阅读说明：本技术 一种柔性太阳电池及其制作方法 (Flexible solar cell and manufacturing method thereof ) 是由 龙军华 肖梦 黄欣萍 李雪飞 陆书龙 于 2018-08-09 设计创作，主要内容包括：本发明公开了一种柔性太阳电池及其制作方法，该方法包括：在衬底上制作分离层；在分离层上倒装生长太阳电池；在太阳电池背面沉积背面电极；在背面电极上制作金属薄膜；将金属薄膜键合到临时衬底上；将分离层和太阳电池分离；在太阳电池正面沉积正面电极；将临时衬底与金属薄膜解键合；本发明通过在制作电池的过程中只进行一次键合与解键合，相比于现有技术的两次键合与解键合更为简单，提高了生产效率；解键合过程快速且不损伤电池和临时衬底；利用电镀金属薄膜的延展性作为柔性衬底，不仅柔韧性好，还降低了生产成本，具有产业化的应用价值。(The invention discloses a flexible solar cell and a manufacturing method thereof, wherein the method comprises the following steps: manufacturing a separation layer on a substrate; growing a solar cell on the separation layer in a flip-chip manner; depositing a back electrode on the back of the solar cell; manufacturing a metal film on the back electrode; bonding a metal film to the temporary substrate; separating the separation layer from the solar cell; depositing a front electrode on the front side of the solar cell; debonding the temporary substrate from the metal film; according to the invention, only one time of bonding and bonding release is carried out in the process of manufacturing the battery, compared with the prior art, the two times of bonding and bonding release are simpler, and the production efficiency is improved; the bonding process is rapid and does not damage the battery and the temporary substrate; the ductility of the electroplated metal film is used as a flexible substrate, so that the flexibility is good, the production cost is reduced, and the industrialized application value is realized.)

1. A method for manufacturing a flexible solar cell is characterized by comprising the following steps:

manufacturing a separation layer on a substrate;

growing a solar cell on the separation layer in a flip-chip manner;

manufacturing a back electrode on the back of the solar cell;

manufacturing a metal film on the back electrode;

bonding the metal thin film to a temporary substrate;

separating the separation layer from the solar cell;

manufacturing a front electrode on the front side of the solar cell;

and debonding the temporary substrate from the metal film.

2. The method of claim 1, wherein the separation layer is a corrosion barrier layer; wherein the method for separating the separation layer from the solar cell comprises:

corroding and removing the substrate in a wet stripping mode;

and stripping and removing the corrosion barrier layer by adopting a wet stripping mode.

3. The method of claim 1, wherein the separation layer is a sacrificial layer; wherein the method for separating the separation layer from the solar cell comprises: and removing the sacrificial layer by adopting a wet stripping mode.

4. The method of claim 1, wherein after the front side electrode of the solar cell is fabricated, the method further comprises: and manufacturing an anti-reflection film on the front electrode.

5. The method of claim 1, wherein the solar cell is a multijunction solar cell.

6. The method of claim 1, wherein the bonding the metal film to the temporary substrate comprises: and bonding the metal film and the temporary substrate by using low-temperature bonding glue at a low temperature.

7. The method as claimed in claim 6, wherein the low temperature bonding glue is a low temperature curing silica gel.

8. The method of claim 6 or 7, wherein the method of debonding the temporary substrate from the metal thin film comprises: and dissolving and removing the low-temperature bonding glue by using a low-temperature glue cleaning agent.

9. The method of claim 1, wherein the method of forming a metal film on the back electrode comprises:

electroplating on the back electrode by using an electroplating process to form a metal film;

and carrying out mechanical chemical polishing treatment on the surface of the metal film.

10. A flexible solar cell made by the method of any one of claims 1-9.

Technical Field

The invention belongs to the technical field of solar cells, and particularly relates to a flexible solar cell and a manufacturing method thereof.

Background

The flexible solar cell is concerned in aerospace field, military field and even civil market due to its characteristics of light weight, high mass-power ratio, flexibility, various environmental adaptation and the like. Meanwhile, as the solar cell has increasingly strong requirements for high efficiency and low cost, the structure of the solar cell is developed towards a multi-junction direction.

