PbS quantum dot detector and preparation method thereof

Abstract

The invention discloses a PbS quantum dot detector and a preparation method thereof, and the method comprises the following steps: dissolving PbS quantum dots in a first solution, and preparing a PbS quantum dot solution; dissolving BMIM-BF4 in the second solution to prepare a first ionic liquid solution; adding the third solution into the first ionic liquid solution, and stirring until the solution is uniform and transparent to form a mixed solution; adding the mixed solution into the PbS quantum dot solution, and stirring to form a turbid solution; carrying out centrifugal precipitation separation on the turbid solution, and adding a detergent for washing to obtain the PbS quantum dot with the surface modified by BMIM-BF4; preparing the PbS quantum dots of which the surfaces are modified by the BMIM-BF4 into a PbS quantum dot film of which the surfaces are modified by the BMIM-BF4; iTO is used as a bottom electrode, ZnO, the BMIM-BF4 modified PbS quantum dot film, MoO3 and Ag are sequentially deposited on the surface of the bottom electrode, and the p-n heterojunction photoelectric detector is formed. According to the PbS quantum dot detector, the problem of ion migration can be effectively solved, and the photoelectric property and the long-term stability of the thin film are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectric detectors, and in particular relates to a PbS quantum dot detector and a preparation method thereof. Background Art

[0002] As an important infrared detection technology, PbS quantum dot detectors have attracted much attention in many fields due to their excellent optoelectronic properties and flexible adjustability. However, their performance and stability are significantly affected by ion migration on the surface of quantum dots. Iodide ions (I-) in PbS quantum dots can easily migrate from quantum dots to other layers of the device (such as the SnO2 layer) under the action of electric field and temperature, which can lead to a series of adverse consequences, such as decreased long-term stability of the device, deterioration of optoelectronic performance, and even the formation of crystals due to ion accumulation, leading to irreversible damage to the device. Traditional interface modification and passivation methods have limited effects and cannot fundamentally solve the problem of ion migration. Therefore, how to fundamentally solve the problem of ion migration is an important issue that urgently needs to be solved. Summary of the Invention

[0003] The technical problem to be solved by the present invention is that, since iodine ions in the existing PbS quantum dot detector are easy to migrate during operation, the present invention provides a PbS quantum dot detector and a preparation method thereof.

[0004] In order to solve the above technical problems, an embodiment of the present invention provides a method for preparing a PbS quantum dot detector, comprising the following steps:

[0005] S1: dissolving PbS quantum dots in the first solution to prepare a PbS quantum dot solution;

[0006] S2: dissolving 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (BMIM-BF4) in the second solution to prepare a first ionic liquid solution;

[0007] S3: adding the third solution to the first ionic liquid solution and stirring until the solution is uniform and transparent to form a mixed solution; and adding the mixed solution to the PbS quantum dot solution and stirring again to form a turbid solution;

[0008] S4: centrifugally separating the turbid solution and adding a detergent for washing to obtain PbS quantum dots with BMIM-BF4 modified surfaces;

[0009] S5: preparing a BMIM-BF4-modified PbS quantum dot film from the PbS quantum dots whose surface is modified by BMIM-BF4;

[0010] S6: Using ITO as the bottom electrode, ZnO, BMIM-BF4 modified PbS quantum dot film, MoO3 and Ag are deposited on its surface in sequence to form a pn heterojunction photodetector.

[0011] Preferably, in step S1, the first solution comprises: one or more combinations of n-hexane and n-octane; and the concentration of the PbS quantum dot solution is 8 mg / mL-12 mg / mL.

[0012] Preferably, in step S2, the second solution comprises ethanol; and the concentration of the first ionic liquid solution is 0.01 mol / L-0.02 mol / L.

[0013] Preferably, in step S3, the third solution comprises isopropyl alcohol; and the secondary stirring time is 20 minutes to 40 minutes.

[0014] Preferably, in step S4, the detergent includes: n-octane; and the washing times are greater than or equal to 2 times.

