An organic narrow-band photodetector and a method for preparing the same

Abstract

The present invention discloses an organic narrow-band photodetector and a preparation method thereof, wherein the organic narrow-band photodetector comprises a resonant cavity layer, a base layer, a positive electrode layer, a hole transport layer, a photoactive layer, an electron transport layer and a negative electrode layer stacked sequentially from bottom to top; the resonant cavity layer comprises a first reflective layer, a cavity adjustment layer and a second reflective layer stacked sequentially in a direction away from the base layer, and the extinction coefficient of the cavity adjustment layer in the wavelength range of 400nm to 1600nm is less than 0.01, and the refractive index is 1.6 to 1.8. The organic narrow-band photodetector can realize a highly selective narrow-band organic photodetector by arranging a resonant cavity layer outside the device and controlling the cavity adjustment layer in the resonant cavity layer to have substantially no absorption in the visible to near-infrared band and a continuous and stable refractive index, and has strong light detection performance in the visible to near-infrared band and high selectivity.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric detectors, and in particular to an organic narrow-band photoelectric detector and a preparation method thereof. Background Art

[0002] At a time when the new generation of silicon-based optoelectronics and optical communication technologies are developing rapidly, near-infrared photodetection technology with spectral selectivity is of great importance in the fields of encrypted information transmission, image sensing, and health monitoring. Commercial photodetectors are mainly made of inorganic semiconductor materials, such as silicon, germanium, gallium arsenide and other III-IV main group elements. Due to the rigidity of their inherent molecular structure and their fixed band gap, they are difficult to modify, have high costs, limited spectral coverage, and low exciton separation efficiency in the near-infrared band, which hinders their further application in near-infrared optoelectronic devices.

[0003] Organic photodetectors have the advantages of high responsiveness, biocompatibility and low production cost, and have been booming in recent years. Through the directional design of molecular structure and band gap, especially non-fullerene materials as electron acceptors, the detection range of organic photodetectors can be extended from ultraviolet and visible light to near-infrared bands, but in specific bands, additional optical elements are still required to filter light to achieve high signal-to-noise ratio.

[0004] It is particularly important to realize a new type of self-filtering narrowband photodetector without optical components to improve performance and integration. Since 2017, Koen Vandewal's research group has carried out a series of work on narrowband organic photodetectors based on optical resonators, achieving a quantum efficiency of 40% in the near-infrared band. However, the current organic photodetectors based on optical resonators have complex absorption problems in the visible band, and the near-infrared band is limited by exciton separation, making it difficult to achieve a balance between quantum efficiency and band expansion, and the detection performance in the near-infrared band is poor. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes an organic narrow-band photodetector and a method for preparing the same, which solves the problems of low selectivity and poor near-infrared detection performance of existing organic photodetectors. Among them, the thickness can be precisely controlled by evaporating the cavity adjustment layer; by placing the resonant cavity layer outside the device, a highly selective narrow-band organic photodetector can be realized, and by changing the thickness of the cavity adjustment layer, arbitrary adjustability of the peak value can be achieved, and high-performance detection from the visible to near-infrared band can be achieved by optimizing the photoactive layer material system.

[0006] In the first aspect of the present invention, an organic narrow-band photodetector is proposed, which includes a resonant cavity layer, a base layer, a positive electrode layer, a hole transport layer, a photoactive layer, an electron transport layer and a negative electrode layer stacked in sequence from bottom to top; the resonant cavity layer includes a first reflection layer, a cavity adjustment layer and a second reflection layer stacked in sequence in a direction away from the base layer; the extinction coefficient of the cavity adjustment layer in the wavelength range of 400nm to 1600nm is less than 0.01, and the refractive index is 1.6 to 1.8.

