Perovskite solar cell based on co-doping of hole transport layer and preparation method thereof

Abstract

The application belongs to the technical field of semiconductor devices, and discloses a perovskite solar cell based on co-doping of a hole transport layer and a preparation method thereof. The perovskite solar cell uses a benzoic acid molecule containing a para-functional group to dope a self-assembled molecule MeO-2PACz as a co-doped hole transport layer, improves the clustering phenomenon of the self-assembled molecule through a co-doping strategy, and improves the coverage of the hole transport layer of the perovskite solar cell. The preparation method uses a solution spin coating method to prepare, and from bottom to top, there are an ITO substrate, a co-doped hole transport layer, a perovskite layer, an upper interface modification layer, an electron transport layer, a hole blocking layer and an electrode. The co-doped hole transport layer is a solution volume ratio of 2:8 of the benzoic acid molecule containing the para-functional group and the self-assembled molecule MeO-2PACz. Finally, the efficiency of a photovoltaic device with an effective active area of 4 square centimeters is increased from 20.91% to 21.86% and 22.75%.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of semiconductor technology, and relates to improvement of materials of a perovskite solar cell, in particular to a perovskite solar cell based on co-doping of a hole transport layer and a preparation method thereof. BACKGROUND

[0002] Perovskite solar cells are mainly divided into formal perovskite solar cells and reverse perovskite solar cells, and the difference between the two lies in the deposition sequence of the electron transport layer and the hole transport layer. The conventional reverse perovskite solar cell device has lower efficiency than the formal device, but has much higher stability than the formal perovskite solar cell device. With the introduction of self-assembled molecules into the reverse perovskite solar cell, the efficiency is broken through and improved, so the reverse perovskite solar cell exceeds the formal device in both efficiency and stability. It has very considerable commercial value and can become the next generation of photovoltaic power generation materials.

[0003] Although the introduction of self-assembled molecules greatly improves the performance of the reverse perovskite solar cell device, the self-assembled molecules still have many defects as the hole transport material. The most important problem is that when the self-assembled molecules are spin-coated on the target substrate by the conventional spin-coating technology, the amphiphilic nature of the self-assembled molecules usually forms a cluster phenomenon, thereby affecting the coverage of the self-assembled molecules, resulting in low hole extraction efficiency, aggravating non-radiative recombination, and hindering the performance of the device. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a perovskite solar cell based on co-doping of a hole transport layer and a preparation method thereof. The para-position benzonic acid molecules containing different functional groups are mixed together with the self-assembled molecules to improve the cluster phenomenon of the self-assembled molecules, improve the coverage of the hole transport material of the perovskite solar cell, and improve the carrier extraction efficiency to obtain a reverse perovskite solar cell device with higher stability and efficiency.

[0005] The perovskite solar cell based on co-doping of a hole transport layer comprises, from bottom to top, an ITO substrate, a co-doped hole transport layer, a perovskite layer, an upper interface modification layer, an electron transport layer, a hole blocking layer and an electrode. The co-doped hole transport layer is a self-assembled molecule MeO-2PACz doped with para-position functional group-containing benzonic acid molecules, and the mass ratio of the para-position functional group-containing benzonic acid molecules to the self-assembled molecule MeO-2PACz is 2:8.

[0006] As a preferred, the para-position functional group-containing benzonic acid molecules are para-mercaptobenzoic acid, para-trifluorobenzoic acid or para-cyanobenzoic acid.

[0007] As a preferred, the upper interface modification layer is PEAI, the electron transport layer is C60, and the hole blocking layer is BCP.

[0008] The application discloses a preparation method of a perovskite solar cell based on co-doping of a hole transport layer.

[0009] Step 1: prepare a self-assembled molecule solution with a concentration of 0.5 mg / ml and a p-functional-group-containing benzoic acid molecule solution; mix the p-functional-group-containing benzoic acid molecule solution with the self-assembled molecule solution in a volume ratio of 2:8 to obtain a co-doped self-assembled molecule solution.

