CN110311006A - A kind of multijunction solar cell and production method improving anti-radiation performance - Google Patents

Abstract

The present application provides a multi-junction solar cell with improved radiation resistance and a manufacturing method thereof, the multi-junction solar cell at least includes an InGaAs sub-cell and a GaInP sub-cell, wherein the GaInP sub-cell is a top cell, and the InGaAs sub-cell is an intermediate cell The side of the top cell facing away from the middle cell is also provided with a photoconductive contact layer, and the material of the photoconductive contact layer is GaInP or AlGaInP. The photoconductive contact layer is used to replace the ohmic contact layer in the prior art, so as to prevent the ohmic contact layer from absorbing the corresponding absorption spectrum of the top cell GaInP and the middle cell InGaAs sub-cell, therefore, the light absorption of the top cell GaInP, especially the middle cell InGaAs sub-cell can be improved efficiency. Since the light absorption efficiency of the InGaAs sub-cell is improved, the corresponding photoelectric conversion efficiency is improved, and the thickness of the intermediate sub-cell can be reduced, thereby improving the radiation resistance performance of the multi-junction solar cell.

Description

A multi-junction solar cell with improved radiation resistance performance and its manufacturing method

technical field

The invention relates to the technical field of solar cells, in particular to a multi-junction solar cell with improved radiation resistance performance and a manufacturing method.

Background technique

Solar cells convert solar energy directly into electricity and are the most efficient form of clean energy. III-V compound semiconductor solar cells have the highest conversion efficiency in the current material system, and have the advantages of good high temperature resistance and strong radiation resistance. They are recognized as a new generation of high-performance and long-life space main power supplies. /Ge lattice-matched triple-junction cells have been widely used in the aerospace field.

There is high-energy charged particle radiation in the space application environment. These charged particles enter the solar cell to displace the lattice atoms, forming a large number of lattice defects such as vacancies, interstitial atoms and complexes. These defects can become the recombination centers of carriers, shorten the lifetime of photogenerated carriers, reduce the photoelectric conversion efficiency of solar cells, and directly affect the on-orbit working life and reliability of spacecraft.

Therefore, how to improve the anti-irradiation performance of solar cells, and then improve the photoelectric conversion efficiency of solar cells has become an urgent problem to be solved.

Contents of the invention

In view of this, the present invention provides a multi-junction solar cell with improved radiation resistance and a manufacturing method to solve the problem of low photoelectric conversion efficiency of solar cells due to limited radiation resistance of solar cells in the prior art.

To achieve the above object, the present invention provides the following technical solutions:

A multi-junction solar cell with improved radiation resistance, comprising:

At least three-junction sub-cells, the three-junction sub-cells at least include InGaAs sub-cells, and GaInP sub-cells or AlGaInP sub-cells, the GaInP sub-cells or AlGaInP sub-cells are the top cells of the multi-junction solar cell, and the InGaAs sub-cells a cell being an intermediate cell positioned between a bottom cell and the top cell of the multijunction solar cell;

a photoconductive contact layer on the side of the top cell facing away from the bottom cell;

A transparent electrode located on the side of the photoconductive contact layer away from the top cell, the transparent electrode has a grid line structure, and the projections of the photoconductive contact layer and the transparent electrode on the top cell overlap;

Wherein, the material of the light guiding contact layer is GaInP or AlGaInP.

Preferably, it also includes:

an ohmic contact layer, the ohmic contact layer is located on the surface of the photoconductive contact layer facing the transparent electrode;

Wherein, the material of the ohmic contact layer is AuGeNi.

Preferably, the ohmic contact layer has a thickness ranging from 2nm to 10nm, inclusive.

Preferably, the photoconductive contact layer has a thickness ranging from 0.2 μm to 1 μm, including endpoint values; the photoconductive contact layer is an n-type contact layer, and the doping concentration of n-type impurities ranges from 1×10 ¹⁸ /cm ³ to 1 ×10 ¹⁹ /cm ³ , inclusive of endpoint values.

Preferably, the transparent electrodes are ITO electrodes, IZO electrodes, IGZO electrodes, AZO electrodes or graphene electrodes.

Preferably, it also includes: a corrosion stop layer;

The etch stop layer is located on the surface of the photoconductive contact layer facing the bottom cell.

Preferably, the etch stop layer is made of n-type AlGaAs material.

Preferably, the thickness of the corrosion stop layer ranges from 1 nm to 20 nm, inclusive; wherein, the Al component is greater than 0.35 and less than 1.

