DE19704031A1 - Aromatic tertiary amine compounds with high glass transition temperature and efficient hole injection from indium-tin oxide - Google Patents

Abstract

Aromatic tertiary amines of formula (I) are new, in which: (a) Ar1, Ar2 = aryl groups of formulae, e.g., (IIA-IIC); (b) Ar1, Ar2 = a group of formula (III), (c) Ar1 = a group of formula, e.g., (IIA-IIC) and Ar2 = a group of formula (IV); or (d) Ar1 = a group of formula (III) and Ar2 = a group of formula (V). In (a)-(d), R11, R12 = hydrogen (H), optionally substituted 1-10 carbon (C) alkyl, alkoxy, phenoxy, phenyl, alkyl- or alkoxy-substituted phenyl, aryl, halogen or dialkylamino; R13 = optionally substituted 2-8C alkyl, alkoxy, phenoxy, phenyl, alkyl- or alkoxy-substituted phenyl, aryl, dialkyl- or diaryl-thiolate or dialkylamino; R21 = optionally substituted 2-10C alkyl, alkoxy, phenoxy, alkyl- or alkoxy-substituted phenyl, aryl, aralkyl or dialkylamino; Ar31 = a group of formula, e.g., (IIA; R11 = as above or aralkyl); and Ar41 = a group of formula (III; R21 = optionally substituted 1-10C alkyl, alkoxy, phenoxy, phenyl, alkyl- or alkoxy-substituted phenyl, aralkyl, aryl, halogen or dialkylamino). Also claimed are electroluminescent devices with an electroluminescent element containing compound(s) (I).

Description

State of the art

The present invention relates to novel amino compounds and an organic electroluminescent device, wel the new amino compounds as hole-conducting materials used.

An electroluminescent (EL) device is thereby cha Characterized that they under application of an electrical Voltage under current flow emits light. Such anord tions are labeled "light emitting diodes" (LED = light emitting diodes) has long been known. As Elektrolumi Nescience is the direct conversion of electrical energy Energy in light. This phenomenon happens depending on what you use Material through different mechanisms. to In general, inorganic semiconductors have been included For example, doped with impurities ZnS or Gas connections used. The origin of the electrolumi The presence of inorganic semiconducting materials lies in the induced by electron injection excitation of lumines centers (for example, the doping materials such as Mn or Tb) in the inorganic host lattices. This is Wech selstrom and a high current of over 100 volts neces sary sary.  

For several years increasingly find organic materials such as poly (p-phenylene-vinylene) (PPV) or 2- (Biphenyl-4-yl) -5- (tert -butylphenyl) -1,3,4-oxadiazole (PBD) and their derivatives use as electroluminescent Ma Materials (J.Salbeck, Ber. Bunsenges Phys. Chem. 100, 1667-1677). Electroluminescence in organic compound made by recombination of so-called holes, d. H. positive charges, and electrons, d. H. negative La tions, via so-called excitement states. You need DC and low voltages from 2 to 20 volts (U.S.P. 4,539,507). It is possible with organic compounds conditions also large-scale LED arrangements.

EL devices based on organic compounds generally contain one or more thin layers of organic or organometallic charge transport compounds. The basic structure in the order of layers is as follows:

Carrier, substrate
Base electrode (anode)
Hole injecting layer
Hole transporting layer
Light-emitting layer
Electron-transporting layer
Electronically injecting layer
Top electrode (cathode)
contacts
Serving, encapsulation.

This structure represents the most general case and can simplified by omitting individual layers so that a shift can take on multiple tasks can. In the simplest case, an EL arrangement consists of two  Electrodes, the anode and the cathode, between which a single organic layer that has all the functio including the emission of light (WO 90-13148). Two-layer systems are advantageous in which an emitter layer consisting of pho Toluminescent materials, on the organic layer be evaporated.

In all known systems, such Verbindun were inherent problems solved unsatisfactorily:

The low glass transition temperature T _{g of} the organic thin-film layers leads to problems with respect to the thermal and morphological stability of the EL devices produced therefrom. Moreover, the known systems have exhibited a relatively rapid decrease in luminescence and lack of storage stability.

Furthermore, almost all of the known systems have relatively high levels HOMO-Niveauxs not in the immediate area of the Ionisa tion potential of indium tin oxide (ITO), the most common most used material for the transparent anode, lie gene.

