KR101624610B1 - Method for purifying organic materials using ionic liquid - Google Patents

Abstract

The present invention relates to a method of purifying an organic material using an ionic liquid, comprising: providing an organic material for providing an amorphous organic material; A mixing step of mixing the amorphous organic material with an ionic liquid; an aggregation step of heat-treating and coagulating the amorphous organic material mixed with the ionic liquid at a first temperature; and an obtaining step of separating the aggregated organic material from the ionic liquid And a control unit. According to the present invention, an amorphous organic material can be purified at a low cost by a simple process, and the purified organic material can be easily obtained.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for purifying an organic material using an ionic liquid,

TECHNICAL FIELD The present invention relates to a method for purifying an organic material, and more particularly, to a purification method capable of purifying an organic material without crystallizing and easily obtaining a purified organic material.

2. Description of the Related Art As an example of using organic materials for electronic devices such as organic electroluminescence (EL) devices, organic semiconductor devices, organic photoelectric conversion devices, and organic sensor devices has been increasing, It is increasingly important to provide materials at low cost.

In particular, an organic electroluminescent device, such as an electron injection layer, an electron transfer layer, a hole injection layer, a hole transfer layer, an emission layer, The conductive organic material used for the light absorbing layer of the conversion element and the organic semiconductor layer of the organic semiconductor device has a serious adverse effect on the performance of the organic electronic device if impurities are contained therein. need.

Recently, a process for recovering and purifying conductive organic materials used in the production of organic electronic devices has also been developed. For example, an organic electroluminescent device is manufactured by evaporating conductive organic materials in a vacuum state and depositing them on a substrate, wherein the amount deposited on the substrate is less than 10% of the evaporated organic material, do. At this time, even if the conductive organic material attached to the surface of the processing apparatus is recovered by scraping or the like, various impurities are contained therein. Therefore, it is essential to refill the conductive organic material with high purity in order to reuse it.

(HJWagner, el al., Journal of Materials Science, 17, 2781 (1982)) discloses a method for mass-refining conductive organic materials of high purity used in the production of organic electronic devices such as organic electroluminescent devices, Is the sole use of the sublimation purification method. The sublimation purification method is a purification method using a difference between sublimation points of a conductive organic material and impurities contained therein, in which a conductive organic material disposed at one longitudinal end portion in a tube maintained in a vacuum state is sublimated And the conductive organic material is cooled in the other end region in the longitudinal direction inside the tube to be recrystallized, thereby obtaining a highly pure conductive organic material from which the impurities have been removed.

However, according to the sublimation purification method, the purified organic material deposited on the inner wall of the tube is recrystallized and must be scraped off by hand, so that it is not easy to obtain. Due to the pumping operation by the vacuum pump connected to the other end in the longitudinal direction of the tube, The conductive organic material is not deposited on the inner wall of the tube and is lost. In addition, the conductive organic material deposited on the inner wall of the tube is difficult to prevent the conductive organic material from being lost even in the process of collecting the conductive organic material not mixed with the impurities. As a result, There is a limit of 70%.

In addition, the sublimation purification method generally involves a complicated process such as the necessity of repeating the same process three times or more since a high-purity organic material can not be obtained in a desired degree by a single process. In addition, due to the nature of the meteorological method, high temperature, high vacuum, and long process time are required. In order to mass-purify, the sublimation purifier must be enlarged. Therefore, the purification efficiency is limited. There is a problem that a long period of process and equipment optimization is required until it is obtained. These problems ultimately lead to a cost increase. Therefore, the sublimation purification method has a limitation in refining organic materials at low cost.

As a purification method other than the sublimation purification method, there is a purification method using crystallization of an organic material. For example, as disclosed in Korean Patent No. 1363241, an organic material is dissolved in an organic solvent at a high temperature and then precipitated by recrystallization at a low temperature And the like. However, in the case of conductive organic materials, the types of soluble organic solvents are limited and even if they are soluble, they are very low in solubility, and there is a possibility that impurities may be contained due to reaction with an organic solvent during purification, and there is a limitation in purification purity and yield .

