Perovskite solar cell and preparation method thereof

Abstract

The invention provides a perovskite solar cell and a preparation method thereof, and particularly relates to the technical field of solar cells. The perovskite solar cell comprises a conductive glass substrate, and an electron transport layer, a perovskite light absorption layer, a molecular modification layer, a hole transport layer and a metal electrode which are sequentially stacked on the conductive glass substrate, the molecular modification layer comprises a benzyltriethylammonium one-dimensional lead halide structure. A molecular modification layer is arranged on a perovskite light absorption layer or the perovskite light absorption layer and the molecular modification layer are integrated into a perovskite composite light absorption layer, so that a benzyltriethylammonium one-dimensional lead halide structure is successfully introduced. And a benzyltriethylammonium one-dimensional lead halide structure in the molecular modification layer is used as a hydrophobic barrier, so that water and oxygen erosion can be effectively blocked, a dimensional mutual dissolution reaction with the three-dimensional perovskite can be avoided, and the environmental stability of the device is remarkably improved. The photoelectric conversion efficiency of the device is improved in a breakthrough manner, and the device is endowed with excellent operation stability and process repeatability.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a perovskite solar cell and a preparation method thereof. Background Art

[0002] Perovskite solar cells, with their unique optoelectronic properties (tunable bandgap, high absorption coefficient) and manufacturing advantages (low-temperature solution processing, low raw material cost), have increased their certified efficiency to 27.0% in more than a decade, showing industrialization potential beyond traditional crystalline silicon technology. However, there are still multi-dimensional scientific challenges in this technology system that need to be broken through urgently.

[0003] From the perspective of the intrinsic properties of the material, lattice defects (such as surface dangling bonds, grain boundary dislocations) formed during the solution preparation process lead to increased non-radiative recombination of carriers, severely restricting the open-circuit voltage and fill factor of the device. At the same time, the chemical decomposition mechanism of perovskite materials under environmental water and oxygen erosion, as well as the migration behavior of halogen ions under working conditions, constitute fundamental challenges to the long-term stability of the device. It is worth noting that the existing dimensional engineering strategies show obvious technical contradictions when solving the above problems: although two-dimensional / three-dimensional heterostructures can enhance stability through quantum confinement effects, the mixed-dimensional phase transition formed by spontaneous phase separation at the heterointerface will reconstruct the ion diffusion path and accelerate the degradation of the active layer; while the one-dimensional structure design can relieve mechanical stress through lattice matching, but due to the fracture of the carrier migration channel and the mismatch of interface energy levels, the charge transport barrier increases, forming a new type of recombination center.

[0004] This antagonistic relationship between material dimensional regulation and optoelectronic properties essentially reflects the deep contradiction between structural stability and carrier transport dynamics in the perovskite system. How to construct a multi-scale structure that can both inhibit ion migration and maintain efficient charge transport has become the key technical bottleneck for breaking through the current efficiency-stability balance problem.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] One of the purposes of the present invention is to provide a perovskite solar cell to solve at least one of the above technical problems in the prior art.

[0007] Another purpose of the present invention is to provide a preparation process for a perovskite solar cell.

[0008] To achieve the above purposes of the present invention, the following technical solutions are specifically adopted:

[0009] The first aspect of the present invention provides a perovskite solar cell, including a conductive glass substrate, and an electron transport layer, a perovskite light-absorbing layer, a molecular modification layer, a hole transport layer, and a metal electrode sequentially stacked on the conductive glass substrate;

[0010] The molecular modification layer includes a benzyltriethylammonium one-dimensional lead halide structure.

[0011] Further, the benzyltriethylammonium one-dimensional lead halide structure is formed by benzyltriethylammonium halide and lead halide.

[0012] The general formula of the benzyltriethylammonium one-dimensional lead halide structure is CMX3; where C is the benzyltriethylammonium ion, M is Pb 2+ lead ion, and X is a halogen ion;

[0013] Preferably, the halogen ion includes Cl - , Br - and I - and at least one of them.

[0014] Further, the conductive glass substrate is FTO.

[0015] Preferably, the material of the electron transport layer is TiO2 or SnO2.

[0016] Preferably, the material of the hole transport layer is Spiro-OMeTAD.

[0017] Preferably, the material of the metal electrode is Ag or Au.

[0018] Further, the material of the perovskite light-absorbing layer is an ABX3-type compound;

[0019] wherein, A is a monovalent organic cation, B is a divalent metal ion, and X is a halogen ion.

[0020] Further, the monovalent organic cation includes MA + , FA + , Cs + and K + and at least one of them.

[0021] Preferably, the divalent metal ion includes Pb 2+ and / or Sn 2+ .

[0022] Preferably, the halogen ion includes Cl - , Br - and I - and at least one of them.

[0023] Further, the thickness of the electron transport layer is 10 - 200 nm.

[0024] Preferably, the thickness of the perovskite light-absorbing layer is 100 - 1000 nm.

[0025] Preferably, the thickness of the molecular modification layer is 1 - 50 nm.

[0026] Preferably, the thickness of the hole transport layer is 50 - 300 nm.

[0027] Preferably, the thickness of the metal electrode is 80 - 200 nm.

[0028] In a second aspect of the present invention, there is provided a method for preparing the perovskite solar cell, which comprises sequentially preparing an electron transport layer, a perovskite light-absorbing layer, a molecular modification layer, a hole transport layer, and a metal electrode on a conductive glass substrate to obtain the perovskite solar cell;

[0029] The method for preparing the molecular modification layer is as follows: A benzyltriethylammonium halide solution is first coated on the perovskite light-absorbing layer, and then a first heat treatment is performed to obtain the molecular modification layer.

[0030] Further, the concentration of the benzyltriethylammonium halide solution is 0.1 - 10 mg / mL, preferably 0.5 - 5 mg / mL.