Preferably, the multi-junction solar cell is a triple-junction solar cell, and the triple-junction solar cell includes:

A Ge bottom cell, an InGaAs middle cell, and a top cell are sequentially arranged along the growth direction, and the top cell is a GaInP top cell or an AlGaInP top cell.

Preferably, the multi-junction solar cell is a four-junction solar cell, and the four-junction solar cell comprises:

A first Ge subcell, a second InGaAs subcell, a third AlInGaAs subcell, and a fourth GaInP subcell or a fourth AlGaInP subcell are sequentially arranged along the growth direction.

The present invention also provides a method for manufacturing a multi-junction solar cell with improved radiation resistance, which is used to manufacture the multi-junction solar cell with improved radiation resistance described in any one of the above, and the method includes:

provide the substrate;

forming a bottom cell on one side of the substrate;

forming an InGaAs sub-cell on the side of the bottom cell facing away from the substrate;

forming a GaInP sub-cell on the side of the InGaAs sub-cell facing away from the substrate;

growing and forming a photoconductive contact layer on the side of the GaInP sub-cell away from the InGaAs sub-cell, and the material of the photoconductive contact layer is GaInP or AlGaInP;

forming a transparent electrode on the side of the photoconductive contact layer away from the GaInP sub-cell;

Wherein, the transparent electrode is a grid line structure, and the projection of the photoconductive contact layer and the transparent electrode on the top cell overlap.

Preferably, before the growth of the GaInP sub-cell away from the side of the InGaAs sub-cell to form the photoconductive contact layer, it may further include:

forming a corrosion stop layer on the surface of the GaInP sub-cell away from the InGaAs sub-cell;

forming an entire layer of photoconductive contact layer on the surface of the corrosion stop layer away from the GaInP sub-cell;

A wet etching process is used to remove part of the photoconductive contact layer and the etching stop layer, so as to form a photoconductive contact layer with a gate line structure.

It can be known from the above technical solutions that the multi-junction solar cell with improved radiation resistance provided by the present invention includes at least an InGaAs sub-cell and a GaInP sub-cell, wherein the GaInP sub-cell is the top cell, the InGaAs sub-cell is the middle cell, and the top cell A photoconductive contact layer is provided on the side away from the middle cell, and a transparent electrode is provided on the side of the photoconductive contact layer away from the top cell. The material of the photoconductive contact layer in the present invention is GaInP or AlGaInP. A photoconductive contact layer is used to replace the ohmic contact layer in the prior art. Since the absorption spectrum of the photoconductive contact layer mainly absorbs the sunlight in the range of 0.25 μm-0.65 μm, but does not absorb the main absorption spectrum of the InGaAs sub-cell of the intermediate cell, the light absorption efficiency of the InGaAs sub-cell of the intermediate cell can be improved. Since the light absorption efficiency of the InGaAs sub-cell is improved, the corresponding photoelectric conversion efficiency is improved. Based on this, the thickness of the InGaAs sub-cell of the intermediate sub-cell can be reduced.

The inventors found that in the space environment, the electrical performance of the InGaAs middle cell decays faster than that of the GaInP top cell, that is, the radiation resistance of InGaAs is relatively weaker. When the thickness of the InGaAs sub-cell is reduced, it can be relatively Improve the anti-irradiation ability of InGaAs, and then improve the anti-irradiation performance of the entire multi-junction solar cell.

At the same time, since the photoconductive contact layer only absorbs part of the spectrum corresponding to the top cell, and the light received by the top cell increases after the transparent electrode is used, the multi-junction solar cell with improved radiation resistance provided by the present invention also has a certain light absorption efficiency for the top cell. improve.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings on the premise of not paying creative efforts.

Fig. 1 is a schematic structural diagram of a multi-junction solar cell with improved radiation resistance provided by an embodiment of the present invention;

Figure 2 is a schematic structural diagram of another multi-junction solar cell with improved radiation resistance provided by an embodiment of the present invention;

Fig. 3 is a schematic structural diagram of a front-mounted lattice-matched triple-junction solar cell provided by an embodiment of the present invention;

Fig. 4 is a schematic structural diagram of a triple-junction solar cell with frontal lattice mismatch provided by an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a front-loaded lattice-mismatched four-junction solar cell provided by an embodiment of the present invention.

Detailed ways

As mentioned in the background section, multi-junction solar cells in the prior art have limited radiation resistance, and are easily irradiated by high-energy charged particles in a space application environment, resulting in a decrease in the photoelectric conversion efficiency of the solar cell.

