Bi-based organic-inorganic perovskite single crystal film photoelectric detector

Abstract

The invention provides a Bi-based organic-inorganic perovskite single crystal thin film photoelectric detector, which is characterized in that Au is used as an electrode material, the surface of a Bi-based organic-inorganic perovskite single crystal thin film is covered with an array structure mask plate, and an Au top electrode array is formed on the surface of the Bi-based organic-inorganic perovskite single crystal thin film through a vacuum thermal precipitation technology; according to the invention, a vertical device structure of asymmetric electrodes is designed, Au is used as a top electrode and ITO is used as a bottom electrode, and the constructed organic-inorganic hybrid perovskite photoelectric detector has a self-powered characteristic and shows the characteristic of photoelectric response to a specific dual-band; the controllable preparation of the non-lead-based organic-inorganic perovskite single crystal film with dual-band photoelectric response can be realized, the operation is convenient, the film is safe and reliable, and the photoelectric detection capability is high.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric detectors, and in particular to a Bi-based organic-inorganic perovskite single crystal thin film photoelectric detector. Background Art

[0002] Compared with polycrystalline materials, lead-free halide perovskite single crystals have better stability, longer carrier diffusion length, higher carrier mobility and longer carrier lifetime. This is attributed to the characteristics of fewer grain boundaries, higher crystallinity and low defect state density in single crystal materials. Therefore, lead-free halide perovskite single crystals are considered to be a promising photosensitive material for optoelectronic devices, and photodetectors constructed with single crystal materials as functional layers have achieved superior performance. However, the thickness of lead-free halide perovskite single crystals needs to be controlled at a certain level to effectively improve the energy conversion efficiency.

[0003] At present, the spatial confinement method is a bottom-up process for growing single crystal films over a larger area. The spatial confinement method has the characteristics of simple operation, mild growth conditions, and no restrictions on operating environment and large equipment. The growth of single crystal films based on the spatial confinement method does not rely on specific substrates and strict lattice matching, which will be beneficial to the monolithic integration of lead-free halide perovskite single crystal films with the required substrate. In general, the driving force of spatial confinement growth comes from inverse temperature crystallization and solvent evaporation, in which the supersaturation of the solution plays a key role in controlling the size and quality of the single crystal.

[0004] In a large number of previous studies, lead-free halide perovskite single crystals as photofunctional layers only absorb and respond to specific wavelengths. With the continuous development of optoelectronic technology, optoelectronic devices with wide-band and dual-frequency response have attracted widespread attention from researchers. Recent studies have shown that CsPbBr3 and Cs4PbBr6 composite perovskite layers can achieve broadband achromatic delay in the visible and near-infrared (532-800nm) ranges, and the devices show potential application prospects in optical communications. In addition, photodetectors based on (C4H9NH3)2PbI4 / (C4H9NH3)2(CH3NH3)Pb2I7 also show the characteristics of dual-band response. Although many beneficial progress has been made in previous studies, the toxicity of lead-based materials still limits their application and development. Therefore, it is urgent to prepare environmentally friendly, high-photoelectric performance, and specific dual-band response non-lead-based perovskites through a simple synthesis process. Bi-based halide perovskite systems have been shown to have high quantum efficiency and beneficial air stability. At present, existing studies have shown that Cs3Bi2Br9 / Cs3BiBr6-based photodetectors can achieve specific dual-band photoelectric responses (365nm and 450nm), but the device needs to be biased at 2V to achieve photocurrent response. The external bias not only increases the working energy consumption but also increases the device cost. Therefore, the present invention will design Bi organic-inorganic perovskite photodetectors based on asymmetric electrodes to achieve self-powered characteristics and specific dual-band photoelectric responses. Summary of the invention

[0005] The purpose of the present invention is to provide a Bi-based organic-inorganic perovskite single crystal thin film photodetector that can achieve self-powered characteristics and has a specific dual-band photoelectric response.

[0006] To achieve the above-mentioned purpose, the present invention proposes a Bi-based organic-inorganic perovskite single crystal thin film photodetector, which uses Au as the electrode material, covers the surface of the Bi-based organic-inorganic perovskite single crystal thin film with an array structure mask, and forms an Au top electrode array on the surface of the Bi-based organic-inorganic perovskite single crystal thin film through vacuum thermal precipitation technology.

