Application of diphenyl disulfide as photovoltaic cell active layer additive and photovoltaic cell

Abstract

The invention discloses an application of diphenyl disulfide as an additive of an active layer of a photovoltaic cell and the photovoltaic cell, which comprises the step of adding a volatile solid additive diphenyl disulfide into the active layer to regulate and control the performance of the active layer. The solid additive is added in the acceptor film forming process, and acceptor molecule aggregation and crystallization behaviors are continuously regulated and controlled in the film forming process and the thermal annealing process. The introduction of diphenyl disulfide can synergistically optimize multi-stage crystallization kinetics, enhance H-aggregation and J-aggregation at the same time, promote the formation of a receptor fibrous polycrystalline structure, improve the carrier mobility, and effectively improve the exciton dissociation and charge transfer capabilities of the active layer. Based on the regulation and control, the organic photovoltaic device using the diphenyl disulfide as the additive realizes the significant improvement of photovoltaic performance, the energy conversion efficiency reaches 19%, a new development direction is provided for the design of a multifunctional solid additive and the accurate control of the form of an active layer in the future, and a powerful technical support is provided for organic photovoltaic industrialization in the future.

Description

Technical Field

[0001] This invention belongs to the field of diphenyl disulfide application and photovoltaic cell technology, specifically involving the application of diphenyl disulfide as an additive for the active layer of photovoltaic cells and photovoltaic cells. Background Technology

[0002] Organic solar cells (OSCs) have attracted widespread attention due to their lightweight, low cost, flexibility, and ease of large-area roll-to-roll production. With the development of information and IoT technologies, flexible and thin OSCs, due to their portability and extremely high power density, have shown broad application prospects. Breakthroughs in OSC photoelectric conversion efficiency (PCE), now exceeding 20%, are mainly attributed to the development of Y-series non-fullerene acceptors (NFAs) (such as Y6 and its derivatives). These NFAs exhibit excellent photoelectric properties, including strong and broad absorption in the near-infrared region, tunable energy levels, and significantly reduced energy loss compared to fullerene acceptors. However, the final photovoltaic performance of NFA-based OSCs is not solely determined by the properties of the donor or acceptor materials themselves. Instead, it is highly sensitive to the nanoscale morphology of the active layer. An ideal morphology should include a bicontinuous interpenetrating network, suitable phase region size, high phase purity, and, most importantly, optimized molecular packing and crystallization of the NFA components. This structure is crucial for efficient exciton dissociation, charge transport, and minimizing charge recombination.

[0003] To achieve ideal morphology control, post-treatment techniques such as thermal annealing and solvent vapor annealing are commonly employed. While these methods are effective to some extent, their precise controllability is often insufficient, and they are prone to causing batch-to-batch performance variations. In contrast, additive engineering is gaining increasing attention as a more powerful and versatile strategy. Among these, high-boiling-point solvent additives (especially 1,8-diiodooctane) are particularly widely used, as they can selectively dissolve acceptor or donor components, thereby effectively controlling drying kinetics and promoting the formation of more optimized fibrous morphologies. However, such volatile liquid additives are often difficult to completely remove, and residues can become a potential cause of morphological instability, leading not only to device performance degradation but also adversely affecting its long-term operational stability.

[0004] These limitations have prompted researchers to explore solid additives as a promising alternative. The emerging field of solid additive engineering has developed rapidly, evolving from early simple crystalline powders to today's complex and functionally diverse molecular systems. Early studies have shown that non-volatile solid additives can guide the ordered arrangement of molecules. A significant advancement is the use of solid additives with specific molecular configurations (such as planar or halogen-substituted structures), which can embed themselves into the lattice of active layer materials through intermolecular interactions (such as π-π stacking and halogen bonding), acting as nucleating agents to enhance crystallinity and optimize phase separation morphology.

[0005] However, the practical application of solid additives still faces multiple technical bottlenecks, such as the difficulty of balancing molecular configuration and morphology control, the ambiguity of the mechanism of action leading to low optimization efficiency, and insufficient system compatibility and universality. These defects together mean that solid additives still need to overcome multiple technical barriers in the commercialization process of OSCs. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide the application of diphenyl disulfide as an additive for the active layer of photovoltaic cells.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: adding diphenyl disulfide to a chloroform solution containing L8-BO to form an active layer solution, spin-coating it onto the anode interface layer of a photovoltaic cell, and then annealing it to form a second active layer.

