Perovskite heterojunction self-polarization effect-based polarization detector and preparation method thereof

Abstract

The invention provides a polarization detector based on a perovskite heterojunction self-polarization effect and a preparation method of the polarization detector, and particularly relates to an innovative device for realizing efficient photon-generated carrier separation and polarization detection by using a perovskite heterojunction structure. According to the detector, a controllable built-in electric field is formed at an interface by constructing a perovskite heterojunction and utilizing the energy band alignment difference between different perovskite materials. The formation of the built-in electric field generates stable charge asymmetric distribution in an interface region along with the heterostructure, so that a remarkable self-polarization effect is generated. The intensity and the direction of the built-in electric field are accurately regulated and controlled, so that high-sensitivity detection of the polarization characteristic of incident light is realized; meanwhile, the built-in electric field also significantly promotes the separation of photo-induced electrons and holes, and the overall performance of the detector is effectively improved. The detector can be widely applied to the fields of optical sensing, polarization imaging, quantum communication and the like, and has important scientific value and market prospect.

Description

Technical Field

[0001] The present invention relates to the fields of metal halide perovskite materials and optoelectronic devices, and particularly relates to a polarization detector based on the self-polarization effect of a perovskite heterojunction and a preparation method thereof. Background Art

[0002] Polarized photodetection, as an important branch in the field of optoelectronics, has key application values in frontier fields such as quantum information processing, biomedical imaging, and atmospheric remote sensing monitoring. Traditional polarization detectors mainly rely on the physical cascading of optically anisotropic materials (such as wire grid polarizers) and optoelectronic detection devices. This discrete structure has inherent defects such as large optical path coupling loss and low system integration. In recent years, although monolithic polarization detectors based on the intrinsic anisotropy of two-dimensional materials (such as black phosphorus, ReS 2 ) have made certain progress, their polarization sensitivities are generally low, and they are limited by narrowband response and low carrier mobility.

[0003] Metal halide perovskite materials, due to their excellent light absorption coefficient (~10 5 cm -1 ), high carrier mobility (>100 cm 2 / V·s), and tunable bandgap characteristics, provide a revolutionary material platform for the development of a new generation of optoelectronic detectors. However, existing perovskite-based polarization detectors mostly adopt a traditional architecture with an external polarizer separated from the optoelectronic detection unit, resulting in a reduction of more than 40% in the utilization rate of incident light energy. A few studies have attempted to construct anisotropic microstructures through nanoimprinting, but such methods face technical bottlenecks such as high process complexity and poor device stability.

[0004] More critically, the existing technology system has not effectively solved the performance coupling contradiction between the photogenerated carrier separation efficiency and the polarization response sensitivity. Although layered perovskites with intrinsic anisotropy exhibit a certain polarization response, their interlayer carrier transport barrier (>0.5 eV) severely restricts the quantum efficiency (<30%). Therefore, how to achieve a synergistic improvement in polarization sensitivity and optoelectronic conversion efficiency in a single perovskite device through material system innovation and device structure design has become a scientific problem that urgently needs to be broken through in this field. Summary of the Invention

[0005] Technical Problem: To solve the above problems existing in the prior art, the present invention provides a polarization detector based on the self-polarization effect of a perovskite heterojunction and a preparation method thereof. The polarization detector based on the self-polarization effect of a perovskite heterojunction has high sensitivity, can achieve precise detection of weak polarization signals, and breaks through the narrowband limitation of traditional two-dimensional material polarization detectors.

[0006] Technical Solution: The polarization detector based on the self-polarization effect of a perovskite heterojunction of the present invention includes:

[0007] The first layered heterojunction and the second layered heterojunction composed of at least two different perovskite materials, and a controllable built-in electric field is formed at the heterojunction interface, and a self-polarization effect is generated through the difference in band alignment;

[0008] The first electrode and the second electrode symmetrically coated on the upper and lower surfaces of the first layered heterojunction and the second layered heterojunction, and the extending directions of the first electrode and the second electrode are parallel to the heterojunction interface;

[0009] The incident light is vertically incident laterally along the layered structure of the heterojunction, and the polarization direction forms an angle with the extending direction of the heterojunction interface, and the carrier separation path is regulated through the self-polarization effect to achieve polarization-sensitive detection.