[0031] Preferably, the solvent in the benzyltriethylammonium halide solution includes at least one of acetonitrile, isopropanol, methanol, ethanol, dimethoxyethanol, and chloroform.

[0032] Preferably, the temperature of the first heat treatment is 100 - 150 °C, and the time is 2 - 60 min.

[0033] Preferably, the first coating method is spin coating.

[0034] Preferably, the spin coating speed is 3000 - 6000 rpm, and the time is 20 - 60 s.

[0035] Further, the method for preparing the perovskite light-absorbing layer is as follows: A perovskite precursor solution is second-coated onto the electron transport layer, and then a second heat treatment is performed to obtain the perovskite light-absorbing layer.

[0036] Preferably, the solvent in the perovskite precursor solution includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, γ-butyrolactone, and 2-mercaptoethanol.

[0037] Preferably, the concentration of the perovskite precursor solution is 1.0 - 1.7 M.

[0038] Preferably, the temperature of the second heat treatment is 100 - 150 °C, and the time is 10 - 60 min.

[0039] Preferably, the second coating includes spin coating.

[0040] Preferably, the rotation speed of the spin coating is 3000 - 6000 rpm, and the time is 20 - 60 s.

[0041] Preferably, the thickness of the perovskite light absorption layer is 100 - 1000 nm.

[0042] In the third aspect of the present invention, another perovskite solar cell is provided, which uses a perovskite composite light absorption layer to replace the perovskite light absorption layer and the molecular modification layer in the perovskite solar cell structure described in the first aspect;

[0043] The perovskite composite light absorption layer includes perovskite and a benzyltriethylammonium one-dimensional lead halide structure.

[0044] In the fourth aspect of the present invention, the preparation method of the perovskite composite light absorption layer is as follows: an electron transport layer, a perovskite composite light absorption layer, a hole transport layer and a metal electrode are sequentially prepared on a conductive glass substrate to obtain a perovskite solar cell;

[0045] The preparation method of the perovskite composite light absorption layer is as follows: benzyltriethylammonium halide is added to a perovskite precursor solution, and the mixture is uniformly mixed to obtain a perovskite composite solution; the perovskite composite solution is subjected to a third coating on the electron transport layer, and then a third heat treatment is performed to obtain the perovskite composite light absorption layer.

[0046] Furthermore, in the perovskite composite solution, the concentration of the benzyltriethylammonium halide solution is 0.1 - 10 mg / mL, preferably 0.2 - 5 mg / mL.

[0047] Preferably, the solvent in the perovskite precursor solution includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, γ-butyrolactone and 2-mercaptoethanol.

[0048] Preferably, the temperature of the third heat treatment is 100 - 150 °C, and the time is 10 - 60 min.

[0049] Preferably, the manner of the third coating is spin coating.

[0050] Preferably, the speed of the spin coating is 3000 - 6000 rpm, and the time is 20 - 60 s.

[0051] Preferably, the thickness of the perovskite composite light absorption layer is 100 - 1000 nm.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] The perovskite solar cell provided by the present invention successfully introduces a benzyltriethylammonium one-dimensional lead halide structure by setting a molecular modification layer on the perovskite light-absorbing layer or integrating the perovskite light-absorbing layer with the molecular modification layer into a perovskite composite light-absorbing layer. The benzyltriethylammonium one-dimensional lead halide structure in the molecular modification layer, as a hydrophobic barrier, can not only effectively block the erosion of water and oxygen, but also avoid the dimensional miscibility reaction with the three-dimensional perovskite, significantly improving the environmental stability of the device. In the perovskite composite light-absorbing layer, a continuous one-dimensional network structure is self-organized at the grain boundaries, reducing the grain boundary dislocation density and inhibiting ion migration through lattice anchoring. At the same time, the benzyltriethylammonium one-dimensional lead halide structure constructs a cross-dimensional charge transport channel through a π-π conjugated framework, and synchronously utilizes the N atom at the molecular end to bind to the uncoordinated lead defects on the perovskite surface, achieving dual gains in optimizing the carrier transport dynamics and suppressing non-radiative recombination. This multi-target regulation at the molecular scale ultimately synergistically realizes a breakthrough improvement in the photoelectric conversion efficiency of the device and endows it with excellent operating stability and process reproducibility.

[0054] The preparation method provided by the present invention, whether preparing the perovskite light-absorbing layer and the molecular modification layer separately or directly preparing the perovskite composite light-absorbing layer, adopts a solution coating process, which has a high compatibility with the existing perovskite solar cell preparation technology and can be directly integrated into the existing perovskite device production line without complex equipment modification. The heat treatment process avoids the risk of damaging the perovskite lattice structure by high-temperature annealing. At the same time, the directional self-assembly behavior of benzyltriethylammonium halide during the heat treatment process realizes the in-situ transformation from disordered adsorption to an ordered one-dimensional structure. In addition, the process window of the coating process is wide, which is beneficial to improving the process stability and the yield rate in large-scale production, providing technical feasibility for the low-cost continuous production of perovskite modules. Description of the Drawings

[0055] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0056] Figure 1 It is a schematic structural diagram of the perovskite solar cell provided in Embodiment 1 of the present invention;

[0057] Figure 2 It is a schematic structural diagram of the perovskite solar cell provided in Embodiment 2 of the present invention;

[0058] Figure 3 It is a schematic structural diagram of the perovskite solar cell provided in Embodiment 3 of the present invention;

[0059] Figure 4 Schematic diagram of the structure of the perovskite solar cell provided in Embodiment 4 of the present invention;

[0060] Figure 5 Current-voltage curve of the perovskite solar cell prepared in Embodiment 5 of the present invention;

[0061] Figure 6 Comparison chart of the stability of the perovskite solar cells prepared in Embodiment 5 and Comparative Example 1 of the present invention;

[0062] Figure 7 Current-voltage curve of the perovskite solar cell prepared in Embodiment 6 of the present invention;

