Ultraviolet and near-infrared dual-band response organic photoelectric detector with light multiplication characteristic

Abstract

The invention discloses an ultraviolet and near-infrared dual-band response organic photoelectric detector with a light multiplication characteristic. The ultraviolet and near-infrared dual-band response organic photoelectric detector comprises a light filtering layer, a substrate, an electrode, a charge transmission layer, a light active layer, a charge transmission layer and an optical microcavity layer which are sequentially stacked and arranged, near-infrared light can selectively penetrate through the light filtering layer; the optical active layer is a mixed film and comprises an electron donor material and an electron acceptor material; the optical microcavity can selectively transmit light of an ultraviolet band; two working modes are realized through double incidence windows, different working modes have different spectral response ranges, the two working modes are integrated in a single device through a simple and low-cost preparation method, and ultraviolet / near-infrared narrow-band dual-waveband optical detection is realized. The detection wavelength range of the detector is an ultraviolet light wave band with the range of 300-380 nm and a near-infrared wave band with the range of 780-970 nm, and the detector has the advantages that the external quantum efficiency exceeds 100% under two wave bands, the response speed is high, the structure is simple, the service life is long, solution treatment can be achieved, and large-area machining can be achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of organic photodetectors, and relates to an ultraviolet / near-infrared dual-band response organic photodetector with light multiplication characteristics and a preparation method thereof. BACKGROUND

[0002] As wave bands with special application value in the electromagnetic spectrum, ultraviolet (UV) and near-infrared (NIR) occupy a key position in the fields of modern science and technology and people's livelihood. Among them, the ultraviolet band (especially 300-380 nm) has the characteristics of optical communication, material structure characterization and environmental monitoring due to its high photon energy, and is widely used in scenes such as atmospheric ozone concentration detection, early fluorescence diagnosis of skin cancer, flame warning (such as ultraviolet signals in industrial fires appearing before visible light / infrared), semiconductor lithography process; and the near-infrared band has become the core technology support in the fields of night vision security, biological tissue oxygen monitoring, near-infrared optical communication (short-distance high-speed data transmission) and the like due to its strong photon penetration (weak absorption to biological tissues, plastics and other media) and no damage to the human body.

[0003] With the surge in demand for multi-band collaborative detection (such as the need for intelligent security systems to simultaneously achieve "ultraviolet flame warning + near-infrared night vision monitoring" and the need for portable medical devices to simultaneously complete "ultraviolet fluorescence marker identification + near-infrared blood oxygen monitoring"), traditional single-band photodetectors have been unable to meet the application requirements of integration and miniaturization, and ultraviolet / near-infrared dual-band integrated detector devices have become a research hotspot. However, current dual-band detection technology still faces many bottlenecks. Traditional inorganic dual-band detectors: high cost, poor flexibility, complex preparation. Currently, commercial dual-band detectors are mostly based on inorganic semiconductor materials and are mainly realized through two schemes: multi-device integrated scheme: two independent detectors are prepared using "ultraviolet response inorganic materials (such as GaN, SiC)" and "near-infrared response inorganic materials (such as Si, InGaAs, HgCdTe)", respectively, and then dual-band function is realized through circuit integration. This scheme has the problems of large size, high power consumption and poor system compatibility, and InGaAs, HgCdTe and other near-infrared materials are expensive (dependent on rare elements) and difficult to popularize on a large scale. Single-device heterojunction scheme: through precise processes such as molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD), ultraviolet-near-infrared response heterojunctions (such as GaN / Si heterojunctions) are grown on a single substrate. However, the preparation process often requires high vacuum and high temperature environments, which are costly, and the prepared devices are mechanically rigid and cannot adapt to the needs of flexible wearable devices (such as flexible medical patches and foldable security lenses).

[0004] Organic semiconductor materials have become the ideal candidate for dual-band detectors due to their solution processability (e.g., spin coating, blade coating, suitable for large-area low-cost preparation), tunable band gap (covering the ultraviolet to near-infrared wave band through molecular structure design), flexibility compatibility (attachable to PET, PI and other flexible substrates), and other advantages. However, the current research and development of organic ultraviolet / near-infrared dual-band detectors still has some core technical difficulties: It is difficult to achieve narrow-band response: most existing organic dual-band detectors are "wide-band coverage type" (e.g., response interval 300-1000 nm), and the response spectra of ultraviolet and near-infrared wave bands overlap, which cannot distinguish the light signals of the two wave bands (e.g., cannot exclude ultraviolet interference signals in the near-infrared night vision scene), and need to be equipped with a complex optical filtering system, increasing the device size and cost.

