Micro-nano spherical light trapping structure for solar cell and preparation method of micro-nano spherical light trapping structure

Abstract

The invention belongs to the field of solar cells, and provides a micro-nano spherical light trapping structure for a solar cell and a preparation method of the micro-nano spherical light trapping structure. The solar cell is characterized in that the size, spacing, distribution density, distribution position and the like of the micro-nano spherical structure can be selected according to the type of the solar cell; materials of the structure can be but not limited to polymers, metal oxides and the like. The structure is located at one or more positions in the light absorption layer or on the upper surface or the lower surface and the like; the structure can adopt one or more of a spin-coating method, a self-assembly method, a spraying method and the like for mixed deposition; the light trapping structure is simple in preparation process, the specific spectral band absorption capacity of the solar cell can be improved, and the light current density of the device is improved.

Description

Technical Field

[0001] The present invention belongs to the field of perovskite solar cells, and particularly relates to a micro-nano spherical light-trapping structure for solar cells and a preparation method thereof. Background Art

[0002] In the process of the continuous evolution of solar cell technology, the power conversion efficiency (PCE) of single-junction solar cells has shown a rapid growth trend and has quickly jumped to 27.0%, which is very close to the theoretical limit value. Looking back on previous studies, researchers generally regarded improving the open-circuit voltage (V oc ) and fill factor (FF) as the core points for preparing high-efficiency solar cells. With the improvement of passivation technology and the development of component engineering, the number of defects inside the light-absorbing layer of solar cells has been significantly reduced. This significant improvement effectively suppresses the loss of V oc and FF, and strongly promotes the improvement of the performance of solar cells. However, with the continuous optimization of V oc and FF, the PCE gradually approaches the Shockley-Queisser (S-Q) theoretical limit. This trend has prompted researchers to re-examine the potential factors restricting the efficiency improvement of perovskite solar cells. Among them, the further increase of the short-circuit current density (J sc ) has become a key problem to be solved urgently. Currently, there is still a significant gap between the actual J sc value and the theoretical limit. Especially in the edge region of the light absorption spectrum, the light absorption efficiency is low, resulting in a large amount of incident light not being fully absorbed and converted into electrical energy. To further improve the light utilization efficiency of the light-absorbing layer and ensure the efficient transmission and extraction of carriers, introducing an optimized optical management strategy has become an urgent need in this field. Among many optical management strategies, using micro-nano spheres to construct a light-trapping structure is an effective means. Micro-nano spheres can enhance the interaction between light and materials by scattering light, reflecting light, etc., thereby increasing J sc , and finally realizing the optimized improvement of the efficiency of solar cell devices. Summary of the Invention

