JP7069052B2 - Solvent blend for photoactive layer - Google Patents

Description

The present invention comprises solvent blends containing at least three solvents, solvent blends and formulations containing p-type and n-type organic semiconductors, and organic electronic devices and photoactive layers and membranes by using the above formulations. Regarding the manufacturing method.

Organic photosensitive electronic devices offer high flexibility and can be manufactured and processed at a relatively low cost by using low temperature vacuum deposition or solution treatment techniques, so they are new organic photosensitive alternatives to inorganic optoelectronic devices. There is increasing interest in the development of sex electronic devices.

Examples of organic photosensitive electronic devices include organic photovoltaic devices (OPVs), photocells and photodetectors. Usually, such organic photosensitive electronic devices include a pn junction as a photoactive layer, where the pn junction is made by film deposition of a donor / acceptor blend from solution and the device emits incident radiation. Allows conversion to current.

Typical examples of p-type materials are conjugated organic oligomers or polymers (eg, thiophene, phenylene, fluorene, polyacetylene, benzaziaziazoles and oligomers or polymers of combinations thereof), while fullerenes and fullerene derivatives (eg, C). ₆₀ PCBM and C70 PCBM) play an important role as n-type materials (see, eg, European Patent Application Publication No. _14478660 ).

In recent years, the choice of solvent or solvent mixture used for the preparation of donor / acceptor solutions has played an important role in manipulating the structure of pn junctions, enabling enhanced charge transport in organic photosensitive electronic devices. Is shown to be.

To achieve maximum generation of photocurrent from an organic photosensitive electronic device, an active layer with an optimized donor-acceptor distribution within the membrane with a suitable exciton diffusion length from the donor / acceptor interface Expected to be needed.

WO 2011/076324 discloses a wide range of suitable solvents used for organic semiconductor (OSC) compositions that can be used as inks for the fabrication of organic electronic devices with improved efficiency. The solvent is selected from the group consisting of aromatic hydrocarbons, aromatic ethers, aromatic ketones, alkyl ketones, heterocyclic aromatic solvents, halogen arylene and aniline derivatives.

US Patent Application Publication No. 2010/0043876 contains an organic semiconductor formulation comprising a blend of a first solvent containing at least one alkylbenzene or benzocyclohexane and a second solvent containing at least one carbocyclic compound. The thing is disclosed.

In WO 2013/029733, a solvent selected from alkylated tetralin, alkylated naphthalene and alkylated anisole, which may be accompanied by a second different solvent, may further modify the structure of the photoactive layer. Proposed.

US Patent Application Publication No. 2011/015601 to use a blend containing two or more solvents as a solvent mixture for polymer formulations based on benzothiadiazole and benzoxadiazole. Is disclosed to be advantageous in terms of film formability and device characteristics.

However, conventional solvent systems for organic semiconductor formulations optimized for the production of organic photosensitive electronic devices with favorable photoresponsiveness generally tend to exhibit poor stability, which is a large number of solutions. Limit their application in deposition techniques. For example, a common phenomenon during ink spray application is nozzle clogging, as this typically occurs during long periods of low frequency spraying or non-spraying periods, such as substrate alignment. Large-scale parsing and cleaning steps at short intervals are required. In many cases, clogging is irreversible and can even lead to complete nozzle blockage, which may not recover even after solvent purging.

In view of the above, stable inks containing n-type and p-type organic semiconductors that are suitable for inkjet printing and at the same time enable the manufacture of organic photosensitive electronic devices that achieve excellent photocurrent levels and efficiencies. There is a need to provide solvent blends that allow fabrication.

European Patent Application Publication No. 14478660 International Publication No. 2011/076324 US Patent Application Publication No. 2010/0043876 International Publication No. 2013/029733 US Patent Application Publication No. 2011/0156018

The present invention solves these problems by the subject matter of the claims as defined herein. The advantages of the present invention will be further described in detail in the sections below, and further advantages will be apparent to those skilled in the art in light of the disclosure of the present invention.

The use of certain solvent mixtures in formulations containing n-type and p-type organic semiconductors provides excellent ink stability without imparting photocurrent performance, thus effectively reducing and suppressing nozzle clogging. Therefore, the present inventors have found that an organic photosensitive device having excellent efficiency can be produced in a simple manner by inkjet printing.

In general, the invention is: (a) alkyl benzoate, aryl benzoate, alkylbenzothiazole or dialkoxybenzene; (b) first aromatic hydrocarbons that are dialkyl or trialkyl substituted aromatic hydrocarbons; and ( c) The present invention relates to a solvent blend containing a second aromatic hydrocarbon different from the first aromatic hydrocarbon.

In a second aspect, the invention relates to a formulation comprising the solvent blend, n-type organic semiconductor, and p-type organic semiconductor described above.

In a further aspect, the invention relates to a method of making an organic electronic device comprising an anode, a cathode, and a photoactive layer between the cathode and the anode, wherein the method is coated with the above formulation by a solution deposition method. Includes forming a photoactive layer.

