Ag / ITO transparent conductive heat-insulating layer based on Ag concentration gradient and preparation method thereof

Abstract

The application discloses an Ag / ITO transparent conductive heat-insulating layer based on an Ag concentration gradient and a preparation method thereof, and belongs to the technical field of transparent conductive films and photoelectric functional materials. The application aims at solving the problem that a silver layer is prone to cracking or migration on a flexible polymer substrate in the prior art, so that the thin film is difficult to meet the long-term stable use requirement of a flexible device, and avoiding the problems of weak combination, easy oxidation, complex process, high cost and the like of a traditional ITO / Ag / ITO layered film interface. The method of the application adopts a physical vapor deposition mode to continuously deposit indium tin oxide on the surface of a flexible substrate and intermittently introduce silver, forms different Ag concentration gradients in the thickness direction, makes Ag diffuse in the ITO matrix with different concentration gradients to realize energization, and forms a composite film structure with high transmittance, low resistivity and high infrared reflection performance. The method of the application realizes the heat-insulating effect, has the advantages of simple process, low temperature and suitability for large-area preparation, and has wide engineering application potential.

Description

Technical Field

[0001] This invention belongs to the field of transparent conductive films and optoelectronic functional materials. Specifically, it relates to an Ag / ITO transparent conductive heat insulation layer based on Ag concentration gradient and its preparation method. Background Technology

[0002] Transparent conductive film (TCF) is a type of functional thin-film material that combines high visible light transmittance, good conductivity, and near-infrared heat radiation blocking capabilities. It is widely used in touch panels, displays, solar cells, smart windows, and defrosting devices. Indium tin oxide (ITO), as a typical transparent conductive oxide, is one of the most widely used TCF materials. However, ITO films exhibit strong free carrier absorption in the near-infrared band, which limits their performance in energy-saving insulation and infrared shielding applications.

[0003] To enhance the near-infrared reflectivity of ITO thin films, existing technologies typically introduce a silver (Ag) layer into the film, leveraging the high infrared reflectivity of Ag to improve the shielding effect against near-infrared radiation. However, research indicates that the ITO-Ag composite system suffers from poor chemical stability, weak interfacial adhesion, a narrow thickness processing window, and insufficient mechanical flexibility. Particularly on flexible polymer substrates, the Ag layer is prone to cracking or migration, making it difficult to meet the requirements for long-term stable use of flexible devices.

[0004] To further balance transparency, conductivity, and thermal insulation, an ITO / Ag / ITO (IAI) sandwich structure is currently used, with an Ag layer encapsulated by upper and lower ITO layers to improve interface stability. However, this multilayer structure still has the following technical defects: (1) The preparation process requires multiple depositions and strict control of the thickness of each layer, resulting in complex processes and poor repeatability; (2) Stress accumulation exists at the interlayer interface, making it prone to delamination or cracking under external force, and its bending resistance is poor; (3) ITO deposition usually requires high temperatures, which is not suitable for flexible substrates with low temperature resistance such as polyethylene terephthalate (PET); (4) Multiple depositions result in high energy consumption, and it is difficult to guarantee the uniformity of film thickness and large-area consistency, which is not conducive to industrial mass production. Therefore, it is urgent to develop a transparent conductive and thermally insulating film that can be formed in one step, prepared at low temperature, and has both excellent transparent conductivity and infrared reflection properties, as well as good flexibility and interface stability. Summary of the Invention

[0005] The technical problem this invention aims to solve is that, in existing technologies, silver (Ag) layers on flexible polymer substrates are prone to cracking or migration, making it difficult for the thin films to meet the long-term stable use requirements of flexible devices. This invention provides an Ag / ITO transparent conductive thermal insulation layer with an Ag concentration gradient and its preparation method. This invention introduces a gradient distribution of silver (Ag) concentration along the thickness direction in the ITO matrix, allowing Ag to be dispersed and embedded within the ITO in the form of nanoparticles. The content of Ag increases first and then decreases from one side of the film layer to the other, forming a biomimetic gradient composite structure. This invention alleviates the problems of interfacial stress concentration and performance degradation by replacing the abrupt interfaces in traditional multilayer films with continuous component transitions, thereby achieving low resistivity and good near-infrared reflective thermal insulation performance while maintaining high visible light transmittance.

