WO2014011491A1

WO2014011491A1 - Carbazole substituted triazole, triazine, and tetrazine ambipolar host materials and devices

Info

Publication number: WO2014011491A1
Application number: PCT/US2013/049394
Authority: WO
Inventors: Carlos Zuniga; Seth Marder; Wojciech HASKE; Bernard Kippelen; Daijun FENG
Original assignee: Georgia Tech Research Corporation
Priority date: 2012-07-09
Filing date: 2013-07-03
Publication date: 2014-01-16

Abstract

Disclosed herein are ambipolar host compounds represented by formula (I): (I), wherein: a) at least one of the R₁, R₂ and R₃ groups is an optionally substituted carbazole group, and the remaining of R₁, R₂ and R₃ are independently selected from hydrogen, halogen and a C_1-20 organic group; b) R₄ is an optionally substituted alkyl group, an optionally substituted heteroalkyl group, a substituted aryl group comprising at least one heteroatom in the substituent, or an optionally substituted heteroaryl group; and c) Y is selected from, and, wherein R₅ is an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group, and wherein R₆ is hydrogen, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group. The compounds can be used in OLED devices.

Description

CARBAZOLE SUBSTITUTED TRIAZOLE, TRIAZINE, AND TETRAZINE AMBIPOLAR HOST MATERIALS AND DEVICES

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 61/669,635, filed July 9, 2012, which is herein incorporated by reference in its entirety.

BACKGROUND

Considerable research has been directed toward the synthesis of organic light-emitting diodes (OLEDs), in view their potential applications in full-color flat panel displays and solid state lighting. Such OLEDs often contain a light emissive layer comprising a luminescent material as a guest, dispersed and/or dissolved in a mixture of host/carrier materials capable of transporting holes, electrons, and/or excitons into contact with the luminescent guest. The light emissive layer is typically disposed between an anode and a cathode.

Compounds comprising the carbazole group have been utilized as hole transporter and/or electron blocking materials in OLED applications, and in some cases as hole- transporting hosts for luminescent guests. In addition, small-molecule 2,5-diaryl oxadiazoles are known as suitable electron transport materials for use in making electron transport layers for OLED devices, and have also been used as electron transport hosts for luminescent guests.

Identifying host materials that can efficiently perform important functions can be difficult, especially for use with guest materials that emit relatively high photon energy. In order to maximize energy transfer from the host materials to the guest emitters, the energies of both the singlet and triplet states of the hole and/or electron transport materials in the host should be at least somewhat higher than the energies of the corresponding singlet and triplet states of the guest emitters. To achieve such high energy excited states, the conjugation of the organic host materials must be limited, in order to provide for singlet and triplet energy levels higher than those of the guest emitters. This can be challenging for OLEDs employing high energy guest emitters.

In some cases, mixtures of hole transport and electron transport materials have been used to form a host material for phosphorescent guests in the emissions layers of multi-layer OLEDs. However, devices based on such mixtures of hole transport and electron transport materials in their emission layers can undergo undesirable phase separations, partial crystallizations, and/or otherwise degrade upon extended OLED device operation, decreasing OLED device efficiency and/or lifetimes over time.

Progress on efficient hosts for higher photon energy phosphorescent emitters has been significantly slower, and the efficiencies and lifetimes of such PhOLEDs remain in need of significant improvement. Accordingly, there remains an unmet need in the art for improved host materials that can efficiently and stably transport holes and electrons into contact with phosphorescent emitters in OLED emission layers.

SUMMARY

Embodiments described herein include, for example, compounds and compositions, methods of making compounds and compositions, and methods of using compounds and compositions, including articles, systems, and devices such as, for example, OLED devices.

One embodiment provides, for example, a compound represented by formula (I):

wherein

a) at least one of the R_l5 R2 and R3 groups is an optionally substituted carbazole group, and the remaining of Ri, R2 and R3 are independently selected from hydrogen, halogen and a Ci-20 organic group; and

b) R4 is an optionally substituted alkyl group, an optionally substituted heteroalkyl group, a substituted aryl group comprising at least one heteroatom in the substituent, or an optionally substituted heteroaryl group; and

R₅ _R₆

c) Y is selected from— N , - -N=N— - and N— C— wherein R₅ is an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group, and wherein R₆ is hydrogen, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group.

Another embodiment provides that (i) the optionally substituted carbazole group is selected from an unsubstituted monocarbazole, an unsubstituted triscarbazole, a

monocarbazole substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide, and a triscarbazole substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide; (ii) the remaining of Ri, R2 and R3 are independently selected from hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide; (iii) R4 is unsubstituted or is substituted with one or more groups selected from hydroxyl, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide; and (iv) R₅ and R₆ are unsubstituted or substituted with one or more substituent groups selected from hydroxyl, fluoro, cyano, alkyl, fluoroalkyl, alkoxide, and fluoroalkoxide.

In another embodiment, the optionally substituted carbazole group is selected from formulae (III), (IV), (V) and (VI):

(VI) wherein each R₈, R9, Rio and Rn is independently selected from hydrogen, fluoro, cyano, a Ci-2₀ linear or branched alkyl group, a C_1-20 linear or branched fluoroalkyl group, a C_1-20 linear or branched alkoxide group, and a C_1-20 linear or branched fluoroalkoxide group.

