High-passivation interlayer of perovskite / crystalline silicon laminated solar cell and cell thereof

Abstract

The invention discloses a high passivation interlayer of a perovskite / crystalline silicon laminated solar cell, which comprises a conductive transition metal oxide layer and an interface conductive layer which are arranged between a perovskite top cell and a crystalline silicon bottom cell, and the conductive transition metal oxide layer is deposited on a heavily doped silicon layer of the crystalline silicon bottom cell. An interface conductive layer is deposited over the conductive transition metal oxide layer. The double-layer structure of the conductive transition metal oxide layer / interface conductive layer is used as the intermediate layer of the perovskite / crystalline silicon laminated solar cell, the structures of the crystalline silicon bottom cell and the perovskite top cell are not limited, and the compatibility is high; according to the invention, through the non-destructive covering of the heavily-doped silicon layer and the hydrogen injection of the heavily-doped silicon layer, the direct contact between magnetron sputtering high-energy groups and particles and the heavily-doped silicon layer is avoided, and multiple effects of high optical transmission, rapid carrier extraction, rapid carrier conduction and recombination and the like are achieved; and the passivation level of the bottom cell is improved, so that the electrical performance of the laminated solar cell is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and particularly relates to a high-passivation intermediate layer and a battery of a perovskite / silicon heterojunction tandem solar cell. Background Art

[0002] As a two-junction solar cell, the perovskite / silicon heterojunction tandem solar cell can provide a higher conversion efficiency than a single-junction crystalline silicon solar cell, and is one of the development directions of future photovoltaic technologies. The crystalline silicon solar cell with a tunnel oxide passivated contact structure (TOPCon) is the mainstream in the current photovoltaic market due to its advantages of high efficiency, low cost, and mass production. Manufacturing a perovskite / silicon heterojunction tandem solar cell based on solar cells is conducive to the application of tandem technology in mass production.

[0003] A conventional perovskite / silicon heterojunction tandem solar cell is composed of a perovskite top cell, an interface conductive layer, and a crystalline silicon bottom cell connected in series. The main manufacturing steps of a perovskite / TOPCon tandem solar cell include: manufacturing the TOPCon bottom cell, removing the hydrogenated passivation layer of the dielectric on the front side of the bottom cell, preparing the interface conductive layer, and manufacturing the perovskite top cell. Among them, removing the hydrogenated passivation layer on the front side of the bottom cell and preparing the interface conductive layer are the keys to manufacturing a high-performance tandem cell.

[0004] The TOPCon bottom cell needs to be covered with a single-layer or multi-layer dielectric hydrogenated passivation film, and the passivation of the bottom cell is improved by releasing hydrogen. However, for a tandem cell, a series structure needs to be formed between the two sub-cells, and good ohmic contacts are required between the top layer / interface conductive layer of the bottom cell and the interface conductive layer / bottom layer of the top cell. This requires first removing the hydrogenated passivation layer on the front side of the bottom cell to expose the heavily doped silicon layer on the top layer; then, an interface conductive layer, such as a transparent conductive oxide (TCO) material like ITO or IZO, is prepared on the heavily doped silicon layer on the top layer. The interface conductive layer is the intermediate layer connecting the perovskite top cell and the crystalline silicon bottom cell. Then, a carrier transport layer of the bottom layer of the top cell and other subsequent film layers of the top cell are prepared on the interface conductive layer.

[0005] Among them, the conventional method for preparing the interfacial conductive layer is magnetron sputtering. The process mainly includes placing the TCO target in the vacuum chamber as the cathode, placing the bottom cell in the vacuum chamber to expose the heavily doped silicon layer as the anode. After forming a high-vacuum state, argon gas is ionized by electromagnetic waves to generate argon ions. At the same time, a high voltage is applied to both electrodes, so that the argon ions impact the TCO target cathode under the action of the electric field, sputtering out high-energy TCO groups and particles. These high-energy groups and particles rush towards the heavily doped silicon anode under the action of the electric field, collide violently with the heavily doped silicon layer and release energy to stay on its surface, forming a TCO layer. It can be seen that during the magnetron sputtering process, the high-energy TCO groups and particles directly contact and bombard the heavily doped silicon layer, generating many defects on the surface and even inside the heavily doped silicon, resulting in a significant decrease in the passivation level of the TOPCon structure and the bottom cell, and further leading to a significant reduction in the contribution of the TOPCon bottom cell to the open-circuit voltage and photoelectric conversion efficiency of the tandem cell. Summary of the Invention

[0006] Aiming at the problem of poor passivation effect of the existing intermediate layer, the purpose of the present invention is to provide a highly passivated intermediate layer and a battery for a perovskite / crystalline silicon tandem solar cell.