[0006] To address the aforementioned technical problems, the present invention adopts the following technical solution: The purpose of this invention is to provide an Ag / ITO transparent conductive thermal insulation layer based on an Ag concentration gradient, comprising a flexible substrate and an Ag / ITO composite layer disposed on the surface of the flexible substrate. The Ag / ITO composite layer uses indium tin oxide (ITO) as a continuous matrix, and silver (Ag) is dispersed in the form of nanoparticles and embedded in the ITO matrix. The Ag exhibits a concentration gradient distribution from low to high and then back to low in the film thickness direction, thereby enabling the transparent conductive thermal insulation film to simultaneously possess high visible light transmittance, low surface resistivity, and excellent near-infrared reflective thermal insulation performance.

[0007] Further specifying, the Ag concentration gradient is a continuous gradient, a segmented gradient, or an equivalent continuous gradient.

[0008] Furthermore, the Ag nanoparticles are partially or completely coated with an ITO matrix to inhibit the oxidation and migration of silver.

[0009] The Ag concentration gradient includes a low Ag concentration region near the flexible substrate, a high Ag concentration region in the middle of the film, and a low Ag concentration region near the surface of the film.

[0010] Another objective of this invention is to provide a method for preparing the Ag / ITO transparent conductive thermal insulation layer based on the Ag concentration gradient.

[0011] A method for preparing an Ag / ITO transparent conductive thermal insulation layer based on an Ag concentration gradient includes the following steps: Step 1: Pre-treat the flexible substrate; Step 2: Under an inert gas protective atmosphere, indium tin oxide (ITO) is continuously deposited on the substrate surface treated in Step 1 using physical vapor deposition. During the deposition process, silver (Ag) is deposited intermittently. By controlling the intermittent deposition sequence of silver, a concentration gradient distribution of silver is formed in the film thickness direction from low to high and then back to low. After deposition is completed, the film is cooled to obtain the heat insulation layer.

[0012] Further specifying, the flexible substrate material is PET, PC, PEN, TPU, PI or glass, and its thickness is 0.05mm-0.2mm.

[0013] Further specifying, the pretreatment includes dust removal, cleaning, and drying.

[0014] Furthermore, the inert gas is specified as pure argon.

[0015] Further specifying, the physical vapor deposition method used is radio frequency magnetron sputtering.

[0016] The deposition process was carried out at room temperature.

[0017] The background vacuum level of the pre-deposition chamber is 5 × 10⁻⁶. -4 Pa.

[0018] Further specified, the sputtering power of the ITO target is 160W, the sputtering pressure is 0.5Pa-1.3Pa, and the sputtering time is 42min.

[0019] Further specified, the sputtering power of the Ag target is 20W, and the pressure is 0.5Pa-1.3Pa.

[0020] Further specified, the intermittent deposition of Ag is achieved through time control, and the single deposition time first increases and then decreases along the film thickness direction to form an Ag concentration gradient structure. Ag target sputtering is initiated at 5 minutes after the start of deposition, followed by Ag target sputtering at intervals of 10s, 15s, 60s, 15s, 10s, and 5s every 5 minutes thereafter; or Ag sputtering is performed at 8, 13, 18, 23, 28, 33, and 38 minutes after the start of deposition, with single sputtering times of 5s, 15s, 20s, 60s, 20s, 15s, and 5s respectively; or Ag sputtering is performed at 8 minutes after the start of deposition. Ag sputtering was performed at 13 min, 18 min, 23 min, 28 min, 33 min, and 38 min, with single sputtering times of 5 s, 15 s, 20 s, 60 s, 20 s, 15 s, and 5 s, respectively; or Ag sputtering was performed at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, and 35 min after the start of deposition, with single sputtering times of 6 s, 12 s, 18 s, 60 s, 20 s, 15 s, and 5 s, respectively.

[0021] Compared with the prior art, the present invention has the following beneficial effects: In this invention, the ITO matrix forms a coating structure for the dispersed Ag nanoparticles, effectively inhibiting Ag oxidation and migration, and improving the chemical stability and lifespan of the film. The Ag nanoparticles are distributed in a gradient along the thickness direction, maintaining high transmittance in the visible light band while forming an effective reflective layer in the near-infrared band, thus balancing optical transparency and thermal insulation performance. The continuous distribution of the Ag nanoconductive network along the thickness direction helps reduce film resistance and enhance conductivity stability. The gradient structure avoids abrupt interfaces in traditional multilayer films, reducing interfacial stress concentration and improving the film's bending resistance and reliability on flexible substrates. This invention employs a one-step film formation and low-temperature magnetron sputtering process, simplifying the preparation process, reducing the risk of thermal damage to flexible polymer substrates (such as PET), and is suitable for large-area industrial production.

