CN109065720B - A kind of perovskite solar cell with precise grain boundary doping and preparation method thereof - Google Patents

Abstract

The invention relates to a perovskite solar cell with precise grain boundary doping and a preparation method thereof, which is characterized by: a conductive glass layer, a dense titanium dioxide film, a titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film, and a hole transport material Titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film refers to a CH ₃ NH ₃ PbI ₃ polycrystalline film that is doped with titanium ions at the grain boundary, and is annealed in situ to form a passivation of grain boundary defects. membrane, the moles of titanium ions are 0.01%-5% of the moles of lead ions. The invention effectively suppresses the recombination of the carriers of the p-n junction inside the battery at the grain boundary through the doping of titanium element, so that the parallel parasitic resistance is increased, thereby improving the battery filling factor, the photocurrent density and the photoelectric conversion efficiency. At the same time, the doping ratio of titanium element is optimized, which further improves the photoelectric conversion efficiency.

Description

A kind of perovskite solar cell with precise grain boundary doping and preparation method thereof

technical field

The invention relates to a perovskite solar cell with precise grain boundary doping and a preparation method thereof.

Background technique

Perovskite solar cells are highly valued by scientific research and industry due to their low cost, good performance, and simple preparation. Perovskite materials have been used in solar cells since 2009, and the current efficiency has exceeded 22%, which is 5 times the initial cell efficiency, leaving new thin-film solar cells such as dye-sensitized solar cells and organic solar cells behind. Perovskite solar cells are low-cost thin-film solar cells that have developed very rapidly in the past three years.

The core of the perovskite solar cell structure is an organometallic halide light-absorbing material with a perovskite crystal form (ABX ₃ ). In this perovskite ABX ₃ structure, A is a methylamine group (CH ₃ NH ₃ ), B is a metal lead atom, and X is a halogen atom such as chlorine, bromine, and iodine. Currently in high-efficiency perovskite solar cells, the most common perovskite material is lead iodide methylamine (CH ₃ NH ₃ PbI ₃ ), which has a band gap of about 1.6 eV, a high extinction coefficient, and is several hundred nanometers thick. The film can fully absorb sunlight below 800 nm. Moreover, the preparation of this material is simple, and a solution containing PbI ₂ and CH ₃ NH ₃ I can be obtained by spin coating and dropwise extraction with chlorobenzene at room temperature to obtain a uniform film. The above characteristics make the perovskite structure CH ₃ NH ₃ PbI ₃ not only can absorb visible light and part of the near-infrared light, but also the photogenerated carriers are not easy to recombine, and the energy loss is small. This is a perovskite solar cell. The root cause of being able to achieve high efficiency.

Perovskite solar cells currently have various structures: mesoscopic cells with porous titania, planar cells without porous titania, and superstructured mesoscopic cells with porous insulating oxides (alumina, zirconia).

At present, research hotspots focus on adjusting the properties of organic-inorganic hybrid perovskites by adjusting the A-site, B-site and X-site to further optimize the photoelectric conversion performance of perovskite. In the current process, it is difficult to obtain a single-crystal planar thin film by solution spin coating and annealing. Due to the large specific surface area and many surface defects of the polycrystalline film, the charge recombination inside the device is serious. There have been reports of lead iodide doping of perovskite films to suppress grain boundary defects. However, there are few reports on doping of its perovskite grain boundaries with other elements and suppressing its defects and recombination. And because the ion radius of the doped element is very small, it cannot be accurately doped at the defect position at the grain boundary, and the repeatability of the battery device cannot be guaranteed. Therefore, it is necessary to explore other element doping to improve the performance of the battery.

To sum up, the problems existing in the prior art are:

1) The organic-inorganic hybrid perovskite material CH ₃ NH ₃ PbI ₃ needs to be further optimized to improve its photoelectric conversion performance;

2) At present, the elements doped at the grain boundary have an impact on the open circuit voltage and repeatability of the battery, and the problem of carrier recombination caused by grain boundary defects has not yet been solved.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art, and to provide a perovskite solar cell with precise grain boundary doping that improves the defects in the polycrystalline formation process by perovskite doping, and a preparation method thereof.

