A solar cell and a method of manufacturing the same

Abstract

The application discloses a solar cell, comprising a transparent conductive substrate layer, a first carrier transport layer, a perovskite absorption layer and a second carrier transport layer arranged in sequence; the first carrier transport layer comprises a substrate layer and a plurality of spaced nanotube structures formed on the substrate layer and facing the perovskite absorption layer; the perovskite absorption layer covers the surface of the substrate layer away from the transparent conductive substrate layer, the outer surface of the nanotube structure and the inside of the nanotube structure; and the second carrier transport layer covers the surface of the perovskite absorption layer away from the first carrier transport layer. The application also provides a preparation method of the solar cell. The solar cell provided by the application can break through the limitation of the Shockley-Queisser limit and improve the energy conversion efficiency of the solar cell.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, specifically to a solar cell and its fabrication method. Background Technology

[0002] According to theoretical research, the energy conversion efficiency of solar cells is limited by the Shockley-Queisser limit. In single-junction cells, the maximum thermodynamic conversion efficiency of solar energy to electrical energy is 33.7%, corresponding to an absorber material with a band gap of 1.34 eV. When a photon with energy Ei irradiates an absorber material with a band gap of Eg, electrons in the valence band are excited to energy levels in the conduction band higher than the bottom of the conduction band. These excited electrons (hot carriers) in the high-energy level are in an unstable state and rapidly relax (the relaxation time is called the "hot carrier lifetime," which is on the order of picoseconds) to the bottom of the conduction band. Then, electrons at the bottom of the conduction band and holes at the top of the valence band are led out to the external circuit through the upper and lower electrodes, completing the photoelectric conversion process. During the relaxation process, the energy "Ei-Eg" of the hot carriers is not effectively utilized and is released as heat. Therefore, the energy conversion efficiency of solar cells in current technology is relatively low. Summary of the Invention

[0003] To address the aforementioned issues, this application proposes a solar cell that can improve the energy conversion efficiency of solar cells and overcome the Shockley-Queisser limit.

[0004] This application provides a solar cell, comprising a transparent conductive substrate layer, a first carrier transport layer, a perovskite absorber layer and a second carrier transport layer arranged sequentially.

[0005] The first carrier transport layer includes a substrate layer and a plurality of spaced nanotube structures formed on the substrate layer facing the perovskite absorber layer.

[0006] The perovskite absorber layer covers the surface of the substrate layer opposite to the transparent conductive substrate layer, the outer surface of the nanotube structure, and the interior of the nanotube structure.

[0007] The second carrier transport layer covers the surface of the perovskite absorber layer that is away from the first carrier transport layer;

[0008] The first carrier transport layer is a hot carrier transport layer.

[0009] Furthermore, the perovskite absorber layer has a columnar structure that covers the nanotube structure and is spaced apart from each other.

[0010] Furthermore, the perovskite absorber layer comprises a perovskite surface layer and a perovskite filling layer.

[0011] The perovskite surface layer uniformly covers the surface of the substrate layer and the outer surface of the nanotube structure.

[0012] The perovskite filling layer completely fills the interior of the nanotube structure.

[0013] The perovskite surface layer located at the top of the nanotube structure is seamlessly connected to the perovskite filling layer.

[0014] Furthermore, the perovskite absorber layer is a perovskite quantum dot layer.

[0015] The size of the quantum dots in the perovskite quantum dot layer is 1-30 nm;

[0016] The perovskite quantum dot layer is selected from one of the following: organic-inorganic hybrid halide perovskite layer, all-inorganic halide perovskite layer, lead-free perovskite layer, or double perovskite layer.

[0017] Furthermore, the quantum dots are one or more of the following shapes: spherical, hemispherical, quasi-spherical, columnar, conical, and frustum-shaped.

[0018] Furthermore, the thickness of the perovskite surface layer is T. abs T abs ≤2L hot ;

[0019] Where L hot =(D hot ×τ hot ) 1 / 2 ;

[0020] L hot The diffusion length of hot carriers in the perovskite absorber layer at room temperature;

[0021] D hot is the diffusion coefficient of hot carriers in the perovskite absorber layer at room temperature;

[0022] τ hot The lifetime of hot carriers in the perovskite absorber layer at room temperature.

[0023] Furthermore, the L hot The wavelength is 70-300nm;

[0024] τ hot 50-300ps;

[0025] T abs The range is 140-600nm.

[0026] Furthermore, the nanotube structure satisfies the following condition:

[0027] R≤Tabs ;

[0028] H≤1500nm;

[0029] D>2T abs ;

[0030] R is the radius of the nanotube structure;

[0031] H is the height of the nanotube structure;

[0032] D represents the spacing between adjacent nanotube structures.

[0033] Furthermore, the multiple nanotube structures are arranged in a matrix.

[0034] Furthermore, the surfaces of adjacent nanotube structures are covered with the perovskite surface layer and then have gaps;

[0035] The second carrier transport layer covers the perovskite surface layer and the gap, and the side of the second carrier transport layer facing away from the perovskite absorber layer is planar.

[0036] Furthermore, the second carrier transport layer is a hot carrier transport layer.

