Trans-perovskite solar cell based on hole transport layer interface cleaning modification and preparation method thereof

Abstract

The invention discloses an interface cleaning modification trans-perovskite solar cell based on a hole transport layer and a preparation method thereof. The trans-perovskite solar cell comprises the hole transport layer, a perovskite light absorption layer, an interface modification layer and a loose soil layer. Wherein the interface modification layer and the loose soil layer are arranged between the hole transport layer and the perovskite light absorption layer; the interface modification layer is a self-assembly molecular layer, and the loose soil layer material is selected from a solvent with good solubility to the hole transport layer. The efficiency and the stability of the PTAA-based trans-perovskite solar cell prepared by the method are remarkably improved, the optimal PTAA interface is cleaned and modified, the highest photoelectric conversion efficiency of the PTAA-based trans-perovskite solar cell is 24.18%, and compared with a PTAA-based trans-perovskite solar cell only subjected to interface modification, the photoelectric conversion efficiency of the PTAA-based trans-perovskite solar cell is improved by nearly two points.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite solar cells, and in particular relates to an inverted perovskite solar cell based on interface cleaning and modification of a hole transport layer and a preparation method thereof. Background Art

[0002] Perovskite solar cells (PSCs), the third generation of photovoltaic cells, are considered one of the most promising photovoltaic cells. Among them, inverse perovskite solar cells (IPSCs) have become one of the most popular research targets due to their high photoelectric conversion efficiency, low cost, and simple process.

[0003] In recent years, the device performance of inverse perovskite solar cells has advanced dramatically, with the highest single-junction photoelectric conversion efficiency reaching 26.92%. PTAA, a conductive organic polymer with high mechanical flexibility and photothermal stability, is widely used as a hole transport layer in inverse perovskite solar cells. However, PTAA's inherent high hydrophobicity easily hinders interfacial contact with the perovskite light-absorbing layer, resulting in a high density of buried interface defects and severe non-radiative recombination, which in turn reduces device performance. Interface modification is an important approach to improve this problem. Therefore, self-assembled molecular materials (SAMs) with excellent wettability have become one of the commonly used interface modification materials to improve the interface between PTAA and perovskite. However, SAMs suffer from severe uneven distribution, which makes this single interface modification unable to fully modify PTAA and reduce buried defects.

[0004] Therefore, there is an urgent need in this field to develop an efficient, stable, and simple process for interface modification of the hole transport layer to improve the performance of PTAA-based inverse perovskite solar cells. Summary of the Invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and to briefly introduce some preferred embodiments.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide an inverted perovskite solar cell based on interface cleaning and modification of a hole transport layer.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: an inverted perovskite solar cell based on interface cleaning and modification of a hole transport layer, comprising: Hole transport layer, perovskite light absorption layer, interface modification layer and loose soil layer; The interface modification layer and the loose soil layer are arranged between the hole transport layer and the perovskite light absorption layer; The interface modification layer is a self-assembled molecular layer, and the loose soil layer material is selected from a solvent that has good solubility for the hole transport layer.

[0009] As a preferred embodiment of the inverse perovskite solar cell of the present invention, the self-assembled molecular layer of the interface modification layer includes MeO-2PACz, the solvent of the self-assembled molecular layer is isopropanol, and the concentration of the self-assembled molecular layer is 0.3-0.5 mg / ml.

[0010] As a preferred embodiment of the inverse perovskite solar cell described in the present invention, the material of the loose soil layer is selected from a good solvent of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], including any one of chlorobenzene, dichlorobenzene, 2-methylanisole, anisole, tetrahydrofuran, and chloroform.

[0011] As a preferred solution of the inverse perovskite solar cell of the present invention, the inverse perovskite solar cell further includes a transparent conductive anode, an electron transport layer and a metal conductive cathode.

[0012] As a preferred solution of the inverse perovskite solar cell of the present invention, wherein: the transparent conductive anode is FTO glass; The electron transport layer includes C60 and BCP; The metal conductive cathode is Ag; The hole transport layer is a PTAA organic polymer layer spin-coated on a transparent conductive anode; The perovskite light-absorbing layer is a coating prepared by spin coating an inverse perovskite precursor solution in a one-step process, wherein the antisolvent is chlorobenzene, and the volume ratio of the antisolvent to the inverse perovskite precursor solution is 3:1.

