Narrow-band-gap small-molecule material and short-wave infrared organic photoelectric detector prepared from narrow-band-gap small-molecule material

Abstract

The invention relates to a narrow-band-gap small-molecule material and a short-wave infrared organic photoelectric detector prepared from the narrow-band-gap small-molecule material, the device structure is a reverse device structure, the light absorption range of the small-molecule material exceeds 1000nm, and the characteristics of the material structure ensure that the photoelectric detector has relatively high light responsivity and high response speed in a short-wave infrared region; the requirement of rapid real-time imaging is met; the invention further relates to processing of the short-wave infrared photoelectric detector array device, and nondestructive inspection application of a silicon-based integrated circuit is realized based on the array device.

Description

Technical Field

[0001] The invention belongs to the technical field of organic photoelectric synaptic devices, and relates to a short-wave infrared organic photodetector that can be used for nondestructive testing of silicon-based integrated circuits, in particular to a narrow-bandgap small molecule material and a short-wave infrared organic photodetector prepared therefrom. Background Art

[0002] Organic photodetectors are devices that use organic semiconductor materials as the photoresponse layer. Currently, research on organic photodetectors focuses on materials and devices that achieve high-performance infrared response. However, there are few materials with excellent photoresponse performance in the short-wavelength infrared region (SWIR: 1-3μm). Currently, commercial short-wave infrared photodetectors are based on inorganic semiconductor materials such as Ge, InGaAs, PbS, and HgCdTe, which contain toxic heavy metal elements and high processing costs. In addition, the effective area of ​​the detector array needs to be precisely aligned with the external readout circuit, which limits the reduction of the pixel unit size. If the photoresponse material is directly processed on the readout circuit, the device will be damaged and fail during operation due to the different thermal expansion coefficients of the various layers of materials. Compared with inorganic semiconductor materials, organic semiconductor materials have strong light absorption ability, and thin films with nanometer thickness can achieve good light absorption. In addition, organic semiconductor materials have the characteristics of intrinsic flexibility and large-area processing in solution. When they are prepared on the readout circuit, the problem of device failure caused by internal stress can be effectively avoided.

[0003] After searching, the Chinese patent publication number: CN118243706A discloses a non-destructive perspective visual inspection equipment, including a host computer, an X-ray generator, an X-ray detector, a top plate, a detection plate, a bottom plate and a self-inspection mechanism. The self-inspection mechanism includes a hydraulic rod, a moving frame, a simulation substrate, defective components and simulation pins. X-rays can pass through the object at the detection opening, and the intensity difference before and after the X-rays is imaged to determine whether the object under test has defects. The hydraulic rod can drive the simulation substrate to move to the detection opening through the moving frame. Defective components are arranged on the simulation substrate, and the simulation pins around the simulation substrate can adjust the state. When the electromagnet is energized, the metal rod will be subjected to magnetic force and retract into the hollow tube. At this time, the metal rod leaves the fixed rod and the simulation pin becomes disconnected. After emitting and receiving X-rays, the imaged image is used to determine whether the disconnected pins and defective components are detected, thereby verifying whether the function of the detection equipment is normal, so as to facilitate timely repair and maintenance.

[0004] Silicon-based integrated circuits (ICs) are made of transistors, capacitors, resistors and other components on a single-crystal silicon substrate and connected together through wiring. In actual use, they are often in a closed shell, and damage may occur during the actual integration process. In order to detect damage, the commonly used method is non-destructive testing equipment based on x-ray detectors, but x-rays have great radiation damage to the human body, and it is necessary to develop new detectors in other bands for non-destructive detection to achieve non-destructive testing of silicon-based integrated circuits.

[0005] Based on the absorption spectrum of single crystal silicon, its absorption coefficient in the short-wave infrared band is very low, which allows short-wave infrared light to penetrate the silicon substrate and realize damage detection of electronic components and wiring connections on the silicon substrate. The advantage of using this detection method is that on the one hand, it can avoid the use of radioactive x-rays, and on the other hand, it can avoid the problem of low resolution caused by the current use of photothermal imaging technology.

