A self-driven perovskite heterojunction photodetector and its preparation method

Abstract

The present invention discloses a self-driven perovskite heterojunction photodetector and a preparation method thereof, relating to the field of photodetectors. The self-driven perovskite heterojunction photodetector includes a perovskite heterojunction disposed between one of the electrodes of the photodetector and the hole transport layer; the perovskite heterojunction is formed at the interface where a wide-bandgap perovskite absorption layer and a narrow-bandgap perovskite absorption layer are combined; the hole transport layer is used to drive holes to move in the direction of the electrode. By introducing a perovskite heterojunction structure into the photodetector, the combination of the two perovskite absorption layers enhances the light absorption capacity of the device, significantly improving the photocurrent of the perovskite photodetector. The high mobility of carriers in the perovskite material helps the electrodes to effectively absorb electrons and holes, thereby achieving a fast response of the perovskite photodetector. Different bandgap characteristics enable the two perovskite absorption layers to absorb light in different wavelength ranges, thereby achieving full-band response.

Description

Technical Field

[0001] The present invention relates to the technical field of photodetectors, and particularly to a self-powered perovskite heterojunction photodetector and a preparation method thereof. Background Art

[0002] A photodetector is a semiconductor device that converts an optical signal into an electrical signal. Conventional photodetectors usually require an external power supply to obtain good photoelectric response, which is costly and has a complex preparation process, restricting their use in certain specific application scenarios. On the other hand, with the popularization of application requirements, progress in materials science, and the concept of sustainable development, self-powered photodetectors with low energy consumption and simple structures have increasingly attracted attention and are expected to play a greater role in future optoelectronic applications.

[0003] Perovskite materials have received extensive attention due to their excellent optoelectronic properties. These materials have a high light absorption coefficient, adjustable bandgap, good carrier mobility, and long carrier lifetime, making them perform outstandingly in photodetectors and significantly improving the response performance of the devices. Therefore, self-powered photodetectors based on perovskite materials show great potential in the field of photodetection.

[0004] Responsivity and response speed are two important indicators for evaluating the performance of photodetectors. In a photodetector, responsivity refers to the sensitivity of the detector to an incident optical signal and, to a certain extent, determines the detection limit of light intensity; while the response speed describes how quickly the photodetector responds to the incident light and, to a large extent, determines the information transmission rate. However, in the reported self-powered perovskite photodetectors, there is generally a trade-off between responsivity and response speed. How to break through the trade-off between responsivity and response speed of perovskite self-powered photodetectors to achieve high-performance detection has always been a key research direction in the field of photodetectors.

[0005] Therefore, a self-powered perovskite heterojunction photodetector with high responsivity, fast response speed, and broadband response is proposed. Summary of the Invention

[0006] In view of the problems existing in the above-mentioned prior art, the present invention is proposed.

[0007] Therefore, the problems to be solved by the present invention are how to improve the responsivity and response speed of the photodetector and how to achieve full-band response.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: A self-driven perovskite heterojunction photodetector, which includes a perovskite heterojunction disposed between one of the electrodes of the photodetector and the hole transport layer; the perovskite heterojunction is formed at the interface where a wide-bandgap perovskite absorption layer and a narrow-bandgap perovskite absorption layer are combined; the hole transport layer is used to drive holes to move in the direction of the electrode.

[0009] As a preferred embodiment of the self-driven perovskite heterojunction photodetector of the present invention, it further includes a substrate and a first conductive layer disposed on the surface of the wide-bandgap perovskite absorption layer, and a second conductive layer disposed on the surface of the hole transport layer.

[0010] As a preferred embodiment of the self-driven perovskite heterojunction photodetector of the present invention, the material of the wide-bandgap perovskite absorption layer is CsPbI2Br, and the material of the narrow-bandgap perovskite absorption layer is MASnI3.

[0011] As a preferred embodiment of the self-driven perovskite heterojunction photodetector of the present invention, the material of the substrate is transparent glass, the material of the first conductive layer is ITO, and the material of the second conductive layer is silver.

[0012] As a preferred embodiment of the self-driven perovskite heterojunction photodetector of the present invention, the material of the hole transport layer is PEDOT:PSS.