[0010] As a preferred embodiment of the application of diphenyl disulfide as an additive for the active layer of photovoltaic cells according to the present invention, the concentration of diphenyl disulfide in the active layer solution is 3~5 mg / ml.

[0011] As a preferred embodiment of the application of the diphenyl disulfide described in this invention as an additive for the active layer of photovoltaic cells, the concentration of L8-BO in the active layer solution is 7~9 mg / ml.

[0012] As a preferred embodiment of the application of the diphenyl disulfide described in this invention as an additive for the active layer of photovoltaic cells, the annealing treatment is performed at a temperature of 90~110℃ for a time of 2~4 minutes.

[0013] As a preferred embodiment of the application of diphenyl disulfide as an additive for the active layer of photovoltaic cells according to the present invention, wherein: a first active layer is further disposed between the second active layer and the anode interface layer, and the first active layer is obtained by spin coating with a chloroform solution containing PM6.

[0014] As a preferred embodiment of the application of the diphenyl disulfide described in this invention as an additive for the active layer of photovoltaic cells, the concentration of the chloroform solution containing PM6 is 6~8 mg / ml.

[0015] Another object of the present invention is to provide a photovoltaic cell that uses the diphenyl disulfide described in claim 1 as an active layer additive.

[0016] To solve the above-mentioned technical problems, the present invention provides the following technical solution: the structure from bottom to top includes, The anode layer, the anode interface layer, the first active layer, the second active layer, the cathode interface layer, and the cathode layer are all transparent.

[0017] In a preferred embodiment of the photovoltaic cell described in this invention, the thickness of the active layer composed of the first active layer and the second active layer is 80~150nm.

[0018] In a preferred embodiment of the photovoltaic cell described in this invention, the anode interface layer is made of 3-BPIC-F and has a thickness of 5~30nm.

[0019] In a preferred embodiment of the photovoltaic cell described in this invention, the cathode interface layer is made of PDINN and has a thickness of 3~10nm.

[0020] Beneficial effects of this invention: In this invention, the addition of the solid additive diphenyl disulfide can continuously and effectively regulate the crystallization dynamics of acceptor molecules during the film formation process and subsequent annealing stage, promoting the formation of more ordered molecular stacking of L8-BO, while enhancing H-aggregation and J-aggregation to form a fibrous polycrystalline structure, thus improving exciton dissociation and charge transport characteristics. At the same time, the addition of diphenyl disulfide can broaden the spectral absorption range of L8-BO, enhance light absorption, and improve charge generation characteristics, thereby effectively improving the performance of photovoltaic devices. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the structure of the photovoltaic cell of the present invention.

[0022] Figure 2 The figures show the current-voltage characteristic curves of the photovoltaic cells obtained in Embodiment 1 and Comparative Example 10 of the present invention, where curve 1 represents Comparative Example 10 and curve 2 represents Embodiment 1.

[0023] Figure 3 This is a schematic diagram of the thin film crystal morphology control mechanism corresponding to the photovoltaic cells prepared in Example 1 and Comparative Example 10 of the present invention. Detailed Implementation

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0025] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0026] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0027] Unless otherwise specified, all raw materials used in this invention are commercially available in the art, and their specific sources are shown in Table 1: Table 1

[0028] The performance testing method for the photovoltaic cells prepared in this invention is as follows: The photovoltaic cells in each embodiment or comparison underwent PCE testing in an atmospheric environment, with illumination conditions provided by a Class 3A AM 1.5G solar simulator (SAN-EI ELECTRIC CO.LTD, XES-300S1, Japan) at a light intensity of 100 mW / cm². 2 After the light was turned on and stabilized for 30 minutes, the light intensity was calibrated using a standard silicon cell with a KG-5 filter. JV curve tests were performed, and data acquisition was completed using a Keithley 2400 source meter. The test voltage range was -0.2 V to 1 V, with a voltage step of 0.05 V. The current-voltage characteristics under AM 1.5G simulated sunlight at 100 mW / cm² were tested.

