WO2021191255A1

WO2021191255A1 - Organic electronic device, organic semiconducting material, a trioxatriborinane compound and the use thereof

Info

Publication number: WO2021191255A1
Application number: PCT/EP2021/057534
Authority: WO
Inventors: Max Peter Nüllen; Markus Hummert; Horst Hartmann; Dieter E. Kaufmann; Serge-Mithérand TENGHO TOGUEM
Original assignee: Novaled Gmbh; Tu Clausthal
Priority date: 2020-03-26
Filing date: 2021-03-24
Publication date: 2021-09-30
Also published as: DE102020108402A1; CN115485873A; DE102020108402B4

Abstract

The present invention relates to an organic electronic device, an organic semiconducting material and a 1,3,5-trioxatriborinane-containg compound.

Description

Organic electronic device, organic semiconducting material, a trioxatriborinane compound and the use thereof

The present invention relates to an organic electronic device, an organic semiconducting material, a trioxatriborinane compound and the use thereof.

BACKGROUND ART

Organic light-emitting diodes (OLEDs), which are self-emitting devices, have a wide viewing angle, excellent contrast, quick response, high brightness, excellent driving voltage characteristics, and color reproduction. A typical OLED includes an anode, a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and a cathode, which are sequentially stacked on a substrate. In this regard, the HTL, the EML, and the ETL are thin films formed from organic and / or organometallic compounds.

When a voltage is applied to the anode and the cathode, holes injected from the anode electrode move to the EML, via the HTL, and electrons injected from the cathode electrode move to the EML, via the ETL. The holes and electrons recombine in the EML to generate excitons. When the excitons drop from an excited state to a ground state, light is emitted. The injection and flow of holes and electrons should be balanced, so that an OLED having the above-described structure has excellent efficiency.

WO 2016/097017 Ai discloses organic compounds which are, due to energy levels of their lowest unoccupied molecular orbitals (LUMO) which are comparable with HOMO (highest occupied molecular orbital) energy levels of compounds typically used as majority components (matrices) in organic hole transporting semiconducting materials, able to act as so called charge transfer or redox p-dopants.

WO 2017/029370 Ai and WO 2017/029366 Ai disclose the use of sulfonyl imide metal complexes comprising at least one sulfonyl imide anionic ligand as hole injection materials.

There is, however, still an unmet demand for p-dopants and hole injection materials which fulfill various and frequently contradictory practical requirements. For example, such requirements might be providing a hole injection material enabling good hole injection without increasing concentration of free holes in the doped material or on the doped phase interface substantially. Such materials could be very suitable for limitation of electrical pixel crosstalk in displays comprising an electrically doped hole transport layer which is adjacent to the structured, pixel-defining anode.

Moreover, there is still a need to improve the performance of organic electronic devices and/or organic semiconducting materials, in particular of optoelectronic devices comprising an organic charge transport material, such as organic light emitting diodes (OLEDs) or organic photovoltaic (OPV) devices and of complex devices comprising the said optoelectronic devices, such as OLED displays.

It is, therefore, the object of the present invention to provide an organic electronic device, an organic semiconducting material and a compound for use therein overcoming drawbacks of the prior art, in particular to provide p-dopants and/or hole injection materials for improving the performance of a respective device, in particular for improving initial voltage, efficiency or voltage stability thereof.

SUMMARY OF THE INVENTION

The above object is achieved by an organic electronic device comprising a first electrode, a second electrode, and an organic semiconducting layer, wherein the organic semiconducting layer is arranged between the first electrode and the second electrode; the organic semiconducting layer is a hole injection layer, a hole transport layer, or a hole generating layer; and the organic semiconducting layer comprises a 1,3,5-trioxatriborinane-containg compound.

It was surprisingly found by the inventors that 1,3,5-trioxatriborinane-containg compounds may be used in organic electronic devices (and in organic semiconducting materials) and that this use, in particular if the 1,3,5-trioxatriborinane-containg compounds are used as p-dopants or as hole injection materials, may be helpful to improve key properties of such devices and materials and, therefore, the performance thereof.

In terms of the present invention, a 1,3,5-trioxatriborinane-containg compound is a compound comprising the following 1,3,5-trioxatriborinane moiety

In the 1,3,5-trioxatriborinane-containg compound, three further groups are comprised which are attached to the trivalent boron atoms, respectively. For example, three organic groups, such as alkyl, aryl, heteroalkyl, heteroaryl alkenyl, alfynyl etc, which are independently selected, may be attached to each of the three boron atoms of the 1,3,5-trioxatriborinane moiety, respectively.

The 1,3,5-trioxatriborinane-containg compound may be represented by the following formula (I)

wherein R¹, R² and R³ are independently selected from the group consisting of substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic electronic devices.

R¹, R² and R³ may be independently selected from the group consisting of substituted aryl and substituted heteroaryl. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic electronic devices.

In case that one or more of R¹ to R³ is substituted, the one or more substituents, if present in one or more of the groups, may be independently selected from the group consisting of deuterium, halogen, CN, C -C₂₀ linear alkyl, C₃-C₂₀ branched alkyl, C₃-C₂₀ cyclic alkyl, C -C₂₀ linear alkoxy, C₃-C₂₀ branched alkoxy, C - C₁₂ linear fluorinated alkyl, C -C₁₂ linear fluorinated alkoxy, C₃-C₁₂ branched fluorinated cyclic alkyl, C₃-C₁₂ fluorinated cyclic alkyl, C₃-C₁₂ fluorinated cyclic alkoxy, OCN, C₆-C₂₀ aryl, C₂-C₂₀ heteroaryl, OR, SR, (C=0)R, (0=0)NI¾, SiR₃, (S=0)R, SO2R, (P=0)R₂; wherein each R independently selected from C -C₂₀ linear alkyl, C -C₂₀ alkoxy, C -C₂₀ thioalkyl, C₃-C₂₀ branched alkyl, C₃-C₂₀ cyclic alkyl, C₃-C₂₀ branched alkoxy, C₃-C₂₀ cyclic alkoxy, C₃-C₂₀ branched thioalkyl, C₃-C₂₀ cyclic thioalkyl, C₆-C₂₀ aryl and C₂-C₂₀ heteroaryl. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic electronic devices.

The substituent(s), if present in one or more of R¹, R² and R³, may be independently selected from the group consisting of halogen and CN. In this regard, halogen may be F, Cl, Br and I. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic electronic devices.

In one embodiment, at least 50 %, preferably at least 66 %, more preferably at least 75 %, more preferably at least 80 %, even more preferably at least 90 %, most preferably too % of the overall number of hydrogen atoms comprised in at least one of R¹, R², R³ may be replaced by substituents independently selected from F, Cl, Br, I and CN. The percentage of substitution in this regard refers to a situation in which, at first, an unsubstituted group R¹, R², R³ is (hypothetically) provided and then a specific percentage of the hydrogen atoms contained in the respective unsubstituted group is replaced by substituents. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic electronic devices.

In another embodiment, at least 50 %, preferably at least 66 %, more preferably at least 75 %, more preferably at least 80 %, even more preferably at least 90 %, most preferably too % of the overall number of hydrogen atoms comprised in at least one of R¹, R², R³ may be replaced by substituents independently selected from F and CN. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic electronic devices.

In various embodiments, at least 50 %, preferably at least 66 %, more preferably at least 75 %, more preferably at least 80 %, even more preferably at least 90 %, most preferably too % of the overall number of hydrogen atoms comprised in all of R¹, R², and R³ together may be replaced by substituents independently selected from the group consisting of F, Cl, Br, I and CN. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic electronic devices.

