Patent Application
20250051381
The present disclosure generally relates to organometallic compounds and formulations and their various uses including as emitters in devices such as organic light emitting diodes and related electronic devices.
Opto-electronic devices that make use of organic materials are becoming increasingly desirable for various reasons. Many of the materials used to make such devices are relatively inexpensive, so organic opto-electronic devices have the potential for cost advantages over inorganic devices. In addition, the inherent properties of organic materials, such as their flexibility, may make them well suited for particular applications such as fabrication on a flexible substrate. Examples of organic opto-electronic devices include organic light emitting diodes/devices (OLEDs), organic phototransistors, organic photovoltaic cells, and organic photodetectors. For OLEDs, the organic materials may have performance advantages over conventional materials.
OLEDs make use of thin organic films that emit light when voltage is applied across the device. OLEDs are becoming an increasingly interesting technology for use in applications such as flat panel displays, illumination, and backlighting.
One application for phosphorescent emissive molecules is a full color display. Industry standards for such a display call for pixels adapted to emit particular colors, referred to as “saturated” colors. In particular, these standards call for saturated red, green, and blue pixels. Alternatively, the OLED can be designed to emit white light.
In conventional liquid crystal displays emission from a white backlight is filtered using absorption filters to produce red, green and blue emission. The same technique can also be used with OLEDs. The white OLED can be either a single emissive layer (EML) device or a stack structure. Color may be measured using CIE coordinates, which are well known to the art.
In one aspect, the present disclosure provides a compound comprising at least one monoanionic bidentate ligand LA represented by Formula I or a tautomer thereof:
In another aspect, the present disclosure provides a formulation comprising a compound comprising at least one monoanionic bidentate ligand LA represented by Formula I as described herein.
In yet another aspect, the present disclosure provides an OLED having an organic layer comprising a compound comprising at least one monoanionic bidentate ligand LA represented by Formula I as described herein.
In yet another aspect, the present disclosure provides a consumer product comprising an OLED with an organic layer comprising a compound comprising at least one monoanionic bidentate ligand LA represented by Formula I as described herein.
Unless otherwise specified, the below terms used herein are defined as follows:
As used herein, the term “organic” includes polymeric materials as well as small molecule organic materials that may be used to fabricate organic opto-electronic devices. “Small molecule” refers to any organic material that is not a polymer, and “small molecules” may actually be quite large. Small molecules may include repeat units in some circumstances. For example, using a long chain alkyl group as a substituent does not remove a molecule from the “small molecule” class. Small molecules may also be incorporated into polymers, for example as a pendent group on a polymer backbone or as a part of the backbone. Small molecules may also serve as the core moiety of a dendrimer, which consists of a series of chemical shells built on the core moiety. The core moiety of a dendrimer may be a fluorescent or phosphorescent small molecule emitter. A dendrimer may be a “small molecule,” and it is believed that all dendrimers currently used in the field of OLEDs are small molecules.
As used herein, “top” means furthest away from the substrate, while “bottom” means closest to the substrate. Where a first layer is described as “disposed over” a second layer, the first layer is disposed further away from substrate. There may be other layers between the first and second layer, unless it is specified that the first layer is “in contact with” the second layer. For example, a cathode may be described as “disposed over” an anode, even though there are various organic layers in between.
As used herein, “solution processable” means capable of being dissolved, dispersed, or transported in and/or deposited from a liquid medium, either in solution or suspension form.
A ligand may be referred to as “photoactive” when it is believed that the ligand directly contributes to the photoactive properties of an emissive material. A ligand may be referred to as “ancillary” when it is believed that the ligand does not contribute to the photoactive properties of an emissive material, although an ancillary ligand may alter the properties of a photoactive ligand.
As used herein, and as would be generally understood by one skilled in the art, a first “Highest Occupied Molecular Orbital” (HOMO) or “Lowest Unoccupied Molecular Orbital” (LUMO) energy level is “greater than” or “higher than” a second HOMO or LUMO energy level if the first energy level is closer to the vacuum energy level.
Since ionization potentials (IP) are measured as a negative energy relative to a vacuum level, a higher HOMO energy level corresponds to an IP having a smaller absolute value (an IP that is less negative). Similarly, a higher LUMO energy level corresponds to an electron affinity (EA) having a smaller absolute value (an EA that is less negative). On a conventional energy level diagram, with the vacuum level at the top, the LUMO energy level of a material is higher than the HOMO energy level of the same material. A “higher” HOMO or LUMO energy level appears closer to the top of such a diagram than a “lower” HOMO or LUMO energy level.
As used herein, and as would be generally understood by one skilled in the art, a first work function is “greater than” or “higher than” a second work function if the first work function has a higher absolute value.
Because work functions are generally measured as negative numbers relative to vacuum level, this means that a “higher” work function is more negative. On a conventional energy level diagram, with the vacuum level at the top, a “higher” work function is illustrated as further away from the vacuum level in the downward direction. Thus, the definitions of HOMO and LUMO energy levels follow a different convention than work functions.
The terms “halo,” “halogen,” and “halide” are used interchangeably and refer to fluorine, chlorine, bromine, and iodine.
The term “acyl” refers to a substituted carbonyl radical (C(O)—Rs).
The term “ester” refers to a substituted oxycarbonyl (—O—C(O)—Rs or —C(O)—O—Rs) radical.
The term “ether” refers to an —ORs radical.
The terms “sulfanyl” or “thio-ether” are used interchangeably and refer to a —SRs radical.
The term “selenyl” refers to a —SeRs radical.
The term “sulfinyl” refers to a —S(O)—Rs radical.
The term “sulfonyl” refers to a —SO2—Rs radical.
The term “phosphino” refers to a —P(Rs)3 radical, wherein each R, can be same or different.
The term “silyl” refers to a —Si(R3)3 radical, wherein each R, can be same or different.
The term “germyl” refers to a —Ge(Rs)3 radical, wherein each R, can be same or different.
The term “boryl” refers to a —B(Rs)2 radical or its Lewis adduct —B(Rs)3 radical, wherein R, can be same or different.
In each of the above, R, can be hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, and combination thereof. Preferred R, is selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and combination thereof.
The term “alkyl” refers to and includes both straight and branched chain alkyl radicals. Preferred alkyl groups are those containing from one to fifteen carbon atoms and includes methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, and the like. Additionally, the alkyl group may be optionally substituted.
The term “cycloalkyl” refers to and includes monocyclic, polycyclic, and spiro alkyl radicals. Preferred cycloalkyl groups are those containing 3 to 12 ring carbon atoms and includes cyclopropyl, cyclopentyl, cyclohexyl, bicyclo[3.1.1]heptyl, spiro[4.5]decyl, spiro[5.5]undecyl, adamantyl, and the like. Additionally, the cycloalkyl group may be optionally substituted.
The terms “heteroalkyl” or “heterocycloalkyl” refer to an alkyl or a cycloalkyl radical, respectively, having at least one carbon atom replaced by a heteroatom. Optionally the at least one heteroatom is selected from O, S, N, P, B, Si and Se, preferably, O, S or N. Additionally, the heteroalkyl or heterocycloalkyl group may be optionally substituted.
The term “alkenyl” refers to and includes both straight and branched chain alkene radicals. Alkenyl groups are essentially alkyl groups that include at least one carbon-carbon double bond in the alkyl chain. Cycloalkenyl groups are essentially cycloalkyl groups that include at least one carbon-carbon double bond in the cycloalkyl ring.
The term “heteroalkenyl” as used herein refers to an alkenyl radical having at least one carbon atom replaced by a heteroatom. Optionally the at least one heteroatom is selected from O, S, N, P, B, Si, and Se, preferably, O, S, or N. Preferred alkenyl, cycloalkenyl, or heteroalkenyl groups are those containing two to fifteen carbon atoms. Additionally, the alkenyl, cycloalkenyl, or heteroalkenyl group may be optionally substituted.
The term “alkynyl” refers to and includes both straight and branched chain alkyne radicals. Alkynyl groups are essentially alkyl groups that include at least one carbon-carbon triple bond in the alkyl chain. Preferred alkynyl groups are those containing two to fifteen carbon atoms. Additionally, the alkynyl group may be optionally substituted.
The terms “aralkyl” or “arylalkyl” are used interchangeably and refer to an alkyl group that is substituted with an aryl group. Additionally, the aralkyl group may be optionally substituted.
The term “heterocyclic group” refers to and includes aromatic and non-aromatic cyclic radicals containing at least one heteroatom. Optionally the at least one heteroatom is selected from O, S, N, P, B, Si, and Se, preferably, O, S, or N. Hetero-aromatic cyclic radicals may be used interchangeably with heteroaryl. Preferred hetero-non-aromatic cyclic groups are those containing 3 to 7 ring atoms which includes at least one hetero atom, and includes cyclic amines such as morpholino, piperidino, pyrrolidino, and the like, and cyclic ethers/thio-ethers, such as tetrahydrofuran, tetrahydropyran, tetrahydrothiophene, and the like. Additionally, the heterocyclic group may be optionally substituted.
The term “aryl” refers to and includes both single-ring aromatic hydrocarbyl groups and polycyclic aromatic ring systems. The polycyclic rings may have two or more rings in which two carbons are common to two adjoining rings (the rings are “fused”) wherein at least one of the rings is an aromatic hydrocarbyl group, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryl, heterocycles, and/or heteroaryls. Preferred aryl groups are those containing six to thirty carbon atoms, preferably six to twenty carbon atoms, more preferably six to twelve carbon atoms. Especially preferred is an aryl group having six carbons, ten carbons or twelve carbons. Suitable aryl groups include phenyl, biphenyl, triphenyl, triphenylene, tetraphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene, preferably phenyl, biphenyl, triphenyl, triphenylene, fluorene, and naphthalene. Additionally, the aryl group may be optionally substituted.
The term “heteroaryl” refers to and includes both single-ring aromatic groups and polycyclic aromatic ring systems that include at least one heteroatom. The heteroatoms include, but are not limited to O, S, N, P, B, Si, and Se. In many instances, O, S, or N are the preferred heteroatoms. Hetero-single ring aromatic systems are preferably single rings with 5 or 6 ring atoms, and the ring can have from one to six heteroatoms. The hetero-polycyclic ring systems can have two or more rings in which two atoms are common to two adjoining rings (the rings are “fused”) wherein at least one of the rings is a heteroaryl, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryl, heterocycles, and/or heteroaryls. The hetero-polycyclic aromatic ring systems can have from one to six heteroatoms per ring of the polycyclic aromatic ring system. Preferred heteroaryl groups are those containing three to thirty carbon atoms, preferably three to twenty carbon atoms, more preferably three to twelve carbon atoms. Suitable heteroaryl groups include dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine, preferably dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocarbazole, imidazole, pyridine, triazine, benzimidazole, 1,2-azaborine, 1,3-azaborine, 1,4-azaborine, borazine, and aza-analogs thereof. Additionally, the heteroaryl group may be optionally substituted.
Of the aryl and heteroaryl groups listed above, the groups of triphenylene, naphthalene, anthracene, dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocarbazole, imidazole, pyridine, pyrazine, pyrimidine, triazine, and benzimidazole, and the respective aza-analogs of each thereof are of particular interest.
