WO2016200108A1

WO2016200108A1 - Method and apparatus for growing organic material monocrystals using ionic liquid

Info

Publication number: WO2016200108A1
Application number: PCT/KR2016/005975
Authority: WO
Inventors: 신동찬; 오용택; 박세연
Original assignee: 조선대학교산학협력단
Priority date: 2015-06-11
Filing date: 2016-06-07
Publication date: 2016-12-15
Also published as: KR20160145971A; CN107660240A; KR101932994B1

Abstract

The present invention relates to a method and apparatus for growing high-purity organic material monocrystals using an ionic liquid, the method comprising: a mixing step for mixing an organic material with an ionic liquid; a solutionization step for solutionizing the organic material mixed with the ionic liquid through thermal treatment under the first condition; a nucleation step for feeding seeds into the ionic liquid, which contains the solutionized organic material, under the second condition; a monocrystalline growth step for growing monocrystals under the third condition; and a separation step for separating the grown organic material monocrystals from the ionic liquid, and thus, organic material monocrystals are obtained that are purified at high purity compared with before the mixing with the ionic liquid. According to the present invention, high-purity organic material monocrystals can be grown at low costs through a simple process.

Description

Method and apparatus for growing single crystal of organic material using ionic liquid

The present invention relates to a method and apparatus for growing an organic material single crystal, and more particularly, to a method and apparatus for growing a single crystal after mixing an organic material in an ionic liquid.

As the use of organic materials in electronic devices such as organic electroluminescence (EL) devices, organic semiconductor devices, organic photoelectric conversion devices, and organic sensor devices is increasing, interest in single crystal organic materials is increasing. However, due to the absence of efficient organic material single crystal growth technology, organic materials in an amorphous state are mostly used in organic electronic devices.

Conventional organic material single crystal growth method is a method in which the single crystal is grown by dissolving the organic material in the solvent and then gradually volatilizing the solvent at a predetermined temperature. However, this method not only takes too much time for single crystal growth, but also has difficulty in controlling the processes required to grow high quality single crystals. These problems ultimately lead to an increase in the cost of single crystal growth, which makes it an obstacle to industrial use of single crystal.

In addition, the conventional organic material single crystal growth method has a problem in that impurities are not easily removed. Therefore, in order to obtain high-purity single crystals, the organic materials must be first purified to high purity by a method such as the sublimation purification method disclosed in HJ Wagner, el al., Journal of Materials Science, 17, 2781 (1982), and then single crystal growth is performed. There was a hassle.

Therefore, there is a need for a new method that can solve various problems of the prior art and grow single crystals while simultaneously purifying organic materials in a low cost and simple process.

An object of the present invention is to provide a novel organic material single crystal growth method and apparatus that can solve the problems of the conventional purification method as described above.

Specifically, it is an object of the present invention to provide a single crystal growth method and apparatus capable of growing a high-purity organic material single crystal of 99% or more, preferably 99.5% or more, and more preferably 99.9% or more by only one process.

In addition, another object of the present invention is to provide a single crystal growth method and apparatus capable of efficiently growing high-purity organic single crystal at low cost.

It is another object of the present invention to provide a single crystal growth method and apparatus which is easy to design and control and can cope with various organic materials.

Organic material single crystal growth method according to an aspect of the present invention for achieving the above object, the mixing step of mixing the organic material with the ionic liquid; A solution step of liquefying an organic material mixed with the ionic liquid by heat treatment under a first condition; Nucleating step of seeding the ionic liquid including the liquefied organic material under a second condition and nucleating the seed surface; A single crystal growing step of growing the single crystal under the third condition; And a separation step (S50) of separating the grown organic material single crystal from the ionic liquid, thereby obtaining a purified organic material single crystal with higher purity than before mixing with the ionic liquid. In this case, the first condition, the second condition, or the third condition may be a condition that changes with time.

In the present invention, the seed introduced into the ionic liquid may be a single crystal or a hollow microtube of the same material as the organic material to be crystallized, and the solution may be at least one of melting or melting.

