A method for preparing large-area single-layer single-crystal domain organic semiconductor single crystal

Abstract

The present invention belongs to the technical field of organic semiconductors, and specifically relates to a method for preparing a large-area single-layer single-crystal domain organic semiconductor single crystal. The method comprises: 1) preparing an organic semiconductor solution a and an organic semiconductor solution b respectively; 2) taking a substrate and performing a solvent-philic treatment and a solvent-phobic treatment respectively to obtain a solvent-philic substrate and a solvent-phobic substrate; 3) heating the solvent-philic substrate, and simultaneously heating the organic semiconductor solution a and the organic semiconductor solution b or a mixed solution of the two, treating the stacked solvent-philic substrate and the solvent-phobic substrate with the organic semiconductor solution a and the organic semiconductor solution b or a mixed solution of the two, and obtaining an organic semiconductor single crystal after solidification. The present invention uses two organic semiconductor mixed solutions with double-sided substituted alkyl chains, which reduces the nucleation density, inhibits the tendency of multilayer growth of crystals, and realizes the growth of large-area single-layer single crystal domains.

Description

Technical Field

[0001] The invention belongs to the technical field of organic semiconductors, and in particular relates to a method for preparing a large-area single-layer single-crystal domain organic semiconductor single crystal. Background Art

[0002] Organic semiconductor materials are bonded by weak van der Waals forces between molecules, which easily produce grain boundaries and defects during the bonding process, greatly affecting carrier transport, thus limiting their practical applications. Among organic semiconductor materials, single-layer single-domain organic semiconductors have the advantages of single crystal long-range order, few impurity defects, and good flexibility and transparency of two-dimensional materials, and have great development potential in the field of organic optoelectronic applications.

[0003] The stable growth of large-area single-layer single-domain organic semiconductor single crystals is of great significance for studying their intrinsic properties, carrier transport modes, and building high-performance organic electronic devices. However, since organic semiconductor materials rely on weak van der Waals forces between molecules, crystal growth is easily affected by external conditions. The two-dimensional organic semiconductor single crystals grown by traditional methods have small domain sizes and relatively complex growth methods. Summary of the invention

[0004] Based on the above content, in order to solve the problems of uncontrollable crystal structure and complicated growth method, the present invention proposes a method for preparing large-area single-layer single-crystal domain organic semiconductor single crystal.

[0005] The purposes of the present invention are: 1. to ensure that the organic semiconductor presents a single-layer single-crystal structure and to increase the size of the single-crystal domain of the organic semiconductor; 2. to improve the stability of the organic semiconductor.

[0006] 3. Provide a simple method for preparing single-crystal organic semiconductors.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions.

[0008] A method for preparing a large-area single-layer single-crystal domain organic semiconductor single crystal, characterized in that the method comprises: 1) taking an organic semiconductor material A and an organic semiconductor material B and dissolving them in an organic solvent to prepare an organic semiconductor solution a and an organic semiconductor solution b respectively.

[0009] 2) The substrate is treated with a solvent-philic substrate and a solvent-phobic substrate respectively to obtain a solvent-philic substrate and a solvent-phobic substrate.

[0010] 3) The solvent-philic substrate is subjected to a heating treatment, and the organic semiconductor solution a and the organic semiconductor solution b or a mixed solution thereof are subjected to a heating treatment, and the stacked solvent-philic substrate and the solvent-phobic substrate are treated with the organic semiconductor solution a and the organic semiconductor solution b or a mixed solution thereof, and an organic semiconductor single crystal is obtained after solidification.

[0011] Preferably, the organic semiconductor material A in step 1) is 2,9-dialkyl (C n , n is a natural number) dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C n -DNTT) and / or 2,7-dialkyl (C n , n is a natural number) dibenzo[d,d]thiophene[3,2-b;4,5-b]dithiophene (C n -DBTDT) and / or 2,7-dialkyl (C n , n is a natural number) benzothiophene [3,2-b]benzothiophene (C n -BTBT).

[0012] Step 1) The organic semiconductor material B is 2,9-dialkyl (C n , n is a natural number) dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C n -DNTT) and / or 2,7-dialkyl (C n , n is a natural number) dibenzo[d,d]thiophene[3,2-b;4,5-b]dithiophene (C n -DBTDT) and / or 2,7-dialkyl (C n , n is a natural number) benzothiophene [3,2-b]benzothiophene (C n -BTBT).

[0013] Step 1) The number of carbon atoms in the alkyl group of the organic semiconductor material A (C n The number of carbon atoms in the alkyl group of the organic semiconductor material B (C n in (n).

[0014] Preferably, the organic solvent in step 1) is toluene and / or xylene and / or trimethylbenzene and / or chlorobenzene and / or dichlorobenzene and / or trichlorobenzene and / or tetralin and / or decalin and / or chlorothiophene.

[0015] Step 1) The concentration of the organic semiconductor material A in the organic semiconductor solution a is 0.05-1.20 mg / mL.

[0016] Step 1) The concentration of the organic semiconductor material B in the organic semiconductor solution b is 0.05-1.20 mg / mL.

[0017] Preferably, the solvent-philic treatment is one of the following methods: Method 1: a smooth substrate is pretreated, placed in an inert gas environment, a hydrocarbon compound is spin-coated on the substrate, and a solvent-philic substrate is obtained by heat treatment; the pretreatment is carried out under the condition of 8 to 12 W, using oxygen plasma treatment for 1 to 2 min; the hydrocarbon compound is benzocyclobutene, and the spin coating thickness is 100 to 1000 nm; the heat treatment is carried out at a constant temperature of 160 to 240 ° C for 1 to 3 h.

[0018] Method 2: A smooth substrate is pretreated, placed in a vacuum oven, and subjected to vapor deposition modification to obtain a solvent-philic substrate; the pretreatment is plasma treatment at 8 to 12 W for 1 to 2 min; the vapor deposition modification is to deposit the material of the first assembled monolayer film onto the substrate; the material of the first assembled monolayer film is phenyltrichlorosilane; the temperature of the vacuum oven is 120 to 180 ° C, and the temperature is kept constant for 0.5 to 2 hours.

[0019] Preferably, the solvent-repellent treatment process comprises: taking a smooth substrate and vapor-depositing a silane compound to obtain a solvent-repellent substrate; the silane compound is octadecyltrichlorosilane, and the amount thereof is 0.0001-1 mL / cm 2 The vapor deposition is carried out at 140-160°C at a speed of 0.001-0.2 nm / s, and the thickness of the vapor deposition layer is 1.8-50 nm.

[0020] Preferably, the solubilizer substrate in the scraping method can be a thin sheet with a smooth surface, good thermal conductivity and not easy to bend, and the material includes any one of metal, glass, silicon, and metal oxide. The material of the shearing tool includes any one of metal, glass, silicon, sapphire, etc., and the shearing tool can be any one of metal sheets, glass sheets, silicon wafers, sapphire sheets, etc.

[0021] Preferably, the substrate is glass and / or silicon wafer (SiO2 and / or Si wafer) and / or sapphire and gemstone analogs and / or p-xylene polymer (Parylene) and / or polydimethylsiloxane (PDMS).

[0022] Preferably, in step 3), the heating treatment heats the solvent-philic substrate and / or the organic semiconductor solution a and / or the organic semiconductor solution b and / or the mixed solution of the organic semiconductor solution a and the organic semiconductor solution b to 30-90°C. Preferably, the relative optimal temperature is 40-60°C.

[0023] Preferably, in step 3), the method of treating the stacked solvent-philic substrate and solvent-phobic substrate with the organic semiconductor solution a and the organic semiconductor solution b or a mixed solution of the two is a droplet fixed crystallization method or a doctor blade method.

