Patent Application
20250051368
Embodiments of the present disclosure relate to ligands for organic electroluminescent compounds (complexes) and their use in organic light-emitting diodes (OLEDs) and in other optoelectronic devices.
The object of embodiments of the present disclosure is to provide ligands which are suitable for use in optoelectronic devices in the form of a complex. A ligand forms a compound (complex) with at least one central atom.
Embodiments of the present disclosure provide a new class of ligands.
The compounds (complexes) including the ligand according to embodiments of the present disclosure exhibit emission maxima in the blue or sky-blue spectral range. The compounds exhibit emission maxima below 560 nm, below 550 nm, below 545 nm or below 540 nm. It will be, for example, above 500 nm, above 510 nm, above 515 nm or above 520 nm. The photoluminescence quantum yields of the compounds according to embodiments of the present disclosure are, for example, 50% or more. The use of the compounds according to embodiments of the present disclosure in an optoelectronic device, for example an organic light-emitting diode (OLED), leads to higher efficiencies and/or higher color purity, expressed by the full width at half maximum (FWHM) of emission, of the device. Corresponding OLEDs have a higher stability than OLEDs with other existing emitter materials and comparable color. In one aspect of embodiments of the present disclosure, the compounds according to embodiments of the present disclosure might be purely organic molecules, e.g., they do not contain any metal ions in contrast to metal complexes for use in optoelectronic devices, however include metalloids, for example, B, Si, Sn, Se, and/or Ge.
In a first aspect of some embodiments, the present disclosure provides a ligand including or consisting of a structure of Formula I (an open tri-dentate ligand L):
C1-C40-thioalkoxy,
The term “open” refers to the fact that the N-heterocyclic groups A1 and A2 are not linked to each other, which allows for different coordinations of the ligand L to a central atom. In contrast, rigid ligands, such as porphyrine, are limited with respect to the coordination and are therefore referred to as “closed”.
The ligand L is a tridentate bis-anionic NNN ligand.
The ligand L can be illustrated in the coordinated form, displaying the three coordination sites, according to Formula I, the neutral uncoordinated form according to Formula I-U, the bisanionic uncoordinated form according to Formula I-B, and coordinated to a central atom M according to Formula I-M:
In one embodiment, the ring A1, ring A2, and ring A3 are independently from each other a substituted or unsubstituted heteroaromatic ring selected from the group consisting of a pyrrole, indole, isoindole, carbazole, indolocarbazole, pyridine, quinoline, isoquinoline, acridine, phenanthridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, phenothiazine, phenoxazine, pyrazole, indazole, imidazole, benzimidazole, naphthoimidazole, phenanthroimidazole, pyridoimidazole, pyrazinoimidazole, quinoxalinoimidazole, oxazole, benzoxazole, naphthooxazole, anthroxazol, phenanthroxazol, isoxazole, 1,2-thiazole, 1,3-thiazole, benzothiazole, pyridazine, benzopyridazine, pyrimidine, benzopyrimidine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, quinoxaline, pyrazine, phenazine, naphthyridine, carboline, benzocarboline, phenanthroline, 1,2,3-triazole, 1,2,4-triazole, benzotriazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,2,3,4-tetrazine, 1,2,4,5-tetrazine, purine, pteridine, indolizine and benzothiadiazole.
In another embodiment, at least one N-heterocyclic ring selected from A1, A2, and A3 includes a 6-membered N-heterocyclic ring and at least one N-heterocyclic ring selected from the group consisting of A1, A2, and A3 includes a 5-membered N-heterocyclic ring.
In one embodiment, at least one N-heterocyclic ring selected from A1, A2, and A3 is a substituted or unsubstituted pyridine or substituted or unsubstituted diazine.
In a preferred embodiment, at least one N-heterocyclic ring selected from A1, A2, and A3 is a substituted or unsubstituted pyridine.
In one embodiment, A3 is a substituted or unsubstituted pyridine or substituted or unsubstituted diazine.
In a preferred embodiment, at least one N-heterocyclic ring selected from A1, A2, and A3 is a substituted or unsubstituted pyridine.
In a preferred embodiment, A3 is a substituted or unsubstituted pyridine.
In one embodiment, the ligand L includes or consists of a structure of Formula II:
In one embodiment, the ligand L includes or consists of a structure of Formula III:
In one embodiment, the ligand L includes or consists of a structure of Formula III-2:
In a further embodiment of the present disclosure, Ra2 is at each occurrence independently from another selected from the group consisting of:
In a further embodiment of the present disclosure, Ra2 is at each occurrence independently from another selected from the group consisting of:
In a further embodiment of the present disclosure, Ra2 is at each occurrence independently from another selected from the group consisting of:
In one embodiment, the ligand L includes or consists of a structure of Formula III-3:
In a further embodiment of the present disclosure, Rb is at each occurrence independently from another selected from the group consisting of:
In a further embodiment of the present disclosure, Rb is at each occurrence independently from another selected from the group consisting of:
In one embodiment, the ligand L includes or consists of a structure of Formula IIIa:
In one embodiment, the ligand L includes or consists of a structure of Formula IIIa-2:
In one embodiment, the ligand L includes or consists of a structure of Formula IIIa-3:
In one embodiment, the ligand L includes or consists of a structure of Formula IIIb:
In one embodiment, the ligand L includes or consists of a structure of Formula IIIb-2:
In one embodiment, the ligand L includes or consists of a structure of Formula IIIb-3:
In one embodiment, Z is a direct bond (e.g., a covalent bond) at each occurrence.
In a further embodiment of the present disclosure, R3 is at each occurrence independently from another selected from the group consisting of:
Examples of the ligand L are shown in the following:
A further aspect of embodiments of the present disclosure relates to a compound including the ligand L.
In one embodiment, the compound of the present disclosure includes or consists of a structure of (L)v-M-(RY)w, wherein
In one embodiment, M is B, Ir, Pd or Pt.
In one embodiment, the compound is an organic material, wherein M is B, Si, Sn, Se or Ge.
In one embodiment of the present disclosure, the compound is a tetrahedral complex.
In one embodiment, the compound of the present disclosure includes or consists of a structure of L-B—RX:
In one embodiment, the compound of the present disclosure includes or consists of a structure of L-B—RX, wherein the compound is a tetrahedral complex.
In one embodiment, RX is selected from the group consisting of: N(R5)2, OR5, Si(R5)3, B(OR5)2, OSO2R5, CF3, CN, F, Br, I,
In a further embodiment of the present disclosure, RX is selected from the group consisting of:
In one embodiment, RX is selected from the group consisting of:
Examples of compounds of the present disclosure according to L-B—RX:
Herein, the term “layer” refers to a body that bears an extensively planar geometry. It should be readily apparent to those skilled in the art upon reviewing this disclosure that optoelectronic devices may be composed of several layers.
A light-emitting layer (EML) in the context of the present disclosure is a layer of an optoelectronic device, wherein light emission from said layer is observed when applying a voltage and electrical current to the device. The person skilled in the art understands that light emission from optoelectronic devices is attributed to light emission from at least one EML. The skilled artisan understands that light emission from an EML is typically not (mainly) attributed to all materials included in said EML, but instead to certain emitter materials.
An “emitter material” or “emitter compound” (also referred to as “emitter”) in the context of the present disclosure is a material that emits light when it is included in a light-emitting layer (EML) of an optoelectronic device (vide infra), given that a voltage and electrical current are applied to said device. The person skilled in the art should recognize that an emitter material usually is an “emissive dopant” material, and the skilled artisan should recognize that a dopant material (may it be emissive or not) is a material that is embedded in a matrix material that is usually (and herein) referred to as host material. Herein, host materials are also in general referred to as HB when they are included in an optoelectronic device (preferably an OLED) including at least one compound according to embodiments of the present disclosure.
In the context of the present disclosure, the term “cyclic group” may be understood in the broadest sense as any mono-, bi- or polycyclic moiety.
In the context of the present disclosure, the term “ring” when referring to chemical structures may be understood in the broadest sense as any monocyclic moiety. Along the same lines, the term “rings” when referring to chemical structures may be understood in the broadest sense as any bi- or polycyclic moiety.
In the context of the present disclosure, the term “ring system” may be understood in the broadest sense as any mono-, bi- or polycyclic moiety.
In the context of the present disclosure, the term “ring atom” refers to any atom which is part of the cyclic core of a ring or a ring system, and not part of a non-cyclic substituent optionally attached to the cyclic core.
In the context of the present disclosure, the term “carbocycle” may be understood in the broadest sense as any cyclic group in which the cyclic core structure includes only carbon atoms that may of course be substituted with hydrogen or any other substituents defined in embodiments of the present disclosure. It is understood that the term “carbocyclic” as adjective refers to cyclic groups in which the cyclic core structure includes only carbon atoms that may of course be substituted with hydrogen or any other substituents defined in embodiments of the present disclosure.
In the context of the present disclosure, the term “heterocycle” may be understood in the broadest sense as any cyclic group in which the cyclic core structure includes not just carbon atoms, but also at least one heteroatom. It is understood that the term “heterocyclic” as adjective refers to cyclic groups in which the cyclic core structure includes not just carbon atoms, but also at least one heteroatom. The heteroatoms may, unless stated otherwise in specific embodiments, at each occurrence be the same or different and may be individually selected from the group consisting of B, Si, N, O, S, and Se, for example, B, N, O and S, or N, O, S. All carbon atoms or heteroatoms included in a heterocycle in the context of the present disclosure may of course be substituted with hydrogen or any other substituents defined in the specific embodiments of the present disclosure.
The person skilled in the art should recognize that any cyclic group (e.g., any carbocycle and heterocycle) may be aliphatic or aromatic or heteroaromatic.
In the context of the present disclosure, the term aliphatic when referring to a cyclic group (e.g., to a ring, to rings, to a ring system, to a carbocycle, to a heterocycle) means that the cyclic core structure (not counting substituents that are optionally attached to it) contains at least one ring atom that is not part of an aromatic or heteroaromatic ring or ring system. In some embodiments, the majority of ring atoms and, for example, all ring atoms within an aliphatic cyclic group are not part of an aromatic or heteroaromatic ring or ring system (such as in cyclohexane or in piperidine for example). Herein, no differentiation is made between carbocyclic and heterocyclic groups when referring to aliphatic rings or ring systems in general, whereas the term “aliphatic” may be used as adjective to describe a carbocycle or heterocycle in order to indicate whether or not a heteroatom is included in the aliphatic cyclic group.
As understood by the skilled artisan, the terms “aryl” and “aromatic” may be understood in the broadest sense as any mono-, bi- or polycyclic aromatic moieties, e.g., cyclic groups in which all ring atoms are part of an aromatic ring system, for example, part of the same aromatic ring system. However, throughout the present application, the terms “aryl” and “aromatic” are restricted to mono-, bi- or polycyclic aromatic moieties wherein all aromatic ring atoms are carbon atoms. In contrast, the terms “heteroaryl” and “heteroaromatic” herein refer to any mono-, bi- or polycyclic aromatic moieties, wherein at least one aromatic carbon ring atom is replaced by a heteroatom (e.g., not carbon). Unless stated otherwise in specific embodiments of the disclosure, the at least one heteroatom within a “heteroaryl” or “heteroaromatic” may at each occurrence be the same or different and be individually selected from the group consisting of N, O, S, and Se, or, for example, N, O, and S. The person skilled in the art understands that the adjectives “aromatic” and “heteroaromatic” may be used to describe any cyclic group (e.g., any ring system). This is to say that an aromatic cyclic group (e.g., an aromatic ring system) is an aryl group and a heteroaromatic cyclic group (e.g., a heteroaromatic ring system) is a heteroaryl group.