[0063] Figure 8 Current-voltage curve of the perovskite solar cell prepared in Embodiment 7 of the present invention;

[0064] Figure 9 Current-voltage curve of the perovskite solar cell prepared in Embodiment 8 of the present invention;

[0065] Figure 10 Current-voltage curve of the perovskite solar cell prepared in Embodiment 9 of the present invention;

[0066] Figure 11 Current-voltage curve of the perovskite solar cell prepared in Embodiment 10 of the present invention;

[0067] Figure 12 Current-voltage curve of the perovskite solar cell prepared in Embodiment 11 of the present invention;

[0068] Figure 13 Current-voltage curve of the perovskite solar cell prepared in Embodiment 12 of the present invention;

[0069] Figure 14 Current-voltage curve of the perovskite solar cell prepared in Embodiment 13 of the present invention;

[0070] Figure 15 Schematic diagram of the structure of the perovskite solar cell provided in Comparative Example 1 of the present invention;

[0071] Figure 16 Current-voltage curve of the perovskite solar cell prepared in Comparative Example 1 of the present invention;

[0072] Figure 17 SEM image of the perovskite composite light-absorbing layer prepared in Embodiment 10 of the present invention;

[0073] Figure 18SEM image of the perovskite light-absorbing layer prepared in Comparative Example 1 of the present invention;

[0074] Figure 19 Both a and b in are the one-dimensional lead halide structure diagrams of benzyltriethylammonium; Figure 19 c in is the simulated XRD pattern of the one-dimensional lead halide structure of benzyltriethylammonium; Figure 19 d in is the XRD pattern of the simulated XRD of the one-dimensional lead halide structure of benzyltriethylammonium and the perovskite composite light-absorbing layer.

[0075] Icon: 100 - Conductive glass substrate; 200 - Electron transport layer; 300 - Perovskite light-absorbing layer; 400 - Molecular modification layer; 500 - Hole transport layer; 600 - Metal electrode; 700 - Perovskite composite light-absorbing layer. Detailed implementation manners

[0076] The implementation manners of the present invention will be described in detail below in combination with the implementation manners and examples. However, those skilled in the art will understand that the following implementation manners and examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. All other examples obtained by those of ordinary skill in the art based on the examples in the present invention without creative efforts belong to the scope protected by the present invention.

[0077] As used herein, the "perovskite solar cell" or "perovskite cell" of the present invention includes, but is not limited to, formal perovskite cells, formal perovskite modules, inverted perovskite cells, inverted perovskite modules, small-area perovskite cells, small-area perovskite modules, single-junction perovskite cells, single-junction perovskite modules, perovskite-organic tandem cells, perovskite-organic tandem modules, perovskite-perovskite tandem cells, perovskite-perovskite tandem modules, perovskite-silicon tandem cells, perovskite-silicon tandem modules, perovskite-CIGS tandem cells, perovskite-CIGS tandem modules.

[0078] The first aspect of the present invention provides a perovskite solar cell, comprising a conductive glass substrate 100, and an electron transport layer 200, a perovskite light-absorbing layer 300, a molecular modification layer 400, a hole transport layer 500 and a metal electrode 600;

[0079] The molecular modification layer 400 includes a one-dimensional lead halide structure of benzyltriethylammonium.

[0080] In one implementation manner of the present invention, the perovskite solar cell includes a conductive glass substrate 100, and an electron transport layer 200, a perovskite light-absorbing layer 300, a molecular modification layer 400, a hole transport layer 500 and a metal electrode 600 which are sequentially stacked on the conductive glass substrate 100;

[0081] The molecular modification layer 400 includes a benzyltriethylammonium one-dimensional lead halide structure.

[0082] In another embodiment of the present invention, the perovskite solar cell includes a conductive glass substrate 100, and a hole transport layer 500, a perovskite light-absorbing layer 300, a molecular modification layer 400, an electron transport layer 200, and a metal electrode 600 that are sequentially stacked on the conductive glass substrate 100;

[0083] The molecular modification layer 400 includes a benzyltriethylammonium one-dimensional lead halide structure.

[0084] The third aspect of the present invention provides another perovskite solar cell, which uses a perovskite composite light-absorbing layer 700 to replace the perovskite light-absorbing layer 300 and the molecular modification layer 400 in the perovskite solar cell structure described in the first aspect;

[0085] The perovskite composite light-absorbing layer 700 includes perovskite and a benzyltriethylammonium one-dimensional lead halide structure.

[0086] The perovskite solar cell provided by the present invention successfully introduces a benzyltriethylammonium one-dimensional lead halide structure by disposing a molecular modification layer 400 on the perovskite light-absorbing layer 300 or integrating the perovskite light-absorbing layer 300 and the molecular modification layer 400 into a perovskite composite light-absorbing layer 700.

[0087] The benzyltriethylammonium one-dimensional lead halide structure in the molecular modification layer 400, as a hydrophobic barrier, can not only effectively block the erosion of water and oxygen, but also avoid the dimensional mutual dissolution reaction with the three-dimensional perovskite, significantly improving the environmental stability of the device.

[0088] The perovskite composite light-absorbing layer 700 has a π-π conjugate system, which is beneficial to charge transfer between interfaces and improves the photoelectric conversion efficiency of the device; at the same time, the N atom in the molecule can interact with the surface defects of the perovskite light-absorbing layer 300, thereby suppressing the recombination of carriers and further improving the device efficiency.

[0089] Furthermore, the benzyltriethylammonium one-dimensional lead halide structure is formed by benzyltriethylammonium halide and lead halide.

[0090] The general formula of the benzyltriethylammonium one-dimensional lead halide structure is CMX3; where C is the benzyltriethylammonium ion, M is the Pb 2+ lead ion, and X is a halogen ion.

[0091] Preferably, the halogen ion includes Cl - , Br - and I - and at least one of them.