[0024] The specific method of the droplet fixed crystallization method adopts any one of the following methods: Method A: Take organic semiconductor solution a and organic semiconductor solution b in proportion to obtain a mixed solution, heat the mixed solution and a solvent-philic substrate, place a solvent-phobic material on the solvent-philic substrate, and drip the mixed solution until it completely soaks the gap between the solvent-philic substrate and the solvent-phobic substrate, and obtain an organic semiconductor single crystal after the mixed solution evaporates.

[0025] Method B: Heat organic semiconductor solution a, organic semiconductor solution b, and a solvent-philic substrate, place a solvent-phobic material on the solvent-philic substrate, and drip organic semiconductor solution a and organic semiconductor solution b twice respectively, and then drip organic semiconductor solution b or organic semiconductor solution a for the second time after the organic semiconductor solution a or organic semiconductor solution b that was dripped first evaporates, and obtain an organic semiconductor single crystal after the solution evaporates.

[0026] Method C: Take organic semiconductor solution a and organic semiconductor solution b and prepare them in proportion to obtain a mixed solution, heat the mixed solution and a solvent-philic substrate, drop the mixed solution on the surface of the solvent-philic substrate, then place the solvent-phobic substrate on the solvent-philic substrate and cover it on the surface with the mixed solution added, and obtain an organic semiconductor single crystal after the mixed solution evaporates.

[0027] The scraping method specifically comprises the following steps: preparing an organic semiconductor solution a and an organic semiconductor solution b in proportion to obtain a mixed solution, heating the mixed solution until its viscosity is ≤100 mPa·s, heating the solvent-philic substrate and the solvent-phobic substrate at the same temperature so that the solvent-phobic substrate is suspended above the solvent-philic substrate, injecting the mixed solution between the solvent-philic substrate and the solvent-phobic substrate, scraping the mixed solution with the solvent-phobic substrate, and then evaporating the solution to obtain an organic semiconductor single crystal.

[0028] Preferably, the molar ratio of the organic semiconductor material A to the organic semiconductor material B contained in the organic semiconductor solution a and the organic semiconductor solution b used in step 3) is 1:(1-100).

[0029] Preferably, the distance between the solvent-repellent substrate and the solvent-philic substrate is controlled to be 50-300 μm during the scraping process; and the scraping rate is controlled to be 1-100 μm / s during the scraping process.

[0030] The organic semiconductor material A and the organic semiconductor material B used in the present invention can form Figure 1 Molecular assembly shown.

[0031] Thiophene derivatives are π-electron-rich heterocyclic compounds. As excellent optoelectronic material components and electron donor units, they are of great significance in two-photon absorption, fluorescence sensors, organic dyes, nonlinear optical crystal materials, etc. In the technical solution of the present invention, a large-area single-layer single-domain organic semiconductor single crystal is prepared based on condensed ring thiophene small molecule materials A and B with double-sided substituted alkyl chains and different alkyl chain lengths. With the periodically repeated alkyl side chain as the center, the growth of organic small molecule materials is induced, and a single crystal structure is formed through weak intermolecular forces. The sulfur atoms in thiophene have non-bonding electron pairs, which promote the formation of characteristic crystalline layers.

[0032] The length of the alkyl substituent in the condensed ring thiophene small molecule material will significantly affect the stacking morphology of the organic semiconductor, thereby significantly affecting the molecular stability, energy level, carrier transport performance and other aspects. Shorter alkyl chains are not conducive to the close arrangement of molecules to form ordered crystals. As the alkyl chain grows, when the number of carbon atoms exceeds 5, the crystal presents a highly ordered phase, and the resulting crystal not only has a high yield, but also has a large crystal domain size. The present invention performs TGA and DSC characterization on materials with different lengths of alkyl chains. After characterization, it is found that as the alkyl chain grows, the melting point gradually decreases. At the same time, the present invention prepares a plurality of organic semiconductor materials, and measures their maximum carrier mobility in the saturation region, average mobility in the saturation region and other properties, and finds that their parameters have a standard linear relationship, and the hysteresis curve overlaps highly, which indicates that there are few charge traps between the organic semiconductor layer and the substrate dielectric layer. As the alkyl chain grows, the carrier mobility of the material shows a trend of first increasing and then decreasing. In order to ensure that the material is a single crystal and has good thermal stability and a large carrier mobility, the present invention preferably has a carbon atom number n of 2 to 14. When the carbon atom number (C n When n) is 5 to 10, the organic semiconductor has high order in the horizontal direction of the substrate, the molecular stacking structure is very compact, and its carrier transport performance is the best.

[0033] Based on the condensed ring thiophene small molecule material with a carbon atom number n of 2 to 14, the present invention selects two materials with different alkyl chain lengths. The two organic semiconductor materials have different reaction activities and promote the growth of unit cells. In addition to the length of the alkyl chain directly affecting the self-assembly effect of the molecule, the amount of organic semiconductor and the concentration of the organic semiconductor solution also have a certain effect on the stacking morphology of the organic semiconductor. The molar mass of the organic semiconductor solution with a double-sided substituted long alkyl chain used in the present invention is usually less than the molar mass of the organic semiconductor solution with a double-sided substituted short alkyl chain, which ensures that the organic semiconductor has a larger area of ​​crystalline domains.

[0034] The substrate surface selected by the present invention has fewer nucleation points, and the modification effect of directly coating benzocyclobutene on its surface is poor. At the same time, the mixed solution that can form a monomolecular layer tends to bind to the substrate. The present invention enhances the affinity of the substrate to the mixed solution by treating the substrate with oxygen plasma, heat treating with inert gas, and modifying benzocyclobutene. Oxygen plasma can produce more hydroxyl groups on the surface of the silicon wafer, so that it has a high density of nucleation points, but too many hydroxyl groups will capture charges during carrier transport, which will reduce its mobility. Therefore, the present invention limits the conditions and time of oxygen plasma treatment. Benzocyclobutene (BCB) monomer has the thermodynamic stability of aromatic compounds and the kinetic reactivity of strained rings. After heating to 200 ° C, the four-membered ring opens and forms a highly active conjugated diene intermediate, which can not only undergo Diels-Alder addition reaction with dienophilic monomers, but also self-polymerize to form spirocyclic intermediates, thereby rearranging to form polymers and oligomers. No catalyst is required in this process, and no small molecule byproducts are produced. Too low a heat treatment temperature will result in the inability of benzocyclobutene to crosslink. The voids formed in the bonding layer seriously affect the heat transfer capacity of the benzocyclobutene layer. This hindering effect is affected by its thickness. At the same time, octadecyltrichlorosilane (OTS) used in the solvent-repellent material is used to reduce the affinity between the substrate and the mixed solution. The self-assembled monolayer obtained by spin coating is solvent-repellent and oil-permeable. The material modified with octadecyltrichlorosilane has extremely low surface energy, and the contact angle between the solvent molecule and the substrate increases, indicating that octadecyltrichlorosilane can effectively modify the material for solvent repellency.

[0035] The present invention regulates the molecular stacking structure of the single crystal by two materials, namely, solvent-philic and solvent-phobic, and plays an important role in improving the carrier mobility of the organic semiconductor single crystal. There is an intermolecular force between the solvent-philic group and the solvent-phobic group, which improves the growth rate of the crystal. At the same time, the side chain groups of thiophene in the single crystal are more inclined to be close to the active groups of the solvent-phobic material, inducing the molecules to be closely stacked along the a-axis of the unit cell, so that the crystal presents a flaky growth without grain boundaries on a macroscopic scale, rather than a dendritic growth containing a large number of grain boundaries and defects, which is conducive to the transmission of carriers and enables the material to show excellent performance.

[0036] As shown in the attached figure, the crystal surface is very smooth, the single-layer crystal is spread over a large area, the crystallinity is high, and the arrangement rules of different regions are the same, indicating that the organic semiconductor prepared by the present invention is a single crystal. After further characterization, it was found that due to the influence of the solvent-philic substrate, the single crystal nucleation points were significantly reduced, and the size of the formed organic semiconductor increased. The direction of the S atom in the thiophene ring has a relatively large influence on the electron transport performance, and random asymmetric molecules will significantly reduce the carrier mobility. Compared with the single-layer single-crystal domain organic semiconductor formed by a single solution, the area of ​​the organic semiconductor obtained by the present invention has increased by more than 2 times, and its single crystal domain area is at least greater than 4 mm 2 .