Advantages of the invention

In an advantageous embodiment for an electroluminescent arrangement, the electroluminescent element of this arrangement is used for the aromatic tertiary amino compounds A, characterized by one of the structural formulas I to IV:

wherein Ar ₁₁ and Ar _{12 may be the} same or different and represent the following group of aryl compounds:

in which R ₁₁ and R _{12 may be the} same or different and for
Hydrogen, optionally substituted C ₁ to C ₁₀ alkyl, alkoxy, phenoxy, phenyl, alkyl-substituted phenyl, alkoxy-substituted phenyl, aryl, halogen or dialkylamino,
and wherein R _{13 is} optionally substituted C ₂ to C ₈ alkyl, alkoxy, phenoxy, phenyl, alkyl-substituted phenyl, alkoxy-substituted phenyl, aryl, dialkylthiolate, diarylthiolate or dialkylamino,

where Ar ₂₁ and Ar _{22 are} for

stands
and in which R ₂₁ for
optionally substituted C ₂ to C ₁₀ alkyl, alkoxy, phenoxy, alkyl-substituted phenyl, alkoxy-substituted phenyl, aryl, aralkyl or dialkylamino,

wherein Ar _{31 is} the following group of aryl compounds:

wherein R ₃₁ and R _{32 may be the} same or different and for
Hydrogen, optionally substituted C ₁ to C ₁₀ alkyl, alkoxy, phenoxy, phenyl, alkyl-substituted phenyl, alkoxy-substituted phenyl, aralkyl, aryl, halogen or dialkylamino,

where Ar _{41 is} for

stands,
and wherein R _{41 is} for
optionally substituted C ₁ to C ₁₀ alkyl, alkoxy, phenoxy, phenyl, alkyl-substituted phenyl, alkoxy-substituted phenyl, aralkyl, aryl, halogen or Dial kylamino.

The amino compound according to the invention has more advantageous Example, a very high glass transition temperature and a niedri HOMO level, which is in the range of the ionization potential from ITC. ITO is usually considered optically transparent te electrode (anode) used. Become from the anode Holes or holes in the organic layer system injected. The injection of holes is then particularly ef efficient when the potential barrier between ITO and hole-conducting material is small, as it is advantageous having the amino compound of the invention.

Further advantageous embodiments and further developments of Invention are described in the subclaims.

In an advantageous embodiment, a two-layer system between the electrodes of the EL device is used, best starting from a layer containing a Aminover inventive compound and an electron-conducting emitter layer of aluminum tris (8-hydroxyquinolate) (Alq ₃ ), so that the luminosity the EL device is amplified.

Description of the embodiments

The amino compound of the formulas I to IV is a new compound. The synthesis of the amino compound is carried out either by a condensation reaction of optionally substituted accordingly tris (diarylamino) benzene compound of the formula V.

where Ar _{51 is} the following group of aryl compounds:

and wherein R ₅₁ and R _{52 may be the} same or different and for
Hydrogen, optionally substituted C ₁ to C ₁₀ alkyl, alkoxy, phenoxy, phenyl, alkyl-substituted phenyl, alkoxy-substituted phenyl, aralkyl, aryl, halogen or dialkylamino,
with an appropriately substituted cyclohexanone in the presence of a hydrogen transfer catalyst, for example Pd / C.

It is likewise possible to use the amino compound according to the invention via the Ullmann reaction between halogenated, given if substituted, aryl and the corresponding with iodine substituted aromatic compound of optionally sub To obtain substituted amino compound.

According to this method, the amino compound was synthesized according to formulas I to IV. By way of example, the compounds I-1 and I-2 are indicated by their structural formula:

The following are further examples of the synthesis of a inventive amino compound according to formula III leads.

Synthetic Example 1

5 g (40 mmol) phloroglucinol, 36.5 g (198 mmol) N-phenyl-1,4- phenylenediamine and 150 mg iodine were dissolved in 10 ml tetralin and Heat 15 ml of p-xylene for 6 hours on a water separator. The hot reaction mixture was stirred with 200 ml Methanol added. Upon cooling, a gray solid precipitated from which filtered off, washed with methanol and dried has been. There were 18.2 g (yield: 75.6%) of 1,3,5-tris - [(4'- phenylaminophenyl) amino] benzene having a melting point of 210 ° C received.