In general, the solubility of an organic material is approximately proportional to the temperature. Therefore, in order to precipitate a large amount of organic material by recrystallization, the temperature must be changed over a wide temperature range. The organic solvent has a temperature range in which the organic solvent has a low boiling point It is practically impossible to obtain purified water at a high yield even in view of its narrowness.

Even in the case of dissolving an organic material in an organic solvent and then melting it without recrystallization and then refining it by crystallization, the melting temperature of the conductive organic material is high in structure, and impurities are easily mixed in the purification process. There is a limit to the purity and yield that can be achieved.

Particularly, according to the method using such crystallization, a process such as filtering is required in order to separate the purified organic material crystals from the organic solvent, and there is a problem that this method can not be applied to amorphous organic materials which are difficult to induce crystallization .

Korean Patent No. 10-1363241

H. J. Wagner, el al., Journal of Materials Science, 17, 2781 (1982)

It is another object of the present invention to provide a novel organic material purification method capable of solving the problems of the conventional methods as described above and more specifically to an organic material purification method capable of purifying an organic material without crystallization .

Another object of the present invention is to provide an organic material purification method capable of purifying an organic material with a high yield and easily obtaining a purified organic material.

It is still another object of the present invention to provide an organic material purification method capable of purifying an amorphous organic material.

It is another object of the present invention to provide a purification method in which ionic liquids can be easily reused by minimizing the deterioration of the ionic liquid used in purification.

According to an aspect of the present invention, there is provided an organic material refining method comprising: providing an organic material for providing an amorphous organic material to be refined; mixing the amorphous organic material with an ionic liquid; And a step of subjecting the mixed amorphous organic material to heat treatment at a first temperature for coagulation, and a step for separating the aggregated organic material from the ionic liquid. Here, the amorphous organic material may be an amorphous organic material, and the amorphous organic material does not show a crystal peak when heated at a rate of 10 ° C / min using a differential scanning calorimeter (DSC) under atmospheric pressure in a nitrogen atmosphere Organic material.

The first temperature is a temperature higher than the glass transition temperature (Tg) of the organic material, and the glass transition temperature (Tg) is a temperature at which the amorphous organic material is heated at a temperature of 10 [deg.] C / min, or the first temperature may be a temperature at which crystallization of the organic material does not occur in the ionic liquid.

Further, the organic material refining method according to the present invention may further include washing and drying the separated organic material crystals after the separating step.

Further, the ionic liquid may be an imidazolium-based ionic liquid, and the ionic liquid may have 12 or less alkyl groups.

Further, in the organic material refining method according to the present invention, the yield of the purified organic material may be 70% or more.

According to the present invention, it is possible to purify an organic material without crystallizing it by using a method of mixing an amorphous organic material into an ionic liquid and then subjecting it to heat treatment and coagulation.

Further, according to the present invention, it is possible to purify an organic material with a high yield, and to obtain a purified organic material easily.

According to the present invention, an amorphous organic material can be purified.

According to the present invention, the heat treatment is performed at a low temperature at which the change in physical properties of the ionic liquid, which is a medium used for purification, is suppressed to the utmost, whereby the ionic liquid used for purification can be easily reused.

1 is a flow chart of a method for purifying an organic material using an ionic liquid according to the present invention.
2 is a schematic configuration diagram showing the organic material refining apparatus according to the present invention by functional blocks.
FIG. 3 shows differential scanning calorimetry (DSC) results of the HTL samples used in Examples and Comparative Examples of the present invention.
FIG. 4 is a result of observing the shape of the HTL sample aggregated after the heat treatment in the Emim ionic liquid according to the embodiment of the present invention.
FIG. 5 is a result of observing the shape of the HTL sample aggregated after heat treatment in a Dodecyl ionic liquid according to an embodiment of the present invention.
Figure 6 shows the result of XRD analysis of the HTL agglomerate of Figure 5 (b)
Figure 7 is the result of the yield of HTL agglutinates obtained according to an embodiment of the present invention.
Figure 8 shows the yield results for the weight percent of HTL samples mixed in the Dodecyl ionic liquid.
FIG. 9 shows differential scanning calorimetry (DSC) results of HTL agglomerates according to the heat treatment temperature.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the embodiments of the present invention. The following description includes specific embodiments, but the present invention is not limited to or limited by the embodiments described. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The method for purifying an organic material according to the present invention is characterized in that an amorphous organic material is mixed with an ionic liquid and then heat-treated at a first temperature and then purified by coagulation in an ionic liquid.