[0037] In addition, the present invention also provides two different forms of methods for final crystallization. Fig. 9 and Fig.10 As shown in Figure 2. Among them, the droplet fixed crystallization method is as follows Fig. 9 As shown in the schematic diagram, when crystallizing in this way, the single crystal molecules will form a regular accumulation at the edge of the solvent-repellent substrate, but due to the different stacking densities of the corresponding edge-corner interfaces, a new interface will be formed during the subsequent crystallization and crystallization process due to the uneven stacking density. This interface will cut the crystal domain, but because the stacking density of most edges is relatively balanced, the degree of cutting is low and a relatively large single crystal domain can still be effectively formed. The schematic diagram of the scraping method is as follows Fig.10 As shown in the figure, in this process, unlike the droplet fixed crystallization method, in the scraping method, the solvent-repellent substrate scrapes the mixed solution on the surface of the solvent-philic substrate. Due to the specificity of scraping, when scraping at a certain stable rate, it can effectively promote the contact between the solvent-repellent substrate and the solvent-philic substrate during the scraping process (macroscopic contact, with an actual minimum spacing of 50 to 300 μm). The single crystal molecules are evenly arranged and stacked due to the microscopic fluid dynamic effect and the affinity and repellency effect. In addition, the induced jet formed by the scraping liquid surface depression during the scraping process can promote the efficient rearrangement of the single crystal molecules in a short period of time. Compared with the droplet fixed crystallization method, the movement momentum of the single crystal molecules is larger, which is more conducive to the formation of effective regular rearrangement with the aid of the affinity and repellency effect. The arrangement and stacking process is carried out dynamically with the scraping process. In addition, the single crystal molecules that form regular and dense stacking first can promote the orderliness of the arrangement and stacking of the single crystal molecules that are stacked later, and the single crystal molecules formed later can strengthen the stability of the single crystal molecules that are stacked first, and they cooperate with each other to achieve the formation of a larger area of ​​single crystal domains.

[0038] The beneficial effects of the present invention are as follows: (1) The present invention uses a mixed solution of two organic semiconductors with double-sided substituted alkyl chains, which reduces the nucleation density, inhibits the tendency of multilayer growth of crystals, realizes the growth of large-area single-layer single crystal domains, and grows crystals in the air by a droplet fixed crystallization method, which is simple to operate and the growth process is relatively stable.

[0039] (2) The present invention prepares large-area single-layer single-domain organic single crystals, which is of great significance for studying their intrinsic properties, carrier transport characteristics, etc., and the method of the present invention is applicable to a variety of polycyclic thiophene organic semiconductor molecules.

[0040] (3) The present invention also provides two methods for forming organic semiconductor single crystals, wherein the droplet fixed crystallization method can efficiently and in batches realize the preparation of organic semiconductor single crystals, and although the efficiency of the scraping method is limited, it can more effectively prepare organic semiconductor single crystals with better all-round performance and larger crystal domain size. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 2,9-dihexylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C6-DNTT) and 2,9-didecylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C6-DNTT) in Examples 1 to 3 10 Schematic diagram of the composition structure of a single crystal grown by mixing two organic semiconductors (-DNTT).

[0042] Figure 2 This is an optical microscope photograph of the organic semiconductor single crystal with a large area single layer single crystal domain prepared in Example 1.

[0043] Figure 3 This is a polarizing microscope photograph of the organic semiconductor single crystal with a large area single layer single crystal domain prepared in Example 1.

[0044] Figure 4 This is an optical microscope photograph of the organic semiconductor single crystal with a large area single layer single crystal domain prepared in Example 2.

[0045] Figure 5 This is a polarizing microscope photograph of the organic semiconductor single crystal with a large area single layer single crystal domain prepared in Example 2.

[0046] Figure 6 This is an optical microscope photograph of the organic semiconductor single crystal with a large area single layer single crystal domain prepared in Example 3.

[0047] Figure 7 This is a polarizing microscope photograph of the organic semiconductor single crystal with a large area single layer single crystal domain prepared in Example 3.

[0048] Figure 8 It is a partial polarizing microscope photograph of the location of the largest single-domain crystal grown from the mixed organic semiconductor solution in Comparative Example 1 and Examples 1 to 3.

[0049] Fig. 9 Schematic diagram of droplet pinning crystallization (DPC).

[0050] Fig.10 Schematic diagram of blade-coating.

[0051] Fig.11 This is a polarizing microscope photograph of the organic semiconductor single crystal with a large area single layer and single crystal domain prepared in Example 4. DETAILED DESCRIPTION

[0052] The present invention is further described in detail below in conjunction with specific embodiments and the accompanying drawings. A person of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0053] Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art.

[0054] Example 1: A method for preparing a large-area single-layer single-domain organic semiconductor single crystal, the method comprising: 1) preparing organic semiconductor solution a and organic semiconductor solution b: taking 5 mg of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 5 mg of 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and respectively dissolving them in tetralin to prepare organic semiconductor solution a with a concentration of 0.05 mg / mL and organic semiconductor solution b with a concentration of 0.05 mg / mL.

[0055] 2) Prepare solvent-friendly substrate: Take an area of ​​10 cm 2 The smooth SiO2 sheet was treated with oxygen plasma at 10 W for 2 min, placed in a closed space of a N2 glove box, and N2 was introduced. Benzocyclobutene was spin-coated on the substrate with a thickness of 100 nm. The substrate was kept at 200 °C for 2 h to obtain a solvent-philic substrate.

[0056] 3) Preparation of solvent-repellent material: Take another area of ​​5 cm 2 , a smooth silicon wafer, 0.000635 mL of octadecyltrichlorosilane, at 160 °C, the deposition was carried out at a speed of 0.001 nm / s for 1800 s, and the thickness of the evaporated layer was 1.8 nm to obtain a solvent-repellent material.

[0057] 4) Further, organic semiconductor single crystals are formed according to the following three methods respectively: Method A: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained is 1:3.28 to obtain a mixed solution, take a solvent-philic substrate and the mixed solution and heat it to 43°C, place a solvent-phobic material on the solvent-philic substrate, and drip the mixed solution on the surface of the solvent-philic substrate until the solvent-philic substrate and the solvent-phobic material are completely covered, and after the mixed solution evaporates, an organic semiconductor single crystal m is obtained.

[0058] Method B: Take organic semiconductor solution a, organic semiconductor solution b, and a solvent-philic substrate and heat them to 43°C, place a solvent-phobic material on the solvent-philic substrate, drip the same amount of organic semiconductor solution a as used in method A on its surface, and after the solution evaporates, drip the same amount of organic semiconductor solution b as used in method A on the surface of the substrate, and after the solution evaporates, obtain an organic semiconductor single crystal n.

[0059] Method C: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:3.28 to prepare a mixed solution, take a solvent-philic substrate and the mixed solution and heat it to 43°C, add the same amount of mixed solution as that of method A dropwise on the surface of the solvent-philic substrate until the solvent-philic substrate is completely covered, place a solvent-phobic material on the solvent-philic substrate, and after the mixed solution evaporates, obtain an organic semiconductor single crystal o.

[0060] Among them, the optical microscope photo of the organic semiconductor single crystal m prepared by method A is as follows Figure 2 As shown in the polarizing microscope photo Figure 3 As shown. Figure 2 and Figure 3 It can be seen that the method of the present invention is very effective in preparing large-sized single-layer semiconductor single crystals.

[0061] The performance of the organic semiconductor single crystal obtained in this example was tested in the following manner.

