Flexible photoelectric detector and preparation method thereof

Abstract

The invention provides a flexible photoelectric detector and a preparation method thereof, and relates to the field of photoelectric detectors, the flexible photoelectric detector comprises a flexible substrate, an electrode layer I, a photosensitive layer, an electrode layer II and a packaging layer, the flexible substrate is located at the bottommost layer, the electrode layer I is deposited between the flexible substrate and the photosensitive layer, and the photosensitive layer is deposited at the top of the electrode layer I; the second electrode layer is deposited on the top of the photosensitive layer, and the packaging layer is deposited on the top of the second electrode layer. The two electrodes are located on the upper side and the lower side of the photosensitive layer respectively and vertically, so that a thinner photosensitive layer is allowed to be used, the light absorption efficiency is improved, meanwhile, charge carriers only need to move within a short distance, the resistance is reduced, and the response speed is increased; and the method is more suitable for applications requiring high sensitivity and quick response, such as high-performance photoelectric detectors or space-limited equipment.

Description

Technical Field

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

[0002] With the development of flexible optoelectronics industry, flexible photodetectors have attracted more and more attention due to their applications in optical communications, imaging technology, environmental monitoring, etc. In practical applications, large-scale integrated flexible photodetector arrays can meet the growing needs of emerging technologies.

[0003] At present, photodetectors are composed of three parts: substrate, electrode layer and photosensitive layer. The photosensitive layer is made of semiconductor materials that can absorb photons. When photons are irradiated on the semiconductor material, the energy of the photon is transferred to the semiconductor material, exciting electrons to jump from the valence band to the conduction band to form electron-holes. The separated electrons and holes reach the electrode layer respectively. Due to the action of the built-in electric field or the external electric field, the electrons and holes are separated and moved to different areas. This process ensures that the generated carriers will not recombine quickly, so that electrical signals can be generated to form photogenerated current. The intensity of the current is proportional to the intensity of the incident light, thereby realizing the conversion of optical signals to electrical signals. At present, the two electrodes in the photodetector are usually located on the left and right sides of the photosensitive layer. Light needs to be incident on the photosensitive layer from the side, so it is necessary to ensure that the photosensitive layer has a certain thickness to fully absorb photons. However, due to the longer electrode path, higher resistance may be caused, affecting the response speed and sensitivity of the detector.

[0004] Therefore, it is necessary to provide a new flexible photodetector and a preparation method thereof to solve the above technical problems. Summary of the invention

[0005] In order to solve the technical problem that the current photosensitive layer has a certain thickness to fully absorb photons, but the longer electrode path may lead to higher resistance, affecting the response speed and sensitivity of the detector, the present invention provides a flexible photodetector and a preparation method thereof.

[0006] On the one hand, the flexible photodetector provided by the present invention includes a flexible substrate, an electrode layer one, a photosensitive layer, an electrode layer two and a packaging layer, wherein the flexible substrate is located at the bottom layer, the electrode layer one is deposited between the flexible substrate and the photosensitive layer, the photosensitive layer is deposited on the top of the electrode layer one, the electrode layer two is deposited on the top of the photosensitive layer, and the packaging layer is deposited on the top of the electrode layer two.

[0007] Furthermore, two dielectric layers are included, and the two dielectric layers are respectively located between the electrode layer 1 and the photosensitive layer and between the electrode layer 2 and the photosensitive layer.

[0008] Another aspect of the present invention provides a method for preparing a flexible photodetector, the method comprising the following steps:

[0009] S1. preparing a flexible substrate, selecting a flexible polymer material as the substrate and unfolding it;

[0010] S2, pretreatment, using solvent to clean the substrate surface to remove surface grease and dust;

[0011] S3, electrode layer deposition, coating the AgNWs solution on the flexible substrate by spraying or spin coating, and after drying, coating a layer of PEDOT:PSS solution, and forming a transparent conductive electrode by heating;

[0012] S4, dielectric layer deposition, using a transparent insulating material to form a dielectric layer on the upper and lower surfaces of the photosensitive layer by chemical vapor deposition;

[0013] S5, photosensitive layer deposition, coating the photosensitive layer material uniformly on the electrode layer 1 by spraying or spin coating and performing drying treatment;

[0014] S6, deposition of the second electrode layer, coating the AgNWs solution on the photosensitive layer by spraying or spin coating, and after drying, coating a layer of PEDOT:PSS solution, and forming a transparent conductive electrode by heating;

[0015] S7, encapsulation layer deposition, using a transparent polymer to form an encapsulation layer by coating the outermost layer of the second electrode layer;

[0016] S8, post-processing, curing and annealing after packaging.

[0017] Furthermore, the flexible polymer material is a PET film.

[0018] Furthermore, the photosensitive layer material is a perovskite solution.

[0019] Furthermore, the curing treatment in the post-treatment step is performed by heating or UV light irradiation.

[0020] Furthermore, the annealing treatment in the post-processing step eliminates stress inside the material through high temperature.

