Orientation Method and Application of Cyanobiphenyl Liquid Crystal Doped with Organic Donor Materials

Abstract

The present disclosure provides an alignment method and application of a cyanobiphenyl liquid crystal composite doped with an organic donor material. The organic small molecule is doped in the host cyanobiphenyl liquid crystal, and the small molecule donor / cyanobiphenyl liquid crystal mixture is directionally induced to assemble by virtue of the large surface energy difference between the superhydrophobic structured substrate and the superhydrophilic flat substrate. The liquid crystal molecules form a uniform arrangement under the action of the liquid bridge, driving the self-assembly of the small molecule donor to be embedded in the cyanobiphenyl liquid crystal, forming a structure of electron donor-donor, enhancing the conductivity of the liquid crystal composite device, studying the influence of the surface tension of the solvent on the performance of the composite, and giving a direction for the selection of the solvent. Compared with the methods of inducing the alignment of liquid crystal molecules and donor small molecules by using electric fields, magnetic fields, photolithography, capillary methods, etc., this method is simpler and more feasible, easy to transfer, the circuit pattern is easy to design, and has good stability.

Description

Technical Field

[0001] The present disclosure relates to the field of liquid crystal materials and charge transport, and in particular to an orientation method of cyanobiphenyl liquid crystal doped with an organic small molecule donor material and its application. Background Art

[0002] As a prominent representative of rod-shaped liquid crystals, cyanobiphenyl liquid crystals have set off a wave of preparation of patterned liquid crystal organic optoelectronic devices due to their excellent electron transmission ability. These methods include printing method, nano-template method, microchannel method, etc. Although these methods can achieve very regular periodic arrangement patterns, the types of patterns prepared are limited, the microstructure of the liquid crystal is difficult to control, it is difficult to form a large area of uniform orientation, and it is difficult to transfer the dependence on the microstructure substrate, which limits the conductivity and further application of cyanobiphenyl liquid crystals. Organic small molecule materials have the advantages of fixed structure and easy adjustment, and their excellent optoelectronic properties. They are incorporated into liquid crystals, and organic small molecule donor materials are added to the electron acceptor cyanobiphenyl liquid crystal to form a cyanobiphenyl liquid crystal charge transfer complex. After the complex is oriented, the optoelectronic properties of the cyanobiphenyl liquid crystal can be greatly improved.

[0003] At present, there are few reports on the orientation methods of cyanobiphenyl liquid crystals doped with organic small molecule donor materials at home and abroad, and most of them use extremely complex orientation processes. With the help of the large surface energy difference between the superhydrophobic structured substrate and the superhydrophobic flat substrate, the directional induced assembly of the small molecule donor / cyanobiphenyl liquid crystal mixture is relatively simple and controllable, and the electrical properties of the liquid crystal composite device can be regulated; however, whether the surface tension of the solvent of the solution of the liquid crystal and the small molecule donor in the preparation process has an effect on the orientation process and the electrical properties of the final liquid crystal composite device is not involved in the prior art. Summary of the invention

[0004] The present invention aims at the deficiencies of the prior art and provides an orientation method and application of cyanobiphenyl liquid crystal doped with organic small molecule donor materials. The preparation method is simple, the pattern can be designed, and it is easy to transfer. At the same time, the influence of the solvent surface tension on the orientation and performance of the composite is studied, so as to optimize the performance of liquid crystal optoelectronic devices.

[0005] The technical solution adopted in this disclosure is:

[0006] A method for aligning a cyanobiphenyl liquid crystal composite doped with an organic donor material, the method comprising the following steps:

[0007] According to the shape of the organic donor material / cyanobiphenyl liquid crystal structured pattern to be prepared, preparing a shape template of the organic donor material / cyanobiphenyl liquid crystal structured pattern;

[0008] A superhydrophobic modification of the shape template of the organic donor material / cyanobiphenyl liquid crystal structured pattern;

[0009] Select and adjust the surface tension of the solvent; use the solvent to prepare a homogeneous organic dispersion solution of cyanobiphenyl liquid crystal doped with an organic donor material at a certain concentration;

[0010] Select the upper substrate and perform a superhydrophilic modification on the upper substrate;

[0011] Drop the organic dispersion liquid between the upper substrate and the shape template of the organic donor material / cyanobiphenyl liquid crystal structured pattern;

[0012] The organic dispersion liquid evaporates and shrinks at a suitable temperature and deposits on the upper substrate to form an oriented organic donor material / cyanobiphenyl liquid crystal composite structured pattern.

