JP6843716B2 - Organic EL solution, organic EL device manufacturing method and organic EL device - Google Patents

Description

The present invention relates to a solution for organic EL, a method for producing an organic EL device, and an organic EL device.

In recent years, research and development of an organic electroluminescence (EL) device, which is a light emitting device utilizing the electroluminescence phenomenon of a solid fluorescent substance, has been progressing. Since the organic EL device emits light by itself, it has high visibility, and since it is a completely solid element, it has excellent impact resistance. The organic EL device is configured by laminating an organic layer including a light emitting layer that performs an electroluminescence phenomenon by recombination of carriers (holes and electrons) between electrode pairs of a pixel electrode (anode) and a common electrode (cathode). To. The organic layer is formed of an organic material and includes a carrier injection layer, a carrier transport layer, a carrier blocking layer, and the like in addition to the light emitting layer.

As an example of the method for producing the organic layer, there are a vapor deposition method and a coating method (see, for example, Patent Document 1). In the coating method, an organic material is dissolved in a solvent to form an ink (solution for organic EL), and the ink is coated on a substrate by a printing method (droplet ejection method) or the like. After coating, the solvent is evaporated from the ink and dried to form an organic layer. Therefore, in the coating method, it is not necessary to carry out the process in a vacuum vessel, which is preferable in terms of mass production.

Further, in the organic EL solution used for manufacturing an organic EL device, it is usually necessary to mix two or more kinds of organic solvents (see, for example, Patent Document 2) for stability of droplet ejection and after drying. It is said to be preferable in terms of flatness of the film shape and the like.

JP-A-2009-267299 Japanese Unexamined Patent Publication No. 2013-143324

By the way, in the step of applying the ink on the substrate by a printing method or the like, the ink comes into contact with the constituent members of the printing apparatus. Further, the ink applied on the substrate is brought into contact with another organic layer already formed on the substrate, a partition wall layer (bank structure) for avoiding mixing with inks of different colors, and the like.

However, the organic solvent contained in the ink includes an organic solvent that elutes a small amount of the constituent members of the printing apparatus and deteriorates the printing apparatus. There are also organic solvents that dissolve other organic layers and bulkhead layers to deteriorate the performance of the other organic layers and bulkhead layers. Further, there is also an organic solvent that elutes a small amount of components of the constituent members of the printing apparatus, the organic layer, and the partition wall layer to deteriorate the performance of the ink itself. Therefore, even if the ink comes into contact with the constituent members of the printing apparatus, other organic layers on the substrate, the partition wall layer, etc., they are required not to be dissolved and deteriorated, or the performance of the ink itself is not deteriorated. ing.

An object of the present invention is to provide a solution for organic EL that does not deteriorate the performance of the solution itself even when it comes into contact with a constituent member of a printing apparatus.

Another object of the present invention is a method for manufacturing an organic EL device having a structure in which an organic layer including a light emitting layer is sandwiched between two electrodes, by applying and drying using the above-mentioned organic EL solution. The present invention provides a method for manufacturing an organic EL device, which comprises a step of forming the organic layer.

Another object of the present invention is to provide an organic EL device in which the organic layer is formed by the method for manufacturing an organic EL device.

According to one embodiment of the present invention, it is a solution for organic EL in which an organic EL contributing material is dissolved in a mixed solvent of two or more kinds of organic solvents containing at least a first organic solvent and a second organic solvent. The coordinates (HSP coordinates) defined by the Hansen solubility parameter of the first organic solvent are Hd within the range of ^{17.5 to 19.5 (J / cm 3 ) 1/2} , 3.5 to 5.5 (Hd). J / cm ³ ) ^{Hp in the range of 1/2} and Hh in the range of 3.5 to 5.5 (J / cm ³ ) ^1/2 , and the HSP coordinates of the second organic solvent are 17. 5~19.5 ^{(J /} cm ³⁾ in the ^half of the range Hd, within the range of ^{0~2.0 (J / cm 3) 1/2} Hp and 0.5 to 2.5 (J / cm ³ ) A solution for organic EL that is Hh within the range of ^{1/2 is provided.}

FIG. 1 is a cross-sectional view of an organic EL display panel included in the organic EL device according to the embodiment of the present invention. FIG. 2 is a cross-sectional view showing a manufacturing process of the organic EL display panel shown in FIG. FIG. 3 is a top view of the organic EL display panel shown in FIG. 1 at the time of manufacture. FIG. 4 is a schematic block diagram showing a schematic configuration of an organic EL device including the organic EL display panel shown in FIG. 1.