[0005] The external quantum efficiency (EQE) of most organic dual-band detectors is less than 100%, making it difficult to achieve weak light detection (e.g., near-infrared night vision under low illumination, weak ultraviolet fluorescence signal detection). Some organic dual-band detectors need to use "multi-layer heterojunction stacking" (e.g., ultraviolet response layer and near-infrared response layer are prepared separately), which has complicated process steps, requires high bias voltage for wave band switching, is prone to charge accumulation, and has poor interfacial compatibility between layers, affecting the stability of the device. Most organic detectors with "light multiplication characteristics" (EQE>100%) are limited to single wave band (e.g., only ultraviolet or only near-infrared), and the technology of achieving light multiplication for dual wave bands has not been broken through.

[0006] In summary, the existing ultraviolet / near-infrared dual-band detection technology cannot simultaneously meet the comprehensive needs of "narrow-band response (no wave band interference), high EQE (light multiplication characteristics), low cost and large-area preparation, and flexibility compatibility potential". Developing an organic photodetector based on a new organic acceptor material, achieving ultraviolet / near-infrared narrow-band dual response through simple structure design (e.g., single photoactive layer + dual incident window), and having light multiplication characteristics and solution processability, not only breaks through the existing technical bottlenecks, but also promotes the industrialization application of dual-band detection in flexible medical devices, intelligent security, portable environmental monitoring and other fields, and has important academic value and market prospects. SUMMARY

[0007] In view of the deficiencies in the prior art, the present application aims to provide an ultraviolet and near-infrared dual-band response organic photodetector with light multiplication characteristics, wherein specifically, the first object is to provide an ultraviolet / near-infrared dual-band response organic photodetector with light multiplication characteristics, which is based on a kind of donor-acceptor material suitable for generating high external quantum efficiency in the ultraviolet / near-infrared wave band as a photoactive layer, has the characteristics of ultraviolet / near-infrared narrow-band dual-band multiplication response, and the response time can reach below 150 microseconds; the second object is to provide a preparation method of an organic photodetector using an organic conjugated molecular material as a photoactive layer acceptor material, which has high detection performance in the ultraviolet / near-infrared dual-band; and the third object is to provide a preparation method of an ultraviolet / near-infrared dual-band response organic photodetector with light multiplication characteristics, which realizes ultraviolet / near-infrared re-band dual-band multiplication response through double incident windows.

[0008] In order to solve the above technical problems, the present application adopts the following technical solutions to achieve the above objects: The ultraviolet and near-infrared dual-band response organic photodetector with light multiplication characteristics comprises a light filtering layer, a substrate, an electrode, a first charge transport layer, a photoactive layer, a second charge transport layer and an optical microcavity layer arranged in sequence; wherein the positions of the first charge transport layer and the second charge transport layer are interchangeable. The light filtering layer is a near-infrared narrow-band light filtering layer, which comprises a polymer-based filter with a wide-band visible light absorption function and a filter capable of cutting off light below 730 nm. The photoactive layer is a mixed film, which comprises an electron donor material and an electron acceptor material; wherein the electron acceptor material comprises an organic conjugated molecule IDSe-S-4F with a structure of electron-deficient unit-π unit-electron-donating unit-π unit-electron-deficient unit, and the structural formula is as follows:

[0009] Wherein R is isooctyl; The optical microcavity layer is a sandwich structure of semi-transparent metal electrode I-lithium fluoride layer-semi-transparent metal electrode II, which can selectively transmit ultraviolet light of 300-380 nm. The detector realizes two working modes through double incident windows: near-infrared light is incident on the photoactive layer through the light filtering layer to realize near-infrared response; ultraviolet light is incident on the photoactive layer through the optical microcavity layer to realize ultraviolet response; and the detection wavelength ranges of the two working modes are 300-380 nm and 780-970 nm respectively, and the external quantum efficiencies EQE in the dual-band are both more than 1000%.

[0010] The present application also includes the following technical features: Specifically, the substrate is a transparent substrate selected from polyethylene terephthalate, polyimide, ordinary glass or quartz glass, and has a thickness of 50-500 μm.