[0007] The present invention realizes the above technical effects through the following technical solutions:

[0008] In a first aspect, the present invention provides a highly passivated intermediate layer for a perovskite / crystalline silicon tandem solar cell. The highly passivated intermediate layer includes a conductive transition metal oxide layer and an interfacial conductive layer disposed between the perovskite top cell and the crystalline silicon bottom cell. The conductive transition metal oxide layer is deposited on the heavily doped silicon layer of the crystalline silicon bottom cell, and the interfacial conductive layer is deposited on the conductive transition metal oxide layer.

[0009] Preferably, the conductive transition metal oxide layer is prepared by atomic layer deposition. The preparation materials of the conductive transition metal oxide layer include one or more combinations of tin oxide, nickel oxide, molybdenum oxide, vanadium oxide, tungsten oxide, zinc oxide, titanium dioxide, indium oxide, tantalum oxide. Further preferably, the preparation materials of the conductive transition metal oxide layer are tin oxide or nickel oxide.

[0010] Preferably, the conductive transition metal oxide layer is prepared by atomic layer deposition, the deposition temperature is room temperature to 500 °C, and the deposition thickness is 0.1 to 300 nm. Further preferably, tin oxide or nickel oxide is prepared by atomic layer deposition, the deposition temperature is 50 to 250 °C, and the deposition thickness is 1 to 10 nm.

[0011] Preferably, the interface conductive layer is deposited on the conductive transition metal oxide layer by magnetron sputtering. The preparation material of the interface conductive layer is one or a combination of more of ITO, IZO, ATO, AZO, FTO or FZO, and the deposition thickness is 0.1-300 nm. Further preferably, the preparation material of the interface conductive layer is ITO or IZO, and the deposition thickness is 5-20 nm.

[0012] In a second aspect, the present invention provides a perovskite / crystalline silicon tandem solar cell, which includes a perovskite top cell, a crystalline silicon bottom cell, and the high-passivation intermediate layer as described above. The crystalline silicon bottom cell is a TOPCon cell.

[0013] Preferably, the preparation method of the perovskite / crystalline silicon tandem solar cell includes the following steps:

[0014] 1) Remove the hydrogen implantation passivation layer on the front side of the crystalline silicon bottom cell;

[0015] 2) Prepare a conductive transition metal oxide layer by atomic layer deposition;

[0016] 3) Prepare an interface conductive layer by magnetron sputtering;

[0017] 4) Prepare a perovskite top cell.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) Before magnetron sputtering to deposit the interface conductive layer, the present invention deposits a layer of conductive transition metal oxide layer on the exposed heavily doped silicon layer in advance; while satisfying the high photon transmission and fast carrier extraction, it realizes the blocking of high-energy active groups or particles during the magnetron sputtering process; avoids the direct contact between the groups or particles and the heavily doped silicon layer, reduces the sputtering and bombardment damage to the heavily doped silicon layer; reduces the production of surface and in-body defects, which is beneficial to improving the passivation level of the bottom cell.

[0020] 2) The present invention deposits a layer of conductive transition metal oxide layer on the heavily doped silicon layer in advance by ALD method. The obtained conductive transition metal oxide layer not only has strong bombardment blocking ability, hydrogen injection ability and carrier extraction ability, which is beneficial to the improvement of the fill factor; but also has excellent optical transparency and small optical loss, and causes no damage to the heavily doped silicon layer during the deposition process and does not generate additional defects.

