阅读说明：本技术 一种叠层太阳能电池及其制备方法 (Laminated solar cell and preparation method thereof ) 是由 王建波 张琦忠 尹力 朱琛 吕俊 于 2019-02-19 设计创作，主要内容包括：本公开提供一种叠层太阳能电池及其制备方法,涉及太阳能电池技术领域,能够解决叠层电池因重掺杂所导致的问题。本公开提供的叠层太阳能电池包括：底电池、顶电池、以及设置在底电池和顶电池之间的连接层,连接层按照从下到上的顺序包括隧穿氧化层、N型掺磷多晶硅薄膜和金属氧化层。(The invention provides a laminated solar cell and a preparation method thereof, relates to the technical field of solar cells, and can solve the problem of the laminated cell caused by heavy doping. The present disclosure provides a tandem solar cell comprising: the device comprises a bottom battery, a top battery and a connecting layer arranged between the bottom battery and the top battery, wherein the connecting layer comprises a tunneling oxide layer, an N-type phosphorus-doped polycrystalline silicon film and a metal oxide layer from bottom to top.)

1. A tandem solar cell, comprising: the device comprises a bottom battery, a top battery and a connecting layer arranged between the bottom battery and the top battery, wherein the connecting layer comprises a tunneling oxide layer, an N-type phosphorus-doped polycrystalline silicon film and a metal oxide layer from bottom to top.

2. The tandem solar cell of claim 1, wherein the tunneling oxide layer is made of SiO (silicon dioxide)₂The thickness is 1nm to 6 nm.

3. The tandem solar cell of claim 1, wherein said N-type phosphorus-doped polysilicon thin film has a doping concentration of 5 × 10²⁰cm^-3～9×10²⁰cm^-3The thickness of the film is 30 nm-150 nm.

4. The tandem solar cell according to claim 1, wherein the metal oxide layer is made of nickel oxide NiO and has a thickness of 1nm to 10 nm.

5. The tandem solar cell of claim 1, wherein said bottom cell comprises a P-type crystalline silicon cell, a PERC cell, an IBC cell.

6. The tandem solar cell of claim 1, wherein said top cell comprises a perovskite cell, a copper zinc tin sulfur cell, a group iii-v cell.

7. A method of fabricating a tandem solar cell, comprising:

preparing a bottom battery;

sequentially preparing a tunneling oxide layer and an N-type phosphorus-doped polycrystalline silicon film on the front side of the bottom cell by using a PECVD method;

preparing a metal oxide layer on the N-type phosphorus-doped polycrystalline silicon film by adopting an evaporation method;

and preparing a top battery on the metal oxide layer.

8. The method of claim 7, wherein the preparing a bottom cell comprises: cleaning, texturing, diffusing, polishing the back surface, depositing a laminated passivation film on the back surface, removing phosphorosilicate glass on the front surface, laser perforating on the back surface, screen printing and sintering the silicon wafer to obtain the bottom cell; in diffusion, the diffusion sheet resistance is 150-200 omega/sq, and the thickness of the phosphorosilicate glass is 20-40 nm.

9. The method as claimed in claim 7, wherein the preparing the metal oxide layer on the N-type phosphorus-doped polysilicon thin film by using an evaporation method comprises:

and (3) evaporating the metal oxide layer on the N-type phosphorus-doped polycrystalline silicon film by using thermal evaporation equipment, wherein the temperature of an evaporation cavity of the thermal evaporation equipment is 300-400 ℃, and the evaporation time is 1-3 min.

10. The method according to claim 7, wherein before the step of forming the metal oxide layer on the N-type phosphorus-doped polysilicon thin film by using an evaporation method, the method further comprises: and annealing in an annealing furnace at 850 ℃ for 15-20 min.

Technical Field

The disclosure relates to the technical field of solar cells, and particularly relates to a tandem solar cell and a preparation method thereof.