[0037] Further, the first and second carrier transport layers are selected from molybdenum oxide layers, [bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) layers, copper iodide layers or Spiro-OMeTAD (2,2',7,7'-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene) layers, PEDOT layers, PEDOT:PSS layers, P3HT layers, P3OHT layers, P3ODDT layers, NiO layers or CuSCN layers, titanium oxide layers, tin oxide layers, C60 layers or C60 derivative layers, [6,6]-phenyl-C 61 - Isomethyl butyrate layer, [6,6]-phenyl-C 71 - Isomethyl butyrate) layer, bis

[60] PCBM(Bis(1-[3-(methoxycarbonyl)propyl]-1-phenyl)-[6,6]C 62 ) layer or

[60] ICBA(1',1",4',4"-Tetrahydro-di[1,4]methanonaphthaleno[1,2:2',3',56,60:2",3"][5,6]full erene-C 60 One of the layers.

[0038] This application provides a method for preparing a solar cell, comprising the following steps:

[0039] Provide a transparent conductive substrate layer;

[0040] The first carrier transport layer is formed on one side surface of the transparent conductive substrate layer. The first carrier transport layer includes a base layer, on which a plurality of spaced nanotube structures are arranged facing the perovskite absorption layer.

[0041] A perovskite absorption layer is formed on the side of the substrate layer opposite to the transparent conductive substrate layer, on the outer surface of the nanotube structure, and inside the nanotube structure.

[0042] A second carrier transport layer is formed on the surface of the perovskite absorber layer that is opposite to the first carrier transport layer.

[0043] The first carrier transport layer is a hot carrier transport layer.

[0044] Furthermore, the perovskite absorber layer comprises a perovskite surface layer and a perovskite filling layer.

[0045] The perovskite surface layer uniformly covers the surface of the substrate layer and the outer surface of the nanotube structure.

[0046] The perovskite filling layer completely fills the interior of the nanotube structure.

[0047] The perovskite surface layer located at the top of the nanotube structure is seamlessly connected to the perovskite filling layer.

[0048] Furthermore, after the surfaces of adjacent nanotube structures are covered by the perovskite surface layer, there are gaps, the second carrier transport layer is formed in the perovskite surface layer and the gaps, and the side surface of the second carrier transport layer facing away from the perovskite absorption layer is planar.

[0049] The solar cell provided in this application has a first carrier transport layer with a base layer and several nanotube structures, and the perovskite absorber layer covers the first carrier transport layer with the above structure. Based on the quantum confinement effect of the nanopores and the phonon bottleneck effect of the perovskite absorber layer, the lifetime of hot carriers in the perovskite absorber layer in the nanopores can be increased by 1-2 orders of magnitude, and the hot carrier diffusion length is greatly increased. While meeting the energy requirements for utilizing hot carriers, the thickness of the perovskite absorber layer can be greatly increased, so that the solar cell can absorb more light energy, improve the energy conversion efficiency of the solar cell, and break through the Shockley-Queisser limit. Attached Figure Description

[0050] The accompanying drawings are provided to better understand this application and do not constitute an undue limitation thereof. Wherein:

[0051] Figure 1 This is a schematic diagram of the structure of the solar cell provided in this application.

[0052] Figure 2 The solar cell provided in this application is along Figure 1 A cross-section diagram with dashed lines.

[0053] Figure 3 A schematic diagram of the structure of a solar cell, Comparative Example 1, is provided for this application.

[0054] Explanation of reference numerals in the attached figures

[0055] 1-Transparent conductive substrate, 2-First carrier transport layer, 21-Base layer, 22-Nanotube structure, 3-Perovskite absorber layer, 31-Perovskite surface layer, 32-Perovskite filling layer, 4-Second carrier transport layer, 5-Upper electrode layer. Detailed Implementation

[0056] The following description illustrates exemplary embodiments of this application, including various details to aid understanding; these should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description. In this application, the vertical position is determined according to the direction of light incidence, with the point of light incidence being vertical.

[0057] In traditional solar cell absorber layers, the diffusion length of hot carriers is only a few nanometers to tens of nanometers. When the migration distance of hot carriers exceeds this length, they cool down and become conventional carriers, making it difficult to realize hot carrier solar cells with conventional absorber layers. However, in perovskite photovoltaic materials, hot carriers have a longer lifetime and a larger diffusion coefficient, thus exhibiting a longer diffusion length. In conventional perovskite materials, the diffusion coefficient D of hot carriers at room temperature is... hot At 5cm 2 Approximately / s, hot carrier lifetime τ hotThe diffusion length of hot carriers in perovskite materials is estimated to be between 20-50 nm, within the range of 1-5 ps. However, a perovskite absorber layer approximately 50 nm thick is still insufficient to fully absorb sunlight. Even with the high energy of hot carriers, a higher open-circuit voltage can be achieved, but due to insufficient light absorption and a low short-circuit current, the energy conversion efficiency remains low, failing to fully realize the high efficiency advantage of hot carrier solar cells. By adopting methods to extend the hot carrier lifetime, thereby extending the diffusion length, and fabricating a thicker perovskite absorber layer while still meeting the hot carrier extraction requirements, the energy conversion efficiency of hot carrier perovskite solar cells can be further improved.

[0058] Based on this, such as Figure 1 As shown, the solar cell provided in this application includes a transparent conductive substrate layer 1, a first carrier transport layer 2, a perovskite absorber layer 3, a second carrier transport layer 4, and an upper electrode layer 5 arranged sequentially.

[0059] The first carrier transport layer 2 includes a substrate layer 21 and a plurality of spaced nanotube structures 22 formed on the substrate layer 21 and facing the perovskite absorption layer 3.

[0060] The perovskite absorber layer 3 covers the surface of the substrate layer 21 facing away from the transparent conductive substrate layer 1, the outer surface of the nanotube structure 22, and the interior of the nanotube structure 22.