[0007] Preferably, the preparation method of the Bi-based organic-inorganic perovskite single crystal thin film is as follows:

[0008] S1: Preparation of stable perovskite precursor solution

[0009] S1.1: Mix two solvents, N-N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), in a certain volume ratio to obtain a uniform and transparent mixed solvent;

[0010] S1.2: Taking A3Bi2X9 as the basic structural formula of perovskite, weigh the precursors of the halogenated organic salt and the halogenated metal salt according to the stoichiometric molar ratio, add them to the above mixed solvent, heat the mixture on a hot plate and stir continuously to obtain a saturated solution of the precursor;

[0011] S1.3: The above-mentioned precursor saturated solution is filtered out by using a 0.22 μm PTFE organic phase filter to remove the precipitate to obtain a clarified precursor saturated solution;

[0012] S2: Monolithic integration of Bi-based organic and inorganic perovskite single crystal films

[0013] S2.1: n-hexane and octadecyltrichlorosilane (OTS) are mixed in a certain volume ratio to form a uniform transparent solution, which is used as a solvent for the subsequent hydrophobic treatment of the glass substrate;

[0014] S2.2: Cut the required substrate into a certain size for single crystal thin film integration, and then clean the substrate in acetone, deionized water, and ethanol in sequence by ultrasonic cleaning, and blow dry with nitrogen for later use;

[0015] S2.3: Immerse the cleaned glass substrate in the hydrophobic solvent of S2.1 to perform hydrophobic treatment; then, ultrasonically clean the OTS-modified glass substrate using n-hexane, chloroform, and isopropanol in sequence to remove residual impurities on the surface, and the glass substrate is ready for use;

[0016] S2.4: Take a clean bottom electrode substrate as a single crystal growth substrate, take a certain volume of the saturated precursor solution and drop it on the surface of the hydrophobic treated glass substrate in S2.3, and fit it tightly with the bottom electrode substrate to form a sandwich structure, so that the liquid film in the confined space is evenly spread; clamp the two substrates with a clamp, place them in an oven, adjust the growth temperature, adjust the growth time, and let it grow statically to obtain a monolithic integrated Bi-based organic-inorganic hybrid perovskite single crystal film.

[0017] Preferably, in said S1.1, the volume ratio of NMN dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) is in the range of: (1-10): (0.1-5).

[0018] Preferably, in S1.2, the halogenated organic salt is selected from: methylamine hydroiodide (MAI) or formamidine hydroiodide (FAI); the halogenated metal salt is selected from: cesium iodide (CsI) and bismuth iodide (BiI3);

[0019] A3Bi 22 In the X9 structural formula, the A position is replaced by a halogenated organic salt and a low-valent halogenated metal salt, and the stoichiometric molar ratio of the two is: the sum is equal to 3.

[0020] Preferably, in S1.2, the precursor solution is placed on a hot plate and heated at a temperature ranging from 25°C to 80°C.

[0021] Preferably, in S1.4, the volume ratio of n-hexane to octadecyltrichlorosilane (OTS) is in the range of (1000-100):(1-0.2).

[0022] Preferably, the substrate required in S2.2 is: ITO or FTO; the size range of the substrate is: 5mm-500mm.

[0023] Preferably, in S2.4, the growth temperature control range is: 30°C-100°C; the growth time range is: 6h-120h.

[0024] Compared with the prior art, the advantages of the present invention are:

[0025] 1. The present invention adopts the spatial confinement method to grow single crystal thin films, which is independent of specific substrates and strict lattice matching, which will be conducive to the monolithic integration of lead-free halide perovskite single crystal thin films and required substrates. Monolithic integration can not only simplify the device structure, but also expand new optoelectronic applications by utilizing complementary characteristics. This will help reduce costs and provide the possibility for the preparation of large-area single crystal thin film-based photodetectors.

[0026] 2. Bi-based organic-inorganic hybrid perovskite single crystal film is integrated on the ITO substrate as the photoelectric functional layer, and Au is used as the top electrode. The photodetector device can exhibit a wide spectral detection range at 0V bias, achieve specific dual-wavelength photoelectric response, and excellent detection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an atomic force microscope image (AFM image) of the MCBI perovskite single crystal film prepared in Example 1.

[0028] Figure 2 This is a microscope image of the Au / MCBI / ITO photoelectric detection device constructed in Example 1, in which the regular square is the top electrode Au electrode.

[0029] Figure 3 This is the photoelectric performance of the Au / MCBI / ITO photodetector with a wide spectrum as described in Example 1: It curve.

[0030] Figure 4 This is the photoelectric performance of the Au / MCBI / ITO photodetector with a wide spectrum as described in Example 1: response and detection rate curve. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be further described below.

