Bifacial silicon / perovskite tandem solar cell

Abstract

The present invention relates to a tandem solar cell, and more particularly to a bifacial silicon / perovskite tandem solar cell that can enhance light absorption at the bottom and achieve significantly high photoelectric conversion efficiency.

Description

[Technical Field]

[0001] The present invention relates to a tandem solar cell, and more particularly to a bifacial silicon / perovskite tandem solar cell that can enhance light absorption at the bottom and achieve significantly high photoelectric conversion efficiency. [Background technology]

[0002] Multi-junction (tandem) solar cells attempt to minimize thermalization loss by effectively utilizing solar energy across a wide wavelength range through vertically stacking photoabsorption layers with different bandgaps. Specifically, tandem solar cells overcome the efficiency limitations of single-junction solar cells by minimizing the loss of excess electron-hole energy as heat energy when photons with higher energy than the bandgap are absorbed by the photoabsorption layer in single-junction solar cells through the use of photoabsorption layers with different bandgaps. Recently, interest in tandem solar cells as the most promising next-generation solar cells has been increasing, and a fierce global R&D race is underway to pioneer tandem solar cell technologies with various structures.

[0003] Conventional tandem solar cells are manufactured as two-terminal tandem solar cells by forming a recombination layer on a lower silicon solar cell and then forming an upper perovskite solar cell, with the lower electrode being a front electrode, or as four-terminal tandem solar cells by joining the perovskite solar cell on the lower silicon solar cell via an intermediate layer.

[0004] However, in the case of conventional tandem solar cells, the lower electrode is formed as a front electrode, so light reflected by the surrounding environment on the rear surface of the element cannot be absorbed, which limits the maximum current that can be obtained.

[0005] Therefore, there is an urgent need to research tandem solar cells that can solve the above-mentioned problems, increase light absorption at the bottom, and obtain significantly higher photoelectric conversion efficiency. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been devised to overcome the above-mentioned problems, and its purpose is to provide a bifacial silicon / perovskite tandem solar cell that can enhance light absorption at the bottom and achieve significantly higher photoelectric conversion efficiency. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides a bifacial silicon / perovskite tandem solar cell including: a silicon lower cell including a silicon layer and a first grid electrode disposed on a lower surface of the silicon layer; a perovskite upper cell including a perovskite absorber layer having a thickness of more than 600 nm to 2,000 nm; and a connecting layer connecting the silicon lower cell and the perovskite upper cell.

[0008] According to one embodiment of the present invention, the perovskite absorber layer may have a thickness of more than 600 nm.

[0009] The perovskite absorption layer may have a thickness of 650 nm to 1,700 nm.

[0010] The perovskite top cell may also have a bandgap of less than 1.66 eV.

[0011] The silicon lower cell may further include a passivation layer on a lower surface of the silicon layer, and the first grid electrode may be disposed on the passivation layer.

[0012] The silicon layer may be a p-type silicon layer, and may further include an n-type emitter layer on an upper surface of the silicon layer.

[0013] The connection layer may be a recombination layer or an intermediate layer including at least one selected from the group consisting of a transparent conductive oxide, a carbonaceous conductive material, a metallic material, and a conductive polymer.

[0014] The silicon lower cell may have any one structure selected from the group consisting of Al-BSF, PERC, PERT, PERL, and TOPCon structures.

[0015] Furthermore, when the connection layer is a recombination layer, the bifacial silicon / perovskite tandem solar cell may be a two-terminal bifacial silicon / perovskite tandem solar cell in which the perovskite upper cell further includes a second grid electrode on the top of the perovskite absorption layer; and when the connection layer is an intermediate layer, the bifacial silicon / perovskite tandem solar cell may be a four-terminal bifacial silicon / perovskite tandem solar cell in which the silicon lower cell further includes a second grid electrode on the top of the silicon layer, the second grid electrode being partially incorporated in the intermediate layer.