[0021] 3) The conductive transition metal oxide is prepared by atomic layer deposition. Utilizing the characteristics of atomic layer deposition, not only does the deposition process cause no passivation damage to the heavily doped silicon layer and generate no additional defects, but also the deposited conductive transition metal oxide layer is rich in hydrogen, can carry a large amount of hydrogen, has excellent hydrogen injection ability, can perform hydrogen injection passivation on the heavily doped silicon layer, is beneficial to improving the passivation level of the bottom cell, and the formation of the conductive transition metal oxide layer does not require an additional annealing step, reducing the complexity of the processing flow and the cost.

[0022] 4) By using the high-passivation intermediate layer of the present invention, the decline in the passivation ability of the TOPCon structure after the preparation of the interface conductive layer can be inhibited, the voltage contribution of the TOPCon bottom cell to the tandem cell can be increased, and thus the open-circuit voltage and photoelectric conversion efficiency of the tandem solar cell can be improved.

[0023] 5) The high-passivation intermediate layer of the present invention has no restrictions on the front structure of the TOPCon bottom cell and the structure of the perovskite top cell, and has a high compatibility. The surface structure of the TOPCon cell can be double-sided planar, one-sided planar and one-sided textured, or double-sided textured; the TOPCon structure can exist on one side or both sides; the first hydrogen injection passivation layer can be a single-layer structure or a multi-layer structure.

[0024] 6) By using the simple double-layer structure of the conductive transition metal oxide layer / interface conductive layer of the present invention, multiple effects such as non-destructive coverage of the heavily doped silicon layer, hydrogen injection into the heavily doped silicon layer, avoiding direct contact between the high-energy groups and particles of magnetron sputtering and the heavily doped silicon layer, high optical transmittance, rapid carrier extraction, rapid carrier conduction and recombination can be achieved. Compared with the conventional direct magnetron sputtering deposition of the TCO layer, the damage is small, the defects are few, and the passivation of the bottom cell is high. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of the TOPCon bottom cell without a front metal electrode commonly used in the present invention;

[0026] Figure 2 It is a schematic structural diagram of the tandem solar cell of the present invention. Detailed Embodiments

[0027] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the following further details the present invention in combination with specific embodiments. It should be understood that the embodiments described herein are some but not all of the embodiments of the present invention, and are only used to explain the present invention, not to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0028] In a first aspect, the present invention provides a highly passivating intermediate layer for a perovskite / silicon heterojunction solar cell. The highly passivating intermediate layer includes a conductive transition metal oxide layer and an interfacial conductive layer disposed between the perovskite top cell and the silicon bottom cell. The conductive transition metal oxide layer is deposited on the heavily doped silicon layer of the silicon bottom cell, and the interfacial conductive layer is deposited on the conductive transition metal oxide layer.

[0029] In some specific embodiments, the conductive transition metal oxide layer is prepared by atomic layer deposition.

[0030] The present invention does not limit the number of layers of the conductive transition metal oxide layer. The preparation materials of the conductive transition metal oxide layer can be one or a combination of tin oxide, nickel oxide, molybdenum oxide, vanadium oxide, tungsten oxide, zinc oxide, titanium dioxide, indium oxide, tantalum oxide, etc. According to the characteristics of the transition metal oxide, the deposition temperature is room temperature to 500 °C, and the deposition thickness is 0.1 to 300 nm.

[0031] Due to the energy band structure and work function of tin oxide, it is suitable for extracting electrons and blocking holes; nickel oxide is suitable for extracting holes and blocking electrons; while the energy band structures of the remaining materials are not conducive to carrier extraction, or the passivation ability is poor. Therefore, the material of the conductive transition metal oxide layer is preferably tin oxide (SnO x 2) or nickel oxide (NiO x ).

[0032] As a preferred embodiment, tin oxide or nickel oxide is prepared by atomic layer deposition, the deposition temperature is 50 to 250 °C, and the deposition thickness is 1 to 10 nm.

[0033] More preferably, the deposition temperature for preparing tin oxide (SnO x 2) is 130 to 170 °C, and the deposition thickness is 5 to 10 nm; the deposition temperature for preparing nickel oxide (NiO x 2) is 180 to 220 °C, and the deposition thickness is 5 to 10 nm.