Background

The photovoltaic power generation technology is considered to be an effective way to solve the problems of energy crisis, environmental pollution, global warming and the like, and crystalline silicon solar cells dominate the photovoltaic market. At present, the Power Conversion Efficiency (PCE) of the crystalline silicon solar cell is as high as 26.6%, which is close to the theoretical Efficiency limit of the crystalline silicon solar cell of 29.4%. An effective way to overcome the S-Q Limit of such single junction solar cells is to integrate crystalline silicon and other types of solar cells to form a double junction Tandem (Tandem) solar Cell, e.g., a perovskite/PERC (passive Emitter and back side Cell) Tandem Cell.

Fig. 1 shows a structural schematic diagram of a perovskite/PERC stacked cell, wherein 11-top perovskite cell, 12-P + + heavily doped composite layer, 13-bottom crystalline silicon cell N + + heavily doped layer, and 14-bottom PERC cell. As shown in fig. 2, which is a schematic energy band diagram of an intermediate connection Layer of a perovskite/PERC stacked cell, in order to ensure that electrons and holes are recombined at the position of the connection Layer, the top of a valence band of a bonding Layer close to the perovskite and the bottom of a conduction band of the bonding Layer close to the PERC stacked cell must be as close as possible, and the two direct energy band bends must be as large as possible to cause the shortest tunneling path, so that the PERC emitter must be heavily doped to form an N + + Layer, meanwhile, a thin Layer of polysilicon heavily doped with boron is deposited between the HTL (Hole-Transport Layer) and the heavily doped emitter of the perovskite stacked cell to serve as a P + + Layer, and the P + + Layer and the N + + Layer form a tunneling effect of electrons and holes to serve as a composite connection Layer of the perovskite and the PERC stacked cell. Although this structure enables connection between the perovskite cell and the PERC cell, there are the following problems: (1) after the emitter of the PERC battery is heavily doped, the minority carrier lifetime of crystalline silicon can be seriously reduced, so that the surface recombination rate is increased, and the performance of the PERC battery at the bottom is reduced; (2) due to the characteristics of boron, the preparation difficulty of the nanometer polycrystalline silicon thin layer heavily doped with boron is higher, and the yield is lower.

Disclosure of Invention

The embodiment of the disclosure provides a laminated solar cell and a preparation method thereof, which can solve the problem of the laminated solar cell caused by heavy doping. The technical scheme is as follows:

according to a first aspect of embodiments of the present disclosure, there is provided a tandem solar cell comprising: the device comprises a bottom battery, a top battery and a connecting layer arranged between the bottom battery and the top battery, wherein the connecting layer comprises a tunneling oxide layer, an N-type phosphorus-doped polycrystalline silicon film and a metal oxide layer from bottom to top.

According to the laminated solar cell, the bottom cell does not need to be heavily doped, the negative effects that the surface recombination rate of the bottom cell is increased and the body service life is reduced due to heavy doping are avoided, and the tunneling oxide layer and the N-type phosphorus-doped polycrystalline silicon film are superposed, so that the conduction of current carriers can be guaranteed, and the laminated solar cell has an excellent passivation effect on the bottom cell; meanwhile, the parasitic absorption problem of light is effectively controlled by reducing the thickness of the N-type phosphorus-doped polycrystalline silicon film and the metal oxide layer, so that the matching of the current density of the bottom battery and the top battery is ensured; in addition, the metal oxide layer can be prepared by adopting ALD equipment, the cost is low, the film forming uniformity is good, the preparation method is simple compared with a heavily doped P-type polycrystalline silicon film, and the yield is high. In conclusion, the connecting layer effectively reduces the surface recombination rate of the bottom battery and improves the performance of the bottom battery while ensuring low manufacturing cost, and further improves the overall performance of the laminated battery.

In a first possible implementation manner of the first aspect, the tunneling oxide layer is made of SiO (silicon dioxide)₂The thickness is 1nm to 6 nm.

In a second possible implementation manner of the first aspect, the doping concentration of the N-type phosphorus-doped polysilicon film is 5 × 10²⁰cm^-3～9×10²⁰cm^-3The thickness of the film is 30 nm-150 nm.

In a third possible implementation manner of the first aspect, the material of the metal oxide layer is nickel oxide NiO, and the thickness is 1nm to 10 nm.

In a fourth possible implementation manner of the first aspect, the bottom cell includes a P-type crystalline silicon cell, a PERC cell, and an IBC cell.