[0007] According to the embodiment of the present invention, the organic narrow-band photodetector has at least the following beneficial effects: the organic narrow-band photodetector includes a resonant cavity layer, wherein the resonant cavity layer is constructed by specifically using two parallel reflective layers and a cavity adjustment layer sandwiched in the middle, and the cavity adjustment layer is controlled to have substantially no absorption in the visible to near-infrared band and a continuous and stable refractive index, forming a Fabry-Perot optical resonant cavity, and the absorption of a specific narrow band of light is achieved by constructing a Fabry-Perot resonant cavity, thereby achieving a narrow-band absorption effect, and a high response of the organic photodetector in a specific narrow band between the visible and near-infrared bands. In the specific working process of the organic narrow-band photodetector, after the wide-spectrum light is incident on the resonant cavity layer, part of the incident light passes through the first reflective layer and the cavity adjustment layer, reaches the second reflective layer, is reflected back, and interferes with the light passing through the first reflective layer, and only the specific narrow band λ in the visible to near-infrared band is coherently enhanced, and the light intensity of the remaining non-interference bands is weakened, so that the wide-spectrum light source can be adjusted to a narrow-band light source after passing through the resonant cavity. The specific narrow band λ is determined by the thickness L and the refractive index n of the cavity adjustment layer, and satisfies the following formula:

[0008]

[0009] Where m is the resonance mode. When m=1, the cavity is in the first resonance. After the thickness of the reflective layer in the resonance cavity layer is fixed, the wavelength of the narrowband light source is determined by the thickness and optical refractive index of the cavity adjustment layer.

[0010] Therefore, by setting the above resonant cavity layer outside the device, a highly selective narrow-band organic photodetector can be obtained. The organic narrow-band photodetector has strong light detection performance in the visible to near-infrared band and has high selectivity.

[0011] In some embodiments of the present invention, the material of the cavity adjustment layer is selected from any one of 8-hydroxyquinoline lithium (Liq, CAS: 850918-68-2), 1,10-phenanthroline (Bphen, CAS: 1662-01-7), zinc sulfide (ZnS), and lithium fluoride (LiF). The above materials have substantially no absorption in the visible to near-infrared band (400nm to 1600nm) and the refractive index is continuous and stable.

[0012] In some embodiments of the present invention, the thickness of the cavity adjustment layer is 100 nm to 300 nm. For example, the thickness of the cavity adjustment layer may be any value of 100 nm, 120 nm, 150 nm, 160 nm, 180 nm, 200 nm, 210 nm, 215 nm, 220 nm, 225 nm, 230 nm, 235 nm, 240 nm, 245 nm, 250 nm, 255 nm, 260 nm, 275 nm, 280 nm, 290 nm, 300 nm, or a range formed by any two of the values.

[0013] In some embodiments of the present invention, the first reflective layer and / or the second reflective layer is a semi-transparent reflective layer.

[0014] In some embodiments of the present invention, the first reflective layer and / or the second reflective layer is any one of a silver reflective layer, a gold reflective layer, an aluminum reflective layer, and a copper reflective layer.

[0015] In some embodiments of the present invention, the thickness of the first reflective layer and / or the second reflective layer is 25nm to 35nm. Further, the thickness of the first reflective layer and / or the second reflective layer may be 25nm to 30nm, 24nm to 28nm, 26nm to 32nm, 30nm to 35nm or 31nm to 33nm. The thickness of the first reflective layer and the second reflective layer may be the same or different.

[0016] In some embodiments of the present invention, the first reflective layer and the second reflective layer are the same.

[0017] In some embodiments of the present invention, at least one of the first reflective layer, the cavity adjustment layer and the second reflective layer is made by evaporation. Further, at least the cavity adjustment layer in the resonant cavity layer is made by evaporation. Further, the first reflective layer, the cavity adjustment layer and the second reflective layer are all made by evaporation.

[0018] The resonant cavity layer is prepared by evaporation, and the thickness is controllable, which can realize the tuning of narrow-band detection in any band such as visible-near infrared. Specifically, by selecting a suitable photoactive layer and controlling the thickness of the cavity adjustment layer by evaporation, the device can have adjustable narrow-band detection performance from visible to near-infrared bands; further, the thickness of the cavity adjustment layer can be controlled by evaporation as needed, so that the optical path difference of the resonance effect changes, and then the resonant wavelength changes, so as to realize arbitrary adjustment of the detection peak, and the half-peak width is less than 30nm, with ultra-high selectivity; further, by optimizing the thickness of the reflective layer, a response with a half-peak width as low as 25nm can be achieved in any band from visible to near-infrared, with a high signal-to-noise ratio.