Another aspect of the invention is the use of the solvent blends described above in solution deposition methods, preferably inkjet printing methods, and the formulations described above as coatings or printing inks for the preparation of photoactive thin films or photoactive layers. Is the use of.

Preferred embodiments of the formulations according to the invention and other aspects of the invention are described in the following description and claims.

The general structure of a conventional organic photodetector is shown graphically.

For a more complete understanding of the invention, the following description of exemplary embodiments thereof will be referred to herein below.

Solvent Blends and Semiconductor Formulations In the first embodiment, the invention is in (a) alkyl benzoate, aryl benzoate, alkylbenzothiazole or dialkoxybenzene; (b) dialkyl or trialkyl substituted aromatic hydrocarbons. With respect to a solvent blend comprising a first aromatic hydrocarbon; and (c) a second aromatic hydrocarbon different from the first aromatic hydrocarbon. Solvent blends have been shown to be useful in the fabrication of semiconductor formulations with excellent ink stability.

The alkyl benzoate is preferably C ₁ to C ₁₈ alkyl benzoate, more preferably C ₁ to C ₁₂ alkyl benzoate, for example C ₁ to C ₆ alkyl benzoate.

The aryl benzoate is preferably a C ₆ to C ₁₈ aryl ester of benzoic acid, and preferably a C ₆ to C ₁₀ aryl ester of benzoic acid. The aryl group may be unsubstituted or substituted with a C ₁ to C ₁₂ alkyl group or preferably a C ₁ to C ₆ alkyl group.

In a preferred embodiment from the viewpoint of the solubility of an excellent n-type organic semiconductor, the component (a) is an alkyl benzoate or an aryl benzoate, especially when a fullerene and / or a fullerene derivative is used. Preferably, the alkyl benzoate or the aryl benzoate is benzyl benzoate. When component (a) is an alkylbenzothiazole, it may be methylbenzothiazole, more preferably 2-methylbenzothiazole or 4-methylbenzothiazole. When the component (a) is dimethoxybenzene, it may be dimethoxybenzene, more preferably 1,2-dimethoxybenzene.

Alkyl benzoate or aryl benzoate, alkylbenzothiazole or dialkoxybenzene are preferably 0.5-50% by volume, more preferably 0.5-30% by volume, even more preferably, based on the total volume of the solvent blend. Is present in the content range of 1-10% by volume.

The component (b), i.e., the first aromatic hydrocarbon, is a dialkyl or trialkyl substituted aromatic hydrocarbon.

The dialkyl-substituted aromatic hydrocarbons preferably contain an alkyl group, which may be selected independently of a C ₁ to C ₁₂ alkyl group or more preferably a C ₁ to C ₆ alkyl group. More preferably, the dialkyl-substituted aromatic hydrocarbons are dialkylbenzenes, more preferably ortho-dialkylbenzenes, the alkyl groups may be the same or different, and the C1 to _C12 alkyl groups or _more preferably C. It may be selected from ₁ to _C6 alkyl groups.

Preferably, the trialkyl-substituted aromatic hydrocarbons are trialkylbenzenes, the alkyl groups may be the same or different, and are selected from C ₁ to C ₁₂ alkyl groups or more preferably C ₁ to C ₆ alkyl groups. It may be something. More preferably, the trialkyl-substituted aromatic hydrocarbon has the following general formula (I):

(In the formula, R ₁ and R ₂ independently represent C ₁ to C ₆ alkyl groups, C ₁ to C ₆ alkyl groups may be linked to each other to form a ring, and R ₃ may be hydrogen or Represented by _C1 to _C6 alkyl groups).

Specific examples of the compound according to the general formula (I) include 1,2-dialkylbenzene (for example, o-xylene) and 1,2,4-trialkylbenzene (for example, 1,2,4-trimethylbenzene, 1,2). , 4-Triethylbenzene, 1,2-dimethyl-4-ethylbenzene), 1,2,3-trialkylbenzene (eg 1,2,3-trimethylbenzene, 1,2,3-triethylbenzene), indan and its Alkyl-substituted derivatives and tetralin and its alkyl-substituted derivatives can be mentioned. In a preferred embodiment, the dialkyl or trialkyl substituted aromatic hydrocarbon is trialkylbenzene, more preferably trimethylbenzene, still more preferably 1,2,4-trimethylbenzene.

The first aromatic hydrocarbon is preferably in the content range of 30-99.4% by volume, preferably 60-99% by volume, more preferably 70-98% by volume, based on the total volume of the solvent blend. Used.

The component (c), i.e., the second aromatic hydrocarbon, preferably exhibits two benzene rings that may be condensed, such as naphthalene and alkylnaphthalene and diphenylalkane. More preferably, the second aromatic hydrocarbon is selected from either 1-methylnaphthalene or diphenylmethane.

The second aromatic hydrocarbon has a content range of 0.1 to 50% by volume, preferably 0.5 to 30% by volume, more preferably 1 to 20% by volume, based on the total volume of the solvent blend. It is preferable to be present.

