of solar cells with this structure is currently suffering from bottlenecks, and one of the keys lies in the performance of the emitter layer formed by boron diffusion and the preparation technology thereof. The boron doping concentration must be high in order to achieve a higher open circuit voltage, but this will lead to an increase in carrier recombination. Furthermore, the low sheet resistance required for the lateral transport loss of carriers in the boron doped layer is contradictory to the technical improvement direction of increasing the boron doping concentration (which causes an increase in recombination loss) required to achieve this condition.

How to solve this conflict is crucial to the development of the PERT technology, and we consider that starting from the design of the device structure may be an effective breakthrough. The present invention is an attempt in this direction.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a local projecting pole homogeneity crystal silicon double-sided solar cell structure.

The utility model discloses a realize through following technical scheme.

A two-sided solar cell structure of local projecting pole homogeneity crystalline substance silicon to n type crystalline substance silicon chip (5) are as the basement, its projecting pole face divide into projecting pole-conductive region and passivation-advance the light region: the emitter-conductive region is formed by a heavily doped p-type crystalline silicon emitter layer (2) and a metal grid line I (1) from a substrate to the outside in sequence, and the passivation-light inlet region is formed by a heavily doped n-type crystalline silicon field passivation layer I (4) and a passivation antireflection layer I (3) from the substrate to the outside in sequence. The two regions are distributed across and do not overlap.

The preferred silicon nitride layer of passivation antireflection layer I (3) of the utility model.

An insulating layer is preferably established between projecting pole and heavily doped n type crystalline silicon field passivation layer I (4).

Further, in order to improve the performance of the device, the thickness of the heavily doped n-type crystalline silicon field passivation layer I (4) is preferably 1-300 nm.

A two-sided solar cell structure of local projecting pole homogeneity crystalline substance silicon, for two-sided light solar cell that advances, its positive and negative electrode is located two surfaces of n type crystalline substance silicon chip (5) basement respectively, advances light solar cell for two-sided. The other side (back electric field side) of the solar cell except the emitter side has the following structure: the method is divided into a passivation-light entering area and a back electric field-conductive area: a heavily doped n-type crystalline silicon layer II (6) is arranged on the substrate of the n-type crystalline silicon wafer (5), and the heavily doped n-type crystalline silicon layer II (6) covers the passivation-light inlet region and the back electric field-conductive region; a passivated antireflection layer II (7) is arranged outside the n-type crystalline silicon layer II (6) of the passivated-light entering region; and a metal grid line II (8) is arranged outside the n-type crystal silicon layer II (6) of the back electric field-conductive region. The two regions are distributed across and do not overlap.

Among them, the passivated antireflection layer II (7) is preferably a silicon nitride layer.

Further, for the performance that improves the device, n type crystal silicon piece (5) can two-sided system fine hair to further improve solar cell short circuit current.

Furthermore, the texturing conditions of the two sides of the n-type crystal silicon wafer (5) can be different, one side of the n-type crystal silicon wafer adopts a textured surface with a pyramid structure with a smaller size, and the other side of the n-type crystal silicon wafer adopts a pyramid textured surface with a larger size or a polishing structure without pyramids.

Furthermore, the area with the metal grid lines (metal grid line I and metal grid line II) can be polished or textured with pyramids with larger sizes so as to reduce recombination loss and improve the open-circuit voltage of the solar cell.

Furthermore, the proportion of the total coverage area of the metal grid lines (metal grid lines I and metal grid lines II) on the surface of the device is preferably 1-3% so as to improve the short-circuit current of the solar cell and ensure good enough conductivity.

The technical effects of the utility model are that: the utility model is suitable for a monocrystalline silicon piece solar cell, polycrystalline silicon piece solar cell and accurate monocrystalline silicon piece solar cell. On the premise of keeping the double-sided light inlet characteristics of the crystalline silicon solar cell, higher open-circuit voltage and short-circuit current are obtained, and the power generation capacity of the crystalline silicon solar cell is improved to the greatest extent. The mechanism is that high open-circuit voltage is obtained through the p-type heavily doped crystalline silicon emitter and a matched structure under the coverage area of the metal grid line, and the structure can only consider the electrical performance of the emitter and does not need to balance the degree of light absorption loss like an emitter layer in a PERT structure; compared with a structure that a heavy doping n-type crystalline silicon field passivation layer is combined with a surface antireflection passivation layer at a position without a metal grid line, the structure can reduce short-circuit current and open-circuit voltage reduction caused by carrier recombination loss compared with a structure that a PERT full-surface heavy doping p-type layer is combined with a passivation layer. On the emitter surface, the generated photo-generated holes enter the bulk silicon under the push of a built-in electric field formed by the heavily doped n-type layer, and then flow to the emitter region in a concentrated manner, so that a high-current effect similar to a concentrating solar cell is formed, the built-in potential of the solar cell can be further improved, and the voltage of the solar cell is further improved; the generated electrons only flow to the metal electrode on the other side of the silicon chip to be collected because the heavily doped n-type region of the emitter surface has no electrode.