[0062] 1. Carrier migration rate: At room temperature and in the dark, the carrier transport performance of the OTFT device was measured using a Keysight B1500A and a probe station with a scan step of 1 V / s to characterize the carrier migration rate on the organic semiconductor single crystal.

[0063] 2. Hardness test: The hardness of the single crystal is measured by nanoindentation technology. The indentation interval size is 50 μm and the indentation depth is 1 μm. After nanoindentation measurement, the nanohardness value of the material is obtained.

[0064] 3. Crystal domain size: By characterizing the grains of a single crystal, the average crystal domain size is calculated according to the Scherrer formula.

[0065] 4. Thermal stability: Heat the organic semiconductor single crystal to 240 °C and characterize the defects of the organic semiconductor single crystal again. If there is no obvious change, it is recorded as "√", otherwise it is recorded as "×".

[0066] The results are as follows.

[0067]

[0068] According to the results in the table, it can be seen that the three methods for preparing organic semiconductor single crystals provided by the present invention can effectively suppress the trend of multilayer growth of crystals, increase the size of crystal domains, and prepare single crystals with good flexibility and thermal stability. The method A provided by the present invention can better promote the migration of carriers on organic semiconductor single crystals, and because the long chain entanglement of the two is delayed by dripping the organic semiconductor solution separately, the crystal domain size of the organic semiconductor single crystal n prepared by method B is relatively small. The operation of method C, which first drips the mixed solution and then covers the solvent-repellent material, also has a great influence on the morphology of the single crystal. The growth rate of the single crystal is slow, and the side chain groups of thiophene in the single crystal are not induced by the active groups of the solvent-repellent material, showing a more chaotic stacking, and the crystal forms a disc-shaped growth, but there are local void defects. Therefore, compared with method A, the carrier transfer rate of the single crystal prepared by method C is lower.

[0069] Example 2: A method for preparing a large-area single-layer single-domain organic semiconductor single crystal, the method comprising: 1) preparing an organic semiconductor solution a and an organic semiconductor solution b: taking 5 mg of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 5 mg of 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and respectively dissolving them in tetralin to prepare an organic semiconductor solution a with a concentration of 0.01 mg / mL and an organic semiconductor solution b with a concentration of 0.04 mg / mL.

[0070] 2) Preparation of solvent-philic substrate: Take a smooth SiO2 sheet with an area of ​​10 cm2, treat it with oxygen plasma at 10 W for 2 min, place it in the closed space of a N2 glove box, introduce N2, spin-coat benzocyclobutene on the substrate with a spin coating thickness of 100 nm, and keep it at 200 °C for 2 h to obtain a solvent-philic substrate.

[0071] 3) Preparation of solvent-repellent material: Take another smooth silicon wafer with an area of ​​5 cm2 and 0.000635 mL of octadecyltrichlorosilane, and deposit it at 160 °C at a speed of 0.001 nm / s for 1800 s. The thickness of the evaporated layer is 1.8 nm to obtain a solvent-repellent material.

[0072] 4) Further, organic semiconductor single crystals are formed according to the following three methods respectively: Method A: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and the mixed solution and heat it to 43°C, place a solvent-phobic material on the solvent-philic substrate, and drip the mixed solution on the surface of the solvent-philic substrate until the solvent-philic substrate and the solvent-phobic material are completely covered, and after the mixed solution evaporates, an organic semiconductor single crystal m is obtained.

[0073] Method B: Take organic semiconductor solution a, organic semiconductor solution b, and a solvent-philic substrate and heat them to 43°C, place a solvent-phobic material on the solvent-philic substrate, drip the same amount of organic semiconductor solution a as used in method A on its surface, and after the solution evaporates, drip the same amount of organic semiconductor solution b as used in method A on the surface of the substrate, and after the solution evaporates, obtain an organic semiconductor single crystal n.

[0074] Method C: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and heat the mixed solution to 43°C, add the same amount of mixed solution as in method A dropwise on the surface of the solvent-philic substrate until the solvent-philic substrate is completely covered, place a solvent-phobic material on the solvent-philic substrate, and after the mixed solution evaporates, obtain an organic semiconductor single crystal o.

[0075] Among them, the optical microscope photo of the organic semiconductor single crystal m prepared by method A is as follows Figure 4 As shown in the polarizing microscope photo Figure 5 As shown. Figure 4 and Figure 5 It can be seen that the method of the present invention is very effective in preparing large-sized single-layer semiconductor single crystals.

[0076] The organic semiconductor single crystal obtained in this example was subjected to the same performance test as in Example 1, and the test results are as follows.

[0077]

[0078] In this example, the molar mass of the organic semiconductor solution with a double-sided substituted long alkyl chain is much lower than that of the organic semiconductor solution with a double-sided substituted short alkyl chain. According to the results in the table, the obtained organic semiconductors all have a larger crystal domain area. In addition, compared with Example 1, the carrier migration rate is improved.

[0079] Example 3: A method for preparing a large-area single-layer single-domain organic semiconductor single crystal, the method comprising: 1) preparing organic semiconductor solution a and organic semiconductor solution b: taking 5 mg of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 5 mg of 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and respectively dissolving them in tetralin to prepare organic semiconductor solution a with a concentration of 0.05 mg / mL and organic semiconductor solution b with a concentration of 0.05 mg / mL.

[0080] 2) Preparation of solvent-philic substrate: Take a smooth SiO2 sheet with an area of ​​10 cm2, treat it with oxygen plasma at 10 W for 2 min, place it in the closed space of a N2 glove box, introduce N2, spin-coat benzocyclobutene on the substrate with a spin coating thickness of 100 nm, and keep it at 200 °C for 2 h to obtain a solvent-philic substrate.

[0081] 3) Preparation of solvent-repellent material: Take another area of ​​5 cm 2 , a smooth silicon wafer, 0.000635 mL of octadecyltrichlorosilane, at 160 °C, the deposition was carried out at a speed of 0.001 nm / s for 1800 s, and the thickness of the evaporated layer was 1.8 nm to obtain a solvent-repellent material.

[0082] 4) Further, organic semiconductor single crystals are formed according to the following three methods respectively: Method A: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:1.83 to obtain a mixed solution, take a solvent-philic substrate and the mixed solution and heat it to 43°C, place a solvent-phobic material on the solvent-philic substrate, and drip the mixed solution on the surface of the solvent-philic substrate until the solvent-philic substrate and the solvent-phobic material are completely covered, and after the mixed solution evaporates, an organic semiconductor single crystal m is obtained.

[0083] Method B: Take organic semiconductor solution a, organic semiconductor solution b, and a solvent-philic substrate and heat them to 43°C, place a solvent-phobic material on the solvent-philic substrate, drip the same amount of organic semiconductor solution a as used in method A on its surface, and after the solution evaporates, drip the same amount of organic semiconductor solution b as used in method A on the surface of the substrate, and after the solution evaporates, obtain an organic semiconductor single crystal n.

[0084] Method C: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:1.83 to obtain a mixed solution, take a solvent-philic substrate and the mixed solution and heat it to 43°C, add the same amount of mixed solution as that of method A on the surface of the solvent-philic substrate until the solvent-philic substrate is completely covered, place a solvent-phobic material on the solvent-philic substrate, and after the mixed solution evaporates, obtain an organic semiconductor single crystal o.

[0085] Among them, the optical microscope photo of the organic semiconductor single crystal m prepared by method A is as follows Figure 6 As shown in the polarizing microscope photo Figure 7 As shown. Figure 6 and Figure 7 It can be seen that the method of the present invention is very effective in preparing large-sized single-layer semiconductor single crystals.

[0086] The organic semiconductor single crystal obtained in this example was subjected to the same performance test as in Example 1, and the test results are as follows.

[0087]

[0088] Compared with Example 1, the amount of organic semiconductor solutions with different alkyl chain lengths in this example is changed, but since the difference in reactivity between the solutions in this example is reduced, the self-assembly effect of the molecules is affected. Compared with Example 2, the material in this example exhibits a low carrier migration rate and a small crystal domain size.

