An ultra-flexible semi-transparent organic solar cell and a preparation method thereof

Abstract

The present application relates to the technical field of solar cells, in particular to a super-flexible semi-transparent organic solar cell and a preparation method thereof; the super-flexible semi-transparent organic solar cell comprises, from bottom to top, a flexible PDMS substrate, a transparent anode, a hole transport layer, an active layer, an electron transport layer and a semi-transparent back electrode; wherein the bottom of the flexible PDMS substrate is formed with a micron-sized inverted pyramid structure, the material of the transparent anode comprises a polyhydroxy compound and PEDOT:PSS (PH1000), and the material of the active layer comprises PBDB-T-2F, Y6 and C6. The solar cell provided by the present application has high light capture rate, high light transmittance and good mechanical bendability, and can meet the use requirements of some special three-dimensional curved surface application scenarios.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more specifically, to an ultra-flexible semi-transparent organic solar cell and its preparation method. Background Technology

[0002] Organic solar cells, due to their lightweight, low cost, flexibility, and semi-transparency, have attracted widespread attention for their potential applications in future multifunctional self-powered greenhouses and building-integrated photovoltaics, becoming a hot topic of scientific research and a key focus of industrial development in various countries.

[0003] Traditional semi-transparent flexible organic solar cells are generally based on ITO plastic substrates. However, ITO has problems such as mechanical brittleness, poor light transmittance and high light reflectance (low light capture rate) on plastic substrates. It cannot simultaneously ensure that flexible semi-transparent organic solar cells have high light capture rate, low light transmittance and good mechanical flexibility. Therefore, it cannot meet the usage requirements of some special three-dimensional curved surface applications (such as self-powered greenhouse roofs). Summary of the Invention

[0004] The technical problem solved by this invention is that existing semi-transparent flexible organic solar cells cannot simultaneously possess high light capture rate, high light transmittance, and good mechanical flexibility, thus failing to meet the usage requirements of some special three-dimensional curved surface application scenarios.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] An ultra-flexible semi-transparent organic solar cell comprises, from bottom to top, a flexible PDMS substrate, a transparent anode, a hole transport layer, an active layer, an electron transport layer, and a semi-transparent back electrode; wherein, the bottom of the flexible PDMS substrate has a micron-sized inverted pyramid structure, the transparent anode is made of a polyhydroxy compound and PEDOT:PSS (PH1000), and the active layer is made of PBDB-T-2F, Y6, and C6.

[0007] Optionally, the inverted pyramid structure is integrally formed with the flexible PDMS substrate.

[0008] The present invention also provides a method for preparing the ultra-flexible semi-transparent organic solar cell as described above, comprising:

[0009] Step S1: After mixing polydimethylsiloxane and crosslinking agent evenly, pour the mixture into a mold, dry it, and peel off the mold to obtain a flexible PDMS substrate with an inverted pyramid structure.

[0010] Step S2: Spin-coat the anode solution onto the flexible PDMS substrate, anneal it, and perform or not perform acidification treatment to obtain a transparent anode; wherein, the anode solution includes a polyhydroxy compound and PEDOT:PSS (PH1000);

[0011] Step S3: Prepare a hole transport layer on the anode;

[0012] Step S4: Prepare an active layer on the hole transport layer, wherein the active layer is made of PBDB-T-2F, Y6 and C6.

[0013] Step S5: Prepare an electron transport layer on the active layer;

[0014] Step S6: Prepare a semi-transparent back electrode on the electron transport layer to obtain an ultra-flexible semi-transparent organic solar cell.

[0015] Optionally, in step S2, the polyhydroxy compound includes one of sorbitol, ethylene glycol, xylitol, and hexanediol.

[0016] Optionally, in step S2, the mass fraction of the polyhydroxy compound in the anode solution is 3-8%.

[0017] Optionally, in step S2, after annealing, acidification is performed, which includes immersion in an acid solution.

[0018] Optionally, in step S2, the annealing temperature is 70-90℃ and the time is 15-25min.

[0019] Optionally, in step S3, the material of the hole transport layer includes PEDOT:PSS(4083).

[0020] Optionally, in step S4, the mass ratio of PBDB-T-2F, Y6, and C6 is 1:1.15:0.15.

