Organic semiconductor thin film, transistor, method for manufacturing organic semiconductor thin film, method for manufacturing transistor, and method for manufacturing electronic device

Abstract

An organic semiconductor thin film comprising a liquid crystalline organic semiconductor, wherein Qp and Qt measured by a predetermined method satisfy a predetermined requirement (1), and a rocking scan pattern has a ratio Ipeak / Ibas, which is a ratio of the peak intensity of a maximum peak Ipeak with respect to a base line value Ibas, of less than 10. (1): 0.06 ≤ Qp / Qt ≤ 0.5

Description

[Technical field]

[0001] The present invention relates to an organic semiconductor thin film, a transistor, a method for manufacturing an organic semiconductor thin film, a method for manufacturing a transistor, and a method for manufacturing an electronic device. This application claims priority based on Japanese Patent Application No. 2021-085293, filed on May 20, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] The solvent evaporation method has been considered as a method for producing an organic semiconductor thin film. In the solvent evaporation method, the solvent is evaporated from an organic semiconductor solution to precipitate an organic semiconductor material from the solution, thereby producing an organic semiconductor film.

[0003] Film formation methods that utilize the solvent evaporation method include dip coating, drop casting, spin coating, inkjet printing, gravure printing, etc. These solution-based processes do not require a vacuum, can be carried out simply and inexpensively, and can be produced at low temperatures of 200°C or less, making them industrially useful methods that can produce high-performance organic semiconductor thin films.

[0004] When producing single crystal films or single crystal crystalline films by the solvent evaporation method, the thickness is 1 to 10 cm 2 It is possible to manufacture an organic semiconductor crystal film having a high carrier mobility / Vs. However, as described in Non-Patent Document 1, for example, the film formation speed is slow at about 100 μm / sec to 1 mm / sec, and there is room for improvement in terms of the film formation speed for industrial applications. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Yamamura et al., Sci. Adv. 2018;4: eaao5758 2 February 2018 Summary of the Invention

[0006] In the organic semiconductor film of the present invention, Qp and Qt measured by the measurement method described below satisfy the following (1), and in the rocking scan pattern described below, the ratio Ipeak / Ibas of the peak intensity Ipeak of the maximum peak described below to the baseline value Ibas described below is less than 10. 0.06≦Qp / Qt≦0.5 (1) [Measurement method] (i) X-ray diffraction measurement is performed on the organic semiconductor thin film in the in-plane direction on the substrate surface, and the diffraction angle 2θ at which the peak of the (020) crystal plane is observed is identified. (ii) The diffraction angle 2θ and the position of the detector are fixed, and X-ray diffraction measurement is performed in the in-plane direction of the substrate surface while rotating only the substrate on which the organic semiconductor thin film is formed by 180°, to obtain a rocking scan pattern. (iii) Obtaining a baseline of the rocking scan pattern. (iv) In the rocking scan pattern, the maximum peak that exceeds the baseline in the positive direction is identified, and the area of ​​the peak portion that exceeds the baseline is defined as Qp. (v) The total peak area of ​​the rocking scan pattern is Qt. [Brief description of the drawings]

[0007] [Figure 1A] 1 is a polarizing microscope photograph of the organic semiconductor film of Comparative Example 1. FIG. [Figure 1B] 1 is an X-ray diffraction pattern of the organic semiconductor film of Comparative Example 1. [Figure 1C] 1 shows a rocking scan pattern of the organic semiconductor film of Comparative Example 1. [Figure 1D] FIG. 13 is a diagram showing the mobility distribution of a transistor of the organic semiconductor film of Comparative Example 1. [Figure 2A] 1 is a polarizing microscope photograph of the organic semiconductor film of Comparative Example 2. FIG. [Figure 2B] 1 is an X-ray diffraction pattern of the organic semiconductor film of Comparative Example 2. [Figure 2C] 1 shows a rocking scan pattern of the organic semiconductor film of Comparative Example 2. [Figure 2D] FIG. 13 is a diagram showing the distribution of mobility of a transistor formed at a deposition speed of 5 mm / sec. [Figure 3A] FIG. 13 is a polarizing microscope photograph of the organic semiconductor film of Comparative Example 3. [Figure 3B] 1 is an X-ray diffraction pattern of the organic semiconductor film of Comparative Example 3. [Figure 3C] 13 is a rocking scan pattern of the organic semiconductor film of Comparative Example 3. [Figure 3D] FIG. 13 is a diagram showing the distribution of mobility of a transistor formed at a deposition rate of 10 mm / sec. [Figure 4A] 1 is a polarizing microscope photograph of the organic semiconductor film of Example 1. FIG. [Figure 4B] 1 is an X-ray diffraction pattern of the organic semiconductor film of Example 1. [Figure 4C] 1 shows a rocking scan pattern of the organic semiconductor film of Example 1. [Figure 5A] FIG. 2 is a polarizing microscope photograph of the organic semiconductor film of Example 2. [Figure 5B] 1 is an X-ray diffraction pattern of the organic semiconductor film of Example 2. [Figure 5C] 1 shows a rocking scan pattern of the organic semiconductor film of Example 2. [Figure 6A] FIG. 11 is a polarizing microscope photograph of the organic semiconductor film of Example 3. [Figure 6B] 1 is an X-ray diffraction pattern of the organic semiconductor film of Example 3. [Figure 6C] 1 shows a rocking scan pattern of the organic semiconductor film of Example 3. [Figure 7A] FIG. 1 is a polarizing microscope photograph of the organic semiconductor film of Example 4. [Figure 7B] 1 is an X-ray diffraction pattern of the organic semiconductor film of Example 4. [Figure 7C] 1 shows a rocking scan pattern of the organic semiconductor film of Example 4. [Figure 7D] FIG. 13 is a diagram showing the mobility distribution of a transistor formed at a film formation speed of 40 mm / sec. [Figure 8A]FIG. 11 is a polarizing microscope photograph of the organic semiconductor film of Comparative Example 4. [Figure 8B] 1 is an X-ray diffraction pattern of the organic semiconductor film of Comparative Example 4. [Figure 8C] 13 is a rocking scan pattern of the organic semiconductor film of Comparative Example 4. [Figure 9] This is a graph showing the pulling rate on the horizontal axis and Qp / Qt on the vertical axis, and further showing the variation in mobility. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <Organic semiconductor thin film> This embodiment is an organic semiconductor thin film containing a liquid crystalline organic semiconductor. The organic semiconductor thin film of this embodiment is manufactured by the method for manufacturing an organic semiconductor thin film of this embodiment described later.