In a fifth possible implementation form of the first aspect, the top cell comprises a perovskite cell, a copper zinc tin sulfur cell, a battery of the thirty-five family.

According to a second aspect of the embodiments of the present disclosure, there is provided a method for manufacturing a tandem solar cell, including:

preparing a bottom battery;

sequentially preparing a tunneling oxide layer and an N-type phosphorus-doped polycrystalline silicon film on the front side of the bottom cell by using a PECVD method;

preparing a metal oxide layer on the N-type phosphorus-doped polycrystalline silicon film by adopting an evaporation method;

a top cell is fabricated on the metal oxide layer.

In a first possible implementation manner of the second aspect, preparing the bottom cell includes: cleaning, texturing, diffusing, polishing the back surface, depositing a laminated passivation film on the back surface, removing phosphorosilicate glass on the front surface, laser perforating on the back surface, screen printing and sintering the silicon wafer to obtain a bottom cell; in diffusion, the diffusion sheet resistance is 150-200 omega/sq, and the thickness of the phosphorosilicate glass is 20-40 nm.

In a second possible implementation manner of the second aspect, the preparing the metal oxide layer on the N-type phosphorus-doped polycrystalline silicon thin film by using an evaporation method includes:

and (3) evaporating the metal oxide layer on the N-type phosphorus-doped polycrystalline silicon film by using thermal evaporation equipment, wherein the temperature of an evaporation cavity of the thermal evaporation equipment is 300-400 ℃, and the evaporation time is 1-3 min.

In a third possible implementation manner of the second aspect, before the metal oxide layer is prepared on the N-type phosphorus-doped polycrystalline silicon thin film by using an evaporation method, the method further includes: and annealing in an annealing furnace at 850 ℃ for 15-20 min.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure.

Fig. 1 is a schematic structural diagram of a conventional perovskite/PERC tandem solar cell provided by an embodiment of the present disclosure;

fig. 2 is a schematic energy band diagram of an intermediate connection layer of a conventional perovskite/PERC tandem solar cell provided by an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of a tandem solar cell provided in an embodiment of the present disclosure;

fig. 4 is a schematic energy band diagram of an intermediate connection layer of a tandem solar cell provided in an embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

The disclosed embodiment provides a tandem solar cell, as shown in fig. 3, the tandem solar cell includes: the bottom cell 35, the top cell 31, and the tunneling oxide layer 34, the N-type phosphorus-doped polycrystalline silicon thin film 33, and the metal oxide layer 32 sequentially stacked from bottom to top between the bottom cell and the top cell.

According to the tandem solar cell shown in fig. 3, an embodiment of the present disclosure provides a method for manufacturing a tandem solar cell, which specifically includes the following steps:

preparing a bottom battery;

sequentially preparing a tunneling oxide layer and an N-type phosphorus-doped polycrystalline silicon film on the front side of the bottom cell by using a PECVD method;

preparing a metal oxide layer on the N-type phosphorus-doped polycrystalline silicon film by adopting an evaporation method;

a top cell is fabricated on the metal oxide layer.

Specifically, preparing the bottom cell includes: and cleaning, texturing, diffusing, polishing the back surface, depositing a laminated passivation film on the back surface, removing phosphorosilicate glass on the front surface, laser perforating on the back surface, screen printing and sintering the silicon wafer to obtain the bottom cell. In diffusion, the diffusion sheet resistance is 150-200 omega/sq, and the thickness of the phosphorosilicate glass is 20-40 nm; back side deposition of the laminated passivation film includes depositing aluminum oxide and silicon nitride in sequence on the back side.

In the embodiment of the present disclosure, before the metal oxide layer is prepared on the N-type phosphorus-doped polysilicon thin film by using the evaporation method, the method further includes: and annealing in an annealing furnace at 850 ℃ for 15-20 min. And then, evaporating a metal oxide layer on the N-type phosphorus-doped polycrystalline silicon film by using thermal evaporation equipment, wherein the temperature of an evaporation cavity of the thermal evaporation equipment is 300-400 ℃, and the evaporation time is 1-3 min.