The terms alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aralkyl, heterocyclic group, aryl, and heteroaryl, as used herein, are independently unsubstituted, or independently substituted, with one or more general substituents.
In many instances, the General Substituents are selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, germyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, selenyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
In some instances, the Preferred General Substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, germyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof.
In some instances, the More Preferred General Substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, alkoxy, aryloxy, amino, silyl, aryl, heteroaryl, sulfanyl, and combinations thereof.
In yet other instances, the Most Preferred General Substituents are selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof.
The terms “substituted” and “substitution” refer to a substituent other than H that is bonded to the relevant position, e.g., a carbon or nitrogen. For example, when R1 represents mono-substitution, then one R1 must be other than H (i.e., a substitution). Similarly, when R1 represents di-substitution, then two of R1 must be other than H. Similarly, when R1 represents zero or no substitution, R1, for example, can be a hydrogen for available valencies of ring atoms, as in carbon atoms for benzene and the nitrogen atom in pyrrole, or simply represents nothing for ring atoms with fully filled valencies, e.g., the nitrogen atom in pyridine. The maximum number of substitutions possible in a ring structure will depend on the total number of available valencies in the ring atoms.
As used herein, “combinations thereof” indicates that one or more members of the applicable list are combined to form a known or chemically stable arrangement that one of ordinary skill in the art can envision from the applicable list. For example, an alkyl and deuterium can be combined to form a partial or fully deuterated alkyl group; a halogen and alkyl can be combined to form a halogenated alkyl substituent; and a halogen, alkyl, and aryl can be combined to form a halogenated arylalkyl. In one instance, the term substitution includes a combination of two to four of the listed groups. In another instance, the term substitution includes a combination of two to three groups. In yet another instance, the term substitution includes a combination of two groups. Preferred combinations of substituent groups are those that contain up to fifty atoms that are not hydrogen or deuterium, or those which include up to forty atoms that are not hydrogen or deuterium, or those that include up to thirty atoms that are not hydrogen or deuterium. In many instances, a preferred combination of substituent groups will include up to twenty atoms that are not hydrogen or deuterium.
The “aza” designation in the fragments described herein, i.e. aza-dibenzofuran, aza-dibenzothiophene, etc. means that one or more of the C—H groups in the respective aromatic ring can be replaced by a nitrogen atom, for example, and without any limitation, azatriphenylene encompasses both dibenzo[fh]quinoxaline and dibenzo[fh]quinoline. One of ordinary skill in the art can readily envision other nitrogen analogs of the aza-derivatives described above, and all such analogs are intended to be encompassed by the terms as set forth herein.
As used herein, “deuterium” refers to an isotope of hydrogen. Deuterated compounds can be readily prepared using methods known in the art. For example, U.S. Pat. No. 8,557,400, Patent Pub. No. WO 2006/095951, and U.S. Pat. Application Pub. No. US 2011/0037057, which are hereby incorporated by reference in their entireties, describe the making of deuterium-substituted organometallic complexes. Further reference is made to Ming Yan, et al., Tetrahedron 2015, 71, 1425-30 and Atzrodt et al., Angew. Chem. Int. Ed. (Reviews) 2007, 46, 7744-65, which are incorporated by reference in their entireties, describe the deuteration of the methylene hydrogens in benzyl amines and efficient pathways to replace aromatic ring hydrogens with deuterium, respectively.
It is to be 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 were a fragment (e.g. phenyl, phenylene, naphthyl, dibenzofuryl) or as if it were the whole molecule (e.g. benzene, naphthalene, dibenzofuran). As used herein, these different ways of designating a substituent or attached fragment are considered to be equivalent.
In some instance, a pair of adjacent substituents can be optionally joined or fused into a ring. The preferred ring is a five, six, or seven-membered carbocyclic or heterocyclic ring, includes both instances where the portion of the ring formed by the pair of substituents is saturated and where the portion of the ring formed by the pair of substituents is unsaturated. As used herein, “adjacent” means that the two substituents involved can be on the same ring next to each other, or on two neighboring rings having the two closest available substitutable positions, such as 2, 2′ positions in a biphenyl, or 1, 8 position in a naphthalene, as long as they can form a stable fused ring system.
In one aspect, the present disclosure provides a compound comprising at least one monoanionic bidentate ligand LA represented by Formula I or a tautomer thereof;
In one embodiment, one of R1 and R2 is not hydrogen; and one of R3 and R4 is not hydrogen.
In one embodiment, X represents O or S. In one embodiment, X represents NRN, wherein RN represents aryl or substituted aryl.
In one embodiment, Z represents CRZ.
In one embodiment, R1 and R2 each represent hydrogen or deuterium; and one of R3 and R4 is not hydrogen.
In one embodiment, the ligand LA is represented by one of the following structures:
In one embodiment, the compound has a formula of M(LA)p(LB)q(LC)r wherein LB and LC are each a bidentate ligand; and wherein p is 1, 2, or 3; q is 0, 1, or 2; r is 0, 1, or 2; and p+q+r is the oxidation state of the metal M.
In one embodiment, the compound has a formula selected from the group consisting of Ir(LA)3, Ir(LA)(LB)2, Ir(LA)2(LB), Ir(LA)2(LC), and Ir(LA)(LB)(LC); and wherein LA, LB, and LC are different from each other.
In some embodiments, LB is a substituted or unsubstituted phenylpyridine, and LC is a substituted or unsubstituted acetylacetonate.
In one embodiment, LB and LC are each independently selected from the group consisting of:
In one embodiment, LB and LC are each independently selected from the group consisting of:
In some embodiments, the compound comprising a ligand LA of Formula I described herein can be at least 30% deuterated, at least 40% deuterated, at least 50% deuterated, at least 60% deuterated, at least 70% deuterated, at least 80% deuterated, at least 90% deuterated, at least 95% deuterated, at least 99% deuterated, or 100% deuterated. As used herein, percent deuteration has its ordinary meaning and includes the percent of possible hydrogen atoms (e.g., positions that are hydrogen or deuterium) that are replaced by deuterium atoms.
In some embodiments of heteroleptic compound having the formula of M(LA)p(LB)q(LC)r as defined above, the ligand LA has a first substituent RI, where the first substituent RI has a first atom a-I that is the farthest away from the metal M among all atoms in the ligand LA. Additionally, the ligand LB, if present, has a second substituent RII, where the second substituent RII has a first atom a-II that is the farthest away from the metal M among all atoms in the ligand LB. Furthermore, the ligand LC, if present, has a third substituent RIII, where the third substituent RIII has a first atom a-III that is the farthest away from the metal M among all atoms in the ligand LC.
In such heteroleptic compounds, vectors VD1, VD2, and VD3 can be defined that are defined as follows. VD1 represents the direction from the metal M to the first atom a-I and the vector VD1 has a value D1 that represents the straight line distance between the metal M and the first atom a-I in the first substituent R. VD2 represents the direction from the metal M to the first atom a-II and the vector VD2 has a value D2 that represents the straight line distance between the metal M and the first atom a-II in the second substituent RII. VD3 represents the direction from the metal M to the first atom a-III and the vector VD3 has a value D3 that represents the straight line distance between the metal M and the first atom a-Ill in the third substituent RIII.
In such heteroleptic compounds, a sphere having a radius r is defined whose center is the metal M and the radius r is the smallest radius that will allow the sphere to enclose all atoms in the compound that are not part of the substituents RI, RII and RIII; and where at least one of D1, D2, and D3 is greater than the radius r by at least 1.5 Å. In some embodiments, at least one of D1, D2, and D3 is greater than the radius r by at least 2.9, 3.0, 4.3, 4.4, 5.2, 5.9, 7.3, 8.8, 10.3, 13.1, 17.6, or 19.1 Å.
In some embodiments of such heteroleptic compound, the compound has a transition dipole moment axis and angles are defined between the transition dipole moment axis and the vectors VD1, VD2, and VD3, where at least one of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 is less than 40°. In some embodiments, at least one of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 is less than 30°. In some embodiments, at least one of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 is less than 20°. In some embodiments, at least one of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 is less than 15°. In some embodiments, at least one of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 is less than 10°. In some embodiments, at least two of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than 20°. In some embodiments, at least two of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than 15°. In some embodiments, at least two of the angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than 10°.
In some embodiments, all three angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than 20°. In some embodiments, all three angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than 15°. In some embodiments, all three angles between the transition dipole moment axis and the vectors VD1, VD2, and VD3 are less than 10°.
In some embodiments of such heteroleptic compounds, the compound has a vertical dipole ratio (VDR) of 0.33 or less. In some embodiments of such heteroleptic compounds, the compound has a VDR of 0.30 or less. In some embodiments of such heteroleptic compounds, the compound has a VDR of 0.25 or less. In some embodiments of such heteroleptic compounds, the compound has a VDR of 0.20 or less. In some embodiments of such heteroleptic compounds, the compound has a VDR of 0.15 or less.
One of ordinarily skill in the art would readily understand the meaning of the terms transition dipole moment axis of a compound and vertical dipole ratio of a compound. Nevertheless, the meaning of these terms can be found in U.S. Pat. No. 10,672,997 whose disclosure is incorporated herein by reference in its entirety. In U.S. Pat. No. 10,672,997, horizontal dipole ratio (HDR) of a compound, rather than VDR, is discussed. However, one skilled in the art readily understands that VDR=1−HDR.
In another aspect, the present disclosure also provides an OLED device comprising a first organic layer that contains a compound as disclosed in the above compounds section of the present disclosure.
In some embodiments, the OLED comprises: an anode; a cathode; and an organic layer disposed between the anode and the cathode, wherein the organic layer comprises a compound comprising at least one monoanionic bidentate ligand LA represented by Formula I or a tautomer thereof;
In some embodiments, the organic layer may be an emissive layer and the compound as described herein may be an emissive dopant or a non-emissive dopant.
In some embodiments, the emissive layer comprises one or more quantum dots.
In some embodiments, the organic layer may further comprise a host, wherein the host comprises a triphenylene containing benzo-fused thiophene or benzo-fused furan, wherein any substituent in the host is an unfused substituent independently selected from the group consisting of CnH2n+1, OCnH2n+1, OAr1, N(CnH2n+1)2, N(Ar1)(Ar2), CH═CH—CnH2n+1, C≡CCnH2n+1, Ar1, Ar1—Ar2, CnH2n—Ar1, or no substitution, wherein n is an integer from 1 to 10; and wherein Ar1 and Ar2 are independently selected from the group consisting of benzene, biphenyl, naphthalene, triphenylene, carbazole, and heteroaromatic analogs thereof.
In some embodiments, the organic layer may further comprise a host, wherein host comprises at least one chemical group selected from the group consisting of triphenylene, carbazole, indolocarbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, 5λ2-benzo[d]benzo[4,5]imidazo[3,2-a]imidazole, 5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracene, triazine, boryl, silyl, aza-triphenylene, aza-carbazole, aza-indolocarbazole, aza-dibenzothiophene, aza-dibenzofuran, aza-dibenzoselenophene, aza-5λ2-benzo[d]benzo[4,5]imidazo[3,2-a]imidazole, and aza-(5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracene).
