CN116171053B - Full perovskite laminated solar cell and preparation method thereof - Google Patents

Abstract

The invention discloses an all-perovskite laminated solar cell and a preparation method thereof, belonging to the technical field of solar cells. The laminated solar cell has a hole transport layer material in a wide bandgap top cell and a hole transport layer in a narrow bandgap bottom cell. The materials of the transport layer are the same, and the material of the hole transport layer is a material with self-assembly properties, specifically a SAM material with a phosphoric acid end group, a SAM material with a carboxylic acid end group, a SAM material with a sulfuric acid end group, or a SAM material with an isocyanate end group. . This all-perovskite tandem solar cell can effectively improve the existing tandem solar cells' problems such as complex preparation process, high cost and serious interface non-radiative recombination.

Description

An all-perovskite tandem solar cell and its preparation method

Technical field

The invention belongs to the technical field of solar cells, and specifically relates to an all-perovskite stacked solar cell and a preparation method thereof.

Background technique

As a device that can directly convert solar energy into electrical energy, solar cells occupy an important position in the existing energy structure. Among them, perovskite solar cells have attracted widespread attention due to their outstanding photoelectric properties and simple preparation process. Currently, the certified efficiency of single-junction perovskite solar cells has exceeded 25.7%, but its efficiency improvement is limited by the Shockley-Quisser (S-Q) limit (~33%). In order to make full use of the solar spectrum, reduce battery heat dissipation, and break through the S-Q limit of single-junction devices, the development of multi-junction stacked perovskite solar cells is very promising.

Two-terminal perovskite-perovskite (all-perovskite) tandem solar cells usually consist of a wide-bandgap (1.7-1.9eV) top cell and a narrow-bandgap (1.0-1.3eV) bottom cell. Although the efficiency of all-perovskite tandem solar cells has exceeded that of single-junction perovskite solar cells, severe interfacial non-radiative recombination limits further improvements in performance. To reduce this loss and manufacturing cost, it is crucial to select appropriate hole transport materials. The hole transport layer materials of wide bandgap and narrow bandgap in all-perovskite tandem solar cells disclosed in the prior art are usually PTAA and PEDOT:PSS respectively, that is, all-perovskite tandem solar cells in the prior art. Different hole transport layer materials are used in the two sub-batteries, which makes the preparation process of the battery more complicated, increases the production cost, and requires higher equipment and environment; moreover, the PEDOT:PSS hole in the existing technology The hole transport layer has strong parasitic absorption of near-infrared light, and its acidity will also cause the degradation of the narrow bandgap perovskite film, which is not conducive to the stability of the stacked device; moreover, the hole transport layer/perovskite film interface exists There is a serious problem of non-radiative recombination at the interface.

Contents of the invention

In view of the above-mentioned deficiencies in the prior art, the present invention provides an all-perovskite tandem solar cell and a preparation method thereof. The all-perovskite tandem solar cell can effectively improve the preparation process of existing tandem solar cells. The process is complex, the cost is high and there are serious problems of non-radiative recombination at the interface.

In order to achieve the above objects, the technical solutions adopted by the present invention to solve the technical problems are:

An all-perovskite tandem solar cell in which the hole transport layer material in the wide bandgap top cell is the same as the hole transport layer material in the narrow bandgap bottom cell.

Furthermore, the material of the hole transport layer is a material with self-assembly properties.

Further, the material with self-assembly properties is a SAM material with phosphate end groups, a SAM material with carboxylic acid end groups, a SAM material with sulfate end groups or a SAM material with isocyanate end groups.

Further, the hole transport layer material is 4-(7-(4-(bis(4-methoxyphenyl)amino)-2,5-difluorophenyl)benzo[c][1,2, 5]thiadiazol-4-yl)benzoic acid.

Further, the thickness of the hole transport layer in the wide band gap top cell and the hole transport layer in the narrow band gap bottom cell are both 3-15 nm.

