Asymmetric electrode contact-induced self-driven 2D perovskite single crystal photodetector, preparation method and application

Abstract

The present invention discloses an asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector, a preparation method and application thereof, wherein the preparation method comprises the following steps: S1, synthesis of a perovskite precursor solution: PEAI and PbI 2 The powder is dissolved in a γ-butyrolactone solvent to prepare a perovskite precursor solution; S2, growth of a 2D perovskite single crystal: after the perovskite precursor solution is fully dissolved, the temperature is reduced to 60°C at a controlled cooling rate of 1°C / h, and after maintaining for 5 hours, a single crystal film floating on the surface of the solution is obtained; S3, preparation of a photodetector: the single crystal film is taken out and rinsed; Ag electrodes and Pt electrodes are prepared respectively to obtain a photodetector; the preparation method of the present application is simple and easy, has no strict requirements for the preparation environment, and the device is stable. The 2D perovskite single crystal photodetector prepared by the method of the present application has the characteristics of self-driving and can work without an external power supply.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric detection technology, and in particular to an asymmetric electrode contact-induced self-driven 2D perovskite single crystal photoelectric detector, a preparation method and an application thereof. Background Art

[0002] In recent years, organic-inorganic hybrid perovskites have been widely used in optoelectronic devices such as solar cells, light-emitting diodes, photodetectors and semiconductor lasers. Perovskite semiconductor materials have the advantages of large light absorption coefficient, high carrier mobility, long carrier diffusion length, and solution processing, and are one of the most promising optoelectronic semiconductor materials. So far, different types of photodetectors have been realized using perovskite materials (thin films, bulk single crystals and micro / nanowires). Photodetectors have the ability to convert light into electrical signals and are key components of optoelectronic systems. They have been widely used in image sensing, optical communications and environmental monitoring.

[0003] In recent years, research on organic-inorganic lead halide two-dimensional (2D) perovskites is booming. 2D perovskites have a layered structure that is completely different from 3D perovskites, with organic and inorganic layers staggered, resulting in more stable 2D perovskite materials. At the same time, 2D organic-inorganic lead halide perovskite single crystals have attracted increasing attention due to their superior properties, such as long carrier lifetime and low defect density, which increases their potential in photodetector applications. 2D layered organic-inorganic hybrid perovskite single crystals show better performance than 3D perovskite single crystals in practical applications due to their higher stability and excellent optoelectronic properties.

[0004] Most photodetectors are designed and prepared based on the metal-semiconductor-metal (MSM) structure, which has the advantages of being controllable, stable and easy to manufacture. However, due to the same Schottky barrier height, traditional MSM photodetectors always require an external power source as a driving force to separate photogenerated carriers and generate photocurrent. From an application point of view, there is an urgent need for a perovskite photodetector that does not require an external power supply, that is, a photodetector that operates without any power supply, that is, a self-powered photodetector, to save energy, reduce device size, and be used under extreme conditions. Summary of the invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a method for preparing an asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector.

[0006] Furthermore, the present application also provides an asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector.

[0007] Furthermore, the present application also provides an application of an asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector.

[0008] The technical solution adopted by the present invention is:

[0009] A method for preparing an asymmetric electrode contact-induced self-driven 2D perovskite single crystal photodetector comprises the following steps:

[0010] S1. Synthesis of perovskite precursor solution: PEAI and PbI2 powders were dissolved in γ-butyrolactone solvent to prepare a 2M perovskite precursor solution, and the perovskite precursor solution was placed on a 90°C magnetic stirrer and stirred until fully dissolved;

[0011] S2, growth of 2D perovskite single crystal: after the perovskite precursor solution in step S1 is fully dissolved, the stirring is stopped, the temperature is reduced to 70°C at a controlled cooling rate of 1°C / h, and a small single crystal film is grown at the solution-air interface. When the temperature is reduced to 60°C, the lateral size of the single crystal film becomes larger. After maintaining for 5 hours, a larger single crystal film floating on the surface of the solution is obtained;

[0012] S3. Preparation of photodetector: Take out the single crystal film floating on the surface of the solution in step S2, and repeatedly rinse it with anti-solvent to obtain a high-quality 2D perovskite single crystal film; place the mask vertically and tightly on top of the single crystal film, place it in an ion sputtering instrument, prepare Ag electrode and Pt electrode respectively, and obtain a photodetector.

[0013] Furthermore, in step S1, the molar ratio of PEAI to PbI2 powder is 2:1.

[0014] Furthermore, in step S1, the volume of the γ-butyrolactone solvent is 5 ml.

