WO2014011477A1 - High glass transition temperature "medium-sized" ambipolar host materials - Google Patents

Abstract

Disclosed herein are am bipolar host compounds represented by formula (I), wherein: a) R₄ is an optionally substituted aryl or an optionally substituted heteroaryl group; b) n is at least 2; e) for each (ii) at least one of R₁, R₂ and R₃ is independently 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: and d ) Y is selected from (III), 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 heteroalky! group. The compounds can be used in OLED devices and are ambipolar. The OLED devices can show high efficiency and high luminance.

Description

HIGH GLASS TRANSITION TEMPERATURE "MEDIUM-SIZED"

AMBIPOLAR HOST MATERIALS

Considerable research has been directed toward the synthesis of organic light-emitting diodes (OLEDs), in view of 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 arc 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 at relatively high photon energy or short wavelengths. 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 photon 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) R₄ is an optionally substituted aryl or an optionally substituted aryl hctcroaryl group; b) n is at least 2;

c) for each

, at least one of R₁, R₂ and R₃ is an optionally substituted carbazole group, and the remaining of R₁, R₂ and R₃ ard independently selected from hydrogen, halogen, and a C_{1 - 20} organic group; and d) Y is selected from

, wherein R₅ is an optionally substituted ar_yl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted hcteroalkyl 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 carbazole group is unsubstituted or substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxidc, fluoroalkoxidc and optionally substituted carbazole; (ii) the remaining of R₁, R₂ and R₃ are independently selected from hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxidc; (iii) R₄ is unsubstituted or substituted with one or more groups selected from

2 fluoro, cyano, alkyl, fluoroalky,l alkoxide and fluoroalkoxide; and (iv) 5₄ and R₆ are unsubstituted or substituted with one or more groups selected from hydroxy 1, fluoro, cyano, alkyl, iluoroalkyl, alkoxide and fluoroalkoxide.

In another embodiment, the R₄ is an optionally substituted phenyl, biphenyl, or naphthyl, and wherein n is 2, 3 and 4.

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

wherein each R₇, R₈, R₉, R₁₀ and R₁₁ is independently hydrogen, fluoro, cyano, a C_{1 - 20} linear or branched alkyl, a C_{1 - 20} linear or branched iluoroalkyl, a C_{1 - 20} linear or branched alkoxidc, or a C_{1 - 20} linear or branched fluoroalkoxide group.

3 In another embodiment, the group is selected from formulae (VII) and

(VIII):

wherein each R₁₂ and R₁₃ is independently hydrogen, fluoro, cyano, a C_{1 - 20} linear or branched alkyl, a C_{1 - 20} linear or branched perfluoroalkyl, a C_{1 - 20} linear or branched alkoxidc, a C_{1 - 20} linear or branched fluoroalkoxide group, or an optionally substituted carbazole.

In another embodiment, the compound is selected from formulae (IX), (X), (XI) and

(XII):

4

(X!)

, (XH).

In other embodiments,

In other embodiments,

In other embodiments,

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

In some embodiments, the compound has a Tg of at least 150°C.

In some embodiments, the compound is selected from:

5

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

represented by

wherein the first compound comprises the R₄

6 group linked to n

a groups, wherein the second compound is represented by

and (b) converting each

moiety to an optionally substituted oxadiazole or an optionally substituted triazole, wherein (i) R₄ and n in the formula representing the first compound, (ii) R₁, R₂ and R₃ in the formula representing the second compound, and (iii) R₁, R₂, R₃, R₄ and n in the formula representing the third compound, have the same definition as their R₁, R₂, R₃, R₄ and n homologucs contained in the formula of the compounds described herein.

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 spin-coated Compound G hole transport layer and spin-coated Compound D:Ir(pppy)3 emitting layer.

FIG. 2 shows performance of OLED devices with spin-coated PEDOT:PSS hole injection layer, spin-coated Compound G hole transport layer and spin-coated

Compound D:Ir(pppy)3 emitting layer.

7 FIG. 3 shows performance of OLED devices with spin-coated Polymer H hole transport layer and evaporation-deposited Compound D:lr(ppy)3 emitting layer.

FIG. 4 shows performance of OLED devices with spin-coated Polymer H hole transport layer and evaporation-deposited Compound D:Flrpic emitting layer.

FIG. 5 shows performance of OLED devices with spin-coated Polymer H hole transport layer and evaporation-deposited Compound C:Ir(ppy)3 emitting layer.

FIG. 6 shows performance of OLED devices with spin-coated PEDOT:PSS hole injection layer, spin-coated Compound G hole transport layer and spin-coated

Compound E:Ir(pppy)3 emitting layer.

FIG. 7 shows performance of OLED devices with spin-coated Compound G hole transport layer and spin-coated Compound F.:Ir(pppy)3 emitting layer.

FIG. 8 shows performance of OLED devices with spin-coated Compound G hole transport layer and spin-coated Compound F:Ir(pppy)3 emitting layer.

FIG. 9 shows performance of OLED devices with spin-coated PEDOT:PSS hole injection layer, spin-coated Compound G hole transport layer and spin-coated

Compound F:lr(pppy)3 emitting layer.

FIG. 10 shows performance of OLED devices with spin-coated and crosslinked Poly- TPD-F hole transport layer and spin-coated Compound B:lr(pppy)3 emitting layer.

FIG. 1 1 shows performance of an exemplary OLED device with evaporation- deposited M0O3 hole injection layer, spin-coated Compound J hole transport layer and spin- coated Compound F:lr(pppy)3 emitting layer.

FIG. 12 shows performance of an exemplary OLED device with spin-coated

PEDOT:PSS hole injection layer, spin-coated Compound J hole transport layer and spin- coated Compound F:Ir(pppy)3 emitting layer.

FIG. 13 shows performance of an exemplary OLED device with spin-coated

PEDOT:PSS hole injection layer, spin-coated Compound J hole transport layer and spin- coated Compound F:Ir(pppy)3 emitting layer.

FIG. 14 shows performance of an exemplary OLED

hole transport layer and spin- coated Compound F:Ir(pppy)3 emitting layer.

8 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" can refer to "at least one" or "one or more" unless specified otherwise.

' ptionally substituted" groups can refer 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 alky I or ar l. When a group is substituted with additional functional groups, it may more generically be referred to as substituted alkyl or substituted aryl.

"Alkyl" can refer 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-butyf, n-pentyl, cthylhexyl, dodecyl, isopentyl, cyclohexyl, and the like.

"Aryl" can refer 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" can refer to, for example, an alkyl group wherein one or more carbon atoms arc substituted with hctcroatoms.

"Hcteroaryl" can refer to, for example, an aryl group wherein one or more carbon atoms are substituted with hetcroatoms.

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

"Fluoroalkyl" can refer to, for example, an alkyl group wherein one or more hydrogen atoms arc substituted with fluorine. Fluoroalkyl described herein include pcrfluoroalkyl groups.

"Fluoroalkoxidc" can refer to, for example, an alkoxide group wherein one or more hydrogen atoms are substituted with fluorine. Fluoroalkoxidc described herein include pcrfluoroalkoxide groups.

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

9 AMBIPOLAR HOS T C MPOUND

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

WO 2010149620, WO 2010149622, and PCT/US201 1/066597, all of which are incorporated herein by reference in their entireties.

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

(I), wherein: (a) R₄ is an optionally substituted aryl or an optionally substituted heteroar l group of valency n; (b) the valency n is at least 2; (c) for

each

. at least one of R₁, R₂ and R₃ is an optionally substituted carbazolc group. and the remaining of R1, R2 and R3 are independently selected from hydrogen, halogen and a C_{1 - 20} rganic group; and (d) Y is selected from

wherein R₅ is an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alky! group or an optionally substituted hctcroalkyl 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.

R₄ can be, for example, an optionally substituted C_{5 - 20} aryl or heteroaryl group, or an optionally substituted C_{5 - 20}aryl or heteroaryl group, or an optionally substituted C_{5 - 14} aryl or heteroaryl group, including the optional substituent. R₄ can be, for example, unsubstituted other than the linkage to the

moieties. R₄ can be. for example, substituted with one or more substituents selected from fluoro, cyano, alkyl. fluoroalkyl, alkoxide, and fluoroalkoxidc, in addition to the linkage to the

· mo .iet .ies.

R₄ can be, for example, an optionally substituted aryl or heteroaryl group derived from benzene, biphenyl, naphthalene, pyrenc. pyridine. 1,3,5 triazinc. fluorene or spiro-fluorenc.

In one embodiment, R₄ is an optionally substituted benzene group. In another embodiment, R₄ is an optionally substituted biphenyl group. In a further embodiment, R₄ is an optionally substituted naphthalene group.

10 The valency n can be, for example, at least 2, or at least 3, or at least 4, or at least 5, or at least 6. In one embodiment, n is 2. In another embodiment, n is 3. In a further embodiment, n is 4.

In some embodiments wherein R₄ is an bivalent, trivalent or tetravalent benzene or biphenyl group, which is unsubstitutcd other than the linkage to the to the Y

moieties, the ambi polar host compounds can be represented by formulae (IX), (X), (XI) and (XII).

I I In another embodiment, Y is

, and the ambipolar host material comprises a triazole moiety represented by

In a further embodiment, Y is—

, and the ambipolar host material comprises a triazine moiety represented by

In an additional embodiment, Y is N=N— , and the ambipolar host material comprises a tetrazine moiety ( 1,2,4,5-tetrazinc) represented by

N

R₅ and R₆ can be, for example, an optionally substituted C_{1 - 30} alkyl or hcteroalkyl group, or an optionally substituted C_1-20alky I or hcteroalkyl group, or an optionally substituted C_{1 - 6} alkyl or hcteroalkyl group, including the optional substituent. Rs and R« can also be, for example, an optionally substituted C_{5 - 30} aryl or heteroaryl group, or an optionally substituted C_{5 - 20} aryl or hcteroaryl group, or an optionally substituted C_{5 - 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 substitucnts selected from fluoro, cyano, alkyl, hydroxyl, fluoroalkyl, alkoxide, and fluoroalkoxide.

In one embodiment, R₁ 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 R₁ and R₃ arc optionally substituted carbazole groups.

Other than the optionally substituted carbazole groups, the remaining of R₁, R₂ and R₃ can be, for example, hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide. In a particular embodiment, the remaining of R₁, R₂ and R₃ are each hydrogen.

