Transparent conductive film and preparation process thereof

Abstract

The invention belongs to the field of photoelectric detector related materials, and discloses a transparent conductive film and a preparation process thereof.The transparent conductive film comprises a film substrate, a rare earth-transition metal composite layer and a passivation layer, and the film substrate, the rare earth-transition metal composite layer and the passivation layer are sequentially arranged from bottom to top; the rare earth-transition metal composite layer comprises a two-dimensional molybdenum oxide nanosheet doped with Ce and Yb; the passivation layer comprises aluminum oxide layers and titanium oxide layers, and the aluminum oxide layers and the titanium oxide layers are periodically and alternately arranged from bottom to top. A composite sol layer containing Ce < 3 + > and Yb < 3 + > double rare earth doped two-dimensional MoO2 nanosheets is spin-coated on the surface of the transparent conductive film, the near-infrared light absorption and carrier separation efficiency of the film are remarkably improved through f-f electron transition of rare earth elements and the interface modification effect of the nanosheets, and the photoelectric property of the transparent conductive film is optimized in combination with a special passivation layer structure.

Description

Technical Field

[0001] This invention belongs to the field of photodetector-related materials, specifically relating to a transparent conductive thin film and its preparation process. Background Technology

[0002] Transparent conductive films are core components of optoelectronic devices, and their performance directly affects the device's efficiency and reliability. Currently, indium tin oxide (ITO) is widely used due to its excellent conductivity and light transmittance; however, its high brittleness, scarcity of indium resources, and high cost limit its further development in the field of flexible electronics. Existing technologies optimize the optoelectronic properties of conductive films by doping zinc oxide (AZO) with aluminum or zinc gallium oxide (IGZO).

[0003] In existing technologies, after conductive thin film materials are deposited layer by layer, they are typically further processed using an annealing process. While traditional annealing or plasma treatment can improve the conductivity of the thin film, it often leads to a decrease in transmittance and limited improvement in carrier mobility. Furthermore, during high-temperature annealing, abnormal grain growth increases surface roughness and intensifies light scattering, while segregation of dopants further degrades the photoelectric properties of the conductive thin film. Summary of the Invention

[0004] In view of the defects and deficiencies of the existing technology, the present invention provides a transparent conductive film in two aspects: firstly, and secondly, a process for preparing the transparent conductive film.

[0005] In a first aspect, the present invention provides a transparent conductive thin film, comprising a thin film substrate, a rare earth-transition metal composite layer, and a passivation layer, wherein the thin film substrate, the rare earth-transition metal composite layer, and the passivation layer are arranged sequentially from bottom to top; the rare earth-transition metal composite layer comprises two-dimensional molybdenum oxide nanosheets doped with Ce and Yb; the passivation layer comprises an aluminum oxide layer and a titanium oxide layer, wherein the aluminum oxide layer and the titanium oxide layer are arranged in a periodic alternation from bottom to top.

[0006] Preferably, the film substrate comprises, from bottom to top, a polyurethane elastic layer, a modified PET / PI layer, and a SiO2 layer, wherein the thickness of the polyurethane elastic layer is 20-30 μm, the thickness of the modified PET / PI layer is 50-80 μm, and the thickness of the SiO2 layer is 0.5-1 μm.

[0007] Preferably, the thickness of the rare earth-transition metal composite layer is 80~120nm.

[0008] Preferably, the thickness of the alumina layer is 0.7~2nm, and the thickness of the titanium oxide layer is 1~3nm; the alternation period of the alumina layer and the titanium oxide layer is 8~10 cycles.

[0009] Secondly, the present invention provides a process for preparing a transparent conductive film, comprising the following steps: Step 1: Mix cerium nitrate, ytterbium nitrate, two-dimensional molybdenum oxide nanosheets, γ-aminopropyltriethoxysilane and ethanol to obtain a colloid. Coat the colloid onto the upper surface of the film substrate to obtain an intermediate product. Step 2: After vacuum drying the intermediate product, aluminum oxide and titanium oxide layers are sequentially and alternately deposited on the upper surface of the intermediate product to obtain the transparent conductive film.

[0010] Preferably, step 1 includes a two-dimensional molybdenum oxide nanosheet pretreatment process, in which the two-dimensional molybdenum oxide nanosheets are dispersed in a sodium citrate solution with pH=3.5~5, ultrasonically treated in a water bath at 60~90℃ for 1.5~3h, filtered, and the resulting solid material is placed in APTES and allowed to stand for 3h~4h.

[0011] Preferably, in step 1, the molar ratio of cerium nitrate, ytterbium nitrate, two-dimensional molybdenum oxide nanosheets and γ-aminopropyltriethoxysilane is 1:0.4~0.6:1.8~2.2:0.25~0.35.