[0016] Also, at least a portion of the lower surface of the silicon lower cell may have a pyramidal unevenness formed thereon, and the pyramidal unevenness may have a pyramidal angle of more than 5°. [Effects of the Invention]

[0017] The bifacial silicon / perovskite tandem solar cell according to the present invention has the effect of increasing light absorption at the bottom and achieving significantly high photoelectric conversion efficiency. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional schematic diagram of a bifacial silicon / perovskite tandem solar cell according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional schematic diagram of a bifacial silicon / perovskite tandem solar cell according to another embodiment of the present invention. [Figure 3] FIG. 3 is a graph showing current values ​​as a function of light irradiation rate for bifacial silicon / perovskite tandem solar cells according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2 of the present invention. [Figure 4] FIG. 4 is a graph showing current values ​​as a function of light irradiation rate for bifacial silicon / perovskite tandem solar cells according to Examples 1, 3, and 4 of the present invention and Comparative Example 1. [Figure 5] FIG. 5 is a graph showing current values ​​versus light irradiation rates for bifacial silicon / perovskite tandem solar cells according to Examples 1-1 to 1-3, 3-1 to 3-3, and 4-1 to 4-3 of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to exemplary embodiments thereof, so that those skilled in the art will be able to easily implement the present invention. As such, the present invention may be embodied in various different forms and is not limited to the embodiments set forth herein.

[0020] As mentioned above, in the case of conventional tandem solar cells, the lower electrode is formed as a front electrode, so light reflected by the surrounding environment on the rear surface of the device cannot be absorbed, and there is a limit to the maximum current that can be obtained.

[0021] Therefore, in order to solve the above-mentioned problems, the present invention provides a bifacial silicon / perovskite tandem solar cell including: a silicon lower cell including a silicon layer and a first grid electrode disposed on a lower surface of the silicon layer; a perovskite upper cell including a perovskite absorber layer having a thickness of more than 600 nm to 2,000 nm; and a connecting layer connecting the silicon lower cell and the perovskite upper cell, thereby seeking to solve the above-mentioned problems.

[0022] Through this, the present invention can increase light absorption at the bottom and achieve significantly higher photoelectric conversion efficiency.

[0023] In this specification, the lower cell refers to a silicon solar cell formed at the bottom of a tandem solar cell, and the upper cell refers to a perovskite solar cell formed at the top of a tandem solar cell.

[0024] In addition, in this specification, a silicon lower cell refers to a solar cell containing silicon as a light absorbing layer, and a perovskite upper cell refers to a solar cell containing a material having a perovskite structure as a light absorbing layer.

[0025] The tandem solar cell element according to the present invention will be specifically described below with reference to the drawings.

[0026] As shown in FIGS. 1 and 2, a bifacial silicon / perovskite tandem solar cell 1000, 1000′ according to the present invention is embodied including a silicon lower cell 100, 100′, a perovskite upper cell 200, 200′, and a connecting layer 300, 300′ connecting the silicon lower cell 100, 100′ and the perovskite upper cell 200, 200′.

[0027] First, the silicon lower cells 100, 100' will be described.

[0028] The silicon lower cell 100, 100' includes a silicon layer 110 and may further include an emitter layer 120 on an upper surface of the silicon layer 110.

[0029] The silicon layer 110 may have one of the structures of known silicon solar cells and is not limited to a specific structure. For example, the silicon layer 110 may include a crystalline silicon substrate (not shown), a p-type amorphous or crystalline silicon layer (not shown), an n-type amorphous or crystalline silicon layer (not shown), or an amorphous intrinsic silicon layer (not shown). Although not shown, the silicon layer 110 may further include additional layers as needed. According to a more preferred embodiment, considering industrial advantages such as ease of internal gettering, which helps improve cell efficiency compared to n-type silicon, or process simplification, the silicon layer 110 may be a p-type silicon layer, and the emitter layer 120 may be an n-type emitter layer.

[0030] According to one embodiment of the present invention, the silicon lower cell 100, 100' has a structure in which n-type silicon is deposited on the surface of p-type silicon. ++ Al-BSF (Aluminum Back Surface Field), PERC (Passivated Emitter and Rear Cell), PERT (Passivated Emitter Rear Totally Diffused) and PERL (Passivated Emitter and Rear Locally Diffused) structures through the formation of emitters or SiOx tunneling layer / n ++ There is no particular limitation, and a TOPCon (Tunnel oxide passivated contact) structure through the formation of poly-Si may also be used.

