Method for enhancing pi-pi conjugated polymer hole extraction efficiency and perovskite solar cell

Abstract

The invention discloses a method for enhancing the hole extraction efficiency of a pi-pi conjugated polymer and a perovskite solar cell, and belongs to the technical field of photoelectric materials, and the pi-pi conjugated polymer is poly [bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine] and a derivative thereof with functional groups capable of forming chemical bonds or coordinate bonds on the upper side and the lower side of a molecular chain; wherein the functional group is at least one of amino, carboxyl, phosphate, carbazole and benzene ring. Pi-Pi conjugated polymer molecules capable of being anchored on two sides are adopted as the hole transport layer, the bonding strength with the conductive glass and the perovskite layer is enhanced, interface contact is improved, and the crystal quality of perovskite is improved; the hole extraction capability of the device is enhanced, the non-radiative recombination of current carriers is reduced, the open-circuit voltage and filling factors are improved, the trans-perovskite solar cell with higher efficiency is obtained, and the preferred pi-pi conjugated polymer is insensitive to processing concentration and better in repeatability.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials technology, and particularly relates to a method for enhancing the hole extraction efficiency of π-π conjugated polymers and a perovskite solar cell. Background Technology

[0002] Perovskite solar cells, especially pin-type inverted structures, have become a research hotspot due to their advantages such as low fabrication temperature, simple process, and small hysteresis effect. In this structure, the hole transport layer is crucial to the device performance. π-π conjugated polymers are an important type of hole transport material. However, currently, the π-π conjugated polymer hole transport layer cannot be simultaneously and strongly anchored to the adjacent ITO conductive glass and perovskite layers, resulting in a decrease in hole extraction capability and consequently a decline in the photovoltaic performance and stability of the cell. PTAA, a widely used π-π conjugated polymer molecule in inverted perovskite solar cells, often maintains a single-sided ITO anchorage state when prepared using a simple spin-coating process. The weak interaction with the upper perovskite layer makes the structural strength of the device insufficiently stable, and the interfacial contact degrades over time, leading to low hole mobility and extraction efficiency, resulting in less than ideal cell performance.

[0003] In the existing technology, there are methods to improve the performance of hole transport layer by improving the synthesis method of π-π conjugated polymer. However, these methods have problems such as complex processes and high purification difficulty. Moreover, the introduction of impurity components will reduce the intrinsic stability of hole transport layer, which will be detrimental to the photovoltaic performance and stability of the cell.

[0004] Therefore, providing a simpler and more efficient method to optimize the performance of π-π conjugated polymer hole transport layers and achieve higher photoelectric conversion efficiency by enhancing hole extraction efficiency is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for enhancing the hole extraction efficiency of π-π conjugated polymers and a perovskite solar cell. This invention utilizes π-π conjugated polymer molecules capable of bifacial anchoring as a hole transport layer, enhancing the bonding strength with the conductive glass and perovskite layer, improving interfacial contact, and preserving the crystallinity of the perovskite. Furthermore, the enhanced hole extraction capability of the device reduces non-radiative recombination of charge carriers, improving open-circuit voltage and fill factor, resulting in a more efficient inverse perovskite solar cell. The preferred π-π conjugated polymer in this invention is insensitive to processing concentration, exhibits better repeatability, and is beneficial for future industrialization.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for enhancing the hole extraction efficiency of π-π conjugated polymers, wherein the π-π conjugated polymer is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) and its derivatives, in which functional groups capable of forming chemical bonds or coordination bonds exist on both sides of the molecular chain; The functional group is at least one of amino, carboxyl, phosphate, carbazole and benzene ring.

[0007] The conjugated polymer molecular structure of this invention is mainly based on PTAA, namely poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] and its derivatives, and functional groups that can form chemical bonds or coordination bonds exist on both sides of the chain, which enhances the bonding strength with conductive glass and perovskite layer, improves interfacial contact, and improves the crystallinity of perovskite.

[0008] Preferably, the molecular configuration of the π-π conjugated polymer is at least one of linear, branched, and cross-linked.

[0009] Preferably, the step of preparing the hole transport layer with the π-π conjugated polymer is as follows: preparing the π-π conjugated polymer into a precursor solution, and then coating the precursor solution onto conductive glass and annealing it.