Preferably, the first aromatic hydrocarbon has a melting point of less than -30 ° C, for example -80 ° C to -40 ° C, and / or the second aromatic hydrocarbon has a melting point of -30 ° C or higher. For example, it exhibits a melting point of −25 ° C. to + 20 ° C. Regarding the characteristics of the boiling point, the first aromatic hydrocarbon may have a boiling point lower than 200 ° C. The second aromatic hydrocarbon has a boiling point of 200 ° C. or higher, more preferably 200 ° C. to 300 ° C., more preferably 160 or less, for example 120 or less, or 80 or less relative. It is preferably possessed in combination with an evaporation rate (DIN 53170: 2009-08; determined according to butyl acetate = 100), whereby the loss due to evaporation of the first aromatic hydrocarbon during injection is semiconductor (typically). It ensures that it does not cause precipitation of p-type organic semiconductors), thereby further reducing nozzle clogging.

The solvent blend may preferably consist of the components (a), (b) and (c), but the solvent mixture may contain one or more additional solvents. The additional solvent may be a liquid component in which either or both of the n-type OSC and the p-type OSC are soluble with a solubility of 0.2 mg / ml or greater. Such additional solvents are not particularly limited and can be appropriately selected by those skilled in the art. Examples include linear or cyclic ketones (eg, cyclohexanone), aromatic and / or aliphatic ethers (eg, anisole), aromatic alcohols, optionally substituted thiophenes, benzothiophenes, alkoxylated naphthalenes, etc. Alkyl benzoate, chlorinated solvents (eg, chlorobenzene, trichlorobenzene, dichlorobenzene or chloroform) and mixtures thereof can be mentioned. In another preferred embodiment, the additional solvent is contained in a total content of less than 3% by volume, more preferably less than 2% by volume, based on the total volume of the solvent. However, from the viewpoint of environmental friendliness, it is preferable that the composition does not contain a chlorinating solvent.

In a second embodiment, the invention relates to a formulation comprising an n-type organic semiconductor, a p-type organic semiconductor, and a solvent blend according to the first embodiment above.

The p-type organic semiconductor is not particularly limited and can be appropriately selected from standard electron donating materials known to those skilled in the art and described in the literature, such as organic polymers, oligomers and small molecules. In a preferred embodiment, the p-type organic semiconductor comprises a conjugated organic polymer, which can be a homopolymer or a copolymer such as an alternating, random or block copolymer. Amorphous or semi-crystalline conjugated organic polymers are preferred. Exemplary p-type OSC polymers include polyacene, polyaniline, polyazulene, polybenzofuran, polyfluorene, polyfuran, polyindenofluorene, polyindole, polyphenylene, polypyrazolin, polypyrene, polypyridazine, polypyridine, polytriarylamine, poly ( Phenilenbinylene), poly (3-substituted thiophene), poly (3,4-disubstituted thiophene), polyselenophene, poly (3-substituted selenophen), poly (3,4-disubstituted selenophen), poly (bisthiophene) ), Poly (terthiophene), poly (bisselenophene), poly (terselenophene), polythieno [2,3-b] thiophene, polythieno [3,2-b] thiophene, polybenzothiophene, polybenzo [1, 2-b: 4,5-b'] Dithiophene, polyisothianaphthalene, poly (single-substituted pyrrole), poly (3,4-disubstituted pyrrole), poly-1,3,4-oxadiazole, polyiso Polymers selected from conjugated hydrocarbon or heterocyclic polymers such as thianaphthalene, derivatives and copolymers thereof can be mentioned. Preferred examples of p-type organic semiconductors are copolymers of polyfluorene and polythiophene, which may be substituted, respectively, and polymers containing benzothiadiazole-based and thiophene-based repeating units, which may be substituted, respectively. It is understood that the p-type organic semiconductor may consist of a mixture of a plurality of electron donating materials.

The n-type organic semiconductor is also not particularly limited, and can be suitably selected from electron-accepting materials known to those skilled in the art, and may be composed of a mixture of a plurality of electron-accepting materials. Examples thereof include n-type conjugated polymers, fullerenes and fullerene derivatives. Preferably, the n-type organic semiconductor is C60, C70, C96, a PCBM-type fullerene derivative (such as C ₆₀ PCBM and C ₇₀ PCBM), and a TCBM-type fullerene derivative (for example, trill-C61-butyric acid methyl ester (C ₆₀ TCBM)). , ThCBM-type fullerene derivative (eg, a single species or mixture of fullerenes and / or fullerene derivatives, such as thienyl-C61-butyric acid methyl ester (C60 _ThCBM ). Further examples of fullerene derivatives include International Publication No. 2004 /. 073082, US Patent Application Publication No. 2011/0132439, International Publication No. 2015/036075, and US Patent Application Publication No. 2011/0132439.

The ratio of p-type material to n-type material present in the formulation can be routinely determined by one of ordinary skill in the art. The ratio is preferably 10: 1 to 1:10, more preferably 4: 1 to 1: 4, and particularly preferably 1: 1 to 1: 3.