[0031] In addition, the silicon lower cell 100, 100' includes a first grid electrode 130 disposed on the lower surface of the silicon layer 110. This increases light absorption of light reflected from the rear surface, thereby increasing current and photoelectric conversion efficiency.

[0032] The silicon lower cell 100, 100′ may further include a passivation layer on the lower surface of the silicon layer 110, and the first grid electrode 130 may be disposed on the passivation layer, but is not limited thereto.

[0033] At least a portion of the lower surface of the silicon lower cell 100, 100' may be textured with pyramidal irregularities to improve light efficiency. That is, an irregular surface (see FIGS. 1 and 2) is formed in the direction of light incidence, and the light scattering effect of the light incident through the irregular surface increases the path of light incident on the silicon layer 110, improving light collection and increasing the solar absorption rate, thereby achieving a high current value. In this case, the texturing may have a surface pyramidal angle of more than 5°, preferably more than 30°, which may be more advantageous in achieving the objects of the present invention.

[0034] Furthermore, as shown in FIG. 2, a bifacial silicon / perovskite tandem solar cell according to another embodiment of the present invention may be a four-terminal bifacial silicon / perovskite tandem solar cell in which the silicon lower cell 100, 100′ further includes a second grid electrode 140, which is partially included in a connection layer 300′ (to be described later), on top of the silicon layer 110, preferably on the emitter layer 120.

[0035] Next, the perovskite upper cells 200, 200' will be described.

[0036] The perovskite upper cells 200 and 200 ′ are cells connected to the silicon lower cells 100 and 100 ′, and may have a band gap of less than 1.66 eV.

[0037] In addition, as shown in FIG. 1, a bifacial silicon / perovskite tandem solar cell according to an embodiment of the present invention may include a hole transport layer 220, a perovskite absorption layer 210, an electron transport layer 230, a transparent electrode layer 240, an anti-reflection film 250, and a second grid electrode 260 stacked in this order on a connection layer 300 (described later).

[0038] 2, a bifacial silicon / perovskite tandem solar cell according to another embodiment of the present invention may include a transparent electrode layer 242, a hole transport layer or electron transport layer 220, a perovskite absorption layer 210, a hole transport layer or electron transport layer 230, a transparent electrode layer 241, and glass 270 stacked in this order on a connecting layer 300′ (described later). In this case, when the hole transport layer or electron transport layer 220 on the transparent electrode layer 242 is a hole transport layer, the other hole transport layer or electron transport layer 230 may be an electron transport layer. Conversely, when the hole transport layer or electron transport layer 220 on the transparent electrode layer 242 is an electron transport layer, the other hole transport layer or electron transport layer 230 may be a hole transport layer. Preferably, the bifacial silicon / perovskite tandem solar cell according to another embodiment of the present invention may include a transparent electrode layer 242, a hole transport layer 220, a perovskite absorber layer 210, an electron transport layer 230, a transparent electrode layer 241, and glass 270 stacked together.

[0039] The perovskite absorption layer 210 may be formed so that hole-electron pairs generated by receiving light energy from the sun can be separated into electrons or holes. In one embodiment, electrons formed in the perovskite absorption layer 210 may be transferred to the electron transport layer 230, and holes formed in the perovskite absorption layer 210 may be transferred to the hole transport layer 220.

[0040] In this case, the perovskite absorption layer 210 may include an organic halide perovskite such as methyl ammonium iodide (MAI) or formamidinium iodide (FAI), or a metal halide perovskite such as lead iodide (PbI), bromine iodide (PbBr), or lead chloride (PbCl). That is, the perovskite absorption layer 210 may have a multilayer structure including at least one of an organic halide perovskite or a metal halide perovskite. More specifically, the perovskite absorption layer 210 may be represented by AMX3 (where A is a monovalent organic ammonium cation or metal cation; M is a divalent metal cation; and X is a halogen anion). Non-limiting examples of this include CH3NH3PbI3, CH3NH3PbI x Cl 3-x , CH3NH3PbI x Br 3-x , CH3NH3PbCl x Br 3-x , HC(NH2)2PbI3, HC(NH2)2PbI x Cl 3-x , HC(NH2)2PbI x Br 3-x , HC(NH2)2PbCl x Br 3-x , (CH3NH3)(HC(NH2)2) 1-y PbI3, (CH3NH3)(HC(NH2)2) 1-y PbI x Cl 3-x , (CH3NH3)(HC(NH2)2) 1-y PbI x Br 3-x , or (CH3NH3)(HC(NH2)2) 1-y PbCl x Br 3-x etc. can be used (0=x, y=1).

