A low-melting-point alloy top electrode, its preparation method and application

Abstract

This invention relates to the field of organic photovoltaic cell technology, and particularly to a low-melting-point alloy top electrode, its preparation method, and its application. The preparation method of the low-melting-point alloy top electrode includes the following steps: heating and melting a low-melting-point alloy, adding it to a syringe equipped with a heating head, and using a temperature control system to control the heating head on the syringe to maintain the low-melting-point alloy in a liquid state; controlling printing parameters so that the liquid low-melting-point alloy is pulled out from the syringe needle by shear force and printed onto a substrate; and cooling to obtain the low-melting-point alloy top electrode. This invention uses a solid low-melting-point alloy as raw material and employs fused deposition modeling to prepare a low-temperature alloy top electrode as the top electrode for organic photovoltaic cells. Its electrode film thickness is controllable, enabling the preparation of alloy films with a thickness of less than 100 μm, thereby saving materials and costs; it also exhibits good repeatability, low printing cost, and is suitable for the preparation of large-area battery modules.

Description

Technical Field

[0001] This invention relates to the field of organic photovoltaic cell technology, and in particular to a low-melting-point alloy top electrode, its preparation method, and its application. Background Technology

[0002] Organic photovoltaic (PV) cells use organic semiconductor materials as the photosensitive active layer and can be fabricated using room-temperature solution methods. This facilitates large-area, low-cost roll-to-roll printing, making it considered one of the most promising third-generation photovoltaic technologies. However, the top electrode of PV cells is typically fabricated using vacuum evaporation of metal. This method is time-consuming, has low yield, and is costly, becoming a bottleneck limiting roll-to-roll printing of PV cells. Other materials used to replace evaporated metal as the top electrode of PV cells mainly include conductive polymers, silver nanowires, silver nanoparticles, carbon nanotubes, and graphene. However, these contain solvents or additives, which can easily damage the active layer. Liquid metals offer many advantages suitable for use as the top electrode of PV cells, such as high conductivity, no need for high-temperature sintering, absence of solvents and additives, and the ability to be fabricated using printing methods in a molten state.

[0003] However, existing methods for preparing organic photovoltaic (PV) top electrodes using liquid metal are typically haphazard, involving methods such as dripping, brushing, or heat lamination. These methods suffer from several drawbacks: 1) low repeatability; 2) uncontrollable thickness, making it difficult to form very thin films, resulting in material waste; 3) difficulty in fabricating large-area devices; 4) incompatibility with roll-to-roll and automated production methods; and 5) the lack of precise control over film thickness and patterning in organic PV electrode printing methods both domestically and internationally.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a low-melting-point alloy top electrode, its preparation method and application, in order to solve the problems of high cost, poor repeatability and thick thickness in the preparation of organic photovoltaic cell top electrodes.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a low-melting-point alloy top electrode includes the following steps:

[0008] The low-melting-point alloy is heated and melted, then added to a syringe equipped with a heating head. The heating head is controlled by a temperature control system to keep the low-melting-point alloy in a liquid state.

[0009] By controlling the printing parameters, liquid low-melting-point alloy is pulled out from the needle of the syringe by shear force and printed onto the substrate.

[0010] After the low-melting-point alloy printed on the substrate cools, the low-melting-point alloy top electrode is obtained;

[0011] The printing parameters include the distance between the needle and the substrate, the flow rate of the liquid low-melting-point alloy, the printing speed, the substrate temperature, and the temperature of the heating head; the melting point of the low-melting-point alloy is 40-100℃.

[0012] The method for preparing the low-melting-point alloy top electrode includes the following: the distance between the needle and the substrate is 40-60 μm; the flow rate of the liquid low-melting-point alloy is 1.2-1.5 μL / s; the printing speed is 15-25 mm / s; the substrate temperature is 18-22℃; and the heating head temperature is 70-90℃.

[0013] The method for preparing the low-melting-point alloy top electrode, wherein the low-melting-point alloy is Field's alloy.

[0014] The method for preparing the low-melting-point alloy top electrode, wherein the size of the needle tip is 15-20g.

[0015] The method for preparing the low-melting-point alloy top electrode, wherein the low-melting-point alloy top electrode is an electrode thin film with a thickness of less than 100 μm.

