Preparation method and application of quantum dot ink
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUAZHONG UNIV OF SCI & TECH
- Filing Date
- 2026-02-03
- Publication Date
- 2026-06-09
Smart Images
Figure CN122168071A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of optoelectronic materials technology, and in particular to a method for preparing quantum dot ink and its application. Background Technology
[0002] Currently, PbS and PbSe quantum dots are typically prepared using organic phase synthesis methods. This involves synthesizing quantum dots through reactions with corresponding reactants in an organic solvent environment with coordination properties. These organic solvents include one or more of oleic acid and oleylamine. Excess organic ligands coat the surface of the PbS and PbSe quantum dots to maintain the stability of the quantum dot solution and facilitate subsequent operations. However, the presence of these organic ligands hinders carrier transport and makes it difficult to form a dense film structure after quantum dot deposition. Therefore, the prepared PbS and PbSe quantum dots usually require ligand exchange treatment before they can be used for subsequent film deposition and application in photodetectors. However, even after conventional ligand exchange quantum dot film deposition, it is still difficult to simultaneously solve the problems of insufficient film density and high dark current, failing to meet the performance requirements of photodetectors. Existing strategies for modifying PbS and PbSe quantum dot light-absorbing layers, such as ligand engineering, crystal plane selective passivation, and high-concentration halogen passivation, are either complex in operation and costly in implementation, or they are difficult to simultaneously achieve film densification and dark current suppression. Some strategies also have poor adaptability to PbS and PbSe quantum dots of different sizes. As a result, the light-absorbing layers modified by these strategies either have a loose film structure that affects carrier transport, or the dark current of the device is still at a high level, making it difficult for the corresponding infrared detectors to meet the requirements of practical applications and severely limiting their application space.
[0003] Therefore, developing a simple and low-cost modification method to simultaneously achieve film densification and dark current suppression in PbS and PbSe quantum dot light-absorbing layers of different sizes is a key requirement in the field of optoelectronic detection devices. Even existing methods for ink treatment of PbS and PbSe quantum dots often suffer from cumbersome operations and limited effectiveness, making it difficult to consider the compatibility with different quantum dot sizes. They cannot efficiently improve film densification or effectively reduce the dark current of the corresponding infrared detectors, resulting in limited overall performance improvement and failing to meet the performance requirements of infrared detectors in practical applications. Summary of the Invention
[0004] Based on the problems existing in the prior art, this invention provides a method for preparing quantum dot ink and its application. It achieves synergistic modification of PbS and PbSe quantum dot light-absorbing layers and dark current suppression by initially passivating quantum dots with 1-octadecene and then introducing indium salts into a lead halide ligand exchange system. This method aims to overcome the technical difficulties of existing PbS and PbSe quantum dot light-absorbing layer modification strategies, which are complex, costly, and difficult to simultaneously achieve film densification and efficient dark current suppression. Using this method, high-performance infrared detectors with dense films and low dark current can be prepared, significantly improving their photoelectric detection performance. Compared with traditional modification strategies, this invention has the core advantages of simple operation, concise process, and low cost. It can also efficiently adapt to PbS and PbSe quantum dots of different sizes, breaking through the application limitations of traditional modification schemes and possessing significant technical innovation and practicality.
[0005] To achieve the above objectives, the first aspect of this invention proposes a method for preparing quantum dot ink, the specific technical solution of which is as follows: A method for preparing quantum dot ink, comprising: S1. In the inert atmosphere of a glove box, lead chalcogenide quantum dots are dissolved in 1-octadecene to form a quantum dot solution; S2. Dissolve indium salt and lead halide ligand in a polar aprotic solvent to form a ligand exchange solution; S3. Perform a ligand exchange reaction between the quantum dot solution and the ligand exchange solution, and then wash the solution. S4. The washed reaction system is subjected to solid-liquid separation and drying to obtain modified lead chalcogenide quantum dot powder; S5. Dissolve the modified lead chalcogenide quantum dot powder in a mixed dispersion solvent to obtain modified quantum dot ink.
[0006] Furthermore, in step S1, the lead chalcogenide quantum dots are PbS or PbSe quantum dots with absorption peaks in the range of 1300~2500 nm.
[0007] Furthermore, in step S1, the concentration of the quantum dot solution is 5-15 mg / mL.
[0008] Furthermore, in step S2, the indium salt includes at least one of InI3, InBr3, InCl3, and In(CH3COO)3.
[0009] Furthermore, in step S2, the solvent includes N,N-dimethylformamide and / or dimethyl sulfoxide.
[0010] Furthermore, in step S5, the mixed dispersion solvent includes at least two of N,N-dimethylformamide, dimethyl sulfoxide, n-butylamine, and 3-pyridinemethylamine.
[0011] Furthermore, in step S2, the concentration of lead halide in the ligand exchange solution is 0.25-0.42 mol / L, and the concentration of indium salt is 0.01-0.1 mol / L.
[0012] A quantum dot ink is prepared by the above-described quantum dot ink preparation method, wherein the quantum dot ink comprises modified lead chalcogenide quantum dot powder and a mixed dispersion solvent.
[0013] A quantum dot detector includes an ITO conductive glass substrate and a NiO layer stacked sequentially from bottom to top. x Hole transport layer, PbS-EDT layer, light-absorbing layer, C 60 The light-absorbing layer comprises a SnO2 layer and an ITO top electrode, wherein the light-absorbing layer is prepared from the quantum dot ink as described in claim 8.