In the organic EL solution according to the embodiment of the present invention, the organic EL contributing material is dissolved in a mixed solvent of two or more kinds of organic solvents containing at least a first organic solvent and a second organic solvent. The coordinates (HSP coordinates) defined by the Hansen solubility parameter of the first organic solvent ^{are Hd within the range of 17.5 to 19.5 (J / cm 3} ) ^1/2 , 3.5 to 5.5 (J). / Cm ³ ) ^{Hp in the range of 1/2} and Hh in the range of 3.5 to 5.5 (J / cm ³ ) ^1/2. HSP coordinates of the second organic solvent is, 17.5~19.5 ^{(J /} cm ³⁾ in the ^half of the range Hd, Hp in the range of 0~2.0 ^{(J /} cm ^{3) 1/2} And Hh in the range of 0.5 to 2.5 (J / cm ³ ) ^1/2.

The Hansen Solubility Parameter (HSP) is composed of three parameters: energy due to London dispersion force (Hd), energy due to bipolar interaction (Hp), and energy due to hydrogen bonding (Hh). HSP is a vector quantity expressed as (Hd, Hp, Hh), and is represented by plotting it on a three-dimensional space (Hansen space) having three parameters of HSP as coordinate axes. HSP can be expressed as HSP coordinates, for example. The unit of each parameter is (J / cm ³ ) ^1/2 . HSP is described, for example, on pages 1-26 of Hansen Solubility Parameters: A User's Handbook, Second Edition by Charles M. Hansen.

Since a database has been constructed for HSPs of commonly used substances, HSPs of desired substances can be obtained by referring to the database. For substances for which HSP is not registered in the database, HSP can be calculated from the chemical structure of the substance by using computer software such as Hansen Solubility Parameters in Practice (HSPiP).

The HSP of a mixture containing two or more substances is calculated as the vector sum of the values obtained by multiplying the HSP of each substance by the volume ratio of each substance with respect to the entire mixture.

The HSP coordinates of the first organic solvent according to the embodiment of the present invention are ^{Hd within the range of 17.5 to 19.5 (J / cm 3} ) ^1/2 , 3.5 to 5.5 (J / cm ^3). ) ^{Hp in the range of 1/2} and Hh in the range of 3.5 to 5.5 (J / cm ³ ) ^1/2.

Examples of the first organic solvent are ethylphenyl acetate, m-tolyl acetate, o-tolyl acetate, o-methylbenzyl acetate, propylphenyl acetate, 2-phenylpropyl acetate, styralyl acetate, methylphenyl acetate, methylphenylcarbinyl. Acetate, methylbenzylacetate, 3-phenylpropylacetate, allylphenylacetate, benzylbutyrate, o-cresylisobutyrate, cresylbutyrate, p-cresylisobutyrate, p-anisylisobutyrate, methyl 4-phenylbutyrate, benzyl propionate, phenethyl propionate, styralyl propionate, cinnamyl propionate, p-cresyl propionate, p-methylanisole, m-methylanisole, o-methylanisole , 2,4-Dimethylanisole, o-vinylanisole, 4-ethylanisole, phenylacetaldehyde ethyleneacetal, benzaldehydepropylene acetal, 2- (α-methylbenzyl) -1,3-dioxolane, cinnamaldehyde dimethylacetal, o-di Ethoxybenzene, p-methoxystyrene, 2-ethoxynaphthalene, 4-allyl anisole, 3,4-dimethoxystyrene, 1-ethoxynaphthalene, octylmethoxycinnam, 2,5-dimethoxystyrene, 2,6-dimethoxystyrene, 1 −methoxy-4-propoxybenzene, benzylmethyl ether, butylphenyl ether, ethylphenyl ether, benzyl ethyl ether, phenylisopropyl ether, phenylpropyl ether, allylphenyl ether, phenylvinyl ether, anisole, dihydroanetol, benzalacetone, phenylethylideneacetone , 2- (4-Isopropyl) propanal, 3- (4-isopropylphenyl) propanal and the like. The first organic solvent may be a mixed solvent of two or more kinds as long as it is an HSP within the above range. The present invention is not limited to such examples.

