Flexible photoelectric sensor and preparation method thereof

Abstract

The invention relates to a flexible photoelectric sensor and a preparation method thereof, and the method comprises the following steps: S1, carrying out the oxygen plasma treatment of the upper surface of a transparent flexible substrate, then carrying out the spin coating and film forming in a middle region through an MXene thin layer dispersion liquid, carrying out the annealing treatment after heating, obtaining an anode layer, and reserving a sealing region at the periphery of the anode layer on the substrate; s2, sequentially forming a hole transport layer, a photoelectric active layer, an electron transport layer and a cathode layer on the upper surface of the anode layer from bottom to top, and then forming a flexible sealing layer for packaging each functional layer; and S3, forming a flexible light-transmitting hydrophobic layer on the lower surface of the substrate. The invention has the advantages that the flexible sealing layer is arranged, so that each functional layer is isolated from the outside and can be used in a high-humidity environment; the flexible light-transmitting hydrophobic layer is arranged, so that light transmission is high, dirt sticking or fogging is not prone to occurring, and the cleaning frequency is low; the hole transport layer is composed of a binary doped and layered cured PEDOT: PSS conductive polymer, the light transmission is good, the conductivity is strong, and the performance of the sensor can be significantly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and in particular relates to a flexible photoelectric sensor and a preparation method thereof. Background Art

[0002] Photoelectric sensors are sensors that use photoelectric elements as detection elements and can convert light signals into electrical signals. Flexible photoelectric sensors are one of the photoelectric sensors with the broadest application prospects at present. They are used in biomedicine, wearable devices, environmental monitoring and other fields. In the biomedical field, flexible photoelectric sensors can be used to monitor patients' physiological parameters in real time, such as heart rate, blood pressure, blood sugar, etc.; in the field of wearable devices, flexible photoelectric sensors can be used to manufacture smart bracelets, smart watches and other equipment to realize functions such as health monitoring and motion monitoring; in the field of environmental monitoring, flexible integrated photoelectric sensors can be used to monitor environmental parameters such as air quality and water quality in real time, providing strong support for environmental protection.

[0003] Flexible photoelectric sensors have the advantages of easy bending, long detection distance, short response time, high resolution and color discrimination, but they also have the following disadvantages: easy to break, relatively short durability and lifespan; greatly affected by the environment, sensitive to temperature and humidity, especially in high humidity environments, performance will quickly drop sharply or even become unusable; the membrane surface is prone to dust, dirt and mist, and the light transmittance is insufficient, affecting the normal use of the photoelectric sensor. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a flexible photoelectric sensor and a preparation method thereof, aiming to overcome the above-mentioned deficiencies existing in the prior art to at least a certain extent.

[0005] The technical solution of the present invention to solve the above technical problem is as follows: A method for preparing a flexible photoelectric sensor, comprising the following steps:

[0006] S1. The upper surface of the transparent flexible substrate is subjected to oxygen plasma treatment. After the treatment, a MXene thin layer dispersion is used to spin-coat a film in the middle area of ​​the upper surface, and then heated and annealed to obtain an anode layer. The transparent flexible substrate is provided with a sealing area around the anode layer;

[0007] S2. firstly, forming a hole transport layer, a photoelectric active layer, an electron transport layer and a cathode layer on the upper surface of the anode layer from bottom to top, and then forming a flexible sealing layer covering the cathode layer and the sealing area and sealing the anode layer, the hole transport layer, the photoelectric active layer, the electron transport layer and the cathode layer from all sides;

[0008] S3. Plasma treatment is performed on the lower surface of the transparent flexible substrate. After the treatment is completed, a flexible light-transmitting hydrophobic layer is formed on the lower surface of the transparent flexible substrate.

[0009] On the basis of the above technical solutions, the present invention may further have the following specific options or more preferred options.

[0010] Specifically, the transparent flexible substrate in S1 is a PET film, the MXene thin layer dispersion is a titanium carbide thin layer dispersion with a concentration of 2.5-5.5 mg / mL, and the width of the sealing area is 3-8 mm.

[0011] Specifically, the hole transport layer is a PEDOT:PSS conductive polymer that is binary doped with N,N-dimethylformamide and ethylene glycol and cured after layered coating.

