Small molecule organic photodetector and preparation method thereof

Abstract

A small molecule photodetector comprises one or more photosensitive layers, wherein at least one of the photosensitive layers is a thin film obtained by co-evaporation of a compound having a large conjugated system and other compounds. The present invention co-evaporates the compound having a large conjugated system and other compounds to obtain a mixed or composite thin film, which is then removed through post-processing. This method avoids the high-temperature decomposition that may occur when directly evaporating a compound having a metal-coordinated large conjugated system, making it possible to deposit a thin film on a given substrate. The resulting organic photodetector exhibits excellent photoelectric response. The present invention also relates to a small molecule photodetector array containing the small molecule photodetector.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technology, and in particular to a small molecule light detector and a preparation method thereof. Background Art

[0002] Organic photodetectors have attracted widespread attention due to their low cost and potential advantages in preparing large-area, flexible optoelectronic devices, especially in the fields of spectral detection and imaging.

[0003] Organic photosensitive semiconductors with relatively low molecular weight can be formed into films via vacuum evaporation, making them compatible with current OLED production processes. Compounds with large conjugated systems and their metal complexes, particularly porphyrin derivatives, phthalocyanine derivatives, and porphyrazine derivatives, exhibit excellent optoelectronic properties. Their molecular backbones can be easily modified to adjust the absorption range.

[0004] However, the modifiability of porphyrin, phthalocyanine, and porphyrazine molecules is limited by the vacuum evaporation process. This is because, firstly, the molecular weight of the porphyrin / phthalocyanine / porphyrazine derivative backbone is relatively large, which would be further increased after modification, and the addition of a coordinated metal is required. Secondly, the porphyrin / phthalocyanine / porphyrazine derivative backbone is highly planar and rigid, resulting in strong intermolecular interactions. This, coupled with the interactions between the coordinated metals, significantly increases their sublimation temperature, ultimately making separation and purification using vacuum evaporation impossible, or even impossible to process.

[0005] For example, to broaden the absorption wavelength to the infrared, SR Forrest et al. developed a series of ribbon porphyrin molecules composed of two zinc porphyrin molecules fused together, with a molecular weight exceeding 1000 g / mol. However, they can only be prepared into photodetection devices through solution processing (Adv. Mater. 2010, 22, 2780-2783), which is incompatible with the current OLED production line process.

[0006] Therefore, it is urgent to find a technical solution to solve the defects of the existing technology. Summary of the Invention

[0007] The present invention relates to a small molecule photodetector and its preparation method. A mixed or composite film is obtained by co-depositing a macroconjugated compound and a metal compound in a vacuum, followed by post-processing to remove impurities. This method avoids the potential high-temperature decomposition of directly deposited metal-coordinated macroconjugated compounds, making it possible to deposit thin films on a given substrate. The resulting organic photodetector exhibits excellent photoelectric response.

[0008] An object of the present invention is to provide a small molecule photodetector comprising one or more photosensitive layers, wherein:

[0009] At least one of the photosensitive layers is a thin film obtained by co-depositing a compound having a large conjugated system and other compounds in a vacuum;

[0010] The compound having a large conjugated system is selected from one or more of porphyrin derivatives, phthalocyanine derivatives, porphyrazine derivatives, subporphyrin derivatives, subphthalocyanine derivatives, subporphyrazine derivatives, complexes of porphyrin derivatives, complexes of phthalocyanine derivatives, complexes of porphyrazine derivatives, complexes of subporphyrin derivatives, complexes of subphthalocyanine derivatives, and complexes of subporphyrazine derivatives.

[0011] Furthermore, the porphyrin derivative / phthalocyanine derivative is selected from the following structures:

[0012]

[0013] The complex of the porphyrin derivative / phthalocyanine derivative is selected from the following structures:

[0014]

[0015] in,

[0016] M is selected from one or more of Group II elements, Group III elements, Group IV elements, all transition elements, and compounds thereof;

[0017] M can be selected from but not limited to: Mg, BR 1 、Si(R 1 )2. Ni, Fe, Cu, Co, Ag, Au, Pb, Al, Ga, In, Ti, Ge, Sn, Pt, Zn, Ru, Pd, etc.