The technical solution adopted by the present invention to solve the above problems is: a perovskite solar cell with precise grain boundary doping, which is characterized by: a conductive glass layer, a dense titanium dioxide film, and a titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film , hole transport material layer and vapor-deposited silver electrode layer, titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film refers to that the grain boundary is doped with titanium ions, and after annealing, the CH ₃ NH is formed in situ with passivation of grain boundary defects. ₃ PbI ₃ polycrystalline film, the mole number of titanium ions is 0.01%-5% of the mole number of lead ions.

The particle radius of the titanium ion in the present invention is smaller than the crystal grain radius of the CH ₃ NH ₃ PbI ₃ polycrystalline film.

The thickness of the dense titanium dioxide film of the present invention is 20-200 nanometers, the thickness of the titanium _- doped _CH3NH3PbI3 polycrystalline film is 200 nanometers _- 1.5 micrometers, the thickness of the hole transport material layer is 50-500 nanometers, and the thickness of the evaporated silver electrode layer 50-200 nm.

The hole transport material layer of the present invention is spiro-MeOTAD or 3-hexyl-substituted polythiophene.

A method for preparing a perovskite solar cell with precise grain boundary doping is characterized in that: comprising the following steps:

Step 1: dissolving methyl iodide and lead iodide in N,N-dimethylformamide at a molar ratio of 1:1, then adding titanium tetrachloride, and stirring to form a perovskite solution;

Step ②: depositing a dense titanium dioxide film on the conductive glass by a sol-gel method; the dense titanium dioxide film is treated at 300°C-500°C and then treated with titanium tetrachloride, and is sintered for later use;

Step 3: Use a glue homogenizer to deposit the perovskite solution on the dense titanium dioxide film through the process of chlorobenzene extraction, and bake at a temperature of 40°C-100°C for 30 minutes, so that the perovskite solution crystallizes on the dense titanium dioxide film to become titanium dioxide. Doping CH ₃ NH ₃ PbI ₃ polycrystalline film;

Step ④: uniformly spin-coating the organic solution of the hole transport material on the titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film to form a hole transport material layer;

Step ⑤: Using an evaporation method, an evaporated silver electrode layer is evaporated on the hole transport material layer.

The hole transport material layer of the present invention is made of spiro-MeOTAD, and the preparation steps of the organic solution of the hole transport material are as follows: dissolve spiro-MeOTAD in chlorobenzene, the molar concentration of spiro-MeOTAD is 0.5-1.5M, and then add Spiro-MeOTAD molar 80% tetrabutylpyridine and spiro-MeOTAD molar 30% lithium bis-trifluoromethanesulfonimide, stir well.

In the perovskite solution of the present invention, the molar concentrations of iodomethylamine and lead iodide are both controlled at 0.8-1.2M.

Compared with the prior art, the present invention has the advantage of using titanium element with relatively small ionic radius to dope CH ₃ NH ₃ PbI ₃ . Since titanium ions are much smaller than perovskite grains, they can be doped at grain boundary defects during the formation of perovskite polycrystals. The incorporation of titanium element effectively inhibits the recombination of carriers in the pn junction inside the battery at the grain boundary, which increases the parallel parasitic resistance, thereby improving the battery fill factor, photocurrent density and photoelectric conversion efficiency. At the same time, the doping ratio of titanium element is optimized, which further improves the photoelectric conversion efficiency.

Description of drawings

FIG. 1 is an EDS diagram of the CH ₃ NH ₃ PbI ₃ lattice, Ti, and Pb in Example 2 of the present invention.

FIG. 2 is a SEM image of a comparative example and Example 2 of the present invention.

FIG. 3 is the volt-ampere characteristic curves of the comparative example and Examples 1-4 of the present invention.

₄ is the steady-state PL photoluminescence spectra _of the _CH3NH3PbI3 polycrystalline films/glasses of Comparative Examples and Examples 1-4 of the present invention.

FIG. 5 is the steady-state PL photoluminescence spectra of the CH ₃ NH ₃ PbI ₃ polycrystalline film/conductive glass of Comparative Example and Examples 1-4 of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and through the examples. The following examples are to explain the present invention and the present invention is not limited to the following examples.