[0014] A method for fabricating a quantum dot detector, comprising the following steps: S10. Centrifuge the quantum dot ink and take the supernatant for later use; S20. NiO is prepared on ITO conductive glass as a substrate. x Hole transport layer; S30. Prepare a PbS-EDT layer on the hole transport layer; S40. The quantum dot ink is coated onto the PbS-EDT layer and annealed to form a light-absorbing layer. S50, C is sequentially deposited on the light-absorbing layer. 60 Layer, SnO2 layer and ITO top electrode.
[0015] By applying the above-described technical solution of the present invention, at least the following technical effects are achieved: This invention effectively addresses the core technical challenges of insufficient film density and high dark current in organically synthesized PbS or PbSe quantum dots after traditional ligand exchange. By combining indium salt modification with preliminary passivation of 1-octadecene, it simultaneously achieves film density enhancement of the quantum dot absorption layer and dark current suppression in infrared detection devices, overcoming the technical bottleneck of existing single modification schemes that struggle to achieve both performance indicators. Furthermore, it overcomes the technical limitation of poor quantum dot size adaptability in traditional partial modification strategies, effectively broadening the application scope of quantum dots in infrared detection. Moreover, compared to traditional complex modification strategies such as ligand engineering, crystal plane selective passivation, and high-concentration halogen passivation, this invention offers a simpler operation process. The indium salt and 1-octadecene raw materials are readily available and cost-effective, significantly reducing the technological threshold and industrialization costs, and possessing the potential for large-scale mass production. It also improves the compatibility of the absorption layer with other device structures, enhances device stability and lifespan, comprehensively breaking through the limitations of existing technologies on infrared detection device performance improvement and expanding its application space. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 A flowchart illustrating a quantum dot ink preparation method proposed in this invention is shown. Figure 2 A partial schematic diagram of the quantum dot ink preparation method proposed in this invention is shown; Figure 3 A flowchart illustrating a method for fabricating a quantum dot detector proposed in this invention is shown. Figure 4 An optical microscope image of the light-absorbing layer film of the 1300 nm PbS-In-PbX2 quantum dot detector of Embodiment 7 of the present invention and a current-voltage curve of the detector are shown (IV). Figure 5 An optical microscope image of the light-absorbing layer film of the 1550 nm PbS-In-PbX2 quantum dot detector of Embodiment 8 of the present invention and a current-voltage curve of the detector are shown (IV). Figure 6 An optical microscope image of the light-absorbing layer film of the 1800 nm PbS-In-PbX2 quantum dot detector of Embodiment 9 of the present invention and a current-voltage curve of the detector are shown (IV). Figure 7An optical microscope image of the light-absorbing layer film of the 2000 nm PbS-In-PbX2 quantum dot detector of Embodiment 10 of the present invention and a current-voltage curve of the detector are shown (IV). Figure 8 An optical microscope image of the light-absorbing layer film of the 1700 nm PbSe-In-PbX2 quantum dot detector of Embodiment 11 of the present invention and a current-voltage curve of the detector are shown (IV).
[0018] Figure 9 An optical microscope image of the light-absorbing layer film of the 2500 nm PbSe-In-PbX2 quantum dot detector of Embodiment 12 of the present invention and a current-voltage curve of the detector are shown (IV). Detailed Implementation
[0019] The following description of the embodiments is with reference to the accompanying illustrations to illustrate specific embodiments in which the invention can be implemented, but this application is not limited to these embodiments.
[0020] To address the challenges of complex and costly modification processes for the light-absorbing layers of PbS and PbSe quantum dots in existing technologies, which also struggle to simultaneously achieve film densification and suppress dark current in devices, this invention proposes a quantum dot ink and its preparation method, as well as a quantum dot detector and its preparation method. This invention enables the easy fabrication of high-performance infrared detectors through a synergistic modification strategy, significantly improving photoelectric performance while offering advantages such as ease of operation and low cost. Furthermore, it is adaptable to quantum dots of different sizes, demonstrating broad application prospects.
[0021] According to a first aspect of the present invention, a method for preparing quantum dot ink is provided, see below. Figure 1 and Figure 2 As shown, the method specifically includes the following steps: S1. In the inert atmosphere of the glove box, weigh a certain mass of PbS quantum dots or PbSe quantum dots and add them to a centrifuge tube. Then, use a pipette to take an appropriate amount of 1-octadecene to prepare a quantum dot solution with a concentration of 5-15 mg / mL.
[0022] Among them, the organic ligands originally coated on the surface of PbS quantum dots and PbSe quantum dots are one or more of oleic acid, oleylamine, and trioctylphosphine; the absorption peak of PbS quantum dots or PbSe quantum dots is located in the range of 1300~2500 nm.
[0023] S2. In the inert atmosphere of the glove box, weigh lead halide PbX2 and indium salt and add them to a glass bottle, then add solvent to prepare a ligand exchange solution.
[0024] The concentration of PbI2 in the ligand exchange solution is 0.2-0.3 mol / L, the concentration of PbBr2 is 0.05-0.12 mol / L, and the concentration of indium salt is 0.01-0.1 mol / L; the indium salt is selected from at least one of InI3, InBr3, InCl3, and In(CH3COO)3; the solvent is any one or a mixture of two of N,N-dimethylformamide or dimethyl sulfoxide.