The currently more common method is to use a secondary temporary bond. Forming a bonding metal layer on the back of the flexible solar cell, carrying out first temporary bonding, then removing the first substrate to expose the surface of the bonding metal layer, and then bonding again on the bonding metal layer to form a metal material film with a thermal expansion coefficient lower than that of the bonding metal layer so as to realize a flexible supporting function. However, the method has two bonding operations, the process is complex, repeated bonding and debonding are needed, the production cost is high, and the production efficiency is low. The first bonding operation has high requirements on the surface roughness of the battery, the bonding is complex, and the second bonding operation causes the warping of the metal material film under the high-temperature condition and the reduction of the yield because the thermal expansion coefficients of the materials are different.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a flexible solar cell which is manufactured by one-time bonding and debonding, has low production cost and quick and efficient production process and a manufacturing method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

in one general aspect, there is provided a method of fabricating a flexible solar cell, comprising:

manufacturing a separation layer on a substrate;

growing a solar cell on the separation layer in a flip-chip manner;

manufacturing a back electrode on the back of the solar cell;

manufacturing a metal film on the back electrode;

bonding the metal thin film to a temporary substrate;

separating the separation layer from the solar cell;

manufacturing a front electrode on the front side of the solar cell;

and debonding the temporary substrate from the metal film.

Preferably, the separation layer is a corrosion barrier layer; wherein the method for separating the separation layer from the solar cell comprises:

corroding and removing the substrate in a wet stripping mode;

and stripping and removing the corrosion barrier layer by adopting a wet stripping mode.

Preferably, the separation layer is a sacrificial layer; wherein the method for separating the separation layer from the solar cell comprises: and removing the sacrificial layer by adopting a wet stripping mode.

Preferably, after the front electrode is fabricated on the front surface of the solar cell, the fabrication method further includes: depositing an anti-reflective film on the front electrode.

Preferably, the solar cell is a multijunction solar cell.

Preferably, the method for bonding the metal thin film to the temporary substrate includes: and bonding the metal film and the temporary substrate by using low-temperature bonding glue at a low temperature.

Preferably, the low-temperature bonding glue is low-temperature curing silica gel.

Preferably, the method for debonding the temporary substrate from the metal thin film includes: and cleaning and removing the low-temperature bonding glue by using a low-temperature glue cleaning agent.

Preferably, the method for forming a metal thin film on the back electrode includes:

electroplating on the back electrode by using an electroplating process to form a metal film;

and carrying out mechanical chemical polishing treatment on the surface of the metal film.

In another general aspect, there is provided a flexible solar cell made by the above method of making a flexible solar cell.

The invention provides a flexible solar cell and a manufacturing method thereof, wherein bonding and bonding release are only carried out once in the process of manufacturing the cell, and compared with the prior art, bonding and bonding release are simpler twice, so that the production efficiency is improved; the bonding process is rapid and does not damage the battery and the temporary substrate; the ductility of the electroplated metal film is used as a flexible substrate, so that the flexibility is good, the production cost is reduced, and the industrialized application value is realized.

Drawings

Fig. 1 is a flow chart of a method of fabricating a flexible solar cell of the present invention;

FIG. 2 is a flow chart of the present invention for forming a metal film on a back electrode;

fig. 3 is a process flow diagram of a flexible solar cell of the present invention;

fig. 4 is a schematic view of a structure of a cell unit of the solar cell of the present invention.

In the figure:

10 a substrate;

20 separating layer;

30 solar cells;

40 a back electrode;

50 a metal thin film;

60 low-temperature bonded silica gel;

70 a temporary substrate;

80 a front electrode;

90 an antireflection film;

100 window layers;

110 an emission area;

a 120 base region;

130 back field layer.

Detailed Description

The invention aims to provide a manufacturing method for quickly and efficiently manufacturing a flexible solar cell by only carrying out bonding and bonding-releasing processes once in the manufacturing process. Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As an embodiment of the present invention, as shown in fig. 1 and fig. 3, a method for manufacturing a flexible solar cell of the present embodiment includes:

s01, manufacturing a separation layer on the substrate. The substrate is made of a semiconductor material GaAs, and the band gap of the GaAs material is matched with the solar spectrum, so that the high-efficiency multi-junction solar cell can be grown. The separation layer is a sacrificial layer made of AlAs, and the sacrificial layer is a structure to be removed when the substrate and the solar cell are separated.

And S02, growing the solar cell on the separation layer in a flip-chip mode. In order to obtain a solar cell with higher photoelectric conversion efficiency, the solar cell can be arranged into three junctions, four junctions or more junctions, so that the cell can absorb light in different wave bands. In the present embodiment, each junction of the solar cell is a cell unit.

As shown in fig. 4, each cell unit has a window layer, an emitter region, a base region, and a back field layer, where the window layer is located on the front surface of the solar cell, and the back field layer is located on the back surface of the solar cell. When the solar cell is manufactured, the solar cell is grown in a flip-chip manner, namely, when each cell unit of the solar cell is prepared, a window layer, an emitter region, a base region and a back field layer are sequentially manufactured on a substrate.

And S03, depositing a back electrode on the back of the solar cell. Wherein, the back electrode material is Ti/Pt/Au. The specific method of the deposition process comprises the following steps: and (3) evaporating Ti/Pt/Au by using an electron beam, depositing the Ti/Pt/Au on the back surface of the solar cell to form a back surface electrode, and then carrying out rapid annealing on the back surface electrode to form ohmic contact with the solar cell.

