Solar cell with grating light trapping structure and preparation method

Abstract

The invention belongs to the field of solar cells, and provides a solar cell with a grating light trapping structure and a preparation method. The grating light trapping structure is characterized in that the size, the blaze angle, the scribed line density, the depth and the like of the grating light trapping structure can be selected according to the requirement of a light trapping wave band and the thickness of the substrate; the grating structure is located at one or more of the upper and lower surfaces of the light absorption layer and the upper and lower surfaces of the functional layer; the grating structure can be prepared by adopting one or more of methods of nanoimprint lithography, laser direct writing, self-assembly, 3D printing, laser ablation and the like; the light trapping structure is simple to prepare, the spectral absorption capacity of the solar cell can be regulated and controlled, the light current density of the device is improved, and meanwhile the device has the colorful appearance.

Description

Technical Field

[0001] The present invention belongs to the field of perovskite solar cells, and particularly relates to a solar cell with a grating light trapping structure and a preparation method thereof. Background Art

[0002] With the continuous development of solar cell technology, the power conversion efficiency (PCE) of single-junction solar cells has been rapidly increased to 27.0%, approaching the theoretical limit value. In past research, researchers generally believed that improving the open-circuit voltage (V oc ) and fill factor (FF) were the keys to achieving high-efficiency solar cells. Thanks to the progress of passivation technology and compositional engineering, the number of defects inside the light-absorbing layer has been significantly reduced, and this improvement effectively reduces the losses of V oc and FF. However, with the continuous increase of V oc and FF, the energy conversion efficiency gradually approaches the Shockley-Queisser (S-Q) theoretical limit. This trend prompts us to re-examine other 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 issue. The short-circuit current density is closely related to the bandgap of the material, and the bandgap of the material is mainly determined by the composition, which makes the space for further increasing J sc very limited. There is still a large gap between the current actual J sc and the theoretical limit, especially in the edge region of the light absorption spectrum, where the light absorption efficiency is poor, resulting in a large amount of incident light not being fully absorbed and utilized. Therefore, in order to further improve the light utilization efficiency of the light-absorbing layer and ensure the effective transport and extraction of carriers, it is urgent to introduce an optimized light management strategy. Among them, using a grating to prepare a light trapping structure is an effective method. This structure can significantly prolong the residence time of light in the photoactive layer, enhance the interaction between light and the material, thereby increasing J sc , and then optimizing the device efficiency. Summary of the Invention