[0006] Organic short-wave infrared photodetectors have advantages in photoelectric imaging applications due to their large-area processability and excellent photoresponse performance. The current challenge is how to develop organic semiconductor materials with excellent photoresponse performance to ensure that the photodetector has excellent photoresponsivity, specific detection rate, and fast response speed in the short-wave infrared region, ensuring that the device has high sensitivity and fast imaging speed in imaging applications, and realizing a new technology for non-destructive testing of silicon-based integrated circuits. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a narrow bandgap small molecule material and a short-wave infrared organic photodetector prepared therefrom, which can have excellent photoelectric response performance in the short-wave infrared region and can be used for non-destructive testing of silicon-based integrated circuits.

[0008] The present invention solves the technical problem by adopting the following technical solutions:

[0009] A narrow bandgap small molecule material, the molecular structure of which is shown in Formula I:

[0010]

[0011] Wherein, X1, X2, X3 and X4 are each independently selected from the chalcogenide elements: O, S, Se, Te;

[0012] Y1, Y2, Y3 and Y4 are each independently selected from the halogen elements: F, Cl, Br, I;

[0013] The side chain groups R1, R2, R3 and R4 are each independently selected from branched alkyl side chains.

[0014] Furthermore, the side chain groups R1, R2, R3 and R4 are each independently selected from at least one of the following side chain groups:

[0015]

[0016] An application of the narrow bandgap small molecule material in a short-wave infrared organic photodetector.

[0017] A short-wave infrared organic photodetector prepared from a narrow bandgap small molecule material is a reverse device structure, comprising a substrate, a bottom electrode, an electron or hole transport layer, a photosensitive layer, a hole or electron transport layer and a top electrode coated sequentially from bottom to top.

[0018] Moreover, the substrate is a rigid glass substrate, a flexible polystyrene or a polyurethane;

[0019] The bottom electrode is indium tin oxide or silver nanowire;

[0020] The electron transport layer is zinc oxide, tin oxide, naphthalene diimide and its derivatives, perylene diimide and its derivatives, 4,7-diphenyl-1,10-phenanthroline, polyethylene imine, polyethoxyethylene imine, 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline, [9,9-dioctylfluorene-9,9-bis(N,N-dimethylaminopropyl)fluorene], bromo-[9,9-dioctylfluorene-9,9-bis(N,N-dimethylaminopropyl)fluorene], 8-hydroxyquinoline lithium, 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl)benzene, bis(2-methyl-8-quinoline)-4-(phenylphenol)aluminum, 1,3,5-tri[(3-pyridyl)-phenyl-3-yl]benzene, or a mixture or composite of the above materials;

[0021] The photosensitive layer includes an acceptor material and a donor material, wherein the acceptor material is a narrow bandgap small molecule material as shown in Formula I, and the donor material is at least one of PCE10, PM6, D18, and PBDB-T;

[0022] The hole transport layer is at least one of polyethylenedioxythiophene-polystyrene sulfonate, molybdenum oxide, 4,4'-cyclohexylbis[N,N'-bis(4-methylphenyl)aniline], N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine, N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-2,7-diamino-9,9-spirobifluorene, 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4',4"-tri(carbazole-9-yl)triphenylamine, poly(4-butyltriphenylamine), polyvinylcarbazole, polystyrene-N,N'-diphenyl-N,N'-bis-(3-methylphenyl)-(1,1)-biphenyl-4,4'-diamineperfluorocyclobutane;

[0023] The top electrode is at least one of silver, aluminum and gold.

[0024] Moreover, the absorption spectrum range of the acceptor material exceeds 1000nm to ensure that it absorbs light signals in the short-wave infrared light region of 1000-3000nm; the absorption spectrum of the donor material is in the visible light region and can produce an energy level difference with the acceptor material, that is, the lowest unoccupied orbital and the highest occupied orbital of the donor material are higher than those of the acceptor material.

[0025] Moreover, it is a photodiode type device structure, including: a conductive ITO glass electrode, zinc oxide, a photosensitive layer, molybdenum oxide and a silver electrode coated in sequence from bottom to top;

[0026] The conductive ITO glass electrode comprises a glass substrate and a conductive ITO film, and a layer of conductive ITO film is plated on the upper surface of the glass substrate.

[0027] Moreover, the transmittance of the glass substrate is not less than 94%, the thickness of zinc oxide is 20-40 nanometers, the thickness of the photosensitive layer is 90-120 nanometers, the thickness of molybdenum oxide is 5-20 nanometers, the thickness of the silver electrode is 80-120 nanometers, and the size of a single device is 0.2×0.2 cm.

