Polarized light detector with high circular dichroism ratio based on organic chiral small molecule material and preparation method of polarized light detector

Abstract

The invention discloses a high circular dichroism ratio polarized light detector based on an organic chiral small molecule material and a preparation method thereof.The high circular dichroism ratio polarized light detector comprises a substrate, an active layer, a source electrode and a drain electrode, the active layer is located on the upper surface of the substrate, and the source electrode and the drain electrode are oppositely located at the two ends of the upper surface of the active layer; the active layer is a (-)-2NDI or (+)-2NDI organic chiral small molecule single crystal, and the polarized light detector also ensures a large circular dichroism ratio on the basis of improving the photoelectric property.

Description

Technical Field

[0001] The invention relates to the technical field of functional materials, and in particular to a high circular dichroism ratio polarized light detector based on organic chiral small molecule materials and a preparation method thereof. Background Art

[0002] Circularly polarized light detection technology brings new opportunities to emerging technologies, including optical communication encryption, quantum computing, bioimaging and multi-channel data processing. The distinction between left-handed and right-handed light can not only facilitate the rapid determination of the absolute configuration of chiral molecules, but also has great application potential in environmental monitoring and medical imaging. Although commercial devices can distinguish between left-handed and right-handed light, they need to combine inorganic photodetectors that are insensitive to circularly polarized light with rigid and bulky optical components. This limits their spectral range and is both expensive and difficult to miniaturize.

[0003] The direct detection of circularly polarized light using chiral functional materials provides a promising approach to address the above problems. Moreover, this method does not require external optical equipment and can combine photodetection with circular polarization sensing into a single device, which has attracted widespread attention. To this end, various organic and organic-inorganic chiral materials have been explored for circularly polarized light detection, including inorganic nanomaterials, chiral organic small molecules, polymers, and organic-inorganic hybrid perovskites. Among them, organic semiconductors have obvious advantages over other materials due to their intrinsic chirality, simple processing requirements, compatibility with low-cost manufacturing processes, and the fact that their chirality can be easily customized through reasonable molecular design.

[0004] To date, several approaches have been reported to fabricate organic circularly polarized light detectors, such as mixing achiral polymers with chiral small molecule additives, amplifying chirality through supramolecular or multiscale assembly, and utilizing twisted molecules. However, there is an inevitable trade-off between charge transport properties and circular polarization selectivity, as the former requires a planar π-π stacking structure, while the latter requires a twisted structure. As a result, most existing organic circularly polarized light detectors show low optoelectronic performance and limited circular polarization selectivity. Therefore, there is a need to develop chiral organic semiconductors that can selectively sense circularly polarized light while maintaining efficient charge transport. Summary of the invention

[0005] The purpose of the present invention is to provide a high circular dichroic ratio polarized light detector based on organic chiral small molecule materials in order to solve the problem of low circular dichroic ratio level and photoelectric performance of circularly polarized light detectors in the prior art.

[0006] Another object of the present invention is to provide a method for preparing the high circular dichroism ratio polarized light detector.

[0007] The technical solution adopted to achieve the purpose of the present invention is:

[0008] A high circular dichroism ratio polarized light detector based on organic chiral small molecule materials, wherein the active layer is (-)-2NDI or (+)-2NDI organic chiral small molecule single crystal, and the structural formula of (-)-2NDI is:

[0009]

[0010] The structural formula of (+)-2NDI is:

[0011]

[0012] The method for preparing the (-)-2NDI or (+)-2NDI organic chiral small molecule single crystal is as follows: dissolving (-)-2NDI or (+)-2NDI in a volatile organic solvent, standing the solution, and allowing the volatile organic solvent to evaporate to obtain the (-)-2NDI or (+)-2NDI organic chiral small molecule single crystal.

[0013] In the above technical solution, the polarized light detector includes a substrate, an active layer, a source electrode and a drain electrode. The active layer is located on the upper surface of the substrate, and the source electrode and the drain electrode are relatively located at two ends of the upper surface of the active layer.

[0014] In the above technical solution, the substrate is a p-type doped silicon oxide wafer.

[0015] In the above technical solution, the source electrode and the drain electrode are both silver electrodes.