[0034] After removing the front hydrogen passivation layer, the heavily doped silicon layer in the TOPCon structure is exposed. If a conductive transition metal oxide layer (TMO layer) is prepared on the heavily doped silicon layer in advance by a coating method. Although the process of preparing the TMO layer by the coating method has no passivation damage, and the obtained TMO layer has bombardment blocking ability, optical transparency ability and carrier extraction ability, however, the TMO layer film formation requires an additional annealing step to promote solvent removal and material crystallization, increasing the complexity of the processing flow, and the obtained TMO layer has no hydrogen passivation ability, which is not conducive to improving the passivation of the bottom cell.

[0035] In the present invention, an atomic layer deposition method (ALD method) is used to pre-deposit a conductive TMO layer on a heavily doped silicon layer. Not only is the deposition process non-damaging to the heavily doped silicon layer and does not generate additional defects, but the obtained TMO layer has the capabilities of bombardment blocking, optical transmission, and carrier extraction. At the same time, since the oxygen source in the specific steps of the ALD method is usually deionized water or / and ozone, a hydrogen-rich TMO layer can be formed. In subsequent processing steps, heat treatment will release hydrogen, which has excellent hydrogen implantation ability, realizes hydrogen implantation passivation, and is beneficial to improving the passivation level of the bottom cell. Moreover, the formation of the TMO layer does not require an additional annealing step, reducing the complexity of the processing flow.

[0036] After removing the front-side hydrogen implantation passivation layer, the heavily doped silicon layer in the TOPCon structure is exposed. Subsequently, if a doped or / and hydrogen-containing amorphous silicon, or doped or / and hydrogen-containing amorphous silicon oxide, or doped or / and hydrogen-containing amorphous silicon carbide, or doped or / and hydrogen-containing amorphous silicon nitride is pre-deposited on the heavily doped silicon layer using plasma-enhanced chemical vapor deposition (PECVD) method. Although the obtained amorphous layer can block direct bombardment and has the capabilities of hydrogen implantation and carrier extraction, the parasitic absorption of amorphous silicon is obvious, resulting in significant optical losses and a low short-circuit current density Jsc of the battery. Moreover, the plasma in the PECVD process still has a bombardment effect on the heavily doped silicon layer, and additional defects will still be generated. In the present invention, an ALD method is used to deposit a conductive TMO layer, which not only causes no damage to the heavily doped silicon layer during the process and does not generate defects, but also the obtained TMO layer has excellent optical transparency and small optical losses.

[0037] In some specific embodiments, the interfacial conductive layer is deposited on the conductive transition metal oxide layer by magnetron sputtering.

[0038] The present invention does not limit the number of layers of the interfacial conductive layer. The preparation material of the interfacial conductive layer is a transparent conductive oxide (TCO), which can be one or a combination of indium tin oxide (ITO), indium zinc oxide (IZO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO), or FZO, etc. According to the special effects and process requirements of the transparent conductive oxide, the deposition thickness is 0.1 - 300 nm.

[0039] As a preferred embodiment, the preparation material of the interfacial conductive layer is ITO or IZO, and the deposition thickness is 5 - 20 nm. Using ITO or IZO, because of its mature technology, qualified and stable properties, an excellent and stable interfacial conductive layer can be obtained.

[0040] In a second aspect, the present invention provides a perovskite / silicon heterojunction tandem solar cell, which includes a perovskite top cell, a silicon bottom cell, and the high-passivation intermediate layer as described above, and the silicon bottom cell is a TOPCon cell.

[0041] As a preferred embodiment, the method for preparing the perovskite / crystalline silicon tandem solar cell includes the following steps:

[0042] 1) Remove the hydrogenated passivation layer on the front side of the crystalline silicon bottom cell;

[0043] 2) Prepare a conductive transition metal oxide layer by atomic layer deposition;

[0044] 3) Prepare an interfacial conductive layer by magnetron sputtering;

[0045] 4) Prepare the perovskite top cell.

[0046] The specific embodiments of the present invention will be further explained and illustrated below through examples and comparative examples.

[0047] The reagents, materials, and instruments used in the following description are all conventional reagents, conventional materials, and conventional instruments, which can be obtained commercially, unless otherwise specified. The methods in the examples are all conventional methods in the art, unless otherwise specified.