[0089] According to the results in the tables of Examples 1 to 3, any one of the methods for preparing organic semiconductor single crystals provided by the present invention can effectively improve the material carrier migration rate and increase the crystal domain size, and the prepared large-area single-layer single crystal domain area is greater than 4 mm 2 It can be seen that the amount of organic semiconductor and the concentration of organic semiconductor solution will have a certain impact on the stacking morphology of organic semiconductor, thereby affecting its crystal domain size, carrier transport performance, etc. And when the number of carbon atoms (C nWhen n) is 6 to 10, the organic semiconductor has high order in the horizontal direction of the substrate, the molecular stacking structure is very tight, its carrier transport performance is the best, and the single crystal has good thermal stability. In addition, in additional orthogonal experiments, the concentration of organic semiconductor material A in organic semiconductor solution a and the concentration of organic semiconductor material B in organic semiconductor solution b are both controlled in a relatively low range of 0.05 to 0.8 mg / mL, both of which can produce better preparation effects. When the concentration is too low, the crystallization will be uneven or even impossible to form, while when the concentration is too high, there will be a tendency to grow multi-layer semiconductor crystals, and the formation of interlayer effects will cause the organic semiconductor crystal domains to be significantly reduced. For example, under the preparation conditions of method A in Example 1, when the concentration of organic semiconductor material A in organic semiconductor solution a and the concentration of organic semiconductor material B in organic semiconductor solution b both reach 0.95 mg / mL, the maximum crystal domain size A max It suddenly dropped to about 3.96 mm 2 , and the average crystal domain size is only about 3.81 mm 2 It can be seen that the concentration of organic semiconductor material A in organic semiconductor solution a and the concentration of organic semiconductor material B in organic semiconductor solution b will also affect the crystallization effect to a certain extent.

[0090] Example 4: A method for preparing a large-area single-layer single-domain organic semiconductor single crystal, the method comprising: 1) preparing an organic semiconductor solution a and an organic semiconductor solution b: taking 5 mg of 2,9-dipentylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 5 mg of 2,9-dinonylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and respectively dissolving them in tetralin to prepare an organic semiconductor solution a with a concentration of 0.12 mg / mL and an organic semiconductor solution b with a concentration of 0.12 mg / mL.

[0091] 2) Prepare solvent-friendly substrate: Take an area of ​​10 cm 2 The smooth SiO2 sheet was treated with oxygen plasma at 10 W for 2 min, placed in a closed space of an oven, evacuated, and modified by vapor deposition using phenyltrichlorosilane (PTS). The solvent-philic substrate was obtained by constant temperature at 150 °C for 1 h.

[0092] 3) Preparation of solvent-repellent material: Take another area of ​​5 cm 2 , a smooth silicon wafer, 0.000635 mL of octadecyltrichlorosilane, at 160 °C, the deposition was carried out at a speed of 0.001 nm / s for 1800 s, and the deposition layer thickness was 1.8 nm to obtain a solvent-repellent material.

[0093] 4) Further, an organic semiconductor single crystal is prepared by a scraping method: an organic semiconductor solution a and an organic semiconductor solution b are taken and the amounts thereof are controlled so that the molar ratio of 2,9-dipentylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dinonylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene is 11.1:1 to prepare a mixed solution, the mixed solution is heated to 65°C (satisfying that the viscosity of the mixed solution is ≤100 mPa·s), the solvent-philic substrate and the solvent-phobic substrate are preheated to 65°C so that the solvent-phobic substrate is suspended above the solvent-philic substrate, the mixed solution is injected between the solvent-philic substrate and the solvent-phobic substrate, and the mixed solution is scraped with the solvent-phobic substrate, the distance between the solvent-phobic substrate and the solvent-philic substrate is controlled to be 120 μm during the scraping process, and the scraping rate is controlled to be 2.2 μm / s, and then the solution is evaporated to obtain an organic semiconductor single crystal.

[0094] The organic semiconductor single crystal obtained in this example was subjected to the same performance test as in Example 1, and the test results are as follows.

[0095]

[0096] In addition, the organic semiconductor single crystal prepared in this example was characterized by polarizing microscope, and the characterization results are as follows: Fig.11 As shown, it can form extremely large and regular ultra-large organic semiconductor single crystal domains, and its maximum single crystal domain area A max =41.18 mm 2 In addition, the obtained organic semiconductor single crystal has a higher carrier migration rate and a lower coefficient of variation, so that the obtained organic semiconductor single crystal has better performance in all aspects. Compared with Examples 1 to 3, it can be seen that compared with the droplet fixed crystallization method, this embodiment can obviously construct a better organic semiconductor single crystal, but compared with the droplet fixed crystallization method, the preparation efficiency is obviously lower. Therefore, from the perspective of industrialization, the droplet fixed crystallization method and the scraping method each have their own advantages. The droplet fixed crystallization method is suitable for batch, rapid and large-scale preparation of organic semiconductor single crystals with larger crystal domain sizes, while the scraping method can be used for refined preparation, and the preparation of organic semiconductor single crystals with ultra-large crystal domain sizes has better performance in all aspects.

[0097] Comparative Example 1: A method for preparing a large-area single-layer single-domain organic semiconductor single crystal, the method comprising: 1) preparing an organic semiconductor solution: taking 5 mg of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C10-DNTT) and dissolving it in tetralin to prepare an organic semiconductor solution with a concentration of 0.01 mg / mL.

[0098] 2) Prepare solvent-friendly substrate: Take an area of ​​10 cm 2 The smooth SiO2 sheet was treated with oxygen plasma at 10 W for 2 min, placed in a closed space of a N2 glove box, and N2 was introduced. Benzocyclobutene was spin-coated on the substrate with a thickness of 100 nm. The substrate was kept at 200 °C for 2 h to obtain a solvent-philic substrate.

[0099] 3) Preparation of solvent-repellent material: Take another area of ​​5 cm 2 , a smooth silicon wafer, 0.000635 mL of octadecyltrichlorosilane, at 160 °C, the deposition was carried out at a speed of 0.001 nm / s for 1800 s, and the thickness of the evaporated layer was 1.8 nm to obtain a solvent-repellent material.

[0100] 4) Further, organic semiconductor single crystals are formed according to the following two methods respectively: Method A: Take a solvent-philic substrate and an organic semiconductor solution and heat it to 43°C, place a solvent-phobic material on the solvent-philic substrate, and drip the mixed solution on the surface until the solvent-philic substrate and the solvent-phobic material are completely covered, and after the mixed solution evaporates, an organic semiconductor single crystal m is obtained.

[0101] Method C: Take a solvent-philic substrate and an organic semiconductor solution and heat it to 43°C. Add the same amount of mixed solution as used in method A onto the surface of the solvent-philic substrate until the solvent-philic substrate is completely covered. Place the solvent-phobic material on the solvent-philic substrate. After the mixed solution evaporates, an organic semiconductor single crystal is obtained.

[0102] The organic semiconductor single crystal obtained in this example was subjected to the same performance test as in Example 1, and the test results are as follows.

[0103]

[0104] According to the results in the table, the organic semiconductor single crystal in this example exhibits extremely poor carrier transport performance, thermal stability and extremely small crystal domain size. The crystal domain area of ​​the organic semiconductor single crystal prepared by any of the preparation methods provided in the embodiment is nearly 3 times the crystal domain area of ​​the organic semiconductor single crystal prepared by a single organic semiconductor solution. The crystal domain area of ​​the material in this example is too small, which is greatly limited in the application of large-scale devices, such as uneven panel brightness and larger numerical errors of digital circuits.

[0105] At the same time, the order of solvent-repellent material coverage will have a great influence on the growth direction of the crystal. The single crystal m obtained by method A has regular crystallization and grows in a large scale along a certain direction, while the single crystal o obtained by method C has local lateral and longitudinal expansion growth, its crystallization quality is reduced, more crystal defects are formed, the crystal orientation is disordered, and the morphology and thickness are uneven, so it shows relatively poor carrier migration rate and thermal stability.