[0015] Preferably, the step S5 is specifically as follows:

[0016] S51: dissolving the PbS quantum dots whose surfaces are modified with BMIM-BF4 in a fourth solution to form a film-forming solution;

[0017] S52: Add the film-forming solution to the surface of the ITO substrate and spin-coat it at 2000 rpm for 30 seconds to prepare a uniform quantum dot film; and add BMIM-BF4 solution to the surface of the spin-coated film and spin-coat it again to enhance the density and interface quality of the film.

[0018] Preferably, the step S5 further includes:

[0019] S53: Annealing the prepared film at 80° C. for 10 minutes under nitrogen protection to improve the crystallization quality and interface stability of the quantum dot film.

[0020] Preferably, in step S51, the fourth solution includes toluene; and the concentration of the membrane-forming solution is 350 mg / mL-450 mg / mL.

[0021] An embodiment of the present invention further provides a PbS quantum dot detector, which is prepared by the above-mentioned PbS quantum dot detector preparation method.

[0022] The implementation of the embodiments of the present invention has the following beneficial effects:

[0023] (1) The present invention introduces the ionic liquid BMIM-BF4 as a surface ligand regulator and ion migration inhibitor for PbS quantum dots. During the preparation process, BMIM-BF4 coordinates with iodine ions on the surface of the PbS quantum dots, significantly enhancing the ionic stability of the PbS quantum dots and optimizing the film quality, thereby improving the photoelectric performance and long-term reliability of the PbS quantum dot detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 A flow chart of a method for preparing a PbS quantum dot detector provided for the implementation of the present invention;

[0026] Figure 2 A graph showing the IV characteristics of a PbS quantum dot detector provided for the implementation of the present invention;

[0027] Figure 3 A comparison light absorption spectrum of a PbS quantum dot detector provided for the implementation of the present invention;

[0028] Figure 4 A light absorption spectrum of a PbS quantum dot detector provided for the implementation of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] like Figure 1 As shown, this embodiment discloses a method for preparing a PbS quantum dot detector, which includes the following steps:

[0031] S1: dissolving PbS quantum dots in the first solution to prepare a PbS quantum dot solution;

[0032] S2: dissolving 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (BMIM-BF4) in the second solution to prepare a first ionic liquid solution;

[0033] S3: adding the third solution to the first ionic liquid solution and stirring until the solution is uniform and transparent to form a mixed solution; and adding the mixed solution to the PbS quantum dot solution and stirring again to form a turbid solution;

[0034] S4: centrifugally separating the turbid solution and adding a detergent for washing to obtain PbS quantum dots with BMIM-BF4 modified surfaces;

[0035] S5: preparing a BMIM-BF4-modified PbS quantum dot film from the PbS quantum dots whose surface is modified by BMIM-BF4;

[0036] S6: Using ITO as the bottom electrode, ZnO, BMIM-BF4 modified PbS quantum dot film, MoO3 and Ag are deposited on its surface in sequence to form a pn heterojunction photodetector.

[0037] Specifically, in step S1, the first solution includes: one or more combinations of n-hexane and n-octane. The concentration of the PbS quantum dot solution is 8 mg / mL-12 mg / mL, preferably 10 mg / mL. In step S2, the second solution includes: ethanol. The concentration of the first ionic liquid solution is 0.01 mol / L-0.02 mol / L, preferably 0.01 mol / L. In step S3, the third solution includes: isopropanol. The time of the secondary stirring is 20 minutes-40 minutes, preferably 30 minutes. The secondary stirring is used to allow the PbS quantum dots to fully exchange ligands with the first ionic liquid solution. In step S4, the detergent includes: n-octane; the number of washing times is greater than or equal to 2 times.

[0038] This embodiment of the present invention introduces the ionic liquid BMIM-BF4 as a surface modifier for PbS quantum dots. BMIM-BF4 stabilizes the coordination of imidazolium cations with PbS quantum dot surface ions, while tetrafluoroborate simultaneously passivates surface defects. This method effectively addresses ion migration issues, significantly improving the photoelectric performance and long-term stability of the film. It also eliminates the need for complex preparation processes and is suitable for large-scale production.