[0016] A low-melting-point alloy top electrode is prepared using the above-described method for preparing a low-melting-point alloy top electrode.

[0017] An application of a low-melting-point alloy top electrode, wherein the low-melting-point alloy top electrode is used as the top electrode of an organic photovoltaic cell, an organic light-emitting diode, a quantum dot light-emitting diode, or a perovskite light-emitting diode.

[0018] The application of the low-melting-point alloy top electrode, wherein the organic photovoltaic cell comprises a substrate, a transparent bottom electrode, a hole transport layer, an organic photovoltaic active layer, an electron transport layer and a low-melting-point alloy top electrode layer stacked sequentially from bottom to top.

[0019] Beneficial Effects: This invention provides a low-melting-point alloy top electrode, its preparation method, and its application. The preparation method of the low-melting-point alloy top electrode includes the following steps: heating and melting the low-melting-point alloy, adding it to a syringe equipped with a heating head, and using a temperature control system to control the heating head on the syringe to keep the low-melting-point alloy in a liquid state; controlling the printing parameters so that the liquid low-melting-point alloy is pulled out from the needle of the syringe by shear force and deposited on a substrate; and obtaining the low-melting-point alloy top electrode after cooling. This invention uses solid low-melting-point alloy as raw material and employs fused deposition modeling to prepare a low-temperature alloy top electrode as the top electrode of an organic photovoltaic cell. Its electrode film thickness is controllable, enabling the preparation of alloy films with a thickness of less than 100 μm, thereby saving materials and costs; it is also easy to pattern the electrode shape, allowing for patterned printing as needed; it has good repeatability, low printing cost, and is suitable for the preparation of large-area battery modules. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the cutting and printing principle of the present invention;

[0021] Figure 2 This is a schematic diagram of the organic photovoltaic cell structure with a low-melting-point alloy top electrode in this invention;

[0022] Figure 3 This is a schematic diagram of an organic photovoltaic cell device with a low-melting-point alloy top electrode prepared according to Example 1 of the present invention. Detailed Implementation

[0023] This invention provides a low-melting-point alloy top electrode, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0024] In the implementation methods and claims, unless otherwise specified in the text, the terms "a," "an," "the," and "the" may also include plural forms. If the embodiments of the present invention involve descriptions of "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0025] It should be further understood that the term "comprising" as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0026] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0027] This invention provides a method for preparing a low-melting-point alloy top electrode, comprising the following steps:

[0028] Step S10: After heating and melting the low-melting-point alloy, add it to a syringe equipped with a heating head, and use a temperature control system to control the heating head to keep the low-melting-point alloy in a liquid state;

[0029] Step S20: By controlling the printing parameters, the liquid low-melting-point alloy is pulled out from the needle of the syringe by shear force and printed onto the substrate.

[0030] Step S20: After the low-melting-point alloy to be printed on the substrate is cooled, the low-melting-point alloy top electrode is obtained.

[0031] In this embodiment, the low-melting-point alloy is first heated and melted, then added to a syringe. A temperature control system is used to maintain a constant temperature on the heating head mounted on the syringe, ensuring the low-melting-point alloy remains in a liquid state. Finally, by controlling the printing parameters, the distance between the needle and the substrate creates a shear force between the liquid low-melting-point alloy and the substrate, thereby pulling the liquid low-melting-point alloy from the needle and depositing it onto the substrate (i.e., shear printing, the principle of which is illustrated in the diagram). Figure 1 As shown in the figure, a low-melting-point alloy top electrode can be obtained after cooling. This preparation method is low-cost, easy to realize, and can be used to prepare large-area electrodes quickly, replacing the vapor-deposited electrodes. It can also achieve device efficiency close to that of vapor-deposited electrodes. Furthermore, it is compatible with roll-to-roll and automated production methods and can be used to prepare fully printed organic photovoltaic cells.

[0032] Specifically, the thickness of the low-melting-point alloy top electrode is mainly achieved by controlling the distance between the needle and the substrate. Since the surface tension of the low-melting-point metal liquid is extremely high (about 9 times that of water), the liquid low-melting-point alloy must be rapidly cooled in order to achieve a thin film. Controlling the distance between the needle and the substrate can make the low-melting-point alloy top electrode thinner and achieve rapid cooling. At the same time, the problem of needle blockage caused by the needle temperature drop due to contact with the substrate is solved by intermittently lifting the needle. Finally, a low-melting-point alloy top electrode thin film with a large aspect ratio, low surface resistivity, and smooth and flat surface is obtained.