[0029] Example 1 Reference Figure 1 This is a schematic diagram of the photovoltaic cell structure of the present invention. The photovoltaic cell structure, from bottom to top, includes, Transparent anode layer, made of indium tin oxide (ITO); Anode interface layer, material is 3-BPIC-F; The photoactive layer consists of a first active layer and a second active layer deposited sequentially. The cathode interface layer is made of PDINN. The cathode layer is made of metallic silver.

[0030] The method for preparing the photovoltaic cell is as follows: 1) A glass substrate with an indium tin oxide (ITO) thickness of 150 nm was sequentially ultrasonically cleaned with alkaline solution, deionized water, acetone and isopropanol, and then treated with oxygen plasma for 10 min to obtain pretreated ITO, which was used as a transparent anode layer. 2) Spin-coat 0.5 mg / ml of 3-BPIC-F solution onto the surface of the transparent anode layer, and anneal at 80°C for 5 min to form an anode interface layer with a thickness of 10 nm; 3) First, spin-coat a 7 mg / ml chloroform solution of PM6 onto the surface of the anode interface layer at a spin speed of 2500 rpm for 30 s. After the chloroform evaporates, the first active layer is formed. Diphenyl disulfide, L8-BO and chloroform were prepared into a chloroform solution with a diphenyl disulfide concentration of 4 mg / ml and an L8-BO concentration of 8 mg / ml. This solution was then spin-coated onto the surface of the first active layer at a spin speed of 4500 rpm for 30 s. After annealing at 100°C for 3 min, the second active layer was formed. 4) Rotate the PDINN solution on the surface of the second active layer at a speed of 3000 rpm to form a 5 nm cathode interface layer. 5) Transfer the product from step 4) to a vacuum evaporation apparatus, and heat it at 2×10⁻⁶ ℃. -4 A 100 nm thick Ag layer is deposited in a vacuum chamber to form a cathode layer, thus obtaining the photovoltaic cell of this embodiment.

[0031] Comparative Example 1 The difference between this comparative example and Example 1 is that the concentration of diphenyl disulfide in the second active layer solution in step 3) is adjusted to 2 mg / ml, while the remaining steps are the same as in Example 1, to obtain the photovoltaic cell of this comparative example.

[0032] Comparative Example 2 The difference between this comparative example and Example 1 is that the concentration of diphenyl disulfide in the second active layer solution in step 3) is adjusted to 6 mg / ml, while the remaining steps are the same as in Example 1, to obtain the photovoltaic cell of this comparative example.

[0033] The performance of the photovoltaic cells prepared in Example 1, Comparative Example 1, and Comparative Example 2 was measured, and the results are shown in Table 2.

[0034] Table 2

[0035] As shown in Table 2, both excessively high and low concentrations of diphenyl disulfide (DPS) lead to a decrease in photovoltaic performance. When the DPS concentration is too low, although a relatively high open-circuit voltage is maintained, the increase in fill factor and short-circuit current density is not significant. This is because the amount of DPS added is insufficient, and its interaction with the acceptor is not obvious. Therefore, its effect on the microstructure regulation of the device is also weak, resulting in suboptimal photovoltaic performance. When the DPS concentration is too high, the open-circuit voltage decreases further, but at the same time, the short-circuit current density and fill factor do not increase further, so the photovoltaic performance still decreases. This may be because more DPS molecules in the active layer further enhance the regulation effect. Excessive regulation can lead to larger aggregation of microstructures in the active layer, reducing the donor-acceptor interface.

[0036] Comparative Example 3 The difference between this comparative example and Example 1 is that the annealing temperature in step 3) is adjusted to 80°C, while the remaining steps are the same as in Example 1, to obtain the photovoltaic cell of this comparative example.

[0037] Comparative Example 4 The difference between this comparative example and Example 1 is that the annealing temperature in step 3) is adjusted to 120°C, while the remaining steps are the same as in Example 1, to obtain the photovoltaic cell of this comparative example.

[0038] The performance of the photovoltaic cells prepared in Comparative Examples 3 and 4 was measured and compared with that of Example 1. The results are shown in Table 3.

[0039] Table 3

[0040] As shown in Table 3, compared with the annealing temperature of 100 °C used in the examples, both decreasing and increasing the annealing temperature will decrease photovoltaic performance, mainly manifested in a reduction in short-circuit current density and fill factor. The purpose of annealing the active layer is twofold: first, to remove the additive diphenyl disulfide from the active layer; and second, to further optimize the morphology of the active layer.

