A colloidal quantum dot material, a preparation method thereof, and applications thereof in a colloidal quantum dot photodetector and an array

Abstract

The present invention relates to a colloidal quantum dot material, which comprises colloidal quantum dots and a colloidal quantum dot ligand, and the colloidal quantum dots are encapsulated within the colloidal quantum dot ligand. The colloidal quantum dot ligand has the following structural formula (I). On the one hand, the colloidal quantum dot ligand with this structure can help the colloidal quantum dots disperse in solution, thereby realizing solution processing. On the other hand, after the colloidal quantum dot material forms a film, the colloidal quantum dot ligand can be decomposed into a short-chain structure through a simple annealing process, thus eliminating the traditional multiple ligand exchange and elution processes. The array of colloidal quantum dot photodetectors prepared based on the technical solution of the present invention has an ideal external quantum efficiency.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technologies, and particularly to a colloidal quantum dot material, a preparation method thereof, and applications thereof in colloidal quantum dot photodetectors and arrays. Background Art

[0002] Colloidal quantum dot photodetectors are one of the important branches of photodetectors. Due to their low cost, potential advantages in fabricating large-area and flexible optoelectronic devices, and excellent optoelectronic efficiency, they have received extensive attention in fields such as solar cells, light-emitting diodes, lasers, detectors, and displays. In particular, they have great application potential in the fields of spectral detection and imaging.

[0003] Generally, colloidal quantum dot materials include core colloidal quantum dots and colloidal quantum dot ligands wrapped outside. During the preparation process, long carbon chain oleic acid is required as a ligand for colloidal quantum dots to ensure solubility, and it can also enhance the resistance of colloidal quantum dots themselves to external water, light, and heat, thereby stabilizing the performance of colloidal quantum dots. However, on the other hand, when colloidal quantum dots are dried into a film on a device, these long-chain ligands will in turn hinder the charge transfer between quantum dots, affecting the final performance of the device, especially the external quantum efficiency (EQE) of the device.

[0004] To solve this problem, usually, post-treatment methods such as ligand exchange are required to replace the above-mentioned long carbon chain oleic acid ligands with short carbon chain ligands, and the replaced long-chain ligands also need to be rinsed off with a solvent. This process is usually not completely replaced, and the process is relatively complex and not suitable for large-scale industrial production.

[0005] Therefore, there is an urgent need to find a technical solution to solve the defects existing in the prior art. Summary of the Invention

[0006] The present invention discloses a colloidal quantum dot material, which includes a colloidal quantum dot ligand with a special structure. On the one hand, the colloidal quantum dot ligand with this structure can help the colloidal quantum dots disperse in solution, thereby realizing solution processing; on the other hand, after the colloidal quantum dot material forms a film, the colloidal quantum dot ligand can be decomposed into a short-chain structure through a simple annealing process, thus eliminating the traditional multiple ligand exchange and elution processes.

[0007] In addition, an array of colloidal quantum dot photodetectors prepared based on the technical solution of the present invention has an ideal external quantum efficiency.

[0008] An object of the present invention is to provide a colloidal quantum dot material.

[0009] A colloidal quantum dot material, which comprises colloidal quantum dots and a colloidal quantum dot ligand, and the colloidal quantum dots are encapsulated within the colloidal quantum dot ligand;

[0010] The colloidal quantum dot ligand has the following structural formula (I) or (II):

[0011]

[0012] Wherein,

[0013] R 1 is independently selected from a hydrogen atom, a deuterium atom, a halogen atom, -OH, -SH, -CN, -SCN, -C(=O)R 3 , -Si(R 3 )3, -N(R 3 )2, -OR 3 , -SR 3 , -S(=O)R 3 , -S(=O)2R 3 , a C1-20 straight-chain alkyl or its derivative, a C3-20 branched-chain alkyl or its derivative, a C3-20 cyclic alkyl or its derivative, a C2-20 ether group, a C2-20 oligoethyleneoxy group, a C2-20 alkenyl or alkynyl group, a C6-60 aryl group or its derivative, a C3-60 heteroaryl group or its derivative; or a group formed by covalently connecting any two identical / different groups or multiple identical / different groups;

[0014] R 3 is independently selected from a C1-60 straight-chain alkyl or its derivative, a C3-60 branched chain or its derivative, a C3-60 cyclic alkyl or its derivative, a C2-20 alkenyl or alkynyl group, a C6-60 aryl group or its derivative, a C3-60 heteroaryl group or its derivative.