12 CARBAZOLE GROUP

The optionally substituted carbazole groups can comprise, for example, a monocarbazolc group or triscarbazole group. The synthesis of triscarbazole group is described in Jiang el al., J. Mater. hem. 21:4 18-4926 (201 1) and Brunner el al., J. Am. Chem. Soc. 126:6035-6042 (2004), both of which are incorporated herein by reference in their entireties. The monocarbazolc group or triscarbazole group can be unsubstitutcd. The monocarbazolc group or triscarbazole group can also be substituted with one or more groups selected from fluoro, cyano, alky I, fluoroalkyl, alkoxide, fluoroalkoxidc, and optionally substituted carbazole.

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

(Π)

(III)

(IV)

(V)

(VI)

13 _{wherein each of R}7_{, R8}, _R9_{, R}10 _{and R}11 _{is independently hydrogen, fluoro, cyano, a} C_{1-20 or C1-6 linear or branched alkyl, a} C_{1-20 or C1-6 linear or branched fluoroalkyl, a} C_{1-20 or} C_{1-6 linear or branched alkoxide, or a} C_{1-20 r C1-6 linear or branched fluoroalkoxide group. In one embodiment, each of R}7_{, R8}, _R9_{, R}10 _{and R}11 _{is hydrogen.}

i_{n some embodiments, wherein} 1 _{is an optionally substituted carbazolc group, and}

_R2 _{and R}3 _{arc each hydrogen, the}

_{moiety is represented by formula (VII):}

_{(VII), wherein R}12 _{is independently hydrogen, fluoro, cyano, a} C_{1-20 C1-6 linear or branched alky], a} C_{1-20 or C1-6 linear or branched pcrfluoroalkyl, a C1.20 or C1-6 linear or branched alkoxide, a} C_{1-20 or C1-6 linear or branched fluoroalkoxide group, or an optionally substituted carbazole group.}

_{In one embodiment, the carbazole group at the} R_{1 position is an unsubstituted}

₁₄ the carbazole group at the R₁ position is an unsubstitutcd triscarbazole, and the

moiety is

H

In some embodiments, wherein R₁ and 3₁ arc each an optionally substituted carbazolc

group, and R₂ is hydrogen, the

moiety is represented by formula (VIII):

(VIII), wherein R₁₃ is independently hydrogen, fluoro, cyano, a C_1-20 or C_1-6 linear or branched alkyl, a C_1-20 or linear or branched perfluoroalkyl, a C_1-20 or C_{1- 6} linear or branched alkoxidc, or a C_1-20 or linear or branched fluoroalkoxidc group, or an optionally substituted carbazole group.

I5 In one embodiment, the carbazolc group at the R₁ and R₃ position are each an

another

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 by:

I6 Specific examples of the ambipolar host compounds described herein include the fallowings:

17 MATERIAL PROPERTIES OF THE AMBIPOLAR HOST COMPOUND

Many of the ambipolar host compounds described herein are either sublimablc 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 can have relatively high glass transition temperature, which can be advantageous for 01, ED applications. For example, the glass transition temperature can be at least 120 °C, or at least 130 °C, or at least 140 °C, or at least 150 °C, or at least 160 °C, or at least 170 °C, or at least 180 °C, or at least 190 °C, or at least 200 °C. The upper limit for the glass transition temperature can be determined by decomposition temperature, for example, but can be, for example, 400 °C, or 300 °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

_t wherein the

P

first compound comprises an R₄ group of valency n linked to n

groups, and wherein

the second compound is represented by

. Subsequently, each

moiety of the third compound can be converted to an optionally substituted oxadiazole or optionally substituted triazole. R₁, R₂, R₃ and R₄ have been defined in the foregoing sections.

Methods for synthesizing triazine and tctrazine-based compounds are disclosed in Yang el at., Ang w. Che . Int. Ed. 51 :5222-5225 (2012) and Phucho et at., ARKIVOC 2008 (xv):79-87, both of which are hereby incorporated by reference in their entireties.

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

ELECTROLUMINESCENCE DEVICES COMPRISING AMBIPOLAR HOST COMPOUND

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

Although other alternatives arc known in the art, in many embodiments, the OLED devices comprise at least an anode layer, a hole transport layer, an emission layer, an electron transport layer, and a cathode layer. Such devices are illustrated in the diagram below for one embodiment.

The thickness of the anode layer, the cathode layer, the emissive layer, the hole transport layer, and the electron transport layer can be, for example, about 0.001 - 100 um, about 0.005-10 um, or about 0.01-1 um, or about 0.02-0.1 um.

Many suitable materials for anode in electroluminescence devices arc known in the art and include, for example, ITO, which can be applied, for example, by sputtering 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 I,iF as electron injecting material coated with a vacuum deposited layer of Λ1, 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-ethylcnedioxythiophcne):poly<styrenesulfonate)

(Pl-DOT:PSS), hole transporting materials described in WO 2009/080799, US 61/579394, US 61/579402 and US 61/579418, all of which arc incorporated herein by reference in their entireties, as well as other hole transporting materials known in the art. In one embodiment, the hole transport 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-diphcnyl-l,10- phenanthroline (BCP), as well as those described in WO 2012 024132, WO 2009/080796 and WO 2009/080797, all of which arc incorporated herein by reference in their entireties. In one embodiment, the electron transport layer is fabricated by solution processing (e.g., spin

20 coating) from a solution comprising the electron transporting material (sec

WO 2012/02 132).

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- l0,10-dimethyl-4-aza- tricycloundeca-2,4,6-triene)Iridium(lll) (I PPpyfo). Tris(2- phenylpyridinc)iridium(III) (Ir(ppy)₃) and Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2- carboxypyridyl)iridium (111) (Flr(pic)), guest materials described in US 2006/0127696, WO 2009/026235, WO 201 1000873 and PCT/US201 1/066597, 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 red emitter, or a combination thereof.

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

phosphorescent emitter which can emit over a variety of wavelengths, e.g., 400 nm to 700 nm, and in color such as blue, green, and red. 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 I 8%, or at least 20%.

In particular, 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%.

21 In some embodiments, the OLKD device described herein comprises a blue phosphorescent emitter. The external quantum efficiency of said OLKD 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%.

OLKD devices and measurements of OLBD parameters, including external quantum efficiency (KQE), are known in the art. See, for example, US Patent Publications

201 1/0012095; 201 1/0248249; 2009/0091918; and 2006/0286409. See also. Organic Light- Emitting Materials and Devices, Eds. Li and Meng, CRC, 2007, including for example, Chapter 7, pages 527-565, and Chapter 8, pages 567-581. A particular value for the luminance measured in units of cd m² can be chosen for comparing KQF. values such as, for example, 1,000 cd/m².

WORKING EXAMPLES

h^'XAMPLK 1 - Synthesis of Compound A and Compound B

A hyper-branch structure can be used to achieve an amorphous solid state.

Compound A and Compound B were synthesized to meet this goal, according to Scheme 1 and Scheme 2, respectively. The molecules were characterized with NMR, mass spectrometry (MS), cyclic voltammctry (CV) and elemental analysis (FA). Table 1 shows the reduction potentials for Compound A and Compound B. In the syntheses shown below thin layer chromatography is abbreviated as TLC.

Tabic 1 - The reduction potentials and DSC data for ambipolar branched molecules. Potentials are reported relative to that of the ferrocene/ferrocenium redox couple.

22

S Scheme 1 - Synthesis of Compound Λ

23

Scheme 2 - Synthesis of Compound B

Methyl 3,5-di(carbazol-9-yl)benzoate: To a solution of methyl 3,5-diiodobenzoate (20.0 g, 51.55 mmol), carbazole (20.0 g, 1 1 .6 mmol), Cu (80.0 g, 1.25 mol) and 18-crown-6

24 (300.0 mg, 1.15 mmol) in 1 ,2-dichlorobenzcnc (200.0 ml) was added potassium carbonate (80.0 g, 0.58 mol) under nitrogen and stirring. The reaction was carried out at 170 °C (oil bath) for 7 h. After cooling, the reaction mixture was filtrated. The solid residues were carefully washed with THF. THF and 1,2-dichlorobcnzene were evaporated from the combined nitration solution. The product was purified by silica gel column chromatography using toluene as elucnt. Final pure product was obtained in 19.0 g (78.8%) by

rccrystallization from acetonc/methanol.

¹ I I NMR (CDCI3): 58.37 (d, J = 1.6 1 Iz, 1 H), 8.15 (dd, J, = 7.2 Hz, J* - 0.8 Hz, 4 H), 8.02 (t, - 1.6 1 Iz, I H), 7.52 (dd, J, - 7.2 Hz, J₂ = 0.8 Hz, 4 H), 7.45 (td, J, = 7.2 Hz, J₂ - 1.6 Hz, 4 11), 7.32 (td, J,= 7.2 Hz, J₃ = 1.2 Hz, 4 H), 3.99 (s, 3 H, OCII3) ppm. ^I3C NMR (CDCIj): 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 ppm. MS (I I) m/z (%): 466.0 (100%) IM']. Anal. Calcd for C32H22N2O2: C, 82.38; II, 4.75; N, 6.00. Found: C, 82.34; H, 4.66; N, 6.03.

3,5-Dicarbazol-9-ylbenzhydrazidc: To a solution of methyl 3,5-di(carbazol-9- yl)benzoate (10.0 g, 0.52 mol) in dioxanc (100.0 ml) and ethanol (70.0 ml) was added hydrazine hydrate (20.0 ml). The reaction mixture was rcfluxed for 6 hours. The reaction mixture was cooled to room temperature and water (380.0 ml) was added. The white product solid was collected by filtration, washed with water and dried under vacuum. The yield of the reaction is 10.0 g ( 100 %). This compound was used for next step without any purification.

¹ H NMR (400 MHz, CDCI3) δ: 8.13 (dd, J, = 7.6 Hz, J₂ = 0.8 Hz, 4 11), 8.05 (d, J = 2.0 Hz, 2 H), 7.98 (t, J = 2.0 Hz, I 11), 7.52 (s, br, 1 H, Nil), 7.50 (dd, J, = 7.6 Hz, J₃ = 0.8 Hz, 4 11), 7.43 (td, J, - 7.6 Hz, J = 0.8 1 Iz, 4 H), 7.31 (Id, J, = 7.6 1 Iz, J₂ = 0.8 Hz, 4 H), 4.16 (br, 2 H, NII₂) ppm. ^,3C 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 ppm. NMR shows this compound contains methanol.