Further, by performing the mixing step, the solution step, the nucleation step, the single crystal growth step and the separation step once, a high purity single crystal organic material of 99% or more can be obtained, and the organic material single crystal separated from the ionic liquid It may further comprise the step of washing and drying.

After the separation step, a sweating process may be further performed to remove surface impurities of the separated organic material single crystal, and the filtering step may be performed to filter out unliquefied organic material between the solution step and the nucleation step. You can proceed further.

Organic material single crystal growth apparatus according to another aspect of the present invention, the stage; A container body supported by the stage and containing a mixture of organic material and ionic liquid; A temperature control unit for heating the mixture of the organic material and the ionic liquid contained in the container body; And a seed holder having a seed fixed to an end thereof, the seed being introduced into a mixture of an organic material and an ionic liquid contained in the container body, wherein the container body and the seed holder are relatively movable.

Here, the seed may be a single crystal or a hollow microtube of the same material as the organic material, and the relative movement may be at least one of vertical movement and rotational movement.

In addition, a gas inlet for introducing gas into the container body; And a gas discharge part for discharging gas from the inside of the container body.

The organic material single crystal according to another aspect of the present invention may be grown by any one of the above-described methods, the X-ray half-value width may be 0.1 ^o or less.

According to the present invention, by using a method of growing a single crystal after mixing and liquefying an organic material in an ionic liquid, there is an effect that can solve various problems with the conventional purification method.

Specifically, there is an effect capable of growing the organic material single crystal with high purity of 99% or more, preferably 99.5% or more, and more preferably 99.9% or more by only one process.

Moreover, according to this invention, there exists an effect which can grow a high purity organic material single crystal efficiently at low cost.

In addition, according to the present invention, there is an effect that the process design and control is easy and can cope with various organic materials.

1 is a main flowchart of a method for growing an organic material single crystal using an ionic liquid according to the present invention.

2 is an example of a temperature change curve for carrying out the organic material single crystal growth method according to the present invention.

3 is a schematic cross-sectional view of an organic material single crystal growth apparatus according to the present invention.

4 is an exemplary diagram using a micro tube for self-seed formation.

Figure 5 (a) is an XRD analysis of the NPB single crystal grown in accordance with the present invention, Figure 5 (b) is an XRD analysis of the NPB polycrystalline.

6 (a) shows the XRD analysis of the Alq3 single crystal grown in accordance with the present invention, and FIG. 6 (b) shows the XRD analysis of the Alq3 polycrystal.

Figure 7 (a) is an Alq3 single crystal grown in accordance with the present invention, Figure 7 (b) is a scanning electron micrograph of the Alq3 polycrystals.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. The following description includes specific embodiments, but the invention is not limited or limited by the described embodiments. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

In the organic material single crystal growth method according to the present invention, a single crystal is grown in an ionic liquid, and the organic material is liquefied by heat treatment under a first condition, followed by single crystal growth under a second condition. It is characterized in that to grow a single crystal of high purity organic material through the process of introducing a seed (Seed) for generating a single crystal nucleus, and then growing a single crystal under a third condition. Herein, the first, second and third conditions mean process conditions such as temperature, pressure, and process atmosphere.

Ionic liquid refers to a liquid composed of only ions, and is generally a molten salt composed of a large cation and a smaller anion. The ionic liquid is not particularly limited but includes cations constituting the ionic liquid. The cation of 1] can be used. In Formula 1, R1, R2, R3, and R4 may be an alkyl group having n linear or branched carbon atoms.

[Formula 1]

Further, the anion constituting the ionic liquid with the cation is ^{^{_{Cl -, Br -, NO 3}}} -, BF 4 -, PF 6 -, AlCl 4 -, Al 2 Cl 7 -, AcO -, CH 3 COO -, CF _{^{_{_{3 COO -, CH 3 SO 3}}}} -, CF 3 SO 3 -, (CF 3 SO 2) 2 N -, (CF 3 SO 2) 3 C -, (CF 3 CF 2 SO 2) 2 N -, C 4 _{_{^{_{F 9 SO 3 -, C 3}}}} F 7 COO -, (CF 3 SO 2) (CF 3 CO) N -, C 4 F 10 N -, C 2 F 6 NO 4 S 2 -, C 2 F 6 NO 6 _{^{_{_{S 2 -, C 4 F 10}}}} NO 4 S 2 -, CF 3 SO 2 -, C 4 F 9 SO 2 -, C 2 H 6 NO 4 S 2 -, C 3 F 6 NO 3 S -, CH 3 CH (OH) CO ₂ ^- may be one of the anion and the like.