In some embodiments, the host may be selected from the HOST Group consisting of:
and combinations thereof.
In some embodiments, the organic layer may further comprise a host, wherein the host comprises a metal complex.
In some embodiments, the emissive layer can comprise two hosts, a first host and a second host. In some embodiments, the first host is a hole transporting host, and the second host is an electron transporting host. In some embodiments, the first host and the second host can form an exciplex.
In some embodiments, the compound as described herein may be a sensitizer; wherein the device may further comprise an acceptor; and wherein the acceptor may be selected from the group consisting of fluorescent emitter, delayed fluorescence emitter, and combination thereof.
In yet another aspect, the OLED of the present disclosure may also comprise an emissive region containing a compound as disclosed in the above compounds section of the present disclosure.
In some embodiments, the emissive region can comprise a compound comprising at least one monoanionic bidentate ligand LA represented by Formula I or a tautomer thereof;
In some embodiments, at least one of the anode, the cathode, or a new layer disposed over the organic emissive layer functions as an enhancement layer. The enhancement layer comprises a plasmonic material exhibiting surface plasmon resonance that non-radiatively couples to the emitter material and transfers excited state energy from the emitter material to non-radiative mode of surface plasmon polariton. The enhancement layer is provided no more than a threshold distance away from the organic emissive layer, wherein the emitter material has a total non-radiative decay rate constant and a total radiative decay rate constant due to the presence of the enhancement layer and the threshold distance is where the total non-radiative decay rate constant is equal to the total radiative decay rate constant. In some embodiments, the OLED further comprises an outcoupling layer. In some embodiments, the outcoupling layer is disposed over the enhancement layer on the opposite side of the organic emissive layer. In some embodiments, the outcoupling layer is disposed on opposite side of the emissive layer from the enhancement layer but still outcouples energy from the surface plasmon mode of the enhancement layer. The outcoupling layer scatters the energy from the surface plasmon polaritons. In some embodiments this energy is scattered as photons to free space. In other embodiments, the energy is scattered from the surface plasmon mode into other modes of the device such as but not limited to the organic waveguide mode, the substrate mode, or another waveguiding mode. If energy is scattered to the non-free space mode of the OLED other outcoupling schemes could be incorporated to extract that energy to free space. In some embodiments, one or more intervening layer can be disposed between the enhancement layer and the outcoupling layer. The examples for interventing layer(s) can be dielectric materials, including organic, inorganic, perovskites, oxides, and may include stacks and/or mixtures of these materials.
The enhancement layer modifies the effective properties of the medium in which the emitter material resides resulting in any or all of the following: a decreased rate of emission, a modification of emission line-shape, a change in emission intensity with angle, a change in the stability of the emitter material, a change in the efficiency of the OLED, and reduced efficiency roll-off of the OLED device. Placement of the enhancement layer on the cathode side, anode side, or on both sides results in OLED devices which take advantage of any of the above-mentioned effects. In addition to the specific functional layers mentioned herein and illustrated in the various OLED examples shown in the figures, the OLEDs according to the present disclosure may include any of the other functional layers often found in OLEDs.
The enhancement layer can be comprised of plasmonic materials, optically active metamaterials, or hyperbolic metamaterials. As used herein, a plasmonic material is a material in which the real part of the dielectric constant crosses zero in the visible or ultraviolet region of the electromagnetic spectrum. In some embodiments, the plasmonic material includes at least one metal. In such embodiments the metal may include at least one of Ag, Al, Au, Ir, Pt, Ni, Cu, W, Ta, Fe, Cr, Mg, Ga, Rh, Ti, Ru, Pd, In, Bi, Ca alloys or mixtures of these materials, and stacks of these materials. In general, a metamaterial is a medium composed of different materials where the medium as a whole acts differently than the sum of its material parts. In particular, we define optically active metamaterials as materials which have both negative permittivity and negative permeability. Hyperbolic metamaterials, on the other hand, are anisotropic media in which the permittivity or permeability are of different sign for different spatial directions. Optically active metamaterials and hyperbolic metamaterials are strictly distinguished from many other photonic structures such as Distributed Bragg Reflectors (“DBRs”) in that the medium should appear uniform in the direction of propagation on the length scale of the wavelength of light. Using terminology that one skilled in the art can understand: the dielectric constant of the metamaterials in the direction of propagation can be described with the effective medium approximation. Plasmonic materials and metamaterials provide methods for controlling the propagation of light that can enhance OLED performance in a number of ways.
In some embodiments, the enhancement layer is provided as a planar layer. In other embodiments, the enhancement layer has wavelength-sized features that are arranged periodically, quasi-periodically, or randomly, or sub-wavelength-sized features that are arranged periodically, quasi-periodically, or randomly. In some embodiments, the wavelength-sized features and the sub-wavelength-sized features have sharp edges.
In some embodiments, the outcoupling layer has wavelength-sized features that are arranged periodically, quasi-periodically, or randomly, or sub-wavelength-sized features that are arranged periodically, quasi-periodically, or randomly. In some embodiments, the outcoupling layer may be composed of a plurality of nanoparticles and in other embodiments the outcoupling layer is composed of a plurality of nanoparticles disposed over a material. In these embodiments the outcoupling may be tunable by at least one of varying a size of the plurality of nanoparticles, varying a shape of the plurality of nanoparticles, changing a material of the plurality of nanoparticles, adjusting a thickness of the material, changing the refractive index of the material or an additional layer disposed on the plurality of nanoparticles, varying a thickness of the enhancement layer, and/or varying the material of the enhancement layer. The plurality of nanoparticles of the device may be formed from at least one of metal, dielectric material, semiconductor materials, an alloy of metal, a mixture of dielectric materials, a stack or layering of one or more materials, and/or a core of one type of material and that is coated with a shell of a different type of material. In some embodiments, the outcoupling layer is composed of at least metal nanoparticles wherein the metal is selected from the group consisting of Ag, Al, Au, Ir, Pt, Ni, Cu, W, Ta, Fe, Cr, Mg, Ga, Rh, Ti, Ru, Pd, In, Bi, Ca, alloys or mixtures of these materials, and stacks of these materials. The plurality of nanoparticles may have additional layer disposed over them. In some embodiments, the polarization of the emission can be tuned using the outcoupling layer. Varying the dimensionality and periodicity of the outcoupling layer can select a type of polarization that is preferentially outcoupled to air. In some embodiments the outcoupling layer also acts as an electrode of the device.
In yet another aspect, the present disclosure also provides a consumer product comprising an organic light-emitting device (OLED) having an anode; a cathode; and an organic layer disposed between the anode and the cathode, wherein the organic layer may comprise a compound as disclosed in the above compounds section of the present disclosure.
In some embodiments, the consumer product comprises an OLED having an anode; a cathode; and an organic layer disposed between the anode and the cathode, wherein the organic layer may comprise a compound comprising at least one monoanionic bidentate ligand LA represented by Formula I or a tautomer thereof as described herein.
In some embodiments, the consumer product can be one of a flat panel display, a computer monitor, a medical monitor, a television, a billboard, a light for interior or exterior illumination and/or signaling, a heads-up display, a fully or partially transparent display, a flexible display, a laser printer, a telephone, a cell phone, tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display that is less than 2 inches diagonal, a 3-D display, a virtual reality or augmented reality display, a vehicle, a video wall comprising multiple displays tiled together, a theater or stadium screen, a light therapy device, and a sign.
Generally, an OLED comprises at least one organic layer disposed between and electrically connected to an anode and a cathode. When a current is applied, the anode injects holes and the cathode injects electrons into the organic layer(s). The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and hole localize on the same molecule, an “exciton,” which is a localized electron-hole pair having an excited energy state, is formed. Light is emitted when the exciton relaxes via a photoemissive mechanism. In some cases, the exciton may be localized on an excimer or an exciplex. Non-radiative mechanisms, such as thermal relaxation, may also occur, but are generally considered undesirable.
Several OLED materials and configurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and 5,707,745, which are incorporated herein by reference in their entirety.
The initial OLEDs used emissive molecules that emitted light from their singlet states (“fluorescence”) as disclosed, for example, in U.S. Pat. No. 4,769,292, which is incorporated by reference in its entirety. Fluorescent emission generally occurs in a time frame of less than 10 nanoseconds.
More recently, OLEDs having emissive materials that emit light from triplet states (“phosphorescence”) have been demonstrated. Baldo et al., “Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices,” Nature, vol. 395, 151-154, 1998; (“Baldo-I”) and Baldo et al., “Very high-efficiency green organic light-emitting devices based on electrophosphorescence,” Appl. Phys. Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), are incorporated by reference in their entireties. Phosphorescence is described in more detail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporated by reference.
More examples for each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by reference in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of emissive and host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference in their entireties, disclose examples of cathodes including compound cathodes having a thin layer of metal such as Mg:Ag with an overlying transparent, electrically-conductive, sputter-deposited ITO layer. The theory and use of blocking layers is described in more detail in U.S. Pat. No. 6,097,147 and U.S. Patent Application Publication No. 2003/0230980, which are incorporated by reference in their entireties. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety. A description of protective layers may be found in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety.
The simple layered structure illustrated in
Structures and materials not specifically described may also be used, such as OLEDs comprised of polymeric materials (PLEDs) such as disclosed in U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated by reference in its entirety. By way of further example, OLEDs having a single organic layer may be used. OLEDs may be stacked, for example as described in U.S. Pat. No. 5,707,745 to Forrest et al, which is incorporated by reference in its entirety. The OLED structure may deviate from the simple layered structure illustrated in
Unless otherwise specified, any of the layers of the various embodiments may be deposited by any suitable method. For the organic layers, preferred methods include thermal evaporation, ink-jet, such as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, which are incorporated by reference in their entireties, organic vapor phase deposition (OVPD), such as described in U.S. Pat. No. 6,337,102 to Forrest et al., which is incorporated by reference in its entirety, and deposition by organic vapor jet printing (OVJP, also referred to as organic vapor jet deposition (OVJD)), such as described in U.S. Pat. No. 7,431,968, which is incorporated by reference in its entirety. Other suitable deposition methods include spin coating and other solution based processes. Solution based processes are preferably carried out in nitrogen or an inert atmosphere. For the other layers, preferred methods include thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819, which are incorporated by reference in their entireties, and patterning associated with some of the deposition methods such as ink-jet and organic vapor jet printing (OVJP). Other methods may also be used. The materials to be deposited may be modified to make them compatible with a particular deposition method. For example, substituents such as alkyl and aryl groups, branched or unbranched, and preferably containing at least 3 carbons, may be used in small molecules to enhance their ability to undergo solution processing. Substituents having 20 carbons or more may be used, and 3-20 carbons are a preferred range. Materials with asymmetric structures may have better solution processability than those having symmetric structures, because asymmetric materials may have a lower tendency to recrystallize. Dendrimer substituents may be used to enhance the ability of small molecules to undergo solution processing.