[0061] The second carrier transport layer 4 covers the surface of the perovskite absorber layer 3 that is away from the first carrier transport layer.

[0062] Specifically, both the first carrier transport layer 2 and the second carrier transport layer 4 are hot carrier transport layers.

[0063] The transparent conductive substrate 1 refers to a rigid or flexible transparent substrate coated with a transparent conductive film; common rigid substrates are glass; common flexible substrates are PET or PEN; common transparent conductive films mainly include fluorine-doped indium oxide (FTO), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), etc.

[0064] The first carrier transport layer 2 and the second carrier transport layer 4 have opposite conductivity types, one being a hot hole transport layer and the other a hot electron transport layer. When the first carrier transport layer 2 is a hot hole transport layer, the first carrier transport layer 2 can be a molybdenum oxide layer, a [bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) layer, a copper iodide layer, or a Spiro-OMeTAD (2,2',7,7'-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene) layer, a PEDOT layer, a PEDOT:PSS layer, a P3HT layer, a P3OHT layer, a P3ODDT layer, a NiO layer, or a CuSCN layer, including but not limited to these, as long as the function in this application can be achieved. When the second carrier transport layer 4 is a hot electron transport layer, the second carrier transport layer 4 can be a titanium oxide layer, a SnO2 layer, a tin oxide layer, a C60 layer or a C60-PCBM layer,

[60] PCBM([6,6]-phenyl-C 61 butyric acid methyl ester, Chinese name [6,6]-phenyl-C 61 -Isomethyl butyrate) layer,

[70] PCBM([6,6]-Phenyl-C 71 -butyric acidmethyl ester, Chinese name is [6,6]-phenyl-C 71 - Isomethyl butyrate) layer, bis

[60] PCBM(Bis(1-[3-(methoxycarbonyl)propyl]-1-phenyl)-[6,6]C 62 ) layer,

[60] ICBA(1',1",4',4"-Tetrahydro-di[1,4]methanonaphthaleno[1,2:2',3',56,60:2",3"][5,6]full erene-C 60 Layers such as

[60] PCBM ([6,6]-phenyl-C 61 Butyric acid methyl ester, Chinese name [6,6]-phenyl-C 61 -Isomethyl butyrate) layer,

[70] PCBM([6,6]-Phenyl-C71 -butyricacidmethyl ester, Chinese name is [6,6]-phenyl-C 71 - Isomethyl butyrate) layer, bis

[60] PCBM(Bis(1-[3-(methoxycarbonyl)propyl]-1-phenyl)-[6,6]C 62 ) layer,

[60] ICBA(1',1",4',4"-Tetrahydro-di[1,4]methanonaphthaleno[1,2:2',3',56,60:2",3"][5,6]full erene-C 60 The second carrier transport layer 4 may be a molybdenum oxide layer, a [bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) layer, a copper iodide layer, or a Spiro-OMeTAD (2,2',7,7'-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene) layer, a PEDOT layer, a PEDOT:PSS layer, a P3HT layer, a P3OHT layer, a P3ODDT layer, a NiO layer, or a CuSCN layer, including but not limited to these, as long as they can achieve the functions in this application.

[0065] One side surface of the substrate layer 21 is stacked with the transparent conductive substrate layer 1, and the other side surface has a plurality of nanotube structures 22.

[0066] The substrate layer 21 is a dense thin film of transport material.

[0067] The thickness of the substrate 21 is 10-200nm, for example, it can be 10nm, 11nm, 12nm, 13nm, 14nm, 5nm, 6nm, 17nm, 18nm, 19nm or 20nm.

[0068] The upper electrode layer 5 can be a transparent conductive material such as ITO (indium tin oxide), FTO (fluorine-doped tin oxide), or AZO (aluminum-doped zinc oxide), or a metallic material such as gold, silver, aluminum, or copper, or a carbon material; the thickness of the upper electrode layer 5 is between 100nm and 100,000nm, for example, it can be 100nm, 500nm, 1000nm, 2000nm, 3000nm, 4000nm, 5000nm, 6000nm, 7000nm, 8000nm, 9000nm, 10000nm, etc.

[0069] In this application, the perovskite absorber layer 3 is a perovskite quantum dot layer.

[0070] Specifically, the perovskite quantum dot layer can be an organic-inorganic hybrid halide perovskite layer, an all-inorganic halide perovskite layer, a lead-free perovskite layer, a double perovskite layer, etc., including but not limited to these.

[0071] The size of the quantum dots in the perovskite quantum dot layer is 1-30 nm, preferably 1-10 nm, and more preferably 1-5 nm. For example, it can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, or 30 nm.

[0072] Specifically, the quantum dots are one or more of the following: spherical, near-spherical, columnar, conical, and frustum-shaped, including but not limited to these.

[0073] More specifically, when the quantum dot is spherical, the diameter of the quantum dot is 1-30 nm, preferably 1-10 nm, and more preferably 1-5 nm.

[0074] When the quantum dot is spherical, the maximum diameter of the quantum dot is 1-30 nm, preferably 1-10 nm, and more preferably 1-5 nm.

[0075] When the quantum dot is columnar, conical, or truncated, the maximum size parameter of the quantum dot is 1-30 nm, preferably 1-10 nm, and more preferably 1-5 nm.

[0076] In this application, the perovskite absorber layer 3 includes a perovskite surface layer 31 and a perovskite filling layer 32.

[0077] The perovskite surface layer 31 uniformly covers the surface of the base layer 21 and the outer surface of the nanotube structure 22.

