Trans-perovskite solar cell based on mixed electron transport layer and preparation method thereof

Abstract

The invention belongs to the technical field of solar cells, and relates to a trans-perovskite solar cell based on a solution method mixed electron transport layer and a preparation method of the trans-perovskite solar cell. The perovskite solar cell is composed of a transparent conductive oxide glass substrate, a hole transport layer, a perovskite light absorption layer, a passivation layer, an electron transport layer and a silver electrode layer in sequence. Materials used by an electron transport layer are generally fullerene and derivatives thereof, but the fullerene has the defects of poor light absorption capability, difficulty in purification, high production cost and the like, and the space for further improving the performance of the device is very small on the premise of good optimization of perovskite layer crystallization and interface engineering. The non-fullerene micromolecule Y6 is introduced into the electron transport layer, so that the cathode interface energy level can be effectively regulated and controlled, and the light absorption of the cell in a near-infrared region is improved. The trans-perovskite solar cell based on the PCBM: Y6 mixed electron transport layer has higher short-circuit current density and stability.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and particularly relates to a trans-structured perovskite solar cell based on a hybrid electron transport layer of fullerene derivatives / non-fullerene small molecules and its preparation method. Background Technology

[0002] Inverted perovskite solar cells have attracted increasing attention due to their good stability and low hysteresis. In recent years, their photoelectric conversion efficiency has rapidly increased to over 26%, making them a strong competitor in the photovoltaic field. However, fullerenes, the electron transport layer material commonly used in inverted perovskite solar cells, have poor crystallinity and are prone to aggregation, resulting in poor water and light stability of the cells.

[0003] Y6, a non-fullerene small molecule material based on dithiophene[3,2-b]-pyrrolobenzothiadiazole (TPBT), possesses advantages such as high mobility and energy level matching with perovskites. Furthermore, its narrow optical bandgap extends the photoresponse range to 940 nm, which is beneficial for increasing the light absorption of the battery and thus improving the short-circuit current density (J). SC Furthermore, the electron-rich functional groups in Y6, such as CSC, C=O, C≡N, and CF, can interact with Pb. 2+ Chemical complexation of empty orbitals or other electron traps on the perovskite surface in the Y6 electron transport layer helps reduce the trap state density and nonradiative recombination, enhances electron extraction, and suppresses ion migration, thereby improving the overall battery performance. Introducing Y6 into the electron transport layer to partially replace fullerene materials not only complements the advantages of fullerene electron transport layers but also improves the overall efficiency and stability of the battery. Summary of the Invention

[0004] The purpose of this invention is to prepare a hybrid electron transport layer by introducing the non-fullerene material Y6 into a traditional fullerene (PCBM) electron transport layer. The hybrid electron transport layer combines the excellent electron mobility of PCBM with the wide optical absorption range and multifunctional groups of Y6, which is beneficial to the overall efficiency and stability of the battery. The introduction of Y6 can broaden the light absorption range of the battery, thus improving the photocurrent. The electron-rich groups such as CSC, C=O, C≡N, and CF in the Y6 molecule can effectively passivate perovskite surface defects, reduce defect recombination at the cathode interface, enhance electron extraction, and inhibit ion migration, thereby improving the overall performance of the battery.

[0005] This invention provides an inverse perovskite solar cell based on a hybrid electron transport layer. The cell structure, from bottom to top, comprises: a free-conductive glass (FTO) substrate / hole transport layer / perovskite layer / passivation layer / electron transport layer / hole blocking layer / silver electrode layer. The electron transport layer material is a blend of PCBM and Y6 in a specific ratio.

[0006] To realize the above-mentioned perovskite solar cell based on a fullerene / non-fullerene electron transport layer, the present invention also provides a preparation method, the method comprising the following steps:

[0007] Step 1: Cleaning the FTO conductive glass substrate: The etched conductive glass substrate is ultrasonically cleaned for 15 minutes in sequence with neutral detergent, ultrapure water, ethanol, and ultrapure water. After cleaning, it is dried with nitrogen to obtain a clean FTO substrate.

[0008] Step 2: Spin-coating a hole transport layer based on a carbazole phosphate self-assembled monolayer onto the surface of an FTO substrate;

[0009] Step 3: A perovskite light-absorbing layer is obtained by spin-coating a perovskite precursor solution onto the hole transport layer and then annealing.