[0003] The present invention aims to promote the light absorption of solar cells so as to further increase the J sc and PCE of the device, and proposes a micro-nano spherical light-trapping structure for solar cells and a preparation method thereof. By embedding micro-nano spheres between different functional layers, the light transmission path in the solar cell is extended and the carrier transmission between different functional layers is assisted, which can effectively increase the J scand PCE. Among them, the size of the micro-nano spheres can be selected as any size according to the type of solar cell and the different material bandgaps, including but not limited to any size from 5 nanometers (nm) to 10 micrometers (μm) in diameter, preferably in the range of 20 nm to 5 μm, and more preferably in the range of 50 nm to 2 μm; the arrangement of the micro-nano spheres can be any one, including but not limited to at least one of regular arrangement, random arrangement, etc.; the spacing of the micro-nano spheres can be selected as any spacing according to the type of solar cell, the particle size of the micro-nano spheres, and the position where the spheres are located, including but not limited to 0 to 50 μm, preferably in the range of 0 to 10 μm, and more preferably in the range of 0 to 2 μm; the density of the micro-nano spheres can be selected as any density according to the type of solar cell, the particle size of the micro-nano spheres, and the position where the spheres are located, including but not limited to 1 to 10 13 per square centimeter (per cm 2 ²), preferably in the range of 10 4 ~10 12 per cm 2 ², and more preferably in the range of 10 6 ~10 10 per cm 2 ²; the material of the micro-nano spheres can be any one, including but not limited to at least one of various materials such as polymers, metal oxides, etc.; the positions of the micro-nano spheres include but not limited to one or more of the upper and lower surfaces of the functional layer, the upper and lower surfaces of the light absorption layer, etc.; the manufacturing method of the light trapping structure of the micro-nano spheres can be selected as any method, including but not limited to one or a mixture of deposition methods such as spin coating, self-assembly, spraying method, etc. This light trapping structure can be applied to any solar cell, including but not limited to silicon solar cells, copper indium gallium selenide solar cells, organic solar cells, copper zinc tin sulfide solar cells, copper zinc tin sulfide selenide solar cells, dye-sensitized solar cells, perovskite solar cells, multi-junction stacked solar cells such as perovskite / silicon or perovskite / perovskite; this light trapping structure can be applied to any optoelectronic device, including but not limited to optoelectronic devices such as solar cells, light-emitting diodes, photodetectors, lasers, field-effect transistors, resistive memories, etc.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A micro-nano spherical light trapping structure for a solar cell and a preparation method thereof, characterized in that the solar cell structure includes: 1) a substrate; 2) a first electrode; 3) a first functional layer; 4) a micro-nano sphere light trapping layer; 5) a light absorption layer; 6) a light absorption material modification layer; 7) a second functional layer; 8) a second electrode. The substrate is made of glass, metal, silicon wafer, fiber fabric, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyimide (PI), polydimethylsiloxane (PDMS) and its derivatives, flexible or rigid substrates, having transparent or opaque characteristics, and also having conductive or non-conductive characteristics. The electrode is made of at least one of Au, Ag, Al, Cu, Ti metals or transparent conductive films of indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), indium-doped zinc oxide (IZO), fluorine-doped tin oxide (FTO), metal and oxide mixed electrodes and carbon material electrodes; the first electrode and the second electrode can be the same material or different materials, and the thickness includes but is not limited to 10 nm to 50 μm., the preferred range is 50 nm to 2 μm, and the more preferred range is 100 nm to 1 μm. The first functional layer and the second functional layer serve as an electron transport layer and a hole transport layer respectively, and can be interchanged; when serving as an electron transport layer, at least one of titanium dioxide (TiO2), tin dioxide (SnO2), zinc oxide (ZnO), fullerene derivatives (such as PCBM), graphene zinc oxide tin, metal phthalocyanine molecular materials and N-type self-assembled monolayer materials (such as 4-PA) is used, and the thickness includes but is not limited to 0.1 nm to 500 nm, the preferred range is 2 nm to 100 nm, and the more preferred range is 10 nm to 50 nm; when serving as a hole transport layer, nickel oxide (NiO x )), molybdenum oxide (MoO x ), tungsten oxide (WO x) and at least one of vanadium pentoxide (V2Ox), cuprous oxide (Cu2O), copper oxide (CuO), copper thiocyanate, cuprous iodide, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), and P-type self-assembled monolayer materials (such as hole transport materials based on phosphine carbazole groups or triphenylamine groups like 4PACz, 2PACz, Me-4PACz, Me-2PACz, MeO-4PACz, MeO-2PACz), the thickness including but not limited to 0.1 nm to 500 nm, preferably in the range of 2 nm to 100 nm, more preferably in the range of 10 nm to 50 nm. The micro-nano sphere light trapping layer is a light trapping structure made of micro-nano spheres, and its function is to extend the light transmission path in the solar cell and enhance the interaction between light and materials by means of scattering light, reflecting light, etc. The size of the micro-nano spheres can be selected as any size according to the type of solar cell and the band gap of the material, including but not limited to a diameter of 5 nm to 10 μm, preferably in the range of 20 nm to 5 μm, more preferably in the range of 50 nm to 2 μm; the arrangement of the micro-nano spheres can be any one, including but not limited to at least one of regular arrangement, random arrangement, etc.; the spacing between the micro-nano spheres can be selected as any spacing according to the type of solar cell, the particle size of the micro-nano spheres, and the position where the spheres are located, including but not limited to 0 to 50 μm, preferably in the range of 0 to 10 μm, more preferably in the range of 0 to 2 μm; the density of the micro-nano spheres can be selected as any density according to the type of solar cell, the particle size of the micro-nano spheres, and the position where the spheres are located, including but not limited to 1 to 10 13 per cm 2 , preferably in the range of 10 4 ~10 12 per cm 2 , more preferably in the range of 10 6 ~10 10 per cm 2; The material of the micro-nano spheres can be, but is not limited to, at least one of various materials such as polymers, metal oxides, etc.; The positions of the micro-nano spheres include, but are not limited to, one or more positions among the upper and lower surfaces of the functional layer, the upper and lower surfaces of the light absorption layer, etc.; The light absorption layer can be any material that absorbs light and can generate freely moving carriers, and can be one or more combinations of organic, inorganic, or organic-inorganic hybrid materials, such as silicon materials (amorphous silicon, polycrystalline silicon, or single crystal silicon), organic semiconductor materials (such as pentacene, triphenylamine, fullerene, phthalocyanine, perylene derivatives, and cyanine small molecule materials, or polyacetylene-type, polyaromatic-ring-type, and copolymer-type polymer materials, where the polyaromatic-ring-type includes polyphenylene, polythiophene, polyaniline, polypyrrole polymer materials), compound materials (CIGS, AgBiS2, GaAs, GaAlAs, InP, CdS, CdTe, CZTS, metal halide perovskites); Taking hybrid perovskite materials as an example, it includes, but is not limited to, polycrystalline and single-crystalline organic-inorganic hybrid perovskite materials, where the A-site cation is at least one of lithium, sodium, potassium, rubidium, cesium, amino, amidinium, guanidinium compounds, the B-site cation is Pb 2+ , Sn 2+ , Ge 2+ , Sb 2+ , Bi 3+ distributed in at least one of the fourth, fifth, and sixth main group elements or Ag + , Cu 2+ distributed in at least one of the first subgroup elements, and the X-site anion is SCN - , BF4 - , I - , Cl - , Br - at least one of the elements, and the thickness of the light absorption layer can be, but is not limited to, 5 nm to 500 μm, preferably in the range of 50 nm to 400 μm, and more preferably in the range of 100 nm to 300 μm; The modification layer of the light absorption material can be any material that can reduce the defects of the light absorption material and improve the generation and transport of photo-generated carriers, including phenyltriethylammonium iodide (PEAI), 4-methoxyphenethylammonium iodide (MeO-PEAI), ethylenediaminetetraacetic acid (EDTA), choline chloride, polymethyl methacrylate (PMMA), alkanes with -SH, -OH, -CN, -COOH, -NH2, -SCN, -halide ion terminal functional groups, pyridine, fullerene, aromatic hydrocarbons, organic halides, graphene compounds and their derivatives, at least one of them, and SiO2, SiN x , a-Si:H, Al2O3, a-SiO x:At least one of inorganic materials such as H, PbSO4, PbS, PbO, and Pb(OH)2, the thickness including but not limited to 1 nm to 500 nm, preferably in the range of 1 nm to 200 nm, and more preferably in the range of 5 nm to 50 nm.