25

N'',N'^J-Bis(3,5-di(carbazol-9-yl)isophthalohydrazidc: To a solution of 3,5- Dicarbazol-9-ylbenzhydrazide (1.0 g, 2.14 mmol) in dry tetrahydrofuran (20.0 ml) was slowly added isophthaloyl chloride (217 mg, 1.10 mmol) at 0 °C under nitrogen. After addition of isophthaloyl chloride, the reaction was warmed to room temperature and the reaction mixture was stirred at room temperature for 23 hours. Pyridine (5.0 ml) was added and stirred for another I hour. The reaction mixture was poured into water (200.0 ml). The white solid was collected by filtration, washed with water and dried overnight under vacuum to give in 1.2 g (91.7 %) yield. This compound was used for next step without any purification.

Ή NM (400 MHz, DMSO-d₆) δ: 1 1.00 (s, 2 H, 2 x NH), 10.87 (s, 2 H, 2 x NH), 8.32 (d, J = 0.8 Hz, 4 H), 8.26 (dd J, = 8.0 Hz, J₂ = 0.4 Hz. 8 11), 8.15 (s, 2 11), 8.12 (s, 1 11), 7.94 (t, J - 8.0 Hz, 1 H), 7.63 (d, J - 8.0 Hz, 8 11), 7.50 (m, 10 H), 7.33 (t, J = 8.0 Hz, 8 H) ppm.

26 ^, ^^τ' N'^ί-Tris(3,5- li(carbazol-9-yl)ben7.o l) cnzcnc-l 3^-tricarboh drazidc: To a solution of 3,5-Dicarbazol-9-y Ibenzhydrazide ( 1.0 g, 2.14 mmol) in dry tetrahydrofuran (20.0 ml) was slowly added bcnzenc-l,3,5-tricarbon l chloride (189.4 mg, 0.71 mmol) at 0°C under nitrogen. After addition of benzene- 1,3,5-tricarbon I chloride, the reaction was warmed to room temperature and the reaction mixture was stirred at room temperature for 19 hours. Pyridine (5.0 ml) was added and stirred for another I hour. The reaction mixture was poured into water (200.0 ml). The white solid was collected by filtration, washed with water and dried overnight under vacuum to give in 1.1 g (91.0 %) yield. This compound was used for next step without any purification.

Ή N R (400 MHz, DMSO-d₆) 5: 1 1.04 (s, 6 H, 6 x Ni l), 8.66 (s, 3 H), 8.31 (d, J= 2.0 Hz, 6 11), 8.26 (d, J = 8.0 Hz, 12 H), 8.15 (t, J- 2.0 Hz, 3 H), 7.62 (d, ./= 8.0 Hz, 12 II), 7.47 (td, J, = 8.0 Hz, J = 1.2 1 Iz, 12 H), 7.32 (td, J_t = 8.0 1 Iz, J? = 1.2 Hz, 12 I I) ppm.

1 -Bis(5-(3 5-di(carbazol-9-yl)phenyl)- l,3,4-oxadazol-2-yl)benzene (Compound

A): N'',N'³-Bis(3,5-di(carbazol-9-yl)isophthalohydrazide (1.0 g, 0.94 mmol) was added in POClj (20.0 ml). The reaction was heated to 90 °C and kept at this temperature for 6 hours. After cooling down to room temperature the reaction mixture was poured into ice-water (600.0 ml). The solid formed was collected by vacuum filtration. The crude product was dried and purified by silica gel column using dichloromcthane hexancs (9.5:0.5) as cluent. After removal of solvents, pure product as white solid was obtained in 0.62 g (63.9%) yield.

'H MR (400 MHz, CDCI₃) 5: 8.88 (t, J " 1 Hz, I Π), 8.48 (d, J= 2.0 Hz, 4 H), 8.29 (dd. I = 8.0 Hz, J₂ = 1.6 Hz, 2 I I), 8.16 (dd, J, = 8.0 Hz, J₂ = 1.6 Hz, 8 H), 8.02 (t, J = 2.0 Hz, 2 11), 7.69 (t, J = 8.0 Hz, 1 11), 7.56 (d, J= 8.0 Hz, 8 H), 7.44 (Id, J, = 8.0 Hz, J? ~ 1.6 Hz, 4 H), 7.32 (td, J, ^« 8.0 1 Iz, J₂ - 1. 1 IT, 8 H) ppm. MS-MALDI (m z): [M]⁴ Calcd for

27 C70H42N8O2: 1027.3. Found 1027.3. Anal. Calcd for C70H42IM8O2: C, 81.85; H, 4.12; N, 10.91. Pound: C, 82.02; H, 4.01 ; N, 10.90.

1 ,3₅5-Tris(5-(3,5-di(carbazol-9-yl)phenyl)-l »4-oxadazol-2-yl)benzcnc

(Compound B): N' ^,,N^,3,N' -Tris(3,5-di(carbazol-9-yl)benzoyl)bcnzcnc-1 ,3,5- tricarbohydrazidc (0.9 g, 0.58 mmol) was added in POCI3 (20.0 ml). The reaction was heated to 1 10 °C and kept at this temperature for 8 hours. After cooling to room temperature the reaction mixture was poured into ice-water (600.0 ml). The solid formed was collected by vacuum filtration. The crude product was dried and purified by silica gel column using dich!oromeihanc/hcxanes (95:0.5) as elucnt. After removal of solvents, pure product as white solid was obtained in 0.7 g (84.5%) yield.

Ή NMR (400 MHz, C CI₃) 6: 8.60 (s, 3 H), 8.48 (d, J= 1.2 Hz, 6 H), 8.09 (d, J= 8.0 Hz, 12 I I), 8.01 (t, J= 1.2 Hz, 3 H), 7.56 (d, J= 8.0 Hz, 12 H), 7.40 (t, J= 8.0 Hz, 12 H), 7.27 (t, J = 8.0 Hz, 12 H) ppm. ^I3C NMR (100 MHz, CDCI₃) 6 163.90, 162.93, 140.58, 140.07, 128.09, 127.17, 126.65, 126.34, 125.15, 123.81, 123.38, 120.83, 120.57, 109.38 ppm. MS- MALDI (m/z): [Μ\' Calcd for C^H_MN OJ: 1500.5, 1501.5. Found 1500.5, 1501.5. Anal. Calcd for CIO₃H«) ,₂0J: C, 81.58; H, 4.03; N, 1 1.19. Found: C, 81.49; H, 3.93; N, M. I I.

28 KXAMPU- 2- Synthesis of Compound C

Compound C was synthesized according to Scheme 3. Yield: 1.102 g, 58 %.

Characterization: Ή and ^,3C NMR, EA, HRMS, UV-Vis, CV, TGA, and DSC.

Scheme 3 - Synthesis of Compound C

COOCH_j

^-^i : 3-lodobenzoic acid (50 g, 0.20 mol) was mixed with 300 mL methanol followed by the addition of 1 mL of concentrated sulfuric acid. The reaction was heated at 80 °C for 24 hours. During this process, the mixture of methanol and water was replaced by methanol twice. When the reaction appeared complete by TLC, the solvents were removed. The addition of 600 mL I feO and overnight stirring led to the formation of large amount of white precipitate. The product was readily isolated by filtration and washed by water to give a white solid (51.3 g, 97 %).

29 Ή NM (300 MHz, C CI₃): δ 8.34 (s, br, III), 7.97 (d, J= 7.5 I Iz, I H), 7.85 (d, J= 7.2 Hz, I H), 7.151 (td, J/ - 7.8 Hz, J₂ = 2.7 Hz, I II), 3.89 (s, 311). GC-MS (m/z): [M'j calcd. for C₈H7l0₂: 262.0, found: 262.0.

(25.0 g, 0.0954 mol) and carbazole (23.928 g, 0.143 mol) were added into o-dichlorobenzcne (200 mL) under N₂. Then Cu (60.670 g, 0.955 mol), 2C0₃ ( 1 1.837 g, 0.954 mol), and 18-crown-6 (0.321 g, 0.0012 mol) were added into the reaction mixture. The reaction was heated to 170 °C for 48 hours. When TLC showed most starting material had been consumed, heating was ceased. The reaction mixture was cooled to room temperature and added THF (150 mL), stirring for I h. After filtering off all inorganic solids, the solvent was removed by evaporation to give a crude product. The crude product was then purified by silica gel chromatography (dichloromethane : hexanc ^ 2 : 1) to give a mixture of the product and carbazolc. After the solvents being removed, the product was further rccrystallizcd from acetone mcthanol to give a colorless needle-shape crystal (19.3 g, 67 %).

Ή NMR (400 MHz, CDCI3): δ (ppm): 8.25 (s, br, IH), 8.14 (d, J= 7.6 Hz, 3H), 7.77 (d, J- 8.0 1 Iz, I H), 7.68 (t, J = 8.0 Hz, 1 H), 7.39 (m, 411), 7.30 (td, J\ = 8.0 Hz, J₂ = 1.6 Hz, 2H), 3.94 (s, 311). GC-MS (m/z): [M*J calcd. for C2₀H1S O2: 301.34, found: 301.1.

(18.5 g, 0.061 mol) and N₂H₄ H₂0 (27 ml, 0.557 mol were dissolved into cthanol (120 mL) and />-dioxane (120 mL). The reaction mixture was heated to reflux for 48 hours. When the reaction appeared to be complete by TLC, the solvent was evaporated to give a light yellow, sticky gel. The addition of 300 mL H2O led to the precipitation of a white solid. The product was collected by filtration and washed by water. The final product was obtained after repeatedly crushing the large chunks of the solid and drying it under vacuum as an off-white powder (18.2 g, 98%).

Ή MR (300 MHz, CDCI3): S (ppm): 8.13 (d, J= 7.8 Hz, 2H), 7.96 (s, br, I H), 7.80 (d, J- 7.5 IIz, I H), 7.73 (d, J= 6.3 Hz, 1 H), 7.68 (q, J= 7.8 Hz, 1 H), 7.50 (s, br, I H), 7.37 (m, 4H), 7.29 (td, J_\ = 7.8 Hz, J₂ = 1.5 Hz, 2H), 4.14 (s, br, 2H). ^,3C NMR (100 MHz, CDCI₃): 167.95, 140.77, 138.60, 134.79, 130.65, 126.35, 125.88, 125.74, 123.75, 120.65, 120.56, 109.72. Ana!. Calcd. for C,glI,5N₃0: C, 75.73; I I, 5.02; N, 13.94. Found: C, 75.43; H, 5.03; N, 13.87. IIRMS (El) Calcd. for 0«Ηι$Ν₃0 [M ]: 301.1215, found: 301.1220.