Unless indicated differently in embodiments of the disclosure, an aryl group herein contains 6 to 60 aromatic ring atoms, 6 to 40 aromatic ring atoms, or 6 to 18 aromatic ring atoms. Unless indicated differently in embodiments of the disclosure, a heteroaryl group herein contains 5 to 60 aromatic ring atoms, 5 to 40 aromatic ring atoms, or 5 to 20 aromatic ring atoms, out of which at least one is a heteroatom selected from N, O, S, and Se, or from N, O, and S. If more than one heteroatom is included an a heteroaromatic group, all heteroatoms are independently of each other selected from N, O, S, and Se, or from N, O, and S.
In the context of the present disclosure, for both aromatic and heteroaromatic groups (for example aryl or heteroaryl substituents), the number of aromatic ring carbon atoms may be given as subscripted number in the definition of certain substituents, for example in the form of “C6-C60-aryl”, which means that the respective aryl substituent includes 6 to 60 aromatic carbon ring atoms. The same subscripted numbers are herein also used to indicate the allowable number of carbon atoms in all other kinds of substituents, regardless of whether they are aliphatic, aromatic or heteroaromatic substituents. For example, the expression “C1-C40-alkyl” refers to an alkyl substituent including 1 to 40 carbon atoms.
Examples of aryl groups include groups derived from benzene, naphthalene, anthracene, phenanthrene, pyrene, dihydropyrene, chrysene, perylene, fluoranthene, benzanthracene, benzophenanthrene, tetracene, pentacene, benzopyrene or combinations of these groups.
Examples of heteroaryl groups include groups derived from furan, benzofuran, isobenzofuran, dibenzofuran, thiophene, benzothiophene, isobenzothiophene, dibenzothiophene; pyrrole, indole, isoindole, carbazole, indolocarbazole, pyridine, quinoline, isoquinoline, acridine, phenanthridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, phenothiazine, phenoxazine, pyrazole, indazole, imidazole, benzimidazole, naphthoimidazole, phenanthroimidazole, pyridoimidazole, pyrazinoimidazole, quinoxalinoimidazole, oxazole, benzoxazole, napthooxazole, anthroxazol, phenanthroxazol, isoxazole, 1,2-thiazole, 1,3-thiazole, benzothiazole, pyridazine, benzopyridazine, pyrimidine, benzopyrimidine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, quinoxaline, pyrazine, phenazine, naphthyridine, carboline, benzocarboline, phenanthroline, 1,2,3-triazole, 1,2,4-triazole, benzotriazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,2,3,4-tetrazine, 1,2,4,5-tetrazine, purine, pteridine, indolizine and benzothiadiazole or combinations of these groups.
As used throughout the present application, the term “arylene” refers to a divalent aryl substituent that bears two binding sites to other molecular structures, thereby serving as a linker structure. Along the same lines, the term “heteroarylene” refers to a divalent aryl substituent that bears two binding sites to other molecular structures, thereby serving as a linker structure.
In the context of the present disclosure, the term “fused” when referring to aromatic or heteroaromatic ring systems means that the aromatic or heteroaromatic rings that are “fused” share at least one bond that is part of both ring systems. For example, naphthalene (or naphthyl when referred to as substituent) or benzothiophene (or benzothiophenyl when referred to as substituent) are considered fused aromatic ring systems in the context of the present disclosure, in which two benzene rings (for naphthalene) or a thiophene and a benzene (for benzothiophene) share one bond. It is also understood that sharing a bond in this context includes sharing the two atoms that build up the respective bond and that fused aromatic or heteroaromatic ring systems can be understood as one aromatic or heteroaromatic ring system. Additionally, it is understood, that more than one bond may be shared by the aromatic or heteroaromatic rings building up a fused aromatic or heteroaromatic ring system (e.g. in pyrene). Furthermore, it will be understood that aliphatic ring systems may also be fused and that this has the same meaning as for aromatic or heteroaromatic ring systems, with the exception of course, that fused aliphatic ring systems are not aromatic. Furthermore, it is understood that an aromatic or heteroaromatic ring system may also be fused to (in other words: share at least one bond with) an aliphatic ring system.
In the context of the present disclosure, the term “condensed” ring system has the same meaning as “fused” ring system.
In certain embodiments of the disclosure, adjacent substituents bonded to a ring or a ring system may together form an additional mono- or polycyclic, aliphatic, aromatic or heteroaromatic ring system which is fused to the aromatic or heteroaromatic ring or ring system to which the substituents are bonded. It is understood that the optionally so formed fused ring system will be larger (meaning it includes more ring atoms) than the aromatic or heteroaromatic ring or ring system to which the adjacent substituents are bonded. In these cases (and if such a number is provided), the “total” amount of ring atoms included in the fused ring system is to be understood as the sum of ring atoms included in the aromatic or heteroaromatic ring or ring system to which the adjacent substituents are bonded and the ring atoms of the additional ring system formed by the adjacent substituents, wherein, however, the ring atoms that are shared by fused rings are counted once and not twice. For example, a benzene ring may have two adjacent substituents that together form another benzene ring so that a naphthalene core is built. This naphthalene core then includes 10 ring atoms as two carbon atoms are shared by the two benzene rings and are thus only counted once and not twice.
In general, in the context of the present disclosure, the terms “adjacent substituents” or “adjacent groups” refer to substituents or groups bonded to either the same or to neighboring atoms.
In the context of the present disclosure, the term “alkyl group” may be understood in the broadest sense as any linear, branched, or cyclic alkyl substituent.
Examples of alkyl groups as substituents include methyl (Me), ethyl (Et), n-propyl (nPr), i-propyl (iPr), cyclopropyl, n-butyl (nBu), i-butyl (iBu), s-butyl (sBu), t-butyl (tBu), cyclobutyl, 2-methylbutyl, n-pentyl, s-pentyl, t-pentyl, 2-pentyl, neo-pentyl, cyclopentyl, n-hexyl, s-hexyl, t-hexyl, 2-hexyl, 3-hexyl, neo-hexyl, cyclohexyl, 1-methylcyclopentyl, 2-methylpentyl, n-heptyl, 2-heptyl, 3-heptyl, 4-heptyl, cycloheptyl, 1-methylcyclohexyl, n-octyl, 2-ethylhexyl, cyclooctyl, 1-bicyclo[2,2,2]octyl, 2-bicyclo[2,2,2]-octyl, 2-(2,6-dimethyl)octyl, 3-(3,7-dimethyl)octyl, adamantyl, 1,1-dimethyl-n-hex-1-yl, 1,1-dimethyl-n-hept-1-yl, 1,1-dimethyl-n-oct-1-yl, 1,1-dimethyl-n-dec-1-yl, 1,1-dimethyl-n-dodec-1-yl, 1,1-dimethyl-n-tetradec-1-yl, 1,1-dimethyl-n-hexadec-1-yl, 1,1-dimethyl-n-octadec-1-yl, 1,1-diethyl-n-hex-1-yl, 1,1-diethyl-n-hept-1-yl, 1,1-diethyl-n-oct-1-yl, 1,1-diethyl-n-dec-1-yl, 1,1-diethyl-n-dodec-1-yl, 1,1-diethyl-n-tetradec-1-yl, 1,1-diethyl-n-hexadec-1-yl, 1,1-diethyl-n-octadec-1-yl, 1-(n-propyl)-cyclohex-1-yl, 1-(n-butyl)-cyclohex-1-yl, 1-(n-hexyl)-cyclohex-1-yl, 1-(n-octyl)-cyclohex-1-yl and 1-(n-decyl)-cyclohex-1-yl.
The “s” in for example s-butyl, s-pentyl and s-hexyl refers to “secondary”; or in other words: s-butyl, s-pentyl and s-hexyl are equal to sec-butyl, sec-pentyl and sec-hexyl, respectively. The “t” in for example t-butyl, t-pentyl and t-hexyl refers to “tertiary”; or in other words: t-butyl, t-pentyl and t-hexyl are equal to tert-butyl, tert-pentyl and tert-hexyl, respectively.
As used herein, the term “alkenyl” includes linear, branched, and cyclic alkenyl substituents. The term alkenyl group exemplarily includes the substituents ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl or cyclooctadienyl.
As used herein, the term “alkynyl” includes linear, branched, and cyclic alkynyl substituents. The term alkynyl group exemplarily includes ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl or octynyl.
As used herein, the term “alkoxy” includes linear, branched, and cyclic alkoxy substituents. The term alkoxy group exemplarily includes methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy and 2-methylbutoxy.
As used herein, the term “thioalkoxy” includes linear, branched, and cyclic thioalkoxy substituents, in which the oxygen atom O of the corresponding alkoxy groups is replaced by sulfur, S.
As used herein, the terms “halogen” (or “halo” when referred to as substituent in chemical nomenclature) may be understood in the broadest sense as any atom of an element of the 7th main group (in other words: group 17) of the periodic table of elements, for example, fluorine, chlorine, bromine or iodine.
It is understood that when a molecular fragment is described as being a substituent or otherwise attached to another moiety, its name may be written as if it was a fragment (e.g., naphthyl, dibenzofuryl) or as if it was the intact group (e.g., naphthalene, dibenzofuran). As used herein, these different ways of designating a substituent or attached fragment are considered to be equivalent.
Furthermore, herein, whenever a substituent such as “C6-C60-aryl” or “C1-C40-alkyl” is referred to without the name indicating the binding site within that substituent, this is to mean that the respective substituent may bond via any atom. For example, a “C6-C60-aryl”-substituent may bond via any of the 6 to 60 aromatic carbon atoms and a “C1-C40-alkyl”-substituent may bond via any of the 1 to 40 aliphatic carbon atoms. On the other hand, a “2-cyanophenyl”-substituent can only be bonded in such a way that its CN-group is adjacent to the binding site as to allow for the chemical nomenclature to be correct.
In the context of the present disclosure, whenever a substituent such as “butyl”, “biphenyl” or “terphenyl” is referred to without further detail, this is to mean that any isomer of the respective substituent is allowable as the substituent. In this regard, for example the term “butyl” as substituent includes n-butyl, s-butyl, t-butyl, and iso-butyl as substituents. Along the same lines, the term “biphenyl” as substituent includes ortho-biphenyl, meta-biphenyl, or para-biphenyl, wherein ortho, meta and para are defined with regard to the binding site of the biphenyl substituent to the respective chemical moiety that bears the biphenyl substituent. Similarly, the term “terphenyl” as substituent includes 3-ortho-terphenyl, 4-ortho-terphenyl, 4-meta-terphenyl, 5-meta-terphenyl, 2-para-terphenyl or 3-para-terphenyl, wherein, as known to the skilled artisan, ortho, meta and para indicate the position of the two Ph-moieties within the terphenyl-group to each other and “2-”, “3-”, “4-” and “5-” denotes the binding site of the terphenyl substituent to the respective chemical moiety that bears the terphenyl substituent.
It is understood that all groups defined above and indeed all chemical moieties, regardless of whether they are cyclic or non-cyclic, aliphatic, aromatic or heteroaromatic, may be further substituted in accordance with embodiments described herein.
All hydrogen atoms (H) included in any structure referred to herein may at each occurrence independently and, be replaced by deuterium (D) without this being indicated specifically. The replacement of hydrogen by deuterium should be readily recognizable by the person skilled in the art upon reviewing this disclosure. Thus, there are numerous suitable methods by which this can be achieved and several review articles describing them.
If experimental or calculated data are compared, the values have to be determined by the same methodology. For example, if an experimental ΔEST is determined to be below 0.4 eV by a specific method, a comparison is only valid using the same specific method including the same conditions. To give a specific example, the comparison of the photoluminescence quantum yield (PLQY) of different compounds is only valid if the determination of the PLQY value was performed under the same reaction conditions (e.g., measurement in a 10% PMMA film at room temperature). Similarly, calculated energy values need to be determined by the same calculation method (e.g., using the same functional and the same basis set).