Drawings

Fig. 1 is a schematic diagram of the present invention. Wherein: 1 is a metal grid line I; 2 is a heavily doped p-type crystalline silicon layer; 3 is a passivated antireflection layer I; 4 is a heavily doped n-type crystalline silicon field passivation layer I; 5 is an n-type crystal silicon wafer; 6 is a heavily doped n-type crystalline silicon layer II; 7 is a passivated antireflection layer II; and 8 is a metal grid line II.

Detailed Description

The present invention will be further illustrated by the following examples.

Example 1.

A local emitter homocrystalline silicon bifacial solar cell structure as shown in figure 1. The two sides of the n-type crystal silicon wafer 5 are both provided with pyramid structured suede with the average size of 2 microns, the thickness of a heavily doped n-type crystal silicon field passivation layer I4 is 10nm, the thickness of a heavily doped n-type crystal silicon layer II 6 is 200nm, the passivation antireflection layer I3 and the passivation antireflection layer II 7 are both provided with silicon nitride films, the metal grid lines I1 and the metal grid lines II 8 are both provided with Ag grid line structures matched with main and auxiliary grids, and the covering area is 3% of the surface area of the silicon wafer. The structure has excellent double-sided light entering characteristics, namely, any one side can be used as a main light entering surface. If the solar cell is used as a single-side light-entering solar cell, a layer of metal can be plated on the back light surface to be used as a reflecting layer, so that the short-circuit current of the single-side light-entering solar cell is increased. The emitter face is preferably used as the main light-facing face.

The light inlet characteristics of the two surfaces of the structure are both excellent, and the two surfaces of the structure can be used as main light inlet surfaces. If the solar cell is used as a single-side light-entering solar cell, a layer of metal can be plated on the back light surface to be used as a reflecting layer, so that the short-circuit current of the single-side light-entering solar cell is increased.

Example 2.

A local emitter homocrystalline silicon bifacial solar cell structure as shown in figure 1. The two sides of the n-type crystal silicon wafer 5 are both provided with pyramid structured suede with the average size of 3 micrometers, the thickness of a heavily doped n-type crystal silicon field passivation layer I4 is 10nm, the thickness of a heavily doped n-type crystal silicon layer II 6 is 300nm, the passivation antireflection layer I3 and the passivation antireflection layer II 7 are both provided with silicon nitride films, the metal grid lines I1 and the metal grid lines II 8 are both provided with Ni/Cu/Ag grid line structures matched with main and auxiliary grids (the surfaces of the silicon wafers are in direct contact with Ni), and the covering area is 1% of the surface area of the silicon wafer. The structure has excellent double-sided light entering characteristics, namely, any one side can be used as a main light entering surface. If the solar cell is used as a single-side light-entering solar cell, a layer of metal can be plated on the back light surface to be used as a reflecting layer, so that the short-circuit current of the single-side light-entering solar cell is increased. The emitter face is preferably used as the main light-facing face.

Claims

1. A local emitter homogeneous crystal silicon double-sided solar cell structure is characterized in that an n-type crystal silicon wafer (5) is used as a substrate, and an emitter surface is divided into an emitter-conductive area and a passivation-light inlet area: the emitter-conductive region is formed by a heavily doped p-type crystalline silicon emitter layer (2) and a metal grid line I (1) from a substrate to the outside in sequence, the passivation-light inlet region is formed by a heavily doped n-type crystalline silicon field passivation layer I (4) and a passivation antireflection layer I (3) from the substrate to the outside in sequence, and the two regions are distributed in a crossed manner and are not overlapped;

the back electric field surface structure is divided into a passivation-light inlet area and a back electric field-conductive area: a heavily doped n-type crystalline silicon layer II (6) is arranged on the substrate of the n-type crystalline silicon wafer (5), and the heavily doped n-type crystalline silicon layer II (6) covers the passivation-light inlet region and the back electric field-conductive region; a passivated antireflection layer II (7) is arranged outside the n-type crystalline silicon layer II (6) of the passivated-light entering region; the outside of the n-type crystalline silicon layer II (6) of the back electric field-conductive region is provided with a metal grid line II (8), and the two regions are distributed in a crossed way and do not overlap.

2. The structure of claim 1, wherein said passivated anti-reflective layer I (3) is a silicon nitride layer.

3. The structure of claim 1, wherein an insulating layer is disposed between the emitter and the heavily doped n-type crystalline silicon field passivation layer I (4).

4. The structure of a local emitter homo-crystalline silicon bifacial solar cell as claimed in claim 1, wherein the thickness of the heavily doped n-type crystalline silicon field passivation layer I (4) is 1-300 nm.

5. The structure of a locally emitting homocrystalline silicon bifacial solar cell as claimed in claim 1, wherein said passivated anti-reflective layer II (7) is a silicon nitride layer.

6. The structure of claim 1, wherein the ratio of the total area covered by metal grid lines on the surface of the device is 1-3%.