Devices fabricated in accordance with embodiments of the present disclosure may further optionally comprise a barrier layer. One purpose of the barrier layer is to protect the electrodes and organic layers from damaging exposure to harmful species in the environment including moisture, vapor and/or gases, etc. The barrier layer may be deposited over, under or next to a substrate, an electrode, or over any other parts of a device including an edge. The barrier layer may comprise a single layer, or multiple layers. The barrier layer may be formed by various known chemical vapor deposition techniques and may include compositions having a single phase as well as compositions having multiple phases. Any suitable material or combination of materials may be used for the barrier layer. The barrier layer may incorporate an inorganic or an organic compound or both. The preferred barrier layer comprises a mixture of a polymeric material and a non-polymeric material as described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos. PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporated by reference in their entireties. To be considered a “mixture”, the aforesaid polymeric and non-polymeric materials comprising the barrier layer should be deposited under the same reaction conditions and/or at the same time. The weight ratio of polymeric to non-polymeric material may be in the range of 95:5 to 5:95. The polymeric material and the non-polymeric material may be created from the same precursor material. In one example, the mixture of a polymeric material and a non-polymeric material consists essentially of polymeric silicon and inorganic silicon.
Devices fabricated in accordance with embodiments of the present disclosure can be incorporated into a wide variety of electronic component modules (or units) that can be incorporated into a variety of electronic products or intermediate components. Examples of such electronic products or intermediate components include display screens, lighting devices such as discrete light source devices or lighting panels, etc. that can be utilized by the end-user product manufacturers. Such electronic component modules can optionally include the driving electronics and/or power source(s). Devices fabricated in accordance with embodiments of the present disclosure can be incorporated into a wide variety of consumer products that have one or more of the electronic component modules (or units) incorporated therein. A consumer product comprising an OLED that includes the compound of the present disclosure in the organic layer in the OLED is disclosed. Such consumer products would include any kind of products that include one or more light source(s) and/or one or more of some type of visual displays. Some examples of such consumer products include flat panel displays, curved displays, computer monitors, medical monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads-up displays, fully or partially transparent displays, flexible displays, rollable displays, foldable displays, stretchable displays, laser printers, telephones, mobile phones, tablets, phablets, personal digital assistants (PDAs), wearable devices, laptop computers, digital cameras, camcorders, viewfinders, micro-displays (displays that are less than 2 inches diagonal), 3-D displays, virtual reality or augmented reality displays, vehicles, video walls comprising multiple displays tiled together, theater or stadium screen, a light therapy device, and a sign. Various control mechanisms may be used to control devices fabricated in accordance with the present disclosure, including passive matrix and active matrix. Many of the devices are intended for use in a temperature range comfortable to humans, such as 18 degrees C. to 30 degrees C., and more preferably at room temperature (20-25° C.), but could be used outside this temperature range, for example, from −40 degree C. to +80° C.
More details on OLEDs, and the definitions described above, can be found in U.S. Pat. No. 7,279,704, which is incorporated herein by reference in its entirety.
The materials and structures described herein may have applications in devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photodetectors may employ the materials and structures. More generally, organic devices, such as organic transistors, may employ the materials and structures.
In some embodiments, the OLED has one or more characteristics selected from the group consisting of being flexible, being rollable, being foldable, being stretchable, and being curved. In some embodiments, the OLED is transparent or semi-transparent. In some embodiments, the OLED further comprises a layer comprising carbon nanotubes.
In some embodiments, the OLED further comprises a layer comprising a delayed fluorescent emitter. In some embodiments, the OLED comprises a RGB pixel arrangement or white plus color filter pixel arrangement. In some embodiments, the OLED is a mobile device, a hand held device, or a wearable device. In some embodiments, the OLED is a display panel having less than 10 inch diagonal or 50 square inch area. In some embodiments, the OLED is a display panel having at least 10 inch diagonal or 50 square inch area. In some embodiments, the OLED is a lighting panel.
In some embodiments, the compound can be an emissive dopant. In some embodiments, the compound can produce emissions via phosphorescence, fluorescence, thermally activated delayed fluorescence, i.e., TADF (also referred to as E-type delayed fluorescence; see, e.g., U.S. application Ser. No. 15/700,352, which is hereby incorporated by reference in its entirety), triplet-triplet annihilation, or combinations of these processes. In some embodiments, the emissive dopant can be a racemic mixture, or can be enriched in one enantiomer. In some embodiments, the compound can be homoleptic (each ligand is the same). In some embodiments, the compound can be heteroleptic (at least one ligand is different from others). When there are more than one ligand coordinated to a metal, the ligands can all be the same in some embodiments. In some other embodiments, at least one ligand is different from the other ligands. In some embodiments, every ligand can be different from each other. This is also true in embodiments where a ligand being coordinated to a metal can be linked with other ligands being coordinated to that metal to form a tridentate, tetradentate, pentadentate, or hexadentate ligands. Thus, where the coordinating ligands are being linked together, all of the ligands can be the same in some embodiments, and at least one of the ligands being linked can be different from the other ligand(s) in some other embodiments.
In some embodiments, the compound can be used as a phosphorescent sensitizer in an OLED where one or multiple layers in the OLED contains an acceptor in the form of one or more fluorescent and/or delayed fluorescence emitters. In some embodiments, the compound can be used as one component of an exciplex to be used as a sensitizer. As a phosphorescent sensitizer, the compound must be capable of energy transfer to the acceptor and the acceptor will emit the energy or further transfer energy to a final emitter. The acceptor concentrations can range from 0.001% to 100%. The acceptor could be in either the same layer as the phosphorescent sensitizer or in one or more different layers. In some embodiments, the acceptor is a TADF emitter. In some embodiments, the acceptor is a fluorescent emitter. In some embodiments, the emission can arise from any or all of the sensitizer, acceptor, and final emitter.
According to another aspect, a formulation comprising the compound described herein is also disclosed.
The OLED disclosed herein can be incorporated into one or more of a consumer product, an electronic component module, and a lighting panel. The organic layer can be an emissive layer and the compound can be an emissive dopant in some embodiments, while the compound can be a non-emissive dopant in other embodiments.
In yet another aspect of the present disclosure, a formulation that comprises the novel compound disclosed herein is described. The formulation can include one or more components selected from the group consisting of a solvent, a host, a hole injection material, hole transport material, electron blocking material, hole blocking material, and an electron transport material, disclosed herein.
The present disclosure encompasses any chemical structure comprising the novel compound of the present disclosure, or a monovalent or polyvalent variant thereof. In other words, the inventive compound, or a monovalent or polyvalent variant thereof, can be a part of a larger chemical structure. Such chemical structure can be selected from the group consisting of a monomer, a polymer, a macromolecule, and a supramolecule (also known as supermolecule). As used herein, a “monovalent variant of a compound” refers to a moiety that is identical to the compound except that one hydrogen has been removed and replaced with a bond to the rest of the chemical structure. As used herein, a “polyvalent variant of a compound” refers to a moiety that is identical to the compound except that more than one hydrogen has been removed and replaced with a bond or bonds to the rest of the chemical structure. In the instance of a supramolecule, the inventive compound can also be incorporated into the supramolecule complex without covalent bonds.
The materials described herein as useful for a particular layer in an organic light emitting device may be used in combination with a wide variety of other materials present in the device. For example, emissive dopants disclosed herein may be used in conjunction with a wide variety of hosts, transport layers, blocking layers, injection layers, electrodes and other layers that may be present. The materials described or referred to below are non-limiting examples of materials that may be useful in combination with the compounds disclosed herein, and one of skill in the art can readily consult the literature to identify other materials that may be useful in combination.
A charge transport layer can be doped with conductivity dopants to substantially alter its density of charge carriers, which will in turn alter its conductivity. The conductivity is increased by generating charge carriers in the matrix material, and depending on the type of dopant, a change in the Fermi level of the semiconductor may also be achieved. Hole-transporting layer can be doped by p-type conductivity dopants and n-type conductivity dopants are used in the electron-transporting layer.
Non-limiting examples of the conductivity dopants that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: EP01617493, EP01968131, EP2020694, EP2684932, US20050139810, US20070160905, US20090167167, US2010288362, WO06081780, WO2009003455, WO2009008277, WO2009011327, WO2014009310, US2007252140, US2015060804, US20150123047, and US2012146012.
A hole injecting/transporting material to be used in the present disclosure is not particularly limited, and any compound may be used as long as the compound is typically used as a hole injecting/transporting material. Examples of the material include, but are not limited to: a phthalocyanine or porphyrin derivative; an aromatic amine derivative; an indolocarbazole derivative; a polymer containing fluorohydrocarbon; a polymer with conductivity dopants; a conducting polymer, such as PEDOT/PSS; a self-assembly monomer derived from compounds such as phosphonic acid and silane derivatives; a metal oxide derivative, such as MoOx; a p-type semiconducting organic compound, such as 1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and a cross-linkable compounds.
Examples of aromatic amine derivatives used in HIL or HTL include, but not limit to the following general structures:
Each of Ar1 to Ar9 is selected from the group consisting of aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene; the group consisting of aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and the group consisting of 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Each Ar may be unsubstituted or may be substituted by a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
In one aspect, Ar1 to Ar9 is independently selected from the group consisting of:
wherein k is an integer from 1 to 20; X101 to X108 is C (including CH) or N; Z101 is NAr1, O, or S; Ar1 has the same group defined above.
Examples of metal complexes used in HIL or HTL include, but are not limited to the following general formula:
wherein Met is a metal, which can have an atomic weight greater than 40; (Y101-Y102) is a bidentate ligand, Y101 and Y102 are independently selected from C, N, O, P, and S; L101 is an ancillary ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.
In one aspect, (Y101-Y102) is a 2-phenylpyridine derivative. In another aspect, (Y101-Y102) is a carbene ligand. In another aspect, Met is selected from Ir, Pt, Os, and Zn. In a further aspect, the metal complex has a smallest oxidation potential in solution vs. Fc+/Fc couple less than about 0.6 V.
Non-limiting examples of the HIL and HTL materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: CN102702075, DE102012005215, EP01624500, EP01698613, EP01806334, EP01930964, EP01972613, EP01997799, EP02011790, EP02055700, EP02055701, EP1725079, EP2085382, EP2660300, EP650955, JP07-073529, JP2005112765, JP2007091719, JP2008021687, JP2014-009196, KR20110088898, KR20130077473, TW201139402, U.S. Ser. No. 06/517,957, US20020158242, US20030162053, US20050123751, US20060182993, US20060240279, US20070145888, US20070181874, US20070278938, US20080014464, US20080091025, US20080106190, US20080124572, US20080145707, US20080220265, US20080233434, US20080303417, US2008107919, US20090115320, US20090167161, US2009066235, US2011007385, US20110163302, US2011240968, US2011278551, US2012205642, US2013241401, US20140117329, US2014183517, U.S. Pat. Nos. 5,061,569, 5,639,914, WO05075451, WO07125714, WO08023550, WO08023759, WO2009145016, WO2010061824, WO2011075644, WO2012177006, WO2013018530, WO2013039073, WO2013087142, WO2013118812, WO2013120577, WO2013157367, WO2013175747, WO2014002873, WO2014015935, WO2014015937, WO2014030872, WO2014030921, WO2014034791, WO2014104514, WO2014157018.