[0015] R 1 The specific structure may include a combination of various groups involved above. For example, in some cases, the specific structure of R 1 may be

[0016] In some cases, the specific structure of R 1 may be

[0017] In some cases, the specific structure of R 1 may be

[0018] In some cases, the specific structure of R 1 may be

[0019] R 2 is selected from one or more alkylene groups or their derivatives;

[0020] Preferably, in one or more embodiments, R 2 may but is not limited to be -CH2-, -CH2-CH2-, -CH2-CH(CH3)-, -CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-, -CH2-CH2-CH(CH3)-CH2-, etc.

[0021] However, the number of alkylene groups should not be too large, because during the subsequent annealing process, the ligand of the colloidal quantum dots will be thermally decomposed into small molecule substances. A too long carbon chain will affect the removal of small molecules.

[0022] Generally, the ligand of the colloidal quantum dots is connected to the colloidal quantum dots through a mercapto group or an ionic bond.

[0023] Further, the colloidal quantum dots are selected from one or more of GaP, ZnSe, ZnS, CuO, CuO2, CuS, CuSe, CuInS2, CuInSe2, CuInGaSe, CuInGaS, Ge, PbS, PbSe, HgTe or AgBiS2.

[0024] Preferably, the mass ratio of the colloidal quantum dots to the ligand of the colloidal quantum dots is 1:1 - 1:3.

[0025] Further, the particle size of the colloidal quantum dots is 2 - 30 nm.

[0026] Another object of the present invention is to provide a preparation method of the above-mentioned colloidal quantum dot material, which includes a preparation method of the ligand of the colloidal quantum dots, and the preparation method of the ligand of the colloidal quantum dots is as follows:

[0027] S1. React an alkyl alcohol with in an alkaline environment to obtain intermediate 1;

[0028] S2. React intermediate 1 with in an alkaline environment to obtain intermediate 2;

[0029] S3. First react intermediate 2 with an amine source by heating, then cool down, react in an acidic environment, and after filtration, concentration and purification, obtain a ligand of the colloidal quantum dots with structural formula (I);

[0030] or

[0031] S1. React an alkyl alcohol with in an alkaline environment to obtain intermediate 1;

[0032] S2. React intermediate 1 with React under alkaline conditions to obtain intermediate product 2;

[0033] S3. React the intermediate product 2 with an amine source by heating first, then cool down, and react under acidic conditions. After filtration, concentration, and purification, a colloidal quantum dot ligand with structural formula (I) is obtained; or

[0034] S4. Ionize the colloidal quantum dot ligand with structural formula (I) in S3 to obtain a colloidal quantum dot ligand with structural formula (II).

[0035] The amine source can be but is not limited to diethylamine, triethylamine, and the like.

[0036] Further, the alkyl alcohol is a monohydric alcohol.

[0037] The alkyl alcohol is a monohydric alcohol containing the above R 1 group.

[0038] Further, in step S3, the heating temperature is 140 - 200 °C.

[0039] Another object of the present invention is to provide a colloidal quantum dot reagent, which includes the above-mentioned colloidal quantum dot material and at least one solvent.

[0040] The solvent can be but is not limited to: one or a mixture of two or more of toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, tetrahydrofuran, petroleum ether, methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, tert-butanol, dichloromethane, chloroform, acetonitrile, cyclohexane, and acetone.

[0041] Another object of the present invention is to provide a colloidal quantum dot film, which is formed by annealing the above-mentioned colloidal quantum dot reagent.

[0042] In the annealing process, the colloidal quantum dot ligand with structural formula (I) will decompose at high temperature, and the products are volatile olefins, carbon dioxide, and thiol substances.

[0043] For example, as shown in the following specific reaction equation:

[0044]

[0045] Another object of the present invention is to provide a colloidal quantum dot photodetector, which includes a photosensitive layer, and the photosensitive layer contains the above-mentioned colloidal quantum dot film.

[0046] Further, the colloidal quantum dot photodetector sequentially includes a substrate, a lower electrode array, a lower electrode interface layer, a photosensitive layer, an upper electrode interface layer, and a common electrode layer.