The above-mentioned preparation method of all-perovskite tandem solar cells includes the following steps:

(1) Dissolve the hole transport layer material in a solvent to prepare a hole transport layer precursor solution;

(2) Spin-coat the hole transport layer precursor solution in step (1) on the ITO transparent conductive glass, and perform annealing treatment to prepare the hole transport layer of the wide bandgap top battery;

(3) sequentially deposit a wide-bandgap perovskite absorption layer, an electron-transport layer and an intermediate connection layer on the hole-transport layer of the wide-band-gap top cell in step (2);

(4) Spin-coating the hole transport layer precursor solution in step (1) on the intermediate connecting layer in step (3), and perform annealing treatment to prepare the hole transport layer of the narrow bandgap bottom battery;

(5) Sequentially deposit a narrow band gap perovskite absorption layer, an electron transport layer and a metal electrode on the hole transport layer of the narrow band gap bottom cell in step (4) to prepare an all-perovskite tandem solar cell.

In the present invention, the deposition methods such as wide bandgap perovskite absorption layer, electron transport layer, intermediate connection layer, narrow bandgap perovskite absorption layer, metal electrode, etc. can be carried out according to conventional methods in the art unless otherwise specified. Unless otherwise specified, or specifically described components or raw materials, conventional components or raw materials in this field may be used.

Further, in step (1), the solvent is toluene, ethanol, isopropyl alcohol, deionized water or ether, and the concentration of the hole transport layer precursor solution is 0.3-0.8 mg/mL.

Further, the spin coating parameters in step (2) and step (4) are the same, specifically: the spin coating speed is 3000-5000 rpm, and the spin coating time is 20-40 s.

Further, the annealing parameters in step (2) and step (4) are the same, specifically: the annealing temperature is 80-130°C, and the annealing time is 5-20 minutes.

Further, the electron transport layer described in step (3) is composed of a C ₆₀ or C ₇₀ transport layer and a tin dioxide barrier layer, and the electron transport layer described in step (5) is composed of a C ₆₀ or C ₇₀ transport layer and a tin dioxide barrier layer. consists of a tin barrier layer, or a C ₆₀ or C ₇₀ transfer layer and a BCP barrier layer.

Further, the material of the intermediate connection layer in step (3) is IZO (indium zinc oxide) or ITO (indium tin oxide) or AZO (aluminum zinc oxide) or Au, and the metal electrode material in step (5) is Cu or Ag.

The beneficial effects produced by the present invention are:

1. The present invention applies the same hole transport layer material to two sub-cells with wide and narrow band gaps at the same time, which simplifies the preparation process of laminated solar cells and reduces the requirements for production equipment and preparation processes, especially when roll-to-roll, When slit coating is used to prepare large-area devices or components, the advantages are more obvious. It greatly reduces the investment in manpower, material resources, and financial resources. It is of great significance to reducing the preparation cost of laminated devices and accelerating large-scale production.

2. In the present invention, materials with self-assembly properties such as donor-acceptor P-type molecules are used to replace the PTAA material in the wide-band gap sub-cell and the PEDOT:PSS material in the narrow-band-gap sub-cell in the tandem perovskite solar cell as the stack. The main working principles of the hole transport layer in the device are: first, the self-assembled hole transport layer has good hole extraction performance, thus ensuring the effective transfer and extraction of holes; second, due to this type of self-assembled hole transport layer The thickness of the assembled hole transport layer is extremely thin. When deposited on the ITO surface, they have better light transmittance than PTAA and PEDOT:PSS, which can improve the effective utilization of sunlight by the perovskite film; third, in the wide bandgap In the top cell, compared with the HOMO energy level of PTAA, the HOMO energy level of the self-assembled material matches the valence band of the wide-bandgap perovskite better, which is beneficial to reducing the interface energy level barrier for hole transmission and accelerating the removal of holes. Extraction, reducing energy loss, and adding functional groups on self-assembled materials can passivate defects on the surface of the wide-bandgap perovskite film, thereby significantly reducing non-radiation at the hole transport layer/wide-bandgap perovskite film interface Recombination; in narrow-bandgap bottom cells, the self-assembled hole transport layer can not only reduce non-radiative recombination at the interface, but also delay the crystallization of tin-lead narrow-bandgap perovskite through the strong interaction with Sn ²⁺ speed to improve its crystallization kinetics, thereby preparing high-quality tin-lead narrow bandgap perovskite films with higher crystallinity and lower defect state density. In summary, this hole transport layer greatly improves the photoelectric conversion efficiency of the two sub-cells, thereby enabling the preparation of more efficient and stable tandem perovskite solar cells.