In various embodiments, at least 50 %, preferably 66 %, more preferably at least 75 %, more preferably at least 80 %, even more preferably at least 90 %, most preferably too % of the overall number of hydrogen atoms comprised in all of R¹, R², and R³ together may be replaced by substituents independently selected from the group consisting of F and CN. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic electronic devices.

The 1,3,5-trioxatriborinane-containg compound may be

or a mixture thereof. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic electronic devices.

It may be provided that the organic electronic device comprises a light emitting layer; the light emitting layer is arranged between the first electrode and the second electrode; the organic semiconducting layer is arranged between the first electrode and the light emitting layer; and the organic semiconducting layer is a hole injection layer or hole transport layer.

As disclosed herein, whenever reference to a specific layer of the organic electronic device is made, for example to a light emitting layer, a hole injection layer, an organic semiconducting layer etc., it may be provided that the organic electronic device comprises more than one of the respective layer. For example, the expression “organic electronic device comprising a light emitting layer” encompasses also organic electronic devices comprising two light emitting layers, organic electronic devices comprising three light emitting layers etc.

It may be provided that the organic electronic device comprises a first light emitting layer and a second light emitting layer; the first light emitting layer and the second light emitting layer are arranged between the first electrode and the second electrode; the organic semiconducting layer is arranged between the first light emitting layer and the second light emitting layer; and the organic semiconducting layer is a hole generating layer.

The organic electronic device may be an organic electroluminescent device, an organic transistor, an organic diode, or an organic photovoltaic device.

The organic electroluminescent device maybe an organic light-emitting diode.

The objective is further achieved by a display device comprising the inventive organic electronic device.

The display device may comprise at least two inventive organic electronic devices.

The objective is further achieved by an organic semiconducting material wherein

- the organic semiconducting material comprises a matrix compound and an electrical dopant; and

- the electrical dopant is a 1,3,5-trioxatriborinane-containg compound. The matrix compound comprised in the organic semiconducting material may comprise or consist of a hole transport matrix compound.

The organic semiconducting material may be a hole transporting material and the matrix compound may be a hole transport matrix compound.

The hole transport matrix compound may be an organic hole transport matrix compound. -The organic hole transport matrix compound may comprise a conjugated system of at least 6 delocalized electrons, alternatively at least to delocalized electrons, alternatively at least 14 delocalized electrons.

The organic hole transport matrix compound may be selected from organic compounds comprising at least one amine nitrogen substituted with groups independently selected from C₆ to C₄₂ aryl and C_3to C₄₂ heteroaryl.

wherein R¹, R² and R³ are independently selected from the group consisting of substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic semiconducting materials.

R¹, R² and R³ may be independently selected from the group consisting of substituted aryl and substituted heteroaryl. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic semiconducting materials.

In case that one or more of R¹ to R³ is substituted, the one or more substituents, if present in one or more of the groups, may be independently selected from the group consisting of deuterium, halogen, CN, C -C₂₀ linear alkyl, C₃-C₂₀ branched alkyl, C₃-C₂₀ cyclic alkyl, C -C₂₀ linear alkoxy, C₃-C₂₀ branched alkoxy, C - C₁₂ linear fluorinated alkyl, C -C ₂ linear fluorinated alkoxy, C₃-C₁₂ branched fluorinated cyclic alkyl, C₃-C₁₂ fluorinated cyclic alkyl, C₃-C ₂ fluorinated cyclic alkoxy, OCN, C₆-C₂₀ aryl, C₂-C₂₀ heteroaryl, OR, SR, (C=0)R, (C=0)NR₂, SiR₃, (S=0)R, SO2R, (P=0)R₂; wherein each R independently selected from C -C₂₀ linear alkyl, C -C₂₀ alkoxy, C -C₂₀ thioalkyl, C₃-C₂₀ branched alkyl, C₃-C₂₀ cyclic alkyl, C₃-C₂₀ branched alkoxy, C₃-C₂₀ cyclic alkoxy, C₃-C₂₀ branched thioalkyl, C₃-C₂₀ cyclic thioalkyl, C₆-C₂₀ aryl and C₂-C₂₀ heteroaryl. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic semiconducting materials.

The substituent(s), if present in one or more of R¹, R² and R³, may be independently selected from the group consisting of halogen and CN. In this regard, halogen may be F, Cl, Br and I. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic semiconducting materials.

In one embodiment, at least 50 %, preferably at least 66 %, more preferably at least 75 %, more preferably at least 80 %, even more preferably at least 90 %, most preferably too % of the overall number of hydrogen atoms comprised in at least one of R¹, R², R³ may be replaced by substituents independently selected from F, Cl, Br, I and CN. The percentage of substitution in this regard refers to a situation in which, at first, an unsubstituted group R¹, R², R³ is (hypothetically) provided and then a specific percentage of the hydrogen atoms contained in the respective unsubstituted group is replaced by substituents. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic semiconducting materials.

In another embodiment, at least 50 %, preferably at least 66 %, more preferably at least 75 %, more preferably at least 80 %, even more preferably at least 90 %, most preferably too % of the overall number of hydrogen atoms comprised in at least one of R¹, R², R³ may be replaced by substituents independently selected from F and CN. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic semiconducting materials.

In various embodiments, at least 50 %, preferably at least 66 %, more preferably at least 75 %, more preferably at least 80 %, even more preferably at least 90 %, most preferably too % of the overall number of hydrogen atoms comprised in all of R¹, R², and R³ together may be replaced by substituents independently selected from the group consisting of F, Cl, Br, I and CN. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic semiconducting materials. In various embodiments, at least 50 %, preferably at least 66 %, more preferably at least 75 %, more preferably at least 80 %, even more preferably at least 90 %, most preferably 100 % of the overall number of hydrogen atoms comprised in all of R¹, R², and R3 together may be replaced by substituents independently selected from the group consisting of F and CN. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic semiconducting materials.

The 1,3,5-trioxatriborinane-containg compound may be

or a mixture thereof. In this way, it is possible to improve the electronic properties of the compound to improve the usability thereof in organic semiconducting materials.

The object is further achieved by a compound represented by the following formula (II)

wherein - R⁴, R5 and R⁶ are independently selected from the group consisting of fully substituted aryl and fully substituted heteroaryl;

- it is provided for each of R⁴, R⁵ and R⁶ that at least one of the substituents is CN and/or at least one of the substituents is a hydrocarbyl comprising at least one sp³- hybridized carbon atom and is fully substituted with halogen atoms; and

- the remaining substituents of R⁴, R⁵ and R⁶ are independently selected from the group consisting of F, Cl, Br, I and CN, alternatively are independently selected from the group consisting of F, Cl, Br, and I, alternatively are all F.

In this regard, “fully substituted” means that in a situation in which, at first, an unsubstituted group R⁴, R⁵, R⁶ is (hypothetically) provided and then all of the hydrogen atoms contained in the respective unsubstituted group are replaced by substituents.

The object is further achieved by a compound represented by the following formula (HI)

Ar-B(0H)₂ (III), wherein

- Ar is a fully substituted aryl or a fully substituted heteroaryl;

- at least one of the substituents of Ar is a hydrocarbyl fully substituted with halogen atoms and comprising at least one sp³-hybridized carbon atom; and

- the remaining substituents of Ar are independently selected from the group consisting of F, Cl, Br, I and CN, alternatively are independently selected from the group consisting of F, Cl, Br, and I, alternatively are all F.

The object is further achieved by the use of a 1,3,5-trioxatriborinane-containg compound as a p-dopant in an electronic device. Preferred embodiments with respect to the 1,3,5-trioxatriborinane-containg compound which may be used in this regard are disclosed above with respect to the inventive organic electronic device, the inventive organic semiconducting material and the inventive compound.