An electron blocking layer (EBL) may be used to reduce the number of electrons and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies, and/or longer lifetime, as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED. In some embodiments, the EBL material has a higher LUMO (closer to the vacuum level) and/or higher triplet energy than the emitter closest to the EBL interface. In some embodiments, the EBL material has a higher LUMO (closer to the vacuum level) and/or higher triplet energy than one or more of the hosts closest to the EBL interface. In one aspect, the compound used in EBL contains the same molecule or the same functional groups used as one of the hosts described below.
The light emitting layer of the organic EL device of the present disclosure preferably contains at least a metal complex as light emitting material, and may contain a host material using the metal complex as a dopant material. Examples of the host material are not particularly limited, and any metal complexes or organic compounds may be used as long as the triplet energy of the host is larger than that of the dopant. Any host material may be used with any dopant so long as the triplet criteria is satisfied.
Examples of metal complexes used as host are preferred to have the following general formula:
wherein Met is a metal; (Y103-Y104) is a bidentate ligand, Y103 and Y104 are independently selected from C, N, O, P, and S; L101 is an another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal; and k′+k″ is the maximum number of ligands that may be attached to the metal.
In one aspect, the metal complexes are:
wherein (O—N) is a bidentate ligand, having metal coordinated to atoms O and N.
In another aspect, Met is selected from Ir and Pt. In a further aspect, (Y103-Y104) is a carbene ligand.
In one aspect, the host compound contains at least one of the following groups selected from the group consisting of aromatic hydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl, triphenylene, tetraphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene; the group consisting of aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine; and the group consisting of 2 to 10 cyclic structural units which are groups of the same type or different types selected from the aromatic hydrocarbon cyclic group and the aromatic heterocyclic group and are bonded to each other directly or via at least one of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom, chain structural unit and the aliphatic cyclic group. Each option within each group may be unsubstituted or may be substituted by a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof.
In one aspect, the host compound contains at least one of the following groups in the molecule:
wherein R101 is selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above. k is an integer from 0 to 20 or 1 to 20. X101 to X108 are independently selected from C (including CH) or N. Z101 and Z102 are independently selected from NR101, O, or S.
Non-limiting examples of the host materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: EP2034538, EP2034538A, EP2757608, JP2007254297, KR20100079458, KR20120088644, KR20120129733, KR20130115564, TW201329200, US20030175553, US20050238919, US20060280965, US20090017330, US20090030202, US20090167162, US20090302743, US20090309488, US20100012931, US20100084966, US20100187984, US2010187984, US2012075273, US2012126221, US2013009543, US2013105787, US2013175519, US2014001446, US20140183503, US20140225088, US2014034914, U.S. Pat. No. 7,154,114, WO2001039234, WO2004093207, WO2005014551, WO2005089025, WO2006072002, WO2006114966, WO2007063754, WO2008056746, WO2009003898, WO2009021126, WO2009063833, WO2009066778, WO2009066779, WO2009086028, WO2010056066, WO2010107244, WO2011081423, WO2011081431, WO2011086863, WO2012128298, WO2012133644, WO2012133649, WO2013024872, WO2013035275, WO2013081315, WO2013191404, WO2014142472, US20170263869, US20160163995, U.S. Pat. No. 9,466,803,
One or more additional emitter dopants may be used in conjunction with the compound of the present disclosure. Examples of the additional emitter dopants are not particularly limited, and any compounds may be used as long as the compounds are typically used as emitter materials. Examples of suitable emitter materials include, but are not limited to, compounds which can produce emissions via phosphorescence, fluorescence, thermally activated delayed fluorescence, i.e., TADF (also referred to as E-type delayed fluorescence), triplet-triplet annihilation, or combinations of these processes.
Non-limiting examples of the emitter materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: CN103694277, CN1696137, EB01238981, EP01239526, EP01961743, EP1239526, EP1244155, EP1642951, EP1647554, EP1841834, EP1841834B, EP2062907, EP2730583, JP2012074444, JP2013110263, JP4478555, KR1020090133652, KR20120032054, KR20130043460, TW201332980, U.S. Ser. No. 06/699,599, U.S. Ser. No. 06/916,554, US20010019782, US20020034656, US20030068526, US20030072964, US20030138657, US20050123788, US20050244673, US2005123791, US2005260449, US20060008670, US20060065890, US20060127696, US20060134459, US20060134462, US20060202194, US20060251923, US20070034863, US20070087321, US20070103060, US20070111026, US20070190359, US20070231600, US2007034863, US2007104979, US2007104980, US2007138437, US2007224450, US2007278936, US20080020237, US20080233410, US20080261076, US20080297033, US200805851, US2008161567, US2008210930, US20090039776, US20090108737, US20090115322, US20090179555, US2009085476, US2009104472, US20100090591, US20100148663, US20100244004, US20100295032, US2010102716, US2010105902, US2010244004, US2010270916, US20110057559, US20110108822, US20110204333, US2011215710, US2011227049, US2011285275, US2012292601, US20130146848, US2013033172, US2013165653, US2013181190, US2013334521, US20140246656, US2014103305, U.S. Pat. Nos. 6,303,238, 6,413,656, 6,653,654, 6,670,645, 6,687,266, 6,835,469, 6,921,915, 7,279,704, 7,332,232, 7,378,162, 7,534,505, 7,675,228, 7,728,137, 7,740,957, 7,759,489, 7,951,947, 8,067,099, 8,592,586, 8,871,361, WO06081973, WO06121811, WO07018067, WO07108362, WO07115970, WO07115981, WO08035571, WO2002015645, WO2003040257, WO2005019373, WO2006056418, WO2008054584, WO2008078800, WO2008096609, WO2008101842, WO2009000673, WO2009050281, WO2009100991, WO2010028151, WO2010054731, WO2010086089, WO2010118029, WO2011044988, WO2011051404, WO2011107491, WO2012020327, WO2012163471, WO2013094620, WO2013107487, WO2013174471, WO2014007565, WO2014008982, WO2014023377, WO2014024131, WO2014031977, WO2014038456, WO2014112450.
A hole blocking layer (HBL) may be used to reduce the number of holes and/or excitons that leave the emissive layer. The presence of such a blocking layer in a device may result in substantially higher efficiencies and/or longer lifetime as compared to a similar device lacking a blocking layer. Also, a blocking layer may be used to confine emission to a desired region of an OLED. In some embodiments, the HBL material has a lower HOMO (further from the vacuum level) and/or higher triplet energy than the emitter closest to the HBL interface. In some embodiments, the HBL material has a lower HOMO (further from the vacuum level) and/or higher triplet energy than one or more of the hosts closest to the HBL interface.
In one aspect, compound used in HBL contains the same molecule or the same functional groups used as host described above.
In another aspect, compound used in HBL contains at least one of the following groups in the molecule:
wherein k is an integer from 1 to 20; L101 is another ligand, k′ is an integer from 1 to 3.
Electron transport layer (ETL) may include a material capable of transporting electrons. Electron transport layer may be intrinsic (undoped), or doped. Doping may be used to enhance conductivity. Examples of the ETL material are not particularly limited, and any metal complexes or organic compounds may be used as long as they are typically used to transport electrons.
In one aspect, compound used in ETL contains at least one of the following groups in the molecule:
wherein R101 is selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acids, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is aryl or heteroaryl, it has the similar definition as Ar's mentioned above. Ar1 to Ar3 has the similar definition as Ar's mentioned above. k is an integer from 1 to 20. X101 to X108 is selected from C (including CH) or N.
In another aspect, the metal complexes used in ETL contains, but not limit to the following general formula:
wherein (O—N) or (N—N) is a bidentate ligand, having metal coordinated to atoms O, N or N, N; L101 is another ligand; k′ is an integer value from 1 to the maximum number of ligands that may be attached to the metal.
Non-limiting examples of the ETL materials that may be used in an OLED in combination with materials disclosed herein are exemplified below together with references that disclose those materials: CN103508940, EP01602648, EP01734038, EP01956007, JP2004-022334, JP2005149918, JP2005-268199, KR0117693, KR20130108183, US20040036077, US20070104977, US2007018155, US20090101870, US20090115316, US20090140637, US20090179554, US2009218940, US2010108990, US2011156017, US2011210320, US2012193612, US2012214993, US2014014925, US2014014927, US20140284580, U.S. Pat. Nos. 6,656,612, 8,415,031, WO2003060956, WO2007111263, WO2009148269, WO2010067894, WO2010072300, WO2011074770, WO2011105373, WO2013079217, WO2013145667, WO2013180376, WO2014104499, WO2014104535,
In tandem or stacked OLEDs, the CGL plays an essential role in the performance, which is composed of an n-doped layer and a p-doped layer for injection of electrons and holes, respectively. Electrons and holes are supplied from the CGL and electrodes. The consumed electrons and holes in the CGL are refilled by the electrons and holes injected from the cathode and anode, respectively; then, the bipolar currents reach a steady state gradually. Typical CGL materials include n and p conductivity dopants used in the transport layers.
In any above-mentioned compounds used in each layer of the OLED device, the hydrogen atoms can be partially or fully deuterated. The minimum amount of hydrogen of the compound being deuterated is selected from the group consisting of 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99%, and 100%. Thus, any specifically listed substituent, such as, without limitation, methyl, phenyl, pyridyl, etc. may be undeuterated, partially deuterated, and fully deuterated versions thereof. Similarly, classes of substituents such as, without limitation, alkyl, aryl, cycloalkyl, heteroaryl, etc. also may be undeuterated, partially deuterated, and fully deuterated versions thereof.
It is understood that the various embodiments described herein are by way of example only and are not intended to limit the scope of the invention. For example, many of the materials and structures described herein may be substituted with other materials and structures without deviating from the spirit of the invention. The present invention as claimed may therefore include variations from the particular examples and preferred embodiments described herein, as will be apparent to one of skill in the art. It is understood that various theories as to why the invention works are not intended to be limiting.
Organometallic iridium complexes with two cyclometalated ligands (C{circumflex over ( )}N) and one bis-oxazoline derived ancillary ligand (L{circumflex over ( )}X), i.e. (C{circumflex over ( )}N)2Ir(L{circumflex over ( )}X), are reported. The C{circumflex over ( )}N ligands are 1-phenylpyrazoline (ppz), 2-(4,6-difluorophenyl)pyridine (F2ppy), 2-phenylpyridine (ppy), 1-phenylisoquinoline (piq). The box ligand is (4S)-(+)-phenyl-α-[(4S)-phenyloxazolidin-2-ylidene]-2-oxazoline-2-acetonitrile. The emission of these complexes span across the visible and into the near-ultraviolet region of the electromagnetic spectrum with moderate to high photoluminescence quantum yields (ΦPL=0.45-1.0). These complexes were found to emit from a metal-ligand to ligand charge transfer (ML′LCT) state and have lifetimes (1.3-2.1 ρs), radiative rates (105 s−1), and nonradiative rates (104-105 s−1) comparable to state-of-the-art iridium emitters. The (ppy)2Ir(BOX-CN) complexes were resolved into the Δ- and Λ-diastereomers using differences in their solubility and additionally characterized by x-ray crystallography, stability, and chiroptic studies. The high ΦPL of these isomers results in the best to date brightness for circularly polarized luminescence (CPL) from iridium complexes (7.0 M−1 cm−1), with dissymmetry factors of −0.57×10−3 and +1.9×10−3 for 3Δ and 3Λ, respectively. The significant difference in CPL magnitude between 3Δ and 3Λ likely arises from interligand interactions (edge-to-face arrangement versus strong π-π interaction) for the pendant phenyl ring of the BOX-CN ligand which differ for the two isomers.