[0010] Step 2: sequentially clean the glass substrate ITO using pure water, ethanol and isopropanol three times, and then place the glass substrate ITO into an oven to dry the surface solution.

[0011] Step 3: uniformly spin-coat the co-doped self-assembled molecule solution on the surface of the glass substrate ITO using a spin coater, set the speed of the spin coater to 3000-4000 r / s, the acceleration to 2000-3000 r / s and the time to 25-30 s; then heat the spin-coated glass substrate ITO using a heating table at 100 DEG C for 10 minutes to obtain a co-doped self-assembled molecule layer with a thickness of 1-5 nm. 2

[0012] Step 4: prepare a perovskite precursor solution and filter the perovskite precursor solution.

[0013] Step 5: uniformly spin-coat the filtered perovskite precursor solution on the surface of the co-doped self-assembled molecule layer using a two-step spin-coating method, drop chlorobenzene solution at the last 10-15 s to perform anti-solvent flushing, and then heat the perovskite layer using a heating table at 100 DEG C for 20 minutes to obtain a perovskite layer with a thickness of 500 nm.

[0014] Step 6: prepare an upper interface modification layer PEAI solution, and dynamically spin-coat the upper interface modification layer PEAI solution on the surface of the perovskite layer to obtain an upper interface modification layer with a thickness of 1-3 nm.

[0015] Step 7: sequentially evaporate C60 and BCP on the surface of the upper interface modification layer using an evaporation method to obtain an electron transport layer and a hole blocking layer.

[0016] Step 8: evaporate an electrode on the surface of the BCP using an evaporation method.

[0017] Preferably, the electrode is a silver electrode, a copper electrode or a gold electrode.

[0018] The application has the following beneficial effects:

[0019] Compared with the deposition of a traditional single self-assembled molecule, the mixing of the p-functional-group-containing benzoic acid and the self-assembled molecule can improve the coverage of the self-assembled molecule and the extraction efficiency of carriers, thereby finally improving the performance of the perovskite solar cell. ​BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 J-V graph of the perovskite solar cell prepared in Comparative Example 1;

[0021] Figure 2 Scanning electron microscope graph of the perovskite layer in Comparative Example 1;

[0022] Figure 3 J-V graph of the perovskite solar cell prepared in Example 1;

[0023] Figure 4 Scanning electron microscope graph of the perovskite layer in Example 1;

[0024] Figure 5 J-V graph of the perovskite solar cell prepared in Example 2;

[0025] Figure 6 Scanning electron microscope graph of the perovskite layer in Example 2. DETAILED DESCRIPTION

[0026] The present application proposes a perovskite solar cell based on co-doping of hole transport layer and a preparation method thereof. By using benzoic acid containing para-functional groups to co-dope single self-assembled molecules, a co-self-assembled molecule film is formed, the coverage of self-assembled molecules is improved, the clustering problem caused by amphiphilicity is solved, and thus the carrier extraction efficiency is further improved, and the performance of the perovskite solar cell is optimized. The present application is further explained and described below in combination with the drawings and comparative examples;

[0027] Comparative Example 1

[0028] This comparative example prepares a conventional trans perovskite solar cell as a control group for performance test, and the specific steps are as follows:

[0029] Step 1, prepare a self-assembled molecule MeO-2PACz solution with a concentration of 0.5 mg / ml.

[0030] Step 2, wash the glass substrate ITO with detergent, and then ultrasonically clean it in pure water for 20 minutes, followed by ultrasonic cleaning in ethanol solution for 20 minutes, and finally ultrasonic cleaning in isopropanol solution for 20 minutes. Put the cleaned glass substrate ITO into an 80℃ oven and dry for 5 minutes, cool it down, and then put it into a plasma treatment instrument for 10 minutes to improve the solution wettability.