[0092] Furthermore, the conductive glass substrate 100 is FTO.

[0093] FTO glass, also known as Fluorine-doped Tin Oxide glass, is a semiconductor material. It obtains conductivity by depositing a layer of fluorine-doped tin oxide film on the surface of ordinary glass.

[0094] Preferably, the material of the electron transport layer 200 is TiO2 or SnO2.

[0095] Preferably, the material of the hole transport layer 500 is Spiro-OMeTAD. Spiro-OMeTAD is 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene.

[0096] Preferably, the material of the metal electrode 600 is Ag or Au.

[0097] Furthermore, the material of the perovskite light-absorbing layer 300 is an ABX3-type compound;

[0098] wherein, A is a monovalent organic cation, B is a divalent metal ion, and X is a halogen ion.

[0099] Furthermore, the monovalent organic cation includes MA + , FA + , Cs + and K + and at least one of them.

[0100] It should be noted that MA + is methylammonium ion, with the chemical formula CH3NH3 + ; FA + is formamidinium ion, with the chemical formula H2NCHNH3 + .

[0101] Preferably, the divalent metal ion includes Pb 2+ and / or Sn 2+ .

[0102] Preferably, the halogen ion includes Cl - , Br - and I - and at least one of them.

[0103] Furthermore, the thickness of the electron transport layer 200 is 10 - 200 nm.

[0104] Preferably, the thickness of the perovskite light-absorbing layer 300 is 100 - 1000 nm.

[0105] Preferably, the thickness of the molecular modification layer 400 is 1 - 50 nm.

[0106] Preferably, the thickness of the hole transport layer 500 is 50 - 300 nm.

[0107] Preferably, the thickness of the metal electrode 600 is 80 - 200 nm.

[0108] In a second aspect of the present invention, there is provided a method for preparing the perovskite solar cell, which comprises sequentially preparing an electron transport layer 200, a perovskite light absorption layer 300, a molecular modification layer 400, a hole transport layer 500 and a metal electrode 600 on a conductive glass substrate 100 to obtain the perovskite solar cell;

[0109] The method for preparing the molecular modification layer 400 is as follows: coating a benzyltriethylammonium halide solution on the perovskite light absorption layer 300 for the first time, and then performing a first heat treatment to obtain the molecular modification layer 400.

[0110] Furthermore, the concentration of the benzyltriethylammonium halide solution is 0.1 - 10 mg / mL, preferably 0.5 - 5 mg / mL.

[0111] Typically but not restrictively, the concentration of the benzyltriethylammonium halide solution can be, for example, 0.1 mg / mL, 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL or 10 mg / mL, or any value within the range of 0.1 - 10 mg / mL. Among them, the preferred concentration range can be, for example, 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL or 5 mg / mL, or any value within the range of 0.5 - 5 mg / mL.

[0112] Preferably, the solvent in the benzyltriethylammonium halide solution includes at least one of acetonitrile, isopropanol, methanol, ethanol, dimethoxyethanol and chloroform.

[0113] Preferably, the temperature of the first heat treatment is 100 - 150 °C, and the time is 2 - 60 min.

[0114] Typically but not restrictively, the temperature of the first heat treatment can be, for example, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C or 150 °C, or any value within the range of 100 °C - 150 °C; the time of the heat treatment can be, for example, 2 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, or any value within the range of 2 - 60 min.

[0115] Preferably, the first coating is performed by spin coating.

[0116] Preferably, the speed of the spin coating is 3000 - 6000 rpm, and the time is 20 - 60 s.

[0117] Typically but not limited to, the speed of the spin coating can be, for example, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm or 6000 rpm, or any value within the range of 3000 - 6000 rpm; the time of the spin coating can be, for example, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s or 60 s, or any value within the range of 20 - 60 s.

[0118] Furthermore, the preparation method of the perovskite light - absorbing layer 300 is as follows: the perovskite precursor solution is second - coated onto the electron - transporting layer 200, and then second - heat - treated to obtain the perovskite light - absorbing layer 300.

[0119] Preferably, the solvent in the perovskite precursor solution includes at least one of N,N - dimethylformamide, dimethyl sulfoxide, N - methylpyrrolidone, γ - butyrolactone and 2 - mercaptoethanol.

[0120] Preferably, the concentration of the perovskite precursor solution is 1.0 - 1.7 M.

[0121] Preferably, the temperature of the second heat - treatment is 100 - 150 °C, and the time is 10 - 60 min.

[0122] Typically but not limited to, the temperature of the second heat - treatment can be, for example, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C or 150 °C, or any value within the range of 100 °C - 150 °C; the time of the heat - treatment can be, for example, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, or any value within the range of 10 - 60 min.

[0123] Preferably, the second coating includes spin coating.

[0124] Preferably, the speed of the spin coating is 3000 - 6000 rpm, and the time is 20 - 60 s.

[0125] Typically but not restrictively, the spin coating speed can be, for example, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm or 6000 rpm, or can also be any value within the range of 3000 to 6000 rpm; the spin coating time can be, for example, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s or 60 s, or can also be any value within the range of 20 to 60 s.

[0126] Preferably, the thickness of the perovskite light-absorbing layer is 100 to 1000 nm.

[0127] Typically but not restrictively, the thickness of the perovskite light-absorbing layer can be, for example, 100 nm, 200 nm, 300 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 900 nm or 1000 nm, or can also be any value within the range of 100 nm to 1000 nm.

[0128] The fourth aspect of the present invention provides that the preparation method of the perovskite composite light-absorbing layer 700 is: sequentially preparing an electron transport layer 200, a perovskite composite light-absorbing layer 700, a hole transport layer 500 and a metal electrode 600 on a conductive glass substrate 100 to obtain a perovskite solar cell;

[0129] The preparation method of the perovskite composite light-absorbing layer 700 is: adding benzyltriethylammonium halide to a perovskite precursor solution, and mixing evenly to obtain a perovskite composite solution; coating the perovskite composite solution on the electron transport layer 200 for the third time, and then performing a third heat treatment to obtain the perovskite composite light-absorbing layer 700.