From the viewpoint of an excellent balance between injection stability and efficiency, the p-type organic semiconductor is preferably in the range of 1 to 30 mPa · s, more preferably in the range of 3 to 6 mPa · s, still more preferably 3.6. It is selected to exhibit kinematic viscosities at 25 ° C. in a tetralin solution in the range of ~ 5.4 mPa · s, eg 3.7 ~ 4.1 mPa · s. The kinematic viscosity at 25 ° C. is that the p-type organic semiconductor is dissolved in tetraline (tetrahydronaphthalene) so as to provide a solution having a p-type organic semiconductor concentration of about 0.6% by weight, and the solution is dissolved at 45 ° C. to 85 ° C. Measured by stirring at a temperature between 12-20 hours, keeping the solution at 25 ° C for at least 1 hour after heating and measuring the kinematic viscosity at 25 ° C using a viscometer (eg Brookfield viscometer). can do. When the p-type organic semiconductor is an organic polymer, its weight average or number average molecular weight can be appropriately selected to obtain a formulation having a desired kinematic viscosity. Preferably, the weight average molecular weight Mw of the p-type polymer is less than 100,000, more preferably in the range of 30,000 to 95,000, and even more preferably in the range of 50,000 to 85,000. The kinematic viscosity of the final ink formulation, that is, the formulation containing the n-type organic semiconductor, the p-type organic semiconductor and the solvent blend, at 25 ° C. is not particularly limited, and is typically 0.1 to 10 mPa · s. Within the range, often within the range of 0.5-2 mPa · s.

Preferably, the total concentration of the n-type and p-type materials in the solvent blend is in the range of 0.1 to 2.5 w / v%, more preferably 0.5 to 1.8 w / v%.

In general, the relative solubility of donors and acceptors and the boiling point of the solvent are considered important parameters when designing ink formulations to achieve high efficiency.

Efficiency and photocurrent are usually good for solubilizing both donor and acceptor materials by including a main solvent and a higher boiling point additive that usually achieves good solubility for either the acceptor or the donor. It is considered to be controlled.

Selection of a suitable solvent by relative solubility of p-type and n-type organic semiconductors can be achieved through the use of known parameters such as, for example, the Hansen solubility parameter (HSP). The Hansen solubility parameter can be determined according to the HSPiP program (version 4.1 or 5.0) provided by Hansen and Abbot et al. For details on the value of the Hansen parameter and its calculation, refer to C.I. M. It can be found in Hansen's "Hansen Solubility Parameters: A User's Handbook", 2nd Edition, 2007, Taylor and Francis Group LLC. The Hansen solubility parameter of each organic semiconductor of the formulation of the present invention is preferably within the following range: the dispersion contribution of the p-type semiconductor δ _D (P) is preferably 17. It is in the range of about 22 MPa ^0.5 , and the polarity contribution δ _P (P) of the p-type semiconductor is preferably in the range of 0 to 7 MPa ^0.5 , more preferably in the range of 0 to 3 MPa ^0.5 , and p. The hydrogen bond contribution δ _H (P) of the type semiconductor is preferably in the range of 0 to 6 MPa ^0.5 , more preferably 0 to 3 MPa ^0.5 . The dispersion contribution δ _D (N) of the n-type semiconductor is preferably in the range of 17 to 21 MPa ^0.5 , and the polarity contribution δ _P (N) of the n-type semiconductor is preferably 0 to 7 MPa ^0.5 . The _hydrogen bond contribution of the n-type semiconductor is preferably in the range of 3 to 7 MPa ^0.5 , preferably 0 to 8 MPa ^0.5 , and more preferably 3 to 6 MPa ^0.5 . be.

Alkyl benzoate or aryl benzoate, alkylbenzothiazole or dialkoxybenzene, a first aromatic hydrocarbon, and a second aromatic hydrocarbon have a Hansen solubility parameter of at least one of p-type or n-type organic semiconductors. By matching one, the difference between their dispersion, polarity and contribution of hydrogen bonds δ _D , δ _P and δ _H is 5 MPa ^0.5 or less, more preferably 3 MPa ^0.5 or less, Even more preferably, it is preferably selected to be 2 MPa ^0.5 or less.

In a preferred embodiment, the Hansen solubility parameter of the second aromatic hydrocarbon and the p-type organic semiconductor satisfies the following relationship:
0MPa ^0.5 ≤ │ δ _D (SAH) -δ _D (P) │ ≤ 5MPa ^0.5 ;
0MPa ^0.5 ≤ │ δ _P (SAH) -δ _P (P) │ ≤ 5MPa ^0.5 ; and 0MPa ^0.5 ≤ │ δ _H (SAH) -δ _H (P) │ ≤ 5MPa ^0.5 ;
Or more preferably satisfy the following relationship:
0MPa ^0.5 ≤ │ δD _SAH -δD _p │ ≤ 2MPa ^0.5 ;
0MPa ^0.5 ≤ │ δP _SAH -δP _p │ ≤3MPa ^0.5 ; and 0MPa ^0.5 ≤│δH _SAH -δH _p │ ≤4MPa ^0.5 ;
(In the formula, δ _D (SAH), δ _P (SAH) and δ _H (SAH) indicate the Hansen solubility parameters of the dispersion, polarity and hydrogen bond of the second aromatic hydrocarbon, δ _D (P), δ _P (P) and δ _H (P) indicate the Hansen solubility parameters for dispersion, polarity and hydrogen bonds of p-type organic semiconductors).

