CN111263986B - Printing ink containing thermally activated delayed fluorescence material and application thereof - Google Patents

Abstract

The invention discloses printing ink containing a thermal excitation delayed fluorescence material and application thereof, wherein the printing ink contains at least two organic functional materials H1 and H2 and at least one organic solvent, wherein the H1 and the H2 form a II-type semiconductor heterojunction structure, and the H2 has the characteristic of the thermal excitation delayed fluorescence material (TADF). The printing ink has better printing performance and film-forming performance, is convenient to realize high-performance organic electronic devices, particularly organic electroluminescent devices, through solution processing, particularly printing process, and provides a manufacturing technical scheme with low cost and high efficiency. Meanwhile, the luminous efficiency and the service life of the organic electronic device can be effectively improved.

Description

Printing ink containing thermally activated delayed fluorescence material and application thereof

The present application claims priority from the chinese patent application entitled "printing ink comprising thermally activated delayed fluorescence material and use thereof" filed by the chinese patent office on 21/12/2017 with application number 2017113945262, the entire contents of which are incorporated herein by reference.

Technical Field

The invention relates to the field of organic electronic devices, in particular to printing ink containing a thermally-excited delayed fluorescence material. The invention also relates to the use of the printing ink according to the invention in organic electronic components.

Background

Organic Light Emitting Diodes (OLEDs), which have excellent properties such as light weight, active light emission, wide viewing angle, high contrast, high light emitting efficiency, low power consumption, easy fabrication of flexible and large-sized panels, are considered as the most promising next-generation display technology in the industry. In order to improve the light emitting efficiency of the organic light emitting diode and promote the large-scale industrialization process of the organic light emitting diode, the key problems of the organic light emitting diode, namely the light emitting performance and the service life, are urgently needed to be solved.

To obtain a high performance organic light emitting diode, the host material is critical. Currently, a single main body material is generally adopted to prepare an OLED light-emitting device together with a light-emitting body, but the single main body material can cause different carrier transmission rates, so that the Roll-off (Roll-off) of the device efficiency is serious under high brightness, and the service life of the device is shortened. The double-main-body material can weaken some problems caused by a single main body, and particularly, the selected double-main-body material can effectively form a composite excited state (exiplex) through proper material matching, so that the luminous efficiency and the service life of the device are greatly improved. Kim et al (see Kim et al adv.Func. Mater.2013 DOI:10.1002/adfm.201300547, kim et al adv.Func. Mater.2013, DOI: 10.1002/adfm.201300187) achieve low Roll-off, high efficiency OLEDs by using Co-hosts (Co-hosts) that form complex excited states (exciplex) and adding a metal complex as phosphorescent emitters.

Further, in evaporation devices, by pre-forming the dual host materials into a blend or organic alloy, the evaporation process can be greatly simplified and the device lifetime significantly increased (patents US2016141505A1, WO2016060332A1, WO2016068450A1, WO2016068460A1, etc.). However, the vacuum evaporation process is expensive and requires a high processing requirement, such as a very precise shadow mask, so that the application of the organic light emitting diode as a large-area and low-cost display device and a lighting device is limited. In contrast, ink jet printing (inkjet printing) and roll-to-roll (roll-to-roll) solution processes are promising technologies for fabricating organic optoelectronic devices, especially organic light emitting diode displays, due to the outstanding advantages of no need of precision shadow masks, no need of greenhouse processes, high material utilization rate, good expandability, etc. Suitable printing inks and materials are critical to the process. Patent CN102498120A provides an efficient method for preparing organic small molecule functional materials suitable for solution processing. However, effective solutions to the problems of the inkjet printing process, efficient co-host material system, film drying process, printability of ink, etc. have not been proposed yet.

Therefore, new materials suitable for printing processes, particularly host material systems, and printing inks related thereto are under development.

Disclosure of Invention

Based on this, it is an object of the present application to provide a printing ink comprising a thermally activated delayed fluorescence material. It is a further object of the present invention to provide a use of the printing ink according to the invention for the preparation of organic electronic devices.

A printing ink comprising at least two organic functional materials H1 and H2, and at least one organic solvent: 1) The printing ink has a viscosity in the range of 1cPs to 100cPs at 25 ℃ and/or a surface tension in the range of 19dyne/cm to 50dyne/cm at 25 ℃; 2) H1 and H2 form a type II semiconductor heterojunction structure, and min ((LUMO (H1) -HOMO (H2), LUMO (H2) -HOMO (H1)) ≦ min (T1 (H1), T1 (H2)) +0.1eV, wherein LUMO (H1), HOMO (H1), and T1 (H1) are, in order, the lowest unoccupied orbital, the highest occupied orbital, the triplet level of H1, LUMO (H2), HOMO (H2), and T1 (H2) are, in order, the lowest unoccupied orbital, the highest occupied orbital, the triplet level of H2; 3) At least one of H1 and H2 has (S1-T1) less than or equal to 0.3eV, and S1 is a singlet energy level.

The application of the printing ink in preparing organic electronic devices.

An organic mixture comprising at least two organic functional materials H1 and H2: 1) Wherein the difference between the molecular weights of H1 and H2 is not less than 200g/mol or the difference between the sublimation temperatures of H1 and H2 is not less than 50K; 2) H1 and H2 form a type II semiconductor heterojunction structure, and min ((LUMO (H1) -HOMO (H2), LUMO (H2) -HOMO (H1)) ≦ min (S1 (H1), S1 (H2)) +0.1eV, wherein LUMO (H1), HOMO (H1) and S1 (H1) are respectively the lowest unoccupied orbital, the highest occupied orbital, the triplet level, LUMO (H2), HOMO (H2) and S1 (H2) are respectively the lowest unoccupied orbital, the highest occupied orbital, the triplet level of H2; 3) At least one of H1 and H2 has (S1-T1) less than or equal to 0.3eV, and S1 is a singlet level.

Compared with the prior art, the method has the following beneficial effects:

the printing ink at least comprises two organic functional materials and at least one organic solvent, has better printing performance and film-forming performance when used as a main material, and is convenient for realizing high-performance organic electronic devices, especially organic electroluminescent devices, through solution processing, especially printing process, thereby providing a manufacturing technical scheme with low cost and high efficiency. Meanwhile, the luminous efficiency and the service life of the organic electronic device can be effectively improved.

Drawings

Fig. 1 is a diagram of a semiconductor heterojunction structure in an embodiment showing two types (type I and type II) that are possible according to the relative positions of the energy levels of the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) when two organic semiconductor materials H1 and H2 are in contact, wherein the semiconductor heterojunction structure of type II is the energy level structure of the printing ink according to the present invention.

Detailed Description

The invention provides printing ink containing a thermally-excited delayed fluorescence material and application thereof. In order to make the objects, technical solutions and effects of the present invention clearer and clearer, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the embodiments of the present invention, the Host material, the Matrix material, the Host material, and the Matrix material have the same meaning and may be interchanged.

In the embodiments of the present invention, singlet states and singlet states have the same meaning and may be interchanged.

In the present examples, the triplet state, has the same meaning and can be interchanged.

In the present invention, printing inks and compositions, or inks, have the same meaning and are interchangeable.

In the present invention, the multiple excited states, exciplex, and exiplex have the same meaning and are interchangeable.

The term "small molecule" as defined herein refers to a molecule that is not a polymer, oligomer, dendrimer, or blend. In particular, there is no repeat structure in small molecules. The small molecules have a molecular weight of 3000 g/mol or less, preferably 2000 g/mol or less, and most preferably 1500 g/mol or less.

In the present invention, an aromatic ring system or an aromatic group means a hydrocarbon group containing at least one aromatic ring, including monocyclic groups and polycyclic ring systems. Heteroaromatic ring systems or heteroaromatic groups refer to hydrocarbon groups (containing heteroatoms) that contain at least one heteroaromatic ring, including monocyclic groups and polycyclic ring systems. These polycyclic rings may have two or more rings in which two carbon atoms are shared by two adjacent rings, i.e., fused rings. At least one of these ring species of the polycyclic ring is aromatic or heteroaromatic. For the purposes of the present invention, aromatic or heteroaromatic ring systems include not only aromatic or heteroaromatic systems, but also systems in which a plurality of aryl or heteroaryl groups may also be interrupted by short nonaromatic units (< 10% of non-H atoms, preferably less than 5% of non-H atoms, such as C, N or O atoms). Thus, for example, systems such as 9,9' -spirobifluorene, 9-diarylfluorene, triarylamines, diaryl ethers, etc., are likewise considered aromatic ring systems for the purposes of this invention.