[0041] Comparative Example 5 The difference between this comparative example and Example 1 is that the diphenyl disulfide in the second active layer solution in step 3) is replaced with diphenyl sulfide, while the remaining steps are the same as in Example 1, to obtain the photovoltaic cell of this comparative example.

[0042] Comparative Example 6 The difference between this comparative example and Example 1 is that the diphenyl disulfide in the second active layer solution in step 3) is replaced with 4,4'-dimethyl diphenyl disulfide, while the remaining steps are the same as in Example 1, to obtain the photovoltaic cell of this comparative example.

[0043] Comparative Example 7 The difference between this comparative example and Example 1 is that the diphenyl disulfide in the second active layer solution in step 3) is replaced with 2,2'-difluorodiphenyl disulfide, while the remaining steps are the same as in Example 1, to obtain the photovoltaic cell of this comparative example.

[0044] Comparative Example 8 The difference between this comparative example and Example 1 is that the diphenyl disulfide in the second active layer solution in step 3) is replaced with 2,2'-dichlorodiphenyl disulfide, while the remaining steps are the same as in Example 1, to obtain the photovoltaic cell of this comparative example.

[0045] Comparative Example 9 The difference between this comparative example and Example 1 is that the diphenyl disulfide in the second active layer solution in step 3) is replaced with (2-bromophenyl)(2,4-dimethylphenyl)thionane, while the remaining steps are the same as in Example 1, to obtain the photovoltaic cell of this comparative example.

[0046] Comparative Example 10 The difference between this comparative example and Example 1 is that the diphenyl disulfide in the second active layer solution in step 3) is omitted, while the remaining steps are the same as in Example 1, to obtain the photovoltaic cell of this comparative example.

[0047] The performance of the photovoltaic cells prepared in Comparative Examples 5 to 10 was measured and compared with that in Example 1. The results are shown in Table 4.

[0048] Table 4

[0049] In addition to the diphenyl disulfide solid additive in the embodiments, this invention also introduces other additives with similar structures to diphenyl disulfide to regulate the acceptor, and the results are shown in Table 4. Introducing halogen atoms and methyl groups onto the benzene ring structure of diphenyl disulfide can also regulate the active layer, but the effect is not as good as that of the diphenyl disulfide in the embodiments of this invention.

[0050] Figure 2 Table 2 shows the current-voltage characteristic curves of the photovoltaic cells of Comparative Example 10 and Example 1 in the organic photovoltaic cell preparation method provided by the embodiments of the present invention, where curve 1 represents Comparative Example 10 and curve 2 represents Example 1. As can be seen from the figure, Example 1, with the addition of diphenyl disulfide, has a higher short-circuit current and fill factor than Comparative Example 10 without additives. Table 2 shows the performance parameters of the photovoltaic cells of Comparative Example 10 and Example 1 in the organic photovoltaic cell preparation method provided by the embodiments of the present invention. It can be more directly seen that the fill factor and photoelectric conversion efficiency of Example 1 are significantly improved, increasing from 74.8% and 17.4% in Comparative Example 10 to 79.5% and 19.0% in Example 1, respectively.

[0051] Figure 3 This is a schematic diagram illustrating the thin film crystal morphology control mechanism of the photovoltaic cells in Comparative Example 10 and Example 1 in the organic photovoltaic cell fabrication method provided by this invention. It can be seen that in Comparative Example 10, the distribution of the acceptor material is relatively random and lacks obvious orientation. However, the introduction of the solid additive diphenyl disulfide enhances the orderliness of the acceptor molecules, promotes closer α-α stacking, and thus improves the crystallinity of the active layer. Diphenyl disulfide regulates the disordered acceptor crystal orientation, forming a fibrous polycrystalline structure, which enhances carrier mobility and generates a more balanced charge carrier transport, thereby improving device performance.

