Method for improving circularly polarized light detection performance of perovskite film through achiral cations

Abstract

The invention belongs to the field of semiconductor optoelectronic devices, and particularly relates to a method for improving circularly polarized light detection performance of a perovskite film through achiral cations. The invention provides an achiral-chiral dication strategy to improve intermolecular force and plane out-of-plane octahedron inclination in chiral perovskite, and the absorption anisotropy factor of the obtained chiral two-dimensional perovskite film is increased by more than 7 times. Based on this, a vertically structured circularly polarized photoelectric detector containing a hole transport layer and an electron transport layer is prepared. The photocurrent anisotropy factor of the circularly polarized photoelectric detector under a self-powered condition reaches 0.72, which is higher than that of a currently reported chiral two-dimensional perovskite-based self-powered circularly polarized photoelectric detector. The device realizes the balance of high absorption anisotropy and high photocurrent anisotropy, and has a wide application prospect in the fields of information encryption and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor photoelectric detectors, and in particular relates to a perovskite thin film circularly polarized light detector and a preparation method thereof. Background Art

[0002] Most traditional photodetectors can only detect conventional optical parameters such as light intensity and wavelength, and lack effective resolution and detection capabilities when faced with light with a specific polarization state. In actual application scenarios, the information carried by circularly polarized light is often of great significance. For example, in the field of optical communications, in order to achieve higher channel capacity and stronger data transmission security, solutions based on polarization multiplexing technology are often used. However, to accurately decode information encoded based on circularly polarized light, high-performance circularly polarized photodetectors are required to accurately distinguish circularly polarized light signals of different rotation directions. On the one hand, existing circularly polarized photodetectors have the problem of insufficient detection sensitivity for circularly polarized light, which makes it difficult to accurately capture weak circularly polarized light signals; on the other hand, the preparation process of some detectors is complex and costly, which limits their practical application.

[0003] Chiral two-dimensional perovskites are ideal materials for high-performance circularly polarized photodetectors due to the flexible tunability of their organic and inorganic components. The inorganic skeleton of perovskites has excellent optoelectronic properties, such as tunable band gap, high carrier mobility, high absorption coefficient, etc., while chiral cations can introduce unique chiral behaviors, including circular dichroism, nonlinear optical response, and ferroelectricity. Chirality is usually transferred from chiral organic cations to the inorganic skeleton of perovskites, resulting in chiral two-dimensional perovskites that combine the advantages of chiral materials and two-dimensional layered perovskites. Therefore, it can effectively solve the key problem of integrating high circularly polarized light absorption with efficient charge transport in circularly polarized photodetectors. However, due to the rigidity of inorganic octahedral units, it is difficult to achieve a balance between charge transport performance and chiral selectivity in chiral perovskites. Recent studies have explored various strategies aimed at improving the performance of chiral perovskites, including designing new chiral organic cations, introducing additional dopants, or constructing heterostructures. Among them, a promising approach is the mixed cation strategy, which can construct chiral two-dimensional perovskites with alternating interlayer cations to enhance the chirality of the material and optimize the stability. However, the circularly polarized light absorption and circularly polarized light detection performance of current chiral perovskite circular polarization detectors need to be further improved. Summary of the invention

[0004] The object of the present invention is to provide a method for improving the circularly polarized light detection performance of a perovskite film by using non-chiral cations, including providing a chiral perovskite circularly polarized photodetector containing non-chiral cations and a preparation method thereof.

[0005] The preparation method of the perovskite circularly polarized photodetector containing non-chiral cations provided by the present invention adopts the chirality enhancement strategy of the chiral two-dimensional perovskite material, reduces the interlayer spacing of the chiral perovskite, and enhances its orientation, so as to simultaneously achieve effective chirality transfer and charge transfer, thereby improving the performance of the perovskite thin film circularly polarized photodetector, and the specific steps are:

[0006] (1) preparing a chiral perovskite precursor solution containing achiral cations: dissolving chiral organic ammonium, achiral organic ammonium and metal halide of two-dimensional perovskite in an organic solvent, performing a solvothermal reaction, washing and drying to obtain a chiral perovskite powder containing achiral cations, and subsequently dissolving the powder using an organic solvent;

[0007] (2) coating a hole transport material on the surface of a conductive substrate and forming a hole transport layer through heat treatment;

[0008] (3) coating a chiral perovskite precursor solution containing non-chiral cations on the surface of the hole transport layer, and forming a chiral perovskite light absorption layer with circular dichroism response through heat treatment;

[0009] (4) coating an electron transport material on the surface of the chiral perovskite light absorption layer and forming an electron transport layer through heat treatment;

[0010] (5) A metal electrode is deposited on the surface of the electron transport layer by vacuum evaporation to obtain a chiral perovskite circularly polarized photodetector containing non-chiral cations.