An optoelectronic device including at least one compound with a ligand according to embodiments of the disclosure
A further aspect of the disclosure relates to an optoelectronic device including at least one compound according to the present disclosure.
In one embodiment, the optoelectronic device including at least one compound according to the present disclosure is selected from the group consisting of:
A light-emitting electrochemical cell includes or consists of three layers, namely a cathode, an anode, and an active layer, which may contain the compound according to the disclosure.
In an embodiment, the optoelectronic device including at least one compound according to the present disclosure is selected from the group consisting of an organic light emitting diode (OLED), a light emitting electrochemical cell (LEC), an organic laser, and a light-emitting transistor.
In an embodiment, the optoelectronic device including at least one compound according to the present disclosure is an organic light-emitting diode (OLED).
In one embodiment, the optoelectronic device including at least one compound according to the present disclosure is an OLED that may exhibit the following layer structure:
Furthermore, the optoelectronic device including at least one compound according to the present disclosure may optionally include one or more protective layers protecting the device from damaging exposure to harmful species in the environment including, exemplarily moisture, vapor and/or gases.
In one embodiment, the optoelectronic device including at least one compound according to the present disclosure is an OLED, that may exhibit the following (inverted) layer structure:
The compounds according to the disclosure (in accordance with the embodiments indicated above) can be employed in various suitable layers, depending on the precise structure and on the substitution. In the case of the use, the fraction of the compound according to the disclosure in the respective layer in an optoelectronic device, for example, in an OLED, is 0.1% to 99% by weight, or 1% to 80% by weight. In some embodiments, the proportion of the compound in the respective layer is 100% by weight.
In one embodiment, of the optoelectronic device including at least one compound according to the present disclosure is an OLED which may exhibit stacked architecture. In this architecture, contrary to other arrangements, where the OLEDs are placed side by side, the individual units are stacked on top of each other. Blended light may be generated with OLEDs exhibiting a stacked architecture, for example, white light may be generated by stacking blue, green and red OLEDs. Furthermore, the OLED exhibiting a stacked architecture may optionally include a charge generation layer (CGL), which may be between two OLED subunits and may include or consist of a n-doped and p-doped layer with the n-doped layer of one CGL being located closer to the anode layer.
In one embodiment, the optoelectronic device including at least one compound according to the present disclosure is an OLED, which includes two or more emission layers between anode and cathode. In some embodiments, this so-called tandem OLED includes three emission layers, wherein one emission layer emits red light, one emission layer emits green light and one emission layer emits blue light, and optionally may include further layers such as charge generation layers, blocking or transporting layers between the individual emission layers. In a further embodiment, the emission layers are adjacently stacked. In a further embodiment, the tandem OLED includes a charge generation layer between each two emission layers. In addition, adjacent emission layers or emission layers separated by a charge generation layer may be merged.
In one embodiment, the optoelectronic device including at least one compound according to the present disclosure may be an essentially white optoelectronic device, which is to say that the device emits white light. Exemplarily, such a white light-emitting optoelectronic device may include at least one (deep) blue emitter molecule and one or more emitter molecules that emit green and/or red light. Then, there may also optionally be energy transmittance between two or more molecules as described in a below section of this text (vide infra).
In the case of the optoelectronic device including at least one compound according to the present disclosure, the at least one compound according to the present disclosure is included in a light-emitting layer (EML) of the optoelectronic device, for example, in an EML of an OLED. However, the compounds according to the disclosure may for example also be employed in an electron transport layer (ETL) and/or in an electron blocking layer (EBL) or exciton-blocking layer and/or in a hole transport layer (HTL) and/or in a hole blocking layer (HBL). In the case of the use, the fraction of the compound according to the disclosure in the respective layer in an optoelectronic device, for example, in an OLED, is 0.1% to 99% by weight, 0.5% to 80% by weight, or 0.5% to 10% by weight. In some embodiments, the proportion of the compound in the respective layer is 100% by weight.
The selection criteria for suitable materials for the individual layers of optoelectronic devices, for example, OLEDs, should be readily recognizable by those skilled in the art upon reviewing this disclosure. The state of the art describes plenty of materials to be used in the individual layers and also teaches which materials are suitable to be used alongside each other. It is understood that any materials used in the state of the art may also be used in optoelectronic devices including the compound according to the present disclosure. In the following, examples of materials for the individual layers will be given. It is understood that this does not imply that all types of layers listed below must be present in an optoelectronic device including at least one compound according to the present disclosure. Additionally, it is understood that an optoelectronic device including at least one compound according to the present disclosure may include more than one of each of the layers listed in the following, for example two or more light-emitting layers (EMLs). It is also understood that two or more layers of the same type (e.g. two or more EMLs or two or more HTLs) do not necessarily include the same materials or even the same materials in the same ratios. Furthermore, it is understood that an optoelectronic device including at least one compound according to the present disclosure does not have to include all the layer types listed in the following, wherein an anode layer, a cathode layer, and a light-emitting layer will usually be present in all cases.
The substrate may be formed by any suitable material or composition of materials. Most frequently, glass slides are used as substrates. In some embodiments, thin metal layers (e.g., copper, gold, silver and/or aluminum films) and/or plastic films and/or slides may be used. This may allow a higher degree of flexibility. The anode layer A is mostly composed of materials allowing to obtain an (essentially) transparent film. As at least one of both electrodes should be (essentially) transparent in order to allow light emission from the OLED, either the anode layer A or the cathode layer C is usually transparent. In some embodiments, the anode layer A includes a large content or even consists of transparent conductive oxides (TCOs). Such an anode layer A may, for example, include indium tin oxide, aluminum zinc oxide, fluorine doped tin oxide, indium zinc oxide, PbO, SnO, zirconium oxide, molybdenum oxide, vanadium oxide, wolfram oxide, graphite, doped Si, doped Ge, doped GaAs, doped polyaniline, doped polypyrrole and/or doped polythiophene.
In some embodiments, an anode layer A (essentially) consists of indium tin oxide (ITO) (e.g., (InO3)0.9(SnO2)0.1). The roughness of an anode layer A caused by the transparent conductive oxides (TCOs) may be compensated by using a hole injection layer (HIL). Further, a HIL may facilitate the injection of quasi charge carriers (e.g., holes) in that the transport of the quasi charge carriers from the TCO to the hole transport layer (HTL) is facilitated. A hole injection layer (HIL) may include poly-3,4-ethylenedioxy thiophene (PEDOT), polystyrene sulfonate (PSS), MoO2, V2O5, CuPC or CuI, for example, a mixture of PEDOT and PSS. A hole injection layer (HIL) may also prevent or reduce the diffusion of metals from an anode layer A into a hole transport layer (HTL). A HIL may for example include PEDOT:PSS (poly-3,4-ethylendioxy thiophene: polystyrene sulfonate), PEDOT (poly-3,4-ethylendioxy thiophene), mMTDATA (4,4′,4″-tris[phenyl(m-tolyl)amino]triphenylamine), Spiro-TAD (2,2′,7,7′-tetrakis(n,n-diphenylamino)-9,9′-spirobifluorene), DNTPD (N1,N1′-(biphenyl-4,4′-diyl)bis(N1-phenyl-N4,N4-di-m-tolylbenzene-1,4-diamine), NPB (N,N′-bis-(1-naphthalenyl)-N,N′-bis-phenyl-(1,1′-biphenyl)-4,4′-diamine), NPNPB (N,N′-diphenyl-N,N′-di-[4-(N,N-diphenyl-amino)phenyl]benzidine), MeO-TPD (N,N,N′,N′-tetrakis(4-methoxyphenyl)benzidine), HAT-CN (1,4,5,8,9,11-hexaazatriphenylen-hexacarbonitrile) and/or Spiro-NPD (N,N′-diphenyl-N,N′-bis-(1-naphthyl)-9,9′-spirobifluorene-2,7-diamine).
Adjacent to an anode layer A or a hole injection layer (HIL), a hole transport layer (HTL) may be located. Herein, any suitable hole transport material may be used. Exemplarily, electron-rich heteroaromatic compounds such as triarylamines and/or carbazoles may be used as hole transport compound. A HTL may decrease the energy barrier between an anode layer A and a light-emitting layer EML. A hole transport layer (HTL) may also be an electron blocking layer (EBL). In some embodiments, hole transport compounds bear comparably high energy levels of their lowermost excited triplet states T1. Exemplarily, a hole transport layer (HTL) may include a star-shaped heterocyclic compound such as tris(4-carbazoyl-9-ylphenyl)amine (TCTA), poly-TPD (poly(4-butylphenyl-diphenyl-amine)), [alpha]-NPD (poly(4-butylphenyl-diphenyl-amine)), TAPC (4,4′-cyclohexyliden-bis[N,N-bis(4-methylphenyl)benzenamine]), 2-TNATA (4,4′,4″-tris[2-naphthyl(phenyl)amino]triphenylamine), Spiro-TAD (2,2′,7,7′-tetrakis(n,n-diphenylamino)-9,9′-spirobifluorene), DNTPD (N1,N1′-(biphenyl-4,4′-diyl)bis(N1-phenyl-N4,N4-di-m-tolylbenzene-1,4-diamine), NPB (N,N′-bis-(1-naphthalenyl)-N,N′-bis-phenyl-(1,1′-biphenyl)-4,4′-diamine)), NPNPB (N,N′-diphenyl-N,N′-di-[4-(N,N-diphenyl-amino)phenyl]benzidine), MeO-TPD (N,N,N′,N′-tetrakis(4-methoxyphenyl)benzidine), HAT-CN (1,4,5,8,9,11-hexaazatriphenylen-hexacarbonitrile) and/or TrisPcz (9,9′-diphenyl-6-(9-phenyl-9H-carbazol-3-yl)-9H,9′H-3,3′-bicarbazole). In addition, a HTL may include a p-doped layer, which may be composed of an inorganic or organic dopant in an organic hole-transporting matrix. Transition metal oxides such as vanadium oxide, molybdenum oxide or tungsten oxide may be used as an inorganic dopant. Tetrafluorotetracyanoquinodimethane (F4-TCNQ), copper-pentafluorobenzoate (Cu(I)pFBz) and/or transition metal complexes may be used as organic dopant.
An EBL may for example include mCP (1,3-bis(carbazol-9-yl)benzene), TCTA (tris(4-carbazoyl-9-ylphenyl)amine), 2-TNATA (4,4′,4″-tris[2-naphthyl(phenyl)amino]triphenylamine), mCBP (3,3-di(9H-carbazol-9-yl)biphenyl), tris-Pcz (9-Phenyl-3,6-bis(9-phenyl-9H-carbazol-3-yl)-9H-carbazole), CzSi (9-(4-tert-Butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole), and/or DCB (N,N′-dicarbazolyl-1,4-dimethylbenzene).
Adjacent to a hole transport layer (HTL) or (if present) an electron blocking layer (EBL), for example, a light-emitting layer (EML) is located. A light-emitting layer (EML) includes at least one light-emitting molecule (e.g., emitter material). In some embodiments, an EML additionally includes one or more host materials (also referred to as matrix materials). Exemplarily, the host material may be selected from CBP (4,4′-Bis-(N-carbazolyl)-biphenyl), mCP (1,3-bis(carbazol-9-yl)benzene), mCBP (3,3-di(9H-carbazol-9-yl)biphenyl), Sif87 (dibenzo[b,d]thiophen-2-yltriphenylsilane), CzSi (9-(4-tert-Butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole), Sif88 (dibenzo[b,d]thiophen-2-yl)diphenylsilane), DPEPO (bis[2-(diphenylphosphino)phenyl]ether oxide), 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzothiophen-2-yl)phenyl]-9H-carbazole, 9-[3,5-bis(2-dibenzofuranyl)phenyl]-9H-carbazole, 9-[3,5-bis(2-dibenzothiophenyl)phenyl]-9H-carbazole, T2T (2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine), T3T (2,4,6-tris(triphenyl-3-yl)-1,3,5-triazine) and/or TST (2,4,6-tris(9,9′-spirobifluorene-2-yl)-1,3,5-triazine). As should be readily recognizable to the person skilled in the art upon reviewing this disclosure, a host material should be selected to exhibit first (e.g., lowermost) excited triplet state (T1) and first (e.g., lowermost) excited singlet (S1) energy levels, which are energetically higher than the first (e.g., lowermost) excited triplet state (T1) and first (e.g., lowermost) excited singlet state (S1) energy levels of the at least one light-emitting molecule that is embedded in the respective host material(s).
