CN211828772U

CN211828772U - Laminated solar cell

Info

Publication number: CN211828772U
Application number: CN202020725795.3U
Authority: CN
Inventors: 丁蕾; 张鹏; 张忠文; 王永谦
Original assignee: Tongwei Solar Meishan Co Ltd
Current assignee: Tongwei Solar Meishan Co Ltd
Priority date: 2020-05-06
Filing date: 2020-05-06
Publication date: 2020-10-30
Anticipated expiration: 2030-05-06

Abstract

A laminated solar cell belongs to the photovoltaic field. A laminated solar cell comprises a perovskite cell and a silicon-based cell which are compounded into a whole through a tunneling junction. Wherein the perovskite cell has a front electrode and the silicon-based cell has a front electrode and a back electrode. The battery has double surfaces which can generate electricity through incident light, so that the electricity can be generated through overturning when the perovskite is invalid and the silicon-based battery is used for generating electricity.

Description

Laminated solar cell

Technical Field

The application relates to the photovoltaic field, particularly, relates to a tandem solar cell.

Background

Due to the outstanding advantages of high photoelectric conversion efficiency, low cost, simple manufacturing and the like, the perovskite solar cell light becomes one of the most promising solar cells and becomes a research hotspot.

Currently, the efficiency of perovskite solar cells has reached 25.2%. The band gap of the material applied to the perovskite solar cell is generally larger than 1.5eV, and the band gap of the perovskite absorption layer can be further increased to be more than 1.65eV through doping.

The perovskite absorption layer with wide band gap is very favorable for forming a double-junction cell with the crystalline silicon solar cell. At present, the photoelectric conversion efficiency of a double-junction solar cell composed of perovskite and crystalline silicon reaches 28%.

However, the service life of the perovskite battery has a great problem all the time, and the development of the laminated battery is severely restricted by the instability of the perovskite structure, so that the current market has no component of the laminated battery. Therefore, how to exert the advantages of perovskite batteries without affecting the service life of silicon-based batteries is one of the key points of future development.

SUMMERY OF THE UTILITY MODEL

In view of the above-mentioned shortcomings, the present application provides a tandem solar cell to partially or fully improve, and even solve, the problem of short service life of the perovskite cell and the silicon-based solar cell in the related art.

The application is realized as follows:

in a first aspect, examples of the present application provide a tandem solar cell.

The laminated solar cell comprises a perovskite sub cell, a tunneling junction and a silicon heterojunction cell, wherein the perovskite sub cell is combined with the silicon heterojunction cell through the tunneling junction.

Wherein the perovskite sub-cell serves as the top cell of the tandem solar cell. The front surface of the perovskite sub-battery is provided with a top electrode through a first transparent conducting layer.

The silicon heterojunction cell serves as the bottom cell of the tandem solar cell. The front surface of the silicon heterojunction cell is provided with a first combination area and a second combination area positioned at the periphery of the first combination area. And the first combination area is provided with a secondary electrode through a second transparent conductive layer, and the back surface of the silicon heterojunction cell is provided with a bottom electrode through a third transparent conductive layer.

The tunneling junction has opposing top and bottom surfaces. The tunneling junction is configured to bond with the top surface to the perovskite sub-cell and with the bottom surface to the second bonding region of the silicon heterojunction cell to complex the perovskite sub-cell with the silicon heterojunction cell.

In the implementation process, the tandem solar cell provided by the embodiment of the application is a double-sided tandem cell, and includes a perovskite solar cell and a silicon-based solar cell respectively. Both sides of the laminated solar cell can be irradiated with light to generate electricity. Therefore, light enters from the front side (the perovskite solar cell side) in the service life range of the perovskite cell, and both the two sub-cells can realize light entering and power generation; and after the service life of the perovskite battery is reached, the battery piece is turned over, and light enters from the back side (the side of the silicon-based solar battery).

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the prior art of the present application, the drawings used in the description of the embodiments or the prior art will be briefly described below.

FIG. 1 is a schematic diagram of a known solar cell;

fig. 2 is a schematic structural diagram of a tandem solar cell provided in an embodiment of the present application;

fig. 3 shows a schematic front view of the tandem solar cell of fig. 2;

fig. 4 shows a schematic rear view of the tandem solar cell of fig. 2.