The formulation may contain additional components in addition to the n-type organic semiconductor, p-type organic semiconductor and solvent blend. Examples of such ingredients are pressure-sensitive agents, defoamers, degassing agents, viscosity-enhancing agents, diluents, auxiliaries, fluidity-enhancing agents, colorants, dyes or dyes, sensitizers, stabilizers, nanoparticles. Examples include particles, surface active compounds, lubricants, wetting agents, dispersants and inhibitors.

It will be appreciated that the preferred features of the first and second embodiments identified above can be combined in any combination, except for combinations in which at least some of the features are mutually exclusive.

The formulations defined above serve as a starting material for solution deposition of photoactive layers and membranes with advantageous high stability for solution deposition applications, organic photosensitive devices, especially light with excellent efficiency. Enables faster and more precise manufacture of detectors.

Organic Photosensitive Electronic Devices and Methods for Manufacturing There In a third embodiment, the present invention relates to the use of a solvent blend according to the first embodiment in a solution deposition method, wherein the solution deposition methods include, for example, spin coating and spray coating. Coating or printing or microdispensing such as web printing, brush coating, dip coating, slot die printing, inkjet printing, typographic printing, screen printing, doctor blade coating, roller printing, offset lithography printing, flexo printing, or pad printing. However, the method is not limited to these methods. Preferably, the solution deposition method is an inkjet printing method, as discussed in more detail below with respect to the fourth embodiment of the present invention.

That is, in a fourth embodiment, the present invention relates to a method for producing an organic electronic device including an anode, a cathode, and a photoactive layer between the cathode and the anode, wherein the method is the above-mentioned second method by a solution deposition method. Includes applying the formulation according to the embodiment of the above to form a photoactive layer.

The organic electronic device may be any organic electronic device or component that requires a layer containing a pn organic semiconductor junction, such as an organic photodiode. Typically, the organic electronic device is an organic photosensitive electronic device, which may be, for example, a photovoltaic device or a solar cell, a photoconducting cell or a photodetector, each of which is desired. Can operate as a single device or as an array.

The typical general structure of an organic photosensitive electronic device is graphically shown in FIG. Here, the anode 2 usually made of a high work function material is deposited on the substrate 1 made of a material that allows visible light to pass through. Typical anode materials include conductive metal oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO), aluminum zinc oxide (AlZnO), and metals (eg, gold), while Glass or plastic is conventionally used as a substrate material. The formulation according to the first embodiment is a photoactive layer 3 comprising a so-called bulk heterojunction between the anode 2 and the cathode 4 which may be made of a metal (eg, Ag, Ag: Mg) or a metal oxide. Formed by the solution deposition of. A contact 5 is provided between the anode 2 and the cathode 4, which is in series with the bias voltage source and detector (eg, as a detection circuit, eg, to measure the generated optical response). It may include a connected ammeter or readout device).

The formulations according to the present invention can be applied to the substrate or component of an organic photosensitive electronic device by any suitable selective solution deposition method, and the method is not limited to the following, for example, spin coating, spray coating, and the like. , Web printing, brush coating, dip coating, slot die printing, inkjet printing, ejection printing, typographic printing, screen printing, doctor blade coating, roller printing, offset lithography printing, flexo printing, or pad printing. The method of microdispensing may be mentioned, but the selective solution deposition method is an inkjet printing method (such as continuous inkjet printing or drop-on-demand (DOD) inkjet printing method) in order to take full advantage of the present invention. Is preferable.

Inkjet printing generally involves the ejection of a certain amount of liquid phase, ie ink, in the form of droplets from the chamber through the nozzles. The ejected droplets are provided to the substrate to form a pattern. Coagulation of droplets can be brought about through chemical changes or crystallization, but solvent evaporation is commonly used, which in some cases, preferably immediately after printing, heated and / or reduced the deposited wet film. It is done by exposure to pressure.

In the conventional method, the injection sensation must be set short to avoid the risk of nozzle clogging and blockage. The method of the invention has the advantage that the risk of clogging is significantly reduced, thereby allowing idle frequencies, i.e. frequencies below 50 Hz, typically even below 20 Hz (5-10 Hz). Stable operation is possible within the range of). In addition, the latency / decap time (ie, the time during which the ink can remain non-sprayed without purging the head prior to re-spraying the nozzles) is compared to the use of conventional organic semiconductor formulations. Sometimes it can increase favorably.

The thickness of the dried photoactive layer or membrane is preferably 10 nm to 3 μm, more preferably 20 nm to 2 μm, for example 50 nm to 600 nm. In a more preferred embodiment, the film thickness of the dry layer is in the range of 80-250 nm.

The photoactive layer or membrane may be homogeneous or phase separated and may contain different phases in which the ratio of p-type material to n-type material may be different. The photoactive layer may have a somewhat uniform ratio throughout the thickness of the photoactive layer, or the ratio of p-type material to n-type material may be gradual or gradual throughout the thickness of the photoactive layer. May change to.