Prepare the N,N-dimethylformamide solution of TiCl ₄ : Take 1 ml of pure TiCl ₄ liquid and add it to 10 ml of pure alcohol (stored in the refrigerator) to obtain a 1M alcohol solution of TiCl ₄ . Take 50 microliters of _TiCl4 alcohol solution and add it to 950 microliters of N,N-dimethylformamide (DMF), dilute to obtain 0.05M _TiCl4 solution; take 100 microliters of _TiCl4 alcohol solution and add into 900 μl of N,N-dimethylformamide (DMF), diluted to obtain a 0.1M TiCl ₄ solution; 200 μl of TiCl ₄ in alcohol solution was added to 800 μl of N,N-dimethylformamide Dimethylformamide (DMF), diluted to obtain 0.2M _TiCl4 solution; 500 μl of _TiCl4 alcoholic solution was added to 500 μl of N,N-dimethylformamide (DMF), diluted to obtain 0.5 M in _TiCl4 solution.

Comparative Example.

In this example, pure CH ₃ NH ₃ PbI ₃ perovskite solar cells were prepared.

First, 0.461 g of PbI ₂ and 0.159 g of CH ₃ NH ₃ I were weighed and dissolved in 1 ml of N,N-dimethylformamide (DMF), and stirred and mixed to form a perovskite solution.

A dense titanium dioxide film (100 nanometers) is deposited on the conductive glass layer by a sol-gel method; the dense titanium dioxide film is treated at 450° C. and then treated with titanium tetrachloride, and is sintered for later use.

The perovskite solution was deposited on the dense titania film by a process of chlorobenzene extraction using a spinner. The perovskite solution was crystallized into a CH ₃ NH ₃ PbI ₃ polycrystalline film by precisely controlling the temperature at 40-100 °C for 30 minutes.

The hole transport material spiro-MeOTAD in chlorobenzene solution (concentration of 0.6M, adding 80% moles of spiro-MeOTAD tetrabutylpyridine (tBP) and 30% moles of spiro-MeOTAD bistrifluoromethanesulfonylidene) Lithium amine (Li-TFSI)) was uniformly spin-coated on the CH ₃ NH ₃ PbI ₃ polycrystalline film to form a hole transport material layer.

The silver electrode layer was vapor-deposited on the hole-transporting material layer using the vapor-deposition method.

In this embodiment, the thickness of the CH ₃ NH ₃ PbI ₃ polycrystalline film is 600 nanometers, the thickness of the hole transport material layer is 300 nanometers, and the thickness of the vapor-deposited silver electrode layer is 90 nanometers.

The photoelectric conversion of perovskite solar cells (effective illumination area 0.07cm ² ) was measured at room temperature using a xenon lamp to simulate sunlight with a light intensity of 95.6mW/cm ² (sunlight simulator model: Newport 91192A). The efficiency is 14.0% (short circuit current density 22.2mAcm ^-2 , open circuit voltage 1.09V, fill factor 0.61).

Example 1.

The N,N-dimethylformamide solution of Ti-doped CH ₃ NH ₃ PbI ₃ was prepared, and the molar concentration of Ti was 0.05% of that of lead iodide, which was used to prepare perovskite solar cells.

First, weigh 0.461 g of PbI ₂ and 0.159 g of CH ₃ NH ₃ I and dissolve them in 1 ml of N,N-dimethylformamide (DMF), stir and mix evenly, and then dropwise add 10 μl of 0.05M TiCl ₄ solution , and after stirring evenly, it becomes a perovskite solution for later use.

A dense titanium dioxide film (100 nanometers) is deposited on the conductive glass layer by a sol-gel method; the dense titanium dioxide film is treated at 450° C. and then treated with titanium tetrachloride, and is sintered for later use.

The perovskite solution was deposited on the dense titania film by a process of chlorobenzene extraction using a spinner. The perovskite solution was crystallized into a titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film by precisely controlling the temperature to bake at 40-100 °C for 30 minutes.

The hole transport material spiro-MeOTAD in chlorobenzene solution (concentration of 0.6M, adding 80% moles of spiro-MeOTAD tetrabutylpyridine (tBP) and 30% moles of spiro-MeOTAD bistrifluoromethanesulfonylidene) Lithium amine (Li-TFSI)) was uniformly spin-coated on the CH ₃ NH ₃ PbI ₃ polycrystalline film to form a hole transport material layer.

The silver electrode layer was vapor-deposited on the hole-transporting material layer using the vapor-deposition method.