[0031] Step 3, place the treated glass substrate ITO on a spin coater, set the spin coater speed to 3000 r / s, and the acceleration to 2000 r / s 2, time for 30s, the self-assembled molecule MeO-2PACz solution configured in step 1 is uniformly spin-coated on the ITO surface of the glass substrate. Then it is placed on a heating table at 100℃ for annealing for 10 minutes to obtain a self-assembled molecule layer with a thickness of 2nm.

[0032] Step 4, configure perovskite precursor solution, use disposable syringe and filter head for filtration.

[0033] Step 5, use double-step spin coating method to uniformly spin-coat the filtered perovskite precursor solution on the surface of the self-assembled molecule layer, set the spin coater speed of the first step to 1000r / s, acceleration to 1000r / s 2 , time for 10s, the speed of the second step to 3000r / s, acceleration to 3000r / s 2 , time for 30s. Drop 150μL of chlorobenzene solution at the last 10s of the second step spin coating to perform anti-solvent flushing. Then it is placed on a heating table at 100℃ for annealing for 20 minutes to obtain a perovskite layer with a thickness of 500nm.

[0034] Step 6, configure the upper interface modification layer PEAI solution, dynamically spin-coat it on the surface of the perovskite layer, set the spin coater speed to 3000r / s, acceleration to 3000r / s 2 , time for 30s, to obtain an upper interface modification layer with a thickness of 1nm.

[0035] Step 7, evaporate C60 with a thickness of 27nm and BCP with a thickness of 7nm on the surface of the upper interface modification layer in sequence to obtain an electron transport layer and a hole blocking layer.

[0036] Step 8, finally evaporate a silver electrode with a thickness of 100nm on the surface of the hole blocking layer BCP to obtain a conventional transverse perovskite solar cell.

[0037] Use a solar simulator to detect the efficiency of the prepared transverse perovskite solar cell, the J-V curve graph is shown in Figure 1 , the effective active area of the transverse perovskite solar cell is 4cm 2 , the efficiency is about 20.91%, and the open circuit voltage is about 1.13V. Use scanning electron microscope (SEM) to observe the surface morphology of the perovskite layer, as shown in Figure 2 , the average grain size of the perovskite layer of the transverse perovskite solar cell is 216nm.

[0038] Example 1

[0039] This example prepares a perovskite solar cell based on hole transport layer co-doping, the specific steps are as follows:

[0040] Step 1, configure the self-assembled molecule MeO-2PACz solution with a concentration of 0.5 mg / ml and the p-mercaptobenzoic acid solution with a concentration of 0.5 mg / ml, then mix the self-assembled molecule MeO-2PACz solution and the p-mercaptobenzoic acid solution according to the volume ratio of 8:2, and put them in a solution shaker to shake for one hour to make them mixed uniformly, to obtain the co-doped self-assembled molecule solution.

[0041] Step 2, after the glass substrate ITO is cleaned with detergent, it is put into pure water for ultrasonic cleaning for 20 minutes, then into ethanol solution for ultrasonic cleaning for 20 minutes, and finally into isopropanol solution for ultrasonic cleaning for 20 minutes. The cleaned glass substrate ITO is put into an 80°C oven for drying for 5 minutes, and after cooling, it is put into a plasma treatment instrument for 10 minutes.

[0042] Step 3, place the treated glass substrate ITO on a spin coater, set the spin coater speed to 3000 r / s, the acceleration to 2000 r / s 2 , and the time to 30 s, and uniformly spin coat the co-doped self-assembled molecule solution obtained in step 1 on the surface of the glass substrate ITO. Then place it on a 100°C heating table for annealing for 10 minutes to obtain a co-doped self-assembled molecule layer with a thickness of 2 nm.

[0043] Step 4, configure the perovskite precursor solution and filter it using a disposable needle tube and a filter head.