And S04, manufacturing a metal film on the back electrode to be used as a flexible substrate. With reference to fig. 2, the method for manufacturing a metal film on the back electrode in this embodiment specifically includes:

and S041, depositing the metal film on the back electrode through an electroplating process. The metal film is made of Cu, and the metal Cu has good ductility and can be used as a flexible substrate.

And S042, performing mechanical chemical polishing treatment on the surface of the metal film. The bonding operation has high requirement on the roughness of the operation surface, so that the metal film needs to be subjected to mechanical chemical polishing treatment, and after the treatment is finished, the thickness of the metal film is 10-20 mu m.

And S05, bonding the metal film to a temporary substrate. The bonding process is carried out in a vacuum environment, high vacuum is beneficial to discharge of gas molecules at a bonding interface, and the contact area is increased; and bonding the metal film on a temporary substrate by using low-temperature bonding glue, wherein the temporary substrate is made of a material with a thermal expansion coefficient similar to that of the solar cell and can be GaAs or glass. The low-temperature bonding glue is low-temperature curing silica gel with the heat curing temperature of 90 ℃ and the heat stability temperature of 300 DEG C

S06, separating the separation layer from the solar cell; in this embodiment, the separation layer is a sacrificial layer, the method for separating the sacrificial layer from the solar cell is a wet stripping process, the sacrificial layer is etched away by the wet stripping process, so that the substrate and the solar cell can be separated, and the separated substrate is not damaged and can be reused.

And S07, depositing a front electrode on the front surface of the solar cell. After the solar cell is separated from the substrate, the front side of the solar cell is exposed, a front side electrode is deposited on the front side, the material of the front side electrode is AuGe/Ni/Au, and ohmic contact can be formed with the solar cell without annealing after deposition; the AuGe/Ni/Au is in a stripe shape, so that light can conveniently penetrate and irradiate the solar cell. If the cell manufactured at one time is large, an isolation groove can be etched on the solar cell to divide the solar cell into required sizes.

S08, depositing an anti-reflection film on the front electrode. The antireflection film covers the front electrode, so that the reflection of light on the surface of the cell is greatly reduced, more light can be absorbed by the cell, and the energy conversion rate of the solar cell is improved.

And S09, debonding the temporary substrate and the metal film. Because stress exists between the metal film and the temporary substrate, in the low-temperature adhesive cleaning agent, along with the gradual dissolution of the low-temperature bonding adhesive, the stress exists between the metal film and the temporary substrate due to the difference of the lattice constant and the thermal expansion coefficient, so that the metal film and the temporary substrate can be separated, and the flexible solar cell can be obtained, and the separated temporary substrate cannot be damaged and can be reused.

As a preferred embodiment, the solar cell described in this embodiment has three cells, which are a GaInP layer, a GaAs layer, and an InGaAs layer in this order. The solar cell is manufactured on the substrate sequentially from the GaInP layer, the GaAs layer and the InGaAs layer. The GaInP layer has a cell band gap of 1.88eV, the GaAs layer has a cell band gap of 1.42eV, and the InGaAs layer has a cell band gap of 1.05 eV. Wherein the InGaAs layer is grown with a cell mismatch.

As another embodiment of the present invention, different from the previous embodiment, the separation layer is a corrosion barrier layer for preventing damage to the solar cell when the substrate and the solar cell are separated, so that the material of the corrosion barrier layer is GaInP. The method for separating the separation layer from the solar cell includes: and stripping the substrate by adopting a wet stripping method, wherein the solution for stripping the substrate can be a mixed solution prepared from hydrogen peroxide, ammonia water and water, the corrosion barrier layer plays a role in protecting the solar cell, when the substrate is stripped cleanly, the corrosion barrier layer is stripped by adopting the wet stripping method again, the solution for stripping the corrosion barrier layer can be a mixed solution prepared from hydrochloric acid and phosphoric acid, and the front surface of the solar cell is exposed after the stripping is finished. However, this method can damage the substrate, which cannot be reused.

The invention provides a flexible solar cell and a manufacturing method thereof, wherein bonding and bonding release are only carried out once in the process of manufacturing the cell, and compared with the prior art, bonding and bonding release are simpler twice, so that the production efficiency is improved; the bonding process is rapid and does not damage the battery and the temporary substrate; the ductility of the electroplated metal film is used as a flexible substrate, so that the flexibility is good, the production cost is reduced, and the industrialized application value is realized.

The foregoing is directed to embodiments of the present application and it is noted that numerous modifications and adaptations may be made by those skilled in the art without departing from the principles of the present application and are intended to be within the scope of the present application.