In another embodiment, the

group is selected from formulae (VII),

(VIII) and (IX):

wherein each Ri₂, R13 and R₁₄ is independently selected from hydrogen, fluoro, cyano, a C_1-20 linear or branched alkyl group, a C_1-20 linear or branched fluoroalkyl group, a C_1-20 linear or branched alkoxide group, a C_1-20 linear or branched fluoroalkoxide group, and an optionally substituted carbazole group.

In another embodiment, R4 is an optionally substituted C_1-30 linear, branched alkyl or heteroalkyl group, or an optionally substituted C_1-30 monocyclic, bicyclic or tricyclic alkyl or heteroalkyl group, including the optional substituent.

In another embodiment, R4 is an optionally substituted C5-30 heteroaryl group, including the optional substituent, or a substituted C5-30 aryl group, including the substituent.

In another embodiment, R4 comprises at least one crosslinkable or polymerizable group.

In another embodiment, R4 is selected from the group consisting of:

In some embodiments, compound comprises at least one triscarbazole group represented by

The some embodiments, the compound is selected from:

Also provided is a method for making the compound described herein, comprising: a) reacting a first compound with a second compound to obtain a third compound represented

by wherein the first compound is represented by a, and

wherein the second compound is represented by

and (b) converting

P c>

^■■-( >-- each HN-NH moiety to an optionally substituted triazole, triazine or tetrazine; wherein (i) R₄ in the formula representing the first compound, (ii) Ri, R2 and R3 in the formula representing the second compound, and (iii) Ri, R2, R3 and R4 in the formula representing the third compound, have the same definition as their R_l5 R₂, R3 and R4 homologues contained in the formula of the compound claimed in any of claims 1-12.

Another embodiment provides a composition comprising the compounds described herein or made by the methods described herein.

Another embodiment provides an electroluminescent device, comprising an anode, a cathode, and an emissive layer, wherein the emissive layer comprises the compounds as described herein or made by the methods described herein, or the compositions as described herein.

In one embodiment, the emissive layer comprises at least one phosphorescent emitter, and wherein the external quantum efficiency of the electroluminescence device at 1,000 cd/m² is at least 5%.

At least one advantage for at least one embodiment includes high external quantum efficiency.

At least one additional advantage for at least one embodiment includes high luminance (measured in units of cd/m²) properties.

At least one additional advantage for at least one embodiment is high efficiency and high luminance properties from a solution-processed emitter layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows performance of OLED devices with evaporation-deposited

Compound A:FIrpic emitting layer and having the structure of

ITO/PEDOT:PSS/ -NPD/mCP/Compound A:FIrpic/BCP/LiF/Al/Ag.

FIG. 2 shows performance of OLED devices with spin-coated Compound H hole transport layer and evaporation-deposited Compound A:FIrpic emitting layer.

DETAILED DESCRIPTION

INTRODUCTION

All references described herein are hereby incorporated by reference in their entireties. Various terms are further described herein below:

"A", "an", and "the" refers to "at least one" or "one or more" unless specified otherwise.

"Optionally substituted" groups refers to, for example, functional groups that may be substituted or unsubstituted by additional functional groups. For example, when a group is unsubstituted, it can be referred to as the group name, for example alkyl or aryl. When a group is substituted with additional functional groups, it may more generically be referred to as substituted alkyl or substituted aryl.

"Alkyl" refers to, for example, linear, branched, or cyclic alkyl groups. This term is exemplified by groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, n-pentyl, ethylhexyl, dodecyl, isopentyl, etc.

"Aryl" refers to, for example, aromatic carbocyclic groups having one or more single rings (e.g., phenyl or biphenyl) or multiple condensed rings (e.g., naphthyl or anthryl).

"Heteroalkyl" refers to, for example, an alkyl group wherein one or more carbon atoms are substituted with heteroatoms.

"Heteroaryl" refers to, for example, an aryl group wherein one or more carbon atoms are substituted with heteroatoms.

"Alkoxide" refers to, for example, the group "alkyl-O". This term is exemplified by groups such as methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, t-butyloxy, etc.

"Fluoroalkyl" refers to, for example, an alkyl group wherein one or more hydrogen atoms are substituted with fluorine. Fluoroalkyl described herein include partially fluorinated alkyl groups as well as perfluoroalkyl groups.

"Fluoroalkoxide" refers to, for example, an alkoxide group wherein one or more hydrogen atoms are substituted with fluorine. Fluoroalkoxide described herein include partially fluorinated alkoxide groups as well as perfluoroalkoxide groups.

"Triscarbazole" refers to, for example, three or more carbazole groups connected to each other through aryl carbon-nitrogen bond and/or aryl carbon-carbon bond.

AMBIPOLAR HOST COMPOUND

Ambipolar host compounds are described in, for example, WO 2010149618,

WO 2010149620, WO 2010149622, and PCT/US2011/066597, all of which are incorporated herein by reference in their entireties.

bodiments described herein relate to a compound represented by formula (I):

(I), wherein: (a) R₄ is an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group; (b) at least one of the R_l5 R2 and R₃ groups is independently an optionally substituted carbazole group, and the remaining of Ri, R2 and R₃ are independently selected from hydrogen, halogen and a C_1-20 organic group; and (c) Y is selected from

R₅ _R₆

N , N=N— - and N— C— wherein R₅ is an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group, and wherein R₆ is hydrogen, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted heteroalkyl group.

In some embodiments, R4 is an optionally substituted alkyl group, an optionally substituted heteroalkyl group, a substituted aryl group comprising at least one heteroatom in the substituent, or an optionally substituted heteroaryl group.