[0032] The present invention provides a method for preparing a Bi-based organic-inorganic perovskite single crystal thin film photodetector, which specifically comprises the following steps:

[0033] The drugs required for the experiment are as follows:

[0034] Methyl hydroiodide (MAI, analytical grade), cesium iodide (CsI, analytical grade), bismuth iodide (BiI3, analytical grade), N-N-dimethylformamide (analytical grade), dimethyl sulfoxide (analytical grade), isopropanol (analytical grade), n-hexane (analytical grade), octadecyltrichlorosilane (OTS) (analytical grade), and acetone (analytical grade) were purchased from Aladdin Reagent Company; ethanol (analytical grade) was purchased from China National Pharmaceutical Group Shanghai Reagent Company, and deionized water.

[0035] Step 1: Preparation of MA by spatial confinement method x Cs y Bi2I9 single crystal thin film:

[0036] (1) NMN dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) are mixed in a volume ratio of 4:1 to a total volume of 1 mL to obtain a uniform and transparent mixed solvent;

[0037] (2) With A3B2X9 as the basic structural formula, methyl hydroiodide (MAI) and cesium iodide (CsI) are added according to the stoichiometric molar ratio of x:y=2:1; then bismuth iodide (BiI3) is added to the mixed solvent of step (1) according to the stoichiometric molar ratio, the mixture is placed on a hot plate and heated at 50°C, and stirred continuously until all dissolved, and then a saturated precursor solution is obtained, and the precipitate is filtered out using a 0.22 μm PTFE organic phase filter head to obtain a clear saturated precursor solution;

[0038] (3) n-hexane and octadecyltrichlorosilane (OTS) were mixed in a volume ratio of 500:1 and stirred continuously at room temperature to form a uniform transparent solution, which was used as a solvent for the subsequent hydrophobic treatment of the glass substrate;

[0039] (4) Cutting the ITO substrate and the glass substrate into a size of 120 mm x 120 mm for single crystal thin film integration, and then ultrasonically cleaning the cut substrates in acetone, deionized water, and ethanol in turn, and then drying them with nitrogen for later use;

[0040] (5) Immerse the cleaned glass substrate in the OTS n-hexane solvent of step (4) and perform hydrophobic treatment for 24 hours. Then, ultrasonically clean the OTS-modified glass substrate using n-hexane, chloroform, and isopropanol in sequence, wipe the surface with dust-free paper to remove residual impurities, and purge with nitrogen for later use.

[0041] (6) Then, a clean ITO substrate was taken as a single crystal growth substrate, and a certain volume of the saturated precursor solution was dripped onto the surface of the glass substrate treated with hydrophobicity in step (5), and the glass substrate was laminated with the ITO substrate to form a sandwich structure, so that the liquid film in the confined space was evenly spread. The two substrates were clamped with two clamps and placed in an oven. The solvent evaporation rate was adjusted, the growth temperature was set to 70°C, and the growth time was 48h to obtain a Bi-based organic-inorganic perovskite single crystal film (MA) integrated on the ITO substrate. x Cs y Bi2I9).

[0042] The Bi-based organic-inorganic perovskite single crystal film prepared in this embodiment is as follows Figure 1 As shown in the atomic force microscope image (AFM image), it can be clearly observed that the single crystal film is composed of a crystalline phase with grains of about 700 nm and a crystalline phase with grains of about 150 nm.

[0043] Step 2: Preparation of thin film photodetectors

[0044] MA prepared in step 1 x Cs y Bi2I9 single crystal thin film (MCBI) is used to construct detectors with wide spectrum and specific dual-band photoelectric response. Figure 2 As shown in the figure, Au is used as the electrode material, and an array structure mask is added to the surface of the MCBI single crystal film. Through vacuum thermal deposition technology, an Au top electrode array is formed on the surface of the MCBI single crystal film. Subsequently, the Au / MCBI / ITO photodetector uses the Keithley 4200 semiconductor needle system to measure the It curve and other data of the sample to characterize the photoelectric characteristics of the detector. Figure 3 As shown in the figure, the Au / MCBI / ITO device can have a photoelectric response to the spectral range of 400nm-600nm under 0V bias, and the photocurrent first increases and then decreases with the increase of the wavelength of the incident light, and then increases at 540nm. It is worth noting that compared with the response to other light bands, the photodetector has a stronger photocurrent response to the 460nm and 540nm bands. Figure 4 The responsivity and detectivity curves of the Au / MCBI / ITO device at 0V bias are shown, which are consistent with the It curve trend. The responsivity at 460nm and 540nm can reach ~4.5x10 -4 AW -1 and ~1.1x10 -4 AW -1 This indicates that the Au / MCBI / ITO photodetector exhibits self-powered characteristics and specific dual-band photoelectric response, which will provide possibilities for optical communication design.