The first organic solvent according to the embodiment of the present invention is preferably dimethylanisole.

The HSP coordinates of the second organic solvent according to the embodiment of the present invention are ^{Hd within the range of 17.5 to 19.5 (J / cm 3} ) ^1/2 , 0 to 2.0 (J / cm ³ ) ^{1. Hp in the range of / 2} and Hh in the range of 0.5 to 2.5 (J / cm ³ ) ^1/2.

Examples of the second organic solvent are mesitylene, cyclohexylbenzene, toluene, benzene, p-diethylbenzene, ethylbenzene, on-butyltoluene, 1,2-diethylbenzene, 1,2,3,4-tetramethylbenzene, 1, 2,3,5-tetramethylbenzene, 1,1-diphenylpentane, 1,1-diphenylhexane, 3- (1-methylethenyl) toluene, 1-methyl-3-propylbenzene, 1-methyl-4- (1) -Methylethyl) -2- (1-propenyl) benzene, pentamethylbenzene, isopropylbenzene, 1,2,4-trimethylbenzene, 2,2-diphenylpropane, 2-ethyldiphenylmethane, 1,4-dimethyltetraline, caramenen , 1-butyl-1,2,3,4-tetrahydronaphthalene, 3-ethyldiphenylmethane, 1,1-diphenylpropane, 3-ethylbiphenyl, 3-methyldiphenylmethane, 1,1-diphenylbutane, 3,3'- Dimethylbiphenyl, 3,3', 4,4'-tetramethylbiphenyl, 3,3', 5,5'-tetramethylbiphenyl, diethylbiphenyl, (S) -1,2-dihydro-4,7-dimethyl- Examples thereof include 1-isopropylnaphthalene and (S) -1,2-dihydro-1,6-dimethyl-4-isopropylnaphthalene. The second organic solvent may be a mixed solvent of two or more kinds as long as it is an HSP within the above range. The present invention is not limited to such examples.

The second organic solvent according to the embodiment of the present invention is preferably diphenylpropane.

In addition to the first organic solvent and the second organic solvent, other solvents may be added to the organic EL solution according to the embodiment of the present invention as long as the object of the present invention is not impaired.

The organic EL contributing material is an organic material that contributes to organic EL, and is an organic EL material (light emitting material of R, G and B), a carrier transporting material (electron transporting material, a hole transporting material), and a carrier injection property. Includes materials (electron-injecting materials, hole-injecting materials) and carrier-blocking materials (electron-blocking materials, hole-blocking materials).

The organic EL contributing material according to the embodiment of the present invention is, for example, a light emitting material, a carrier transporting material, a carrier injecting material, or a carrier blocking material.

Examples of luminescent materials include F8-co-F6 (a copolymer of F8 (polydioctyl fluorene) and F6 (polydihexyl fluorene)), an oxinoid compound, a perylene compound, a pyrolopyrrole compound, a naphthalene compound, an anthracene compound, and a fluorene compound. , Fluolanthen compound, tetracene compound, pyrene compound, coronen compound, quinolone compound and azaquinolone compound, pyrazoline derivative, pyrazolone derivative, rhodamine compound, chrysene compound, phenanthrene compound, cyclopentadiene compound, stylben compound, diphenylquinone compound, styryl compound, butadiene compound , Dicyanomethylenepyran compound, Dicyanomethylenethiopyran compound, Fluolecein compound, Pyrylium compound, Thiapyrylium compound, Serenapyrilium compound, Tellopyrylium compound, Aromatic aldaziene compound, Oligophenylene compound, Thioxanthene compound, Cyanine compound, Acrydin compound, 8- Examples thereof include metal complexes of hydroxyquinoline compounds, metal complexes of 2-bipyridine compounds, chains of Schiff bases and Group III metals, oxine metal complexes, rare earth complexes and the like. These compounds and complexes may be used alone or in combination of two or more. The present invention is not limited to such examples.