As stated previously, in some embodiments, at least one EML of the optoelectronic device in the context of the disclosure includes at least one molecule according to the present disclosure. The compositions of an EML of an optoelectronic device including at least one compound according to the present disclosure are described in more detail in a below section of this text (vide infra).
Adjacent to a light-emitting layer (EML), an electron transport layer (ETL) may be located. Herein, any suitable electron transport material may be used. Exemplarily, compounds bearing electron-deficient groups, such as for example benzimidazoles, pyridines, triazoles, triazines, oxadiazoles (e.g., 1,3,4-oxadiazole), phosphinoxides and sulfones, may be used. An electron transport material may also be a star-shaped heterocyclic compound such as 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi). An ETL may for example include Nbphen (2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline), Alq3 (Aluminum-tris(8-hydroxyquinoline)), TSPO1 (diphenyl-4-triphenylsilylphenyl-phosphinoxide), BpyTP2 (2,7-di(2,2′-bipyridin-5-yl)triphenylene), Sif87 (dibenzo[b,d]thiophen-2-yltriphenylsilane), Sif88 (dibenzo[b,d]thiophen-2-yl)diphenylsilane), BmPyPhB (1,3-bis[3,5-di(pyridin-3-yl)phenyl]benzene) and/or BTB (4,4′-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1′-biphenyl). Optionally, an ETL may be doped with materials such as Liq ((8-hydroxyquinolinato)lithium). An electron transport layer (ETL) may also block holes or a hole blocking layer (HBL) is introduced, for example, between an EML and an ETL.
A hole blocking layer (HBL) may for example include BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline=bathocuproine), 4,6-diphenyl-2-(3-(triphenylsilyl)phenyl)-1,3,5-triazin, 9,9′-(5-(6-([1,1′-biphenyl]-3-yl)-2-phenylpyrimidin-4-yl)-1,3-phenylene)bis(9H-carbazole), BAlq (bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum), NBphen (2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline), Alq3 (aluminum-tris(8-hydroxyquinoline)), TSPO1 (diphenyl-4-triphenylsilylphenyl-phosphinoxide), T2T (2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine), T3T (2,4,6-tris(triphenyl-3-yl)-1,3,5-triazine), TST (2,4,6-tris(9,9′-spirobifluorene-2-yl)-1,3,5-triazine), and/or TCB/TCP (1,3,5-tris(N-carbazolyl)benzol/1,3,5-tris(carbazol)-9-yl)benzene).
A cathode layer C may be located adjacent to the electron transport layer (ETL). For example, the cathode layer C may include or may consist of a metal (e.g., Al, Au, Ag, Pt, Cu, Zn, Ni, Fe, Pb, LiF, Ca, Ba, Mg, In, W, and/or Pd) and/or a metal alloy. For practical reasons, the cathode layer may consist of (essentially) non-transparent metals such as Mg, Ca and/or Al. Alternatively or additionally, the cathode layer C may also include graphite and/or carbon nanotubes (CNTs). In some embodiments, the cathode layer C may also include or consist of nanoscalic silver wires.
An OLED including at least one compound according to the present disclosure may further, optionally include a protection layer between an electron transport layer (ETL) and a cathode layer C (which may be designated as electron injection layer (EIL)). This layer may include lithium fluoride, cesium fluoride, silver, Liq ((8-hydroxyquinolinato)lithium), Li2O, BaF2, MgO and/or NaF.
Optionally, an electron transport layer (ETL) and/or a hole blocking layer (HBL) may also include one or more host materials.
As used herein, if not defined more specifically in the particular context, the designation of the colors of emitted and/or absorbed light is as follows:
With respect to light-emitting molecules (in other words: emitter materials), such colors refer to the emission maximum of the main emission peak. Therefore, exemplarily, a deep blue emitter has an emission maximum in the range of from >420 to 480 nm, a sky-blue emitter has an emission maximum in the range of from >480 to 500 nm, a green emitter has an emission maximum in a range of from >500 to 560 nm, and a red emitter has an emission maximum in a range of from >620 to 800 nm.
A deep blue emitter may have an emission maximum of below 475 nm, below 470 nm, below 465 nm or below 460 nm. It may be above 420 nm, above 430 nm, above 440 nm or above 450 nm. In an embodiment, the compounds according to the present disclosure exhibit emission maxima between 420 and 500 nm, between 430 and 490 nm, between 440 and 480 nm, or between 450 and 470 nm, typically measured at room temperature (e.g., (approximately) 20° C.) from a spin-coated film with 1 to 5%, 2% by weight of the compound according to the disclosure in poly(methyl methacrylate), PMMA, mCBP or, in some embodiments, in an organic solvent, for example, DCM and/or toluene, with 0.001 mg/mL of compound according to the disclosure.
A further embodiment relates to an OLED including at least one compound according to the present disclosure and that emits light with CIEx and CIEy color coordinates close to the CIEx (=0.131) and CIEy (=0.046) color coordinates of the primary color blue (CIEx=0.131 and CIEy=0.046) as defined by the ITU-R Recommendation BT.2020 (Rec. 2020) and thus is suited for the use in Ultra High Definition (UHD) displays, e.g., UHD-TVs. Accordingly, a further aspect of the present disclosure relates to an OLED including at least one compound according to the present disclosure, whose emission exhibits a CIEx color coordinate of between 0.02 and 0.30, between 0.03 and 0.25, between 0.05 and 0.20 or between 0.08 and 0.18 or between 0.10 and 0.15 and/or a CIEy color coordinate of between 0.00 and 0.45, between 0.01 and 0.30, between 0.02 and 0.20 or between 0.03 and 0.15 or between 0.04 and 0.10.
A further embodiment relates to an OLED including at least one compound according to the present disclosure and exhibits an external quantum efficiency at 1000 cd/m2 of more than 8%, of more than 10%, of more than 13%, of more than 15% or more than 20% and/or exhibits an emission maximum 420 and 500 nm, between 430 and 490 nm, between 440 and 480 nm, or between 450 and 470 nm or still and/or exhibits an LT80 value at 500 cd/m2 of more than 100 h, more than 200 h, more than 400 h, more than 750 h or more than 1000 h.
A green emitter has an emission maximum of below 560 nm, below 550 nm, below 545 nm or below 540 nm. It may be above 500 nm, above 510 nm, above 515 nm or above 520 nm.
A green emitter material may have an emission maximum between 500 and 560 nm, between 510 and 550 nm, or between 520 and 540 nm.
In a further embodiment of the disclosure, the composition has a photoluminescence quantum yield (PLQY) of more than 20%, more than 30%, more than 35%, more than 40%, more than 45%, more than 50%, more than 55%, more than 60% or more than 70% at room temperature.
An embodiment relates to an OLED including at least one compound according to the present disclosure and that emits light at a distinct color point. In some embodiments, the OLED emits light with a narrow emission band (a small full width at half maximum (FWHM)). In an embodiment, the OLED including at least one compound according to the disclosure emits light with an FWHM of the main emission peak of less than 0.30 eV, less than 25 eV, less than 0.20 eV, less than 0.1 eV, or less than 0.17 eV.
In accordance with the disclosure, the optoelectronic devices including at least one compound according to the present disclosure can for example be employed in displays, as light sources in lighting applications and as light sources in medical and/or cosmetic applications (for example light therapy).
Combination of the Compounds According to the Disclosure with Further Materials
It should be readily recognizable to those skilled in the art upon reviewing this disclosure that any layer within an optoelectronic device (herein, for example, an OLED), and for example, the light-emitting layer (EML), may be composed of a single material or a combination of different materials.
For example, the person skilled in the art should understand upon reviewing this disclosure that an EML may be composed of a single material that is capable of emitting light when a voltage (and electrical current) is applied to said device. However, the skilled artisan should also understand upon reviewing this disclosure that it may be beneficial to combine different materials in an EML of an optoelectronic device (herein, for example, an OLED), for example, one or more host material(s) (in other words: matrix material(s); herein designated host material(s) HB when included in an optoelectronic device that includes at least one compound according to the disclosure) and one or more dopant materials out of which at least one is emissive (e.g., an emitter material) when applying a voltage and electrical current to the device.
In an embodiment of the use of a compound according to the disclosure in an optoelectronic device, said optoelectronic device includes at least one compound according to the disclosure in an EML or in a layer that is directly adjacent to an EML or in more than one of these layers.
In an embodiment of the use of a compound according to the disclosure in an optoelectronic device, said optoelectronic device is an OLED and includes at least one compound according to the disclosure in an EML or in a layer that is directly adjacent to an EML or in more than one of these layers.
In an embodiment of the use of a compound according to the disclosure in an optoelectronic device, said optoelectronic device is an OLED and includes at least one compound according to the disclosure in an EML.
In one embodiment relating to the optoelectronic device, for example, the OLED, including at least one compound according to the disclosure, the at least one, for example, each, compound according to the disclosure is used as emitter material in a light-emitting layer EML, which is to say that it emits light when a voltage (and electrical current) is applied to said device.
As should be readily recognizable to the person skilled in the art upon reviewing this disclosure, light emission from emitter materials (e.g., emissive dopants), for example in organic light-emitting diodes (OLEDs), may include fluorescence from excited singlet states (typically the lowermost excited singlet state S1) and phosphorescence from excited triplet states (typically the lowermost excited triplet state T1).
A fluorescence emitter F is capable of emitting light at room temperature (e.g., (approximately) 20° C.) upon electronic excitation (for example in an optoelectronic device), wherein the emissive excited state is a singlet state. Fluorescence emitters usually display prompt (e.g., direct) fluorescence on a timescale of nanoseconds, when the initial electronic excitation (for example by electron hole recombination) affords an excited singlet state of the emitter.
In the context of the disclosure, a delayed fluorescence material is a material that is capable of reaching an excited singlet state (for example, the lowermost excited singlet state S1) by means of reverse intersystem crossing (RISC; in other words: up intersystem crossing or inverse intersystem crossing) from an excited triplet state (typically from the lowermost excited triplet state T1) and that is furthermore capable of emitting light when returning from the so-reached excited singlet state (typically S1) to its electronic ground state. The fluorescence emission observed after RISC from an excited triplet state (e.g., T1) to the emissive excited singlet state (typically S1) occurs on a timescale (e.g., in the range of microseconds) that is slower than the timescale on which direct (e.g., prompt) fluorescence occurs (e.g., in the range of nanoseconds) and is thus referred to as delayed fluorescence (DF). When RISC from an excited triplet state (e.g., from T1) to an excited singlet state (e.g., to S1), occurs through thermal activation, and if the so populated excited singlet state emits light (delayed fluorescence emission), the process is referred to as thermally activated delayed fluorescence (TADF). Accordingly, a TADF material is a material that is capable of emitting thermally activated delayed fluorescence (TADF) as explained above. It should be readily recognizable to the person skilled in the art that, when the energy difference ΔEST between the lowermost excited singlet state energy level E(S1E) and the lowermost excited triplet state energy level E(T1E) of a fluorescence emitter F is reduced, population of the lowermost excited singlet state from the lowermost excited triplet state by means of RISC may occur with high efficiency. Thus, it should be readily recognizable to those skilled in the art that a TADF material may have a small ΔEST value (vide infra). As should be readily recognizable to the person skilled in the art, a TADF material may not just be a material that is on its own capable of RISC from an excited triplet state to an excited singlet state with subsequent emission of TADF as laid out above. It should be readily recognizable to those skilled in the art that a TADF material may in fact also be an exciplex that is formed from two kinds of materials, for example, from two host materials HB, or from a p-host material HP and an n-host material HN (vide infra).