[0013] As a preferred embodiment of the self-driven perovskite heterojunction photodetector of the present invention, the thickness of the wide-bandgap perovskite absorption layer is 100-200 nm, and the thickness of the narrow-bandgap perovskite absorption layer is 600-800 nm.

[0014] On the other hand, the present invention also provides a preparation method of a self-driven perovskite heterojunction photodetector, which is characterized in that it includes providing a substrate; forming a first conductive layer on the substrate; sequentially forming the above-mentioned wide-bandgap perovskite absorption layer and narrow-bandgap perovskite absorption layer on the first conductive layer; forming a hole transport layer on the narrow-bandgap perovskite absorption layer; forming a second conductive layer on the hole transport layer; and forming a perovskite heterojunction between the interfaces of the wide-bandgap perovskite absorption layer and the narrow-bandgap perovskite absorption layer.

[0015] As a preferred embodiment of the self-driven perovskite heterojunction photodetector of the present invention, the material of the first conductive layer is ITO, and it is deposited on the substrate by chemical vapor deposition.

[0016] As a preferred embodiment of the self-driven perovskite heterojunction photodetector of the present invention, wherein: the material of the wide-bandgap perovskite absorption layer is CsPbI2Br, the material of the narrow-bandgap perovskite absorption layer is MASnI3, and the material of the hole transport layer is PEDOT:PSS, which are sequentially spin-coated on the first conductive layer by a solution method.

[0017] As a preferred embodiment of the self-driven perovskite heterojunction photodetector of the present invention, wherein: the material of the second conductive layer is silver, which is deposited on the hole transport layer by vacuum evaporation.

[0018] The beneficial effects of the present invention are as follows: by introducing a perovskite heterojunction structure into the photodetector, the combination of the two perovskite absorption layers enhances the light absorption ability of the device, significantly improving the photocurrent of the perovskite photodetector. After adding the perovskite heterojunction structure to the photodetector, the built-in electric field generated promotes the drift motion of photogenerated carriers. At the same time, the high mobility of carriers in the perovskite material contributes to the effective absorption of electrons and holes by the electrodes, thus achieving a fast response of the perovskite photodetector. By introducing a perovskite heterojunction structure into the photodetector, the different bandgap characteristics enable the two perovskite absorption layers to absorb light in different wavelength ranges, thereby achieving full-band response. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a schematic structural diagram of a self-driven perovskite heterojunction photodetector.

[0021] Figure 2 It is the energy band diagram of the heterojunction structure of a self-driven perovskite heterojunction photodetector.

[0022] Figure 3 It is a curve graph showing the relationship between absorption, reflection, transmission and wavelength of a self-driven perovskite heterojunction photodetector.

[0023] Figure 4 It is the relationship spectrum between the perovskite thickness and light absorption of a perovskite photodetector at a wavelength of 400 nm.

[0024] Figure 5 It is the relationship spectrum between the perovskite thickness and light absorption of a perovskite photodetector at a wavelength of 600 nm.

[0025] Figure 6 Spectrum of the relationship between perovskite thickness and light absorption of a perovskite photodetector at a wavelength of 900 nm.

[0026] Figure 7 Graph of the relationship between light absorption and wavelength of a perovskite photodetector for different combinations of perovskite thicknesses.

[0027] Figure 8 Simulation diagram of the influence of perovskite doping concentration on external quantum efficiency.

[0028] Figure 9 Simulation diagram of the influence of perovskite lifetime on external quantum efficiency.

[0029] Figure 10 Simulation diagram of the influence of perovskite carrier mobility on external quantum efficiency.

[0030] Figure 11 Response time of the self-driven perovskite heterojunction photodetector of the present invention.

[0031] Figure 12 Simulation diagram of the influence of perovskite thickness on response time.

[0032] Figure 13 Simulation diagram of the influence of perovskite doping concentration on response time.

[0033] In the figure: 1. Wide-bandgap perovskite absorption layer; 2. Narrow-bandgap perovskite absorption layer; 3. First conductive layer; 4. Hole transport layer; 5. Second conductive layer; 6. Substrate. Specific embodiments

[0034] To make the above objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings of the specification.