[0106] Based on the above experiments, only 2,9-didecylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C 10 -DNTT) was replaced with 2,9-dihexylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C6-DNTT) and the same preparation was performed, but the performance was also poor, with the largest single crystal domain area being only 1.49 cm 2 The largest single crystal of the prepared organic semiconductor single crystal was characterized by polarizing microscope and compared with Examples 1 to 3. The comparison diagram is as follows: Figure 8 As shown, Figure 8 Each crystal photo is 6 mm × 5 mm, with a total area of ​​30 mm 2 , and the largest single crystal domain area in each figure is recorded as A max , Figure 8 (a) is a partial polarizing microscope photograph of the largest single crystal domain crystal grown only with 2,9-dihexylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C6-DNTT) in Comparative Example 1. max =1.49 mm 2 , Figure 8 (b) is the compound in Comparative Example 1 containing only 2,9-didecylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C 10 A partial polarizing microscope photo of the largest single-domain crystal grown by the A-DNTT max =2.10 mm 2 , Figure 8 (c) is a partial polarizing microscope photograph of the largest single-domain crystal grown during the preparation process of Example 1. max =7.57 mm 2 , Figure 8 (d) is a partial polarizing microscope photograph of the largest single-domain crystal grown during the preparation process of Example 2. max =5.95 mm 2 , Figure 8 (e) is a partial polarizing microscope photograph of the largest single-domain crystal grown during the preparation process of Example 3. max =4.43 mm 2 ,from Figure 8 It can be seen that there are huge differences in the preparation effects, and the single crystal area has a significant difference.

[0107] Comparative Example 2: A method for preparing a large-area single-layer single-domain organic semiconductor single crystal, the method comprising: 1) preparing an organic semiconductor solution a and an organic semiconductor solution b: taking 5 mg of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 5 mg of 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and respectively dissolving them in tetralin to prepare an organic semiconductor solution a with a concentration of 0.01 mg / mL and an organic semiconductor solution b with a concentration of 0.04 mg / mL.

[0108] 2) Prepare solvent-friendly substrate: Take an area of ​​10 cm 2 The triazine polycarboxylic acid sheet was treated with oxygen plasma at 10 W for 2 min, placed in a closed space of a N2 glove box, introduced N2, and spin-coated benzocyclobutene with a thickness of 100 nm on the substrate. The substrate was kept at 200 °C for 2 h to obtain a solvent-philic substrate.

[0109] 3) Preparation of solvent-repellent material: Take another area of ​​5 cm 2 triazine polycarboxylic acid sheet and 0.000635 mL of octadecyltrichlorosilane were deposited at 160 °C at a rate of 0.001 nm / s for 1800 s, and the thickness of the evaporated layer was 1.8 nm to obtain a solvent-repellent material.

[0110] 4) Further, organic semiconductor single crystals are formed according to the following three methods respectively: Method A: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and the mixed solution and heat it to 43°C, place a solvent-phobic material on the solvent-philic substrate, and drip the mixed solution on the surface of the solvent-philic substrate until the solvent-philic substrate and the solvent-phobic material are completely covered, and after the mixed solution evaporates, an organic semiconductor single crystal m is obtained.

[0111] Method B: Take organic semiconductor solution a, organic semiconductor solution b, and a solvent-philic substrate and heat them to 43°C, place a solvent-phobic material on the solvent-philic substrate, drip the same amount of organic semiconductor solution a as used in method A on its surface, and after the solution evaporates, drip the same amount of organic semiconductor solution b as used in method A on the surface of the substrate, and after the solution evaporates, obtain an organic semiconductor single crystal n.

[0112] Method C: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and heat the mixed solution to 43°C, add the same amount of mixed solution as in method A dropwise on the surface of the solvent-philic substrate until the solvent-philic substrate is completely covered, place a solvent-phobic material on the solvent-philic substrate, and after the mixed solution evaporates, obtain an organic semiconductor single crystal o.

[0113] The organic semiconductor single crystal obtained in this example was subjected to the same performance test as in Example 1, and the test results are as follows.

[0114]

[0115] The surface roughness of the substrate used in this example is relatively large. After characterization, it was found that the prepared organic semiconductor single crystal showed dendritic growth, large surface roughness of the single crystal, uneven thickness, secondary nucleation, and crystals in different directions, that is, local polycrystalline. This structure contains a large number of grain boundaries and defects, which is not conducive to carrier transport. The material in this example showed extremely poor carrier migration rate and thermal stability.

[0116] Comparative Example 3: A method for preparing a large-area single-layer single-domain organic semiconductor single crystal, the method comprising: 1) preparing an organic semiconductor solution a and an organic semiconductor solution b: taking 5 mg of 2,9-didecylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 5 mg of 2,9-dihexylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and respectively dissolving them in N,N-dimethylformamide to prepare an organic semiconductor solution a with a concentration of 0.01 mg / mL and an organic semiconductor solution b with a concentration of 0.04 mg / mL.

[0117] 2) Prepare solvent-friendly substrate: Take an area of ​​10 cm 2 The smooth SiO2 sheet was treated with oxygen plasma at 10 W for 2 min, placed in a closed space of a N2 glove box, and N2 was introduced. Benzocyclobutene was spin-coated on the substrate with a thickness of 100 nm. The substrate was kept at 200 °C for 2 h to obtain a solvent-philic substrate.

[0118] 3) Preparation of solvent-repellent material: Take another area of ​​5 cm 2 , a smooth silicon wafer, 0.000635 mL of octadecyltrichlorosilane, at 160 °C, the deposition was carried out at a speed of 0.001 nm / s for 1800 s, and the thickness of the evaporated layer was 1.8 nm to obtain a solvent-repellent material.

[0119] 4) Further, organic semiconductor single crystals are formed according to the following three methods respectively: Method A: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and the mixed solution and heat it to 43°C, place a solvent-phobic material on the solvent-philic substrate, and drip the mixed solution on the surface of the solvent-philic substrate until the solvent-philic substrate and the solvent-phobic material are completely covered, and after the mixed solution evaporates, an organic semiconductor single crystal m is obtained.

[0120] Method B: Take organic semiconductor solution a, organic semiconductor solution b, and a solvent-philic substrate and heat them to 43°C, place a solvent-phobic material on the solvent-philic substrate, drip the same amount of organic semiconductor solution a as used in method A on its surface, and after the solution evaporates, drip the same amount of organic semiconductor solution b as used in method A on the surface of the substrate, and after the solution evaporates, obtain an organic semiconductor single crystal n.

[0121] Method C: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and heat the mixed solution to 43°C, add the same amount of mixed solution as in method A dropwise on the surface of the solvent-philic substrate until the solvent-philic substrate is completely covered, place a solvent-phobic material on the solvent-philic substrate, and after the mixed solution evaporates, obtain an organic semiconductor single crystal o.

[0122] The organic semiconductor single crystals obtained in Example 2 and this example were subjected to the same tests and crystallinity characterization as in Example 1. The test results and characterization results are as follows.

[0123]

[0124] The crystallinity of the organic semiconductor single crystal prepared in this example is much lower than that of the single crystal obtained in Example 2. The reason is that N,N-dimethylformamide easily causes the single crystal to accumulate in a strip-like manner. Although the single crystal domain size is large, the local thickness of the crystal is not conducive to the injection and transmission of carriers, resulting in a low carrier mobility.

[0125] Comparative Example 4: A method for preparing a large-area single-layer single-domain organic semiconductor single crystal, the method comprising: 1) preparing an organic semiconductor solution a and an organic semiconductor solution b: taking 5 mg of 2,9-dipentylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 5 mg of 2,9-dimethylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and respectively dissolving them in tetralin to prepare an organic semiconductor solution a with a concentration of 0.01 mg / mL and an organic semiconductor solution b with a concentration of 0.04 mg / mL.