[0018] X is independently selected from CR 1 or N; Y is independently selected from O, S, Se or NH;

[0019] R 1 independently selected from hydrogen, deuterium, fluorine, chlorine, bromine, iodine, -CN, -C(=O)R 2 、-Si(R 2 )3、 -N(R 2 )2、-OR 2 、-SR 2 、-S(=O)R 2 、-S(=O)2R 2, C1-20 straight-chain alkyl, C3-20 branched or cyclic alkyl, C2-20 alkenyl or alkynyl group, C6-60 aromatic organic group, C3-60 heteroaromatic organic group; wherein, R 2 Independently selected from C1-60 straight chain alkyl groups, C3-60 branched or cyclic alkyl groups, C2-20 alkenyl or alkynyl groups, C6-60 aromatic organic groups, and C3-60 heteroaromatic organic groups;

[0020] Ar is independently selected from an acetylene group, a diacetylene group, 0, one or more R 1 Substituted vinyl groups, 0, one or more R 1 Aromatic ring system group of substituted C5-50 aromatic ring atoms, 0, one or more R 1 a heteroaromatic ring system group containing substituted C3 to 50 aromatic ring atoms;

[0021] Further, Ar is independently selected from 0, one or more groups R 1 Benzene substituted by 0, one or more groups R 1 Substituted thiophene, 0, one or more groups R 1 Substituted furan, 0, one or more groups R 1 Substituted selenophene, 0, one or more groups R 1 Substituted imide, 0, one or more groups R 1 Substituted thiazole, 0, one or more groups R 1 Substituted thiadiazole, 0, one or more groups R 1 Substituted oxadiazole, 0, one or more groups R 1 Substituted pyridine, 0, one or more groups R 1 Substituted pyrazine, 0, one or more groups R 1 Substituted benzotriazole, 0, one or more groups R 1 Substituted naphthalenes.

[0022] Furthermore, the other compounds are selected from one or more of Group II elements, Group III elements, Group IV elements, all transition elements, and compounds thereof.

[0023] Furthermore, the small molecule photodetector further includes at least one of an electron transport layer and a hole transport layer.

[0024] Further, the electron transport layer is independently selected from organic compound 1, inorganic compound 1, or a combination thereof;

[0025] wherein the organic compound 1 is selected from fullerene and its derivatives, 4,7-diphenyl-1,10-phenanthroline, polyethyleneimine, polyethoxyethyleneimine, 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-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, bis(2-methyl-8-quinolinolato)-4-(phenylphenol)aluminum, 1,3,5-tris[(3-pyridyl)-phenyl-3-yl]benzene, or a mixture or a composite thereof;

[0026] The inorganic compound 1 is selected from zinc oxide, tin oxide, lithium-doped zinc oxide, aluminum-doped zinc oxide, magnesium-doped zinc oxide, gallium-doped zinc oxide, titanium oxide, tantalum oxide, zinc sulfide, chromium sulfide, or a mixture or composite of the above materials.

[0027] Furthermore, the material of the hole transport layer is selected from organic compound 2, inorganic compound 2, or a combination thereof;

[0028] Wherein, the organic compound 2 is selected from one or more of 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"-tris(carbazol-9-yl)triphenylamine, poly(4-butyltriphenylamine), polyvinylcarbazole, polystyrene-N,N'-diphenyl-N,N'-bis-(3-methylphenyl)-(1,1)-biphenyl-4,4'-diamine perfluorocyclobutane, and poly-3,4-ethylenedioxythiophene mixed with polystyrene sulfonate;

[0029] The inorganic compound 2 is selected from tungsten oxide, molybdenum oxide, vanadium oxide, chromium oxide, nickel oxide, copper oxide, cuprous oxide, cuprous thiocyanate, copper sulfide, bismuth sulfide, copper iodide, cuprous iodide, or a mixture or composite of the above materials.