[0011] Specifically, the electrode is indium tin oxide; The first charge transport layer is a hole transport layer, and the material is selected from PEDOT:PSS, PTAA or Spiro-OMeTAD, and has a thickness of 5-20 nm. The second charge transport layer is an electron transport layer, and the material is selected from PDINO, PDINN, F3N or ZnO nanoparticles, and has a thickness of 5-20 nm.

[0012] Specifically, in the optical microcavity layer, the materials of the semi-transparent metal electrode I and the semi-transparent metal electrode II are both selected from Au, Al or Ag, and have a thickness of 30-60 nm; the thickness of the lithium fluoride layer is 40-60 nm.

[0013] Specifically, in the photoactive layer, the electron donor material is selected from J52, and the mass ratio of the electron donor material to the electron acceptor material is 1:0.1-1:1.2; the photoactive layer has a thickness of 80-500 nm.

[0014] Specifically, when the detector is arranged in a stacking manner of the filter layer, the substrate, the electrode, the first charge transport layer, the photoactive layer, the second charge transport layer, and the optical microcavity layer in sequence, it is a normal structure; When the detector is arranged in a stacking manner of the filter layer, the substrate, the electrode, the second charge transport layer, the photoactive layer, the first charge transport layer, and the optical microcavity layer in sequence, it is a reverse structure.

[0015] A preparation method of the organic photodetector with the ultraviolet and near-infrared dual-band response and the light multiplication property comprises the following steps: Step one: substrate pretreatment: ultrasonic cleaning and plasma cleaning the transparent substrate in sequence; Step two: setting the electrode on the substrate; Step three: setting the charge transport layer on the electrode; wherein, in the normal structure, the first charge transport layer is spin-coated on the electrode, and in the reverse structure, the second charge transport layer is spin-coated on the electrode; Step four: setting the photoactive layer on the charge transport layer, including dissolving the electron donor material and the electron acceptor material in a solvent according to a mass ratio of 1:0.1-1:1.2 to prepare a mixed solution, uniformly coating, dropping or spin-coating the mixed solution on the charge transport layer, and then heating and annealing to volatilize the solvent, thereby preparing the photoactive layer; Step five: setting the charge transport layer on the photoactive layer; in the normal structure, the second charge transport layer is spin-coated on the photoactive layer, and in the reverse structure, the first charge transport layer is set on the photoactive layer; Step six: setting an optical microcavity layer on the charge transport layer; the optical microcavity layer is deposited on the surface of the charge transport layer by a thermal evaporation method in sequence of a semi-transparent metal electrode I, a lithium fluoride layer and a semi-transparent metal electrode II; Step seven: setting a filter layer under the substrate.

[0016] Specifically, in step four, the solvent includes one or more of pentane, dichloromethane, carbon disulfide, 1,1-dichloroethane, chloroform, tetrahydrofuran, hexane, trifluoroacetic acid, 1,1,1-trichloroethane, carbon tetrachloride, benzene, ethyl acetate, isopropanol, 1,2-dichloroethane, ethylene glycol dimethyl ether, nitromethane, trichloroethylene, toluene, chlorobenzene, 1,4-dioxane, pyridine, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, p-xylene, xylene, o-xylene, N,N-dimethylformamide, cyclohexanone, phenol, 1,2-propanediol, dimethyl sulfoxide, and acetamide; the heating annealing temperature ranges from 0°C to 200°C.

[0017] Compared with the prior art, the present application has the following technical effects: The photoelectric detector provided by the present application is realized by sequentially stacking the filter layer, the substrate, the electrode, the charge transport layer, the photoactive layer, the charge transport layer and the optical microcavity layer (the optical microcavity layer includes the semi-transparent metal electrode, the lithium fluoride layer and the semi-transparent metal electrode), wherein the photoactive layer is a mixed film made of an electron donor material and an electron acceptor material, so that the ultraviolet-near infrared spectral response is realized in a single device. By using the optical microcavity and the filter on the device, the ultraviolet / near infrared narrow-band dual-band light detection is realized in a single device through a double-injection window. The spectral detection range of the ultraviolet / near infrared dual-band response organic photoelectric detector includes the ultraviolet region (300-380 nm) and the near infrared region (780-970 nm). BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a structure diagram of an ultraviolet / near infrared dual-band response organic photoelectric detector of the present application.

[0019] Figure 2 is a current-voltage curve of the ultraviolet / near infrared dual-band response organic photoelectric detector in a dark state.

[0020] Figure 3 is an external quantum efficiency spectral curve of the ultraviolet / near infrared dual-band response organic photoelectric detector with a 150-nanometer photoactive layer thickness.