[0019] The base layer serves as a device substrate and can play a load-bearing role. In some embodiments of the present invention, the base layer is a transparent base layer, and specifically, a material with a high light transmittance can be used, such as a glass base layer, a polyimide (PI) base layer, a polymethyl methacrylate (PMMA) base layer, a thermoplastic polyurethane (TPU) base layer, a polyester film (PET) base layer, etc.

[0020] In some embodiments of the present invention, the positive electrode layer is a transparent conductive electrode layer so as to have good light transmittance and conductivity.

[0021] In some embodiments of the present invention, the material of the positive electrode layer is selected from any one of indium tin oxide, fluorine-doped tin oxide, silver nanowires, and conductive polymers.

[0022] The photoactive layer can absorb photons and convert them into electron-hole pairs, forming a current in the external circuit. Based on the setting of the resonant cavity layer, especially on the basis of preparing the resonant cavity layer by evaporation to achieve controllable thickness adjustment, the organic narrow-band photodetector can further combine the selection of a photoactive layer with high efficiency response in the visible to near-infrared band, so that the organic optoelectronic device can achieve high detection rate narrow-band detection in the visible to near-infrared band, with high performance and good universality. By changing different photoactive layer systems, such as materials with longer infrared band absorption, the spectral range of narrow-band detection can be further broadened.

[0023] In some embodiments of the present invention, the material of the photoactive layer includes an electron donor material and an electron acceptor material in a mass ratio of 1:1.2 to 1.6; the electron donor material is selected from any one of PM6 (CAS: 1802013-83-7), PTB7-Th (CAS: 1469791-66-9), and PBDBT (CAS: 145929-80-4); the electron acceptor material is selected from any one of BTP-4F, COTIC-4F (CAS: 2455510-64-0), and COTIC-4Cl (CAS: 2328092-51-7). The mass ratio of the electron donor material to the electron acceptor material can be controlled to be 1:1.2, 1:1.3, 1:1.5, 1:1.6, etc.

[0024] In some embodiments of the present invention, the photoactive layer is a bulk heterojunction layer formed by blending an electron donor material and an electron acceptor material.

[0025] The hole transport layer can transport holes generated by the photoactive layer to the positive electrode layer. In some embodiments of the present invention, the hole transport layer is made of any one of PEDOT:PSS, CuSCN, MnO3, and NiOx, which can promote hole transport and block electron transport.

[0026] The electron transport layer can transport electrons generated by the photoactive layer to the negative electrode layer. In some embodiments of the present invention, the material of the electron transport layer is selected from any one of Phen-NADPO (CAS: 1480371-38-7), PFN-Br (CAS: 889672-99-5), PDINN (CAS: 1020180-01-1), and PDINO (CAS: 1558023-86-1), which can promote electron transport and block hole transport.

[0027] In some embodiments of the present invention, the cathode electrode layer is a metal electrode layer.

[0028] In some embodiments of the present invention, the negative electrode layer is made of any one of silver (Ag), gold (Au), and aluminum (Al). In order to effectively reduce the interface resistance of the device, the negative electrode layer can be made of silver.

[0029] In some embodiments of the present invention, the thickness of the negative electrode layer is 80nm to 120nm. Further, the thickness of the negative electrode layer may be 80nm to 100nm, 90nm to 100nm, 90nm to 110nm, 85nm to 95nm, 95nm to 105nm, 100nm to 110nm, 100nm to 120nm or 105nm to 115nm.