The ionic liquid refers to a liquid composed of only ions, and is generally a molten salt which is composed of a large cation and a smaller anion, and is not particularly limited, but the cation constituting the ionic liquid includes the following [ 1] can be used. In formula (1), R 1, R 2, R 3 and R 4 may be linear or branched alkyl groups having n carbon atoms.

 [Chemical Formula 1]

In addition, the anions constituting the ionic liquid together with the cations include Cl ^- , Br ^- , NO ₃ ^- , BF ₄ ^- , PF ₆ ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , AcO ^- , CH ₃ COO ^{- _{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 ^-, and the like.

The ionic liquid has a low melting point due to its structural characteristics and has a very low vapor pressure and is present as a stable liquid in a wide temperature range. In addition, it is excellent in thermal stability and ionic conductivity, can dissolve various organic, inorganic and polymeric substances having hydrophilic and hydrophobic properties, is low in volatility, low in flammability, and low in explosibility, thus being environmentally friendly.

1 is a flow chart of a method for purifying an organic material using an ionic liquid according to the present invention.

1, a method of purifying an organic material according to the present invention will now be described with reference to FIG. 1. Referring to FIG. 1, there is provided a method for purifying an organic material comprising: providing an organic material for providing an amorphous organic material to be purified (S110); mixing the amorphous organic material with an ionic liquid An aggregating step (S130) of heat-treating and aggregating the organic material mixed with the ionic liquid at a first temperature, and a step (S140) of separating the aggregated organic material from the ionic liquid.

More specifically, the organic material provided in the organic material providing step (S110) is an amorphous organic material to be purified using the method according to the present invention, and the material thereof is not specifically limited, An electron injection layer, an electron transport layer, a hole injection layer, a hole transport layer, a light emitting layer, a light absorbing layer of an organic photoelectric conversion element, an organic semiconductor layer of an organic semiconductor device, or the like.

Further, the amorphous organic material may be an amorphous organic material which is difficult to induce crystallization. Here, the amorphous organic material may be an organic material in which a crystallization peak is not observed when the temperature is elevated at a rate of 10 ° C / min by using differential scanning calorimetry (DSC) under atmospheric pressure in a nitrogen atmosphere, for example.

The mixing step (S120) is a step of mixing the provided amorphous organic material into the ionic liquid. At this time, stirring may be performed using a magnetic bar so that the organic material can be more uniformly mixed with the ionic liquid.

The ionic liquid may be appropriately selected according to the organic material to be purified, and an imidazolium-based ionic liquid having a long alkyl substituent is suitable as the ionic liquid of the present invention. For example, 1-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (hereinafter abbreviated as 'Omim'), 1-butyl- Methylimidazolium bis (trifluoromethylsulfonyl) imide] (hereinafter abbreviated as 'Bmim'), 1-ethyl-3-methylimidazolium triflor 3-methylimidazolium bis (trifluoromethylsulfonyl) amide (hereinafter abbreviated as 'Emim'), 1-decyl-3-methylimidazolium trifluoromethylsulfonylamide [1-Decyl 3-methylimidazolium bis (trifluoromethylsulfonyl) amide] (hereinafter abbreviated as 'Decyl'), 1-dodecyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide] (hereinafter abbreviated as 'Dodecyl') may be used.

The ionic liquid can cope with a variety of organic materials because of the myriad combinations of up to 10 ¹⁸ theoretically due to the combination of cations and anions. That is, it is possible to select and use an ionic liquid having properties suitable for the organic material to be purified.