1 g (1.6 mmol) of 1,3,5-tris - [(4'-phenylaminophenyl) -amino] - benzene, 4 g potassium carbonate, 1.8 g copper powder and 200 mg 18- Crown ethers were dissolved in 20 ml of o-dichlorobenzene under argon heated to 170 ° C. 7.8 g (38 mmol) of iodobenzene added dropwise over 1 hour and the reaction mixture heated to 200 ° C for 48 hours. The reaction mixture was filtered hot and the reaction product of methanol recrystallized and with ethyl acetate / hexane (1: 4) as eluent purified by chromatography. The yield of 1,3,5-tris [(4'-diphenylaminophenyl) amino] benzene (III-1) was 1.25 g (35%) with a melting point of 235 ° C.  

Synthesis Example 2

1 g (1.6 mmol) of 1,3,5-tris - [(4'-phenylaminophenyl) amino] benzene, 4 g of potassium carbonate, 1.8 g of copper powder and 200 mg of 18-crown ether were in 20 ml of o-dichlorobenzene under argon atmosphere heated to 170 ° C. 8.9 g (38 mmol) of p-iodoanisole were added dropwise over one hour and the reaction mixture was heated to 200 ° C. for 48 hours. The reaction mixture was filtered hot and the solvent removed. The reaction product was dissolved in 10 ml of THF, precipitated with methanol and purified by chromatography with ethyl acetate / hexane (1: 4) as the eluent. The yield of 1,3,5-tris - [(4'-phenyl-4 '' - methoxyphenylaminophenyl) amino] benzene (III-2) was 1.1 g (46%).

Synthesis Example 3

1 g (1.6 mmol) of 1,3,5-tris - [(4'-phenylaminophenyl) -amino] - benzene, 4 g potassium carbonate, 1.8 g copper powder and 200 mg 18- Crown ethers were dissolved in 50 ml of o-dichlorobenzene under argonatmo heated to 170 ° C. 7.8 g (38 mmol) of 1-iodonaphthalene were added dropwise during one hour and the reaction mixture heated to 200 ° C during 48 hours. The reaction The mixture was filtered hot and the solvent was removed The reaction product was dissolved in 10 ml of THF, with Methanol and ethyl acetate / hexane (1: 4) as eluent purified by chromatography. The yield of 1,3,5-tris [(4-phenyl-naphthyl-aminophenyl) -amino] -benzene (III-3) be contributed 1.9 g (42%).  

The amino compound according to the invention of the formulas I to IV has a high glass transition temperature and a low one HOMO level in the region of the ionization potential of Indi to tin oxide. The glass state is thermal and chemical morphologically extremely stable. The aminover Bonding of the formulas I to III can therefore be very advantageous as a hole-conducting material in electroluminescent Use arrangements.

The glass transition temperature and the energy of the HOMO level the amino compound of the invention is on some out selected examples shown in Table 1:  

Table 1

The energy of the HOMO-Niveauxs was determined by means of Cyclic voltammetry. The amino compound of the invention leaves also in a single-layer system as an emitter substance put. This is from the respective substituents on the Dependent on phenyl rings.

In the following are some examples of the production of electroluminescent devices by means of the inventions To the invention amino compound of formulas I to IV beschrie ben:

example 1

On a cleaned, coated with ITO substrate was a 70 nm thick layer of a 1% solution consisting from the amino compound having the structural formula I-1 and the Binder PVC in a ratio of 1: 1 spin-coated (100 rpm). As the solvent, dichloroethane was used. On it was a 60 nm thick layer consisting of aluminum tris (8- hydroxy-quinolate) by means of vacuum evaporation. The layer system was completed with a Magnesi um-silver (10: 1) cathode vapor-deposited in vacuo. Magnesium and Silver was co-evaporated from thermally heated sources.

Example 2

On a cleaned, coated with ITO substrate was an approximately 100 nm thick layer of the amino compound with of the structural formula I-1 evaporated in vacuo. On it was an approximately 60 nm thick layer consisting of aluminum tris (8-hydroxyquinolate) also by means of vacuum evaporation divorced. The layer system was completed with a Aluminum cathode vapor-deposited in vacuum. The threshold voltage for the light emission was 3.5 volts.