[0078] The perovskite filling layer 32 completely fills the interior of the nanotube structure 22.

[0079] The perovskite surface layer 31 located on top of the nanotube structure 22 is seamlessly connected to the perovskite filling layer 32.

[0080] In this application, according to the principle of a carrier battery, the hot carriers generated in the perovskite surface layer 31 must reach the first carrier transport layer or the second carrier transport layer 4 and be collected before it "cools down." Therefore,

[0081] If it is required that all the hot carriers generated in the perovskite surface layer 31 can be collected, then the following condition must be met: T abs ≤L hot .

[0082] That is, hot electrons and hot holes generated at any location in the perovskite surface layer 31 can migrate to the corresponding carrier transport layer before cooling.

[0083] If it is required that the hot carriers at the center of the perovskite surface layer 31 be collected, then the following condition must be met: T abs ≤2L hot .

[0084] That is, both hot electrons and hot holes generated at the center of the perovskite surface layer 31 can be collected; on the side away from the center and closer to the hot electron transport layer, only hot electrons can be collected before cooling; similarly, on the other side, only hot holes are collected; as the thickness of the perovskite surface layer 31 continues to increase, the proportion of collected hot electrons and / or hot holes continues to decrease, while the probability of hot electrons or hot holes being scattered, recombinated, and cooled during transport in the perovskite surface layer 31 increases significantly, thus losing the advantages of hot carrier solar cells and gradually transforming into conventional solar cells.

[0085] Therefore, when T abs ≤2L hot At this time, most of the hot carriers generated in the perovskite surface layer 31 can be effectively discharged to the external circuit. Therefore, in this application, the thickness T of the perovskite surface layer 31 is... abs satisfy:

[0086] T abs ≤2L hot .

[0087] L hot The diffusion length of hot carriers in the perovskite absorber layer at room temperature.

[0088] In this application, the L hot Satisfy the following formula:

[0089] L hot =(D hot ×τ hot ) 1 / 2 ;

[0090] D hot is the diffusion coefficient of hot carriers in the perovskite absorber layer at room temperature;

[0091] τ hot The lifetime of hot carriers in the perovskite absorber layer at room temperature.

[0092] In the above equation, at room temperature, for a specific material, the diffusion coefficient D of hot carriers is... hot It is a constant; to increase the diffusion length of hot carriers, the lifetime of hot carriers must be increased. When the size of the quantum dots in the perovskite absorber layer 3 is reduced to the nanometer level, the lifetime of hot carriers will be significantly extended due to the quantum confinement effect and the phonon bottleneck effect. Therefore, by restricting the size of the quantum dots in the perovskite absorber layer 3 to the nanometer level, a perovskite absorber layer 3 with a larger carrier diffusion length can be obtained.

[0093] Specifically, at room temperature D hot 1-3cm 2 / s, for example, can be 1cm 2 / s、2cm 2 / s or 3.

[0094] τ hot The range is 50-300ps, for example, it can be 50ps, 100ps, 150ps, 200ps, 250ps or 300ps.

[0095] L hot The range is 70-300nm, for example, it can be 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm or 300nm.

[0096] T abs It can be 140-600nm, for example, it can be 140nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm or 600nm.

[0097] The above parameters only apply when the perovskite absorber layer 3 is a perovskite quantum dot layer. If the perovskite absorber layer 3 is not a perovskite quantum dot layer, but a conventional continuous thin-film perovskite, the hot carrier diffusion length is no more than 50 nm.

[0098] In this application, the arrangement of the plurality of nanotube structures 22 can be in a matrix (e.g., Figure 2 (as shown), including but not limited to this.

[0099] The nanotube structure 22 can be perpendicular to the substrate layer 21, and the nanotube structure 22 can also be curved.

[0100] In this application, the nanotube structure 22 satisfies the following conditions:

[0101] R≤T abs ;

[0102] H≤1500nm;

[0103] D>2T abs

[0104] R is the radius of the nanotube structure 22;

[0105] H is the height of nanotube structure 22;

[0106] D represents the spacing between adjacent nanotube structures 22.

[0107] Specifically, R is less than T abs At this time, most of the hot carriers generated in all regions of the perovskite absorber layer 3 can be collected. Although the smaller the diameter of the nanotube structure 22, the more obvious the quantum confinement effect and the longer the diffusion length of the hot carriers, the smaller the diameter of the nanotube structure 22, the more difficult it is to prepare, and the more difficult it is to fill the absorber layer material inside the nanotube structure 22.

[0108] Specifically, the interior of the nanotube structure 22 is filled with perovskite quantum dot material. The higher the nanotube structure 22, the more perovskite quantum dot material can be filled, resulting in more sufficient light absorption. However, the taller the nanotube structure 22, the more easily the tubular structure bends, which is not conducive to the filling of perovskite quantum dot material. At the same time, the preparation process is also more complex and difficult to control.

[0109] Specifically, the spacing between the two nanotube structures 22 should be greater than twice the thickness of the perovskite surface layer 31. Since the thickness of the perovskite surface layer 31 is between 140-600 nm, D > 1200 nm. To ensure a certain safe distance and effective extraction of hot carriers, D ≥ 1500 nm is preferred.

[0110] In this application, the perovskite absorber layer 3 has a columnar structure that covers the nanotube structure and is spaced apart from each other. That is, there is a gap between adjacent nanotube structures 22 after the surface of the perovskite surface layer 31 is covered.