[0012] Preferably, the two-dimensional molybdenum oxide nanosheets have a lateral dimension of 50~100nm and a thickness of 1.5~3nm.

[0013] Preferably, an annealing process is included between step 1 and step 2, in which the upper surface of the intermediate product is divided into a central region, a transition region, and an edge region from the inside out. The annealing temperature of the central region is 480~510℃ and the annealing time is 8~12s; the annealing temperature of the transition region is 250~310℃ and the annealing time is 35~45s; and the annealing temperature of the edge region is 180~210℃ and the annealing time is 45~55s.

[0014] Further preferred, the distance from the center point to the edge position on the upper surface of the intermediate product is set as R, the distance from the boundary line between the central region and the transition region to the center point is L1, and L1 is 30%R~35%R; the distance from the boundary line between the transition region and the edge region to the center point is L2, and L2 is 65%R~70%R.

[0015] Preferably, during the annealing process, an argon-hydrogen mixed gas flow is sprayed onto the surface of the intermediate product. The flow rate of the argon-hydrogen mixed gas flow is 2.5-5 L / min. As the reaction time progresses, the hydrogen content in the argon-hydrogen mixed gas flow increases at a constant rate from 4.5 vol% to 6 vol% to 12 vol% to 16 vol%.

[0016] Preferably, a carbon dioxide-assisted defect repair process is included between step 1 and step 2, in which the intermediate product is placed in a supercritical CO2 atmosphere of 13-16 MPa, heated to 70-90°C, and then a treatment liquid is injected into the reaction system. After standing for a certain period of time, the pressure is released in stages.

[0017] Preferably, the treatment solution is a mixed solution of trifluoroacetic acid and HMDS, wherein the concentration of trifluoroacetic acid in the treatment solution is 0.3~1 vol%, and the concentration of HMDS in the treatment solution is 0.05~0.5 vol%.

[0018] Preferably, the staged pressure relief includes two stages of pressure relief. In the first stage of pressure relief, the pressure relief rate is 0.2~0.4MPa / min; in the second stage of pressure relief, the pressure relief rate is 0.7~1.2MPa / min; and the critical point between the first stage and the second stage of pressure relief is 8~12MPa.

[0019] Preferably, in step 2, during deposition, the power is 280~310W, the pulse frequency is 480~520Hz, and the temperature of the intermediate product is 140~160℃.

[0020] Preferably, in step 2, an argon ion bombardment process is inserted after five alternating deposition cycles.

[0021] Preferably, the method further includes step 3, immersing the conductive film in a passivation solution containing sodium thiosulfate and sodium dodecyl sulfate, applying an electric field of 8~10V / cm for electrochemical passivation, with a passivation time of 4~7min, followed by drying with nitrogen gas.

[0022] Preferably, the concentration of sodium thiosulfate in the passivation solution is 0.01~0.03M, and the concentration of sodium dodecyl sulfate in the passivation solution is 0.003~0.006M.

[0023] Compared with the prior art, one or more technical solutions provided by the present invention have at least one of the following beneficial effects: (1) Spin-coating Ce-containing material onto the surface of a transparent conductive film 3+ Yb 3+ The composite sol layer of dual rare earth doping and two-dimensional MoO2 nanosheets significantly improves the near-infrared light absorption and carrier separation efficiency of the thin film through the ff electronic transition of rare earth elements and the interface modification effect of nanosheets. Combined with a special passivation layer structure, it optimizes the optoelectronic performance of transparent conductive films.

[0024] (2) Near-infrared laser partition scanning is used in combination with argon-hydrogen mixed atmosphere control to achieve precise gradient control of film surface temperature and optimize grain growth and dopant element distribution.

[0025] (3) Inject a treatment solution containing trifluoroacetic acid and HMDS into a supercritical CO2 environment. Utilize the high diffusivity and selective etching effect of supercritical fluid to efficiently remove grain boundary oxygen vacancies and impurities.

[0026] (4) Alternating deposition of alumina and titanium oxide layers, and inserting an argon ion bombardment process during the alternating deposition process, can enhance the bonding strength between the film layers. Detailed Implementation

[0027] The present invention provides the following specific technical solutions.

[0028] In a first aspect, the present invention provides a transparent conductive thin film, comprising a thin film substrate, a rare earth-transition metal composite layer, and a passivation layer, wherein the thin film substrate, the rare earth-transition metal composite layer, and the passivation layer are arranged sequentially from bottom to top; the rare earth-transition metal composite layer comprises two-dimensional molybdenum oxide nanosheets doped with Ce and Yb; the passivation layer comprises an aluminum oxide layer and a titanium oxide layer, wherein the aluminum oxide layer and the titanium oxide layer are arranged in a periodic alternation from bottom to top.