(2.006 g, 0.0067 mol) were dissolved into 40 mL anhydrous THF under N2. After cooling the reaction mixture to 0 °C for 30 min, trimesoyl chloride (0.587 g, 0.0022 mol) was quickly added into the reaction mixture. Then the reaction mixture was warmed to room temperature and stirred overnight. When the reaction appeared to be complete by TLC, 5 mL of pyridine was added to neutralize the system. The addition of 1 0 ml, water gave rise to a light brown sticky precipitate. The product was collected by nitration and washed by water. The crude product was obtained after drying it under vacuum as a light brown powder (2.51 g).

Ή NMR (400 MHz, DMSO- δ 10.95 (s, 311), 10.86 (s, 3H), 8.65 (s, 311), 8.27 (d, J = 7.6 Hz, 6H), 8.15 (s, 3H), 8.10 (d, J- 7.6 Hz, 3H), 7.90 (d, J= 8.0 I Iz, 311), 7.87 (q. J - 8.0 Hz, 3H), 7.48—7.42 (m, 12H), 7.32 (t, J= 6.4 Hz, 6H). ^I3C NMR (100 MHz, DMSC i⁶): 164.91, 149.62, 140.05, 137.18, 136.15, 134.39, 133.48, 130.75, 130.39, 126.85, 126.41, 125.50, 122.85, 120.64, 120.34, 109.65.

(2.00 g, 1.88 mmol) was dissolved into phosphoryl chloride (30 mL, 0.322 mol) under N₂ and the reaction mixture was heated to 90 °C overnight. ITien the reaction mixture was poured into 900 mL ice slowly with interval shaking to give a yellow precipitate. After warming to room temperature the crude product was isolated by filtration and washed by water. Then the final product was purified by silica gel chromatography (dichloromcthane: ethyl acetate = 9.S : 0.5) and isolated as a light yellow solid (1.102 g, 58 %).

*H NMR (400 MHz, CDCI3): 69.02 (s, 3H), 8.43 (s, 3H), 8.26 (t, J= 4.8 Hz, 3H), 8.15 (d, J- 7.6 Hz, 6H), 7.81 (dt, J = 4.8 Hz, 611), 7.45-7.3 (m, 1211), 7.30 (td, J, = 8.0 Hz, J2 - 1.6 Hz, 611). ^I3C MR (100 MHz, CDCI3): δ 165.07, 163.26, 140.82, 139.21, 131.27, 131.1 1, 127.87, 126.46, 126.24, 125.98, 125.49, 123.90, 120.72, 109.76. Anal. Calcd. for CttHnNrffe C, 78.79; H, 3.91 ; N, 12.53. Found: C, 78.95; H, 3.95; N, 12.52. HRMS (El) Calcd. for ^HwN f *]: 1005.3176, found: 1005.3121.

Additional characterization data:

1. U V-Vis: 338 nm, 292 nm, 241 nm (CI 1₂CI₂, measured at room temperature)

2. Fluorescence: 468 nm (Excitation at 330 nm) in CH₂C1₂

3. DSC: T₈ = I80 °C

4. TGA: 5 % mass lost at 433 °C

5. CV: Oxidation potential vs. Ferrocene: 0.89 V in CI I2CI2, measured at room temperature. Reduction potential vs. Ferrocene: -2.04 V in THF, measured at room temperature

EXAMPLE 3- Synthesis of Compound P

Compound D was synthesized according to Scheme 4.

32

Scheme 4 - Synthesis of Compound D

o : Diphenic acid (12.1 14 g, 0.050 mol), thionyl chloride (50.0 mL, 0.688 mol), and 1 mL triethyl amine were dissolved into 500 mL anhydrous dichloromethane under N₂. After heating the reaction mixture to reflux for 4 hours, the CH2CI2 was removed on a rotoary evaporator and then extra SOCI₂ was removed by distillation with a Dean-stark trap under N₂. The crude product was left in the flask under N₂.

¹ I I NMR (400 Ml Iz, CDCI₃): S 8.27 (dd, J_x = 8.0 Hz, J₂ - 0.8 Hz, 211), 7.64 (td, J\ - 7.6 1 Iz, J₂ = 1.2 I Iz, 211), 7.54 (td, J_\ - 7.6 Hz, J₂ - 0. 1 Iz, 211), 7.19 (dd, J| = 7.6 Hz, J₂ - 0.8 Hz, 211).

(2.008 g, 0.0067 mol) were dissolved into 40 mL anhydrous Tl IF under 2. After cooling down the reaction mixture to 0

°C for 30 min. 0 (1.375 g, 0.0033 mol) was quickly added into the reaction mixture. Then the reaction mixture was warmed to room temperature and stirred overnight. When the reaction appeared to be complete by TLC, 2 mL of pyridine was added to neutralize the

33 system. The addition of 160 mL water gave rise to a light yellow precipitate. The product was collected by filtration and washed by water. The final product was obtained after repeatedly crushing chunks of the solid and drying it under vacuum as a light brown powder (2.38 g, 89 %).

Ή NMR (400 MHz, DMSO-*/⁶): δ 10.68 (s, 2H), 10.45 (s, 2H), 8.25 (d, J= 7.6 Hz, 4H), 8.06~7.99 (m, 4H), 7.85^-7.76 (m, 4H), 7.64 (dd, , = 6.4 Hz, J₂ = 2.4 Hz, 2H), 7.52-7.28 (m, 18H). ¹³C NMR (100 MHz, DMSO-*/⁵): 168.26, 164.71, 140.08, 139.02, 137.07, 134.17, 133.90, 130.62, 130.37, 130.30, 130.06, 128.02, 127.59, 126.93, 126.40, 125.60, 122.82, 120.61, 120.32, 109.65.

(2.00 g, 2.47 mmol) was dissolved into phosphoryl chloride (30 mL, 0.322 mol) under 2 and the reaction mixture was heated to 90 °C overnight. Then the reaction mixture was poured into 900 mL ice slowly with interval shaking to give a yellow precipitate. After warming to room temperature, the crude product was isolated by filtration and washed by water. Then the final product was purified by silica gel chromatography (dichloromethane: ethyl acetate - 9.5 : 0.5) and isolated as a white solid (0.770 g, 41 %).

Ή NMR (400 MHz, CDCb): S (ppm): 8.18 (d, J= 8.0 Hz, 4H), 8.00 (d, J= 7.6 Hz, 2H), 7.83 (dt, J i = 7.2 Hz, J₂ - 1.6 Hz, 2H), 7.63 (m, 4H), 7.42 (t, J = 72 Hz, 4H), 7.42 (s, 2H), 7.32 (t, J = 7.2 Hz, 4H), 7.28-7.21 (m, 8H), 6.83 (td, J, = 7.2 Hz,J₂ - 1.6 Hz, 2H), ^,3C NMR (100 MHz, CDCb): δ 164.65, 163.83, 140.91, 140.19, 138.74, 131.60, 130.91, 130.83, 130.49, 129.24, 128.57, 126.40, 125.79, 125.70, 125.51, 123.70, 122.68, 120.64, 120.60, 109.93. Anal. Calcd. for C52H32N6O2: C, 80.81; H, 4.17; N, 10.87. Found: C, 80.60; H, 4.09; N, 10.84. HRMS (EI) Calcd. for CsiHsiNeOa [ *]: 772.2587, found: 772.2575.

Additional characterization data:

1. UV-Vis: 339 nm, 292 nm, 240 nm (CH₂CI₂, measured at room temperature)

2. Fluorescence: 424 nm (Excitation at 330 nm) in CH2CI₂

3. DSC: Tg= 121 °C

4. TGA: 5 % mass lost at 419 °C

5. CV: Oxidation potential vs. Ferrocene: 0.93 V in CH₂CI2, measured at room temperature. Reduction potential vs. Ferrocene: -2.46 V in THF, measured at room temperature.

34 EXAMPLE 4- Synthesis of Compound E

Compound E was synthesized according to Scheme 4.

Scheme 4 - Synthesis of Com pound E.

COOCH, . id (29 ml., 0.554 mol) dissolved into 500 ml, dichloromcthanc under N₂. 4-Amino-methylbcnzoate (33,35 g, 0.221 mol) was added into the reaction mixture slowly. The reaction mixture was heated to reflux for 4 hours. The addition of an additional 500 mL dichloromcthane dissolved the precipitate after cooling to room temperature. The reaction mixture was stirred for 1 hour and then washed with 400 mL saturated aqueous solution of Na2S2<¾ followed by water washing the organic layer twice. The organic fractions were combined and concentrated to about I L. After rccryslallization the product then was collected as needle-like yellow crystals (72.5 g, 83 %). ¹11 MR (400 Ml Iz, CDCI₃): S (ppm): 8.28 (s, 211), 5.04 (s, br, 2H), 3.84 (s, 311).

35

coocH,; To a 150 ml. THF solution ofisoamyl nitrite (242 ml,, 1.80 mol) at

reflux under N₂ was added dropwisc the 500 mL TI IF solution of COOCH, (72.5 g, 0.180 mol) slowly. The reaction mixture was heated to reflux for 8 hours. After cooling the mixture to room temperature the solution was concentrated and left overnight yielding light yellow solids, ITie light yellow solid then was purified by silica gel chromatography

(dichloromethane : hexanc = 6:4) to give a white solid (43.2 g, 62 %). Ή N R {400 MHz, CDC ): S (ppm): 8.30 (s, 2H), 8.21 (s, 1 H), 3.90 (s, 3H).

COOCH. : Mixed COOCH, ₍₂2.01 g, 0.0567 mol), carbazole (28.49 g,

0.170 mol). Copper (36.06 g, 0.567 mol), potassium bicarbonate (78.51 g, 0.568 mol), and 18-crown-6 (0.670 g, 0.0025 mol) in 250 mL anhydrous o-dichlorobenzcne under N₂. The reaction mixture was heated to 165 °C overnight. Then the reaction mixture was cooled to room temperature and added TH F ( 150 m L), stirring for 1 h. After filtering off inorganic solids, the solvent was removed by evaporation to give a crude product. ^'ITie crude product was then purified by silica gel chromatography (ethyl acetate: hexane = 3 : 7) to give a mixture of the product and carbazole. Alter the solvents were removed, the product was further rccrystallizcd from acctonc/mcthanol to give a light yellow needle-shape crystal (13.5 g, 51 %).

