A composite hole transport layer and its application in perovskite solar cells

Abstract

The present invention relates to a composite hole transport layer and its application in perovskite solar cells, wherein the composite hole transport layer is obtained by compounding 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) film and MeO-2PACz film, wherein the surface of the MeO-2PACz film is in contact with the perovskite film. The present invention uses 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) film and MeO-2PACz film as a hole transport layer to increase the transmittance of light, effectively improve the photocurrent of the battery, and optimize the interface with the perovskite film, improve the compactness and grain size of the perovskite film, so that the efficiency of the perovskite solar cell is significantly improved, and the thermal stability and light stability of the perovskite solar cell are also significantly improved. After 500 hours of 85°C thermal stability test or one sunlight light stability test, the battery can still maintain more than 90% of the initial efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic electrical solid-state device structural parts, and in particular relates to a composite hole transport layer and an application thereof in a perovskite solar cell. Background Art

[0002] With the continuous consumption of fossil energy, the energy crisis is gradually emerging. Solar energy is a green, clean energy that is easy to obtain. Among them, perovskite solar cells (PSCs) have developed rapidly in recent years due to their advantages such as low cost, simple preparation, and high power conversion efficiency (PCE).

[0003] Based on their structures, perovskite solar cells are usually divided into two categories: formal (nip) and trans

[0004] (pin), where the hole transport layer (HTL) of the pin structure battery is on the lower side of the perovskite film, and the electron transport layer is on the upper side of the perovskite film. This structure allows it to be used not only as a single cell, but also to be prepared on other solar cells to form a two-terminal stacked solar cell, which has a wider application space. In this structure, the selection and preparation of the transport layer material is crucial. Commonly used hole transport layer materials include [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), nickel oxide, poly [bis (4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA), etc. Commonly used electron transport layer materials include C 60 , PCBM, etc.

[0005] At present, the efficiency of pin-structured perovskite solar cells prepared based on single-molecular-layer hole transport layers such as MeO-2PACz still has room for improvement, and the stability of the cells is significantly different from that of traditional crystalline silicon cells. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a composite hole transport layer and its application in a perovskite solar cell in view of the above-mentioned deficiencies in the prior art. The composite hole transport layer is obtained by compounding a 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) film and a MeO-2PACz film. The PIN structure perovskite solar cell prepared based on the composite hole transport layer has high energy conversion efficiency and good performance stability.

[0007] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0008] A composite hole transport layer is obtained by compounding a 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) film and a MeO-2PACz film, wherein the surface of the MeO-2PACz film is in contact with a perovskite film.

[0009] The present invention also includes a PIN structure perovskite solar cell prepared based on the above-mentioned composite hole transport layer.

[0010] According to the above scheme, the pin structure perovskite solar cell includes, from bottom to top, an ITO transparent conductive substrate, a composite hole transport layer, a perovskite film, an electron transport layer, a buffer layer and an electrode.

[0011] The present invention also includes a method for preparing the above-mentioned PIN structure perovskite solar cell, which specifically includes the following steps:

[0012] 1) dissolving 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) in chlorobenzene to obtain a 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) solution, coating the obtained 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) solution on a clean ITO transparent conductive substrate surface, and then performing annealing treatment to obtain a 2,9,16,23-tetra-tert-butylphthalocyanine copper film on the surface of the ITO transparent conductive substrate;

[0013] 2) dissolving MeO-2PACz in a mixed solvent of ethanol and isopropanol to obtain a MeO-2PACz solution, and then coating the obtained MeO-2PACz solution on the surface of the 2,9,16,23-tetra-tert-butylphthalocyanine copper film in step 1), followed by annealing to obtain a MeO-2PACz film on the surface of the 2,9,16,23-tetra-tert-butylphthalocyanine copper film, wherein the 2,9,16,23-tetra-tert-butylphthalocyanine copper film and the MeO-2PACz film together constitute a composite hole transport layer;

[0014] 3) A perovskite film, an electron transport layer, a buffer layer and an electrode are sequentially prepared on the surface of the composite hole transport layer obtained in step 2) to obtain a pin structure perovskite solar cell.