[0003] The present invention aims to improve the light absorption efficiency of solar cells, so as to further increase the short-circuit current density and device efficiency of the device. A solar cell with a grating light-trapping structure and a preparation method thereof are proposed. By fabricating the grating structure, on the one hand, the transmission path of light in the solar cell is extended, and on the other hand, the efficient transmission of carriers between different functional layers is assisted, which can effectively increase the short-circuit current and device efficiency of the solar cell. Among them, the size of the grating can be selected as any size according to different light-absorbing materials and light-absorbing bands, including but not limited to any size in the range of 5 nanometers (nm) to 1 millimeter (mm), preferably the period is 0.8 to 1.5 times the light-absorbing wavelength, preferably in the range of 200 nm to 100 micrometers (μm), more preferably in the range of 400 nm to 5 μm; the blaze angle of the grating can be any angle in the range of 0 to 180 degrees (°), preferably in the range of 0 to 90°, more preferably in the range of 80 to 90°; the line density of the grating can be selected as any density according to different light-trapping wavelengths, including but not limited to 2 lines / mm to 20,000 lines / mm, preferably in the range of 833 lines / mm to 2500 lines / mm, more preferably in the range of 1000 lines / mm to 2500 lines / mm; the depth of the grating can be selected as any depth according to different imprint substrates, including but not limited to 1 nm to 2 mm, preferably the depth is 1 / 10 to 1 / 4 of the grating period, preferably in the range of 50 nm to 2 μm, more preferably in the range of 100 nm to 1 μm; the grating structure is located at one or more positions such as the upper and lower surfaces of the light absorption layer, the upper and lower surfaces of the functional layer, etc.; the grating structure can be prepared by using one or a combination of methods such as nanoimprinting, laser direct writing, self-assembly, 3D printing, laser ablation, 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 solar cell with a grating light trapping structure and a preparation method thereof, characterized in that the structure comprises: 1) a substrate; 2) a first electrode; 3) a first functional layer; 4) a light absorption layer with a light trapping structure; 5) a light absorption material modification layer; 6) a second functional layer; 7) 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, with transparent or opaque characteristics, and also with conductive or non-conductive characteristics. The electrode is made of at least one of Au, Ag, Al, Cu, Ti metals or transparent conductive films such as 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., preferably in the range of 50 nm to 2 μm, and more preferably in the range of 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, preferably in the range of 2 nm to 100 nm, and more preferably in the range of 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 4PACz, 2PACz, Me-4PACz, Me-2PACz, MeO-4PACz, MeO-2PACz hole transport materials based on carbazole phosphate groups or triphenylamine groups), the thickness including but not limited to 0.1 nm to 500 nm, preferably in the range of 2 nm to 100 nm, and more preferably in the range of 10 nm to 50 nm.The function of the grating structure is to increase the light transmission path in the solar cell and assist the transport of carriers between different functional layers. The size of the grating can be selected as any size according to different solar cells and absorption bands, including but not limited to any size in the range of 5 nm to 1 mm for the period, preferably 0.8 to 1.5 times the absorption wavelength, preferably in the range of 200 nm to 100 μm, and more preferably in the range of 400 nm to 5 μm; the blaze angle of the grating can be any angle in the range of 0 to 180°, preferably in the range of 0 to 90°, and more preferably in the range of 80 to 90°; the line density of the grating can be selected as any density according to different trapping wavelengths, including but not limited to 2 lines / mm to 20000 lines / mm, preferably in the range of 833 lines / mm to 2500 lines / mm, and more preferably in the range of 1000 lines / mm to 2500 lines / mm; the depth of the grating can be selected as any depth according to different imprinted substrates, including but not limited to 1 nm to 2 mm, preferably the depth is 1 / 10 to 1 / 4 of the grating period, preferably in the range of 50 nm to 200 nm, and more preferably in the range of 100 nm to 150 nm; the grating structure is located at one or more positions such as the upper and lower surfaces of the light absorption layer, the upper and lower surfaces of the functional 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 perovskite); taking hybrid perovskite materials as an example, including but not limited to polycrystalline and single crystal organic-inorganic hybrid perovskite materials, where the A-site cation is at least one of lithium, sodium, potassium, rubidium, cesium, amine group, amidine group, guanidine group compounds, and the B-site cation is Pb. 2+ 、Sn 2+ 、Ge 2+ 、Sb 2+ 、Bi 3+ 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 - 、BF4 - 、I - 、Cl - 、Br -At least one of the elements, 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, 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-methoxyphenylethylammonium 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, fullerenes, aromatic hydrocarbons, organic halides, graphene compounds and their derivatives, and at least one of SiO2, SiN x , a-Si:H, Al2O3, a-SiO x :H, PbSO4, PbS, PbO, Pb(OH)2, at least one of inorganic materials, the thickness includes but is not limited to 1 nm to 500 nm, preferably in the range of 1 nm to 200 nm, more preferably in the range of 5 nm to 50 nm.

[0006] The above-mentioned solar cell based on the light trapping structure is characterized in that the functional layers such as the electrode, the electron and hole transport layers, the light absorption layer with the light trapping structure, and the modification layer of the light absorption material can be deposited on the substrate by various methods, including but not limited to thermal evaporation, spin coating, blade coating, roll coating, magnetron sputtering, atomic layer deposition, slot die coating, screen printing, inkjet printing, thermal oxidation, imprinting, etching, and at least one of these methods.