[0013] Optionally, adjust the surface tension of the solvent to be greater than 30 mN / m.

[0014] Optionally, the solvent includes dimethyl sulfoxide, N-methylpyrrolidone, chlorobenzene or a compound solvent thereof with one or more of toluene, tetrahydrofuran, dimethylformamide, chloroform, and trichloromethane.

[0015] Optionally, it further includes a peeling step of peeling the upper substrate deposited with the oriented organic donor material / cyanobiphenyl liquid crystal composite from the silicon substrate to obtain a shape-controllable organic donor material / cyanobiphenyl liquid crystal composite structured pattern.

[0016] Optionally, the organic donor material includes OXD-7 or BTBP.

[0017] Optionally, the cyanobiphenyl liquid crystal includes 8OCB, 7OCB or 9OCB.

[0018] Optionally, the mass content of the organic donor material accounts for 30%-50% of the post-oriented liquid crystal composite.

[0019] Optionally, the suitable temperature is 70°C - 90°C.

[0020] The present invention also provides a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, and the cyanobiphenyl liquid crystal doped with the organic small molecule donor material is prepared according to the preparation method provided by the present invention.

[0021] The present invention also provides a fluorescent or electrical component, and the fluorescent or electrical component includes a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) The present invention provides an alignment method for a cyanobiphenyl liquid crystal doped with an organic small molecule donor material, and the alignment method is simple and low-cost.

[0024] (2) The present invention provides an alignment method for a cyanobiphenyl liquid crystal doped with an organic small molecule donor material. According to different requirements of actual applications, the pattern of the photomask can be adjusted to change the pattern of the silicon substrate to meet the fluorescence or electrical applications.

[0025] (3) The present invention studies the process parameters in the alignment method for preparing a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, especially the influence of the surface tension of the solvent on the properties of the composite, gives a direction for the selection of the solvent, and obtains a composite with excellent electrical properties to meet the application requirements.

[0026] (4) A cyanobiphenyl liquid crystal doped with an organic small molecule donor material is used as a material for optoelectronic applications. This type of material has excellent optoelectronic properties and can greatly expand the application range of liquid crystal elements. Brief Description of the Drawings

[0027] Figure 1 Optical photograph, polarized light microscope photograph, polarized light microscope photograph with a photo-compensation plate inserted, and XRD pattern of the OXD-7 / 8OCB small molecule donor / liquid crystal composite after alignment in Example 1 of the present disclosure.

[0028] Figure 2 Schematic diagram of attaching a gold film in the electrical application of the OXD-7 / 8OCB small molecule donor / liquid crystal composite after alignment in Example 1 of the present disclosure and possible molecular arrangements in the aligned composite micro-wires.

[0029] Figure 3 Comparison chart of current density passing through the micro-wires of the OXD-7 / 8OCB small molecule donor / liquid crystal composite after alignment, the micro-wires of 8OCB after alignment, and the unaligned film in Example 1 of the present disclosure.

[0030] Figure 4 Schematic diagram of the influence of different heating temperatures on the electrical properties of the OXD-7 / 8OCB small molecule donor / liquid crystal composite after alignment in the present disclosure.

[0031] Figure 5 Schematic diagram of the electrical properties of liquid crystal composite films and micro-wires with different contents of small molecule OXD-7 in the present disclosure.

[0032] Figure 6 Schematic diagram of the influence of different solvents on the electrical properties of liquid crystal composite films and micro-wires with different contents of small molecule OXD-7 in the present disclosure. Detailed Description of the Embodiments

[0033] To enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] In order to make the purpose, technical solutions and advantages of the present disclosure more clear, the present disclosure will be described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and are not used to limit the present disclosure. In addition, the technical features involved in the various embodiments of the present disclosure described below can be combined with each other as long as they do not conflict with each other.

[0035] Example 1

[0036] An alignment method for a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, wherein the organic small molecule donor in the composite structure is OXD-7 and the cyanobiphenyl liquid crystal is 8OCB.