[0009] In the organic semiconductor thin film of this embodiment, Qp and Qt measured by the measurement method described below satisfy (1). Furthermore, the ratio Ipeak / Ibas of the peak intensity Ipeak of the maximum peak described below to the baseline value Ibas described below is less than 10. 0.06≦Qp / Qt≦0.5 (1) [Measurement method] (i) X-ray diffraction measurement is performed on the organic semiconductor thin film in the in-plane direction on the substrate surface, and the diffraction angle 2θ at which the peak of the (020) crystal plane is observed is identified. (ii) The diffraction angle 2θ and the position of the detector are fixed, and X-ray diffraction measurement is performed in the in-plane direction of the substrate surface while rotating only the substrate on which the organic semiconductor thin film is formed by 180°, to obtain a rocking scan pattern. (iii) Obtaining a baseline of the rocking scan pattern. (iv) In the rocking scan pattern, the maximum peak that exceeds the baseline in the positive direction is identified, and the area of ​​the peak portion that exceeds the baseline is defined as Qp. (v) The total peak area of ​​the rocking scan pattern is Qt.

[0010] In step (i), the diffraction angle 2θ at which the peak of the (020) crystal plane is observed is specified because the peak of the (020) crystal plane is more easily observed. For example, even if the peaks of other crystal planes such as the (110) plane or the (120) plane are observed, the diffraction angle 2θχ can be similarly specified.

[0011] In step (ii), the position of the detector is fixed at 2θχ, and only the substrate on which the organic semiconductor thin film is formed is rotated 180° while X-ray diffraction measurements are performed in the directions within the substrate surface, allowing X-rays to be irradiated from all directions and the orientation of the crystal planes to be confirmed in all directions.

[0012] In step (iii), the rocking scan pattern obtained in step (ii) is analyzed using analysis software. For smoothing processing in the analysis software, for example, Global fit manufactured by Rigaku Co., Ltd. can be used. One example of the smoothing process is convolution using a Gaussian function.

[0013] In step (iii), a baseline of the rocking scan pattern is obtained. Here, the "baseline" is a value obtained by smoothing the data using analysis software, finding the minimum value, and calculating the average value within a range that does not include a steep peak. The range that does not include a steep peak is a range of 2.5 degrees around the minimum value.

[0014] In this embodiment, the ratio Ipeak / Ibas in the rocking scan pattern is less than 10. This means that in the above measurement method, it is a random film in which the (020) crystal plane is observed in all directions.

[0015] In step (v), a peak that exceeds the baseline in the positive direction is identified in the rocking scan pattern, and the area of ​​the peak that exceeds the baseline is defined as Qp. A peak is observed in the rocking scan pattern of the organic semiconductor thin film of this embodiment. This is because, in the process of producing the organic semiconductor film, the organic semiconductor solution is applied to the substrate in one direction at a speed exceeding 10 mm / sec, and the crystal orientation is anisotropic.

[0016] For example, when an organic semiconductor solution is applied to a substrate by spin coating, the crystal orientation does not have anisotropy, so that no peaks are observed in the rocking scan pattern of the organic semiconductor thin film.

[0017] Qp is the area formed by the baseline and the area beyond the baseline.

[0018] In step (v), the total area of ​​the rocking scan pattern, Qt, is obtained.

[0019] When Qp and Qt satisfy (1), it is a random film in which the (020) crystal plane is observed in all directions in the above measurement method, and it is found that the crystal orientation has anisotropy.

[0020] (1) is preferably any one of the following (1)-1 to (1)-3. 0.07≦Qp / Qt≦0.49 (1)-1 0.08≦Qp / Qt≦0.48 (1)-2 0.09≦Qp / Qt≦0.47 (1)-3

[0021] An organic semiconductor film in which Qp and Qt satisfy (1) has a small variation in mobility. Here, "small variation in mobility" means that the variation coefficient determined by the method described below in [Evaluation of carrier mobility] is 20% or less.