Ή NMR (300 MHz, CDCb) 8 (ppm): 8.37 (d, J= 2.0 Hz, 2H), 8.15 (d, J- 7.7 Hz, 4H), 8.02 (t, J- 2.0 Hz, I H), 7.52 (d, J- 8.1 Hz, 4H), 7.45 (t, J= 8.0 Hz, 4H), 7.32 (t, J 8.0 Hz, 4H), 3.99 (s, 3H).

(13.5 g, 0.0289 mol) and N₂H₄ H₂0 (23.5 mL, 0.484 mol) were dissolved into cthanol (120 mL) and / -dioxanc (120 mL). The reaction mixture was heated to reflux for 48 hours. After cooling to room temperature, the removal of some solvent and the addition of 300 mL H₂0 led to the precipitation of a white solid. The

36 product was collected by filtration and washed by water. The final product was obtained after repeatedly crushing chunks of the solid and drying it under vacuum as an off-white powder (13.3 g, 98 %).

Ή NMR (400 MHz, CDClj) 8 8.14 (d, J- 8.0 Hz, 4H), 8.05 (d, J= 1.8 Hz, 2H), 7.98 (t, J = 4.0 I Iz, 111), 7.50 (d, J = 8.0 Hz, 5H), 7.43 (t, J = 8-0 Hz, 4H), 7. 1 (t, J = 8.0 Hz, 411), 4.15 (s, br, 2H). Anal. Calcd. for C31H22N4O: C, 79.81; H, 4.75; N, 12.01. Pound: C, 79.67; H, 4.62; N. 1 1.83.

mixture to 0 °C for 30 min, 6 (0.897 g, 0.00215 mol) was quickly added into the reaction mixture. Then the reaction mixture was warmed to room temperature and stirred overnight. When the reaction appeared to be complete by TLC, pyridine (2 mL) was added to neutralize the system. I^*he addition of water ( 160 mL) gave rise to a light yellow precipitate. The crude product was collected by filtration and washed by water. The final product was obtained after repeatedly crushing chunks of the solid and drying it under vacuum as a light brown powder (2.46 g, crude product).

Ή NMR (400 MHz, DMSO- £ 10.91 (s, 2H), 10.62 (s, 2H), 8.22 (d, J= 7.6 l lz, 8H), 8.4 (m, 2H), 7.54~7.40 (m, 23H), 7.33~7.22 (m, 13H).

(2.00 g, 1.76 mmol) was dissolved into phosphoryl chloride (30 mL, 0.322 mol) under N₂ and

37 the reaction mixture was heated to 90 °C overnight. Then the reaction mixture was poured into ice (900 ml.) slowly with interval shaking to give a yellow precipitate. After warming to room temperature, the crude product was isolated by filtration and washed with water. Then the final product was purified by silica gel chromatography (dichloromethane: ethyl acetate =

9.5 : 0.5) and isolated as a white solid (0.865 g, 45 %).

Ή NMR (400 MHz, CDCI₃): S 8.17 (d, = 8.0 Hz, 8H), 7.91 (m, 4H), 7.76 (d, J -

1.6 Hz, 4H), 7.45 (m, 1611), 7.34 (m, 8H), 7.25 (m, 2H), 7.08 (t, J- 8.0 Hz, 2H), 6.48 (t, 7- 8.0 Hz, 2H). ^,3C{H} NMR ( 100 MHz, CDCI3): S 164.90, 163.83, 140.57, 140.16, 131.85, 130.72, 129.36, 128.64, 128.31, 127.23, 126.64, 123.99, 123.81, 122.31, 121.05, 120.80,

109.88. Anal. Calcd. for CyoH^NgO C, 82.74; H, 4.20; N, 10.16. Found: C, 82.42; H, 4.13; N, 10.05. HRMS (MAIJD1) Calcd. for C76H 6H1O2 [M*]: 1 102.374, found: 1 102.372.

Additional characterization data:

1. UV-Vis: 337 nm, 2 1 nm, 232 nm (CI Ι₂0₂, measured at room temperature)

2. Fluorescence: 432 nm (Excitation at 330 nm) in CI 1₂CI₂

3. DSC: T_B = 183 ^eC

4. TGA: 5 % mass lost at 451 °C

5. CV: Oxidation potential vs. Ferrocene: 0.96 V in CH2CI2, measured at room temperature. Reduction potential vs. Ferrocene: -2.35 V in THF, measured at room temperature.

HXAMPLE 5- Synthesis of Compound F

Compound F was synthesized according to Scheme 5.

38 Scheme 5 - Synthesis of Compound F.

To a solution of pyrene (6.00 g, 297 mol) in dichloromcthanc ( 120 ml.) was added MeCN ( 120 mL) and water ( 180 mL). Then added Nal0 (60.0 g, 281 mmol) and RuCb (240 mg, 1.16 mmol) into the reaction mixture. The reaction mixture was heated to reflux overnight with stirring. The resulting yellow solid was isolated by filtration and subsequently extracted by acetone three times (750 mL). The combined extract gave an orange-yellow solid after evaporation as a crude product. The crude product was refluxed in CH₂CI₂ for 24 h and filtered to give a light yellow solid (3.6S0 g, 37 %). 'II MR (400 MHz, DMSO- 6 12.36 (s, br, 4H), 7.97 (d, J= 8.0 I Iz, 4H), 7.45 (t, ./= 8.0 Hz, 2H).

The tctraacid HOOC (3.30 g, 0.010 mol), thionyl chloride (10.2 mL, 0.140 mol), and triethyl amine (2.1 mL) were dissolved into anhydrous dichloromethanc (200 mL) under N₂. After heating the reaction mixture to reflux for 4 hours, the CH2CI2 was removed by evaporation and then extra SOCl₂ was removed by distillation with a Dean-stark trap under N₂. The crude product was stored under N2. Ή NMR (400 MHz. CDCI₃): <J 8.50 (dd, J, = 8.0 Hz, J₂ = 4.0 I Iz, 411), 7.77 (td, ./j = 8.0 Hz, J₂ = 1.6 Hz, 2H).

(2.00 g, 0.0066 mol) were dissolved into 40 mL anhydrous TI IF under 2. After cooling the reaction mixture to 0

°C for 30 min, coci (1.24 g, 0.00166 mol) was quickly added into the reaction mixture. Then the reaction mixture was warmed to room temperature and stirred overnight.

39 When the reaction appeared to be complete by TLC, pyridine ( 1 mL) was added to neutralize the system. The addition of deionized water (160 mL) gave rise to a light yellow precipitate. The product was collected by filtration and washed with water. The final product was obtained after repeatedly crushing chunks of the solid and drying it under vacuum as a light brown powder (2,62 g, 1 8 %, crude product).

'II NMR (400 MHz, DMSO-t/⁵): δ 10.85 (s, 411), 10.67 (s, 4H), 8.24 (d, J = 8.0 Hz. 811), 8.04 (s, br, 411), 7.99 (d, br, J= 8.0 Hz, 411), 7.85~7.67 (m, I2H), 7.60 (t, J= 8.0 Hz, 2H), 7.43-7.27 (m, 24H). ^,3C{H} NMR (100 MHz, DMS(W): S 167.65, 164.98, 140.07, 137.06, 135.60, 133.65, 133.34, 130.59, 129.62, 128.52, 126.99, 126.34, 125.73, 122.76, 120.55, 120.24, 109.61.

(2.00 g, 1.37 mmol) was dissolved into phosphoryl chloride (30 mL, 0.322 mol) under N₂ and the reaction mixture was heated to 90 °C overnight. l^*hen the reaction mixture was poured into ice (900 mL) slowly with interval shaking to give a yellow precipitate. After warming to room temperature, the crude product was isolated by filtration and washed by water, Then the final product was purified by silica gel chromatography (dichloromethane: ethyl acetate = 9.5 : .5) and isolated as a white solid (0.697 g, 37 %).

Ή NMR (400 MHz, CDC1₃): 0 8.14 (d, J= 8.0 Hz, 8H), 8.04 (d, J= 8.0 Hz, 4H), 7.86 (d, br, ./ = 8.0 Hz, 4H), 7.67-7.59 (m, 12H), 7.37 (t, J= 8.0 Hz, 4H), 7.36 (d, J= 8.0 Hz, 4H), 7.28 (m, 16H), 6.81 (t, J= 8.0 Hz, 2H). ^,3C{H} NMR (100 MHz, CDCb): 6

40 163.97, 163.60, 140.80, 138.87, 136.57, 132.53, 131.05, 130.70, 129.90, 126.44, 125.82, 125.43, 125.35, 125.15, 123.74, 120.70, 109.82. Anal. Calcd. for Gal^N^O-,: C, 79.41 ; II, 3.91 ; N, 12.08. Found: C, 79.15; II, 3.82; N, 1 1.98. IIRMS (MALDI) Calcd. for

C_9Sn₅s i₂0₄ [Mir]: 1391.4469, found: 1391.4523.

Additional characterization data:

1. UV-Vis: 338 nm, 292 nm, 240 nm (CI feCh, measured at room temperature)

2. Fluorescence: 440 nm (Excitation at 340 nm) in CII2CI2

3. DSC: T₈ = 166 °C

4. TGA: 5 % mass lost at 435 °C

5. CV: Oxidation potential vs. Ferrocene: 0.88 V in CH2CI2, measured at room temperature. Reduction potential vs. Ferrocene: -2.29 V in THF, measured at room temperature.

F:XAMPLH 6

LiF/Al/Ag C2.5/60 nm/100

nmj

BCP (50 nm)

Compound D :.r(pppy)₃ 6 wt. % (20

nm)

G (35 nm)

ITO

Glass

Indium tin oxide (ITO)-coated glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of -15 Ω sq were used as substrates for the OLED fabrication. The ITO substrates were masked partially with kapton tape and the exposed ITO was etched in acid vapor ( 1 :3 by volume, I INO3: 1 IC1) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently. ITO substrates were O2 plasma treated for 2 min.

4I

(target x = 0.9) Polymer G

Polymer G was synthesized according to US Provisional Application Serial No.

61/579,402 filed December 22, 201 1 (Mardcr et al.), incorporated by reference in its entirety. Polymer G was processed in the glove box under nitrogen. 5 mg of TAG (DPI-TPFPB) (Aldrich) was dissolved in 10 ml of anhydrous chlorobenzene (Aldrich) then 10 mg of Compound G was dissolved in 1ml of previously prepared TAG solution. Around 35 nm thick films of the hole-transport material were spin-coated at 1000 rpm, acceleration 1540 rpm/sec for 60 sec. The films were then dried on a hot plate at 1 10 °C for 30 minutes followed by thermal curing at 200 °C for 30 min. A watch glass was used during the curing process over the samples in order to avoid excessive heat losses.