[0022] This invention can effectively overcome the problems of weak interfacial bonding, easy oxidation, and complex process of traditional ITO / Ag / ITO layered structures. It has the characteristics of simple process, low cost, excellent photoelectric performance and suitability for large-scale application.

[0023] For a deeper understanding of the features and technical content of this invention, please refer to the accompanying detailed description and drawings. It should be noted that the drawings are provided for illustrative purposes only and are not intended to limit the scope of the invention. Attached Figure Description

[0024] Figure 1This is a schematic diagram of the Ag concentration gradient in a transparent conductive thermal insulation layer based on Ag / ITO blend films with Ag gradient distribution. Figure 2 It is the transmittance of a transparent conductive heat insulation layer based on Ag / ITO blend film with Ag gradient distribution in the 200-2500nm electromagnetic wave band; Figure 3 It is the reflectivity of a transparent conductive heat insulation layer based on Ag / ITO blend film with Ag gradient distribution in the 200-2500nm electromagnetic wave band. Detailed Implementation

[0025] The present invention will be described in detail below with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but should not be considered as limiting the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0026] Example 1 The preparation method of Ag / ITO transparent conductive heat insulation layer based on Ag concentration gradient in this embodiment is carried out according to the following steps: Step 1: Select a PET film with a thickness of 0.2 mm, clean it with anhydrous ethanol and then blow it dry.

[0027] Step 2: Install the Ag target and ITO target on the target holder of the spherical magnetron sputtering equipment. Place the substrate in the magnetron sputtering equipment, turn on the DC power, turn off the magnetron sputtering chamber, and evacuate to a vacuum level of 5 × 10⁻⁶. -4 Pa; When the vacuum degree reaches 5×10 -4 When the pressure reaches Pa, open the argon cylinder, adjust the argon flow rate to 20 Sccm, and raise the cavity pressure to about 3 Pa to initiate plasma ignition. Then, adjust the stable working cavity pressure to 0.7 Pa. Start ITO target sputtering with the following parameters: ITO target power: 160W; sputtering time: 42min; working pressure: 0.7Pa. Ag target sputtering was initiated 5 minutes after the start of sputtering, with the following parameters: sputtering time: 5 s; Ag target power: 20 W; working pressure: 0.7 Pa. Subsequently, Ag target sputtering was initiated every 5 minutes for 10 s, 15 s, 60 s, 15 s, 10 s, and 5 s, respectively, with constant power and pressure. After deposition, the film was cooled and removed. The film was a light brown and transparent film with a visible light transmittance of 73%. The near-infrared reflectance was 66% in the 780 nm-1700 nm range and 53% in the 1700 nm-2500 nm range, showing significantly enhanced infrared reflectivity. The surface resistivity was 121 Ω / sq, lower than that of a pure ITO film.

[0028] Example 2 The difference between this embodiment and Embodiment 1 is that the intermittent sputtering time of Ag is set to 5s, 8s, 12s, 40s, 12s, 8s, and 5s. The other steps and parameters are the same as in Embodiment 1.

[0029] The thin film prepared in this embodiment has a visible light transmittance of 76% and a sheet resistivity of 145 (Ω / sq). In the near-infrared range, the reflectivity of the thin film is 61% in the 780 nm to 1700 nm band and 49% in the 1700 nm to 2500 nm band.

[0030] Compared with Example 1, the film in this example also has an Ag concentration gradient distribution structure in the thickness direction. Based on this structure, its visible light transmittance is slightly improved, while maintaining a low surface resistivity and good near-infrared reflectivity.

[0031] Example 3 The difference between this embodiment and Embodiment 1 is that the intermittent sputtering sequence of the Ag target is adjusted as follows: Ag sputtering is performed at 8 min, 13 min, 18 min, 23 min, 28 min, 33 min, and 38 min after the start of deposition, with single sputtering times of 5 s, 15 s, 20 s, 60 s, 20 s, 15 s, and 5 s, respectively. Other steps and parameters are the same as in Embodiment 1. The method in this embodiment shifts the peak position of the Ag concentration gradient towards the upper part of the film.