[0006] The above-mentioned micro-nano spherical light trapping structure for solar cells is characterized in that the process of applying the micro-nano spherical light trapping structure to a solar cell is as follows: 1) Simulate the optimal geometric parameters and distribution spacing of the corresponding structure; 2) Clean the substrate; 3) Prepare a thin film electrode on the substrate surface; 4) Prepare a first functional layer on the thin film electrode; 5) Prepare a micro-nano spherical dispersion; 6) According to the optimal parameters simulated, prepare a micro-nano spherical light trapping layer on the first functional layer; 7) Prepare a polycrystalline or single-crystalline light absorption layer; 8) Prepare a modification layer of the light absorption layer; 9) Prepare a second functional layer; 10) Prepare a second electrode. Among them, functional layers such as the electrode, electron and hole transport layers, light absorption layer, modification layer of the light absorption material, and light trapping layer can be deposited on the substrate by various methods, including but not limited to at least one of thermal evaporation, spin coating, blade coating, roll coating, magnetron sputtering, atomic layer deposition, slot die coating, screen printing, inkjet printing, thermal oxidation, imprinting, etching methods; the micro-nano spherical light trapping structure can be prepared by various methods, including but not limited to one or a combination of spin coating, self-assembly, spraying methods. Among them, the solvent for dispersing the micro-nano spheres can be selected from any solvent according to the material properties and surface properties of the micro-nano spheres, including but not limited to at least one of water (H2O), ethanol (EtOH), isopropanol (IPA), chlorobenzene (CB), toluene, N,N-dimethylformamide (DMF), methanol (MeOH), acetone (Me2CO), ethylene glycol (EG), acetonitrile (ACN), n-hexane, cyclohexane (CyH), carbon tetrachloride (CTC), dimethyl sulfoxide (DMSO), hexafluoroisopropanol (HFIP), ionic liquids; the concentration of the micro-nano spherical dispersion can be selected from any concentration according to different uses, the characteristics of the micro-nano spheres, and the properties of the dispersion, including but not limited to a concentration of 0.5 to 50 mg / mL, preferably in the range of 1 to 20 mg / mL, and more preferably in the range of 1 to 10 mg / mL.