Icon: 101-back electrode; 102-a back transparent conductive layer; 103-amorphous silicon p-layer; 104-intrinsic amorphous silicon layer; 105-crystalline silicon; 106-intrinsic amorphous silicon layer; 107-amorphous silicon n layer; 108-nano-silicon n layer; 109-nano-silicon p layer; 1010-hole transport layer; 1011-an absorbing layer; 1012-electron transport layer; 1013-front transparent conductive layer; 1014-front electrode; 201-bottom electrode; 202-backside transparent conductive layer; 203-amorphous silicon n layer; 204-amorphous silicon i layer; 205-a crystalline silicon wafer; 206-amorphous silicon i layer; 207-amorphous silicon p-layer; 208-front transparent conductive layer; 209-secondary electrode; 210-a bonding layer; 211-electron transport layer; 212-an absorbent layer; 213-hole transport layer; 214-front transparent conductive layer; 215-top electrode.

Detailed Description

Embodiments of the present application will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present application and should not be construed as limiting the scope of the present application. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Perovskite cells have unique properties and thus are a hot spot in current research. Silicon-based solar cells also have their unique advantages as a technologically mature solar cell technology. Therefore, how to combine the advantages of perovskite solar cells and silicon-based solar cells to better match them becomes a difficulty in the art.

One of the key problems is: the stability of perovskites is worse compared to silicon-based materials, and therefore, the lifetime of perovskites is generally lower than that of silicon-based materials. When the two are combined, the entire cell is often scrapped because of failure of the perovskite cell. Therefore, in the scheme of combining the perovskite battery and the silicon-based battery, how to prolong the service life of the battery is particularly important.

In order to study the performance and characteristics of a perovskite cell and a silicon-based solar cell, the inventors have implemented a perovskite-silicon composite tandem solar cell, whose structure is shown in fig. 1.

The back electrode 101 is a back conductive gate line (gate line electrode), typically a silver gate. It can be made by screen printing. The back transparent conductive layer 102 is typically Indium Tin Oxide (ITO). It can be made by magnetron sputtering deposition, and the thickness is about 80 nm.

The thickness of the amorphous silicon p-layer 103 is typically 10 nm. It can be fabricated by Plasma-Enhanced Chemical Vapor Deposition (PECVD). The intrinsic amorphous silicon layer 104 (amorphous silicon i-layer) is typically 5nm thick. Which may be fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD). The crystalline silicon 105 may be an n-type silicon wafer or a p-type silicon wafer. Typically 150 to 250 microns thick. The amorphous silicon i layer (intrinsic amorphous silicon layer 106) is typically 5nm thick. Which may be fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD). The amorphous silicon n-layer 107 is typically 10nm thick. Which may be fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD).

The amorphous silicon p-layer 103 to the amorphous silicon n-layer 107 film layers together form the semiconductor layers of the SHJ cell, wherein the cathode is in contact with the tunnel junction and the anode is in contact with the back transparent conductive layer 102.

The nano-silicon n-layer 108 is typically 20nm thick and is fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD). Nano-silicon refers to crystalline silicon particles less than 5 nanometers in diameter. The nano-silicon p-layer 109 is typically 20nm thick. Which is fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD). The nano-silicon n layer 108 and the nano-silicon p layer 109 form a tunnel junction together, that is, the tunnel junction is a composite layer, and the electron and the hole are combined.

The hole transport layer 1010 material of the perovskite solar cell is generally organic small molecule material such as PTAA, spiro-TTB, spiro-OMeTAD and the like. The absorption layer 1011 (i.e. perovskite material layer) of the perovskite solar cell is made of FA_1-xCs_xPbI3, generally 0.1 therein<x<0.3. The electron transport layer 1012 of the perovskite solar cell is made of SnO₂、TiO₂And ZnO. Typically it is fabricated by Atomic Layer Deposition (ALD), typically 50nm thick.

The hole transport layer 1010 through the electron transport layer 1012 together make up the semiconductor layers of the perovskite cell, with the positive electrode in contact with the tunnel junction and the negative electrode in contact with the front transparent conductive layer 1013.

The front transparent conductive layer 1013 is typically Indium Tin Oxide (ITO). It can be made by magnetron sputtering, with a thickness of 80 nm. The front conductive grid line is a front electrode 1014, typically a silver grid, which is made by screen printing.

When the solar cell is operated, light enters the perovskite-silicon heterojunction solar cell through the front silver grid (front electrode 1014) and the front transparent conductive layer 1013. The perovskite material and the silicon material have characteristic absorption for light of different wavelengths due to their difference in band gap. Therefore, both have a larger response width to the spectrum.

In the solar cell, after light enters the solar cell, a short-wavelength (less than 800nm) portion is absorbed by the perovskite absorption layer 1011, and electron-hole pairs are generated. The photo-generated electrons migrate toward the electron transport layer 1012 and the holes migrate toward the hole transport layer 1010.