In this embodiment, the thickness of the CH ₃ NH ₃ PbI ₃ polycrystalline film is 600 nanometers, the thickness of the hole transport material layer is 300 nanometers, and the thickness of the vapor-deposited silver electrode layer is 90 nanometers.

In this embodiment, the thickness of the titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film is 600 nanometers, the thickness of the hole transport material layer is 300 nanometers, and the thickness of the vapor-deposited silver electrode layer is 90 nanometers.

At room temperature, using a xenon lamp to simulate sunlight with a light intensity of 95.6mW/cm ² (sunlight simulator model: Newport 91192A), the modified perovskite solar cell was measured (effective light area is 0.07cm ² ) The photoelectric conversion efficiency is 14.8% (short-circuit current density 19.0mAcm ^-2 , open-circuit voltage 1.10V, fill factor 0.70), which is about 6.0% higher than that of unmodified solar cells. It can be seen that the small amount of Ti doping reduces the short-circuit current, but the fill factor is greatly improved. Compared with the undoped sample, see Fig. 4, 0.05% titanium doping effectively increases the photoluminescence intensity of the CH ₃ NH ₃ PbI ₃ polycrystalline film, indicating that the doped sample inhibits the recombination of charges in the crystal. Referring to Fig. 5, the weakening of the luminescence intensity of the perovskite layer doped with 0.05% titanium on the conductive glass indicates that the 0.05% doped titanium element enhances the carrier transport capability of the perovskite layer. This is because the introduction of Ti doping has an effect on the formation of CH ₃ NH ₃ PbI ₃ polycrystals, resulting in a decrease in current. However, a small amount of Ti is doped at the CH ₃ NH ₃ PbI ₃ grain boundary defect, which effectively inhibits the recombination of carriers and increases the transport capacity of carriers, thereby greatly improving the filling factor of the battery.

Example 2.

The N,N-dimethylformamide solution of titanium-doped CH ₃ NH ₃ PbI ₃ was prepared, and the molar concentration of Ti was 0.1% of the molar concentration of lead iodide for the preparation of perovskite solar cells.

First, weigh 0.461 g of PbI ₂ and 0.159 g of CH ₃ NH ₃ I and dissolve them in 1 ml of N,N-dimethylformamide (DMF), stir and mix evenly, and then add 10 μl of 0.1 M TiCl ₄ solution dropwise , and after stirring evenly, it becomes a perovskite solution for later use.

A dense titanium dioxide film (100 nanometers) is deposited on the conductive glass layer by a sol-gel method; the dense titanium dioxide film is treated at 450° C. and then treated with titanium tetrachloride, and is sintered for later use.

The perovskite solution was deposited on the dense titania film by a process of chlorobenzene extraction using a spinner. The perovskite solution was crystallized into a titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film by precisely controlling the temperature to bake at 40-100 °C for 30 minutes.

The hole transport material spiro-MeOTAD in chlorobenzene solution (concentration of 0.6M, adding 80% moles of spiro-MeOTAD tetrabutylpyridine (tBP) and 30% moles of spiro-MeOTAD bistrifluoromethanesulfonylidene) Lithium amine (Li-TFSI)) was uniformly spin-coated on the CH ₃ NH ₃ PbI ₃ polycrystalline film to form a hole transport material layer.

The silver electrode layer was vapor-deposited on the hole-transporting material layer using the vapor-deposition method.

In this embodiment, the thickness of the CH ₃ NH ₃ PbI ₃ polycrystalline film is 600 nanometers, the thickness of the hole transport material layer is 300 nanometers, and the thickness of the vapor-deposited silver electrode layer is 90 nanometers.

In this embodiment, the thickness of the titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film is 600 nanometers, the thickness of the hole transport material layer is 300 nanometers, and the thickness of the vapor-deposited silver electrode layer is 90 nanometers.