[0030] A second aspect of the present invention provides a method for preparing any of the above-mentioned organic narrow-band photodetectors, comprising the following steps:

[0031] A positive electrode layer, a hole transport layer, a photoactive layer, an electron transport layer and a negative electrode layer are sequentially arranged on one surface of the base layer;

[0032] A first reflection layer, a cavity adjustment layer and a second reflection layer are sequentially arranged on a surface of the base layer away from the positive electrode layer to construct a resonance cavity layer.

[0033] Since the preparation method adopts all the technical solutions of the above-mentioned organic electro-optical detector, it at least has all the beneficial effects brought by the above-mentioned organic electro-optical detector.

[0034] In some embodiments of the present invention, a positive electrode layer, a hole transport layer, a photoactive layer, an electron transport layer and a negative electrode layer are sequentially arranged on a surface of the base layer, specifically comprising:

[0035] SA1, evaporating or sputtering a positive electrode layer on one surface of the base layer;

[0036] SA2, coating the surface of the positive electrode layer away from the base layer to prepare a hole transport layer;

[0037] SA3, coating the surface of the hole transport layer away from the positive electrode layer to prepare a photoactive layer;

[0038] SA4, coating the surface of the photoactive layer away from the hole transport layer to prepare an electron transport layer;

[0039] SA5. Vapor-deposit a negative electrode layer on the surface of the electron transport layer away from the photoactive layer.

[0040] In some embodiments of the present invention, before step SA1, it further includes: SA0, pre-treating the base layer, wherein the pre-treatment includes cleaning. Further, the cleaning may specifically include: firstly ultrasonic cleaning with ethanol, ultrasonic cleaning with acetone, ultrasonic cleaning with deionized water with detergent, ultrasonic cleaning with deionized water, and ultrasonic cleaning with anhydrous ethanol, and then drying. The time of each ultrasonic cleaning may be controlled within 10 minutes to 30 minutes; ultrasonic cleaning with ethanol and ultrasonic cleaning with deionized water may be performed twice respectively.

[0041] In some embodiments of the present invention, after the positive electrode layer is prepared in step SA1, the positive electrode layer may be further cleaned with oxygen plasma. Specifically, the sample including the base layer and the positive electrode layer may be placed in an oxygen plasma cleaning machine with the positive electrode layer facing upward for cleaning.

[0042] In some embodiments of the present invention, step SA2 may include: preparing a hole transport layer slurry by mixing a hole transport layer material with a solvent, and then coating it on the surface of the positive electrode layer away from the base layer, and annealing to obtain a hole transport layer. The hole transport layer slurry may be coated by spin coating, and the spin coating process may control the rotation speed to 2500rpm to 3500rpm; the time is 20s to 40s. The annealing temperature may be controlled to 140℃ to 160℃; the annealing time may be controlled to 10min to 20min.

[0043] In some embodiments of the present invention, step SA3 may include: dissolving the photoactive layer material in a solvent (such as chlorobenzene), stirring at 40°C to 60°C overnight to obtain an organic active slurry; then, under a nitrogen atmosphere, coating the organic active slurry on the surface of the hole transport layer, and annealing to obtain a photoactive layer. The coating method of the organic active slurry can be spin coating, and the spin coating process can control the speed to 1500rpm to 2500rpm, and the time can be 20s to 40s. The temperature of the annealing treatment can be controlled to 80°C to 120°C; the annealing time can be controlled to 3min to 10min.

[0044] In some embodiments of the present invention, step SA4 may include: preparing an electron transport layer slurry by mixing an electron transport layer material with a solvent, and then applying it to the surface of the photoactive layer away from the hole transport layer, and annealing to obtain an electron transport layer. The electron transport layer slurry may be coated by spin coating, and the spin coating process may control the rotation speed to 1500rpm to 2500rpm; the time is 20s to 40s. The annealing temperature may be controlled to 50℃ to 100℃; the annealing time may be controlled to 3min to 10min.