R4 can be, for example, an optionally substituted C_5-30 aryl or heteroaryl group, or an optionally substituted C5-20 aryl or heteroaryl group, or an optionally substituted C5-14 aryl or heteroaryl group, including the optional substituent. R4 can be, for example, an optionally substituted C_1-30 linear or branched alkyl or heteroalkyl group, or an optionally substituted Ci_ 20 linear or branched alkyl or heteroalkyl group, or an optionally substituted C_1-12 linear or branched alkyl or heteroalkyl group, or an optionally substituted Ci-6 linear or branched alkyl or heteroalkyl group, including the optional substituent. R4 can be, for example, an optionally substituted C_1-30 monocyclic, bicyclic or tricyclic alkyl or heteroalkyl group, or an optionally substituted C_1-20 monocyclic, bicyclic or tricyclic alkyl or heteroalkyl group, or an optionally substituted C_1-12 monocyclic, bicyclic or tricyclic alkyl or heteroalkyl group, or an optionally substituted Ci-6 monocyclic, bicyclic or tricyclic alkyl or heteroalkyl group, including the optional substituent.

R4 can be, for example, unsubstituted. R4 can be, for example, substituted with one or more substituents selected from fluoro, cyano, hydroxyl, alkyl, fluoroalkyl, alkoxide, and fluoroalkoxide.

In one embodiment, R4 is an optionally substituted phenyl group. In another embodiment, R4 is a linear or branched alkyl or fluoroalkyl group such as -CH₃ and -CF₃. In A further embodiment, R⁴ is a monocyclic, bicyclic or tricyclic alkyl or fluoroalkyl group such as cyclopentane, cyclohexane, bicyclo[2.2.1]heptane, bicyclo[2.2.2]octane and adamantane.

In some embodiments, R⁴ is a group having the structures shown below:

In one embodiment, R4 comprises at least one crosslinkable or polymerizable group.

R₅

I

In one embodiment, Y is N , and the ambipolar host material comprises a triazole moiety represented by

R₆

_ I

In an another embodiment, Y is N— C— and the ambipolar host material comprises a triazine moiety represented by

In a further embodiment, Y is N=N— and the ambipolar host material comprises a tetrazine moiety represented by

N— N

N=N

In some embodiments, Y is selected from N— N— - and N— C— and

is selected from

R5 and Re can be, for example, an optionally substituted C_1-30 alkyl or heteroalkyl group, or an optionally substituted C_1-20 alkyl or heteroalkyl group, or an optionally substituted C_1-12 alkyl or heteroalkyl group, or an optionally substituted d-5 alkyl or heteroalkyl group, including the optional substituent. R5 and R6 can also be, for example, an optionally substituted C5-30 aryl or heteroaryl group, or an optionally substituted C5-2₀ aryl or heteroaryl group, or an optionally substituted C5-14 aryl or heteroaryl group, including the optional substituent. R5 and R6 can be, for example, unsubstituted. R5 and R6 can also be, for example, substituted with one or more substituents selected from fluoro, cyano, hydroxyl, alkyl, fluoroalkyl, alkoxide, and fluoroalkoxide.

In one embodiment, Ri is an optionally substituted carbazole group. In another embodiment, R2 is an optionally substituted carbazole group. In a further embodiment, R₃ is an optionally substituted carbazole group. In an additional embodiment, both Ri and R₃ are optionally substituted carbazole groups.

Other than the optionally substituted carbazole groups, the remaining of Ri, R2 and R₃ can be, for example, hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide. In a particular embodiment, the remaining of Ri, R2 and R₃ are each hydrogen.

CARBAZOLE GROUP

The optionally substituted carbazole groups can comprise, for example, a

monocarbazole group or triscarbazole group. The synthesis of triscarbazole group is described in Jiang et al., J. Mater. Chem. 21:4918-4926 (2011) and Brunner et al, J. Am. Chem. Soc. 126:6035-6042 (2004), both of which are incorporated herein by reference in their entireties. The monocarbazole group or triscarbazole group can be unsubstituted. The monocarbazole group or triscarbazole group can also be substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxide, fluoroalkoxide, and carbazole.

The optionally substituted carbazole groups described herein can be represented by, ample, formulae (II), (III), (IV), (V) and (VI).

wherein each of R₇, Rg, R¾ Rio and Rn is independently selected from hydrogen, fluoro, cyano, a C_1-20 or Ci-6 linear or branched alkyl, a C_1-20 or Ci-6 linear or branched fluoroalkyl, a C_1-20 or Ci-6 linear or branched alkoxide, or a C_1-20 or Ci-6 linear or branched fluoroalkoxide group. In one embodiment, each of R₇, Rg, R9, Rio and Rn is hydrogen.

In one embodiment, the optionally substituted carbazole groups is selected from formulae (III), (IV), (V) and (VI).

In some embodiments, wherein Ri is an optionally substituted carbazole group, and

hydrogen, the

moiety is represented by formula (VII)

(VII), wherein Ri₂ is independently hydrogen, carbazole, fluoro, cyano, a C_1-20 or Ci-6 linear or branched alkyl, a C_1-20 or C i-6 linear or branched

perfluoroalkyl, a C_1-2o or Ci_-6 linear or branched alkoxide, or a C_1-2o or Ci_-6 linear or branched fluoroalkoxide group.