[0048] The TOPCon bottom cell involved in the present invention includes, but is not limited to, crystalline silicon solar cells with an n-type (or p-type) silicon substrate, one side having an n-type (or p-type) TOPCon structure, both sides having a TOPCon structure, both sides being planar, one side being textured and the other side being planar, and both sides being textured. The cell surface is covered with a single layer or multiple layers of dielectric hydrogenated passivation layers.

[0049] The schematic structural diagram of the common TOPCon bottom cell without a front metal electrode in the present invention is as Figure 1 shown. Taking the side with the TOPCon structure as the front side and the side with the metal electrode as the back side. From top to bottom, there are a first hydrogenated passivation layer (front hydrogenated passivation layer), a first heavily doped silicon layer (n-type or p-type), a first tunneling silicon oxide layer, a monocrystalline silicon substrate (n-type or p-type), an emitter layer (p-type or n-type), a second hydrogenated passivation layer (back hydrogenated passivation layer), and a back metal electrode.

[0050] Example 1 (tin oxide + ITO)

[0051] The method for preparing the perovskite / crystalline silicon tandem solar cell includes the following steps:

[0052] 1) Remove the hydrogenated passivation layer on the front side of the crystalline silicon bottom cell: Use photoresist or other oil-soluble liquids, and apply Figure 1Perform single-sided covering and wrapping on the back side (the side with metal electrodes) of the TOPCon bottom cell shown, and also wrap the sidewalls of the bottom cell; Immerse the wrapped bottom cell in a 5% hydrofluoric acid aqueous solution for 5 min to remove the dielectric first hydrogen implantation passivation layer on the front side, exposing the underlying heavily doped silicon layer; Send it into the wet cleaning system, wash with water to remove the residual hydrofluoric acid on the front side of the bottom cell, immerse it in acetone or other organic solvents to remove the wrapping layer, and expose the back side and sidewalls of the bottom cell;

[0053] 2) Prepare a conductive transition metal oxide layer by atomic layer deposition: Set the parameters as follows: chamber temperature 150 °C, carrier gas nitrogen flow rate 100 sccm, tin source: oxygen source pulse duration ratio 1 s:2 s, evacuation duration 10 s, number of cycles 20; Use tetra(dimethylamino)tin (abbreviated as TDMASn) as the tin source and deionized water as the oxygen source; Take out the bottom cell with the front-side heavily doped silicon layer exposed from the wet cleaning system and send it into the atomic layer deposition system. After preheating, start cyclic deposition to prepare a layer of conductive tin oxide layer on the heavily doped silicon layer, obtaining a tin oxide film thickness of 10 nm;

[0054] 3) Prepare an interface conductive layer by magnetron sputtering: Set the parameters as follows: RF radio frequency electromagnetic wave, power 80 W, room temperature, pressure 50 mTorr, Ar gas flow rate 500 sccm, duration 180 s; Take out the bottom cell deposited with the conductive tin oxide layer from the ALD system and send it into the magnetron sputtering chamber, and wait for the pressure to drop to the target value to start sputtering and deposition. Ionize Ar gas with electromagnetic waves to generate high-energy Ar ions, use them to bombard the target containing ITO, release ITO groups and particles, and deposit them on the conductive tin oxide layer under the action of an electric field to prepare the interface conductive layer ITO, obtaining an interface conductive layer ITO thickness of 20 nm. In this step, the high-energy groups and particles do not directly contact the heavily doped silicon layer, but directly contact the conductive transition metal oxide layer, avoiding the generation of defects in the heavily doped silicon layer. Therefore, the annealing step after deposition can be omitted or can be carried out as needed.

[0055] 4) Prepare a perovskite top cell: For the bottom cell deposited with the interface conductive layer above, use the common methods in the field of perovskite top cells to carry out the subsequent preparation of the perovskite top cell to obtain a complete tandem solar cell, and its structure is as Figure 2 shown.

[0056] Example 2 (nickel oxide + ITO)

[0057] This example includes most of the operation steps in Example 1, and the difference lies in the different materials and set parameters used in step 2) to prepare the conductive transition metal oxide layer.