[0013] As a preferred embodiment of the inverse perovskite solar cell of the present invention, the inverse perovskite precursor solution includes a solute and a solvent, wherein the solute is lead iodide, iodomethane, cesium iodide, lead chloride and methylammonium chloride, and the solvent is a mixture of N,N-dimethylformamide and dimethyl sulfoxide.

[0014] As a preferred embodiment of the inverse perovskite solar cell of the present invention, the structure of the inverse perovskite solar cell is configured from bottom to top as follows: Transparent conductive anode; hole transport layer; Interface modification layer; Loose soil layer; Perovskite light-absorbing layer; electron transport layer; Metal conductive cathode.

[0015] Another object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing an inverse perovskite solar cell, comprising: The cleaned and dried FTO transparent conductive substrate is treated with ultraviolet ozone to obtain a transparent conductive anode; A PTAA polymer layer was spin-coated on the ozone-cooled FTO, and then annealed and cooled to form a hole transport layer; Spin-coating a self-assembled molecular layer on the hole transport layer, and annealing and cooling to form an interface modification layer; Spin-coating the solvent of the hole transport layer on the interface modification layer, and forming a loose soil layer after annealing and cooling; Spin coating an inverse perovskite precursor solution on the loose soil layer to prepare a perovskite light absorbing layer; vacuum depositing an electron transport layer on the perovskite light absorbing layer; A metal electrode layer is deposited on the electron transport layer.

[0016] As a preferred embodiment of the method for preparing an inverse perovskite solar cell according to the present invention, wherein: the hole transport layer is formed, wherein the solvent of the PTAA organic polymer layer is chlorobenzene, the concentration of the PTAA organic polymer layer is 2-2.2 mg / ml, the rotation speed is 6000 rpm, the spin coating time is 30 s, the annealing temperature is 150°C, and the annealing time is 10 min; The interface modification layer is formed by spin coating a self-assembled molecular layer on the hole transport layer at a rotation speed of 5000 rpm, a spin coating time of 30 s, an annealing temperature of 100° C., and an annealing time of 10 min; The formation of the loose soil layer, wherein the rotation speed is 5000 rpm, the spin coating time is 30 s, the annealing temperature is 100 ° C, and the annealing time is 5 min; The perovskite light-absorbing layer is prepared by the method, wherein the spin coating speed is 1000 rpm at a low speed and the spin coating time is 10 s; the high speed is 5000 rpm and the spin coating time is 35 s, the anti-solvent is quickly added dropwise in the last 15 s, the annealing temperature is 100° C., and the annealing time is 30 min.

[0017] As a preferred embodiment of the method for preparing an inverse perovskite solar cell according to the present invention, the thickness of the inverse perovskite light-absorbing layer is 300-1000 nm.

[0018] Beneficial effects of the present invention: (1) The present invention uses MeO-2PACz as the interface modification layer of the hole transport layer. Through MeO-2PACz, the hole transport layer can be interacted with each other downwards through π-π and the deposited perovskite light absorbing layer can be bridged upwards, thereby enhancing the interface contact between the hole transport layer and the perovskite light absorbing layer. On the other hand, the present invention uses a common solvent to soak and clean the hole transport layer. The solvent enters the hole transport layer from the position where MeO-2PACz does not cover PTAA to achieve the purpose of "loosening the soil" and cleans the surface PTAA that is not in close contact with the transparent conductive substrate, so that the contact between MeO-2PACz and the hole transport layer is closer and the interaction is stronger. After spin coating and cleaning, dense and orderly coverage of the hole transport layer by MeO-2PACz is achieved, which makes up for the deficiency of uneven distribution of MeO-2PACz. At the same time, MeO-2PACz can passivate the defects of the perovskite buried interface. Specifically, the phosphonic acid groups in MeO-2PACz bind to the uncoordinated lead ions (Pb 2+ ) form strong coordination bonds. This interaction effectively passivates buried defects, inhibits non-radiative recombination, and improves the transmission efficiency of photogenerated carriers. In addition, the uniformly distributed self-assembled molecular layer is conducive to the high-quality deposition of the perovskite light-absorbing layer, improves the perovskite crystallization process, and makes the crystallinity higher, thereby reducing the surface roughness and interface defects of the perovskite light-absorbing layer. Solvent cleaning of the hole transport layer further improves the crystallization quality of the perovskite film on the basis of improving the contact ability between the hole transport layer and the upper interface, and significantly enhances the photovoltaic performance and environmental stability of perovskite solar energy.