[0041] Furthermore, the perovskite absorption layer 210 may have a thickness of more than 600 nm to 2,000 nm, preferably 650 nm to 1,700 nm. If the thickness of the perovskite absorption layer is 600 nm or less, even if the current of the lower cell increases, the current is limited to the upper cell, resulting in current matching, and the current value may not increase as intended due to an increase in the lower light irradiation rate. If the thickness exceeds 2,000 nm, limitations in solution processability may result in a decrease in thin film grain size, an increase in defect sites, an increase in surface roughness, and other problems, which may limit charge movement and reduce device performance.

[0042] The hole transport layer 220 serves to separate and transport holes formed in the perovskite absorption layer 210 and may be made of a known material as long as it meets the objectives of the present invention. Non-limiting examples of the material include Mo oxide, Ni oxide, W oxide, Cu oxide, V oxide, CuCN, and CuI.

[0043] The electron transport layer 230 serves to separate and transport electrons formed in the perovskite absorption layer 210 and may be formed of a known material as long as it satisfies the objective of the present invention. Non-limiting examples of the electron transport layer 230 include Ti oxide, Zn oxide, In oxide, Sn oxide, W oxide, Nb oxide, Mo oxide, Mg oxide, Zr oxide, Sr oxide, Yr oxide, La oxide, V oxide, Al oxide, Y oxide, Sc oxide, Sm oxide, Ga oxide, In oxide, and SrTi oxide.

[0044] The transparent electrode layers 240, 241, and 242 transfer charges to the metal electrode (second grid electrode). The transparent electrode layers 240, 241, and 242 may be implemented with at least one material selected from the group consisting of transparent conductive oxides, carbonaceous conductive materials, metallic materials, and conductive polymers, and preferably include transparent conductive oxides.

[0045] The anti-reflection film 250, the second grid electrode 260, and the glass 270 may be any material that is commonly used in the art, and the present invention does not limit them.

[0046] As described above, the perovskite upper cell 100, 100' of the bifacial silicon / perovskite tandem solar cell 1000, 1000' according to the present invention may have a bandgap of less than 1.66 eV, preferably 1.63 eV or less. If the bandgap of the perovskite upper cell exceeds 1.66 eV, the backside illumination efficiency increases, but the increase in current value is small, making it difficult to achieve the objectives of the present invention. The bandgap of the perovskite upper cell can be controlled by controlling the composition of the perovskite with an ABX2 structure (for the formation of a perovskite with a low bandgap, CH3NH3PbI3, CH3NH3PbI x Cl 3-x , CH3NH3PbI x Br 3-x , CH3NH3PbCl x Br 3-x , HC(NH2)2PbI3, HC(NH2)2PbI x Cl 3-x , HC(NH2)2PbI x Br 3-x , HC(NH2)2PbCl x Br 3-x , (CH3NH3)(HC(NH2)2) 1-y PbI3, (CH3NH3)(HC(NH2)2) 1-y PbI x Cl 3-x , (CH3NH3)(HC(NH2)2) 1-y PbI x Br 3-x , or (CH3NH3)(HC(NH2)2) 1-y PbCl x Br 3-x (e.g., increasing the CH3NH3- content or decreasing the Br content in the perovskite composition).

[0047] Next, the connection layers 300 and 300' will be described.

[0048] The connection layers 300, 300' connect the silicon lower cells 100, 100' and the perovskite upper cells 200, 200', and serve to physically and electrically connect the silicon lower cells 100, 100' and the perovskite upper cells 200, 200', thereby enabling charge recombination between the upper and lower cells.