[0030] Another object of the present invention is to provide a method for preparing the above-mentioned small molecule photodetector, characterized in that the preparation method comprises the following steps:

[0031] S1. Heating a compound having a large conjugated system to a temperature of 1 and heating a metal compound to a temperature of 2, simultaneously subliming or evaporating, and depositing the metal compound onto a substrate;

[0032] S2. Annealing is performed under a vacuum environment to form a mixed film.

[0033] Furthermore, the compound having a large conjugated system is in excess relative to the metal compound.

[0034] Furthermore, the heating temperature 1 is 300-600°C; the heating temperature 2 is 100-300°C.

[0035] The heating temperature 1 of the present invention may be, but is not limited to, 300°C, 400°C, 500°C, or 600°C;

[0036] The heating temperature 2 described in the present invention can be, but is not limited to, 100° C., 200° C., or 300° C.;

[0037] And any intermediate value mentioned above, such as 120°C, 250°C, 350°C, 450°C, 550°C, etc.

[0038] Another object of the present invention is to provide an array of small molecule photodetectors, wherein the photosensitive pixels of the array contain the above-mentioned small molecule photodetectors.

[0039] Furthermore, the array of small molecule photodetectors includes a substrate, and the substrate includes a pixel readout circuit composed of silicon-based complementary metal oxide semiconductor transistors or thin film transistors.

[0040] Furthermore, the length of the photosensitive pixel is less than 50 μm.

[0041] Furthermore, the photosensitive pixel further includes an electrode 1, a photosensitive layer and an electrode 2, wherein the electrode 1 is adjacent to the substrate;

[0042] in,

[0043] The length of the photosensitive pixel is consistent with the length of the electrode 1;

[0044] The electrode 1 is patterned;

[0045] The photosensitive layer is not patterned;

[0046] When the electrode 1 is an anode, the electrode 2 is a cathode;

[0047] When the electrode 1 is a cathode, the electrode 2 is an anode.

[0048] Furthermore, the array of small molecule photodetectors further comprises an interface material 1 and an interface material 2; the interface material 1 and the interface material 2 are selected from a hole transport layer or an electron transport layer;

[0049] Wherein, when the interface material 1 is a hole transport layer, the interface material 2 is an electron transport layer;

[0050] When the interface material 1 is an electron transport layer, the interface material 2 is a hole transport layer.

[0051] Another object of the present invention is to provide a method for preparing the above-mentioned small molecule photodetector array, which comprises the following steps:

[0052] (1) Substrate cleaning and readout circuit preparation;

[0053] (2) forming a film of electrode 1 and patterning it by photolithography;

[0054] (3) Preparation of interface material 1;

[0055] (4) Preparation of photosensitive layer;

[0056] (5) Preparation of interface material 2;

[0057] (6) Preparation of electrode 2;

[0058] (7) Preparation of encapsulation layer.

[0059] Furthermore, the preparation of the photosensitive layer is independently selected from one or more of vacuum thermal evaporation, atomic layer deposition, and chemical vapor deposition.

[0060] Furthermore, the preparation of the interface material 1 and the interface material 2 are independently selected from one or more of solution film formation, sol-gel film formation, vacuum thermal evaporation, atomic layer deposition, chemical vapor deposition, electrodeposition, and anodization.

[0061] Furthermore, the preparation of the electrode 1 and the electrode 2 are independently selected from one or more of vacuum thermal evaporation, electron beam evaporation, molecular beam evaporation or plasma sputtering, atomic layer deposition or liquid film formation followed by reduction conversion, electroplating or electrodeposition.