[0047] Further, the lower electrode interface layer, the photosensitive layer, the upper electrode interface layer, and the common electrode layer are all continuous structures within the colloidal quantum dot photodetector region.

[0048] Further, the lower electrode interface layer, the photosensitive layer, the upper electrode interface layer, and the common electrode layer are not patterned between pixels.

[0049] Further, the lower electrode interface layer and / or the upper electrode interface layer are selected from metal oxides or metal sulfides.

[0050] Further, the lower electrode interface layer completely covers the lower electrode array.

[0051] Further, the substrate includes a pixel readout circuit composed of silicon-based complementary metal oxide semiconductor transistors or thin film transistors.

[0052] Another object of the present invention is to provide an array of colloidal quantum dot photodetectors, which includes a plurality of photosensitive pixels, and the colloidal quantum dot photodetectors described above are contained in the photosensitive pixels.

[0053] Further, the array of colloidal quantum dot photodetectors includes a lower electrode array, and the lower electrode array is patterned.

[0054] Further, the lower electrode array is periodically arranged.

[0055] Another object of the present invention is to provide a light-emitting diode device, which includes the above-mentioned colloidal quantum dot material.

[0056] Another object of the present invention is to provide an organic solar cell device, which includes the above-mentioned colloidal quantum dot material.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] 1. In the technical solution of the present invention, on the one hand, the colloidal quantum dot ligand with this structure can help the colloidal quantum dots disperse in the solution, thus realizing solution processing; on the other hand, after the colloidal quantum dot material forms a film, the colloidal quantum dot ligand can be decomposed into a short-chain structure through a simple annealing process, thus omitting the traditional multiple ligand exchange and elution processes.

[0059] 2. The array of colloidal quantum dot photodetectors prepared based on the technical solution of the present invention has an ideal external quantum efficiency. Description of the Drawings

[0060] Figure 1 Shows the device structures of the colloidal quantum dot photodetectors based on Examples 1-3 and the comparative example.

[0061] Figure 2 Shows a top - view structure of the substrate of the colloidal quantum dot photodetector array based on Examples 1 - 3 and the comparative example (the encapsulation layer is omitted), which is covered with a pixel - defining layer. The cross - sectional view cut along the dashed line corresponds to Figure 1 .

[0062] Figure 3 Shows a top - view structure of the substrate of the colloidal quantum dot photodetector array based on Examples 1 - 3 and the comparative example (the encapsulation layer and the pixel - defining layer are omitted).

[0063] Figure 4 Shows a comparison chart of the external quantum efficiency of the colloidal quantum dot photodetector array based on Examples 1 - 3 and the comparative example.

[0064] Figure 5 Shows another technical solution of the present invention, that is, the array structure in the case of high - density pixels.

[0065] Reference numerals:

[0066] Glass substrate - 200, metal pin - 201, lower electrode array (ITO) - 202, lower electrode interface layer (ZnO nanoparticle layer) - 203, photosensitive layer - 204, upper electrode interface layer - 205, common electrode layer - 206, top - electrode contact - 207, pixel - defining layer - 208, encapsulation layer - 209.

[0067] Pixel read - out circuit - 301, lower electrode array - 302, electrode interface layer - 303, colloidal quantum dot photosensitive layer - 304, small - molecule interface layer + blend layer - 305, common electrode layer - 306, encapsulation layer - 307. Detailed implementation manners

[0068] To more clearly illustrate the technical solutions of the present invention, the following examples are listed, but the present invention is not limited thereto.

[0069] The experimental methods used in the following examples are all conventional methods unless otherwise specified; the reagents, materials, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

[0070] The preparation methods of the monomers, intermediates, and products involved in the embodiments of the present invention are as follows.

[0071] Preparation example

[0072]

[0073]

[0074] (1) Synthesis of Compound 1

[0075] Under nitrogen protection, 20.00 g of 2-methyl-2-hexanol (172.1 mmol), 55.82 g of N,N'-carbonyldiimidazole (344.2 mmol), and 19.31 g of potassium hydroxide (344.2 mmol) were transferred to a 2.0 L single-necked round-bottom flask. 800 mL of toluene was added, and the mixture was stirred for 5 min. Then the temperature was raised to 60 °C and the reaction was carried out for 12 h. After the reaction, the mixture was returned to room temperature. It was filtered, and the filter residue was rinsed with dichloromethane. The filtrate was concentrated, and extracted three times with dichloromethane and deionized water. The organic phase was successively dried, filtered, and concentrated. Column chromatography was carried out using petroleum ether:ethyl acetate = 50:1 (v / v) as the eluent. 24.6 g of the pure product of compound 1 was obtained, with a yield of 68.0%.