The object is further achieved by the use of a 1,3,5-trioxatriborinane-containg compound as a hole injecting material in an electronic device. Preferred embodiments with respect to the 1,3,5-trioxatriborinane-containg compound which may be used in this regard are disclosed above with respect to the inventive organic electronic device, the inventive organic semiconducting material and the inventive compound.

The object is further achieved by the use of a compound represented by the following formula (III)

Ar-B(0H)₂ (III), as a precursor compound for preparing a 1,3,5-trioxatriborinane-containg compound. Further layers

In accordance with the invention, the organic electronic device may comprise, besides the layers already mentioned above, further layers. Exemplary embodiments of respective layers are described in the following:

Substrate

The substrate may be any substrate that is commonly used in manufacturing of organic electronic devices, such as organic light-emitting diodes. If light is to be emitted through the substrate, the substrate shall be a transparent or semitransparent material, for example a glass substrate or a transparent plastic substrate. If light is to be emitted through the top surface, the substrate may be both a transparent as well as a non transparent material, for example a glass substrate, a plastic substrate, a metal substrate or a silicon substrate.

Anode electrode

Either the first electrode or the second electrode may be an anode electrode. The anode electrode may be formed by depositing or sputtering a material that is used to form the anode electrode. The material used to form the anode electrode may be a high work- function material, so as to facilitate hole injection. The anode material may also be selected from a low work function material (i.e. aluminum). The anode electrode may be a transparent or reflective electrode. Transparent conductive oxides, such as indium tin oxide (ITO), indium zinc oxide (IZO), tin-dioxide (Sn02), aluminum zinc oxide (AlZO) and zinc oxide (ZnO), may be used to form the anode electrode. The anode electrode may also be formed using metals, typically silver (Ag), gold (Au), or metal alloys. Another alternative material for the anode electrode maybe graphene. Hole injection layer

In accordance with the invention, the hole injection layer may comprise the 1,3,5- trioxatriborinane-containg compound as described above in very detail. The hole injection layer (HIL) may be formed on the anode electrode by vacuum deposition, spin coating, printing, casting, slot-die coating, Langmuir-Blodgett (LB) deposition, or the like. When the HIL is formed using vacuum deposition, the deposition conditions may vary according to the compound that is used to form the HIL, and the desired structure and thermal properties of the HIL. In general, however, conditions for vacuum deposition may include a deposition temperature of ioo° C to 500° C, a pressure of icr⁸ to icr³ Torr (1 Torr equals 133.322 Pa), and a deposition rate of 0.1 to 10 nm/sec.

When the HIL is formed using spin coating or printing, coating conditions may vary according to the compound that is used to form the HIL, and the desired structure and thermal properties of the HIL. For example, the coating conditions may include a coating speed of about 2000 rpm to about 5000 rpm, and a thermal treatment temperature of about 8o° C to about 200° C. Thermal treatment removes a solvent after the coating is performed.

The HIL may be formed - in particular if the organic electronic device comprises another layer comprising the 1,3,5-trioxatriborinane-containg compound - of any compound that is commonly used to form a HIL. Examples of compounds that may be used to form the HIL include a phthalocyanine compound, such as copper phthalocyanine (CuPc), 4,4',4"-tris (3-methylphenylphenylamino) triphenylamine (m- MTDATA), TDATA, 2T-NATA, polyaniline/dodecylbenzenesulfonic acid (Pani/DBSA), poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT /PSS), polyaniline/camphor sulfonic acid (Pani/CSA), and polyaniline)/poly(4- styrenesulfonate (PANI/PSS).

In such a case, the HIL maybe a pure layer of p-dopant or maybe selected from a hole transporting matrix compound doped with a p-dopant. Typical examples of known redox doped hole transport materials are: copper phthalocyanine (CuPc), which HOMO level is approximately -5.2 eV, doped with tetrafluoro-tetracyanoquinonedimethane (F4TCNQ), which LUMO level is about -5.2 eV; zinc phthalocyanine (ZnPc) (HOMO = - 5.2 eV) doped with F4TCNQ; a-NPD (N,N'-bis(naphthalen-i-yl)-N,N'-bis(phenyl)- benzidine) doped with F4TCNQ. a-NPD doped with 2,2’-(perfluoronaphthalen-2,6- diylidene) dimalononitrile (PDi). a-NPD doped with 2,2’,2"-(cyclopropane-i,2,3- triylidene)tris(2-(p-cyanotetrafluorophenyl)acetonitrile) (PD2). Dopant concentrations can be selected from 1 to 20 wt.-%, more preferably from 3 wt.-% to 10 wt.-%.

The thickness of the HIL may be in the range from about 1 nm to about 100 nm, and for example, from about 1 nm to about 25 nm. When the thickness of the HIL is within this range, the HIL may have excellent hole injecting characteristics, without a substantial penalty in driving voltage.

Hole transport layer

In accordance with the invention, the hole transport layer may comprise the 1,3,5- trioxatriborinane-containg compound as described above in detail.

The hole transport layer (HTL) may be formed on the HIL by vacuum deposition, spin coating, slot-die coating, printing, casting, Langmuir-Blodgett (LB) deposition, or the like. When the HTL is formed by vacuum deposition or spin coating, the conditions for deposition and coating may be similar to those for the formation of the HIL. However, the conditions for the vacuum or solution deposition may vary, according to the compound that is used to form the HTL.

In case that the HTL does not comprise the 1,3,5-trioxatriborinane-containg compound in accordance with the invention, but the 1,3,5-trioxatriborinane-containg compound is comprised in another layer, the HTL may be formed by any compound that is commonly used to form a HTL. Compounds that can be suitably used are disclosed for example in Yasuhiko Shirota and Hiroshi Kageyama, Chem. Rev. 2007, 107, 953-1010 and incorporated by reference. Examples of the compound that may be used to form the HTL are: carbazole derivatives, such as N-phenylcarbazole or polyvinyl carbazole; benzidine derivatives, such as N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[i,i-biphenyl]- 4,4’-diamine (TPD), or N,N'-di(naphthalen-i-yl)-N,N'-diphenyl benzidine (alpha- NPD); and triphenylamine-based compound, such as 4,4’,4"-tris(N- carbazolyl)triphenylamine (TCTA). Among these compounds, TCTA can transport holes and inhibit excitons from being diffused into the EML.

The thickness of the HTL may be in the range of about 5 nm to about 250 nm, preferably, about 10 nm to about 200 nm, further about 20 nm to about 190 nm, further about 40 nm to about 180 nm, further about 60 nm to about 170 nm, further about 80 nm to about 160 nm, further about 100 nm to about 160 nm, further about 120 nm to about 140 nm. A preferred thickness of the HTL may be 170 nm to 200 nm. When the thickness of the HTL is within this range, the HTL may have excellent hole transporting characteristics, without a substantial penalty in driving voltage.

Electron blocking layer

The function of the electron blocking layer (EBL) is to prevent electrons from being transferred from the emission layer to the hole transport layer and thereby confine electrons to the emission layer. Thereby, efficiency, operating voltage and/or lifetime are improved. Typically, the electron blocking layer comprises a triarylamine compound. The triarylamine compound may have a LUMO level closer to vacuum level than the LUMO level of the hole transport layer. The electron blocking layer may have a HOMO level that is further away from vacuum level compared to the HOMO level of the hole transport layer. The thickness of the electron blocking layer may be selected between 2 and 20 nm.

The electron blocking layer may comprise a compound of formula Z below (Z).