[0015] Furthermore, in step S3, the size of the electrode on the mask is 1 mm×1 mm, and the width of the gap between the two electrodes is 100 μm.

[0016] Further, in step S3, the mask is placed vertically and closely on the single crystal film, and placed in an ion sputtering apparatus to prepare the Ag electrode and the Pt electrode respectively, specifically:

[0017] S31, covering the electrode position on one side of the mask plate, placing the single crystal film and the mask plate vertically attached to the single crystal film in an ion sputtering apparatus, and evaporating to obtain a Ag electrode;

[0018] S32, taking out the device on which the Ag electrode has been evaporated, covering the position where the Ag electrode has been evaporated and exposing the portion covered in step S31, placing it in an ion sputtering apparatus, and evaporating to obtain a Pt electrode material.

[0019] Furthermore, the present application also provides an asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector, which is prepared using the above-mentioned asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector preparation method.

[0020] Furthermore, the present application also provides an application of the above-mentioned asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector as an imaging medium.

[0021] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0023] Figure 1 (a) is a surface scanning electron microscope image of a 2D single crystal film;

[0024] Figure 1 (b) is a periodic layered scanning image of a 2D single crystal film;

[0025] Figure 2 This is the X-ray diffraction spectrum of the 2D single crystal film material;

[0026] Figure 3 (a) UV-visible absorption spectrum of 2D single crystal film;

[0027] Figure 3 (b) Photoluminescence spectrum of 2D single crystal film;

[0028] Figure 4 (a) is a photoelectric characteristic curve of the photodetector provided in Example 2 of the present application;

[0029] Figure 4 (b) is a stability test curve of the photoelectric detector provided in Example 2 of the present application in an air environment;

[0030] Figure 4 (c) is the transient light response of the photodetector provided in Example 2 of the present application under 0V illumination;

[0031] Figure 4 (d) Figure 4 (c) Single-cycle transient photoresponse shown;

[0032] Figure 5 (a) is a schematic diagram of an imaging system using the photodetector prepared in Example 2 of the present application as an imaging medium;

[0033] Figure 5 (b) is the obtained imaging pattern;

[0034] Figure 5 (c) and Figure 5 (d) Using MATLAB Figure 5 (b) The gray value is extracted from the red line marked in the imaging pattern;

[0035] Figure 6 This is a schematic diagram of the structure of the photodetector prepared in Example 2 of the present application. DETAILED DESCRIPTION

[0036] The following embodiments of the technical solution of the present invention are described in detail in conjunction with specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0037] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the invention belongs.

[0038] Example 1

[0039] This embodiment provides a method for preparing an asymmetric electrode contact-induced self-driven 2D perovskite single crystal photodetector, comprising the following steps:

[0040] S1. Synthesis of perovskite precursor solution: PEAI and PbI2 powders were dissolved in γ-butyrolactone solvent to prepare a 2M perovskite precursor solution, and the perovskite precursor solution was placed on a 90° C. magnetic stirrer and stirred until fully dissolved.

[0041] Specifically, in this step, the molar ratio of PEAI to PbI2 powder is 2: 1. The volume of γ-butyrolactone solvent is 5 ml.

[0042] After the perovskite precursor solution is obtained by configuring PEAI and PbI2, the perovskite precursor solution is placed on a 90° C. magnetic stirrer and stirred overnight until a clear solution is formed, so that the PEAI and PbI2 powders are fully dissolved in the γ-butyrolactone solvent.

[0043] S2. Growth of 2D perovskite single crystals: After the perovskite precursor solution described in step S1 is fully dissolved, stirring is stopped, and the temperature is reduced to 70°C at a controlled cooling rate of 1°C / h. A small single crystal film is grown at the solution-air interface. When the temperature is cooled to 60°C, the lateral size of the single crystal film becomes larger. After maintaining for 5 hours, a larger single crystal film floating on the surface of the solution is obtained. The single crystal film is a (PEA)2PbI4 single crystal, and the absorption edge of the (PEA)2PbI4 single crystal is located at 540nm.

[0044] S3. Preparation of photodetector: Take out the single crystal film floating on the surface of the solution in step S2, and repeatedly rinse it with anti-solvent to obtain a high-quality 2D perovskite single crystal film; place the mask vertically and tightly on top of the single crystal film, place it in an ion sputtering instrument, prepare Ag electrode and Pt electrode respectively, and obtain a photodetector.

[0045] The size of the electrode on the mask is 1 mm×1 mm, and the width of the gap between the two electrodes is 100 μm.