[0049] The connection layers 300, 300′ may be made of any material commonly used in the art. However, in order to achieve the object of the present invention, the connection layers 300, 300′ may include at least one selected from the group consisting of transparent conductive oxides, carbonaceous conductive materials, metallic materials, and conductive polymers. More preferably, the connection layers 300, 300′ may be at least one TCO-based material selected from the group consisting of ITO (Indium Tin Oxide), ICO (Indium Cerium Oxide), IWO (Indium Tungsten Oxide), ZITO (Zinc Indium Tin Oxide), ZIO (Zinc Indium Oxide), ZTO (Zinc Tin Oxide), GITO (Gallium Indium Tin Oxide), GIO (Gallium Indium Oxide), GZO (Gallium Zinc Oxide), AZO (Aluminum doped Zinc Oxide), FTO (Fluorine Tin Oxide), and ZnO, and / or nc-Si:H material layers.

[0050] The thickness of the connection layer 300, 300' may be 5 to 50 nm, and more preferably 10 to 30 nm. If the thickness of the connection layer exceeds 50 nm, problems may occur, such as current loss due to increased parasitic absorption and a decrease in horizontal resistance, resulting in a shunt path and a decrease in efficiency. Furthermore, if the thickness of the connection layer is less than 5 nm, a decrease in recombination and a decrease in efficiency may occur due to limited electron mobility.

[0051] The connection layer 300, 300' may be a recombination layer 300 or an intermediate layer 300'. When the connection layer 300, 300' is a recombination layer 300, the bifacial silicon / perovskite tandem solar cell 1000 may be a two-terminal bifacial silicon / perovskite tandem solar cell in which the perovskite upper cell 200 further includes a second grid electrode 260 on the upper side of the perovskite absorption layer 210. When the connection layer 300, 300' is an intermediate layer 300', the bifacial silicon / perovskite tandem solar cell 1000' may be a four-terminal bifacial silicon / perovskite tandem solar cell in which the silicon lower cell 100' further includes a second grid electrode 140 on the upper side of the silicon layer 110, the second grid electrode 140 being partially embedded in the intermediate layer 300'.

[0052] The tandem solar cell element according to the present invention has been described above, but this is merely an example, and the tandem solar cell element may further include an additional stack structure that can improve the efficiency of the solar cell.

[0053] The present invention will be described in more detail below with reference to examples. However, it should be understood that the following examples do not limit the scope of the present invention, but are merely intended to aid in the understanding of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0054] <Example 1: Manufacture of a two-terminal tandem solar cell element> First, a silicon layer doped with p-type impurities is doped with n-type impurities through a POCl process. ++ A passivation layer was formed under the PERC structure cell with the emitter layer formed, and an Al paste was printed to form a silicon lower cell. The lower surface of the silicon lower cell was textured so that the surface pyramid angle was greater than 30° and less than 60°, with an average pyramid angle of 46°.

[0055] Thereafter, an ITO (Indium Tin Oxide) layer was formed to a thickness of 20 nm on the emitter layer as a connection layer, which is a recombination layer.

[0056] A hole transport layer was then formed on the recombination layer by sputtering NiOx to a thickness of approximately 20 nm under high vacuum conditions. A perovskite absorption layer with a band gap of 1.66 eV and a thickness of 1,000 nm was then formed through a perovskite solution spin-coating process. An electron transport layer of approximately 20 nm was then formed using a thermal evaporator and ALD equipment. A transparent electrode layer of IZO (indium-doped zinc oxide) was then formed on the electron transport layer using sputtering equipment to a thickness of approximately 80 nm. An anti-reflective coating was then formed using a thermal evaporator, and a patterned silver (Ag) second grid electrode was then formed using a thermal evaporator to form a perovskite upper cell, resulting in a two-terminal bifacial silicon / perovskite tandem solar cell.

[0057] <Example 2> A two-terminal bifacial silicon / perovskite tandem solar cell was manufactured by the same procedure as in Example 1, except that the thickness of the perovskite absorption layer was changed to 1,600 nm.

[0058] <Comparative Example 1> The same procedure as in Example 1 was carried out, but instead of forming a first grid electrode on the silicon lower cell, a conventional single-facial silicon / perovskite tandem solar cell was fabricated by forming a lower electrode and using the lower electrode as the front electrode.