In the embodiment of the present invention, the energy level structure of the organic material, the triplet energy level T1, the singlet energy level S1, the HOMO, and the LUMO play a key role. The determination of these energy levels is described below.

The HOMO and LUMO energy levels can be measured by the photoelectric effect, for example XPS (X-ray photoelectron spectroscopy) and UPS (ultraviolet photoelectron spectroscopy) or by cyclic voltammetry (hereinafter referred to as CV). Recently, quantum chemical methods, such as the density functional theory (hereinafter abbreviated as DFT), have become effective methods for calculating the molecular orbital level.

The triplet energy level T1 of the organic material can be measured by low temperature Time resolved luminescence spectroscopy, or can be obtained by quantum simulation calculations (e.g. by Time-dependent DFT), such as by commercial software Gaussian 03W (Gaussian inc.), specific simulation methods can be found in WO2011141110 or as described in the examples below.

It should be noted that the absolute values of HOMO, LUMO, T1 depend on the measurement or calculation method used, and even for the same method, different methods of evaluation, such as starting point and peak point on the CV curve, may give different HOMO/LUMO values. Thus, a reasonably meaningful comparison should be made with the same measurement method and the same evaluation method. In the description of the embodiment of the present invention, the values of HOMO, LUMO, and T1 are based on the Time-dependent DFT simulation, but do not affect the application of other measurement or calculation methods.

In the present invention, (HOMO-1) is defined as the second highest occupied orbital level, (HOMO-2) is the third highest occupied orbital level, and so on. (LUMO + 1) is defined as the second lowest unoccupied orbital level, (LUMO + 2) is the third lowest occupied orbital level, and so on.

The invention relates to a printing ink, comprising at least two organic functional materials H1 and H2, and at least one organic solvent, characterized in that: 1) The printing ink has a viscosity in the range of 1 to 100cPs at 25 ℃, and/or a surface tension in the range of 19 to 50dyne/cm at 25 ℃. 2) H1 and H2 form a semiconductor heterojunction structure of type II, and min ((LUMO (H1) -HOMO (H2), LUMO (H2) -HOMO (H1)) ≦ min (T1 (H1), T1 (H2)) +0.1eV, wherein LUMO (H1), HOMO (H1), and T1 (H1) are, in order, the lowest unoccupied orbital, the highest occupied orbital, the triplet level of H1, LUMO (H2), HOMO (H2), and T1 (H2) are, in order, the lowest unoccupied orbital, the highest occupied orbital, the triplet level of H2; 3) At least one of H1 and H2 has (S1-T1) less than or equal to 0.3eV.

In a preferred embodiment, the printing ink, S1 (H2) -T1 (H2). Ltoreq.0.25 eV.

In a preferred embodiment, the printing ink, S1 (H2) -T1 (H2). Ltoreq.0.20 eV.

In a more preferred embodiment, the printing ink, S1 (H2) -T1 (H2). Ltoreq.0.15 eV.

In another very preferred embodiment, the printing ink, S1 (H2) -T1 (H2). Ltoreq.0.1 eV.

In another particularly preferred embodiment, the printing ink, S1 (H2) -T1 (H2). Ltoreq.0.08 eV.

In another most preferred embodiment, the printing ink, S1 (H2) -T1 (H2). Ltoreq.0.05 eV.

In certain preferred embodiments, the printing ink according to the present invention wherein the difference in molecular weight of H1 and H2 is <50g/mol.

In some preferred embodiments, the printing inks according to the invention are those in which the difference between the molecular weights of H1 and H2 is greater than or equal to 50g/mol, preferably greater than or equal to 70g/mol, more preferably greater than or equal to 90g/mol, most preferably greater than or equal to 100g/mol.

In certain embodiments, a printing ink according to the present invention, wherein the difference in sublimation temperatures of H1 and H2 is <30K.

In certain preferred embodiments, the printing ink according to the invention has a difference between the sublimation temperatures of H1 and H2 of 30K or more, preferably 40K or more, more preferably 50K or more, and most preferably 60K or more.

In a co-host in an evaporation-type OLED, it is preferable that the two host materials have similar physicochemical properties, such as molecular weight and sublimation temperature. The present invention has found that in solution processed OLEDs, two host materials with different properties may improve the film forming properties and thus the performance of the device. The properties mentioned, in addition to the molecular weight and sublimation temperature, can also be other, such as glass transition temperature, different molecular volumes, etc. So that the following conditions may be substituted for the above-described condition 2):

a) The difference between the glass transition temperatures of H1 and H2 is not less than 20K, preferably not less than 30K, more preferably not less than 40K, most preferably not less than 45K.

b) The difference between the molecular volumes of H1 and H2 is not less than 20%, preferably not less than 30%, more preferably not less than 40%, most preferably not less than 45%. The molecular volume of the compound can be optimized for the molecular configuration, such as by Gaussian.

In another preferred embodiment, the printing ink according to the invention, the organic solvent has a viscosity in the range of 1 to 80cPs at 25 ℃; preferably in the range of 1cPs to 50 cPs; more preferably in the range of 1cPs to 40 cPs; more preferably in the range of 1cPs to 30 cPs; most preferably in the range of 1.5cps to 20 cps. The viscosity herein means the viscosity at the ambient temperature at the time of printing, and is generally 15 to 30 ℃, preferably 18 to 28 ℃, more preferably 20 to 25 ℃, most preferably 23 to 25 ℃. Printing inks so formulated will be particularly suitable for ink jet printing.

In a preferred embodiment, the printing ink according to the invention has a solubility of H1 and H2 in an organic solvent of 0.5wt% or more and a difference in the solubilities of H1 and H2 in an organic solvent of 0.2wt% or less.

In a preferred embodiment, the printing ink according to the invention has a solubility of said H1 and said H2 in an organic solvent of 0.5wt% or more; more preferably at least one organic functional material having a solubility in organic solvents of 1wt% or more; more preferably, the solubility of at least one organic functional material in the organic solvent is greater than or equal to 1.5wt%; more preferably at least one organic functional material having a solubility in organic solvents of 2wt% or more; most preferably, at least one of the organic functional materials has a solubility in organic solvents of greater than or equal to 2.5wt%.

In a preferred embodiment, the difference in solubility between H1 and H2 in the organic solvent is less than or equal to 0.2% by weight in the printing ink according to the invention; more preferably 0.15wt% or less; more preferably 0.1wt% or less; most preferably 0.05wt% or less.

In a preferred embodiment, the printing ink according to the invention, at least one of the molecular weights of H1 and H2 is greater than or equal to 600g/mol; more preferably at least one is 800g/mol or more; more preferably at least one of them is 900g/mol or more; very preferably at least one is 1000g/mol or more; most preferably at least one is 1100g/mol or more.

In a preferred embodiment, the printing ink according to the invention, the molecular weight of both H1 and H2 is greater than or equal to 600g/mol; more preferably, each is 800g/mol or more; more preferably, both are greater than or equal to 900g/mol; most preferably 1000g/mol or more in each case.

In a preferred embodiment, the printing ink according to the invention comprises the organic functional material in a weight ratio of the printing ink in the range of 0.3 to 30wt%, preferably in the range of 0.5 to 20wt%, more preferably in the range of 0.5 to 15wt%, even more preferably in the range of 0.5 to 10wt%, and most preferably in the range of 1 to 5wt%.

In a preferred embodiment, the printing ink according to the invention has at least one of the glass transition temperatures of H1 and H2 of 100 ℃ or higher; more preferably at least one of the carbon atoms is 120 ℃ or higher; more preferably at least one is 140 ℃ or higher; it is particularly preferred that at least one is 160 ℃ or higher.

In a preferred embodiment, in the printing ink according to the invention, the glass transition temperature of both H1 and H2 is greater than or equal to 100 ℃; more preferably, both are 120 ℃ or higher; more preferably, both are equal to or greater than 140 ℃; particularly preferably 160 ℃ or higher.

In a preferred embodiment, the molar ratio of said first organic functional material H1 to said second organic functional material H2 in the printing ink according to the invention is in the range of 1; more preferably 2; more preferably 3; more preferably 4; most preferably 5.

In some embodiments, the energy gap of the first organic functional material H1 is less than H2.

In certain preferred embodiments, the first organic functional material H1 has a larger energy gap than H2.

In a preferred embodiment, the first organic functional material H1 has electron transport properties, or hole transport properties, according to the printing ink of the present invention.

In a preferred embodiment, in a printing ink according to the invention, the HOMO- (HOMO-1)) of one of said H1 and H2 is ≧ 0.2eV, preferably ≧ 0.25eV, more preferably ≧ 0.3eV, still more preferably ≧ 0.35eV, very preferably ≧ 0.4eV, most preferably ≧ 0.45eV.