[0035] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0036] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The appearances of "in one embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or alternative embodiments that exclude each other.

[0037] Embodiment 1

[0038] Refer to Figures 1 to 8, which is the first embodiment of the present invention. This embodiment provides a self-powered perovskite heterojunction photodetector. The self-powered perovskite heterojunction photodetector sequentially includes a substrate 6, a first conductive layer 3, a wide-bandgap perovskite absorption layer 1, a narrow-bandgap perovskite absorption layer 2, a hole transport layer 4, and a second conductive layer 5 along the incident light direction.

[0039] Specifically, the substrate 6 is transparent glass. The first conductive layer 3 is a transparent conductive oxide, the material of which is ITO, and the thickness is 100 nm. The first conductive layer 3 is an electrode of the device.

[0040] Specifically, the wide-bandgap perovskite absorption layer 1, the material of which is CsPbI2Br, the bandgap of which is 1.86 eV, and the thickness is 130 nm.

[0041] Specifically, the narrow-bandgap perovskite absorption layer 2, the material of which is MASnI3, the bandgap of which is 1.3 eV, and the thickness is 740 nm.

[0042] Specifically, the material of the hole transport layer 4 is PEDOT:PSS, and the thickness is 60 nm.

[0043] The material of the second conductive layer 5 is silver, and the thickness is 200 nm. The function of the second conductive layer 5 is to serve as the other electrode of the device.

[0044] The self-powered perovskite heterojunction photodetector of the present invention shows a band diagram as Figure 2 shown, clearly indicating the movement of carriers inside the device. After being generated, electrons move towards the first conductive layer 3 and are collected by the electrode, while holes move in the opposite direction and, under the further drive of the hole transport layer 4, move towards the second conductive layer 5 and are collected by the electrode.

[0045] In order to improve the device performance of the self-powered perovskite heterojunction photodetector of the present invention, optimization was mainly carried out from two aspects: optical performance and electrical performance.

[0046] As Figure 3 shown, the self-powered perovskite heterojunction photodetector of the present invention exhibits strong light absorption ability in the full wavelength range, fully demonstrating the excellent optoelectronic performance of the perovskite photodetector.

[0047] First, for the perovskite heterojunction structure, that is, the selection of the thickness of the perovskite absorption layer. When the perovskite absorption layer is at the optimal thickness, the photodetector shows a high level in terms of light absorption in the full wavelength range.

[0048] At different wavelengths, the influence of the thickness of the perovskite on light absorption shows significant differences. In the present invention, as Figures 4 to 6Three typically representative wavelengths are explored, namely short wavelength (400 nm), critical wavelength (the cut-off wavelength of wide-bandgap perovskite, i.e., 600 nm), and long wavelength (900 nm). The research results show that the light absorption performances of different perovskite thickness combinations vary significantly at different wavelengths. Specifically, the perovskite thickness combination with strong light absorption at short wavelengths has weak light absorption at long wavelengths, while the perovskite thickness combination with strong light absorption at long wavelengths has strong light absorption performance at short wavelengths.

[0049] Therefore, through the screening and comparison of a large amount of data, the present invention presents curves of light absorption varying with wavelength under three typical perovskite thickness combinations, as Figure 7 shown. It can be observed that when the thickness of the wide-bandgap perovskite absorption layer 1 is 130 nm and the thickness of the narrow-bandgap perovskite absorption layer 2 is 740 nm, the self-driven perovskite heterojunction photodetector of the present invention exhibits a relatively high level in terms of light absorption in the full wavelength range. In addition, Figure 7 shows the light field distribution under different perovskite thickness combinations at an incident wavelength of 600 nm, indicating that when the thickness of the wide-bandgap perovskite absorption layer 1 is 130 nm and the thickness of the narrow-bandgap perovskite absorption layer 2 is 740 nm, the perovskite heterojunction layer excites a stronger resonance mode and exhibits stronger light absorption in the full wavelength range.