Due to its structural characteristics, ionic liquids have a low melting point and have a very low vapor pressure and thus exist as a stable liquid over a wide temperature range. In addition, it has excellent thermal stability and ion conductivity, can dissolve various hydrophilic and hydrophobic organic materials, inorganic materials, and high molecular materials, and is low in volatility, flame retardancy, and low explosiveness, making it an environmentally friendly material compared to general organic solvents.

Referring to FIG. 1, a method of growing an organic material single crystal according to an embodiment of the present invention is a mixing step (S10) of mixing an organic material to be grown single crystal with an ionic liquid, followed by heat treatment under a first condition to organic in ionic liquid. Solution liquefaction step (S20) to liquefy the material, the seed is added to the ionic liquid containing the organic material liquefied at the second condition and nucleation step (S30) to generate nuclei on the seed surface, single crystal at the third condition A single crystal growth step (S40) for growing a and a separation step (S50) for separating the grown organic material single crystal from the ionic liquid.

More specifically, first, the mixing step (S10) of mixing the organic material with the ionic liquid is a step of mixing the organic material to be grown single crystal into the ionic liquid. At this time, the agitation may be performed by mechanical stirring, magnetic stirring, or the like so that the organic material in the solid state may be more uniformly mixed with the ionic liquid. The organic material is an organic material intended to grow high purity single crystals using the method according to the present invention, but the material is not specifically limited, but the electron injection layer, the electron transport layer, the hole injection layer and the hole transport of the organic EL device. It is preferable that it is a conductive organic material used for a layer, a light emitting layer, the light absorption layer of an organic photoelectric conversion element, the organic semiconductor layer of an organic semiconductor element, etc. In addition, the organic material mixed with the ionic liquid may be a low purity organic material containing impurities.

The ionic liquid may also be appropriately selected depending on the organic materials to be mixed. In particular, imidazolium based ionic liquids having long alkyl substituents are suitable as the ionic liquid of the present invention. Eg 1-octyl-3-methylimidazolium trifluoromethylsulfonylimide [l-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide] (hereinafter abbreviated as '[Omim] [TFSI]'), L-butyl-3-methylimidazolium trifluoromethylsulfonylamide [l-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide], 1-ethyl-3-methylimidazolium trifluoromethylsulfonylamide [(l-Ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide], 1-decyl-3-methylimidazolium trifluoromethylsulfonylamide [1-Decyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide], 1- Dodecyl-3-methylimidazolium trifluoromethylsulfonylamide [1-Dodecyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide] and the like can be used.

The ionic liquid can be used in a myriad of combinations of theoretically 10 ¹⁸ by the combination of cations and anions, and thus can cope with various organic materials. That is, it is possible to select and use an ionic liquid having suitable characteristics according to the organic material to grow high purity single crystal. In particular, most of the commercially available conductive organic materials such as conductive organic materials for organic electroluminescent devices have similar basic structure and polarity, and since some of the reactors are substituted based on the basic structure, similar crystallization behavior appears. Even without designing various ionic liquids, the single crystal growth method according to the present invention can be used for various conductive organic materials by optimizing process conditions using some ionic liquids such as [Omim] [TFSI].

After mixing the organic material and the ionic liquid, a heat treatment under the first condition is performed to solution solution (S20) to liquefy the organic material in the ionic liquid. Solution may mean dissolution or melting, and may also be a mixture of dissolution and melting. Whether dissolution or melting is the main mechanism of solution can be determined depending on the organic material and the ionic liquid pair and the first condition. The first condition refers to a heat treatment process condition such as a first temperature, a first pressure, and a first atmosphere condition, and may be a condition that varies with time rather than any fixed condition. For example, the organic material may be liquefied while mixing the organic material and the ionic liquid while maintaining the predetermined temperature at the first temperature, or may be liquefied while changing the temperature at a predetermined rate. Also, the first condition does not require to be uniform depending on the position. For example, a container in which an organic material and an ionic liquid are mixed may be heat-treated to produce a predetermined temperature gradient depending on the position.