In one embodiment, the carbazole group at the Ri position is an unsubstituted monocarbazole, and the

moiety is In another embodiment,

the carbazole group at the Ri position is an unsubstituted triscarbazole, and the

mo

In some embodiments, wherein Ri and R₃ are each an optionally substituted carbazole

cyano, a C_1-20 or Ci-6 linear or branched alkyl, a C_1-20 or Ci-6 linear or branched

perfluoroalkyl, a C_1-20 or Ci-6 linear or branched alkoxide, or a C_1-20 or Ci-6 linear or branched fluoroalkoxide group.

In one embodiment, the carbazole group at the Ri and R₃ position are each an

unsubstituted monocarbazole, and the

moiety is In another embodiment, the carbazole group at the Ri and R₃ position are each an unsubstituted

triscarbazole, and the

moiety is

In some embodiments, wherein R₂ is an optionally substituted carbazole group, and

hydrogen, the

moiety is represented by formula (IX):

(IX), wherein R₁₄ is independently hydrogen, carbazole, fluoro, cyano, a Ci-2₀ or Ci-6 linear or branched alkyl, a Ci-2₀ or Ci-6 linear or branched perfluoroalkyl, a Ci_ 2₀ or Ci-6 linear or branched alkoxide, or a Ci-2₀ or Ci-6 linear or branched fluoroalkoxide group.

In one embodiment, the carbazole group at the R2 position is an unsubstituted monocarbazole, and the

moiety is In another

unsubstituted triscarbazole, and the

In some embodiments of the ambipolar host compound described herein, the ■--

moiety is selected from , wherein the

moiety is represented by one of formulae (VII), (VIII) and (IX).

In one embodiment, the ambipolar host material described herein comprises at least one optionally substituted triscarbazole group. In a further embodiment, the ambipolar host material described herein comprises at least one unsubstituted triscarbazole group represented

Specific examples of the ambipolar host compounds described herein include the followings:

MATERIAL PROPERTIES OF THE AMBIPOLAR HOST COMPOUND

Many of the ambipolar host compounds described herein are either sublimable under high vacuum or readily soluble in common organic solvent, and therefore can be readily processed to form compositions useful in organic electronic devices, especially when mixed and/or co-deposited with phosphorescent guest emitters to form the emissive layers of OLED devices.

Further, many of the ambipolar host compounds described herein have high glass transition temperature which is advantageous for OLED applications. For example, the glass transition temperature can be at least 120°C, or at least 150°C, or at least 180°C, or at least 200°C.

METHODS FOR MAKING AMBIPOLAR HOST COMPOUND

Methods for making the ambipolar host compound described herein are disclosed in detail in the Working Examples. For example, a first compound can be reacted with a second

compound to obtain a third compound represented by

wherein the first compound is represented by a, and wherein the second compound is represented

by

equently, the HN-NH moiety of the third compound can be converted to an optionally substituted triazole, triazine or tetrazine group. Ri, R2, R3 and R₄ have been defined in the foregoing sections. Methods for synthesizing triazine and tetrazine-based compounds are disclosed in Yang et al, Angew. Chem. Int. Ed. 51 :5222-5225 (2012) and Phucho et al. , ARKIVOC 2008 (xv):79-87, both of which are hereby incorporated by reference in their entireties. Further, triazole-based compounds can be made by treating oxadiazole-based compounds at high temperature, preferably in a microwave reactor, with a primary amine, preferably with the amine serving as the solvent. The amine can be an aromatic amine and can be present at very high concentrations.

In some embodiments, the ambipolar host compound described herein are synthesized according to the following schemes.

ELECTROLUMINESCENCE DEVICES COMPRISING AMBIPOLAR HOST COMPOUND

The solution-processed electron transporting layer described herein can be used in various electronic devices, including electroluminescence devices such as OLED devices.

Although other alternatives are known in the art, in many embodiments, the OLED devices comprise at least an anode layer, a hole transporting layer, an emission layer, an electron transporting layer, and a cathode layer. Such devices are illustrated in the diagram below. ^■ Cathode Layer

Electron Transporting Layer

Emission Layer

Hole Transporting Layer

Anode Layer

Glass

The thickness of the anode layer, the cathode layer, the emissive layer, the hole transporting layer, and the electron transporting layer can be, for example, about 0.001-1000 μηι, about 0.005-100 μηι, or about 0.01-10 μηι, or about 0.02-1 μηι.

Many suitable materials for anode in electroluminescence devices are known in the art and include, for example, ITO, which can be applied, for example, as a vacuum-deposited layer over an inert and transparent substrate such as glass. Other examples include metal oxide with high work function, such as zinc oxide and indium zinc oxide.

Many suitable materials for cathode in electroluminescence devices are known in the art and include, for example, a combination of LiF as electron injecting material coated with a vacuum deposited layer of Al, and optionally an additional layer of Ag.

Many suitable materials for the hole transporting or hole injection layer of electroluminescence devices are known in the art. Suitable hole transporting materials include, for example, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)

(PEDOT:PSS), hole transporting materials described in WO 2009/080799, US 61/579394, US 61/579402 and US 61/579418, all of which are incorporated herein by reference in their entireties, as well as other hole transporting materials known in the art. In one embodiment, the hole transporting layer is fabricated by solution processing (e.g., spin coating) from a solution comprising the hole transporting material.