[0076] (2) Synthesis of compound 2

[0077] Under nitrogen protection, 10.00 g of compound 1 (47.6 mmol), 3.33 g of 2-hydroxyethyl disulfide (21.6 mmol), and 4.85 g of potassium hydroxide (86.5 mmol) were transferred to a 500 L single-necked round-bottom flask. 200 mL of tetrahydrofuran was added, and the mixture was stirred for 5 min. Then the temperature was raised to 60 °C and the reaction was carried out for 12 h. After the reaction, the mixture was returned to room temperature. It was filtered, and the filter residue was rinsed with petroleum ether. The filtrate was concentrated, and extracted three times with petroleum ether and deionized water. The organic phase was successively dried, filtered, and concentrated. Column chromatography was carried out using petroleum ether:dichloromethane = 10:1 (v / v) as the eluent. 5.77 g of the pure product of compound 2 was obtained, with a yield of 60.9%.

[0078] (3) Synthesis of compound 3

[0079] Under nitrogen protection, 5.50 g of compound 2 (12.5 mmol) and 12.69 g of triethylamine (125.4 mmol) were dissolved in 100 mL of dimethyl sulfoxide. After stirring for 5 min, the temperature was raised to 100 °C and the reaction was carried out for 4 h. After the reaction was completed, the temperature was lowered to 0 °C and stirred for 15 min while maintaining the temperature. 2.0 mol / L hydrochloric acid aqueous solution was added dropwise to the reaction solution until the pH of the solution was equal to 1, and the temperature of the solution was kept below 5 °C, and stirred for 1 h. Then it was returned to room temperature and stirred for 2 h. After the reaction, it was repeatedly extracted with 10 L of water and 500 mL of petroleum ether. The organic phase was successively dried, filtered, and concentrated. Vacuum distillation gave 4.01 g of compound 3, with a yield of 72.6%.

[0080] (4) Synthesis of compound 2-1

[0081] Under nitrogen protection, 10.00 g of compound 2-0 (70.3 mmol), 22.80 g of N,N'-carbonyldiimidazole (140.6 mmol), and 7.89 g of potassium hydroxide (140.6 mmol) were transferred to a 1.0 L single-necked round-bottom flask. 300 mL of toluene was added, and the mixture was stirred for 5 min. Then the temperature was raised to 60 °C, and the reaction was carried out for 12 h. After the reaction, the mixture was cooled to room temperature. It was filtered, and the filter cake was rinsed with dichloromethane. The filtrate was concentrated, and then extracted three times with dichloromethane and deionized water. The organic phase was successively dried, filtered, and concentrated. Column chromatography was carried out using petroleum ether:ethyl acetate = 50:1 (v / v) as the eluent. 10.76 g of compound 2-1 was obtained, with a yield of 64.8%.

[0082] (5) Synthesis of compound 2-2

[0083] Under nitrogen protection, 10.00 g of compound 2-1 (42.3 mmol), 2.97 g of 2-hydroxyethyl disulfide (19.2 mmol), and 4.32 g of potassium hydroxide (77.0 mmol) were transferred to a 500 L single-necked round-bottom flask. 150 mL of tetrahydrofuran was added, and the mixture was stirred for 5 min. Then the temperature was raised to 60 °C, and the reaction was carried out for 12 h. After the reaction, the mixture was cooled to room temperature. It was filtered, and the filter cake was rinsed with petroleum ether. The filtrate was concentrated, and then extracted three times with petroleum ether and deionized water. The organic phase was successively dried, filtered, and concentrated. Column chromatography was carried out using petroleum ether:dichloromethane = 10:1 (v / v) as the eluent. 4.33 g of pure compound 2-2 was obtained, with a yield of 45.9%.