[0021] Furthermore, during the deposition of the electrode layer 1, the photosensitive layer, the dielectric layer, the electrode layer 2 and the encapsulation layer, the speed change of the flexible substrate is detected by a speed sensor, and the tension of the flexible substrate is adjusted by a tension controller to ensure that the coating on the surface of the flexible substrate is evenly distributed during the deposition process.

[0022] Compared with the related art, the flexible photodetector and the preparation method thereof provided by the present invention have the following advantages:

[0023] Beneficial effects:

[0024] 1. The present invention allows the use of a thinner photosensitive layer by arranging two electrodes vertically on the upper and lower sides of the photosensitive layer, and thinning the photosensitive layer, thereby improving the light absorption efficiency. At the same time, the charge carriers only need to move within a shorter distance, which reduces the resistance and improves the response speed. It is more suitable for applications that require high sensitivity and fast response, such as high-performance photodetectors or space-constrained devices.

[0025] 2. The AgNWs solution in the present invention has high conductivity and can form a conductive network, and is combined with the PEDOT:PSS solution to assist in conductivity. The PEDOT:PSS solution itself is also a conductive polymer, which can further enhance the conductivity of the electrode and fill the gaps between the AgNWs, thereby significantly improving the conductivity of the electrode. Compared with pure metal electrodes, the cost is lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the structure of the flexible photodetector provided by the present invention;

[0027] Figure 2 A flowchart of a method for preparing a flexible photodetector provided by the present invention;

[0028] Figure 3 A flowchart of the photosensitive layer deposition process provided by the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0030] Please refer to Figure 1 , Figure 2 , Figure 3 ,in, Figure 1 A schematic diagram of the structure of the flexible photodetector provided by the present invention; Figure 2 A flowchart of a method for preparing a flexible photodetector provided by the present invention; Figure 3 A flowchart of the photosensitive layer deposition process provided by the present invention.

[0031] Embodiment 1

[0032] In the specific implementation process, Figure 1As shown, the flexible photodetector provided by the present invention includes a flexible substrate, an electrode layer 1, a photosensitive layer, an electrode layer 2 and a packaging layer, the flexible substrate is located at the bottom layer, the electrode layer 1 is deposited between the flexible substrate and the photosensitive layer, the photosensitive layer is deposited on the top of the electrode layer 1, the electrode layer 2 is deposited on the top of the photosensitive layer, and the packaging layer is deposited on the top of the electrode layer 2. The photosensitive layer is thinned by mechanical or chemical methods, and two electrodes are respectively located on the upper and lower sides of the photosensitive layer. Since light can be directly incident on the photosensitive layer from above, this means that the vertical configuration allows the use of a thinner photosensitive layer to reduce light scattering, thereby improving light absorption efficiency;

[0033] Furthermore, two dielectric layers are included, and the two dielectric layers are respectively located between the electrode layer 1 and the photosensitive layer and between the electrode layer 2 and the photosensitive layer.

[0034] Embodiment 2

[0035] Another aspect of the present invention provides a method for preparing a flexible photodetector, referring to Figure 2 As shown, the method comprises the following steps:

[0036] S1. Prepare a flexible substrate (thickness is about 125 μm), select a PET film as the substrate and unfold it;

[0037] S2, pretreatment, using a solvent (such as isopropyl alcohol, acetone) to clean the substrate surface, remove surface grease and dust, and use oxygen plasma to treat the substrate, the power is set to 50W, and the treatment time is 5 minutes;

[0038] S3, electrode layer deposition, coating the AgNWs silver nanowire solution on the flexible substrate by spraying or spin coating, and after drying, coating a layer of PEDOT:PSS aqueous solution, and forming a transparent conductive electrode by heating;

[0039] S4, dielectric layer deposition, using a transparent insulating material to form a dielectric layer on the upper and lower surfaces of the photosensitive layer by chemical vapor deposition;

[0040] S5, photosensitive layer deposition, coating the perovskite solution uniformly on the electrode layer 1 by spraying or spin coating and drying, and then thinning the photosensitive layer by mechanical or chemical methods;

[0041] S6, electrode layer 2 deposition, coating the AgNWs silver nanowire solution on the photosensitive layer by spraying or spin coating, maintaining the drying temperature at 80°C for 30 minutes, and after drying, coating a layer of PEDOT:PSS aqueous solution, and performing heat treatment at a drying temperature of 120°C for 10 minutes to form a transparent conductive electrode;

[0042] S7, depositing an encapsulation layer, using a transparent polymer to form an encapsulation layer by coating the outermost layer of the second electrode layer, and drying at 100° C. for 30 minutes;

[0043] S8, post-processing, curing and annealing treatment are performed after packaging, wherein the curing treatment promotes the curing of the material by heating or UV light irradiation, the annealing temperature is controlled at 100°C, and the annealing time is 10 minutes. The annealing treatment eliminates the stress inside the material through high temperature and improves the stability of the film.