After the amorphous organic material and the ionic liquid are mixed, an aggregation step (S130) is performed in which the amorphous organic material mixed with the ionic liquid is heat-treated at a first temperature and agglomerated. Here, the first temperature is not limited to a specific temperature as long as it is the temperature at which aggregation of the organic material occurs. However, it is preferable that the ionic liquid is easily reused by suppressing the change of physical properties of the ionic liquid as much as possible during the heat treatment. It is preferable that the temperature is as low as possible. However, the first temperature should be at least above the temperature at which agglomeration occurs. For example, in the present invention, the first temperature may be higher than the glass transition temperature (Tg) of the amorphous organic material, wherein the glass transition temperature (Tg) is measured using a differential scanning calorimeter (DSC) Lt; RTI ID = 0.0 > 10 C / min. ≪ / RTI >

Especially when the first temperature is set to be lower than the glass transition temperature (Tg) in the case of amorphous organic material, as described in the following embodiments, the organic material in the ionic liquid may be crystallized rather than aggregated have. Therefore, it is particularly preferable to set the first temperature to the glass transition temperature (Tg) or higher in order to coagulate and purify a specific amorphous organic material.

Conditions for carrying out the flocculation step (S130) other than the temperature condition are not particularly limited. Flocculation step (S130) in accordance with the present invention as will be described in Examples below may proceed in a nitrogen (N ₂₎ atmosphere of normal pressure, it may take place in a vacuum environment.

After the flocculation step (S130), an obtaining step (S140) of separating the flocculated organic material from the ionic liquid in the ionic liquid proceeds. According to the present invention, an organic material can be easily separated from an ionic liquid since it aggregates in a lump form in an ionic liquid. For example, the organic material agglomerated in the ionic liquid may be taken out by a suitable means such as tweezers, or the ionic liquid may be discharged in another vessel. The method of separating the organic material aggregate from the ionic liquid is not limited thereto, and it is obvious that various methods can be used. Also, after the flocculation step (S130), the organic material may not exist only as an aggregate in the ionic liquid. In this case, the obtaining step (S140) is not limited to separating only aggregates.

1, the organic material separated from the ionic liquid may be washed and then dried.

Although it is preferable that the mixing step (S120) and the obtaining step (S140) according to the embodiment of the present invention proceed at room temperature, it is not limited thereto. For example, mixing the organic material with the ionic liquid at the first temperature, It may be separated after heat treatment. In addition, the first temperature is not limited to a fixed temperature, but may be a temperature that changes with time.

According to the organic material refining method of the present invention described above, since the amorphous organic material is mixed in the ionic liquid and then heat-treated, the aggregate of the organic material is separated, so that the organic material can be purified by a simple and inexpensive process. Particularly, as described in Examples, the purification method according to the present invention makes it possible to crystallize an amorphous organic material which is difficult to purify through crystallization.

In addition, it is easy to obtain the purified organic material, and it is advantageous to obtain a high yield of 95% or more by optimizing the kind or mixing ratio of the ionic liquid according to the organic material to be purified. Further, since the temperature for heat treatment in the ionic liquid may be relatively low, the change in physical properties of the ionic liquid is minimized, and it is possible to repeatedly reuse the expensive ionic liquid.

In addition, such a process using an ionic liquid is advantageous in that it can be performed at a normal pressure in a short time, has little loss of a raw material, is a liquid phase process in which an organic material does not need to be sublimated, .

FIG. 2 is a block diagram showing an example of a purification apparatus that can be configured to perform the organic material purification method according to the present invention, according to functional blocks. 2, the refining apparatus according to the present invention comprises a mixing tank for mixing organic materials and ionic liquids to be purified from an organic material supply tank and an ionic liquid supply tank, respectively, And a heat treatment tank for heat-treating the mixed organic material and the ionic liquid. At this time, the measuring unit is connected to the heat treatment tank to measure conditions such as temperature and pressure, and the gas supply unit and the exhaust unit are connected to control the process atmosphere in which the heat treatment is performed. Also, although not shown, a vacuum pump may be connected to the heat treatment tank to exhaust the atmospheric gas supplied from the gas supply unit, and to adjust the pressure at which the heat treatment proceeds, and the vacuum pump may be included in the exhaust unit.