[0007] The beneficial effects of the present invention are as follows: By depositing micro-nano spheres between different layers of a solar cell to fabricate a light-trapping structure, the optical path can be effectively increased, the contact between light and the light-absorbing layer can be enlarged, light scattering can be enhanced, charge separation and transport can be promoted, thereby improving the absorption and utilization of light by the light-absorbing layer, reducing light loss, and ultimately increasing the short-circuit current density and device efficiency of the solar cell. The principle lies in that the existence of the light-trapping structure extends the propagation path of light in the perovskite thin film, and expands the distribution range of light in the light-absorbing layer through mechanisms such as enhanced light scattering, standing wave effect, and surface plasmon resonance, thereby improving the utilization rate of light by the light-absorbing layer and effectively reducing the loss of short-circuit current density. This structure significantly improves both the optical and electrical properties of the solar cell, and the improvement effect is more obvious when the light-absorbing layer is relatively thin. In addition, this light-trapping structure can be applied to any solar cell, including but not limited to silicon solar cells, copper indium gallium selenide solar cells, organic solar cells, copper zinc tin sulfide solar cells, copper zinc tin sulfide selenide solar cells, dye-sensitized solar cells, perovskite solar cells, perovskite / silicon or perovskite / perovskite multi-junction stacked solar cells. This light-trapping structure can also be applied to a variety of optoelectronic devices, including but not limited to solar cells, light-emitting diodes, photodetectors, lasers, field-effect transistors, resistive memories, etc., and has broad application prospects. Description of the Drawings

[0009] Figure 1 is a schematic diagram showing the random distribution of the micro-nano spheres of the present invention on the substrate;

[0010] Figure 2 is a schematic diagram comparing the device efficiencies before and after depositing the micro-nano spheres in Specific Embodiment 1 of the present invention;

[0011] Figure 3 is a schematic diagram comparing the short-circuit current densities of the devices before and after depositing the micro-nano spheres in Specific Embodiment 1 of the present invention;

[0012] Figure 4 is a schematic diagram comparing the steady-state fluorescence spectra of the light-absorbing layer thin films before and after depositing the micro-nano spheres in Specific Embodiment 1 of the present invention;

[0013] Figure 5 is a schematic diagram of the device structure for depositing micro-nano spheres on the first functional layer in Specific Embodiment 1 of the present invention;

[0014] Figure 6 is a schematic diagram of the device structure for depositing micro-nano spheres on the light-absorbing material modification layer in Specific Embodiment 3 of the present invention;

[0015] Figure 7 is a schematic diagram of the device structure for depositing micro-nano spheres on the light-absorbing layer in Specific Embodiment 5 of the present invention. Detailed Embodiments

[0017] To make the technical solutions and advantages of the present invention clearer, the following further elaborates on the technical solutions of the present invention in detail in conjunction with the accompanying drawings and specific embodiments. However, the described embodiments are only a part of all possible embodiments of the present invention and are not limited thereto.

[0018] A micro-nano spherical light-trapping structure for a solar cell and a preparation method thereof, characterized in that the preparation sequence of the battery is successively: 1) cleaning the substrate; 2) preparing the first electrode; 3) preparing the first functional layer; 4) preparing the micro-nano spherical light-trapping structure; 5) preparing the light absorption layer; 6) preparing the modification layer of the light absorption layer; 9) preparing the second functional layer; 10) preparing the second electrode.

[0019] Example 1

[0020] 1. Use FTO / glass as the substrate and perform ultrasonic cleaning on it with a cleaning agent, deionized water, acetone, and isopropanol.

[0021] 2. Prepare the electron transport layer by the method of chemical bath deposition (CBD) of tin oxide.

[0022] 3. Spin-coat micro-nano spheres on the SnO2 transport layer. The solution concentration is 1 - 6 mg / mL, the solvent is DMF and DMSO, and spin-coat at a speed of 2000 - 4000 rpm for 30 - 40 s, and then anneal at 100 - 150 °C for 10 - 15 min, as Figure 5 shown.

[0023] 4. On the SnO2 transport layer deposited with micro-nano spheres, prepare the perovskite absorption layer by a two-step spin-coating method. First, spin-coat the lead iodide (PbI2) solution at a speed of 1500 - 1700 rpm for 30 - 40 s and anneal at 70 - 80 °C for 1 - 2 min. Then, drop the organic salt solution on the PbI2 layer, spin-coat at a speed of 1800 - 2000 rpm for 30 - 40 s and anneal at 120 - 150 °C for 10 - 15 min to obtain the perovskite absorption layer.