[0011] Preferably, in step (1), the molar ratio of the organic ammonium to the metal halide is (1:1) to (2:1); the organic solvent is selected from hydroiodic acid and dimethyl sulfoxide; the solvent thermal reaction temperature is 85 to 100°C, and the reaction time is 20 to 30 hours; the mass fraction of the chiral perovskite precursor solution containing achiral cations is 20 to 60 wt%.

[0012] Preferably, in step (1), the molar ratio of the chiral organic ammonium to the achiral organic ammonium is 1 / 3 to 3 / 1, the chiral organic ammonium is selected from any one of chiral ammoniums such as R- / S-phenylethylamine, (R / S)-(- / +)-1-phenylpropylamine, (R / S)-1-(3-bromophenyl)ethylamine, (R / S)-1-(2-chlorophenyl)ethylamine, (R / S)-(- / +)-N,α-dimethylbenzylamine, and R- / S-β-methylphenylethylamine, and the achiral organic ammonium is selected from any one of organic ammoniums such as phenylethylamine, n-pentylamine, n-butylamine, 3-bromopropylamine, and 2-bromoethylamine.

[0013] Preferably, in step (2), the hole transport layer material is PEDOT:PSS; the coating method is spin coating; the heat treatment temperature is 100-130° C., and the time is 15-20 minutes.

[0014] Preferably, in step (3), the solvent of the chiral perovskite precursor solution containing achiral cations is dimethyl sulfoxide; the coating method is substrate heating spin coating, the substrate heating temperature is 65-75°C, the amount of the chiral perovskite precursor solution containing achiral cations coated is 65-75 μL, the anti-solvent is added dropwise during the spin coating process, and the spin coating speed is 2000-6000 rpm; the heat treatment temperature is 80-120°C, and the time is 10-20 minutes.

[0015] Preferably, in step (4), the electron transport layer material is PCBM, and 15 to 25 mg of PCBM is dissolved in 1 mL of chlorobenzene; the coating method is spin coating, and the amount of the coated PCBM chlorobenzene solution is 40 to 50 μL; the heat treatment temperature is 45 to 65° C., and the time is 10 to 20 minutes.

[0016] Preferably, in step (5), the metal electrode is silver, gold, copper, aluminum, chromium or an alloy thereof.

[0017] The present invention also provides a chiral perovskite circular polarization photodetector containing non-chiral cations, which is obtained by the above preparation method.

[0018] The non-chiral-chiral double cation strategy provided by the present invention is used to improve the intermolecular force and out-of-plane octahedral tilt in the chiral perovskite, and the absorption anisotropy factor of the obtained chiral two-dimensional perovskite film is increased by more than 7 times, and the vertical structure circular polarization photodetector containing a hole transport layer and an electron transport layer prepared based on this has a photocurrent anisotropy factor of 0.72 under self-powered conditions, which is higher than the currently reported chiral two-dimensional perovskite-based self-powered circular polarization photodetector. The device achieves a balance between high absorption anisotropy and high photocurrent anisotropy, and has broad application prospects in fields such as information encryption.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention provides a strategy for preparing achiral-chiral dication chiral perovskite, which introduces achiral cations into chiral perovskite films, which can effectively reduce the interlayer spacing of chiral two-dimensional perovskites and improve oriented growth, thereby simultaneously enhancing the chirality and charge transport in the perovskite.

[0021] (2) The chiral perovskite circularly polarized photodetector obtained based on the chiral perovskite containing non-chiral cations has good self-powered photodetection performance, and at the same time achieves a higher circularly polarized light absorption anisotropy factor and photocurrent anisotropy factor, which solves the problem of the difficult balance between charge transfer performance and chiral selectivity in chiral perovskite, and has the potential to be applied in information encryption fields such as encrypted imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the circular dichroism spectrum of the chiral perovskite containing achiral cations provided in Example 1.

[0023] Figure 2 The crystal structure diagram of the chiral perovskite containing achiral cations provided in Example 1.

[0024] Figure 3 Absorption anisotropy factor diagram of the chiral perovskite with pure chiral cations provided in Example 1 and the chiral perovskite containing achiral cations.