In a particularly preferred embodiment, the printing ink according to the invention has a value of ≧ 0.2eV (HOMO- (HOMO-1)), (HOMO-0.25 eV) is preferred, (. Gtoreq.0.3 eV is preferred, (. Gtoreq.0.35 eV is particularly preferred, (. Gtoreq.0.4 eV is most preferred, (. Gtoreq.0.45 eV) for each of said H1 and H2.

In a further preferred embodiment of the printing ink according to the invention, one of said H1 and H2 ((LUMO + 1) -LUMO) ≥ 0.15eV, preferably ≥ 0.20eV, more preferably ≥ 0.25eV, even more preferably ≥ 0.30eV, very preferably ≥ 0.35eV, most preferably ≥ 0.40eV.

In a further particularly preferred embodiment of the printing ink according to the invention, the (LUMO + 1) -LUMO) of each of said H1 and H2 is ≧ 0.15eV, preferably of H1 ((LUMO + 1) -LUMO) is ≧ 0.20eV, more preferably of ≧ 0.25eV, still more preferably of ≧ 0.30eV, very preferably of ≧ 0.35eV, most preferably of ≧ 0.40eV.

In a preferred embodiment, the printing ink according to the invention, wherein said H1 has the structure of formula (I):

wherein,

Z ⁴ ，Z ⁵ ，Z ⁶ are independently selected from N or CR ² . In certain embodiments, Z ⁴ ，Z ⁵ ，Z ⁶ One or two or three may be N.

Ar ¹ ～Ar ³ Identical or different are aromatic or heteroaromatic ring systems having 5 to 40 ring atoms, or aryloxy or heteroaryloxy groups having 5 to 40 ring atoms, or nonaromatic groups having 5 to 40 ring atoms, or combinations of these systems, where one or more radicalsCan be further substituted by R ² Substituted, or R ² May further form a ring system with the substituted group.

Preferably, ar ¹ ～Ar ³ Identical or different are aromatic or heteroaromatic ring systems having from 5 to 20 ring atoms, or aryloxy or heteroaryloxy groups having from 5 to 20 ring atoms, or nonaromatic groups having from 5 to 20 ring atoms, or combinations of these systems, where one or more radicals may further be substituted by R ² Substituted, or R ² May further form a ring system with the substituted group.

More preferably, ar ¹ ～Ar ³ Identical or different are substituted or unsubstituted aromatic or heteroaromatic ring systems having from 5 to 15 ring atoms, or aryloxy or heteroaryloxy groups having from 5 to 15 ring atoms, or nonaromatic groups having from 5 to 15 ring atoms, or combinations of these systems, where one or more radicals may be further substituted by R ² Substituted, or R ² May further form a ring system with the substituted group.

R ² Identical or different on each occurrence is H, D, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 20C atoms, or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 20C atoms or a silyl group, or a substituted keto group having 1 to 20C atoms, or an alkoxycarbonyl group having 2 to 20C atoms, or an aryloxycarbonyl group having 7 to 20C atoms, a cyano group (-CN), a carbamoyl group (-C (= O) NH-, a ₂ ) A haloformyl group (- = O) -X wherein X represents a halogen atom), a formyl group (- = C (= O) -H), an isocyano group, an isocyanate group, a thiocyanate group or an isothiocyanate group, a hydroxyl group, a nitro group, CF ₃ A group, cl, br, F, a crosslinkable group or a substituted or unsubstituted aromatic or heteroaromatic ring system having 5 to 40 ring atoms, or an aryloxy or heteroaryloxy group having 5 to 40 ring atoms, or a combination of these systems.

More preferably, R ² On each occurrence, the same or differentIs H, D, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 10C atoms, or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 10C atoms or is a silyl group, or a substituted keto group having 1 to 10C atoms, or an alkoxycarbonyl group having 2 to 10C atoms, or an aryloxycarbonyl group having 7 to 10C atoms, a cyano group (-CN), a carbamoyl group (- = C (= O) NH) ₂ ) A haloformyl group (- = O) -X wherein X represents a halogen atom), a formyl group (-C (= O) -H), an isocyano group, an isocyanate group, a thiocyanate group or an isothiocyanate group, a hydroxyl group, a nitro group, CF ₃ A group, cl, br, F, a crosslinkable group or a substituted or unsubstituted aromatic or heteroaromatic ring system having from 5 to 20 ring atoms or an aryloxy or heteroaryloxy group having from 5 to 20 ring atoms or a combination of these systems.

m, m1, m2 are independently 1 or 2 or 3. Preferably 1.

In a preferred embodiment, the printing inks according to the invention, ar in the general formula (I) ¹ -Ar ³ At multiple occurrences, they may be selected, identically or differently, from one or a combination of the following structural groups:

wherein n1 is 1 or 2 or 3 or 4.

In a very preferred embodiment, the printing ink according to the invention, wherein said H1 is a compound of one of the following formulae (II) to (V):

wherein，L ¹ Represents an aromatic group or an heteroaromatic group having 5 to 60 ring atoms.

L ² Represents a single bond, an aromatic group or an aromatic hetero group having 5 to 30 ring atoms.

Ar ⁴ -Ar ⁹ Each independently represents an aromatic or heteroaromatic ring system having 5 to 40 ring atoms.

X represents a single bond, N (R) ³ )、C(R ³ ) ₂ 、Si(R ³ ) ₂ 、O、C＝N(R ³ )、C＝C(R ³ ) ₂ 、P(R ³ )、P(＝O)R ³ S, S = O or SO ₂ 。

X ₂ -X ₉ Each independently represents a single bond, N (R) ³ )、C(R ³ ) ₂ 、Si(R ³ ) ₂ 、O、C＝N(R ³ )、C＝C(R ³ ) ₂ 、P(R ³ )、P(＝O)R ³ S, S = O or SO ₂ But X ₂ And X ₃ Not simultaneously being a single bond, X ₄ And X ₅ Not simultaneously being a single bond, X ₆ And X ₇ Not simultaneously being a single bond, X ₈ And X ₉ Not simultaneously a single bond.

R ³ 、R ⁴ 、R ⁵ Each independently represents H, D, F, CN, alkenyl, alkynyl, nitrile group, amino group, nitro group, acyl group, alkoxy group, carbonyl group, sulfone group, alkyl group having 1 to 30 carbon atoms, cycloalkyl group having 3 to 30 carbon atoms, aromatic hydrocarbon group having 5 to 60 ring atoms or aromatic heterocyclic group, wherein R is ⁴ 、R ⁵ Can be on any carbon atom of the fused ring and is substituted by R ⁴ 、R ⁵ There may be any plurality of substituted carbon atoms.

n2 represents an integer of 1 to 4. Preferably 2. Most preferably 1.

Preferably, R ³ 、R ⁴ 、R ⁵ Or L ¹ ，L ² At least one of which comprises an electron withdrawing group.

In a more preferred embodiment, the printing ink according to the invention, wherein said H1 is a compound represented by one of the following formulae (II-a) to (V-a):

wherein,

L1、X ₃ 、X ₄ 、、R ² 、R ³ 、R ⁴ as defined above;

l3 has the meaning of L1;

A ¹ 、A ² each independently represents an aromatic group or an aromatic hetero group having 5 to 30 ring atoms;

Y ¹ ～Y ¹⁷ each independently represents N, C (R) ² ) Adjacent to Y ¹ -Y ¹⁷ It cannot be N.

In certain preferred embodiments, the printing ink according to the present invention, wherein H1 and H2 cannot both be derivatives of indolocarbazole. In a preferred embodiment, the printing ink according to the invention, wherein H2 has Thermally Activated Delayed Fluorescence (TADF) characteristics.

According to the principle of thermally excited delayed fluorescence TADF materials (see Adachi et al, nature Vol 492,234, (2012)), when (S1-T1) of an organic compound is sufficiently small, triplet excitons of the organic compound can be internally converted to singlet excitons by inversion, thereby achieving high-efficiency light emission. Generally, TADF materials are obtained by linking an electron donating (Donor) group and an electron deficient or electron withdrawing (Acceptor) group, directly or through other groups, i.e. having a distinct D-a structure.

The printing inks according to the invention have a smaller H2 with (S1-T1), typically (S1-T1). Ltoreq.0.30 eV, preferably.ltoreq.0.25 eV, particularly preferably.ltoreq.0.20 eV, particularly preferably.ltoreq.0.15 eV, particularly preferably.ltoreq.0.10 eV, in particular preferably.ltoreq.0.08 eV, most particularly preferably.ltoreq.0.05 eV.