Since the organic material must first be liquefied in the ionic liquid for single crystal growth, the first condition for high process yield is at least 80%, preferably at least 90%, more preferably of the organic material mixed in the ionic material. Can be set to a condition that substantially totally liquefies, and this can be achieved by setting the first temperature condition to a high temperature sufficient for the total amount of organic material to be liquefied.

After the solution step (S20), the seed is added to the ionic liquid containing the liquefied organic material and the nucleation step (S30) for generating a nucleus on the seed surface is performed. Injecting the seed here does not necessarily mean that the seed is completely submerged in the ionic liquid, but it is to be understood that at least a portion of the seed is in contact with the ionic liquid.

The nucleation step is carried out under a second condition, which may be a condition in which nucleation of organic material crystals is easily performed at the seed surface. For example, if the main mechanism of solution is dissolution, the second condition may be a condition of temperature lower than the first condition. In the case of an organic material having low solubility at low temperature, a driving force for crystallization is increased under the second condition, which is lower than the first condition, so that nucleation can be easily performed on the seed surface. In addition, when the main mechanism of solution is melting, the second condition may be a condition of higher temperature than the first condition. Depending on the organic material-ionic liquid pair, the driving force for crystallization may be increased at a higher temperature than the melting temperature, so that nucleation can be easily performed on the seed surface at a second condition at a temperature higher than the first condition.

On the other hand, the second condition does not necessarily mean a fixed condition, but may be a condition that changes with time. That is, although the nucleation may be induced while maintaining the temperature at a lower or higher temperature after the heat treatment under the first condition, the nucleation may be performed while the temperature is gradually decreased or increased. Also, the second condition does not require to be uniform depending on the position. For example, a predetermined temperature gradient may be generated depending on the seed injection direction.

The seed may be a high purity single crystal of the same material as the molten organic material, or may use a hollow microtube for self-seed formation. In the case of using a microtube, the molten organic material may crystallize as the seed is raised by the capillary phenomenon to the hollow portion of the microtube, so that the diameter of the hollow region of the microtube may be 800 μm or less.

After the nucleation step (S30) to perform a single crystal growth step of growing a single crystal in the third condition (S40). Here, the third condition refers to process conditions for growing single crystals of an organic material liquefied in an ionic liquid, such as a third temperature, a third pressure, and a third atmospheric condition, and depending on the time rather than any fixed condition. It may be a changing condition. Also, the third condition does not require to be uniform depending on the position. For example, a predetermined temperature gradient may be generated depending on the seed injection direction.

The third condition may be a condition in which at least one of the first condition and / or the second condition is different from the temperature, the pressure, and the atmosphere, and the pressure and the atmosphere are preferably the same and the temperature is different. The third temperature may be lower than the first or second temperature if the main mechanism of solution is dissolution, and the third temperature is higher than the first or second temperature if the main mechanism of solution is melting. Can be.

On the other hand, in the nucleation step (S20) and / or single crystal growth step (S30) it is possible to move the injected seed relative to the container containing the organic material and the ionic liquid. Here, the relative movement may include rotation or vertical movement. For example, the seed may be moved upwards at a speed of 2 mm or less while rotating the seed at a speed of 9 rph or less, and in this process, single crystals may be grown from the seed.

Meanwhile, in the above description, an example of liquefying an organic material and growing a single crystal by varying the temperature has been described, but the solution and the monocrystallization of the organic material are induced by changing the pressure instead of the temperature or changing both the temperature and pressure. You may.

In the single crystal growth step (S30), since the organic material dissolved or melted in the ionic liquid is precipitated as a high purity single crystal in which impurities are excluded, when the organic material single crystal is separated from the ionic liquid containing impurities, the organic material is highly purified. A single crystal can be obtained (S50).