3. The hole transport layer in the present invention effectively improves the problem that the near-infrared light transmittance of the intermediate connection layer in the all-perovskite tandem solar cell is low and easily causes degradation and oxidation of the perovskite film. This is mainly due to the problem in the present invention. The thickness of the self-assembled hole transport layer used is extremely thin, 3-15nm, which can reduce the absorption and emission of sunlight, thereby reducing the loss of sunlight, which is beneficial to more sunlight reaching the surface of the perovskite film. Strengthen the full utilization of sunlight by the two sub-cells, especially reduce the parasitic absorption of near-infrared light by the intermediate connection layer, improve the quality of the narrow bandgap perovskite film, improve the photoelectric conversion efficiency of the device and enhance the stability of the device sex.

Moreover, the hole transport layer in this application is extremely thin and has a greater tolerance for uneven film thickness. The hole transport layer material in this application will be more orderly after being anchored on the ITO surface through anchoring groups. Arrangement, and the alignment orientation is more parallel to ITO, so the extraction and transfer rate of holes can be effectively improved. In the existing technology, traditional hole transport layers such as PTAA and PEDOT:PSS are arranged randomly on the surface of ITO, and their hole extraction and transfer capabilities are poor.

Description of the drawings

Figure 1 is a schematic structural diagram of an all-perovskite tandem solar cell in the prior art;

Figure 2 is a schematic structural diagram of an all-perovskite tandem solar cell in the present invention;

Figure 3 is the ultraviolet-visible transmission spectrum of the wide-bandgap top cell in Example 3 and Comparative Example 1;

Figure 4 is the ultraviolet-visible transmission spectrum of the narrow bandgap bottom cell in Example 3 and Comparative Example 1;

Figure 5 is a J-V curve of the all-perovskite tandem solar cell in Comparative Example 1;

Figure 6 is a J-V curve of the all-perovskite tandem solar cell in Example 3.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with examples. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention. That is, the described embodiments are only some embodiments of the present invention, rather than all embodiments.

Therefore, the following detailed description of the embodiments of the invention is not intended to limit the scope of the claimed invention, but rather to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without any creative work fall within the scope of protection of the present invention.

It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations are mutually exclusive. any such actual relationship or sequence exists between them. Furthermore, the terms "comprises," "comprises," or any other variations thereof are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also those not expressly listed other elements, or elements inherent to the process, method, article or equipment. Without further limitation, an element qualified by the statement "comprises a..." does not exclude the presence of additional identical elements in the process, method, article, or device that includes the element.

The features and performance of the present invention will be described in further detail below with reference to the embodiments and drawings.

Example 1

An all-perovskite tandem solar cell, its preparation method includes the following steps:

(1) 4-(7-(4-(Bis(4-methoxyphenyl)amino)-2,5-difluorophenyl)benzo[c][1,2,5]thiadiazole -4-yl)benzoic acid material is dissolved in toluene to prepare a hole transport layer precursor solution with a concentration of 0.3 mg/mL;

(2) Spin-coat the hole transport layer precursor solution in step (1) on the cleaned ITO transparent conductive glass at a spin-coating speed of 4000 rpm and a spin-coating time of 40 s, and then perform annealing treatment at an annealing temperature of 80 ℃, annealing time is 20min, and a hole transport layer with a thickness of 6nm is obtained;

(3) Use the anti-solvent method to drop the wide-bandgap perovskite precursor solution on the hole transport layer prepared in step (2) for spin coating. The low speed spin coating is 300 rpm, the spin coating time is 10 s, and the high speed spin coating is 2000 rpm. , the spin coating time is 60s, the anti-solvent ether is dropped at the 30th second during high-speed spin coating, and then annealed at 50°C for 8 minutes and 90°C for 17 minutes to prepare a wide-bandgap perovskite absorption layer;

(4) Use thermal evaporation method to deposit a 20nm thick C ₆₀ transmission layer on the wide bandgap perovskite absorption layer prepared in step (3). The specific operation is: turn on the power and slowly heat C ₆₀ until the temperature is 530°C. Above, the evaporation rate is Until the deposition thickness reaches 20nm; then use atomic layer deposition to deposit a 20nm thick tin dioxide barrier layer on the C ₆₀ electron transport layer. The specific operations are: set the deposition chamber temperature to 90°C, the tin source pulse time to 100ms, and the cleaning time to 30s. , the water source pulse time is 100ms, and the cleaning time is 30s;