According to the tandem solar cell and the preparation method thereof described above, in the embodiment of the present disclosure, the bottom cell includes a P-type or N-type crystalline silicon cell, and the P-type crystalline silicon cell includes a P-type conventional cell and a P-type polysilicon PERC cell; the N-type crystalline silicon cell includes an IBC (indirect back contact) cell. The top battery comprises a perovskite battery, a copper zinc tin sulfur battery and a III-V battery.

In the embodiment of the present disclosure, the material of the metal oxide layer is nickel oxide nio (nickel oxide), and the thickness is 1nm to 10 nm. Due to the energy band characteristics of NiO and the good transmission capability of the holes, NiO is added between a Hole-Transport Layer (HTL) of the top cell and the N-type phosphorus-doped polycrystalline silicon film, so that the NiO is a very good trap for the holes, the holes in the Hole-Transport Layer of the top cell are captured in the trap, then a tunneling effect is formed to be combined with electrons in the N-type phosphorus-doped polycrystalline silicon film, and the N-type phosphorus-doped polycrystalline silicon film and NiO form an electron-Hole tunneling composite Layer. In the embodiment of the disclosure, ALD (Atomic Layer Deposition) can be used to prepare a Layer of metal oxide NiO on the N-type phosphorus-doped polysilicon thin film. Meanwhile, a tunneling oxide layer is arranged between the N-type phosphorus-doped polycrystalline silicon film and the emitting electrode of the bottom cell, and in the embodiment of the disclosure, the tunneling oxide layer is made of SiO₂(Silicon dioxide ) with a thickness of 1 nm-6 nm, a tunneling oxide layer SiO₂Not only can ensure the conduction of current carriers, but also can increase the passivation effect.

It should be noted that although the N-type phosphorus-doped polysilicon thin film has good electron transport property, it also has a larger parasitic absorption problem, and in order to solve the parasitic absorption problem, the control of the polysilicon thin film can be usedThe thickness and doping concentration of the N-type P-doped polysilicon film are 5 × 10²⁰cm^-3～9×10²⁰cm^-3The thickness of the film is 30 nm-150 nm, the parasitic absorption problem of light is effectively controlled by increasing the doping concentration of the N-type phosphorus-doped polycrystalline silicon film and reducing the film thickness of the N-type phosphorus-doped polycrystalline silicon film, so that the matching of the current density of the bottom battery and the top battery is ensured.

The embodiment of the disclosure provides a tandem solar cell, which comprises a bottom cell, a top cell and a connecting layer arranged between the bottom cell and the top cell, wherein the connecting layer comprises a tunneling oxide layer, an N-type phosphorus-doped polycrystalline silicon film and a metal oxide layer from bottom to top. Compared with the prior art, the bottom crystalline silicon battery does not need to be heavily doped, so that the negative effects of the increase of the surface recombination rate of the bottom battery and the reduction of the body service life caused by the heavy doping are avoided, and the tunneling oxide layer and the N-type phosphorus-doped polycrystalline silicon film can ensure the conduction of current carriers and have excellent passivation effect on the bottom battery; meanwhile, the parasitic absorption problem of light is effectively controlled by reducing the thickness of the N-type phosphorus-doped polycrystalline silicon film and the metal oxide layer, so that the matching of the current density of the bottom battery and the top battery is ensured; in addition, the heavily doped P-type polycrystalline silicon film is replaced by the metal oxide layer, the metal oxide layer can be prepared by ALD equipment, the cost is low, the film forming uniformity is good, the preparation method is simple compared with that of the heavily doped P-type polycrystalline silicon film, and the yield is high. To sum up, the connecting layer effectively reduces the surface recombination rate of the bottom battery and improves the performance of the bottom battery while ensuring low manufacturing cost, thereby improving the overall performance of the laminated battery.

According to the tandem solar cell shown in fig. 1 and the method for manufacturing the tandem solar cell shown in fig. 2, the perovskite/PERC tandem cell and the method for manufacturing the same will be specifically described below by taking the bottom cell as the PERC cell and the top cell as the perovskite cell as an example.