[0111] In this application, the second carrier transport layer 4 covers the perovskite surface layer 31 and the gap, and the surface of the second carrier transport layer 4 facing away from the perovskite absorber layer 3 is planar. The second carrier transport layer 4 includes a filling layer and a surface layer. The filling layer fills the gap and the perovskite surface layer 31 on the surface of the nanotube structure 22 located at the edge. The surface layer is planar, that is, the surface layer covers the perovskite surface layer 31 on top of the nanotube structure 22 and the filling layer, and the filling layer and the surface layer are seamlessly connected.

[0112] This application provides a method for preparing the solar cell described above, comprising the following steps:

[0113] Step 1: Provide a transparent conductive substrate layer 1;

[0114] Step 2: The first carrier transport layer 2 is formed on one side surface of the transparent conductive substrate layer 1. The first carrier transport layer 2 includes a base layer 21. On the base layer 21, on one side surface opposite to the transparent conductive substrate layer 1, there are a plurality of spaced nanotube structures 22.

[0115] Step 3: A perovskite absorption layer 3 is formed on the side of the substrate layer 21 facing away from the transparent conductive substrate layer 1, on the outer surface of the nanotube structure 22, and inside the nanotube structure 22.

[0116] Step 4: A second carrier transport layer 4 is formed on the surface of the perovskite absorber layer 3 that is opposite to the first carrier transport layer 2.

[0117] Both the first carrier transport layer 2 and the second carrier transport layer 4 are hot carrier transport layers.

[0118] Specifically, in step one, the FTO conductive glass substrate is cleaned by ultrasonic cleaning in ethanol, acetone, water and isopropanol for 15 minutes each, and then dried with clean dry air to obtain the transparent conductive substrate layer 1.

[0119] Specifically, in step two, 20 μL of saturated FeCl3 solution is dropped onto the transparent conductive substrate 1 and placed in a wide-mouth bottle. 250 μL of a 50 μmol pyrrole-chlorobenzene solution is then placed in the bottle. Before the reaction begins, the wide-mouth bottle is heated to 115°C and humidified nitrogen gas (700 sccm flow rate) with a humidity of 25% wt is introduced. After reacting for 30 min, a PEDOT nanotube structure containing FeCl2 impurities is formed. Finally, the mixture is rinsed three times in 6M hydrochloric acid to obtain the first carrier transport layer 2.

[0120] (Growth mechanism: The PEDOT synthesis reaction occurs at the interface between "moist nitrogen gas containing pyrrole-chlorobenzene" and "FeCl3 solution". Therefore, in the early stage of growth, the saturated FeCl3 solution covers the entire surface of the transparent conductive substrate 1, forming a full-surface PEDOT, i.e., the substrate layer 21; in the later stage, due to the effect of liquid surface tension and the consumption of FeCl3 solution, the FeCl3 solution gradually becomes distributed in droplets, and PEDOT is only generated at the interface between the droplets and the gas phase. By controlling the flow rate of moist nitrogen gas, the volatilization temperature and rate of pyrrole-chlorobenzene solution, the growth height and wall thickness of the nanotube structure can be controlled; by controlling the amount of saturated FeCl3 solution added to the transparent conductive substrate 1, the thickness of the substrate layer 21 and the density of the nanotube structure on the substrate layer, i.e., the spacing between the tubes, can be controlled.)

[0121] Specifically, in step three, a MAPbI3 perovskite quantum dot layer is prepared using a hot-injection method. 0.1 mmol of PbI2, 0.08 mmol of MAI, 0.2 ml of oleic acid, and 15 μl of n-octylamine are dissolved in 2 ml of acetonitrile. After ultrasonic dispersion for 15 minutes, this solution is added dropwise to 10 ml of toluene while stirring. After addition, the solution is centrifuged at 7000 rpm for 15 minutes, the precipitate is discarded, and the supernatant is collected to obtain a toluene dispersion of MAPbI3 quantum dots with a particle size range of 5-10 nm. The product obtained in step two is then placed into the toluene dispersion of MAPbI3 quantum dots, and a chemical bath deposition method is used to form a MAPbI3 perovskite quantum dot absorption layer on the first carrier transport layer 2.

[0122] Specifically, in step four, a PC61BM solution with a concentration of 20 mg / ml is spin-coated onto the perovskite absorber layer 3 by spin-coating at 2000 rpm for 30 seconds to obtain the second carrier transport layer 4.

[0123] The method further includes step five, forming an upper electrode layer 5 on the second carrier transport layer 4.

[0124] Specifically, in step six, a 200 nm thick Al thin film is deposited on the second carrier transport layer 4 using a thermal evaporation method. The evaporation rate is: Finally, a complete perovskite thermal carrier cell was obtained.

[0125] This application provides a method for preparing the solar cell described above, comprising the following steps:

[0126] Step 1: Provide a transparent conductive substrate layer 1;

[0127] Specifically, the FTO conductive glass substrate is cleaned by ultrasonic cleaning in ethanol, acetone, water and isopropanol for 15 minutes each, and then dried with clean dry air to obtain the transparent conductive substrate layer 1.

[0128] Step 2: The first carrier transport layer 2 is formed on one side surface of the transparent conductive substrate layer 1. The first carrier transport layer 2 includes a base layer 21. On the base layer 21, on one side surface opposite to the transparent conductive substrate layer 1, there are a plurality of spaced nanotube structures 22.