[0045] In some embodiments of the present invention, in step SA5, the process of preparing the negative electrode layer by evaporation can be carried out at a vacuum degree of less than 5×10 -4 Pa environment, and the whole process speed does not exceed

[0046] In some embodiments of the present invention, a first reflection layer, a cavity adjustment layer, and a second reflection layer are sequentially arranged on the surface of the base layer away from the positive electrode layer by an evaporation method, so that the thickness of the cavity adjustment layer can be precisely adjusted and controlled by the evaporation method, and tuning of narrow-band detection in any band from visible to near-infrared can be achieved by changing the thickness of the cavity adjustment layer.

[0047] In some embodiments of the present invention, the first reflective layer, the cavity adjustment layer and the second reflective layer are evaporated under a vacuum degree of less than 5×10 -4 Pa environment, and the whole process speed does not exceed BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0049] Figure 1 This is a schematic diagram of the structure of an organic narrow-band photodetector according to Example 1;

[0050] Figure 2 This is a schematic diagram of the preparation process of the organic narrow-band photodetector of Example 1. DETAILED DESCRIPTION

[0051] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0052] Example 1

[0053] This embodiment proposes an organic narrow-band photodetector, see Figure 1 , which includes a resonant cavity layer 17, a base layer 11, a positive electrode layer 12, a hole transport layer 13, a photoactive layer 14, an electron transport layer 15 and a negative electrode layer 16 stacked in sequence from bottom to top, wherein the resonant cavity layer 17 includes a first reflective layer 171, a cavity adjustment layer 172 and a second reflective layer 173 stacked in sequence in a direction away from the base layer 11.

[0054] In this embodiment, the first reflective layer 171 and the second reflective layer 173 are both semi-transparent silver reflective layers with a thickness of 30 nm; the cavity adjustment layer 172 is made of Liq with a thickness of 235 nm; the base layer 11 is an ITO glass substrate; the positive electrode layer 12 is a transparent conductive electrode layer made of indium tin oxide with a thickness of 180 nm; the hole transport layer 13 is made of PEDOT:PSS with a thickness of 40 nm; the photoactive layer 14 is made of PTB7-Th:COTIC-4F, the mass ratio of PTB7-Th to COTIC-4F is 1:1.5, and the thickness of the photoactive layer is 110 nm; the electron transport layer 15 is made of Phen-NADPO with a thickness of 10 nm; the negative electrode layer 16 is made of Ag with a thickness of 100 nm. The organic narrow-band photodetector structure is Ag / Liq / Ag / ITO / PEDOT:PSS / PTB7-Th:COTIC-4F / Phen-NADPO / Ag.

[0055] See also Figure 2 The method for preparing the organic narrow-band photodetector comprises the following steps:

[0056] S1. Cleaning a glass substrate with an indium tin oxide transparent conductive electrode layer, wherein the glass substrate is used as the base layer 11 and the indium tin oxide transparent conductive electrode layer is used as the positive electrode layer 12. Specifically, the cleaning process includes: first, ultrasonic cleaning with ethanol twice, each time for 20 minutes; ultrasonic cleaning with acetone for 20 minutes; then, ultrasonic cleaning with deionized water with detergent for 20 minutes; cleaning with deionized water twice, each time for 20 minutes; then, ultrasonic cleaning with anhydrous ethanol for 20 minutes; and finally, drying in an oven overnight.

[0057] S2. Place the cleaned glass substrate and transparent conductive electrode layer into an oxygen plasma cleaning machine with the transparent conductive electrode layer facing upwards, and perform cleaning treatment for 5 minutes.

[0058] S3, dissolving PEDOT:PSS in water to prepare a hole transport layer slurry, spin coating the hole transport layer slurry on the transparent conductive electrode layer after plasma treatment, controlling the rotation speed to 3000 rpm and the time to 30 s, and then annealing at 150° C. for 15 min to obtain a hole transport layer 13.

[0059] S4. Take the electron donor material PTB7-Th and the electron acceptor material COTIC-4F according to the mass ratio of 1:1.5, and then dissolve them in chlorobenzene with a concentration of 20 mg / mL, and stir overnight at 50°C to obtain an organic active slurry; then in a nitrogen protective atmosphere in a glove box, spin-coat the organic active slurry on the hole transport layer 13, control the rotation speed to 2000 rpm, the time to 30 seconds, and anneal at 100°C for 5 minutes to obtain a photoactive layer 14.