[0012] Specifically, when the hole transport layer is formed, a PEDOT:PSS aqueous solution with a solid content of 1.2-2.0% is first divided into two parts, one of which is mixed with 1-1.5% by weight of N,N-dimethylformamide to obtain solution one, and the other is mixed with 2.5-3.5% by weight of ethylene glycol to obtain solution two. Solution one is first used to coat the upper surface of the anode layer to form a film, placed in a vacuum drying oven at 100-120°C, baked for 3-5 minutes, taken out and naturally cooled to room temperature, first used oxygen plasma to treat the newly formed film layer for 2-3 minutes, and then solution two is used to spray the upper surface of the existing film layer to form a film, and then placed in a vacuum drying oven at 135-145°C and baked for 30-40 minutes to form a hole transport layer.

[0013] Specifically, the photoelectric active layer is a perovskite film layer deposited on the upper surface of the hole transport layer.

[0014] Specifically, the electron transport layer is a Mg-doped ZnO film.

[0015] Preferably, the cathode layer is an aluminum film formed on the upper surface of the electron transport layer.

[0016] Specifically, the flexible sealing layer is a flexible waterproof film whose periphery is sealed and connected to the sealing area by an adhesive. Preferably, the flexible waterproof film can be a PET film, a PVC film or a PE film.

[0017] Preferably, the flexible light-transmitting hydrophobic layer is a dyn-PDMS film with a thickness of 10-30 nm.

[0018] In addition, the present invention also provides a flexible photoelectric sensor, which is prepared by the above method. The flexible photoelectric sensor includes a flexible substrate, an anode layer, a hole transport layer, a photoelectric active layer, an electron transport layer and a cathode layer stacked in sequence from bottom to top, and also includes a flexible light-transmitting hydrophobic layer and a flexible sealing layer, wherein the hole transport layer is composed of a modified PEDOT:PSS conductive polymer, the flexible light-transmitting hydrophobic layer is formed on the lower surface of the flexible substrate, and the flexible sealing layer covers the upper surface of the cathode layer and the periphery of the anode layer, the hole transport layer, the photoelectric active layer, the electron transport layer and the cathode layer.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) The flexible photoelectric sensor provided by the present invention has a flexible sealing layer, which together with the flexible substrate seals and encapsulates the anode layer, the hole transport layer, the photoelectric active layer, the electron transport layer and the cathode layer, and each functional layer is isolated from oxygen, water, dust and other substances in the air, which can ensure that the flexible photoelectric sensor has good durability, long service life and can be used normally in a high humidity environment;

[0021] 2) The flexible photoelectric sensor provided by the present invention also has a flexible light-transmitting hydrophobic layer located on the lower surface of the flexible substrate, which is composed of a highly light-transmitting and super-hydrophobic nanofilm layer, and water mist, dust and stains are difficult to be contaminated and attached to it, so that the flexible photoelectric sensor can be ensured to reduce the cleaning frequency during use, and can maintain light sensitivity for a long time, and the performance is significantly improved;

[0022] 3) The hole transport layer of the flexible photoelectric sensor provided by the present invention is composed of a PEDOT:PSS conductive polymer that is binary doped with N,N-dimethylformamide and ethylene glycol and cured after layered coating. During the layered coating, the PEDOT:PSS conductive polymer film layer doped with N,N-dimethylformamide is first moderately dried and then treated with oxygen plasma to form nano-sized protrusions and recessed structures on the surface that help enhance hole transport. Then, an ethylene glycol-doped PEDOT:PSS aqueous solution is sprayed thereon. After spraying, part of it penetrates into the previous film layer and is then cured under heating to form a hole transport layer with better light transmittance and stronger conductivity, which can significantly improve the performance of the photoelectric sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A cross-sectional view of a flexible photoelectric sensor provided by the present invention;

[0024] Figure 2 for Figure 1 A top view of the flexible substrate and the anode layer thereon of the flexible photosensor shown.

[0025] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0026] 1. Flexible substrate; 2. Anode layer; 3. Hole transport layer; 4. Photoelectric active layer; 5. Electron transport layer; 6. Cathode layer; 7. Flexible sealing layer; 8. Flexible light-transmitting hydrophobic layer; 9. Adhesive; 10. Sealing area. DETAILED DESCRIPTION

[0027] The principles and features of the present invention are described below in conjunction with the accompanying drawings and specific embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0028] Unless otherwise specified, the pharmaceutical raw materials used in the following examples are all commercially available products, and the methods used are all conventional methods in the art unless otherwise specified.