[0010] The first layered heterojunction and the second layered heterojunction are stacked by different types or ion-doped lead halide perovskite materials, and the chemical general formula of at least one layer of the materials is ABX 3 , where A is methylammonium ion / formamidinium ion / cesium ion, B is lead / tin, and X is halogen.

[0011] The band alignment of the first layered heterojunction and the second layered heterojunction is of Type-II structure, the conduction band offset range at the interface is 0.2 - 1.0 eV, and the valence band offset range is 0.3 - 1.2 eV.

[0012] The wavelength range of the incident light is 200 - 1000 nm; the incident light is incident laterally along the layered structure of the heterojunction, and the polarization direction forms an angle of 0° - 360° with the interface extending direction; when the polarization electric field component is parallel to the self-polarization direction, the photo-generated electron-hole pairs are efficiently separated along the direction perpendicular to the interface under the drive of the built-in electric field; when the polarization direction is perpendicular to the self-polarization direction, the carrier separation path is inhibited, thereby generating a significant polarization-dependent photocurrent difference; the polarization direction forms an angle with the extending direction of the heterojunction interface, and the carrier separation path is regulated through the self-polarization effect to achieve polarization-sensitive detection.

[0013] The preparation method of the polarization detector based on the self-polarization effect of the perovskite heterojunction of the present invention includes the following steps:

[0014] Step 1, deposit a first perovskite layer and a second perovskite layer on the substrate in sequence to form the first layered heterojunction and the second layered heterojunction;

[0015] Step 2, use an ion beam etching process to vertically cut the side of the heterojunction to obtain a smooth incident end face with a roughness < 5 nm;

[0016] Step 3: Using an electron beam evaporation process, deposit the first electrode and the second electrode on both sides of the heterojunction in a vacuum through a mask plate, and control the electrode spacing and orientation; the electrode extension direction is parallel to the heterojunction interface to ensure that the carrier directional collection efficiency > 90%.

[0017] The first layered heterojunction and the second layered heterojunction are prepared by one or more of solution epitaxy, spraying, spin coating, and chemical vapor deposition, and the thickness of each layer is 10 μm - 500 μm.

[0018] When preparing the perovskite heterojunction by solution epitaxy, spraying, spin coating, or chemical vapor deposition, at least two different perovskite materials (such as organic-inorganic hybrid perovskite and all-inorganic perovskite) are used to construct a layered heterojunction, and through precise design of the chemical composition and energy band structure, a Type-II energy band alignment is formed; the conduction band offset at the interface is 0.2 - 1.0 eV, and the valence band offset is 0.3 - 1.2 eV, inducing a strong built-in electric field of 10 4 -10 5 V / cm, and triggering a stable self-polarization effect.

[0019] The self-polarization effect is realized through the asymmetric distribution of interface charges, and its polarization direction is perpendicular to the extension direction of the heterojunction interface, providing an intrinsic anisotropic response basis for polarization-sensitive detection.

[0020] The preparation process of the first electrode and the second electrode is at least one of an electron beam evaporation process or a magnetron sputtering process. The materials of the first electrode (3) and the second electrode (4) include at least one of gold, silver, platinum, titanium, aluminum, copper, ITO, and IZO. The coating thickness is 10 - 200 nm, and the electrode spacing is 10 - 500 μm.

[0021] Use an ion beam etching process to vertically cut the side of the heterojunction to obtain a smooth incident end face with a surface roughness < 5 nm, effectively reducing the light scattering loss, with a scattering rate < 2%, and improving the incident light coupling efficiency.