[0021] Optionally, in step S5, the material of the electron transport layer includes PDINO.

[0022] Compared with existing technologies, this invention replaces the traditional glass substrate with a flexible PDMS substrate and sets an inverted pyramid structure at the bottom of the flexible PDMS substrate. The bottom of the flexible PDMS substrate serves as the light-facing surface. When light shines on this surface, the inverted pyramid micro / nano structure scatters the incident light forward, reducing reflection in the incident direction, increasing the light path inside the battery, and improving the light capture rate of the active layer. In this invention, the transparent anode material is PEDOT:PSS (PH1000) doped with polyhydroxy compounds. The polyhydroxy compound doped PEDOT:PSS (PH1000) forms hydrogen bonds and van der Waals bonds with the flexible PDMS substrate, significantly improving the adhesion of the transparent anode to the flexible PDMS substrate. Moreover, the polyhydroxy compound doped PEDOT:PSS (PH1000) has high toughness, making the transparent anode less prone to cracking and detachment under mechanical deformation. In addition, in this invention, the active layer material uses a non-fullerene acceptor with a strong response in the near-infrared region, which allows the semi-transparent battery to absorb light in the non-visible light region, thereby allowing more visible light to pass through and improving the battery's high light transmittance. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the ultra-flexible semi-transparent organic solar cell in an embodiment of the present invention;

[0024] Figure 2 This is a schematic flowchart of the preparation method of the ultra-flexible semi-transparent organic solar cell in an embodiment of the present invention;

[0025] Figure 3 A schematic diagram illustrating the process of preparing a flexible PDMS substrate with an inverted pyramid structure in an embodiment of the present invention;

[0026] Figure 4 The JV curve of the ultra-flexible semi-transparent organic solar cell prepared in Example 1 is shown.

[0027] Figure 5 The graph shows the transmittance of the ultra-flexible semi-transparent organic solar cell prepared in Example 1 versus the wavelength of visible light.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Flexible PDMS substrate, 2. Transparent anode, 3. Hole transport layer, 4. Active layer, 5. Electron transport layer, 6. Semi-transparent back electrode. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] It should be noted that, unless otherwise specified, the features in the embodiments of this invention can be combined with each other. The terms "comprising," "including," "containing," and "having" are non-limiting, meaning that other steps and other components that do not affect the results can be added. The above terms cover the terms "composed of" and "substantially composed of." Unless otherwise specified, the materials, equipment, and reagents are commercially available.

[0032] like Figure 1 As shown, this embodiment of the invention provides an ultra-flexible semi-transparent organic solar cell comprising, from bottom to top, a flexible PDMS substrate 1, a transparent anode 2, a hole transport layer 3, an active layer 4, an electron transport layer 5, and a semi-transparent back electrode 6; wherein, the bottom of the flexible PDMS substrate 1 has a micron-sized inverted pyramid structure, the material of the transparent anode 2 includes a polyhydroxy compound and PEDOT:PSS (PH1000), and the material of the active layer 4 includes PBDB-T-2F, Y6, and C6; wherein, PBDB-T-2F is used as an electron donor material, and Y6 and C6 are used as electron acceptor materials.

[0033] Compared with existing technologies, this invention replaces the traditional glass substrate with a flexible PDMS substrate 1, and sets an inverted pyramid structure at the bottom of the flexible PDMS substrate 1. The bottom of the flexible PDMS substrate 1 serves as the light-facing surface. When light shines on this surface, the inverted pyramid micro / nano structure scatters the incident light forward, reducing reflection in the incident direction, increasing the light path inside the battery, and improving the light capture rate of the active layer 4. In this invention, the transparent anode 2 is made of polyhydroxy compound-doped PEDOT:PSS (PH1000). The polyhydroxy compound-doped PEDOT:PSS (PH1000) forms hydrogen bonds and van der Waals bonds with the flexible PDMS substrate 1, significantly improving the adhesion of the transparent anode 2 to the flexible PDMS substrate 1. Moreover, the polyhydroxy compound-doped PEDOT:PSS (PH1000) has high toughness, making the transparent anode 2 less prone to cracking and detachment under mechanical deformation. In addition, in this invention, the active layer 4 material uses a non-fullerene acceptor with a strong response in the near-infrared region, which allows the semi-transparent battery to absorb light in the non-visible light region, thereby allowing more visible light to pass through and improving the high light transmittance of the battery.