[0024] 5. Prepare the MeO-PEAI passivation layer on the perovskite absorption layer. The solution concentration is 1 - 5 mg / mL, the solvent is IPA, and spin-coat at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0025] 6. Prepare the Spiro-OMeTAD hole transport layer on the passivation layer and spin-coat the Spiro-OMeTAD solution at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0026] 7. Deposit 80 - 100 nm of Ag as the metal electrode.

[0027] 8. The device efficiency before and after depositing the micro - nano spheres is compared as Figure 2 shown. The highest efficiency of the perovskite solar cell after depositing the micro - nano spheres is 23.29%. The specific parameters are: short - circuit current: 25.28 mA / cm 2 , open - circuit voltage: 1.15 V, fill factor: 79.83%.

[0028] 9. The short - circuit current density before and after depositing the micro - nano spheres is compared as Figure 3 shown.

[0029] 10. The steady - state photoluminescence spectra before and after depositing the micro - nano spheres are as Figure 4 shown, and an obviously increased photoluminescence intensity can be seen.

[0030] Example 2

[0031] 1. Use FTO / glass as the substrate and ultrasonically clean it with a cleaning agent, deionized water, acetone, ethanol, and isopropanol.

[0032] 2. Prepare the electron transport layer by the CBD tin oxide method.

[0033] 3. Spin - coat micro - nano spheres on the SnO2 transport layer. The solution concentration is 1 - 6 mg / mL, the solvent is DMF and DMSO, and spin - coat at a speed of 2000 - 4000 rpm for 30 - 40 s, then anneal at 100 - 150 °C for 10 - 15 min.

[0034] 4. On the SnO2 transport layer deposited with micro - nano spheres, prepare the perovskite absorption layer by the one - step spin - coating method. Spin - coat the formamidinium lead iodide (FAPbI3) solution at a speed of 7000 - 8000 rpm for 40 - 50 s, add 170 - 200 μL of anisole as the anti - solvent, and then anneal at 120 - 150 °C for 10 - 15 min to obtain the perovskite thin film.

[0035] 5. Prepare the MeO - PEAI passivation layer on the perovskite absorption layer. The solution concentration is 1 - 5 mg / mL, the solvent is IPA, and spin - coat at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0036] 6. Prepare the Spiro - OMeTAD hole transport layer on the passivation layer and spin - coat the Spiro - OMeTAD solution at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0037] 7. Deposit 80 - 100 nm Ag as the metal electrode.

[0038] Example 3

[0039] 1. Use FTO / glass as the substrate and ultrasonically clean it with a cleaning agent, deionized water, acetone, and isopropanol.

[0040] 2. Prepare the electron transport layer by the CBD tin oxide method.

[0041] 3. On the SnO2 transport layer, prepare the perovskite absorption layer by a two-step spin-coating method. First, spin-coat the PbI2 solution at a speed of 1500 - 1700 rpm for 30 - 40 s and anneal it at 70 - 80 °C for 1 - 2 min. Then, drop the organic salt solution on the PbI2 layer, spin-coat it at a speed of 1800 - 2000 rpm for 30 - 40 s and anneal it at 120 - 150 °C for 10 - 15 min to obtain the perovskite absorption layer.

[0042] 4. Prepare the MeO-PEAI passivation layer on the perovskite absorption layer. The solution concentration is 1 - 5 mg / mL, the solvent is IPA, and it is spin-coated at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0043] 5. Spin-coat micro-nano spheres on the MeO-PEAI passivation layer. The solution concentration is 1 - 6 mg / mL, the solvent is CB or IPA, and it is spin-coated at a speed of 2000 - 4000 rpm for 30 - 40 s, as Figure 6 shown.

[0044] 6. Prepare the Spiro-OMeTAD hole transport layer on the passivation layer with micro-nano spheres and spin-coat the Spiro-OMeTAD solution at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0045] 7. Deposit 80 - 100 nm Ag as the metal electrode.

[0046] Example 4

[0047] 1. Use FTO / glass as the substrate and ultrasonically clean it with a cleaning agent, deionized water, acetone, and isopropanol.

[0048] 2. Prepare the electron transport layer by the CBD tin oxide method.

[0049] 3. On the SnO2 transport layer, a perovskite absorption layer is prepared by a one-step spin-coating method. The FAPbI3 solution is spin-coated at a speed of 7000 - 8000 rpm for 40 - 50 s, 170 - 200 μL of anisole is added dropwise as an anti-solvent, and then annealed at 120 - 150 °C for 10 - 15 min to obtain the perovskite absorption layer.