[0007] The above-mentioned solar cell based on the grating structure for making the light trapping structure is characterized in that the preparation process of the solar cell based on the light trapping structure is as follows: 1) Simulate the optimal geometric parameters of the corresponding structure; 2) Clean the substrate; 3) Prepare a thin film electrode on the substrate surface; 4) Prepare the first functional layer on the thin film electrode; 5) Prepare a polycrystalline or single-crystalline light absorption layer; 6) Prepare an imprinting template according to the simulated optimal parameters; 7) Prepare a light absorption layer with a light trapping structure; 8) Prepare a modification layer of the light absorption layer; 9) Prepare the second functional layer; 10) Prepare the second electrode. Among them, the material for making the imprinting template usually has good mechanical stability, and the material of the template can be selected from any one of the materials, including but not limited to silicon, quartz, nickel, polymer materials (such as PDMS, etc.), glass, cemented carbide, alumina, silicon carbide, chromium, titanium alloy, etc.; the steps for making a light absorption layer with a light trapping structure using the template include but are not limited to preheating, cooling, imprinting annealing, post-treatment, and other steps. Among them, the temperature for preheating the substrate can be but is not limited to 50 degrees Celsius (o C) ~130 o Any one of the temperatures in C, preferably in the range of 60 o C~110 o C, more preferably in the range of 80 o C~90 o C; The cooling time after the preheating ends can be, but is not limited to, any one of the times from 30 seconds (s) to 30 minutes (min) according to the characteristics of the light absorbing layer material, preferably in the range of 1 min to 15 min, more preferably in the range of 3 min to 6 min; The temperature for imprinting and annealing on the light absorbing layer using a template can be, but is not limited to, any one of the temperatures from 80 o C~200 o C, preferably in the range of 80 o C~150 o C, more preferably in the range of 100 o C~150 o C; The time for imprinting and annealing on the light absorbing layer using a template can be, but is not limited to, any one of the times from 1 min to 5 hours (h), preferably in the range of 1 min to 1 h, more preferably in the range of 5 min to 30 min; The pressure applied during imprinting and annealing on the light absorbing layer using a template can be, according to the different light absorbing layer materials and template materials, but is not limited to, any one of the pressures from 10 pascals (Pa) to 1 gigapascal (GPa), preferably in the range of 1 kilopascal (kPa) to 100 kilopascals, more preferably in the range of 1 kPa to 10 kPa.

[0008] The beneficial effects of the present invention are as follows: By fabricating a light-trapping structure in a solar cell, the optical path can be effectively extended, the interaction between light and the light-absorbing layer and light scattering can be enhanced, and the separation and transmission of charges can be promoted. As a result, the light absorption efficiency of the light-absorbing layer can be improved, light loss can be reduced, and further, the short-circuit current density and device efficiency of the solar cell can be increased. The principle lies in that the light-trapping structure extends the propagation path of light in the perovskite thin film, and by enhancing light scattering, standing wave effect, and exciting surface plasmon resonance, etc., the distribution range of light in the light-absorbing layer is expanded, the utilization rate of light by the light-absorbing layer is increased, and the loss of short-circuit current density is effectively reduced. This structure has an improvement effect on both the optical and electrical properties of the solar cell, and the advantages of this structure are more prominent when the light-absorbing layer is relatively thin. In addition, this light-trapping structure is applicable to various types of solar cells, 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram of the propagation path of light in the imprinted grating solar cell of the present invention;

[0011] Figure 2 is a schematic diagram of the surface morphology of the imprinted grating light-absorbing layer thin film of the present invention;

[0012] Figure 3 is a schematic diagram of the transmittance curve of the light-absorbing layer thin film before and after imprinting the grating of the present invention;

[0013] Figure 4 is a schematic diagram of the comparison of device efficiencies before and after imprinting the grating in Specific Embodiment 1 of the present invention;

[0014] Figure 5 is a schematic diagram of the comparison of short-circuit current densities before and after imprinting the grating in Specific Embodiment 1 of the present invention;

[0015] Figure 6 is a schematic diagram of the steady-state photoluminescence spectrum of the light-absorbing layer thin film before and after imprinting the grating in Specific Embodiment 1 of the present invention;