[0010] Step 4: Dissolve 4-methoxyphenylethyl ammonium iodide (MeO-PEAI) in a specific solvent and spin-coat it onto the perovskite light-absorbing layer to obtain a passivation layer;

[0011] Step 5: Dissolve the electronic material in chlorobenzene and spin-coat it onto the passivation layer to obtain the electron transport layer;

[0012] Step 6: Dissolve 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) in a specific solvent and spin-coat it onto the electron transport layer to obtain a hole blocking layer.

[0013] Step 7: Deposit silver electrodes on the surface of the hole blocking layer by thermal evaporation to obtain an inverse perovskite solar cell based on a hybrid electron transport layer.

[0014] In step 2, the carbazole phosphate molecule used in this invention is MeO-4PACz, the solvent is isopropanol, and the concentration is 0.3–1 mg / mL. When preparing the hole transport layer, the spin-coating speed is 3000–5000 rpm, the spin-coating time is 20–40 s, the annealing temperature is 90–110 °C, and the annealing time is 5–15 min.

[0015] In step 3, the concentration of the perovskite precursor is 1.4–1.6 mol / L, and the solvent is N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), with a volume ratio of DMF to DMSO of 9:1–4:1. During spin-coating of the perovskite precursor solution, the rotation speed in the first stage is 500–1500 rpm, and the spin-coating time is 5–10 seconds. In the second stage, the rotation speed is 3000–5000 rpm, and the spin-coating time is 20–40 seconds. 10–200 μL of chlorobenzene is added dropwise 10–20 seconds before the end of spin-coating. The annealing temperature is 90–110℃, and the annealing time is 30–60 min.

[0016] In step 4, the concentration of MeO-4PACz in the prepared passivation layer solution is 3-5 mg / mL, and the solvent is isopropanol (IPA); the spin coating speed is 3000-5000 rpm, the spin coating time is 25-35 seconds, the annealing temperature is 90-110℃, and the annealing time is 3-10 min.

[0017] In step 5, the total concentration of the electron transport layer solution is 15-25 mg / mL, the mass ratio of PCBM to Y6 is 10:0-8:2, the solvent is chlorobenzene, the spin coating speed is 1000-2000 rpm, the spin coating time is 25-35 s, the annealing temperature is 95-105℃, and the annealing time is 5-15 min.

[0018] In step 6, the concentration of BCP is 0.1–1 mg / mL, the solvent is isopropanol, the spin coating speed is 3500–4500 rpm, and the spin coating time is 25–35 s.

[0019] In step 7, the thickness of the silver electrode is 80–100 nm.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention relates to a perovskite solar cell with an inverse structure based on a fullerene / non-fullerene hybrid electron transport layer. Figure 1 Introducing the non-fullerene small molecule Y6 into a conventional fullerene electron transport layer results in a hybrid electron transport layer that combines the advantages of both electron transport materials, which is beneficial for improving the overall efficiency and long-term stability of the battery.

[0022] 2. The wide light absorption range of the non-fullerene material Y6 used in this invention can effectively improve the photocurrent of the battery. Its multifunctional groups can effectively passivate perovskite surface defects, which is beneficial for reducing defect recombination at the cathode interface and improving electron extraction and transport efficiency. When the PCBM:Y6 (mass ratio) is 9:1, the inverse perovskite solar cell device based on the hybrid electron transport layer has the highest efficiency. Figure 2 , 3 Compared to other batteries, it is characterized by a significant increase in short-circuit current density.

[0023] 3. The inverted perovskite solar cell based on a hybrid electron transport layer (PCBM:Y6 = 9:1, mass ratio) prepared in this invention exhibits excellent light stability. After continuous irradiation under standard sunlight for 600 s, its steady-state output efficiency at the maximum power point remains essentially unchanged. Figure 4 ). Attached Figure Description

[0024] Figure 1 This is a schematic diagram of an inverted perovskite solar cell device.

[0025] Figure 2 The JV characteristic curves are for the optimal device based on a fullerene / non-fullerene (9:1) hybrid electron transport layer.

[0026] Figure 3 The JV characteristic curves of the optimal device based on the fullerene electron transport layer are shown.

[0027] Figure 4 The steady-state output efficiency of an inverted perovskite solar cell based on a fullerene / non-fullerene (9:1) hybrid electron transport layer under standard sunlight at the maximum power point. Detailed Implementation

[0028] The method of the present invention will be further described in detail below with reference to specific embodiments. The following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0029] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0030] Example 1

[0031] A method for fabricating an inverted perovskite solar cell based on a hybrid electron transport layer, comprising:

[0032] 1. Cleaning the FTO conductive glass substrate: The etched conductive glass substrate is ultrasonically cleaned for 15 minutes in sequence with neutral detergent, ultrapure water, ethanol and ultrapure water. After cleaning, it is dried with nitrogen to obtain a clean FTO substrate.