[0045] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A Bi-based organic-inorganic perovskite single crystal thin film photodetector, characterized in that: Au is used as the electrode material, an array structure mask is added to the surface of the Bi-based organic-inorganic perovskite single crystal film, and an Au top electrode array is formed on the surface of the Bi-based organic-inorganic perovskite single crystal film through vacuum thermal precipitation technology.

2. The Bi-based organic-inorganic perovskite single crystal thin film photodetector according to claim 1, characterized in that: The preparation method of the Bi-based organic-inorganic perovskite single crystal film is as follows: S1: Preparation of stable perovskite precursor solution S1.1: Mix two solvents, N-N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), in a certain volume ratio to obtain a uniform and transparent mixed solvent; S1.2: Taking A3Bi2X9 as the basic structural formula of perovskite, weigh the precursors of the halogenated organic salt and the halogenated metal salt according to the stoichiometric molar ratio, add them to the above mixed solvent, heat the mixture on a hot plate and stir continuously to obtain a saturated solution of the precursor; S1.3: The above-mentioned precursor saturated solution is filtered out by using a 0.22 μm PTFE organic phase filter to remove the precipitate to obtain a clarified precursor saturated solution; S2: Monolithic integration of Bi-based organic and inorganic perovskite single crystal films S2.1: n-hexane and octadecyltrichlorosilane (OTS) are mixed in a certain volume ratio to form a uniform transparent solution, which is used as a solvent for the subsequent hydrophobic treatment of the glass substrate; S2.2: Cut the required substrate into a certain size for single crystal thin film integration, and then clean the substrate in acetone, deionized water, and ethanol in sequence by ultrasonic cleaning, and blow dry with nitrogen for later use; S2.3: Immerse the cleaned glass substrate in the hydrophobic solvent of S2.1 to perform hydrophobic treatment; then, ultrasonically clean the OTS-modified glass substrate using n-hexane, chloroform, and isopropanol in sequence to remove residual impurities on the surface, and the glass substrate is ready for use; S2.4: Take a clean bottom electrode substrate as a single crystal growth substrate, take a certain volume of the saturated precursor solution and drop it on the surface of the hydrophobic treated glass substrate in S2.3, and fit it tightly with the bottom electrode substrate to form a sandwich structure, so that the liquid film in the confined space is evenly spread; clamp the two substrates with a clamp, place them in an oven, adjust the growth temperature, adjust the growth time, and let it grow statically to obtain a monolithic integrated Bi-based organic-inorganic hybrid perovskite single crystal film.

3. The Bi-based organic-inorganic perovskite single crystal thin film photodetector according to claim 2, characterized in that: In the S1.1, the volume ratio of NMN dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) is in the range of (1-10): (0.1-5).

4. The Bi-based organic-inorganic perovskite single crystal thin film photodetector according to claim 2, characterized in that: In S1.2, the halogenated organic salt is selected from methylamine hydroiodide (MAI) or formamidine hydroiodide (FAI); the halogenated metal salt is selected from cesium iodide (CsI) and bismuth iodide (BiI3); A3Bi 22 In the X9 structural formula, the A position is replaced by a halogenated organic salt and a low-valent halogenated metal salt, and the stoichiometric molar ratio of the two is: the sum is equal to 3.

5. The Bi-based organic-inorganic perovskite single crystal thin film photodetector according to claim 2, characterized in that: In S1.2, the precursor solution is placed on a hot plate and heated in the temperature range of 25°C-80°C.

6. The Bi-based organic-inorganic perovskite single crystal thin film photodetector according to claim 2, characterized in that: In S1.4, the volume ratio range of n-hexane to octadecyltrichlorosilane (OTS) is: (1000-100): (1-0.2).

7. The Bi-based organic-inorganic perovskite single crystal thin film photodetector according to claim 2, characterized in that: The substrate required in S2.2 is: ITO or FTO; the size range of the substrate is: 5mm-500mm.

8. The Bi-based organic-inorganic perovskite single crystal thin film photodetector according to claim 2, characterized in that: In S2.4, the growth temperature control range is: 30℃-100℃; the growth time range is: 6h-120h.

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