[0016] In another aspect of the present invention, the method for preparing the polarized light detector comprises the following steps:

[0017] Step 1, cleaning, drying and oxygenating a single-throw silicon oxide wafer, and then hydrophobically modifying the wafer with octadecyltrichlorosilane, and then cleaning and drying the wafer to obtain a hydrophobically modified substrate;

[0018] Step 2, dissolving an organic chiral small molecule (-)-2NDI or (+)-2NDI in chloroform, and obtaining a mixed solution after ultrasonic dispersion, and dropping the mixed solution onto the hydrophobically modified substrate obtained in step 1, and allowing the mixed solution to stand to obtain a chiral small molecule single crystal as an active layer, thereby obtaining an intermediate sample;

[0019] Step 3, evaporating silver electrodes on the hydrophobic modified substrate obtained in step 1, and then transferring them to the opposite ends of the active layer of the intermediate sample obtained in step 2, respectively serving as the source electrode and the drain electrode, to obtain a polarized light detector.

[0020] In the above technical solution, in step 1, the cleaning and drying step is: ultrasonically clean the single-polished silicon oxide wafer with deionized water, acetone, and isopropanol in sequence for 10-20 minutes, and then blow dry with high-purity nitrogen.

[0021] In the above technical solution, in step 1, the oxygenation time is 10-20 minutes.

[0022] In the above technical solution, in step 1, the steps of cleaning and drying are: ultrasonic cleaning with chloroform, n-hexane and isopropanol for 10-20 minutes in sequence, and then drying with high-purity nitrogen.

[0023] In the above technical solution, in step 2, 0.5-1 mg of organic chiral small molecule (-)-2NDI or (+)-2NDI is dissolved in each ml of chloroform.

[0024] In the above technical solution, in step 3, the thickness of the silver electrode is 100-200 nm.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The circularly polarized light detector based on organic chiral small molecule single crystal provided by the present invention, wherein the active layer adopts organic chiral small molecule single crystal. Since the organic chiral small molecule single crystal not only maintains the planar π-π stacking structure but also does not produce a large distorted structure, it has excellent photoelectric performance.

[0027] 2. The circularly polarized light detector based on organic chiral small molecule single crystal provided by the present invention not only improves the photoelectric performance, but also ensures a large circular dichroism ratio, thus overcoming the difficulties of traditional circular polarization detectors based on organic semiconductor materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure shows the structure of a circularly polarized light detector based on organic chiral small molecule single crystal materials; in the figure: 1-silicon part, 2-SiO 2 Parts: 3-active layer, 4-source electrode, 5-drain electrode, 6-wave plate, 7-polarizer.

[0029] Figure 2 Shown are the X-ray diffraction spectra of (-)-2NDI, (+)-2NDI and single crystal simulation;

[0030] Figure 3 Shown is a schematic diagram of the crystal structure of (-)-2NDI single crystal.

[0031] Figure 4 Shown are the circular dichroism spectra of organic chiral small molecule single crystal materials of (-)-2NDI and (+)-2NDI;

[0032] Figure 5 Shown is the result of circularly polarized light detection by a (-)-2NDI-based circularly polarized light detector under 450 nm left- and right-handed circularly polarized light irradiation. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Example 1

[0035] A high circular dichroism ratio polarization light detector based on organic chiral small molecules, such as Figure 1 As shown, it includes a substrate, an active layer 3, a source electrode 4 and a drain electrode 5. The active layer 3 is located on the upper surface of the substrate. The material of the active layer 3 is a (-)-2NDI or (+)-2NDI organic chiral small molecule single crystal. The source electrode 4 and the drain electrode 5 are relatively located at the two ends of the upper surface of the active layer. The substrate includes a silicon part 1 and a SiO 2 Part 2, active layer 3 is located on SiO2 hydrophobically modified with octadecyltrichlorosilane. 2 The upper surface of part 2.