[0021] Figure 4 is a response time curve of the ultraviolet / near infrared dual-band response organic photoelectric detector.

[0022] The meanings of the various reference numerals in the drawings are as follows: 1. filter layer, 2. substrate, 3. electrode, 4. first charge transport layer, 5. photoactive layer, 6. second charge transport layer, 7. optical microcavity layer. DETAILED DESCRIPTION

[0023] In practical applications, the detector needs to extract useful information from noise. By reducing the dark current in the organic photodetector, the specific detectivity and signal-to-noise ratio of the device can be greatly improved, and sensitive detection of weak light can be realized. In addition, the light multiplication type detector with dual-band response also needs to realize efficient multiplication of charges and precise matching of dual-band response under a certain external bias, which not only activates the carrier multiplication mechanism in the photoactive layer, but also avoids excessive bias leading to a sharp increase in dark current or degradation of device stability, ultimately achieving the synergistic performance of "dual-band response-high light multiplication-fast response speed".

[0024] The present application provides an ultraviolet near-infrared dual-band response organic photodetector with light multiplication characteristics, such as Figure 1 comprising a filter layer 1, a substrate 2, an electrode 3, a first charge transport layer 4, a photoactive layer 5, a second charge transport layer 6 and an optical microcavity layer 7 arranged in sequence; wherein the first charge transport layer 4 and the second charge transport layer 6 are interchangeable.

[0025] The filter layer 1 is a near-infrared narrow-band filter layer, which includes a polymer-based filter with wide-band visible light absorption function (which can absorb visible light band light) and a filter that can cut off light below 730 nm (which can block ultraviolet light and visible light below 730 nm).

[0026] The photoactive layer 5 is a mixed film, which includes an electron donor material and an electron acceptor material; wherein the electron acceptor material includes an organic conjugated molecule IDSe-S-4F of a structure (A-π-D-π-A) type of electron-deficient unit-π unit-electron-donating unit-π unit-electron-deficient unit, which can realize ultraviolet / near-infrared dual-band detection, and its structural formula is:

[0027] wherein R is isooctyl; The optical microcavity layer 7 is a sandwich structure of semi-transparent metal electrode I-lithium fluoride layer-semi-transparent metal electrode II, which can selectively transmit 300-380 nm ultraviolet light.

[0028] The detector realizes two working modes through double-injection windows: the light from the bottom of the device shows near-infrared multiplication response; the near-infrared light is injected to the light active layer 5 through the filter layer 1 to realize near-infrared response; the light from the top of the device shows ultraviolet multiplication response: the ultraviolet light is injected to the light active layer 5 through the optical microcavity layer 7 to realize ultraviolet response; and the detection wavelength ranges of the double working modes are 300-380 nm (ultraviolet) and 780-970 nm (near-infrared) respectively, and the external quantum efficiency (EQE) under the double wave bands is more than 1000%.

[0029] The substrate 2 is a transparent substrate selected from polyethylene terephthalate (PET), polyimide (PI), ordinary glass or quartz glass, and has a thickness of 50-500 mu m.

[0030] The electrode 3 is indium tin oxide.

[0031] The charge transport layer includes PEDOT:PSS, zinc oxide (ZnO), molybdenum trioxide (MoO3) or PDINO.

[0032] The first charge transport layer 4 is a hole transport layer, the material is selected from PEDOT:PSS, PTAA or Spiro-OMeTAD, and the thickness is 5-20 nm; the second charge transport layer 6 is an electron transport layer, the material is selected from PDINO, PDINN, F3N or ZnO nanoparticles, and the thickness is 5-20 nm.

[0033] In the optical microcavity layer 7, the materials of the semi-transparent metal electrode I and the semi-transparent metal electrode II are both selected from Au, Al or Ag, and the thickness is 30-60 nm; the thickness of the lithium fluoride layer is 40-60 nm.

[0034] In the light active layer 5, the electron donor material is selected from J52, the mass ratio of the electron donor material to the electron acceptor material is 1:0.1-1:1.2, and the thickness of the light active layer 5 is 80-500 nm.

[0035] When the detector is stacked and arranged in the order of the filter layer 1, the substrate 2, the electrode 3 (anode), the first charge transport layer 4 (hole transport layer), the light active layer 5, the second charge transport layer 6 (electron transport layer) and the optical microcavity layer 7, it is a normal structure.