[0022] [Evaluation of carrier mobility] (Carrier mobility μ AV Measurement of Regarding the organic thin film transistor, the carrier mobility of all the manufactured samples for carrier mobility measurement is measured. Specifically, a voltage of -50 V was applied between the source electrode and the drain electrode of each organic thin-film transistor element, and the gate voltage was changed in the range of +10 V to -70 V. The carrier mobility μ (cm 2The average carrier mobility of all samples is calculated and this is called the carrier mobility μ AV Let us assume that. Carrier mobility μ AV The higher the value, the more preferable it is.

[0023] I d =(w / 2L)μC i (V g -V th ) 2 where L is the channel length, w is the channel width, μ is the carrier mobility, and C i is the capacitance per unit area of ​​the gate insulating layer, V g is the gate voltage, V th represent the threshold voltages, respectively.

[0024] (Calculation of the variation coefficient) Regarding the organic thin-film transistor, the above (carrier mobility μ AV For the carrier mobility μ of all samples measured in the test described in (1) Measurement of the carrier mobility μ of all samples, the mutation coefficient is calculated by the following formula. In the following formula, the standard deviation is calculated by a conventional method, and the average value is the above-mentioned carrier mobility μ AV This variation coefficient is evaluated as an index of the variation in carrier mobility.

[0025] Variance coefficient (%) = (standard deviation / average value) x 100

[0026] In this embodiment, when Qp and Qt satisfy (1), it is possible to reduce the variation in mobility even in a polycrystalline film. The rational reason for this can be explained as follows. When Qp and Qt satisfy (1), the proportion of crystal grains oriented in a specific direction in the crystal film is small, and the proportion of crystal grains oriented randomly within the plane is high. When an element is formed using such a crystal film, even if there is anisotropy in the mobility within the crystal grains, the characteristics are averaged, and the variation in the mobility of the element can be suppressed to a small extent. This is a different approach from the conventional approach using single-crystalline crystal films, and gives it a great industrial advantage.

[0027] In one embodiment of the organic semiconductor thin film of this embodiment, 2 / Vs or more.

[0028] The mobility was measured using a commonly used method for evaluating FET mobility; that is, a bottom-gate, bottom-contact transistor was fabricated using a SiO2 / Si substrate as the gate insulating film / gate electrode, and the mobility was calculated from the transistor characteristics in the saturation region.

[0029] In one embodiment of the organic semiconductor thin film of this embodiment, the average film thickness is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less.

[0030] <Transistor> This embodiment is a transistor including the organic semiconductor thin film of this embodiment as a semiconductor layer.

[0031] In the organic semiconductor film included in the transistor of this embodiment, the Qp and Qt satisfy the above (1). Furthermore, the ratio Ipeak / Ibas of the peak intensity Ipeak of the maximum peak in the rocking scan pattern below to the baseline value Ibas below is less than 10.

[0032] Conventionally, when producing an organic semiconductor film, the growth of the crystal grains of the organic semiconductor is controlled to align the orientation direction of the crystal grains and increase the grain size to reduce the effect of the crystal grain boundaries and to uniformize the characteristics of the crystal film. However, although this method can reduce the density of grain boundaries in the entire crystal film, when used as a semiconductor layer of a transistor, the number of the few crystal grain boundaries that can exist in the channel region varies greatly between elements, resulting in large variations in the element characteristics.

[0033] Conversely, one approach to reducing the variation between transistor elements would be to increase the number of grain boundaries in the organic semiconductor film. However, in this case, the density of the grain boundaries in the channel region of the transistor would also increase, degrading the carrier transport characteristics and impairing the performance of the element.

[0034] On the other hand, the organic semiconductor film of the present embodiment can suppress the formation of crystal grain boundaries that inhibit carrier transport while increasing the number of crystal grain boundaries. Here, the crystal grain boundaries that inhibit carrier transport are formed by crystal domains oriented in a specific direction, and the organic semiconductor film of the present embodiment suppresses the orientation of the crystal domains in a specific direction.

[0035] In the organic semiconductor film of this embodiment, the average grain size of the crystal domains is preferably 1 μm or more and 300 μm or less, more preferably 1 μm or more and 200 μm or less, and even more preferably 1 μm or more and 100 μm or less.

[0036] In the organic semiconductor film of this embodiment, the aspect ratio of the crystal domains (ratio of the major axis to the minor axis (major axis / minor axis)) is preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less. In addition, when the organic semiconductor film contains crystal domains having an aspect ratio different from the above-mentioned aspect ratios, the area ratio of the crystal domains having the above-mentioned aspect ratios in the organic semiconductor film is preferably 30% or more, more preferably 50% or more, and even more preferably 70% or more.

[0037] <Method of manufacturing organic semiconductor thin film> The present embodiment relates to a method for producing an organic semiconductor thin film. The method for producing an organic semiconductor thin film of this embodiment includes the steps of dissolving a liquid crystalline organic semiconductor in an organic solvent to prepare an organic semiconductor solution, applying the organic semiconductor solution to a substrate at a speed exceeding 10 mm / sec, and drying the organic semiconductor solution. Each step will be described below.

[0038] [Step of preparing organic semiconductor solution] First, an organic semiconductor is dissolved in an organic solvent to prepare an organic semiconductor solution. The organic semiconductor used in this embodiment may be, for example, an organic semiconductor having a structure in which one or two alkyl chains are substituted in the molecular long axis direction of a π-electron system skeleton responsible for charge transport.