[0025] S3. Filter the ligand exchange solution into a glass bottle using a syringe and filter. Replace the syringe and filter to filter the quantum dot solution into the same glass bottle, with a volume ratio of 1:1. Tighten the cap to seal the glass bottle, manually shake for 3-5 minutes, and allow it to stand to separate. Aspirate the supernatant. Then add n-octane to the remaining lower layer solution, manually shake, allow it to stand to separate, and aspirate the supernatant. Repeat this n-octane washing step at least 2 times, preferably 2-4 times.
[0026] S4. Transfer the washed lower layer solution into a centrifuge tube and centrifuge at 8500~9500 r / min for 5~8 min. Then discard the supernatant and place the ligand-exchanged quantum dots in a vacuum drying oven for 1-2 h to obtain dried modified quantum dot powder (PbS-In-PbX2). Weigh it for later use.
[0027] S5. Prepare a mixed dispersion solvent under the inert atmosphere of a glove box. The mixed dispersion solvent contains at least two of N,N-dimethylformamide, dimethyl sulfoxide, n-butylamine and 3-pyridinemethylamine, and the volume ratio of the four solvents is (35-80):(0-30):(15-40):(0-5). Add the mixed dispersion solvent to a centrifuge tube containing the above modified quantum dot powder to prepare a quantum dot slurry with a concentration of 150~550 mg / mL. Shake the slurry for 3-5 min to obtain the modified quantum dot ink.
[0028] The following specific embodiments illustrate a method for preparing quantum dot ink proposed in this invention.
[0029] Example 1 Prepare PbS-In-PbX2 quantum dot ink with an absorption peak of 1300 nm.
[0030] S1. Weigh 150 mg of PbS quantum dots with an absorption peak of 1300 nm in a glove box, add 10 mL of 1-octadecene to dissolve them to obtain a 15 mg / mL quantum dot solution.
[0031] S2. Weigh 1.226 g PbI2, 0.424 g PbBr2 and 49.6 mg InI3 and add them to a glass bottle. Then add 10 mL of N,N-dimethylformamide to prepare a ligand exchange solution.
[0032] S3. After filtering the two solutions, transfer them to the same sealed glass bottle in equal volume ratio, shake manually for 4 minutes, let stand to separate the layers, and remove the supernatant. Add n-octane to the remaining lower layer solution, shake manually, let stand to separate the layers, remove the supernatant, and repeat this n-octane washing step twice.
[0033] S4. Transfer the washed solution into a centrifuge tube, centrifuge at 9000 r / min for 7 minutes, discard the supernatant, and then dry it in a vacuum drying oven for 2 hours to obtain modified quantum dot powder with an absorption peak of 1300 nm. Weigh it for later use.
[0034] S5. Under the inert atmosphere of a glove box, prepare a mixed dispersion solvent with N,N-dimethylformamide and n-butylamine in a volume ratio of 80:20. Add the mixed dispersion solvent to a centrifuge tube containing modified quantum dot powder to prepare a quantum dot slurry with a concentration of 150 mg / mL. Then shake with a shaker for 3-5 min to obtain a modified quantum dot ink with an absorption peak of 1300 nm.
[0035] Example 2 Prepare PbS-In-PbX2 quantum dot ink with an absorption peak of 1550 nm.
[0036] S1. Weigh 120 mg of PbS quantum dots with an absorption peak of 1550 nm in a glove box, add 10 mL of 1-octadecene to dissolve, and obtain a 12 mg / mL quantum dot solution.
[0037] S2. Weigh 1.226 g PbI2, 0.424 g PbBr2 and 49.6 mg InI3 and add them to a glass bottle. Then add 10 mL N,N-dimethylformamide to prepare a ligand exchange solution.
[0038] S3. After filtering the two solutions, transfer them to the same sealed glass bottle in equal volume ratio, shake manually for 3 minutes, let stand to separate the layers, and remove the supernatant. Add n-octane to the remaining lower layer solution, shake manually, let stand to separate the layers, remove the supernatant, and repeat this n-octane washing step 3 times.
[0039] S4. Transfer the washed solution into a centrifuge tube, centrifuge at 8500 r / min for 6 minutes, discard the supernatant, and then dry it in a vacuum drying oven for 1.5 hours to obtain modified quantum dot powder with an absorption peak of 1550 nm, and then weigh it for later use.
[0040] S5. Under the inert atmosphere of a glove box, a mixed dispersion solvent was prepared with N,N-dimethylformamide, dimethyl sulfoxide, n-butylamine and 3-pyridinemethylamine as components, with a volume ratio of 35:25:37:3; the mixed dispersion solvent was added to a centrifuge tube containing modified quantum dot powder to prepare a quantum dot slurry with a concentration of 350 mg / mL, and the mixture was shaken for 5 minutes to obtain a modified quantum dot ink with an absorption peak of 1550 nm.
[0041] Example 3 Prepare PbS-In-PbX2 quantum dot ink with an absorption peak of 1800 nm.
[0042] S1. Weigh 100 mg of PbS quantum dots with an absorption peak of 1800 nm in a glove box, add 10 mL of 1-octadecene to dissolve, and obtain a 10 mg / mL quantum dot solution.
[0043] S2. Weigh 1.226 g PbI3, 0.424 g PbBr2 and 99.2 mg InI3 and add them to a glass bottle. Then add 10 mL N,N-dimethylformamide to prepare a ligand exchange solution.