Among them, light having a long wavelength of 800nm to 1200nm is absorbed by an absorption layer (crystalline Silicon 105) of a Silicon Hetero-Junction (SHJ) solar cell, generating electron-hole pairs. Electrons migrate to the amorphous silicon n-layer 107 and holes migrate to the amorphous silicon p-layer 103.

Holes migrating from the perovskite layer cell and electrons migrating from the SHJ cell recombine at a tunneling junction (electron-hole recombination layer, which may optionally include a nano-silicon n-layer and a nano-silicon p-layer).

Meanwhile, electrons of the tandem solar cell are collected through the front transparent conductive layer 1013 and the front electrode 1014, which is a silver grid of the front, and form a negative electrode of the tandem solar cell. Holes of the tandem solar cell are collected through the back transparent conductive layer 102 and the back electrode 101, which is a back silver grid, to form the positive electrode of the tandem solar cell.

Thus, the tandem solar cell performs a process of forming separated carriers by a photovoltaic effect. The power can be supplied to the outside through an external circuit or a load.

The electrical characteristics of the tandem solar cell can be partially reflected by a current-voltage curve (J-V curve). Three characteristic parameters of short-circuit current, maximum power output point and open-circuit voltage can be focused on from the curve, or other electrical characteristic parameters such as photoelectric conversion efficiency can be inspected through other testing means.

Open circuit voltage (V) of tandem solar cell_oc) Equal to the sum of the open circuit voltage of the perovskite solar cell and the open circuit voltage of the SHJ cell; short-circuit current density (J) of a laminate battery_sc) Equal to the smaller of the short circuit current density of the perovskite solar cell and the short circuit current density of the SHJ cell.

The laminated cell can improve the performance of the cell, such as light energy utilization rate and photoelectric conversion efficiency. Then, as described above, since the characteristics of the materials of the perovskite absorption layer in the perovskite cell and the hole transport layer thereof determine that the absorption layer and the hole transport layer are highly sensitive to impurities such as water and the like and are easily decomposed, the structural stability is poor. When the absorption layer and the hole transport layer of the perovskite battery are damaged, the whole laminated battery cannot continue to work. In other words, perovskite cells, which typically have lifetimes of less than 10 years, are difficult to match with silicon-based solar cells, which have lifetimes of 20 to 30 years.

In order to alleviate or solve the above problems, a major research direction is to improve materials of the perovskite absorption layer and the hole transport layer. However, it is disappointing that most of the perovskite materials known so far suffer from decomposition to a varying extent. Such a situation is particularly prominent and evident when the perovskite is exposed to high humidity, high temperature, high light, and oxygen enrichment. Among them, the decomposition of perovskite is more remarkable particularly at high humidity. Therefore, it puts a considerable demand on the encapsulation of solar cell devices, thereby posing a great obstacle to their application as commercial products.

In view of such current situation, the inventors tried to start from the structure of the battery, and considered that the improvement in the structure thereof may bring visible advantages and relatively low implementation difficulty, relative to the improvement in materials of batteries based on perovskite and silicon-based materials.

From the above-described cell structure implemented by the inventors, the main manifestation of the drawbacks is that the entire laminate cell cannot be put into service after failure of the perovskite cell. One reason for this problem is that: failure of the perovskite cell prevents the photo-generated electrons of the cell from being generated and transported normally, and thus prevents the front electrode of the cell from collecting electrons normally. Therefore, the battery cannot supply power to the outside through the external load.

Since the silicon-based solar cells have a longer lifetime, the inventors have developed improvements to silicon-based cells in tandem cells in order to make them work-based after failure of the perovskite cells. One of the main approaches is by adding additional electrodes to the silicon-based cell. Therefore, when the perovskite battery fails, the silicon-based battery can still be used as an independent battery to supply power to the outside.

In an example, such an innovative cell may be represented in some examples as a reversible double-sided power generating perovskite/SHJ stack solar cell. In a broader aspect, the cell is also a tandem solar cell. It may be incident on both sides (front and back) by light.

When the perovskite cell is in normal service, the perovskite cell side serves as a light incident side. The back electrode and the front electrode of the laminate battery were used as the positive and negative electrodes of the battery.

When the perovskite is invalid, the laminated solar cell is turned over, and the side of the silicon-based cell is used as a light incidence side. The back electrode of the laminated battery and the additional electrode arranged on the silicon-based battery are used as the positive electrode and the negative electrode of the battery.

Thus, the tandem solar cell proposed by the inventors and based on perovskite and silicon based materials will have a longer lifetime. Meanwhile, in the service period Of the perovskite, the battery combines the advantages Of the perovskite battery and the silicon-based material battery, so that the open-circuit voltage and the battery efficiency Of the battery are improved, and the reference average power Cost (LCOE) Of the battery is increased.