[0126] 2) Prepare solvent-friendly substrate: Take an area of ​​10 cm 2 The smooth SiO2 sheet was treated with oxygen plasma at 10 W for 2 min, placed in a closed space of a N2 glove box, and N2 was introduced. Benzocyclobutene was spin-coated on the substrate with a thickness of 100 nm. The substrate was kept at 200 °C for 2 h to obtain a solvent-philic substrate.

[0127] 3) Preparation of solvent-repellent material: Take another area of ​​5 cm 2 , a smooth silicon wafer, 0.000635 mL of octadecyltrichlorosilane, at 160 °C, the deposition was carried out at a speed of 0.001 nm / s for 1800 s, and the thickness of the evaporated layer was 1.8 nm to obtain a solvent-repellent material.

[0128] 4) Further, organic semiconductor single crystals are formed according to the following three methods respectively: Method A: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-dipentylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dimethylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and the mixed solution and heat it to 43°C, place a solvent-phobic material on the solvent-philic substrate, and drip the mixed solution on the surface of the solvent-philic substrate until the solvent-philic substrate and the solvent-phobic material are completely covered, and after the mixed solution evaporates, an organic semiconductor single crystal m is obtained.

[0129] Method B: Take organic semiconductor solution a, organic semiconductor solution b, and a solvent-philic substrate and heat them to 43°C, place a solvent-phobic material on the solvent-philic substrate, drip the same amount of organic semiconductor solution a as used in method A on its surface, and after the solution evaporates, drip the same amount of organic semiconductor solution b as used in method A on the surface of the substrate, and after the solution evaporates, obtain an organic semiconductor single crystal n.

[0130] Method C: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-dipentylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dimethylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and heat the mixed solution to 43°C, add the same amount of mixed solution as in method A dropwise on the surface of the solvent-philic substrate until the solvent-philic substrate is completely covered, place a solvent-phobic material on the solvent-philic substrate, and after the mixed solution evaporates, obtain an organic semiconductor single crystal o.

[0131] The organic semiconductor single crystal obtained in this example was subjected to the same performance test as in Example 1, and the test results are as follows.

[0132]

[0133] In this example, the alkyl substituent is relatively short, which significantly affects the stacking morphology of the organic semiconductor, thereby significantly affecting the molecular energy level, carrier transport performance, etc. The shorter carrier transport channel causes a low carrier migration rate. And compared with Example 2, the single crystal yield of this example is relatively low and the crystal domain size is relatively small. In more experiments, it is shown that the number of alkyl carbon atoms (C n The performance is better when the number of n is controlled between 3 and 12.

[0134] Comparative Example 5: A method for preparing a large-area single-layer single-domain organic semiconductor single crystal, the method comprising: 1) preparing an organic semiconductor solution a and an organic semiconductor solution b: taking 5 mg of 2,9-didecylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 5 mg of 2,9-dihexylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and respectively dissolving them in tetralin to prepare an organic semiconductor solution a with a concentration of 0.01 mg / mL and an organic semiconductor solution b with a concentration of 0.04 mg / mL.

[0135] 2) Preparation of solvent-philic substrate: Take a smooth SiO2 sheet with an area of ​​10 cm2, treat it with oxygen plasma at 10 W for 3 min, place it in the closed space of a N2 glove box, introduce N2, spin-coat benzocyclobutene on the substrate with a spin coating thickness of 100 nm, and keep it at 200 °C for 2 h to obtain a solvent-philic substrate.

[0136] 3) Preparation of solvent-repellent material: Take another area of ​​5 cm 2, a smooth silicon wafer, 0.000635 mL of octadecyltrichlorosilane, at 160 °C, the deposition was carried out at a speed of 0.001 nm / s for 1800 s, and the thickness of the evaporated layer was 1.8 nm to obtain a solvent-repellent material.

[0137] 4) Further, organic semiconductor single crystals are formed according to the following three methods respectively: Method A: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and the mixed solution and heat it to 43°C, place a solvent-phobic material on the solvent-philic substrate, and drip the mixed solution on the surface of the solvent-philic substrate until the solvent-philic substrate and the solvent-phobic material are completely covered, and after the mixed solution evaporates, an organic semiconductor single crystal m is obtained.

[0138] Method B: Take organic semiconductor solution a, organic semiconductor solution b, and a solvent-philic substrate and heat them to 43°C, place a solvent-phobic material on the solvent-philic substrate, drip the same amount of organic semiconductor solution a as used in method A on its surface, and after the solution evaporates, drip the same amount of organic semiconductor solution b as used in method A on the surface of the substrate, and after the solution evaporates, obtain an organic semiconductor single crystal n.

[0139] Method C: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and heat the mixed solution to 43°C, add the same amount of mixed solution as in method A dropwise on the surface of the solvent-philic substrate until the solvent-philic substrate is completely covered, place a solvent-phobic material on the solvent-philic substrate, and after the mixed solution evaporates, obtain an organic semiconductor single crystal o.

[0140] The organic semiconductor single crystal obtained in this example was subjected to the same performance test as in Example 1, and the test results are as follows.

[0141]

[0142] In this case, a large number of hydroxyl groups are generated on the surface of the silicon wafer, and its surface has a high density of nucleation points. Although the modification effect of the material surface is obvious, the substrate has good affinity for the mixed solution and exhibits better hydrophilicity, a large number of hydroxyl groups will capture charges during the carrier transport process, resulting in low carrier mobility.

[0143] Comparative Example 6: A method for preparing a large-area single-layer single-domain organic semiconductor single crystal, the method comprising: 1) preparing an organic semiconductor solution a and an organic semiconductor solution b: taking 5 mg of 2,9-didecylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 5 mg of 2,9-dihexylbisnaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and respectively dissolving them in tetralin to prepare an organic semiconductor solution a with a concentration of 0.01 mg / mL and an organic semiconductor solution b with a concentration of 0.04 mg / mL.

[0144] 2) Prepare solvent-friendly substrate: Take an area of ​​10 cm 2 The smooth SiO2 sheet was treated with oxygen plasma at 10 W for 2 min, placed in a closed space of a N2 glove box, and N2 was introduced. Benzocyclobutene was spin-coated on the substrate with a thickness of 100 nm. The substrate was kept at 190 °C for 2 h to obtain a solvent-philic substrate.

[0145] 3) Preparation of solvent-repellent material: Take another area of ​​5 cm 2 , a smooth silicon wafer, 0.000635 mL of octadecyltrichlorosilane, at 160 °C, the deposition was carried out at a speed of 0.001 nm / s for 1800 s, and the thickness of the evaporated layer was 1.8 nm to obtain a solvent-repellent material.

[0146] 4) Further, organic semiconductor single crystals are formed according to the following three methods respectively: Method A: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and the mixed solution and heat it to 43°C, place a solvent-phobic material on the solvent-philic substrate, and drip the mixed solution on the surface of the solvent-philic substrate until the solvent-philic substrate and the solvent-phobic material are completely covered, and after the mixed solution evaporates, an organic semiconductor single crystal m is obtained.

[0147] Method B: Take organic semiconductor solution a, organic semiconductor solution b, and a solvent-philic substrate and heat them to 43°C, place a solvent-phobic material on the solvent-philic substrate, drip the same amount of organic semiconductor solution a as used in method A on its surface, and after the solution evaporates, drip the same amount of organic semiconductor solution b as used in method A on the surface of the substrate, and after the solution evaporates, obtain an organic semiconductor single crystal n.

[0148] Method C: Take organic semiconductor solution a and organic semiconductor solution b and control the dosage so that the molar ratio of 2,9-didecylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and 2,9-dihexylbinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene contained therein is 1:13.11 to obtain a mixed solution, take a solvent-philic substrate and heat the mixed solution to 43°C, add the same amount of mixed solution as in method A dropwise on the surface of the solvent-philic substrate until the solvent-philic substrate is completely covered, place a solvent-phobic material on the solvent-philic substrate, and after the mixed solution evaporates, obtain an organic semiconductor single crystal o.