[0029] The present invention provides Figure 1 and 2 A flexible photoelectric sensor is shown, which includes a flexible substrate 1, an anode layer 2, a hole transport layer 3, a photoelectric active layer 4, an electron transport layer 5 and a cathode layer 6 stacked in sequence from bottom to top, and also includes a flexible sealing layer 7 and a flexible light-transmitting hydrophobic layer 8, wherein the flexible sealing layer 7 covers the upper surface of the cathode layer 6 and the periphery of the anode layer 2, the hole transport layer 3, the photoelectric active layer 4, the electron transport layer 5 and the cathode layer 6, and the flexible light-transmitting hydrophobic layer 8 is formed on the lower surface of the flexible substrate 1. During preparation, various functional layers are stacked up and down in the middle area of ​​the upper surface of the flexible substrate 1, and a sealing area 10 is reserved around the middle area of ​​the upper surface to connect the periphery of the flexible sealing layer 7 through an adhesive 10 to form a packaging structure. It should be noted that the anode layer and the cathode layer can lead out conductive contacts before being encapsulated by the flexible sealing layer.

[0030] The specific preparation process of the above-mentioned flexible photoelectric sensor is described by the following embodiment. Among them, the photoelectric active layer is a perovskite film layer deposited on the upper surface of the hole transport layer; the electron transport layer is a Mg-doped ZnO film; and the cathode layer is an aluminum film formed on the upper surface of the electron transport layer. The formation of the perovskite film layer, the Mg-doped ZnO film and the aluminum film is well known to those skilled in the art and will not be described in detail here.

[0031] Example 1

[0032] A flexible photoelectric sensor, the preparation of which comprises the following steps:

[0033] S1. The upper surface of the transparent flexible substrate (PET film) is cleaned by oxygen plasma. After the treatment, a 2.5 mg / mL titanium carbide MXene thin layer dispersion is used to spin-coat the middle area of ​​the upper surface, and then annealed after heating to obtain an anode layer. The transparent flexible substrate is provided with a sealing area around the anode layer, and the width of the sealing area is 3 mm;

[0034] S2. firstly, forming a hole transport layer, a photoelectric active layer, an electron transport layer and a cathode layer on the upper surface of the anode layer from bottom to top, and then forming a flexible sealing layer covering the cathode layer and the sealing area and sealing the anode layer, the hole transport layer, the photoelectric active layer, the electron transport layer and the cathode layer from all sides;

[0035] When the hole transport layer is formed, a PEDOT:PSS (AL 4083) aqueous solution with a solid content of 1.2wt% is first divided into two parts, one of which is mixed with 1% by weight of N,N-dimethylformamide to obtain a solution 1, and the other is mixed with 3.5% by weight of ethylene glycol to obtain a solution 2, firstly using the solution 1 to coat the upper surface of the anode layer to form a film, placing it in a vacuum drying oven at 100-102° C. and baking it for 5 minutes, taking it out and cooling it naturally to room temperature, first using oxygen plasma to treat the newly formed film layer for 2-3 minutes, and then using the solution 2 to spray the upper surface of the existing film layer to form a film, the amounts of the film-forming solution 1 and the solution 2 are equal, and then placing it in a vacuum drying oven at 135-138° C. and baking it for 40 minutes to form a hole transport layer;

[0036] The flexible sealing layer is a flexible waterproof film (PET film) whose periphery is sealed and connected to the sealing area by an adhesive (flexible UV light-curing glue);

[0037] S3. Plasma treatment is performed on the lower surface of the transparent flexible substrate. After the treatment is completed, a flexible light-transmitting hydrophobic layer is formed on the lower surface of the transparent flexible substrate. The flexible light-transmitting hydrophobic layer is a dyn-PDMS film with a thickness of 6-10nm: PDMS and boric acid are initially mixed in a metering ratio of 1.4:1. After sufficient mixing, they are heated and evaporated to be concentrated to less than 30% of the original volume. The concentrated solution is then spin-coated on the lower surface of the transparent flexible substrate and dried in a vacuum environment at 98-100°C for 12-13h to obtain dyn-PDMS that is stably adhered to the lower surface of the transparent flexible substrate. The contact angle is tested to be 156°, which has good super-hydrophobicity. At the same time, the light transmittance is equivalent to that of PET film, with good light transmittance, not easy to accumulate dirt and fog, which can ensure that the flexible photoelectric sensor maintains stable performance for a long time and reduce the frequency of cleaning.

