Perovskite solar cell electron transport layer based on cationic polyelectrolyte additive and preparation method and application thereof
By adding cationic polyelectrolyte additives to PCBM electron transport materials, the problems of poor solubility and uneven film formation of PCBM were solved, enabling the preparation of a high-efficiency electron transport layer for perovskite solar cells, improving device efficiency and reducing manufacturing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DAZHENG (XIAMEN) MICRONANO TECHNOLOGY CO LTD
- Filing Date
- 2026-02-04
- Publication Date
- 2026-05-05
AI Technical Summary
In existing perovskite solar cells, PCBM electron transport materials have poor solubility, poor film quality, uneven film thickness, and difficulty in adjusting the material interface energy level, which affects device efficiency.
Cationic polyelectrolyte additives, such as polyvinylpyridine, polyvinyl alcohol, and polyethyleneimine, are added to the PCBM electron transport material solution. After stirring, the solution is coated to form an electron transport layer. The polyelectrolyte molecules migrate to the interface during the drying process to perform in-situ protonation, thereby regulating the energy level and passivating defects.
It improves the morphology and processability of PCBM films, reduces deep carrier traps, increases open-circuit voltage, enhances electron transport efficiency, and reduces process complexity and manufacturing costs, providing a new preparation route for large-area solar cells.
Smart Images
Figure CN121985704A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of perovskite solar cell technology, specifically to an electron transport layer for perovskite solar cells based on cationic polyelectrolyte additives, its preparation method, and its application. Technical Background
[0002] With the advancement of science and technology, human beings have an increasing demand for energy. Solar energy is renewable, clean and environmentally friendly. Perovskite solar cells have advantages such as simple preparation and low-temperature processing. To date, the certified efficiency of perovskite solar cells has exceeded 25%. PCBM ([6,6]-phenyl-C61-butyrate methyl ester) has excellent electron mobility and is an irreplaceable electron transport material in the current highly promising inverted (pin) structure perovskite solar cells. However, its poor solubility makes it very difficult to prepare high-quality, fully covered perovskite films based on PCBM.
[0003] Furthermore, traditional single-component PCBMs exhibit poor film quality, displaying inhomogeneity during solvent drying, resulting in inconsistent film thickness and porosity. Moreover, during the drying process, traditional single-component PCBMs cannot fine-tune the interfaces between different materials using their own energy levels. Summary of the Invention
[0004] To overcome the above-mentioned defects, this invention provides an electron transport layer for perovskite solar cells based on cationic polyelectrolyte additives, its preparation method, and its application. This method can passivate perovskite defects, improve device efficiency, and reduce process complexity and manufacturing costs, providing a new approach for the preparation of large-area solar cells.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] A method for preparing an electron transport layer for a perovskite solar cell based on a cationic polyelectrolyte additive includes the following steps: adding a cationic polyelectrolyte additive to a PCBM electron transport material solution and stirring to obtain an electron transport material solution containing the cationic polyelectrolyte additive; coating the electron transport material solution containing the cationic polyelectrolyte additive onto a perovskite light-absorbing layer to prepare an electron transport layer for a perovskite solar cell based on the cationic polyelectrolyte additive; wherein the cationic polyelectrolyte additive is one of polyvinylpyridine, polyvinyl alcohol, polyethyleneimine, polyesteramide, polyacrylamide, and polyvinylamide.
[0007] Furthermore, the mass concentration of the PCBM electron transport material solution is 15-25 mg / ml.
[0008] Furthermore, the solvent of the PCBM electron transport material solution is chlorobenzene.
[0009] Furthermore, the concentration of the cationic polyelectrolyte additive in the PCBM electron transport material solution is 0.01-0.5 wt%.
[0010] Furthermore, the concentration of the cationic polyelectrolyte additive in the PCBM electron transport material solution is 0.05-0.15 wt%.
[0011] Furthermore, the stirring time is 20-40 minutes.
[0012] Furthermore, the coating methods include spin coating, scraping coating, slot coating, or spraying.
[0013] Furthermore, the cationic polyelectrolyte additive is added to the electron transport layer by solution mixing.
[0014] The present invention also provides an electron transport layer for a perovskite solar cell based on a cationic polyelectrolyte additive, which is prepared by the above preparation method, and the electron transport layer material includes a fullerene derivative of PCBM.
[0015] Furthermore, the thickness of the electron transport layer is 20-40 nm.
[0016] Furthermore, this invention also provides the application of a perovskite solar cell electron transport layer based on cationic polyelectrolyte additives in the fabrication of solar cells.
[0017] Beneficial effects
[0018] The cationic polyelectrolyte solution, upon ionization, becomes a cationic polymer, improving the solution's processability and film morphology without affecting the PCBM itself. During the PCBM film coating and drying process, the cationic polyelectrolyte molecules migrate to the top and bottom interfaces. The bottom polyelectrolyte undergoes in-situ protonation at the perovskite interface, significantly reducing deep carrier trapping. The top polyelectrolyte thin layer can improve the potential barrier between the PCBM electron transport layer and the top electrode layer. The molecular orbital energy levels of the polyelectrolyte material can match those of the PCBM. By slightly downgrading the PCBM's energy levels through energy level hybridization, the open-circuit voltage of the device can be increased without sacrificing electron transport efficiency. Due to these characteristics, perovskite defects can be passivated, device efficiency improved, and process complexity and manufacturing costs reduced, providing a new approach for fabricating large-area solar cells.