In a particularly preferred embodiment, the printing inks according to the invention have H2 which comprises at least one electron-donating group and/or at least one electron-withdrawing group and have the general formula (VI):

wherein Ar is a single bond or a substituted or unsubstituted aromatic or heteroaromatic structural unit, W may be independently selected from the same or different electron-donating groups when occurring multiple times, A may be independently selected from the same or different electron-withdrawing groups when occurring multiple times, n, p are integers between 1 and 6, ar is further substituted with R ₀ Substituted or unsubstituted, R ₀ An alkyl group having 1 to 5 carbon atoms.

When Ar is a single bond, W and A are directly connected.

Examples of suitable electron-withdrawing groups A are shown below, but are not limited thereto, and they may be further optionally substituted:

examples of suitable electron-donating groups W are shown below, but not limited thereto, which may be further optionally substituted:

further electron donating groups W may be selected from the group consisting of:

further electron withdrawing groups A may be selected from F, cyano or a structure comprising:

wherein o is 1,2 or 3; x ¹ -X ⁸ Is selected from CR ⁶ Or N, and at least one is N; m is a group of ¹ 、M ² 、M ³ Each independently represents N (R) ⁶ )、C(R ⁶ 6R ⁷ )、Si(R ⁶ R ⁷ )、O、C＝N(R ⁶ )、C＝C(R ⁶ R ⁷ )、P(R)、P(＝O)R ⁶ 、S、S＝O、SO ₂ Or none; r ⁶ 、R ⁷ See claim 9 for R ³ 。

In a very preferred embodiment, H2 has a structure represented by formulas (II) - (V) and comprises at least one electron withdrawing group as described above.

In certain preferred embodiments, the printing ink according to the present invention, wherein H1 and H2 are not both indolocarbazole derivatives.

Further TADF materials suitable as H2 can be found in the following patent documents: CN103483332 (a), TW201309696 (a), TW201309778 (a), TW201343874 (a), TW201350558 (a), US20120217869 (A1), WO2013133359 (A1), WO2013154064 (A1), adachi, et.al.adv.mater, 21,2009,4802, adachi, et.al.appl.lett.98, 2011,083302, adachi, et.al.phys.lett.101, 2012,093306, adachi, et.chem.comm., 48,2012,11392, adachi, et.al.natu photomoni, 6,2012,253, adachi, 492, natu, 234, 11392, adachi, 2012,23, et.natu chem.t.t.t.7, adachi, chem.73, chem.14711, adachi, chem.t.t.t.t.t.t.t. 48,2012,9580, adachi,et al chem.commun, 48,2013,10385, adachi,et al adv.mater, 25,2013,3319, adachi,et al adv.mater, 25,2013,3707, adachi,et al chem.mater, 25,2013,3038, adachi,et al chem.mater, 25,2013,3766, adachi,et al j.mater.chem.c, 1,2013,4599, adachi,al.j.phys.chem.a, 117,2013,7, the entire contents of the patents or articles listed above are hereby incorporated herein by reference.

Specific examples that may be used as H2 are listed below, but are not limited to:

in a preferred embodiment of the printing ink according to the invention, said first organic functional material H1 is preferably selected from, but not limited to, the following structures:

in a preferred embodiment, the printing ink according to the present invention further comprises a third organic functional material, wherein the third organic functional material is selected from hole (also called hole) injection or transport material (HIM/HTM), hole Blocking Material (HBM), electron injection or transport material (EIM/ETM), electron Blocking Material (EBM), organic matrix material (Host), singlet emitter (fluorescent emitter), triplet emitter (phosphorescent emitter), thermal emission delayed fluorescent material (TADF) and organic dye. Various organic functional materials are described in detail, for example, in O2010135519A1, US20090134784A1 and WO2011110277A1, the entire contents of this 3 patent document being hereby incorporated by reference.

In certain preferred embodiments, the printing ink according to the present invention, wherein H2 and said third organic functional material are not simultaneously selected from indolocarbazole derivatives.

In a most preferred embodiment, said printing ink, wherein said third organic functional material is selected from singlet emitters (fluorescent emitters), triplet emitters (phosphorescent emitters) or TADF emitters.

In a preferred embodiment, the printing ink contains the abovementioned H1 and H2, and a phosphorescent emitter, where the percentage by weight of the phosphorescent emitter in all functional materials (excluding solvent) is less than or equal to 30% by weight, preferably less than or equal to 25% by weight, more preferably less than or equal to 20% by weight. Particularly preferred are phosphorescent emitters having triplet energy levels ≦ min (T1 (H1), T1 (H2).

In another preferred embodiment, the printing ink comprises H1 and H2 as described above, and a fluorescent emitter. Wherein the weight percentage of the fluorescent luminophor in all functional materials (excluding solvent) is less than or equal to 15wt percent, preferably less than or equal to 10wt percent, and more preferably less than or equal to 8wt percent.

In another preferred embodiment, the printing ink comprises H1 and H2 as described above, and a TADF phosphor. Wherein the weight percentage of the TADF luminescent material in all functional materials (excluding solvent) is less than or equal to 15wt%, preferably less than or equal to 10wt%, and more preferably less than or equal to 8wt%. Singlet emitters and triplet emitters are described in some more detail below (but not limited thereto).

1. Singlet state luminophor (Singlet Emitter)

Singlet emitters tend to have longer conjugated pi-electron systems. To date, there have been many examples such as styrylamine and its derivatives disclosed in JP2913116B and WO2001021729A1, indenofluorene and its derivatives disclosed in WO2008/006449 and WO2007/140847, and triarylamine derivatives of pyrene disclosed in US7233019, KR 2006-0006760.

In a preferred embodiment, the singlet emitters may be selected from the group consisting of monostyrenes, distyrenes, tristyrenes, tetrastyrenes, styrylphosphines, styryl ethers, and arylamines.

A monostyrene amine is a compound comprising an unsubstituted or substituted styryl group and at least one amine, preferably an aromatic amine. A distyrene amine refers to a compound comprising two unsubstituted or substituted styryl groups and at least one amine, preferably an aromatic amine. A tristyrenylamine refers to a compound comprising three unsubstituted or substituted styrene groups and at least one amine, preferably an aromatic amine. A tetrastyrene amine refers to a compound comprising four unsubstituted or substituted styrene groups and at least one amine, preferably an aromatic amine. One preferred styrene is stilbene, which may be further substituted. The corresponding phosphines and ethers are defined analogously to the amines. Arylamine or aromatic amine refers to a compound comprising three unsubstituted or substituted aromatic rings or heterocyclic systems directly linked to nitrogen. At least one of these aromatic or heterocyclic ring systems is preferably a fused ring system and preferably has at least 14 aromatic ring atoms. Among them, preferred examples are aromatic anthracenamines, aromatic anthracenediamines, aromatic pyrenediamines, aromatic chrysenamines and aromatic chrysenediamines. An aromatic anthracylamine refers to a compound in which a diarylamine group is attached directly to the anthracene, preferably at the 9 position. An aromatic anthracenediamine refers to a compound in which two diarylamine groups are attached directly to the anthracene, preferably at the 9,10 position. Aromatic pyrene amines, aromatic pyrenediamines, aromatic chrysenes and aromatic chrysenes are similarly defined, wherein preferably the diarylamine groups are attached to the 1 or 1,6 position of pyrene.

Examples, which are also preferred, of singlet emitters based on vinylamines and arylamines can be found in the following patent documents: WO 2006/000388, WO 2006/058737, WO 2006/000389, WO 2007/065549, WO 2007/115610, US 7250532B 2, DE 102005058557 A1, CN 1583691A, JP 08053397A, US 6251531B 1, US 2006/210830A, EP 1957606 A1 and US 2008/0113101 A1 the entire contents of the patent documents listed above are hereby incorporated by reference.

An example of singlet emitters based on stilbene and on their derivatives is U.S. Pat. No. 5,1187,1187.

Further preferred singlet emitters may be selected from indenofluorene-amines and indenofluorene-diamines, as disclosed in WO2006/122630, benzindenofluorene-amines and benzindenofluorene-diamines, as disclosed in WO2008/006449, dibenzoindenofluorene-amines and dibenzoindenofluorene-diamines, as disclosed in WO 2007/140847.

Further preferred singlet emitters may be selected from fluorene based fused ring systems as disclosed in US2015333277A1, US2016099411A1, US2016204355 A1.