In Formula Z, CYi and CY2 are the same as or different from each other, and each independently represent a benzene cycle or a naphthalene cycle, Ari to Ar3 are the same as or different from each other, and each independently selected from the group consisting of hydrogen; a substituted or unsubstituted aryl group having 6 to 30 carbon atoms; and a substituted or unsubstituted heteroaryl group having 5 to 30 carbon atoms, AT4 is selected from the group consisting of a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, a substituted or unsubstituted triphenylene group, and a substituted or unsubstituted heteroaryl group having 5 to 30 carbon atoms, L is a substituted or unsubstituted arylene group having 6 to 30 carbon atoms.

If the electron blocking layer has a high triplet level, it may also be described as triplet control layer. The function of the triplet control layer is to reduce quenching of triplets if a phosphorescent green or blue emission layer is used. Thereby, higher efficiency of light emission from a phosphorescent emission layer can be achieved. The triplet control layer is selected from triarylamine compounds with a triplet level above the triplet level of the phosphorescent emitter in the adjacent emission layer. Suitable compounds for the triplet control layer, in particular the triarylamine compounds, are described in EP 2722908 Ai.

Emission layer (EML)

The EML may be formed on the HTL by vacuum deposition, spin coating, slot-die coat ing, printing, casting, LB deposition, or the like. When the EML is formed using vacuum deposition or spin coating, the conditions for deposition and coating may be similar to those for the formation of the HIL. However, the conditions for deposition and coating may vary, according to the compound that is used to form the EML.

The emission layer (EML) may be formed of a combination of a host and an emitter dopant. Example of the host are Alq3, 4,4'-N,N'-dicarbazole-biphenyl (CBP), poly(n- vinylcarbazole) (PVK), 9,io-di(naphthalene-2-yl)anthracene (ADN), 4A'A”~ tris(carbazol-9-yl)-triphenylamine(TCTA), i,3,5-tris(N-phenylbenzimidazole-2- yl)benzene (TPBI), 3-tert-butyl-9,io-di-2-naphthylanthracenee (TBADN), distyrylarylene (DSA), bis(2-(2-hydroxyphenyl)benzo-thiazolate)zinc (Zn(BTZ)₂), G3 below, Compound 1 below, and Compound 2 below.

ADN

Compound l

Compound 2

The emitter dopant may be a phosphorescent or fluorescent emitter. Phosphorescent emitters and emitters which emit light via a thermally activated delayed fluorescence (TADF) mechanism may be preferred due to their higher efficiency. The emitter may be a small molecule or a polymer.

Examples of red emitter dopants are PtOEP, Ir(piq)₃, and Btp₂lr(acac), but are not limited thereto. These compounds are phosphorescent emitters, however, fluorescent red emitter dopants could also be used.

Examples of phosphorescent green emitter dopants are Ir(ppy)₃ (ppy = phenylpyridine), Ir(ppy)₂(acac), Ir(mpyp)₃ are shown below. Compound 3 is an example of a fluorescent green emitter and the structure is shown below.

Compound 3

Examples of phosphorescent blue emitter dopants are F2lrpic, (F2ppy)2lr(tmd) and Ir(dfppz)3, ter-fluorene, the structures are shown below. 4 '-bis(4-diphenyl amiostyryl)biphenyl (DPAVBi), 2,5,8,11-tetra-tert-butyl perylene (TBPe), and Compound 4 below are examples of fluorescent blue emitter dopants.

Compound 4

The amount of the emitter dopant may be in the range from about 0.01 to about 50 parts by weight, based on 100 parts by weight of the host. Alternatively, the emission layer may consist of a light-emitting polymer. The EML may have a thickness of about 10 nm to about 100 nm, for example, from about 20 nm to about 60 nm. When the thickness of the EML is within this range, the EML may have excellent light emission, without a substantial penalty in driving voltage.

Hole blocking layer (HBL)

A hole blocking layer (HBL) may be formed on the EML, by using vacuum deposition, spin coating, slot-die coating, printing, casting, LB deposition, or the like, in order to prevent the diffusion of holes into the ETL. When the EML comprises a phosphorescent dopant, the HBL may have also a triplet exciton blocking function.

When the HBL is formed using vacuum deposition or spin coating, the conditions for deposition and coating may be similar to those for the formation of the HIL. However, the conditions for deposition and coating may vary, according to the compound that is used to form the HBL. Any compound that is commonly used to form a HBL may be used. Examples of compounds for forming the HBL include oxadiazole derivatives, triazole derivatives, and phenanthroline derivatives.

The HBL may have a thickness in the range from about 5 nm to about too nm, for example, from about 10 nm to about 30 nm. When the thickness of the HBL is within this range, the HBL may have excellent hole-blocking properties, without a substantial penalty in driving voltage.

Electron transport layer (ETL)

The OLED according to the present invention may contain an electron transport layer (ETL). According to various embodiments, the OLED may comprise an electron transport layer or an electron transport layer stack comprising at least a first electron transport sub-layer and at least a second electron transport sub-layer.

By suitably adjusting energy levels of particular layers of the ETL, the injection and transport of the electrons may be controlled, and the holes may be efficiently blocked. Thus, the OLED may have long lifetime.

The electron transport layer of the organic electronic device may comprise an organic electron transport matrix (ETM) material. Further, the electron transport layer may comprise one or more n-dopants. Suitable compounds for the ETM are not particularly limited. In one embodiment, the electron transport matrix compounds consist of covalently bound atoms. Preferably, the electron transport matrix compound comprises a conjugated system of at least 6, more preferably of at least to delocalized electrons. In one embodiment, the conjugated system of delocalized electrons may be comprised in aromatic or heteroaromatic structural moieties, as disclosed e.g. in documents EP 1970 371 At or WO 2013/079217 Ai.

In one embodiment, the electron transport layer may be electrically doped with an electrical n-dopant. In another embodiment, the electron transport layer may comprise the second electron transport sub-layer which is arranged closer to the cathode than the first electron transport sub-layer and only the second electron transport sub-layer may comprise the electrical n-dopant.

The electrical n-dopant may be selected from electropositive elemental metals, and/or from metal salts and metal complexes of electropositive metals, particularly from elemental forms, salts and/or complexes of metal selected from alkali metals, alkaline earth metals, and rare earth metals.

Electron injection layer (EIL)

The optional EIL, which may facilitates injection of electrons from the cathode, may be formed on the ETL, preferably directly on the electron transport layer. Examples of materials for forming the EIL include lithium 8-hydroxyquinolinolate (LiQ), LiF, NaCl, CsF, Li₂0, BaO, Ca, Ba, Yb, Mg which are known in the art. Deposition and coating conditions for forming the EIL are similar to those for formation of the HIL, although the deposition and coating conditions may vary, according to the material that is used to form the EIL. The thickness of the EIL may be in the range from about o.i nm to about 10 nm, for example, in the range from about 0.5 nm to about 9 nm. When the thickness of the EIL is within this range, the EIL may have satisfactory electron-injecting properties, without a substantial penalty in driving voltage.

Cathode electrode

The cathode electrode is formed on the EIL if present. The cathode electrode may be formed of a metal, an alloy, an electrically conductive compound, or a mixture thereof. The cathode electrode may have a low work function. For example, the cathode electrode may be formed of lithium (Li), magnesium (Mg), aluminum (Al), aluminum (Al)-lithium (Li), calcium (Ca), barium (Ba), ytterbium (Yb), magnesium (Mg)-indium (In), magnesium (Mg)-silver (Ag), or the like. Alternatively, the cathode electrode may be formed of a transparent conductive oxide, such as ITO or IZO.