[0028] An application of the narrow bandgap small molecule material in photodetector arrays for real-time imaging of short-wave infrared light and non-destructive testing of silicon-based integrated circuits.

[0029] A photodetector array device is processed in the following steps:

[0030] (1) Cleaning of substrate: Place the substrate on a rack and clean it with soapy water, deionized water, acetone, and isopropanol in sequence; before use, blow away the residual solvent on the substrate with N2, and use plasma cleaning to further remove the residual organic matter on the substrate surface;

[0031] (2) Preparation of zinc oxide electron transport layer: 90-110 mg zinc acetate dihydrate, 80-120 mL 2-methoxyethanol and 15-30 μL ethanolamine were mixed, stirred and dissolved at room temperature, and filtered before use; then spin coating was performed, and after spin coating, heating and annealing were performed on a hot plate to obtain a zinc oxide layer; then the substrate was transferred to a glove box for spin coating of an active layer;

[0032] (3) Processing of the photosensitive layer: Dissolve the donor and the acceptor in chlorobenzene solvent at a mass ratio of 1:0.5 to 1:2.5, stir, and then spin coat; after the active layer is spin-coated, anneal on a hot plate;

[0033] (4) Thermal evaporation of hole transport layer: Place the substrate with the active layer spin-coated on the mask plate, and evaporate molybdenum oxide at locations other than the common electrode area;

[0034] (5) Evaporation of top electrode;

[0035] (6) The array device is connected to the external leads;

[0036] (7) Photodetector array area packaging.

[0037] The advantages and positive effects of the present invention are:

[0038] 1. The present invention solves two major challenges currently faced by short-wave infrared organic photodetectors: one is the low external quantum conversion efficiency (EQE) in the short-wave infrared region, which results in low performance indicators such as the responsivity and specific detection rate of the photodetector in this wavelength range. The main reason for the low EQE is the low efficiency of the generation and collection of photogenerated carriers in the device, as well as the competition between the photothermal conversion process and the photoelectric process caused by non-radiative transitions. The second challenge is that the dark current of photodetectors based on narrow-bandgap materials is large, making it difficult to obtain a high specific detection rate. The large dark current is due to the low charge injection barrier generated by the narrow-bandgap material when the device is operating under an external bias. At the same time, the free charges generated by thermal excitation in the narrow-bandgap material in the dark state will also increase the dark current level. Therefore, the present invention provides new material structures and high-performance photodetector devices based on solving the challenges of current short-wave infrared organic photodetectors.

[0039] 2. The narrow bandgap small molecule receptor material disclosed in the present invention adopts an A-π-D-π-A structure. Such a molecular structure can form a charge transfer state between the structural units within the molecule, thereby realizing the absorption of short-wave infrared light. In addition, the introduction of chalcogen elements from oxygen, sulfur, selenium to tellurium atoms can gradually red-shift the absorption spectrum of the material. At the same time, the oxygen atoms introduced in the molecular side chain groups can form non-covalent bond interactions with the chalcogen elements in the molecular conjugated skeleton, thereby locking the rotation of the two conjugated units connected by a single bond in the molecular skeleton, thereby improving the planarity and rigidity of the molecular skeleton, which is conducive to the transfer of charges. In addition, the strong non-covalent bond interactions within the molecule can effectively suppress the electron-phonon coupling in the molecule, and reducing the electron-phonon coupling can effectively suppress the non-radiative transition process and improve the light response performance of the optoelectronic device.

[0040] 3. The light absorption range of the narrow bandgap small molecule material in the present invention exceeds 1000nm. The short-wave infrared organic photodetector device processed by solution spin coating can work under zero bias or low bias, and can obtain a responsivity and specific detection rate comparable to some currently commercial short-wave infrared photodetectors. In addition, the response speed of the photodetector is about 1μs, indicating that the short-wave infrared organic photodetector in the present invention is expected to be used in the field of real-time imaging detection.