[0050] To study the perovskite heterojunction structure in the present invention more deeply, the present invention explores the effects of the doping concentration of the perovskite absorption layer material, the lifetime and mobility of carriers on the device performance, as Figures 8 to 10 shown. The results show that, under the condition that other conditions remain unchanged, the external quantum efficiency increases with the increase of the doping concentration of the narrow-bandgap perovskite absorption layer 2, while the external quantum efficiency of the wide-bandgap perovskite absorption layer 1 shows a trend of increasing first and then decreasing. This is because, with the increase of the doping concentration of the narrow-bandgap perovskite absorption layer 2, the material can effectively absorb light of more wavelengths, resulting in an increase in the number of photo-generated carriers, thereby improving the external quantum efficiency; for the wide-bandgap perovskite absorption layer 1, the increase in the initial doping concentration will increase the number of photo-generated carriers, but when the doping concentration is too high, the recombination phenomenon between carriers will increase, thereby leading to a decrease in the external quantum efficiency. In addition, it can also be seen from Figures 8 to 10 that within the given range of carrier lifetime and mobility, the influence of carrier lifetime and mobility on the external quantum efficiency is relatively small, so no detailed discussion will be carried out.

[0051] Response time is an important parameter for evaluating the performance of perovskite heterojunction photodetectors. Therefore, the present invention further studies the response time of the self-driven perovskite heterojunction photodetector in the present invention. Figure 11Shows the average terminal current density curve of the optoelectronic detector device of the present invention. By calculation, the response time of the device is 40.3 picoseconds, achieving an ultrafast response. At the same time, the present invention also deeply explores the influence of other factors on the response time of the device, such as the thickness and doping concentration of the perovskite material, as Figure 12 and Figure 13 shown. The results show that as the thickness of the perovskite absorption layer increases, the response time becomes longer and the device performance decreases. This is because as the thickness of the perovskite absorption layer increases, the migration distance of carriers also increases, causing carriers to experience more recombination processes before reaching the electrodes, thus resulting in an increase in the response time. In addition, the present invention also studies the influence of the doping concentration of the perovskite material on the response time. The results show that under the condition that other conditions remain unchanged, the response time increases with the increase of the doping concentration of the narrow-bandgap perovskite, while the response time of the wide-bandgap perovskite shows a decreasing trend. This is because as the doping concentration of the narrow-bandgap increases, the recombination probability of carriers increases, thus prolonging the response time; while for the wide-bandgap perovskite, the increase in the doping concentration will enhance the built-in electric field, which helps carriers reach the electrodes faster, thus reducing the response time.

[0052] Example 2

[0053] This Example 2 uses Figure 1 structure to fabricate a perovskite heterojunction optoelectronic detector, and the specific preparation process is as follows:

[0054] S1: Provide a substrate 6.

[0055] Specifically, use deionized water, ethanol, and acetone to clean the substrate to ensure that the surface is pollution-free. After cleaning, dry it in an oven at a temperature of about 100°C;

[0056] S2: Prepare the first conductive layer 3.

[0057] Specifically, deposit an ITO layer on the substrate 6 by chemical vapor deposition (CVD) with a thickness of 100 nm. After deposition, perform annealing treatment at a temperature of about 200°C for 1 hour;

[0058] S3: Deposition of the wide-bandgap perovskite layer: Use the solution method to coat the wide-bandgap perovskite precursor solution on the ITO layer, with a spin coating speed usually of 2000 - 3000 rpm and a spin coating time of 30 seconds. Then perform heat treatment at 60°C for 10 minutes;

[0059] S4: Deposition of the narrow-bandgap perovskite layer: Coat the narrow-bandgap perovskite precursor solution on the wide-bandgap perovskite layer, with the same spin coating speed and time as the wide-bandgap perovskite, and perform heat treatment at 100°C for 30 minutes;

[0060] S5: Hole transport layer deposition: Coat the hole transport layer material (PEDOT:PSS) on the narrow-bandgap perovskite layer, with a spin-coating speed of 3000 rpm, a spin-coating time of 30 seconds, and heat treatment at 100 °C for 10 minutes;

[0061] S6: Silver electrode deposition: Deposit a silver electrode on the hole transport layer using vacuum evaporation, with a thickness of 200 nm. After evaporation, perform annealing treatment at a temperature of about 150 °C for 30 minutes.