[0046] In step S3, the mask is placed vertically and closely on the single crystal film, and placed in an ion sputtering apparatus to prepare Ag electrodes and Pt electrodes respectively, which specifically includes the following steps:

[0047] S31, covering the electrode position on one side of the mask plate, placing the single crystal film and the mask plate vertically attached to the single crystal film in an ion sputtering apparatus, and evaporating to obtain a Ag electrode.

[0048] S32, taking out the device on which the Ag electrode has been evaporated, covering the position where the Ag electrode has been evaporated and exposing the portion covered in step S31, placing it in an ion sputtering apparatus, and evaporating to obtain a Pt electrode material.

[0049] Example 2

[0050] In this embodiment, the present application provides an asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector, which is prepared by the asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector preparation method described in Example 1. The prepared photodetector is as follows Figure 6 shown.

[0051] The photodetector preparation method of the present application is simple and easy, has no strict requirements for the preparation environment and the device is stable. The 2D perovskite single crystal photodetector prepared by the method of the present application has the characteristics of self-driving and can work without an external power supply. The photodetector has high spectral responsivity and stability and can be used for the detection of long-term optical signals.

[0052] The photodetector prepared by the method of the present application is composed of metal electrodes with different work functions and a 2D perovskite single crystal; this asymmetric contact electrode with different work functions introduces a strong built-in electric field due to the asymmetric Schottky contact barrier. For the photodetector, the existence of the built-in electric field can effectively prevent the recombination of photogenerated electron-hole pairs and effectively separate photogenerated carriers, thereby converting the acquired light signal into an electrical signal, realizing the detection of the light signal and realizing the self-driving of the detector.

[0053] test

[0054] In order to further detect the morphology and performance of the asymmetric electrode contact-induced self-driven 2D perovskite single crystal photodetector prepared in this application, the prepared detector was tested and analyzed as follows.

[0055] Figure 1 This is a surface scanning electron microscope image of a 2D single crystal film material. Figure 1 (a) shows a scanning electron microscope (SEM) image of the flat surface showing a very smooth surface, while Figure 1 (b) shows the periodic layered morphology, which is completely consistent with the layered structure of 2D perovskite single crystal. From the scanning image, it can be clearly observed that the 2D perovskite single crystal film was successfully synthesized by the method of the present application.

[0056] Figure 2 It is the X-ray diffraction spectrum (XRD) of the single crystal film material. XRD is the most intuitive means of evaluating the quality of the reaction material synthesis. The diffraction peaks reflected by the curve are highly matched with each crystal plane and no redundant diffraction peaks appear, indicating that the perovskite single crystal material prepared in this application has high synthesis quality.

[0057] Figure 3 is the UV-visible absorption and photoluminescence curve of the perovskite single crystal film material, where: Figure 3 (a) is the UV-visible absorption spectrum of (PEA)2PbI4; Figure 3 (b) Photoluminescence spectrum of (PEA)2PbI4 single crystal.

[0058] Depend on Figure 3 (a) It can be seen that the single crystal film exhibits broadband absorption in the visible light region, with a clear absorption edge at ≈550nm. Figure 3 (b) It can be seen that the photoluminescence peak is located at ≈530nm and the half-peak width is less than 20nm. The above results indicate that a 2D perovskite single crystal film with good crystallinity was successfully synthesized.

[0059] Figure 4The photoelectric characteristic curve of the single crystal film material detector. Spectral response is an important indicator of the detector, which indicates the strength of the ability to detect light. It can be seen from the test curve that the detector prepared in this application successfully realizes the wide spectrum detection of visible light.

[0060] like Figure 4 As shown in (a), the detector shows a broadband photoresponse in the visible light region, with a sharp drop in the photoresponse at ≈550 nm, corresponding to the absorption curve of the material, and a high responsivity of 110 mA / W at 530 nm.

[0061] Figure 4 (b) is a stability test of the 2D single crystal in an air environment. The experiment tested the change in the spectral responsivity of the single crystal within 7 weeks. It can be observed from the curve that the spectral responsivity is almost unchanged in an atmospheric environment with a humidity of 50%, proving that the heterojunction perovskite single crystal photodetector prepared in this application has high air stability and can be used for long-term optical signal detection.

[0062] Response time is also an important parameter for evaluating detector performance. It determines the ability to follow fast-changing light signals. Figure 4 (c) shows the transient photoresponses of the photodetectors under illumination at 0 V. They exhibit fast, reproducible, and stable responses.