[0039] Wherein, the step S5 is specifically as follows:

[0040] S51: dissolving the PbS quantum dots whose surfaces are modified with BMIM-BF4 in a fourth solution to form a film-forming solution;

[0041] S52: Add the film-forming solution to the surface of the ITO substrate and spin-coat it at 2000 rpm for 30 seconds to prepare a uniform quantum dot film; and add BMIM-BF4 solution to the surface of the spin-coated film and spin-coat it again to enhance the density and interface quality of the film.

[0042] S53: Annealing the prepared film at 80° C. for 10 minutes under nitrogen protection to improve the crystallization quality and interface stability of the quantum dot film.

[0043] Specifically, in step S51, the fourth solution includes toluene. The concentration of the membrane-forming solution is 350 mg / mL-450 mg / mL, preferably 400 mg / mL.

[0044] By introducing the ionic liquid BMIM-BF4 as a thin film regulator, the embodiment of the present invention can significantly enhance the density and interface quality of the thin film, thereby preventing the PbS quantum dot film formation process from being affected by the solvent volatilization rate and the surface ligand force, resulting in rough film surface and particle aggregation, which in turn affects the photoelectric performance of the film and the consistency of the device.

[0045] Example 1

[0046] Specifically, an embodiment of the present invention provides a method for preparing BMIM-BF4 modified PbS quantum dots.

[0047] Experimental steps:

[0048] S1: Dissolve PbS quantum dots in n-octane to prepare a 10 mg / mL PbS quantum dot solution;

[0049] S2: Dissolve BMIM-BF4 in ethanol to prepare a 0.01 mol / L first ionic liquid solution;

[0050] S3: adding a small amount of isopropanol to the first ionic liquid solution and stirring until the solution is homogeneous and transparent to form a mixed solution; then adding the mixed solution to the PbS quantum dot solution and stirring at 120° C. for 30 minutes to form a turbid solution;

[0051] S4: The turbid solution is subjected to centrifugal precipitation separation, and n-octane is added for washing to obtain PbS quantum dots with BMIM-BF4 surface modified.

[0052] Example 2

[0053] Specifically, an embodiment of the present invention provides a method for preparing a PbS quantum dot thin film and testing a device.

[0054] S51: PbS quantum dots with surface modified by BMIM-BF4 were dissolved in toluene to form a 400 mg / mL film-forming solution;

[0055] S52: Add the film-forming solution to the surface of the SnO2 / ITO substrate, spin-coat at 2000 rpm for 30 seconds, anneal at 100°C for 15 minutes to prepare a uniform PbS quantum dot film; and add BMIM-BF4 solution to the surface of the spin-coated film, and spin-coat again to enhance the density and interface quality of the film.

[0056] S53: Annealing the prepared film at 80° C. for 10 minutes under nitrogen protection to improve the crystallization quality and interface stability of the quantum dot film.

[0057] See Figure 2-Figure 4 . The ion migration inhibition performance and photoelectric response performance of the PbS quantum dot film in the second embodiment were tested respectively. By testing the IV characteristic curve of the PbS quantum dot film and observing the current hysteresis behavior under forward and reverse voltages, the ion migration inhibition performance of the PbS quantum dot film was determined. By measuring the photocurrent response spectrum of the PbS quantum dot film in the short-wave infrared (900-1600nm) band, its photoelectric conversion efficiency and detection sensitivity were evaluated.

[0058] like Figure 1 and Figure 2 As shown in Figure 2, the unmodified PbS quantum dot film has large hysteresis and large dark current. Figure 1 and Figure 3 As shown, the BMIM-BF4-modified film exhibits low hysteresis and dark current. Therefore, it can be seen that the embodiments of the present invention introduce the ionic liquid BMIM-BF4 as a surface ligand regulator and ion migration inhibitor for PbS quantum dots. During the preparation process, BMIM-BF4 coordinates with the iodide ions on the surface of the PbS quantum dots, significantly enhancing the ionic stability of the PbS quantum dot surface while optimizing the film formation quality, thereby improving the optoelectronic performance and long-term reliability of the PbS quantum dot detector.