Many suitable materials for the electron transport layer of electroluminescence devices are known in the art and include, for example, 2,9-Dimethyl-4,7-diphenyl-l,10- phenanthroline (BCP), as well as those described in WO 2012/024132, WO 2009/080796 and WO 2009/080797, all of which are incorporated herein by reference in their entireties. In one embodiment, the electron transporting layer is fabricated by solution processing (e.g., spin coating) from a solution comprising the electron transporting material (see

WO 2012/024132). Many suitable guest emitters for the emissive layer of electroluminescence devices are known in the art and include, for example, Iridium complexes such as Tris(5-phenyl- 10,10-dimethyl-4-aza- tricycloundeca-2,4,6-triene)Iridium(III) (Ir(pppy)₃), Tris(2- phenylpyridine)iridium(III) (Ir(ppy)₃) and Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2- carboxypyridyl)iridium (III) (FIr(pic)), guest materials described in US 2006/0127696, WO 2009/026235, WO 2011000873 and PCT/US2011/066597, all of which are incorporated herein by reference in their entirety, as well as other guest materials known in the art. The emissive layer can comprise at least one blue emitter, at least one green emitter, at least one

In one embodiment, the OLED devices described herein comprise a solution- processed hole transport layer and a solution-processed emissive layer. In another embodiment, the OLED devices described herein comprise a solution-processed hole transport layer and a vacuum-deposited emissive layer. In a further embodiment, the OLED devices described herein comprise a solution-processed hole transport layer, a solution- processed emissive layer, and a solution-processed electron transport layer.

In some embodiments, the OLED device described herein comprises a green phosphorescent emitter. The external quantum efficiency of said OLED device at 1,000 cd/m² can be, for example, at least 5%, or at least 8%, or at least 10%, or at least 12%, or at least 15%, or at least 18%, or at least 20%.

In some embodiments, the OLED device described herein comprises a blue phosphorescent emitter. The external quantum efficiency of said OLED device at 1,000 cd/m² can be, for example, at least 5%, or at least 8%, or at least 10%, or at least 12%, or at least 15%, or at least 18%, or at least 20%. WORKING EXAMPLES

EXAMPLE 1- Synthesis of Compound A iCZ-III- 100)

S3.10: Synthesized according to the literature.

S3.ll: To a solution of S3.10 (6.8 g, 18 mmol) in methanol (200 mL) was added sulfuric acid (0.5 mL). The reaction mixture was refluxed for 7.5 hours, then after cooling concentrated and deionized water (200 mL) was added. A dark-brown solid was collected by filtration and purified by column chromatography (silica gel; hexanes:ethyl acetate = 8:2). The product was obtained as a white powder, 4.2 g (59.2%), by recrystallization from methanol/water. ¾

NMR (300 MHz, CDC1₃): δ 8.29 (d, J= 1.6 Hz, 2H), 8.20 (t, J= 1.6 Hz, 1H), 3.90 (s, ¹³ δ 163.97, 148.99, 137.56, 133.08, 94.32, 52.73.

S3.12: To a solution of S3.ll (3.0 g, 7.73 mmol), 9H-carbazole (3.0 g, 17.94 mmol), Cu powder (6.4 g, 100.71 mmol) and 18-crown-6 (65 mg, 0.25 mmol) in 1,2-dichlorobenzene (30.0 mL) was added K₂C0₃ (12.6 g, 91.17 mmol) under nitrogen atmosphere. The reaction was carried out at 180 °C for 10.5 hours. After cooling, the reaction mixture was filtered and solids were washed with THF. After solvent removal in vacuo, the product was purified by column chromatography (silica gel ; toluene). The final product was obtained as a white powder, 2.6 g (71.7%), by recrystallization from acetone/methanol. ¾ NMR (300 MHz,

CDCI₃): δ 8.37 (d, J= 1.6 Hz, 1H), 8.15 (dd, J = 7.2 Hz, J₂ = 0.8 Hz, 4H), 8.02 (t, J= 1.6 Hz, 1H), 7.52 (dd, J = 7.2 Hz, J₂ = 0.8 Hz, 4H), 7.45 (td, J; = 7.2 Hz, J₂ = 1.6 Hz, 4H), 7.32 (td, Ji= 12 Hz, J₂ = 1.2 Hz, 4H), 3.99 (s, 3H). ¹³C{ 1H} (75 MHz, CDC1₃): δ 165.39, 140.18, 139.54, 133.63, 129.09, 126.45, 126.20, 123.62, 120.55, 120.43, 109.42, 52.82. MS (EI) m/z : 466.0 [M+]. Anal, calcd. for C₃2H22N2O2: C, 82.38; H, 4.75; N, 6.00. Found: C, 82.34; H, 4.66; N, 6.03.

S4.1: To a solution of S3.12 (10.0 g, 0.5 mmol) in dioxane (100 mL) and ethanol (70 mL) was added hydrazine monohydrate (20 mL). The reaction mixture was reflux for 6 hours. The reaction mixture was cooled down to room temperature and water (380 mL) was added. The solid was collected by filtration, washed with water and dried under vacuum to yield a white solid (10.0 g, 100 %). This compound can be used for next step without any purification. ¾

NMR (400 MHz, CDC1₃): δ 8.13 (dd, J = 7.6 Hz, J₂ = 0.8 Hz, 4H), 8.05 (d, J= 2.0 Hz, 2H), 7.98 (t, J = 2.0 Hz, 1H), 7.52 (s, br, 1H), 7.50 (dd, J = 7.6 Hz, J₂ = 0.8 Hz, 4H), 7.43 (td, J; = 7.6 Hz, J₂ = 0.8 Hz, 4H), 7.31 (td, J = 7.6 Hz, J₂ = 0.8 Hz, 4H), 4.16 (br, 2 H).¹³C{ 1H} NMR (100 MHz, CDC1₃) δ: 166.85, 140.23, 139.99, 136.14, 128.09, 126.31, 123.85, 123.73, 120.73, 120.55, 109.42. MS (EI) m/z : 466.0 [M+]. Anal, calcd. for C₃1H22N2O: C, 79.81; H,

H, 4.78; N, 1 1.82.