[0037] The alignment method of the above composite includes the following steps:

[0038] (1) Etching a micron-line silicon pillar template: The etched micron-line silicon pillar template is formed by coating a photoresist on a nitrogen-doped, <100> crystal plane, 5-inch diameter, 500-micron thick silicon wafer, using a pre-designed chrome (Cr) quartz photomask, irradiating the photoresist through a laser direct writing device to cure it, and then baking and developing to expose the surface of the silicon wafer where the unexposed part is located. Using a fluorine-based reagent to perform a depth reactive ion etching on the silicon wafer with the photoresist pattern for about 6 minutes, and finally performing a degumming treatment on the substrate, and cleaning it with acetone and ethanol to obtain a micron-line silicon pillar template. The length of the micron-line silicon pillar is 1 cm, the width is 2 microns, the height is 20 microns, and the interval between the patterns is 5 microns.

[0039] (2) Superhydrophobic modification of the micron-line silicon pillar: The micron-line silicon pillar template needs to be cleaned with ethanol and acetone before modification. Using a low-temperature plasma treatment instrument (atmosphere is oxygen, discharge power is 200 W, treatment time is 300 s) to treat the silicon pillar template to activate its surface, and then putting it into a vacuum oven, dropping 5 μl of octadecylfluorosilane, in a vacuum environment, at a temperature of 80 °C, and placing it for 12 hours to obtain a micron-line structured silicon pillar template with superhydrophobic surface, and the water contact angle can reach about 150°.

[0040] (3) Preparation of the mixture solution of the small molecule donor OXD-7 and the liquid crystal 8OCB: In this embodiment, considering the influence of the solvent surface tension, chlorobenzene was first selected as the solvent. OXD-7 and 8OCB were respectively dispersed in chlorobenzene by ultrasonic treatment, and the concentration of the prepared solution was 2.5 mg / mL, and the range could be 0.25 - 10 mg / mL. The chlorobenzene solutions of OXD-7 and 8OCB were mixed together at a volume ratio of 3:7, and a homogeneous solution was formed after ultrasonic treatment. At this time, the mass ratio of the small molecule OXD-7 to 8OCB was 3:7.

[0041] (4) Formation of a micron-scale linear pattern of the oriented donor small molecule OXD-7 and the liquid crystal 8OCB composite on the SiO2@Si wafer: The SiO2@Si wafer was treated with super-hydrophilic treatment using a low-temperature plasma treatment instrument (the atmosphere was oxygen, the discharge power was 200 W, and the treatment time was 300 s). After treatment, the SiO2@Si wafer became super-hydrophilic, and the water contact angle was 0°. 10 μl of the OXD-7 / 8OCB chlorobenzene solution was taken and dropped between the super-hydrophobic micron-scale linear silicon column template and the super-hydrophilic SiO2@Si wafer to form a "sandwich" structure. The lower substrate was the super-hydrophobic micron-scale linear silicon column template, the upper substrate was the super-hydrophilic SiO2@Si wafer, and the middle was the OXD-7 / 8OCB chlorobenzene solution. After placing it in a medium vacuum drying oven at 80 °C for 48 hours, the vacuum drying oven was closed. After the drying oven naturally cooled to room temperature, the sample was taken out. The large surface energy difference between the silicon substrate and the super-hydrophilic flat substrate caused the homogeneous mixed solution to form a micron-scale liquid bridge at the contact surface of the two substrates to directionally induce the assembly of the OXD-7 / 8OCB quantum dots. The liquid crystal 8OCB deflected under the action of the liquid bridge to form a uniform arrangement, driving the orientation of the small molecule OXD-7 to form a charge transfer complex with the liquid crystal 8OCB. At the same time, due to the anchoring effect of the micron-scale linear silicon substrate, a micron-scale linear OXD-7 / 8OCB composite structure identical to the silicon substrate was formed on the upper substrate.

[0042] As Figure 1 shown, the polarized micrographs (a - e) and XRD patterns (f) of the backward OXD-7 / 8OCB microwires were taken; among them, Figure 1 (a) is the optical micrograph of the microwire; Figure 1 (b) and Figure 1 (c) are the polarized micrographs of the microwire at +45° and 0° with respect to the polarizer, respectively; Figure 1 (d), Figure 1 (e) are the micrographs of the microwire at +45° and -45° with respect to the polarizer after adding the optical compensator; Figure 1 (f) is the XRD pattern of the microwire.