The heat-treated organic material is separated from the ionic liquid in the separation tank and transferred to the washing tank. The ionic liquid separated from the organic material removes the impurities contained in the ionic liquid preparation and can be recycled to the ionic liquid supply tank have. Further, the organic material transferred to the cleaning tank is washed using the cleaning liquid supplied from the cleaning liquid supply tank, and dried in the drying tank to obtain a final purified organic material, and the used cleaning liquid can be purified in the cleaning liquid cleaning process and recycled to the cleaning liquid cleaning bath .

Although not shown in FIG. 2, the purification apparatus according to the present invention may further include a control unit for controlling at least some of the entire processes according to a process recipe inputted by a user.

FIG. 2 is a functional block diagram of a purification apparatus according to the present invention, and thus may be different from a configuration of an actual apparatus, and a plurality of functions may actually be performed in one configuration. For example, the organic material or the ionic liquid may be directly introduced into the mixing tank without separately providing the organic material supply tank or the ionic liquid supply tank. Instead, the drying tank may be separately provided, . In addition, the functional blocks shown in FIG. 2 are not necessarily provided in the organic material purification apparatus according to the present invention, and it should be understood that the ionic liquid purifier or the cleaning liquid purifier, for example, may be omitted. In order to improve the productivity, it is preferable to arrange each functional block inline so that the processes can be sequentially performed.

Hereinafter, the organic material purification method and results according to the present invention will be described with reference to Examples and Comparative Examples.

1. Sample Preparation

In order to confirm the refining effect by the refining method according to the present invention, an HTL sample which is a conductive organic material used for an organic electroluminescent device (OLED) was prepared. The initial structure of the HTL sample was confirmed by X-ray diffraction (XRD). As a result, an amorphous crystal peak was not observed, and the initial purity was 99.5% by HPLC (High Performance Liquid Chromatography).

Differential scanning calorimetry (DSC) was also performed while the temperature was raised at a rate of 10 ° C / min in an atmospheric pressure nitrogen gas atmosphere. The results are shown in FIG. As shown in FIG. 3, the DSC thermal analysis showed that only a glass transition temperature (Tg) peak, which is an amorphous characteristic, was observed at about 133.1 ° C, and no other peak was observed.

2. Purification experiment

< Example >

The HTL samples were mixed in an ionic liquid at 10 wt%, and then heat treated in a tube furnace maintained in a nitrogen atmosphere for 1 hour. As the heat treatment temperature, 170 DEG C, which is higher than the glass transition temperature (Tg) shown in FIG.

After the heat treatment was completed, an aggregate of organic materials was obtained, washed with isopropyl alcohol (IPA), and dried at 50 DEG C for 1 hour to obtain a final purified sample .

As the ionic liquid, five ionic liquids having different numbers of alkyl groups were used as shown in [Table 1].

number Ionic liquid Number of alkyl groups Example 1 Emim 2 Example 2 Bmim 4 Example 3 Omim 8 Example 4 Decyl 10 Example 5 Dodecyl 12

< Comparative Example >

The same HTL sample as used in the examples was mixed with a heating medium oil (SG-THERM 700, SK Corp.) for a high-temperature heat exchanger instead of an ionic liquid, and then put into a tube furnace maintained in a nitrogen atmosphere and heat-treated at 170 ° C for 1 hour. The other conditions were the same as in the examples.

3. Coagulation and purification results

Fig. 4 is a result of Embodiment 1 of the present invention, in which the HTL material is aggregated after heat treatment in the Emim ionic liquid. Fig. 4 (a) shows the mixed state before the heat treatment, and Fig. 4 (b) shows that the HTL material aggregates into a large lump in the Emim ionic liquid in the shape after the heat treatment.