[0019] Furthermore, regarding the issue of particle aggregation after excessive ultrasounding and prolonged use, the introduction of trace polyelectrolyte additives allows polymer chains to interweave between PCBM molecules, limiting their migration and aggregation, thereby controlling the size of individual PCBM molecules within the ideal range of below 20 nm. In addition, the introduction of trace polyelectrolyte additives can improve the viscosity and wettability of the solution during film formation, making the PCBM film formation more continuous and thus accelerating the electron transport rate in the electron transport layer.
[0020] In addition to traditional physical adsorption and metal chelation modes, the interaction between cationic polyelectrolytes and perovskites is an in-situ protonation process. The moderate density of amine branches can maximize the passivation effect. The one-step preparation of cationic polyelectrolytes by dissolving them in PCBM can not only produce high-quality PCBM films and significantly reduce deep carrier traps, but also help reduce the complexity of the process and manufacturing costs, providing a new approach for the preparation of large-area solar cells. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the perovskite solar cell structure in this invention;
[0022] Figure 2 The JV (current density-voltage) characteristic curves of the perovskite solar cells prepared in Examples 1-3 and Comparative Example 1 are shown.
[0023] Figure 3 The JV (current density-voltage) characteristic curves of the perovskite solar cells prepared in Examples 4, 5 and Example 1 are shown. Detailed Implementation
[0024] The following description, in conjunction with the embodiments and accompanying drawings, provides a further explanation. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.
[0025] Example 1
[0026] Preparation of flexible ITO transparent substrates
[0027] After cutting, etching and rinsing, the flexible ITO transparent substrate was ultrasonically cleaned with deionized water, ethanol and isopropanol for 15 minutes in sequence, and then dried at 120°C for later use. Before spin coating, it was treated with UV ozone for 30 minutes.
[0028] Preparation of hole transport layer
[0029] Dissolve 15 mg of nickel oxide in 1 ml of water, shake well, and filter to obtain a hole transport layer material precursor solution. Use a one-step spin coating method to drop the solution onto the above flexible ITO, anneal at 3000 rpm for 30 s and 120 °C for 15 min to obtain a hole transport layer with a thickness of 15 nm.
[0030] Preparation of perovskite layers
[0031] 1.05 M PbI₂, 0.45 M FAI, 0.6 M CsI, 0.45 M PbBr₂, and 0.45 M FABr were added to 1 ml of a mixed solution of DMF:DMSO = 4:1 / v:v, stirred overnight, and filtered to obtain a perovskite precursor solution. The filtered perovskite precursor solution was spin-coated onto the hole transport layer in a one-step process: 1000 rpm for 10 s + 6000 rpm for 30 s. At the 5-second countdown from 6000 rpm, 200 μl of chlorobenzene was added dropwise, followed by annealing at 100 °C for 30 min to obtain a perovskite layer with a thickness of approximately 600 nm.
[0032] Fabrication of electron transport layer
[0033] A PCBM solution containing polymer additives was prepared by dissolving 20 mg of PCBM in 1 ml of chlorobenzene and stirring overnight. Before use, a trace amount of PVA was added to the PCBM solution to prepare a PCBM-PVA solution with a concentration of 0.05 wt% PVA. The mixture was stirred for 30 min. After the perovskite layer cooled to room temperature, the PCBM solution was spin-coated onto the surface of the perovskite layer and film was formed at 2000 rpm for 30 s to obtain a PCBM layer with a thickness of approximately 30 nm.
[0034] Preparation of electrode layer
[0035] A 100nm thick silver electrode layer was deposited on the surface of the electron transport layer using a vacuum deposition method and a photomask.
[0036] Example 2
[0037] In the specific operation process, except that the additive in the electron transport layer is polyethyleneimine (PEI), everything else is the same as in Example 1.
[0038] Example 3
[0039] In the specific operation process, except that the additive in the electron transport layer is polyacrylamide (PAM), everything else is the same as in Example 1.
[0040] Example 4
[0041] In the specific operation process, except that the concentration of polyvinyl alcohol (PVA) in the electron transport layer was adjusted to 0.1 wt%, the rest was the same as in Example 1.
[0042] Example 5
[0043] In the specific operation process, except that the concentration of polyvinyl alcohol (PVA) in the electron transport layer is adjusted to 0.15wt%, the rest is the same as in Example 1.
[0044] Comparative Example 1:
[0045] <Preparation of Flexible ITO Transparent Substrates>
[0046] After cutting, etching and rinsing, the flexible ITO transparent substrate was ultrasonically cleaned with deionized water, ethanol and isopropanol for 15 minutes in sequence, and then dried at 120°C for later use. Before spin coating, it was treated with UV ozone for 30 minutes.