The following description is made in detail for a tandem solar cell and a method for manufacturing the same according to an embodiment of the present application:

the tandem solar cell in the example, as a whole, consists essentially of a top cell and a bottom cell bonded to each other. In the previous stage of the service life cycle of the battery, the top battery and the bottom battery are matched to work simultaneously to supply power; at the later stage of the battery life cycle, the bottom battery is mainly used for supplying power to the outside. Thus, from the foregoing, it can be seen that the top cell is a perovskite-based solar cell, while the bottom cell is a silicon-based solar cell.

In the combination region of the top cell and the bottom cell, the two are combined through a tunneling junction as a recombination region of carriers. And in some examples, the tunnel junction may take the form of a stack, such as a bilayer design (e.g., p-type nanocrystals and n-type nanocrystals).

For different structural forms of the tunnel junction, the other layers in the corresponding tandem solar cell can also be adjusted accordingly. As for the case of the scheme 1, the front electrode of the tandem solar cell is fabricated and used as the positive electrode, and the back electrode of the tandem solar cell is fabricated and used as the negative electrode. As for the case of the scheme 2, the front electrode of the tandem solar cell is fabricated and used as the negative electrode, and the back electrode of the tandem solar cell is fabricated and used as the positive electrode. In the present example, the description is made by taking scheme 1 as an example.

In addition, as one of the features of the design of the corresponding development of the tandem solar cell with a relatively long service life, the bottom cell of the solar cell of silicon-based material also has an additional electrode (which will be described later again with the sub-electrode). The additional electrode is adapted to the back electrode of the tandem solar cell. When the back electrode of the tandem solar cell is the positive electrode, the additional electrode is the negative electrode, and vice versa. Thus, the cell has three electrodes, typically to reduce shading while increasing contact area, and each electrode can be selected to be a finger electrode because the cell is a bifacial cell. The thickness of the electrode can be chosen to be between 100nm and 200 μm. The width of the gate lines for forming the gate finger electrodes may be between 1 micron and 200 microns. The number of main gates of the gate finger electrode may be one or more (e.g. at least two), such as two or three or four or five, or even more. Or the electrode can also be selected to be a zigzag electrode, wherein the outer ring and the inner ring are respectively an electrode.

Thus, in the present example, tandem solar cells include perovskite subcells, tunneling junctions, and silicon heterojunction cells. It should be noted that the tandem solar cell designed in the present example is a vertical junction solar cell, mainly comprising alternating P-type and N-type layers, which constitute different numbers of PN junctions. Or some PN junctions may be replaced with homotype junctions, such as NN + type junctions (high-low junctions) and the like, as desired.

Top battery

The perovskite sub-cell is used as a top cell, and the front surface of the perovskite sub-cell is provided with a top electrode through a first transparent conducting layer. The top electrode may be a gate finger electrode with an index (number of gate lines) of 3. In a perovskite sub-cell, the perovskite material acts as a photoactive layer. The subcell may also have other functional layers, such as a hole transport layer, an electron transport layer, etc. Perovskite materials have different choices according to different requirements. Perovskite materials generally have the shape of ABX₃The structure of (1). Wherein A is FA, MA and Cs which are mixed in any proportion, and B is one or two of Pb ions and Sn ions; x is at least one selected from I ion, Cl ion and Br ion.

E.g., FAPBI₃、MAPb(I_1-xBr_x)₃、MAPbI_1-x(SCN)_x、(BA)₂(MA)_n-1Pb_nI_3n+1And so on. In the present example, the perovskite material in the perovskite sub-cell is FA_1-xCs_xPbI₃And wherein 0.1<x<0.3。

Bottom battery

The silicon heterojunction cell is used as a bottom cell, and the front side of the silicon heterojunction cell is provided with a first combination region and a second combination region positioned at the periphery of the first combination region. The first combination area is provided with an auxiliary electrode through a second transparent conductive layer, and the back surface of the silicon heterojunction cell is provided with a bottom electrode through a third transparent conductive layer. The bottom electrode may be a gate finger electrode having an index (number of gate lines) of 5.