[0036] When the detector is stacked and arranged in the order of the filter layer 1, the substrate 2, the electrode 3 (cathode), the second charge transport layer 6 (electron transport layer), the light active layer 5, the first charge transport layer 4 (hole transport layer) and the optical microcavity layer 7, it is a flip-chip structure.

[0037] The application also provides a preparation method of an ultraviolet and near-infrared double-waveband response organic photodetector with light multiplication characteristics. Step one: substrate pretreatment: ultrasonic cleaning, plasma cleaning of the transparent substrate in turn; Step two: set electrode on the substrate; indium tin oxide is plated on the substrate, then cleaned with ultrasonic cleaner in deionized water, acetone, semiconductor cleaner, isopropyl alcohol; after cleaning, dry with nitrogen; then clean with plasma cleaner for 2 minutes.

[0038] Step three: set charge transport layer on the electrode; the positive structure is to spin-coat the first charge transport layer such as PEDOT:PSS (i.e. poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)) on the electrode, and the inverted structure is to spin-coat the second charge transport layer such as zinc oxide (ZnO) on the electrode.

[0039] Step four: set photoactive layer on the charge transport layer, including dissolving electron donor material and electron acceptor material in solvent according to mass ratio 1:0.1-1:1.2 to prepare mixed solution, uniformly coating, dropping or spin-coating the mixed solution on the charge transport layer, and then heating and annealing to evaporate the solvent to prepare the photoactive layer; Specifically, in step four, the solvent includes one or more of pentane, dichloromethane, carbon disulfide, 1,1-dichloroethane, chloroform, tetrahydrofuran, hexane, trifluoroacetic acid, 1,1,1-trichloroethane, carbon tetrachloride, benzene, ethyl acetate, isopropyl alcohol, 1,2-dichloroethane, ethylene glycol dimethyl ether, nitromethane, trichloroethylene, toluene, chlorobenzene, 1,4-dioxane, pyridine, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, p-xylene, xylene, o-xylene, N,N-dimethylformamide, cyclohexanone, phenol, 1,2-propanediol, dimethyl sulfoxide, acetamide; preferably chloroform. The heating and annealing temperature ranges from 0°C to 200°C; preferably the temperature is 200°C.

[0040] Step five: set charge transport layer on the photoactive layer; the positive structure is to spin-coat the second charge transport layer such as PDINO or F3N on the photoactive layer, and the inverted structure is to set the first charge transport layer on the photoactive layer such as placing the sample obtained in step four into a vacuum chamber containing MoO3, heating the MoO3 powder to evaporate and uniformly adhere to the photoactive layer, and evaporating MoO3 on the photoactive layer; Step six: set optical microcavity layer on the charge transport layer; the optical microcavity layer is deposited on the surface of the charge transport layer by thermal evaporation method in order, including semi-transparent metal electrode I, lithium fluoride layer, semi-transparent metal electrode II; specifically, the sample obtained in step five is placed into a vacuum chamber containing aluminum ingot, silver ingot or gold ingot and lithium fluoride powder, and the metal electrode and lithium fluoride film are plated by thermal evaporation to form the optical microcavity. The semi-transparent electrode in the optical microcavity layer is preferably silver (Ag), and the thickness is preferably 50 nanometers. The thickness of the lithium fluoride layer is preferably 58 nanometers. The thickness of the photoactive layer 5 is preferably 150 nanometers.

[0041] Step seven: setting a filter layer under the substrate; a near-infrared narrow-band filter layer is attached to the side of the substrate away from the bottom electrode, to obtain an organic photodetector. Specifically, the filter layer is realized by spin-coating an organic thin film on the back of the substrate or by installing an inorganic filter.

[0042] The following gives specific embodiments of the present application, it should be noted that the present application is not limited to the following specific embodiments, any equivalent transformation made on the basis of the technical solutions of the present application falls within the protection scope of the present application.

[0043] Example 1: In this embodiment, several indium tin oxide (ITO) conductive glass substrates of the same batch were taken, with a size of 15 mm x 15 mm and an ITO thickness of about 130 nm. The ITO glass substrates were sequentially ultrasonically cleaned with deionized water, acetone, semiconductor cleaning agent, and isopropyl alcohol, and then dried with nitrogen. Before use, the ITO glass substrate was plasma cleaned in a plasma cleaner for 2 minutes, and then placed on a spin coater to drop a proper amount of PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)) suspension (Xi'an Baolai Optical Technology Co., Ltd., model AI 4083) on its surface. Before dropping, the suspension should be filtered with a 0.2 micron polyvinylidene fluoride (PVDF) filter. The spin coater was started to spin at a speed of 4500 rpm for 30 seconds to obtain a 30 nm thick hole transport layer. After film formation, the ITO conductive glass substrate coated with PEDOT:PSS was placed on a heating stage at 150°C to remove residual solvents and obtain a stable film.