[0016] Figure 7 is a schematic diagram of the current density-voltage curve of the solar cell before and after imprinting the grating in Specific Embodiment 1 of the present invention;

[0017] Figure 8 is a schematic diagram of the structure of imprinting the grating on the light-absorbing layer in Specific Embodiment 1 of the present invention;

[0018] Figure 9 It is a schematic structural diagram of imprinting a grating on the light absorption material modification layer in Specific Embodiment 3 of the present invention;

[0019] Figure 10 It is a schematic structural diagram of imprinting a grating on the first functional layer in Specific Embodiment 5 of the present invention. Specific Embodiments

[0021] In order to make the technical solutions and advantages of the present invention clearer, the following further details the technical solutions of the present invention in conjunction with the 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.

[0022] A solar cell with a grating light trapping structure and a preparation method thereof, characterized in that the preparation sequence of the cell is as follows: 1) cleaning the substrate; 2) preparing the first electrode; 3) preparing the first functional layer; 4) preparing the light absorption layer; 5) preparing the grating light trapping structure; 6) preparing the modification layer of the light absorption layer; 9) preparing the second functional layer; 10) preparing the second electrode.

[0023] Embodiment 1

[0024] 1. Use FTO / ITO / glass as the substrate and ultrasonically clean it with a cleaning agent, deionized water, acetone, ethanol, and isopropanol.

[0025] 2. Prepare the electron transport layer by the method of chemical bath deposition (CBD) of tin oxide.

[0026] 3. On the SnO2 transport layer, prepare the perovskite absorption layer by one-step spin coating. Spin the formamidinium lead iodide (FAPbI3) solution at a speed of 7000 - 8000 rpm for 40 - 50 s, drop 170 - 200 μL of anisole as an anti-solvent, then place the substrate on a hot plate at 85 - 100 o °C for preheating for 3 - 5 min, take it down and cool for 3 - 5 min, then press the PDMS template on the surface of the perovskite film, and press it at 120 - 150 o °C with a 100 - 200 g weight for 3 - 10 min. After removing the template, continue annealing for 10 - 15 min to obtain a perovskite film with a grating structure, as Figure 8 shown.

[0027] 4. Prepare the MeO-PEAI passivation layer on the perovskite absorption layer. The solution concentration is 1 - 5 mg / mL, the solvent is isopropanol, and it is spin-coated at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0028] 5. 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.

[0029] 6. The device efficiency before and after the imprinted grating is compared as Figure 4 shown. The highest efficiency of the perovskite solar cell after the imprinted grating is 24.6%, and the specific parameters are: short-circuit current: 25.37 mA / cm 2 , open-circuit voltage: 1.17 V, fill factor: 82.8%.

[0030] 7. The short-circuit current density before and after the imprinted grating is compared as Figure 5 shown.

[0031] 8. The steady-state photoluminescence spectra before and after the imprinted grating are as Figure 6 shown, and it can be seen that the photoluminescence intensity is significantly improved.

[0032] 9. The current density-voltage curves of the perovskite solar cells before and after the imprinted grating are as Figure 7 shown.

[0033] Example 2

[0034] 1. Use FTO / ITO / glass as the substrate, and ultrasonically clean it with a cleaning agent, deionized water, acetone, ethanol, and isopropanol.

[0035] 2. Prepare the electron transport layer by the CBD tin oxide method.

[0036] 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 - 1800 rpm for 30 - 40 s and anneal at 70 o °C. Then, drop the organic salt solution on the surface of the PbI2 layer, spin-coat it at a speed of 1500 - 2000 rpm for 30 - 40 s, then place the substrate on a hot plate at 80 - 100 o °C and preheat it for 3 - 5 min, take it down and cool it for 3 - 5 min. Subsequently, press the PDMS template on the surface of the perovskite film, and press it with a 100 - 200 g weight at 120 - 150 o °C for 3 - 10 min. After removing the template, continue annealing for 10 - 15 min to obtain a perovskite film with a grating structure.