As the name implies, a silicon heterojunction cell is a semiconductor cell made of silicon material. It can have various expressions according to the classification of the material for making it, for example, the silicon heterojunction cell is a heterojunction cell, such as a junction made of silicon material; or a heterojunction battery made of materials such as silicon materials, germanium and the like. In addition, the structure in the heterojunction cell may be a homotype heterojunction (e.g., a P +/P junction or an N/N-junction or a P-/P junction or an N/N + junction), or a heterotype heterojunction (e.g., a P-N or a P-N) junction, depending on the type of junction that is constructed, and the multilayer heterojunction is referred to as a heterostructure. Alternatively, silicon heterojunction cells can also be classified as single junction cells or multi-junction cells according to the number of junctions in the silicon heterojunction cells.

For the first transparent conductive layer, the second transparent conductive layer and the third transparent conductive layer, the thicknesses of the first transparent conductive layer, the second transparent conductive layer and the third transparent conductive layer can be the same; alternatively, the three transparent conductive layers can be designed to have different thicknesses according to different requirements. Generally, the thickness of all three is between 50nm and 200 nm.

Tunneling junction

The tunneling junction has opposing top and bottom surfaces. The tunneling junction is configured in such a way: the top surface is bonded to the perovskite sub-cell and the bottom surface is bonded to the second bonding region of the silicon heterojunction cell to composite the perovskite sub-cell with the silicon heterojunction cell.

In general, for the electrodes of the solar cell, the electrodes on the front side (light incident side) are usually selected to be grid-like fingers, and the electrodes on the back side can be selected to be flat plate-like. In the present application, the tandem solar cell has a characteristic that light can be incident on both sides and photovoltaic power generation is performed, and therefore, the top electrode, the bottom electrode, and the sub-electrode are selected as the gate line electrode. The top electrode, the bottom electrode and the sub-electrode can be made of the same or different conductive materials. The conductive material is, for example, silver, a titanium copper alloy or a tin copper alloy.

As an alternative specific example, the silicon heterojunction cell in the tandem solar cell is selected as a multi-junction cell and has an N-type amorphous silicon layer, a first intrinsic amorphous silicon layer, an N-type crystalline silicon layer, a second intrinsic amorphous silicon layer, and a P-type amorphous silicon layer, which are sequentially layered. In the structure, the N-type crystalline silicon layer is taken as a substrate and has larger thickness relative to other structural layers in the silicon heterojunction cell.

In another alternative example, the silicon heterojunction cell is a multi-junction cell, and has an N-type amorphous silicon layer, a first intrinsic amorphous silicon layer, a P-type crystalline silicon layer, a second intrinsic amorphous silicon layer, and a P-type amorphous silicon layer, which are sequentially arranged in layers. In the structure, the P-type crystalline silicon layer is taken as a substrate and has larger thickness relative to other structural layers in the silicon heterojunction cell.

Accordingly, the perovskite battery has an electron transport layer, a perovskite layer, and a hole transport layer, which are sequentially layered.

The structure of the tandem solar cell based on the above structure is shown in fig. 2, fig. 3 and fig. 4. Wherein fig. 2 is a front view of the tandem solar cell and shows a structure of one side surface of the cell. Fig. 3 is a top view of a tandem solar cell and shows the electrode distribution on the front side of the cell. Fig. 4 is a bottom view of a tandem solar cell and shows the electrode distribution on the back side of the cell.

The battery is based on a perovskite/SHJ laminated battery and has the characteristic of double-sided power generation. Which has the following structure from the bottom and the top in sequence.

The bottom electrode 201 is a back conductive grid line, and can be made of silver, copper, or a composite of the silver and the copper with various metals, such as Ti/Cu and Sn/Cu. The bottom electrode 201 may be prepared by screen printing, i.e., a metal silver grid line is prepared on the back transparent conductive layer 202 by screen printing. The silver grid prepared by the screen printing method has the thickness of 5 micrometers to 200 micrometers and the width of 1 micrometer to 200 micrometers. The copper grid lines have a thickness of 100nm to 20 microns and a width of 1 micron to 200 microns. Another method of making the bottom electrode is electroplating. A thin layer of titanium (Ti) or tin (Sn) is first vapor-deposited or sputtered on the back transparent conductive layer 202 through a mask as a precursor, and then a copper grid line is plated on the Ti or Sn precursor in a solution of copper salt. The thickness of the grid line prepared by the electroplating method is 100 nanometers to 20 micrometers, wherein the thickness of the front body is 5nm to 100nm, and the width is 1 micrometer to 200 micrometers.

The back transparent conductive layer 202 can be made of Indium Tin Oxide (ITO), indium tungsten oxide (IWO), aluminum-doped zinc oxide AZO, or boron-doped zinc oxide BZO. The manufacturing method is magnetron sputtering deposition or Reactive Plasma Deposition (RPD), and the thickness is 50nm to 500 nm.