[0044] Step 5, use a two-step spin coating method to uniformly spin coat the filtered perovskite precursor solution on the surface of the self-assembled molecule layer, set the spin coater speed to 1000 r / s, the acceleration to 1000 r / s 2 , and the time to 10 s in the first step, and the speed to 3000 r / s, the acceleration to 3000 r / s 2 , and the time to 30 s in the second step. Drop 150 μL of chlorobenzene solution at the last 10 s of the second step to perform anti-solvent flushing. Then place it on a 100°C heating table for annealing for 20 minutes to obtain a perovskite layer with a thickness of 500 nm.

[0045] Step 6, configure the upper interface modification layer PEAI solution, and dynamically spin coat it on the surface of the perovskite layer, set the spin coater speed to 3000 r / s, the acceleration to 3000 r / s 2 , and the time to 30 s to obtain an upper interface modification layer with a thickness of 1 nm.

[0046] Step 7, evaporate C60 with a thickness of 27 nm and BCP with a thickness of 7 nm on the surface of the upper interface modification layer in sequence to obtain an electron transport layer and a hole blocking layer.

[0047] Step 8, finally, a silver electrode with a thickness of 100 nm is evaporated on the surface of the hole blocking layer BCP to obtain a conventional trans-perovskite solar cell.

[0048] The J-V curve of the perovskite solar cell based on the co-doped hole transport layer prepared in this example is shown in Figure 3 , the effective active area is 1 cm 2 , the efficiency is about 21.86%, and the open circuit voltage reaches 1.14V. The scanning electron microscope results are shown in Figure 4 , the average grain size of the perovskite layer is 268 nm.

[0049] Example 2

[0050] In this example, based on Example 1, a p-trifluorobenzoic acid solution with a concentration of 0.5 mg / ml is mixed with a self-assembled molecule MeO-2PACz solution in a volume ratio of 2:8 to obtain a co-doped self-assembled molecule solution.

[0051] The J-V curve of the perovskite solar cell based on the co-doped hole transport layer obtained is shown in Figure 5 , the effective active area is 4 cm 2 , the efficiency is about 22.75%, and the open circuit voltage reaches 1.15V. The scanning electron microscope results are shown in Figure 6 , the average grain size of the perovskite layer is 288 nm.

[0052] It can be seen that compared with the trans-perovskite solar cell prepared in Comparative Example 1, the open circuit voltage of the perovskite solar cell based on the co-doped hole transport layer prepared in Examples 1 and 2 is obviously improved, the photoelectric conversion efficiency is improved, and after the self-assembled molecule solution is doped with p-functional group-containing benzoic acid, the perovskite layer has better crystallization growth and the grain size is improved.

[0053] Example 3

[0054] In this example, based on Example 1, when the co-doped self-assembled molecule solution is spin-coated by the film applicator, the speed of the film applicator is set to 4000 r / s, the acceleration is 3000 r / s 2 , and the time is 30 s, to prepare a co-doped self-assembled molecule layer with a thickness of 5 nm.

[0055] Example 4

[0056] In this example, based on Example 1, a p-cyanobenzoic acid solution with a concentration of 0.5 mg / ml is mixed with a self-assembled molecule MeO-2PACz solution to prepare a co-doped self-assembled molecule layer with a thickness of 1 nm.

[0057] Example 5

[0058] This example is based on Example 4, with the addition of a reverse solvent rinse with a 150 μL volume of chlorobenzene solution dropped during the last 15 s of spin coating the perovskite precursor solution in the second step. The upper interface modification layer thickness was also modified to 3 nm.

Claims

1. A perovskite solar cell based on a hole transport layer co-doping, comprising, from bottom to top, an ITO substrate, a hole transport layer, a perovskite layer, an upper interface modification layer, an electron transport layer, a hole blocking layer, and an electrode, characterized in that: The hole transport layer is a self-assembled molecule MeO-2PACz doped with a benzoic acid molecule containing a para-functional group, wherein the mass ratio of the benzoic acid molecule containing a para-functional group to the self-assembled molecule MeO-2PACz is 2:8; The benzoic acid molecule containing a para-functional group is p-mercaptobenzoic acid, p-trifluorobenzoic acid or p-cyanobenzoic acid.