[0034] In some embodiments of the present invention, the inverted pyramid structure is integrally formed with the flexible PDMS substrate 1. Compared with physical bonding and other bonding methods, since the inverted pyramid structure is integrally formed with the PDMS substrate 1, it is not easy for the inverted pyramid structure to separate from the flexible PDMS substrate 1 during mechanical deformation, thus resulting in better battery stability.

[0035] like Figure 2As shown, the present invention also provides a method for preparing the ultra-flexible semi-transparent organic solar cell as described above, comprising:

[0036] Step S1: After mixing polydimethylsiloxane and crosslinking agent evenly, pour the mixture into a mold, dry it, and peel off the mold to obtain a flexible PDMS substrate 1 with an inverted pyramid structure; the mold is used to prepare the flexible PDMS substrate 1 with an inverted pyramid structure.

[0037] Step S2: Spin-coat the anode solution onto the flexible PDMS substrate 1, anneal it, and perform or not perform acidification treatment to obtain a transparent anode 2; wherein, the anode solution includes a polyhydroxy compound and PEDOT:PSS (PH1000);

[0038] Step S3: Prepare a hole transport layer 3 on the transparent anode 2;

[0039] Step S4: Prepare an active layer 4 on the hole transport layer 3. The active layer 4 is made of materials including PBDB-T-2F, Y6 and C6.

[0040] Step S5: Prepare an electron transport layer 5 on the active layer 4;

[0041] Step S6: A semi-transparent back electrode 6 is fabricated on the electron transport layer 5 to obtain an ultra-flexible semi-transparent organic solar cell.

[0042] In some embodiments of the present invention, exemplarily, such as Figure 3 As shown, the specific process of step S1 is as follows: Polydimethylsiloxane (PDMS) and crosslinking agent (vinyltrimethoxysilane) are mixed evenly at a mass ratio of 10:1, poured onto a silicon template, and cured at 70-90℃ for 1-3 hours. The resulting flexible PDMS substrate 1 with an inverted pyramid structure is then peeled off from the silicon template. It can be seen from the preparation process that the inverted pyramid structure and the flexible PDMS substrate 1 are integrally formed. Figure 3 As shown, the silicon template substrate has a pyramid structure.

[0043] In some embodiments of the present invention, optionally, the flexible PDMS substrate 1 is subjected to ultraviolet ozone pretreatment before step S2. Specifically, the flexible PDMS substrate 1 is placed in an ultraviolet ozone (UVO) cleaner for ultraviolet ozone pretreatment for 35 minutes. Ultraviolet ozone pretreatment can effectively clean the surface of the flexible PDMS substrate 1, and also improve its surface wettability, thereby improving the interface quality between the flexible PDMS substrate 1 and the transparent anode 2, reducing contact resistance and interface reflection, and improving the carrier collection efficiency.

[0044] In some embodiments of the present invention, in step S2, the polyhydroxy compound includes one of sorbitol, ethylene glycol, xylitol, and hexanediol; preferably, the polyhydroxy compound is sorbitol, and the mass fraction of the polyhydroxy compound in the anode solution is 3-8%.

[0045] In some embodiments of the present invention, in step S2, after annealing, an acidification treatment is performed, which includes immersion in an acid solution. For example, immersion in methanesulfonic acid or formic acid for 5-15 minutes. Acid treatment also induces PEDOT recrystallization and alignment, increasing electronic hopping between PEDOT chains, ultimately resulting in a high conductivity >2000 S cm⁻¹. -1 2. Transparent anode.

[0046] In some embodiments of the present invention, in step S2, the spin coating speed is 1000-3000 rpm and the time is 20-40 s, the annealing temperature is 70-90℃ and the time is 15-25 min; the thickness of the finally obtained transparent anode 2 is 50-90 nm.

[0047] In some embodiments of the present invention, in step S3, the material of the hole transport layer 3 includes PEDOT:PSS (4083). Exemplarily, the method for preparing the hole transport layer 3 includes: spin-coating a hole transport layer solution onto the transparent anode 2, and annealing at 70-90°C for 15-25 min to obtain a hole transport layer 3 with a thickness of 20-60 nm; wherein the hole transport layer solution includes PEDOT:PSS (4083), the spin-coating speed is 3000-5000 rpm, and the time is 20-40 s.