The thickness of the cathode electrode may be in the range from about 5 nm to about 1000 nm, for example, in the range from about 10 nm to about too nm. When the thickness of the cathode electrode is in the range from about 5 nm to about 50 nm, the cathode electrode may be transparent or semitransparent even if formed from a metal or metal alloy.

It is to be understood that the cathode electrode is not part of an electron injection layer or the electron transport layer.

Charge generation layer/hole generation layer

The charge generation layer (CGL) may be composed of a double layer. In case that the charge generation layer is a p-type charge generation layer (hole generation layer), it may comprise the 1,3,5-trioxatriborinane-containg compound as defined herein.

Typically, the charge generation layer is a pn junction joining a n-type charge generation layer (electron generation layer) and a hole generation layer. The n-side of the pn junction generates electrons and injects them into the layer which is adjacent in the direction to the anode. Analogously, the p-side of the p-n junction generates holes and injects them into the layer which is adjacent in the direction to the cathode.

Charge generation layers are used in tandem devices, for example, in tandem OLEDs comprising, between two electrodes, two or more emission layers. In a tandem OLED comprising two emission layers, the n-type charge generation layer provides electrons for the first light emission layer arranged near the anode, while the hole generation layer provides holes to the second light emission layer arranged between the first emission layer and the cathode.

In accordance with the invention, it may be provided that the organic electronic device comprises a hole injection layer as well as a hole generation layer. If another layer than the hole generation layer comprises the 1,3,5-trioxatriborinane-containg compound as defined herein, it is not obligatory that also the hole generation layer comprises the 1,3,5-trioxatriborinane-containg compound as defined herein. In such a case, the hole generation layer can be composed of an organic matrix material doped with p-type dopant. Suitable matrix materials for the hole generation layer may be materials conventionally used as hole injection and/or hole transport matrix materials. Also, p- type dopant used for the hole generation layer can employ conventional materials. For example, the p-type dopant can be one selected from a group consisting of tetrafluoro- 7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), derivatives of tetracyanoquinodimethane, radialene derivatives, iodine, FeCl3, FeF3, and SbCls. Also, the host can be one selected from a group consisting of N,N'-di(naphthalen-i-yl)-N,N- diphenyl-benzidine (NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-i,i-biphenyl-4,4’- diamine (TPD) and N,N',N'-tetranaphthyl-benzidine (TNB).

In an embodiment, the hole generation layer comprises the 1,3,5-trioxatriborinane- containg compound as defined herein as defined above in detail.

The n-type charge generation layer can be layer of a neat n-dopant, for example of an electropositive metal, or can consist of an organic matrix material doped with the n- dopant. In one embodiment, the n-type dopant can be alkali metal, alkali metal compound, alkaline earth metal, or alkaline earth metal compound. In another embodiment, the metal can be one selected from a group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, La, Ce, Sm, Eu, Tb, Dy, and Yb. More specifically, the n-type dopant can be one selected from a group consisting of Cs, K, Rb, Mg, Na, Ca, Sr, Eu and Yb. Suitable matrix materials for the electron generating layer may be the materials conventionally used as matrix materials for electron injection or electron transport layers. The matrix material can be for example one selected from a group consisting of triazine compounds, hydroxyquinoline derivatives like tris(8- hydroxyquinolinejaluminum, benzazole derivatives, and silole derivatives.

In one embodiment, the p-type charge generation layer may include compounds of the following Chemical Formula X.

wherein each of Ai to A6 maybe hydrogen, a halogen atom, nitrile (-CN), nitro (-NO2), sulfonyl (-SO2R), sulfoxide (-SOR), sulfonamide (-SO2NR₂), sulfonate (-SO3R), trifluoromethyl (-CF3), ester (-COOR), amide (-CONHR or - CONRR’), substituted or unsubstituted straight-chain or branched-chain C1-C12 alkoxy, substituted or unsubstituted straight-chain or branched-chain C1-C12 alkyl, substituted or unsubstituted straight-chain or branched chain C2-C12 alkenyl, a substituted or unsubstituted aromatic or non-aromatic heteroring, substituted or unsubstituted aryl, substituted or unsubstituted mono- or di-arylamine, substituted or unsubstituted aralkylamine, or the like. Herein, each of the above R and R’ may be substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted aryl, or a substituted or unsubstituted 5- to 7-membered heteroring, or the like.

An example of such p-type charge generation layer may be a layer comprising CNHAT

The hole generating layer may be arranged on top of the n-type charge generation layer. Organic light-emitting diode (OLED)

According to one aspect of the present invention, there is provided an organic light- emitting diode (OLED) comprising: a substrate; an anode electrode formed on the substrate; a hole injection layer, a hole transport layer, an emission layer, and a cathode electrode. According to another aspect of the present invention, there is provided an OLED comprising: a substrate; an anode electrode formed on the substrate; a hole injection layer, a hole transport layer, an electron blocking layer, an emission layer, a hole blocking layer and a cathode electrode.

According to another aspect of the present invention, there is provided an OLED comprising: a substrate; an anode electrode formed on the substrate; a hole injection layer, a hole transport layer, an electron blocking layer, an emission layer, a hole blocking layer, an electron transport layer, and a cathode electrode.

According to another aspect of the present invention, there is provided an OLED comprising: a substrate; an anode electrode formed on the substrate; a hole injection layer, a hole transport layer, an electron blocking layer, an emission layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode electrode.

According to various embodiments of the present invention, there may be provided OLEDs comprising layers arranged between the above mentioned layers, on the substrate or on the top electrode.

According to one aspect, the OLED can comprise a layer structure of a substrate that is adjacent arranged to an anode electrode, the anode electrode is adjacent arranged to a first hole injection layer, the first hole injection layer is adjacent arranged to a first hole transport layer, the first hole transport layer is adjacent arranged to a first electron blocking layer, the first electron blocking layer is adjacent arranged to a first emission layer, the first emission layer is adjacent arranged to a first electron transport layer, the first electron transport layer is adjacent arranged to an n-type charge generation layer, the n-type charge generation layer is adjacent arranged to a hole generating layer, the hole generating layer is adjacent arranged to a second hole transport layer, the second hole transport layer is adjacent arranged to a second electron blocking layer, the second electron blocking layer is adjacent arranged to a second emission layer, between the second emission layer and the cathode electrode an optional electron transport layer and/or an optional injection layer are arranged.

For example, the OLED according to Fig. 2 may be formed by a process, wherein on a substrate (no), an anode (120), a hole injection layer (130), a hole transport layer (140), an electron blocking layer (145), an emission layer (150), a hole blocking layer (i55) an electron transport layer (160), an electron injection layer (180) and the cathode electrode (190) are subsequently formed in that order.

Details and definitions of the invention

The organic electronic device of the present invention comprises at least one (semiconducting) layer which may comprise a hole transport matrix compound and the 1,3,5-trioxatriborinane-containg compound. The 1,3,5-trioxatriborinane-containg compound may be embedded in the matrix material, i.e. the matrix material is the predominant material in such a layer. Likewise, it may be provided that the matrix material and the 1,3,5-trioxatriborinane-containg compound are separated from each other in the semiconducting layer in a first sublayer comprising the matrix material and a second sublayer comprising the 1,3,5-trioxatriborinane-containg compound as a dopant, or, in a preferred embodiment, respectively consisting thereof. Likewise, it may be provided that the layer is consisting of the 1,3,5-trioxatriborinane-containg compound.

The 1,3,5-trioxatriborinane-containg compound may diffuse into the adjacent layers after deposition, in particular the 1,3,5-trioxatriborinane-containg compound may diffuse into the layer on which it is deposited.

The organic electronic device is described herein may be an organic electronic device based on semiconducting layers. In particular, the hole injection layer, the hole transport layer and the hole generating layer are semiconducting layers.