[0062] Furthermore, the encapsulation layer is prepared by one of vacuum thermal evaporation, chemical vapor deposition, atomic layer deposition, plasma sputtering, and liquid film formation.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] The present invention utilizes two independent evaporation sources, one for a macroconjugated compound and the other for a metal compound, to produce a composite thin film through co-evaporation. As the macroconjugated compound and the metal compound gradually deposit onto the photodetector device, a chemical reaction occurs, generating a metal-coordinated macroconjugated compound, thereby forming an ideal photosensitive layer. This method differs from conventional methods of directly depositing metal-coordinated macroconjugated compounds onto the photodetector device through evaporation, and offers the following advantages:

[0065] 1. The co-evaporation method used in this invention uses a heating temperature far lower than that used in traditional methods of directly evaporating and depositing metal-coordinated large conjugated system compounds on photodetector devices. This effectively prevents the risk of high-temperature decomposition or denaturation of the material and greatly reduces energy consumption and risks in the production process.

[0066] 2. The small molecule photodetector prepared by the technical solution of the present invention has a more significant photoelectric response effect than similar products obtained by traditional evaporation, and is a type of organic photodetector with commercial prospects.

[0067] 3. The small molecule photodetector array prepared by the technical solution of the present invention broadens the selection range of the photosensitive layer of the small molecule photodetector array. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 A schematic structural diagram of the small molecule photodetector array in Example 3 is shown.

[0069] Description of the drawings: 201 - pixel readout circuit array chip, 202 - anode array, 203 - hole transport layer, 204 - photosensitive layer, 205 - electron transport layer, 206 - common cathode layer, 207 - encapsulation layer, 208 - connection contact, 209 - pixel readout circuit.

[0070] Figure 2 The EQE graphs of the organic photodetectors obtained in Examples 1-2 and Comparative Examples 1-2 in the test examples are shown. DETAILED DESCRIPTION

[0071] In order to more clearly illustrate the technical solution of the present invention, the following embodiments are listed, but the present invention is not limited thereto.

[0072] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the reagents, materials, etc. used in the following examples are all commercially available unless otherwise specified.

[0073] 2,3-Naphthaldehyde anthocyanin, the precursor of M1, bis(2,2,6,6,-tetramethyl-3,5-heptanedione) lead, lead acetate, and C60 in the examples of the present invention were purchased from Sigma-Aldrich.

[0074] Example 1

[0075] A small molecule photodetector, whose structure from bottom to top is: ITO (100nm) / MoO3 (8nm) / cuprous iodide (2nm) / 2,3-naphthaldehyde anthocyanin:bis(2,2,6,6,-tetramethyl-3,5-heptanedione)lead (1.2:1 composite film, n / n, 40nm) / C60 (40nm) / lithium fluoride (1nm) / Al (100nm).

[0076] The preparation method of the above-mentioned small molecule photodetector is as follows:

[0077] S1. The ITO glass substrate is placed on a washing rack and ultrasonically cleaned using an ultrasonic device. The washing solution is acetone, isopropyl alcohol, detergent, deionized water, and isopropyl alcohol in this order, and then dried in a vacuum oven.

[0078] S2. Place the ITO substrate in an oxygen plasma generator and bombard it with oxygen plasma (O2 plasma) for 2 minutes to completely remove any residual organic matter on the surface of the ITO glass substrate.

[0079] S3. The treated ITO substrate is placed in a vacuum evaporation apparatus, under vacuum conditions of less than 1E-4Pa, the thickness is monitored by a quartz crystal oscillator, and a layer of MoO3 and cuprous iodide is sequentially deposited on the ITO;

[0080] S4. The evaporation source containing 2,3-naphthaldehyde anthocyanin was heated to 400°C, and the evaporation source containing bis(2,2,6,6,-tetramethyl-3,5-heptanedione)lead was heated to 120°C. When the rate stabilized at 1.2:1, the shutter was opened to deposit the composite film.

[0081] S5. Anneal at 120°C for 1 h under a vacuum of less than 1E-4 Pa.