(5) Use the radio frequency magnetron sputtering method to sputter a 120nm thick IZO film on the tin dioxide barrier layer prepared in step (4). The specific parameters are: the sputtering power is 70W, the sputtering pressure is 0.5Pa, The argon gas flow rate is 30 sccm, and the sputtering time is controlled to adjust the sputtering thickness;

(6) The IZO thin film prepared in step (5) is spin-coated with the hole transport layer precursor solution in step (1) by spin coating at a spin coating speed of 4000 rpm and a spin coating time of 40 s, and then annealed. The annealing temperature is 80°C, the annealing time is 20 minutes, and a 6nm thick hole transport layer is obtained;

(7) Use the anti-solvent method to spin-coat the narrow-bandgap perovskite absorption layer on the hole transport layer prepared in step (6). The low speed is 500 rpm, the spin coating time is 20 s, the high speed is 4000 rpm, the spin coating time is 60 s, and reverse The solvent chlorobenzene was dropped at the 15th second during high-speed spin coating, and then annealed at 80°C for 20 minutes and 50°C for 20 minutes to prepare a narrow bandgap perovskite absorption layer;

(8) Use thermal evaporation method to sequentially deposit a 20nm thick C ₆₀ transmission layer and a 20nm thick tin dioxide barrier layer on the narrow bandgap perovskite absorption layer prepared in step (7);

(9) Use thermal evaporation method to deposit a 100nm thick copper electrode on the tin dioxide barrier layer prepared in step (8) to prepare a full perovskite tandem solar cell.

Example 2

An all-perovskite tandem solar cell, its preparation method includes the following steps:

(1) 4-(7-(4-(Bis(4-methoxyphenyl)amino)-2,5-difluorophenyl)benzo[c][1,2,5]thiadiazole -4-yl)benzoic acid material is dissolved in toluene to prepare a hole transport layer precursor solution with a concentration of 0.8 mg/mL;

(2) Spin-coat the hole transport layer precursor solution in step (1) on the cleaned ITO transparent conductive glass at a spin-coating speed of 5000 rpm and a spin-coating time of 20 s, and then perform annealing treatment at an annealing temperature of 130 ℃, annealing time is 5min, and a hole transport layer with a thickness of 15nm is obtained;

(3) Use the anti-solvent method to drop the wide-bandgap perovskite precursor solution on the hole transport layer prepared in step (2) for spin coating. The low speed spin coating is 800 rpm, the spin coating time is 2 s, and the high speed spin coating is 4000 rpm. , the spin coating time is 30s, the anti-solvent ether is dropped at the 30th second during high-speed spin coating, and then annealed at 70°C for 2 minutes and 130°C for 8 minutes to prepare a wide-bandgap perovskite absorption layer;

(4) Use thermal evaporation method to deposit a 20nm thick C ₇₀ transmission layer on the wide bandgap perovskite absorption layer prepared in step (3). The specific operation is: turn on the power and slowly heat C ₇₀ until the temperature is 530°C. Above, the evaporation rate is Until the deposition thickness reaches 20nm; then use atomic layer deposition to deposit a 20nm thick tin dioxide barrier layer on the C ₇₀ electron transport layer. The specific operations are: set the deposition chamber temperature to 90°C, the tin source pulse time to 100ms, and the cleaning time to 30s. , the water source pulse time is 100ms, and the cleaning time is 30s;

(5) Use the radio frequency magnetron sputtering method to sputter a 120nm thick IZO film on the tin dioxide barrier layer prepared in step (4). The specific parameters are: the sputtering power is 70W, the sputtering pressure is 0.5Pa, The argon gas flow rate is 30 sccm, and the sputtering time is controlled to adjust the sputtering thickness;

(6) Use the spin coating method to spin-coat the IZO film prepared in step (5) with the hole transport layer precursor solution in step (1). The spin-coating speed is 5000 rpm, the spin-coating time is 20 s, and then annealed. The annealing temperature is 130°C, the annealing time is 5 minutes, and a 15-minute-thick hole transport layer is obtained;

(7) Use the anti-solvent method to spin-coat the narrow-bandgap perovskite absorption layer on the hole transport layer prepared in step (6). The low speed is 1200 rpm, the spin coating time is 8 s, the high speed is 7000 rpm, the spin coating time is 30 s, and reverse The solvent chlorobenzene was dropped at the 15th second during high-speed spin coating, and then annealed at 120°C for 10 minutes and 60°C for 10 minutes to prepare a narrow bandgap perovskite absorption layer;

(8) Use thermal evaporation method to sequentially deposit a 20nm thick C ₆₀ transmission layer and a 20nm thick BCP barrier layer on the narrow bandgap perovskite absorption layer prepared in step (7);

(9) Use thermal evaporation method to deposit a 100nm thick copper electrode on the tin dioxide barrier layer prepared in step (8) to prepare a full perovskite tandem solar cell.