Specifically, a tunneling oxide Layer SiO2 and a high-concentration phosphorus-doped N-type phosphorus-doped Polycrystalline Silicon (Poly-Si) film are grown on an emitter of a lightly-doped PERC cell, a metal oxide Layer NiO is prepared on the N-type phosphorus-doped Polycrystalline Silicon film by using ALD (Atomic Layer Deposition), and then the perovskite cell is prepared on the metal oxide Layer NiO. The tunneling oxide layer, the heavily phosphorus-doped polycrystalline silicon nano thin layer and the metal oxide layer NiO are used as a composite connecting layer of the P-i-N structure perovskite battery and the PERC battery. Referring to fig. 4, a schematic energy band diagram of the intermediate connection layer of a perovskite/PERC stacked cell is shown, in the disclosed embodiment, the light doping is denoted by "+" and the heavy doping is denoted by "+ +".

The preparation method of the perovskite/PERC laminated cell comprises the following steps:

(1) after a conventional texturing and cleaning process is carried out on the PERC battery at the bottom, a light expansion process is carried out in a phosphorus expansion process, the sheet resistance is controlled to be 150-200 omega/sq, a large amount of oxygen is introduced in a propulsion step after the diffusion is finished, the propulsion time is prolonged, and the thickness of the phosphorosilicate glass on the surface is controlled to be 20-40 nm;

(2) the phosphorosilicate glass on the surface is used as a protective layer and is reserved in the back polishing process;

(3) performing conventional back alumina deposition and back silicon nitride deposition;

(4) removing the phosphorosilicate glass on the front side by adopting single-side chain type wet equipment;

(5) entering PECVD equipment to grow a front ultrathin tunneling layer and grow phosphorus-doped amorphous silicon;

(6) annealing at 850 deg.C in an annealing furnace for 15-20 min;

(7) carrying out laser hole opening on a back aluminum back field contact area, then carrying out printing of a back aluminum back field and printing of a back electrode, and then sintering;

(8) entering a thermal evaporation device for evaporation of the metal tunneling oxide layer, wherein the temperature of an evaporation cavity is controlled at 300-400 ℃, and the evaporation time is controlled at 1-3 min;

(9) and then preparing the rest film layer of the top perovskite battery.

The remaining film layer preparation for the top perovskite cell included: after the preparation of the metal oxide layer NiO film is finished, preparing a modification layer PTAA and a perovskite film in sequence, and after the perovskite film is annealed at a low temperature, thermally evaporating a LiF (lithium fluoride) film with the thickness of 1-5 nm, a TiO2 (Titanium Dioxide) film with the thickness of 10-15 nm and a PCBM film with the thickness of 10-15 nm in sequence; depositing a layer of SnO2 (stannic oxide) film with the thickness of 4-10 nm on the top of the PCBM film by ALD; depositing 110-150 nm thick IZO (indium zinc oxide) transparent conductive glass by direct current sputtering; and finally, evaporating or sputtering an Ag electrode with the thickness of 120-150 nm on the surface of the device, and then evaporating LiF with the thickness of 100-120 nm to serve as an antireflection layer, so that the laminated solar cell with the whole perovskite/PERC cell structure is prepared.

Compared with the prior art, the perovskite/PERC laminated solar cell provided by the implementation of the present disclosure has the following advantages:

1) the method has the advantages that the crystalline silicon body region does not need to be heavily doped, the negative effects that the recombination rate of the surface of the PERC battery is increased and the service life of the PERC battery is reduced due to the heavy doping are avoided, the tunneling oxide layer is overlapped with the N-type phosphorus-doped polycrystalline silicon film, the conduction of current carriers can be guaranteed, and the bottom PERC battery has an excellent passivation effect.

2) NiO is adopted to replace a heavily doped P + + layer, the NiO can be prepared by ALD equipment, the cost is low, the film forming uniformity is good, the preparation method of the polysilicon film with boron doped in specific gravity is simple, and the yield is high.

3) The parasitic absorption problem of light is effectively controlled by reducing the thicknesses of the polycrystalline silicon nano layer and the NiO nano layer, so that the matching property of the current density of the PERC battery and the top perovskite battery is ensured.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.