[0032] The thin film prepared in this embodiment has a visible light transmittance of 71% and a sheet resistivity of 121 Ω / sq. Its reflectance in the near-infrared band is 69% in the 780 nm to 1700 nm band and 56% in the 1700 nm to 2500 nm band. Therefore, the thin film obtained in this embodiment possesses both high visible light transmittance and good near-infrared heat insulation performance.

[0033] Example 4 The difference between this embodiment and Embodiment 1 is that the intermittent sputtering time of the Ag target adopts an asymmetric gradient distribution: Ag sputtering is performed at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min and 35 min after the start of deposition, with single sputtering times of 6 s, 12 s, 18 s, 60 s, 20 s, 15 s and 5 s respectively. Other steps and parameters are the same as in Embodiment 1.

[0034] The thin film prepared in this embodiment has a visible light transmittance of 72% and a sheet resistivity of 108 (Ω / sq). Its reflectance in the near-infrared band is 70% in the 780 nm to 1700 nm band and 57% in the 1700 nm to 2500 nm band. Therefore, the thin film obtained in this embodiment possesses both high visible light transmittance and good near-infrared heat insulation performance.

[0035] The specific embodiments of the present invention have been described in detail above. It should be noted that the present invention is not limited to the specific embodiments described above. Various modifications or alterations can be made by those skilled in the art without departing from the scope of protection defined by the claims, and all such modifications or alterations fall within the scope of the present invention.

Claims

1. An Ag / ITO transparent conductive thermal insulation layer based on an Ag concentration gradient, characterized in that, It includes a flexible substrate and an Ag / ITO composite layer disposed on the surface of the flexible substrate. The Ag / ITO composite layer uses indium tin oxide (ITO) as a continuous matrix, and silver (Ag) is dispersed in the form of nanoparticles and embedded in the ITO matrix. The Ag exhibits a concentration gradient distribution from low to high and then back to low in the film thickness direction.

2. The transparent conductive heat insulation layer according to claim 1, characterized in that, The Ag concentration gradient is a continuous gradient, a piecewise gradient, or an equivalent continuous gradient.

3. The transparent conductive heat insulation layer according to claim 1, characterized in that, The Ag nanoparticles are partially or completely coated with an ITO matrix.

4. The method for preparing the transparent conductive heat insulation layer according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Pre-treat the flexible substrate; Step 2: Under an inert gas protective atmosphere, indium tin oxide (ITO) is continuously deposited on the substrate surface treated in Step 1 using physical vapor deposition. During the deposition process, silver (Ag) is deposited intermittently. By controlling the intermittent deposition sequence of silver, a concentration gradient distribution of silver is formed in the film thickness direction from low to high and then back to low. After deposition is completed, the film is cooled to obtain the heat insulation layer.

5. The method according to claim 4, characterized in that, The flexible substrate material is PET, PC, PEN, TPU, PI or glass, and its thickness is 0.05mm-0.2mm.

6. The method according to claim 1, characterized in that, The pretreatment includes dust removal, cleaning, and drying.

7. The method according to claim 1, characterized in that, The inert gas is pure argon.

8. The method according to claim 1, characterized in that, The physical vapor deposition method used is radio frequency magnetron sputtering.

9. The method according to claim 8, characterized in that, The sputtering power of the ITO target is 160W, the sputtering power of the Ag target is 20W, and the pressure is 0.5Pa-1.3Pa.

10. The method according to claim 8, characterized in that, Ag target sputtering was initiated at 5 min after deposition began, followed by sputtering every 5 min for 10 s, 15 s, 60 s, 15 s, 10 s, and 5 s; or Ag sputtering was initiated at 8 min, 13 min, 18 min, 23 min, 28 min, 33 min, and 38 min after deposition began, with single sputtering times of 5 s, 15 s, 20 s, 60 s, 20 s, 15 s, and 5 s respectively; or Ag sputtering was initiated at 8 min after deposition began. Ag sputtering was performed at 13 min, 18 min, 23 min, 28 min, 33 min, and 38 min, with single sputtering times of 5 s, 15 s, 20 s, 60 s, 20 s, 15 s, and 5 s, respectively; or Ag sputtering was performed at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, and 35 min after the start of deposition, with single sputtering times of 6 s, 12 s, 18 s, 60 s, 20 s, 15 s, and 5 s, respectively.

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