[0033] 2. Preparation of hole transport layer: Carbazole phosphate molecule MeO-4PACz was dissolved in isopropanol at a concentration of 0.3-1 mg / mL and spin-coated onto FTO substrate. The spin-coating speed was 4000 rpm and the spin-coating time was 30 s. The annealing temperature was 100℃ and the annealing time was 10 min.

[0034] 3. Preparation of the perovskite active layer: 6.7 mg of methyl ammonium bromide (MABr), 8.8 mg of methyl ammonium chloride (MACl), 18.2 mg of cesium iodide (CsI), 196.1 mg of formamidine iodide (FAI), 22 mg of lead bromide (PbBr2), and 572 mg of lead iodide (PbI2) were weighed and dissolved in 0.865 ml of a mixed solvent of DMF:DMSO at a volume ratio of 4:1. The solution was stirred at 60 °C for 1 h to obtain a well-dissolved perovskite precursor solution. During spin coating of the perovskite precursor solution, the first stage was at a speed of 1000 rpm for 5 seconds, and the second stage was at a speed of 4000 rpm for 30 seconds. 15 seconds before the end of spin coating, the antisolvent (150 μL of chlorobenzene) was added dropwise, and then the solution was annealed at 100 °C for 60 min to obtain the perovskite active layer.

[0035] 4. Preparation of passivation layer: Weigh 4.5 mg of MeO-PEAI and dissolve it in 1 mL of isopropanol. Then spin-coat it onto the perovskite surface at 4000 rpm for 30 s. Then anneal at 100 °C for 5 min.

[0036] 5. Preparation of electron transport layer: PCBM and Y6 were dissolved in chlorobenzene at a mass ratio of 9:1 and a total concentration of 20 mg / mL. The solution was then spin-coated onto the perovskite surface at 1500 rpm and annealed at 100 °C for 10 min.

[0037] 6. Preparation of hole blocking layer: Prepare a 0.5 mg / mL BCP solution (solvent is isopropanol) and spin-coat it onto the PCBM surface at a speed of 4000 rpm.

[0038] 7. Fabrication of the metal electrode: A silver electrode was fabricated using vacuum evaporation, with a thickness of 80 nm. The electrode shape was determined by a photomask. This yielded a preferred inverse-structure perovskite solar cell based on a PCBM / Y6 hybrid electron transport layer.

[0039] The efficiency of the inverted perovskite solar cell prepared in this embodiment was tested under simulated standard sunlight (AM1.5G).

[0040] Test results are available Figure 2 .

[0041] Comparative Example 1

[0042] The method for preparing an inverse perovskite solar cell based on a hybrid electron transport layer according to Example 1 differs in that, in step 5, when preparing the electron transport layer, PCBM (non-fullerene small molecules) is dissolved in chlorobenzene at a concentration of 20 mg / mL, and then spin-coated onto the perovskite surface at a speed of 1500 rpm, and annealed at 100°C for 10 min.

[0043] The efficiency of the inverted perovskite solar cell prepared in this embodiment was tested under simulated standard sunlight (AM1.5G).

[0044] Test results are available Figure 3 .

[0045] Will Figure 2 , Figure 3 The comparison shows that when the PCBM:Y6 (mass ratio) is 9:1, the inverted perovskite solar cell device based on the hybrid electron transport layer has the highest efficiency. Compared with other cells, it mainly shows a significant increase in short-circuit current density, indicating that introducing an appropriate amount of non-fullerene small molecules into the traditional fullerene electron transport layer can effectively improve the photocurrent.

[0046] Depend on Figure 4 It can be seen that the inverted perovskite solar cell based on the hybrid electron transport layer (PCBM:Y6 = 9:1, mass ratio) prepared in this invention maintains a steady-state output efficiency at the maximum power point after continuous irradiation under standard sunlight for 600s, demonstrating excellent light stability.

Claims

1. A trans-perovsk solar cell based on a fullerene / non-fullerene small molecule hybrid electron transport layer, characterized in that... The perovskite solar cell structure comprises an FTO conductive substrate / hole transport layer / perovskite absorber layer / passivation layer / mixed electron transport layer / hole blocking layer / silver electrode layer, wherein the electron transport layer is a mixture of fullerene (PCBM) and non-fullerene small molecule (Y6) materials in a certain mass ratio. The fullerene in this invention: The planar heterojunction formed between the non-fullerene small molecule mixed electron transport layer and the perovskite active layer can broaden the overall light absorption range of the cell, passivate perovskite surface defects, and improve charge collection and transport at the cathode interface of the inverted perovskite solar cell.