5 shows the results of Example 5 using Dodecyl as an ionic liquid. Fig. 5 (a) shows the mixed state before the heat treatment, and Fig. 5 (b) shows the shape after the heat treatment. As shown in FIG. 4 (b), it was confirmed that the HTL material was aggregated in the ionic liquid, but the size of the aggregate was smaller than that of FIG. 4 (b).

On the other hand, in the case of the comparative example in which the heat treatment was performed under the same conditions in the heat medium oil without using the ionic liquid, aggregation phenomenon of the HTL sample was not observed.

[Table 2] below shows the result of HPLC purity analysis of the final purified sample obtained from the aggregates of Figs. 4 (b) and 5 (b). Both Emim and Dodecyl ionic liquids were found to be purified to a high purity of 99.9% or more.

division Process condition water(%) Initial sample - 99.5 Example 1 Heat treatment after mixing with Emim (170 ° C, 1 hour) 99.95 Example 5 After mixing with Dodecyl, heat treatment (170 ℃, 1 hour) 99.93

6 shows the results of XRD analysis of the HTL agglomerate of Example 5. Fig. As can be seen in FIG. 6, after agglomeration by heat treatment at 170 ° C for 1 hour in Dodecyl ionic liquid, it was still amorphous as in the HTL initial sample. That is, according to the purification method of the present invention, the purification is performed without crystallization of the organic material, which is an unexpected result when the general purification principle in which impurities are separated in the crystallization process.

4. Yields according to ionic liquids

FIG. 7 is a graph showing the results obtained by measuring the mass of HTL agglomerates obtained according to Examples 1 to 5, wherein the abscissa is the number of alkyl groups in the ionic liquid and the ordinate is the yield. Here, the yield is the mass ratio of the organic material obtained as an aggregate to the mass of the organic material mixed with the ionic liquid.

7, the yield was about 96% for Emim with the number of alkyl groups of 2, and the yield decreased with increasing number of alkyl groups, resulting in a yield of about 70% for Dodecyl having 12 alkyl groups, The smaller the number of alkyl groups, the more aggregated the HTL organic material with the higher yield.

Meanwhile, the result of FIG. 7 was obtained by mixing 10 wt% of the HTL sample with heat treatment, regardless of the kind of the ionic liquid. Therefore, the change in the yield was observed while changing the weight% of the HTL sample mixed in the ionic liquid . FIG. 8 shows the results obtained by mixing the HTL sample at several weight% in a Dodecyl ionic liquid having an alkyl number of 12 and calculating the yield.

From Figure 8 it can be seen that the yield varies with the weight percent of the organic material, and when mixing the HTL organic material with the Dodecyl ionic liquid, a yield of about 80% is obtained when mixing at about 15% by weight lost. From this, it is expected that other ionic liquids other than Dodecyl will achieve better yields than the results of FIG. 7 when optimizing the weight percent of organic materials to be mixed.

5. Effect of heat treatment temperature (first temperature)

In the above example, the first heat treatment temperature was set to 170 캜, but it was experimentally determined whether the same coagulation phenomenon occurs even at a lower temperature. 3, the glass transition temperature (Tg) was found to be about 133.1 degrees. Therefore, it was found that the glass transition temperature was 120 ° C. below the glass transition temperature, 140 ° C. around the glass transition temperature, and 170 ° C. above the glass transition temperature , And the heat treatment time was 10 hours. Dodecyl was used as the ionic liquid.

As a result of the heat treatment, aggregates were formed similarly to FIG. 5 (b) after the heat treatment at 170 ° C., but after the heat treatment at 120 ° C., the aggregate was not formed and HTL powder was dispersed in the ionic liquid. Thereafter, a small amount of agglomerates were mixed with the powders.