The solvent blends used in the formulations of the present invention have a decisive effect on the resulting uniformity and structure of the photoactive layer, so the latter has characteristic properties (eg, texture and / or phase distribution). ) Should be noted. Also, residual amounts of solvents with high boiling points (eg, 200 ° C. or higher) can be found in the active layer even after extensive drying and thus can contribute to unique structural properties.

[Example]
Ink stability test Stable ink injection of a formulation containing _C70 PCBM as an n-type organic semiconductor and a p-type organic semiconductor according to structural formula (1) (2: 1 ratio, concentration of 1% at w / v in solvent). Sex was tested using different solvent blends:

The materials that make up the tested ink formulation are shown in Table 1.

[ Comparative Example 1 ]
First, OPD inks containing the n-type and p-type organic conductors (1% w / v) identified above in a solvent blend (9: 1) consisting of trimethylbenzene and benzyl benzoate were prepared to make Fujifilm Dimatix. The injection stability was evaluated using an 8pL SX3 printhead (nozzle diameter of 27 μm) and a 35pL SE3 printhead (nozzle diameter of 42 μm) available from the company.

[ Example 1 ]
OPD inks were prepared and evaluated in the same manner as in Comparative Example 1 except that a solvent blend containing trimethylbenzene, benzyl benzoate and diphenylmethane was used in a volume ratio of 90: 5: 5.

When the composition of Comparative Example 1 was sprayed at a frequency of 50 Hz using both types of printheads, nozzle clogging was observed within a few hours or up to a few days, and of the 128 nozzles available for the printhead. More than one of the nozzles no longer ejected, after which the risk of irreversible nozzle blockage increased. However, when diphenylmethane was added as a three-component solvent blend, no clogging was observed when the injection was left for longer than 3 days (even when the injection frequency was reduced to 5-10 Hz). The differences in ejection stability for the two types of ink are summarized in Table 2 below.

The time for stable idle injection at low frequencies (in "stand-by" mode) was found to be substantially longer with the three-component solvent blend than with the ink according to Comparative Example 1. The latency / decap time, which is the time during which the ink can remain non-sprayed without purging the head prior to re-spraying the nozzles, was also found to be significantly better with the composition of Example 1. bottom.

Device Performance Testing In a further series of experiments, organic semiconductor formulations containing different solvent systems were used to make device laminates by spin coating.

Specifically, a device laminate having the following configuration was produced:
Geomatic 45nm ITO as photopatterned as an anode on glass with 100nm MoCr in the tracking region
50 nm Nissan NDHIL layer 100 nm spin-coated photoactive layer Glass encapsulation with 200 nm evaporated Ag cathode getter Glass encapsulation 1: 2 weight ratio structural formula (1) p-type organic semiconductor and _C70 PCBM drying The materials were combined and a photoactive layer formulation was made by adding a solvent blend at a concentration of 24 mg / ml in a nitrogen environment. The solution was then heated to 80 ° C. for 14 hours with stirring. The solution was then cooled for 8 minutes and immediately drawn into a syringe for spin coating. Spin coating was performed using a glass syringe, a 2 μm glass filter and a needle.

After the substrate was completely immersed in the solution, spin treatment was applied using a single spin phase (cover + gyroset cover) at a speed of 500-1000 rpm (acceleration of 1000 rpm) and a duration of 6 seconds.

The coated substrate was then dried in a Vacuum vacuum oven for 5 minutes at a temperature of 80 ° C. and a vacuum pressure of less than 5 × 10 ⁻² millibar.

After drying, the membrane was transferred to a nitrogen-filled glove box for loading into a deposition tool for the cathode process. During this transfer, the membrane was placed in a chamber under vacuum for a short time.

The cathode was then deposited and then the device was encapsulated in a nitrogen environment. The device was then scribed and pinned in preparation for the test.

The test procedure involved illumination of each OPD element with a calibrated LED (λ = 525 nm) inside a sealed test box, and measurement of the average photocurrent (active device area = 1 mm ² ). The selected wavelengths will be useful for biosensor applications. The external quantum efficiency (EQE) of the photodetector is the equation:

Based on (in the equation, I is the average light current, P is the power of monochromatic light of wavelength λ entering the photodetector, h is Planck's constant, e is the electron charge, and c is the light velocity in vacuum). Calculated.

[ Comparative Example 2 ]
In Comparative Example 2, a blend of 1,2,4-trimethylbenzene and benzyl benzoate (9: 1) was used as a solvent system. As a result, an average photocurrent of 49.2 nA / mm ² was measured (EQE = 44.1%). A value of 48.3 nA / mm ² was obtained in the second measurement (EQE = 43.3%).

A main solvent that is good for solubilizing both donor and acceptor materials and additives with higher boiling points (in this case, benzyl benzoate) that achieve good solubility for the acceptor but are the donor's non-solvent. It is considered that high efficiency is controlled by including (in this case, 1,2,4-trimethylbenzene).