[0044] S3. After filtering the two solutions, transfer them to the same sealed glass bottle in equal volume ratio, shake manually for 5 minutes, let stand to separate the layers, and remove the supernatant. Add n-octane to the remaining lower layer solution, shake manually, let stand to separate the layers, remove the supernatant, and repeat this n-octane washing step 4 times.
[0045] S4. Transfer the washed solution into a centrifuge tube, centrifuge at 9200 r / min for 5 minutes, discard the supernatant, and then dry it in a vacuum drying oven for 2 hours to obtain modified quantum dot powder with an absorption peak of 1800 nm. Weigh it for later use.
[0046] S5. Under the inert atmosphere of a glove box, a mixed dispersion solvent was prepared with N,N-dimethylformamide, dimethyl sulfoxide, n-butylamine and 3-pyridinemethylamine as components in a volume ratio of 35:25:37:3. The mixed dispersion solvent was added to a centrifuge tube containing modified quantum dot powder to prepare a quantum dot slurry with a concentration of 400 mg / mL. The slurry was shaken for 4 minutes to obtain a modified quantum dot ink with an absorption peak of 1800 nm.
[0047] Example 4 Prepare PbS-In-PbX2 quantum dot ink with an absorption peak of 2000 nm.
[0048] S1. Weigh 80 mg of PbS quantum dots with an absorption peak of 2000 nm in a glove box, add 10 mL of 1-octadecene to dissolve, and obtain an 8 mg / mL quantum dot solution.
[0049] S2. Weigh 1.226 g PbI2, 0.424 g PbBr2 and 99.2 mg InI3 and add them to a glass bottle. Then add 10 mL N,N-dimethylformamide to prepare a ligand exchange solution.
[0050] S3. After filtering the two solutions, transfer them to the same sealed glass bottle in equal volume ratio, shake manually for 3 minutes, let stand to separate the layers, and remove the supernatant. Add n-octane to the remaining lower layer solution, shake manually, let stand to separate the layers, remove the supernatant, and repeat this n-octane washing step twice.
[0051] S4. Transfer the washed solution into a centrifuge tube and centrifuge at 8800 r / min for 7 minutes. Discard the supernatant and then dry it in a vacuum drying oven for 1 hour to obtain modified quantum dot powder with an absorption peak of 2000 nm. Weigh it for later use.
[0052] S5. Under the inert atmosphere of a glove box, a mixed dispersion solvent was prepared with N,N-dimethylformamide, dimethyl sulfoxide, n-butylamine and 3-pyridinemethylamine as components in a volume ratio of 50:30:17:3. The mixed dispersion solvent was added to a centrifuge tube containing modified quantum dot powder to prepare a quantum dot slurry with a concentration of 450 mg / mL. The slurry was shaken for 3 minutes to obtain a modified quantum dot ink with an absorption peak of 2000 nm.
[0053] Example 5 Prepare PbSe-In-PbX2 quantum dot ink with an absorption peak of 1700 nm.
[0054] S1. Weigh 50 mg of PbSe quantum dots with an absorption peak of 1700 nm in a glove box, add 10 mL of 1-octadecene to dissolve, and obtain a 5 mg / mL quantum dot solution.
[0055] S2. Weigh 1.226 g PbI2, 0.424 g PbBr2 and 49.6 mg InI3 and add them to a glass bottle. Then add 10 mL N,N-dimethylformamide to prepare a ligand exchange solution.
[0056] S3. After filtering the two solutions, transfer them to the same sealed glass bottle in equal volume ratio, shake manually for 5 minutes, let stand to separate the layers, and remove the supernatant. Add n-octane to the remaining lower layer solution, shake manually, let stand to separate the layers, remove the supernatant, and repeat this n-octane washing step twice.
[0057] S4. Transfer the washed solution into a centrifuge tube and centrifuge at 9500 r / min for 5.5 minutes. Discard the supernatant and then dry it in a vacuum drying oven for 1.5 hours to obtain modified quantum dot powder with an absorption peak of 1700 nm. Weigh it for later use.
[0058] S5. Under the inert atmosphere of a glove box, a mixed dispersion solvent was prepared with N,N-dimethylformamide, dimethyl sulfoxide, n-butylamine and 3-pyridinemethylamine as components in a volume ratio of 35:25:37:3. The mixed dispersion solvent was added to a centrifuge tube containing modified quantum dot powder to prepare a quantum dot slurry with a concentration of 550 mg / mL. The slurry was shaken for 5 minutes to obtain a modified quantum dot ink with an absorption peak of 1700 nm.
[0059] Example 6 Prepare PbSe-In-PbX2 quantum dot ink with an absorption peak of 2500 nm.
[0060] S1. Weigh 100 mg of PbSe quantum dots with an absorption peak of 2500 nm in a glove box, add 10 mL of 1-octadecene to dissolve, and obtain a 10 mg / mL quantum dot solution.
[0061] S2. Weigh 1.226 g PbI2, 0.424 g PbBr2 and 99.2 mg InI3 and add them to a glass bottle. Then add 10 mL N,N-dimethylformamide to prepare a ligand exchange solution.
[0062] S3. After filtering the two solutions, transfer them to the same sealed glass bottle in equal volume ratio, shake manually for 5 minutes, let stand to separate the layers, and remove the supernatant. Add n-octane to the remaining lower layer solution, shake manually, let stand to separate the layers, remove the supernatant, and repeat this n-octane washing step twice.