The occurrence of (thermally activated) delayed fluorescence may for example be analyzed based on the decay curve obtained from time-resolved (e.g., transient) photoluminescence (PL) measurements. For this purpose, a spin-coated film of the respective emitter (e.g., the assumed TADF material) in poly(methyl methacrylate) (PMMA) with 1 to 10% by weight, or 10% by weight of the respective emitter may be used as sample. The analysis may for example be performed using an FS5 fluorescence spectrometer from Edinburgh instruments. The sample PMMA film may be placed in a cuvette and kept under nitrogen atmosphere during the measurement. Data acquisition may be performed using the well-established technique of time correlated single photon counting (TCSPC, vide infra). To gather the full decay dynamics over several orders of magnitude in time and signal intensity, measurements in four time windows (200 ns, 1 μs, and 20 μs, and a longer measurement spanning >80 μs) may be carried out and combined (vide infra).
TADF materials may fulfill the following two conditions regarding the aforementioned full decay dynamics:
The ratio of delayed and prompt fluorescence may be expressed in form of a so-called n-value that may be calculated by the integration of respective photoluminescence decays in time according to the following equation:
In the context of the present disclosure, a TADF material may exhibit an n-value (ratio of delayed to prompt fluorescence) larger than 0.05 (n>0.05), larger than 0.1 (n>0.1), larger than 0.15 (n>0.15), larger than 0.2 (n>0.20), or larger than 0.25 (n>0.25).
In the context of the present disclosure, a TADF material EB is characterized by exhibiting a ΔEST value, which corresponds to the energy difference between the lowermost excited singlet state energy level E(S1E) and the lowermost excited triplet state energy level E(T1E), of less than 0.4 eV, of less than 0.3 eV, of less than 0.2 eV, of less than 0.1 eV, or of less than 0.05 eV. The means of determining the ΔEST value of TADF materials EB are further laid out in a below section of this text.
One approach for the design of TADF materials in general is to covalently attach one or more (electron) donor moieties on which the HOMO is distributed and one or more (electron) acceptor moieties on which the LUMO is distributed to the same bridge, herein referred to as linker group. A TADF material EB may, for example, also include two or three linker groups which are bonded to the same acceptor moiety and additional donor and acceptor moieties may be bonded to each of these two or three linker groups.
One or more donor moieties and one or more acceptor moieties may also be bonded directly to each other (without the presence of a linker group).
Example donor moieties are derivatives of diphenyl amine, indole, carbazole, acridine, phenoxazine, and related structures. In some embodiments, aliphatic, aromatic or heteroaromatic ring systems may be fused to the aforementioned donor motifs to arrive at for example indolocarbazoles.
Benzene-, biphenyl-, and to some extend also terphenyl-derivatives are common linker groups.
Nitrile groups are common acceptor moieties in TADF materials and examples thereof include:
Nitrogen-heterocycles such as triazine-, pyrimidine-, triazole-, oxadiazole-, thiadiazole-, heptazine-, 1,4-diazatriphenylene-, benzothiazole-, benzoxazole-, quinoxaline-, and diazafluorene-derivatives are also examples acceptor moieties used for the construction of TADF molecules. Examples of TADF molecules including for example a triazine acceptor include PIC-TRZ (7,7′-(6-([1,1′-biphenyl]-4-yl)-1,3,5-triazine-2,4-diyl)bis(5-phenyl-5,7-dihydroindolo[2,3-b]carbazole)), mBFCzTrz (5-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5H-benzofuro[3,2-c]carbazole), and DCzTrz (9,9′-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)-1,3-phenylene)bis(9H-carbazole)).
Another group of TADF materials includes diaryl ketones such as benzophenone or (heteroaryl)aryl ketones such as 4-benzoylpyridine, 9,10-anthraquinone, 9H-xanthen-9-one, and derivatives thereof as acceptor moieties to which the donor moieties (usually carbazolyl substituents) are bonded. Examples of such TADF molecules include BPBCz (bis(4-(9′-phenyl-9H,9′H-[3,3′-bicarbazol]-9-yl)phenyl)methanone), mDCBP ((3,5-di(9H-carbazol-9-yl)phenyl)(pyridin-4-yl)methanone), AQ-DTBu-Cz (2,6-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)anthracene-9,10-dione), and MCz-XT (3-(1,3,6,8-tetramethyl-9H-carbazol-9-yl)-9H-xanthen-9-one), respectively.
Sulfoxides, for example, diphenyl sulfoxides, are also suitable as acceptor moieties for the construction of TADF materials and examples include 4-PC-DPS (9-phenyl-3-(4-(phenylsulfonyl)phenyl)-9H-carbazole), DitBu-DPS (9,9′-(sulfonylbis(4,1-phenylene))bis(9H-carbazole)), and TXO-PhCz (2-(9-phenyl-9H-carbazol-3-yl)-9H-thioxanthen-9-one 10,10-dioxide).
It is understood that a fluorescence emitter F may also display TADF as defined herein and even be a TADF material EB as defined herein. In consequence, a small FWHM emitter SB as defined herein may or may not also be a TADF material EB as defined herein.
Phosphorescence, e.g., light emission from excited triplet states (e.g., from the lowermost excited triplet state T1) is a spin-forbidden process. As should be readily recognizable to the person skilled in the art, phosphorescence may be facilitated (enhanced) by exploiting the (intramolecular) spin-orbit interaction (so called (internal) heavy atom effect). A phosphorescence material PB in the context of the disclosure is a phosphorescence emitter capable of emitting phosphorescence at room temperature (e.g., at approximately 20° C.).
Herein, in some embodiments, a phosphorescence material PB includes at least one atom of an element having a standard atomic weight larger than the standard atomic weight of calcium (Ca). In some embodiments, a phosphorescence material PB in the context of the disclosure includes a transition metal atom, for example, a transition metal atom of an element having a standard atomic weight larger than the standard atomic weight of zinc (Zn). The transition metal atom included in the phosphorescence material PB may be present in any oxidation state (and may also be present as ion of the respective element).
It should be readily recognizable to those skilled in the art that phosphorescence materials PB used in optoelectronic devices are oftentimes complexes of Ir, Pd, Pt, Au, Os, Eu, Ru, Re, Ag and Cu, in the context of this disclosure, for example, of Ir, Pt, and Pd, or of Ir and Pt. The skilled artisan should readily recognize which materials are suitable as phosphorescence materials PB in optoelectronic devices and how to synthesize them. Furthermore, the skilled artisan should readily recognize the design principles of phosphorescent complexes for use as phosphorescence materials in optoelectronic devices and how to tune the emission of the complexes by means of structural variations.
The skilled artisan should readily recognize which materials are suitable as phosphorescence materials PB to be used in optoelectronic devices and how to synthesize them. In this regard, the skilled artisan should readily recognize the design principles of phosphorescent complexes for use as phosphorescence materials PB in optoelectronic devices and how to tune the emission of the complexes by means of structural variations.
Examples of phosphorescence materials PB that may be used alongside the compounds according to the present disclosure (for example in form of a composition or in an EML of an optoelectronic device, vide infra) are disclosed in the state of the art. For example, the following metal complexes are phosphorescence materials PB that may be used alongside the compounds according to the present disclosure:
A small full width at half maximum (FWHM) emitter SB in the context of the disclosure is any emitter (e.g., emitter material) that has an emission spectrum, which exhibits an FWHM of less than or equal to 0.35 eV (≤0.35 eV), of less than or equal to 0.30 eV (≤0.30 eV), or of less than or equal to 0.25 eV (≤0.25 eV). Unless stated otherwise, this is judged based on an emission spectrum of the respective emitter at room temperature (e.g., (approximately) 20° C.), for example, measured with 1 to 5% by weight, or with 2% by weight, of the emitter in poly(methyl methacrylate) PMMA or mCBP. In some embodiments, emission spectra of small FWHM emitters SB may be measured in a solution, for example, with 0.001 to 0.2 mg/mL of the emitter SB in dichloromethane or toluene at room temperature (e.g., (approximately) 20° C.).
A small FWHM emitter SB may be a fluorescence emitter F, a phosphorescence emitter (for example a phosphorescence material PB) and/or a TADF emitter (for example a TADF material EB). For TADF materials EB and for phosphorescence materials PB as laid out above, the emission spectrum is recorded at room temperature (e.g., approximately 20° C.) from a spin-coated film of the respective material in poly(methyl methacrylate) PMMA, with 10% by weight of the respective molecule of the disclosure, EB or PB.
As should be readily recognizable to the person skilled in the art, the full width at half maximum (FWHM) of an emitter (for example a small FWHM emitter SB) is readily determined from the respective emission spectrum (fluorescence spectrum for fluorescence emitters and phosphorescence spectrum for phosphorescence emitters). All reported FWHM values may refer to the main emission peak (e.g., the peak with the highest intensity). The means of determining the FWHM (herein, for example, reported in electron volts, eV) should be readily recognizable to those skilled in the art. Given for example that the main emission peak of an emission spectrum reaches its half maximum emission (e.g., 50% of the maximum emission intensity) at the two wavelengths λ1 and λ2, both obtained in nanometers (nm) from the emission spectrum, the FWHM in electron volts (eV) is commonly (and herein) determined using the following equation:
In the context of the disclosure, a small FWHM emitter SB is an organic emitter, which, in the context of the disclosure, means that it does not contain any transition metals. In some embodiments, a small FWHM emitter SB in the context of the disclosure predominantly includes or consists of the elements hydrogen (H), carbon (C), nitrogen (N), and boron (B), but may for example also include oxygen (O), silicon (Si), fluorine (F), and bromine (Br).
Furthermore, in some embodiments, a small FWHM emitter SB in the context of the disclosure is a fluorescence emitter F that may or may not additionally exhibit TADF.
In some embodiments, a small FWHM emitter SB in the context of the disclosure fulfills at least one of the following requirements:
As should be readily recognizable to a person skilled in the art, a host material HB of an EML may transport electrons or positive charges through said EML and may also transfer excitation energy to the at least one emitter material doped in the host material(s) HB. The skilled artisan should understand that a host material HB included in an EML of an optoelectronic device (e.g. an OLED) may not be significantly involved in light emission from said device upon applying a voltage and electrical current. The person skilled in the art should readily recognize that any host material HB may be a p-host HP exhibiting high hole mobility, an n-host HN exhibiting high electron mobility, or a bipolar host material HBP exhibiting both, high hole mobility and high electron mobility.
As should be readily recognizable to person skilled in the art, an EML may also include a so-called mixed-host system with at least one p-host HP and one n-host HN. In some embodiments, the EML may include exactly one emitter material according to the disclosure and a mixed-host system including T2T (2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine) as n-host HN and a host selected from CBP, mCP, mCBP, 4,6-diphenyl-2-(3-(triphenylsilyl)phenyl)-1,3,5-triazine, 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzothiophen-2-yl)phenyl]-9H-carbazole, 9-[3,5-bis(2-dibenzofuranyl)phenyl]-9H-carbazole and 9-[3,5-bis(2-dibenzothiophenyl)phenyl]-9H-carbazole as p-host HP.
An EML may include a so-called mixed-host system with at least one p-host HP and one n-host HN, wherein the n-host HN includes groups derived from pyridine, pyrimidine, benzopyrimidine, 1,3,5-triazine, 1,2,4-triazine, and 1,2,3-triazine, while the p-host HP includes groups derived from indole, isoindole, and/or, for example, carbazole.