[0129] Specifically, 20 μL of saturated FeCl3 solution was dropped onto a transparent conductive substrate 1 and placed in a wide-mouthed bottle. 250 μL of a 50 μmol pyrrole-chlorobenzene solution was then added to the bottle. Before the reaction began, the bottle was heated to 115 °C and humidified nitrogen gas (700 sccm flow rate) with a humidity of 25% wt was introduced. After reacting for 30 min, a PEDOT nanotube structure containing FeCl2 impurities was formed. Finally, the mixture was rinsed three times in 6M hydrochloric acid to obtain the first carrier transport layer 2.

[0130] (Growth mechanism: The PEDOT synthesis reaction occurs at the interface between "moist nitrogen gas containing pyrrole-chlorobenzene" and "FeCl3 solution". Therefore, in the early stage of growth, the saturated FeCl3 solution covers the entire surface of the transparent conductive substrate 1, forming a full-surface PEDOT, i.e., the substrate layer 21; in the later stage, due to the effect of liquid surface tension and the consumption of FeCl3 solution, the FeCl3 solution gradually becomes distributed in droplets, and PEDOT is only generated at the interface between the droplets and the gas phase. By controlling the flow rate of moist nitrogen gas, the volatilization temperature and rate of pyrrole-chlorobenzene solution, the growth height and wall thickness of the nanotube structure can be controlled; by controlling the amount of saturated FeCl3 solution added to the transparent conductive substrate 1, the thickness of the substrate layer 21 and the density of the nanotube structure on the substrate layer, i.e., the spacing between the tubes, can be controlled.)

[0131] Step 3: A perovskite absorption layer 3 is formed on the side of the substrate layer 21 facing away from the transparent conductive substrate layer 1, on the outer surface of the nanotube structure 22, and inside the nanotube structure 22.

[0132] Specifically, 0.1 mmol of PbI₂, 0.08 mmol of MAI, 0.2 ml of oleic acid, and 15 μl of n-octylamine were dissolved in 2 ml of acetonitrile and ultrasonically dispersed for 15 minutes. This solution was then added dropwise to 10 ml of toluene while stirring. After addition, the solution was centrifuged at 7000 rpm for 15 minutes, the precipitate was discarded, and the supernatant was collected to obtain a toluene dispersion of MAPbI₃ quantum dots with a particle size range of 5-10 nm.

[0133] The product obtained in step two is placed in a toluene dispersion of the MAPbI3 quantum dots, and a chemical bath deposition method is used to form a MAPbI3 perovskite quantum dot absorption layer on the first carrier transport layer 2.

[0134] Step 4: A second carrier transport layer 4 is formed on the surface of the perovskite absorber layer 3 that is opposite to the first carrier transport layer 2.

[0135] Specifically, a PC61BM solution with a concentration of 20 mg / ml was spin-coated onto the perovskite absorber layer 3 at 2000 rpm for 30 seconds to obtain the second carrier transport layer 4.

[0136] Step 5: Form an upper electrode layer 5 on the second carrier transport layer 4.

[0137] Specifically, a 200 nm thick Al thin film is deposited on the second carrier transport layer 4 using a thermal evaporation method. The evaporation rate is: Finally, a complete perovskite thermal carrier cell was obtained.

[0138] Both the first carrier transport layer 2 and the second carrier transport layer 4 are hot carrier transport layers.

[0139] The solar cell described in this application has a first carrier transport layer 2 with a nanotube structure 22 and a perovskite quantum dot layer. The perovskite absorber layer 3 has a perovskite surface layer 31 and a perovskite filling layer 32. The perovskite filling layer 32 is filled and disposed in the "arrayed nanotube structure 22 with a nanoscale porous structure". Based on the quantum confinement effect of the nanotube structure 22 and the phonon bottleneck effect of the perovskite quantum dot layer, the lifetime of hot carriers in the perovskite filling layer 32 in the nanotube structure 22 can be increased by 1-2 orders of magnitude, and the hot carrier diffusion length is greatly increased. While meeting the energy requirements for utilizing hot carriers, the thickness of the perovskite surface layer 31 can also be greatly increased, allowing the solar cell to absorb more light energy, improving the energy conversion efficiency of the hot carrier perovskite solar cell, and breaking the Shockley-Queisser limit.

[0140] Example

[0141] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0142] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0143] Example 1

[0144] The method for preparing a solar cell described in this embodiment includes the following steps:

[0145] Step 1: Forming the transparent conductive substrate layer 1: Cleaning the FTO conductive glass substrate: The FTO substrate was ultrasonically cleaned in ethanol, acetone, water, and isopropanol for 15 minutes each, and then dried with clean, dry air to obtain the transparent conductive substrate layer 1. The thickness of the FTO layer is 700 nm.

[0146] Step 2: Formation of the first carrier transport layer 2: 20 μL of saturated FeCl3 solution was dropped onto the transparent conductive substrate 1 and placed in a wide-mouth bottle. 250 μL of a 50 μmol pyrrole-chlorobenzene solution was added to the bottle. Before the reaction began, the bottle was heated to 115°C and humidified nitrogen gas (700 sccm flow rate) with a humidity of 25% wt was introduced. After reacting for 30 min, a PEDOT nanotube structure containing FeCl2 impurities was formed. Finally, the mixture was rinsed three times in 6M hydrochloric acid to obtain the first carrier transport layer 2.

[0147] The thickness of the PEDOT film (substrate 21) is 100 nm, the radius R of the nanotube structure 22 is 200 nm, the height H of the nanotube structure 22 is 800 nm, and the spacing D between the nanotube structures 22 is 2000 nm.