[0029] The inventors discovered through research that spin-coating Ce-containing materials onto the surface of a transparent conductive film... 3+ Yb 3+ The composite sol layer of dual rare earth doping and two-dimensional MoO2 nanosheets significantly improves the near-infrared light absorption and carrier separation efficiency of the thin film through the ff electronic transition of rare earth elements and the interface modification effect of nanosheets. Combined with a special passivation layer structure, it optimizes the optoelectronic performance of transparent conductive films.

[0030] Preferably, the film substrate comprises, from bottom to top, a polyurethane elastic layer, a modified PET / PI layer, and a SiO2 layer, wherein the thickness of the polyurethane elastic layer is 20-30 μm, the thickness of the modified PET / PI layer is 50-80 μm, and the thickness of the SiO2 layer is 0.5-1 μm.

[0031] In practical applications, polyester-polyimide composite material systems achieved through blending, filling, or lamination techniques typically employ multilayer composites (such as PET film + PI coating) or blend modification (PI nanofiber reinforced PET matrix). In a specific embodiment of this invention, the film matrix used consists of a 25 μm polyurethane elastic layer, a 65 μm modified PET / PI layer, and a 0.8 μm SiO2 layer from bottom to top. The film matrix provided by this invention can also be used alone as a transparent conductive film. Other materials used to prepare transparent conductive films can also be used as the film matrix, selected according to actual needs.

[0032] Preferably, the thickness of the rare earth-transition metal composite layer is 80~120nm.

[0033] Preferably, the thickness of the alumina layer is 0.7~2nm, and the thickness of the titanium oxide layer is 1~3nm; the alternation period of the alumina layer and the titanium oxide layer is 8~10 cycles.

[0034] Secondly, the present invention provides a process for preparing a transparent conductive film, comprising the following steps: Step 1: Mix cerium nitrate, ytterbium nitrate, two-dimensional molybdenum oxide nanosheets, γ-aminopropyltriethoxysilane and ethanol to obtain a colloid. Coat the colloid onto the upper surface of the film substrate to obtain an intermediate product. Step 2: After vacuum drying the intermediate product, aluminum oxide and titanium oxide layers are sequentially and alternately deposited on the upper surface of the intermediate product to obtain the transparent conductive film.

[0035] Preferably, step 1 includes a two-dimensional molybdenum oxide nanosheet pretreatment process, in which the two-dimensional molybdenum oxide nanosheets are dispersed in a sodium citrate solution with pH=3.5~5, ultrasonically treated in a water bath at 60~90℃ for 1.5~3h, filtered, and the resulting solid material is placed in APTES and allowed to stand for 3h~4h.

[0036] Through research, the inventors discovered that by improving the dispersibility of two-dimensional molybdenum oxide nanosheets with sodium citrate and regulating their surface charge, and then silanizing and coupling the two-dimensional molybdenum oxide nanosheets with APTES, surface functionalization, improved organic compatibility, and enhanced chemical stability of the nanosheets can be achieved. Through the pretreatment of two-dimensional molybdenum oxide nanosheets, molybdenum oxide nanosheets with good dispersibility, amino-active sites on the surface, and both inorganic properties and organic compatibility can be prepared.

[0037] Preferably, in step 1, the molar ratio of cerium nitrate, ytterbium nitrate, two-dimensional molybdenum oxide nanosheets and γ-aminopropyltriethoxysilane is 1:0.4~0.6:1.8~2.2:0.25~0.35.

[0038] Preferably, the two-dimensional molybdenum oxide nanosheets have a lateral dimension of 50~100nm and a thickness of 1.5~3nm.

[0039] Preferably, an annealing process is included between step 1 and step 2, in which the upper surface of the intermediate product is divided into a central region, a transition region, and an edge region from the inside out. The annealing temperature of the central region is 480~510℃ and the annealing time is 8~12s; the annealing temperature of the transition region is 250~310℃ and the annealing time is 35~45s; and the annealing temperature of the edge region is 180~210℃ and the annealing time is 45~55s.

[0040] In practical applications, laser scanning equipment is used to perform zoned annealing on the upper surface of the intermediate product. During annealing, the laser head first scans the central region of the intermediate product. After the central region is annealed, the laser probe moves to the transition region for surface scanning annealing. After the transition region is annealed, the laser probe moves to the edge region for surface scanning annealing. The annealing temperature is adjusted by regulating the laser power density.

[0041] Further preferred, the distance from the center point to the edge position on the upper surface of the intermediate product is set as R, the distance from the boundary line between the central region and the transition region to the center point is L1, and L1 is 30%R~35%R; the distance from the boundary line between the transition region and the edge region to the center point is L2, and L2 is 65%R~70%R.

[0042] Preferably, during the annealing process, an argon-hydrogen mixed gas flow is sprayed onto the surface of the intermediate product. The flow rate of the argon-hydrogen mixed gas flow is 2.5~5 L / min. As the reaction time progresses, the hydrogen content in the argon-hydrogen mixed gas flow increases at a constant rate from 4.5 vol%~6 vol% to 12 vol%~16 vol%.