Examples of hole-transporting materials include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, and styrylanthracene derivatives. , Fluolenone derivative, hydrazone derivative, stilben derivative, polyphyllin compound, aromatic tertiary amine compound, styrylamine compound, butadiene compound, polystyrene derivative, hydrazone derivative, triphenylmethane derivative, tetraphenylbenzine derivative and the like. These compounds and complexes may be used alone or in combination of two or more. Further, the hole transporting material may be used as an electron blocking material. The present invention is not limited to such examples.

Examples of electron-transporting materials include compounds having a heterocycle such as a phenanthroline derivative, a pyridine derivative, a tetrazine derivative, and an oxadiazole derivative, or a metal complex such as a _{tris (8-hydroxyquinolinate) aluminum complex (Alq 3).} Can be mentioned. Moreover, the electron transporting material may be used as a hole blocking material. These compounds and complexes may be used alone or in combination of two or more. Further, the hole transporting material may be used as an electron blocking material. The present invention is not limited to such examples.

Examples of hole-injectable materials include metal oxides such as MoOx (molybdenum oxide), WOx (tungsten oxide) or MoxWyOz (molybdenum-tungsten oxide) (x, y and z are positive numbers), metal nitrides. A thing or a metal oxynitride and the like can be mentioned.

Examples of electron-injectable materials include alkali metals such as lithium and sodium, alkaline earth metals such as magnesium and calcium, alkali metals such as lithium fluoride and lithium oxide, or inorganic compounds of alkaline earth metals, 8-quinolinol lithium and the like. Examples thereof include organic metal complexes having an alkali metal or alkaline earth metal as a central metal. The present invention is not limited to such examples.

The organic EL solution according to the embodiment of the present invention does not deteriorate the performance of the solution itself even when it comes into contact with the constituent members of the printing apparatus. Specifically, even if the organic EL solution comes into contact with the constituent members of the printing apparatus, the performance of the organic EL contributing material contained therein does not deteriorate. Further, even if the organic EL solution comes into contact with other organic layers already formed on the substrate, they are not dissolved and deteriorated, and the performance of the solution itself is not deteriorated. Therefore, the organic EL solution according to the embodiment can be applied onto the substrate by a droplet ejection method or the like and dried to form an organic layer without deteriorating the performance.

The method for manufacturing an organic EL device according to an embodiment of the present invention is a method for manufacturing an organic EL device having a structure in which an organic layer including a light emitting layer is sandwiched between two electrodes, and is a method for manufacturing an organic EL device according to the embodiment. Includes a step of forming the organic layer by applying and drying using.

Hereinafter, the method for manufacturing the organic EL device according to the embodiment will be described. First, the configuration of the organic EL display panel 1 formed by the manufacturing method will be described with reference to FIG. The organic EL display panel 1 is incorporated into the organic EL device according to the embodiment.

FIG. 1 is a cross-sectional view of the organic EL display panel 1. Note that FIG. 1 shows two pixels (six sub-pixels) of the organic EL display panel 1.

The organic EL display panel 1 includes a TFT substrate 11 including a glass substrate, a TFT (thin film transistor) layer, a flattening film layer, and the like, and a partition wall layer 12 formed on the TFT substrate 11. Since well-known configurations of the thin film transistor and the flattening film are used, they are not shown here. The film thickness of the partition wall layer 12 is about 1 μm, and the cross-sectional shape thereof is a forward taper shape.

In the sub-pixel region between the adjacent partition wall layers 12, an anode (first electrode) 13 made of a metal such as Al, a hole injection layer 14, and light emitting layers 15R, 15G, 15B made of a light emitting material ( Hereinafter, when it is not necessary to distinguish between them, they are collectively referred to as "light emitting layer 15"). Further, an electron injection layer 16 that covers the partition wall layer 12 and the light emitting layer 15, a cathode (second electrode) 17 made of a transparent material such as ITO (Indium Tin Oxide), and light transmission such as SiN and SiON. The sealing layer 18 made of a material is laminated in this order. In the organic EL display panel 1, the combination of the three sub-pixels R, G, and B is one pixel. Further, the emission color of the sub-pixel region is different from that of R, G, and B due to the difference in the light emitting material of the light emitting layer 15.