The amorphous silicon n-layer 203 is formed by Plasma Enhanced Chemical Vapor Deposition (PECVD) and has a thickness of 2nm to 200 nm.

The amorphous silicon i-layer 204 (intrinsic amorphous silicon) is fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) and has a thickness of 2nm to 50 nm.

The crystalline silicon wafer 205 may be an n-type silicon wafer or a p-type silicon wafer, and the silicon wafer has a thickness of 150 to 250 micrometers.

The amorphous silicon i-layer 206 is fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) to a thickness of 2nm to 50 nm.

The amorphous silicon p-layer 207 is fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) to a thickness of 2nm to 100 nm.

The silicon-based semiconductor layer of the cell is formed by the amorphous silicon n-layer 203 to the amorphous silicon p-layer 207 which are combined to form the SHJ cell. And the front side of the SHJ cell is in contact with the tunnel junction. The front side of the SHJ cell is also in contact with the secondary electrode 209 through a transparent conductive layer. The sub-electrode may have at least one gate line, for example, one gate line or a plurality of gate lines (two or more). For the case of multiple gate lines, all of the gate lines may be located on one or both sides of the tunnel junction. In fig. 2 to 4, all the gate lines are respectively arranged at two sides, and the number of the gate lines at the two sides is the same and is one; the number of gate lines on two separate sides may also be different. The negative electrode (as an example of the aforementioned bottom electrode 201) is in contact with the back transparent conductive layer.

Two superposed tin oxide layers are manufactured in a selected area (inner area) on the amorphous silicon p layer 207 by adopting a mask plate in a magnetron sputtering mode to form a tunneling junction. The two tin oxide layers include a bonding layer 210 in direct contact with the amorphous silicon p-layer 207, and an electron transport layer 211 in direct contact with the bonding layer 210 (which may also serve as an electron transport layer for a perovskite solar cell).

A transparent conductive layer is made in another selected area (outer area) on the amorphous silicon p-layer 207 using magnetron sputter deposition or Reactive Plasma Deposition (RPD). This conductive layer serves as the front transparent conductive layer 208 of the SHJ cell (silicon-based heterojunction HJT cell). And, Indium Tin Oxide (ITO), indium tungsten oxide (IWO) and a thickness of 50nm to 150nm are generally used alternatively.

The secondary electrode 209 is a conductive grid line and may be made of silver, copper, or a composite material of multiple metals such as Ti/Cu, or Sn/Cu.

The absorption layer 212 of the perovskite solar cell is made of FA_1-xCs_xPbI₃Wherein 0.1<x<0.3。

The hole transport layer 213 of the perovskite solar cell is made of nickel oxide NiO or cuprous thiocyanate (CuSCN) and has the thickness of 5nm to 100 nm. Among them, nickel oxide (NiO) may be fabricated by magnetron sputtering, Reactive Plasma Deposition (RPD), or chemical vapor deposition. Chemical vapor deposition includes Atomic Layer Deposition (ALD), Low Pressure Chemical Vapor Deposition (LPCVD), Metal Organic Chemical Vapor Deposition (MOCVD). Cuprous thiocyanate (CuSCN) was produced by vacuum evaporation.

The front transparent conductive layer 214 may be selectively fabricated using Indium Tin Oxide (ITO), indium tungsten oxide (IWO) by magnetron sputtering deposition or Reactive Plasma Deposition (RPD) with a thickness of 50nm to 150 nm.

The top electrode 215 is a front conductive grid line, and the material thereof may be silver, copper, or a composite material of multiple metals, such as Ti/Cu (titanium copper alloy), Sn/Cu (tin copper alloy).

In order to make it easier for the skilled person to implement the solution of the tandem solar cell described above, the following also gives a method for its fabrication. The battery has different manufacturing methods according to different structures of the SHJ battery.

The first manufacturing method comprises the following steps:

step S301, providing an N-type silicon wafer which is subjected to texturing, and is respectively provided with intrinsic amorphous silicon layers on the back surface and the front surface, and manufacturing a P-type amorphous silicon layer on one intrinsic amorphous silicon layer and manufacturing an N-type amorphous silicon layer on the other intrinsic amorphous silicon layer.

Step S302 is to form a first transparent conductive layer on the N-type amorphous silicon layer, and form a first gate line electrode on the first transparent conductive layer.

Step S303, a tunnel junction is formed in the first region of the P-type amorphous silicon layer, a second transparent conductive layer is formed in the second region of the P-type amorphous silicon layer, and a second gate line electrode is formed on the second transparent conductive layer, wherein the second region is located at the periphery of the first region.

And S404, sequentially laminating a perovskite absorption layer, a hole transport layer and a third transparent conducting layer on the tunneling junction.