S4.16: S4.1 (5.007 g, 10.7 mmol) was dissolved in anhydrous tetrahydrofuran (20 mL) and cooled to 0 °C over an ice-water bath under nitrogen atmosphere. 3-methoxybenzoyl chloride (2.056 g, 11.9 mmol) was added dropwise to the cooled solution. The mixture was stirred overnight and then pyridine (8 mL) was added. Then, deionized water (100 mL) was added and the mixture was extracted with dichloromethane (3 x 150 mL). The organic phase was dried over magnesium sulfate, filtered, and concentrated in vacuo. The crude product was purified by column chromatography (silica gel; 100% dichloromethane) to afford an oil that formed a precipitate upon addition of methanol. The precipitate was collected by filtration and dried to afford a white powder (3.898 g, 60.5%). ¾ (300MHz, DMSO-<¾): δ 10.93 (s, 1H), 10.66 (s, 1H), 8.35-8.30 (m, 2H), 8.25 (d, J= 7.8 Hz, 4H), 8.13 (t, J= 1.8 Hz, 1H), 7.62 (d, J= 8.2, 4H), 7.56-7.39 (m, 7H), 7.32 (t, J= 13 Hz, 4H), 7.19-7.12 (m, 1H), 3.80 (s, 3H). "C^H NMR ClOO MHz, CDC1₃): 166.10, 164.77, 159.68, 140.41, 139.47, 136.60, 134.18, 130.25, 126.98, 125.05, 123.51, 123.44, 121.07, 120.18, 118.33, 112.99, 110.24, 55.75. MS (EI) m/z = 600.2 [M+]. Anal, calcd. for C₃₉H2₈N4O₃: C, 77.98; H, 4.70; N, 9.33. Found: C,

4.36 (Compound A):

Method 1 : Aniline (3.793 g, 40.7 mmol) and anhydrous o-dichlorobenzene (50 mL) combined and cooled in ice-water bath under inert atmosphere. After mixture cooled to 0 °C, phenyl phosphorodichloridate (2.334 g, 1 1.1 mmol) added dropwise and ice-water bath removed. S4.16 (5.999 g, 9.99 mmol) was added portion-wise and the mixture was heated to 195 °C. After 4h, heating was stopped and 2N HC1 (200 mL) was added to cooled mixture. Phases were separated and aqueous layer was extracted with dichloromethane (2 x 100 mL). The combined organic phases were washed with deionized water (200 mL), dried over magnesium sulfate, filtered, and solvents removed in vacuo to afford a clear yellowish oil. The crude oil was purified (silica gel; ethyl acetate: dichloromethane = 70:30) and the product was isolated as a white powder (2.061 g, 31.4%). ¾ (300 MHz, DMSO-£¾: δ 8.22 (m, 4H), 7.92 (t, J = 2.0 Hz, 1H), 7.79 (d, J= 1.9 Hz, 2H), 7.75-7.57 (m, 5), 7.47-7.39 (m, 4H), 7.36- 7.25 (m, 9H), 7.01-6.94 (m, 2H), 6.87-6.84 (m, 1H), 3.60 (s, 3H). ^C^H} (75 MHz, DMSO- d₆): δ 159.3, 154.9, 153.7, 140.1, 139.1, 135.2, 131.0, 130.8, 129.0, 128.4, 127.0, 123.5, 121.2, 121.1, 114.1, 1 10.1, 55.5. MS (EI) m/z = 657.0 [M+]. Anal, calcd. for C₄₅H₃iN₅0: C, 82.17; H, 4.75; N, 10.65. Found: C, 82.04; H, 4.57; N, 10.52.

Method 2:

(1.751 g, 3.01 mmol) was synthesized according to WO 2012/088316 and added to distilled aniline (15 mL) and sealed in microwave reaction vessel and heated to 200 °C for 6 h (power = 250 W, Temperature = 200 °C, PSI = 250 psi, Run Time = 10 min, Hold Time = 90 min). The reaction solution was mixed with 2N HC1 (100 mL) and dichloromethane (100 mL). The phases were separated, dried over magnesium sulfate, filtered, and solvents removed in vacuo. The crude product was purified by column chromatography (silica gel; gradient elution from 100%

dichloromethane to dichloromethane: ethyl acetate = 80:20) to afford an oil that precipitated upon addition of methanol. The final product was obtained as a white powder (0.603 g, 35.7%). 1H (300 MHz, DMSO-d₆): δ 8.22 (m, 4H), 7.92 (t, J= 2.0 Hz, 1H), 7.79 (d, J= 1.9 Hz, 2H), 7.75-7.57 (m, 5), 7.47-7.39 (m, 4H), 7.36-7.25 (m, 9H), 7.01-6.94 (m, 2H), 6.87- 6.84 (m, 1H), 3.60 (s, 3H). - Synthesis of Compound B