Next, a method of manufacturing the organic EL display panel 1 will be described with reference to FIGS. 2 and 3.
2A to 2D are cross-sectional views showing a manufacturing process of the organic EL display panel 1, and FIG. 3 is a top view of FIG. 2B. The cross section of AA'in FIG. 3 is (b) of FIG.

As shown in FIG. 2A, first, a substrate 10 including a TFT substrate 11, a partition wall layer 12, an anode 13, and a hole injection layer 14 is prepared.

As shown in FIG. 2B, in all the sub-pixel regions on the substrate 10, the recesses surrounded by the partition wall layer 12 are used for organic EL, which is the material of the light emitting layer 15 by a printing method using an inkjet method. The light emitting layer 15 is formed by applying the solution and drying it. As shown in FIG. 3, the partition wall layer 12 surrounds the light emitting layer 15. Further, the area where the light emitting layer 15 is visible corresponds to each sub-pixel area. In a general 20-inch organic EL display panel, when 1280 × 768 pixels are arranged at an equal distance, the size of the sub pixel area is about (64 μm × 234 μm).

As shown in FIG. 2C, an electron injection layer 16 and a cathode 17 are formed so as to cover the partition wall layer 12 and the light emitting layer 15.

As shown in FIG. 2D, when the sealing layer 18 is formed on the cathode 17, the organic EL display panel 1 is completed.

For the cathode 17 and the sealing layer 18, general members and forming techniques in known organic light emitting device techniques are used.

Next, the configuration of the organic EL device 40 according to the embodiment will be described with reference to FIG.
FIG. 4 is a schematic block diagram showing a schematic configuration of the organic EL device 40 provided with the organic EL display panel 1.

As shown in FIG. 4, the organic EL display panel 1 is electrically connected to the drive circuit 31, and the drive circuit 31 is controlled by the control circuit 32. The electrical connection of the organic EL display panel 1 is as known. In this way, the organic EL device 40 provided with the organic EL display panel 1 can be manufactured. In other words, the organic layer of the organic EL device is formed by the manufacturing method described above.

Hereinafter, the present invention will be described with reference to Examples.

[Preparation of organic solvent]
The organic solvents A to F shown in Table 1 were prepared. The HSP coordinates of each organic solvent are also shown.

[Preparation of organic EL contributing material (solute)]
An anthracene-based luminescent material was prepared as a solute.

[Preparation of solution for organic EL]
Each mixed solvent of the combination shown in Table 2 and the solute are stirred in an air atmosphere at a temperature of 60 ° C. in a shaker at 100 rpm for 24 hours to dissolve the solute for 2.0% by weight of organic EL. Solutions (No. 1 to No. 13) were prepared. The mixing ratio of the two organic solvents was 50:50 (% by weight).

〔Evaluation methods〕
No. prepared in this way. 1-No. The organic EL solution of No. 13 was set in the printing apparatus, discharged from the printing apparatus, and contacted with the constituent members of the printing apparatus, and the solution not contacted with the liquid was prepared. Subsequently, after the degassing treatment, the fluorescence quantum yield (PLQE) of each organic EL solution was measured using a fluorescence quantum yield measuring device.

Next, No. 1-No. The PLQE change rate (%) of the organic EL solution of No. 13 is calculated by the following formula [PLQE change rate] = ([PLQE of the organic EL solution brought into contact with the constituent members of the printing apparatus] / [not contacted]. PLQE of organic EL solution]) x 100%
Calculated by

No. 1-No. The PLQE change rate of the 13 organic EL solutions was evaluated on a three-point scale. The evaluation result is that a>b> c, and a has a PLQE change rate of 90% or more, and the performance of the organic EL solution has not deteriorated, or even if it has deteriorated, the degree of deterioration is small. b has a PLQE change rate of 60% or more and less than 90%. In c, the PLQE change rate is less than 60%, and the degree of deterioration of the organic EL solution is large. The results are shown in Table 2.

〔result〕
No. in Table 2 As shown in 1, 2, 5, and 6, the PLQE change rate of each of the organic EL solutions containing the mixed solvent of the first organic solvent and the second organic solvent exceeds 100%. In other words, it can be seen that the organic EL solution according to the embodiment does not deteriorate in the performance of the solution itself even when it comes into contact with the constituent members of the printing apparatus.