[0043] Through research, the inventors discovered that by employing near-infrared laser zonal scanning combined with argon-hydrogen mixed atmosphere control, precise gradient control of the thin film surface temperature can be achieved, optimizing grain growth and dopant element distribution. During annealing, hydrogen acts as a reducing agent, removing trace oxygen impurities from the rare-earth composite layer and passivation layer surface, preventing conductivity degradation caused by high-temperature oxidation. Furthermore, hydrogen promotes the condensation of γ-aminopropyltriethoxysilane (APTES) with silanol groups (Si-OH) on the nanosheet surface, enhancing interlayer covalent bonding and suppressing bending and delamination. Argon (Ar) acts as an inert carrier to dilute the hydrogen concentration, preventing excessive hydrogen atom penetration that could lead to lattice expansion or hydrogen embrittlement. Adjusting the hydrogen ratio allows for precise control of oxygen vacancy concentration, optimizing carrier migration paths.

[0044] Preferably, a carbon dioxide-assisted defect repair process is included between step 1 and step 2, in which the intermediate product is placed in a supercritical CO2 atmosphere of 13-16 MPa, heated to 70-90°C, and then a treatment liquid is injected into the reaction system. After standing for a certain period of time, the pressure is released in stages.

[0045] Preferably, the treatment solution is a mixed solution of trifluoroacetic acid and HMDS, wherein the concentration of trifluoroacetic acid in the treatment solution is 0.3~1 vol%, and the concentration of HMDS in the treatment solution is 0.05~0.5 vol%.

[0046] Through research, the inventors discovered that injecting a treatment solution containing trifluoroacetic acid and HMDS into a supercritical CO2 environment can efficiently remove grain boundary oxygen vacancies and impurities by utilizing the high diffusivity and selective etching effect of supercritical fluids.

[0047] In practical applications, the solvent for the treatment solution is an anhydrous fluorinated solvent. The solvent can be a perfluorocarbon solvent, a hydrofluoroether solvent, or a fluoroaromatic solvent. Specifically, it can be any one or more of perfluorohexane, HFE-7100, and trifluorotoluene.

[0048] Preferably, the staged pressure relief includes two stages of pressure relief. In the first stage of pressure relief, the pressure relief rate is 0.2~0.4MPa / min; in the second stage of pressure relief, the pressure relief rate is 0.7~1.2MPa / min; and the critical point between the first stage and the second stage of pressure relief is 8~12MPa.

[0049] Through research, the inventors discovered that by using two-stage pressure relief and ultrasonic-assisted desorption, wrinkling or damage to the film surface can be avoided.

[0050] Preferably, in step 2, during deposition, the power is 280~310W, the pulse frequency is 480~520Hz, and the temperature of the intermediate product is 140~160℃.

[0051] Preferably, in step 2, an argon ion bombardment process is inserted after five alternating deposition cycles.

[0052] The inventors discovered through research that inserting an argon ion bombardment process improves the bonding strength between the passivation layer and the substrate.

[0053] Preferably, the method further includes step 3, immersing the conductive film in a passivation solution containing sodium thiosulfate and sodium dodecyl sulfate, applying an electric field of 8~10V / cm for electrochemical passivation, with a passivation time of 4~7min, followed by drying with nitrogen gas.

[0054] Preferably, the concentration of sodium thiosulfate in the passivation solution is 0.01~0.03M, and the concentration of sodium dodecyl sulfate in the passivation solution is 0.003~0.006M.

[0055] In practical applications, the passivation solution disclosed in reference patent CN105755456A is modified by adding sodium thiosulfate and sodium dodecyl sulfate. The inventors discovered that immersing the film in a solution containing sodium thiosulfate and sodium dodecyl sulfate, and applying an electric field for electrochemical passivation, further reduces the surface defect state density and improves the film's mechanical stability.

[0056] To make the technical problems, technical solutions and technical advantages of the present invention clearer, a detailed description will be given below with reference to specific examples. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0057] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0058] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0059] Example 1: A method for preparing a transparent conductive thin film includes the following steps: Step 1: Place the two-dimensional molybdenum oxide nanosheets in a sodium citrate solution with pH=4 and sonicate them in a water bath at 75°C for 2 hours.

[0060] Step 2: Cerium nitrate, ytterbium nitrate, the two-dimensional molybdenum oxide nanosheets obtained in Step 1, and γ-aminopropyltriethoxysilane (APTES) are mixed in a molar ratio of 1:0.5:2:0.3. The mixture is then poured into 100 mL of ethanol solvent, magnetically stirred for 2 hours, and ultrasonically dispersed for 30 min to obtain a uniform sol.