The emissive layer, consisting of the Compound D host and Ir(pppy>3 emitter was prepared in the following way in the glove box: 10 mg of Compound D was dissolved in I ml chlorobenzene and 10 mg of lr(pppy)3 in 1 ml of chlorobenzene. 64 μΙ of Ir(pppy)3 was added to 1 ml of the solution of Compound D. The solution was then spin-coated onto the hole transport layer, HTL, at 2000 rpm, 1000 rpm / sec, 60 sec. The films were dried at 100 °C for 10-15 min.

42 The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF (Aldrich) and aluminum were thermally evaporated at I A/s, 0.2 A/s and 2 A s respectively. The pressure in the vacuum chamber was 1 * 10^"7 Torr. The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen, where current- voltage and lumi ance-voltage characteristics were measured with a cithley 2400 Source Meter and a calibrated photodiode (I^' S 100 from Thorlabs, Inc.). The performance of the device is shown in Figure I . The plot on the left shows current density voltage characteristic of the diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (EQE) (empty symbols) as a function of applied voltage. The value of EQE between 10 and 1000 cd/m² is between 13% and 10% and maximum luminance shown is above 10,000 cd/m². This high level of performance in terms of efficiency and luminance proves the suitability of these compositions for organic light-emitting diode applications.

EXAMPLE 7

LiF/Al/Ag (2.5/60 nm/100

nml

BCP (50 nm)

Compound D :Ir(pppy)₃ 6 Wt. % (20

nm)

^Compound G(35

nm)

PEDOT: PSS AI 4083 (50

nm)

ITO

Glass

Indium tin oxide (ITO)-coated glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of -15 Ω/sq were used as substrates for the OLEDs fabrication. The ITO substrates were masked partially with kapton tape and the exposed ITO was etched in acid vapor ( 1 :3 by volume, HNO3: HCI) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently, ITO substrates were 0₂ plasma treated for 2 min.

43 Immediately after 0₂ plasma treatment of the ITO slides, PEDOT:PSS AI4083 (Clevios) was spin-coated at 5000 rpm, acceleration - 928 rpm/s for 60 sec. Subsequently, the films were heated on a hot plate at I40°C for IS min. PEDOT:PSS was deposited in air.

Compound G was processed in the glove box under nitrogen. 5 mg of TAG (DPI- TPFPB) (Aldrich) was dissolve in 10 ml of anhydrous chlorobenzene (Aldrich) then 10 mg of Compound G was dissolved in 1ml of previously prepared thermal acid generator, TAG, solution. Around 35 nm thick films of the hole-transport material were spin-coated at 1000 rpm, acceleration 1540 rpm/sec for 60 sec. The films were then dried on a hot plate at 1 10 °C for 30 minutes followed by thermal curing at 200 °C for 30 min. A watch glass was used during the curing process over the samples in order to avoid excessive heat loses.

The emissive layer, consisting of the Compound D host and Ir(pppy)3 emitter was prepared in the following way in the glove box: 10 mg of Compound D was dissolved in I ml chlorobenzene and 10 mg of Ir(pppy)3 in 1 ml of chlorobenzene. 64 μΙ of Ir(pppy).¾ was added to 1 ml of the solution of Compound D. The solution was then spin-coated onto the HTE at 2000 rpm, 1000 rpm / sec, 60 sec. The films were dried at 100 °C for 1 - 15 min.

The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF

(Aldrich) and aluminum were thermally evaporated at 1 A/s, 0.2 A/s and 2 A/s respectively. The pressure in the vacuum chamber was 1 x 10^"7 Torr. The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen, where current- voltage and luminance-voltage characteristics were measured with a eithlcy 2400 Source Meter and a calibrated photodiodc (FDS 100 from Thorlabs, Inc.). The performance of the device is shown in Figure 2. The plot on the left shows current density voltage characteristic ofthc diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (EQR) (empty symbols) as a function of applied voltage, ^'fhe value of EQE between 10 and 1000 cd/m² is between 9% and 6% and maximum luminance shown is above 10,000 cd m². This high level of performance in terms of efficiency and luminance proves the suitability of these compositions for organic light-emitting diode applications.

44 EXAMPLE 8

Indium tin oxide (ITO)-coatcd glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of -15 i2/sq were used as substrates for the OLEDs fabrication. The ITO substrates were masked partially with kapton tape and the exposed ITO was etched in acid vapor ( 1 :3 by volume, HN<¾: 11C1) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently, ITO substrates were 0₂ plasma treated for 2 min.

Polymer H

Polymer 11 was synthesized according to US Provisional Serial No. 61/579,394 filed December 22, 201 1 (Marder et al.), incorporated by reference in its entirety. Polymer H was processed in the glove box under nitrogen. 10 mg of Polymer H was dissolved in I ml of anhydrous chlorobenzene (Aldrich). 35 nm thick films of the hole-transport material were spin-coated at 1500 rpm, acceleration 1,000 rpm/scc for 60 sec. The films were then heated on a hot plate at 150 °C for 15 minutes.

45

The emissive layer, consisting of a host - Compound D and an emitter - lr(ppy)3 (Lumtec) was deposited by co-evaporation of the two components at 0.94 A/s and 0.06 A/s respectively, llie electron transport layer, BCP (Aldrich), the electron-injection layer, LiF (Aldrich), Al (Kurt I-esker) and Ag (Alfa Acsar) were thermally evaporated at 1 A/s, 0.2 A/s, 2 A/s and 2 A/s respectively. The pressure in the vacuum chamber was 1 * 10^"7 Torr. The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen, where current-voltage and luminance-voltage characteristics were measured with a Kcithlcy 2400 Source Meter and a calibrated photodiode (FDS 100 from Thorlabs, Inc.). The performance of the device is shown in Figure 3. The plot on the left shows current density voltage characteristic of the diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (liQE) (empty symbols) as a function of applied voltage. The value of EQE between 10 and 1000 cd m² is between 13% and 1 1% and maximum luminance shown is above 10,000 cd/m². This high level of performance in terms of efficiency and luminance proves the suitability of these compositions for organic light- emitting diode applications.

1-ΧΑΜΡΙ.Π 9

LiF/Al/Ag [2.5/40 nm/100

nm]

BCP (40 nm)

D.:FIrpic 11 vol. % (20 ompound H(35 nm)

1TO

Glass

Indium tin oxide (ITO)-coated glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of -15 Ω/sq were used as substrates for the OLliDs fabrication, llie ITO substrates were masked partially with kapton tape and the exposed ΠΌ was etched in acid

46 vapor ( 1 :3 by volume, HNO3: MCI) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently, ΙΊΌ substrates were (¼ plasma treated for 2 min.

Polymer 11 was processed in the glove box under nitrogen. 10 mg of Polymer 11 was dissolved in 1ml of anhydrous chlorobenzene (Aldrich). 35 nm thick films of the hole- transport material were spin-coated at 1500 rpm, acceleration 1,000 rpm/scc for 60 sec. The films were then heated on a hot plate at 150 °C for 15 minutes.

The emissive layer, consisting of a host - Compound D and an emitter - Plrpic (Lumtec) was deposited by co-evaporation of the two components at 0.88 A/s and 0.12 A/s respectively. The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF (Aldrich), Al (Kurt I-esker) and Ag (Alfa Aesar) were thermally evaporated at 1 A/s, 0.2 A/s, 2 A/s and 2 A/s respectively. The pressure in the vacuum chamber was 1 10^'7 Torr. The active area of the tested devices was about 0.1 cm³. The devices were tested in a glove box under nitrogen, where current-voltage and luminance-voltage characteristics were measured with a Kcithlcy 2400 Source Meter and a calibrated photodiode (FDS 100 from Thorlabs, Inc.). The performance of the device is shown in Figure 4. The plot on the left shows current density voltage characteristic of the diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (RQF.) (empty symbols) as a function of applied voltage. The value of EQE between 10 and 1000 cd/m² is between 4% and 6% and maximum luminance shown is above 10,000 cd/m². This good level of performance in terms of efficiency and luminance proves the suitability of these compositions for organic light- emitting diode applications.

47 KX AMPLE 10

LiF/Al/Ag (2.5/40 nm/100

nm]

BCP (40 nm)

Compound C :lr(ppy)₃ 6 vol. % (20

nm)

H (35 nm)

ITO

Glass

Indium tin oxide (ITO)-coatcd glass slides (Colorado Concept Coatings LLC) with a sheet resistivity o -15 Ω sq were used as substrates for the OLK s fabrication. The ITO substrates were masked partially with kapton tape and the exposed ITO was etched in acid vapor (1 :3 by volume, HNO3. HCI) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently, ITO substrates were O2 plasma treated for 2 min.

Polymer II was processed in the glove box under nitrogen. 10 mg of Polymer H was dissolved in I ml of anhydrous chlorobcnzene (Aldrich). 35 nm thick films of the hole- transport material were spin-coated at 1500 rpm, acceleration 1,000 rpm/sec for 60 sec. The films were then heated on a hot plate at 150 °C for 15 minutes.

The emissive layer, consisting of a host - Compound C and an emitter - Ir(ppy)3 (Lumtcc) was deposited by co-evaporation of the two components at 0.94 A/s and 0.06 A/s respectively. The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF (Aldrich), Al (Kurt Lcskcr) and Ag (Alfa Acsar) were thermally evaporated at 1 A/s, 0.2 A/s, 2 A/s and 2 A s respectively. The pressure in the vacuum chamber was I * 10^"7 Torn The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen, where current-voltage and luminance-voltage characteristics were measured with a Kcithlcy 2400 Source Meter and a calibrated photodiode (FDS 100 from Thorlabs, Inc.). The performance of the device is shown in Figure 5. The plot on the left shows current density voltage characteristic of the diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (liQE) (empty symbols) as a function of applied voltage. The value of EQE between 10 and 1000 cd/m² is between 1% and 6% and maximum luminance shown is above 10,000 cd m². This good level of performance in terms

48 of efficiency and luminance proves the suitability of these compositions for organic light- emitting diode applications.

EXAMPLE 1 1

LiF/AI/Ag (2.5/60 nm/100

nm]

BCP (50 nm)

—Compound E :Ir(pppy)₃ 6 wt. % (20

nm)

•Compound G(35 nm)

PEDOT: PSS AI 4083 (50 nm)

ITO

Glass

Indium tin oxide (ITO)-coated glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of -15 Ω sq were used as substrates for the OLEDs fabrication. The ITO substrates were masked partially with kapton tape and the exposed ITO was etched in acid vapor ( 1 :3 by volume, I INO3: 11CI) for 5 min at 60 °C. ITie substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently. ITO substrates were Oi plasma treated for 2 min.