[0010] Preferably, the concentration of the precursor solution is 0.1-5.0 mg / mL, and the solvent in the precursor solution is any one of ethanol, methanol, isopropanol, toluene, chlorobenzene, and ultrapure water.

[0011] Preferably, the coating is at least one of spin coating, blade coating and spray coating; wherein the spin coating speed is 2000-5000 rpm and the spin coating time is 10-60 s.

[0012] Preferably, the annealing treatment is performed at a temperature of 0-100℃ for a time of 1-60 minutes.

[0013] A perovskite solar cell, wherein the perovskite solar cell has a pin-type inverted structure and comprises, from bottom to top, a conductive glass, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and an electrode; wherein the hole transport layer is prepared by the method described above.

[0014] Preferably, the material formula of the perovskite light-absorbing layer is: Cs z FA k MA 1-z-k PbI x Br y Cl 3-x-y The values ​​of x, y, z, and k are all in the range of 0-3.

[0015] Preferably, the material of the electron transport layer is titanium dioxide (TiO2) or [6,6]-phenyl-C. 61 methyl butyrate (PC) 61 BM), [6,6]-phenyl-C 71 methyl butyrate (PC) 71 BM) and C 60 At least one of them.

[0016] Preferably, the material of the electron transport layer is [6,6]-phenyl-C 61 methyl butyrate (PC) 61 BM).

[0017] Preferably, the material of the electrode is selected from at least one of silver, copper and aluminum.

[0018] Preferably, the conductive glass is ITO / FTO conductive glass.

[0019] Preferably, a buffer layer is further included between the electron transport layer and the electrode, and the material of the buffer layer is BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline).

[0020] Preferably, the fabrication method of the perovskite solar cell is as follows: (1) After cleaning and drying the conductive glass, ozone treatment is performed to improve the surface wettability; (2) Prepare a precursor solution of π-π conjugated polymer, and then coat it on the conductive glass obtained in step (1) and anneal it to obtain a π-π conjugated polymer hole transport layer; (3) A perovskite light-absorbing layer is prepared on the π-π conjugated polymer hole transport layer by a blade coating method, a spin coating method, or a vacuum evaporation method; (4) An electron transport layer is prepared on the perovskite light-absorbing layer by a blade coating method, a spin coating method, or a vacuum evaporation method; (5) A buffer layer is prepared on the electron transport layer by means of a blade coating method, a spin coating method, or a vacuum evaporation method; (6) After preparing metal electrodes on the buffer layer by a vacuum evaporation coating machine, a perovskite solar cell is obtained.