Triscarbazole (600 mg, 20 mmol), 3-(3-iodophenyl)-5-methyl-4-phenyl-4H-l,2,4- triazole (861, 40 mmol), Cul (38 mg, 0.2 mmol), and K₃PO4 (1.0 g, 5 mmol) were added to a 3-necked flask, and then (±)-/ra«s-l,2-cyclohexanediamine (23 mg, 0.2 mmol) and dioxane (3mL) were added under a nitrogen atmosphere. After stirring for 24 h at 110°C, the reaction mixture was cooled to room temperature. Upon removal of the solvent under reduced pressure, the resulting residue was poured into saturated NH₄C1 aqueous solution and extracted with chloroform. The organic layer was separated and dried over sodium sulfate. Removal of sodium sulfate by filtration and solvent by rotarvaperization under reduced pressure afforded the crude product. Purification by silica gel column chromatography (eluent = THF: hexane= 2: 1) provided the title compound 750 mg. Yield: 85%. 1H NMR (300 MHz, CDC13, δ):8.23 (d, J = 1.8 Hz, 1H, ), 8.18 (d, J = 7.8 Hz, 1H), 7.84-7.82 (1H, m), 7.76-7.70 (2H, m), 7.68-7.64 (1H, m), 7.56-7.64 (3H, m), 7.54-7.48 (1H, m), 7.45-7.26 (16H, m), 2.40 (3H,s). (75 MHz, CDC13): U\ .1 , 140.1, 137.2, 135.3, 134.9, 130.8, 130.6, 130.1,

129.3, 128.1, 128.0, 127.4, 126.5, 126.3, 125.9, 124.3, 124.1, 123.2, 123.1, 120.4, 119.8, 119.7, 1 11.0, 109.6, 11.4. Elem. Anal. Calcd for C₃₈H₃₀N4O: C, 81.81; H, 4.69; N, 11.50. Found: C, 82.24; H, 4.75; N, 11.21.MALDY-MS (m/z): M⁺ calcd for C₅iH₃₄N6, 731.3; found 731.3.

Indium tin oxide (ITO)-coated glass (Colorado Concept Coatings LLC) with a sheet resistivity of -15 Ω/sq was used as the substrate for the OLEDs fabrication. The ITO substrates were patterned with kapton tape and etched in acid vapor (1 :3 by volume, HNO₃: HC1) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath of detergent water, rinsed with deionized water, and then cleaned in sequential ultrasonic baths of deionized water, acetone, and isopropanol. Each ultrasonic bath lasted for 20 minutes. Nitrogen was used to dry the substrates after each of the last three baths. Finally all substrates were treated with an O2 plasma for 3 minutes prior to the deposition of the organic layers.

For the PEDOT: PSS hole-transport layer, PEDOT: PSS A14083 was spin coated (60s@7000 rpm, acceleration 10,000 rpm/s) onto plasma-treated ITO coated glass substrates. After spin-coating, the PEDOT: PSS layers were annealed for 10 minutes at 140 °C on a hot plate. Samples were then transferred into an in an EvoVac thermal deposition system, Angstrom Engineering, for the evaporation of the remaining layers.

NPD

For the hole transport layer, a 35 nm thick -NPD was first deposited on top of the PEDOT:PSS layer at a pressure below 2* 10^"7 Torr and at a rate of 0.6 A/s. Then a 15 nm thick mCP layer was deposited on top of the a-NPD at a pressure below 2* 10^"7 Torr and at rates of

A 20 nm thick emissive layer consisting of Compound A and Flrpic was then co- deposited, with an Flrpic concentration of 10 wt.%, in the EvoVac system at a pressure below 10^"7 Torr and at rates of 1 and 0.1 A/s respectively. Then, for the hole-blocking and electron transport layer, a 40 nm thick BCP layer was deposited at a pressure below 2* 10^"7 Torr and at rates of 0.4 A/s. A 2.4 nm of lithium fluoro (LiF), as an electron- injection layer, and a 40 nm- thick aluminum layer were sequentially deposited through a shadow mask at a pressure below 3* 10^"7 Torr and at rates of 0.15 A/s and 2 A/s, respectively. The cathode was then finished by depositing a 100 nm thick silver layer, through the same shadow mask as LiF and Al, at a pressure below 3 ^χ 10^"7 Torr and at a rate of 1.1 A/s. The shadow mask used for the evaporation of the metal electrodes yielded five devices with an area of roughly 0.1 cm² per substrate. The testing was done right after the deposition of the metal cathode in inert atmosphere and without exposing the devices to air. The performance of the device is shown in Figure 1.

Glass

Indium tin oxide (ITO)-coated glass (Colorado Concept Coatings LLC) with a sheet resistivity of -15 Ω/sq was used as the substrate for the OLEDs fabrication. The ITO substrates were patterned with kapton tape and etched in acid vapor (1 :3 by volume, HNO₃: HCl) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath of detergent water, rinsed with deionized water, and then cleaned in sequential ultrasonic baths of deionized water, acetone, and isopropanol. Each ultrasonic bath lasted for 20 minutes. Nitrogen was used to dry the substrates after each of the last three baths. Finally all substrates were treated with an O₂ plasma for 3 minutes prior to the deposition of the organic layers.