[0059] The present invention also provides a PbS quantum dot detector, which is prepared by the above-mentioned PbS quantum dot detector preparation method. The PbS quantum dot detector comprises: a PbS quantum dot film modified with ITO, ZnO, and BMIM-BF4, MoO3, and Ag.

[0060] In summary, the present invention provides a novel method for modifying PbS quantum dot thin films using BMIM-BF₄. This method successfully addresses the performance degradation issue of PbS quantum dot detectors due to ion migration, enabling the fabrication of high-performance, highly stable photodetectors. This technology not only provides new insights into the development of quantum dot infrared detectors but also opens up new research directions for interface optimization and performance enhancement of future quantum dot optoelectronic materials.

[0061] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of the rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for preparing a PbS quantum dot detector, characterized in that: The following steps are involved: S1: dissolving PbS quantum dots in the first solution to prepare a PbS quantum dot solution; S2: dissolving 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (BMIM-BF4) in the second solution to prepare a first ionic liquid solution; S3: adding the third solution to the first ionic liquid solution, stirring until uniform and transparent, to form a mixed solution; and adding the mixed solution to the PbS quantum dot solution and stirring it a second time to form a turbid solution; S4: centrifugally precipitating and separating the turbid solution, and adding a detergent to wash it to obtain PbS quantum dots with BMIM-BF4 modified on the surface; S5: preparing a BMIM-BF4-modified PbS quantum dot film by using the PbS quantum dots whose surface is modified by BMIM-BF4; S6: Using ITO as the bottom electrode, ZnO, BMIM-BF4-modified PbS quantum dot film, MoO3 and Ag are deposited on its surface in sequence to form a pn heterojunction photodetector.

2. The method for preparing a PbS quantum dot detector according to claim 1, characterized in that: In step S1, the first solution includes: one or more combinations of n-hexane and n-octane; and the concentration of the PbS quantum dot solution is 8 mg / mL-12 mg / mL.

3. The method for preparing a PbS quantum dot detector according to claim 1, characterized in that: In step S2, the second solution includes ethanol; and the concentration of the first ionic liquid solution is 0.01 mol / L-0.02 mol / L.

4. The method for preparing a PbS quantum dot detector according to claim 1, characterized in that: In step S3, the third solution includes isopropanol; and the secondary stirring time is 20 minutes to 40 minutes.

5. The method for preparing a PbS quantum dot detector according to claim 1, characterized in that: In step S4, the detergent includes n-octane; and the washing times are greater than or equal to 2 times.

6. The method for preparing a PbS quantum dot detector according to claim 1, characterized in that: The step S5 is specifically as follows: S51: dissolving the PbS quantum dots whose surfaces are modified by BMIM-BF4 in a fourth solution to form a film-forming solution; S52: Add the film-forming solution to the surface of the ITO substrate and spin-coat it at 2000 rpm for 30 seconds to prepare a uniform quantum dot film; and add the BMIM-BF4 solution to the surface of the spin-coated film and spin-coat it again to enhance the density and interface quality of the film.

7. The method for preparing a PbS quantum dot detector according to claim 6, characterized in that: The step S5 further comprises: S53: annealing the prepared film at 80° C. for 10 minutes under nitrogen protection to improve the crystallization quality and interface stability of the quantum dot film.

8. The method for preparing a PbS quantum dot detector according to claim 6, characterized in that: In the step S51, the fourth solution includes toluene; and the concentration of the film-forming solution is 350 mg / mL-450 mg / mL.

9. A PbS quantum dot detector, characterized in that: The PbS quantum dot detector is prepared by any one of the PbS quantum dot detector preparation methods described in claims 1-8.

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