The person skilled in the art should readily recognizable which materials are suitable host materials for use in optoelectronic devices. It is understood that any suitable host materials that are used in the state of the art may be suitable host materials HB in the context of the disclosure.
Examples of materials HB that are p-host materials HP in the context of the disclosure are listed below:
Examples of materials HB that are n-host materials HN in the context of the disclosure are listed below:
The person skilled in the art should understand that any suitable materials that are included in the same layer, for example, in the same EML, but also materials that are in adjacent layers and get in close proximity at the interface between these adjacent layers, may together form an exciplex. The person skilled in the art should readily recognize how to choose pairs of materials, for example, pairs of a p-host HP and an n-host HN, which form an exciplex and the selection criteria for the two components of said pair of materials, including HOMO- and/or LUMO-energy level requirements. This is to say that, in case exciplex formation may be aspired, the highest occupied molecular orbital (HOMO) of the one component, e.g., the p-host material HP, may be at least 0.20 eV higher in energy than the HOMO of the other component, e.g. the n-host material HN, and the lowest unoccupied molecular orbital (LUMO) of the one component, e.g. the p-host material HP, may be at least 0.20 eV higher in energy than the LUMO of the other component, e.g. the n-host material HN. It should be readily recognizable to those skilled in the art that, if present in an EML of an optoelectronic device, for example, an OILED, an exciplex may have the function of an emitter material and emit light when a voltage and electrical current are applied to said device. In some embodiments, an exciplex may also be non-emissive and may for example transfer excitation energy to an emitter material, if included in an EML of an optoelectronic device.
In some embodiments, triplet-triplet annihilation (TTA) materials can be used as host materials HB. The TTA material enables triplet-triplet annihilation. Triplet-triplet annihilation may result in a photon up-conversion. Accordingly, two, three or even more photons may facilitate photon up-conversion from the lowermost excited triplet state (T1TTA) to the first excited singlet state S1TTA of the TTA material HTTA In an embodiment, two photons facilitate photon up-conversion from T1TTA to S1TTA Triplet-triplet annihilation may thus be a process that through a number of energy transfer steps, may combine two (or optionally more than two) low frequency photons into one photon of higher frequency.
Optionally, the TTA material may include an absorbing moiety, the sensitizer moiety, and an emitting moiety (or annihilator moiety). In this context, an emitter moiety may, for example, be a polycyclic aromatic moiety such as, benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, azulene. In an embodiment, the polycyclic aromatic moiety includes an anthracene moiety or a derivative thereof. A sensitizer moiety and an emitting moiety may be located in two different chemical compounds (e.g., separated chemical entities) or may be both moieties embraced by one chemical compound.
According to the disclosure, a triplet-triplet annihilation (TTA) material converts energy from first excited triplet states T1N to first excited singlet states S1N by triplet-triplet annihilation.
According to the present disclosure, a TTA material is characterized in that it exhibits triplet-triplet annihilation from the lowermost excited triplet state (T1N) resulting in a triplet-triplet annihilated first excited singlet state S1N, having an energy of up to two times the energy of T1N
In one embodiment of the present disclosure, a TTA material is characterized in that it exhibits triplet-triplet annihilation from T1N resulting in S1N, having an energy of 1.01 to 2fold, 1.1 to 1.9fold, 1.2 to 1.5fold, 1.4 to 1.6fold, or 1.5 to 2fold times the energy of T1N
As used herein, the terms “TTA material” and “TTA compound” may be understood interchangeably.
Example “TTA materials” can be found in the state of the art related to blue fluorescent OLEDs, as described by Kondakov (Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2015, 373:20140321). Such blue fluorescent OLEDs employ aromatic hydrocarbons such as anthracene derivatives as the main component (host) in the EML.
In an embodiment, the TTA material enables sensitized triplet-triplet annihilation. Optionally, the TTA material may include one or more polycyclic aromatic structures. In an embodiment, the TTA material includes at least one polycyclic aromatic structure and at least one further aromatic residue.
In an embodiment, the TTA material bears larger singlet-triplet energy splitting, e.g., an energy difference between its first excited singlet state S1N and its lowermost excited triplet state T1N of at least 1.1 fold, at least 1.2fold, at least 1.3fold, at least 1.5fold and, for example, not more than 2fold.
In an embodiment of the disclosure, the TTA material HTTA is an anthracene derivative.
In one embodiment, the TTA material HTTA is an anthracene derivate of the following Formula 4:
In one embodiment, the TTA material HTTA is an anthracene derivate of the following Formula 4, wherein
In one embodiment, HTTA is an anthracene derivate of the following Formula 4, wherein at least one of A1 is hydrogen. In one embodiment, HTTA is an anthracene derivate of the following Formula 4, wherein at least two of A1 are hydrogen. In one embodiment, HTTA is an anthracene derivate of the following Formula 4, wherein at least three of A1 are hydrogen. In one embodiment, HTTA is an anthracene derivate of the following Formula 4, wherein all of A1 are each hydrogen.
In one embodiment, HTTA is an anthracene derivate of the following Formula 4, wherein one of Ar is a residue selected from the group consisting of phenyl, naphthyl, phenanthryl, pyrenyl, triphenylenyl, dibenzoanthracenyl, fluorenyl, benzofluorenyl, anthracenyl, phenanthrenyl, benzonaphthofuranyl, benzonaphthothiopehnyl, dibenzofuranyl, dibenzothiophenyl,
In one embodiment, HTTA is an anthracene derivate of the following Formula 4, wherein both Ar are residues each independently from each other selected from the group consisting of phenyl, naphthyl, phenanthryl, pyrenyl, triphenylenyl, dibenzoanthracenyl, fluorenyl, benzofluorenyl, anthracenyl, phenanthrenyl, benzonaphthofuranyl, benzonaphthothiopehnyl, dibenzofuranyl, dibenzothiophenyl,
which may be each optionally substituted with one or more residues selected from the group consisting of C6-C60-aryl, C3-C57-heteroaryl, halogen, and C1-C40-(hetero)alkyl.
One aspect of the disclosure relates to a composition including at least a compound according to the disclosure. One aspect of the disclosure relates to the use of this composition in optoelectronic devices, for example OLEDs, for example, in an EML of said devices.
In the following, when describing the aforementioned composition, reference is in some cases made to the content of certain materials in the respective compositions in form of percentages. It is to be noted that, unless stated otherwise for specific embodiments, all percentages refer to weight percentages, which has the same meaning as percent by weight or % by weight ((weight/weight), (w/w), wt. %). It is understood that, when for example stating that the content of one or more compound according to the disclosure in a specific composition is exemplarily 30%, this is to mean that the total weight of the one or more compound according to the disclosure (e.g., of all of these molecules combined) is 30% by weight, e.g., accounts for 30% of the total weight of the respective composition. It is understood that, whenever a composition is specified by providing the content of its components in % by weight, the total content of all components adds up to 100% by weight (e.g., the total weight of the composition).
When in the following describing the embodiments of the disclosure relating to a composition including at least one compound according to the disclosure, reference will be made to energy transfer processes that may take place between components within these compositions when using said compositions in an optoelectronic device, for example, in an EML of an optoelectronic device, for example, in an EML of an OLED. The person skilled in the art should understand that such excitation energy transfer processes may enhance the emission efficiency when using the composition in an EML of an optoelectronic device.
When describing compositions including at least one compound according to the present disclosure, it will also be pointed out that certain materials “differ” from other materials. This is to mean the materials that “differ” from each other do not have the same chemical structure.
In one embodiment, the composition includes or consists of:
In one embodiment, the composition includes or consists of:
In one embodiment, the composition includes or consists of:
In one embodiment, the composition includes or consists of:
In a further aspect, the disclosure relates to an optoelectronic device including an compound or a composition of the type (or kind) described here, for example, in the form of a device selected from the group consisting of organic light-emitting diode (OLED), light-emitting electrochemical cell, OLED sensor, for example, gas and vapour sensors not hermetically externally shielded, organic diode, organic solar cell, organic transistor, organic field-effect transistor, organic laser and down-conversion element.
In an embodiment, the optoelectronic device is a device selected from the group consisting of an organic light emitting diode (OLED), a light emitting electrochemical cell (LEC), and a light-emitting transistor.
In one embodiment of the optoelectronic device of the disclosure, the compound according to the disclosure E is used as emission material in a light-emitting layer EML.
In one embodiment of the optoelectronic device of the disclosure, the light-emitting layer EML consists of the composition according to the disclosure described here.
When the optoelectronic device is an OLED, it may, for example, have the following layer structure:
Furthermore, the optoelectronic device may, in one embodiment, include one or more protective layers protecting the device from damaging exposure to harmful species in the environment including, for example, moisture, vapor and/or gases.
In one embodiment of the disclosure, the optoelectronic device is an OLED, with the following inverted layer structure:
In one embodiment of the disclosure, the optoelectronic device is an OLED, which may have a stacked architecture. In this architecture, contrary to other arrangements in which the OLEDs are placed side by side, the individual units are stacked on top of each other. Blended light may be generated with OLEDs exhibiting a stacked architecture, for example, white light may be generated by stacking blue, green and red OLEDs. Furthermore, the OLED exhibiting a stacked architecture may include a charge generation layer (CGL), which is typically located between two OLED subunits and may include or consist of a n-doped and p-doped layer with the n-doped layer of one CGL being located closer to the anode layer.
In one embodiment of the disclosure, the optoelectronic device is an OLED, which includes two or more emission layers between anode and cathode. In some embodiments, this so-called tandem OLED includes three emission layers, wherein one emission layer emits red light, one emission layer emits green light and one emission layer emits blue light, and optionally may include further layers such as charge generation layers, blocking or transporting layers between the individual emission layers. In a further embodiment, the emission layers are adjacently stacked. In a further embodiment, the tandem OLED includes a charge generation layer between each two emission layers. In some embodiments, adjacent emission layers or emission layers separated by a charge generation layer may be merged.
The substrate may be formed by any suitable material or composition of materials. In some embodiments, glass slides are used as substrates. In some embodiments, thin metal layers (e.g., copper, gold, silver or aluminum films) and/or plastic films and/or slides may be used. This may allow for a higher degree of flexibility.
The anode layer A is mostly composed of materials allowing to obtain an (essentially) transparent film. As at least one of both electrodes should be (essentially) transparent in order to allow light emission from the OLED, either the anode layer A or the cathode layer C is transparent. In some embodiments, the anode layer A includes a large content or even consists of transparent conductive oxides (TCOs). Such anode layer A may, for example, include indium tin oxide, aluminum zinc oxide, fluorine doped tin oxide, indium zinc oxide, PbO, SnO, zirconium oxide, molybdenum oxide, vanadium oxide, tungsten oxide, graphite, doped S1, doped Ge, doped GaAs, doped polyaniline, doped polypyrrole and/or doped polythiophene.