[0025] Figure 4 This is a schematic diagram of the structure of a chiral perovskite circularly polarized photodetector containing achiral cations provided in Example 2.

[0026] Figure 5 Photocurrent diagram of the chiral perovskite circularly polarized photodetector containing achiral cations provided in Example 2 under irradiation of left-handed circularly polarized light and right-handed circularly polarized light.

[0027] Figure 6 A comparison chart of the circularly polarized light absorption anisotropy factor and the photocurrent anisotropy factor of the chiral perovskite circularly polarized photodetector containing non-chiral cations provided in Example 2 and the reported chiral perovskite-based circularly polarized photodetector. DETAILED DESCRIPTION

[0028] The present invention is further described below by examples in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are only used to illustrate the present invention and do not constitute a limitation to the present invention.

[0029] Example 1, Chiral perovskite film containing achiral cations (R / S-3BrMBA 0.75 PEA 0.25 )2PbI4 preparation, the specific steps are as follows:

[0030] (1) Dissolve 113.25 μL of (R / S)-1-(3-bromophenyl)ethylamine (R / S-3BrMBA), 0.0623 g of phenethylammonium iodide (PEAI), and 0.231 g of lead iodide (PbI2) in a hydroiodic acid solution;

[0031] (2) The above solution was kept at 95°C for 24 hours, cooled naturally, washed and dried to obtain (R / S-3BrMBA 0.75 PEA 0.25 )2PbI4 powder;

[0032] (3) Dissolve in (R / S-3BrMBA 0.75 PEA0.25 )2PbI4 powder was dissolved in DMSO, spin-coated and kept at 90 °C for 10 min to form a chiral perovskite film containing achiral cations.

[0033] (4) For the chiral perovskite R / S-3BrMBA2PbI4 with pure chiral cations, replace "113.25 μL of R / S-3BrMBA, 0.0623 g of PEAI" in step (1) with "151 μL of R / S-3BrMBA", and the other steps remain the same.

[0034] Figure 1 Shown is a chiral perovskite film containing achiral cations (R / S-3BrMBA 0.75 PEA 0.25 )2PbI4 circular dichroism spectrum, the mirror image signal indicates the successful preparation of chiral perovskite. Figure 2 Depicted (R-3BrMBA 0.75 PEA 0.25 )2PbI4, which crystallizes in the chiral space group P21, further confirms the chirality transfer of chiral organic amines to the perovskite structure. Figure 4 As shown, the calculation results show that R-3BrMBA2PbI4 and (R-3BrMBA 0.75 PEA 0.25 )2PbI4 has an absorption anisotropy factor of 3×10 -4 and 2.2×10 -3 The introduction of achiral cations increases the absorption anisotropy factor of chiral perovskite by 7.33 times.

[0035] Example 2, based on (R / S-3BrMBA 0.75 PEA 0.25 )2PbI4 circular polarization photodetector preparation, the specific steps are as follows:

[0036] (1) The (R / S-3BrMBA obtained by solvent thermal reaction 0.75 PEA 0.25 )2PbI4 powder was dissolved in DMSO;

[0037] (2) Spin coating PEDOT:PSS on the surface of ITO conductive glass and keeping it at 130°C for 15 minutes to form a hole transport layer;

[0038] (3) Spin coating (R / S-3BrMBA) on the surface of PEDOT:PSS layer 0.75 PEA 0.25 )2PbI4 DMSO solution was heated at 90°C for 10 minutes to form a chiral perovskite light absorption layer;

[0039] (4) In (R / S-3BrMBA 0.75 PEA 0.25 )2PbI4 layer surface spin-coated PC 71 The chlorobenzene solution of BM was kept at 50 °C for 15 min to form an electron transport layer;

[0040] (5) Depositing a silver metal electrode on the surface of the electron transport layer by vacuum evaporation to obtain a (R / S-3BrMBA 0.75 PEA 0.25 )2PbI4 circularly polarized photodetector.

[0041] Figure 4 The following is based on (R / S-3BrMBA 0.75 PEA 0.25 )2PbI4 circular polarization photodetector structure diagram. The device has obvious photocurrent differences when irradiated with left-handed circular polarization light and right-handed circular polarization light, such as Figure 5 As shown. The calculated photocurrent anisotropy factor of the device is 0.72, which is the highest value of chiral two-dimensional perovskite-based self-powered circularly polarized photodetection. In addition, Figure 6 As shown, compared with the reported chiral perovskite-based circularly polarized photodetectors, the device simultaneously achieves higher circularly polarized light absorption anisotropy factor and photocurrent anisotropy factor, indicating that the invention has a significant performance optimization effect on chiral perovskite circularly polarized photoelectric devices.