The term “carbon-containing group” as used herein shall be understood to encompass any organic group comprising carbon atoms, in particular organic groups, such as alkyl, aryl, heteroaryl, heteroalkyl, in particular such groups which are substituents usual in organic electronics.

The term “hydrocarbyl” as used herein shall be understood to encompass any organic monovalent group comprising only carbon and hydrogen atoms, for example organic groups such as alkyl, aryl, arylalkyl, cycloalkyl, alkenyl, alkynyl, arylalkenyl, arylalkynyl and like.

The term “alkyl” as used herein shall encompass linear as well as branched and cyclic alkyl. For example, C₃-alkyl may be selected from n-propyl and iso-propyl. Likewise, C₄-alkyl encompasses n-butyl, sec-butyl and t-butyl. Likewise, C₆-alkyl encompasses n- hexyl and cyclo-hexyl. The subscribed number n in C_n relates to the total number of carbon atoms in the respective alkyl, arylene, heteroarylene or aryl group.

The term “aryl” as used herein shall encompass phenyl (C₆-aryl), as well as monovalent groups derived fromfused aromatics, such as naphthalene, anthracene, phenanthrene, tetracene etc. Further encompassed are biphenyl and oligo- or polyphenyls, such as terphenyl etc. Further encompassed shall be any hydrocarbyl group comprising at least one aromatic ring if the single bond attaching the hydrocarbyl group to another structural moiety arises from the aromaticring comprised in the hydrocarbyl group, examples can bee.g. 2-fluorenyl, 3-fluorenyl, 9,9’-dimethyl-2-fluorenyl,etc. Arylene, respectively heteroarylene refers analogously to divalent aromatic groups derived from an arene or a heteroarene so that two hydrogen atoms originally attached to aromatic rings of the arene or heteroarene are replaced with two further structural moieties

The term “heteroaryl” as used herein refers to aryl groups in which at least one carbon atom is substituted by a heteroatom, preferably selected from N, O, S, B or Si.

The term “halogenated” refers to an organic compound in which one hydrogen atom thereof is replaced by a halogen atom. The term “perhalogenated” refers to an organic compound in which all of the hydrogen atoms thereof are replaced by halogen atoms. The meaning of the terms “fluorinated” and “perfluorinated” should be understood analogously.

The subscripted number n in C_n-heteroaryl merely refers to the number of carbon atoms excluding the number of heteroatoms. In this context, it is clear that a C₃ heteroarylene group is an aromatic compound comprising three carbon atoms, such as pyrazol, imidazole, oxazole, thiazole and the like.

In terms of the invention, the expression “between” with respect to one layer being between two other layers does not exclude the presence of further layers which may be arranged between the one layer and one of the two other layers. In terms of the invention, the expression “in direct contact” with respect to two layers being in direct contact with each other means that no further layer is arranged between those two layers. One layer deposited on the top of another layer is deemed to be in direct contact with this layer.

In the context of the present specification the term “essentially non-emissive” or “non- emissive” means that the contribution of the compound or layer to the visible emission spectrum from the device is less than 10 %, preferably less than 5 % relative to the visible emission spectrum. The visible emission spectrum is an emission spectrum with a wavelength of about ³ 380 nm to about < 780 nm.

Preferably, the organic semiconducting layer comprising at least one electrical dopant is essentially non-emissive or non-emitting.

With respect to the inventive electronic device, the compounds mentioned in the experimental part maybe most preferred.

The inventive electronic device may encompass semiconducting devices wherein charge transport consists solely in movement of electrons and/or holes.

The inventive electronic device may be an organic electroluminescent device (OLED), an organic photovoltaic device (OPV) or an organic field-effect transistor (OFET).

According to another aspect, the organic electroluminescent device according to the present invention may comprise more than one emission layer, preferably two or three emission layers. An OLED comprising more than one emission layer is also described as a tandem OLED or stacked OLED.

The organic electroluminescent device (OLED) may be a bottom- or top-emission device.

Another aspect is directed to a device comprising at least one organic electroluminescent device (OLED). A device comprising organic light-emitting diodes is for example a display or a lighting panel.

In the present invention, the following defined terms, these definitions shah be applied, unless a different definition is given in the claims or elsewhere in this specihcation.

In the context of the present specification the term “different” or “differs” in connection with the matrix material means that the matrix material differs in their structural formula.

The energy levels of the highest occupied molecular orbital, also named HOMO, and of the lowest unoccupied molecular orbital, also named LUMO, are measured in electron volt (eV).

The terms “OLED” and “organic light-emitting diode” are simultaneously used and have the same meaning. The term “organic electroluminescent device” as used herein may comprise both organic light emitting diodes as well as organic light emitting transistors (OLETs).

As used herein, „weight percent", „wt.-%”, wt%, „percent by weight”, „% by weight”, and variations thereof refer to a composition, component, substance or agent as the weight of that component, substance or agent of the respective electron transport layer divided by the total weight of the respective electron transport layer thereof and multiplied by too. It is understood that the total weight percent amount of all components, substances and agents of the respective electron transport layer and electron injection layer are selected such that it does not exceed too wt.-%.

As used herein, „volume percent", „vol.-%”, „percent by volume”, „% by volume”, and variations thereof refer to a composition, component, substance or agent as the volume of that component, substance or agent of the respective electron transport layer divided by the total volume of the respective electron transport layer thereof and multiplied by too. It is understood that the total volume percent amount of all components, substances and agents of the cathode layer are selected such that it does not exceed too vol.-%.

All numeric values are herein assumed to be modified by the term "about", whether or not explicitly indicated. As used herein, the term "about" refers to variation in the numerical quantity that can occur. Whether or not modified by the term „about“ the claims include equivalents to the quantities.

It should be noted that, as used in this specification and the appended claims, the singular forms „a”, „an”, and „the“ include plural referents unless the content clearly dictates otherwise.

The term “free of’, “does not contain”, “does not comprise” does not exclude impurities. Impurities have no technical effect with respect to the object achieved by the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings, of which: FIG. l is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention;

FIG. 2 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

FIG. 3 is a schematic sectional view of a tandem OLED comprising a charge generation layer, according to an exemplary embodiment of the present invention.

EMBODIMENTS OF THE INVENTIVE DEVICE

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The exemplary embodiments are described below, in order to explain the aspects of the present invention, by referring to the figures.

Herein, when a first element is referred to as being formed or disposed "on" a second element, the first element can be disposed directly on the second element, or one or more other elements may be disposed there between. When a first element is referred to as being formed or disposed "directly on" a second element, no other elements are disposed there between.

FIG. l is a schematic sectional view of an organic light-emitting diode (OLED) too, according to an exemplary embodiment of the present invention. The OLED too includes a substrate no, an anode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an emission layer (EML) 150, an electron transport layer (ETL) 160. The electron transport layer (ETL) 160 is formed directly on the EML 150. Onto the electron transport layer (ETL) 160, an electron injection layer (EIL) 180 is disposed. The cathode 190 is disposed directly onto the electron injection layer (EIL) 180.

Instead of a single electron transport layer 160, optionally an electron transport layer stack (ETL) can be used.

Fig. 2 is a schematic sectional view of an OLED too, according to another exemplary embodiment of the present invention. Fig. 2 differs from Fig. 1 in that the OLED too of Fig. 2 comprises an electron blocking layer (EBL) 145 and a hole blocking layer (HBL)

155· Referring to Fig. 2, the OLED ioo includes a substrate no, an anode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an electron blocking layer (EBL) 145, an emission layer (EML) 150, a hole blocking layer (HBL) 155, an electron transport layer (ETL) 160, an electron injection layer (EIL) 180 and a cathode electrode 190.