[0061] Step 3: The sol is dropped onto the surface of the film substrate and spin-coated at 3000 rpm for 30 seconds to form a uniform coating with a thickness of about 150 nm. After spin-coating, the film is placed on an 80°C hot plate for pre-baking for 5 minutes to allow the sol to initially solidify and obtain the intermediate product.

[0062] Step 4: Using an 808nm near-infrared laser, the surface temperature of the intermediate product was monitored in real time using an infrared thermal imager. The annealing temperature of the central region of the intermediate product was 500℃, and the annealing time was 10s; the annealing temperature of the transition region was 300℃, and the annealing time was 30s; the annealing temperature of the edge region was 200℃, and the annealing time was 60s. During the annealing process, an argon-hydrogen mixed gas flow was injected into the film surface at a total flow rate of 5L / min. As annealing progressed, the hydrogen proportion was uniformly increased from 5 vol% to 15 vol%. On the upper surface of the intermediate product, the distance L1 from the boundary line between the central region and the transition region to the center point was 33%R; the distance L2 from the boundary line between the transition region and the edge region to the center point was 67%R.

[0063] Step 5: Then, the intermediate product after step 3 is placed into a supercritical reactor, sealed, and CO2 is introduced to a pressure of 15 MPa and heated to 80°C. Then, a treatment solution containing 0.5 vol% trifluoroacetic acid and 0.1 vol% hexamethyldisilazane (HMDS) is injected into the supercritical reactor and kept for 30 min.

[0064] Step 6: Use two-stage depressurization. Depressurize to 10 MPa at a rate of 0.3 MPa / min; then depressurize to atmospheric pressure at a rate of 1 MPa / min. After depressurization, purge the membrane surface with high-purity nitrogen for 10 min to remove residual reagents.

[0065] Step 7: Place the intermediate product from Step 5 into a microwave plasma-assisted atomic layer deposition (PE-ALD) apparatus, setting the microwave power to 300W, pulse frequency to 500Hz, and substrate temperature to 150℃. Al₂O₃ (0.8nm) and TiO₂ (1.2nm) are deposited alternately for a total of 10 cycles. After 5 cycles, argon ions are inserted for bombardment at an energy of 50eV for 5s, yielding a transparent conductive film.

[0066] Step 8: Immerse the transparent conductive film obtained in Step 6 in a passivation solution containing 0.01M sodium thiosulfate and 0.005M sodium dodecyl sulfate, apply an electric field of 10V / cm, treat for 5 minutes, remove and dry with nitrogen gas to complete the treatment of the transparent conductive film.

[0067] Example 2: A method for preparing a transparent conductive thin film includes the following steps: Step 1: Place the two-dimensional molybdenum oxide nanosheets in a sodium citrate solution with pH=3.5 and sonicate them in a water bath at 60°C for 1.5 h.

[0068] Step 2: Cerium nitrate, ytterbium nitrate, two-dimensional molybdenum oxide nanosheets and γ-aminopropyltriethoxysilane (APTES) are mixed in a molar ratio of 1:0.4:1.8:0.25. The mixture is then poured into 90 mL of ethanol solvent, magnetically stirred for 2 hours, and ultrasonically dispersed for 30 min to obtain a uniform sol.

[0069] Step 3: The sol is dropped onto the surface of the film substrate and spin-coated at 3000 rpm for 30 seconds to form a uniform coating with a thickness of about 130 nm. After spin-coating, the film is placed on an 80°C hot plate for pre-baking for 5 minutes to allow the sol to initially solidify and obtain the intermediate product.

[0070] Step 4: Using an 808nm near-infrared laser, the surface temperature of the intermediate product was monitored in real time using an infrared thermal imager. The annealing temperature of the central region of the intermediate product was 480℃, and the annealing time was 8s; the annealing temperature of the transition region was 250℃, and the annealing time was 35s; the annealing temperature of the edge region was 180℃, and the annealing time was 45s. During the annealing process, an argon-hydrogen mixed gas flow was injected into the film surface at a total flow rate of 2.5L / min. As annealing progressed, the hydrogen content increased uniformly from 4.5 vol% to 15 vol%. On the upper surface of the intermediate product, the distance L1 from the boundary line between the central region and the transition region to the center point was 30%R; the distance L2 from the boundary line between the transition region and the edge region to the center point was 70%R.

[0071] Step 5: Then, the intermediate product after step 3 is placed into a supercritical reactor, sealed, and CO2 is introduced to a pressure of 13 MPa and heated to 70°C. Then, a treatment solution containing 0.3 vol% trifluoroacetic acid and 0.05 vol% hexamethyldisilazane (HMDS) is injected into the supercritical reactor and kept for 30 min.