[0039] The π-electron skeleton of the organic semiconductor used in this embodiment is preferably a thienoacene skeleton, typically a benzothieneobenzothiazole skeleton, but is not limited thereto. Representative examples of compounds having a thienoacene skeleton include the compounds described in WO 2012-121393.

[0040] In this embodiment, among these, 2-decyl-7-phenylbenzothieneobenzothiophene (Ph-BTBT-10) and derivatives having different chain lengths and derivatives in which the side chain is substituted on the phenyl group side are preferable.

[0041] The organic semiconductor molecules having an alkyl group used in this embodiment exhibit liquid crystallinity. When liquid crystallinity is exhibited, a uniform and flat crystal film can be produced. In addition, it is preferable for forming an organic crystal film for a transistor from the viewpoint of easily controlling the crystal grain boundary (for example, see non-patent paper (Adv. Mater., 23, 1748-1751, 2006) and non-patent document (Jpn. J. Appl. Phys., 45, L867-870, 2006)).

[0042] In preparing the semiconductor solution, a small amount of insulating polymer such as polystyrene may be added to control the morphology of the organic semiconductor film to be formed. When an insulating polymer is added, the amount can be appropriately adjusted within the range of 0.1% by mass to 10% by mass based on the total amount of the organic semiconductor.

[0043] The organic solvent used in this embodiment is preferably an organic solvent having a boiling point of 250° C. or less, more preferably 200° C. or less, for film formation at around room temperature. Specific examples include alkyl-substituted benzene derivatives such as toluene, xylene, and diethylbenzene, in which organic semiconductors can be dissolved. The alkyl-substituted benzene derivative may be substituted with a halogen atom, an alkoxy group, or a thioalkoxy group. Examples of those substituted with an alkoxy group include anisole and thioanisole derivatives.

[0044] In this embodiment, it is preferable to use an organic solvent that dissolves the organic semiconductor at a concentration of 0.01% by mass or more, and it is more preferable to use an organic solvent that dissolves the organic semiconductor at a concentration of 0.1% by mass or more.

[0045] [Coating process] Next, depending on the application method, a liquid film of the organic semiconductor solution is formed on the substrate. In the present embodiment, the organic semiconductor solution is preferably applied to the substrate in one direction. The method for applying the organic semiconductor solution includes, for example, a dip coating method, but is not limited thereto, and other known methods may be used as long as they can apply the organic semiconductor solution to the substrate in one direction.

[0046] The thickness of the organic semiconductor film is generally selected depending on the type of device to be produced, such as an organic EL element, a photosensor, a solar cell, or a transistor. For example, when producing an organic transistor, the film thickness is set to 5 nm to 200 nm, more preferably 5 nm to 100 nm, and even more preferably 5 nm to 50 nm. The film thickness of the produced crystal film can also be directly controlled by the thickness of the liquid film applied to the substrate. It is also generally known that the thickness of the crystal film to be formed can be appropriately controlled by the type of solvent used, the concentration of the organic semiconductor, the type of substrate, the temperature of the organic semiconductor solution, and the temperature of the substrate to which it is applied.

[0047] In this embodiment, when an organic semiconductor exhibiting liquid crystallinity is used, it is effective to set the temperature at which the liquid film of the organic semiconductor solution is formed on the substrate to be close to the liquid crystal phase temperature of the liquid crystalline organic semiconductor used. The temperature during the formation of the liquid film may be controlled by heating the substrate, or when a dip coating method is used, the temperature can be controlled by the temperature of the organic semiconductor solution when the substrate is immersed in the solution.

[0048] For example, when Ph-BTBT-10 is used as the organic semiconductor exhibiting liquid crystallinity, it is preferable to adjust the film formation temperature to a range of 40° C. to 150° C. When C8-BTBT is used, it is preferable to adjust the film formation temperature to a range of 30° C. to 120° C.

[0049] In this embodiment, the speed at which the organic semiconductor solution is applied to the substrate exceeds 10 mm / sec, preferably 15 mm / sec or more, and more preferably 30 mm / sec or more.

[0050] The upper limit of the speed at which the organic semiconductor solution is applied to the substrate is not particularly limited, but examples include 5000 mm / sec or less, 1000 mm / sec or less, 500 mm / sec or less, and 100 mm / sec or less.

[0051] The above upper and lower limit values ​​of the pulling speed can be combined arbitrarily. Examples of combinations include greater than 10 mm / sec and less than or equal to 120 mm / sec, greater than 10 mm / sec and less than or equal to 100 mm / sec, 20 mm / sec or more and less than or equal to 80 mm / sec, and 40 mm / sec or more and less than or equal to 60 mm / sec.

[0052] [Process for drying the organic semiconductor solution] In the manufacturing method of this embodiment, an organic semiconductor solution is applied to a substrate, and a liquid layer of the organic semiconductor solution is formed on the substrate. Furthermore, the organic solvent contained in the liquid layer dries by evaporation, and crystals are precipitated to form a solid film of the organic semiconductor on the surface of the substrate. That is, in this embodiment, the speed at which the substrate is pulled up from the organic semiconductor solution is synonymous with the film formation speed, and may be referred to as the film formation speed hereinafter.