Fig. 3 is a schematic sectional view of a tandem OLED 200, according to another exemplary embodiment of the present invention. Fig. 3 differs from Fig. 2 in that the OLED 100 of Fig. 3 further comprises a charge generation layer and a second emission layer.

Referring to Fig. 3, the OLED 200 includes a substrate 110, an anode 120, a first hole injection layer (HIL) 130, a first hole transport layer (HTL) 140, a first electron blocking layer (EBL) 145, a first emission layer (EML) 150, a first hole blocking layer (HBL) 155, a first electron transport layer (ETL) 160, an n-type charge generation layer (n-type CGL) 185, a hole generating layer (p-type charge generation layer; p-type GCL) 135, a second hole transport layer (HTL) 141, a second electron blocking layer (EBL) 146, a second emission layer (EML) 151, a second hole blocking layer (EBL) 156, a second electron transport layer (ETL) 161, a second electron injection layer (EIL) 181 and a cathode 190.

While not shown in Fig. 1, Fig. 2 and Fig. 3, a sealing layer may further be formed on the cathode electrodes 190, in order to seal the OLEDs too and 200. In addition, various other modifications maybe applied thereto.

Hereinafter, one or more exemplaiy embodiments of the present invention will be described in detail with reference to the following examples. However, these examples are not intended to limit the purpose and scope of the claims to one or more exemplary embodiments of the present invention.

EXPERIMENTAL PART

Supporting materials

The formulae of the supporting materials mentioned below are as follows:

Ft is

(Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine)], commercially available from Solaris Chem Inc., Canada)

F2 is

N-([i,i'-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H- fluoren-2-amine, CAS 1242056-42-3;

F3 is

8-(4-(4,6-di(naphthalen-2-yl)-i,3,5-triazin-2-yl)phenyl)quinoline, CAS 1312928-44-1;

F4 is

4'-(4-(4-(4,6-diphenyl-i,3,5-triazin-2-yl)phenyl)naphthalen-i-yl)-[i,i'-biphenyl]-4- carbonitrile, CAS 2032421-37-5.

ABH-113 and H09 are emitter hosts and NUBD-370 and DB-200 are blue fluorescent emitter dopants, all commercially available from SFC, Korea.

ITO is indium tin oxide, LiQ stands for lithium 8-hydroxy quinolinolate. In device experiments, compound

was used as a state-of-art benchmarking p-dopant or hole injection material for the tested inventive compounds.

Standard procedures

Device preparation

FI layer comprising the tested and/or comparative electrical dopant was prepared by spin coating on a standard glass substrate provided with an ITO layer; 1.5 wt% FI stock solution in anisole and 2 wt% stock solution of electrical dopant in benzonitrile were prepared, filtered through PTFE syringe filter having 0.2 pm pore size and mixed in the desired volume ratio before application.

Other layers were deposited by vacuum thermal evaporation (VTE).

Voltage stability

OLEDs are driven by constant current circuits. Those circuits can supply a constant current over a given voltage range. The wider the voltage range, the wider the power losses of such devices. Hence, the change of driving voltage upon driving needs to be minimized.

The driving voltage of an OLED is temperature dependent. Therefore, voltage stability needs to be judged in thermal equilibrium. Thermal equilibrium is reached after one hour of driving.

Voltage stability is measured by taking the difference of the driving voltage after 50 hours and after 1 hour driving at a constant current density. Here, a current density of 30 mA/cm² is used. Measurements are done at room temperature. dU [V] = U(50 h, 30 mA/cm²) - U(i h, 30 mA/cm²)

Synthesis of trioxatriborinane compounds Preparation ofEi

Step l: Synthesis of(perfluorophenyl)boronic acid

Bromopentafluorobenzene (l.oo g, 4.0 mmol) was added to a suspension of magnesium (0.10 g, 4.1 mmol) in ether (10 mL) at o °C. The mixture was stirred at the same temperature for 2 h and then refluxed for 1 h. The reaction mixture was cooled to o °C and added in portions to a cooled solution of B(OMe)₃ (0.60 g, 6.0 mmol) in ether (5 mL). The suspension was stirred at o °C for 1 h and then poured into 5% HCI (20 mL). After stirring for 10 min at room temperature, the organic layer was separated, the aqueous layer extracted with ether (5 mL) and the combined extracts were dried over MgS0₄. After evaporation under reduced pressure and recrystallization of the resulting solid from toluene, (perfluorophenyl)boronic acid was obtained as white solid (0.37 g, 43%)·

^UB NMR (600 MHz, acetone-d₆) d 26.3; ¹⁹F NMR (377 MHz, acetone-d₆) d -132.6 (m, 2F), -154.8 (m, lF), -163.5 (m, 2F); IR (ATR): vD = 3308, 1648, 1524, 1482, 1396, 1332, 1270, 1096, 970, 856, 775, 741, 603, 565·

Step 2: Synthesis oftris(perfluorophenyl)boroxine (El)

(Perfluorophenyl)boronic acid (0.21 g, l.o mmol) was heated at 120 °C under reduced pressure (700 mbar) for 40 min to provide tris(perfluorophenyl)boroxine (0.18 g , 94% yield). Reaction can be monitored by IR analysis. ⁿB NMR (600 MHz, acetone-do) d 19.1; ¹⁹F NMR (377 MHz, acetone-do) d -133.1 (m, 2F), -157.7 (m, lF), -163.8 (m, 2F); IR (ATR): vD = 1648, 1524, 1481, 1344, 1222, 1091, 978, 885, 756, 707, 625, 565, 482; EIMS: m/z (%) = 581 (15) [M⁺], 489 (5), 378 (12), 212 (40), 184 (55), 168 (100), 136 (50), 105 (43), 91 (25)· EI-MS: m/z (%) = 582 (100) [M⁺], 194 (40), 148 (19).

Preparation qfE2

Step l: Synthesis of(4-cyano-2,3,5,6-tetrafluorophenyl)boronic acid

To a solution of 4-bromo-2,3,5,6-tetrafluorobenzonitrile (1.00 g, 3.9 mmol) in 15 mL ether was added dropwise iPrMgCl (2.1 mL, 4.1 mmol, 2M in ether ) at -95 °C, and the reaction mixture was stirred at the same temperature. After 3 h, a solution of B(OMe)₃ (0.61 g, 5.9 mmol) in ether (5 mL) was added to the reaction mixture. The suspension was stirred at -95 °C for 2 h, warmed up to room temperature (overnight) and then poured into 5% HCI (20 mL). After stirring for 10 min at room temperature, the organic layer was separated, the aqueous layer extracted with ether (5 mL), and the combined extracts were dried over MgS0₄. After evaporation under reduced pressure (4-cyano- 2,3,5,6-tetrafluorophenyl)boronic acid was obtained as white solid (0.44 g, 51%).

^UB NMR (600 MHz, acetone-d₆) d 26.2; ¹⁹F NMR (377 MHz, acetone-d₆) d -131.0 (m, 2F), -136.7 (m, 2F); IR (ATR): vD = 3191, 1679, 1408, 1381, 1280, 1190, 884, 706, 634, 545, 474·

Step 2: Synthesis oftris(4-cyano-2,3,5,6-tetrafluorophenyl)boroxine (E2)

(4-Cyano-2,3,5,6-tetrafluorophenyl)boronic acid (0.22 g, 1.0 mmol) was heated at 120 °C under reduced pressure (800 mbar) for 2.5 h to provide tris(4-cyano-2, 3,5,6- tetrafluorophenyl)boroxine (0.18 g, 88%). (The reaction was monitored by IR analysis). ^UB NMR (600 MHz, acetone-d₆) d 19.7; IR (ATR): vD = 1702, 1465, 1382, 1269, 1153, 971, 942, 812, 703, 654, 581; EI-MS: m/z (%) = 603 (15) [M⁺], 376 (10), 190 (20), 174 (100), 100 (65).