More preferred singlet emitters may be selected from derivatives of pyrene, such as the structures disclosed in US2013175509 A1; triarylamine derivatives of pyrene, such as triarylamine derivatives of pyrene containing dibenzofuran units as disclosed in CN 102232068B; other triarylamine derivatives of pyrene having specific structures are disclosed in CN105085334A, CN 105037173A. Other materials which can be used as singlet emitters are polycyclic aromatic compounds, in particular derivatives of the following compounds: anthracenes such as 9,10-bis (2-naphthoanthracene), naphthalenes, tetraphenes, xanthenes, phenanthrenes, pyrenes (such as 2,5,8,11-tetra-t-butylperylene), indenopyrenes, phenylenes such as (4,4 '-bis (9-ethyl-3-carbazolylethenyl) -1,1' -biphenyl), diindenopyrenes, decacycloalkenes, coronenes, fluorenes, spirobifluorenes, arylpyrenes (such as US 20060222886), aryleneethylenes (such as US5121029, US 5130603), cyclopentadienes such as tetraphenylcyclopentadiene, rubrene, coumarins, rhodamines, quinacridones, pyrans such as 4 (dicyanomethylene) -6- (4-p-dimethylaminostyryl-2-methyl) -4H-pyran (DCM), thiopyrans, bis (azinyl) imine boron compounds (US 2007/00753 A1), bis (azinyl) methylene compounds, carbostyryl compounds, oxazinones, benzoxazoles, benzimidazoles and pyrrolopyrrole diketones. Some singlet emitter materials can be found in the following patent documents: US20070252517 A1, US4769292, US6020078, US2007/0252517 A1. The entire contents of the above listed patent documents are hereby incorporated by reference.

Some examples of suitable singlet emitters are listed in the following table:

2. triplet Emitter (Triplet Emitter)

Triplet emitters are also known as phosphorescent emitters. In a preferred embodiment, the triplet emitter is a metal complex of the general formula M (L) n, where M is a metal atom, L, which may be the same or different at each occurrence, is an organic ligand which is bonded or coordinately bound to the metal atom M via one or more positions, and n is an integer greater than 1, preferably 1,2,3,4,5 or 6. Optionally, the metal complexes are coupled to a polymer through one or more sites, preferably through organic ligands.

In a preferred embodiment, the metal atom M is chosen from transition metals or lanthanides or actinides, preferably Ir, pt, pd, au, rh, ru, os, sm, eu, gd, tb, dy, re, cu or Ag, particularly preferably Os, ir, ru, rh, re, pd, au or Pt.

Preferably, the triplet emitter comprises a chelating ligand, i.e. a ligand, which coordinates to the metal via at least two binding sites, particularly preferably the triplet emitter comprises two or three identical or different bidentate or polydentate ligands. Chelating ligands are advantageous for increasing the stability of the metal complex.

Examples of organic ligands may be selected from phenylpyridine derivatives, 7, 8-benzoquinoline derivatives, 2 (2-thienyl) pyridine derivatives, 2 (1-naphthyl) pyridine derivatives, or 2-phenylquinoline derivatives. All of these organic ligands may be substituted, for example by fluorine-containing or trifluoromethyl groups. The ancillary ligands may preferably be selected from acetone acetate or picric acid.

In a preferred embodiment, the metal complexes which can be used as triplet emitters are of the form:

where M is a metal selected from the transition metals or the lanthanides or actinides, particularly preferably Ir, pt, au;

Ar ₁ each occurrence of which may be the same or different, is a cyclic group containing at least one donor atom, i.e., an atom having a lone pair of electrons, such as nitrogen or phosphorus, through which the cyclic group is coordinately bound to the metal; ar (Ar) ₂ Each occurrence, which may be the same or different, is a cyclic group containing at least one C atom through which the cyclic group is attached to the metal; ar (Ar) ₁ And Ar ₂ Linked together by a covalent bond, may each carry one or more substituent groups, which may in turn be linked together by substituent groups; l', which may be the same or different at each occurrence, is a bidentate chelating ancillary ligand, preferably a monoanionic bidentate chelating ligand; x may be 0,1,2 or 3, preferably 2 or 3; y may be 0,1,2 or 3, preferably 1 or 0.

<xnotran> : WO 200070655,WO 200141512,WO 200202714,WO 200215645,EP 1191613,EP 1191612,EP 1191614,WO 2005033244,WO 2005019373,US 2005/0258742,WO 2009146770,WO 2010015307,WO 2010031485,WO 2010054731,WO 2010054728,WO 2010086089,WO 2010099852,WO 2010102709,US 20070087219 A1,US 20090061681 A1,US 20010053462 A1,Baldo,Thompson et al.Nature 403, (2000), 750-753,US 20090061681 A1,US 20090061681 A1,Adachi et al.Appl.Phys.Lett.78 (2001), 1622-1624,J.Kido et al.Appl.Phys.Lett.65 (1994), 2124,Kido et al.Chem.Lett.657,1990,US 2007/0252517 A1,Johnson et al., JACS 105,1983,1795,Wrighton,JACS 96,1974,998,Ma et al., synth.Metals 94,1998,245,US 6824895,US 7029766,US 6835469,US 6830828,US 20010053462 A1,WO 2007095118 A1,US 2012004407A1,WO 2012007088A1,WO2012007087A1,WO 2012007086A1,US 2008027220A1,WO 2011157339A1,CN 102282150A,WO 2009118087A1,WO 2013107487A1,WO 2013094620A1,WO 2013174471A1,WO 2014031977A1,WO 2014112450A1,WO 2014007565A1,WO 2014038456A1,WO 2014024131A1,WO 2014008982A1,WO2014023377A1. </xnotran> The entire contents of the above listed patent documents and literature are hereby incorporated by reference.

Some examples of suitable triplet emitters are listed in the following table:

in a preferred embodiment, the printing ink according to the invention is a printing ink wherein the organic solvent is selected from one or a mixture of two or more of aromatic or heteroaromatic, ester, aromatic ketone or aromatic ether, aliphatic ketone or aliphatic ether, alicyclic or olefinic compounds, or borate or phosphate compounds.

In another preferred embodiment, the printing ink according to the invention, the organic solvent has a surface tension at 25 ℃ in the range of 20dyne/cm to 45 dyne/cm; more preferably in the range of 22dyne/cm to 35 dyne/cm; preferably in the range of 25dyne/cm to 33 dyne/cm.

In a preferred embodiment, the printing ink according to the invention, the at least one organic solvent is chosen from aromatic-or heteroaromatic-based solvents.

Examples of aromatic or heteroaromatic based solvents suitable for the present invention are, but not limited to: <xnotran> , , , , ,1,4- ,3- , , , , , , , ,1,2,3,4- ,1,2,3,5- ,1,2,4,5- , , , , , , , , ,3- , ,1- ,1,2,4- ,4,4- ,1,2- -4- (1- ) , ,2- ,3- , N- ,4- , - ,4- (3- ) , ,1,1- (3,4- ) ,2- , , ,2- ,2- . </xnotran>

Examples of aromatic ketone-based solvents suitable for the present invention are, but not limited to: 1-tetralone, 2- (phenylepoxy) tetralone, 6- (methoxy) tetralone, acetophenone, propiophenone, benzophenone, and derivatives thereof, such as 4-methylacetophenone, 3-methylacetophenone, 2-methylacetophenone, and the like.

Examples of aromatic ether-based solvents suitable for the present invention are, but not limited to: 3-phenoxytoluene, butoxybenzene, p-anisaldehyde dimethylacetal, tetrahydro-2-phenoxy-2H-pyran, 1, 2-dimethoxy-4- (1-propenyl) benzene, 1, 4-benzodioxan, 1, 3-dipropylbenzene, 2, 5-dimethoxytoluene, 4-ethylphenetole, 1, 3-dipropoxybenzene, 1,2, 4-trimethoxybenzene, 4- (1-propenyl) -1, 2-dimethoxybenzene, 1, 3-dimethoxybenzene, glycidylphenyl ether, dibenzyl ether, 4-t-butylanisole, trans-p-propenylanisole, 1, 2-dimethoxybenzene, 1-methoxynaphthalene, diphenyl ether, 2-phenoxymethyl ether, 2-phenoxytetrahydrofuran, ethyl-2-naphthyl ether.

In some preferred embodiments, the at least one organic solvent may be selected from: aliphatic ketones such as 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone, 2, 5-hexanedione, 2,6, 8-trimethyl-4-nonanone, fenchyne, phorone, isophorone, di-n-amyl ketone, etc.; or aliphatic ethers such as amyl ether, hexyl ether, dioctyl ether, ethylene glycol dibutyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol ethyl methyl ether, triethylene glycol butyl methyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and the like.