[0033] In some embodiments, the printing parameters include the distance between the needle and the substrate, the flow rate of the liquid low-melting-point alloy, the printing speed, the substrate temperature, and the temperature of the heating head. By setting these parameters, electrode films (low-melting-point alloy top electrodes) with identical properties can be printed, resulting in high production repeatability. Furthermore, by setting these parameters, electrode films with a thickness of less than 100 μm can be obtained, ensuring both high electrode conductivity and material savings. Additionally, by setting the parameters of the fused deposition modeling (FDM) method, the contact interface between the electrode and the active layer can be optimized, thereby ensuring high efficiency of the alloy electrode device. By setting the printing pattern of the electrode, large-area organic photovoltaic devices can be fabricated. It is compatible with roll-to-roll and automated production methods, and by adjusting the printing speed, rapid and automated printing of organic photovoltaic electrodes can be achieved.

[0034] In some embodiments, the distance between the needle and the substrate is 40-60 μm; the flow rate of the liquid low-melting-point alloy is 1.2-1.5 μL / s; the printing speed is 15-25 mm / s; the substrate temperature is 18-22°C; and the heating head temperature is 70-90°C. By setting the printing parameters within the above ranges, a low-melting-point alloy top electrode with a thickness of less than 100 μm can be obtained. The substrate temperature of 18-22°C allows for rapid cooling and solidification of the low-melting-point alloy deposited on the substrate.

[0035] In one specific embodiment, the distance between the needle and the substrate is 50 μm; the flow rate of the liquid low-melting-point alloy is 1.22 μL / s; the printing speed is 20 mm / s; the substrate temperature is 20 °C; and the heating head temperature is 80 °C, so that the thickness of the resulting low-melting-point alloy top electrode is between 95-100 μm.

[0036] In some embodiments, the low-melting-point alloy is, but is not limited to, Field's alloy; the Field's alloy is composed of Bi / In / Sn (22.5%, 51%, 16.5%) and has a melting point of 62°C; the low-melting-point alloy may also be a 47°C fusible alloy, the 47°C fusible alloy being composed of Bi / Pb / Sn / Cd / In (44.7%, 22.6%, 8.2%, 5.2%, 19.1%).

[0037] In some embodiments, the needle is 15-20G in size; the distance between the needle and the substrate allows the liquid low-melting-point alloy to be pulled out by the shear force between the needle and the substrate and deposited on the substrate, and then cooled to obtain a low-melting-point alloy top electrode.

[0038] In a preferred embodiment, the needle is 17G in size.

[0039] In some embodiments, the low-melting-point alloy top electrode is an electrode film with a thickness of less than 100 μm; the smaller the thickness of the low-melting-point alloy electrode, the larger the aspect ratio and the smaller the surface resistivity of the electrode film.

[0040] In addition, the present invention also provides a low-melting-point alloy top electrode, which is prepared by the same method as described above.

[0041] The present invention also provides an application of a low-melting-point alloy top electrode, which is used as the top electrode of an organic photovoltaic cell, an organic light-emitting diode, a quantum dot light-emitting diode, or a perovskite light-emitting diode.

[0042] In some implementations, such as Figure 2 As shown, the organic photovoltaic cell includes, from bottom to top, a substrate 10, a transparent bottom electrode 20, a hole transport layer 20, an organic photovoltaic active layer 40, an electron transport layer 50, and a low-melting-point alloy top electrode layer 60, which are stacked sequentially. The low-melting-point alloy top electrode layer 60 is disposed at intervals on the side of the electron transport layer 50 facing away from the organic photovoltaic active layer 40. The substrate 10 is a glass substrate; the transparent bottom electrode 20 is indium tin oxide (ITO); the hole transport layer 20 is PEDOT:PSS; and the electron transport layer 50 is PDINO.

[0043] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0044] Example 1

[0045] Field's alloy is used as the material for the top electrode of organic photovoltaic cells. After the Field's alloy is heated and melted, it is added to a syringe. The heating head set on the syringe is controlled by a temperature control system to make the low melting point alloy liquid. By controlling the printing parameters, the liquid low melting point alloy is pulled out from the needle of the syringe by shear force and deposited on the substrate. After cooling, the low melting point alloy top electrode is obtained.