[0019] (2) The efficiency and stability of the PTAA-based inverse perovskite solar cells prepared by the present invention have been significantly improved. Among them, the best device is the one after the PTAA interface is cleaned and modified, and its highest photoelectric conversion efficiency is 24.18%. Compared with the PTAA-based inverse perovskite solar cells that have only undergone interface modification, its photoelectric conversion efficiency has been improved by nearly 2 points; the prepared Cs 0.1 FA 0.9 After 500 hours of heating and storage in a N2 environment, the unpackaged PbI3 perovskite solar cell still maintains an initial photoelectric conversion efficiency of more than 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them: Figure 11 is a current density-voltage curve diagram of the device before and after interface cleaning and modification in an embodiment of the present invention; Figure 2 1 is an X-ray diffraction (XRD) diagram of the perovskite film before and after interface cleaning and modification in an embodiment of the present invention; Figure 3 1 is a transient fluorescence spectrum (PL) graph of the perovskite film before and after interface cleaning and modification in an embodiment of the present invention; Figure 4 1 is a graph showing the normalized photoelectric conversion efficiency of the device before and after interface cleaning and modification in an embodiment of the present invention after heating and storing on a 65° C. hot plate in an N 2 environment for 500 h. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0022] Raw materials used in the embodiments of the present invention: Raw material sources: lead iodide (PbI2, purity ≥99.99%), lead chloride (PbCI2, purity ≥99.99%), methylammonium iodide (MAI, purity 99.5%), methylammonium chloride (MACl, purity 99.5%), PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], molecular weight: 6000-15000 g mol) - 1 ), bathoquinone (BCP) and C60 were purchased from Xi'an Polymerization Technology Co., Ltd.; tetrahydrofuran (THF, Standard for GC, purity ≥99.6%); MeO-2PACz (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid) was purchased from TCI Development Co., Ltd. (Shanghai, China); chlorobenzene (CB, purity ≥99.9%) was purchased from Thermo Fisher Scientific. Dimethyl sulfoxide (DMSO, purity ≥99.9%) and N,N-dimethylformamide (DMF, purity ≥99.9%) were purchased from Alpha Asar. All chemical reagents were used as received without further treatment.

[0023] Example 1 (1) The FTO glass was soaked in a detergent solution and ultrasonically cleaned for 15 min. Then, it was ultrasonically cleaned with deionized water three times and anhydrous ethanol three times at a constant temperature of 40 °C for 15 min, and finally dried in an oven at 50 °C for storage.

[0024] (2) Preparation of perovskite precursor solution: 1.5 eV: 0.16 mol / L CsI, 1.44 mol / L FAI, 1.6 mol / L PbI2, 0.08 mol / L PbCl2 and 0.08 mol / L MACl were mixed in DMF:DMSO = 4:1 to prepare the perovskite solution, and stirred at room temperature for 2-3 h.

[0025] (3) The dried FTO was irradiated with UV ozone for 20 min in an air environment.

[0026] (4) In a N2 environment, the ozone-treated FTO was placed on a spin coater and a layer of a mixed solution of PTAA and chlorobenzene (PTAA concentration was 2 mg / mL) was spin-coated as a hole transport layer (12 nm), 70 μL each time, the rotation speed was 6000 rpm, and the spin coating time was 30 s; then it was placed on a 150°C hot stage for annealing for 10 min.

[0027] (5) In a N2 environment, a mixed solution of MeO-2PACz and isopropanol (concentration of 0.3 mg / ml) was spin-coated on the cooled hole transport layer as an interface modification layer (1.5 nm), 80 μL each time, the rotation speed was 5000 rpm, and the spin coating time was 30 s; then it was placed on a hot plate for annealing at 100 °C for 10 min.

[0028] (6) In a N2 environment, the cleaning solvent chlorobenzene of the hole transport layer was spin-coated on the cooled interface modification layer, 70 μL each time, the rotation speed was 5000 rpm, and the spin coating time was 30 s; then it was placed on a 100 °C hot plate for annealing for 5 minutes to form a cleaning "loose soil" layer with a structure of FTO / PTAA / SAM / CB.

[0029] (7) Spin-coat a layer of perovskite solution on the cooled cleaned "loose soil" layer in a N2 environment, 70 μL each time; Step 1: rotation speed 1000 r / min, acceleration 200, spin coating time 10 s, step 2: rotation speed 5000 r / min, acceleration 2500, spin coating time 35 s, at the 12th second before the end, 180 μL of chlorobenzene (CB) was quickly added as antisolvent; Then anneal on a hot plate at 100°C for 30 min; The thickness of the perovskite light-absorbing layer is 600nm.