2. A method for fabricating an inverted perovskite solar cell based on a fullerene / non-fullerene hybrid electron transport layer, characterized in that, Includes the following steps: Step 1: Clean the FTO conductive glass substrate; Step 2: Spin-coating a hole transport layer based on a carbazole phosphate self-assembled monolayer onto the surface of an FTO substrate; Step 3: Prepare a perovskite light-absorbing layer on the hole transport layer by spin coating; Step 4: Spin-coat 4-methoxyphenylethyl ammonium iodide (MeO-PEAI) onto the perovskite light-absorbing layer to prepare a passivation layer; Step 5: Dissolve the electron transport material in chlorobenzene and spin-coat it onto the passivation layer to obtain the electron transport layer; Step 6: Dissolve 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) in a specific solvent and spin-coat it onto the electron transport layer to obtain a hole blocking layer. Step 7: Deposit silver electrodes on the surface of the hole blocking layer by thermal evaporation to obtain an inverse perovskite solar cell based on a hybrid electron transport layer.

3. The method for fabricating an inverted perovskite solar cell based on a fullerene / non-fullerene hybrid electron transport layer according to claim 2, characterized in that, In step 2, the hole transport layer carbazole phosphate molecule MeO-4PACz self-assembles a monolayer. MeO-4PACz is dissolved in isopropanol (IPA) at a concentration of 0.3-1 mg / mL and spin-coated onto the FTO substrate. The spin-coating speed is 3000-5000 rpm and the spin-coating time is 20-40 s. The annealing temperature is 90-110℃ and the annealing time is 5-15 min.

4. The method for fabricating an inverted perovskite solar cell based on a fullerene / non-fullerene hybrid electron transport layer according to claim 2, characterized in that, In step 3, the specific preparation method of the perovskite precursor solution is as follows: 6.7 mg of methyl ammonium bromide (MABr), 8.8 mg of methyl ammonium chloride (MACl), 18.2 mg of cesium iodide (CsI), 196.1 mg of formamidinium iodide (FAI), 22 mg of lead bromide (PbBr2), and 572 mg of lead iodide (PbI2) are weighed sequentially. The concentration of the perovskite precursor is 1.4–1.6 mol / L, and the organic solvent is N,N-dimethylformamide (DMF) and dimethylformamide (DMF). The perovskite film is spin-coated in two stages: the first stage has a spin speed of 500-1500 rpm and a spin-coating time of 5-10 seconds; the second stage has a spin speed of 3000-5000 rpm and a spin-coating time of 20-40 seconds. 10-20 seconds before the end of the spin-coating, an anti-solvent (100-200 μL chlorobenzene) is added, and then the film is annealed at 90-110℃ for 30-60 min to obtain the perovskite active layer.

5. The method for fabricating an inverted perovskite solar cell based on a fullerene / non-fullerene hybrid electron transport layer according to claim 2, characterized in that, In step 4, the concentration of MeO-PEAI in the prepared passivation layer solution is 3-5 mg / mL, the solvent is IPA, the spin coating speed is 3000-5000 rpm, the spin coating time is 25-35 s, the annealing temperature is 90-110℃, and the annealing time is 3-10 min.

6. The method for fabricating an inverted perovskite solar cell based on a fullerene / non-fullerene hybrid electron transport layer according to claim 2, characterized in that, In step 5, PCBM and Y6 are dissolved in chlorobenzene at a mass ratio of 10:0 to 8:2 and a total concentration of 15 to 25 mg / mL. The spin coating speed is 1000 to 2000 rpm and the spin coating time is 25 to 35 s. The annealing temperature is 95 to 105℃ and the annealing time is 5 to 15 min.

7. The method for fabricating an inverted perovskite solar cell based on a fullerene / non-fullerene hybrid electron transport layer according to claim 2, characterized in that, In step 6, the concentration of the hole blocking layer BCP solution is 0.1–1 mg / mL (solvent is isopropanol), the spin coating speed is 3500–4500 rpm, and the spin coating time is 25–35 s.

8. The method for fabricating an inverted perovskite solar cell based on a fullerene / non-fullerene hybrid electron transport layer according to claim 2, characterized in that, In step 7, a silver electrode is prepared using vacuum evaporation, with a thickness of 80–100 nm. The electrode shape is determined by a photomask. This yields a trans-perovskite solar cell based on a fullerene / non-fullerene hybrid electron transport layer.

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