[0148] Step 3: Formation of the perovskite absorber layer 3: Dissolve 0.1 mmol of PbI2, 0.08 mmol of MAI, 0.2 ml of oleic acid, and 15 μl of n-octylamine in 2 ml of acetonitrile. After ultrasonic dispersion for 15 minutes, add the solution dropwise to 10 ml of toluene while stirring. After completion, centrifuge the solution at 7000 rpm for 15 minutes, discard the precipitate, and take the supernatant to obtain a toluene dispersion of MAPbI3 quantum dots with a particle size range of 5-10 nm.

[0149] The product obtained in step two is placed in a toluene dispersion of the MAPbI3 quantum dots, and a chemical bath deposition method is used to form a MAPbI3 perovskite quantum dot layer on the first carrier transport layer 2.

[0150] The thickness of the perovskite absorber layer 3 is 300 nm, the diameter of the quantum dots on the perovskite quantum dot layer is 5-10 nm, and the hot carrier lifetime τ hot The thermal carrier diffusion coefficient D is 150 ps. hot It is 1.8cm 2 / s, L can be calculated hot It is 164nm.

[0151] Step 4: Forming the second carrier transport layer 4: Using a spin-coating method, a 20 mg / ml PC61BM solution is spin-coated onto the perovskite absorber layer 3 at 2000 rpm for 30 seconds to obtain the second carrier transport layer 4. The thickness of the second carrier transport layer 4 is 50 nm.

[0152] Step 5: Forming the electrode layer: A thermal evaporation method is used, with an evaporation rate of: A 200 nm thick Al thin film was deposited on the second carrier transport layer 4 to obtain a complete perovskite hot carrier solar cell. The energy conversion efficiency of the solar cell is 24%.

[0153] Example 2

[0154] The difference between Example 2 and Example 1 is that the perovskite absorber layer 3 is a common perovskite absorber layer 3, using a non-quantum dot three-dimensional FAPbI3 thin film, and there are no quantum dots on the perovskite absorber layer 3. The efficiency of the solar cell is 20%.

[0155] Example 3

[0156] The difference between Example 3 and Example 1 lies in the type and materials of the first and second carrier transport layers:

[0157] In Example 3, the first carrier transport layer is a TiO2 electron transport layer. A 120 nm metallic Ti thin film is deposited on the FTO layer by vapor deposition. Then, the substrate with the Ti film is used as the anode and the Pt sheet is used as the cathode. The substrate is oxidized in an electrolyte of 0.5 wt% NH4F aqueous solution (pH = 4-5) at 18 V for 4 hours to obtain the TiO2 electron transport layer.

[0158] The parameters of the first carrier transport layer are as follows: the thickness of the substrate 21 is 80 nm, the radius R of the nanotube structure 22 is 250 nm, the height H of the nanotube structure 22 is 600 nm, and the spacing D between the nanotube structures 22 is 1800 nm.

[0159] The second carrier transport layer is prepared using Spiro-OMeTAD hole transport material by spin coating, with a thickness of 100 nm.

[0160] The solar cell has an energy conversion efficiency of 23%.

[0161] Example 4

[0162] The difference between Example 4 and Example 1 is that the first carrier transport layer uses NiO with a nanotube structure as the hole transport layer.

[0163] The solar cell has an energy conversion efficiency of 22%.

[0164] Example 5

[0165] The difference between Example 5 and Example 1 is that the materials of the first carrier transport layer and the second carrier transport layer are different.

[0166] The first carrier transport layer uses PTAA hole transport layer material with a nanotube structure.

[0167] The second carrier transport layer uses a tin oxide electron transport layer.

[0168] The solar cell has an energy conversion efficiency of 21%.

[0169] Example 6

[0170] The difference between Example 6 and Example 1 lies in the size characteristics of the PEDOT nanotubes and the type and size of the perovskite quantum dot material.

[0171] In this embodiment,

[0172] The dimensions of the first carrier transport layer, the PEDOT nanotube, are as follows:

[0173] The thickness of the substrate 21 is 80 nm, the radius R of the nanotube structure 22 is 180 nm, the height H of the nanotube structure 22 is 700 nm, and the spacing D between the nanotube structures 22 is 1500 nm.

[0174] The perovskite absorber layer uses FAPbI3 perovskite quantum dot absorber layer with the following parameters:

[0175] The thickness of the perovskite absorber layer 3 is 250 nm, the diameter of the quantum dots on the perovskite quantum dot layer is 3-8 nm, and the hot carrier lifetime τ hot The thermal carrier diffusion coefficient D is 200 ps. hot It is 1.3cm 2 / s, L can be calculated hot It is 161nm.

[0176] The solar cell has an energy conversion efficiency of 25%.

[0177] Comparative Example 1

[0178] Comparative Example 1 solar cell, such as Figure 3 As shown, the difference between Comparative Example 1 and Example 1 is that the first carrier transport layer, the perovskite absorber layer 3, and the second carrier transport layer in the solar cell of Comparative Example 1 are all planar. Specifically, the structure of the planar perovskite solar cell is as follows: Figure 3 As shown, the parameters are as follows:

[0179] The transparent conductive substrate layer is made of FTO conductive glass with an FTO thickness of 700nm;

[0180] The first carrier transport layer adopts a PEDOT planar dense hole transport layer with a thickness of 100nm;

[0181] The perovskite absorber layer is composed of 5-10 nm MAPbI3 quantum dots forming a perovskite thin film with a thickness of 300 nm.

[0182] The second carrier transport layer uses a PC61BM electron transport layer with a thickness of 50nm.

[0183] The electrode layer is made of Al and has a thickness of 200 nm;

[0184] The efficiency of the solar cell is 10%.