[0063] S4. Transfer the washed solution into a centrifuge tube and centrifuge at 9500 r / min for 5.5 minutes. Discard the supernatant and then dry it in a vacuum drying oven for 1.5 hours to obtain modified quantum dot powder with an absorption peak of 2500 nm. Weigh it for later use.
[0064] S5. Under the inert atmosphere of a glove box, a mixed dispersion solvent was prepared with N,N-dimethylformamide, dimethyl sulfoxide, n-butylamine and 3-pyridinemethylamine as components, with a volume ratio of 50:30:17:3; the dispersion solvent was added to a centrifuge tube containing modified quantum dot powder to prepare a quantum dot slurry with a concentration of 400 mg / mL, and the mixture was shaken for 5 minutes to obtain a modified quantum dot ink with an absorption peak of 2500 nm.
[0065] According to a second aspect of the present invention, a quantum dot ink is provided, which is prepared by a quantum dot ink preparation method according to the first aspect of the present invention. The quantum dot ink comprises modified quantum dots and a mixed dispersion solvent; wherein the modified quantum dots are lead-based quantum dots with surface-coated organic ligands, obtained by reacting with a ligand exchange system comprising lead halide PbX2 and indium salt, wherein X is a halogen; the absorption peak of the lead-based quantum dots is located in the range of 1300~2500 nm; the dispersion solvent comprises at least two of N,N-dimethylformamide, dimethyl sulfoxide, n-butylamine and 3-pyridinemethylamine; the concentration of the modified quantum dots in the modified quantum dot ink is 150~550 mg / mL.
[0066] According to a third aspect of the present invention, a quantum dot detector is provided, wherein the light-absorbing layer of the quantum dot detector is prepared by solution method from a quantum dot ink proposed in the second aspect of the present invention, and the quantum dot detector further includes a hole transport layer, an electron transport layer and electrodes; the light-absorbing layer is located between the hole transport layer and the electron transport layer, and has high light absorption and low defect density in the operating band, so that the detector has the characteristics of high responsivity and low dark current in the infrared band.
[0067] According to a fourth aspect of the present invention, a method for fabricating a quantum dot detector is provided for fabricating a quantum dot detector as described in the third aspect of the present invention. (See also...) Figure 3 As shown, the preparation method specifically includes the following steps: S10. Centrifuge the modified quantum dot ink at a speed of 2000-2500 r / min for 1-2 min, and take the supernatant for later use.
[0068] S20. Using ITO conductive glass as a substrate, a layer of NiO is prepared on the substrate by magnetron sputtering. X The thin film serves as a hole transport layer, with a thickness of 80–120 nm.
[0069] S30. On the hole transport layer, a PbS-EDT thin film is prepared as an electron blocking layer by solid-phase ligand exchange technology. Specifically, this includes: spin-coating a PbS quantum dot n-octane solution with a concentration of 20-30 mg / mL and an absorption peak of 850-900 nm, then drop-coating an acetonitrile solution of 1,2-ethylenedithiol with a volume concentration of 0.01-0.02%, allowing it to stand for 20-30 s, then spin-coating again, and washing with acetonitrile; repeating this process 1-2 times.
[0070] S40. The quantum dot ink pretreated in step S10 is spin-coated onto the electron blocking layer. The amount of ink used is 50-80 µL, the spin-coating speed is 1500-2500 r / min, and the time is 30-50 s. Then, the coated substrate is annealed at 80-90 ℃ for 10-20 min to form a quantum dot light-absorbing layer.
[0071] S50, C is sequentially deposited on the light-absorbing layer. 60 The quantum dot detector was fabricated by adding a SnO2 layer, an ITO electrode layer, and an ITO electrode layer.
[0072] The following specific embodiments illustrate a method for fabricating a quantum dot detector proposed in this invention.
[0073] Example 7 S10. Place the PbS-In-PbX2 quantum dot ink with an absorption peak of 1300 nm prepared in Example 1 into a centrifuge and centrifuge at 2000 r / min for 2 min. Take the upper layer solution for later use.
[0074] S20. Magnetron sputtering of NiO with a thickness of 80 nm onto clean ITO conductive glass. x A thin film is formed, creating a hole transport layer.
[0075] S30, in NiO x On the hole transport layer, EDT-coated PbS quantum dot (CQD) films were prepared using solid-state ligand exchange technology: First, a 20 mg / mL solution of PbS quantum dots in n-octane was prepared, with the PbS quantum dots exhibiting an absorption peak at 850 nm; simultaneously, a 0.01% (v / v) acetonitrile solution of 1,2-ethylenedithiol was prepared. In NiO... x The PbS quantum dots in n-octane solution were spin-coated onto the hole transport layer, and EDT acetonitrile solution was dropped on and allowed to stand for 25 s. After spin-coating again, the layer was washed twice with acetonitrile to remove residual ligands, thus completing the monolayer preparation. The spin-coating, ligand exchange and washing process was repeated once to obtain the PbS-EDT layer.
[0076] S40. Set the spin coater parameters to: rotation speed 1500 r / min, acceleration 1500, and time 50 s. Take 50 μL of the 1300 nm PbS-In-PbX2 quantum dot slurry centrifuged in step S10 and uniformly drop it onto the surface of the substrate with the PbS-EDT layer. Start the spin coater to form a uniform wet film. Then, transfer the substrate coated with the wet film to a heating stage and anneal it at 80 ℃ for 10 min to remove the dispersion solvent and reduce film defects, forming a 1300 nm PbS-In-PbX2 quantum dot light-absorbing layer.