[0048] In some embodiments of the present invention, in step S4, the preparation method of the active layer 4 includes: spin-coating an active layer solution onto the hole transport layer 3, annealing at 80-120°C for 5-15 min, and vacuum treatment to obtain an active layer 4 with a thickness of 80-200 nm; wherein the active layer solution is prepared by dissolving PBDB-T-2F, Y6, and C6 in chloroform, and the mass ratio of PBDB-T-2F, Y6, and C6 in the active layer solution is 1:1.15:0.15; the concentration of the solute in the active layer solution is 13-15 mg / ml, the spin-coating speed is 3000-5000 rpm, and the time is 20-40 s. The vacuum degree after vacuum treatment is 10. –4 Pa, the holding time is 2-30 min.

[0049] In some embodiments of the present invention, in step S5, the method for preparing the electron transport layer 5 includes: spin-coating an electron transport layer solution onto the active layer 4 to obtain an electron transport layer 5 with a thickness of 10-30 nm; wherein the electron transport layer solution is prepared by dissolving PDINO in anhydrous methanol, with a concentration of 1-1.5 mg / ml, and the spin-coating speed is 3000-4000 rpm for 20-40 s.

[0050] In some embodiments of the present invention, in step S6, the method for preparing the semi-transparent back electrode 6 includes: depositing a semi-transparent back electrode 6 of Ag material onto the electron transport layer 5 using a vacuum evaporation process; wherein the vacuum degree of the vacuum evaporation is 10. -4 Pa.

[0051] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0052] Example 1

[0053] 1.1 Preparation of a flexible PDMS substrate with an inverted pyramid structure

[0054] Polydimethylsiloxane (PDMS) and vinyltrimethoxysilane were mixed evenly at a mass ratio of 10:1, poured onto a silicon template, and cured at 80°C for 2 hours. The resulting flexible PDMS substrate 1 with an inverted pyramid structure was peeled off from the silicon template.

[0055] 1.2 Place the flexible PDMS substrate 1 in an ultraviolet ozone (UVO) cleaning machine for ultraviolet ozone pretreatment for 35 minutes.

[0056] 1.3 Fabrication of a transparent anode 2 on a flexible PDMS substrate 1

[0057] A positive electrode solution was spin-coated onto a flexible PDMS substrate 1, annealed at 80°C for 20 min, immersed in formic acid for 5-15 min, washed, and dried to obtain a transparent positive electrode 2. The positive electrode solution included sorbitol and PEDOT:PSS (pH 1000). The mass fraction of sorbitol in the positive electrode solution was 5%, and the spin-coating speed was 2000 rpm for 30 s.

[0058] 1.4. Fabrication of a hole transport layer 3 on the transparent anode 2

[0059] A hole transport layer solution was spin-coated onto the transparent anode 2 and annealed at 80°C for 20 min to obtain a hole transport layer 3. The hole transport layer solution included PEDOT:PSS(4083), and the spin-coating speed was 4000 rpm for 30 s.

[0060] 1.5. Prepare an active layer 4 on the hole transport layer 3.

[0061] An active layer solution was spin-coated onto the hole transport layer 3, annealed at 100°C for 10 min, and then subjected to vacuum treatment to obtain the active layer 4. The active layer solution was prepared by dissolving PBDB-T-2F, Y6, and C6 in chloroform, with a mass ratio of PBDB-T-2F, Y6, and C6 of 1:1.15:0.15. The concentration of the solute in the active layer solution was 15 mg / ml, the spin-coating speed was 4000 rpm, and the time was 30 s. The vacuum degree after vacuum treatment was 10... –4 Pa, the holding time is 2-30 min.

[0062] 1.6. Prepare electron transport layer 5 on active layer 4.

[0063] An electron transport layer solution was spin-coated onto the active layer 4 to obtain an electron transport layer 5; wherein the electron transport layer solution was prepared by dissolving PDINO in anhydrous methanol, with a concentration of 1.5 mg / ml, and the spin-coating speed was 3500 rpm for 30 s.