[0037] 4. Prepare a MeO-PEAI passivation layer on the perovskite absorption layer. The solution concentration is 1 - 5 mg / ml, the solvent is isopropanol, and it is spin-coated at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0038] 5. 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.

[0039] 6. Deposit 100 nm of Ag as the metal electrode.

[0040] Example 3

[0041] 1. Use ITO / glass as the substrate, and ultrasonically clean it with a cleaning agent, deionized water, acetone, and isopropanol.

[0042] 2. Prepare an electron transport layer by the CBD tin oxide method.

[0043] 3. On the SnO2 transport layer, prepare a perovskite absorption layer by a two-step spin-coating method. First, spin-coat the PbI2 solution at a speed of 1500 - 1800 rpm for 30 - 40 s and anneal at 70 o °C. Then, drop the organic salt solution on the surface of the PbI2 layer, spin-coat it at a speed of 1500 - 2000 rpm for 30 - 40 s and anneal at 120 - 150 o °C for 10 - 15 min to obtain a perovskite thin film.

[0044] 4. Prepare a MeO-PEAI passivation layer on the perovskite absorption layer. The solution concentration is 1 - 5 mg / ml, the solvent is isopropanol, and spin-coat it at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0045] 5. Imprint a grating structure on the MeO-PEAI passivation layer. Use a 100 - 200 g weight to press the PDMS with the structure on the passivation layer, anneal at 100 - 150 o °C for 10 - 30 min and then remove it, as Figure 9 shown.

[0046] 6. Prepare a Spiro-OMeTAD hole transport layer on the passivation layer with the structure, and spin-coat the Spiro-OMeTAD solution at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0047] 7. Deposit 100 nm of Ag as the metal electrode.

[0048] Example 4

[0049] 1. Use ITO / glass as the substrate, and ultrasonically clean it with a cleaning agent, deionized water, acetone, and isopropanol.

[0050] 2. The method of using CBD tin oxide to prepare the electron transport layer.

[0051] 3. On the SnO2 transport layer, the 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 o °C for 10 - 15 min to obtain the perovskite thin film.

[0052] 4. The MeO-PEAI passivation layer is prepared on the perovskite absorption layer. The solution concentration is 1 - 5 mg / ml, the solvent is isopropanol, and it is spin-coated at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0053] 5. The grating structure is imprinted on the MeO-PEAI passivation layer. A PDMS with the structure is pressed on the passivation layer using a 100 - 200 g weight, and after annealing at 100 - 150 o °C for 10 - 30 min, it is removed.

[0054] 6. The Spiro-OMeTAD hole transport layer is prepared on the passivation layer with the structure, and the Spiro-OMeTAD solution is spin-coated at a speed of 3000 - 4000 rpm for 30 - 40 s.

[0055] 7. Deposit 100 nm of Ag as the metal electrode.

[0056] Example 5

[0057] 1. Use ITO / glass as the substrate and ultrasonically clean it with a cleaning agent, deionized water, acetone, and isopropanol.

[0058] 2. The method of using CBD tin oxide to prepare the electron transport layer.

[0059] 3. The grating structure is imprinted on the tin oxide electron transport layer. A PDMS with the structure is pressed on the tin oxide using a 100 - 200 g weight, and after annealing at 150 - 170 o °C for 10 - 30 min, it is removed, as Figure 10 shown.

[0060] 4. On the SnO2 transport layer with the structure, the perovskite absorption layer is prepared by a two-step spin-coating method, and SiO2 is added to the perovskite precursor solution. Add 4 - 5 mg of SiO2 to PbI2 The solution was spin-coated at 1500 - 1800 rpm for 30 - 40 s and annealed at 70 °C. Then, an organic salt solution was dropped onto the surface of the PbI2 layer, spin-coated at 1500 - 2000 rpm for 30 - 40 s and annealed at 120 - 150 o °C for 10 - 15 min to obtain a perovskite thin film.

[0061] 5. A MeO-PEAI passivation layer was prepared on the perovskite absorption layer. The solution concentration was 1 - 5 mg / ml, the solvent was isopropanol, and it was spin-coated at 3000 - 4000 rpm for 30 - 40 s.