Example 3

An all-perovskite tandem solar cell, its preparation method includes the following steps:

(1) 4-(7-(4-(Bis(4-methoxyphenyl)amino)-2,5-difluorophenyl)benzo[c][1,2,5]thiadiazole -4-yl)benzoic acid material is dissolved in toluene to prepare a hole transport layer precursor solution with a concentration of 0.5 mg/mL;

(2) Spin-coat the hole transport layer precursor solution in step (1) on the cleaned ITO transparent conductive glass at a spin-coating speed of 4000 rpm and a spin-coating time of 30 s, and then perform annealing treatment at an annealing temperature of 110 ℃, annealing time is 10min, and a hole transport layer with a thickness of 10nm is obtained;

(3) Use the anti-solvent method to drop the wide-bandgap perovskite precursor solution on the hole transport layer prepared in step (2) for spin coating. The low speed spin coating is 500 rpm, the spin coating time is 7 s, and the high speed spin coating is 3000 rpm. , the spin coating time is 50s, the anti-solvent ether is dropped at the 20th second during high-speed spin coating, and then annealed at 60°C for 5 minutes and 110°C for 12 minutes to prepare a wide-bandgap perovskite absorption layer;

(4) Use thermal evaporation method to deposit a 20nm thick C ₆₀ transmission layer on the wide bandgap perovskite absorption layer prepared in step (3). The specific operation is: turn on the power and slowly heat C ₆₀ until the temperature is 530°C. Above, the evaporation rate is Until the deposition thickness reaches 20nm; then use atomic layer deposition to deposit a 20nm thick tin dioxide barrier layer on the C ₆₀ electron transport layer. The specific operations are: set the deposition chamber temperature to 90°C, the tin source pulse time to 100ms, and the cleaning time to 30s. , the water source pulse time is 100ms, and the cleaning time is 30s;

(5) Use the radio frequency magnetron sputtering method to sputter a 120nm thick IZO film on the tin dioxide barrier layer prepared in step (4). The specific parameters are: the sputtering power is 30W, the sputtering pressure is 0.3Pa, The argon gas flow rate is 23 sccm, and the sputtering time is controlled to adjust the sputtering thickness;

(6) Use the spin coating method to spin-coat the IZO thin film prepared in step (5) with the hole transport layer precursor solution in step (1), the spin-coating speed is 4000 rpm, the spin-coating time is 30 s, and then annealed, The annealing temperature is 110°C, the annealing time is 15 minutes, and an 8-minute-thick hole transport layer is obtained;

(7) Use the anti-solvent method to spin-coat the narrow-bandgap perovskite absorption layer on the hole transport layer prepared in step (6), at a low speed of 800 rpm, a spin coating time of 10 s, a high speed of 6000 rpm, a spin coating time of 50 s, and reverse The solvent chlorobenzene was dropped at the 15th second during high-speed spin coating, and then annealed at 100°C for 15 minutes and 55°C for 15 minutes to prepare a narrow bandgap perovskite absorption layer;

(8) Use thermal evaporation method to sequentially deposit a 20nm thick C ₆₀ transmission layer and a 20nm thick tin dioxide barrier layer on the narrow bandgap perovskite absorption layer prepared in step (7);

(9) Use thermal evaporation method to deposit a 100nm thick copper electrode on the tin dioxide barrier layer prepared in step (8) to prepare a full perovskite tandem solar cell.