At room temperature, using a xenon lamp to simulate sunlight with a light intensity of 95.6mW/cm ² (sunlight simulator model: Newport 91192A), the modified perovskite solar cell was measured (effective light area is 0.07cm ² ) The photoelectric conversion efficiency is 17.4% (short-circuit current density 22.3mAcm ^-2 , open circuit voltage 1.09V, fill factor 0.72), which is higher than that of the unmodified solar cell (14.0%, short-circuit current density 22.2mAcm ^-2 , open circuit voltage 1.09 V, fill factor 0.61) improved by 24.3%. It can be seen that the fill factor of the cell is greatly improved by doping. Compared with the undoped sample, see Figure 4, the 0.1% titanium doping improves the luminescence intensity of the CH ₃ NH ₃ PbI ₃ polycrystalline film, indicating that the doped sample inhibits the recombination of charges in the crystal. Referring to Figure 5, the luminescence intensity of the titanium-doped 0.1% perovskite layer on the conductive glass layer is greatly weakened, indicating that the 0.1% titanium doping effectively enhances the carrier transport capability of the perovskite layer. The reason for the improved performance of 0.1% Ti-doped perovskite is that an appropriate amount of Ti is doped at the perovskite grain boundary defects, which effectively inhibits the recombination of carriers, thereby greatly increasing the transport capacity of carriers, and thus extremely. Greatly improve the fill factor of the battery. This example is the best example.

See Figure 1. The EDS diagram of CH ₃ NH ₃ PbI ₃ lattice is part a in FIG. 1 , the EDS diagram of Ti is part b in FIG. 1 , and the EDS diagram of Pb is part c in FIG. 1 . The comparison of part b and part a shows that Ti is concentrated at the grain boundary of CH ₃ NH ₃ PbI ₃ lattice; the comparison of part c and a part shows that Pb element is evenly distributed in the CH ₃ NH ₃ PbI ₃ lattice. It is illustrated that Ti element plays a role in passivating defects in the CH ₃ NH ₃ PbI ₃ lattice, thereby inhibiting the recombination of carriers in the perovskite polycrystal and contributing to the transport of carriers in the device.

See Figure 2. Part a in FIG. 2 is an SEM image of the CH ₃ NH ₃ PbI ₃ polycrystalline film of the comparative example, and part b is an SEM image of the CH ₃ NH ₃ PbI ₃ polycrystalline film of the present embodiment. The coordinate scale in Figure 2 is 1 μm. Figure 2 illustrates that doped with Ti, the perovskite grains are slightly smaller than the undoped perovskite grains, thereby attenuating the formation of large defects at the perovskite polygrain boundaries.

Example 3.

The N,N-dimethylformamide solution of Ti-doped CH ₃ NH ₃ PbI ₃ was prepared, and the molar concentration of Ti was 0.2% of the molar concentration of lead iodide for the preparation of perovskite solar cells.

First, weigh 0.461 g of PbI ₂ and 0.159 g of CH ₃ NH ₃ I and dissolve them in 1 ml of N,N-dimethylformamide (DMF), stir and mix evenly, and then add 10 μl of 0.2 M TiCl ₄ solution dropwise , and after stirring evenly, it becomes a perovskite solution for later use.

A dense titanium dioxide film (100 nanometers) is deposited on the conductive glass layer by a sol-gel method; the dense titanium dioxide film is treated at 450° C. and then treated with titanium tetrachloride, and is sintered for later use.

The perovskite solution was deposited on the dense titania film by a process of chlorobenzene extraction using a spinner. The perovskite solution was crystallized into a titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film by precisely controlling the temperature to bake at 40-100 °C for 30 minutes.

The hole transport material spiro-MeOTAD in chlorobenzene solution (concentration of 0.6M, adding 80% moles of spiro-MeOTAD tetrabutylpyridine (tBP) and 30% moles of spiro-MeOTAD bistrifluoromethanesulfonylidene) Lithium amine (Li-TFSI)) was uniformly spin-coated on the CH ₃ NH ₃ PbI ₃ polycrystalline film to form a hole transport material layer.

The silver electrode layer was vapor-deposited on the hole-transporting material layer using the vapor-deposition method.

In this embodiment, the thickness of the CH ₃ NH ₃ PbI ₃ polycrystalline film is 600 nanometers, the thickness of the hole transport material layer is 300 nanometers, and the thickness of the vapor-deposited silver electrode layer is 90 nanometers.

In this embodiment, the thickness of the titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film is 600 nanometers, the thickness of the hole transport material layer is 300 nanometers, and the thickness of the vapor-deposited silver electrode layer is 90 nanometers.