[0047] <Preparation of Hole Transport Layer>
[0048] Dissolve 15 mg of nickel oxide in 1 ml of water, shake well, and filter to obtain a hole transport layer material precursor solution. Use a one-step spin coating method to drop the solution onto the above flexible ITO, anneal at 3000 rpm for 30 s and 120 °C for 15 min to obtain a hole transport layer with a thickness of 15 nm.
[0049] <Preparation of Perovskite Layer>
[0050] 1.05 M PbI₂, 0.45 M FAI, 0.6 M CsI, 0.45 M PbBr₂, and 0.45 M FABr were added to 1 ml of a mixed solution of DMF:DMSO = 4:1 / v:v, stirred overnight, and filtered to obtain a perovskite precursor solution. The filtered perovskite precursor solution was spin-coated onto the hole transport layer in a one-step process: 1000 rpm for 10 s + 6000 rpm for 30 s. At the 5-second countdown from 6000 rpm, 200 μl of chlorobenzene was added dropwise, followed by annealing at 100 °C for 30 min to obtain a perovskite layer with a thickness of approximately 600 nm.
[0051] <Preparation of Electron Transport Layer>
[0052] 20 mg of PCBM was dissolved in 1 ml of chlorobenzene. After the perovskite layer cooled to room temperature, the PCBM solution was spin-coated onto the surface of the perovskite layer and formed into a film at 2000 rpm for 30 s to obtain a PCBM layer with a thickness of about 30 nm.
[0053] <Preparation of Electrode Layer>
[0054] A 100nm thick silver electrode layer was deposited on the surface of the electron transport layer using a vacuum deposition method and a photomask.
[0055] Table 1
[0056] Table 1 shows the specific test results of the perovskite solar cells prepared in Examples 1-3 and Comparative Example 1.
[0057] Examples 1-3 show different cationic polyelectrolyte materials. When added to PCBM at the same concentration and used to prepare perovskite solar cells, the efficiency tests all showed improvements in open-circuit voltage, fill factor, and photoelectric conversion efficiency. The increase in open-circuit voltage indicates that the additive plays a role in interface regulation between perovskite and PCBM, resulting in a better match between interlayer energy levels. The increase in fill factor indicates an improvement in the PCBM film surface state, which is more conducive to electron transport and migration.
[0058] Table 2
[0059] Table 2 shows the specific test results of the perovskite solar cells prepared in Examples 1 and 4-5.
[0060] Examples 1 and 4-5 compare different concentrations of the additive polyvinyl alcohol (PVA). Within this concentration range, the efficiency increases with the increase of the additive concentration, indicating that the interface regulation and transport capabilities of the PVA additive are also enhanced, and no negative effects are produced. It has a wide range of applicable concentrations and is suitable for various perovskite materials and device structures, thus having universality.
Claims
1. A method for preparing an electron transport layer for a perovskite solar cell based on a cationic polyelectrolyte additive, characterized in that, The preparation steps include: adding a cationic polyelectrolyte additive to a PCBM electron transport material solution and stirring to obtain an electron transport material solution containing the cationic polyelectrolyte additive; coating the electron transport material solution containing the cationic polyelectrolyte additive onto a perovskite light-absorbing layer to prepare an electron transport layer for a perovskite solar cell based on the cationic polyelectrolyte additive; wherein the cationic polyelectrolyte additive is one of polyvinylpyridine, polyvinyl alcohol, polyethyleneimine, polyesteramide, polyacrylamide, and polyvinylamide.
2. The method for preparing the electron transport layer of a perovskite solar cell based on a cationic polyelectrolyte additive according to claim 1, characterized in that, The mass concentration of the PCBM electron transport material solution is 15-25 mg / ml.
3. The method for preparing the electron transport layer of a perovskite solar cell based on a cationic polyelectrolyte additive according to claim 1, characterized in that, The solvent for the PCBM electron transport material solution is chlorobenzene.
4. The method for preparing the electron transport layer of a perovskite solar cell based on a cationic polyelectrolyte additive according to claim 1, characterized in that, The concentration of the cationic polyelectrolyte additive in the PCBM electron transport material solution is 0.01-0.5 wt%.
5. The method for preparing the electron transport layer of a perovskite solar cell based on a cationic polyelectrolyte additive according to claim 1, characterized in that, Stirring time is 20-40 minutes.
6. The method for preparing the electron transport layer of a perovskite solar cell based on a cationic polyelectrolyte additive according to claim 1, characterized in that, The coating methods include spin coating, scraping coating, slot coating, or spraying.
7. The method for preparing the electron transport layer of a perovskite solar cell based on a cationic polyelectrolyte additive according to claim 1, characterized in that, The cationic polyelectrolyte additive is added to the electron transport layer by solution mixing.
8. An electron transport layer for a perovskite solar cell based on a cationic polyelectrolyte additive, characterized in that, Prepared by the preparation method according to any one of claims 1-7, the electron transport layer material includes a fullerene derivative of PCBM.
9. The electron transport layer of a perovskite solar cell based on a cationic polyelectrolyte additive according to claim 7, characterized in that, The thickness of the electron transport layer is 20-40 nm.
10. The application of the perovskite solar cell electron transport layer based on cationic polyelectrolyte additives as described in claim 8 or 9 in the fabrication of solar cells.