[0044] In a specific embodiment, reference Figure 3 As shown, the specific steps of photosensitive layer deposition are as follows:

[0045] S501, prepare materials: prepare the perovskite solution to a suitable concentration;

[0046] S502, substrate preparation: fix the electrode layer substrate on the rotating table of the spin coater to ensure that the surface is clean and flat;

[0047] S503: dropping a proper amount of photosensitive layer material (perovskite solution) at the center of the substrate using a dropper or syringe;

[0048] S504, start the spin coater: set an appropriate rotation speed and time, start the spin coater, and make the material evenly distributed on the surface of the substrate;

[0049] S505, drying: After the spin coating is completed, the substrate is placed in an oven for drying to remove the solvent.

[0050] It should be noted that during the spin coating process, the rotation speed, drop amount and environmental control have high requirements:

[0051] Spin speed: 4000rpm, acceleration time 5 seconds, spin time 30 seconds, solvent volume about 20μL per square meter to ensure uniform coating;

[0052] Dropping amount: Control the amount of material added to avoid uneven coating due to too much or too little;

[0053] Environmental control: Spin coating in a dust-free or clean environment to avoid dust contamination;

[0054] Furthermore, during the deposition of electrode layer 1, photosensitive layer, dielectric layer, electrode layer 2 and encapsulation layer, the speed change of the flexible substrate is detected by a speed sensor, and the tension of the flexible substrate is adjusted by a tension controller to ensure that the coating on the surface of the flexible substrate is evenly distributed during the deposition process. Tension control can ensure smooth transfer of materials between various processing stations and maintain consistency and uniformity in deposition, curing and other processes.

[0055] It should be noted that in the present invention, a roll-to-roll production line is used to prepare the flexible photodetector:

[0056] The roll-to-roll production line consists of the following main parts:

[0057] Unwinding station: used to release flexible substrate materials (such as PET film);

[0058] Pretreatment station: cleaning, surface activation and other pretreatment of the substrate;

[0059] Deposition station: used to deposit various layers of materials;

[0060] Processing station: solidify and anneal the deposited film;

[0061] Inspection station: Online inspection of the film in production.

[0062] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims, and any figure mark in the claims should not be regarded as limiting the claims involved.

[0063] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A flexible photodetector, characterized in that: It includes a flexible substrate, an electrode layer 1, a photosensitive layer, an electrode layer 2 and a packaging layer, wherein the flexible substrate is located at the bottom layer, the electrode layer 1 is deposited between the flexible substrate and the photosensitive layer, the photosensitive layer is deposited on the top of the electrode layer 1, the electrode layer 2 is deposited on the top of the photosensitive layer, and the packaging layer is deposited on the top of the electrode layer 2.

2. The flexible photodetector according to claim 1, characterized in that: It also includes two dielectric layers, which are respectively located between the first electrode layer and the photosensitive layer and between the second electrode layer and the photosensitive layer.

3. A method for preparing the flexible photodetector as claimed in claim 2, characterized in that: The method comprises the following steps: S1. preparing a flexible substrate, selecting a flexible polymer material as the substrate and unfolding it; S2, pretreatment, using solvent to clean the substrate surface to remove surface grease and dust; S3, electrode layer deposition, coating the AgNWs solution on the flexible substrate by spraying or spin coating, and after drying, coating a layer of PEDOT:PSS solution, and forming a transparent conductive electrode by heating; S4, dielectric layer deposition, using a transparent insulating material to form a dielectric layer on the upper and lower surfaces of the photosensitive layer by chemical vapor deposition; S5, photosensitive layer deposition, coating the photosensitive layer material uniformly on the electrode layer 1 by spraying or spin coating and performing drying treatment; S6, deposition of the second electrode layer, coating the AgNWs solution on the photosensitive layer by spraying or spin coating, and after drying, coating a layer of PEDOT:PSS solution, and forming a transparent conductive electrode by heating; S7, encapsulation layer deposition, using a transparent polymer to form an encapsulation layer by coating the outermost layer of the second electrode layer; S8, post-processing, curing and annealing after packaging.

4. The method for preparing a flexible photodetector according to claim 1, characterized in that: The flexible polymer material is a PET film.

5. The method for preparing a flexible photodetector according to claim 1, characterized in that: The photosensitive layer material is a perovskite solution.

6. The method for preparing a flexible photodetector according to claim 1, characterized in that: The curing treatment in the post-treatment step is performed by heating or UV light irradiation.

7. The method for preparing a flexible photodetector according to claim 1, characterized in that: The annealing treatment in the post-processing step eliminates the stress inside the material by high temperature.

8. The method for preparing a flexible photodetector according to claim 1, characterized in that: During the deposition of the electrode layer 1, the photosensitive layer, the dielectric layer, the electrode layer 2 and the encapsulation layer, the speed change of the flexible substrate is detected by a speed sensor, and the tension of the flexible substrate is adjusted by a tension controller to ensure that the coating on the surface of the flexible substrate is evenly distributed during the deposition process.

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