[0059] <Comparative Example 2> A two-terminal bifacial silicon / perovskite tandem solar cell was manufactured by the same procedure as in Example 1, except that the thickness of the perovskite absorption layer was changed to 600 nm.

[0060] <Experimental Example 1> For Example 1, Example 2, Comparative Example 1, and Comparative Example 2, the current value and the current value depending on the bottom light irradiation rate were calculated under the condition of irradiating the front with light of the AM1.5G optical spectrum in an optical simulation, and the results are shown in Figure 3.

[0061] As a result, as shown in Figure 3, in the case of Comparative Example 1, a conventional single-sided silicon / perovskite tandem solar cell, the output was 19.95 mA / cm when illuminated from the front. 2 In the case of Example 1, which is a bifacial silicon / perovskite tandem solar cell (perovskite light absorption layer thickness 1,000 nm), the current is 18.49 mA / cm when there is no bottom light irradiation. 2 When the bottom light irradiation rate was 10% or more, the current value was 20.22 mA / cm 2 At a significantly higher current value and a lower light irradiation rate of 20% or more, the current was approximately 21.11 mA / cm 2 It can be seen that the current value is significantly higher than that of the conventional ion implantation.

[0062] In addition, in the case of Example 2 (perovskite light absorption layer thickness 1,600 nm), when there is no bottom light irradiation, the current is 18.04 mA / cm 2 When the bottom light irradiation rate is 10%, the current value is 19.87mA / cm 2 When the bottom light irradiation rate was 20% or more, the current value was 21.66 mA / cm 2 It can be seen that the current value is remarkably high.

[0063] In the case of Comparative Example 2, which is a bifacial silicon / perovskite tandem solar cell with a perovskite light absorption layer thickness of 600 nm, the current was 19.50 mA / cm when there was no bottom light irradiation. 2 Even when the bottom light irradiation rate is 10% or more, the current value is 19.99mA / cm 2 The current value was similar to that of Comparative Example 1 and significantly lower than that of Example 1. This is because in the case of Comparative Example 2, in which the thickness of the perovskite light absorption layer is 600 nm, even if the current of the lower cell increases, the current of the upper cell is limited and current matching is performed, which is why the increase in current value is small despite the increase in the lower light irradiation rate.

[0064] Example 3 A two-terminal bifacial silicon / perovskite tandem solar cell was manufactured in the same manner as in Example 1, except that the band gap of the perovskite absorption layer was changed to 1.63 eV.

[0065] Example 4 A two-terminal bifacial silicon / perovskite tandem solar cell was manufactured in the same manner as in Example 1, except that the band gap of the perovskite absorption layer was changed to 1.60 eV.

[0066] <Experimental Example 2> For Examples 1, 3, and 4, the current values ​​depending on the bottom light irradiation rate were calculated in an optical simulation under the condition that light of the AM1.5G optical spectrum was irradiated onto the front surface, and the results are shown in Figure 4 (Comparative Example 1 is shown as a control group).

[0067] As a result, as shown in FIG. 4, Example 3, in which the band gap of the perovskite absorption layer is 1.63 eV, exhibits a higher current value than Comparative Example 1 when the bottom light irradiation rate is 15% or more, and when the bottom light irradiation rate is 30% or more, it exhibits a current value of about 22.05 mA / cm 2 A significantly high current value of .

[0068] Furthermore, Example 4, in which the band gap of the perovskite absorption layer is 1.60 eV, exhibits a current value equal to or greater than that of Comparative Example 1 when the bottom light irradiation rate is 20% or more, and when the bottom light irradiation rate is 40% or more, it exhibits a current value of approximately 22.99 mA / cm 2 The current value was significantly higher than that of the ion implantation.

[0069] <Example 1-1> The two-terminal bifacial silicon / perovskite tandem solar cell of Example 1 was used (the surface pyramid angle on the lower surface of the silicon lower cell was greater than 30° and less than or equal to 60°, with an average pyramid angle of 46°).

[0070] <Example 1-2> A two-terminal bifacial silicon / perovskite tandem solar cell was manufactured by carrying out the same procedure as in Example 1-1, except that the surface pyramid angle on the lower surface of the silicon lower cell was changed to be greater than 5° and less than 30°, with an average pyramid angle of 18°.