Luminescent iridium (III) complexes have garnered attention for their application in biosensors (Huang, T. C. et al., Dalton Transactions 2018, 47 (23), 7628-7633), photoredox catalysis (Ackerman, L. K. G. et al., Journal of the American Chemical Society 2018, 140 (43), 14059-14063; Gonzalez-Esguevillas, M. et al., Tetrahedron 2019, 75 (32), 4222-4227) and organic light-emitting diodes (Baldo, M. A. et al., Nature 1998, 395 (6698), 151-154).
Interest in these heavy metal emitters stems from their demonstrated ability to harvest both singlet and triplet excitons and give photoluminescent efficiencies up to 100%. Spin orbit coupling (SOC) of the heavy iridium ion leads to ultrafast intersystem crossing. The strong SOC of the heavy iridium atom of these emitters imparts substantial singlet character to the nominally triplet states leading to emission on the μs timescale and near unit efficiencies for phosphorescence.
Some of the most common and successful phosphorescent emitters are bis-cyclometalated iridium complexes, (C{circumflex over ( )}N)2Ir(L{circumflex over ( )}X) (Yoon, S.; et al., Chemical Communications 2021, 57 (16), 1975-1988), where the cyclometalating (C{circumflex over ( )}N) ligand is composed of a covalently bound arene or other organic moiety and datively bound nitrogen of a heterocyclic ring (Baldo, M. A., et al., Applied Physics Letters 1999, 75 (1), 4-6; Adachi, C. et al., Applied Physics Letters 2000, 77 (6), 904-906), and the ancillary ligand (L{circumflex over ( )}X) is monoanionic bidentate ligand. Some benefits of these (C{circumflex over ( )}N)2Ir(L{circumflex over ( )}X) over their tris-cyclometalated iridium complex counterparts, Ir(C{circumflex over ( )}N)3, include simpler synthesis and tuning of the emission properties for the heteroleptic complexes (Lai, P.-N. et al., Chemical Communications 2020, 56 (62), 8754-8757). While a wide variety of ancillary ligands have been incorporated into bis-cyclometalated iridium complexes (Chen, Z. et al., Journal of Materials Chemistry C 2020, 8 (7), 2551-2557; Lai, P.-N. et al., Journal of the American Chemical Society 2018, 140 (32), 10198-10207; Lamansky, S. et al., Journal of the American Chemical Society 2001, 123 (18), 4304-4312; Lee, H. S. et al., Journal of Organometallic Chemistry 2009, 694 (20), 3325-3330; Pinter, P. et al., Journal of Organometallic Chemistry 2020, 919, 121251; Zanoni, K. P. S. et al., Inorganic Chemistry 2014, 53 (8), 4089-4099; Liang, A. et al., Optical Materials 2020, 106, 109976; Dumur, F. et al., Synthetic Metals 2013, 182, 13-21), few work well across the entire visible spectral range and nearly all of the Ir(C{circumflex over ( )}N)3 and (C{circumflex over ( )}N)2Ir(L{circumflex over ( )}X) complexes have been studied as racemic mixtures of A and A isomers (Li, T.-Y. et al., Scientific Reports 2015, 5 (1), 14912; Lu, J.-J. et al., Journal of Materials Chemistry C 2021, 9 (15), 5244-5249; Han, J. et al., Advanced Optical Materials 2017, 5 (22), 1700359; Marchi, E. et al., Chemistry—A European Journal 2012, 18 (28), 8765-8773).
C2-symmetric bis(oxazoline) units, commonly referred to as BOX, have been widely implemented as ligands for chiral catalysis (Evans, D. A. et al., Journal of the American Chemical Society 1991, 113 (2), 726-728; Corey, E. J. et al., Journal of the American Chemical Society 1991, 113 (2), 728-729) and coordination chemistry (Gómez, M. et al., Coordination Chemistry Reviews 1999, 193-195, 769-835). These compounds are considered “privileged ligands” for their ability to perform a wide variety of chemical transformations with a high degree of selectivity (Desimoni. et al., Chemical Reviews 2006, 106 (9), 3561-3651). The wide use of BOX is owed in part to its ease of synthesis. Enantiomerically pure chiral BOX ligands can be synthesized from chiral precursors. While BOX has been broadly implemented as ligands, their use in bis-cyclometalated iridium complexes is severely limited.
The C{circumflex over ( )}N ligand used in previous Ir(III) BOX complexes was F2ppy whose Ir(C{circumflex over ( )}N)3 is a sky-blue emitter (Marchi, E. et al., Journal of Materials Chemistry C 2014, 2 (22), 4461-4467). In comparison to the L{circumflex over ( )}X=acac counterpart, both the chiral and achiral BOX ligands resulted in a significant red-shift in the emission (58 and 100 nm, respectively). In this case the BOX ligand is not truly ancillary as the HOMO (and excited state hole-NTO) are largely composed of BOX π-orbitals. The authors reported that upon cycling electrochemically a new iridium (IV) species was formed, presumably stabilized by the strongly electron donating BOX ligand.
Building on this work, reported herein is an examination of strategically modifying the meso-position of the BOX ligand to stabilize the HOMO, resulting in a blue-shift in the λmax of emission. This stabilization was accomplished through the use of an electron withdrawing cyano (CN) group. The BOX-CN complexes highlighted in this study include racemic mixtures of the Δ- and Λ-diastereomers of (ppz)2Ir(BOX-CN) (1Δ,Λ), (F2ppy)2Ir(BOX-CN) (2Δ,Λ) and (piq)2Ir(BOX-CN) (4Δ,Λ) as well as diastereomerically pure Δ- and Λ-isomers of (ppy)2Ir(BOX-CN) (3Δ and 3Λ). All complexes were photophysically and electrochemically characterized. Complexes 3Δ and 3Λ were additionally characterized using X-ray crystallographic, stability and chiroptic studies.
All reactions were carried out under nitrogen using standard Schlenk line techniques unless otherwise noted. Diethyl malonimidate dihydrochloride was purchased from Sigma-Aldrich and used without further purification. Tetrahydrofuran (THF) was dried using a dry solvent system from Glass Contour. The chloride-bridged cyclometalated (C{circumflex over ( )}N=ppz, F2ppy, ppy, piq) iridium dimer precursors, [(C{circumflex over ( )}N)2Ir(μ-Cl)]2, were synthesized following standard Nonoyama conditions.
General synthesis of BOXSS—CN/BOXRR—CN ((4S)-(+)-phenyl-α-[(4S)-phenyloxazolidin-2-ylidene]-2-oxazoline-2-acetonitrile) and ((4R)-(+)-phenyl-α-[(4R)-phenyloxazolidin-2-ylidene]-2-oxazoline-2-acetonitrile), respectively. BOXSS—CN was synthesized in two steps from diethylmalonimidate dihydrochloride, as illustrated in Scheme 1. Bis((S)-4-phenyl-4,5-dihydrooxazol-2-yl)methane (BOXSS—H) was first synthesized using (S)-phenylglycinol (Guan, Y. et al., Chemistry—A European Journal 2020, 26 (8), 1742-1747). BOXSS—H was then converted to BOXSS—CN (Nolin, K. A. et al., Chemistry—A European Journal 2010, 16 (31), 9555-9562). BOXRR—CN was synthesized following the same two step synthesis but substituting (R)-phenylglycinol in place of (S)-phenylglycinol.
General synthesis of all complexes with BOXSS—CN/BOXR—CN. BOXSS—CN ligand (2.2 equiv.), K2CO3 (10 equiv.) and THF (40 mL) were added to an oven-dried flask and allowed to stir at RT for ˜1 h. [(C{circumflex over ( )}N)2Ir(μ-Cl)]2 (250 mg) was added to the flask and the reaction mixture was brought to reflux with stirring overnight. The reaction mixture was cooled to room temperature, reduced to half the volume and filtered to remove excess potassium carbonate. The filtrate was concentrated to dryness to give crude product, (C{circumflex over ( )}N)2Ir(BOXSS—CN). The resulting solid was purified by on a silica column eluting with 50% ethyl acetate in hexanes to give a mixture of Δ- and Λ-isomers of the (C{circumflex over ( )}N)2Ir(BOXSS—CN) complexes as microcrystalline powders. Complexes containing BOXRR—CN were synthesized using a similar procedure but using BOXRR—CN in place of BOXSS—CN.
(C{circumflex over ( )}N)2Ir(BOXSS—CN) complexes (C{circumflex over ( )}N=ppz, F2ppy, piq) were analyzed as a mixture of the Δ- and Λ-isomers. The Δ- and Λ-diastereomers of (ppy)2Ir(BOXSS—CN) (3Δ and 3Λ respectively) we separated using differences in solubility. 3Δ was found to have a higher solubility in ethyl acetate compared to 3Λ. 3Δ was obtained by washing the isomeric mixture with a minimal amount of cold ethyl acetate. The solid that dissolved was found to be mostly the 3Δ isomer. The solution was concentrated to dryness and the procedure was repeated until isomerically pure 3Δ was obtained. 3Λ was then isolated by heating the remaining diastereomeric mixture in ethyl acetate and the mixture filtered hot. The solid obtained was found to be mostly 3Λ. Heating the solid in hot ethyl acetate and filtering hot was performed until only 3Λ remained. The Δ- and Λ-isomers of the (ppy)2Ir(BOXRR—CN) complexes were separated using similar conditions to that of the (ppy)2Ir(BOXSS—CN) diastereomers. Complex 3RRΛ was obtained using the same cold ethyl acetate wash as 3Δ, whereas 3RRΔ was obtained using the same hot ethyl acetate method as for 3Λ. The yields of each individual isomers were not optimized. Enough of each pure isomer was obtained to get all required data (<50 mg).
General synthesis for (ppz)2Ir(BOXss-CN) BOXss—CN (117 mg, 535 μmol), K2CO3 (336 mg, 2.43 mmol), ppy iridium dimer (250 mg, 243 μmol). White microcrystalline powder. (326 mg, 83% yield of isomer mixture).
(ppz)2Ir(BOXSS—CN) (1Δ,Λ). 1H NMR (400 MHz, Acetone-d6) δ 8.49 (d, J=2.9 Hz, 2H), 7.38 (d, J=7.9 Hz, 2H), 7.27 (d, J=2.2 Hz, 2H), 7.14 (dd, J=5.0, 1.9 Hz, 6H), 6.81-6.66 (m, 6H), 6.56 (t, J=2.6 Hz, 2H), 6.23 (td, J=7.4, 1.2 Hz, 2H), 5.47 (dd, J=7.5, 1.4 Hz, 2H), 4.11 (t, J=8.7 Hz, 2H), 4.04 (dd, J=8.6, 3.6 Hz, 2H), 3.90 (dd, J=8.9, 3.6 Hz, 2H). 13C{1H}NMR (101 MHz, acetone) δ 143.48, 143.37, 139.78, 135.51, 134.13, 128.08, 127.17, 126.69, 126.38, 124.75, 121.06, 110.66, 107.00, 75.25, 69.39. Elemental Analysis: Anal. Calcd. for C38H30IrN7O2: C, 56.4; H, 3.74; N, 12.1. Found: C, 56.1; H, 3.75; N, 11.8.