[0130] Mixing benzyltriethylammonium halide into the perovskite precursor solution can react with the residual lead iodide to in-situ form a one-dimensional structure at the grain boundaries of the perovskite thin film, reducing grain boundary defects.

[0131] When preparing the perovskite composite solution, the stirring temperature is 25 to 100 °C, and the time is 0.5 to 5 h. Adding benzyltriethylammonium halide can be carried out by using a benzyltriethylammonium halide solution. Here, the solvent used in the benzyltriethylammonium halide solution is dimethyl sulfoxide to ensure compatibility with the perovskite precursor solution system.

[0132] Typically but not restrictively, the stirring temperature can be, for example, 25 °C, 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C or 100 °C, or can also be any value within the range of 25 °C to 100 °C; the stirring time can be, for example, 0.5 h, 1 h, 2 h, 3 h, 4 h or 5 h, or can also be any value within the range of 0.5 to 5 h.

[0133] Further, in the perovskite composite solution, the concentration of the benzyltriethylammonium halide solution is 0.1 - 10 mg / mL, preferably 0.2 - 5 mg / mL.

[0134] Typically but not restrictively, in the perovskite composite solution, the concentration of the benzyltriethylammonium halide solution can be, for example, 0.1 mg / mL, 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL or 10 mg / mL, or any value within the range of 0.1 - 10 mg / mL. Among them, the preferred concentration range can be, for example, 0.2 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL or 5 mg / mL, or any value within the range of 0.2 - 5 mg / mL.

[0135] Further, the concentration of the perovskite precursor solution is 1.0 - 1.7 M.

[0136] Typically but not restrictively, the concentration of the perovskite precursor solution can be, for example, 1.0 M, 1.1 M, 1.2 M, 1.3 M, 1.4 M, 1.5 M, 1.6 M or 1.7 M, or any value within the range of 1.0 - 1.7 M.

[0137] During the preparation process, in an anhydrous and anaerobic environment, the perovskite precursor is dissolved in a solvent and heated and stirred at 25 - 100 °C for 1 - 12 h to form a perovskite precursor solution with a concentration of 1.0 - 1.7 M.

[0138] Preferably, the solvent in the perovskite precursor solution includes at least one of N,N - dimethylformamide, dimethyl sulfoxide, N - methylpyrrolidone, γ - butyrolactone and 2 - mercaptoethanol.

[0139] Preferably, the temperature of the third heat treatment is 100 - 150 °C and the time is 10 - 60 min.

[0140] Typically but not restrictively, the temperature of the third heat treatment can be, for example, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C or 150 °C, or any value within the range of 100 °C - 150 °C; the time of the third heat treatment can be, for example, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, or any value within the range of 10 - 60 min.

[0141] Preferably, the third coating includes spin coating.

[0142] Preferably, the rotation speed of the spin coating is 3000 - 6000 rpm, and the time is 20 - 60 s.

[0143] Typically but not restrictively, the speed of the spin coating can be, for example, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm or 6000 rpm, or any value within the range of 3000 - 6000 rpm; the time of the spin coating can be, for example, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s or 60 s, or any value within the range of 20 - 60 s.

[0144] Preferably, the thickness of the perovskite composite light - absorbing layer is 100 - 1000 nm.

[0145] Typically but not restrictively, the thickness of the perovskite light - absorbing layer can be, for example, 100 nm, 200 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 900 nm or 1000 nm, or any value within the range of 100 nm - 1000 nm.

[0146] For the preparation method provided by the present invention, whether preparing the perovskite light - absorbing layer 300 and the molecular modification layer 400 separately or directly preparing the perovskite composite light - absorbing layer 700, a solution coating process is adopted, which has a high compatibility with the existing perovskite solar cell preparation technology and can be directly integrated into the existing perovskite device production line without complex equipment modification. The heat treatment process avoids the risk of damage to the perovskite lattice structure caused by high - temperature annealing. At the same time, the directional self - assembly behavior of benzyltriethylammonium halide molecules during the heat treatment process realizes the in - situ transformation from disordered adsorption to an ordered one - dimensional structure. In addition, the process window of the coating process is relatively wide, which is beneficial to improving the process stability and the yield rate in large - scale production, providing technical feasibility for the low - cost continuous production of perovskite components.

[0147] Furthermore, the material of the electron - transporting layer 200 is TiO2 or SnO2.

[0148] In some embodiments of the present invention, the preparation method of using TiO2 as the material of the electron - transporting layer 200 is the CBD chemical bath deposition method, the hydrothermal temperature is 50 - 90 °C, and the annealing temperature is 90 - 150 °C.

[0149] When SnO2 is used as the material of the electron - transporting layer 200, the preparation method of the electron - transporting layer 200 is to spin - coat the SnO2 solution. The rotation speed of the spin coating is 1000 - 4000 rpm; the annealing temperature is 80 - 150 °C.

[0150] Typically but not limited thereto, the rotation speed of spin coating can be, for example, 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm or 4000 rpm, or can also be any value within the range of 1000 to 4000 rpm.

[0151] The annealing temperature can be, for example, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C or 150 °C, or can also be any value within the range of 80 °C to 150 °C.

[0152] The present invention will be further described below through specific examples and comparative examples. However, it should be understood that these examples are only for more detailed description and should not be construed as limiting the present invention in any form. For the raw materials used in the examples and comparative examples of the present invention, if no specific conditions are indicated, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments used, if the manufacturer is not indicated, they are all conventional products that can be obtained by purchasing in the market.