[0072] Step 6: Use two-stage depressurization. Depressurize to 8 MPa at a rate of 0.2 MPa / min; then depressurize to atmospheric pressure at a rate of 0.7 MPa / min. After depressurization, purge the membrane surface with high-purity nitrogen for 7 min to remove residual reagents.

[0073] Step 7: Place the intermediate product from Step 5 into a microwave plasma-assisted atomic layer deposition (PE-ALD) apparatus, setting the microwave power to 280W, the pulse frequency to 480Hz, and the substrate temperature to 140℃. Al₂O₃ (0.7nm) and TiO₂ (1nm) are deposited alternately for a total of 8 alternating deposition cycles. After 4 deposition cycles, argon ions are inserted for bombardment at an energy of 50eV for 5s, yielding a transparent conductive film.

[0074] Step 8: Immerse the transparent conductive film obtained in Step 6 in a passivation solution containing 0.01M sodium thiosulfate and 0.003M sodium dodecyl sulfate, apply an electric field of 8V / cm, treat for 4 minutes, remove and dry with nitrogen gas to complete the treatment of the transparent conductive film.

[0075] Example 3: A method for preparing a transparent conductive thin film includes the following steps: Step 1: Place the two-dimensional molybdenum oxide nanosheets in a sodium citrate solution at pH=5 and sonicate them in a water bath at 90°C for 3 hours.

[0076] Step 2: Cerium nitrate, ytterbium nitrate, two-dimensional molybdenum oxide nanosheets and γ-aminopropyltriethoxysilane (APTES) are mixed in a molar ratio of 1:0.6:2.2:0.35. The mixture is then poured into 120 volumes of ethanol solvent, magnetically stirred for 2 hours, and ultrasonically dispersed for 30 minutes to obtain a uniform sol.

[0077] Step 3: The sol is dropped onto the surface of the film substrate and spin-coated at 3000 rpm for 30 seconds to form a uniform coating with a thickness of about 180 nm. After spin-coating, the film is placed on an 80°C hot plate for pre-baking for 5 minutes to allow the sol to initially solidify and obtain an intermediate product.

[0078] Step 4: Using an 808nm near-infrared laser, the surface temperature of the intermediate product was monitored in real time using an infrared thermal imager. The annealing temperature of the central region of the intermediate product was 510℃, and the annealing time was 12s; the annealing temperature of the transition region was 310℃, and the annealing time was 45s; the annealing temperature of the edge region was 210℃, and the annealing time was 55s. During the annealing process, an argon-hydrogen mixed gas flow was injected into the film surface at a total flow rate of 5L / min. As annealing progressed, the hydrogen proportion increased uniformly from 6 vol% to 16 vol%. On the upper surface of the intermediate product, the distance L1 from the boundary line between the central region and the transition region to the center point was 35%R; the distance L2 from the boundary line between the transition region and the edge region to the center point was 65%R.

[0079] Step 5: Then, the intermediate product after step 3 is placed into a supercritical reactor, sealed, and CO2 is introduced to a pressure of 16 MPa and heated to 90°C. Then, a treatment solution containing 1 vol% trifluoroacetic acid and 0.5 vol% hexamethyldisilazane (HMDS) is injected into the supercritical reactor and kept for 30 min.

[0080] Step 6: Use two-stage depressurization. Depressurize to 12 MPa at a depressurization rate of 0.4 MPa / min; then depressurize to atmospheric pressure at a depressurization rate of 1.2 MPa / min. After depressurization, purge the membrane surface with high-purity nitrogen for 12 min to remove residual reagents.

[0081] Step 7: Place the intermediate product from Step 5 into a microwave plasma-assisted atomic layer deposition (PE-ALD) apparatus, setting the microwave power to 310W, pulse frequency to 520Hz, and substrate temperature to 160℃. Al₂O₃ (2nm) and TiO₂ (3nm) are deposited alternately for a total of 12 cycles. After 6 cycles of deposition, argon ions are inserted for bombardment at an energy of 50eV for 5s, yielding a transparent conductive film.

[0082] Step 8: Immerse the transparent conductive film obtained in Step 6 in a passivation solution of 0.03M sodium thiosulfate and 0.006M sodium dodecyl sulfate, apply an electric field of 10V / cm, treat for 7 minutes, remove and dry with nitrogen gas to complete the treatment of the transparent conductive film.

[0083] Comparative Example 1: A method for preparing a transparent conductive film differs from Example 1 in that, in step 4, the intermediate product is placed in a tube furnace and heated to 500°C at 5°C / min under an argon atmosphere, held at that temperature for 30 minutes, and then allowed to cool naturally.

[0084] Comparative Example 2: A method for preparing a transparent conductive film differs from Example 1 in that, in step 7, the intermediate product processed in step 6 is placed in a microwave plasma-assisted atomic layer deposition (PE-ALD) device, with a microwave power of 300W, a pulse frequency of 500Hz, and a substrate temperature of 150℃, to deposit a 10nm Al2O3 layer, thereby obtaining a transparent conductive film.