[0082] S6. Sequentially deposit C60, lithium fluoride, and aluminum electrodes. The overlapping portion of the aluminum electrode and the ITO pattern is the device working area;

[0083] S7. After the device is prepared, it is cured and encapsulated with epoxy resin and a glass cover under UV light.

[0084] Example 2

[0085] A small molecule photodetector, whose structure from bottom to top is: ITO (120nm) / MoO3 (10nm) / cuprous iodide (3nm) / compound M1:lead acetate (composite film of ~0.6:1, n / n, 30nm) / C60 (30nm) / lithium fluoride (1nm) / Al (100nm).

[0086] The molecular formula and preparation method of the above compound M1 are as follows:

[0087]

[0088] Under nitrogen, 1.15 g of magnesium turnings (47.1 mmol) was added to 400 ml of n-butanol and heated to 125°C under reflux for 3 h until the magnesium turnings were completely dissolved. After cooling to room temperature, 1.00 g of compound 1 (4.7 mmol) and 4.83 h of 1,2-dicyanobenzene (37.7 mmol) were added to the reaction solution. The mixture was stirred for 5 min and then heated to 125°C under reflux for 48 h. After the reaction was complete, the mixture was returned to room temperature and 1.0 L of anhydrous methanol was added to the reaction solution, which was stirred for 1 h. The reaction mixture was filtered, and the residue was washed three times with methanol, dried, and extracted with toluene. The toluene solution was dried, and the resulting solid was dissolved in 200 ml of trifluoroacetic acid and stirred in the dark for 1 h. The solution was poured into 1.0 L of ice water and filtered. The residue was washed sequentially with sufficient amounts of 5 wt% sodium bicarbonate, deionized water, and methanol, dried, and dissolved in toluene / n-hexane (4:1 v / v). Column chromatography was then used as the eluent, using a mixture of toluene and n-hexane (4:1 v / v to 20:1 v / v). The resulting product was recrystallized from toluene and sublimed to obtain pure Compound M1. Yield = 13.6%.

[0089] The preparation method of the above-mentioned small molecule photodetector is as follows:

[0090] S1. The ITO glass substrate is placed on a washing rack and ultrasonically cleaned using an ultrasonic device. The washing solution is acetone, isopropyl alcohol, detergent, deionized water, and isopropyl alcohol in this order, and then dried in a vacuum oven.

[0091] S2. Place the ITO substrate in an oxygen plasma generator and bombard it with oxygen plasma (O2 plasma) for 2 minutes to completely remove any residual organic matter on the surface of the ITO glass substrate.

[0092] S3. The treated ITO substrate is placed in a vacuum evaporation apparatus, under vacuum conditions of less than 1E-4Pa, the thickness is monitored by a quartz crystal oscillator, and a layer of MoO3 and cuprous iodide is sequentially deposited on the ITO;

[0093] S4. Heat the evaporation source containing M1 to 450°C and the evaporation source of lead acetate to 280°C until the rate stabilizes at ~0.6:1, then open the shutter and deposit the composite film;

[0094] S5. Anneal at 125°C for 1 h under a vacuum of less than 1E-4 Pa.

[0095] S6. Sequentially deposit C60, lithium fluoride, and aluminum electrodes. The overlapping portion of the aluminum electrode and the ITO pattern is the device working area;

[0096] S7. After the device is prepared, it is cured and encapsulated with epoxy resin and a glass cover under UV light.

[0097] Example 3

[0098] A small molecule photodetector array comprises, from bottom to top, a pixel readout circuit array chip 201 fabricated on a single-crystal silicon substrate and composed of silicon-based complementary metal oxide semiconductor transistors (MOSFETs). Each pixel readout circuit is connected to an anode array 202 that defines the pixel size. Above the electrode array are a hole transport layer 203, a photosensitive layer 204, an electron transport layer 205, a common cathode layer 206, and an encapsulation layer 207. Component 201 includes a connection contact 208 for the top electrode and a single pixel readout circuit 209 connected to 202. Components 203 through 207 are continuous across the entire array, eliminating the need for patterning between pixels.