Preparation of E3

Step 1: Synthesis of (2,3,5, 6-tetrafluoro-4-(trifluoromethyl)phenyl)boronic acid

To a solution of i-bromo-2,3,5,6-tetrafluoro-4-(trifluoromethyl)benzene (1.00 g, 3.4 mmol) in 15 mL ether was added dropwise i-PrMgCl (1.9 mL, 3.7 mmol, 2M in ether ) at -30 °C, and the reaction mixture was stirred at the same temperature for 2 h and then warmed up to o °C . After 1 h, a solution of B(OMe)₃ (0.52 g, 5.1 mmol) in ether (5 mL) was added to the reaction mixture. The suspension was stirred at o °C for 2 h, warmed up to room temperature (overnight) and then poured into 5% HC1 (20 mL). After stirring for 10 min at room temperature, the organic layer was separated, the aqueous layer was extracted with ether (5 mL), and the combined extracts were dried over MgS0₄. After evaporation of the solvent under reduced pressure, (2,3,5,6-tetrafluoro-4- (trifluoromethyl)phenyl)boronic acid was obtained as white solid (0.74 g, 84%). ^UB NMR (600 MHz, acetone-d₆) d 26. l; ¹⁹F NMR (377 MHz, acetone-d₆) d -58.3 (t, J = 21.8 Hz, 3F), -132.4 (m, 2F), 138.3 (m, 2F); IR (ATR): vD = 3340, 1464, 1430, 1345, 1312, 1161, 1033, 970, 942, 792, 713, 598, 432.

Step 2: Synthesis oftris(2,3,5,6-tetrafluoro-4-(trifluoromethyl)phenyl)boroxine (E3)

2,3,5,6-Tetrafluoro-4-(trifluoromethyl)phenyl)boronic acid (0.26 g, 1.0 mmol) was heated at 120 °C under reduced pressure (800 mbar) for 20 min to provide tris(2, 3,5,6- tetrafluoro-4-(trifluoromethyl)phenyl)boroxine (0.21 g, 87%) . (The reaction was monitored by IR analysis).

^UB NMR (600 MHz, acetone-d₆) d 19.7; ¹⁹F NMR (57 MHz, acetone-d₆) d -45-3 - -82.8 (m), -120.4 - -153-1 (m). IR (ATR): vD = 1468, 1329, 1147, 973, 804, 713, 620; EI- MS: m/z (%) = 732 (25) [M⁺], 481 (20), 265 (30), 234 (100), 218 (60), 184 (27), 98 (40).

Device experiments

1) Blue fluorescent OLED comprising a trioxatriborinane compound as a p-dopant in a hole injection layer The layer containing the tested materials (45 nm HTL doped with 8 mol% of each dopant, mol% estimation based on molar weight of the tested p-dopant and molar weight of the structural unit of Fi as depicted above) was applied directly on-top of an ITO anode by generic procedure described above. After 10 min bake-out at ioo°C, the experimental devices were transferred into the vacuum chamber of the VTE tool; subsequently, an undoped HTL made of F2 and all other layers was deposited by VTE.

Device structure is schematically described in Table 1:

Table 1

Material c d

[vol%] [nm]

ITO 90

Fi: p-dopant various (8 45 mol%)

F2 85

SFC_ABHii3: SFC_NUBD370 3 20

F3: LiQ 50 36

Al 100

Experimental OLED data are tabulated in Table 2 below. Concerning initial voltage U and external quantum efficiency EQE, El performs at least equally good or even better as the comparative material LiTFSI. Additionally, a better performance in terms of voltage stability is observed for both compounds El and E2 in comparison with Li(TFSI).

Table 2 p-dopant U EQE dU dU

(io mA/cm²) (io mA/cm²) (10 h, 30 (50 h, 30

[V] [%] mA/cm²) mA/cm²)

[V] [V]

B2 ref. 4,1 5,9 2,9 6,9 El 4,1 6,0 1,7 4,3

E2 4,4 5,8 0,4 1,6

2) Blue fluorescent OLED comprising a trioxatriborinane compound as a neat hole injection layer

Sublimed sample of El was tested in a following model device which was prepared completely by vacuum processing and is schematically described in Table 3:

Table 3

Material c d

[vol%] [nm]

ITO 90

El 100

F2 128

F4 5

H09: BD200 3 20

F5 5

F6: LiQ 50 31

Yb 2

Al 100

Experimental OLED data are shown in Table 4:

Table 4

HIL U EQE CIE-y

(10 (10 mA/cm²) mA/cm²)

[V] [V] 2 nm El 3,85 8,2 0,101

The features disclosed in the foregoing description and in the dependent claims may, both separately and in any combination thereof, be material for realizing the aspects of the disclosure made in the independent claims, in diverse forms thereof.

Claims

Claims l. Organic electronic device comprising a first electrode, a second electrode, and an organic semiconducting layer, wherein the organic semiconducting layer is arranged between the first electrode and the second electrode; the organic semiconducting layer is a hole injection layer, a hole transport layer, or a hole generating layer; and the organic semiconducting layer comprises a 1,3,5-trioxatriborinane- containg compound.

2. Organic electronic device according to claim 1, wherein the 1,3,5- trioxatriborinane-containg compound is represented by the following formula (I)

wherein R¹, R² and R³ are independently selected from the group consisting of substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl.

3. Organic electronic device according to claim 2, wherein the substituent(s) if present in one or more of R¹, R² and R³, is/are independently selected from the group consisting of halogen and CN.

4. Organic electronic device according to any of the preceding claims, wherein the organic electronic device comprises a light emitting layer; the light emitting layer is arranged between the first electrode and the second electrode; the organic semiconducting layer is arranged between the first electrode and the light emitting layer; and the organic semiconducting layer is a hole injection layer or hole transport layer.

5. Organic electronic device according to any of the preceding claims, wherein the organic electronic device is an organic electroluminescent device, an organic transistor, an organic diode, or an organic photovoltaic device.

6. Display device comprising at least one organic electronic device according to any of the preceding claims.

7. Organic semiconducting material, wherein the organic semiconducting material comprises a matrix compound and an electrical dopant; and the electrical dopant is a 1,3,5-trioxatriborinane-containg compound.

8. Compound represented by the following formula (II)

wherein

R⁴, R⁵ and R⁶ are independently selected from the group consisting of fully substituted aryl and fully substituted heteroaryl; it is provided for each of R⁴, R⁵ and R⁶ that at least one of the substituents is CN and/or at least one of the substituents is a hydrocarbyl comprising at least one sp³-hybridized carbon atom and is fully substituted with halogen atoms; and the remaining substituents of R⁴, R⁵ and R⁶ are independently selected from the group consisting of F, Cl, Br, I and CN, alternatively are independently selected from the group consisting of F, Cl, Br, and I.

9. Compound represented by the following formula (III)

Ar-B(0H)₂ (III), wherein

Ar is a fully substituted aryl or a fully substituted heteroaryl; at least one of the substituents of Ar is a hydrocarbyl fully substituted with halogen atoms and comprising at least one sp³-hybridized carbon atom; and the remaining substituents of Ar are independently selected from the group consisting of F, Cl, Br, I and CN, alternatively are independently selected from the group consisting of F, Cl, Br, and I. io. Use of a 1,3,5-trioxatriborinane-containg compound as a p-dopant and/or as a hole injection material in an electronic device.