[0077] S50, C is sequentially deposited on a 1300 nm PbS-In-PbX2 quantum dot light-absorbing layer. 60 The process involved layering a SnO2 layer, an ITO layer, and finally fabricating a 1300 nm PbS-In-PbX2 quantum dot detector.
[0078] Example 8 S10. Place the PbS-In-PbX2 quantum dot ink with an absorption peak of 1550 nm prepared in Example 2 into a centrifuge and centrifuge at 2500 r / min for 2 min. Take the upper layer solution for later use.
[0079] S20. Magnetron sputtering of NiO with a thickness of 85 nm onto clean ITO conductive glass. x A thin film is formed, creating a hole transport layer.
[0080] S30, in NiO x On the hole transport layer, an EDT-coated PbS CQD film was prepared using solid-state ligand exchange technology: first, a 25 mg / mL solution of PbS quantum dots in n-octane was prepared, the absorption peak of which was 880 nm; simultaneously, a 0.015% (v / v) acetonitrile solution of 1,2-ethylenedithiol was prepared; and then, on NiO... x The hole transport layer is spin-coated with an octane solution of PbS quantum dots, then EDT acetonitrile solution is dropped on it and allowed to stand for 25 s. After spin-coating again, the layer is washed twice with acetonitrile to remove residual ligands, thus completing the monolayer preparation. The above spin-coating, ligand exchange and washing process is repeated once to obtain the PbS-EDT layer.
[0081] S40. Set the spin coater parameters: rotation speed 2000 r / min, acceleration 1500, time 40 s. Take 60 μL of the 1550 nm PbS-In-PbX2 quantum dot slurry centrifuged in step S10 and uniformly drop it onto the surface of the substrate with the PbS-EDT layer. Start the spin coater to form a uniform wet film. Then transfer the substrate coated with the wet film to a heating stage and anneal at 85 ℃ for 15 min to remove the dispersion solvent and reduce film defects, forming a 1550 nm PbS-In-PbX2 quantum dot light-absorbing layer.
[0082] S50, C is sequentially deposited on a 1550 nm PbS-In-PbX2 quantum dot light-absorbing layer. 60 The process involved layering a SnO2 layer, an ITO layer, and finally fabricating a 1550 nm PbS-In-PbX2 quantum dot detector.
[0083] Example 9 S10. Place the PbS-In-PbX2 quantum dot ink with an absorption peak of 1800 nm prepared in Example 3 into a centrifuge and centrifuge at 2500 r / min for 2 min. Take the upper layer solution for later use.
[0084] S20. Magnetron sputtering of NiO with a thickness of 90 nm onto clean ITO conductive glass. x This forms a hole transport layer.
[0085] S30, in NiO x On the hole transport layer, EDT-coated PbS quantum dot films were prepared using solid-state ligand exchange technology: first, a 30 mg / mL solution of PbS quantum dots in n-octane was prepared, the absorption peak of which was 900 nm; simultaneously, a 0.02% (v / v) acetonitrile solution of 1,2-ethylenedithiol was prepared; and then, on NiO... x The PbS quantum dots in n-octane solution were spin-coated onto the hole transport layer, and EDT acetonitrile solution was dropped on and allowed to stand for 25 s. After spin-coating again, the layer was washed twice with acetonitrile to remove residual ligands, thus completing the monolayer preparation. The spin-coating, ligand exchange and washing process was repeated once to obtain the PbS-EDT layer.
[0086] S40. Set the spin coater parameters as follows: rotation speed 2500 r / min, acceleration 1500, and time 30 s. Take 70 μL of the 1800 nm PbS-In-PbX2 quantum dot slurry obtained from the centrifugation treatment in step S10 and uniformly drop it onto the surface of the substrate with the PbS-EDT layer. Start the spin coater to form a uniform wet film. Then, transfer the substrate coated with the wet film to a heating stage and anneal it at 90 ℃ for 20 min to remove the dispersion solvent and reduce film defects, forming an 1800 nm PbS-In-PbX2 quantum dot light-absorbing layer.
[0087] S50, C is sequentially deposited on an 1800 nm PbS-In-PbX2 quantum dot light-absorbing layer. 60 The process involves layering a SnO2 layer, an ITO layer, and finally fabricating an 1800 nm PbS-In-PbX2 quantum dot detector.
[0088] Example 10 S10. Place the PbS-In-PbX2 quantum dot ink with an absorption peak of 2000 nm prepared in Example 4 into a centrifuge and centrifuge at 2000 r / min for 1 min. Take the upper layer solution for later use.
[0089] S20. Magnetron sputtering of NiO with a thickness of 100 nm onto clean ITO conductive glass. x This forms a hole transport layer.
[0090] S30. On the NiOx hole transport layer, an EDT-coated PbS quantum dot film is prepared using solid-state ligand exchange technology: First, a 20 mg / mL solution of PbS quantum dots in n-octane is prepared, wherein the absorption peak of the PbS quantum dots is 880 nm; simultaneously, a 0.01% (v / v) acetonitrile solution of 1,2-ethylenedithiol is prepared; on the NiOx hole transport layer... x The PbS quantum dots in n-octane solution were spin-coated onto the hole transport layer, and EDT acetonitrile solution was dropped on and allowed to stand for 25 s. After spin-coating again, the layer was washed twice with acetonitrile to remove residual ligands, thus completing the monolayer preparation. The spin-coating, ligand exchange and washing process was repeated once to obtain the PbS-EDT layer.