9 is a result of DSC thermal analysis after separating the HTL sample heat-treated at each temperature from the ionic liquid. As a result, the glass transition temperature (Tg) peak of the sample annealed at 170 ° C showed only a peak of amorphous state. However, in the case of the sample annealed at 120 ° C, the peak of the glass transition temperature disappeared, Melting (Tm) peaks were observed, and as a result of XRD analysis (not shown), it was confirmed to be crystalline. From this, it can be seen that when heat-treated at 120 ° C, not crystallized in an amorphous form but dispersed in a powder form in an ionic liquid after crystallization. In addition, in the case of the sample heat treated at 140 ℃, the glass transition temperature (Tg) peak and the melting (Tm) peak of the crystal appeared together, which was consistent with that observed in a mixed form of a small amount of agglomerates and powders.

From this, it can be seen that it is important to set the first temperature to a specific temperature range in order to induce aggregates in the amorphous state by the purification method according to the present invention. In order to minimize the phenomenon of crystal formation without aggregation, the specific temperature range may be a temperature range higher than the glass transition temperature (Tg). Such crystallization and amorphous cohesion properties are contrary to the general expectation that crystallization is usually easier as the heat treatment temperature is higher.

From the above results, it can be seen that when the purification method using the ionic liquid disclosed in the present invention is used, it is possible to purify the amorphous organic material through a simple and low-cost process only once. Particularly, according to the present invention, the organic material is characterized in that the organic material is not crystallized but aggregated in an amorphous state to be purified. Thus, it is easy to obtain a purified organic material, and as in the HTL sample used in the examples, The amorphous organic material having difficulty in crystallization can be purified by the method of the present invention. In the case of the comparative example in which heat treatment was performed under the same conditions by mixing with the heat medium oil instead of the ionic liquid, aggregation did not proceed at all, and the effect of the present invention is not a simple heat treatment or a heat treatment effect in a solvent, Effect.

Further, according to the purification method of the present invention, it is possible to purify an organic material while performing heat treatment at a relatively low temperature not lower than the glass transition temperature (Tg) of the amorphous organic material. The characteristic that can be refined by such a heat treatment at a relatively low temperature is advantageous in that the ionic liquid is prevented from being denatured and reusable.

It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

In the embodiment, only the purification results for some conductive organic materials are disclosed. However, the purification method according to the present invention is not limited to the conductive organic materials used for the organic electroluminescent device, the organic photoelectric conversion device, and the organic semiconductor device, Can be effectively used for the purification of difficult low-molecular conductive organic materials, amorphous organic materials or other organic materials. Here, the organic material may also include a metal organic compound.

It should be understood that the present invention does not exclude the use of a mixture of a plurality of kinds of ionic liquids mixed with another solvent as an ionic liquid used for purification. Accordingly, the scope of protection of the present invention should be determined by the description of the claims and their equivalents.

Claims (9)

An organic material providing step of providing an amorphous organic material to be purified;
Mixing the amorphous organic material with an ionic liquid;
An agglomeration step of subjecting the amorphous organic material mixed with the ionic liquid to heat treatment at a first temperature to coagulate; And
A step of separating the aggregated organic material from the ionic liquid;
Wherein the ionic liquid is an organic material. The method according to claim 1,
Wherein the first temperature is higher than the glass transition temperature (Tg) of the organic material,
Wherein the glass transition temperature (Tg) is a glass transition temperature measured when the amorphous organic material is heated at a rate of 10 占 폚 / min using a differential scanning calorimeter (DSC) at normal pressure in a nitrogen atmosphere. A method for purifying an organic material using the method. 3. The method of claim 2,
Wherein the first temperature is a temperature at which crystallization of the organic material does not occur in the ionic liquid. The method according to claim 1,
Wherein the amorphous organic material is an amorphous organic material. 5. The method of claim 4,
Wherein the amorphous organic material is an organic material in which crystal peaks do not appear when the temperature of the amorphous organic material is raised at a rate of 10 ° C / min using a differential scanning calorimeter (DSC) under atmospheric pressure in a nitrogen atmosphere. Way. The method according to claim 1,
And washing and drying the separated organic material crystals after the separation step. The method according to claim 1,
Wherein the ionic liquid is an imidazolium-based ionic liquid. 8. The method of claim 7,
Wherein the ionic liquid has a number of alkyl groups of 12 or less. 8. The method of claim 7,
And the yield is 70% or more.

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