Comparative example 1

An all-perovskite tandem solar cell, its preparation method includes the following steps:

(1) Prepare PTAA hole transport layer precursor solution and PEDOT:PSS hole transport layer precursor solution respectively;

(2) Spin-coat the PTAA hole transport layer precursor solution on the cleaned ITO transparent conductive glass at a spin-coating speed of 4000 rpm and a spin-coating time of 30 s, and then perform annealing treatment at a temperature of 110°C and an annealing time of 10min, a hole transport layer with a thickness of 10nm is obtained;

(3) Use the anti-solvent method to drop the wide-bandgap perovskite precursor solution on the hole transport layer prepared in step (2) for spin coating. The low speed spin coating is 500 rpm, the spin coating time is 7 s, and the high speed spin coating is 3000 rpm. , the spin coating time is 50s, the anti-solvent ether is dropped at the 20th second during high-speed spin coating, and then annealed at 60°C for 5 minutes and 110°C for 12 minutes to prepare a wide-bandgap perovskite absorption layer;

(4) Use thermal evaporation method to deposit a 20nm thick C ₆₀ electron transport layer on the wide bandgap perovskite absorption layer prepared in step (3). The specific operation is: turn on the power and slowly heat C ₆₀ until the temperature is 530 ℃ or above, so that the evaporation rate is Until the deposition thickness reaches 20nm; then use atomic layer deposition to deposit a 20nm thick tin dioxide electron transport layer on the C ₆₀ electron transport layer. The specific operations are: set the deposition chamber temperature to 90°C, the tin source pulse time to 100ms, and the cleaning time to 30s, the water source pulse time is 100ms, and the cleaning time is 30s;

(5) Use the radio frequency magnetron sputtering method to sputter a 120nm thick IZO film on the tin dioxide barrier layer prepared in step (4). The specific parameters are: the sputtering power is 70W, the sputtering pressure is 0.5Pa, The argon gas flow rate is 30 sccm, and the sputtering time is controlled to adjust the sputtering thickness;

(6) Use the spin coating method to spin-coat the PEDOT:PSS hole transport layer precursor solution on the IZO film prepared in step (5). The spin-coating speed is 4000 rpm and the spin-coating time is 30 s. Then, it is annealed. The annealing temperature is 110℃, annealing time is 15min, and an 8nm thick hole transport layer is produced;

(7) Use the anti-solvent method to spin-coat the narrow-bandgap perovskite absorption layer on the hole transport layer prepared in step (6), at a low speed of 800 rpm, a spin coating time of 10 s, a high speed of 6000 rpm, a spin coating time of 50 s, and reverse The solvent chlorobenzene was dropped at the 15th second during high-speed spin coating, and then annealed at 100°C for 15 minutes and 55°C for 15 minutes to prepare a narrow bandgap perovskite absorption layer;

(8) Use thermal evaporation method to sequentially deposit a 20nm thick C ₆₀ electron transport layer and a 20nm thick tin dioxide barrier layer on the narrow bandgap perovskite absorption layer prepared in step (7);

(9) Use thermal evaporation method to deposit a 100nm thick copper electrode on the tin dioxide electron transport layer prepared in step (8) to prepare a full perovskite tandem solar cell.

Test example

Taking the all-perovskite tandem solar cell in Example 3 as an example, the performance of the all-perovskite tandem solar cell in Example 3 and Comparative Example 1 was tested respectively. The specific results are shown in Figure 3-6.

It can be seen from Figure 3 that the light transmittance of SAM is higher in the 300-450nm band, so that more short-wavelength sunlight will illuminate the surface of the wide-bandgap perovskite film, and the wide-bandgap perovskite film mainly absorbs Short-wavelength sunlight, which undoubtedly allows the wide-bandgap perovskite absorption layer to absorb more photons, thereby increasing the output current of the wide-bandgap top cell.

As can be seen from Figure 4, the light transmittance of SAM can be seen to be higher in the 700-1200nm band, so that more long-wavelength sunlight will illuminate the surface of the narrow-bandgap perovskite film, and the narrow-bandgap perovskite film is exactly It mainly absorbs long-wavelength sunlight, which undoubtedly allows the narrow-bandgap perovskite absorption layer to absorb more photons, thereby increasing the output current of the narrow-bandgap bottom cell.

Comparing Figure 5 and Figure 6, it can be seen that the improvement of V _OC is mainly based on the significant reduction of non-radiative recombination at the SAM/perovskite interface, mainly: in the wide bandgap top cell, compared with the HOMO energy level of PTAA, SAM The HOMO energy level of the material matches the valence band of the wide-bandgap perovskite better, which is beneficial to reducing the interface energy level barrier for hole transmission, accelerating hole extraction, and reducing energy loss. In addition, the functionalized groups on the self-assembled material The group can passivate the defects on the surface of the wide-bandgap perovskite film, thereby significantly reducing the non-radiative recombination of the hole transport layer/wide-bandgap perovskite film interface; and in the narrow-bandgap bottom battery, the self-assembled hole transport layer Not only can it reduce non-radiative recombination at the interface, but it can also improve the crystallization kinetics of tin-lead narrow-bandgap perovskite by slowing down its crystallization speed through the strong interaction with Sn ²⁺ , thereby preparing materials with higher crystallinity. , high-quality tin-lead narrow bandgap perovskite films with higher defect state density. In summary, this hole transport layer greatly improves the photoelectric conversion efficiency of the two sub-cells, thereby enabling the preparation of more efficient and stable tandem perovskite solar cells.