[0085] Comparative Example 3: A method for preparing a transparent conductive film differs from Example 1 in that, in step 7, the intermediate product processed in step 6 is placed in a microwave plasma-assisted atomic layer deposition (PE-ALD) device, with a microwave power of 300W, a pulse frequency of 500Hz, and a substrate temperature of 150℃, to deposit a 10nm TiO2 layer, thereby obtaining a transparent conductive film.

[0086] Comparative Example 4: A method for preparing a transparent conductive thin film includes the following steps: Step 1: Mix indium nitrate and tin nitrate at a molar ratio of 9:1, then pour the mixture into 100 mL of ethanol solvent, stir magnetically for 2 hours, and ultrasonically disperse for 30 min to obtain a uniform sol; the subsequent steps are the same as steps 3 to 8 of Example 1.

[0087] The sheet resistance, transmittance, carrier concentration, carrier mobility, and flexural strength of the transparent conductive films prepared in Examples 1-3 and Comparative Examples 1-4 were tested. The MIT flexural strength test was used to test the flexural strength, with a bending angle of 135°, a tension of 1N, and a frequency of 1-2Hz. The endpoint was determined as the conductive layer breaking. The test data are shown in Table 1.

[0088] Table 1. Properties of the transparent conductive films and film substrates prepared in Examples 1-3 and Comparative Examples 1-4 As shown in Table 1, the present invention significantly improves the photoelectric performance of transparent conductive films through the synergistic effect of photothermal gradient annealing, supercritical CO2 defect repair and microwave plasma passivation. The transparent conductive film prepared in Example 1 has the lowest sheet resistance, the highest transmittance, and both carrier concentration and mobility are improved to a certain extent. It also has excellent bending resistance, which is superior to the prior art and is beneficial for the preparation of high-performance flexible optoelectronic devices.

[0089] Comparing the data of Example 1 and Comparative Example 1, it can be seen that the special annealing process provided by the present invention can optimize grain growth and the distribution of doped elements, thereby improving the wire performance and photoelectric performance of the transparent conductive film.

[0090] Comparing the data of Example 1 and Comparative Example 2, it can be seen that the periodically alternating alumina layer and titanium oxide layer provided by the present invention can disperse the film stress, and the alternating structure can form an optical interference structure, which can significantly reduce the resistance of the transparent conductive film, increase the carrier concentration and mobility, increase its transmittance, and improve the photoelectric performance.

[0091] Comparing the data of Example 1 and Comparative Example 3, single titanium dioxide has low bending resistance, high hardness but high brittleness, resulting in lower transmittance of the passivation layer prepared in Comparative Example 3 compared to the periodic alternating structure of Example 1.

[0092] Comparing the data of Example 1 and Comparative Example 4, it can be seen that changing the rare earth-transition metal composite layer material has little effect on its optical performance and bending resistance, but has some effect on its electrical performance. The composite layer obtained by using cerium nitrate and ytterbium nitrate in Example 1 has lower sheet resistance, higher carrier concentration, and higher mobility.

[0093] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope of the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A transparent conductive film, characterized by, The transparent conductive film comprises a film substrate, a rare earth-transition metal composite layer and a passivation layer arranged in sequence from bottom to top; the rare earth-transition metal composite layer comprises two-dimensional molybdenum oxide nanosheets doped with Ce and Yb; the passivation layer comprises an aluminum oxide layer and a titanium oxide layer, and the aluminum oxide layer and the titanium oxide layer are arranged in a periodic alternating manner from bottom to top.

2. The transparent conductive film according to claim 1, wherein The film substrate comprises a polyurethane elastic layer, a modified PET / PI layer and a SiO2 layer arranged in sequence from bottom to top, the thickness of the polyurethane elastic layer is 20-30 μm, the thickness of the modified PET / PI layer is 50-80 μm, and the thickness of the SiO2 layer is 0.5-1 μm; The thickness of the rare earth-transition metal composite layer is 80-120 nm; The thickness of the aluminum oxide layer is 0.7-2 nm, and the thickness of the titanium oxide layer is 1-3 nm; and the alternating period of the aluminum oxide layer and the titanium oxide layer is 8-10 periods.

3. The method of producing a transparent conductive film according to any one of claims 1 to 2, wherein The method comprises the following steps: In step 1, Ce(NO3)4, Yb(NO3)3, two-dimensional molybdenum oxide nanosheets, γ-aminopropyltriethoxysilane and ethanol are mixed to obtain a colloid, and the colloid is coated on the upper surface of the film substrate to obtain an intermediate product; In step 2, after vacuum drying the intermediate product, the aluminum oxide layer and the titanium oxide layer are sequentially and alternately deposited on the upper surface of the intermediate product to obtain the transparent conductive film.