Although only up to step S50 is shown in FIG. 1, a process of washing and drying the organic material single crystal separated from the ionic liquid may be further performed. In order to remove impurities contained in the surface of the organic material single crystal, the surface may be heated or heated to an appropriate temperature. Sweating processes, such as melting only a portion slightly, can be further performed. In addition, when the organic material mixed in the ionic liquid is grown in the solution state (S20) in which the entire solution is not liquefied and partially dissolved or melted, the low-purity organic material is high purity in the separation step (S50) Since it may be mixed with the single crystal, a filtering step for filtering the unliquefied organic material may be further performed between the solution step (S20) and the nucleation step (S30).

At a high temperature at which a large amount of organic materials are dissolved or melted, general organic solvents are highly volatile and do not exist in a stable liquid phase, and even in the presence of liquids, the ratio with organic materials is not kept constant. Impurity mixing due to the reaction with, etc. becomes a problem. On the other hand, the ionic liquid can be heat-treated to a relatively high temperature due to the wide temperature range that is stably present as a liquid, so that a large amount of organic materials can be dissolved or melted, and there is little change in properties even at such high temperatures. Since the amount of the organic material to be dissolved or melted eventually affects the single crystal process yield, it is possible to grow the organic material single crystal at low cost according to the present invention in which the single crystal is grown using the ionic liquid.

In particular, according to the present invention, by growing a single crystal using an ionic liquid, high-purity single crystal growth is possible without undergoing a prior purification process. According to the embodiments described later, the organic material single crystals could be grown with high purity of 99.9% or more by only one step of growing a single crystal after liquefying a low purity organic material in an ionic liquid.

In addition, the ionic liquid has a very low vapor pressure, so that the ratio of the ionic liquid to the organic material is maintained even at high temperature, so that the process design and control is easy, and the chemical stability is also negligible. . These effects are characteristics that cannot be expected in the conventional single crystal growth method using a general organic solvent.

2 is an example of a temperature change curve for carrying out the organic material single crystal growth method according to the present invention. Referring to FIG. 2, after the organic material is mixed with the ionic liquid, the organic material is liquefied by raising the temperature to the first temperature T1 at a predetermined rate and maintaining the predetermined time (t2-t1). The first temperature can be set to a temperature at which the organic material can be liquefied as much as possible according to the combination of the organic material and the ionic liquid, and the liquefaction temperature of the organic material can be greatly reduced by using the ionic liquid. Can be. In addition, since the mixed organic material may contain low-quality initial crystals, it is preferable to set the time to maintain the first temperature T1 to a time sufficient to allow the entire amount of the organic material including the initial crystals to be liquefied.

After the holding time at the first temperature T1 is completed, the temperature is lowered to a second temperature T2, which is a single crystal growth temperature after seed injection, at a predetermined speed, and the predetermined time t4-t3 is maintained at the second temperature T2. Let's do it. The single crystal growth rate and the grown single crystal quality may be different according to the second temperature T2, and the purity of the crystal may vary. In order to form a high purity single crystal, it is preferable that the second temperature T2 is as high as possible. Meanwhile, since nucleation and single crystal growth proceed while the temperature is lowered at the first temperature T1 at the second temperature T2 or while the temperature is maintained at the second temperature T2, the time maintained at the second temperature T2 is It is desirable to set the time sufficient to allow the solutiond organic material to be crystallized mostly.

After the single crystal growth is performed at the second temperature T2, the temperature may be lowered at a predetermined speed and the separation step S50 may be performed.

The temperature change curve of FIG. 2 is merely an example, and the present invention is not limited thereto. For example, instead of maintaining a predetermined time at the first temperature for the solution of the organic material, the solution may be liquefied in the process of raising the temperature to the first temperature at a predetermined rate, in which case the temperature increase rate is relatively small. good. In addition, in FIG. 2, although the second temperature is lower than the first temperature, the second temperature may be higher than the first temperature, and in the process of changing the temperature at a predetermined speed instead of maintaining the predetermined temperature at the second temperature Single crystal growth can also be achieved. The temperature at which the mixing step (S10) and the separating step (S50) are performed is not limited to room temperature, for example, an organic material may be mixed with the ionic liquid at the first temperature (T1).