The inventors found that the main reason for the above phenomenon is that the multi-junction solar cells widely used in the aerospace field in the prior art usually include GaInP top cells and InGaAs intermediate cells. In the space environment, the electrical performance of the InGaAs intermediate cell declines faster than that of the GaInP top cell. Therefore, how to improve the radiation resistance of the InGaAs sub-cell is of great significance for improving the radiation resistance and reliability of solar cells in space applications.

Then, in order to improve the radiation resistance of solar cells, it is necessary to reduce the proportion of InGaAs intermediate cells while ensuring that the overall photoelectric conversion efficiency of solar cells is high or unchanged. The inventors found that, in the prior art, in the manufacture of existing III-V solar cell devices, strip-shaped metal grid lines are usually used, so that photogenerated carriers can be better collected and transported.

However, the opaque metal grid electrode will reflect and absorb the incident light, which reduces the effective light-receiving area of the solar cell device, thereby reducing the output power of the cell. Therefore, the gate line and electrode structure are optimized to be transparent electrodes, and an ohmic contact layer is arranged between the transparent electrodes and the top cell to electrically connect the transparent electrodes to the top cell. This can also reduce the use of noble metal electrodes such as gold and silver, which is of great significance for reducing the preparation cost of III-V solar cell chips.

Although the light-absorbing area increases, it is found through experiments that the photoelectric conversion efficiency of the solar cell has been improved, but the radiation resistance performance has not been significantly improved. The inventors found that this is because the material of the ohmic contact layer in the prior art is InGaAs, because the ohmic contact layer also absorbs the sunlight spectrum, which is the same as the absorption spectrum of the intermediate battery InGaAs sub-cell in the solar cell. When sunlight enters the sub-cells through the ohmic contact layer, the absorption spectrum of the intermediate cell InGaAs has been absorbed by the ohmic contact layer, so the photoelectric conversion efficiency of the intermediate cell InGaAs has not been improved, but the photoelectricity of other sub-cells has been improved. conversion efficiency. However, in the space environment, the electrical performance of the InGaAs intermediate cell declines faster than that of the GaInP top cell, so the radiation resistance of the solar cell does not improve.

Based on this, the present invention provides a multi-junction solar cell with improved radiation resistance, including:

At least three-junction sub-cells, the three-junction sub-cells at least include InGaAs sub-cells, and GaInP sub-cells or AlGaInP sub-cells, the GaInP sub-cells or AlGaInP sub-cells are the top cells of the multi-junction solar cell, and the InGaAs sub-cells a cell being an intermediate cell positioned between a bottom cell and the top cell of said multijunction solar cell;

a photoconductive contact layer on the side of the top cell facing away from the bottom cell;

A transparent electrode located on the side of the photoconductive contact layer away from the top cell, the transparent electrode has a grid line structure, and the projections of the photoconductive contact layer and the transparent electrode on the top cell overlap;

Wherein, the material of the light guiding contact layer is GaInP or AlGaInP.

The material of the light guide contact layer in the present invention is GaInP or AlGaInP. A photoconductive contact layer is used to replace the ohmic contact layer in the prior art. Since the absorption spectrum of the photoconductive contact layer mainly absorbs sunlight in the range of 0.25 μm-0.65 μm, and the main absorption spectrum of the InGaAs sub-cell of the intermediate cell absorbs less, the light absorption efficiency of the InGaAs sub-cell of the intermediate cell can be improved. Since the light absorption efficiency of the InGaAs sub-cell is improved, the corresponding photoelectric conversion efficiency is improved. Based on this, the thickness of the InGaAs sub-cell of the intermediate sub-cell can be reduced. When the thickness of the InGaAs sub-cell is reduced, the proportion of the InGaAs sub-cell is relatively small, which can relatively improve the radiation resistance of InGaAs, thereby improving the radiation resistance of the entire multi-junction solar cell.

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The multi-junction solar cell with improved radiation resistance provided by the embodiment of the present invention, as shown in Figure 1, includes:

At least three-junction sub-cells, the three-junction sub-cells at least include InGaAs sub-cells 01 and GaInP sub-cells or AlGaInP sub-cells 02, the GaInP sub-cells or AlGaInP sub-cells 02 are the top cells of multi-junction solar cells, and the InGaAs sub-cell 01 is located at The middle cell between the bottom cell 03 and the top cell 02 of the multi-junction solar cell; the photoconductive contact layer 04 located on the side of the top cell 02 away from the bottom cell 03; the transparent electrode 05 located on the side of the photoconductive contact layer 04 away from the top cell, transparent The electrode 05 has a grid line structure, and the projections of the photoconductive contact layer 04 and the transparent electrode 05 on the top cell 02 overlap; wherein, the material of the photoconductive contact layer 04 is GaInP or AlGaInP.