[0043] The electrical applications of the above-mentioned OXD-7 / 8OCB composite after orientation:

[0044] Using a semiconductor parameter analyzer with a probe station, the electrical conductivity of the OXD-7 / 8OCB composite after orientation was studied. As Figure 2 shown, where Figure 2 (a) is a schematic diagram of the electrode arrangement: a pair of long strip-shaped gold electrodes are symmetrically placed on the strip-shaped OXD-7 / 8OCB composite, and the distance between the electrodes is about 8 microns. A metal probe is placed on each of the two electrodes. Figure 2 (b) is a schematic diagram of the composite structure. As Figure 3 shown, when a voltage is applied to the oriented liquid crystal composite from -100 V to +100 V, compared with the 8OCB composite film without deflection and patterning, the current density increases by 7 orders of magnitude, and compared with the oriented 8OCB micron wire, the current density increases by 5 orders of magnitude, greatly improving the electrical conductivity of the liquid crystal.

[0045] Optionally, the micron wire silicon column template in this embodiment is a shape template for forming a cyanobiphenyl liquid crystal composite doped with an organic donor material. Based on this shape template, a composite with a corresponding shape is prepared. It can be understood that the shape template of the composite can be designed according to the required circuit pattern.

[0046] Example 2

[0047] An orientation method for a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, where the organic small molecule donor in the composite structure is OXD-7 and the cyanobiphenyl liquid crystal is 8OCB.

[0048] The above orientation method for the composite includes the following steps:

[0049] The orientation method and application in this example are the same as those in Example 1, except that the heating temperature in step (4) is 25 °C at room temperature.

[0050] Example 3

[0051] An orientation method for a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, where the organic small molecule donor in the composite structure is OXD-7 and the cyanobiphenyl liquid crystal is 8OCB.

[0052] The above orientation method for the composite includes the following steps:

[0053] The orientation method and application in this example are the same as those in Example 1, except that the heating temperature in step (4) is 40 °C.

[0054] Example 4

[0055] An orientation method for a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, where the organic small molecule donor in the composite structure is OXD-7 and the cyanobiphenyl liquid crystal is 8OCB.

[0056] The orientation method of the above-mentioned composite includes the following steps:

[0057] The orientation method and application in this embodiment are the same as those in Embodiment 1, except that the heating temperature in step (4) is 60 °C.

[0058] Through the study of the heating temperature, in order to achieve the orientation of the composite of the present invention, the appropriate heating temperature ranges from room temperature to 100 °C. Embodiment 5

[0059] An orientation method for a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, wherein the organic small molecule donor in the composite structure is OXD-7 and the cyanobiphenyl liquid crystal is 8OCB.

[0060] The orientation method of the above-mentioned composite includes the following steps:

[0061] The orientation method and application in this embodiment are the same as those in Embodiment 1, except that the mass ratio of OXD to 8OCB in step (3) is 2:8.

[0062] Embodiment 6

[0063] An orientation method for a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, wherein the organic small molecule donor in the composite structure is OXD-7 and the cyanobiphenyl liquid crystal is 8OCB.

[0064] The orientation method of the above-mentioned composite includes the following steps:

[0065] The orientation method and application in this embodiment are the same as those in Embodiment 1, except that the mass ratio of OXD-7 to 8OCB in step (3) is 4:6.

[0066] Embodiment 7

[0067] An orientation method for a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, wherein the organic small molecule donor in the composite structure is OXD-7 and the cyanobiphenyl liquid crystal is 8OCB.

[0068] The orientation method of the above-mentioned composite includes the following steps:

[0069] The orientation method and application in this embodiment are the same as those in Embodiment 1, except that the cyanobiphenyl liquid crystal 8OCB is replaced by 7OCB.

[0070] Embodiment 8

[0071] An orientation method for a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, wherein the organic small molecule donor in the composite structure is OXD-7 and the cyanobiphenyl liquid crystal is 8OCB.

[0072] The orientation method of the above-mentioned composite includes the following steps:

[0073] The alignment method and application in this embodiment are the same as those in Embodiment 1, except that the cyanobiphenyl liquid crystal 8OCB is replaced by 9OCB.