[0022] Beneficial effects: A polarization detector based on the self-polarization effect of perovskite heterojunction and its preparation method of the present invention have the following advantages

[0023] (1) High sensitivity, enabling precise detection of weak polarization signals;

[0024] (2) Through the regulation of the heterojunction material components, the response band covers 200 - 1000 nm, breaking through the narrow band limitation of traditional two-dimensional material polarization detectors;

[0025] (3) Ultra-fast response speed, meeting the real-time analysis requirements of high-speed optical communication and quantum key distribution;

[0026] (4) Abandon the physical cascade of the external polarizer and the detection unit, with the light energy utilization rate increased by more than 60%, and it is compatible with the integration of miniaturized optical systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a device structure diagram of the polarization detector of the present invention; among them: the first layered heterojunction 1, the second layered heterojunction 2, the first electrode 3, the second electrode 4, and the incident light 5;

[0028] Figure 2 It is the angular resolved photocurrent of the polarization detector in Example 1 of the present invention in rectangular coordinates (a) and polar coordinates (b) under the incidence of 540 nm polarized light. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0030] To make the substantial features and the practicality of the present invention more easily understood, the technical solutions of the present invention will be further described in detail below in conjunction with the accompanying drawings and several specific embodiments. However, the following description and explanation of the embodiments do not constitute any limitation to the protection scope of the present invention. Any equivalent transformation or substitution in function, method, or structure made by those of ordinary skill in the art according to these embodiments shall fall within the protection scope of the present invention:

[0031] The technical problem to be solved by the present invention is achieved through a method for preparing a polarization detector based on the self-polarization effect of a perovskite heterojunction.

[0032] Step 1: Deposit the first perovskite layer and the second perovskite layer on the substrate in sequence to form the first layered heterojunction 1 and the second layered heterojunction 2;

[0033] Step 2: Use the ion beam etching process to vertically cut the side of the heterojunction to obtain a smooth incident end face with a roughness < 5 nm;

[0034] Step 3: Use the electron beam evaporation process to vacuum deposit the first electrode 3 and the second electrode 4 on both sides of the heterojunction through a mask plate, and control the electrode spacing and orientation; the electrode extension direction is parallel to the heterojunction interface to ensure that the carrier directional collection efficiency > 90%.

[0035] S1: Prepare the perovskite heterojunction by solution method, spin coating method or chemical vapor deposition. Construct a layered heterojunction using at least two different perovskite materials (such as organic-inorganic hybrid perovskite and all-inorganic perovskite). Through precise design of chemical composition and energy band structure, form a Type-II energy band alignment. The conduction band offset at the interface is 0.2 - 1.0 eV, and the valence band offset is 0.3 - 1.2 eV, inducing a strong built-in electric field (10 4 -10 5 V / cm), and triggering a stable self-polarization effect. The self-polarization effect is achieved through the asymmetric distribution of interface charges, and its polarization direction is perpendicular to the extension direction of the heterojunction interface, providing an intrinsic anisotropic response basis for polarization-sensitive detection.

[0036] S2: Use the ion beam etching process to vertically cut the side of the heterojunction to obtain a smooth incident end face with a surface roughness < 5 nm, effectively reducing the light scattering loss (scattering rate < 2%), and improving the incident light coupling efficiency.

[0037] S3: Symmetrically evaporate gold, silver or ITO electrodes on both sides of the heterojunction through a mask. The extension direction of the electrodes is parallel to the heterojunction interface, the coating thickness is 10 - 200 nm, and the electrode spacing is 10 - 500 μm, ensuring that the carrier directional collection efficiency > 90%.

[0038] The second aspect of the present invention provides a polarization detector based on the self-polarization effect of perovskite heterojunction, which is prepared by the preparation method provided in the first aspect of the present invention. The polarization detector includes:

[0039] The first layered heterojunction 1 and the second layered heterojunction 2 composed of at least two different perovskite materials. A controllable built-in electric field is formed at the heterojunction interface, and a self-polarization effect is generated through the energy band alignment difference;

[0040] The first electrode 3 and the second electrode 4 symmetrically plated on the upper and lower surfaces of the first layered heterojunction 1 and the second layered heterojunction 2. The extension directions of the first electrode 3 and the second electrode 4 are parallel to the heterojunction interface;

[0041] The incident light 6 is incident vertically from the side of the heterojunction layered structure, and its polarization direction forms an angle with the extension direction of the heterojunction interface. The carrier separation path is regulated through the self-polarization effect to achieve polarization-sensitive detection.