The specific number of junctions of the multi-junction solar cell is not limited in the embodiment of the present invention, the multi-junction solar cell may be a triple-junction solar cell or a four-junction solar cell, and the triple-junction solar cell and the four-junction solar cell It may be a lattice-matched multi-junction solar cell or a lattice-mismatched multi-junction solar cell, which is not limited in this embodiment of the present invention. Wherein, the triple-junction solar cell may include: a Ge bottom cell, an InGaAs middle cell, and a GaInP top cell arranged in sequence along the growth direction. The four-junction solar cell may include: a first Ge subcell, a second InGaAs subcell, a third AlInGaAs subcell, and a fourth GaInP subcell arranged in sequence along the growth direction.

In the embodiment of the present invention, the transparent electrode 05 is a conductive material with high light transmittance. In an embodiment of the present invention, the material of the transparent electrode is indium tin oxide, Al-doped zinc oxide or graphene. That is, the transparent electrode is an indium tin oxide electrode, an Al-doped zinc oxide electrode or a graphene electrode.

It should be noted that, in order to improve the ohmic contact between the photoconductive contact layer and the transparent electrode, the embodiment of the present invention may also include an ohmic contact layer 06, please refer to FIG. 2, which is another embodiment of the present invention. Schematic diagram of the multi-junction solar cell structure; the ohmic contact layer is located on the surface of the photoconductive contact layer facing the transparent electrode; wherein, the material of the ohmic contact layer is AuGeNi. In order to ensure a better ohmic contact effect and avoid more light absorption by the ohmic contact layer, in the embodiment of the present invention, optionally, the thickness of the ohmic contact layer ranges from 2 nm to 10 nm, including the endpoint values. Since the material of the ohmic contact layer is a metal alloy, when the thickness is relatively thin, it is basically a transparent structure and absorbs less light. However, if the thickness is too thin, the ohmic contact effect cannot be achieved, so the thickness range is limited.

Similarly, when the thickness of the photoconductive contact layer is large, it absorbs more light and absorbs more of the absorbable spectrum of the GaInP top cell, which affects the photoelectric conversion efficiency of the GaInP top cell. When the thickness of the light guide contact layer is relatively thin, it cannot play the role of contact. Therefore, in the embodiment of the present invention, the thickness range of the light guide contact layer is 0.2 μm-1 μm, including the endpoint value; the light guide contact layer in this embodiment is For the n-type contact layer, the doping concentration of n-type impurities ranges from 1×10 ¹⁸ /cm ³ to 1×10 ¹⁹ /cm ³ , including the endpoint values.

The manufacturing method of the multi-junction solar cell is not limited in the embodiment of the present invention. It should be noted that since the transparent electrode is a grid structure, and the photoconductive contact layer overlaps with the projection of the transparent electrode on the top cell, the photoconductive contact layer in the embodiment of the present invention overlaps with the projection of the transparent electrode on the top cell. The layers are also gridline structured. In the manufacturing process, the photoconductive contact layer with the gate line structure can be formed by wet etching process, or the photoconductive contact layer with gate line structure can be formed by dry etching process, which is not limited in this embodiment. It should be noted that, in order to control the precision of wet etching when wet etching process is used to form the photoconductive contact layer with grid line structure, this embodiment also includes an etching stop layer, and the etching stop layer is located at the A photoconductive contact layer faces the surface of the bottom cell. In this way, during the manufacturing process, when wet etching the photoconductive contact layer to form the gate line structure, it can stop on the etching stop layer, so as to control the etching precision of wet etching.

The material of the corrosion cut-off layer is different from that of the photoconductive contact layer, and when the wet etching process is used, the etching rate differs greatly, so that it can play the role of corrosion cut-off. Optionally in this embodiment, the The corrosion stop layer is made of n-type AlGaAs material. Optionally, the thickness of the corrosion stop layer ranges from 1 nm to 20 nm, inclusive; wherein, the Al component is greater than 0.35 and less than 1.