[0053] In this embodiment, an organic semiconductor thin film can be formed at a film formation speed exceeding 10 mm / sec, which is significantly faster than conventional film formation speeds.

[0054] In this embodiment, in the case of the dip coating method, the substrate is generally pulled up vertically from the liquid surface of the organic semiconductor solution, but pulling it up at an angle is also effective in controlling the thickness of the liquid film.

[0055] The substrate is not particularly limited, and examples of the substrate that can be used include glass, quartz glass, a silicon wafer, a metal plate, and a flexible resin sheet. For example, a plastic film can be used as the sheet. Examples of the plastic film include films made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP), etc.

[0056] As described above, the manufacturing method of this embodiment can form a film by applying a semiconductor solution at a low temperature of 200° C. or less, so it is not subject to restrictions on the material, size, or shape of the substrate. Therefore, it can be applied to continuous mass production equipment such as a roll-to-roll process.

[0057] <Transistor manufacturing method> This embodiment is a method for manufacturing a transistor having a semiconductor layer. The method for producing a transistor of this embodiment includes a step of forming a semiconductor layer by the method for producing an organic semiconductor film of this embodiment.

[0058] <Electronic device manufacturing method> This embodiment is a method for manufacturing an electronic device. The method for manufacturing an electronic device according to this embodiment includes a step of forming a transistor by the method for manufacturing a transistor according to this embodiment. EXAMPLES

[0059] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0060] <Preparation of semiconductor solution> Ph-BTBT-10 was synthesized according to the non-patent literature (Nature Commun., DOI: 0.1038 / ncomms7828). It was then repeatedly purified by silica column chromatography and recrystallization to improve its purity before use.

[0061] <Preparation of Substrate> The organic semiconductor film was formed on a 300 nm thermally oxidized p + A substrate was used in which a BCB film with a thickness of about 20 nm was formed on a -Si substrate. BCB stands for Dibutyltetramethyldisiloxane-bis{benzocyclobutene).

[0062] <Application of semiconductor solution by dip coating method> The crystal film was produced using a dip coater. The dip coater used had a substrate placement section, a substrate lifting section capable of electrically controlling the lifting speed, and a container filled with an organic semiconductor solution whose temperature was controlled to be constant. In this example, a dip coater with a substrate lifting speed of up to 40 mm / sec was used.

[0063] <Transistor fabrication and evaluation> To fabricate the transistor, a SiO2 (300 nm) / Si substrate coated with BCB with a thickness of about 20 nm was used as the substrate. Au was deposited by vacuum deposition using a shadow mask to form source and drain electrodes, and the substrate was treated with PFBT (pentafluorobenzenethiol) in a glove box. The channel length and width were 100 μm and 500 μm, respectively. The characteristics of the fabricated transistor were examined at room temperature in the atmosphere, and the mobility was calculated from the transistor characteristics in the saturation region.

[0064] <Evaluation of carrier mobility> The carrier mobility of the transistor was evaluated by the method described in [Evaluation of Carrier Mobility] above.

[0065] <Comparative Example 1> A SiO2 / Si substrate coated with BCB was immersed in a 0.5 mass% Ph-BTBT-10 p-xylene solution maintained at 130℃, and the substrate was pulled up at a speed of 1 mm / sec in the direction opposite to gravity at room temperature under atmospheric conditions. Immediately after pulling up, the formation of a liquid film on the substrate was visually confirmed, and the formation of a solid film was confirmed as the solvent dried.

[0066] The crystal film formed on the substrate was subjected to a heat treatment at 120° C. for 15 minutes.

[0067] Figure 1A is a polarized light micrograph of a crystalline film produced at a pulling speed of 1 mm / sec. The crystalline film in Figure 1A exhibited a texture in which the crystalline domains were oriented in the film formation direction.

[0068] Grazing incidence X-ray diffraction measurements were performed on the crystal film in the in-plane direction on the substrate surface, and the diffraction angle 2θχ at which the peak of the (020) crystal plane was observed was identified. The X-ray diffraction pattern obtained is shown in Figure 1B.

[0069] The detector position was fixed at the diffraction angle 2θχ, and the substrate on which the crystalline film was formed was rotated 180° while performing grazing incidence X-ray diffraction measurement in the direction within the substrate surface to obtain a rocking scan pattern, which is shown in Figure 1C.

[0070] The rocking scan pattern was smoothed (convoluted with a Gaussian function) using analysis software (Rigaku, Global fit), and the minimum value was found. The average value was calculated in the range that did not include steep peaks (2.5 degrees before and after the minimum value) to obtain the baseline. Peaks that exceeded the baseline in the positive direction were identified from the rocking scan pattern, and the area exceeding the baseline was defined as Qp. The total area of ​​the rocking scan pattern was defined as Qt.

[0071] The crystalline film of Comparative Example 1 had a Qp / Qt of 0.74. Also, from FIG. 1C, the ratio Ipeak / Ibas was 53.36 in the rocking scan pattern.

[0072] FIG. 1D is a graph showing the mobility distribution of a transistor formed at a deposition speed of 1 mm / sec. The average mobility of a transistor is 0.53 cm 2 / Vs. The mobility variation was 28.0%.