[0042] The first layered heterojunction 1 and the second layered heterojunction 2 are stacked and composed of different types or ion-doped lead halide perovskite materials. The chemical general formula of at least one layer of the materials is ABX 3 , where A is methylammonium ion / formamidinium ion / cesium ion, B is lead / tin, and X is halogen.

[0043] The energy band alignment of the first layer heterojunction 1 and the second layer heterojunction 2 is of Type-II structure, and the conduction band offset range at the interface is 0.2 - 1.0 eV, and the valence band offset range is 0.3 - 1.2 eV.

[0044] The incident light 5 is incident laterally along the heterojunction layered structure, and the polarization direction forms an angle of 0° - 360° with the interface extension direction. When the polarization electric field component is parallel to the self-polarization direction, the photo-generated electron-hole pairs are efficiently separated along the direction perpendicular to the interface under the drive of the built-in electric field; when the polarization direction is perpendicular to the self-polarization direction, the carrier separation path is inhibited, resulting in a significant polarization-dependent photocurrent difference. Its polarization direction forms an angle with the heterojunction interface extension direction, and the carrier separation path is regulated through the self-polarization effect to achieve polarization-sensitive detection.

[0045] Example 1

[0046] MAPbCl 3 / MAPbBr 3 Preparation of the heterojunction polarization detector:

[0047] (1) Dissolve lead chloride and methylammonium chloride in a mixed solution of N,N-dimethylformamide / dimethyl sulfoxide (VDMF:VDMSO = 1; 1), stir in a beaker until completely dissolved, and the stirring rate is 800 rpm. Filter the solution using a 22 μm organic filter head to form a clear and transparent MAPbCl 3 precursor solution, and the molar ratio of lead chloride to methylammonium chloride is 1:1. The concentration of Pb 2+ is 1 M;

[0048] (2) Dissolve lead bromide and methylammonium bromide in N,N-dimethylformamide, stir in a beaker until completely dissolved, and the stirring rate is 800 rpm. Filter the solution using a 22 μm organic filter head to form a clear and transparent MAPbBr 3 precursor solution, and the molar ratio of lead bromide to methylammonium bromide is 1:1. The concentration of Pb 2+ is 1 M;

[0049] (3) Place the MAPbCl 3 precursor solution prepared in step 1 on a heating table, raise the temperature from 40 °C to 70 °C at a rate of 0.5 °C / hour to grow high-quality MAPbCl 3 single crystal. Place the MAPbCl 3 single crystal in a vacuum dryer at 60 °C for 12 hours and then take it out.

[0050] (4) The MAPbBr prepared in step (1) 3The precursor solution is placed on a stirring and heating table, and the temperature is set to 60 °C. The MAPbCl obtained in (2) 3 single crystal substrate is put into it for epitaxial growth at a growth rate of 5 μm / min to obtain MAPbCl 3 / MAPbBr 3 heterojunction; The above heterojunction is placed in a vacuum dryer at 60 °C and dried for 12 hours and then taken out.

[0051] (5) Use a polishing machine to thin and polish the upper and lower surfaces of the MAPbCl 3 / MAPbBr 3 heterojunction. Finally, the thickness of the MAPbCl 3 / MAPbBr 3 heterojunction is 200 μm, and a surface roughness <5 nm is obtained.

[0052] (6) Use the ion beam etching process to vertically cut the side of the heterojunction to obtain a smooth incident end face with a surface roughness <5 nm, effectively reducing the light scattering loss (scattering rate <2%), and improving the incident light coupling efficiency.

[0053] (7) Symmetrically evaporate gold electrodes on the upper and lower surfaces of the heterojunction through a mask plate. The electrode extension direction is parallel to the heterojunction interface, the coating thickness is 30 nm, and the electrode spacing is 200 μm. Finally, a MAPbCl 3 / MAPbBr 3 heterojunction polarization detector is obtained.