[0064] 1.7 Fabrication of a semi-transparent back electrode 6 on electron transport layer 5

[0065] A semi-transparent back electrode 6 made of Ag was deposited on the electron transport layer 5 using a vacuum evaporation process to obtain an ultra-flexible semi-transparent organic solar cell; wherein the vacuum degree of the vacuum evaporation was 10-4 Pa.

[0066] Experimental Example

[0067] The JV characteristics of the ultra-flexible semi-transparent organic solar cell prepared in Example 1 were tested, and the JV curve was obtained, as shown below. Figure 4 As shown, analysis Figure 4 It can be concluded that the open-circuit voltage of the ultra-flexible semi-transparent organic solar cell prepared in Example 1 is 0.844V, and the short-circuit current is 19.60mA / cm. 2 With a fill factor of 72.71% and a photoelectric conversion efficiency of 12.04%, it can be seen that the ultra-flexible semi-transparent organic solar cell prepared in Example 1 has excellent performance and high photoelectric conversion efficiency.

[0068] The transmittance of the ultra-flexible semi-transparent organic solar cell prepared in Example 1 was tested using a UV-Vis spectrometer. The test results are shown in [Figure 1]. Figure 5 ,from Figure 5It can be seen that the ultra-flexible semi-transparent organic solar cell prepared in Example 1 has an average transmittance of more than 20% in the visible light region (370-40nm), indicating that the ultra-flexible semi-transparent organic solar cell prepared in Example 1 has good light transmittance.

[0069] Furthermore, it should be noted that although the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for preparing an ultra-flexible semi-transparent organic solar cell, characterized in that, include: Step S1: After mixing polydimethylsiloxane and crosslinking agent evenly, pour the mixture into a mold, dry it, peel off the mold, and obtain a flexible PDMS substrate with an inverted pyramid structure (1). Step S2: Spin-coat the anode solution onto the flexible PDMS substrate (1), anneal it, and perform or not perform acidification treatment to obtain a transparent anode (2); wherein, the anode solution includes a polyhydroxy compound and PEDOT:PSS PH1000; Step S3: Prepare a hole transport layer (3) on the transparent anode (2); Step S4: Prepare an active layer (4) on the hole transport layer (3). The active layer (4) is made of PBDB-T-2F, Y6, and C6. The preparation method of the active layer (4) includes: spin-coating an active layer solution onto the hole transport layer (3), annealing at 80-120℃ for 5-15 min, and vacuum treatment to obtain an active layer (4) with a thickness of 80-200 nm. The active layer solution is prepared by dissolving PBDB-T-2F, Y6, and C6 in chloroform. The mass ratio of PBDB-T-2F, Y6, and C6 in the active layer solution is 1:1.15:0.

15. The concentration of the solute in the active layer solution is 13-15 mg / ml. The spin-coating speed is 3000-5000 rpm and the time is 20-40 s. The vacuum degree after vacuum treatment is 10. –4 Pa, holding time is 2-30 min; Step S5: Prepare an electron transport layer (5) on the active layer (4); Step S6: Prepare a semi-transparent back electrode (6) on the electron transport layer (5) to obtain an ultra-flexible semi-transparent organic solar cell.

2. The method for preparing the ultra-flexible semi-transparent organic solar cell according to claim 1, characterized in that, In step S2, the polyhydroxy compound includes one of sorbitol, ethylene glycol, xylitol, and hexanediol.

3. The method for preparing an ultra-flexible semi-transparent organic solar cell according to claim 1, characterized in that, In step S2, the mass fraction of the polyhydroxy compound in the anode solution is 3-8%.

4. The method for preparing an ultra-flexible semi-transparent organic solar cell according to claim 1, characterized in that, In step S2, after annealing, acidification is performed, which includes immersion in an acid solution.

5. The method for preparing an ultra-flexible semi-transparent organic solar cell according to claim 1, characterized in that, In step S2, the annealing temperature is 70-90℃ and the time is 15-25min.

6. The method for preparing an ultra-flexible semi-transparent organic solar cell according to claim 1, characterized in that, In step S3, the material of the hole transport layer (3) includes PEDOT:PSS 4083.

7. The method for preparing an ultra-flexible semi-transparent organic solar cell according to claim 1, characterized in that, In step S5, the material of the electron transport layer (5) includes PDINO.

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