[0071] <Examples 1-3> A two-terminal bifacial silicon / perovskite tandem solar cell was manufactured in the same manner as in Example 1-1, except that the surface pyramid angle on the lower surface of the silicon lower cell was changed to 0° to 5°, with an average pyramid angle of 3°.

[0072] <Example 3-1> The two-terminal bifacial silicon / perovskite tandem solar cell of Example 3 was used (the surface pyramid angle on the lower surface of the silicon lower cell was greater than 30° and less than or equal to 60°, with an average pyramid angle of 46°).

[0073] <Example 3-2> A two-terminal bifacial silicon / perovskite tandem solar cell was manufactured by carrying out the same procedure as in Example 3-1, except that the surface pyramid angle on the lower surface of the silicon lower cell was changed to be greater than 5° and less than 30°, with an average pyramid angle of 18°.

[0074] <Example 3-3> A two-terminal bifacial silicon / perovskite tandem solar cell was manufactured by the same procedure as in Example 3-1, except that the surface pyramid angle on the lower surface of the silicon lower cell was changed to 0° to 5°, with an average pyramid angle of 3°.

[0075] <Example 4-1> The two-terminal bifacial silicon / perovskite tandem solar cell of Example 4 was used (the surface pyramid angle on the lower surface of the silicon lower cell was greater than 30° and less than or equal to 60°, with an average pyramid angle of 46°).

[0076] <Example 4-2> A two-terminal bifacial silicon / perovskite tandem solar cell was manufactured by the same procedure as in Example 4-1, except that the surface pyramid angle on the lower surface of the silicon lower cell was changed to be greater than 5° and less than 30°, with an average pyramid angle of 18°.

[0077] <Example 4-3> A two-terminal bifacial silicon / perovskite tandem solar cell was manufactured in the same manner as in Example 4-1, except that the surface pyramid angle on the lower surface of the silicon lower cell was changed to 0° to 5°, with an average pyramid angle of 3°.

[0078] <Experimental Example 3> For Examples 1-1 to 1-3, Examples 3-1 to 3-3, and Examples 4-1 to 4-3, the current values ​​depending on the lower light irradiation rate were calculated in an optical simulation under the condition that light of the AM1.5G optical spectrum was irradiated onto the front surface, and the results are shown in Figure 5 (Comparative Example 1 is shown as a control group).

[0079] As a result, the difference in current value due to the lower surface texturing shape differed depending on the band gap of the perovskite absorption layer and the lower light irradiation rate, and the lower the band gap, the more significant the difference in current value due to the lower surface texturing shape as the lower light irradiation rate increased.

[0080] In Examples 4-1 to 4-3, when the lower light irradiation rate was 20%, the difference in current value due to the lower surface texturing shape began to become apparent, and when the lower light irradiation rate was 30%, the difference in current value due to the lower surface texturing shape was the largest. At this time, the current value of Example 4-1 was about 0.54 mA / cm compared to Example 4-3. 2 A high current value was observed.

[0081] <Examples 5 to 7> Two-terminal bifacial silicon / perovskite tandem solar cells were fabricated in the same manner as in Example 1, except that the thicknesses of the perovskite absorption layers were changed to 700 nm, 800 nm, and 900 nm, respectively.

[0082] <Experimental Example 4> For Examples 5 to 7, a current value was calculated according to a bottom light irradiation rate under the condition that light of the AM1.5G optical spectrum was irradiated onto the front surface in an optical simulation using a solar simulator (not shown).

[0083] As a result, Example 5, in which the thickness of the perovskite absorption layer was 700 nm, had a light irradiance of 20.5 mA / cm when the light irradiance on the rear surface was 20% or more. 2 In Example 6, where the thickness of the perovskite absorption layer is 800 nm, the current value is 20.8 mA / cm when the light irradiation rate on the rear surface is 20% or more. 2 In Example 5, where the thickness of the perovskite absorption layer is 900 nm, the current value is 21 mA / cm when the light irradiation rate on the rear surface is 20% or more. 2 The current value was shown.