[0073] <Comparative Example 2> A SiO2 / Si substrate coated with BCB was immersed in a 0.5 mass% Ph-BTBT-10 p-xylene solution maintained at 130℃, and the substrate was pulled up at a speed of 5 mm / sec in the direction opposite to gravity at room temperature under atmospheric conditions. Immediately after pulling up, the formation of a liquid film on the substrate was visually confirmed, and the formation of a solid film was confirmed as the solvent dried.

[0074] The crystal film formed on the substrate was subjected to a heat treatment at 120° C. for 15 minutes.

[0075] Figure 2A is a polarized light micrograph of a crystalline film produced at a pulling speed of 5 mm / sec. The crystalline film in Figure 2A exhibited a texture in which the crystalline domains were oriented in the film formation direction.

[0076] X-ray diffraction measurements were performed on the crystal film in the in-plane direction on the substrate surface, and the diffraction angle 2θ at which the peak of the (020) crystal plane was observed was identified. The resulting X-ray diffraction pattern is shown in Figure 2B.

[0077] The diffraction angle 2θ and the position of the detector were fixed, and only the substrate on which the crystalline film was formed was rotated 180° while performing X-ray diffraction measurement in the direction within the substrate surface to obtain a rocking scan pattern. The obtained rocking scan pattern is shown in Figure 2C.

[0078] The rocking scan pattern was analyzed using analysis software (Rigaku, Global fit) to obtain a baseline. The maximum peak exceeding the baseline in the positive direction was identified from the rocking scan pattern, and the area of ​​the peak exceeding the baseline was defined as Qp. The total peak area of ​​the rocking scan pattern was defined as Qt.

[0079] The crystalline film of Comparative Example 2 had a Qp / Qt of 0.76. Also, from FIG. 2C, the ratio Ipeak / Ibas was 29.40 in the rocking scan pattern.

[0080] FIG. 2D is a graph showing the mobility distribution of a transistor formed at a deposition speed of 5 mm / sec. The average mobility of a transistor is 4.59 cm 2 / Vs. The mobility variation was 24.1%.

[0081] <Comparative Example 3> A SiO2 / Si substrate coated with BCB was immersed in a 0.5 mass% Ph-BTBT-10 p-xylene solution maintained at 130℃, and the substrate was pulled up at a speed of 10 mm / sec in the direction opposite to gravity at room temperature under atmospheric conditions. Immediately after pulling up, the formation of a liquid film on the substrate was visually confirmed, and the formation of a solid film was confirmed as the solvent dried.

[0082] The crystal film formed on the substrate was subjected to a heat treatment at 120° C. for 15 minutes.

[0083] Figure 3A is a polarized light micrograph of a crystalline film produced at a pulling speed of 10 mm / sec, which exhibited a texture with randomly oriented crystalline domains.

[0084] X-ray diffraction measurements were performed on the crystal film in the in-plane direction on the substrate surface, and the diffraction angle 2θ at which the peak of the (020) crystal plane was observed was identified. The X-ray diffraction pattern obtained is shown in Figure 3B.

[0085] The diffraction angle 2θ and the position of the detector were fixed, and only the substrate on which the crystalline film was formed was rotated 180° while performing X-ray diffraction measurement in the direction within the substrate surface to obtain a rocking scan pattern. The obtained rocking scan pattern is shown in Figure 3C.

[0086] The rocking scan pattern was analyzed using analysis software (Rigaku, Global fit) to obtain a baseline. The maximum peak exceeding the baseline in the positive direction was identified from the rocking scan pattern, and the area of ​​the peak exceeding the baseline was defined as Qp. The total peak area of ​​the rocking scan pattern was defined as Qt.

[0087] The crystalline film of Comparative Example 3 had a Qp / Qt of 0.57. Also, from FIG. 3C, the ratio Ipeak / Ibas was 10.09 in the rocking scan pattern.

[0088] FIG. 3D is a graph showing the mobility distribution of a transistor formed at a deposition rate of 10 mm / sec. The average mobility of a transistor is 4.53 cm 2 / Vs. The mobility variation was 40.5%.

[0089] <Example 1> A SiO2 / Si substrate coated with BCB was immersed in a 0.5 mass% Ph-BTBT-10 p-xylene solution maintained at 130℃, and the substrate was pulled up at a speed of 15 mm / sec in the direction opposite to gravity at room temperature under atmospheric conditions. Immediately after pulling up, the formation of a liquid film on the substrate was visually confirmed, and the formation of a solid film was confirmed as the solvent dried.

[0090] The crystal film formed on the substrate was subjected to a heat treatment at 120° C. for 15 minutes.

[0091] Figure 4A is a polarized light micrograph of a crystalline film produced at a pulling speed of 15 mm / sec, which exhibited a texture with randomly oriented crystalline domains.

[0092] X-ray diffraction measurements were performed on the crystal film in the in-plane direction on the substrate surface, and the diffraction angle 2θ at which the peak of the (020) crystal plane was observed was identified. The X-ray diffraction pattern obtained is shown in Figure 4B.

[0093] The diffraction angle 2θ and the position of the detector were fixed, and only the substrate on which the crystalline film was formed was rotated 180° while performing X-ray diffraction measurement in the direction within the substrate surface to obtain a rocking scan pattern. The obtained rocking scan pattern is shown in Figure 4C.

[0094] The rocking scan pattern was analyzed using analysis software (Rigaku, Global fit) to obtain a baseline. The maximum peak exceeding the baseline in the positive direction was identified from the rocking scan pattern, and the area of ​​the peak exceeding the baseline was defined as Qp. The total peak area of ​​the rocking scan pattern was defined as Qt.