Compound H

Compound H was synthesized according to US 61/579394, incorporated by reference in its entirety. For the Compound H hole -transport layer, 10 mg of Compound H were dissolved in 1 ml of 99.8% pure chlorobenzene which was distilled and degassed over night prior to be used. 35 nm thick Compound H layers were spin coated (60s@1500 rpm, acceleration 10,000 rpm/s) onto plasma-treated ITO coated glass substrates. Samples where then transferred into an EvoVac thermal deposition system, Angstrom Engineering, for the evaporation of the remaining layers.

A 20 nm thick emissive layer consisting of Compound A and Flrpic was co-deposited, with an Flrpic concentration of 10 wt.%, in the EvoVac system at a pressure below 10^"7 Torr and at rates of 1 and 0.1 A/s respectively. Then, for the hole-blocking and electron transport layer, a 40 nm thick BCP layer was deposited at a pressure below 2* 10^"7 Torr and at rates of 0.4 A/s. A 2.4 nm of lithium fluoro (LiF), as an electron- injection layer, and a 40 nm-thick aluminum layer were sequentially deposited through a shadow mask at a pressure below 3* 10^"7 Torr and at rates of 0.15 A/s and 2 A/s, respectively. The cathode was then finished by depositing a 100 nm thick silver layer, through the same shadow mask as LiF and Al, at a pressure below 3 ^χ 10^"7 Torr and at a rate of 1.1 A/s. The shadow mask used for the evaporation of the metal electrodes yielded five devices with an area of roughly 0.1 cm² per substrate. The testing was done right after the deposition of the metal cathode in inert atmosphere and without exposing the devices to air. The performance of the device is shown in Figure 2.

Claims

WHAT IS CLAIMED IS:

1. A compound represented by formula (I):

wherein

a) at least one of the R_l5 R2 and R3 groups is an optionally substituted carbazole group, and the remaining of Ri, R2 and R3 are independently selected from hydrogen, halogen and a Ci-2₀ organic group; and

b) R₄ is an optionally substituted alkyl group, an optionally substituted heteroalkyl group, a substituted aryl group comprising at least one heteroatom in the substituent, or an optionally substituted heteroaryl group; and

R₅ _R₆

2. The compound of claim 1, wherein:

(i) the optionally substituted carbazole group is selected from an unsubstituted monocarbazole, an unsubstituted triscarbazole, a monocarbazole substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide, and a triscarbazole substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide; (ii) the remaining of Ri, R2 and R3 are

independently selected from hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide; (iii) R4 is unsubstituted or is substituted with one or more groups selected from hydroxyl, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide; and (iv) R5 and R6 are unsubstituted or substituted with one or more substituent groups selected from hydroxyl, fluoro, cyano, alkyl, fluoroalkyl, alkoxide, and fluoroalkoxide.

3. The compound of claim 1 or 2, wherein the optionally substituted carbazole group is selected from formulae (III), (IV), (V) and (VI):

wherein each R₈, R9, Rio and Rn is independently selected from hydrogen, fluoro, cyano, a

Ci-20 linear or branched alkyl group, a C_1-20 linear or branched fluoroalkyl group, a C_1-20 linear or branched alkoxide group, and a C_1-2o linear or branched fluoroalkoxide group.

wherein each Ri₂, R13 and R₁₄ is independently selected from hydrogen, fluoro, cyano, a C_1-20 linear or branched alkyl group, a C 1-20 linear or branched fluoroalkyl group, a C_1-20 linear or branched alkoxide group, a C_1-20 linear or branched fluoroalkoxide group, and an optionally substituted carbazole group.

5. The compound of any of claims 1-4, wherein R₄ is an optionally substituted C_1-30 linear, branched alkyl or heteroalkyl group, or an optionally substituted C_1-30 monocyclic, bicyclic or tricyclic alkyl or heteroalkyl group, including the optional substituent.

6. The compound of any of claims 1-4, wherein R₄ is an optionally substituted C5_-3o heteroaryl group, including the optional substituent, or a substituted C5_-3o aryl group, including the substituent.

7. The compound of any of claims 1-4, wherein R4 is selected from the group consisting

e compoun o any o c a ms - , w ere n

9. The compound of any of claims 1-7, wherein

N— N

< >--- or N=N

10. The compound of claim 1, wherein the compound comprises at least one triscarbazole group represented by

11. The compound of any of claims 1-10, therein R₄ comprises at least one crosslinkable or polymerizable group.

12. The compound of claim 1, wherein the compound is selected from:

13. A method for making the compound of any of claims 1 to 12, comprising:

(a) reacting a first compound with a second compound to obtain a third compound

represented by the first compound is represented by

and wherein the second compound is represented and

(b)

moiety to an optionally substituted triazole, triazine or tetrazine;

wherein (i) R₄ in the formula representing the first compound, (ii) R_l5 R₂ and R₃ in the formula representing the second compound, and (iii) Ri, R2, R3 and R4 in the formula representing the third compound, have the same definition as their R_l5 R₂, R3 and R4 homologues contained in the formula of the compound claimed in any of claims 1-12.

14. A composition comprising the compound of any of claims 1-12 or made by the method of claim 13.

15. An electroluminescence device, comprising an anode, a cathode, and an emissive layer, wherein the emissive layer comprises the compound of any of the claims 1-12 or made by the method of claim 13, or the composition of claim 14.

16. The electroluminescence device of claim 15, wherein the emissive layer comprises at least one phosphorescent emitter, and wherein the external quantum efficiency of the electroluminescence device at 1,000 cd/m² is at least 5%.