Immediately after 0₂ plasma treatment of the ITO slides, PEDOT:PSS A14083 (Clcvios) was spin-coated at 5000 rpm, acceleration - 928 rpm/s for 60 sec. Subsequently, the films were heated on a hot plate at I40°C for 15 min. PEDOT:PSS was deposited in air.

Compound G was processed in the glove box under nitrogen. 5 mg of TAG (DPI- TPFPB) (Aldrich) was dissolved in 10 ml of anhydrous chlorobenzene (Aldrich) then 10 mg of Compound G was dissolved in I ml of previously prepared TAG solution. Around 35 nm thick films of the hole-transport material were spin-coated at 1000 rpm, acceleration 1540 rpm/scc for 60 sec. The films were then dried on a hot plate at 1 10 °C for 30 minutes followed by thermal curing at 200 °C for 30 min. A watch glass was used during the curing process over the samples in order to avoid excessive heat loses.

The emissive layer, consisting of the Compound E host and Ir(pppy)3 emitter was prepared in the following way in the glove box: 10 mg of Compound E was dissolved in 1 ml

49 chlorobenzene and 10 mg of Ir(pppy)3 in 1 ml of chloroben/ene. 64 μΙ of Ir(pppy>3 was added to I ml of the solution of Compound E. The solution was then spin-coated onto the HTL at 2000 rpm, 1000 rpm / sec, 60 sec. The films were dried at 100 °C for 10-15 min.

The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF

(Aldrich) and aluminum were thermally evaporated at 1 A/s, 0.2 A/s and 2 A/s respectively. The pressure in the vacuum chamber was 1 * 10^"' Torn The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen, where current- voltage and luminescence-voltage characteristics were measured with a Keith ley 2400 Source Meter and a calibrated pholodiode (FDS 100 from Thorlabs, Inc.). The performance of the device is shown in Figure 6. The plot on the left shows current density voltage characteristic of the diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (EQK) (empty symbols) as a function of applied voltage. The value of KQE between 10 and 1000 cd/m² is between 7% and 6% and maximum luminance shown is above 1 ,000 cd/m². This level of performance in terms of efficiency and luminance is outstanding for a device with an emissive layer that is processed from solution, and proves the suitability of these compositions for organic light-emitting diode applications.

EXAMPLE 12

LiF/Al/Ag (2.5/60 nm/100

nmj

BCP (50 nm)

Compound E :Ir(pppy)₃ 6 wt. % (20

nm)

G(35 nm)

ITO

Glass

Indium tin oxide (ITO)-coated glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of ~15 Ω/sq were used as substrates for the OLKDs fabrication. The ITO substrates were masked partially with kapton tape and the exposed ΠΌ was etched in acid vapor ( 1 :3 by volume, HNO3: HCI) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently, ΙΊΌ substrates were (¼ plasma treated for 2 min.

50 Compound G was processed in the glove box under nitrogen. 5 mg of TAG (DPI- TPFPB) (Aldrich) was dissolved in 10 ml of anhydrous chlorobcnzcnc (Aldrich) then 1 mg of Compound G was dissolved in I ml of previously prepared TAG solution. Around 35 nm thick films of the hole-transport material were spin-coated at 1000 rpm, acceleration 1540 rpm/sec for 60 sec. The films were then dried on a hot plate at 1 10 °C for 30 minutes followed by thermal curing at 200 °C for 30 min. A watch glass was used during the curing process over the samples in order to avoid excessive heat loses.

The emissive layer, consisting of the Compound li host and Ir(pppy)3 emitter was prepared in the following way in the glove box: 10 mg of Compound E was dissolved in 1 ml chloroben/ene and 10 mg of Ir(pppy)3 in 1 ml of chlorobenzene. 64 μΙ of lr(pppy)₃ was added to I ml of the solution of Compound E. The solution was then spin-coated onto the I ITL at 2000 rpm, 1000 rpm / sec, 60 sec. The films were dried at 1 0 °C for 1 - 15 min.

The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF

(Aldrich) and aluminum were thermally evaporated at I A s, 0.2 A s and 2 A s respectively. The pressure in the vacuum chamber was MO^'7 Torr. The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen, where current- voltage and luminance-voltage characteristics were measured with a Keith ley 2400 Source Meter and a calibrated photodiodc (FDS 100 from Thorlabs, Inc.). The performance of the device is shown in Figure 7. The plot on the left shows current density voltage characteristic of the diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (HQE) (empty symbols) as a function of applied voltage. The value of F.QE between 10 and 1000 cd/m² is between 14% and 2% and maximum luminance shown is above 5,000 cd/m². This level of performance in terms of efficiency and luminance is outstanding for a device with an emissive layer that is processed from solution, and proves the suitability of these compositions for organic light-emitting diode applications.

51 EXAMPLE 13

(2.5/60 nm/100

[50 nm)

ompound F :Ir(pppy)₃ 6 wt. % (20

nm)

G (35 nm)

ITO

Glass

Indium tin oxide (ITO)-coated glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of- 15 Ω/sq were used as substrates for the OLEDs fabrication. The ITO substrates were masked partially with kapton tape and the exposed ITO was etched in acid vapor ( 1 :3 by volume, HNOj: HC1) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently, ITO substrates were O2 plasma treated for 2 min.

Compound G was processed in the glove box under nitrogen. 5 mg of TAG (DP1- TPFPB) (Aldrich) was dissolved in 10 ml of anhydrous chlorobenzenc (Aldrich) then 10 mg of Compound G was dissolved in I ml of previously prepared TAG solution. Around 35 nm thick films of the hole-transport material were spin-coated at 1000 rpm, acceleration 1540 rpm/scc for 60 sec. The films were then dried on a hot plate at 1 10 °C for 30 minutes followed by thermal curing at 200 °C for 30 min. A watch glass was used during the curing process over the samples in order to avoid excessive heat loses.

The emissive layer, consisting of the Compound F host and Ir(pppy);» emitter was prepared in the following way in the glove box: 10 mg of Compound F was dissolved in I ml chlorobcnzenc and 1 mg of lr(pppy)₃ in I ml of chlorobenzcnc. 64 μΙ of lr(pppy)s was added to 1 ml of the solution of Compound F. The solution was then spin-coated onto the HTL at 2000 rpm, 1000 rpm / sec, 60 sec. The films were dried at 100 °C for 10-15 min.

The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF

(Aldrich) and aluminum were thermally evaporated at 1 A/s, 0.2 A/s and 2 A s respectively. The pressure in the vacuum chamber was 1 x 10^"7 Torr. The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen, where current- voltage and luminance-voltage characteristics were measured with a eithley 2400 Source

52 Meter and a calibrated photodiode (FDS 100 from Thorlabs, Inc.). The performance of the device is shown in Figure 8. The plot on the left shows current density voltage characteristic of the diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (EQE) (empty symbols) as a function of applied voltage. The value of EQE between 10 and 1000 cd/rn² is between 14% and 8% and maximum luminance shown is above 5,000 cd/m². This level of performance in terms of efficiency and luminance is outstanding for a device with an emissive layer that is processed from solution, and proves the suitability of these compositions for organic light-emitting diode applications.

EXAMPLE 14

LiF/Al/Ag (2.5/60 nm/100

nm]

BCP (50 nm)

Compound F :Ir(pppy)₃ 6 wt. % (20

nm)

G(35 nm)

PEDOT: PSS Al 4083 (50 nm)

ITO

Glass

Indium tin oxide (ITO)-coatcd glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of -15 Ω/sq were used as substrates for the OLEDs fabrication. The ITO substrates were masked partially with kapton tape and the exposed ITO was etched in acid vapor (1 :3 by volume, I INO3: 1 ICI) for 5 min at 60 °C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently, NO substrates were O3 plasma treated for 2 min.

Immediately after O2 plasma treatment of the ΙΊΌ slides, PEDOT-.PSS AI4083 (Clevios) was spin-coated at 5000 rpm, acceleration - 928 rpm/s for 60 sec. Subsequently, the films were heated on a hot plate at 140°C for 15 min. PEDOT:PSS was deposited in air.

Compound G was processed in the glove box under nitrogen. 5 mg of TAG (DPI- TPFPB) (Aldrich) was dissolved in 10 ml of anhydrous chloroben/ene (Aldrich) then 10 mg of Compound G was dissolved in 1 ml of previously prepared TAG solution. Around 35 nm

53 thick films of the hole-transport material were spin-coated at 1000 rpm, acceleration 1540 rpm/sec for 60 sec. The films were then dried on a hot plate at 1 10 °C for 30 minutes followed by thermal curing at 200 °C for 30 min. Λ watch glass was used during the curing process over the samples in order to avoid excessive heat loses.

Emissive layer, consisting of the Compound F host and Ir(pppy)3 emitter was prepared in the following way in the glove box: 10 mg of Compound F was dissolved in 1 ml chlorobcnzcne and 10 mg of Ir(pppy)3 in 1 ml of chlorobcnzcnc. 64 μΐ of Ir(pppy)j was added to 1 ml of the solution of Compound F. The solution was then spin-coated onto the MTL at 2000 rpm, 1000 rpm / sec, 60 sec. The films were dried at 100 °C for 10-15 min.

The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF

(Aldrich) and aluminum were thermally evaporated at 1 A/s, 0.2 A/s and 2 A/s respectively. The pressure in the vacuum chamber was 1 * 10^"T Torr. The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen, where current- voltage and luminance-voltage characteristics were measured with a Keithley 2400 Source Meter and a calibrated photodiodc (I DS 100 from Thorlabs, Inc.). The performance of the device is shown in Figure 9. The plot on the left shows current density voltage characteristic of the diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (liQli) (empty symbols) as a function of applied voltage. The value of EQE between 10 and 1000 cd/m² is between 9% and 5% and maximum luminance shown is about 10,000 cd m². This level of performance in terms of efficiency and luminance is outstanding for a device with an emissive layer that is processed from solution, and proves the suitability of these compositions for organic light-emitting diode applications.

EXAMPLE 15

LiF/Al/Ag (2.4/40/100

(40 nm)

B :lr(pppy)₃ 6wt. % (40 nm)

Poly-TPD-F (35

!TO

Glass

54 Indium tin oxide (ITO)-coated glass (Colorado Concept Coatings LLC) with a sheet resistivity of -15 ii sq was used as the substrate for the OLI£Ds fabrication. The NO substrates were patterned with kapton tape and etched in acid vapor (1:3 by volume, HN0₃: 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.