[0063] Figure 4 (d) Figure 4 (c) shows the single-cycle transient photoresponse. When a 355nm pulsed laser is irradiated on the surface of the photodetector, the rise time and decay time are 1.2 and 582μs, respectively, at 0V bias. The ultrafast response time of the photodetector indicates that the fabricated photodetector has the potential to track fast optical signals.

[0064] The photoelectric detector produced by the present invention is not only useful in photoelectric detection, but also has practical value in imaging, and can be used as an imaging medium. Figure 5 As shown in Figure 1, an imaging system using photodetectors as sensing pixels was constructed. Figure 5 As shown in (a). Use a laser cutting machine to make an object with a hollow pattern on a steel plate (the pattern is the motto of Harbin Normal University - Dunpin, Lixue, Hongyi, Zhiyuan) as the object of the imaging system. The object is mounted on a computer-controlled XY translation stage and can move continuously in the horizontal and vertical directions. A 532nm laser (10mW) is used as the test light source. As the translation stage moves, the photocurrent generated by the photodetector is extracted and recorded by the phase-locked amplifier and the computer, and is recorded simultaneously with the position coordinates of the object. Then, the image is acquired by combining the current intensity and position coordinates. As shown Figure 5(b) As shown in the image, it can be observed that the test image has clear boundaries and is highly consistent with the shape of the target object. Figure 5 The red line marked in (b) extracts the gray value, such as Figure 5 (c), 5(d). The grayscale value changes from high to low, corresponding to the image boundary. This shows that the imaging system has high fidelity characteristics using heterojunction single crystal photodetectors as sensing pixels. These results show that heterojunction single crystal photodetectors can meet the requirements of imaging systems without any external power supply.

[0065] In this application, unless otherwise clearly specified and limited, the terms "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] In the specification of the present invention, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, systems and techniques are not shown in detail so as not to obscure the understanding of this specification.

[0067] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, systems, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, systems, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for preparing asymmetric electrode contact-induced self-driven 2D perovskite single crystal photodetector, characterized in that: The steps include: S1. Synthesis of perovskite precursor solution: PEAI and PbI2 powders were dissolved in γ-butyrolactone solvent to prepare a 2M perovskite precursor solution, and the perovskite precursor solution was placed on a 90°C magnetic stirrer and stirred until fully dissolved; S2, growth of 2D perovskite single crystal: after the perovskite precursor solution in step S1 is fully dissolved, the stirring is stopped, the temperature is reduced to 70°C at a controlled cooling rate of 1°C / h, and a small single crystal film is grown at the solution-air interface. When the temperature is reduced to 60°C, the lateral size of the single crystal film becomes larger. After maintaining for 5 hours, a larger single crystal film floating on the surface of the solution is obtained; S3. Preparation of photodetector: Take out the single crystal film floating on the surface of the solution in step S2, and repeatedly rinse it with anti-solvent to obtain a high-quality 2D perovskite single crystal film; place the mask vertically and tightly on top of the single crystal film, place it in an ion sputtering instrument, prepare Ag electrode and Pt electrode respectively, and obtain a photodetector.

2. The method for preparing the asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector according to claim 1, characterized in that: In the step S1, the molar ratio of PEAI to PbI2 powder is 2:

1.

3. The method for preparing the asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector according to claim 2, characterized in that: In the step S1, the volume of the γ-butyrolactone solvent is 5 ml.

4. The method for preparing the asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector according to claim 1, characterized in that: In the step S3, the size of the electrode on the mask is 1 mm×1 mm, and the width of the gap between the two electrodes is 100 μm.

5. The method for preparing the asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector according to claim 4, characterized in that: In the step S3, the mask is placed vertically and closely on the single crystal film, and placed in an ion sputtering apparatus to prepare the Ag electrode and the Pt electrode respectively, specifically: S31, covering the electrode position on one side of the mask plate, placing the single crystal film and the mask plate vertically attached to the single crystal film in an ion sputtering apparatus, and evaporating to obtain a Ag electrode; S32, taking out the device on which the Ag electrode has been evaporated, covering the position where the Ag electrode has been evaporated and exposing the portion covered in step S31, placing it in an ion sputtering apparatus, and evaporating to obtain a Pt electrode material.

6. An asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector, which is prepared by the asymmetric electrode contact induced self-driven 2D perovskite single crystal photodetector preparation method according to any one of claims 1 to 5.

7. Use of the asymmetric electrode contact-induced self-driven 2D perovskite single crystal photodetector as claimed in claim 6 as an imaging medium.

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