[0021] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention has functional groups that can form chemical bonds or coordination bonds on both the upper and lower sides of the preferred π-π conjugated polymer molecular chain, thereby achieving strong double-sided force anchoring with the perovskite layer and conductive glass, improving the interface contact and enhancing the crystal quality of the perovskite film, effectively improving the structural strength and stability of the battery, hole extraction efficiency, open circuit voltage and fill factor, and effectively improving the photoelectric conversion efficiency of the battery. (2) The present invention does not involve complex synthesis processes or purification operations, and the concentration change of π-π conjugated polymer molecules in the present invention is not sensitive to the battery performance, has good repeatability, and is conducive to the future industrial production of high-performance perovskite solar cells. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of the inverted perovskite solar cell prepared in this embodiment. Figure 2 A comparison of the JV characteristic curves of the perovskite solar cell prepared in Example 1 of the present invention; Figure 3 A comparison of the JV characteristic curves of the perovskite solar cell prepared in Example 2 of the present invention; Figure 4 This is a comparison chart of the photoelectric conversion efficiency of perovskite solar cells prepared with different concentrations of PTAA and PTAA-3POOH as hole transport layers in Example 3 of the present invention. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 This invention provides a PTAA-3POOH material for use in inverted perovskite solar cells (structure as follows). Figure 1 The preparation method includes the following steps: (1) For the surface treatment of ITO conductive glass, the order is to use surface cleaner, deionized water and ethanol for ultrasonic cleaning, then use nitrogen to dry, and finally treat the substrate with ultraviolet ozone for 15 minutes. (2) Disperse polyPTAA and PTAA-3POOH in an appropriate amount of toluene, heat and stir at 60°C for 1-2 h to obtain PTAA solution and PTAA-3POOH solution with a concentration of 1 mg / mL, respectively; wherein, the structural formulas of PTAA and PTAA-3POOH are as follows: ; (3) Transfer the ITO conductive glass obtained in step (1) to a spin coater in a nitrogen glove box. Take the PTAA solution and PTAA-3POOH solution obtained in step (2) and spin coat them evenly on the surface of the ITO conductive glass. Spin coat at 5000 rpm for 30s, and then anneal at 100℃ for 10min to obtain the PTAA hole transport layer (control group) and the PTAA-3POOH hole transport layer. (4) Dissolve FAPbI3 (with 15% MACl) in 1 mL of a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 4:1, heat and stir until completely dissolved to prepare a 1.5 M FAPbI3 perovskite solution. (5) Take the perovskite solution obtained in step (4) and spin coat it onto the PTAA hole transport layer and PTAA-3POOH hole transport layer obtained in step (3) respectively. Spin coat it at 1000 rpm (10 s) + 4500 rpm (40 s) with chlorobenzene anti-solvent added in the last 8 s. After removing it, anneal it at 100℃ for 20 min to obtain FAPbI3 perovskite film. (6) Take 20mg of PC 61 PC obtained by dissolving BM in 1 mL of chlorobenzene solvent 61 The BM solution was then spin-coated onto the perovskite film obtained in step (5) at a speed of 2000 rpm for 30 s to obtain PC. 61 BM electron transport layer; (7) Dissolve 1 mg of BCP in 2 mL of isopropanol solvent, stir to dissolve the obtained BCP solution, and then spin-coat the supernatant of the BCP solution onto the PC obtained in step (6). 61 The surface of the BM electron transport layer is rotated at 5000 rpm for 30 seconds to obtain a buffer layer; (8) An Ag electrode with a thickness of 100-110 nm was prepared on the buffer layer obtained in step (7) using a vacuum evaporation coating machine; The performance tests of the perovskite solar cells are shown in Table 1 and 2. Figure 2 : Table 1. Photovoltaic parameters of solar cells corresponding to PTAA and PTAA-3POOH hole transport layers.

[0026] like Figure 2 Table 1 shows the results at AM 1.5, 100 mW / cm². 2Under standard light intensity irradiation, the JV performance comparison results of solar cells fabricated with a conventional PTAA hole transport layer (control group) and those using the PTAA-3POOH hole transport layer of this embodiment show that, thanks to the enhanced hole extraction capability and reduced internal defects, the open-circuit voltage of the cell using the PTAA-3POOH hole transport layer (compared to PTAA) increased from 1.128V to 1.160V, the fill factor increased from 76.89% to 84.22%, and a photoelectric conversion efficiency of 24.48% was achieved (an improvement of 2.64%). Figure 2 (As shown).

[0027] Example 2 Perovskite solar cells were prepared according to the process described in Example 1 of this invention. The hole transport layer molecular materials were selected from PTAA and PTAA-POOH, respectively, with the conditions kept constant. The results are shown in Table 2 and [Table 3]. Figure 3 : Table 2 Photovoltaic parameters of battery devices corresponding to PTAA and PTAA-POOH hole transport layers

[0028] As shown in Table 2 and Figure 3 The figure shows the effect at AM 1.5, 100mW / cm 2 Under standard light intensity irradiation, the JV performance of solar cells prepared with traditional PTAA hole transport layers (control group) and those prepared with PTAA-POOH hole transport layers according to this embodiment was compared. The results showed that the open-circuit voltage and fill factor of the cells prepared with the PTAA hole transport layer in the control group were 1.127V and 74.17%, respectively, while those prepared with the PTAA-POOH hole transport layer were 1.151V and 82.01%, respectively. Both showed significant improvements, and the photoelectric conversion efficiency also increased from 24.15% to 21.16%. This indicates that the present invention, by optimizing π-π conjugated polymer molecules for reinforcement and anchoring at the upper and lower interfaces, enhances the hole extraction capability of the hole transport layer, which is an effective method for improving the photovoltaic performance of solar cells.