For the Poly-TPD-F hole-transport layer, 10 mg of Poly-TPD-F were dissolved in 1 ml of chloroform with purity of 99.8%; which was distilled and degassed over night 35 nm thick films were then spin coated (60 s@!500 rpm, acceleration 10,000 rpm/s) onto the indium tin oxide (ΠΌ) coated glass substrates, treated with an 0₂ plasma for 3 minutes prior to the deposition of the hole-transport material. Spin coating was carried out in a N₂ filled wet glove box. After spin-coating, a rectangular strip of the layer was removed at the edge of the substrate to expose ITO and ensure electrical contact to the anode; then, the sample was transferred to the wet glove box ante-chamber and subjected to vacuum for 1 minutes; then the sample was transferred back into the wet glove-box were it was annealed for 15 min at 75 °C on a hot plate, after which the hot plate was turned off. The sample was removed from the hot plate only until its temperature was down to 40 °C. Finally the sample was exposed to 0.7 mW/cm² of UV illumination for 1 minute to crosslink the hole-transport layer.

For the emissive layer, 6 wt.% of Ir(pppy)3 was mixed with Compound B and both materials dissolved in 1 ml of chlorobenzene with a purity of 99.8%; distilled and degassed over night. 40-50 nm thick films were then spin coated (60 s@1000 rpm, acceleration 10,000 rpm/s) onto the UV crosslinkcd poly-TPD-F layer. After spin-coating, the samples were baked at 75 °C for 1 minutes. Chlorobenzene was then used to remove the emissive layer in

55 the area not covered by poly-TPD-F, exposing the (TO substrate to provide electrical contact to the anode. The samples were then transferred, under a N₂ atmosphere, into an SPECTROS from Kurt J. Lcskcr thermal deposition system directly connected to the wet-glove box.

For the hole-blocking and electron transport layer, a 40 nm thick BCP layer was vacuum deposited at a pressure below 2* 10^"7 Torr and at rates of 0.4 A/s, respectively. Then, a 2.4 nm of lithium fluoride (LiF), as an electron-injection layer, and a 200 nm-thick aluminum cathode were vacuum deposited through a shadow mask at a pressure below 3x 10^{' 7} Torr and at rates of 0.15 A/s and 2 A/s, respectively. The shadow mask used for the evaporation of the metal electrodes yield five devices with an area of roughly 0.1 cm² per substrate. The device testing was done, right after the deposition of the metal cathode, in an inert atmosphere and without exposing the devices to air, where current-voltage and luminance-voltage characteristics were measured with a Keithley 2400 Source Meter and a calibrated photodiode (FDS 100 from Thorlabs, Inc.). The performance of the device is shown in Figure 10. The plot on the left shows current density voltage characteristic of the diode. The plot on the right shows luminance values (solid symbols) and external quantum efficiency (EQE) (empty symbols) as a function of applied voltage. The value of EQE between 10 and 1000 cd/m² is between 1% and 0.3% and maximum luminance shown is above 1 ,000 cd/m². The performance of this device is lower compared to other examples, due in part to the use of Poly TP -F as a hole transport layer. Optimization of the device architecture through the use of different hole transport layers is expected to lead to higher performance.

EXAMPLE 16

UF/AI/Ag (2.5/60 nm/100 nm)

BCP (SO nm)

Compound F:lr(pppy)_s 6 wt. % (20

^~7 nm)

Compound J (35 nm) MoO, (15 nm)

ITO

Glass

Indium tin oxide (ITO)-coated glass slides (Colorado Concept Coatings LLC) with a sheet resistivity of -15 Ω/sq were used as substrates for the OLEDs fabrication. The ITO

56 substrates were masked with kapton tape and the exposed 1TO was etched in acid vapor (1:3 by volume, I Γ Ο3: 1 ICl) for 5 min at 60 *C. The substrates were cleaned in an ultrasonic bath in the following solutions: detergent water, distilled water, acetone, and isopropanol for 20 min in each step. At the end the substrates were blown dry with nitrogen. Subsequently, ΙΊΌ substrates were 0₂ plasma treated for 2 min.

The hole injection layer, M0O3 (Aldirch) was thermally evaporated at 0.2 A/s. The pressure in the vacuum chamber was I *10^"7 Torr.

Compound J

Compound J was processed in the glove box under nitrogen. 10 mg of Compound J was dissolved in 1.5 ml of toluene. Around 35 nm thick films of the hole-transport material were spin-coated at 2000 rpm, acceleration 1 00 rpm/sec for 60 sec. The films were then dried on a hot plate at 1 10 °C for 3 minutes followed by thermal curing at 150 °C for 15 min. A watch glass was used during the curing process over the samples in order to avoid excessive heat loses.

{^•missive layer, consisting of the Compound F host and emitter was prepared in the following way in the glove box: 10 mg of Compound F was dissolved in 1.5 ml toluene and 10 mg of lr(pppy)₃ (Solvay) in 1.5 ml of toluene.64 μΐ of Ir(pppy>3 was added to 1 ml of the solution of Compound F. The solution was then spin-coated onto the HTL at 2000 rpm, 1000 rpm / sec, 60 sec. The films were dried at 100 °C for 2 min.

The electron transport layer, BCP (Aldrich), the electron-injection layer, LiF

(Aldrich), aluminum, silver were thermally evaporated at I A/s, 0.2 A s, 2 A/s and 2 A/s respectively. The pressure in the vacuum chamber was 1 ^χ 10^'7 Torr. The active area of the tested devices was about 0.1 cm². The devices were tested in a glove box under nitrogen. The performance of the device is shown in Figure 1 1.

EXAMPLE 17

57 UF/Al/Ag (2.5/60 nm/100 nm)

BCP (50 nm)

Compound F:lr(pppy)₃ 6 wt. % (20

τ nm)

Compound J (35 nm)

PEDOT: PSS Al 4083 (50 nm)

ITO

Glass

Λ device is fabricated in substantially the same way as in Example 16, except that the hole injection layer comprises PEDOT:PSS instead of M0O₃. Immediately after O2 plasma treatment of the ITO slides, PEDOT:PSS ΛΙ4083 (Clevios) was spin-coated at 5000 rpm, acceleration - 928 rpm/s for 60 sec. Subsequently, the films were heated on a hot plate at 140°C for 15 min. PEDOT:PSS was deposited in air.

The performance of the device is shown in Figure 12.

EXAMPLE 18

LiF/Al/Ag (2.5/60 nm/100 nm)

TmPyPB (50 nm)

Compound F:lr(pppy), 6 wt. % (20

nm)

Compound J (35 nm)

PEDOT: PSS Al 4083 (50 nm)

ITO

Glass

A device is fabricated in substantially the same way as in Example 17, except that the electron transport layer comprises TmPyPB instead of BCP.

TmPyPB ώ^. ,'.

The performance of the device is shown in Figure 13.

58 EXAMPLE 1

LiF/Al/Ag (2.S/60 nm/100 nm)

TpPyPB (50 nm)

Compound F:lr(pppy)₃ 6 wt. % (20

nm)

Compound J (35 nm)

PEDOT: PSS AI 40S3 (50 nm)

ITO

Glass

A device is fabricated in substantially the same way as in Example 17, except that the electron transport layer comprises TpPyPB instead of BCP.

V TpPyPB

The performance of the device is shown in Figure 14.

59

Claims

WHAT IS CLAIMED IS:

I. A compound represented by formula (I)

n

H R,

wherein:

a) R₄ is an optionally substituted aryl or an optionally substituted hctcroaryl group; b) n is at least 2;

c) for each ^{H R}i , at least one of R|, R2 and R3 is 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

optionally substituted aryl group, an optionally substituted hctcroaryl group, an optionally substituted alkyl group or an optionally substituted hctcroalkyl group, and wherein R* is hydrogen, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted alkyl group or an optionally substituted hctcroalkyl group.

2. The compound of claim I, wherein:

(i) the carbazole group is unsubstitutcd or substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxide, fluoroalkoxide and optionally substituted carbazole; (ii) the remaining of R|, R₂ and R3 are independently selected from hydrogen, fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide; (iii) R₄ is unsubstitutcd or substituted with one or more groups selected from fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide; and (iv) R¾ and are unsubstituted or substituted with one or more groups selected from hydroxy), fluoro, cyano, alkyl, fluoroalkyl, alkoxide and fluoroalkoxide.

3. The compound of claim I or 2, wherein R₄ is a group derived from a compound selected from benzene, biphenyl, and naphthalene, and wherein n is 2, 3 and 4.

60 4. The compound of any of claims 1-3, wherein the optionally substituted carbazole group is selected from formulae (II), (111), (IV), (V) and (VI):

Re (IV)

wherein each R₇, Rg, R?, Rio and Rn is independently hydrogen, fluoro, cyano, a Ci-20 linear or branched alkyl, a Ci_-2c linear or branched fluoroalkyl, a C|_-2o linear or branched alkoxide, or a Ci-2u linear or branched fluoroalkoxidc group.

5. The compound of any of claims 1-3, wherein the ^{H R}i group is selected from formulae (VII) and (VIII):

61

wherein each R|₂ and R13 is independently hydrogen, fluoro, cyano, a C_{1 - 20} linear or branched alkyl, a CY20 linear or branched pcrfluoroalkyl, a C_{1 - 20} linear or branched alkoxide, a C1.20 linear or branched fluoroalkoxide group, or an optionally substituted carbazolc.

62

N-N N

7. The compound of any of claims 1-6, wherein -^~ Y is or

N— N > - Ϊ

8. The compound of any of claims 1-6, wherein Y is ^R5 .

— N-N

9. I¾c compound of any of claims 1-6, wherein Y is N=N or

N N

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

1 1. The compound of any of claims 1-10, wherein the compound has a Tg of at least I50°C.

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

63

64

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

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

represented by n Ri , wherein the first compound comprises the R₄ group linked to n a groups, wherein the second compound is represented by

H f¾

^H Ri ; and

.0 0.

(b) converting each HN-NH moiety to an optionally substituted oxadiazolc or triazolc;

wherein (i) R₄ and n in the formula representing the first compound, (ii) Ri, R2 and Rj in the formula representing the second compound, and (iii) R|, R₂, R3, R₄ and n in the formula representing the third compound, have the same definition as their R|, R₂, R₃, R₄ and n homologucs 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.

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

65