General synthesis for (F2ppy)2Ir(BOXSS—CN) BOXSS—CN (300 mg, 905 mmol), K2CO3 (568 mg, 4.11 mol), ppy iridium dimer (500 mg, 411 mmol). Light yellow microcrystalline powder. (482 mg, 65% yield of isomer mixture). The NMR is for a mixture of diastereomers for (F2ppy)2Ir(BOXSS—CN) (2Δ,Λ).
1H NMR (400 MHz, Acetone-d6) δ 8.80 (dddd, J=12.5, 5.8, 1.6, 0.8 Hz, 4H), 8.26-8.18 (m, 2H), 7.99 (tdd, J=8.1, 1.7, 0.8 Hz, 2H), 7.78 (dddd, J=8.3, 7.5, 1.6, 0.8 Hz, 2H), 7.60-7.52 (m, 2H), 7.48 (ddd, J=7.4, 5.8, 1.5 Hz, 2H), 7.33 (ddd, J=7.4, 5.8, 1.4 Hz, 2H), 7.14-7.06 (m, 6H), 6.91 (tt, J=7.4, 1.3 Hz, 2H), 6.82-6.74 (m, 4H), 6.73 (t, J=7.8 Hz, 4H), 6.30 (dddd, J=31.3, 12.7, 9.4, 2.3 Hz, 3H), 6.14 (dd, J=8.3, 1.3 Hz, 3H), 5.37 (dd, J=8.9, 2.4 Hz, 2H), 4.80 (ddd, J=25.7, 8.7, 2.7 Hz, 3H), 4.73 (t, J=8.6 Hz, 2H), 4.21 (dd, J=8.8, 8.1 Hz, 2H), 4.08-3.96 (m, 6H).
13C{1H}NMR (101 MHz, Acetone-d6) δ 157.01, 151.88, 148.55, 142.20, 142.15, 138.37, 137.66, 127.95, 127.69, 127.36, 127.04, 126.54, 123.17, 122.97, 122.92, 122.28, 122.07, 114.76, 112.40, 96.75, 96.48, 75.96, 75.50, 69.77, 69.19, 13.57, −5.66. Elemental Analysis: Anal. Calcd. for C38H30IrN7O2: C, 55.8; H, 3.13; N, 7.76. Found: C, 55.5; H, 3.10; N, 7.76.
General Synthesis for (ppy)2Ir(BOXSS—CN) BOXSS—CN (340 mg, 1.03 mol), K2CO3 (645 mg, 4.66 mol), ppy iridium dimer (500 mg, 466 mmol). Bright yellow powder. (636 mg, 82% yield of isomer mixture).
Δ-(ppy)2Ir(BOXSS—CN) (3Δ). 1H NMR (400 MHz, Acetone-d6) δ 8.51 (dd, J=5.9, 1.1 Hz, 2H), 8.03 (d, J=8.1 Hz, 2H), 7.85 (td, J=8.0, 1.5 Hz, 2H), 7.66 (d, J=7.7 Hz, 2H), 7.09 (ddt, J=10.8, 5.6, 2.6 Hz, 8H), 6.75 (t, J=7.5 Hz, 2H), 6.64 (dd, J=7.5, 2.1 Hz, 4H), 6.29 (t, J=7.4 Hz, 2H), 5.51 (d, J=7.6 Hz, 2H), 4.08 (dd, J=8.5, 4.2 Hz, 2H), 4.04 (t, J=8.5 Hz, 2H), 3.94 (dd, J=8.5, 4.1 Hz, 2H). 13C{1H}NMR (101 MHz, Acetone-d6) δ 168.01, 166.58, 152.47, 151.31, 144.08, 142.70, 137.08, 133.66, 128.47, 127.91, 127.18, 127.13, 123.84, 121.64, 120.51, 118.21, 75.46, 68.55. Elemental Analysis: Anal. Calcd. for C42H32IrN5O2: C, 60.7; H, 3.88; N, 8.43. Found: C, 60.5; H, 3.80; N, 8.34.
Λ-(ppy)2Ir(BOXSS—CN) (3Λ): 1H NMR (400 MHz, Acetone-d6) δ 8.78 (ddd, J=5.7, 1.6, 0.8 Hz, 1H), 7.65 (ddd, J=8.1, 7.4, 1.6 Hz, 1H), 7.37 (ddd, J=7.3, 5.8, 1.5 Hz, 1H), 7.29 (d, J=8.1 Hz, 2H), 6.95-6.89 (m, 1H), 6.86 (tt, J=7.5, 1.2 Hz, 2H), 6.66 (t, J=7.8 Hz, 3H), 6.62-6.53 (m, 3H), 6.03 (dd, J=8.2, 1.3 Hz, 3H), 6.00-5.90 (m, 2H), 4.76 (dd, J=8.5, 2.4 Hz, 2H), 4.66 (t, J=8.4 Hz, 2H), 3.95 (dd, J=8.3, 2.4 Hz, 2H).
13C{1H}NMR (101 MHz, Acetone-d6) δ 168.51, 148.01, 145.42, 142.42, 136.39, 130.42, 128.76, 127.46, 126.03, 124.73, 123.71, 122.25, 120.22, 119.06, 75.77, 69.82. Elemental Analysis: Anal. Calcd. for C42H32IrN5O2: C, 60.7; H, 3.88; N, 8.43. Found: C, 60.4; H, 3.83; N, 8.34.
General Synthesis for (ppy)2Ir(BOXRR—CN) BOXRR—CN (340 mg, 1.03 mol), K2CO3 (645 mg, 4.66 mol), ppy iridium dimer (500 mg, 4.66 mmol). Bright yellow powder. (612 mg, 79% yield of isomer mixture).
Δ-(ppy)2Ir(BOXRR—CN) (3RRΔ): 1H NMR (400 MHz, Acetone-d6) δ 8.78 (ddd, J=5.8, 1.6, 0.8 Hz, 1H), 7.65 (ddd, J=8.1, 7.4, 1.6 Hz, 1H), 7.37 (ddd, J=7.3, 5.7, 1.5 Hz, 1H), 7.29 (d, J=8.3 Hz, 2H), 6.96-6.88 (m, 2H), 6.86 (tt, J=7.1, 1.3 Hz, 2H), 6.66 (t, J=7.8 Hz, 3H), 6.64-6.54 (m, 3H), 6.03 (dd, J=8.2, 1.1 Hz, 3H), 6.01-5.92 (m, 2H), 4.76 (dd, J=8.5, 2.4 Hz, 2H), 4.66 (t, J=8.4 Hz, 2H), 3.95 (dd, J=8.2, 2.4 Hz, 1H). 13C{1H}NMR (101 MHz, Acetone-d6) δ 168.51, 148.01, 142.42, 136.40, 130.42, 128.76, 127.46, 126.02, 124.72, 123.71, 122.25, 120.22, 119.06, 75.77, 69.82.
Λ-(ppy)2Ir(BOX1m-CN) (3RRΛ): 1H NMR (400 MHz, Acetone-d6) δ 8.51 (ddd, J=5.8, 1.6, 0.8 Hz, 2H), 8.03 (ddd, J=8.2, 1.4, 0.7 Hz, 2H), 7.86 (ddd, J=8.1, 7.4, 1.6 Hz, 2H), 7.66 (dd, J=7.7, 1.3 Hz, 2H), 7.15-7.05 (m, 7H), 6.75 (ddd, J=7.7, 7.2, 1.2 Hz, 2H), 6.69-6.60 (m, 4H), 6.29 (ddd, J=7.6, 7.2, 1.3 Hz, 2H), 5.51 (ddd, J=7.7, 1.3, 0.5 Hz, 2H), 4.09 (dd, J=8.5, 4.2 Hz, 3H), 4.04 (t, J=8.5 Hz, 3H), 3.94 (dd, J=8.5, 4.2 Hz, 2H). 13C{1H}NMR (101 MHz, Acetone-d6) δ 168.01, 152.47, 151.31, 144.08, 142.70, 137.08, 133.66, 128.47, 127.91, 127.18, 127.13, 123.84, 121.64, 120.51, 118.21, 75.46, 68.55.
General Synthesis for (piq)2Ir(BOXss—CN) BOXSS—CN (143 mg, 432 μmol), K2CO3 (272 mg, 1.96 mmol), ppy iridium dimer (250 mg, 196 μmol). Dark red microcrystalline powder. (289 mg, 79% yield of diastereomeric mixture).
(piq)2Ir(BOXSS—CN) (4Δ,Λ). 1H NMR (400 MHz, Acetone-d6) δ 8.49 (d, J=2.9 Hz, 2H), 7.38 (d, J=7.9 Hz, 2H), 7.27 (d, J=2.2 Hz, 2H), 7.14 (dd, J=5.0, 1.9 Hz, 6H), 6.81-6.66 (m, 6H), 6.56 (t, J=2.6 Hz, 2H), 6.23 (td, J=7.4, 1.2 Hz, 2H), 5.47 (dd, J=7.5, 1.4 Hz, 2H), 4.11 (t, J=8.7 Hz, 2H), 4.04 (dd, J=8.6, 3.6 Hz, 2H), 3.90 (dd, J=8.9, 3.6 Hz, 2H). 13C{1H}NMR (101 MHz, Acetone-d6) δ 156.19, 143.75, 142.06, 140.69, 136.94, 136.76, 133.61, 131.03, 130.87, 130.63, 130.04, 129.58, 128.93, 128.60, 128.07, 127.87, 127.53, 127.44, 127.15, 127.08, 127.06, 126.67, 126.41, 126.26, 126.25, 125.82, 125.64, 124.91, 120.72, 120.27, 120.10, 119.62, 75.75, 75.51, 69.43, 68.61. Elemental Analysis: Anal. Calcd. for 38H30IrN7O2: C, 64.5; H, 3.90; N, 7.52. Found: C, 64.0; H, 3.82; N, 7.44.
Single x-ray crystallography was used to structurally characterize the Δ- and Λ-diastereomers of (ppy)2Ir(BOXSS—CN) (3Δ and 3Λ, respectively). Single crystals were obtained by dissolving each isomer in a minimum amount of chloroform and allowing pentane vapor to slowly diffuse into the solution resulting in crystals suitable for x-ray crystallography. All single crystal structures were determined at 100 K with Rigaku Xta LAB Synergy S, equipped with an HyPix-600HE detector and an Oxford Cryostream 800 low Temperature unit, using Cu Ka PhotonJet-S X-ray source. The frames were integrated using the SAINT algorithm to give the hkl files. Data were corrected for absorption effects using the multi-scan method (SADABS) with Rigaku CrysalisPro. The structures were solved by intrinsic phasing and refined with the SHELXTL Software Package (Sheldrick, G. Acta Crystallographica Section C 2015, 71 (1), 3-8). The sample, crystal, data collection, and refinement are provided in the SI. The structures were uploaded to the Cambridge Crystallographic Database (CCDC #2283038 (3Δ) and #2283098 (3Λ))
The QChem 5.1 software package using the iQmol interface was used to run geometry optimized ground-state and triplet-state calculations on all complexes at the B3LYP/LACVP* level.