[0074] To study the electrical properties of the cyanobiphenyl liquid crystal after alignment of the doped small molecule donor material of the present invention, when the concentration of the OXD-7 / 8OCB mixed organic solution is fixed at 2.5 mg / mL, during the preparation process, the heating temperature in step (4) has a great influence on the conductivity of the prepared liquid crystal composite micro-wires. As Figure 4 shown, among which, Figure 4 (a) is the J-V curve of the liquid crystal composite micro-wires; Figure 4 (b) is the relationship between the current density value of each liquid crystal composite micro-wire when a voltage of -60 V is applied and the heating temperature during the alignment process; Figure 4 (c) is the XRD pattern. As Figure 4 shown, when the heating temperature is 70°C - 90°C, the current density passing through the micro-wires is increased by 3 orders of magnitude compared with that at other heating temperatures. Especially when the heating temperature is 80°C, the current density is increased by 5 orders of magnitude. Subsequently, XRD means were used to study the liquid crystal properties of the micro-wires formed at different heating temperatures, and the XRD pattern shown in Figure 4 (c) was obtained. When the heating temperature is 70°C - 90°C, a strong diffraction peak appears at 3.7° in the XRD curve, corresponding to the (001) plane of 8OCB, indicating that the liquid crystal molecules form a smectic layered ordered arrangement, and the 8OCB molecules stand vertically on the upper substrate. The diffraction peak appearing at 6.9° comes from the (200) plane of the small molecule OXD-7, representing that OXD-7 presents a B6 phase arrangement. At 80°C, the uniform arrangement of the liquid crystal and the small molecule forms a good electron donor-acceptor pairing, so the conductivity of the sample is the strongest at this time. When the heating temperature is lower than 70°C (25°C - 60°C), only the strong diffraction peak of 8OCB at 3.7° is observed, indicating that low temperature is beneficial to the alignment of the liquid crystal 8OCB. When the temperature is higher than 90°C (100°C), a strong diffraction peak of the small molecule OXD-7 appears, while the diffraction peak of 8OCB is significantly weakened, indicating that high temperature is beneficial to the uniform arrangement of OXD-7, while the alignment of 8OCB becomes very weak. Correspondingly, when the heating temperature is lower than 70°C or higher than 90°C, the current density of the sample is significantly lower than that at 70°C - 90°C. Only when 8OCB and OXD-7 form a uniform arrangement at the same time, the conductivity in the sample can reach the maximum, and the uniform arrangement of a single 8OCB or OXD-7 has little effect on the conductivity of the liquid crystal composite.

[0075] As Figure 5As shown, the effect of the mass content of the small molecule OXD-7 on the conductivity of the prepared liquid crystal composite microwires is studied. Among them, the concentration of the OXD-7 / 8OCB organic mixed solution is fixed at 2.5 mg / mL, and the heating temperature during the orientation process is 80 °C. Figure 5 (a) are the J-V curves of liquid crystal composite films and microwires with different OXD-7 contents; Figure 5 (b) is a comparative bar chart of the current density passing through the unoriented film of OXD-7 / 8OCB, the unoriented film of 8OCB, the oriented microwires, and the microwires of liquid crystal composites with OXD-7 contents of 30%, 40%, and 50% when a voltage of -60 V is applied;

[0076] Figure 5 (c) is the relationship between the current density value of each composite liquid crystal microwire and the OXD-7 content when a voltage of -60 V is applied; Figure 5 (d) is the XRD pattern. It can be seen from the figure that when the mass content of OXD-7 is 30% - 50%, the current density passing through the microwires is increased by 3 orders of magnitude compared with that of microwires with other contents. Especially when the OXD-7 content is 30%, it is increased by nearly 5 orders of magnitude, greatly improving the conductivity of OXD-7 / 8OCB. Corresponding to the XRD diffraction pattern, a strong diffraction peak appears at 3.7°, corresponding to the (001) plane of 8OCB, indicating that the liquid crystal molecules form a smectic layered ordered arrangement, and 8OCB stands vertically on the upper substrate. The diffraction peak appearing at 6.9° comes from the (200) plane of the small molecule OXD-7, representing the B6-phase arrangement of OXD-7. When the OXD-7 content is 30%, the liquid crystal and the small molecule are uniformly arranged, forming a good electron donor-acceptor pair, and the conductivity of the composite microwires is the strongest at this time. When the content of OXD-7 is less than 30%, there are three peaks in the XRD diffraction pattern. A diffraction peak appears near 3.0°, corresponding to the smectic A phase (partial bilayer smectic Ad, SmAd) of the trans-dimer of 8OCB. A diffraction peak appears at 3.7°, corresponding to the diffraction peak of the (001) plane of the smectic layer of 8OCB. The third peak appears at 6.9°, corresponding to the B6 phase of the small molecule OXD-7. The SmAd arrangement of 8OCB is not conducive to the formation of donor-acceptor complexes in the composite microwires, so the conductivity drops significantly. When the content of OXD-7 is higher than 50%, only the diffraction peak of the B6 phase of OXD-7 appears, and the diffraction peak of 8OCB does not appear, indicating that 8OCB does not form an ordered arrangement, so the conductivity is not high either.