[0091] S40. Set the spin coater parameters: rotation speed 2500 r / min, acceleration 1500, time 40 s. Take 80 μL of the 2000 nm PbS-In-PbX2 quantum dot slurry obtained from centrifugation in step S10 and uniformly drop it onto the surface of the substrate with the PbS-EDT layer. Start the spin coater to form a uniform wet film. Then transfer the substrate coated with the wet film to a heating stage and anneal at 85 ℃ for 15 min to remove the dispersion solvent and reduce film defects, forming a 2000 nm PbS-In-PbX2 quantum dot light-absorbing layer.
[0092] S50. On a 2000 nm PbS-In-PbX2 quantum dot light-absorbing layer, C is sequentially deposited. 60 The SnO2 layer, ITO layer, and other layers were used to finally fabricate a 2000 nm PbS-In-PbX2 quantum dot detector.
[0093] Example 11 S10. Place the PbSe-In-PbX2 quantum dot ink with an absorption peak of 1700 nm prepared in Example 5 into a centrifuge and centrifuge at 2500 r / min for 2 min. Take the upper layer solution for later use.
[0094] S20. Magnetron sputtering of NiO with a thickness of 110 nm onto clean ITO conductive glass. x This forms a hole transport layer.
[0095] S30, in NiO x On the hole transport layer, EDT-coated PbS quantum dot films were prepared using solid-state ligand exchange technology: first, a 20 mg / m³ PbS quantum dot n-octane solution was prepared, the absorption peak of the PbS quantum dots being 880 nm; simultaneously, a 0.01% (v / v) acetonitrile solution of 1,2-ethylenedithiol was prepared; and then, on NiO... xThe PbS quantum dots in n-octane solution were spin-coated onto the hole transport layer, and EDT acetonitrile solution was dropped on and allowed to stand for 25 s. After spin-coating again, the layer was washed twice with acetonitrile to remove residual ligands, thus completing the monolayer preparation. The spin-coating, ligand exchange and washing process was repeated once to obtain the PbS-EDT layer.
[0096] S40. Set the spin coater parameters as follows: rotation speed 2500 r / min, acceleration 1500, and time 40 s. Take 70 μL of the centrifuged 1700 nm PbSe-In-PbX2 quantum dot slurry and uniformly drop it onto the surface of the substrate with the PbS-EDT layer. Start the spin coater to form a uniform wet film. Then, transfer the substrate coated with the wet film to a heating stage and anneal at 85 ℃ for 15 min to remove the dispersion solvent and reduce film defects, forming a 1700 nm PbSe-In-PbX2 quantum dot light-absorbing layer.
[0097] S50, C is sequentially deposited on a 1700 nm PbSe-In-PbX2 quantum dot light-absorbing layer. 60 The process involved layering a SnO2 layer, an ITO layer, and finally fabricating a 1700 nm PbSe-In-PbX2 quantum dot detector.
[0098] Example 12 S10. Place the PbSe-In-PbX2 quantum dot ink with an absorption peak of 2500 nm prepared in Example 6 into a centrifuge and centrifuge at 2500 r / min for 2 min. Take the supernatant solution for later use.
[0099] S20. Magnetron sputtering of NiO with a thickness of 120 nm onto clean ITO conductive glass. x This forms a hole transport layer.
[0100] S30, in NiO x On the hole transport layer, EDT-coated PbS quantum dot films were prepared using solid-state ligand exchange technology: first, a 20 mg / m³ PbS quantum dot n-octane solution was prepared, the absorption peak of the PbS quantum dots being 880 nm; simultaneously, a 0.01% (v / v) acetonitrile solution of 1,2-ethylenedithiol was prepared; and then, on NiO... x The PbS quantum dots in n-octane solution were spin-coated onto the hole transport layer, and EDT acetonitrile solution was dropped on and allowed to stand for 25 s. After spin-coating again, the layer was washed twice with acetonitrile to remove residual ligands, thus completing the monolayer preparation. The spin-coating, ligand exchange and washing process was repeated once to obtain the PbS-EDT layer.
[0101] S40. Set the spin coater parameters as follows: rotation speed 2500 r / min, acceleration 1500, and time 40 s. Take 70 μL of the centrifuged 1700 nm PbSe-In-PbX2 quantum dot slurry and uniformly drop it onto the surface of the substrate with the PbS-EDT layer. Start the spin coater to form a uniform wet film. Then, transfer the substrate coated with the wet film to a heating stage and anneal at 85 ℃ for 15 min to remove the dispersion solvent and reduce film defects, forming a 2500 nm PbSe-In-PbX2 quantum dot light-absorbing layer.
[0102] S50, C is sequentially deposited on a 2500 nm PbSe-In-PbX2 quantum dot light-absorbing layer. 60 The process involves layering a SnO2 layer, an ITO layer, and finally fabricating a 2500 nm PbSe-In-PbX2 quantum dot detector.
[0103] To verify the superior performance of the quantum dot detector prepared according to the fourth aspect of the present invention, the quantum dot detectors prepared in Examples 7 to 12 were characterized. Figures 4 to 9 Optical microscope images of the light-absorbing layers of each detector and the current-voltage (IV) characteristic curves of the devices are presented respectively.