[0038] Example 2

[0039] A flexible photoelectric sensor, the preparation of which comprises the following steps:

[0040] S1. The upper surface of the transparent flexible substrate (PET film) is cleaned by oxygen plasma. After the treatment, a 4.2 mg / mL titanium carbide MXene thin layer dispersion is used to spin-coat the middle area of ​​the upper surface, and then annealed after heating to obtain an anode layer. The transparent flexible substrate is provided with a sealing area around the anode layer, and the width of the sealing area is 5 mm;

[0041] S2. firstly, forming a hole transport layer, a photoelectric active layer, an electron transport layer and a cathode layer on the upper surface of the anode layer from bottom to top, and then forming a flexible sealing layer covering the cathode layer and the sealing area and sealing the anode layer, the hole transport layer, the photoelectric active layer, the electron transport layer and the cathode layer from all sides;

[0042] When the hole transport layer is formed, a PEDOT:PSS (AL 4083) aqueous solution with a solid content of 1.5wt% is first divided into two parts, one of which is mixed with 1.3% by weight of N,N-dimethylformamide to obtain a solution 1, and the other is mixed with 3% by weight of ethylene glycol to obtain a solution 2. The solution 1 is first coated on the upper surface of the anode layer to form a film, and then placed in a vacuum drying oven at 110-112° C. and baked for 4 minutes. After being taken out and naturally cooled to room temperature, the newly formed film layer is first treated with oxygen plasma for 2-3 minutes, and then the solution 2 is sprayed on the upper surface of the existing film layer to form a film. The amounts of the film-forming solution 1 and the solution 2 are equal for the two times, and then placed in a vacuum drying oven at 140-142° C. and baked for 35 minutes to form a hole transport layer.

[0043] The flexible sealing layer is a flexible waterproof membrane (PVC membrane) whose periphery is sealed and connected to the sealing area by an adhesive (flexible UV light-curing glue);

[0044] S3. Plasma treatment is performed on the lower surface of the transparent flexible substrate. After the treatment is completed, a flexible light-transmitting hydrophobic layer is formed on the lower surface of the transparent flexible substrate. The flexible light-transmitting hydrophobic layer is a dyn-PDMS film with a thickness of 15-20 nm: PDMS and boric acid are initially mixed in a metering ratio of 1.6:1. After sufficient mixing, they are heated and evaporated to be concentrated to less than 30% of the original volume. The concentrated solution is then spin-coated on the lower surface of the transparent flexible substrate and dried in a vacuum environment at 85-90°C for 8-10 hours to obtain dyn-PDMS that is stably adhered to the lower surface of the transparent flexible substrate. The contact angle is tested to be 154°, which has good super-hydrophobicity. At the same time, the light transmittance is equivalent to that of PET film, with good light transmittance, not easy to accumulate dirt and fog, which can ensure that the flexible photoelectric sensor maintains stable performance for a long time and reduce the frequency of cleaning.

[0045] Example 3

[0046] A flexible photoelectric sensor, the preparation of which comprises the following steps:

[0047] S1. The upper surface of the transparent flexible substrate (PET film) is cleaned by oxygen plasma. After the treatment, a 5.5 mg / mL titanium carbide MXene thin layer dispersion is used to spin-coat the middle area of ​​the upper surface, and then annealed after heating to obtain an anode layer. The transparent flexible substrate is provided with a sealing area around the anode layer, and the width of the sealing area is 8 mm;

[0048] S2. firstly, forming a hole transport layer, a photoelectric active layer, an electron transport layer and a cathode layer on the upper surface of the anode layer from bottom to top, and then forming a flexible sealing layer covering the cathode layer and the sealing area and sealing the anode layer, the hole transport layer, the photoelectric active layer, the electron transport layer and the cathode layer from all sides;

[0049] When the hole transport layer is formed, a PEDOT:PSS (AL 4083) aqueous solution with a solid content of 1.8wt% is first divided into two parts, one of which is mixed with 1.5% by weight of N,N-dimethylformamide to obtain solution one, and the other is mixed with 2.5% by weight of ethylene glycol to obtain solution two, firstly using solution one to coat the upper surface of the anode layer to form a film, placing it in a vacuum drying oven at 118-120°C, baking for 3 minutes, taking it out and cooling it naturally to room temperature, first using oxygen plasma to treat the newly formed film layer for 2-3 minutes, and then using solution two to spray the upper surface of the existing film layer to form a film, the amounts of solution one and solution two used in the two film-forming processes are equal, and then placing it in a vacuum drying oven at 143-145°C and baking for 30 minutes to form a hole transport layer;