[0084] Although one embodiment of the present invention has been described above, the concept of the present invention is not limited to the examples presented in this specification, and a person skilled in the art who understands the concept of the present invention can easily propose other examples by adding, changing, deleting, or adding components within the scope of the same concept, which can also be said to fall within the scope of the concept of the present invention.

[0085] <Cell assignment> -Remaining execution time: Third year: 2021.01.01~2022.12.31 4th year: 2023.01.01~2023.09.30 [National research and development project that supported this invention] [Project unique number]1415174234 [Project number] 20203040010320 [Department name] Ministry of Trade, Industry and Energy of Korea [Name of issue management (specialized organization)] Korea Energy Technology Evaluation Institute [Research Project Name] Core Technology Development for New Renewable Energy [Research title] Development of manufacturing technology for 6-inch perovskite / crystalline silicon tandem solar cells with 26% efficiency to increase power generation [Contribution rate] 1 / 2 [Name of organization performing the task] Hanwha Solutions Co., Ltd. [Research Period] 2022.01.01~2022.12.31 <Module assignments> -Remaining execution time: Second year: 2022.05.01~2022.12.31 Third year: 2023.01.01~2023.12.31 4th year: 2024.01.01~2024.10.30 [National research and development project that supported this invention] [Project unique number]1415176482 [Project number] 20213030010400 [Department name] Ministry of Trade, Industry and Energy of Korea [Name of issue management (specialized organization)] Korea Energy Technology Evaluation Institute [Research Project Name] New Renewable Energy Core Technology Development (R&D) [Research topic] Development of process technology for highly efficient and durable perovskite / crystalline silicon tandem solar modules [Contribution rate] 1 / 2 [Name of organization performing the task] Hanwha Solutions Co., Ltd. [Research Period] 2022.05.01~2022.12.31

Claims

1. a silicon lower cell including a silicon layer and a first grid electrode disposed on a lower surface of the silicon layer; a perovskite top cell comprising a perovskite absorber layer having a thickness of greater than 600 nm to 2,000 nm; a connecting layer connecting the silicon bottom cell and the perovskite top cell.

2. 2. The bifacial silicon / perovskite tandem solar cell of claim 1, wherein the perovskite absorber layer has a thickness of 650 nm to 1,700 nm.

3. 10. The bifacial silicon / perovskite tandem solar cell of claim 1, wherein the perovskite top cell has a bandgap of less than 1.66 eV.

4. The silicon bottom cell comprises: further comprising a passivation layer on a lower surface of the silicon layer; 2. The bifacial silicon / perovskite tandem solar cell of claim 1, wherein the first grid electrode is disposed on the passivation layer.

5. the silicon layer is a p-type silicon layer, 10. The bifacial silicon / perovskite tandem solar cell of claim 1, further comprising an n-type emitter layer on a top surface of the silicon layer.

6. The tie layer is 2. The bifacial silicon / perovskite tandem solar cell of claim 1, wherein the recombination layer or intermediate layer comprises at least one selected from the group consisting of transparent conductive oxides, carbonaceous conductive materials, metallic materials, and conductive polymers.

7. 2. The bifacial silicon / perovskite tandem solar cell of claim 1, wherein the silicon lower cell has one structure selected from the group consisting of Al-BSF, PERC, PERT, PERL, and TOPCon structures.

8. When the connection layer is a recombination layer, the bifacial silicon / perovskite tandem solar cell is a two-terminal bifacial silicon / perovskite tandem solar cell, in which the perovskite upper cell further includes a second grid electrode on an upper side of the perovskite absorber layer; 7. The bifacial silicon / perovskite tandem solar cell of claim 6, wherein when the connection layer is an intermediate layer, the bifacial silicon / perovskite tandem solar cell is a four-terminal bifacial silicon / perovskite tandem solar cell, in which the silicon lower cell further includes a second grid electrode on top of the silicon layer, the second grid electrode being partially embedded in the intermediate layer.

9. At least a portion of the lower surface of the silicon lower cell is formed with pyramidal irregularities, 2. The bifacial silicon / perovskite tandem solar cell of claim 1, wherein the pyramidal asperities have a pyramidal angle of more than 5°.

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