[0104] like Figures 4 to 9 As shown in the optical microscope images, the light-absorbing film formed by spin-coating and annealing of the modified quantum dot ink of this invention exhibits high uniformity, high density, and no macroscopic defects. This demonstrates that the ink provided by this invention has excellent film-forming properties and can form a high-quality light-absorbing layer, laying a material foundation for realizing high-performance devices.
[0105] Figures 4 to 9 The IV curves show that all detectors exhibit extremely low dark current under dark conditions, fully verifying the effectiveness of the ligand exchange modification strategy in suppressing dark current. Under illumination, each detector generated significant photocurrent responses in its corresponding target wavelength band, demonstrating excellent photoelectric detection characteristics. In particular, from Examples 7 to 10, the devices maintained consistently excellent performance at different target wavelengths of 1300 nm, 1550 nm, 1800 nm, and 2000 nm; Examples 11 and 12 further demonstrate the successful applicability of the method of this invention to PbSe quantum dot systems. These results collectively indicate that the technical solution provided by this invention has the advantages of strong universality and good repeatability, and can be widely applied to the fabrication of infrared photodetectors in different target wavelength bands.
[0106] In summary, this invention addresses the pain points of existing technologies by proposing an innovative scheme of synergistic modification through preliminary passivation of 1-octadecene and indium salt-lead halide ligand exchange. This effectively solves the core problems of insufficient film density and high dark current in organically synthesized PbS and PbSe quantum dots after ligand exchange, successfully overcoming the technical challenges of complex operation, high cost, and the inability to simultaneously achieve film densification and efficient dark current suppression in traditional modification strategies. This synergistic modification system not only efficiently adapts to the modification needs of quantum dots of different sizes, overcoming the limitations of poor size adaptability in traditional schemes and broadening the application range, but also possesses the core advantage of simple operation. Furthermore, the readily available and cost-controllable raw materials of indium salt and 1-octadecene significantly reduce the process threshold and implementation cost, demonstrating potential for large-scale industrialization. Simultaneously, the method of this invention can prepare high-performance infrared detectors with dense film layers and low dark current, significantly improving photoelectric detection performance. It also enhances the compatibility of the light-absorbing layer with other structures of the device, strengthens device stability and lifespan, comprehensively breaking through the limitations of existing technologies on the performance of infrared detectors, expanding their application space, and demonstrating significant technological innovation and practical value.
[0107] It should be noted that although the present invention has been disclosed above with specific embodiments, the above embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.
Claims
1. A method for preparing quantum dot ink, characterized in that, include: S1. In the inert atmosphere of a glove box, lead chalcogenide quantum dots are dissolved in 1-octadecene to form a quantum dot solution; S2. Dissolve indium salt and lead halide ligand in a polar aprotic solvent to form a ligand exchange solution; S3. Perform a ligand exchange reaction between the quantum dot solution and the ligand exchange solution, and then wash the solution. S4. The washed reaction system is subjected to solid-liquid separation and drying to obtain modified lead chalcogenide quantum dot powder; S5. Dissolve the modified lead chalcogenide quantum dot powder in a mixed dispersion solvent to obtain modified quantum dot ink.
2. The method for preparing quantum dot ink according to claim 1, characterized in that, In step S1, the lead chalcogenide quantum dots are PbS or PbSe quantum dots with absorption peaks in the range of 1300~2500 nm.
3. The method for preparing quantum dot ink according to claim 1, characterized in that, In step S1, the concentration of the quantum dot solution is 5-15 mg / mL.
4. The method for preparing quantum dot ink according to claim 1, characterized in that, In step S2, the indium salt includes at least one of InI3, InBr3, InCl3, and In(CH3COO)3.
5. The method for preparing quantum dot ink according to claim 1, characterized in that, In step S2, the solvent includes N2N-dimethylformamide and / or dimethyl sulfoxide.
6. The method for preparing quantum dot ink according to claim 1, characterized in that, In step S5, the mixed dispersion solvent includes at least two of N,N-dimethylformamide, dimethyl sulfoxide, n-butylamine, and 3-pyridinemethylamine.
7. The method for preparing quantum dot ink according to claim 1 or 4, characterized in that, In step S2, the concentration of lead halide in the ligand exchange solution is 0.25-0.42 mol / L, and the concentration of indium salt is 0.01-0.1 mol / L.
8. A quantum dot ink, prepared by the quantum dot ink preparation method according to any one of claims 1 to 7, characterized in that, The quantum dot ink comprises modified lead chalcogenide quantum dot powder and a mixed dispersion solvent.
9. A quantum dot detector, characterized in that, Including an ITO conductive glass substrate and NiO layered from bottom to top X Hole transport layer, PbS-EDT layer, light-absorbing layer, C 60 The light-absorbing layer comprises a SnO2 layer and an ITO top electrode, wherein the light-absorbing layer is prepared from the quantum dot ink as described in claim 8.
10. A method for fabricating a quantum dot detector, used to fabricate the quantum dot detector as described in claim 9, characterized in that, Includes the following steps: S10. Centrifuge the quantum dot ink and take the supernatant for later use; S20. NiO is prepared on ITO conductive glass as a substrate. x Hole transport layer; S30. Prepare a PbS-EDT layer on the hole transport layer; S40. The quantum dot ink is coated onto the PbS-EDT layer and annealed to form a light-absorbing layer. S50, C is sequentially deposited on the light-absorbing layer. 60 Layer, SnO2 layer and ITO top electrode.