[0044] Subsequently, the prepared film was placed in a special glove box filled with nitrogen and placed on a corresponding spin coater. A chloroform solution of J52:IDSe-S-4F with a concentration of 10 mg / ml was prepared and dropped on the surface of the hole transport layer. The spin coater was started to spin at a speed of 2000 rpm. The thickness of the light radiation layer film obtained by this method was 150 nm, and the preferred thickness was 140-160 nm. The prepared film was placed on a hot stage at 200°C for thermal annealing. After the film was stable, the previously prepared electron transport layer PNDIT-F3N (solvent: methanol, with 0.4% acetic acid, concentration: 1 mg / ml) was prepared by spin coating to obtain a F3N film. The thickness of the F3N film in this embodiment was 10 nm. Then, the sample was moved into a vacuum evaporation chamber, and a 50 nm silver film, a 58 nm lithium fluoride film, and a 50 nm silver film were evaporated by thermal evaporation as an optical microcavity. -4 After the above steps, a 50 nm silver film, a 58 nm lithium fluoride film, and a 50 nm silver film were evaporated by thermal evaporation as an optical microcavity.

[0045] In this embodiment, the device area is 0.057 square centimeters, and the shape is rectangular. As shown in FIG. 1, under a positive 5 volt condition, the dark current density is 3.37 x 10⁻¹⁰ A / cm². Figure 2 As shown in FIG. 1, under a positive 5 volt condition, the dark current density is 3.37 x 10⁻¹⁰ A / cm².2 Amp / cm2, which can realize the optimal light multiplication under a positive 5-volt bias. As shown in Figure 3 shown, under the condition of +5 volts, the device external quantum efficiency reaches the ultraviolet response peak at 335 nanometers, and the highest EQE can reach 2350%; it reaches the near-infrared response peak at 780 nanometers, and the external quantum efficiency can reach 5160%.

[0046] Example 2: The organic photodetector with ultraviolet / near-infrared dual-band response prepared in Example 1 and having the light multiplication property was tested for response time. As shown in Figure 4 shown, under the condition of +5 volts, the device showed a rise time of 17.7 microseconds and a fall time of 131.8 microseconds. This result highlights the potential of the light multiplication type dual-band organic photodetector (OPD) device of the present application in terms of ultrafast response speed.

[0047] The preferred embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited to the specific details in the above-described embodiments. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application.

[0048] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again by the present application.

[0049] Furthermore, any combination of various different embodiments of the present application can also be made, as long as it does not deviate from the idea of the present application, and it should also be considered as disclosed by the present application.

Claims

1. An organic photodetector with ultraviolet-near-infrared dual-band response and photomultiplication properties, characterized in that, It includes a filter layer (1), a substrate (2), an electrode (3), a first charge transport layer (4), a photoactive layer (5), a second charge transport layer (6), and an optical microcavity layer (7) arranged in sequence; wherein the positions of the first charge transport layer (4) and the second charge transport layer (6) can be interchanged; The filter layer (1) is a near-infrared narrowband filter layer, including a polymer-based filter with wide-band visible light absorption function and a filter that can block light below 730 nm; The photoactive layer (5) is a hybrid film, which includes an electron donor material and an electron acceptor material; wherein the electron acceptor material includes an organic conjugated molecule IDSe-S-4F with an electron-deficient unit-π unit-electron-donating unit-π unit-electron-deficient unit structure, and its structural formula is: Where R is isooctyl; The optical microcavity layer (7) is a sandwich structure of semi-transparent metal electrode I-lithium fluoride layer-semi-transparent metal electrode II, which can selectively transmit ultraviolet light of 300-380nm; The detector achieves two working modes through dual incident windows: near-infrared light is incident on the photoactive layer (5) through the filter layer (1) to achieve near-infrared response; ultraviolet light is incident on the photoactive layer (5) through the optical microcavity layer (7) to achieve ultraviolet response; and the detection wavelength ranges of the dual working modes are 300-380nm and 780-970nm, respectively, and the external quantum efficiency (EQE) under both bands exceeds 1000%.