The multi-junction solar cell with improved radiation resistance provided by the present invention includes at least an InGaAs sub-cell and a GaInP sub-cell, wherein the GaInP sub-cell is a top cell, the InGaAs sub-cell is an intermediate cell, and the side of the top cell away from the intermediate cell is also A photoconductive contact layer is provided, and a transparent electrode is provided on the side of the photoconductive contact layer away from the top battery. In the present invention, the material of the photoconductive contact layer is GaInP or AlGaInP. A photoconductive contact layer is used to replace the ohmic contact layer in the prior art. Since the absorption spectrum of the photoconductive contact layer mainly absorbs sunlight in the range of 0.25 μm-0.65 μm, and the main absorption spectrum of the InGaAs sub-cell of the intermediate cell absorbs less, the light absorption efficiency of the InGaAs sub-cell of the intermediate cell can be improved. Since the light absorption efficiency of the InGaAs sub-cell is improved, the corresponding photoelectric conversion efficiency is improved. Based on this, the thickness of the InGaAs sub-cell of the intermediate sub-cell can be reduced.

The inventors found that in the space environment, the electrical performance of the InGaAs middle cell decays faster than that of the GaInP top cell, that is, the radiation resistance of InGaAs is relatively weaker. When the thickness of the InGaAs sub-cell is reduced, it can be relatively Improve the anti-irradiation ability of InGaAs, and then improve the anti-irradiation performance of the entire multi-junction solar cell.

It should be noted that the multi-junction solar cell with improved radiation resistance provided by the embodiments of the present invention also includes other structures, such as a double-layer anti-reflection film located outside the transparent electrode, and the double-layer anti-reflection film can be evaporated It is formed by plating Al ₂ O ₃ and TiO ₂ , which will not be described in detail in the embodiment of the present invention. In addition, the main electrode is also included, and the main electrode is used to collect the current of the transparent conductive grid electrode and output it to the outside of the solar cell to provide power for other electrical components.

Please refer to FIG. 3 . FIG. 3 is a schematic diagram of a front-mounted three-junction solar cell structure provided by an embodiment of the present invention. The growth direction of each layer structure of the front-mounted three-junction solar cell structure is bottom-up. As shown in Figure 3, the structure of a front-mounted three-junction solar cell mainly includes:

The Ge substrate 11 is grown on the Ge substrate by metal organic chemical vapor phase epitaxy deposition (MOCVD), and the first sub-cell 12, the first tunnel junction 13, the DBR reflective layer 14, the second The sub-cell 15 , the second tunnel junction 16 , the third sub-cell 17 , the corrosion stop layer 18 , the photoconductive contact layer 19 , the ohmic contact layer 110 and the transparent electrode 111 , wherein the ohmic contact layer 110 is made of AuGeNi.

The three sub-cells are connected through a tunnel junction, wherein the first sub-cell is a Ge bottom cell, the second sub-cell is an InGaAs middle cell, and the third sub-cell is a GaInP or AlGaInP top cell.

Wherein, the first sub-cell 12 includes: performing phosphorus diffusion on a p-type Ge substrate to obtain an n-type emitter region and growing an (Al)GaInP layer that matches the substrate lattice on the p-type Ge substrate as a nucleation layer , and as the window layer of the first sub-cell. Here, the (Al)GaInP layer represents a GaInP layer or an AlGaInP layer.

The first tunnel junction 13 includes n-type GaAs or n-type GaInP as the N-type layer of the first tunnel junction and p-type (Al) GaAs material as the P-type layer of the first tunnel junction, wherein the N-type and P-type doped The impurities are doped with Si and C, respectively.

The DBR reflective layer 14 includes a laminated structure in which multiple layers of first layer materials and second layer materials are alternately formed. Wherein, the material of the first layer is Al _x InGaAs, and the material of the second layer is Al _y InGaAs, where 0≦x<y≦1. Two layers of materials are alternately grown for n periods, 3≦n≦30.

The second sub-cell 15 includes a back field layer, a p-type doped InGaAs layer base region, an n-type doped InGaAs layer emitter region, and a window layer sequentially from bottom to top. The back field layer is made of GaInP or AlGaAs material, and the window layer is made of AlGaInP or AlInP material.

The second tunnel junction 16 includes n-type InGaAs or n-type GaInP as the N-type layer of the second tunnel junction and p-type (Al) InGaAs material as the P-type layer of the second tunnel junction, wherein the N-type and P-type Doping uses Si and C doping respectively.

The third subcell 17 includes an AlGaInP back field layer, a p-type doped AlGaInP or GaInP layer base region, an n-type doped AlGaInP or GaInP layer emitter region, and an AlInP window layer from bottom to top.

The photoconductive contact layer 19 includes an (Al)GaInP layer as an N-type contact layer forming ohmic contact with the transparent electrode 111, with a thickness of 0.2 μm-1 μm, including endpoint values, and a doping concentration range of n-type impurities in the range of 1×10 ¹⁸ /cm ³ ~1 x 10 ¹⁹ /cm ³ inclusive of endpoints.