[0054] The incident light (5) is incident laterally along the layered structure of the heterojunction, and its polarization direction forms an angle of 0° - 360° with the interface extension direction. Under the irradiation of 525 nm polarized light, the photoexcited electron-hole pairs will be quickly separated by the directional built-in electric field, generating a highly polarization-sensitive optical response.

[0055] Example 2

[0056] MAPbBr 3 / MAPbI 3 Preparation of heterojunction polarization detector:

[0057] (1) Dissolve lead bromide and methylammonium bromide in N,N-dimethylformamide, stir in a beaker until completely dissolved, and the stirring rate is 800 rpm. Filter the solution with a 22 μm organic filter head to form a clear and transparent MAPbBr 3 precursor solution, and the molar ratio of lead bromide to methylammonium bromide is 1:1. The Pb 2+ concentration is 1 M;

[0058] (2) Dissolve lead iodide and methylammonium iodide in γ-butyrolactone, and stir in a beaker until completely dissolved. The stirring rate is 800 rpm. Filter the solution using a 22 μm organic filter head to form a clear and transparent MAPbI 3 precursor solution, and the molar ratio of lead iodide to methylammonium iodide is 1:1. The concentration of Pb 2+ is 1 M;

[0059] (3) Place the MAPbBr 3 precursor solution prepared in step 1 on a heating stage, and raise the temperature from 40 °C to 70 °C at a rate of 0.5 °C / hour to grow high-quality MAPbBr 3 single crystal. Place the MAPbBr 3 single crystal in a vacuum dryer at 60 °C and dry it for 12 hours before taking it out.

[0060] (4) Place the MAPbBr 3 precursor solution prepared in step (2) on a stirring and heating stage, set the temperature to 110 °C, and put the MAPbBr 3 single crystal substrate obtained in step (3) into it for epitaxial growth. The growth rate is 10 μm / min to obtain MAPbBr 3 / MAPbI 3 heterojunction; Place the above heterojunction in a vacuum dryer at 60 °C and dry it for 12 hours before taking it out.

[0061] (5) Use a polishing machine to thin and polish the surface of the MAPbCl 3 / MAPbBr 3 heterojunction. Finally, the thickness of the MAPbCl 3 / MAPbI 3 heterojunction is 200 μm, and the surface roughness < 5 nm is obtained.

[0062] (6) Use an ion beam etching process to vertically cut the side of the heterojunction to obtain a smooth incident end face with a surface roughness < 5 nm, effectively reducing the light scattering loss (scattering rate < 2%), and improving the incident light coupling efficiency.

[0063] (7) Symmetrically evaporate the first electrode 3 and the second electrode 4 on both sides of the heterojunction through a mask. The extending direction of the electrodes is parallel to the heterojunction interface. The coating thickness is 30 nm, and the electrode spacing is 200 μm. Finally, a MAPbBr 3 / MAPbI 3 heterojunction polarization detector is obtained.

[0064] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A polarization detector based on the self-polarization effect of a perovskite heterojunction, characterized in that: The polarization detector includes: A first layered heterojunction (1) and a second layered heterojunction (2) composed of at least two different perovskite materials, wherein a controllable built-in electric field is formed at the interface of the heterojunction, and a self-polarization effect is generated through the difference in energy band alignment; A first electrode (3) and a second electrode (4) symmetrically plated on the upper and lower surfaces of the first layered heterojunction (1) and the second layered heterojunction (2), wherein the extension direction of the first electrode (3) and the second electrode (4) is parallel to the heterojunction interface; The incident light (5) is incident vertically along the side of the heterojunction layered structure, and its polarization direction forms an angle with the extension direction of the heterojunction interface. The carrier separation path is regulated by the self-polarization effect to achieve polarization-sensitive detection.

2. The polarization detector based on the self-polarization effect of the perovskite heterojunction according to claim 1, characterized in that: The first layered heterojunction (1) and the second layered heterojunction (2) are formed by stacking different types or ion-doped lead halide perovskite materials, wherein at least one layer of material has a general chemical formula of ABX3, wherein A is methylamine ion / formamidine ion / cesium ion, B is lead / tin, and X is a halogen.