[0050] 4. A MeO-PEAI passivation layer is prepared on the perovskite absorption layer. The solution concentration is 1 - 5 mg / mL, the solvent is IPA, and it is spin-coated at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0051] 5. Micro-nano spheres are spin-coated on the MeO-PEAI passivation layer. The solution concentration is 1 - 6 mg / mL, the solvent is CB or IPA, and it is spin-coated at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0052] 6. A Spiro-OMeTAD hole transport layer is prepared on the passivation layer with micro-nano spheres, and the Spiro-OMeTAD solution is spin-coated at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0053] 7. 80 - 100 nm of Ag is deposited as the metal electrode.

[0054] Example 5

[0055] 1. FTO / glass is used as the substrate and ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropyl alcohol.

[0056] 2. An electron transport layer is prepared by the CBD tin oxide method.

[0057] 3. On the SnO2 transport layer, a perovskite absorption layer is prepared by a two-step spin-coating method. First, the PbI2 solution is spin-coated at a speed of 1500 - 1700 rpm for 30 - 40 s and annealed at 70 - 80 °C for 1 - 2 min. Then, the organic salt solution is added dropwise on the PbI2 layer, spin-coated at a speed of 1800 - 2000 rpm for 30 - 40 s and annealed at 120 - 150 °C to obtain the perovskite absorption layer.

[0058] 4. Micro-nano spheres are spin-coated on the perovskite absorption layer. The solution concentration is 1 - 6 mg / ml, the solvent is CB or IPA, and it is spin-coated at a speed of 2000 - 4000 rpm for 30 - 40 s, as Figure 7 shown.

[0059] 5. Prepare a MeO-PEAI passivation layer on the perovskite absorption layer with micro-nano spheres. The solution concentration is 1 - 5 mg / mL, the solvent is IPA, and it is spin-coated at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0060] 6. Prepare a Spiro-OMeTAD hole transport layer on the passivation layer, and spin-coat the Spiro-OMeTAD solution at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0061] 7. Deposit 80 - 100 nm of Ag as the metal electrode.

[0062] Example 6

[0063] 1. Use FTO / glass as the substrate and ultrasonically clean it with a cleaning agent, deionized water, acetone, and isopropyl alcohol.

[0064] 2. Prepare the electron transport layer by the CBD tin oxide method.

[0065] 3. On the SnO2 transport layer, prepare the perovskite absorption layer by the one-step spin-coating method. Spin-coat the FAPbI3 solution at a speed of 7000 - 8000 rpm for 40 - 50 s, add 170 - 200 μL of anisole as the antisolvent, and then anneal it at 120 - 150 °C for 10 - 15 min to obtain the perovskite absorption layer.

[0066] 4. Spin-coat micro-nano spheres on the perovskite absorption layer. The solution concentration is 1 - 6 mg / mL, the solvent is CB or IPA, and it is spin-coated at a speed of 2000 - 4000 rpm for 30 - 40 s.

[0067] 5. Prepare a MeO-PEAI passivation layer on the perovskite absorption layer with micro-nano spheres. The solution concentration is 1 - 5 mg / mL, the solvent is IPA, and it is spin-coated at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0068] 6. Prepare a Spiro-OMeTAD hole transport layer on the passivation layer, and spin-coat the Spiro-OMeTAD solution at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0069] 7. Deposit 80 - 100 nm of Ag as the metal electrode.

[0070] As described above, it is only the preferred specific embodiment of the present invention and does not limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the embodiments, for any person skilled in the technical field, he can still make changes or substitutions to the technical solutions described in the above embodiments. However, all changes made based on the design principle of the present invention and non-creative labor shall fall within the protection scope of the present invention.

Claims

1. A micro-nano spherical light trapping structure for a solar cell and a preparation method thereof, characterized in that The structure of the solar cell includes: 1) a substrate; 2) a first electrode; 3) a first functional layer; 4) a micro-nano sphere light trapping layer; 5) a light absorption layer; 6) a light absorption material modification layer; 7) a second functional layer; 8) a second electrode.

2. The micro-nano spherical light trapping structure for a solar cell and its preparation method according to claim 1, characterized in that The substrate of the solar cell is made of glass, metal, silicon wafer, fiber fabric, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyimide (PI), polydimethylsiloxane (PDMS) and its derivatives, flexible or rigid substrates, having transparent or opaque characteristics, and also having conductive or non-conductive characteristics.