Step S405, the third gate line is electrically disposed on the third transparent conductive layer.

The second manufacturing method comprises the following steps:

step S501, providing an N-type silicon wafer which is subjected to texturing, and is respectively provided with intrinsic amorphous silicon layers on the back and the front, and manufacturing a P-type amorphous silicon layer on one intrinsic amorphous silicon layer and manufacturing an N-type amorphous silicon layer on the other intrinsic amorphous silicon layer.

Step S502, forming a first transparent conductive layer on the P-type amorphous silicon layer, and forming a first gate line electrode on the first transparent conductive layer.

Step S503, respectively fabricating a tunnel junction in the first region of the N-type amorphous silicon layer, fabricating a second transparent conductive layer in the second region of the P-type amorphous silicon layer, and forming a second gate line electrode on the second transparent conductive layer, wherein the second region is located at the periphery of the first region.

Step S504, sequentially laminating a perovskite absorption layer, an electron transmission layer and a third transparent conducting layer on the tunneling junction.

Step S505, the third gate line is electrically disposed on the third transparent conductive layer.

A tandem solar cell and a method for fabricating the same according to the present application are further described in detail with reference to the following examples.

Example 1

And plating an intrinsic amorphous silicon layer on the upper surface and the lower surface of the cleaned and textured n-type silicon wafer respectively through plasma enhanced chemical vapor deposition, wherein the thicknesses of the intrinsic amorphous silicon layers are 10nm and 8nm respectively.

Then a layer of p-type amorphous silicon is deposited on the 8nm thick intrinsic amorphous silicon layer to a thickness of 10 nm. An n-type amorphous silicon layer with a thickness of 15nm is deposited on the 10nm thick intrinsic amorphous silicon layer.

And preparing a back transparent conducting layer on the n-type amorphous silicon layer by magnetron sputtering, wherein the material is Indium Tin Oxide (ITO) and the thickness is 120 nm. And preparing silver grid lines on the back transparent conducting layer subjected to magnetron sputtering by screen printing, wherein the distance between the silver grid lines is 2 mm. Each silver grid line has a height of 20 microns and a width of 50 microns.

A mask plate is arranged on the p-type amorphous silicon layer, and then a tunneling junction (formed by compounding double layers) with the thickness of 50nm is prepared in the laminated region by taking tin dioxide as a target material through magnetron sputtering. And preparing an indium tin oxide film layer on the front surface of the SHJ battery by magnetron sputtering on the p-type amorphous silicon layer by using a corresponding template, wherein the thickness of the indium tin oxide film layer is 100 nm. And preparing a silver grid line by screen printing, wherein the height of the silver grid line is 20 micrometers, and the width of the silver grid line is 50 micrometers.

Deposition of FA on tin dioxide as electron transport layer in a tunnel junction_0.9MA_0.1PbI₃The thickness of the perovskite absorption layer is 400 nm. The deposition method comprises the following steps: co-evaporating in vacuum; the evaporation raw materials are FAI, MAI and PbI2 respectively; with the following conditions: FAI evaporation temperature of 200 ℃, MAI evaporation temperature of 120 ℃, PbI₂The evaporation temperature was 400 degrees celsius and the temperature of the substrate material was 30 degrees celsius.

And depositing a hole transport layer with the thickness of 80nm on the deposited perovskite absorption layer by using polythiophene acetic acid. The deposition method is vacuum evaporation, the evaporation temperature of the raw material is 150 ℃, and the temperature of the substrate is 30 ℃.

And depositing a front transparent conductive layer with the film thickness of 80nm on the deposited hole transport layer by plasma deposition with indium tin oxide on the front surface.

And preparing a plurality of silver grid lines on the deposited transparent conductive layer by screen printing, wherein the distance between the silver grid lines is 2 mm, and each silver grid line has the height of 20 micrometers and the width of 50 micrometers.

Example 2

And plating an intrinsic amorphous silicon layer on each of two surfaces of the cleaned and textured n-type silicon wafer through plasma enhanced chemical vapor deposition, wherein the thickness of each intrinsic amorphous silicon layer is 10 nm.

And respectively depositing a layer of p-type amorphous silicon and a layer of n-type amorphous silicon on the two intrinsic amorphous silicon layers, wherein the thickness of the p-type amorphous silicon is 20nm, and the thickness of the n-type amorphous silicon is 15 nm.

And preparing a back transparent conductive layer with the thickness of 200nm on the p-type amorphous silicon layer by adopting aluminum-doped zinc oxide through magnetron sputtering. And then preparing silver grid lines on the back transparent conductive layer by screen printing, wherein the distance between the silver grid lines is 2 mm. Each silver grid line has a height of 20 microns and a width of 50 microns.