According to the organic material single crystal growth method according to the present invention described above, since the organic material is mixed and liquefied in the ionic liquid, the seed is added and the single crystal growth is carried out. Can grow. In particular, as described in the Examples, the method according to the present invention enables high-purity single crystal growth up to 99.9% or more with only one process.

In addition, such a process using an ionic liquid can be made in a short time at atmospheric pressure or low vacuum, and there is almost no loss of raw materials, so the process yield is high, which is advantageous in terms of cost compared to conventional single crystal growth or purification methods.

The present invention also has an advantageous effect in terms of ease of design and control of process conditions. That is, general organic solvents have high volatility, so they are difficult to apply to organic materials requiring high temperature for solution, and the organic solvents are volatilized during heat treatment, so that the process does not proceed as designed, such as uniform nucleation. The soluble liquid is compatible with most organic materials and exists not only in the liquid phase over a wide temperature range but also chemically stable, so that the mixing ratio of the ionic liquid and the organic material remains substantially the same during the heat treatment process.

3 is a schematic cross-sectional view of an organic material single crystal growth apparatus according to another aspect of the present invention. Referring to FIG. 3, the organic material single crystal growth apparatus 100 according to the present invention includes a stage body 110, a container body 120 supported by the stage, in which a mixture 200 of an organic material and an ionic liquid is accommodated. ), A temperature control unit 130 provided around the container body 120 to heat the mixture 200 of the organic material and the ionic liquid, and a gas inlet unit for introducing gas into the container body 120. 140, a gas discharge part 150 for discharging gas from the inside of the container body 120, a container cover 160 for covering and sealing the container body 120, and a seed holder for fixing the seed 310. And 300.

More specifically, the stage 110 may be configured to enable vertical movement and / or rotational movement as a configuration for supporting the container body 120. The container body 120 accommodates therein an ionic liquid mixed with an organic material for growing single crystals. The container body 120 may be formed of a material having excellent heat resistance, such as ceramic, and is preferably formed of a material that does not react with the ionic liquid and the organic material at high temperature. The temperature control unit 130 is configured to heat the organic material to liquefy the ionic liquid, and may be a resistance heating heater. In FIG. 3, the temperature controller 130 is illustrated as a coil-type heater that wraps around the container body 120, but the shape, type, and installation position of the temperature controller 130 are not limited thereto. The temperature controller 130 may be a heater capable of heating up to 400 ° C. or higher, and may be designed such that a temperature gradient is constant in all directions of the container body 120.

The gas inlet 140 and the gas outlet 150 are configured to control the gas atmosphere inside the container body 140. For example, the gas inlet 140 may be connected to an inert gas supply source such as nitrogen or argon to maintain the inside of the container body 140 in an inert gas atmosphere. The gas discharge unit 150 may be connected to a vacuum pump so that the process may be performed while maintaining the inside of the container body 140 in a vacuum atmosphere. In order to maintain the atmosphere or pressure inside the container body 140, it is necessary to form a sealed space. The container cover 160 covers the upper portion of the container body 140 to form a sealed space.

The seed holder 300 is configured to inject the seed into the ionic liquid by fixing the seed 310 at an end thereof, and may be configured to enable vertical movement and / or rotational movement. The seed 310 may be a high purity single crystal of the same material as the organic material to be grown single crystal.

Meanwhile, instead of fixing the seed 310 at the end of the seed holder 300, a micro tube for self-seed formation may be fixed and introduced into the ionic liquid, which is illustrated in FIG. 4. As shown in FIG. 4, the hollow microtube 320 is fixed to the end of the seed holder 300 instead of the seed 310, and the diameter of the hollow region may be 800 μm or less. When the microtube is injected into the ionic liquid in which the organic material is liquefied, the organic material solution may rise to the hollow region of the microtube by the capillary phenomenon and may be crystallized by a minute temperature difference to form the seed 330. As such, when the microtube is used, the organic material single crystal may be grown without a separate single crystal seed 310.