[0050] The flexible sealing layer is a flexible waterproof film (PE film) whose periphery is sealed and connected to the sealing area by an adhesive (flexible UV light-curing glue);

[0051] S3. Plasma treatment is performed on the lower surface of the transparent flexible substrate. After the treatment is completed, a flexible light-transmitting hydrophobic layer is formed on the lower surface of the transparent flexible substrate. The flexible light-transmitting hydrophobic layer is a dyn-PDMS film with a thickness of 25-30nm: PDMS and boric acid are initially mixed in a metering ratio of 1.8:1. After sufficient mixing, they are heated and evaporated to be concentrated to less than 30% of the original volume. The concentrated solution is then spin-coated on the lower surface of the transparent flexible substrate and dried at 75°C in a vacuum environment for 15-16h to obtain dyn-PDMS that is stably adhered to the lower surface of the transparent flexible substrate. The contact angle is tested to be 151°, which has good super-hydrophobicity. At the same time, the light transmittance is equivalent to that of PET film, with good light transmittance, not easy to accumulate dirt and fog, which can ensure that the flexible photoelectric sensor maintains stable performance for a long time and reduce the frequency of cleaning.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a flexible photoelectric sensor, characterized in that: The steps include: S1. The upper surface of the transparent flexible substrate is subjected to oxygen plasma treatment. After the treatment, a MXene thin layer dispersion is used to spin-coat a film in the middle area of ​​the upper surface, and then heated and annealed to obtain an anode layer. The transparent flexible substrate is provided with a sealing area around the anode layer; S2. firstly, forming a hole transport layer, a photoelectric active layer, an electron transport layer and a cathode layer on the upper surface of the anode layer from bottom to top, and then forming a flexible sealing layer covering the cathode layer and the sealing area and sealing the anode layer, the hole transport layer, the photoelectric active layer, the electron transport layer and the cathode layer from all sides; S3. Plasma treatment is performed on the lower surface of the transparent flexible substrate. After the treatment is completed, a flexible light-transmitting hydrophobic layer is formed on the lower surface of the transparent flexible substrate.

2. The method for preparing a flexible photoelectric sensor according to claim 1, characterized in that: The transparent flexible substrate in S1 is a PET film, the MXene thin layer dispersion is a titanium carbide thin layer dispersion with a concentration of 2.5-5.5 mg / mL, and the width of the sealing area is 3-8 mm.

3. The method for preparing a flexible photoelectric sensor according to claim 1, characterized in that: The hole transport layer is a PEDOT:PSS conductive polymer formed by binary doping of N,N-dimethylformamide and ethylene glycol and curing after layered coating.

4. The method for preparing a flexible photoelectric sensor according to claim 3, characterized in that: When the hole transport layer is formed, a PEDOT:PSS aqueous solution with a solid content of 1.2-2.0% is first divided into one part, 1-1.5% by weight of N,N-dimethylformamide is added to one part and mixed to obtain solution one, and 2.5-3.5% of ethylene glycol is added to the other part and mixed to obtain solution two, firstly using solution one to coat the upper surface of the anode layer to form a film, placing it in a vacuum drying oven at 100-120° C. and baking it for 3-5 minutes, taking it out and cooling it naturally to room temperature, first using oxygen plasma to treat the newly formed film layer for 2-3 minutes, and then using solution two to spray the upper surface of the existing film layer to form a film, and then placing it in a vacuum drying oven at 135-145° C. and baking it for 30-40 minutes to form the hole transport layer.

5. The method for preparing a flexible photoelectric sensor according to claim 1, characterized in that: The photoelectric active layer is a perovskite film layer deposited on the upper surface of the hole transport layer.

6. The method for preparing a flexible photoelectric sensor according to claim 1, characterized in that: The electron transport layer is a Mg-doped ZnO film.

7. The method for preparing a flexible photoelectric sensor according to claim 1, characterized in that: The cathode layer is an aluminum film formed on the upper surface of the electron transport layer.

8. The method for preparing a flexible photoelectric sensor according to claim 1, characterized in that: The flexible sealing layer is a flexible waterproof film whose periphery is sealed and connected to the sealing area by an adhesive, and the flexible waterproof film is a PET film, a PVC film or a PE film.

9. A method for preparing a flexible photoelectric sensor according to any one of claims 1 to 9, characterized in that: The flexible light-transmitting hydrophobic layer is a dyn-PDMS film with a thickness of 10-30 nm.

10. A flexible photoelectric sensor, characterized in that: It is prepared by the method according to any one of claims 1 to 9.

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