3. A micro-nano spherical light trapping structure for a solar cell and a preparation method thereof according to claim 1, characterized in that The electrodes of the solar cell are made of at least one of Au, Ag, Al, Cu, Ti metals or transparent conductive films of indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), indium-doped zinc oxide (IZO), fluorine-doped tin oxide (FTO) with good conductivity, metal and oxide mixed electrodes, and carbon material electrodes; the first electrode and the second electrode can be made of the same material or different materials, and the thickness includes but is not limited to 10 nanometers to 50 micrometers, preferably in the range of 50 nanometers to 2 micrometers, and more preferably in the range of 100 nanometers to 1 micrometer.

4. A micro-nano spherical light trapping structure for a solar cell and a preparation method thereof according to claim 1, characterized in that The first functional layer and the second functional layer of the solar cell serve as an electron transport layer and a hole transport layer respectively, and their positions can be interchanged; when serving as the electron transport layer, at least one of titanium dioxide (TiO2), tin dioxide (SnO2), zinc oxide (ZnO), fullerene derivatives (such as PCBM), graphene zinc oxide tin, metal phthalocyanine molecular materials, and N-type self-assembled monolayer materials (such as 4-PA) is used, and the thickness is 0.1 nanometer to 500 nanometers; when serving as the hole transport layer, nickel oxide (NiO x ), molybdenum oxide (MoO x ), tungsten oxide (WO x ), vanadium pentoxide (V2O x ), cuprous oxide (Cu2O), copper oxide (CuO), copper thiocyanate, cuprous iodide, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), and at least one of P-type self-assembled monolayer materials (such as hole transport materials based on phosphonic carbazole groups or triphenylamine groups like 4PACz, 2PACz, Me-4PACz, Me-2PACz, MeO-4PACz, MeO-2PACz) are used, and the thickness includes but is not limited to 0.1 nanometer to 500 nanometers, the preferred range is 2 nanometers to 100 nanometers, and the more preferred range is 10 nanometers to 50 nanometers.

5. A micro-nano spherical light trapping structure for a solar cell and a preparation method thereof according to claim 1, characterized in that The size of the micro-nano spheres can be selected as any size according to the type of solar cell and the different material band gaps, including but not limited to diameters ranging from 5 nanometers to 10 micrometers, preferably in the range of 20 nanometers to 5 micrometers, and more preferably in the range of 50 nanometers to 2 micrometers; the arrangement of the micro-nano spheres can be any one, including but not limited to at least one of regular arrangement, random arrangement, etc.; the spacing between the micro-nano spheres can be selected as any spacing according to the type of solar cell, the particle size of the micro-nano spheres, and the position where the spheres are located, including but not limited to 0 to 50 micrometers, preferably in the range of 0 to 10 micrometers, and more preferably in the range of 0 to 2 micrometers; the density of the micro-nano spheres can be selected as any density according to the type of solar cell, the particle size of the micro-nano spheres, and the position where the spheres are located, including but not limited to 1 to 10 13 per square centimeter, preferably in the range of 10 4 ~10 12 per square centimeter, and more preferably in the range of 10 6 ~10 10 per square centimeter; the material of the micro-nano spheres can be but not limited to at least one of various materials such as polymers, metal oxides, etc.; the positions of the micro-nano spheres include but not limited to one or more of the upper and lower surfaces of the functional layer, the upper and lower surfaces of the light absorption layer, etc.