[0077] Example 9

[0078] In this example, the effect of the surface tension of the solvent on the performance of the final device is considered during the preparation of a cyanobiphenyl liquid crystal composite doped with an organic donor material.

[0079] An alignment method for a cyanobiphenyl liquid crystal composite doped with an organic small molecule donor material, where the organic small molecule donor in the composite structure is OXD-7 and the cyanobiphenyl liquid crystal is 8OCB.

[0080] The alignment method for the above composite includes the following steps:

[0081] According to the alignment method of Example 1, replace the organic solvent chlorobenzene in step (3) with toluene, tetrahydrofuran, dimethylformamide, trichloromethane, chloroform, and n-hexane respectively. This experiment confirms that chlorobenzene, toluene, tetrahydrofuran, dimethylformamide, trichloromethane, and chloroform can all enable the composite to achieve excellent alignment. However, when the solvent is changed to n-hexane, the conductivity of the micro wires decreases, indicating that the surface tension of the solvent affects the alignment and conductivity of the micro wires; the surface tension values of chlorobenzene, toluene, tetrahydrofuran, dimethylformamide, trichloromethane, and chloroform are 33 mN / m, 28 mN / m, 26.4 mN / m, 25.7 mN / m for dimethylformamide, 28.9 mN / m for trichloromethane, and 27.6 mN / m for chloroform respectively; when the surface tension of these solvents is greater than 25 mN / m, the composite micro wires can achieve excellent alignment ( Figure 6 ). The surface tension value of n-hexane is 18.92 mN / m, and when this solvent is used, the alignment of the micro wires decreases.

[0082] To further study the influence of the solvent surface tension, N-methylpyrrolidone (NMP) (surface tension about 34 mN / m) and dimethyl sulfoxide (DMSO) (surface tension about 42.3 mN / m) are respectively selected as solvents, and the test results are as Figure 6 shown.

[0083] It can be seen that the performance of the micro wires obtained with solvents of high surface tension is better. The current density of the composite micro wires after alignment with dimethyl sulfoxide as the solvent increases by at least 10 times. That is, the adjustment of the solvent surface tension can affect the assembly process of liquid crystal molecules and small molecule donors, thereby affecting the alignment and electrical properties of the composite.

[0084] In addition, in order to obtain the desired arbitrary surface tension, or to combine the advantages and disadvantages of various solvents (such as some solvents being highly toxic and some solvents having high costs), some solvents can also be compounded. For example, dimethyl sulfoxide (DMSO) and chlorobenzene are compounded and mixed in a certain proportion, and the surface tension of the mixed solvent can be measured according to the pendant drop method.

[0085] Specifically, solvents with high surface tension, such as chlorobenzene, toluene, tetrahydrofuran, dimethylformamide, chloroform, etc., usually have a surface tension value greater than 25 mN / m. More preferably, solvents with a surface tension value greater than 33, such as N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), or a mixed solvent of dimethyl sulfoxide and other solvents (such as chlorobenzene, toluene, tetrahydrofuran, dimethylformamide, chloroform); they are more conducive to forming a stable liquid bridge and promoting the oriented arrangement of liquid crystal molecules and donor small molecules in the liquid bridge. When the solvent evaporates, the contraction force of the liquid bridge can more effectively drive molecular orientation, forming a more ordered structure, thereby enhancing the conductivity of the device. In contrast, solvents with low surface tension (such as n-hexane, whose surface tension value is 18.92 mN / m) may cause the liquid bridge to be unstable, making it difficult to form effective orientation forces, resulting in a disordered structure of the composite and a decrease in conductivity.

[0086] In practical applications, most surfactants are used to reduce the surface tension of solvents. In the application scenario of the present invention, increasing the surface tension of the solvent is beneficial to the orientation of the cyanobiphenyl liquid crystal composite. Therefore, in the whole scheme, when preparing the solution of liquid crystal and small molecule donor, considering the influence of the surface tension of the solvent, screening the solvent and consciously adjusting the surface tension are important steps to improve the orientation efficiency and performance of the composite. However, the selection of the solvent should also consider its solubility, stability for liquid crystal and small molecule donor, and compatibility with subsequent processes (such as evaporation, drying process). Therefore, although the surface tension of some solvents is higher, whether they are suitable for the implementation of the present invention still needs to be verified by experiments on their specific performance during the preparation process of the composite.