In the single crystal growth step, the container body 12 and the seed holder 300 may be relatively moved in the vertical direction or the rotation direction, and the vertical movement speed may be 2 mm or less per hour, and the rotational speed may be 9 rph or less. In FIG. 3, both the stage 110 and the seed holder 300 are shown to be capable of vertically moving and rotating. However, only one of the stage 110 and the seed holder 300 may be configured to vertically move or rotate.

It is to be understood that the apparatus of FIG. 3 is exemplary and that the organic material single crystal growth apparatus according to the present invention is not limited to the configuration of FIG. 3. Some components of FIG. 3 may be omitted or changed, or configurations not shown in FIG. 3 may be added. For example, the container body 120 or the container cover 160 may be provided with a measuring unit that can measure the process conditions, such as temperature, pressure, and control the temperature control unit 130 by receiving the measurement results of the measuring unit A control device may be provided.

Hereinafter, a result of growing a high-purity organic material single crystal using an ionic liquid according to the present invention will be described through examples.

<실시예 1><Example 1>

Example 1 is N, N′-bis- (1-naphyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine, which is a conductive organic material used as a material of the organic EL device. (Hereinafter abbreviated as 'NPB') is an example of single crystal growth using [Omim] [TFSI] ionic liquid. The chemical formula of NPB is shown below in [Formula 2].

[Formula 2]

Scanning Electron Microscope (SEM) observations showed that the NPB particles before mixing with the ionic liquid had an amorphous shape of about 1 to 2 μm, and HPLC (High Performance Liquid Chromatography) analysis showed a low purity of 82.4%.

The low purity NBP before purification was pulverized and mixed with the [Omim] [TFSI] ionic liquid at a mixing ratio of 10 wt%, and then 5 ° C./min from normal temperature to 260 ° C. in a heat treatment furnace maintained in an argon (Ar) gas atmosphere. NPB was liquefied at elevated temperature. Next, after the introduction of the microtube, the slow cooling to 10 ℃ / h to 230 ℃ to induce nucleation, isothermal heat treatment for 12 hours at 230 ℃ to grow a single crystal. The NPB single crystal formed was separated from the ionic liquid, washed with isopropyl alcohol (IPA) and dried in an oven at 60 ° C. for 24 hours to obtain final NPB crystals. The crystallinity of the crystal thus obtained was analyzed by X-ray diffraction (XRD; X-ray Diffractometry), and its purity was confirmed by HPLC.

FIG. 5 (a) shows the XRD analysis results of the NPB single crystal grown in Example 1, and the XRD analysis results of the NPB polycrystals are shown in FIG. 5 (b). As can be seen from FIG. 5, the excellent NPB single crystal with an X-ray half-value width of 0.1 ^o or less was grown by the method of the present invention. In addition, HPLC purity analysis showed that the grown NPB single crystal had a high purity of 99.92%. That is, according to the method of the present invention, it can be seen that a high purity NPB single crystal of 99.9% or more can be obtained through only one simple heat treatment process.

<실시예 2><Example 2>

Example 2 is an example in which tris- (8-hydroxyquinoline) aluminum (hereinafter, abbreviated as 'Alq3'), a conductive organic material used as a material of an organic EL device, is purified using [Omim] [TFSI] ionic liquid to be. Compared with Example 1, only the organic material was changed from NPB to Alq3, and the remaining process conditions were performed in the same manner. The chemical formula of Alq3 is shown below in [Formula 3].

[Formula 3]

FIG. 6 (a) shows the XRD analysis results of Alq3 single crystals grown in Example 2, and the XRD analysis results of Alq3 polycrystals are shown in FIG. 6 (b). As will be confirmed from FIG. 6, X-ray full width at half maximum by the method of the present invention are excellent in 0.1 ^o Alq3 was grown single crystal or less. Also, HPLC purity analysis showed that the grown Alq3 single crystal had high purity similar to that of NPB single crystal.