[0041] 4. The short-wave infrared organic photodetector in the present invention can be processed into a photodetector array and integrated on the backplane of a thin film transistor (TFT) by solution processing. In this way, only the exposed electrodes on the TFT backplane need to be arrayed, and no photosensitive layer needs to be patterned by photolithography, and finally an arrayed image sensor array device is obtained. In addition, the size of the pixel unit in the arrayed device can be adjusted by changing the shape and size of the exposed electrodes on the TFT backplane, thereby adjusting the imaging resolution of the obtained image. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the UV-visible absorption spectrum of the narrow bandgap small molecule material M1 synthesized in Example 1 of the present invention.

[0043] Figure 2 Schematic diagram of the energy level structure of the narrow bandgap small molecule material M1 synthesized in Example 1 of the present invention.

[0044] Figure 3 This is a device structure diagram of the short-wave infrared organic photodetector in Examples 2-5 of the present invention.

[0045] Figure 4 This is a responsivity curve diagram of the short-wave infrared organic photodetector under different test bias conditions in Example 2 of the present invention.

[0046] Figure 5 This is a curve diagram of the specific detection rate of the short-wave infrared organic photodetector under different test bias conditions in Example 2 of the present invention.

[0047] Figure 6 This is a responsivity curve diagram of the short-wave infrared organic photodetector under different test bias conditions in Example 3 of the present invention.

[0048] Figure 7 This is a curve diagram of the specific detection rate of the short-wave infrared organic photodetector under different test bias conditions in Example 3 of the present invention.

[0049] Figure 8 This is a responsivity curve diagram of the short-wave infrared organic photodetector under different test bias conditions in Example 4 of the present invention.

[0050] Fig. 9 This is a curve diagram of the specific detection rate of the short-wave infrared organic photodetector under different test bias conditions in Example 4 of the present invention.

[0051] Fig.10 This is a responsivity curve diagram of the short-wave infrared organic photodetector under different test bias conditions in Example 5 of the present invention.

[0052] Fig.11 This is a curve diagram of the specific detection rate of the short-wave infrared organic photodetector under different test bias conditions in Example 5 of the present invention.

[0053] Fig.12 This is a diagram of a real-time imaging test architecture based on a short-wave infrared organic photodetector array provided in Example 6 of the present invention.

[0054] Fig.13 This is a test diagram for nondestructive testing of silicon-based integrated circuits according to Example 6 of the present invention.

[0055] Reference numerals

[0056] 1-silver electrode, 2-molybdenum oxide, 3-photosensitive layer, 4-zinc oxide, 5-conductive ITO glass electrode. DETAILED DESCRIPTION

[0057] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0058] Example 1

[0059] A narrow band gap small molecule material M1 based on the A-π-D-π-A structure, the structural formula of which is shown in the figure below;

[0060]

[0061] In the molecular structure, X1, X2, X3 and X4 are selected from S or Se, thereby obtaining molecules M1-1, M1-2, M1-3, and M1-4. The synthesis method of the molecule is synthesized with reference to the following literature method: J. Lee, S.-J. Ko, H. Lee, J. Huang, Z. Zhu, M. Seifrid, J. Vollbrecht, V V Rus, A. Karki, H. Wang, K. Cho, T.-Q. Nguyen, G C Bazan, Side-Chain Engineering of Nonfullerene Acceptors for Near-Infrared Organic Photodetectors and Photovoltaics. ACS Energy Lett. 4, 1401-1409 (2019).

[0062] Figure 1 The absorption spectra of four molecules are displayed. The absorption range exceeds 1000nm and the absorption edge extends to 1300nm. Therefore, the detection of short-wave infrared light can be achieved based on these materials. Figure 2 The corresponding highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy level positions of M1-1, M1-2, M1-3, and M1-4 materials are shown.

[0063] Example 2

[0064] A method for preparing a short-wave infrared organic photodetector made of narrow-bandgap small molecule materials, wherein the device structure is a reverse structure, comprising: a conductive ITO glass electrode 5 / an electron transport layer of zinc oxide 4 (ZnO) / a photosensitive layer 3 (PCE10: M1-1) / a hole transport layer of molybdenum oxide 2 (MoO3) / a silver electrode 1 (Ag), wherein the conductive ITO glass electrode 5 comprises a glass substrate and a conductive ITO film, and a layer of conductive ITO film is plated on the upper surface of the glass substrate.