[0087] Compared with the prior art, the beneficial effects of the present disclosure are as follows:

[0088] (1) The orientation method of cyanobiphenyl liquid crystal doped with small molecule donor materials provided by the present invention is simple and low-cost.

[0089] (2) The orientation method of cyanobiphenyl liquid crystal doped with small molecule donor materials provided by the present invention can adjust the pattern of the photomask to change the pattern of the silicon substrate according to different requirements of practical applications to meet fluorescence or electrical applications.

[0090] (3) The present invention studies the process parameters in the orientation method of preparing cyanobiphenyl liquid crystal composites doped with organic small molecule donor materials, especially the influence of the surface tension of the solvent on the performance of the composite, gives a direction for the selection of the solvent, and obtains composites with excellent electrical properties to meet the application requirements.

[0091] (4) The cyanobiphenyl liquid crystal doped with a small molecule donor material is used as a material for optoelectronic applications. This type of material has excellent optoelectronic properties and can greatly expand the application scope of liquid crystal elements.

[0092] The embodiments described above are only descriptions of the preferred embodiments of the present disclosure. The preferred embodiments do not elaborate on all details and do not limit the invention to the specific embodiments described. Without departing from the design spirit of the present disclosure, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present disclosure shall fall within the protection scope determined by the claims of the present disclosure.

Claims

1. A method for aligning a cyanobiphenyl liquid crystal composite doped with an organic donor material, characterized in that, The orientation method includes the following steps: Prepare a shape template of the organic donor material / cyanobiphenyl liquid crystal structured pattern according to the shape of the organic donor material / cyanobiphenyl liquid crystal structured pattern to be prepared; Superhydrophobically modify the shape template of the organic donor material / cyanobiphenyl liquid crystal structured pattern; Select and adjust the surface tension of the solvent; use the solvent to prepare a homogeneous organic dispersion solution of cyanobiphenyl liquid crystal doped with an organic donor material at a certain concentration; Select an upper substrate and superhydrophilically modify the upper substrate; Drop the organic dispersion solution between the upper substrate and the shape template of the organic donor material / cyanobiphenyl liquid crystal structured pattern; The organic dispersion solution evaporates and shrinks at a suitable temperature and deposits on the upper substrate to form an oriented organic donor material / cyanobiphenyl liquid crystal composite structured pattern; wherein, The organic donor material includes OXD-7 or BTBP; the cyanobiphenyl liquid crystal includes 8OCB, 7OCB or 9OCB.

2. The alignment method of the cyanobiphenyl liquid crystal composite doped with an organic donor material according to claim 1, characterized in that: Adjust the surface tension of the solvent to be greater than 30 mN / m.

3. The alignment method of the cyanobiphenyl liquid crystal composite doped with an organic donor material according to claim 2, characterized in that: The solvent includes dimethyl sulfoxide, N-methylpyrrolidone, chlorobenzene or a compound solvent thereof with one or more of toluene, tetrahydrofuran, dimethylformamide, chloroform, trichloromethane; 4. The alignment method of the cyano-biphenyl liquid crystal composite doped with an organic donor material according to claim 1, characterized in that: It further includes a peeling step of peeling the upper substrate deposited with the oriented organic donor material / cyanobiphenyl liquid crystal composite from the silicon substrate to obtain an organic donor material / cyanobiphenyl liquid crystal composite structured pattern with controllable shape.

5. The alignment method of the cyano-biphenyl liquid crystal composite doped with an organic donor material according to claim 1 or 2, characterized in that: The mass content of the organic donor material accounts for 30%-50% of the liquid crystal composite after orientation.

6. The alignment method of the cyanobiphenyl liquid crystal composite doped with an organic donor material according to claim 1 or 2, characterized in that: The suitable temperature is 70°C - 90°C.

7. A cyanobiphenyl liquid crystal composite of an oriented doped donor material, characterized in that, The cyanobiphenyl liquid crystal doped with the organic donor material is prepared by the method according to any one of claims 1-6.

8. A fluorescent or electrical component, characterized in that, The fluorescent or electrical component includes the oriented cyanobiphenyl liquid crystal composite doped with the organic donor material according to claim 7.

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