The improvement of J _SC is mainly based on the improvement of solar transmittance in the two bands shown in Figure 3 and Figure 4, which allows both wide and narrow band gap perovskite films to absorb more photons. Another reason is that the narrow band gap perovskite film The improvement in quality makes the output current of the bottom cell higher, thus more closely matching the current of the top cell; the improvement of FF is due to the enhanced hole transport and extraction capabilities of the SAM/perovskite interface, which is mainly due to its own material Characteristics, and the more orderly arrangement of self-assembled materials after being anchored on the ITO surface through anchoring groups, and the arrangement orientation is more parallel to ITO, which can effectively improve the hole extraction and transfer efficiency. However, traditional hole transport layers such as PTAA and PEDOT:PSS are arranged randomly on the surface of ITO, and their hole extraction and transfer capabilities are poor. Based on this, the stacked device with the new structure in this application has higher photoelectric conversion efficiency.

Claims (8)

1. An all-perovskite tandem solar cell, characterized in that the hole transport layer material in the wide bandgap top cell is the same as the hole transport layer material in the narrow bandgap bottom cell, and the hole transport layer material is 4-(7-(4-(bis(4-methoxyphenyl)amino)-2,5-difluorophenyl)benzo[c][1,2,5]thiadiazol-4-yl )benzoic acid. 2. The all-perovskite tandem solar cell according to claim 1, wherein the thickness of the hole transport layer in the wide band gap top cell and the hole transport layer in the narrow band gap bottom cell are both 3 -15 nm. 3. The preparation method of the all-perovskite tandem solar cell according to claim 1 or 2, characterized in that it includes the following steps: (1) Dissolve the hole transport layer material in a solvent to prepare a hole transport layer precursor solution; (2) Spin-coat the hole transport layer precursor solution in step (1) on the ITO transparent conductive glass, and perform annealing treatment to prepare the hole transport layer of the wide bandgap top battery; (3) Deposit the wide-bandgap perovskite absorption layer, electron-transport layer and intermediate connection layer in sequence on the hole-transport layer of the wide-band-gap top cell in step (2); (4) Spin-coat the hole transport layer precursor solution in step (1) on the intermediate connection layer in step (3), and perform annealing treatment to prepare the hole transport layer of the narrow bandgap bottom battery; (5) Sequentially deposit a narrow band gap perovskite absorption layer, an electron transport layer and a metal electrode on the hole transport layer of the narrow band gap bottom cell in step (4) to prepare a full perovskite tandem solar cell. 4. The method for preparing an all-perovskite tandem solar cell according to claim 3, wherein the solvent in step (1) is toluene, ethanol, isopropyl alcohol, deionized water or ether, and the hole transport layer The concentration of the precursor solution is 0.3-0.8 mg/mL. 5. The method for preparing an all-perovskite tandem solar cell according to claim 3, characterized in that the spin coating parameters in step (2) and step (4) are the same, specifically: the spin coating speed is 3000-5000 rpm, spin coating time is 20-40 s. 6. The method for preparing an all-perovskite tandem solar cell according to claim 3, characterized in that the annealing parameters in step (2) and step (4) are the same, specifically: the annealing temperature is 80-130°C, Annealing time is 5-20 min. 7. The method for preparing an all-perovskite tandem solar cell according to claim 3, wherein the electron transport layer in step (3) consists of a C ₆₀ or C ₇₀ transport layer and a tin dioxide barrier layer. , the electron transport layer described in step (5) consists of a C ₆₀ or C ₇₀ transport layer and a tin dioxide barrier layer, or a C ₆₀ or C ₇₀ transport layer and a BCP barrier layer. 8. The method for preparing an all-perovskite tandem solar cell according to claim 3, characterized in that in step (3), the intermediate connection layer material is IZO, ITO, AZO or Au, and in step (5), the metal electrode The material is Cu or Ag.