[0029] Example 3 Perovskite solar cells were prepared according to the process described in Example 1 of this invention, wherein the concentrations of PTAA and PTAA-3POOH solutions were varied and set to 0.5 mg / mL, 1.0 mg / mL, 1.5 mg / mL, and 2 mg / mL, respectively; the conditions were kept constant, and the results are shown in Tables 3-4 and 4. Figure 4 : Table 3. Photovoltaic parameters of battery devices corresponding to different concentrations of PTAA hole transport layer

[0030] Table 4. Photovoltaic parameters of battery devices corresponding to different concentrations of PTAA-3POOH hole transport layer

[0031] As shown in Tables 3 and 4, Figure 4 As shown, at AM 1.5, 100mW / cm 2 Under standard light intensity irradiation, the solar cell corresponding to the PTAA hole transport layer (control group) achieved a maximum photoelectric conversion efficiency of 23.06%, with significant performance differences at different concentrations, requiring relatively strict process control. In contrast, the solar cell corresponding to the PTAA-3POOH hole transport layer of this invention exhibited photoelectric conversion efficiency that was not sensitive to concentration changes, achieving a maximum of 24.74%. The maximum difference in photoelectric conversion efficiency at different concentrations was 1.19% (compared to 4.25% for the control PTAA group). Furthermore, as the concentration of the π-π conjugated polymer increases, the thickness and structure of the prepared hole transport layer also change (see Table 3). Figure 4 The results show that the PTAA-3POOH in this invention is not sensitive to processing concentration, and the fabricated devices can achieve better repeatability, which is beneficial to the future industrial production of perovskite batteries.

[0032] In summary, the embodiments of the present invention, by employing π-π conjugated polymer molecules capable of bifacial anchoring in inverted perovskite solar cells, enhance the bonding strength with ITO conductive glass and perovskite, improve interfacial contact, improve the crystal quality of perovskite, enhance the hole extraction capability of the device, and reduce nonradiative recombination of charge carriers, thereby increasing the open-circuit voltage and fill factor of the cell and obtaining a more efficient inverted perovskite solar cell. Furthermore, the preferred π-π conjugated polymer in this invention is insensitive to processing concentration and exhibits better repeatability.

[0033] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for enhancing the hole extraction efficiency of π-π conjugated polymers, characterized in that, The π-π conjugated polymer is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] and its derivatives, in which functional groups capable of forming chemical bonds or coordination bonds exist on both sides of the molecular chain; The functional group is at least one of amino, carboxyl, phosphate, carbazole and benzene ring.

2. The method for enhancing the hole extraction efficiency of π-π conjugated polymers according to claim 1, characterized in that, The molecular configuration of the π-π conjugated polymer is at least one of linear, branched, and cross-linked.

3. The method for enhancing the hole extraction efficiency of π-π conjugated polymers according to claim 1, characterized in that, The steps for preparing the hole transport layer using the π-π conjugated polymer are as follows: prepare a precursor solution of the π-π conjugated polymer, and then coat the precursor solution onto conductive glass and anneal it.

4. The method for enhancing the hole extraction efficiency of π-π conjugated polymers according to claim 3, characterized in that, The concentration of the precursor solution is 0.1-5.0 mg / mL, and the solvent in the precursor solution is any one of ethanol, methanol, isopropanol, toluene, chlorobenzene, and ultrapure water.

5. The method for enhancing the hole extraction efficiency of π-π conjugated polymers according to claim 3, characterized in that, The coating is at least one of spin coating, blade coating and spray coating; wherein the spin coating speed is 2000-5000 rpm and the spin coating time is 10-60 s.

6. The method for enhancing the hole extraction efficiency of π-π conjugated polymers according to claim 3, characterized in that, The annealing process is performed at a temperature of 0-100℃ for a time of 1-60 minutes.

7. A perovskite solar cell, characterized in that, The perovskite solar cell has a pin-type inverted structure and includes, from bottom to top, a conductive glass, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and an electrode; wherein the hole transport layer is prepared by the method described in any one of claims 1-6.

8. A perovskite solar cell according to claim 7, characterized in that, The general formula for the perovskite light-absorbing layer is: Cs z FA k MA 1-z-k PbI x Br y Cl 3-x-y The values ​​of x, y, z, and k are all in the range of 0-3.

9. A perovskite solar cell according to claim 7, characterized in that, The electron transport layer is made of tin dioxide, titanium dioxide, methyl [6,6]-phenyl-C61-butyrate, and C 60 At least one of [6,6]-phenyl-C71-butyrate methyl ester.

10. A perovskite solar cell according to claim 7, characterized in that, The electrode is made of at least one of silver, copper, and aluminum.

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