And preparing a front transparent conductive layer of the SHJ battery, which has the thickness of 120nm and is made of indium tin oxide, on the n-type amorphous silicon by using a corresponding mask. And further preparing silver grid lines by screen printing, wherein the distance between the silver grid lines is 2 mm. Each silver grid line has a height of 20 microns and a width of 50 microns.

And preparing a tunneling junction with the thickness of 15nm on the n-type amorphous silicon layer by taking the nanocrystalline as a raw material through chemical vapor deposition and utilizing a corresponding mask.

And preparing a hole transport layer on the tunneling junction in an evaporation coating mode, wherein the material is Spiro-TTB, the substrate temperature is 30 ℃, and the film thickness is 20 nm.

A perovskite absorption layer is then deposited on the hole transport layer Spiro-TTB. The material of the absorbing layer is FA_0.7MA_0.3PbI₃(ii) a The deposition method is vacuum co-evaporation. The evaporation raw materials are FAI, MAI and PbI2 respectively; FAI evaporation temperature is 200 ℃, MAI evaporation temperature is 140 ℃, PbI evaporation temperature is₂The evaporation temperature was 400 degrees celsius. The temperature of the substrate material was 30 degrees celsius. The thickness of the perovskite absorption layer is 400 nm.

And depositing an electron transmission layer on the deposited perovskite absorption layer, wherein the material is tin dioxide, the deposition method is atomic layer deposition, the evaporation temperature of the raw material is 85 ℃, and the film thickness is 20 nm.

And depositing a front transparent conductive layer on the deposited electron transport layer, wherein the material is indium tungsten oxide (IWO). The deposition method is reactive plasma deposition, and the thickness of the deposited film is 80 nm.

And preparing silver grid lines on the deposited transparent conductive layer of the back electrode by screen printing, wherein the height of the silver grid lines is 15 micrometers, and the width of the silver grid lines is 50 micrometers. The distance between the silver grid lines is 1.5 mm.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A tandem solar cell, comprising:

the front surface of the perovskite sub-battery is provided with a top electrode through a first transparent conducting layer;

the silicon heterojunction cell is used as a bottom cell, the silicon heterojunction cell is a multi-junction cell, the front side of the silicon heterojunction cell is provided with a first combination region and a second combination region positioned on the periphery of the first combination region, the first combination region is provided with an auxiliary electrode through a second transparent conductive layer, and the back side of the silicon heterojunction cell is provided with a bottom electrode through a third transparent conductive layer;

a tunneling junction having opposing top and bottom surfaces, the tunneling junction configured to bond with the top surface to the perovskite sub-cell and with the bottom surface to the second bonding region of the silicon heterojunction cell to recombine the perovskite sub-cell with the silicon heterojunction cell.

2. The tandem solar cell according to claim 1, wherein a hole transport layer and an electron transport layer are provided on each side of the perovskite sub-cell.

3. The tandem solar cell of claim 1, wherein the first, second and third transparent conductive layers have the same thickness.

4. The tandem solar cell according to claim 1 or 3, wherein the thickness of the first transparent conductive layer, the thickness of the second transparent conductive layer and the thickness of the third transparent conductive layer are each independently between 50nm and 100 nm.

5. The tandem solar cell of claim 1, wherein said top electrode, said bottom electrode, and said secondary electrode are all grid fingers.

6. The tandem solar cell of claim 1, wherein the top electrode, the bottom electrode, and the sub-electrode are all in the shape of a grid finger and each independently has a thickness between 100nm and 200 μm.

7. The tandem solar cell according to claim 5 or 6, wherein the width of the grid lines of the grid-finger electrode is 1 to 200 μm.

8. The tandem solar cell according to claim 1 or 5 or 6, wherein alternatively, the top electrode, the bottom electrode and the secondary electrode are each independently selected to be a silver electrode, a copper electrode, a titanium copper alloy electrode or a tin copper alloy electrode.

9. The tandem solar cell of claim 1, wherein the bottom electrode is a finger electrode having at least one grid line or the bottom electrode is a meander-shaped electrode;

optionally, the bottom electrode is a finger electrode having 5 gate lines;

optionally, the top electrode is a finger electrode having 3 gate lines.

10. The tandem solar cell according to claim 1 or 9, wherein the secondary electrode comprises at least one grid line or the secondary electrode is a meander-line electrode;

optionally, when the secondary electrode comprises at least two gate lines, all of the gate lines are located at one side of the tunnel junction.