The anode layer A (essentially) may consist of indium tin oxide (ITO) (e.g., (InO3)0.9(SnO2)0.1). The roughness of the anode layer A caused by the transparent conductive oxides (TCOs) may be compensated by using a hole injection layer (HIL). Further, the HIL may facilitate the injection of quasi charge carriers (e.g., holes) in that the transport of the quasi charge carriers from the TCO to the hole transport layer (HTL) is facilitated. The hole injection layer (HIL) may include poly-3,4-ethylendioxy thiophene (PEDOT), polystyrene sulfonate (PSS), MoO2, V2O5, CuPC or CuI, for example, a mixture of PEDOT and PSS. The hole injection layer (HIL) may also prevent or reduce the diffusion of metals from the anode layer A into the hole transport layer (HTL). The HIL may, for example, include PEDOT:PSS (poly-3,4-ethylendioxy thiophene: polystyrene sulfonate), PEDOT (poly-3,4-ethylendioxy thiophene), mMTDATA (4,4′,4″-tris[phenyl(m-tolyl)amino]triphenylamine), Spiro-TAD (2,2′,7,7′-tetrakis(n,n-diphenylamino)-9,9′-spirobifluorene), DNTPD (N1,N1′-(biphenyl-4,4′-diyl)bis(N1-phenyl-N4,N4-di-m-tolylbenzene-1,4-diamine), NPB (N,N′-nis-(1-naphthalenyl)-N,N′-bis-phenyl-(1,1′-biphenyl)-4,4′-diamine), NPNPB (N,N′-diphenyl-N,N′-di-[4-(N,N-diphenyl-amino)phenyl]benzidine), MeO-TPD (N,N,N′,N′-tetrakis(4-methoxyphenyl)benzidine), HAT-CN (1,4,5,8,9,11-hexaazatriphenylen-hexacarbonitrile) and/or Spiro-NPD (N,N′-diphenyl-N,N′-bis-(1-naphthyl)-9,9′-spirobifluorene-2,7-diamine).
Adjacent to the anode layer A or the hole injection layer (HIL), a hole transport layer (HTL) may be located. Herein, any hole transport compound may be used. For example, electron-rich heteroaromatic compounds such as triarylamines and/or carbazoles may be used as hole transport compound. The HTL may decrease the energy barrier between the anode layer A and the light-emitting layer EML. The hole transport layer (HTL) may also be an electron blocking layer (EBL). In some embodiments, hole transport compounds bear comparably high energy levels of their triplet states T1. For example, the hole transport layer (HTL) may include a star-shaped heterocycle such as tris(4-carbazoyl-9-ylphenyl)amine (TCTA), poly-TPD (poly(4-butylphenyl-diphenyl-amine)), [alpha]-NPD (poly(4-butylphenyl-diphenyl-amine)), TAPC (4,4′-cyclohexyliden-bis[N,N-bis(4-methylphenyl)benzenamine]), 2-TNATA (4,4′,4″-tris[2-naphthyl(phenyl)amino]triphenylamine), Spiro-TAD, DNTPD, NPB, NPNPB, MeO-TPD, HAT-CN and/or TrisPcz (9,9′-diphenyl-6-(9-phenyl-9H-carbazol-3-yl)-9H,9′H-3,3′-bicarbazole). In some embodiments, the HTL may include a p-doped layer, which may be composed of an inorganic or organic dopant in an organic hole-transporting matrix. Transition metal oxides as vanadium oxide, molybdenum oxide or tungsten oxide may, for example, be used as inorganic dopant. Tetrafluorotetracyanoquinodimethane (F4-TCNQ), copper-pentafluorobenzoate (Cu(I)pFBz) or transition metal complexes may, for example, be used as organic dopant.
The EBL may, for example, include mCP (1,3-bis(carbazol-9-yl)benzene), TCTA, 2-TNATA, mCBP (3,3-di(9H-carbazol-9-yl)biphenyl), tris-Pcz, CzSi (9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole), and/or DCB (N,N′-dicarbazolyl-1,4-dimethylbenzene).
Adjacent to the hole transport layer (HTL), the light-emitting layer EML may be located. The light-emitting layer EML includes at least one light emitting molecule. In some embodiments, the EML includes at least one light emitting compound according to the disclosure E. In one embodiment, the light-emitting layer includes only the compound according to the disclosure. In some embodiments, the EML additionally includes one or more host materials H. For example, the host material H is selected from CBP (4,4′-Bis-(N-carbazolyl)-biphenyl), mCP, mCBP Sif87 (dibenzo[b,d]thiophen-2-yltriphenylsilane), CzSi, Sif88 (dibenzo[b,d]thiophen-2-yl)diphenylsilane), DPEPO (bis[2-(diphenylphosphino)phenyl]ether oxide), 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzothiophen-2-yl)phenyl]-9H-carbazole, 9-[3,5-bis(2-dibenzofuranyl)phenyl]-9H-carbazole, 9-[3,5-bis(2-dibenzothiophenyl)phenyl]-9H-carbazole, T2T (2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine), T3T (2,4,6-tris(triphenyl-3-yl)-1,3,5-triazine) and/or TST (2,4,6-tris(9,9′-spirobifluorene-2-yl)-1,3,5-triazine). The host material H typically should be selected to exhibit first triplet (T1) and first singlet (S1) energy levels, which are energetically higher than the first triplet (T1) and first singlet (S1) energy levels of the organic molecule.
In one embodiment of the disclosure, the EML includes a so-called mixed-host system with at least one hole-dominant host and one electron-dominant host. In a particular embodiment, the EML includes exactly one light emitting compound according to the disclosure and a mixed-host system including T2T as electron-dominant host and a host selected from CBP, mCP, mCBP, 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzothiophen-2-yl)phenyl]-9H-carbazole, 9-[3,5-bis(2-dibenzofuranyl)phenyl]-9H-carbazole and 9-[3,5-bis(2-dibenzothiophenyl)phenyl]-9H-carbazole as hole-dominant host. In a further embodiment the EML includes 50 to 80% by weight, or 60 to 75% by weight of a host selected from CBP, mCP, mCBP, 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzothiophen-2-yl)phenyl]-9H-carbazole, 9-[3,5-bis(2-dibenzofuranyl)phenyl]-9H-carbazole and 9-[3,5-bis(2-dibenzothiophenyl)phenyl]-9H-carbazole; 10 to 45% by weight, or 15 to 30% by weight of T2T and 5 to 40% by weight, or 10 to 30% by weight of light emitting molecule according to the disclosure.
Adjacent to the light-emitting layer EML, an electron transport layer (ETL) may be located. Herein, any suitable electron transporter may be used. Exemplarily, electron-poor compounds such as, e.g., benzimidazoles, pyridines, triazoles, oxadiazoles (e.g., 1,3,4-oxadiazole), phosphinoxides and sulfone, may be used. An electron transporter may also be a star-shaped heterocycle such as 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi). The ETL may include NBphen (2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline), Alq3 (Aluminum-tris(8-hydroxyquinoline)), TSPO1 (diphenyl-4-triphenylsilylphenyl-phosphinoxide), BPyTP2 (2,7-di(2,2′-bipyridin-5-yl)triphenyle), Sif87 (dibenzo[b,d]thiophen-2-yltriphenylsilane), Sif88 (dibenzo[b,d]thiophen-2-yl)diphenylsilane), BmPyPhB (1,3-bis[3,5-di(pyridin-3-yl)phenyl]benzene) and/or BTB (4,4′-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1′-biphenyl). Optionally, the ETL may be doped with materials as Liq. The transport layer (ETL) may also block holes or a holeblocking layer (HBL) may be introduced.
The HBL may, for example, include BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline=Bathocuproine), BAlq (bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum), NBphen (2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline), Alq3 (Aluminum-tris(8-hydroxyquinoline)), TSPO1 (diphenyl-4-triphenylsilylphenyl-phosphinoxide), T2T (2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine), T3T (2,4,6-tris(triphenyl-3-yl)-1,3,5-triazine), TST (2,4,6-tris(9,9′-spirobifluorene-2-yl)-1,3,5-triazine), and/or TCB/TCP (1,3,5-tris(N-carbazolyl)benzol/1,3,5-tris(carbazol)-9-yl)benzene).
Adjacent to the electron transport layer (ETL), a cathode layer C may be located. The cathode layer C may, for example, include or may consist of a metal (e.g., Al, Au, Ag, Pt, Cu, Zn, Ni, Fe, Pb, LiF, Ca, Ba, Mg, In, W, or Pd) or a metal alloy. For practical reasons, the cathode layer may also consist of (essentially) intransparent metals such as Mg, Ca or Al. Alternatively or additionally, the cathode layer C may also include graphite and/or carbon nanotubes (CNTs). In some embodiments, the cathode layer C may also consist of nanoscalic silver wires.
An OLED may further, optionally, include a protection layer between the electron transport layer (ETL) and the cathode layer C (which may be designated as electron injection layer (EIL)). This layer may include lithium fluoride, cesium fluoride, silver, Liq (8-hydroxyquinolinolatolithium), Li2O, BaF2, MgO and/or NaF.
Optionally, the electron transport layer (ETL) and/or a hole blocking layer (HBL) may also include one or more host compounds H.
In order to modify the emission spectrum and/or the absorption spectrum of the light-emitting layer EML further, the light-emitting layer EML may further include one or more further emitter molecules F. Such an emitter molecule F may be any suitable emitter molecule known in the art. In some embodiments, such an emitter molecule F is a molecule with a structure differing from the structure of the molecules according to the disclosure E. The emitter molecule F may optionally be a TADF emitter. In some embodiments, the emitter molecule F may optionally be a fluorescent and/or phosphorescent emitter molecule which is able to shift the emission spectrum and/or the absorption spectrum of the light-emitting layer EML. Exemplarily, the triplet and/or singlet excitons may be transferred from the compound according to the disclosure to the emitter molecule F before relaxing to the ground state S0 by emitting light typically red-shifted in comparison to the light emitted by a compound according to the disclosure. Optionally, the emitter molecule F may also provoke two-photon effects (e.g., the absorption of two photons of half the energy of the absorption maximum).
Optionally, an optoelectronic device (e.g., an OLED) may, for example, be an essentially white optoelectronic device. For example, such a white optoelectronic device may include at least one (deep) blue emitter molecule and one or more emitter molecules emitting green and/or red light. Then, there may also optionally be energy transmittance between two or more molecules as described above.
As used herein, if not defined more specifically in the particular context, the designation of the colors of emitted and/or absorbed light is as follows:
With respect to emitter molecules, such colors refer to the emission maximum. Therefore, for example, a deep blue emitter has an emission maximum in the range of from >420 to 480 nm, a sky blue emitter has an emission maximum in the range of from >480 to 500 nm, a green emitter has an emission maximum in a range of from >500 to 560 nm, a red emitter has an emission maximum in a range of from >620 to 800 nm.
A deep blue emitter may have an emission maximum of below 480 nm, below 470 nm, below 465 nm or below 460 nm. It may be above 420 nm, above 430 nm, above 440 nm or above 450 nm.
A green emitter has an emission maximum of below 560 nm, below 550 nm, below 545 nm or below 540 nm. It may be above 500 nm, above 510 nm, above 515 nm or above 520 nm.
Accordingly, a further aspect of the present disclosure relates to an OLED, which exhibits an external quantum efficiency at 1000 cd/m2 of more than 8%, of more than 10%, of more than 13%, of more than 15% or more than 20% and/or exhibits an emission maximum between 420 nm and 500 nm, between 430 nm and 490 nm, between 440 nm and 480 nm, between 450 nm and 470 nm and/or exhibits a LT80 value at 500 cd/m2 of more than 100 h, more than 200 h, more than 400 h, more than 750 h or more than 1000 h. Accordingly, a further aspect of the present disclosure relates to an OLED, whose emission exhibits a CIEy color coordinate of less than 0.45, less than 0.30, less than 0.20 or less than 0.15 or even less than 0.10.
A further aspect of the present disclosure relates to an OLED, which emits light with CIEx and CIEy color coordinates close to the CIEx (=0.170) and CIEy (=0.797) color coordinates of the primary color green (CIEx=0.170 and CIEy=0.797) as defined by ITU-R Recommendation BT.2020 (Rec. 2020) and thus is suited for the use in Ultra High Definition (UHD) displays, e.g. UHD-TVs. In this context, the term “close to” refers to the ranges of CIEx and CIEy coordinates provided at the end of this paragraph. In commercial applications, for example, top-emitting (top-electrode is transparent) devices are used, whereas test devices as used throughout the present application represent bottom-emitting devices (bottom-electrode and substrate are transparent). Accordingly, a further aspect of the present disclosure relates to an OLED, whose emission exhibits a CIEx color coordinate of between 0.15 and 0.45 between 0.15 and 0.35, between 0.15 and 0.30 or between 0.15 and 0.25 or between 0.15 and 0.20 and/or a CIEy color coordinate of between 0.60 and 0.92, between 0.65 and 0.90, between 0.70 and 0.88 or between 0.75 and 0.86 or between 0.79 and 0.84.