[0060] S5. Dissolve Phen-NADPO in isopropanol solvent to prepare an electron transport layer slurry with a concentration of 0.5 mol / L. Spin-coat the electron transport layer slurry on the photoactive layer 14 at a controlled rotation speed of 2000 rpm and a time of 30 s. Anneal at 80° C. for 5 min to obtain the electron transport layer 15.

[0061] S6, transferring the sample obtained in step S5 to a vacuum thermal evaporation device, and -4 In the Pa environment, 100 nm Ag is evaporated on the surface of the electron transport layer 15 to obtain the negative electrode layer 16, and the whole process rate does not exceed

[0062] S7, turn the device over and place it in a vacuum less than 5×10 -4 Pa environment, on the surface of the glass substrate away from the indium tin oxide transparent conductive electrode layer, a 30nm Ag reflection layer, a 235nm Liq cavity adjustment layer and a 30nm Ag reflection layer are sequentially evaporated to form a resonant cavity layer, and the whole process rate does not exceed

[0063] When the organic narrow-band photodetector is working, when the incident light is irradiated from one side of the resonant cavity layer, the light is reflected and interfered in the resonant cavity layer, and only the light wave with the resonance peak can pass through the resonant cavity to reach the photoactive layer 14. As the thickness of the resonant cavity layer increases, the detection peak increases linearly to a higher wavelength range, and near-infrared narrow-band detection can be achieved. The donor-acceptor material in the photoactive layer 14 absorbs photons to generate electron-hole pairs, and separates the generated electrons and holes through the heterojunction interface barrier, and transmits them to the negative electrode layer 16 and the positive electrode layer 12 through the electron transport layer 15 and the hole transport layer 13, respectively, and the electrons and holes are absorbed by the negative electrode layer 16 and the positive electrode layer 12, respectively.

[0064] Through current-voltage test, spectrum analysis and other tests, the organic narrow-band photodetector produces a resonance peak at 910nm, and the switching ratio exceeds 10 at 0V. 5 , the specific detection rate is about 8×10 11 Jones, with a half-peak width of 25nm, can achieve high-performance narrow-band detection in the near-infrared band.

[0065] Example 2

[0066] This embodiment provides an organic narrow-band photodetector. The difference between this embodiment and embodiment 1 is that the thickness of the cavity adjustment layer is adjusted from 235 nm in embodiment 1 to 250 nm, and other structures and preparation operations are the same as those in embodiment 1.

[0067] Through current-voltage test, spectrum analysis and other tests, the detector produces a resonance peak at 1040nm, and the switching ratio exceeds 10 at 0V. 5 , the specific detection rate is about 5×10 11 Jones, with a half-width of 26nm, further expands the high-performance narrow-band detection capability in the higher wavelength near-infrared band.

[0068] Example 3

[0069] This embodiment provides an organic narrow-band photodetector. The difference between this embodiment and embodiment 1 is that the thickness of the cavity adjustment layer is adjusted from 235 nm in embodiment 1 to 150 nm, and other structures and preparation operations are the same as those in embodiment 1.

[0070] Through current-voltage test, spectrum analysis and other tests, the detector produces a resonance peak at 630nm, and the switching ratio exceeds 10 at 0V. 5 , the specific detection rate is about 1×10 12 Jones, with a half-peak width of 24 nm, demonstrated high-performance narrow-band detection capabilities in the visible range.

[0071] Example 4

[0072] This embodiment provides an organic narrow-band photodetector. The difference between this embodiment and Example 1 is that the material of the photoactive layer is an electron donor material PM6 and an electron acceptor material BTP-4F in a mass ratio of 1:1.2, the electron transport layer material is PDINN, and the thickness of the cavity adjustment layer is adjusted from 235nm in Example 1 to 200nm. The other structures and preparation operations are basically the same as those in Example 1.