[0030] (8) On the perovskite light-absorbing layer prepared in step (7), 8 nm thick BCP and 20 nm thick C were sequentially deposited by vacuum evaporation. 60 as an electron transport layer.

[0031] (9) On the electron transport layer prepared in step (8), a 100 nm thick Ag electrode was deposited by vacuum evaporation to complete the preparation of the inverse perovskite solar cell.

[0032] The Cs prepared in this example 0.1 FA 0.9 The PbI3 (1.5 eV) cell has a photoelectric conversion efficiency of 24.18%; the JV measurement value was obtained by using a Kelly 2400 power supply and a standard AM 1.5 G solar simulator (O'Reilly 94043A, Newport, USA, AM1.5, 100 mW / cm2).

[0033] Example 2 In step 6 of this embodiment, the cleaning solvent chlorobenzene is replaced with 2-methylanisole (2-MTOL), and the remaining steps are the same as those in embodiment 1. After step 6, the structure is FTO / PTAA / SAM / 2-MTOL.

[0034] Example 3 In step 6 of this embodiment, the cleaning solvent chlorobenzene is replaced with tetrahydrofuran (THF), and the remaining steps are the same as those in embodiment 1. The structure is FTO / PTAA / SAM / THF.

[0035] Comparative Example 1 In step 6 of this comparative example, no cleaning solvent is spin-coated on the interface modification layer, and the remaining steps are the same as those in Example 1. After step 6, the structure is FTO / PTAA / SAM.

[0036] Comparative Example 2 In step 5 of this comparative example, MeO-2PACz is not spin-coated on PTAA, and in step 6 of this comparative example, a cleaning solvent is not spin-coated on the interface modification layer. The remaining steps are the same as those in Example 1. After step 6, the structure is FTO / PTAA.

[0037] Related test analysis: Table 1 Photoelectric conversion parameters of solar cell devices As can be seen from the above, after the interface cleaning and modification of the hole transport layer in the present invention, its maximum photoelectric conversion efficiency is 24.18%. Compared with the perovskite solar cell without interface cleaning and modification, its maximum photoelectric conversion efficiency increases from 20.54% to 24.18%.

[0038] Figure 1The current density-voltage curves of the device before and after interface cleaning and modification are shown in Table 1. The specific performance parameters are shown in Table 1. It can be seen that after the PTAA hole transport layer is interface cleaned and modified, the open circuit voltage of the device increases from 1.01V to 1.09V, and the short-circuit current density and fill factor also increase significantly. Therefore, the photoelectric conversion efficiency of the device is increased to 24.18% at the highest; and from interface modification to interface cleaning and modification, the device performance shows a gradient enhancement, indicating that interface cleaning and modification plays a key role.

[0039] Figure 2 These are the X-ray diffraction (XRD) patterns of the perovskite films before and after interface cleaning and modification obtained in Example 1 and Comparative Example 2. It can be clearly seen from the figures that the main peak intensity of the perovskite of the film prepared after interface cleaning and modification is much stronger than that of the unmodified one, and the half-peak width is reduced from the original 0.1° to 0.06°, almost half the value. These results indicate that the film after cleaning and modification has higher crystallinity and better quality of the perovskite film, so the final device prepared is also the best.

[0040] Figure 3 Figures 2 and 3 show the transient fluorescence spectra (PL) of the perovskite film before and after interface cleaning and modification in Example 1 and Comparative Example 2. It can be seen that compared with the control group, the perovskite film after interface cleaning and modification has significantly stronger PL intensity, indicating that the perovskite film deposited on the hole transport layer after interface cleaning and modification has better quality, passivates buried defects, and reduces non-radiative recombination.

[0041] Figure 4 This is a graph of the normalized photoelectric conversion efficiency of the devices in Example 1 and Comparative Example 2 before and after interface cleaning and modification, after heating and storing on a 65°C hot plate in an N2 environment for 500 hours. The device after interface cleaning and modification can still maintain 95% of its original efficiency after 500 hours of continuous high-temperature heating, while the untreated device only maintains 90% of the original efficiency. It can be seen that the thermal stability of the device has been greatly improved, which makes it more adaptable to some high-temperature environments.

[0042] 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 the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the present invention.