[0084] (6) Synthesis of compound 2-3

[0085] Under nitrogen protection, 4.3 g of compound 2-2 (9.8 mmol) and 9.92 g of triethylamine (98.0 mmol) were dissolved in 100 mL of dimethyl sulfoxide. After stirring for 5 min, the temperature was raised to 100 °C, and the reaction was carried out for 4 h. After the reaction was completed, the temperature was lowered to 0 °C, and the mixture was stirred for 15 min while maintaining the temperature. 2.0 mol / L hydrochloric acid aqueous solution was added dropwise to the reaction solution until the pH of the solution was equal to 1, while keeping the solution temperature below 5 °C, and the mixture was stirred for 1 h. Then it was returned to room temperature and stirred for 2 h. After the reaction, it was repeatedly extracted three times with 1 L of water and 150 mL of petroleum ether. The organic phase was successively dried, filtered, and concentrated. Vacuum distillation gave 3.66 g of compound 2-3, with a yield of 75.8%.

[0086] (7) Synthesis of compound 3-1

[0087] Under nitrogen protection, 10.00 g of compound 3-0 (70.3 mmol), 22.80 g of N,N'-carbonyldiimidazole (140.6 mmol), and 7.89 g of potassium hydroxide (140.6 mmol) were transferred to a 1.0 L single-necked round-bottom flask. 300 mL of toluene was added, and the mixture was stirred for 5 min, then heated to 60 °C and reacted for 12 h. After the reaction, it was cooled to room temperature. Filtration was carried out, and the filter residue was rinsed with dichloromethane. The filtrate was concentrated, and extracted three times with dichloromethane and deionized water. The organic phase was successively dried, filtered, and concentrated. Column chromatography was performed using petroleum ether:ethyl acetate = 50:1 (v / v) as the eluent. 9.66 g of compound 3-1 was obtained, with a yield of 58.2%.

[0088] (8) Synthesis of compound 3-2

[0089] Under nitrogen protection, 9.50 g of compound 3-1 (40.2 mmol), 2.82 g of 2-hydroxyethyl disulfide (18.3 mmol), and 4.10 g of potassium hydroxide (73.1 mmol) were transferred to a 500 L single-necked round-bottom flask. 120 mL of tetrahydrofuran was added, and the mixture was stirred for 5 min, then heated to 60 °C and reacted for 12 h. After the reaction, it was cooled to room temperature. Filtration was carried out, and the filter residue was rinsed with petroleum ether. The filtrate was concentrated, and extracted three times with petroleum ether and deionized water. The organic phase was successively dried, filtered, and concentrated. Column chromatography was performed using petroleum ether:dichloromethane = 10:1 (v / v) as the eluent. 4.68 g of pure compound 3-2 was obtained, with a yield of 52.2%.

[0090] (9) Synthesis of compound 3-3

[0091] Under nitrogen protection, 4.50 g of compound 3-2 (10.3 mmol) and 10.38 g of triethylamine (102.6 mmol) were dissolved in 50 mL of dimethyl sulfoxide. After stirring for 5 min, the temperature was raised to 100 °C and the reaction was carried out for 4 h. After the reaction was completed, the temperature was lowered to 0 °C and stirred for 15 min while maintaining the temperature. 2.0 mol / L hydrochloric acid aqueous solution was added dropwise to the reaction solution until the pH of the solution was equal to 1, and the temperature of the solution was kept below 5 °C and stirred for 1 h. Then it was returned to room temperature and stirred for 2 h. After the reaction, it was repeatedly extracted three times with 500 mL of water and 100 mL of petroleum ether. The organic phase was successively dried, filtered, and concentrated. Vacuum distillation gave 3.29 g of compound 3-3, with a yield of 65.6%.

[0092] Examples and comparative examples

[0093] The above-mentioned compound 3, compound 2-3, and compound 3-3 were dispersed in a mixed solvent of acetone: ethanol = 1: 3 (v / v) at a concentration of 100 mg / ml, respectively, and the PbS quantum dots (purchased from Suzhou Xingshuo, with a particle size of about 4-5 nm) powders of equal mass to compound 3, compound 2-3, and compound 3-3 were added respectively, and the liquid phase was removed by centrifugation at 8000 rpm, and then the mixed solvent of acetone: ethanol = 1: 3 (v / v) was added, and the liquid phase was removed by centrifugation again after repeated shaking for 30 s, and the lead sulfide colloidal quantum dots wrapped by compound 3, compound 2-3, and compound 3-3 were obtained after low temperature drying. The obtained product was dispersed in n-octane at a concentration of 150 mg / mL to prepare a reagent for standby use, and the above-mentioned colloidal quantum dot materials were recorded as D1-D3 respectively.