[0042] The above embodiments illustrate that the present invention is an effective method for constructing a high-performance chiral perovskite circularly polarized photodetector.

[0043] It should be noted that the above embodiments are only preferred specific implementations of the present invention and should not be construed as limiting the present invention. Any modification, equivalent substitution and improvement made by any person skilled in the art within the technical scope disclosed in the present invention should be included in the protection scope of the invention.

Claims

1. A method for preparing a chiral perovskite circularly polarized photodetector containing non-chiral cations, characterized in that: The chirality enhancement strategy of chiral two-dimensional perovskite materials is adopted to reduce the interlayer spacing of chiral perovskites and enhance their orientation to achieve effective chirality transfer and charge transfer at the same time, thereby improving the performance of perovskite film circularly polarized light detectors. The specific steps are as follows: (1) preparing a chiral perovskite precursor solution containing achiral cations: dissolving chiral organic ammonium, achiral organic ammonium and metal halide of two-dimensional perovskite in an organic solvent, performing a solvothermal reaction, washing and drying to obtain a chiral perovskite powder containing achiral cations, and subsequently dissolving the powder using an organic solvent; (2) coating a hole transport material on the surface of a conductive substrate and forming a hole transport layer through heat treatment; (3) coating a chiral perovskite precursor solution containing non-chiral cations on the surface of the hole transport layer, and forming a chiral perovskite light absorption layer with circular dichroism response through heat treatment; (4) coating an electron transport material on the surface of the chiral perovskite light absorption layer and forming an electron transport layer through heat treatment; (5) A metal electrode is deposited on the surface of the electron transport layer by vacuum evaporation to obtain a chiral perovskite circularly polarized photodetector containing non-chiral cations.

2. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of the organic ammonium to the metal halide is (1-2):1; the organic solvent is selected from hydroiodic acid and dimethyl sulfoxide; the solvent thermal reaction temperature is 85-100°C, and the reaction time is 20-30h; the mass fraction of the chiral perovskite precursor solution containing achiral cations is 20-60wt%.

3. The preparation method according to claim 2, characterized in that: In step (1), the molar ratio of the chiral organic ammonium to the achiral organic ammonium is 1 / 3 to 3 / 1, the chiral organic ammonium is selected from any one of chiral ammoniums such as R- / S-phenylethylamine, (R / S)-(- / +)-1-phenylpropylamine, (R / S)-1-(3-bromophenyl)ethylamine, (R / S)-1-(2-chlorophenyl)ethylamine, (R / S)-(- / +)-N,α-dimethylbenzylamine, and R- / S-β-methylphenylethylamine, and the achiral organic ammonium is selected from any one of organic ammoniums such as phenylethylamine, n-pentylamine, n-butylamine, 3-bromopropylamine, and 2-bromoethylamine.

4. The preparation method according to claim 3, characterized in that: In step (2), the hole transport layer material is PEDOT:PSS; the coating method is spin coating; the heat treatment temperature is 100-130° C., and the time is 15-20 minutes.

5. The preparation method according to claim 4, characterized in that: In step (3), the solvent of the chiral perovskite precursor solution containing achiral cations is dimethyl sulfoxide; the coating method is substrate heating spin coating, the substrate heating temperature is 65-75°C, the amount of the chiral perovskite precursor solution containing achiral cations coated is 65-75 μL, the anti-solvent is added dropwise during the spin coating process, and the spin coating speed is 2000-6000 rpm; the heat treatment temperature is 80-120°C, and the time is 10-20 minutes.

6. The preparation method according to claim 5, characterized in that: In step (4), the electron transport layer material is PCBM, and 15 to 25 mg of PCBM is dissolved in 1 mL of chlorobenzene; the coating method is spin coating, and the amount of the coated PCBM chlorobenzene solution is 40 to 50 μL; the heat treatment temperature is 45 to 65° C., and the time is 10 to 20 minutes.

7. The preparation method according to claim 6, characterized in that: In step (5), the metal electrode is silver, gold, copper, aluminum, chromium or an alloy thereof.

8. A chiral perovskite circularly polarized photodetector containing achiral cations obtained by the preparation method according to any one of claims 1 to 7.

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