At room temperature, using a xenon lamp to simulate sunlight with a light intensity of 95.6mW/cm ² (sunlight simulator model: Newport 91192A), the modified perovskite solar cell was measured (effective light area is 0.07cm ² ) The photoelectric conversion efficiency is 14.1% (, short circuit current density 20.1mAcm ^-2 , open circuit voltage 1.10V, fill factor 0.637), which is comparable to that of the unmodified solar cell (14.0%, short circuit current density 22.2mAcm ^-2 , open circuit voltage 1.09V, fill factor 0.61) is not much difference. It can be seen, however, that the fill factor is increased by doping, while the short-circuit current density is decreased. Compared with the undoped sample, see Fig. 4, the luminescence intensity of the 0.2% Ti-doped CH ₃ NH ₃ PbI ₃ polycrystalline film is weakened. Referring to Fig. 5, the luminescence intensity of the CH ₃ NH ₃ PbI ₃ polycrystalline film doped with 0.2% Ti on the conductive glass layer is weakened, but it is enhanced compared with the sample doped with 0.1%. This is because 0.2%Ti can still act at the perovskite grain boundary. However, with the increase of Ti doping amount, it affects the formation of CH ₃ NH ₃ PbI ₃ polycrystalline film, resulting in impurity defects and affecting the battery current. improve.

Example 4.

The N,N-dimethylformamide solution of Ti-doped CH ₃ NH ₃ PbI ₃ was prepared, and the molar concentration of Ti was 0.5% of the molar concentration of lead iodide for the preparation of perovskite solar cells.

First, weigh 0.461 g of PbI ₂ and 0.159 g of CH ₃ NH ₃ I and dissolve them in 1 ml of N,N-dimethylformamide (DMF), stir and mix evenly, and then add 10 μl of 0.5 M TiCl ₄ solution dropwise , and after stirring evenly, it becomes a perovskite solution for later use.

A dense titanium dioxide film (100 nanometers) is deposited on the conductive glass layer by a sol-gel method; the dense titanium dioxide film is treated at 450° C. and then treated with titanium tetrachloride, and is sintered for later use.

The perovskite solution was deposited on the dense titania film by a process of chlorobenzene extraction using a spinner. The perovskite solution was crystallized into a titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film by precisely controlling the temperature to bake at 40-100 °C for 30 minutes.

The hole transport material spiro-MeOTAD in chlorobenzene solution (concentration of 0.6M, adding 80% moles of spiro-MeOTAD tetrabutylpyridine (tBP) and 30% moles of spiro-MeOTAD bistrifluoromethanesulfonylidene) Lithium amine (Li-TFSI)) was uniformly spin-coated on the CH ₃ NH ₃ PbI ₃ polycrystalline film to form a hole transport material layer.

The silver electrode layer was vapor-deposited on the hole-transporting material layer using the vapor-deposition method.

In this embodiment, the thickness of the CH ₃ NH ₃ PbI ₃ polycrystalline film is 600 nanometers, the thickness of the hole transport material layer is 300 nanometers, and the thickness of the vapor-deposited silver electrode layer is 90 nanometers.

In this embodiment, the thickness of the titanium-doped CH ₃ NH ₃ PbI ₃ polycrystalline film is 600 nanometers, the thickness of the hole transport material layer is 300 nanometers, and the thickness of the vapor-deposited silver electrode layer is 90 nanometers.

At room temperature, using a xenon lamp to simulate sunlight with a light intensity of 95.6mW/cm ² (sunlight simulator model: Newport 91192A), the doped perovskite solar cells were measured (the effective light area was 0.07cm ^{2 )} . ) with a photoelectric conversion efficiency of 11.7% (short circuit current density 20.0mAcm ^-2 , open circuit voltage 1.08V, fill factor 0.540), which is higher than that of the unmodified solar cell (14.0%, short circuit current density 22.2mAcm ^-2 , open circuit voltage 1.09V, fill factor 0.61) is significantly reduced. It can be seen that the short-circuit current density and fill factor are greatly reduced by doping. Compared with the undoped sample, see Fig. 4, the luminescence intensity of the 0.5% Ti-doped CH ₃ NH ₃ PbI ₃ polycrystalline film is greatly weakened. Referring to Fig. 5, the luminescence intensity of the CH ₃ NH ₃ PbI ₃ polycrystalline film doped with 0.5% Ti on the conductive glass layer is reduced, but it is greatly improved compared with the perovskite doped with 0.1% Ti. This is due to excessive Ti doping, which seriously affects the formation of titanite polycrystals, resulting in more impurity defects, thereby increasing the probability of carrier recombination, resulting in a substantial decrease in short-circuit current and fill factor.