In this embodiment, the etch stop layer 18 is disposed between the AlInP window layer of the third subcell 17 and the photoconductive contact layer 19, and is made of n-type doped AlGaAs material with a thickness of 1nm-20nm and an Al composition greater than 0.35 and less than 1.

In addition, other parts of the solar cell structure not shown in the figure, such as the back metal electrode formed by evaporation on the surface of the Ge substrate away from the first sub-cell; The main electrode electrically connected to the conductive grid electrode, the transparent conductive material can be indium tin oxide (ITO), Al-doped zinc oxide (AZO), IZO (indium zinc oxide), IGZO (indium gallium zinc oxide) or graphene . In this embodiment, a metal main electrode may also be included to form a good ohmic contact with the main electrode of the transparent conductive electrode for connecting the solar cell with an external circuit. It also includes an anti-reflection film located outside the electrode area, and the anti-reflection film is a double-layer anti-reflection film of Al ₂ O ₃ /TiO ₂ formed by vapor deposition.

Since the photoconductive contact layer has a grid line structure, dry etching is used to remove the photoconductive contact layer during the manufacturing process. On the one hand, the complexity and cost of the process are increased, and on the other hand, the degree of controllability is relatively poor.

Therefore, in the embodiment of the present invention, the AlGaAs material is used as the corrosion stop layer, which is arranged between the AlInP window layer of the third sub-cell 17 and the photoconductive contact layer (Al)GaInP, and cooperates with the photoconductive contact layer of (Al)GaInP, so that the solar When the anti-reflection film is fabricated on the surface of the AlInP window layer in the battery chip process, the wet etching process is effectively stopped after the photoconductive contact layer is etched away, and then the etching stop layer is continuously removed by wet etching to expose the AlInP window layer. If there is no such layer, since the photoconductive contact layer of (Al)GaInP and the AlInP window layer of the third sub-cell 17 are P-oxide materials, when the photoconductive contact layer is removed by chemical solution wet etching, the corrosion process cannot be effectively controlled to stop At the interface of the photoconductive contact layer and the window layer.

The existing technology uses (In)GaAs layer as the ohmic contact layer, because its band gap is smaller than GaInP, so this layer absorbs light or partially absorbs light in the absorption spectrum range of GaInP battery and (In)GaAs battery, even if the transparent electrode is used as the sun The electrode grid line of the battery chip will still be absorbed by the (In)GaAs ohmic contact layer for the light that is irradiated on the electrode area of the grid line and whose spectral range is in the absorption range of GaInP battery and (In)GaAs battery. Radiation resistance and conversion efficiency.

The positive three-junction solar cell provided in the embodiment of the present invention uses GaInP or AlGaInP material as the photoconductive contact layer, and uses transparent electrodes as the electrode grid lines of the solar cell chip. Light irradiated to the grid line electrode area, wherein the light in the spectral range in the GaInP cell absorption range through the electrode will be partially absorbed by the GaInP photoconductive contact layer, and the light in the spectral range in the (In)GaAs cell absorption range will pass through the electrode. The GaInP photoconductive contact layer and the GaInP sub-cell, thereby increasing the light absorption of the (In)GaAs sub-cell, so that the thickness of the base region of the (In)GaAs sub-cell can be reduced accordingly, thereby improving the radiation resistance and conversion efficiency of the cell.

It should be noted that, in the above embodiment, a lattice-matched GaInP/InGaAs/Ge triple-junction solar cell is used as an example for illustration. Similarly, the optical contact layer provided by the present invention can also be applied to a lattice-mismatched GaInP solar cell. /InGaAs/Ge triple-junction solar cells, and lattice-mismatched GaInP/AlInGaAs/InGaAs/Ge quadruple-junction solar cells, which will not be described in detail in this embodiment.

Please refer to Fig. 4, Fig. 4 is a schematic diagram of a structure of a forward lattice-mismatched triple-junction solar cell provided by an embodiment of the present invention; Among them, the lattice-mismatched triple-junction solar cell further includes a metamorphic buffer layer 112 , wherein the metamorphic buffer layer 112 is located between the DBR reflective layer 14 and the first tunnel junction 13 .