[0015] According to the above scheme, the concentration of the 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) solution in step 1) is 0.5 to 2.5 mg / mL.

[0016] According to the above scheme, the process conditions of step 1) annealing treatment are: annealing temperature is 120-150° C., and annealing time is 10-20 minutes.

[0017] According to the above scheme, the thickness of the 2,9,16,23-tetra-tert-butylphthalocyanine copper film in step 1) is 1 to 10 nm.

[0018] According to the above scheme, the volume ratio of ethanol to isopropanol in the mixed solvent of ethanol and isopropanol in step 2) is 1 to 4:1.

[0019] According to the above scheme, the concentration of the MeO-2PACz solution in step 2) is 0.5-1.5 mg / mL.

[0020] According to the above scheme, the process conditions of step 2) annealing treatment are: annealing temperature is 100-120° C., and annealing time is 5-10 minutes.

[0021] According to the above scheme, the thickness of the MeO-2PACz film in step 2) is 1 to 10 nm.

[0022] According to the above scheme, the perovskite film in step 3) is Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 ) 3 Perovskite, thickness is 600-800nm.

[0023] According to the above scheme, the electron transport layer is C 60 , with a thickness of 30-40nm, and the buffer layer is BCP with a thickness of 10-20nm.

[0024] According to the above scheme, the electrode is a silver electrode with a thickness of 80 to 100 nm.

[0025] The present invention also includes the application of the above-mentioned composite hole transport layer in the field of perovskite solar cells.

[0026] The beneficial effects of the present invention are as follows: 1. The present invention uses 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) film and MeO-2PACz film as a hole transport layer to increase the transmittance of light, effectively improve the photocurrent of the battery, and optimize the interface with the perovskite film, improve the density and grain size of the perovskite film, and significantly improve the efficiency of the perovskite solar cell. Secondly, the addition of 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) greatly improves the stability of the composite hole transport layer, and the thermal stability and light stability of the perovskite solar cell are also significantly improved. In the aging test, the composite hole layer did not fail or break, and the degradation rate of the perovskite layer was significantly slowed down. After 500 hours of 85°C thermal stability test and one sunlight light stability test, the battery can still maintain more than 90% of the initial efficiency. 2. The preparation method of the present invention has a simple process, is easy to realize industrialization, and has industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1This is a device structure diagram of a composite hole transport layer perovskite solar cell prepared in Example 1 of the present invention;

[0028] Figure 2 This is a scanning electron microscope (SEM) image of the device cross section corresponding to Example 1;

[0029] Figure 3 The UV-visible absorption spectra of different cavity layers of Example 1, Comparative Example 1 and Comparative Example 2 are shown;

[0030] Figure 4 Surface SEM images of the perovskite films of Example 1, Comparative Example 1 and Comparative Example 2;

[0031] Figure 5 The external quantum efficiency and integrated current diagram of the perovskite solar cell obtained in Example 1 and Comparative Example 1;

[0032] Figure 6 The JV curves and specific performance parameters of the perovskite solar cells obtained in Example 1, Comparative Example 1 and Comparative Example 2;

[0033] Figure 7 Graph showing long-term stability of the perovskite solar cells of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings.

[0035] Example 1

[0036] A pin structure perovskite solar cell based on a 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) / MeO-2PACz composite hole transport layer, wherein the preparation method comprises the following steps:

[0037] 1) Cleaning the ITO transparent conductive substrate, immersing the ITO transparent conductive substrate in deionized water, ethanol, and isopropanol in sequence for ultrasonic cleaning for 15 minutes, then drying with nitrogen, and treating with an ultraviolet ozone cleaning machine for 15 minutes;

[0038] 2) dissolving 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) in chlorobenzene to obtain a 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) solution with a concentration of 1.0 mg / mL, and then spin-coating the obtained 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) solution on a clean ITO transparent conductive substrate surface at a spin coating speed of 4000 revolutions per minute for 20 seconds, and then annealing at 120° C. for 10 minutes to obtain a 2,9,16,23-tetra-tert-butylphthalocyanine copper film on the surface of the ITO transparent conductive substrate with a thickness of about 5 nm;