2. The ultraviolet-near-infrared dual-band response organic photodetector with photomultiplication characteristics as described in claim 1, characterized in that, The substrate (2) is a transparent substrate, selected from polyethylene terephthalate, polyimide, ordinary glass or quartz glass, with a thickness of 50-500μm.

3. The ultraviolet-near-infrared dual-band response organic photodetector with photomultiplication characteristics as described in claim 1, characterized in that, The electrode (3) is indium tin oxide; The first charge transport layer (4) is a hole transport layer, and the material is selected from PEDOT:PSS, PTAA or Spiro-OMeTAD, with a thickness of 5-20 nm; The second charge transport layer (6) is an electron transport layer, and the material is selected from PDINO, PDINN, F3N or ZnO nanoparticles, with a thickness of 5-20 nm.

4. The ultraviolet-near-infrared dual-band response organic photodetector with photomultiplication characteristics as described in claim 1, characterized in that, In the optical microcavity layer (7), the materials of the semi-transparent metal electrode I and the semi-transparent metal electrode II are both selected from Au, Al or Ag, and the thickness is 30-60 nm; the thickness of the lithium fluoride layer is 40-60 nm.

5. The ultraviolet-near-infrared dual-band response organic photodetector with photomultiplication characteristics as described in claim 1, characterized in that, In the photoactive layer (5), the electron donor material is selected from J52, the mass ratio of the electron donor material to the electron acceptor material is 1:0.1-1:1.2, and the thickness of the photoactive layer (5) is 80-500 nanometers.

6. The ultraviolet-near-infrared dual-band response organic photodetector with photomultiplication characteristics as described in claim 3, characterized in that, When the detector is arranged in the following order of filter layer (1), substrate (2), electrode (3), first charge transport layer (4), photoactive layer (5), second charge transport layer (6), and optical microcavity layer (7), it is a positive mounting structure. When the detector is stacked in sequence as filter layer (1), substrate (2), electrode (3), second charge transport layer (6), photoactive layer (5), first charge transport layer (4), and optical microcavity layer (7), it is an inverted structure.

7. A method for fabricating an ultraviolet-near-infrared dual-band response organic photodetector with photomultiplication characteristics as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Substrate pretreatment: The transparent substrate is ultrasonically cleaned and then plasma cleaned sequentially; Step 2: Set electrodes on the substrate; Step 3: Deposit a charge transport layer on the electrode; wherein, in the upright structure, the first charge transport layer is spin-coated on the electrode, and in the flip-chip structure, the second charge transport layer is spin-coated on the electrode. Step 4: Set a photoactive layer on the charge transport layer, including dissolving electron donor material and electron acceptor material in a solvent at a mass ratio of 1:0.1 - 1:1.2 to prepare a mixed solution, uniformly coating the mixed solution onto the charge transport layer by scraping, dropping, or spin coating, and then heating and annealing to evaporate the solvent to prepare the photoactive layer; Step 5: Deposit a charge transport layer on the photoactive layer; for the upright mounting structure, spin-coat the second charge transport layer on the photoactive layer, and for the flip-chip structure, deposit the first charge transport layer on the photoactive layer. Step 6: Set an optical microcavity layer on the charge transport layer; the optical microcavity layer is formed by sequentially depositing a semi-transparent metal electrode I, a lithium fluoride layer, and a semi-transparent metal electrode II on the surface of the charge transport layer using a thermal evaporation method; Step 7: Set a filter layer under the substrate.

8. The method for fabricating an ultraviolet-near-infrared dual-band response organic photodetector with photomultiplication characteristics as described in claim 7, characterized in that, In step four, the solvent includes one or more of the following: pentane, dichloromethane, carbon disulfide, 1,1-dichloroethane, chloroform, tetrahydrofuran, hexane, trifluoroacetic acid, 1,1,1-trichloroethane, carbon tetrachloride, benzene, acetonitrile, isopropanol, 1,2-dichloroethane, ethylene glycol dimethyl ether, nitromethane, trichloroethylene, toluene, chlorobenzene, 1,4-dioxane, pyridine, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, p-xylene, xylene, o-xylene, N,N-dimethylformamide, cyclohexanone, phenol, 1,2-propanediol, dimethyl sulfoxide, and acetamide; the heating annealing temperature range is 0℃-200℃.

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