[0099] Among them, the patterned anode array 202 is a gold electrode with a thickness of 100 nm, the hole transport layer 203 is a stacked structure of a molybdenum oxide film (8 nm) and a cuprous iodide film (2 nm), the material composition of the photosensitive layer 204 refers to the photosensitive layer (40 nm) prepared in steps S4-S5 in Example 1, the electron transport layer 205 is a C60 film (40 nm), the common cathode layer 206 is an indium tin oxide electrode (100 nm), and the encapsulation layer 207 is an epoxy resin.

[0100] The structural diagram of the small molecule photodetector array is shown in Figure 1 shown.

[0101] The array has a pixel size of 25 μm and a pixel number of 1×256 or 1×512, and imaging tests have been conducted on it. Figure 2 The organic photodiode array shown, in which pixels are defined only by the bottom electrode, can be used for digital camera applications with high pixel density.

[0102] The method for preparing the above-mentioned small molecule photodetector array comprises the following steps:

[0103] S1. The pixel readout circuit composed of silicon-based complementary metal oxide semiconductor transistors was transferred to the evaporation glove box. -7 Under vacuum conditions of torr, a gold electrode array of specified thickness was deposited by thermal evaporation;

[0104] S2-S4. The preparation method of the molybdenum oxide film, cuprous iodide, photosensitive layer film, C60 film, and indium tin oxide electrode is the same as that in Example 1.

[0105] S5. After the device is prepared, it is cured and encapsulated with epoxy resin under ultraviolet light.

[0106] Example 4

[0107] The device structure, materials used, and device manufacturing method in this embodiment are the same as those in Example 3. The only difference is that the pixel readout circuit array chip 201 in Example 3 is replaced with a pixel readout circuit composed of thin film transistors (TFTs) on a glass substrate.

[0108] Comparative Example 1

[0109] A small molecule photodetector has a structure from bottom to top of: ITO (100 nm) / MoO3 (8 nm) / cuprous iodide (2 nm) / 2,3-naphthaldehyde anthocyanin lead (40 nm) / C60 (40 nm) / lithium fluoride (1 nm) / Al (100 nm); wherein the 2,3-naphthaldehyde anthocyanin lead is prepared by refluxing 2,3-naphthaldehyde anthocyanin:lead chloride (4:1 n / n) in 1-pentanol at 50°C for 24 hours (reference: Materials Letters 2003, 57, 3302-3304).

[0110] The preparation method of the above-mentioned small molecule photodetector is the same as that of Example 1, except that S4 is changed to: heating an evaporation source filled with 2,3-naphthaldehyde anthocyanin lead to 500° C., then opening the baffle and depositing a 40 nm thick 2,3-naphthaldehyde anthocyanin lead film.

[0111] Comparative Example 2

[0112] A small molecule photodetector has the following structure, from bottom to top: ITO (100nm) / MoO3 (8nm) / cuprous iodide (3nm) / a lead complex of compound M1 (30nm) / C60 (30nm) / lithium fluoride (1nm) / Al (100nm). The lead complex of compound M1 is prepared by reacting M1 with lead acetate in toluene at 60°C for 24 hours. The crude product is then filtered, washed with toluene, and dried to obtain a crude product. This product is insoluble and infusible, making further purification impossible (Reference: Technical Physics 2015, 60, 877-884).

[0113] The preparation method of the above-mentioned small molecule photodetector is the same as that of Example 1, except that S4 is changed to: heating an evaporation source containing the above-mentioned product to 550° C., then opening the baffle and depositing a 30 nm thick thin film of the lead complex of compound M1.

[0114] Test Case

[0115] The photoelectric performance of the small molecule photodetectors prepared in Examples 1-2 and Comparative Examples 1-2 was tested, and the results are shown in Table 1. The testing methods are well known to those skilled in the art, and all samples were tested under the same experimental conditions.