[0058] Step 2) Prepare the conductive transition metal oxide layer by atomic layer deposition: Set the parameters: chamber temperature 200 °C, carrier gas nitrogen flow rate 100 sccm, nickel source: oxygen source pulse duration ratio 1 s:3 s, evacuation duration 10 s, number of cycles 30; Use nickel bis(acetylacetonate)bis(tetramethylethylenediamine) (abbreviated as Ni(acac)2(TMEDA)) as the nickel source and ozone as the oxygen source; Take out the bottom cell with the front-side heavily doped silicon layer exposed from the wet cleaning system and send it into the atomic layer deposition system. After preheating, start cyclic deposition to prepare a layer of conductive nickel oxide (NiOx) on the heavily doped silicon layer, and obtain a nickel oxide (NiOx) film thickness of 5 nm.

[0059] Example 3 (tin oxide + IZO)

[0060] This example includes most of the operation steps in Example 1, and the difference lies in the different materials and set parameters used in Step 3) to prepare the interfacial conductive layer.

[0061] Step 3) Prepare the interfacial conductive layer by magnetron sputtering: Set the parameters: RF radio frequency electromagnetic wave, power 120 W, room temperature, pressure 50 mTorr, Ar gas flow rate 500 sccm, duration 210 s; Take out the bottom cell deposited with the conductive tin oxide layer from the ALD system and send it into the magnetron sputtering system chamber, and wait for the pressure to drop to the target value to start sputtering and deposition. Ionize Ar gas with electromagnetic waves to generate high-energy Ar ions, bombard the target containing IZO with them to release IZO groups and particles, and deposit them on the conductive tin oxide layer under the action of an electric field to prepare the IZO interfacial conductive layer, and obtain an IZO interfacial conductive layer thickness of 10 nm.

[0062] Example 4 (nickel oxide + IZO)

[0063] This example includes most of the operation steps in Example 1, and the differences lie in that the materials and set parameters used in Step 2) to prepare the conductive transition metal oxide layer and the materials and set parameters used in Step 3) to prepare the interfacial conductive layer are both different. Specifically as follows:

[0064] Step 2) Prepare the conductive transition metal oxide layer by atomic layer deposition: Set the parameters: chamber temperature 180 °C, carrier gas nitrogen flow rate 100 sccm, nickel source: oxygen source pulse duration ratio 1 s:3 s, evacuation duration 10 s, number of cycles 30; Use nickel bis(acetylacetonate)bis(tetramethylethylenediamine) (abbreviated as Ni(acac)2(TMEDA)) as the nickel source and ozone as the oxygen source; Take out the bottom cell with the front-side heavily doped silicon layer exposed from the wet cleaning system and send it into the atomic layer deposition system. After preheating, start cyclic deposition to prepare a layer of conductive nickel oxide (NiOx) on the heavily doped silicon layer, and obtain a nickel oxide (NiOx) film thickness of 10 nm;

[0065] Step 3) Prepare the interfacial conductive layer by magnetron sputtering: Set the parameters: RF radio frequency electromagnetic wave, power 120 W, room temperature, pressure 50 mTorr, Ar gas flow rate 500 sccm, duration 210 s; Take out the bottom cell deposited with the conductive nickel oxide layer from the ALD system, send it into the cavity of the magnetron sputtering system, and wait for the pressure to drop to the target value to start sputtering and deposition. Ionize Ar gas with electromagnetic waves to generate high-energy Ar ions, bombard the target containing IZO with them, release IZO groups and particles, and deposit them on the conductive tin oxide layer under the action of an electric field to prepare the IZO interfacial conductive layer, obtaining an IZO interfacial conductive layer with a thickness of 20 nm.

[0066] Comparative Example 1 (hydrogen-doped amorphous silicon + ITO)

[0067] The difference between this comparative example and Example 1 is that in step 2), a layer of hydrogen-doped amorphous silicon is pre-deposited on the heavily doped silicon layer of the bottom cell by plasma-enhanced chemical vapor deposition (PECVD), and the other steps are the same.

[0068] Comparative Example 2 (hydrogen-doped amorphous silicon oxide + ITO)

[0069] The difference between this comparative example and Example 1 is that in step 2), a layer of hydrogen-doped amorphous silicon oxide is pre-deposited on the heavily doped silicon layer of the bottom cell by plasma-enhanced chemical vapor deposition (PECVD), and the other steps are the same.