Please refer to FIG. 5. FIG. 5 is a schematic diagram of a forward four-junction solar cell structure provided by an embodiment of the present invention; the forward four-junction solar cell structure is a GaInP/AlInGaAs/InGaAs/Ge forward four-junction solar cell, using The metal-organic chemical vapor phase epitaxy deposition method is grown on the Ge substrate, and the four sub-cells are sequentially included along the growth direction: the first sub-cell, the second sub-cell, the third sub-cell and the fourth sub-cell; wherein, the first The sub-cell is a Ge sub-cell; the second sub-cell is an InGaAs sub-cell with a band gap of 1.0eV; the third sub-cell is an AlInGaAs sub-cell with a band gap of 1.4eV; the fourth sub-cell is an AlGaInP sub-cell with a band gap of 1.9eV. battery or GaInP sub-cell; wherein, the second sub-cell and the third sub-cell are both lattice-mismatched sub-cells.

Specifically, as shown in FIG. 5 , it includes a first sub-cell 21, a first tunnel junction 22, a metamorphic buffer layer 23, a DBR reflective layer 24, a second sub-cell 25, and a second tunnel junction 26 from bottom to top. , the third sub-cell 27 , the third tunnel junction 28 , the fourth sub-cell 29 , the photoconductive contact layer 210 , the ohmic contact layer 211 and the transparent electrode 212 .

Regardless of the front-mounted lattice-mismatched three-junction solar cell or the front-mounted lattice-mismatched four-junction solar cell provided in the embodiments of the present invention, GaInP or AlGaInP materials can be used as the photoconductive contact layer, and transparent electrodes can be used as the solar cell chip. electrode grid. Light irradiated to the grid line electrode area, wherein the light in the spectral range in the GaInP cell absorption range through the electrode will be partially absorbed by the GaInP photoconductive contact layer, and the light in the spectral range in the (In)GaAs cell absorption range will pass through the electrode. The GaInP photoconductive contact layer and the GaInP sub-cell, thereby increasing the light absorption of the (In)GaAs sub-cell, so that the thickness of the base region of the (In)GaAs sub-cell can be reduced accordingly, thereby improving the radiation resistance and conversion efficiency of the cell.

Based on the same inventive concept, an embodiment of the present invention also provides a method for manufacturing a multi-junction solar cell with improved radiation resistance, which is used to form a multi-junction solar cell with improved radiation resistance as described in any of the above embodiments , the production method includes:

provide the substrate;

forming a bottom cell on one side of the substrate;

forming an InGaAs sub-cell on the side of the bottom cell facing away from the substrate;

forming a GaInP sub-cell on the side of the InGaAs sub-cell facing away from the substrate;

growing and forming a photoconductive contact layer on the side of the GaInP sub-cell away from the InGaAs sub-cell, and the material of the photoconductive contact layer is GaInP or AlGaInP;

forming a transparent electrode on the side of the photoconductive contact layer away from the GaInP sub-cell;

Wherein, the transparent electrode is a grid line structure, and the projection of the photoconductive contact layer and the transparent electrode on the top cell overlap.

In this embodiment, it is not limited whether the multi-junction solar cell is triple-junction or quadruple-junction. If it is a quadruple-junction solar cell, it may also include the structure of forming other intermediate sub-cells, which will not be described in detail in this embodiment.

In this embodiment, the photoconductive contact layer is located below the transparent electrode and overlaps with the projection of the transparent electrode on the top cell. Therefore, the present invention includes the process step of etching the photoconductive contact layer. It should be noted that wet A photoconductive contact layer with a gate line structure may be formed by a dry etching process, or a dry etching process may be used to form a photoconductive contact layer with a gate line structure, which is not limited in this embodiment. It should be noted that, in order to control the precision of wet etching when wet etching process is used to form the photoconductive contact layer with grid line structure, this embodiment also includes an etching stop layer, and the etching stop layer is located at the A photoconductive contact layer faces the surface of the bottom cell. In this way, during the manufacturing process, when wet etching the photoconductive contact layer to form the gate line structure, it can stop on the etching stop layer, so as to control the etching precision of wet etching.

In order to prevent the corrosion cut-off layer from absorbing the spectrum, after the thickness of the photoconductive contact layer with the grid line structure is completed, a selective etching process is used to remove the corrosion cut-off layer outside the grid line structure, so that only the grid line remains in the corrosion cut-off layer corresponding part of the structure.

It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. For the same and similar parts in each embodiment, refer to each other, that is, Can.