4. The transparent conductive film according to claim 3, wherein In step 1, the molar ratio of Ce(NO3)4, Yb(NO3)3, two-dimensional molybdenum oxide nanosheets and γ-aminopropyltriethoxysilane is 1:0.4-0.6:1.8-2.2:0.25-0.35; the lateral size of the two-dimensional molybdenum oxide nanosheets is 50-100 nm, and the thickness of the two-dimensional molybdenum oxide nanosheets is 1.5-3 nm.

5. The method of producing a transparent conductive film according to claim 3, wherein The annealing process is further included between step 1 and step 2, the radial direction is set from the center point to the edge position of the upper surface of the intermediate product, and the radial direction sequentially comprises a center area, a transition area and an edge area from inside to outside, the annealing temperature of the center area is 480-510 ℃, and the annealing time is 8-12 s; the annealing temperature of the transition area is 250-310 ℃, and the annealing time is 35-45 s; the annealing temperature of the edge area is 180-210 ℃, and the annealing time is 45-55 s.

6. The method of producing a transparent conductive film according to claim 5, wherein The distance from the center point to the edge position of the upper surface of the intermediate product is set as R, the distance from the boundary line between the center area and the transition area to the center point is L1, and L1 is 30% R-35% R; the distance from the boundary line between the transition area and the edge area to the center point is L2, and L2 is 65% R-70% R; During the annealing process, an argon-hydrogen mixed gas stream is sprayed to the surface of the intermediate product, the flow rate of the argon-hydrogen mixed gas stream is 2.5-5 L / min, and the hydrogen content in the argon-hydrogen mixed gas stream is uniformly increased from 4.5 vol%-6 vol% to 12 vol%-16 vol% with the lapse of reaction time.

7. The method of producing a transparent conductive film according to claim 3, wherein The carbon dioxide assisted defect repair process is further included between step 1 and step 2, the intermediate product is placed in a supercritical CO2 atmosphere with a pressure of 13-16 MPa, heated to 70-90 ℃, then a treatment liquid is injected into the reaction system, and after standing for a certain period of time, the pressure is released in stages.

8. The method of producing a transparent conductive film according to claim 7, wherein The processing liquid is a mixed solution of trifluoroacetic acid and HMDS, the concentration of trifluoroacetic acid in the processing liquid is 0.3-1 vol%, and the concentration of HMDS in the processing liquid is 0.05-0.5 vol%. The staged pressure relief includes two-stage pressure relief, in the first-stage pressure relief, the pressure relief rate is 0.2-0.4 MPa / min, in the second-stage pressure relief, the pressure relief rate is 0.7-1.2 MPa / min, and the critical point of the first-stage pressure relief and the second-stage pressure relief is 8-12 MPa.

9. The method of producing a transparent conductive film according to claim 3, wherein In step 2, during deposition, the power is 280-310 W, the pulse frequency is 480-520 Hz, and the temperature of the intermediate product is 140-160℃; after 5 cycles of alternating deposition, an argon ion bombardment process is inserted.

10. The method of producing a transparent conductive film according to claim 3, wherein The method further comprises step 3: soaking the conductive film in a passivation solution containing sodium thiosulfate and sodium dodecyl sulfate, performing electrochemical passivation by applying an electric field of 8-10 V / cm, and then blowing dry with nitrogen; the concentration of sodium thiosulfate in the passivation solution is 0.01-0.03 M, and the concentration of sodium dodecyl sulfate in the passivation solution is 0.003-0.006 M. The processing liquid is a mixed solution of trifluoroacetic acid and HMDS, the concentration of trifluoroacetic acid in the processing liquid is 0.3-1 vol%, and the concentration of HMDS in the processing liquid is 0.05-0.5 vol%. The staged pressure relief includes two-stage pressure relief, in the first-stage pressure relief, the pressure relief rate is 0.2-0.4 MPa / min, in the second-stage pressure relief, the pressure relief rate is 0.7-1.2 MPa / min, and the critical point of the first-stage pressure relief and the second-stage pressure relief is 8-12 MPa. In step 2, during deposition, the power is 280-310 W, the pulse frequency is 480-520 Hz, and the temperature of the intermediate product is 140-160℃; after 5 cycles of alternating deposition, an argon ion bombardment process is inserted. The method further comprises step 3: soaking the conductive film in a passivation solution containing sodium thiosulfate and sodium dodecyl sulfate, performing electrochemical passivation by applying an electric field of 8-10 V / cm, and then blowing dry with nitrogen; the concentration of sodium thiosulfate in the passivation solution is 0.01-0.03 M, and the concentration of sodium dodecyl sulfate in the passivation solution is 0.003-0.006 M.

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