[0073] The method for preparing the organic narrow-band photodetector comprises the following steps:

[0074] S1-S3, the operations are the same as those in steps S1-S3 in Example 1;

[0075] S4. Take the electron donor material PM6 and the electron acceptor material BTP-4F in a mass ratio of 1:1.2, and then dissolve them in chloroform to a concentration of 16.5 mg / mL, and stir overnight at 50°C to obtain an organic active slurry; then, in a nitrogen protective atmosphere in a glove box, spin-coat the organic active slurry on the hole transport layer 13, control the rotation speed to 4000 rpm, the time to 40s, and anneal at 50°C for 5min to obtain a photoactive layer 14.

[0076] S5. Dissolve PDINN in methanol solvent to prepare an electron transport layer slurry with a concentration of 1 mol / L. Spin-coat the electron transport layer slurry on the photoactive layer 14 at a controlled rotation speed of 3000 rpm and a time of 30 s. Anneal at 80° C. for 5 min to obtain the electron transport layer 15.

[0077] S6-S7: The operations of steps S6 and S7 in Example 1 are the same as those in Example 1, and an organic narrow-band photodetector is obtained.

[0078] Through current-voltage test, spectrum analysis and other tests, the organic narrow-band photodetector produces a resonance peak at 810nm, and the switching ratio exceeds 10 at 0V. 5 , the specific detection rate is about 9.5×10 11 Jones, with a half-peak width of 23nm, can achieve high-performance narrow-band detection in the near-infrared band.

[0079] Example 5

[0080] This embodiment provides an organic narrow-band photodetector, which differs from the embodiment 1 in that the thickness of the first reflective layer and the second reflective layer is 25 nm. The rest is the same as the embodiment 1. Through current-voltage test, spectrum analysis and other tests, the detector generates a resonance peak at 920 nm, and the specific detection rate is about 1×10 12 Jones, with a half-peak width of 30nm, can achieve high-performance narrow-band detection in the near-infrared band.

[0081] Example 6

[0082] This embodiment provides an organic narrow-band photodetector, which differs from the embodiment 1 in that the thickness of the first reflective layer and the second reflective layer is 35 nm. The rest is the same as the embodiment 1. Through current-voltage test, spectrum analysis and other tests, the detector generates a resonance peak at 905 nm, and the specific detection rate is about 5×10 11 Jones, with a half-peak width of 23nm, can achieve high-performance narrow-band detection in the near-infrared band.

[0083] Comparative Example 1

[0084] This comparative example provides an organic narrow-band photodetector, which differs from Example 1 in that: in this comparative example, the material of the cavity adjustment layer is ZnS, the material of the photoactive layer is PM6:BTP-eC9, the material of the hole transport layer is CuSCN, and the material of the electron transport layer is BCP layer and C 60 The organic narrow-band photodetector structure is Ag / ZnS / Ag / ITO / CuSCN / PM6:BTP-eC9 / C 60 / BCP / Ag; the rest is the same as in Example 1.

[0085] The half-maximum width (FWHM), responsivity (R) and response time of the organic narrow-band photodetector of Example 1 and Comparative Example 1 were tested respectively, and the results are shown in Table 1. The half-maximum width is the wavelength range reached when the corresponding narrow peak intensity is normal, the responsivity is the current generated under unit incident light power, and the response time is the time taken for the device current to rise from 10% to 90% of the maximum intensity.

[0086] Table 1

[0087] Organic narrow-band photodetectors Wavelength (nm) Responsivity (mA / W) Half peak width (nm) Response time (ns) Example 1 910 67 25 440 Comparative Example 1 820 279 80 2150

[0088] As can be seen from Table 1, the organic narrow-band photodetector in Example 1 has a lower half-width and response time in the near-infrared band, and has obvious advantages of high selectivity and high transmission speed.

[0089] Comparative Example 2

[0090] This comparative example provides an organic narrow-band photodetector, which is different from Example 1 in that the thickness of the first reflective layer and the second reflective layer is 15 nm. The rest is the same as Example 1. Through current-voltage test, spectrum analysis and other tests, the detector generates a resonance peak at 980 nm, but the half-peak width is 85 nm, the selectivity is poor, and it is difficult to achieve highly selective narrow-band detection.