[0116] Table 1 Device performance of small molecule photodetectors

[0117]

[0118] As can be seen from Table 1, the device performance of the small molecule photodetector obtained in Examples 1-2 is significantly better than the device performance of the small molecule photodetector obtained in Comparative Examples 1-2.

[0119] In addition, the spectral response rate test data of the above small molecule photodetector is as follows Figure 1 As shown. Figure 1 It can be seen that the small molecule photodetector prepared by the co-evaporation method adopted in Examples 1-2 is less likely to denature the material due to the lower heating temperature, and the resulting spectral response rate is higher; while in Comparative Examples 1-2, the heating temperature is significantly higher (>500°C), which significantly increases the risk of material denaturation and decomposition, resulting in a very low spectral response rate of the small molecule photodetector in the comparative example.

[0120] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0121] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A small molecule photodetector, characterized in that: The small molecule photodetector comprises one or more photosensitive layers, wherein: At least one of the photosensitive layers is a composite thin film obtained by co-depositing a compound having a large conjugated system and a metal compound in a vacuum; during the gradual deposition of the compound having a large conjugated system and the metal compound on the photodetector device, a chemical reaction occurs to generate a compound having a large conjugated system coordinated by the metal, thereby forming the photosensitive layer; The compound having a large conjugated system is selected from one or more of porphyrin derivatives, phthalocyanine derivatives, porphyrazine derivatives, porphyrin sub-derivatives, phthalocyanine sub-derivatives and porphyrazine sub-derivatives.

2. The small molecule photodetector according to claim 1, characterized in that: The porphyrin derivative / phthalocyanine derivative is selected from the following structures: X is independently selected from CR 1 or N; Y is independently selected from O, S, Se or NH; R 1 independently selected from hydrogen, deuterium, fluorine, chlorine, bromine, iodine, -CN, -C(=O)R 2 、-Si(R 2 )3、-N(R 2 )2、-OR 2 、-SR 2 、-S(=O)R 2 、-S(=O)2R 2 , C1-20 straight-chain alkyl, C3-20 branched or cyclic alkyl, C2-20 alkenyl or alkynyl group, C6-60 aromatic organic group, C3-60 heteroaromatic organic group; wherein, R 2 Independently selected from C1-60 straight chain alkyl groups, C3-60 branched or cyclic alkyl groups, C2-20 alkenyl or alkynyl groups, C6-60 aromatic organic groups, and C3-60 heteroaromatic organic groups; Ar is independently selected from acetylene groups, diacetylene groups, 0, one or more R 1 Substituted vinyl groups, 0, one or more R 1 The aromatic ring system group of substituted C5-50 aromatic ring atoms is substituted by 0, one or more R 1 A heteroaromatic ring system group having substituted C3-50 aromatic ring atoms.

3. The small molecule photodetector according to claim 2, characterized in that: Ar is independently selected from 0, one or more groups R 1 Substituted benzene, 0, one or more groups R 1 Substituted thiophene, 0, one or more groups R 1 Substituted furan, 0, one or more groups R 1 Substituted selenophene, 0, one or more groups R 1 Substituted imide, 0, one or more groups R 1 Substituted thiazole, 0, one or more groups R 1 Substituted thiadiazole, 0, one or more groups R 1 Substituted oxadiazole, 0, one or more groups R 1 Substituted pyridine, 0, one or more groups R 1 Substituted pyrazine, 0, one or more groups R 1 Substituted benzotriazole, 0, one or more groups R 1 Substituted naphthalenes.

4. The small molecule photodetector according to claim 1, characterized in that: The metal compound is selected from one or more compounds of Group II elements, Group III elements, Group IV elements, and all transition elements.

5. The small molecule photodetector according to claim 1, characterized in that: The small molecule photodetector further includes at least one of an electron transport layer and a hole transport layer.