[0153] Example 1

[0154] This example provides a perovskite solar cell, the structural schematic diagram of which is as Figure 1 shown, including a conductive glass substrate 100, and an electron transport layer 200, a perovskite light-absorbing layer 300, a molecular modification layer 400, a hole transport layer 500 and a metal electrode 600 that are sequentially stacked on the conductive glass substrate 100;

[0155] The molecular modification layer 400 includes a benzyltriethylammonium one-dimensional lead halide structure.

[0156] The thickness of the electron transport layer 200 is 100 nm; the thickness of the perovskite light-absorbing layer 300 is 500 nm; the thickness of the molecular modification layer 400 is 20 nm; the thickness of the hole transport layer 500 is 170 nm; the thickness of the metal electrode 600 is 100 nm.

[0157] Example 2

[0158] This example provides a perovskite solar cell, the structural schematic diagram of which is as Figure 2 shown, including a conductive glass substrate 100, and a hole transport layer 500, a perovskite light-absorbing layer 300, a molecular modification layer 400, an electron transport layer 200 and a metal electrode 600 that are sequentially stacked on the conductive glass substrate 100;

[0159] The molecular modification layer 400 includes a benzyltriethylammonium one-dimensional lead halide structure.

[0160] The thickness of the hole transport layer 500 is 170 nm; the thickness of the perovskite light-absorbing layer 300 is 500 nm; the thickness of the molecular modification layer 400 is 20 nm; the thickness of the electron transport layer 200 is 100 nm; the thickness of the metal electrode 600 is 100 nm.

[0161] Example 3

[0162] This example provides a perovskite solar cell, and its structural schematic diagram is as Figure 3 shown, including a conductive glass substrate 100, and an electron transport layer 200, a perovskite composite light-absorbing layer 700, a hole transport layer 500, and a metal electrode 600 that are sequentially stacked on the conductive glass substrate 100.

[0163] The perovskite composite light-absorbing layer 700 includes perovskite and a benzyltriethylammonium one-dimensional lead halide structure.

[0164] The thickness of the electron transport layer 200 is 100 nm; the thickness of the perovskite composite light-absorbing layer 700 is 500 nm; the thickness of the hole transport layer 500 is 170 nm; the thickness of the metal electrode 600 is 100 nm.

[0165] Example 4

[0166] This example provides a perovskite solar cell, and its structural schematic diagram is as Figure 4 shown, including a conductive glass substrate 100, and a hole transport layer 500, a perovskite composite light-absorbing layer 700, an electron transport layer 200, and a metal electrode 600 that are sequentially stacked on the conductive glass substrate 100;

[0167] The perovskite composite light-absorbing layer 700 includes perovskite and a benzyltriethylammonium one-dimensional lead halide structure.

[0168] The thickness of the hole transport layer 500 is 170 nm; the thickness of the perovskite composite light-absorbing layer 700 is 500 nm; the thickness of the electron transport layer 200 is 100 nm; the thickness of the metal electrode 600 is 100 nm.

[0169] Example 5

[0170] This example provides a preparation method of the perovskite solar cell of Example 1, and the specific process is as follows:

[0171] 1. Cleaning of the conductive glass substrate 100: The purchased FTO glass is ultrasonically treated with deionized water, acetone, and absolute ethanol in sequence, the ultrasonic time is 30 min, the glass surface is cleaned, and it is dried with nitrogen for standby.

[0172] 2. Preparation of the electron transport layer 200: Place the FTO glass in ultraviolet ozone for 15 minutes. Then, take 850 μL of TiCl4 solution and slowly add it dropwise to a glass vial containing 40 mL of ultrapure water (the vial was pre-frozen to the ice state). After the ice has completely melted, transfer the mixed solution to a petri dish. Place the petri dish in an oven at 70 °C for hydrothermal treatment for 50 min. After the reaction is completed, wash the residual TiCl4 on the surface of the substrate with ultrapure water, and then place it in an oven at 150 °C for annealing for 1 h to finally obtain a TiO2 thin film.

[0173] 3. Preparation of the perovskite light-absorbing layer 300: In an anhydrous and anaerobic environment, dissolve CsI, MABr, FAI, PbI2, and MACl in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1 according to a molar ratio of 0.05:0.09:0.85:0.955:0.02, and stir at 55 °C for 2 h. After filtering through an organic filter head, obtain a 1.55 M perovskite precursor solution Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.97 Br 0.03 )3. Take 25 μL of the perovskite precursor solution and drop it onto the conductive glass substrate 100 coated with the electron transport layer 200. The spin-coating speed is 4000 rpm, and the spin-coating time is 30 s. Add 200 μL of ethyl acetate in the last 10 s before the end of spin-coating. After spin-coating, anneal at 130 °C for 10 min to obtain the perovskite light-absorbing layer 300.

[0174] 4. Preparation of the molecular modification layer 400: In an anhydrous and anaerobic environment, stir and dissolve benzyltriethylammonium iodide molecules in isopropanol solvent at room temperature to obtain a solution with a concentration of 1.5 mg / mL. Take 40 μL of the benzyltriethylammonium iodide solution and drop it onto the perovskite light-absorbing layer 300. The spin-coating speed is 4000 rpm, and the spin-coating time is 30 s. After spin-coating, heat-treat at 100 °C for 2 min to obtain the molecular modification layer 400.

[0175] 5. Preparation of the hole transport layer 500: After thoroughly mixing the chlorobenzene solution of the hole transport material Spiro-OMeTAD, take 25 μL and drop it onto the molecular modification layer 400. The spin-coating speed is 4000 rpm, and the spin-coating time is 30 s to obtain the hole transport layer 500.

[0176] 6. Preparation of the metal electrode 600 layer: Using the thermal evaporation method, evaporate 80 nm of silver above the hole transport layer 500.

[0177] Perform performance tests on the prepared perovskite solar cell, and its photoelectric conversion efficiency is 24.11%; Figure 5Current-voltage curve of the perovskite solar cell prepared in Example 5. As Figure 6 shown, Example 5 has better stability compared to Comparative Example 1.