Further, the PLQE change rate of any of the first organic solvent and the second organic solvent, or the solution for organic EL containing neither the first organic solvent nor the second organic solvent is less than 100%. As a comparative example, it was found that when the first organic solvent and the second organic solvent were used as the solvents of E and F which did not satisfy the HSP, the rate of change of PLQE was lowered.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and do not limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.
The inventions described in the claims of the original application of the present application are described below.
[1]
An organic EL solution in which an organic EL contributing material is dissolved in a mixed solvent of two or more kinds of organic solvents containing at least a first organic solvent and a second organic solvent.
The coordinates (HSP coordinates) defined by the Hansen solubility parameter of the first organic solvent are Hd within the range of ^{17.5 to 19.5 (J / cm 3 ) 1/2} , 3.5 to 5.5 (Hd). J / cm ³ ) ^{Hp in the range of 1/2} and Hh in the range of 3.5 to 5.5 (J / cm ³ ) ^1/2.
The HSP coordinates of the second organic solvent is, 17.5~19.5 ^{(J /} cm ³⁾ in the ^half of the range ^{Hd, 0~2.0 (J / cm 3} ) in the ^half of the range A solution for organic EL that has Hp and Hh in the range of 0.5 to 2.5 (J / cm ³ ) ^1/2.
[2]
The organic EL solution according to [1], wherein the first organic solvent is dimethylanisole.
[3]
The solution for organic EL according to [1] or [2], wherein the second organic solvent is diphenylpropane.
[4]
The solution for organic EL according to any one of [1] to [3], wherein the organic EL contributing material is a light emitting material, a carrier transporting material, a carrier injecting material, or a carrier blocking material.
[5]
A method for manufacturing an organic EL device having a structure in which an organic layer including a light emitting layer is sandwiched between two electrodes, using the organic EL solution according to any one of [1] to [4]. A method for manufacturing an organic EL device, which comprises a step of forming the organic layer by coating and drying.
[6]
An organic EL device having a structure in which an organic layer including a light emitting layer is sandwiched between two electrodes, wherein the organic layer uses the solution for organic EL according to any one of [1] to [4]. An organic EL device formed by applying and drying.

1 Organic EL display panel 11 TFT substrate 12 Partition layer 13 Anode (first electrode)
14 Hole injection layer 15 Light emitting layer 16 Electron injection layer 17 Cathode (second electrode)
18 Sealing layer 40 Organic EL device

Claims (4)

An organic EL solution in which an organic EL contributing material is dissolved in a mixed solvent of two or more kinds of organic solvents containing at least a first organic solvent and a second organic solvent.
The first organic solvent is benzyl butyrate and is
The second organic solvent has a coordinate (HSP coordinate) defined by the Hansen solubility parameter, which is Hd within the range of ^{17.5 to 19.5 (J / cm 3 ) 1/2} , 0 to 2.0 (J / cm). cm ³ ) A solution for organic EL that has ^{Hp in the range of 1/2} and Hh in the range of 0.5 to 2.5 (J / cm ³ ) ^1/2. An organic EL solution in which an organic EL contributing material is dissolved in a mixed solvent of two or more kinds of organic solvents containing at least a first organic solvent and a second organic solvent.
The first organic solvent has Hd, 3.5 to 5.5 (Hd, 3.5 to 5.5) in which the coordinates (HSP coordinates) defined by the Hansen solubility parameter are ^{within the range of 17.5 to 19.5 (J / cm 3} ) ^1/2. J / cm ³ ) ^{Hp in the range of 1/2} and Hh in the range of 3.5 to 5.5 (J / cm ³ ) ^1/2.
It said second organic solvent is an organic EL solution is diphenyl Le propane.
The solution for organic EL according to claim 1 or 2, wherein the organic EL contributing material is a light emitting material, a carrier transporting material, a carrier injecting material, or a carrier blocking material. A method for manufacturing an organic EL device having a structure in which an organic layer including a light emitting layer is sandwiched between two electrodes, which is applied using the organic EL solution according to any one of claims 1 to 3. A method for manufacturing an organic EL device, which comprises a step of forming the organic layer by drying.

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