[0094] The above colloidal quantum dot materials D1-D3 are respectively taken and applied to the field of colloidal quantum dot photodetectors. After annealing and film formation, a photosensitive layer is formed, and a colloidal quantum dot photodetector is correspondingly formed, which is set as Examples 1-3.

[0095] The above-purchased Starry Lead Sulfide Colloidal Quantum Dots (particle size of 4-5nm) were prepared into colloidal quantum dot material D' by spin coating and ligand exchange in sequence according to the literature (Nature Materials 2011, vol 10, p765), and applied to the field of colloidal quantum dot photodetectors to form colloidal quantum dot photodetectors, which were set as comparative examples.

[0096] The structures of the colloidal quantum dot photodetectors in the above-mentioned embodiments 1-3 and the comparative examples are specifically described in Figure 1 .

[0097] The device structures of specific embodiments 1-3 and comparative examples are as follows from bottom to top: glass substrate 200 (0.7 mm) / lower electrode array 202 (ITO) (100 nm) / lower electrode interface layer 203 (nickel oxide) (30 nm) / photosensitive layer 204 (colloidal quantum dot film formed by D1-D3 / D') (200 nm) / upper electrode interface layer 205 (fullerene) (30 nm) / silver electrode 206 (100 nm) / encapsulation layer 209 (epoxy resin). The exposed area of 202 is limited by the pixel definition layer 208 (photoresist SU8) and is led out to the outside of 209 through the contact 201. Similarly, the silver electrode 206 is also led out to the outside of 209 through the contact 207.

[0098] The colloidal quantum dot photodetectors in the above-mentioned embodiments 1-3 and the comparative example are used to form an array of colloidal quantum dot photodetectors. The pixel size of the array of colloidal quantum dot photodetectors is limited to 1.6×1.6 mm by the insulating pixel definition layer. 2, the pixel pitch is 2.4 mm, and the number of pixels is 4×8.

[0099] Figure 2 and Figure 3 shows an overall top view of the colloidal quantum dot photodetector array based on Examples 1-3 and the comparative example.

[0100] Figure 2 shows a top view structure of the substrate of the colloidal quantum dot photodetector array based on Examples 1-3 and the comparative example, which is covered with a pixel definition layer, and the working area of the pixel is defined by the patterned bottom electrode. There is a metal lead between 201 and 202, which is covered by the insulating pixel definition layer; Figure 3 shows a top view structure of the substrate of the colloidal quantum dot photodetector array based on Examples 1-3 and the comparative example, in which the pixel definition layer is removed, clearly showing the connection of the electrode pins of the pixel array substrate to the bottom electrode.

[0101] The preparation method of the above-mentioned colloidal quantum dot photodetector and its array based on Examples 1-3 and the comparative example includes the following steps:

[0102] S1. Place the substrate on the developing rack and ultrasonically clean it for 1 min using an ultrasonic cleaner, with isopropyl alcohol as the detergent;

[0103] S2. Sputter a 30-nm nickel oxide layer on the cleaned lower electrode array through a mask.

[0104] S3. Spin-coat a colloidal quantum dot material of D1-D3.

[0105] S4. Anneal in vacuum at 150 °C for 20 min to form a colloidal quantum dot thin film with a specified thickness (200 nm).

[0106] S5. Use a laser to remove the residual zinc oxide and colloidal quantum dot thin film above the pins to expose the metal pins and top electrode contacts.

[0107] S6. Deposit a specified thickness of fullerene in sequence through a patterned mask.

[0108] S7. Deposit a silver electrode with a specified thickness through another patterned mask.

[0109] S8. After device preparation, cure and encapsulate with epoxy resin in ultraviolet light.

[0110] S9. Further, prepare the above-mentioned colloidal quantum dot photodetector into a colloidal quantum dot photodetector array.