[0185] Table 1 shows the efficiency of the solar cells in each embodiment.

[0186]

[0187] Summary: As shown in Table 1, the efficiency of the solar cell described in this application is more than twice that of the solar cell in Comparative Example 1.

[0188] Although the embodiments of this application have been described above in conjunction with the specific embodiments described, this application is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the teachings of this specification and without departing from the scope of protection of the claims of this application, and these are all within the scope of protection of this application.

Claims

1. A solar cell, characterized in that, It includes a transparent conductive substrate layer, a first carrier transport layer, a perovskite absorption layer and a second carrier transport layer arranged sequentially. The first carrier transport layer includes a substrate layer and a plurality of spaced nanotube structures formed on the substrate layer and facing the perovskite absorber layer. The perovskite absorber layer covers the surface of the substrate layer opposite to the transparent conductive substrate layer, the outer surface of the nanotube structure, and the interior of the nanotube structure. The second carrier transport layer covers the surface of the perovskite absorber layer that is away from the first carrier transport layer; The first carrier transport layer is a hot carrier transport layer; The perovskite absorber layer is a perovskite quantum dot layer; The perovskite absorber layer comprises a perovskite surface layer and a perovskite filling layer. The perovskite surface layer uniformly covers the surface of the substrate layer and the outer surface of the nanotube structure. The perovskite filling layer completely fills the interior of the nanotube structure. The perovskite surface layer located at the top of the nanotube structure is seamlessly connected to the perovskite filling layer; The thickness of the perovskite surface layer is T. abs T abs ≤2L hot ; Where L hot =(D hot ×τ hot )1 / 2; L hot The diffusion length of hot carriers in the perovskite absorber layer at room temperature; D hot is the diffusion coefficient of hot carriers in the perovskite absorber layer at room temperature; τ hot The lifetime of hot carriers in the perovskite absorber layer at room temperature; L hot The wavelength is 70-300nm; τ hot 50-300ps; T abs The range is 140-600nm; The nanotube structure satisfies the following conditions: R≤T abs ; H≤1500nm; D>2T abs ; R is the radius of the nanotube structure; H is the height of the nanotube structure; D represents the spacing between adjacent nanotube structures.

2. The solar cell according to claim 1, characterized in that, The perovskite absorber layer has a columnar structure that encapsulates the nanotube structure and is spaced apart from each other.

3. The solar cell according to claim 1, characterized in that, The size of the quantum dots in the perovskite quantum dot layer is 1-30 nm; The perovskite quantum dot layer is selected from one of the following: organic-inorganic hybrid halide perovskite layer, all-inorganic halide perovskite layer, lead-free perovskite layer, or double perovskite layer.

4. The solar cell according to claim 3, characterized in that, The quantum dots are one or more of the following shapes: spherical, hemispherical, quasi-spherical, columnar, conical, and frustum-shaped.

5. The solar cell according to claim 1, characterized in that, Multiple nanotube structures are arranged in a matrix.

6. The solar cell according to claim 1, characterized in that, The surfaces of adjacent nanotube structures are covered with the perovskite surface layer and then have gaps; The second carrier transport layer covers the perovskite surface layer and the gap, and the side of the second carrier transport layer facing away from the perovskite absorber layer is planar.

7. The solar cell according to claim 1, characterized in that, The second carrier transport layer is a hot carrier transport layer.

8. The solar cell according to any one of claims 1-7, characterized in that, The first carrier transport layer and the second carrier transport layer have opposite conductivity types; one is a hot hole transport layer and the other is a hot electron transport layer. The first and second carrier transport layers are respectively selected from molybdenum oxide layer, PTAA layer, copper iodide layer or 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene layer, PEDOT layer, PEDOT:PSS layer, P3HT layer, P3OHT layer, P3ODDT layer, NiO layer, CuSCN layer, titanium oxide layer, tin oxide layer, C60 layer, C60 derivative layer, [6,6]-phenyl-C 61 - Isomethyl butyrate layer, [6,6]-phenyl-C 71 - One of the following: isomethyl butyrate layer, bis[60]PCBM layer or [60]ICBA layer.

9. A method for preparing a solar cell according to any one of claims 1-8, characterized in that, Includes the following steps: Provide a transparent conductive substrate layer; The first carrier transport layer is formed on one side surface of the transparent conductive substrate layer. The first carrier transport layer includes a base layer, on which a plurality of spaced nanotube structures are arranged facing the perovskite absorption layer. A perovskite absorption layer is formed on the side of the substrate layer opposite to the transparent conductive substrate layer, on the outer surface of the nanotube structure, and inside the nanotube structure. A second carrier transport layer is formed on the surface of the perovskite absorber layer that is opposite to the first carrier transport layer. The first carrier transport layer is a hot carrier transport layer.

10. The preparation method according to claim 9, characterized in that, The perovskite absorber layer comprises a perovskite surface layer and a perovskite filling layer. The perovskite surface layer uniformly covers the surface of the substrate layer and the outer surface of the nanotube structure. The perovskite filling layer completely fills the interior of the nanotube structure. The perovskite surface layer located at the top of the nanotube structure is seamlessly connected to the perovskite filling layer.

11. The preparation method according to claim 9, characterized in that, After the surfaces of adjacent nanotube structures are covered by the perovskite surface layer, there are gaps. The second charge carrier transport layer is formed in the perovskite surface layer and the gaps, and the side surface of the second charge carrier transport layer facing away from the perovskite absorption layer is planar.

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