[0065] The device processing steps are as follows:

[0066] (1) Cleaning of the substrate: The substrate is a glass substrate with ITO. The substrate is placed on a rack and cleaned with soapy water, deionized water, acetone, and isopropanol in turn. Each liquid is used twice, and each time is half an hour. Before use, the residual solvent on the substrate is blown away with N2, and plasma cleaning is performed for 1 minute to further remove the residual organic matter on the substrate surface.

[0067] (2) Preparation of zinc oxide electron transport layer: Prepare zinc oxide precursor, mix 100 mL zinc acetate dihydrate, 90 mL 2-methoxyethanol, and 28 μ ethanolamine, stir and dissolve at room temperature, and filter before use. The conditions for spin coating on the substrate are: a rotation speed of 4000 r / min, 30 s. After spin coating, heat and anneal on a hot plate at 200 ° C for 30 min to obtain a ZnO layer. Next, transfer the substrate to a glove box to spin coat the active layer.

[0068] (3) Processing of photosensitive layer: The concentration of active layer solution is 15 mg / mL, the solvent is chlorobenzene, the mass ratio of donor to acceptor is 1:1.5, and the solution is stirred for at least three hours. During spin coating, the speed is 2000 r / min, the time is 30 s, and 18 μL is taken each time. After the active layer is spin-coated, anneal it on a hot plate at 100 °C for 10 min.

[0069] (4) Thermal evaporation of hole transport layer: Place the substrate with the active layer spin-coated on the mask plate, and evaporate 15nm thick molybdenum oxide in the area other than the common electrode area. The evaporation condition is that the vacuum chamber pressure is less than 2×10 -4 Pa, the evaporation rate is less than 0.2nm / s.

[0070] (5) Evaporation of top electrode: Also in vacuum chamber with pressure less than 2×10 -4 The evaporation started at 100 nm and the thickness was 100 nm. The effective area of ​​the photodetector was 0.04 cm 2 .

[0071] Figure 3 The device structure of the reverse device is shown.

[0072] Example 3

[0073] The device structure and device processing method in this embodiment are the same as those in Embodiment 2. The difference is that the photosensitive layer material used in Embodiment 3 is PCE10:M1-2, and the mass ratio of the donor to the acceptor is 1:1.8.

[0074] Example 4

[0075] The device structure and device processing method in this embodiment are the same as those in embodiment 2. The difference is that the photosensitive layer material used in embodiment 4 is PCE10:M1-3, and the mass ratio of donor to acceptor is 1:1.8.

[0076] Example 5

[0077] The device structure and device processing method in this embodiment are the same as those in embodiment 2. The difference is that the photosensitive layer material used in embodiment 5 is PCE10:M1-4, and the mass ratio of donor to acceptor is 1:1.5.

[0078] Example 6

[0079] This embodiment demonstrates a method for processing an arrayed short-wave infrared organic photodetector. The photodetector array is processed on a thin-film transistor (TFT) backplane purchased from LinkZill, model SC-X-A064-2203, 64×64 pixel unit, active area size of 12.8×12.8mm, pixel size of 200×200μm. The device structure is also an inverted structure, and the other materials and device processing methods are the same as those in Example 4.

[0080] After the photodetector array is processed, a signal reading device purchased from LinkZill is used to obtain the image obtained by the photodetector. At the same time, the damage in the silicon-based integrated circuit can be detected.

[0081] Test Example 1

[0082] After the short-wave infrared organic photodetector was processed, its photoelectric response performance was characterized. For Examples 2-5, after the device was processed, the dark current (J d ), responsivity (R) and specific detectivity (D sh *), the test references for the above three indicators: T.Liu, Z.Jia, Y.Song, N.Yu, Q.Lin, C.Li, Y.Jia, H.Chen, S.Wang, Y.Wei, Y.Lin, F.Huang, Z.Tang, Y.Li, L.Meng, H.Huang, Near Infrared Self-Powered Organic Photodetectors with a Record Responsivity Enabled by Low TrapDensity. Adv.Funct.Mater.2023,33,2301167. The test parameters of Examples 2-5 are summarized in Table 1:

[0083] Table 1 Dark current (J) of short-wave infrared organic photodetectors of Examples 2-5 d ), responsivity (R) and specific detectivity (D*)

[0084]