Dimethylformamide (DMF) was purchased from Milipore and used without further purification. Cyclic Voltammetry (CV) and Differential pulse voltammetry (DPV) were performed through use of an EG&G potentiostat/galvanostat model 283. The electrolyte was composed of 0.1 M tetra-n-butylammonium hexafluorophosphate (TBAF) in anhydrous DriSolv dimethylformamide (DMF). The measurements were taken under an inert atmosphere. The working, counter, and pseudoreference electrodes were composed of glassy carbon, platinum wire, and silver wire respectively. All complexes were referenced to an internal ferrocene/ferrocenium (Fc/Fc+) redox couple.
2-Methyl tetrahydrofuran (2-MeTHF) and methylcyclohexane (MeCy) were purchased from Sigma-Aldrich and used without further purification. Dichloromethane (CH2Cl2) and toluene were dried using a dry solvent system from Glass Contour. Absorbance and molar absorptivity data were measured using a UV-VIS Hewlett-Packard 4853 diode array spectrometer. Photoluminescence quantum yields were recorded using a Hamatsu C9920 integrating sphere equipped with a xenon lamp. Lifetimes were measured using a Time-Correlated Single Photon Counting (TCSPC) equipped with a 405 nm pulsed laser source. Steady state excitation and emission spectra were obtained using a Photon Technology International QuantaMaster phosphorescence/fluorescence spectrofluorimeter.
All NMRs were performed on a Varian 400 NMR spectrometer and referenced to the residual proton signal of the deuterated solvent. Elemental analysis was performed at the University of Southern California. A Bruker Autoflex Speed MALDI-TOF spectrometer was used to obtain mass spectroscopy data. Neat films of the materials were deposited on the Maldi plate by dissolving the complex in CH2Cl2 and spotting the plate with this solution.
BOX-CN was synthesized in two steps. The (C{circumflex over ( )}N)2Ir(BOX-CN) complexes were synthesized by deprotonation of the BOX-CN ligand using K2CO3, followed by reaction with [(C{circumflex over ( )}N)2Ir(μ-Cl)]2 (Scheme 2). Complexes 1-4Δ,Λ were isolated in yields of 65-83% and were obtained in roughly 1:1 ratios of the Δ- and Λ-diastereomers based on NMR. The microcrystalline powders of the complexes ranged in color from white (1Δ,Λ) to red (4Δ,Λ) based on the C{circumflex over ( )}N ligand used. All complexes are air- and moisture-stable. We took advantage of the differences in solubility to separate the diastereomers of 3, 3Δ and 3Λ. Complex 3Δ dissolves easily in ethyl acetate whereas 3Λ is less soluble. 3Δ was purified by washing the isomeric mixture with a minimal amount of cold ethyl acetate, dissolving 3Δ. The resulting mixture was filtered and the filtrate, containing principally 3Δ, was concentrated in vacuo. This step was repeated until enantiomerically pure 3Δ was obtained. Complex 3Λ was purified by heating the remaining solid in ethyl acetate and filtering the mixture hot. The solid obtained was principally 3Λ. Purification by hot ethyl acetate and filtering was repeated until the solid filtered was enantiomerically pure 3Λ.
Single crystal x-ray crystallography was used to examine the two diastereomers of (ppy)2Ir(BOX-CN). The structures of the Δ- and Λ-diastereomers of (ppy)2Ir(BOX-CN), 3Δ and 3Λ respectively, are shown in
Laser desorption/ionization (LDI) mass spectra were taken of all (C{circumflex over ( )}N)2Ir(BOX-CN) complexes. A major peak was observed for all complexes corresponding to the Ir(C{circumflex over ( )}N)2 moiety, i.e., the loss of the BOX ligand. Similar fragmentation behaviors were observed for Ir(ppy)2(acac) (Baranoff, E. et al., Inorganic Chemistry 2012, 51 (1), 215-224) and Ir(F2ppy)2(pic), where loss of acac and pic are observed in the LDI mass spectra respectively. The parent ion is observed in the mass spectra of complexes 2Δ,Λ, while all other BOX complexes give a peak corresponding to the mass of the parent complex plus 14 amu, suggesting the formation of a new species during ionization.
Addition of HCl to Ir(ppy)2(acac) dissolved in CDCl3 is known to result in the formation of the chloride bridge Ir dimer via cleavage of the Ir—O bonds of the acac ancillary ligand (Baranoff, E. et al., Inorganic Chemistry 2012, 51 (1), 215-224). Similar acid-induced degradation reactions were performed on 3Δ,Λ with Ir(ppy)2(acac) run alongside as a control. A 0.2 M HCl solution was added to NMR tubes of the iridium complexes dissolved in CDCl3. Addition of HCl converts Ir(ppy)2(acac) into the chloride bridged dimer within 10 minutes. The HCl solution of 3Δ,Λ shows very little decomposition over a period of 24 hours, indicating that the BOX-CN ligand is more stable to acid than its acac counterpart.
Density functional theory (DFT) modeling was performed at the B3LYP/LACVP* level (functional/basis). For all five complexes, the highest occupied molecular orbital (HOMO) is localized on the iridium and BOX ligand while the lowest occupied molecular orbital (LUMO) is largely localized on the pyridine ring with small contributions from the iridium and phenyl ring of the ppy moiety (see
Cyclic voltammetry and differential pulse voltammetry (DPV) electrochemical measurements were carried out on complexes 1-4Δ,Λ in dimethylformamide. Cyclic voltammetry was used to determine the reversibility of oxidation and reduction features, whereas DPV was used to assign the oxidation and reduction potentials. The redox potentials are summarized in Table 1. The tris, acac and picolinate analogues of 2Δ,Λ, 3Δ and 3Λ are also listed for reference. All complexes show one reversable oxidation and up to 3 quasi-reversible/reversible reduction waves. The reduction potentials vary depending on the C{circumflex over ( )}N ligand used. With the exception of 2Δ,Λ, the oxidation potentials fall in a narrow range (0.39-0.43 V vs. ferrocene), regardless of C{circumflex over ( )}N ligand used. The oxidation and reduction potentials for complexes 3Δ and 3Λ are same within experimental error. The similarity in reduction potentials for these two diastereomers is surprising considering the structural differences between the two isomers. The close π-stacking of the BOX-phenyl and pyridyl groups does not appear to a significant effect on the reduction potential, even though the reduction is largely centered on the pyridyl group.
aPotentials are quoted relative to an internal ferrocene/ferrocenium couple.
bLi, T. -Y. et al., Scientific Reports 2015, 5 (1), 14912
The UV-visible absorption spectra for all the complexes were recorded in 2-MeTHF solutions (
The emission spectra of the (C{circumflex over ( )}N)Ir(BOX-CN) complexes at RT and 77 K are shown in
aValues calculated using kr = ΦPL/τ and ΦPL = kr/(kr + knr).
bLu, J. -J. et al., Journal of Materials Chemistry C 2021, 9 (15), 5244-5249
cMarchi, E. et al., Chemistry - A European Journal 2012, 18 (28), 8765-8773
Complex 1Δ,Λ is non-emissive at RT due to thermal population of metal centered states (3MC), which are nonemissive (Tamayo, A. B. et al., Journal of the American Chemical Society 2003, 125 (24), 7377-7387). Upon cooling, these states are no longer thermally accessible, resulting in these materials being strongly emissive at 77 K. The emission maximum and lifetime are comparable to that of Ir(ppz)3 (Sajoto, T. et al., Journal of the American Chemical Society 2009, 131 (28), 9813-9822). As mentioned previously, 2Δ,Λ is the only complex that is substantially red-shifted in emission from both its tris and bis-cyclometalated complexes. This red-shift in emission is the result of 2Δ,Λ having a HOMO localized on the BOX ligand rather than the deeper HOMO on the C{circumflex over ( )}N ligands. Complexes 3Δ and 3Λ are blue shifted by ˜6 and ˜20 nm at room temperature from the Ir(ppy)3 and (ppy)2Ir(acac) respectively. This blue-shift in the emission is the result of the BOX-CN ligand stabilizing the HOMO (Li, J. et al., Inorganic Chemistry 2005, 44 (6), 1713-1727). The increased LC character in 3Δ and 3Λ leads to a decrease in the spin-orbital coupling, resulting in a slightly lower radiative rates for these complexes to that of the acac derivative. The emission lifetimes at room temperature and 77 K for these complexes are slightly longer than those of (ppy)2Ir(acac), which is likely a result of less MLCT character mixing into the excited states of 3Δ and 3Λ.
Finally, 4Δ,Λ is the most red-shifted of the (C{circumflex over ( )}N)2Ir(BOX-CN) complexes and has a significantly lower ΦPL than that of the other BOX-CN complexes. However, the ΦPL of 4Δ,Λ is comparable to that of the tris complex Ir(piq)3, indicating that the decrease in efficiency is not caused by the BOX-CN ligand but is likely the result of vibronic coupling to the ground state (Energy Gap Law) (Yoon, S.; et al., Chemical Communications 2021, 57 (16), 1975-1988).
Tables 3-8 depict the photophysical properties of the examined compounds in various solvents.
Circular dichroism (CD) spectra were obtained for the four different isomers of (ppy)2Ir(BOX-CN) (3Δ, 3Λ, 3RRΔ and 3RRΛ) in CH2Cl2 (
The emissive properties and chiral nature of 3Δ and 3Λ lead to circularly polarized luminescence, the preferential emission of left- or right-circularly polarized light. CPL spectra were collected in dilute dichloromethane solutions (
In summary, series of chiral bis-cyclometalated iridium complexes containing bis-oxazoline derived ancillary ligands were synthesized. Strategic substitution at the meso-position of the BOX ligand with a cyano group was used to stabilize the HOMO of these materials, leading to a significant blue-shifted in the emission from the parent BOX complex. All complexes were analyzed for their electrochemical, photophysical, and computational properties. The emission of these complexes varied across the visible spectra with moderate to high photoluminescence quantum yields. The synthesized RR and SS isomers of the BOX ligand were used to resolve Δ and Λ isomers of the octahedral (ppy)2Ir(BOX) complexes as diastereomers, which could be separated by fractional crystallization. Crystallographic and spectroscopic studies showed alterations in their structural and electronic properties, which give rise to differences in their circular dichroism spectra. The circularly polarized luminesce from the resolved Δ and Λ isomers of the octahedral (ppy)2Ir(BOX) complexes show a significant difference in CPL intensity between the two diastereomers, with a factor of three greater dissymmetry factor for 3Δ relative to 3Λ. Differing dissymmetry factors for the A and A isomers have not been observed for chiral Ir complexes previously, and likely arises here from differing interligand interactions (edge-to-face arrangement versus strong π-π interaction) for the two isomers.
This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 63/517,128, filed on Aug. 2, 2023, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63517128 | Aug 2023 | US |