[0178] Example 6

[0179] This example provides another preparation method of the perovskite solar cell of Example 1. Different from Example 5, in step 3, the concentration of the benzyltriethylammonium iodide solution is 0.5 mg / mL, and the other raw materials and preparation steps are the same as those in Example 5, which will not be elaborated here.

[0180] The prepared perovskite solar cell was subjected to performance testing, and its photoelectric conversion efficiency was 23.73%; Figure 7 Current-voltage curve of the perovskite solar cell prepared in Example 6.

[0181] Example 7

[0182] This example provides another preparation method of the perovskite solar cell of Example 1. Different from Example 5, in step 3, the concentration of the benzyltriethylammonium iodide solution is 3 mg / mL, and the other raw materials and preparation steps are the same as those in Example 5, which will not be elaborated here.

[0183] The prepared perovskite solar cell was subjected to performance testing, and its photoelectric conversion efficiency was 23.23%; Figure 8 Current-voltage curve of the perovskite solar cell prepared in Example 7.

[0184] Example 8

[0185] This example provides another preparation method of the perovskite solar cell of Example 1. Different from Example 5, in step 3, benzyltriethylammonium chloride is used to replace benzyltriethylammonium iodide, and the other raw materials and preparation steps are the same as those in Example 5, which will not be elaborated here.

[0186] The prepared perovskite solar cell was subjected to performance testing, and its photoelectric conversion efficiency was 23.76%. Figure 9 Current-voltage curve of the perovskite solar cell prepared in Example 8.

[0187] Example 9

[0188] This example provides another preparation method of the perovskite solar cell of Example 1. Different from Example 5, in step 3, benzyltriethylammonium bromide is used to replace benzyltriethylammonium iodide, and the other raw materials and preparation steps are the same as those in Example 5, which will not be elaborated here.

[0189] The prepared perovskite solar cell was subjected to performance testing, and its photoelectric conversion efficiency was 23.54%.Figure 10 Current-voltage curve of the perovskite solar cell prepared in Example 9.

[0190] Example 10

[0191] This example provides a preparation method of the perovskite solar cell of Example 3. The specific process is as follows:

[0192] 1-2: The same steps as in Example 5.

[0193] 3. Prepare the perovskite composite light-absorbing layer 700: In an anhydrous and oxygen-free environment, stir and dissolve benzyltriethylammonium iodide molecules in dimethyl sulfoxide solvent at room temperature to obtain a benzyltriethylammonium iodide solution with a concentration of 0.5 mg / mL.

[0194] In an anhydrous and oxygen-free environment, dissolve CsI, MABr, FAI, PbI2, and MACl in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1 according to a molar ratio of 0.05:0.09:0.85:0.955:0.02. Add 10 μL of the benzyltriethylammonium iodide solution, stir at 55 °C for 2 h, and filter through an organic filter head to obtain a 1.55 M perovskite composite solution, where the molecular formula of the perovskite is Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.97 Br 0.03 )3.

[0195] Take 25 μL of the perovskite composite solution and drop it on the conductive glass substrate 100 coated with the electron transport layer 200. The spin-coating speed is 4000 rpm, and the spin-coating time is 30 s. Drop 200 μL of ethyl acetate in the last 10 s before the end of spin-coating. After spin-coating, heat-treat at 130 °C for 10 min to obtain the perovskite composite light-absorbing layer 700.

[0196] 4-6: The same steps as in Example 5.

[0197] Perform performance testing on the prepared perovskite solar cell, and its photoelectric conversion efficiency is 23.99%; Figure 11 Current-voltage curve of the perovskite solar cell prepared in Example 10.

[0198] Example 11

[0199] This example provides another preparation method of the perovskite solar cell of Example 3. Different from Example 10, the concentration of the benzyltriethylammonium iodide solution used in step 3 is 1.0 mg / mL, and the remaining raw materials and preparation steps are the same as those in Example 10, which will not be elaborated here.

[0200] The prepared perovskite solar cell was subjected to performance testing, and its photoelectric conversion efficiency was 23.21%; Figure 12 It is the current-voltage curve graph of the perovskite solar cell prepared in Example 11.

[0201] Example 12

[0202] This example provides another preparation method for the perovskite solar cell of Example 3. Different from Example 10, in step 3, benzyltriethylammonium chloride was used to replace benzyltriethylammonium iodide, and the remaining raw materials and preparation steps were the same as those in Example 10, which will not be elaborated here.

[0203] The prepared perovskite solar cell was subjected to performance testing, and its photoelectric conversion efficiency was 23.34%. Figure 13 It is the current-voltage curve graph of the perovskite solar cell prepared in Example 12.

[0204] Example 13

[0205] This example provides another preparation method for the perovskite solar cell of Example 3. Different from Example 10, in step 3, benzyltriethylammonium bromide was used to replace benzyltriethylammonium iodide, and the remaining raw materials and preparation steps were the same as those in Example 10, which will not be elaborated here.

[0206] The prepared perovskite solar cell was subjected to performance testing, and its photoelectric conversion efficiency was 23.33%. Figure 14 It is the current-voltage curve graph of the perovskite solar cell prepared in Example 13.

[0207] Comparative Example 1

[0208] This comparative example provides a perovskite solar cell, as Figure 15 shown. The difference in its structure from that of Example 1 is that there is no molecular modification layer 400, and the thicknesses of other structural layers are the same as those in Example 1, which will not be elaborated here.

[0209] The difference in the preparation method of this perovskite solar cell from that of Example 5 is that step 4 is not included, and the remaining preparation methods are the same as those in Example 5, which will not be elaborated here.

[0210] The prepared perovskite solar cell was subjected to performance testing, and its photoelectric conversion efficiency was 22.01%; Figure 16 It is the current-voltage curve graph of the perovskite solar cell prepared in Comparative Example 1.