[0062] 6. A Spiro-OMeTAD hole transport layer was prepared on the passivation layer, and the Spiro-OMeTAD solution was spin-coated at 3000 - 4000 rpm for 30 - 40 s.

[0063] 7. 100 nm of Ag was deposited as the metal electrode.

[0064] Example 6

[0065] 1. ITO / glass was used as the substrate and ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropanol.

[0066] 2. An electron transport layer was prepared by the CBD tin oxide method.

[0067] 3. A grating structure was imprinted on the tin oxide electron transport layer. A PDMS with the structure was pressed onto the tin oxide using a 100 - 200 g weight and removed after annealing at 150 - 170 o °C for 10 - 30 min.

[0068] 4. On the SnO2 transport layer with the structure, a perovskite absorption layer was prepared by a one-step spin-coating method, and SiO2 was added to the perovskite precursor solution. 4 - 5 mg of SiO2 was added to the FAPbI3 solution and spin-coated at 7000 - 8000 rpm for 40 - 50 s, 170 - 200 μL of anisole was added as an anti-solvent, and then annealed at 120 - 150 o °C for 10 - 15 min to obtain a perovskite thin film.

[0069] 5. A MeO-PEAI passivation layer was prepared on the perovskite absorption layer. The solution concentration was 1 - 5 mg / ml, the solvent was isopropanol, and it was spin-coated at 3000 - 4000 rpm for 30 - 40 s.

[0070] 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.

[0071] 7. Deposit 100 nm of Ag as the metal electrode.

[0072] 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 art of this technology, they 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 solar cell with a grating light trapping structure and a preparation method thereof, characterized in that The structure includes: 1) a substrate; 2) a first electrode; 3) a first functional layer; 4) a light absorption layer with a light trapping structure; 5) a light absorption material modification layer; 6) a second functional layer; and 7) a second electrode.

2. The solar cell with a grating light trapping structure and the preparation method according to claim 1, characterized in that The substrate includes, but is not limited to, flexible or rigid substrates such as glass, metal, silicon wafers, fiber fabrics, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyimide (PI), polydimethylsiloxane (PDMS) and its derivatives, etc., having transparent or opaque characteristics, and also having conductive or non-conductive characteristics.

3. The solar cell with a grating light trapping structure according to claim 1 and its manufacturing method, characterized in that The electrode includes, but is not limited to, at least one of metals such as Au, Ag, Al, Cu, Ti, etc., or transparent conductive films such as 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. The solar cell with a grating light trapping structure and the preparation method according to claim 1, characterized in that The first functional layer and the second functional layer serve as the electron transport layer and the 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 can be but is not limited to 0.1 nanometer to 500 nanometers, preferably 2 nanometers to 100 nanometers, and more preferably 10 nanometers to 50 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 P-type self-assembled monolayer materials (such as 4PACz, 2PACz, Me-4PACz, Me-2PACz, MeO-4PACz, MeO-2PACz hole transport materials based on carbazole phosphate groups or triphenylamine groups) 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 solar cell with a grating light trapping structure and a preparation method according to claim 1, characterized in that The size of the grating can be selected as any size according to different light absorption bands, including but not limited to any size within the range of 5 nanometers to 1 millimeter in period, preferably the period is 0.8 to 1.5 times the light absorption wavelength, the preferred range is 200 nanometers to 100 micrometers, and the more preferred range is 400 nanometers to 5 micrometers; the blaze angle of the grating can be any angle within 0 to 180 degrees, preferably in the range of 0 to 90 degrees, and more preferably in the range of 80 degrees to 90 degrees; the line density of the grating can be selected as any density according to different trapping light wavelengths, including but not limited to 2 lines / mm to 20000 lines / mm, preferably in the range of 833 lines / mm to 2500 lines / mm, and more preferably in the range of 1000 lines / mm to 2500 lines / mm; the depth of the grating can be selected as any depth according to different imprinted substrates, including but not limited to 1 nanometer to 2 millimeters, preferably the depth is 1 / 10 to 1 / 4 of the grating period, the preferred range is 50 nanometers to 2 micrometers, and more preferably in the range of 100 nanometers to 1 micrometer; the grating structure is located at one or more positions such as the upper and lower surfaces of the light absorption layer, the upper and lower surfaces of the functional layer, etc.; the grating structure can be prepared by using one or a combination of methods such as nanoimprinting, laser direct writing, self-assembly, 3D printing, laser ablation, etc.; the light absorption layer can be any material that absorbs light and can generate free moving carriers, and can be one or a combination 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 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, including but not limited to polycrystalline and single crystal organic-inorganic hybrid perovskite materials, where the A-site cation is at least one of lithium, sodium, potassium, rubidium, cesium, amine group, amidine group, guanidine group compounds, the B-site cation is Pb 2+ 、Sn 2+ 、Ge 2+ 、Sb 2+ 、Bi + 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 - 、BF 4- 、I - 、Cl - 、Br - At least one of the elements, 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.