[0149] The organic semiconductor single crystal obtained in this example was subjected to the same performance test as in Example 1, and the test results are as follows.

[0150]

[0151] At 190 °C, the benzocyclobutene in this example did not form a highly active conjugated diene intermediate, resulting in poor bonding to the substrate. Low heat treatment temperature will cause the benzocyclobutene to be unable to cross-link, and the voids formed in the bonding layer seriously affect the heat transfer capacity of the benzocyclobutene layer, and this hindering effect is affected by its thickness. In this example, the single crystal nucleation points on the surface of the solvent-philic substrate are significantly reduced, and the size of the formed organic semiconductor is large, but the direction of the S atom in the thiophene ring has a greater influence on the electron transport performance, and the random asymmetric molecules will significantly reduce the carrier mobility.

Claims

1. A method for preparing a large-area single-layer single-crystal domain organic semiconductor single crystal, characterized in that: The method comprises: 1) dissolving an organic semiconductor material A and an organic semiconductor material B in an organic solvent to prepare an organic semiconductor solution a and an organic semiconductor solution b respectively; 2) taking a substrate and performing a solvent-philic treatment and a solvent-phobic treatment respectively to obtain a solvent-philic substrate and a solvent-phobic substrate; 3) heating the solvent-philic substrate and heating the organic semiconductor solution a and the organic semiconductor solution b or a mixed solution thereof, treating the stacked solvent-philic substrate and the solvent-phobic substrate with the organic semiconductor solution a and the organic semiconductor solution b or a mixed solution thereof, and obtaining an organic semiconductor single crystal after solidification; Step 1) The organic semiconductor material A and the organic semiconductor material B are both condensed ring thiophene materials with double-sided substituted alkyl chains and different alkyl chain lengths, and the number of carbon atoms in the alkyl chain is ≥5, and the number of alkyl carbon atoms in the organic semiconductor material A is greater than the number of alkyl carbon atoms in the organic semiconductor material B; Step 1) the organic solvent is toluene and / or xylene and / or trimethylbenzene and / or chlorobenzene and / or dichlorobenzene and / or trichlorobenzene and / or tetralin and / or decalin and / or chlorothiophene; Step 1) The concentration of the organic semiconductor material A in the organic semiconductor solution a is 0.05-1.20 mg / mL; Step 1) The concentration of the organic semiconductor material B in the organic semiconductor solution b is 0.05-1.20 mg / mL; The solvent affinity treatment is one of the following methods: Method 1: A smooth substrate is pretreated, placed in an inert gas environment, a hydrocarbon compound is spin-coated on the substrate, and a solvent-philic substrate is obtained by heat treatment; The pretreatment is carried out by oxygen plasma treatment at 8 to 12 W for 1 to 2 min; The hydrocarbon compound is benzocyclobutene, and the spin coating thickness is 100 to 1000 nm; The heat treatment is carried out at 160-240°C for 1-3 hours; Method 2: A smooth substrate is pretreated, placed in a vacuum oven, and modified by vapor deposition to obtain a solvent-friendly substrate; The pretreatment is plasma treatment at 8 to 12 W for 1 to 2 min; The vapor deposition modification is formed by depositing the material of the first assembled monolayer film onto the substrate; The material of the first assembled monolayer film is phenyltrichlorosilane; The temperature of the vacuum oven is 120-180°C, and the temperature is kept constant for 0.5-2 hours; The solvent-repellent treatment process comprises: Taking a smooth substrate and vapor-depositing a silane compound to obtain a solvent-repellent substrate; The silane compound is octadecyltrichlorosilane, and its dosage is 0.0001-1 mL / cm 2 Base material; The vapor deposition is carried out at 140-160°C at a speed of 0.001-0.2 nm / s, and the thickness of the vapor deposition layer is 1.8-50 nm; Step 3) the method of treating the stacked solvent-philic substrate and solvent-phobic substrate with the organic semiconductor solution a and the organic semiconductor solution b or the mixed solution of the two is a droplet fixed crystallization method or a doctor blade method; The specific method of the droplet fixed crystallization method is any one of the following methods: Method A: prepare an organic semiconductor solution a and an organic semiconductor solution b in proportion to obtain a mixed solution, heat the mixed solution and a solvent-philic substrate, place a solvent-phobic material on the solvent-philic substrate, drop the mixed solution until it completely soaks the gap between the solvent-philic substrate and the solvent-phobic substrate, and obtain an organic semiconductor single crystal after the mixed solution evaporates; Method B: heating organic semiconductor solution a, organic semiconductor solution b, and a solvent-philic substrate, placing a solvent-phobic material on the solvent-philic substrate, and dripping organic semiconductor solution a and organic semiconductor solution b twice respectively, and dripping organic semiconductor solution b or organic semiconductor solution a for the second time after the organic semiconductor solution a or organic semiconductor solution b dripped previously evaporates, and obtaining an organic semiconductor single crystal after the solution evaporates; Method C: preparing an organic semiconductor solution a and an organic semiconductor solution b in proportion to obtain a mixed solution, heating the mixed solution and a solvent-philic substrate, dripping the mixed solution onto the surface of the solvent-philic substrate, placing a solvent-phobic substrate on the solvent-philic substrate and covering the surface onto which the mixed solution has been dripped, and obtaining an organic semiconductor single crystal after the mixed solution evaporates; The scraping method is specifically: An organic semiconductor solution a and an organic semiconductor solution b are prepared in proportion to obtain a mixed solution, the mixed solution is heated until its viscosity is ≤100 mPa·s, the solvent-philic substrate is heated while the solvent-phobic substrate is heated at the same temperature so that the solvent-phobic substrate is suspended above the solvent-philic substrate, the mixed solution is injected between the solvent-philic substrate and the solvent-phobic substrate, the mixed solution is scraped on the solvent-phobic substrate, and then the solution is evaporated to obtain an organic semiconductor single crystal.

2. The method for preparing a large-area single-layer single-crystal domain organic semiconductor single crystal according to claim 1, characterized in that: Step 1) The organic semiconductor material A is 2,9-dialkyl dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and / or 2,7-dialkyl dibenzo[d,d]thiophene[3,2-b;4,5-b]dithiophene and / or 2,7-dialkylbenzothiophene[3,2-b]benzothiophene; Step 1) The organic semiconductor material B is 2,9-dialkyl dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene and / or 2,7-dialkyl dibenzo[d,d]thiophene[3,2-b;4,5-b]dithiophene and / or 2,7-dialkylbenzothiophene[3,2-b]benzothiophene.

3. The method for preparing a large-area single-layer single-crystal domain organic semiconductor single crystal according to claim 1, characterized in that: The substrate is glass and / or silicon wafer and / or sapphire and / or p-xylene polymer and / or polydimethylsiloxane.

4. The method for preparing a large-area single-layer single-crystal domain organic semiconductor single crystal according to claim 1, characterized in that: Step 3) The heating treatment heats the solvent-philic substrate and / or the organic semiconductor solution a and / or the organic semiconductor solution b and / or the mixed solution of the organic semiconductor solution a and the organic semiconductor solution b to 30-90°C.

5. The method for preparing a large-area single-layer single-crystal domain organic semiconductor single crystal according to claim 1, characterized in that: The molar ratio of the organic semiconductor material A to the organic semiconductor material B contained in the organic semiconductor solution a and the organic semiconductor solution b used in step 3) is 1:(1-100).

6. The method for preparing a large-area single-layer single-crystal domain organic semiconductor single crystal according to claim 1, characterized in that: The distance between the solubilizing agent substrate and the solvent-philic substrate is controlled to be 50 to 300 μm during the scraping process; The scraping process controls the scraping rate to be 1-100 μm / s.

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