3. The polarization detector based on the self-polarization effect of the perovskite heterojunction according to claim 1, characterized in that: The energy band alignment of the first layered heterojunction (1) and the second layered heterojunction (2) is a Type-II structure, the conduction band offset at the interface is in the range of 0.2-1.0 eV, and the valence band offset is in the range of 0.3-1.2 eV.

4. The polarization detector based on the self-polarization effect of the perovskite heterojunction according to claim 1, characterized in that: The wavelength range of the incident light (5) is 200-1000nm; the incident light (5) is incident laterally along the heterojunction layered structure, and its polarization direction forms an angle of 0°-360° with the interface extension direction; when the polarized light electric field component is parallel to the self-polarization direction, the photogenerated electron-hole pairs are efficiently separated along the perpendicular interface direction under the drive of the built-in electric field; when the polarization direction is perpendicular to the self-polarization direction, the carrier separation path is suppressed, thereby generating a significant polarization-dependent photocurrent difference; its polarization direction forms an angle with the heterojunction interface extension direction, and the carrier separation path is regulated by the self-polarization effect to achieve polarization-sensitive detection.

5. A method for preparing a polarization detector based on the self-polarization effect of a perovskite heterojunction according to any one of claims 1 to 4, characterized in that The following steps are involved: Step 1, depositing a first perovskite layer and a second perovskite layer on a substrate in sequence to form a first layered heterojunction (1) and a second layered heterojunction (2); Step 2, vertically cutting the side of the heterojunction by ion beam etching process to obtain a smooth incident end face with a roughness of less than 5 nm; Step 3, using an electron beam evaporation process to vacuum evaporate the first electrode (3) and the second electrode (4) on both sides of the heterojunction through a mask, controlling the electrode spacing and orientation; the electrode extension direction is parallel to the heterojunction interface to ensure that the carrier directional collection efficiency is greater than 90%.

6. The method for preparing a polarization detector based on the self-polarization effect of a perovskite heterojunction according to claim 5, characterized in that: The first layered heterojunction (1) and the second layered heterojunction (2) are prepared by one or more of solution epitaxy, spraying, spin coating, and chemical vapor deposition, and the thickness of each layer is 10 μm-500 μm.

7. The method for preparing a polarization detector based on the self-polarization effect of a perovskite heterojunction according to claim 6, characterized in that: The method adopts solution epitaxy, spraying, spin coating, and chemical vapor deposition to prepare perovskite heterojunctions, uses at least two different perovskite materials to construct layered heterojunctions, and forms Type-II energy band alignment through precise design of chemical composition and energy band structure; the conduction band offset at the interface is 0.2-1.0eV, and the valence band offset is 0.3-1.2eV, inducing a strong built-in electric field of 10 4 -10 5 V / cm and induces a stable self-polarization effect.

8. The method for preparing a polarization detector based on the self-polarization effect of a perovskite heterojunction according to claim 7, characterized in that: The self-polarization effect is achieved through asymmetric distribution of interface charges, and its polarization direction is perpendicular to the extension direction of the heterojunction interface, providing an intrinsic anisotropic response basis for polarization-sensitive detection.

9. The method for preparing a polarization detector based on the self-polarization effect of a perovskite heterojunction according to claim 5, characterized in that: The preparation process of the first electrode (3) and the second electrode (4) is at least one of an electron beam evaporation process or a magnetron sputtering process, and the material of the first electrode (3) and the second electrode (4) includes at least one of gold, silver, platinum, titanium, aluminum, copper, ITO, and IZO, and the coating thickness is 10-200nm, and the electrode spacing is 10-500μm.

10. The method for preparing a polarization detector based on the self-polarization effect of a perovskite heterojunction according to claim 5, characterized in that: The ion beam etching process is used to vertically cut the side of the heterojunction to obtain a smooth incident end face with a surface roughness of less than 5nm, which effectively reduces light scattering loss, the scattering rate is less than 2%, and improves the incident light coupling efficiency.

Images