[ Example 2 ]
A blend of 1,2,4-trimethylbenzene, benzyl benzoate and diphenylmethane (85: 5:10) was used as the solvent system of Example 2. An average photocurrent of 49.8 nA / mm ² (EQE = 44.7%) was measured, demonstrating that the addition of diphenylmethane (component (c)) does not negatively contribute to the efficiency of the device. On the contrary, the external quantum efficiency is slightly higher than that measured in Comparative Example 2.

[ Examples 3 to 6 ]
In another series of experiments, different compositions according to the invention were tested in inkjet printed devices with the following configurations:
Geomatic 45nm ITO as photopatterned as an anode on glass with 100nm MoCr in the tracking region
Inkjet-printed 50 nm Nissan PN7-B1 layer Inkjet-printed photoactive layer Glass encapsulation using a 200 nm evaporated Ag cathode getter Glass encapsulation 1: 2 weight ratio structural formula (1) p-type organic semiconductor and C A photoactive layer formulation was made by combining ₇₀ PCBM dried products and adding a solvent blend at a concentration of 9.8 mg / ml in a nitrogen environment. The solution was then heated to 80 ° C. for 14 hours with stirring. The solution was then degassed for 1 hour using a sonication process under vacuum and then mounted on a Litrex inkjet printer. After the printer was continuously sprayed for several hours at an injection frequency of 10 to 100 Hz, printing was performed on the device.

The average photocurrent of the inkjet printed device (effective device area = 1 mm ² ) was measured, and the EQE was calculated for Comparative Example 2 and Example 2 in the same manner as outlined above.

The measurement results for each of the tested compositions are shown in Table 3.

The external quantum efficiency of the devices made by using the compositions of the present invention is photoactive using a HSPiP-optimized blend of two solvents, 1,2,4-trimethylbenzene and benzyl benzoate. It can be seen that the layer achieves a level comparable to the device according to Comparative Example 2 with spin coating.

Accordingly, the organic semiconductor formulations according to the invention exhibit improved stability for ink ejection applications, even at low ejection frequencies, and can be used to provide high quality photoactive thin films or photoactive layers at the same time. It can enable the manufacture of organic photosensitive electronic devices that achieve excellent photocurrent levels.

Measurements Dependent on P-Type Semiconductors In the final series of experiments, ink formulations containing p-type semiconductors with different kinematic viscosities in tetraline solutions were used with p-type polymers according to structural formula (1) with different weight average molecular weights. Prepared and tested. The kinematic viscosity at 25 ° C. dissolves the p-type organic semiconductor in tetraline (tetrahydronaphthalene) so as to provide a solution having a p-type organic semiconductor concentration of 0.6% by weight, and the solution is stirred at 50 ° C. for 16 hours. And keep the solution at 25 ° C. for about 4 hours after heating and at 25 ° C. using a Brookfield viscometer (model DV2TLV CP; spindle CPA-40Z; rotation speed 30 rpm; 0.70 mL liquid; 3 measurements). It was measured by measuring the kinematic viscosity of. A solvent blend of different p-type polymers consisting of trimethylbenzene, benzyl benzoate and diphenylmethane in a weight ratio of 1: 2 with C ₇₀ PCBM and in a volume ratio of 90: 5: 5 (0.98 w / v%). In addition, the ink formulations according to Examples 7 to 15 were obtained.

The ink formulations were tested for filterability and jet stability (according to Example 1) and OPD devices (each with an effective device area of 1 mm ² ) were made according to Example 2 using the ink formulations. The relative efficiencies were then compared based on photocurrent performance (see Example 2). The results of the evaluation are shown in Table 3, where "++" indicates very good, "+" indicates good, and "ο" indicates acceptable performance.

As shown above, a favorable balance between injection stability and photocurrent is observed in Examples 9-13. Ideal results are obtained in Examples 9 and 10, and the p-type organic semiconductor exhibits kinematic viscosities of 3.9 and 4.1 mPa · s at 25 ° C. in tetralin solution.

Given the above disclosure, many other features, modifications, and improvements will be apparent to those of skill in the art.

1 Substrate layer 2 Anode 3 Photoactive layer 4 Cathode 5 Contact

Claims (25)