In further preferred embodiments, the at least one organic solvent may be selected from ester-based solvents: alkyl octanoates, alkyl sebacates, alkyl stearates, alkyl benzoates, alkyl phenylacetates, alkyl cinnamates, alkyl oxalates, alkyl maleates, alkyl lactones, alkyl oleates, and the like. Octyl octanoate, diethyl sebacate, diallyl phthalate, isononyl isononanoate are particularly preferred.

In a particularly preferred embodiment, the printing inks according to the invention are such that the at least one organic solvent is selected from the group consisting of 1-tetralone, 3-phenoxytoluene, acetophenone, 1-methoxynaphthalene, p-diisopropylbenzene, pentylbenzene, tetrahydronaphthalene, cyclohexylbenzene, chloronaphthalene, 1, 4-dimethylnaphthalene, 3-isopropylbiphenyl, p-methylisopropylbenzene, dipentyl-benzene, o-diethylbenzene, m-diethylbenzene, p-diethylbenzene, 1,2,3, 4-tetramethylbenzene, 1,2,3, 5-tetramethylbenzene, 1,2,4, 5-tetramethylbenzene, butylbenzene, dodecylbenzene, 1-methylnaphthalene, 1,2, 4-trichlorobenzene, diphenyl ether, diphenylmethane, 4-isopropylbiphenyl, benzyl benzoate, 1-bis (3, 4-dimethylphenyl) ethane, 2-isopropylnaphthalene, dibenzyl ether, octyl octanoate, diethyl sebacate, diallyl phthalate, isononyl isononanoate

The solvents mentioned may be used alone or as a mixture of two or more organic solvents.

In some preferred embodiments, the printing ink according to the present invention comprises an organic functional compound and at least one organic solvent, and may further comprise another organic solvent, and examples of the another organic solvent include (but are not limited to): methanol, ethanol, 2-methoxyethanol, methylene chloride, chloroform, chlorobenzene, o-dichlorobenzene, tetrahydrofuran, anisole, morpholine, toluene, o-xylene, m-xylene, p-xylene, 1,4 dioxane, acetone, methyl ethyl ketone, 1,2 dichloroethane, 3-phenoxytoluene, 1-trichloroethane, 1, 2-tetrachloroethane, ethyl acetate, butyl acetate, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, tetrahydronaphthalene, decalin, indene, and/or mixtures thereof.

In some preferred embodiments, particularly suitable solvents for the present invention are those having Hansen (Hansen) solubility parameters within the following ranges:

δ _d (dispersion force) is 17.0-23.2 MPa ^1/2 In particular in the range from 18.5 to 21.0MPa ^1/2 A range of (d);

δ _p (polar force) is 0.2-12.5 MPa ^1/2 In particular in the range from 2.0 to 6.0MPa ^1/2 A range of (d);

δ _h (hydrogen bonding force) is 0.9-14.2 MPa ^1/2 In particular in the range of 2.0 to 6.0MPa ^1/2 The range of (1).

The printing inks according to the invention are those in which the organic solvent is selected taking into account its boiling point parameter. In the invention, the boiling point of the organic solvent is more than or equal to 150 ℃; preferably equal to or more than 180 ℃; more preferably more than or equal to 200 ℃; more preferably not less than 250 ℃; most preferably more than or equal to 275 ℃ or more than or equal to 300 ℃. Boiling points in these ranges are beneficial for preventing nozzle clogging in inkjet print heads. The organic solvent may be evaporated from the solvent system to form a thin film comprising the functional material.

The invention also relates to the use of said printing inks as printing inks in the production of organic electronic devices, particularly preferably by printing or coating methods.

Suitable printing or coating techniques include, but are not limited to, ink jet printing, letterpress printing, screen printing, dip coating, spin coating, doctor blade coating, roll printing, twist roll printing, lithographic printing, flexographic printing, rotary printing, spray coating, brush or pad printing, slot die coating, and the like. Gravure printing, screen printing and ink jet printing are preferred. Gravure printing, ink jet printing, will be used in the examples of the present invention. The solution or suspension may additionally include one or more components such as surface active compounds, lubricants, wetting agents, dispersants, hydrophobing agents, binders, and the like, for adjusting viscosity, film forming properties, enhancing adhesion, and the like. For details on the printing technology and its requirements concerning the solutions, such as solvents and concentrations, viscosities, etc., see the Handbook of Print Media, techniques and Production Methods, by Helmut Kipphan, ISBN 3-540-67326-1.

In the above method, the thickness of the formed functional layer is 5nm-1000nm.

The invention also relates to an organic mixture comprising at least two organic functional materials H1 and H2: 1) Wherein the difference between the molecular weights of H1 and H2 is not less than 200g/mol or the difference between the sublimation temperatures of H1 and H2 is not less than 50K; 2) H1 and H2 form a semiconductor heterojunction structure of type II, and min ((LUMO (H1) -HOMO (H2), LUMO (H2) -HOMO (H1)) ≦ min (S1 (H1), S1 (H2)) +0.1eV, wherein LUMO (H1), HOMO (H1), and S1 (H1) are respectively the lowest unoccupied orbital, the highest occupied orbital, the triplet level, LUMO (H2), HOMO (H2), and S1 (H2) are respectively the lowest unoccupied orbital, the highest occupied orbital, the triplet level of H2; 3) (S1-T1) of at least one of H1 and H2 is not more than 0.3eV, preferably not more than 0.25eV, more preferably not more than 0.20eV, still more preferably not more than 0.15eV, most preferably not more than 0.10eV.

In a preferred embodiment, the organic mixture is one in which the difference between the molecular weights of H1 and H2 is 250g/mol or more, preferably 250g/mol or more, more preferably 300g/mol or more, most preferably 350g/mol or more; or the difference between the sublimation temperatures of H1 and H2 is not less than 60K, preferably not less than 70K, more preferably not less than 75K, most preferably not less than 80K.

Preferably, the organic mixture comprises a third organic functional material, and the third organic functional material is selected from hole (also called hole) injection or transport material (HIM/HTM), hole Blocking Material (HBM), electron injection or transport material (EIM/ETM), electron Blocking Material (EBM), organic Host material (Host), singlet emitter (fluorescent emitter), triplet emitter (phosphorescent emitter), thermal excitation delayed fluorescence material (TADF) and organic dye. Various organic functional materials are described in detail, for example, in O2010135519A1, US20090134784A1 and WO2011110277A1, the entire contents of this 3 patent document being hereby incorporated by reference.

In a most preferred embodiment, the organic mixture comprises a third organic functional material selected from singlet emitters (fluorescent emitters), triplet emitters (phosphorescent emitters) or TADF emission.

The invention further relates to an organic electronic device comprising at least one functional layer which is formed by printing a printing ink as described above. The Organic electronic device can be selected from, but not limited to, organic Light Emitting Diodes (OLEDs), organic photovoltaic cells (OPVs), organic light Emitting cells (OLEECs), organic Field Effect Transistors (OFETs), organic light Emitting field effect transistors (effets), organic lasers, organic spintronic devices, organic sensors, organic Plasmon Emitting diodes (Organic plasma Emitting diodes), and the like, and particularly preferred are Organic electroluminescent devices such as OLEDs, OLEECs, organic light Emitting field effect transistors.

In some particularly preferred embodiments, the organic electroluminescent device comprises at least one luminescent layer, which is prepared from the printing ink as described above.

In the above-mentioned light emitting device, especially an OLED, it comprises a substrate, an anode, at least one light emitting layer, and a cathode.

The substrate may be opaque or transparent. A transparent substrate may be used to fabricate a transparent light emitting device. See, for example, bulovic et al Nature 1996,380, p29, and Gu et al appl. Phys. Lett.1996,68, p2606. The substrate may be rigid or flexible. The substrate may be plastic, metal, semiconductor wafer or glass. Preferably, the substrate has a smooth surface. A substrate free of surface defects is a particularly desirable choice. In a preferred embodiment, the substrate is flexible, and may be selected from polymeric films or plastics having a glass transition temperature Tg of 150 ℃ or higher, preferably above 200 ℃, more preferably above 250 ℃, and most preferably above 300 ℃. Examples of suitable flexible substrates are poly (ethylene terephthalate) (PET) and polyethylene glycol (2, 6-naphthalene) (PEN).