[0085] Comparison of key parameters of short-wave infrared organic photodetectors: responsivity (R) and specific detectivity (D sh *), R and D of the short-wave infrared photodetectors processed in Examples 2-5 at 0, -0.1, -1 and -2 V bias voltages sh *The results are shown in Figure 4-11First, under a -2V bias, in the main visible light region and part of the near-infrared region, the responsivity of the material system based on PCE10:M1-1 (Example 2) drops rapidly after the wavelength exceeds 940nm, which is consistent with the absorption change of the material ( Figure 4 ). In the transition region from NIR to SWIR, the responsivity of PCE10:M1-3 (Example 4) reaches a peak, and the highest responsivity of Example 2-5 is 0.54 AW. -1 (990nm). Entering the SWIR region, Example 4 still has a relatively high responsivity, wherein at 1000nm, the responsivity can still reach 0.53AW -1 ( Figure 8 ). The responsivity of Example 3 and Example 5 is consistent with the change of the material absorption spectrum ( Figure 6 , 10 ). In addition, assuming that the device shot noise makes the main contribution to the dark current, the D sh *. Comparing the specific detection rates of the four material systems at 0V bias, they can exceed 10 from the visible light to the SWIR region. 13 Jones, showing good light detection capabilities ( Figure 5 , 7 , 9, 11). As the applied bias voltage increases, the D sh * gradually decreases, indicating that the detection limitation is the dark current characteristic, not the photocurrent. The device remains stable even at -2V bias (corresponding to an applied electric field of 20kVcm -1 ), in the wavelength range exceeding 1000nm, D sh *Still remains at 10 12 Jones, indicating that the device has good SWIR light response capability.

[0086] Test Example 2

[0087] Testing short-wave infrared organic photodetectors for non-destructive probing of silicon-based integrated circuits. Fig.12 The architecture of the test system is demonstrated, including the photodetector array device, the matrix readout system, and the mobile terminal that displays the imaging picture via wireless connection.

[0088] Fig.13 This is a test diagram for nondestructive testing of silicon-based integrated circuits according to Example 6 of the present invention, wherein a is type 1, including a lossless area and a lossy area; b is type 2; c is type 3; and d is for increasing the light intensity to increase image contrast.

[0089] In the non-destructive testing of silicon-based integrated circuits, three types of integrated circuits are placed on the photodetector array. Through the irradiation of 1050nm light, a clear image of the integrated circuit chip part can be obtained. Fig.13 a shows the intact circuit area (A1) and the damaged area (A2), indicating that defects in silicon-based integrated circuits can be detected. When the circuit lead coverage area is reduced, the photodetector array can still obtain the corresponding shape ( Fig.13 b, c). In addition, by increasing the light intensity, an image with higher contrast can be obtained ( Fig.13 d) In addition, in practical applications, it is necessary to reduce the size of pixel units in array devices to obtain clearer images.

[0090] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A narrow bandgap small molecule material, characterized in that: The general molecular structure is shown in Formula I: Wherein, X1, X2, X3 and X4 are each independently selected from the chalcogenide elements: O, S, Se, Te; Y1, Y2, Y3 and Y4 are each independently selected from the halogen elements: F, Cl, Br, I; The side chain groups R1, R2, R3 and R4 are each independently selected from branched alkyl side chains.

2. The narrow bandgap small molecule material according to claim 1, characterized in that: The side chain groups R1, R2, R3 and R4 are each independently selected from at least one of the following side chain groups:

3. An application of the narrow bandgap small molecule material according to claim 1 in a short-wave infrared organic photodetector.

4. A short-wave infrared organic photodetector made of the narrow bandgap small molecule material according to claim 1, characterized in that: It is an inverted device structure, including a substrate, a bottom electrode, an electron or hole transport layer, a photosensitive layer, a hole or electron transport layer and a top electrode coated in sequence from bottom to top.