6. The micro-nano spherical light trapping structure for a solar cell and its preparation method according to claim 1, characterized in that The light absorption layer of a solar cell can be any material that absorbs light and generates freely moving charge carriers, which can be one or a combination of organic, inorganic, or organic-inorganic hybrid materials, such as silicon materials (amorphous silicon, polycrystalline silicon, or single-crystalline silicon), organic semiconductor materials (such as pentacene, triphenylamine, fullerene, phthalocyanine, perylene derivatives, and cyanine small molecule materials, or polyacetylene-type, polyaromatic-ring-type, and copolymer-type polymer materials, where polyaromatic-ring-type includes polymer materials such as polyphenylene, polythiophene, polyaniline, and polypyrrole), compound materials (CIGS, AgBiS2, GaAs, GaAlAs, InP, CdS, CdTe, CZTS, metal halide perovskite); taking hybrid perovskite materials as an example, it includes but is not limited to polycrystalline and single-crystalline organic-inorganic hybrid perovskite materials, where the A-site cation is at least one of lithium, sodium, potassium, rubidium, cesium, amine group, amidinium group, and guanidine group compounds, the B-site cation is Pb 2+ , Sn 2+ , Ge 2+ , Sb 2+ , Bi + distributed in at least one of the elements in the fourth, fifth, and sixth main groups or Ag + , Cu 2+ distributed in at least one of the elements in the first subgroup, and the X-site anion is SCN - , BF 4- , I - , Cl - , Br - at least one of the elements, and the thickness of the light absorption layer can be but is not limited to 5 nanometers to 500 micrometers, preferably in the range of 50 nanometers to 400 micrometers, and more preferably in the range of 100 nanometers to 300 micrometers. The modification layer of the light absorption material can be any material that can reduce the defects of the light absorption material and improve the generation and transport of photo-generated charge carriers, including at least one of phenyltriethylammonium iodide (PEAI), 4-methoxyphenethylammonium iodide (MeO-PEAI), ethylenediaminetetraacetic acid (EDTA), choline chloride, polymethyl methacrylate (PMMA), alkanes, pyridine, fullerenes, aromatic hydrocarbons, organic halides, graphene, etc. with -SH, -OH, -CN, -COOH, -NH2, -SCN, -halide ion terminal functional groups, and compounds and derivatives thereof, as well as at least one of inorganic materials such as SiO2, SiN x , a-Si:H, Al2O3, a-SiO x :H, PbSO4, PbS, PbO, Pb(OH)2, and the thickness includes but is not limited to 1 nanometer to 500 nanometers, preferably in the range of 1 nanometer to 200 nanometers, and more preferably in the range of 5 nanometers to 50 nanometers.

7. The functional layers such as the electrodes, electron and hole transport layers, light absorption layers, and light absorption material modification layers according to claims 3, 4, and 6 can be deposited on the substrate by various methods, including but not limited to at least one of thermal evaporation, spin coating, blade coating, roll coating, magnetron sputtering, atomic layer deposition, slot die coating, screen printing, inkjet printing, thermal oxidation, imprinting, etching methods.

8. The micro-nano sphere light trapping layer according to claim 5 can be deposited on the substrate by a variety of methods, including but not limited to one or a combination of methods such as spin coating, self-assembly, spraying, etc. Among them, The solvent for dispersing the micro-nano spheres can be any solvent according to the material characteristics and surface properties of the micro-nano spheres, including but not limited to at least one of water (H2O), ethanol (EtOH), isopropanol (IPA), chlorobenzene (CB), toluene, N,N-dimethylformamide (DMF), methanol (MeOH), acetone (Me2CO), ethylene glycol (EG), acetonitrile (ACN), n-hexane, cyclohexane (CyH), carbon tetrachloride (CTC), dimethyl sulfoxide (DMSO), hexafluoroisopropanol (HFIP), ionic liquids, etc.; the concentration of the micro-nano sphere dispersion can be any concentration according to different uses, the characteristics of the micro-nano spheres, and the properties of the dispersion, including but not limited to a concentration of 0.5 to 50 mg / ml, preferably in the range of 1 to 20 mg / ml, and more preferably in the range of 1 to 10 mg / ml.

9. The above-mentioned micro-nano spherical light trapping structure for solar cells and its preparation method are characterized in that The preparation process is as follows: 1) Simulate the optimal geometric parameters and distribution spacing of the corresponding structure; 2) Clean the substrate; 3) Prepare a thin-film electrode on the substrate surface; 4) Prepare a first functional layer on the thin-film electrode; 5) Prepare a micro-nano sphere dispersion; 6) According to the simulated optimal parameters, prepare a micro-nano sphere light-trapping layer on different functional layers; 7) Prepare a polycrystalline or single-crystalline light absorption layer; 8) Prepare a modification layer for the light absorption layer; 9) Prepare a second functional layer; 10) Prepare a second electrode.

10. The micro-nano spherical light trapping structure for a solar cell and its preparation method according to claim 1, characterized in that The described micro-nano sphere light-trapping structure can be applied to any solar cell, including but not limited to silicon solar cells, copper indium gallium selenide solar cells, organic solar cells, copper zinc tin sulfide solar cells, copper zinc tin sulfide selenide solar cells, dye-sensitized solar cells, perovskite solar cells, perovskite / silicon or perovskite / perovskite multi-junction stacked solar cells; the micro-nano sphere light-trapping structure can be applied to any optoelectronic device, including but not limited to optoelectronic devices such as solar cells, light-emitting diodes, photodetectors, lasers, field-effect transistors, resistive memories, etc.

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