[0052] Example 2 The difference between this embodiment and embodiment 1 is that step 3) is adjusted as follows: First, spin-coat an 8 mg / ml chloroform solution of PM6 onto the surface of the anode interface layer at a spin speed of 2500 rpm for 30 s. After the chloroform evaporates, the first active layer is formed. Diphenyl disulfide, L8-BO and chloroform were prepared into a chloroform solution with a diphenyl disulfide concentration of 5 mg / ml and an L8-BO concentration of 9 mg / ml. This solution was then spin-coated onto the surface of the first active layer at a spin speed of 4500 rpm for 30 s. After annealing at 100°C for 3 min, the second active layer was formed. The remaining steps and processes are the same as in Example 1, resulting in the photovoltaic cell of this example.

[0053] Example 3 The difference between this embodiment and embodiment 1 is that step 3) is adjusted as follows: A chloroform solution of PM6 at a concentration of 6 mg / ml was first spin-coated onto the surface of the anode interface layer at a spin speed of 2500 rpm for 30 s. After the chloroform evaporated, the first active layer was formed. Diphenyl disulfide, L8-BO and chloroform were prepared into a chloroform solution with a diphenyl disulfide concentration of 3 mg / ml and an L8-BO concentration of 7 mg / ml. This solution was then spin-coated onto the surface of the first active layer at a spin speed of 4500 rpm for 30 s. After annealing at 100°C for 3 min, the second active layer was formed. The remaining steps and processes are the same as in Example 1, resulting in the photovoltaic cell of this example.

[0054] The performance of the photovoltaic cells prepared in Examples 2 and 3 was measured and compared with that of Example 1. The results are shown in Table 5.

[0055] Table 5

[0056] As can be seen from Table 5, the performance of the batteries prepared in Examples 2 and 3 is slightly lower than that in Example 1, but is still better than the comparative examples.

[0057] In summary, the addition of the solid additive diphenyl disulfide in this invention can continuously and effectively regulate the crystallization dynamics of acceptor molecules during the film formation process and subsequent annealing stage, promoting the formation of more ordered molecular stacking of L8-BO, while enhancing H-aggregation and J-aggregation to form a fibrous polycrystalline structure, thus improving exciton dissociation and charge transport characteristics. At the same time, the addition of diphenyl disulfide can broaden the spectral absorption range of L8-BO, enhance light absorption, and improve charge generation characteristics, thereby effectively improving the performance of photovoltaic devices.

[0058] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. The application of diphenyl disulfide as an additive for the active layer of photovoltaic cells, characterized in that: Diphenyl disulfide is added to a chloroform solution containing L8-BO to form an active layer solution, which is then spin-coated onto the anode interface layer of a photovoltaic cell and annealed to form a second active layer.

2. The application of diphenyl disulfide as an additive in the active layer of photovoltaic cells as described in claim 1, characterized in that: The concentration of diphenyl disulfide in the active layer solution is 3~5 mg / ml.

3. The application of diphenyl disulfide as an additive in the active layer of photovoltaic cells as described in claim 2, characterized in that: The concentration of L8-BO in the active layer solution is 7~9 mg / ml.

4. The application of diphenyl disulfide as an additive in the active layer of photovoltaic cells as described in claim 1, characterized in that: The annealing process is performed at a temperature of 90-110°C for 2-4 minutes.

5. The application of diphenyl disulfide as described in claim 1 as an additive for the active layer of photovoltaic cells, characterized in that: A first active layer is disposed between the second active layer and the anode interface layer. The first active layer is obtained by spin-coating with a chloroform solution containing PM6.

6. The application of diphenyl disulfide as an additive in the active layer of photovoltaic cells as described in claim 4, characterized in that: The concentration of the chloroform solution containing PM6 is 6~8 mg / ml.

7. A photovoltaic cell, characterized in that: Using the diphenyl disulfide of claim 1 as an active layer additive, the structure from bottom to top includes, The anode layer, the anode interface layer, the first active layer, the second active layer, the cathode interface layer, and the cathode layer are all transparent.

8. The photovoltaic cell as described in claim 7, characterized in that: The thickness of the active layer, which is composed of the first active layer and the second active layer, is 80~150nm.

9. The photovoltaic cell as described in claim 7, characterized in that: The anode interface layer is made of 3-BPIC-F and has a thickness of 5~30nm.

10. The photovoltaic cell as described in claim 7, characterized in that: The cathode interface layer is made of PDINN and has a thickness of 3~10nm.

Images