[0111] The preparation steps of the comparative example are replaced at S3-S4 with:

[0112] S3'-S4'. After D' is spin-coated into a film, it is rinsed twice with a mixed solution of methanol: diethyl sulfide = 98:2 (v / v), and this step is repeated four times until the film thickness reaches the specified thickness of 200 nm.

[0113] From the comparison of the steps of the above-mentioned preparation method of the colloidal quantum dot photodetector device based on Examples 1-3 and Comparative Example, it can be seen that the former is simpler and the formation of the photosensitive layer can be achieved by direct annealing.

[0114] Test Case

[0115] The relevant test images of the photoelectric performance of the prepared array of colloidal quantum dot photodetectors based on Examples 1-3 and Comparative Examples are as follows: Figure 4 The relevant EQE data are shown in Table 1. The test methods used for each index are not conventional means well known to those skilled in the art.

[0116] Table 1 EQE values of arrays of colloidal quantum dot photodetectors based on Examples 1-3 and Comparative Examples

[0117] Sample EQE@400nm EQE@1550nm Example 1 56.6％ 26.4％ Example 2 49.6％ 21.0％ Example 3 55.3％ 28.4％ Comparative Example 42.2％ 16.0％

[0118] from Figure 4 As can be seen from Table 1, the device performance of the comparative example is poorer than that of Examples 1-3. This is because: repeated ligand exchange accumulates more film defects, resulting in a significant decrease in the external quantum efficiency of the comparative example.

[0119] The above results illustrate the advancement of the technical solution of the present invention.

[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 present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0121] For example, Figure 5 As shown, a pixel readout circuit composed of a thin film transistor (TFT) on a glass substrate or a pixel readout circuit composed of a silicon-based complementary metal oxide semiconductor transistor (MOSFET) on a single crystal silicon substrate is used as a substrate to meet the imaging requirements of high-density pixels.

[0122] For another example, by using 202 with a relatively high light reflectance and 207 with a relatively high light transmittance, the photosensitive direction of the array is changed to be incident from 210. Or by using 202 and 207 both with relatively high light transmittance simultaneously, the array is made to have the characteristic of photosensitivity on both sides.

[0123] In addition, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A colloidal quantum dot material, characterized in that, The colloidal quantum dot material includes colloidal quantum dots and a colloidal quantum dot ligand, and the colloidal quantum dots are encapsulated within the colloidal quantum dot ligand; The colloidal quantum dot ligand has the following structural formula (I): wherein, R 1 is independently selected from a branched alkyl having 3 to 7 carbon atoms and a cyclic alkyl having 3 to 9 carbon atoms; R 2 -CH2-, -CH2-CH2-, -CH2-CH(CH3)-, -CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-, -CH2-CH2-CH(CH3)-CH2- 2. The colloidal quantum dot material according to claim 1, wherein The colloidal quantum dots are selected from one or more of GaP, ZnSe, ZnS, CuO, CuO2, CuS, CuSe, CuInS2, CuInSe2, CuInGaSe, CuInGaS, Ge, PbS, PbSe, HgTe, or AgBiS2.

3. The colloidal quantum dot material according to claim 2, wherein The particle size of the colloidal quantum dots is 2 - 30 nm.

4. The preparation method of the colloidal quantum dot material according to any one of claims 1-3, characterized in that, It includes a preparation method of the colloidal quantum dot ligand, and the preparation method of the colloidal quantum dot ligand is as follows: S1. React an alkyl alcohol with under an alkaline condition to obtain Intermediate 1; S2. React the intermediate 1 with under an alkaline condition to obtain intermediate 2; S3. First, react the intermediate product 2 with an amine source by heating, then cool down, react in an acidic environment, and after filtration, concentration, and purification, obtain the colloidal quantum dot ligand with the structural formula (I); The alkyl alcohol is a monohydric alcohol containing an R 1 group.

5. The preparation method of the colloidal quantum dot material according to claim 4, characterized in that, In step S3, the heating temperature is 140 - 200 °C.

6. A colloidal quantum dot reagent, characterized in that, It includes the colloidal quantum dot material according to any one of claims 1 - 3, and at least one solvent.

7. A method for preparing a colloidal quantum dot thin film, characterized in that, The colloidal quantum dot thin film is formed by annealing the colloidal quantum dot reagent according to claim 6.

Images