Accordingly, a further aspect of the present disclosure relates to an OLED, which exhibits an external quantum efficiency at 14500 cd/m2 of more than 8%, of more than 10%, of more than 13%, of more than 15% or of more than 17%, or of more than 20% and/or exhibits an emission maximum between 485 nm and 560 nm, between 500 nm and 560 nm, between 510 nm and 550 nm, or between 515 nm and 540 nm and/or exhibits a LT97 value at 14500 cd/m2 of more than 100 h, more than 250 h, more than 50 h, more preferably more than 750 h or more than 1000 h.
A further aspect of the present disclosure relates to an OLED, which emits light at a distinct color point. According to the present disclosure, the OLED emits light with a narrow emission band (small full width at half maximum (FWHM)). In one aspect, the OLED according to the disclosure emits light with a FWHM of the main emission peak of less than 0.25 eV, less than 0.20 eV, less than 0.17 eV, less than 0.15 eV or less than 0.13 eV.
In a further embodiment of the disclosure, the composition has a photoluminescence quantum yield (PLQY) of more than 20%, more than 30%, more than 35%, more than 40%, more than 45%, more than 50%, more than 55%, more than 60% or more than 70% at room temperature.
In a further aspect, the disclosure relates to a method for producing an optoelectronic component. In this case a compound of the disclosure is used.
In a further aspect, the disclosure relates to a method for generating light at a wavelength range from 510 nm to 550 nm, or from 520 nm to 540 nm, including the steps of:
The optoelectronic device, for example, the OLED according to the present disclosure can be fabricated by any means of vapor deposition and/or liquid processing. Accordingly, at least one layer is
The methods used to fabricate the optoelectronic device, in particular the OLED according to the present disclosure may be any suitable ones generally used in the art. The different layers are individually and successively deposited on a suitable substrate by means of subsequent deposition processes. The individual layers may be deposited using the same or differing deposition methods.
Vapor deposition processes, for example, include thermal (co)evaporation, chemical vapor deposition and physical vapor deposition. For active matrix OLED display, an AMOLED backplane is used as substrate. The individual layer may be processed from solutions or dispersions employing adequate solvents. Solution deposition process, for example, include spin coating, dip coating and jet printing.
Liquid processing may optionally be carried out in an inert atmosphere (e.g., in a nitrogen atmosphere) and the solvent may be completely or partially removed by means any suitable processes generally used in the state of the art.
For Y1═Y2, and A1=A2
The coupling groups CG1 and CG2 are chosen as a reaction pair to introduce the heterocycle of E2 at the position of CG1. In some embodiments, a so-called Suzuki coupling reaction is used. Here, either CG1 is chosen from Cl, Br or I, and CG2 is a boronic acid group or a boronic acid ester group, for example, a boronic acid pinacol ester group, or CG1 is a boronic acid group or a boronic acid ester group, for example, a boronic acid pinacol ester group, and CG2 is chosen from Cl, Br or I.
The person skilled in the art should be aware that in order to introduce different heterocycles via the coupling reactions of E1 with E2 and E1-2 with E2-2.
E1 (1.00 equivalents, e.g. 6-bromo-N-pyridin-2-ylpyridin-2-amine, CAS201049-89-0), E2 (1.00 equivalents; e.g. CAS: 1510810-80-6), Tris(dibenzylideneacetone)dipalladium(O) (0.01 equivalents; CAS: 51364-51-3), X-Phos (0.04 equivalents; CAS: 564483-18-7) and potassium acetate (KOAc; CAS: 127-08-2, 1.50 equivalents) are stirred under nitrogen atmosphere in dry dioxane at 90° C. for 24 h. After cooling down to room temperature (rt) the reaction mixture is extracted between ethyl acetate and water. The organic phases were collected, dried over MgSO4, treated with Celite and Charcoal, stirred for 1 h and filtered. The combined organic layers concentrated under reduced pressure. The crude is purified by column chromatography or recrystallization and E3 is obtained as a solid.
E1-2 (1.00 equivalents, e.g. 2,6-Dibromopyridine, CAS: 626-05-1), E2-2 (2.10 equivalents; e.g. 1-(tetramethyl-1,3,2-dioxaborolan-2-yl)-9H-carbazole CAS: 1219637-88-3), Tris(dibenzylideneacetone)dipalladium(0) (0.01 equivalents; CAS: 51364-51-3), S-Phos (0.04 equivalents; CAS: 657408-07-6) and potassium acetate (KOAc; CAS: 127-08-2, 3.00 equivalents) are stirred under nitrogen atmosphere in dry dioxane at 100° C. for 24 h. After cooling down to room temperature (rt) the reaction mixture is extracted between ethyl acetate and water. The organic phases were collected, dried over MgSO4, treated with Celite and Charcoal, stirred for 1 h and filtered. The combined organic layers concentrated under reduced pressure. The crude is purified by column chromatography or recrystallization and E3 is obtained as a solid.
E3 (1.00 equivalents), and N,N-Diisopropylethylamine (1.00 equivalents; CAS: 7087-68-5) are stirred under nitrogen atmosphere in dry toluene and the solution was cooled to 0° C. Sodium hydride (1.20 equivalents; CAS: 7646-69-7) was added dropwise and stirred under nitrogen atmosphere for 30 minutes. E4 (1.00 equivalents; e.g., Boron trifluoride etherate, CAS: 109-63-7) was added dropwise and the reaction mixture was heated to 110° C. for 2 h.
The reaction mixture was cooled down to room temperature and then extracted with ethyl acetate and brine/water. The combined organic layers were dried over MgSO4 and the combined organic layers concentrated under reduced pressure. The crude is purified by column chromatography or recrystallization and P1 is obtained as a solid.
Cyclic voltammograms are measured from solutions having concentration of 10−3 mol/L of the compounds in dichloromethane or a suitable solvent and a suitable supporting electrolyte (e.g. 0.1 mol/L of tetrabutylammonium hexafluorophosphate). The measurements are conducted at room temperature under nitrogen atmosphere with a three-electrode assembly (Working and counter electrodes: Pt wire, reference electrode: Pt wire) and calibrated using FeCp2/FeCp2+ as internal standard. The HOMO data was corrected using ferrocene as internal standard against a saturated calomel electrode (SCE).
Molecular structures are optimized employing the BP86 functional and the resolution of identity approach (RI). Excitation energies are calculated using the (BP86) optimized structures employing Time-Dependent DFT (TD-DFT) methods. Orbital and excited state energies are calculated with the B3LYP functional. Def2-SVP basis sets (and a m4-grid for numerical integration are used. The Turbomole program package is used for all calculations.
The sample concentration is 10 mg/ml, dissolved in a suitable solvent. Program: 1) 3 s at 400 U/min; 20 s at 1000 U/min at 1000 Upm/s. 3) 10 s at 4000 U/min at 1000 Upm/s. After coating, the films are tried at 70° C. for 1 min.
Steady-state emission spectroscopy is measured by a Horiba Scientific, Modell FluoroMax-4 equipped with a 150 W Xenon-Arc lamp, excitation- and emissions monochromators and a Hamamatsu R928 photomultiplier and a time-correlated single-photon counting option. Emissions and excitation spectra are corrected using standard correction fits.
Excited state lifetimes are determined employing the same system using the TCSPC method with FM-2013 equipment and a Horiba Yvon TCSPC hub.
For photoluminescence quantum yield (PLQY) measurements an Absolute PL Quantum Yield Measurement C9920-03G system (Hamamatsu Photonics) is used. Quantum yields and CIE coordinates are determined using the software U6039-05 version 3.6.0.
Emission maxima are given in nm, quantum yields 0 in % and CIE coordinates as x,y values.
PLQY is determined using the following protocol:
Quantum yields are measured, for sample, of solutions or films under nitrogen atmosphere. The yield is calculated using the equation:
Optoelectronic devices, such as OLED devices including compounds according to the disclosure can be produced via vacuum-deposition methods. If a layer contains more than one compound, the weight-percentage of one or more compounds is given in %. The total weight-percentage values amount to 100%, thus if a value is not given, the fraction of this compound equals to the difference between the given values and 100%.
The not fully optimized OLEDs are characterized using standard methods and measuring electroluminescence spectra, the external quantum efficiency (in %) in dependency on the intensity, calculated using the light detected by the photodiode, and the current. The OLED device lifetime is extracted from the change of the luminance during operation at constant current density. The LT50 value corresponds to the time, where the measured luminance decreased to 50% of the initial luminance, analogously LT80 corresponds to the time point, at which the measured luminance decreased to 80% of the initial luminance, LT 95 to the time point, at which the measured luminance decreased to 95% of the initial luminance etc.
Accelerated lifetime measurements are performed (e.g. applying increased current densities). For example, LT80 values at 500 cd/m2 are determined using the following equation:
The values correspond to the average of several pixels (typically two to eight), the standard deviation between these pixels is given.
HPLC-MS analysis is performed on an HPLC by Agilent (1100 series) with MS-detector (Thermo LTQ XL).
An example, HPLC method is as follows: a reverse phase column 4.6 mm×150 mm, particle size 3.5 μm from Agilent (ZORBAX Eclipse Plus 95 Å C18, 4.6×150 mm, 3.5 μm HPLC column) is used in the HPLC. The HPLC-MS measurements are performed at room temperature (rt) following gradients represented by Table 1:
using the following solvent mixtures represented by Table 2:
An injection volume of 5 μL from a solution with a concentration of 0.5 mg/mL of the analyte is taken for the measurements.
Ionization of the probe is performed using an APCI (atmospheric pressure chemical ionization) source either in positive (APCI+) or negative (APCI−) ionization mode.
(complex) with ligand L1:
Example 1 was synthesized according to:
AAV1-1 (95% yield), wherein 6-bromo-N-pyridin-2-ylpyridin-2-amine:
(CAS 201049-89-0) was used as material E-1 and
(CAS 1510810-80-6) was used as material E-2; and
AAV2 (11% yield), wherein boron trifluoride etherate (CAS 109-63-7) was used as material E-3.
MS (LC-MS, APCI ion source): 477 m/z at rt: 1.12 min.
The emission maximum of example 1 (0.1 mg/mL in toluene) is at 479 nm, the CIEx coordinate is 0.19 and the CIEy coordinate is 0.45. The photoluminescence quantum yield (PLQY) is 65%.
complex) with Iigand L2:
Example 2 was synthesized according to:
AAV1-2 (81% yield), wherein 2,6-Dibromopyridine (CAS 626-05-1) was used as material E1-2 and 1-(tetramethyl-1,3,2-dioxaborolan-2-yl)-9H-carbazole (CAS 1219637-88-3) was used as material E2-2,
AAV2 (33% yield), wherein Boron trifluoride etherate (CAS 109-63-7) was used as material E-3.
MS (LC-MS, APCI ion source): 439 m/z at rt: 2.90 min.
The emission maximum of example 2 (0.001 mg/mL in toluene) is at 529 nm, the CIEx coordinate is 0.33 and the CIEy coordinate is 0.60. The photoluminescence quantum yield (PLQY) is 59%.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21216895.9 | Dec 2021 | EP | regional |
The present application is a U.S. National Phase Patent Application of International Patent Application Number PCT/KR2022/020889, filed on Dec. 20, 2022, which claims priority to and the benefit of European Patent Application Number 21216895.9, filed on Dec. 22, 2021, the entire content of which is hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2022/020889 | 12/20/2022 | WO |