[0062] Comparative Example 1

[0063] Specifically, use Figure 1 a structure to establish a simulation model of a perovskite heterojunction photodetector. The specific setting process is as follows:

[0064] The substrate is stacked by indium tin oxide and a transparent glass layer.

[0065] The light-absorbing layer, which is set on the substrate, uses a perovskite with a bandgap of 1.86 eV and a thickness of 130 nm.

[0066] The hole transport layer, which is set on the light-absorbing layer, uses PEDOT:PSS and has a thickness of 60 nm.

[0067] The metal electrode, which is set on the hole transport layer, is made of silver and has a thickness of 200 nm.

[0068] In summary, the beneficial effects of the present invention are as follows:

[0069] 1. By setting the perovskite heterojunction structure between the first electrode layer and the hole transport layer, the present invention forms a new charge transport structure, thereby accelerating the response speed of carriers and achieving a fast response of the device.

[0070] 2. Using the perovskite heterojunction structure, the present invention can not only accelerate the response speed of carriers and achieve a fast response of the device, but also achieve full-band response. Since the two absorption layers of the perovskite heterojunction have different absorption characteristics for light of different wavelengths, compared with a single perovskite absorption layer, the present invention can achieve a wider spectral response.

[0071] 3. The present invention adopts the perovskite heterojunction structure, which enhances the light absorption ability of the device, significantly improves the photocurrent of the perovskite photodetector, and successfully solves the trade-off problem between the responsivity and the response speed in the perovskite photodetector, which has important practical significance.

[0072] It should be noted that the above embodiments are only used to illustrate the preferred technical solutions of the present invention, and should not be construed as a limitation of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

[0073] It should be noted that the above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A self-driven perovskite heterojunction photodetector, characterized in that: Comprising, A perovskite heterojunction disposed between a first conductive layer (3) and a hole transport layer (4) in the photodetector; The perovskite heterojunction is formed at the interface where a wide-bandgap perovskite absorption layer (1) and a narrow-bandgap perovskite absorption layer (2) are combined; The hole transport layer (4) is used to drive holes to move in the direction of the electrode; The material of the wide-bandgap perovskite absorption layer (1) is CsPbI2Br, and the material of the narrow-bandgap perovskite absorption layer (2) is MASnI3; The material of the hole transport layer (4) is PEDOT:PSS; The thickness of the wide-bandgap perovskite absorption layer (1) is 100 - 200 nm, and the thickness of the narrow-bandgap perovskite absorption layer (2) is 600 - 800 nm.

2. The self-driven perovskite heterojunction photodetector according to claim 1, wherein: It further includes a substrate (6) and a first conductive layer (3) disposed on the surface of the wide-bandgap perovskite absorption layer (1), and a second conductive layer (5) disposed on the surface of the hole transport layer (4).

3. The self-driven perovskite heterojunction photodetector according to claim 2, wherein: The material of the substrate (6) is transparent glass, the material of the first conductive layer (3) is ITO, and the material of the second conductive layer (5) is silver.

4. A method for preparing a self-driven perovskite heterojunction photodetector according to any one of claims 1 to 3, characterized in that: Comprising, Providing a substrate (6); Forming a first conductive layer (3) on the substrate (6); Successively forming a wide-bandgap perovskite absorption layer (1) and a narrow-bandgap perovskite absorption layer (2) on the first conductive layer (3); Forming a hole transport layer (4) on the narrow-bandgap perovskite absorption layer (2); Forming a second conductive layer (5) on the hole transport layer (4); A perovskite heterojunction is formed between the interfaces of the wide-bandgap perovskite absorption layer (1) and the narrow-bandgap perovskite absorption layer (2).

5. The preparation method according to claim 4, characterized in that: The material of the first conductive layer (3) is ITO, and it is deposited on the substrate (6) by chemical vapor deposition.

6. The preparation method according to claim 5, wherein: The wide-bandgap perovskite absorption layer (1), the narrow-bandgap perovskite absorption layer (2), and the hole transport layer (4) are respectively spin-coated on the first conductive layer (3) by solution method in sequence.

7. The preparation method according to claim 6, characterized in that: The material of the second conductive layer (5) is silver, and it is deposited on the hole transport layer (4) by vacuum evaporation method.

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