[0091] Comparative Example 3

[0092] This comparative example provides an organic narrow-band photodetector, which is different from Example 1 in that the thickness of the first reflective layer and the second reflective layer is 40 nm. The rest is the same as Example 1. Through current-voltage test, spectral analysis and other tests, the detector generates a resonance peak at 905 nm, but the peak external quantum efficiency is about 5%, which is low, the loss is large, and it is difficult to achieve high-performance narrow-band detection.

[0093] The half-peak width (FWHM) of the organic narrow-band photodetector of Comparative Example 2 was tested, and the half-peak width of Comparative Example 2 was about 120nm, which was a relatively high value and could not meet the selective detection requirements. It can be concluded that the organic narrow-band photodetector in Example 1 had a lower half-peak width when the thickness of the reflective layer was limited, and had an obvious advantage of high selectivity.

[0094] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An organic narrow-band photodetector, characterized in that: It includes a resonant cavity layer, a base layer, a positive electrode layer, a hole transport layer, a photoactive layer, an electron transport layer and a negative electrode layer stacked in sequence from bottom to top; the resonant cavity layer includes a first reflection layer, a cavity adjustment layer and a second reflection layer stacked in sequence in a direction away from the base layer; the extinction coefficient of the cavity adjustment layer in the wavelength range of 400nm to 1600nm is less than 0.01, and the refractive index is 1.6 to 1.

8.

2. The organic narrow-band photodetector according to claim 1, characterized in that: The material of the cavity adjustment layer is selected from any one of Liq, Bphen, ZnS, and LiF; and / or the thickness of the cavity adjustment layer is 200nm to 300nm.

3. The organic narrow-band photodetector according to claim 1, characterized in that: The first reflecting layer and / or the second reflecting layer is a semi-transparent reflecting layer; And / or, the thickness of the first reflective layer and / or the second reflective layer is 25 nm to 35 nm.

4. The organic narrow-band photodetector according to claim 1, characterized in that: The material of the photoactive layer includes an electron donor material and an electron acceptor material in a mass ratio of 1:1.2 to 1.6; the electron donor material is selected from any one of PM6, PTB7-Th, and PBDBT, and the electron acceptor material is selected from any one of BTP-4F, COTIC-4F, and COTIC-4Cl.

5. The organic narrow-band photodetector according to claim 4, characterized in that: The photoactive layer is a bulk heterojunction layer formed by blending the electron donor material and the electron acceptor material.

6. The organic narrow-band photodetector according to claim 1, characterized in that: The positive electrode layer is a transparent conductive electrode layer; and / or the negative electrode layer is a metal electrode layer.

7. The organic narrow-band photodetector according to claim 6, characterized in that: The material of the positive electrode layer is selected from any one of indium tin oxide, fluorine-doped tin oxide, silver nanowires, and conductive high polymers; and / or the material of the negative electrode layer is selected from any one of silver, gold, and aluminum.

8. The organic narrow-band photodetector according to any one of claims 1 to 7, characterized in that: The material of the electron transport layer is selected from any one of Phen-NADPO, PFN-Br, PDINN, and PDINO; and / or the material of the hole transport layer is selected from any one of PEDOT:PSS, CuSCN, MnO3, and NiO2.

9. The method for preparing an organic narrow-band photodetector according to any one of claims 1 to 8, characterized in that: The following steps are involved: A positive electrode layer, a hole transport layer, a photoactive layer, an electron transport layer and a negative electrode layer are sequentially arranged on one surface of the base layer; A first reflection layer, a cavity adjustment layer and a second reflection layer are sequentially arranged on a surface of the base layer away from the positive electrode layer to construct a resonance cavity layer.

10. The method for preparing an organic narrow-band photodetector according to claim 9, characterized in that: At least one of the first reflective layer, the cavity adjustment layer, and the second reflective layer is provided by an evaporation method.

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