[0095] The crystal film of Example 1 had a Qp / Qt of 0.24. Also, from FIG. 4C, the ratio Ipeak / Ibas was 2.94 in the rocking scan pattern. The variation in the mobility of the transistors was 14.0%.

[0096] <Example 2> A SiO2 / Si substrate coated with BCB was immersed in a 0.5 mass% Ph-BTBT-10 p-xylene solution maintained at 130℃, and the substrate was pulled up at a speed of 20 mm / sec in the direction opposite to gravity at room temperature under atmospheric conditions. Immediately after pulling up, the formation of a liquid film on the substrate was visually confirmed, and the formation of a solid film was confirmed as the solvent dried.

[0097] The crystal film formed on the substrate was subjected to a heat treatment at 120° C. for 15 minutes.

[0098] Figure 5A is a polarized light micrograph of a crystalline film produced at a pulling speed of 20 mm / sec. The crystalline film in Figure 5A exhibited a texture with randomly oriented crystalline domains.

[0099] X-ray diffraction measurements were performed on the crystal film in the in-plane direction on the substrate surface, and the diffraction angle 2θ at which the peak of the (020) crystal plane was observed was identified. The resulting X-ray diffraction pattern is shown in Figure 5B.

[0100] The diffraction angle 2θ and the position of the detector were fixed, and only the substrate on which the crystalline film was formed was rotated 180° while performing X-ray diffraction measurement in the direction within the substrate surface to obtain a rocking scan pattern. The obtained rocking scan pattern is shown in Figure 5C.

[0101] The rocking scan pattern was analyzed using analysis software (Rigaku, Global fit) to obtain a baseline. The maximum peak exceeding the baseline in the positive direction was identified from the rocking scan pattern, and the area of ​​the peak exceeding the baseline was defined as Qp. The total peak area of ​​the rocking scan pattern was defined as Qt.

[0102] The crystal film of Example 2 had a Qp / Qt of 0.30. Also, from FIG. 5C, the ratio Ipeak / Ibas was 4.959 in the rocking scan pattern. The mobility variation of the transistors was 11.7%.

[0103] <Example 3> A SiO2 / Si substrate coated with BCB was immersed in a 0.5 mass% Ph-BTBT-10 p-xylene solution maintained at 130℃, and the substrate was pulled up at a speed of 30 mm / sec in the direction opposite to gravity at room temperature under atmospheric conditions. Immediately after pulling up, the formation of a liquid film on the substrate was visually confirmed, and the formation of a solid film was confirmed as the solvent dried.

[0104] The crystal film formed on the substrate was subjected to a heat treatment at 120° C. for 15 minutes.

[0105] Figure 6A is a polarized light micrograph of a crystalline film produced at a pulling speed of 30 mm / sec. The crystalline film in Figure 6A exhibited a texture with randomly oriented crystalline domains.

[0106] X-ray diffraction measurements were performed on the crystal film in the in-plane direction on the substrate surface, and the diffraction angle 2θ at which the peak of the (020) crystal plane was observed was identified. The X-ray diffraction pattern obtained is shown in Figure 6B.

[0107] The diffraction angle 2θ and the position of the detector were fixed, and only the substrate on which the crystalline film was formed was rotated 180° while performing X-ray diffraction measurement in the direction within the substrate surface to obtain a rocking scan pattern. The obtained rocking scan pattern is shown in Figure 6C.

[0108] The rocking scan pattern was analyzed using analysis software (Rigaku, Global fit) to obtain a baseline. The maximum peak exceeding the baseline in the positive direction was identified from the rocking scan pattern, and the area of ​​the peak exceeding the baseline was defined as Qp. The total peak area of ​​the rocking scan pattern was defined as Qt.

[0109] The crystal film of Example 3 had a Qp / Qt of 0.13. Also, from FIG. 6C, the ratio Ipeak / Ibas was 1.645 in the rocking scan pattern. The mobility variation of the transistors was 13.5%.

[0110] <Example 4> A SiO2 / Si substrate coated with BCB was immersed in a 0.5 mass% Ph-BTBT-10 p-xylene solution maintained at 130℃, and the substrate was pulled up at a speed of 40 mm / sec in the direction opposite to gravity at room temperature under atmospheric conditions. Immediately after pulling up, the formation of a liquid film on the substrate was visually confirmed, and the formation of a solid film was confirmed as the solvent dried.

[0111] The crystal film formed on the substrate was subjected to a heat treatment at 120° C. for 15 minutes.

[0112] Figure 7A is a polarized light micrograph of a crystalline film produced at a pulling speed of 40 mm / sec. The crystalline film in Figure 7A exhibited a texture with randomly oriented crystalline domains.

[0113] X-ray diffraction measurements were performed on the crystal film in the in-plane direction on the substrate surface, and the diffraction angle 2θ at which the peak of the (020) crystal plane was observed was identified. The resulting X-ray diffraction pattern is shown in Figure 7B.

[0114] The diffraction angle 2θ and the position of the detector were fixed, and only the substrate on which the crystalline film was formed was rotated 180° while performing X-ray diffraction measurement in the direction within the substrate surface to obtain a rocking scan pattern. The obtained rocking scan pattern is shown in Figure 7C.