6. The small molecule photodetector according to claim 5, characterized in that: The electron transport layer is independently selected from an organic compound 1, an inorganic compound 1, or a combination thereof; wherein the organic compound 1 is selected from fullerene and its derivatives, 4,7-diphenyl-1,10-phenanthroline, polyethyleneimine, polyethoxyethyleneimine, 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-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, bis(2-methyl-8-quinolinolato)-4-(phenylphenol)aluminum, 1,3,5-tris[(3-pyridyl)-phenyl-3-yl]benzene, or a mixture or composite of the above materials; The inorganic compound 1 is selected from zinc oxide, tin oxide, lithium-doped zinc oxide, aluminum-doped zinc oxide, magnesium-doped zinc oxide, gallium-doped zinc oxide, titanium oxide, tantalum oxide, zinc sulfide, chromium sulfide, or a mixture or composite of the above materials.

7. The small molecule photodetector according to claim 5, characterized in that: The material of the hole transport layer is selected from organic compound 2, inorganic compound 2, or a combination thereof; Wherein, the organic compound 2 is selected from one or more of 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"-tris(carbazol-9-yl)triphenylamine, poly(4-butyltriphenylamine), polyvinylcarbazole, polystyrene-N,N'-diphenyl-N,N'-bis-(3-methylphenyl)-(1,1)-biphenyl-4,4'-diamine perfluorocyclobutane, and poly-3,4-ethylenedioxythiophene mixed with polystyrene sulfonate; The inorganic compound 2 is selected from tungsten oxide, molybdenum oxide, vanadium oxide, chromium oxide, nickel oxide, copper oxide, cuprous oxide, cuprous thiocyanate, copper sulfide, bismuth sulfide, copper iodide, cuprous iodide, or a mixture or composite of the above materials.

8. The method for preparing the small molecule photodetector according to any one of claims 1 to 7, characterized in that: The preparation method of the small molecule photodetector comprises the following steps: S1. Heating the compound having a large conjugated system to temperature 1 and heating the other compounds to temperature 2, and simultaneously subliming or evaporating and depositing them onto the substrate; during the gradual deposition of the compound having a large conjugated system and the metal compound on the photodetector device, a chemical reaction occurs to generate a metal-coordinated large conjugated system compound, thereby forming a photosensitive layer; S2. Annealing is performed under a vacuum environment to form a mixed film.

9. The method for preparing a small molecule photodetector according to claim 8, characterized in that: The compound having a large conjugated system is in excess relative to the metal compound.

10. The method for preparing a small molecule photodetector according to claim 8, characterized in that: The heating temperature 1 is 300-600°C; the heating temperature 2 is 100-300°C.

11. An array of small molecule photodetectors, characterized in that: The photosensitive pixels of the array of small molecule photodetectors contain the small molecule photodetectors according to any one of claims 1-7.

12. The array of small molecule photodetectors according to claim 11, characterized in that: The array of the small molecule photodetector includes a substrate, and the substrate includes a pixel readout circuit composed of silicon-based complementary metal oxide semiconductor transistors or thin film transistors.

13. The array of small molecule photodetectors according to claim 11, characterized in that: The length of the photosensitive pixel is less than 50 μm.

14. The array of small molecule photodetectors according to claim 11, characterized in that: The photosensitive pixel further includes an electrode 1, a photosensitive layer and an electrode 2, wherein the electrode 1 is adjacent to the substrate; in, The length of the photosensitive pixel is consistent with the length of the electrode 1; The electrode 1 is patterned; The photosensitive layer is not patterned; When the electrode 1 is an anode, the electrode 2 is a cathode; When the electrode 1 is a cathode, the electrode 2 is an anode.

15. The array of small molecule photodetectors according to claim 14, characterized in that: The array of small molecule photodetectors further includes an interface material 1 and an interface material 2; the interface material 1 and the interface material 2 are selected from a hole transport layer or an electron transport layer; Wherein, when the interface material 1 is a hole transport layer, the interface material 2 is an electron transport layer; When the interface material 1 is an electron transport layer, the interface material 2 is a hole transport layer.

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