Claims

1. An inverted perovskite solar cell based on interface cleaning and modification of a hole transport layer, characterized in that: include, Hole transport layer, perovskite light absorption layer, interface modification layer and loose soil layer; The interface modification layer and the loose soil layer are arranged between the hole transport layer and the perovskite light absorption layer; The interface modification layer is a self-assembled molecular layer, and the loose soil layer material is selected from a solvent that has good solubility for the hole transport layer.

2. The inverted perovskite solar cell according to claim 1, wherein: The self-assembled molecular layer of the interface modification layer includes MeO-2PACz, the solvent of the self-assembled molecular layer is isopropanol, and the concentration of the self-assembled molecular layer is 0.3-0.5 mg / ml.

3. The inverted perovskite solar cell according to claim 1 or 2, wherein: The material of the loose soil layer is selected from a good solvent of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], including any one of chlorobenzene, dichlorobenzene, 2-methylanisole, anisole, tetrahydrofuran and chloroform.

4. The inverted perovskite solar cell according to claim 1, wherein: The inverse perovskite solar cell further includes a transparent conductive anode, an electron transport layer and a metal conductive cathode.

5. The inverted perovskite solar cell according to claim 4, wherein: The transparent conductive anode is FTO glass; The electron transport layer includes C60 and BCP; The metal conductive cathode is Ag; The hole transport layer is a PTAA organic polymer layer spin-coated on a transparent conductive anode; The perovskite light-absorbing layer is a coating prepared by spin coating an inverse perovskite precursor solution in a one-step process, wherein the antisolvent is chlorobenzene, and the volume ratio of the antisolvent to the inverse perovskite precursor solution is 3:

1.

6. The inverted perovskite solar cell according to claim 5, wherein: The inverse perovskite precursor solution includes a solute and a solvent, wherein the solute is lead iodide, iodomethane, cesium iodide, lead chloride and methylammonium chloride, and the solvent is a mixture of N,N-dimethylformamide and dimethyl sulfoxide.

7. The inverted perovskite solar cell according to claim 1 or 4, wherein: The structure of the inverse perovskite solar cell is configured from bottom to top as follows: Transparent conductive anode; hole transport layer; Interface modification layer; Loose soil layer; Perovskite light-absorbing layer; electron transport layer; Metal conductive cathode.

8. The method for preparing an inverse perovskite solar cell according to any one of claims 1 to 7, characterized in that: include, The cleaned and dried FTO transparent conductive substrate is treated with ultraviolet ozone to obtain a transparent conductive anode; A PTAA polymer layer is spin-coated on the ozone-cooled FTO, and then annealed and cooled to form a hole transport layer with a thickness of 10-15 nm. A self-assembled molecular layer is spin-coated on the hole transport layer, and an interface modification layer is formed after annealing and cooling. The thickness of the interface modification layer is 1-2 nm. The solvent of the hole transport layer is spin-coated on the interface modification layer, and a loose soil layer is formed after annealing and cooling; Spin-coating an inverse perovskite precursor solution on the loose soil layer to prepare a perovskite light-absorbing layer; An electron transport layer is vacuum deposited on the perovskite light-absorbing layer, with a thickness of 28 nm. A metal electrode layer is deposited on the electron transport layer, and the thickness of the metal electrode layer is 100 nm.

9. The preparation method according to claim 8, wherein: The hole transport layer is formed, wherein the solvent of the PTAA organic polymer layer is chlorobenzene, the concentration of the PTAA organic polymer layer is 2-2.2 mg / ml, the rotation speed is 6000 rpm, the spin coating time is 30 s, the annealing temperature is 150° C., and the annealing time is 10 min; The interface modification layer is formed by spin coating a self-assembled molecular layer on the hole transport layer at a rotation speed of 5000 rpm, a spin coating time of 30 s, an annealing temperature of 100° C., and an annealing time of 10 min; The loose soil layer is formed, wherein the rotation speed is 5000 rpm, the spin coating time is 30 s, the annealing temperature is 100° C., and the annealing time is 5 min; The perovskite light-absorbing layer is prepared by the method, wherein the spin coating speed is 1000 rpm at a low speed and the spin coating time is 10 s; the high speed is 5000 rpm and the spin coating time is 35 s, the anti-solvent is quickly added dropwise in the last 15 s, the annealing temperature is 100° C., and the annealing time is 30 min.

10. The preparation method according to claim 9, wherein: The thickness of the perovskite light-absorbing layer is 300-1000 nm.

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