The anode may comprise a conductive metal or metal oxide, or a conductive polymer. The anode can easily inject holes into a Hole Injection Layer (HIL) or a Hole Transport Layer (HTL) or an emission layer. In one embodiment, the absolute value of the difference between the work function of the anode and the HOMO level or valence band level of the emitter in the light emitting layer or the p-type semiconductor material acting as a HIL or HTL or Electron Blocking Layer (EBL) is less than 0.5eV, preferably less than 0.3eV, most preferably less than 0.2eV. Examples of anode materials include, but are not limited to: al, cu, au, ag, mg, fe, co, ni, mn, pd, pt, ITO, aluminum-doped zinc oxide (AZO), and the like. Other suitable anode materials are known and can be readily selected for use by one of ordinary skill in the art. The anode material may be deposited using any suitable technique, such as a suitable physical vapor deposition method including radio frequency magnetron sputtering, vacuum thermal evaporation, electron beam (e-beam), and the like. In certain embodiments, the anode is patterned. Patterned ITO conductive substrates are commercially available and can be used to prepare devices according to the present invention.

The cathode may comprise a conductive metal or metal oxide. The cathode can easily inject electrons into the EIL or ETL or directly into the light emitting layer. In one embodiment, the absolute value of the difference between the work function of the cathode and the LUMO level or conduction band level of the emitter in the light-emitting layer or of the n-type semiconductor material as Electron Injection Layer (EIL) or Electron Transport Layer (ETL) or Hole Blocking Layer (HBL) is less than 0.5eV, preferably less than 0.3eV, most preferably less than 0.2eV. In principle, all materials which can be used as cathodes in OLEDs are possible as cathode materials for the device according to the invention. Examples of cathode materials include, but are not limited to: al, au, ag, ca, ba, mg, liF/Al, mgAg alloy, baF ₂ Al, cu, fe, co, ni, mn, pd, pt, ITO, etc. The cathode material may be deposited using any suitable technique, such as a suitable physical vapor deposition method, including radio frequency magnetron sputtering, vacuum thermal evaporation, electron beam (e-beam), and the like.

The OLED may also comprise further functional layers, such as a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), an Electron Blocking Layer (EBL), an Electron Injection Layer (EIL), an Electron Transport Layer (ETL), a Hole Blocking Layer (HBL). Materials suitable for use in these functional layers are described in detail above and in WO2010135519A1, US20090134784A1 and WO2011110277A1, the entire contents of these 3 patent documents being hereby incorporated by reference.

The light-emitting device according to the present invention emits light at a wavelength of 300 to 1000nm, preferably 350 to 900nm, more preferably 400 to 800 nm.

The invention also relates to the use of the electroluminescent device according to the invention in various electronic devices, including, but not limited to, display devices, lighting devices, light sources, sensors, etc.

The present invention will be described in connection with preferred embodiments, but the present invention is not limited to the following embodiments, and it should be understood that the appended claims outline the scope of the present invention and those skilled in the art, guided by the inventive concept, will appreciate that certain changes may be made to the embodiments of the invention, which are intended to be covered by the spirit and scope of the appended claims.

Organic functional materials referred to in the examples:

the energy level of the organic functional material can be obtained by quantum calculation, for example, by using TD-DFT (including time density functional theory) through Gaussian09W (Gaussian inc.), and a specific simulation method can be referred to in WO2011141110. Firstly, a Semi-empirical method of 'group State/Semi-empirical/Default Spin/AM 1' (Charge 0/Spin Singlet) is used for optimizing the molecular geometrical structure, and then the energy structure of the organic molecules is calculated by a TD-DFT (time-density functional theory) method to obtain 'TD-SCF/DFT/Default Spin/B3PW 91' and a base group of '6-31G (d)' (Charge 0/Spin Singlet). The HOMO and LUMO energy levels were calculated according to the following calibration formula, S1, T1 used directly.

HOMO(eV)＝((HOMO(G)×27.212)-0.9899)/1.1206

LUMO(eV)＝((LUMO(G)×27.212)-2.0041)/1.385

Wherein HOMO (G) and LUMO (G) are the direct calculation of Gaussian09W, in Hartree. The results are shown in table one:

watch 1

Wherein,

the compound H1-1 and the compound H1-2 are used for the first organic functional material;

the compound H2-1 and the compound H2-2 are used for the second organic functional material.

H1-1 (WO 2015156449); h1-2 (WO 2007063796); h2-1 (WO 2008056746); the synthesis method of H2-2 (US 2012238105) refers to related patents respectively.

Preparation of printing ink:

examples preparation of a third organic functional material contained in a printing ink is a metal complex E1 shown in the following formula, which is synthesized as a phosphorescent guest in patent CN102668152.

The printing ink is prepared according to the following matching mode, and the molar ratio of the first organic functional material to the second organic functional material is 1.

Example 1: compound H1-1+ Compound H2-1 (LUMO (H2-1) -HOMO (H1-1) =2.57 eV)

Example 2: compound H1-1+ Compound H2-2 (LUMO (H2-2) -HOMO (H1-1) =2.56 eV)

Example 3: compound H1-2+ compound H2-1 (LUMO (H2-1) -HOMO (H1-2) =2.63 eV)

Example 4: compound H1-2+ compound H2-2 (LUMO (H2-2) -HOMO (H1-2) =2.62 eV)

The preparation method of the printing ink comprises the following steps:

a stirrer was placed in the vial, and the vial was washed clean and transferred to a glove box. A vial was charged with 9.8g of 3-phenoxytoluene solvent. 0.19g of the mixture of examples 1 to 4 and 0.01g of E1 were weighed into a solvent system in a vial in a glove box and mixed with stirring. After stirring at 60 ℃ until the organic mixture was completely dissolved, it was cooled to room temperature. The resulting organic mixture solution was filtered through a 0.2um PTFE membrane, sealed and stored.

The viscosity of the printing ink was measured by DV-I Prime Brookfield rheometer; the surface tension of the printing ink was measured by SITA bubble pressure tensiometer.

The above tests show that the 4 printing inks obtained have viscosity ranging from 5.7 + -0.5 cPs to 6.4 + -0.5 cPs and surface tension ranging from 32.3 + -0.5 dyne/cm to 34.1 + -0.5 dyne/cm.

In a further experiment, the mixtures of examples 1 to 4 were used to prepare printing inks in the following solvents: 1-tetralone, 1-methoxynaphthalene, tetrahydronaphthalene, cyclohexylbenzene, chloronaphthalene, 1, 4-dimethylnaphthalene, 3-isopropylbiphenyl, p-methylisoprene, dipentylbenzene, o-diethylbenzene, p-diethylbenzene, 1,2,3, 4-tetramethylbenzene, 1,2,3, 5-tetramethylbenzene, 1,2,4, 5-tetramethylbenzene, dodecylbenzene, 1-methylnaphthalene, 4-isopropylbiphenyl, benzyl benzoate, 1-bis (3, 4-dimethylphenyl) ethane, 2-isopropylnaphthalene, and dibenzyl ether, wherein the viscosity of the obtained printing ink is in the range of 2-20cPs, and the viscosity can be further adjusted by combining solvents and other methods, so that the printing ink can meet the requirements of ink-jet printing and other technologies.

Comparative example 1:

the composition was prepared as in example 1 above, the only difference being the substitution of compound H2-1 for the combination of compound H1-1+ compound H2-1.

Comparative example 2:

the composition was prepared as described above in example 2, with the only difference that compound H2-2 was substituted for the combination of compound H1-1+ compound H2-2.

Comparative example 3:

the composition was prepared as in example 2 above, with the only difference that the combination of compound H1-1+ compound H2-2 was replaced with the combination of compound H2-1+ compound Host.

Preparing an OLED device:

with ITO/HIL/HTL/EML (example 1-example 4, one of comparative examples 1-comparative examples 3)/Al, the OLED device was prepared as follows:

1) Cleaning an ITO transparent electrode (anode) glass substrate: carrying out ultrasonic treatment for 30 minutes by using an aqueous solution of 5% Decon90 cleaning solution, then carrying out ultrasonic cleaning for several times by using deionized water, then carrying out ultrasonic cleaning by using isopropanol, and carrying out nitrogen blow-drying; processing for 5 minutes under oxygen plasma to clean the ITO surface and improve the work function of an ITO electrode;

2) Preparation of HIL and HTL: spin coating PEDOT: PSS (Clevios) on a glass substrate treated with oxygen plasma ^TM PEDOT: PSS Al 4083) to obtain a film of 80nm, annealing the film in air at 150 ℃ for 20 minutes after the spin coating is finished, and then spin coating the PEDOT: PSS layer to obtain a Poly-TFB film of 20nm (CAS: 223569-31-1, available from Lumtec. Corp;5mg/mL toluene solution), followed by treatment on a hotplate at 180 ℃ for 60 minutes;

3) Preparing a luminescent layer: the above printing ink was spin coated in a nitrogen glove box to give an 80nm film, which was then annealed at 120 ℃ for 10 minutes.