[0070] Prepare perovskite / crystalline silicon tandem solar cells by the methods of Comparative Examples 1-2, and the following problems are found: Although the amorphous layer prepared in step 2) can block direct bombardment and has the ability of hydrogen injection and carrier extraction, however, the parasitic absorption of amorphous silicon is obvious, resulting in significant optical losses and a low short-circuit current density Jsc of the battery; moreover, the plasma in the PECVD process still has a bombardment effect on the heavily doped silicon layer, and additional defects will still be generated.

[0071] Comparative Example 3 (coating method TMO + ITO)

[0072] The difference between this comparative example and Example 1 is that in step 2), a conductive transition metal oxide layer is prepared by a coating method on the heavily doped silicon layer of the bottom cell, and the other steps are the same.

[0073] The perovskite / silicon heterojunction tandem solar cell was prepared by the method of Comparative Example 3, and the following problems were found: In step 2), although there is no passivation damage in the process of preparing the TMO layer by the coating method, and the obtained TMO layer has the ability to block bombardment, optical transparency, and carrier extraction ability, however, the formation of the TMO layer requires an additional annealing step to promote solvent removal and crystallization of substances, which increases the complexity of the processing flow, and the obtained TMO layer has no hydrogen injection passivation ability, which is not conducive to improving the passivation of the bottom cell.

[0074] Comparative Example 4 (ALD method silicon oxide + ITO)

[0075] The difference between this comparative example and Example 1 is that in step 2), a layer of silicon oxide was pre-deposited on the heavily doped silicon layer of the bottom cell by atomic layer deposition (ALD) method, and the other steps are the same.

[0076] Comparative Example 5 (ALD method aluminum oxide + ITO)

[0077] The difference between this comparative example and Example 1 is that in step 2), a layer of aluminum oxide was pre-deposited on the heavily doped silicon layer of the bottom cell by atomic layer deposition (ALD) method, and the other steps are the same.

[0078] The perovskite / silicon heterojunction tandem solar cell was prepared by the method of Comparative Examples 4-5, and the following problems were found: poor passivation of silicon oxide, low carrier selectivity, and low conductivity; the passivation of aluminum oxide is stronger than that of silicon oxide, but the same low carrier selectivity and low conductivity; moreover, although substances such as silicon oxide have charge transfer effects when the thickness is less than 2 nm, they have no selectivity and cannot distinguish between electrons and holes, which is not conducive to carrier extraction and the improvement of the fill factor of the battery.

[0079] Comparative Example 6

[0080] The difference between this comparative example and Example 1 is that there is no step 2), and a 20-nm interface conductive layer (TCO) was directly deposited on the heavily doped silicon layer.

[0081] The perovskite / silicon heterojunction tandem solar cell was prepared by the method of Comparative Example 6, and the following problems mentioned in the background technology of the present invention were found: direct contact and bombardment of high-energy TCO groups and particles on the heavily doped silicon layer, resulting in many defects on the surface and even in the body of the heavily doped silicon, leading to a significant decrease in the passivation level of the TOPCon structure and the bottom cell, and further leading to a significant decrease in the contribution of the TOPCon bottom cell to the open-circuit voltage and photoelectric conversion efficiency of the tandem cell.

[0082] Performance test:

[0083] The perovskite / crystalline silicon tandem solar cells obtained by using the above examples and comparative examples were subjected to performance tests. The performance parameters: open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and photoelectric conversion efficiency (PCE) were measured by common testing methods in the art. The test results are shown in Table 1.

[0084] Table 1:

[0085]

[0086] From the test results of Example 1 and Comparative Examples 1-2, it can be seen that compared with the method of pre-depositing an amorphous layer by plasma-enhanced chemical vapor deposition (PECVD), the present invention can improve the passivation level of the bottom cell, and the open-circuit voltage, short-circuit current density, and photoelectric conversion efficiency of the tandem solar cell are significantly improved.

[0087] From the test results of Example 1 and Comparative Example 3, it can be seen that compared with the method of preparing a conductive transition metal oxide layer by coating, the present invention can improve the passivation level of the bottom cell, and the open-circuit voltage and photoelectric conversion efficiency of the tandem solar cell are significantly improved.

[0088] From the test results of Example 1 and Comparative Examples 4-5, it can be seen that compared with the method of preparing other oxides (such as silicon oxide or aluminum oxide) by atomic layer deposition (ALD), the fill factor of the tandem solar cell is improved.