It should also be noted that in this article, relational terms such as first and second etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations Any such actual relationship or order exists between. Moreover, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that an article or device comprising a set of elements includes not only those elements but also other elements not expressly listed, Or also include elements inherent in such an article or device. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in an article or device comprising the aforementioned element.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (12)

1. A multi-junction solar cell improving radiation resistance, characterized in that, comprising: At least three-junction sub-cells, the three-junction sub-cells at least include InGaAs sub-cells, and GaInP sub-cells or AlGaInP sub-cells, the GaInP sub-cells or AlGaInP sub-cells are the top cells of the multi-junction solar cell, and the InGaAs sub-cells a cell being an intermediate cell positioned between a bottom cell and the top cell of said multijunction solar cell; a photoconductive contact layer on the side of the top cell facing away from the bottom cell; A transparent electrode located on the side of the photoconductive contact layer away from the top cell, the transparent electrode has a grid line structure, and the projections of the photoconductive contact layer and the transparent electrode on the top cell overlap; Wherein, the material of the light guiding contact layer is GaInP or AlGaInP. 2. The multi-junction solar cell improving radiation resistance according to claim 1, further comprising: an ohmic contact layer, the ohmic contact layer is located on the surface of the photoconductive contact layer facing the transparent electrode; Wherein, the material of the ohmic contact layer is AuGeNi. 3 . The multi-junction solar cell with improved radiation resistance according to claim 2 , wherein the thickness of the ohmic contact layer ranges from 2 nm to 10 nm, inclusive. 4 . 4. The multi-junction solar cell with improved radiation resistance according to claim 1, characterized in that, the thickness range of the photoconductive contact layer is 0.2 μm-1 μm, including the endpoint values; the photoconductive contact layer is n-type In the contact layer, the doping concentration of the n-type impurity ranges from 1×10 ¹⁸ /cm ³ to 1×10 ¹⁹ /cm ³ , including the endpoint values. 5 . The multi-junction solar cell with improved radiation resistance according to claim 1 , wherein the transparent electrode is an ITO electrode, an IZO electrode, an IGZO electrode, an AZO electrode or a graphene electrode. 6. The multi-junction solar cell with improved radiation resistance according to claim 1, further comprising: a corrosion stop layer; The etch stop layer is located on the surface of the photoconductive contact layer facing the bottom cell. 7. The multi-junction solar cell with improved radiation resistance according to claim 6, wherein the corrosion stop layer is made of n-type AlGaAs material. 8. The multi-junction solar cell with improved radiation resistance according to claim 7, wherein the corrosion stop layer has a thickness ranging from 1nm to 20nm, inclusive; wherein the Al component is greater than 0.35, and less than 1. 9. The multi-junction solar cell for improving radiation resistance according to any one of claims 1-8, wherein the multi-junction solar cell is a triple-junction solar cell, and the triple-junction solar cell comprises: A Ge bottom cell, an InGaAs middle cell, and a top cell are sequentially arranged along the growth direction, and the top cell is a GaInP top cell or an AlGaInP top cell. 10. The multi-junction solar cell for improving radiation resistance according to any one of claims 1-8, wherein the multi-junction solar cell is a four-junction solar cell, and the four-junction solar cell comprises: A first Ge subcell, a second InGaAs subcell, a third AlInGaAs subcell, and a fourth GaInP subcell or a fourth AlGaInP subcell are sequentially arranged along the growth direction. 11. A method for making a multi-junction solar cell with improved radiation resistance, characterized in that it is used to make the multi-junction solar cell with improved radiation resistance according to any one of claims 1-10, said making Methods include: provide the substrate; forming a bottom cell on one side of the substrate; forming an InGaAs sub-cell on the side of the bottom cell facing away from the substrate; forming a GaInP sub-cell on the side of the InGaAs sub-cell facing away from the substrate; growing and forming a photoconductive contact layer on the side of the GaInP sub-cell away from the InGaAs sub-cell, and the material of the photoconductive contact layer is GaInP or AlGaInP; forming a transparent electrode on the side of the photoconductive contact layer away from the GaInP sub-cell; Wherein, the transparent electrode is a grid line structure, and the projection of the photoconductive contact layer and the transparent electrode on the top cell overlap. 12. The method for manufacturing a multi-junction solar cell with improved radiation resistance according to claim 11, characterized in that, before the growth of the GaInP sub-cell away from the side of the InGaAs sub-cell to form a photoconductive contact layer, include: forming a corrosion stop layer on the surface of the GaInP sub-cell away from the InGaAs sub-cell; forming an entire layer of photoconductive contact layer on the surface of the corrosion stop layer away from the GaInP sub-cell; A wet etching process is used to remove part of the photoconductive contact layer and the etching stop layer, so as to form a photoconductive contact layer with a gate line structure.