4) Preparing a cathode: and putting the spin-coated device into a vacuum evaporation cavity, and sequentially evaporating 2nm barium and 100nm aluminum to complete the light-emitting device.

5) All devices were encapsulated in a nitrogen glove box with uv cured resin plus glass cover plate.

The current-voltage (J-V) characteristics of each OLED device were characterized by a characterization device, while recording important parameters such as efficiency, lifetime, and external quantum efficiency. In Table II, all the device data are relative values of comparative example 1.

Watch 2

The luminous efficiency and the service life of the examples 1 to 4 are obviously improved compared with those of the comparative example 1 and the comparative example 2. Therefore, the OLED device prepared by the printing ink provided by the invention has the advantages that the luminous efficiency and the service life are greatly improved, and the external quantum efficiency is also obviously improved. Compared with the H2-1+ compound Host combination in the comparative example 3, which can form the exiplex but does not contain the material with TADF characteristic, the luminous efficiency and the service life of the examples 1 and 2 are obviously improved, and the excellent effect of the invention is further illustrated.

Claims (15)

1. A printing ink comprising at least two organic functional materials H1 and H2, and at least one organic solvent, characterized in that: 1) The printing ink has viscosity in the range of 1cPs to 100cPs at 25 ℃ and/or surface tension in the range of 19dyne/cm to 50dyne/cm at 25 ℃; 2) H1 and H2 form a type II semiconductor heterojunction structure, and min ((LUMO (H1) -HOMO (H2), LUMO (H2) -HOMO (H1)) ≦ min (T1 (H1), T1 (H2)) +0.1eV, wherein LUMO (H1), HOMO (H1), and T1 (H1) are, in order, the lowest unoccupied orbital, the highest occupied orbital, the triplet level of H1, LUMO (H2), HOMO (H2), and T1 (H2) are, in order, the lowest unoccupied orbital, the highest occupied orbital, the triplet level of H2; 3) At least one of H1 and H2 has (S1-T1) less than or equal to 0.3eV, and S1 is a singlet state energy level;

wherein the H2 has a structure represented by general formula (VI):

wherein Ar is a substituted or unsubstituted aromatic or substituted or unsubstituted heteroaromatic structural unit, W is independently selected from the same or different electron-donating groups when appearing for multiple times, A is independently selected from the same or different electron-withdrawing groups when appearing for multiple times, and n and p are integers from 1 to 6;

w in formula (VI) is selected from the group consisting of structural units comprising:

2. printing ink according to claim 1, characterised in that the difference between the molecular weights of H1 and H2 is equal to or greater than 50g/mol or the difference between the sublimation temperatures of H1 and H2 is equal to or greater than 30K.

3. Printing ink according to claim 1, characterised in that at least one of the molecular weights of H1 and H2 is greater than or equal to 800g/mol.

4. A printing ink according to claim 1, wherein the molar ratio of H1 to H2 in the printing ink is in the range of 1.

5. Printing ink according to claim 1, characterised in that the energy gap of H1 is greater than H2.

6. Printing ink according to claim 1, characterised in that H1 has hole transport properties or electron transport properties.

7. The printing ink of claim 1, wherein H1 has a structure of formula (I),

wherein,

Z ⁴ ，Z ⁵ ，Z ⁶ are each independently selected from N or CR ² ；

Ar ¹ ～Ar ³ Identical or different are aromatic or heteroaromatic ring systems having from 5 to 40 ring atoms, or aryloxy or heteroaryloxy groups having from 5 to 40 ring atoms, or nonaromatic groups having from 5 to 40 ring atoms, or combinations of these systems, where one or more radicals may further be substituted by R ² Substituted, or R ² May further form a ring system with the substituted group;

R ² identical or different on each occurrence is H, D, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 20C atoms, or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 20C atoms or a silyl group, or a substituted keto group having 1 to 20C atoms, or an alkoxycarbonyl group having 2 to 20C atomsA group, or an aryloxycarbonyl group having 7 to 20C atoms, a cyano group), a carbamoyl group, a haloformyl group, a formyl group, an isocyano group, an isocyanate group, a thiocyanate group or an isothiocyanate group, a hydroxyl group, a nitro group, CF ₃ A group, cl, br, F, a crosslinkable group or a substituted or unsubstituted aromatic or heteroaromatic ring system having 5 to 40 ring atoms, or an aryloxy or heteroaryloxy group having 5 to 40 ring atoms, or a combination of these systems;

m, m1, m2 are independently 1 or 2 or 3.

8. Printing ink according to claim 7, characterised in that Ar in formula (I) ¹ -Ar ³ In multiple occurrences, the same or different are selected from one or a combination of the following structural groups:

wherein n1 is 1 or 2 or 3 or 4.

9. A printing ink according to claim 1, wherein H1 is a compound of one of the following formulae (II) to (V):

wherein,

L ¹ represents an aromatic group or an heteroaromatic group having 5 to 60 ring atoms;

L ² represents a single bond, an aromatic group or an aromatic hetero group having 5 to 30 ring atoms;

Ar ⁴ -Ar ⁹ each independently represents an aromatic or heteroaromatic ring system having 5 to 40 ring atoms;

x represents a single bond, N (R) ³ )、C(R ³ ) ₂ 、Si(R ³ ) ₂ 、O、C＝N(R ³ )、C＝C(R ³ ) ₂ 、P(R ³ )、P(＝O)R ³ 、S、

S = O or SO ₂ ；

X ₂ -X ₉ Each independently represents a single bond, N (R) ³ )、C(R ³ ) ₂ 、Si(R ³ ) ₂ 、O、C＝N(R ³ )、C＝C(R ³ ) ₂ 、P(R ³ )、P(＝O)R ³ S, S = O or SO ₂ But X ₂ And X ₃ Not simultaneously being a single bond, X ₄ And X ₅ Not simultaneously being a single bond, X ₆ And X ₇ Not simultaneously being a single bond, X ₈ And X ₉ Is not a single bond at the same time;

R ³ 、R ⁴ 、R ⁵ each independently represents H, D, F, CN, alkenyl, alkynyl, nitrile group, amino group, nitro group, acyl group, alkoxy group, carbonyl group, sulfone group, straight chain or branched chain alkyl group having 1 to 30 carbon atoms, cycloalkyl group having 3 to 30 carbon atoms, aromatic hydrocarbon group having 5 to 60 ring atoms or aromatic heterocyclic group, wherein R is ⁴ 、R ⁵ Can be on any carbon atom of the fused ring and is substituted by R ⁴ 、R ⁵ The number of substituted carbon atoms may be any plural;

n2 represents an integer of 1 to 4.

10. Printing ink according to claim 1, characterised in that a in formula (VI) is selected from F, cyano or one of the following groups:

wherein o is 1,2 or 3; x ¹ -X ⁸ Is selected from CR ⁶ Or N, and at least one is N; m ¹ 、M ² 、M ³ Each independently represents N (R) ⁶ )、C(R ⁶ 6R ⁷ )、Si(R ⁶ R ⁷ )、O、C＝N(R ⁶ )、C＝C(R ⁶ R ⁷ )、P(R)、P(＝O)R ⁶ 、S、S＝O、SO ₂ Or none; r ⁶ 、R ⁷ Each independently represents H, D, F, CN, alkenyl, alkynyl, nitrile group, amino group, nitro group, acyl group, alkoxy group, carbonyl group, sulfone group, straight-chain or branched-chain alkyl group having 1 to 30 carbon atoms, cycloalkyl group having 3 to 30 carbon atoms, aromatic hydrocarbon group having 5 to 60 ring atoms or aromatic heterocyclic group having 5 to 60 ring atoms.

11. The printing ink according to claim 1, wherein the printing ink further comprises a third organic functional material, and the third organic functional material is selected from one or more of hole injection or transport material, hole blocking material, electron injection or transport material, electron blocking material, organic matrix material, singlet emitter, triplet emitter, thermally-excited delayed fluorescence material, and organic dye.

12. A printing ink according to claim 1, characterised in that said organic solvent is selected from one or a mixture of two or more of aromatic or heteroaromatic, ester, aromatic ketone or ether, aliphatic ketone or ether, alicyclic or olefinic compounds, or borate or phosphate compounds.

13. Use of the printing ink according to any one of claims 1 to 12 for the preparation of an organic electronic device.

14. Use according to claim 13, wherein the organic electronic device is selected from an organic light emitting diode, an organic photovoltaic cell, an organic field effect transistor, an organic laser, an organic spintronic device or an organic sensor.

15. Use according to claim 14, wherein the organic electronic device is an organic light emitting diode comprising at least one light emitting layer prepared from a printing ink according to any one of claims 1 to 12.

Images