The solvent blend contains an n-type organic semiconductor, a p-type organic semiconductor, and a solvent blend.
(A) Alkyl benzoate, aryl benzoate, alkylbenzothiazole or dialkoxybenzene;
In a formulation comprising (b) a first aromatic hydrocarbon that is a dialkyl or trialkyl substituted aromatic hydrocarbon; and (c) a second aromatic hydrocarbon different from the first aromatic hydrocarbon. There,
The first aromatic hydrocarbon has a boiling point lower than 200 ° C., and the second aromatic hydrocarbon has a boiling point of 200 ° C. or higher.
Dispersion and hydrogen bond contribution of each Hansen solubility parameter of (a), (b) and (c) δ _D and δ _H and each dispersion and hydrogen bond contribution of the Hansen solubility parameter of the p-type organic semiconductor δ The difference between _D and δ _H is all 5 MPa ^0.5 or less,
Dispersion and hydrogen bond contribution of each Hansen solubility parameter of (a), (b) and (c) δ _D and δ _H and each dispersion and hydrogen bond contribution of the Hansen solubility parameter of the n-type organic semiconductor δ A formulation in which the difference between _D and δ _H is all 5 MPa ^0.5 or less. The formulation according to claim 1, wherein the component (a) is selected from the alkyl benzoate or the aryl benzoate. The component (a) is selected from benzoic acid C ₁ to C ₁₈ alkyl or benzoic acid C ₆ to C ₁₈ aryl esters, and the C ₆ to C ₁₈ aryl groups may be unsubstituted or C ₁ to. It may be substituted with a _C12 alkyl group and may be substituted.
The component (b) is selected from dialkylbenzene or trialkylbenzene containing an alkyl group which may be independently selected from the C ₁ to C ₁₂ alkyl groups, wherein the alkyl groups are the same. It may or may be different and may be selected from C ₁ to C ₁₂ alkyl groups and / or the component (c) comprises two benzene rings which may be fused. Aromatic hydrocarbon,
The formulation according to claim 2. The formulation according to any one of claims 1 to 3, wherein the second aromatic hydrocarbon has a boiling point between 200 ° C and 300 ° C. Ingredient (a) is benzyl benzoate,
Component (b) is trialkylbenzene ,
The formulation according to any one of claims 1 to 4. Component (b) is trimethylbenzene and / or
Ingredient (c) is selected from either 1-methylnaphthalene or diphenylmethane,
The formulation according to claim 5. Claims 1 to claim that the alkyl benzoate or aryl benzoate, the alkyl benzothiazole or the dialkoxybenzene are present in a content range of 0.5-50 % by volume based on the total volume of the solvent blend. The formulation according to any one of 6 . The formulation according to claim 7, wherein the alkylbenzothiazole or the dialkoxybenzene is present in a content range of 0.5 to 30% by volume based on the total volume of the solvent blend. The formulation according to claim 7, wherein the alkylbenzothiazole or the dialkoxybenzene is present in a content range of 1 to 10% by volume based on the total volume of the solvent blend. The formulation according to any one of claims 1 to 9 , wherein the first aromatic hydrocarbon is present in a content range of 30 to 99.4 % by volume based on the total volume of the solvent blend . Things . The formulation according to claim 10, wherein the first aromatic hydrocarbon is present in a content range of 60 to 99% by volume based on the total volume of the solvent blend. The formulation according to claim 10, wherein the first aromatic hydrocarbon is present in a content range of 70 to 98% by volume based on the total volume of the solvent blend. The formulation according to any one of claims 1 to 12 , wherein the second aromatic hydrocarbon is present in a content range of 0.1 to 50 % by volume based on the total volume of the solvent blend . Things . 13. The formulation according to claim 13, wherein the second aromatic hydrocarbon is present in a content range of 0.5 to 30% by volume based on the total volume of the solvent blend. 13. The formulation according to claim 13, wherein the second aromatic hydrocarbon is present in a content range of 1 to 20% by volume based on the total volume of the solvent blend. The formulation according to any one of claims 1 to 15 , wherein the component (a) is the alkylbenzothiazole, and the alkylbenzothiazole is selected from 2-methylbenzothiazole and 4-methylbenzothiazole. The formulation according to any one of claims 1 to 15 , wherein the component (a) is the dialkoxybenzene and 1,2-dimethoxybenzene. The Hansen solubility parameter of the second aromatic hydrocarbon and the p-type organic semiconductor has the following relationship:
0MPa ^0.5 ≤│δD _SAH -δDp│≤2MPa ^0.5 ,
0MPa ^0.5 ≤│δP _SAH -δPp│≤3MPa ^0.5 , and 0MPa ^0.5 ≤│δH _SAH -δHp│≤4MPa ^0.5
(In the formula, δD _SAH , δP _SAH and δH _SAH indicate the Hansen solubility parameter of the dispersion, polarity and hydrogen bond of the second aromatic hydrocarbon, and δD _p , δP _p and δH _p are the above p-types. The formulation according to any one of claims 1 to 17 , which satisfies the Hansen solubility parameter of dispersion, polarity and hydrogen bond of an organic semiconductor). The formulation according to any one of claims 1 to 18 , wherein the p-type organic semiconductor is a conjugated organic polymer and / or the n-type organic semiconductor is a fullerene or a fullerene derivative. The formulation according to any one of claims 1 to 19 , wherein the p-type organic semiconductor has a kinematic viscosity in the range of 3.6 to 5.4 mPa · s in a tetralin solution at 25 ° C. Use of the formulation according to any one of claims 1 to 20 in the solution deposition method . 21. The use of the formulation according to claim 21, wherein the solution deposition method is an inkjet printing method. The formulation according to any one of claims 1 to 20 , which is a method for producing an organic electronic device including an anode, a cathode, and a photoactive layer between the cathode and the anode, according to a solution deposition method. A method comprising applying the photoactive layer to form the photoactive layer. 23. The method of claim 23, wherein the solution deposition method is an inkjet printing method. Use of the formulation according to any one of claims 1 to 20 as a coating or printing ink for the preparation of a photoactive thin film or photoactive layer.

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