[0036] The structural formula of (-)-2NDI is:

[0037]

[0038] The structural formula of (+)-2NDI is:

[0039]

[0040] Example 2

[0041] A method for preparing a high circular dichroism ratio polarization light detector based on organic chiral small molecules comprises the following steps:

[0042] Step 1, preparation of hydrophobic modified substrate:

[0043] First, a commercial standard 4-inch p-type doped single-throw silicon oxide wafer (the thickness of the silicon part is 500um, the resistivity is 1-10Ω·cm, SiO 2 Thickness 300nm) cut into 1×1cm 2 size.

[0044] Then, the organic matter attached to the surface of the single-polished silicon oxide wafer was removed by ultrasonic cleaning with deionized water, acetone and isopropanol for 10 minutes in sequence. After the cleaning, it was blown clean with high-purity nitrogen to obtain a cleaned insulating substrate.

[0045] Finally, the insulating substrate was oxygenated at 80W for 10 minutes and then hydrophobically modified with octadecyltrichlorosilane; it was then ultrasonically cleaned with chloroform, n-hexane and isopropanol for 10 minutes in sequence to obtain a hydrophobically modified substrate.

[0046] Step 2, synthesize an organic chiral small molecule (-)-2NDI, and dissolve it in chloroform, and obtain a mixed solution after ultrasonic dispersion, and drop the mixed solution onto the hydrophobic modified substrate obtained in step 1, and let it stand to obtain a chiral small molecule single crystal as an active layer to obtain an intermediate sample, specifically:

[0047] A solution of (RR)-trans-1,2-cyclohexanediamine (0.171 g, 1.5 mmol) in anhydrous DMF (10 mL) was quickly added to a solution of naphthalenetetracarboxylic dianhydride (0.398 g, 1.5 mmol) in anhydrous DMF (500 mL) and stirred vigorously at 130°C. The resulting deep red reaction mixture was stirred at 130°C for 6 hours, after which DMF was removed under reduced pressure (~3 mbar) at 60°C. The deep red residue was dissolved in CH 2 Cl 2 and column chromatography (SiO 2 :CH 2 Cl 2 / Me 2 CO, gradient from 0-10% Me 2 CO) followed by precipitation with MeOH to afford pure (-)-2NDI as a slightly yellow solid.

[0048] Take 0.5 mg (-)-2NDI and dissolve it in 1 ml chloroform solution. After ultrasonic treatment for 1 hour, take 50 ul of the mixed solution and drop it on the hydrophobic modified substrate obtained in step 1. Let it stand for 24 hours to prepare an organic chiral small molecule single crystal material, which is used as the active layer to obtain an intermediate sample.

[0049] Step 3, evaporate a 150nm silver electrode on the hydrophobic modified substrate obtained in step 1, then pick it up with a probe and transfer it to the left and right sides of the top of the active layer of the intermediate sample obtained in step 2, respectively serving as the source electrode and drain electrode, to obtain a circularly polarized light detector based on organic chiral small molecule single crystal material.

[0050] Example 3

[0051] The difference between this embodiment and embodiment 2 is that the active layer adopts (+)-2NDI organic chiral small molecule single crystal, and the other steps are the same as those in embodiment 2. Specifically, the difference is that in step 2, the organic chiral small molecule (+)-2NDI is synthesized, and the raw material used is (SS)-trans-1,2-cyclohexanediamine.

[0052] Test Example 1

[0053] pass Figure 2 The comparison of X-ray diffraction (XRD) of (-)-2NDI, (+)-2NDI and single crystal simulation proves the successful preparation of chiral small molecule single crystal materials.

[0054] The crystal structure diagram of (-)-2NDI single crystal is shown in Figure 3 The crystallographic data are shown in Table 1.

[0055] Table 1 Crystallographic data of (-)-2NDI single crystal

[0056]

[0057] Test Example 2

[0058] The circular dichroism spectra of (-)-2NDI and (+)-2NDI are as follows: Figure 4 As shown, the organic chiral small molecule single crystal material has good absorption in the 250-500 nanometer region and has a typical "marshmallow" effect, indicating that it has strong circularly polarized light absorption.