[0089] From the test results of Example 1 and Comparative Example 6, it can be seen that compared with directly depositing an interface conductive layer on a heavily doped silicon layer, the present invention can improve the passivation level of the bottom cell, and the open-circuit voltage and photoelectric conversion efficiency of the tandem solar cell are significantly improved.

[0090] Thus, the present invention uses atomic layer deposition (ALD) to pre-deposit a layer of conductive transition metal oxide layer on a heavily doped silicon layer, and then uses magnetron sputtering to deposit an interface conductive layer on the conductive transition metal oxide layer, which can cause no damage to the heavily doped silicon layer and no generation of defects. The obtained TMO layer has excellent optical transmittance and small optical loss. Moreover, the processing flow is simple. In the subsequent processing steps, heat treatment will release hydrogen, which has excellent hydrogen injection ability, realizes hydrogen injection passivation, is beneficial to improving the passivation level of the bottom cell, and thus improves the open-circuit voltage and photoelectric conversion efficiency of the tandem solar cell.

[0091] The above further describes the present invention with the aid of specific examples. However, it should be understood that the specific description here should not be construed as a limitation on the essence and scope of the present invention. Various modifications made by those of ordinary skill in the art after reading the above examples all fall within the scope protected by the present invention.

Claims

1. A high-passivation intermediate layer for a perovskite / crystalline silicon tandem solar cell, characterized in that, The high-passivation intermediate layer includes a conductive transition metal oxide layer and an interfacial conductive layer disposed between the perovskite top cell and the crystalline silicon bottom cell. The conductive transition metal oxide layer is deposited on the heavily doped silicon layer of the crystalline silicon bottom cell, and the interfacial conductive layer is deposited on the conductive transition metal oxide layer.

2. The high-passivation intermediate layer of the perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that, The conductive transition metal oxide layer is prepared by atomic layer deposition. The preparation materials of the conductive transition metal oxide layer include one or more of tin oxide, nickel oxide, molybdenum oxide, vanadium oxide, tungsten oxide, zinc oxide, titanium dioxide, indium oxide, and tantalum oxide.

3. The high-passivation intermediate layer of the perovskite / silicon heterojunction tandem solar cell according to claim 2, wherein When preparing the conductive transition metal oxide layer by atomic layer deposition, the deposition temperature is room temperature to 500 °C, and the deposition thickness is 0.1 to 300 nm.

4. The high-passivation intermediate layer of the perovskite / silicon heterojunction solar cell according to claim 2, wherein, The preparation material of the conductive transition metal oxide layer is tin oxide or nickel oxide.

5. The high-passivation intermediate layer of the perovskite / silicon heterojunction tandem solar cell according to claim 2, wherein When preparing tin oxide or nickel oxide by atomic layer deposition, the deposition temperature is 50 to 250 °C, and the deposition thickness is 1 to 10 nm.

6. The high-passivation intermediate layer of the perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that The interfacial conductive layer is deposited on the conductive transition metal oxide layer by magnetron sputtering. The preparation materials of the interfacial conductive layer are one or more of ITO, IZO, ATO, AZO, FTO, or FZO, and the deposition thickness is 0.1 to 300 nm.

7. The high-passivation intermediate layer of the perovskite / crystalline silicon tandem solar cell according to claim 1, wherein The preparation material of the interfacial conductive layer is ITO or IZO, and the deposition thickness is 5 to 20 nm.

8. A perovskite / silicon heterojunction tandem solar cell, characterized in that, The tandem solar cell includes a perovskite top cell, a crystalline silicon bottom cell, and the high-passivation intermediate layer as described in claims 1 to 7. The crystalline silicon bottom cell is a TOPCon cell.

9. The perovskite / silicon heterojunction tandem solar cell according to claim 8, wherein, The preparation method of the tandem solar cell includes the following steps: 1) Remove the hydrogen injection passivation layer on the front side of the crystalline silicon bottom cell; 2) Prepare the conductive transition metal oxide layer by atomic layer deposition; 3) Prepare the interfacial conductive layer by magnetron sputtering; 4) Prepare the perovskite top cell.

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