[0046] The printing parameters shown are as follows: the distance between the needle and the substrate is 50 μm; the flow rate of the liquid low-melting-point alloy is 1.22 μL / s; the printing speed is 20 mm / s; the substrate temperature is 20 °C; and the heating head temperature is 62 °C.

[0047] Experiments have verified that a low-melting-point metal electrode with a height of approximately 100 micrometers can be fabricated using the above parameters, as shown in the following figure. Figure 2 As shown, organic solar cell devices fabricated using this electrode can achieve an efficiency of 16.44% and a series resistance of approximately 5 ohms / cm. 2 The parallel resistance is approximately 1000 ohms / cm 2 The fill factor reaches 74%, indicating that the electrode prepared by this process has good contact with the interface and does not damage the interface film. Compared with vapor-deposited silver electrodes, it has lower cost and roll-to-roll production potential.

[0048] Lifetime tests showed that organic solar devices using this electrode retained 70% efficiency after 100 hours of exposure to air, while under the same conditions, devices using vapor-deposited Ag electrodes only achieved 20% of the original efficiency. This demonstrates that this electrode has better water and oxygen isolation performance compared to Ag electrodes.

[0049] In summary, this invention provides a low-melting-point alloy top electrode, its preparation method, and its application. The preparation method includes the following steps: heating and melting the low-melting-point alloy, adding it to a syringe equipped with a heating head, and using a temperature control system to control the heating head on the syringe to keep the low-melting-point alloy in a liquid state; controlling printing parameters to allow the liquid low-melting-point alloy to be pulled out from the syringe needle by shear force and deposited on a substrate; and cooling to obtain the low-melting-point alloy top electrode. This invention uses a solid low-melting-point alloy as raw material and employs fused deposition modeling to prepare a low-temperature alloy top electrode as the top electrode for organic photovoltaic cells. Its electrode film thickness is controllable, enabling the preparation of alloy films with a thickness of less than 100 μm, thus saving materials and costs. Simultaneously, the electrode shape is easily patterned, allowing for patterned printing as needed; it has good repeatability, low printing cost, and is suitable for the preparation of large-area battery modules.

[0050] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method of making a low melting point alloy top electrode, characterized by, Including the following steps: The low-melting-point alloy is heated and melted, then added to a syringe equipped with a heating head. The heating head is controlled by a temperature control system to keep the low-melting-point alloy in a liquid state. By controlling the printing parameters, liquid low-melting-point alloy is pulled out from the needle of the syringe by shear force and printed onto the substrate. After the low-melting-point alloy printed on the substrate cools, the low-melting-point alloy top electrode is obtained; The printing parameters include the distance between the needle and the substrate, the flow rate of the liquid low-melting-point alloy, the printing speed, the substrate temperature, and the temperature of the heating head; the melting point of the low-melting-point alloy is 40~100℃. The distance between the needle and the substrate is 40-60 μm; the flow rate of the liquid low-melting-point alloy is 1.2-1.5 μL / s; the printing speed is 15-25 mm / s; the substrate temperature is 18-23℃; the heating head temperature is 70-90℃; the low-melting-point alloy is Field's alloy. The needle has a size of 15-20g; the low-melting-point alloy top electrode is an electrode film with a thickness of less than 100μm; the thickness of the low-melting-point alloy top electrode is controlled by controlling the distance between the needle and the substrate.

2. A low-melting-point alloy top electrode, characterized in that, The low-melting-point alloy top electrode is prepared using the method for preparing a low-melting-point alloy top electrode as described in claim 1.

3. An application of the low-melting-point alloy top electrode as described in claim 2, characterized in that, The low-melting-point alloy top electrode is used as the top electrode of organic photovoltaic cells, organic light-emitting diodes, quantum dot light-emitting diodes, and perovskite light-emitting diodes.

4. The application of the low-melting-point alloy top electrode according to claim 3, characterized in that, The organic photovoltaic cell includes a substrate, a transparent bottom electrode, a hole transport layer, an organic photovoltaic active layer, an electron transport layer, and a low-melting-point alloy top electrode stacked from bottom to top.

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