[0115] The rocking scan pattern was analyzed using analysis software (Rigaku, Global fit) to obtain a baseline. The maximum peak exceeding the baseline in the positive direction was identified from the rocking scan pattern, and the area of ​​the peak exceeding the baseline was defined as Qp. The total peak area of ​​the rocking scan pattern was defined as Qt.

[0116] The crystal film of Example 4 had a Qp / Qt of 0.39. Also, from FIG. 7C, the ratio Ipeak / Ibas was 5.199 in the rocking scan pattern.

[0117] FIG. 7D is a diagram showing the mobility distribution of a transistor formed at a deposition speed of 40 mm / sec. The average mobility of a transistor is 4.13 cm 2 / Vs. The mobility variation was 18.2%.

[0118] <Comparative Example 4> A 0.5 mass% solution of Ph-BTBT-10 in p-xylene maintained at 80℃ was spin-coated at 3000 rpm onto a SiO2 / Si substrate coated with BCB. A solid film was instantly formed upon spin-coating.

[0119] The crystal film formed on the substrate was subjected to a heat treatment at 120° C. for 15 minutes.

[0120] Figure 8A is a polarizing microscope photograph of a crystalline film produced by spin coating. The crystalline film in Figure 8A exhibits a texture in which the crystalline domains are oriented in the film formation direction.

[0121] X-ray diffraction measurements were performed on the crystal film in the in-plane direction on the substrate surface, and the diffraction angle 2θ at which the peak of the (020) crystal plane was observed was identified. The resulting X-ray diffraction pattern is shown in Figure 8B.

[0122] The diffraction angle 2θ and the position of the detector were fixed, and only the substrate on which the crystalline film was formed was rotated 180° while performing X-ray diffraction measurement in the direction within the substrate surface to obtain a rocking scan pattern. The obtained rocking scan pattern is shown in Figure 8C.

[0123] No maximum peak was observed in the rocking scan pattern, and Qp could not be calculated.

[0124] Figure 9 shows a graph with the pulling rate on the horizontal axis and Qp / Qt on the vertical axis. In Figure 9, the variation in mobility is shown as "σ / μ".

Claims

1. An organic semiconductor thin film including a liquid crystalline organic semiconductor, Qp and Qt measured by the measurement method described below satisfy the following (1), In the rocking scan pattern shown below, the ratio Ipeak / Ibas of the maximum peak intensity Ipeak shown below to the baseline value Ibas shown below is less than 10. 0.06≦Qp / Qt≦0.5 (1) [Measurement method] (i) X-ray diffraction measurement is performed on the organic semiconductor thin film in a direction within the substrate surface, and the diffraction angle 2θ at which a peak of the (020) crystal plane is observed is specified. (ii) The diffraction angle 2θ and the position of the detector are fixed, and only the substrate on which the organic semiconductor thin film is formed is rotated 180° while performing X-ray diffraction measurement in a direction within the substrate surface to obtain a rocking scan pattern. (iii) Obtaining a baseline of the rocking scan pattern. (iv) In the rocking scan pattern, the maximum peak that exceeds the baseline in the positive direction is identified, and the area of ​​the peak portion that exceeds the baseline is defined as Qp. (v) The total peak area of ​​the rocking scan pattern is designated as Qt.

2. A transistor comprising the organic semiconductor thin film according to claim 1 as a semiconductor layer.

3. A step of dissolving a liquid crystalline organic semiconductor in an organic solvent to prepare an organic semiconductor solution; applying the organic semiconductor solution to a substrate at a rate of greater than 10 mm / sec; and drying the organic semiconductor solution. the applying step is performed by immersing the substrate in the organic semiconductor solution and then lifting the substrate from the liquid surface of the organic semiconductor solution at a speed of 10 mm / sec or more.

4. A step of dissolving a liquid crystalline organic semiconductor in an organic solvent to prepare an organic semiconductor solution; applying the organic semiconductor solution to a substrate at a speed of greater than 40 mm / sec; and drying the organic semiconductor solution. A method for producing an organic semiconductor thin film.

5. A step of dissolving a liquid crystalline organic semiconductor in an organic solvent to prepare an organic semiconductor solution; applying the organic semiconductor solution to a substrate at a rate of greater than 10 mm / sec; and drying the organic semiconductor solution. In the coating step, the organic semiconductor solution is coated on the substrate in one direction, The coating step is performed by immersing the substrate in the organic semiconductor solution and then lifting the substrate from the liquid surface of the organic semiconductor solution at a speed of 10 mm / sec or more. A method for producing an organic semiconductor thin film.

6. A step of dissolving a liquid crystalline organic semiconductor in an organic solvent to prepare an organic semiconductor solution; applying the organic semiconductor solution to a substrate at a speed of greater than 40 mm / sec; and drying the organic semiconductor solution. In the coating step, the organic semiconductor solution is coated on the substrate in one direction. A method for producing an organic semiconductor thin film.

7. 1. A method for manufacturing a transistor having a semiconductor layer, comprising: A method for producing a transistor, comprising the step of forming the semiconductor layer by the method for producing an organic semiconductor thin film according to any one of claims 3 to 6.

8. A method for manufacturing an electronic device, comprising the step of forming a transistor by the method for manufacturing a transistor according to claim 7.

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