[0039] 3) MeO-2PACz was dissolved in a mixed solvent of ethanol and isopropanol to obtain a MeO-2PACz solution with a concentration of 1.0 mg / mL, wherein the volume ratio of ethanol to isopropanol in the mixed solvent was 4:1, and then the obtained MeO-2PACz solution was spin-coated on the surface of the 2,9,16,23-tetra-tert-butylphthalocyanine copper film at a spin-coating speed of 4000 rpm for 30 seconds, followed by annealing at 100°C for 5 minutes to obtain a MeO-2PACz film on the surface of the ITO transparent conductive substrate with a thickness of about 2 nm. The 2,9,16,23-tetra-tert-butylphthalocyanine copper film and the MeO-2PACz film together formed a composite hole transport layer;

[0040] 4) Preparation of perovskite precursor solution: CsI (19.5 mg), RbI (15.9 mg), MABr (8.4 mg), FAI (219.5 mg), and PbI2 (656.9 mg) were dissolved in 1 mL of DMF / DMSO mixed solvent (the volume ratio of DMF to DMSO was 4:1), and the obtained perovskite precursor solution was coated on the surface of the composite hole transport layer by spin coating to prepare a perovskite film. The film was first spin coated at 1000 rpm for 10 s, then accelerated to 3000 rpm and spin coated for 40 s. 15 s before the end of the second step of spin coating, 150 μL of chlorobenzene was added. After the spin coating was completed, the film was annealed at 100 ° C for 10 minutes to obtain a perovskite film whose composition was Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 ) 3 , thickness is 700-800nm;

[0041] 5) 35nm of C is deposited on the surface of the perovskite film 60 , 10nm BCP, and 100nm silver electrode to obtain a pin structure perovskite solar cell.

[0042] The schematic diagram of the device structure of the pin structure perovskite solar cell prepared in this embodiment is as follows Figure 1 shown.

[0043] Figure 2 This is a cross-sectional SEM image of the pin structure perovskite solar cell prepared in this embodiment.

[0044] Comparative Example 1

[0045] A pin structure perovskite solar cell, which differs from comparative document 1 in that the hole transport layer is a single-layer MeO-2PACz film. The preparation method thereof is different from that of Example 1 in that only chlorobenzene is used for spin coating in step 2) and 2,9,16,23-tetra-tert-butyl copper phthalocyanine is not added, and the remaining steps are the same as those of Example 1.

[0046] Comparative Example 2

[0047] A pin structure perovskite solar cell, which differs from comparative example 1 in that the hole transport layer is a single-layer 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) film, and the preparation method thereof is different from that of example 1 in that in step 3), only a mixed solvent of ethanol and isopropanol (the volume ratio of ethanol to isopropanol is 4:1) is used, and MeO-2PACz is not added, and the remaining steps are the same as those of example 1.

[0048] like Figure 3 The UV-visible absorption spectra of the hole transport layers of Example 1, Comparative Example 1 and Comparative Example 2 show that the transmittance of the single-layer MeO-2PACz film and the single-layer 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) film are lower than that of the composite hole transport layer, and the higher the transmittance, the more conducive it is to the transmission of light and the improvement of photocurrent.

[0049] Figure 4 Surface SEM images of the perovskite films of Example 1, Comparative Example 1 and Comparative Example 2 show that the perovskite film obtained in Example 1 is flat and dense, with a grain size exceeding 1 μm, and the grain size of the perovskite film prepared on the single-layer MeO-2PACz film is significantly smaller, while the perovskite film prepared on the single-layer 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) film is not dense enough, has obvious voids, and has poor film quality.

[0050] Figure 5 The external quantum efficiency and integrated current of the perovskite solar cells obtained in Example 1 and Comparative Example 1 are shown. The integrated current of the cell obtained in Example 1 is 24.58 mA / cm 2 , which is higher than the integrated current of the battery corresponding to Comparative Example 1 (23.51 mA / cm 2 ).