5. The short-wave infrared organic photodetector prepared from a narrow bandgap small molecule material according to claim 4, characterized in that: The substrate is a rigid glass substrate, a flexible polystyrene or a polyurethane; The bottom electrode is indium tin oxide or silver nanowire; The electron transport layer is zinc oxide, tin oxide, naphthalene diimide and its derivatives, perylene diimide and its derivatives, 4,7-diphenyl-1,10-phenanthroline, polyethylene imine, polyethoxyethylene imine, 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline, [9,9-dioctylfluorene-9,9-bis(N,N-dimethylaminopropyl)fluorene], bromo-[9,9-dioctylfluorene-9,9-bis(N,N-dimethylaminopropyl)fluorene], 8-hydroxyquinoline lithium, 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl)benzene, bis(2-methyl-8-quinoline)-4-(phenylphenol)aluminum, 1,3,5-tri[(3-pyridyl)-phenyl-3-yl]benzene, or a mixture or composite of the above materials; The photosensitive layer includes an acceptor material and a donor material, wherein the acceptor material is a narrow bandgap small molecule material as shown in Formula I, and the donor material is at least one of PCE10, PM6, D18, and PBDB-T; The hole transport layer is at least one of polyethylenedioxythiophene-polystyrene sulfonate, molybdenum oxide, 4,4'-cyclohexylbis[N,N'-bis(4-methylphenyl)aniline], N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine, N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-2,7-diamino-9,9-spirobifluorene, 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4',4"-tri(carbazole-9-yl)triphenylamine, poly(4-butyltriphenylamine), polyvinylcarbazole, polystyrene-N,N'-diphenyl-N,N'-bis-(3-methylphenyl)-(1,1)-biphenyl-4,4'-diamineperfluorocyclobutane; The top electrode is at least one of silver, aluminum and gold.

6. The short-wave infrared organic photodetector prepared from a narrow bandgap small molecule material according to claim 5, characterized in that: The absorption spectrum range of the acceptor material exceeds 1000nm to ensure that it absorbs light signals in the short-wave infrared light region of 1000-3000nm; the absorption spectrum of the donor material is in the visible light region and can produce an energy level difference with the acceptor material, that is, the lowest unoccupied orbital and the highest occupied orbital of the donor material are both higher than those of the acceptor material.

7. The short-wave infrared organic photodetector prepared from a narrow bandgap small molecule material according to claim 4, characterized in that: The device structure is a photodiode type, including: a conductive ITO glass electrode, zinc oxide, a photosensitive layer, molybdenum oxide and a silver electrode coated in sequence from bottom to top; The conductive ITO glass electrode comprises a glass substrate and a conductive ITO film, and a layer of conductive ITO film is plated on the upper surface of the glass substrate.

8. The short-wave infrared organic photodetector prepared from a narrow bandgap small molecule material according to claim 7, characterized in that: The transmittance of the glass substrate is not less than 94%, the thickness of zinc oxide is 20-40 nanometers, the thickness of the photosensitive layer is 90-120 nanometers, the thickness of molybdenum oxide is 5-20 nanometers, the thickness of the silver electrode is 80-120 nanometers, and the size of a single device is 0.2×0.2 cm.

9. An application of the narrow bandgap small molecule material according to claim 1 in a photodetector array for real-time imaging of short-wave infrared light and non-destructive testing of silicon-based integrated circuits.

10. A photodetector array according to claim 9, characterized in that: The device processing steps are as follows: (1) Cleaning of substrate: Place the substrate on a rack and clean it with soapy water, deionized water, acetone, and isopropanol in sequence; before use, blow away the residual solvent on the substrate with N2, and use plasma cleaning to further remove the residual organic matter on the substrate surface; (2) Preparation of zinc oxide electron transport layer: 90-110 mg zinc acetate dihydrate, 80-120 mL 2-methoxyethanol and 15-30 μL ethanolamine were mixed, stirred and dissolved at room temperature, and filtered before use; then spin coating was performed, and after spin coating, heating and annealing were performed on a hot plate to obtain a zinc oxide layer; then the substrate was transferred to a glove box for spin coating of an active layer; (3) Processing of the photosensitive layer: Dissolve the donor and the acceptor in chlorobenzene solvent at a mass ratio of 1:0.5 to 1:2.5, stir, and then spin coat; after the active layer is spin-coated, anneal on a hot plate; (4) Thermal evaporation of hole transport layer: Place the substrate with the active layer spin-coated on the mask plate, and evaporate molybdenum oxide at locations other than the common electrode area; (5) Evaporation of top electrode; (6) The array device is connected to the external leads; (7) Photodetector array area packaging.

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