[0211] Characterization Example 1

[0212] The perovskite composite light-absorbing layer prepared in Example 10 was subjected to scanning electron microscopy, and the obtained picture is as Figure 17 shown. FromFigure 17 It can be seen that the island-like structure on the surface is the one-dimensional lead halide structure of benzyltriethylammonium.

[0213] The perovskite light-absorbing layer obtained in Comparative Example 1 was subjected to scanning electron microscopy, and the resulting image is as Figure 18 shown. From Figure 18 it can be seen that the perovskite film is flat and dense.

[0214] Characterization Example 2

[0215] From Figure 19 it can be seen that the single crystal structure of the one-dimensional lead halide structure of benzyltriethylammonium is composed of benzyltriethylammonium ions and one-dimensional lead iodide chains, and the X-ray powder diffraction pattern illustrates the successful modification of the one-dimensional lead halide structure of benzyltriethylammonium in the perovskite film.

[0216] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A perovskite solar cell, characterized in that, It includes a conductive glass substrate, and an electron transport layer, a perovskite light-absorbing layer, a molecular modification layer, a hole transport layer, and a metal electrode that are sequentially stacked on the conductive glass substrate; The molecular modification layer includes a benzyltriethylammonium one-dimensional lead halide structure.

2. The perovskite solar cell according to claim 1, characterized in that, The benzyltriethylammonium one-dimensional lead halide structure is formed by benzyltriethylammonium halide and lead halide; The general formula of the benzyltriethylammonium one-dimensional lead halide structure is CMX3; where C is the benzyltriethylammonium ion, M is Pb 2+ lead ion, and X is a halide ion; Preferably, the halogen ion includes Cl - , Br - and I - and at least one of them.

3. The perovskite solar cell according to claim 1, wherein The conductive glass substrate is FTO; Preferably, the material of the electron transport layer is TiO2 or SnO2; Preferably, the material of the hole transport layer is Spiro-OMeTAD; Preferably, the material of the metal electrode is Ag or Au.

4. The perovskite solar cell according to any one of claims 1 to 3, characterized in that, The material of the perovskite light-absorbing layer is an ABX3-type compound; Among them, A is a monovalent organic cation, B is a divalent metal ion, and X is a halogen ion.

5. The perovskite solar cell according to claim 4, characterized in that, The monovalent organic cation described above includes MA + , FA + , Cs + , and K + and at least one of them; Preferably, the divalent metal ions include Pb 2+ and / or Sn 2+ ; Preferably, the halogen ion includes Cl - , Br - and I - and at least one of them.

6. A method for preparing a perovskite solar cell according to any one of claims 1 to 5, characterized in that, An electron transport layer, a perovskite light-absorbing layer, a molecular modification layer, a hole transport layer, and a metal electrode are sequentially prepared on the conductive glass substrate to obtain a perovskite solar cell; The preparation method of the molecular modification layer is: coating the benzyltriethylammonium halide solution on the perovskite light-absorbing layer by the first coating, and then obtaining the molecular modification layer through the first heat treatment.

7. The preparation method according to claim 6, characterized in that, The concentration of the benzyltriethylammonium halide solution is 0.1-10 mg / mL, preferably 0.5-5 mg / mL; Preferably, the solvent in the benzyltriethylammonium halide solution includes at least one of acetonitrile, isopropanol, methanol, ethanol, dimethoxyethanol, and chloroform; Preferably, the temperature of the first heat treatment is 100-150 °C, and the time is 2-60 min; Preferably, the manner of the first coating is spin coating; Preferably, the speed of the spin coating is 3000-6000 rpm, and the time is 20-60; Preferably, the preparation method of the perovskite light-absorbing layer is: coating the perovskite precursor solution on the electron transport layer by the second coating, and then performing the second heat treatment to obtain the perovskite light-absorbing layer; Preferably, the solvent in the perovskite precursor solution includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, γ-butyrolactone, and 2-mercaptoethanol; Preferably, the concentration of the perovskite precursor solution is 1.0-1.7 M; Preferably, the temperature of the second heat treatment is 100-150 °C, and the time is 10-60 min; Preferably, the second coating includes spin coating; Preferably, the rotation speed of the spin coating is 3000-6000 rpm, and the time is 20-60 s; Preferably, the thickness of the perovskite light-absorbing layer is 100-1000 nm.

8. A perovskite solar cell, characterized in that, Using a perovskite composite light-absorbing layer to replace the perovskite light-absorbing layer and the molecular modification layer in the perovskite solar cell according to any one of claims 1-5; The perovskite composite light-absorbing layer includes perovskite and a benzyltriethylammonium one-dimensional lead halide structure.

9. A method for preparing the perovskite solar cell according to claim 8, characterized in that, An electron transport layer, a perovskite composite light-absorbing layer, a hole transport layer, and a metal electrode are sequentially prepared on the conductive glass substrate to obtain a perovskite solar cell; The preparation method of the perovskite composite light-absorbing layer is as follows: Add benzyltriethylammonium halide to the perovskite precursor solution, and mix evenly to obtain a perovskite composite solution; Coating the perovskite composite solution on the electron transport layer for the third time, and then performing the third heat treatment to obtain the perovskite composite light-absorbing layer.

10. The preparation method according to claim 9, characterized in that, In the perovskite composite solution, the concentration of the benzyltriethylammonium halide solution is 0.1-10 mg / mL, preferably 0.2-5 mg / mL; Preferably, the solvent in the perovskite precursor solution includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, γ-butyrolactone, and 2-mercaptoethanol; Preferably, the temperature of the third heat treatment is 100-150 °C, and the time is 10-60 min; Preferably, the method of the third coating is spin coating; Preferably, the speed of the spin coating is 3000-6000 rpm, and the time is 2*-6* s; Preferably, the thickness of the perovskite composite light-absorbing layer is 1**-1*** nm.

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