7 (a) and 7 (b) are scanning electron micrographs of Alq3 single crystals and Alq3 polycrystals grown in Example 2, respectively. From Fig. 7, it was confirmed that Alq3 polycrystals were needles of several micrometers or less in size, whereas crystal growth of several hundred micrometers or more was achieved after the single crystal growth process according to the present invention.

From the above results, it can be seen that using the single crystal growth method using the ionic liquid disclosed in the present invention, it is possible to grow an organic material into high purity single crystals of approximately 99.9% through only one simple and low-cost process. This is important because it overcomes the fundamental limitations of the conventional methods. In the embodiment, only the purification results of NPB and Alq3 are disclosed, but this is merely illustrative, and the single crystal growth method according to the present invention can be effectively applied to most organic materials used in organic electroluminescent devices, organic photoelectric conversion devices, organic semiconductor devices, and the like. . The reason why such an excellent effect is exhibited by the single crystal growth method using the ionic liquid is not fully understood. However, in the case of the conductive organic material used in the organic electroluminescent device, the composition and molecular weight are similar to the ionic liquid, so it is easy to mix. It can be presumed that the kinetics is very advantageous in solution and shows excellent behavior in crystallization.

Although described above with reference to the limited embodiments and drawings, this is only an embodiment, it will be apparent to those skilled in the art that various modifications are possible within the scope of the technical idea of the present invention. For example, it should be understood that the present invention does not exclude the use of a plurality of types of ionic liquids in admixture with or in combination with other solvents. Therefore, the protection scope of the present invention should be defined by the description of the claims and their equivalents.

Claims

Mixing the organic material with the ionic liquid;

A solution step of liquefying an organic material mixed in the ionic liquid by heat treatment under a first condition;

Nucleating step of seeding the ionic liquid including the liquefied organic material under a second condition and nucleating the seed surface;

A single crystal growing step of growing the single crystal under the third condition; And

A separation step of separating the grown organic material single crystal from the ionic liquid (S50);

Including,

A method of growing an organic material single crystal using an ionic liquid, characterized by obtaining an organic material single crystal purified at a higher purity than before mixing with an ionic liquid.
The method of claim 1,

And the seed is a single crystal or hollow microtube of the same material as the organic material.
The method of claim 1,

The method of growing an organic material single crystal using an ionic liquid, characterized in that the solution is at least one of melting or melting.
The method of claim 1,

The method of growing an organic material single crystal using an ionic liquid, characterized in that a high purity single crystal organic material of 99% or more is obtained by performing the mixing step, solution solution, nucleation step, single crystal growth step and separation step once.
The method of claim 1,

The method of growing an organic material single crystal using an ionic liquid, further comprising the step of washing and drying the organic material single crystal separated from the ionic liquid.
The method of claim 1,

The first, second or third condition is a condition that changes with time, the organic material single crystal growth method using an ionic liquid.
The method of claim 1,

After the separation step, a method of growing an organic material single crystal using an ionic liquid, characterized in that for further performing a sweating process for removing surface impurities of the separated organic material single crystal.
The method of claim 1,

Between the solution step and the nucleation step,

A method of growing an organic material single crystal using an ionic liquid, further comprising a filtering step for filtering out unliquefied organic material.
stage;

A container body supported by the stage and containing a mixture of organic material and ionic liquid;

A temperature control unit for heating the mixture of the organic material and the ionic liquid contained in the container body;

A seed holder having a seed fixed to an end thereof, the seed being introduced into a mixture of an organic material and an ionic liquid contained in the container body;

Including;

And said container body and said seed holder are movable relative to each other.
The method of claim 9,

And the seed is a single crystal or hollow microtube of the same material as the organic material.
The method of claim 9,

The relative movement is an organic material single crystal growth apparatus, characterized in that at least one of vertical movement and rotational movement.
The method of claim 9,

A gas inlet for introducing gas into the container body; And

The organic material single crystal growth apparatus further comprises a gas discharge unit for discharging gas from the inside of the container body.
An organic material single crystal grown by the method of any one of claims 1 to 8.
The method of claim 13,

X-ray full width at half maximum is 0.1 o organic single crystal material, characterized in that not more than.