2. The hole transport layer co-doped perovskite solar cell according to claim 1, characterized in that: The thickness of the hole transport layer is 1-5 nm.

3. The hole transport layer co-doped perovskite solar cell according to claim 1, characterized in that: The upper interface modification layer is PEAI, the electron transport layer is C60, the hole blocking layer is BCP, and the electrode is one of silver, copper or gold.

4. The hole transport layer co-doped perovskite solar cell according to claim 1 or 3, characterized in that: The thickness of the perovskite layer is 500 nm, the thickness of the upper interface modification layer is 1-3 nm, the thickness of the electron transport layer and the hole blocking layer are 27 nm and 7 nm respectively, and the thickness of the electrode is 100 nm.

5. A method for preparing a perovskite solar cell based on a hole transport layer co-doping method, wherein a perovskite solar cell device is prepared by a solution spin coating method, which comprises, from bottom to top, an ITO substrate, a hole transport layer, a perovskite layer, an upper interface modification layer, an electron transport layer, a hole blocking layer, and an electrode, characterized in that: The hole transport layer is obtained by spin coating a co-doped self-assembled molecular solution on the surface of the ITO substrate; The co-doped self-assembly molecule solution is a mixture of a benzoic acid molecule solution containing a para-functional group and a self-assembly molecule solution in a volume ratio of 2:8, and the concentrations of the self-assembly molecule solution and the benzoic acid molecule solution containing a para-functional group are both 0.5 mg / ml; the benzoic acid molecule containing a para-functional group is p-mercaptobenzoic acid, p-trifluorobenzoic acid or p-cyanobenzoic acid.

6. The method for preparing a perovskite solar cell based on co-doping of a hole transport layer according to claim 5, characterized in that: The specific steps include: Step 1: preparing a self-assembly molecule solution and a benzoic acid molecule solution containing a para-functional group, and mixing them to obtain a co-doped self-assembly molecule solution; Step 2: Use pure water, ethanol, and isopropyl alcohol to clean the ITO glass substrate, and then put it into an oven to dry the surface liquid; Step 3: Use a coating machine to evenly spin-coat the co-doped self-assembled molecular solution on the ITO surface of the glass substrate. Set the coating machine speed to 3000~4000r / s and the acceleration to 2000~3000r / s. 2 , the time is 25~30s; then the spin-coated glass substrate ITO is heated at 100℃ for 10 minutes using a heating table to obtain a co-doped self-assembled molecular layer with a thickness of 1~5nm; Step 4: preparing a perovskite precursor solution and filtering it; Step 5: Use a double-step spin coating method to evenly spin-coat the filtered perovskite precursor solution on the surface of the co-doped self-assembled molecular layer, and then heat it on a heating table at 100°C for 20 minutes to obtain a perovskite layer with a thickness of 500 nm; Step 6: Prepare an upper interface modification layer PEAI solution and dynamically spin-coat it on the surface of the perovskite layer to obtain an upper interface modification layer with a thickness of 1 to 3 nm; Step 7: Using an evaporation method, C60 and BCP are sequentially evaporated on the surface of the upper interface modification layer to obtain an electron transport layer and a hole blocking layer; Step 8: Use the evaporation method to plate electrodes on the surface of BCP.

7. The method for preparing a perovskite solar cell based on co-doping of a hole transport layer according to claim 6, characterized in that: In step 5, set the first speed of the spin coater to 1000 r / s and the acceleration to 1000 r / s. 2 , time is 10s, second step speed is 3000r / s, acceleration is 3000r / s 2 , time is 30s.

8. The method for preparing a perovskite solar cell based on co-doping of a hole transport layer according to claim 6 or 7, characterized in that: In the last 10-15 seconds of the second spin coating step, chlorobenzene solution was added dropwise for anti-solvent washing.

9. The method for preparing a perovskite solar cell based on co-doping of a hole transport layer according to claim 8, characterized in that: The volume of the chlorobenzene solution was 150 μL.

Images