In addition, it should be noted that the specific embodiments described in this specification may have different shapes and names of parts and components, and the above content described in this specification is only an illustration of the structure of the present invention. All equivalent changes or simple changes made according to the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or additions to the described specific embodiments or substitute in similar manners, as long as they do not deviate from the structure of the present invention or go beyond the scope defined by the claims, All should belong to the protection scope of the present invention.

Claims (7)

1. a perovskite solar cell of grain boundary precision doping is characterized in that: conductive glass layer, dense titanium dioxide film, titanium tetrachloride doped CH ₃ NH ₃ PbI ₃ polycrystalline film, hole transport material layer and Evaporated silver electrode layer, titanium tetrachloride doped CH ₃ NH ₃ PbI ₃ polycrystalline film refers to the CH ₃ NH ₃ PbI ₃ polycrystalline film that is doped with titanium ions at the grain boundary and formed in situ through annealing to passivate the grain boundary defects. For the crystal film, the moles of titanium ions are 0.01%-5% of the moles of lead ions. 2 . The perovskite solar cell with precise grain boundary doping according to claim 1 , wherein the particle radius of the titanium ions is smaller than the crystal grain radius of the CH ₃ NH ₃ PbI ₃ polycrystalline film. 3 . 3. The perovskite solar cell with precise grain boundary doping according to claim 1 or 2, characterized in that: the thickness of the dense titanium dioxide film is 20-200 nanometers, and the titanium tetrachloride doped CH ₃ NH ₃ PbI ₃ is more The thickness of the crystal film is 200 nanometers to 1.5 micrometers, the thickness of the hole transport material layer is 50 to 500 nanometers, and the thickness of the vapor-deposited silver electrode layer is 50 to 200 nanometers. 4 . The perovskite solar cell with precise grain boundary doping according to claim 3 , wherein the hole transport material layer is spiro-MeOTAD or 3-hexyl-substituted polythiophene. 5 . 5. a kind of preparation method of the perovskite solar cell of the accurate grain boundary doping as described in any one of claim 1-4, it is characterized in that: comprise the steps: Step 1: dissolving methyl iodide and lead iodide in N,N-dimethylformamide at a molar ratio of 1:1, then adding titanium tetrachloride, and stirring to form a perovskite solution; Step ②: depositing a dense titanium dioxide film on the conductive glass by a sol-gel method; the dense titanium dioxide film is treated at 300°C-500°C and then treated with titanium tetrachloride, and is sintered for later use; Step 3: The perovskite solution is deposited on the dense titanium dioxide film by the process of chlorobenzene extraction using a glue homogenizer, and the temperature is controlled at 40°C to 100°C for 30 minutes, so that the perovskite solution is crystallized on the dense titanium dioxide film. Titanium chloride doped CH ₃ NH ₃ PbI ₃ polycrystalline film; Step ④: uniformly spin-coating the organic solution of the hole transport material on the titanium tetrachloride doped CH ₃ NH ₃ PbI ₃ polycrystalline film to form a hole transport material layer; Step ⑤: Using an evaporation method, a silver electrode layer is evaporated on the hole transport material layer. 6. the preparation method of the perovskite solar cell of grain boundary accurate doping according to claim 5, is characterized in that: described hole transport material layer material is spiro-MeOTAD, the organic solution preparation step of hole transport material As follows: Dissolve spiro-MeOTAD in chlorobenzene, the molar concentration of spiro-MeOTAD is 0.5-1.5M, then add tetrabutylpyridine with 80 mole% of spiroMeOTAD and bistrifluoromethanesulfonic acid with 30% mole of spiro-MeOTAD Lithium imide, stir well. 7. The preparation method of the perovskite solar cell doped with grain boundary precision according to claim 6, it is characterized in that: in the perovskite solution, the molar concentrations of methyl iodide and lead iodide are all controlled at 0.8-1.2 M.

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