6. The solar cell with a grating light trapping structure and the preparation method according to claim 1, characterized in that 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 at least one of compounds such as phenyltriethylammonium iodide (PEAI), ethylenediaminetetraacetic acid (EDTA), choline chloride, polymethyl methacrylate (PMMA), alkanes with -SH, -OH, -CN, -COOH, -NH2, -SCN, -halide ion terminal functional groups, pyridine, fullerenes, aromatic hydrocarbons, organic halides, graphene and its derivatives, as well as at least one of inorganic materials such as SiO2, SiNx, a-Si:H, Al2O3, a-SiOx: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 electrode, electron and hole transport layers, light absorption layer with a light trapping structure, and modification layer of the light absorption material according to claims 3, 4, and 5 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 solar cell with a grating light trapping structure and the preparation method as described above are characterized in that The preparation method is as follows: 1) Simulate the optimal geometric parameters 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 light absorption layer; 6) Prepare an imprint template according to the simulated optimal parameters; 7) Prepare a grating light-trapping structure on the light absorption layer; 8) Prepare a modification layer for the light absorption layer; 9) Prepare a second functional layer; 10) Prepare a second electrode. Among them, the material for making the imprint template usually has good mechanical stability, and the template material can be but is not limited to at least one of silicon, quartz, nickel, polymer materials (such as PDMS), glass, cemented carbide, alumina, silicon carbide, chromium, and titanium alloy. The steps of using the template to make a light absorption layer with a light-trapping structure include but are not limited to multiple steps such as preheating, cooling, imprint annealing, and post-treatment. Among them, the temperature for preheating the substrate can be any temperature from 50 °C to 130 °C, preferably in the range of 60 °C to 110 °C, and more preferably in the range of 80 °C to 90 °C, depending on the material of the light absorption layer; the cooling time after the preheating is completed can be any time from 30 seconds to 30 minutes, preferably in the range of 1 minute to 15 minutes, and more preferably in the range of 3 minutes to 6 minutes, depending on the characteristics of the light absorption layer material; the temperature for imprint annealing on the light absorption layer using the template can be any temperature from 80 °C to 200 °C, preferably in the range of 80 °C to 150 °C, and more preferably in the range of 100 °C to 150 °C; the time for imprint annealing on the light absorption layer using the template can be any time from 1 minute to 5 hours, preferably in the range of 1 minute to 1 hour, and more preferably in the range of 5 minutes to 30 minutes; the pressure applied during imprint annealing on the light absorption layer using the template can be any pressure from 10 Pa to 1 GPa, preferably in the range of 1 kPa to 100 kPa, and more preferably in the range of 1 kPa to 10 kPa, depending on the materials of the light absorption layer and the template material.

9. The solar cell with a grating light trapping structure and the preparation method according to claim 1, characterized in that The described 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 tandem solar cells.

10. The solar cell with a grating light trapping structure and its manufacturing method according to claim 1, characterized in that The described 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, and resistive memories.

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