[0051] Figure 6 The JV curves and specific performance parameters of the perovskite solar cells obtained in Example 1, Comparative Example 1 and Comparative Example 2 are shown in Figure 1. The test was conducted under simulated illumination of AM 1.5G. Compared with Example 1, the perovskite solar cell V prepared in Comparative Example 1 is OC and J SCThe efficiency of the perovskite solar cell prepared in Comparative Example 2 is much lower than that of the perovskite solar cell prepared in Example 1, and an obvious hysteresis phenomenon occurs, which is mainly due to the low quality of the perovskite film, the presence of obvious voids, and the poor interface between the void layer and the perovskite.

[0052] Figure 7 The long-term stability test diagram of the perovskite solar cells prepared in Example 1 and Comparative Example 1, the cells were subjected to long-term stability tests under 85°C heating and 1sun illumination conditions, and a JV test was performed every 24 hours to statistically analyze the efficiency. The perovskite solar cell corresponding to the composite hole layer obtained in Example 1 can maintain more than 90% of the initial efficiency after 500 hours of 85°C heating stability or 1sun illumination stability test. However, the efficiency of the cell obtained in Comparative Example 1 decayed significantly during the aging process.

Claims

1. A composite hole transport layer, characterized in that: The composite hole transport layer is obtained by compounding a 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) film and a MeO-2PACz film, wherein the surface of the MeO-2PACz film is in contact with the perovskite film.

2. A pin structure perovskite solar cell prepared based on the composite hole transport layer according to claim 1.

3. The pin structure perovskite solar cell according to claim 2, characterized in that: The pin structure perovskite solar cell comprises, from bottom to top, an ITO transparent conductive substrate, a composite hole transport layer, a perovskite film, an electron transport layer, a buffer layer and an electrode.

4. A method for preparing a pin structure perovskite solar cell according to claim 2 or 3, characterized in that: The specific steps include: 1) dissolving 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) in chlorobenzene to obtain a 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) solution, coating the obtained 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) solution on a clean ITO transparent conductive substrate surface, and then performing annealing treatment to obtain a 2,9,16,23-tetra-tert-butylphthalocyanine copper film on the surface of the ITO transparent conductive substrate; 2) dissolving MeO-2PACz in a mixed solvent of ethanol and isopropanol to obtain a MeO-2PACz solution, and then coating the obtained MeO-2PACz solution on the surface of the 2,9,16,23-tetra-tert-butylphthalocyanine copper film in step 1), followed by annealing to obtain a MeO-2PACz film on the surface of the 2,9,16,23-tetra-tert-butylphthalocyanine copper film, wherein the 2,9,16,23-tetra-tert-butylphthalocyanine copper film and the MeO-2PACz film together constitute a composite hole transport layer; 3) A perovskite film, an electron transport layer, a buffer layer and an electrode are sequentially prepared on the surface of the composite hole transport layer obtained in step 2) to obtain a pin structure perovskite solar cell.

5. The method for preparing a pin structure perovskite solar cell according to claim 4, characterized in that: The concentration of the 2,9,16,23-tetra-tert-butylphthalocyanine copper (II) solution in step 1) is 0.5-2.5 mg / mL; the annealing process conditions in step 1) are: the annealing temperature is 120-150° C., and the annealing time is 10-20 minutes.

6. The method for preparing a pin structure perovskite solar cell according to claim 4, characterized in that: In step 1), the thickness of the 2,9,16,23-tetra-tert-butylphthalocyanine copper film is 1 to 10 nm.

7. The method for preparing a pin structure perovskite solar cell according to claim 4, characterized in that: The volume ratio of ethanol to isopropanol in the mixed solvent of step 2) is 1-4:1; the concentration of the MeO-2PACz solution in step 2) is 0.5-1.5 mg / mL.

8. The method for preparing a pin structure perovskite solar cell according to claim 4, characterized in that: Step 2) The annealing process conditions are: annealing temperature is 100-120° C., and annealing time is 5-10 minutes; Step 2) The thickness of the MeO-2PACz film is 1-10 nm.

9. The method for preparing a pin structure perovskite solar cell according to claim 4, characterized in that: Step 3) The perovskite film is Rb 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 )3 perovskite, with a thickness of 600-800nm; the electron transport layer is C 60 , with a thickness of 30-40nm, and the buffer layer is BCP with a thickness of 10-20nm.

10. Application of the composite hole transport layer according to claim 1 in the field of perovskite solar cells.

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