[0059] Test Example 3

[0060] The circular polarization light detector of Example 2 is subjected to polarization light detection test. The circular polarization light detector is ensured to be stationary and the intensity of the irradiated polarized laser light is constant. Figure 1 As shown, after the laser passes through the polarizer 7 and the wave plate 6, it is irradiated on the active layer 3 of the circularly polarized light detector. Each time the wave plate 6 is rotated by one quarter and each time it is rotated by 90 degrees, it is equivalent to the polarized laser irradiated on the circularly polarized light detector switching between left-handed circularly polarized light and right-handed circularly polarized light. The photocurrent of the circularly polarized light detector under different circularly polarized light irradiation conditions is tested with the help of a semiconductor parameter tester. Figure 5 The result of circularly polarized light detection by the circularly polarized light detector of Example 2 is shown. It can be seen that under the irradiation of light with different circular polarizations, light with different chirality corresponds to different current responses, which is due to the different absorption of left-handed and right-handed circularly polarized light by organic chiral small molecule single crystals.

[0061] Based on the different current responses corresponding to different circularly polarized lights in the circularly polarized light detector of organic chiral small molecule single crystal materials, the g factor is calculated by the current under left-handed and right-handed circularly polarized light. The maximum g value can reach 0.5 under 450nm light, and the circular polarization characteristics are obvious.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high circular dichroism ratio polarization light detector based on organic chiral small molecule materials, characterized in that: The active layer is (-)-2NDI or (+)-2NDI organic chiral small molecule single crystal, and the structural formula of (-)-2NDI is: The structural formula of (+)-2NDI is:

2. The high circular dichroic ratio polarized light detector according to claim 1, characterized in that: The method for preparing the (-)-2NDI or (+)-2NDI organic chiral small molecule single crystal is as follows: dissolving (-)-2NDI or (+)-2NDI in a volatile organic solvent, standing the solution, and allowing the volatile organic solvent to evaporate to obtain the (-)-2NDI or (+)-2NDI organic chiral small molecule single crystal.

3. The high circular dichroic ratio polarized light detector according to claim 1, characterized in that: The polarized light detector comprises a substrate, an active layer, a source electrode and a drain electrode. The active layer is located on the upper surface of the substrate, and the source electrode and the drain electrode are located at two ends of the upper surface of the active layer opposite to each other.

4. The high circular dichroic ratio polarization light detector according to claim 1, characterized in that: The substrate is a p-type doped silicon oxide wafer.

5. The high circular dichroic ratio polarized light detector according to claim 1, characterized in that: The source electrode and the drain electrode are both silver electrodes.

6. The method for preparing a high circular dichroic ratio polarization light detector according to claim 1, characterized in that: The following steps are involved: Step 1, cleaning, drying and oxygenating a single-throw silicon oxide wafer, and then hydrophobically modifying the wafer with octadecyltrichlorosilane, and then cleaning and drying the wafer to obtain a hydrophobically modified substrate; Step 2, dissolving an organic chiral small molecule (-)-2NDI or (+)-2NDI in chloroform, and obtaining a mixed solution after ultrasonic dispersion, and dropping the mixed solution onto the hydrophobically modified substrate obtained in step 1, and allowing the mixed solution to stand to obtain a chiral small molecule single crystal as an active layer, thereby obtaining an intermediate sample; Step 3, evaporating silver electrodes on the hydrophobic modified substrate obtained in step 1, and then transferring them to the opposite ends of the active layer of the intermediate sample obtained in step 2, respectively serving as the source electrode and the drain electrode, to obtain a polarized light detector.

7. The preparation method according to claim 6, characterized in that: In step 1, the cleaning and drying steps are as follows: the single-throw silicon oxide wafer is ultrasonically cleaned with deionized water, acetone, and isopropanol in sequence for 10-20 minutes, and then blown dry with high-purity nitrogen.

8. The preparation method according to claim 6, characterized in that: In step 1, the oxygenation time is 10-20 minutes, and the cleaning and drying steps are: ultrasonic cleaning with chloroform, n-hexane and isopropanol for 10-20 minutes in sequence, and then drying with high-purity nitrogen.

9. The preparation method according to claim 6, characterized in that: In the step 2, 0.5-1 mg of an organic chiral small molecule (-)-2NDI or (+)-2NDI is dissolved in each ml of chloroform.

10. The preparation method according to claim 6, characterized in that: In the step 3, the thickness of the silver electrode is 100-200 nm.

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