Example 3

Was on a cleaned with ITO coated substrate an approximately 100 nm thick layer of the amino compound with the structural formula 1-2 evaporated in vacuo. On it was an approximately 60 nm thick layer consisting of aluminum tris (8-hydroxyquinolate) also by means of vacuum evaporation divorced. The layer system was completed with a Aluminum cathode vapor-deposited in vacuum. The threshold voltage for the light emission was 5 volts.

Example 4

Was on a cleaned with ITO coated substrate an approximately 150 nm thick layer of the amino compound with of the structural formula I-1 evaporated in vacuo. The Schichtsy stem was completed with an aluminum cathode in vacuum steamed. The threshold voltage for the light emission was at 3 volts.

Example 5

Was on a cleaned with ITO coated substrate an approximately 150 nm thick layer of the amino compound with  of the structural formula I-2 evaporated in vacuo. The shift system was completed with an aluminum cathode in vacuum steamed. The threshold voltage for the light emission was at 3 volts.

Example 6

On a cleaned ITO coated substrate was an approximately 60 nm thick layer of a 1% solution, be standing from the amino compound having the structural formula III-3 and PVK in the ratio 1: 1 spin-coated (1000 U / min). When Solvent was used dichloroethane. On it was an approximately 60 nm thick layer consisting of aluminum tris (8-hydroxyquinolate) deposited by vacuum evaporation. The layer system was completed with a Magnesi um-silver (10: 1) cathode vapor-deposited in vacuo. Magnesium and Silver was co-evaporated from thermally heated sources.

The achieved luminescence values of the arrangement according to the invention with an emitter layer of Alq ₃ are explained in Table 2 in two examples:

connection Luminescence (cd / m ² ) I-1 1000 III-3 2100

The arrangements according to the invention are for the production of Units for lighting and information presentation suitable.

Of course, the invention includes besides the spezi rule configurations also familiar to any expert Mo modifications and modifications thereof.

Claims (11)

1. Aromatic tertiary amino compound A, characterized by one of the structural formulas I to IV,
wherein Ar ₁₁ and Ar _{12 may be the} same or different and represent the following group of aryl compounds:
in which R ₁₁ and R _{12 may be the} same or different and for
Hydrogen, optionally substituted C ₁ to C ₁₀ alkyl, alkoxy, phenoxy, phenyl, alkyl-substituted phenyl, alkoxy-substituted phenyl, aryl, halogen or dialkylamino,
and wherein R _{13 represents} optionally substituted C ₂ to C ₈ alkyl, alkoxy, phenoxy, phenyl, alkyl-substituted phenyl, alkoxy-substituted phenyl, aryl, dialkylthiolate, diarylthiolate or dialkylamino,
where Ar ₂₁ and Ar _{22 are} for
stands
and in which R ₂₁ for
optionally substituted C ₂ to C ₁₀ alkyl, alkoxy, phenoxy, alkyl-substituted phenyl, alkoxy-substituted phenyl, aryl, aralkyl or dialkylamino,
wherein Ar _{31 is} the following group of aryl compounds:
wherein R ₃₁ and R _{32 may be the} same or different and for
Hydrogen, optionally substituted C ₁ to C ₁₀ alkyl, alkoxy, phenoxy, phenyl, alkyl-substituted phenyl, alkoxy-substituted phenyl, aralkyl, aryl, halogen or dialkylamino,
where Ar _{41 is} for
stands,
and where R _{41 is} for
optionally substituted C ₁ to C ₁₀ alkyl, alkoxy, phenoxy, phenyl, alkyl-substituted phenyl, alkoxy-substituted phenyl, aralkyl, aryl, halogen or Dial kylamino. 2. Electroluminescent arrangements with a elektrolumi neszierenden element, characterized in that the elec triluminescent element at least one, optionally substituted compound of the structural formulas I, II, III or IV contains. 3. Electroluminescent arrangements according to claim 2, since characterized in that the electroluminescent element consists of a single-layer system. 4. Electroluminescent devices according to claim 3, characterized in that the electroluminescent element contains a luminescent material L consisting of a compound of the general formula (VI):
5. Electroluminescent arrangement according to claim 2, characterized characterized in that the electroluminescent element with an emitter layer of a luminescent material L communicates. 6. Electroluminescent devices according to claim 5, characterized in that the luminescent material L is a compound of general formula (VI)
wherein M is a metal, n is a number between 1 and 3 and z indicates the valence of the metal and wherein R is hydrogen, optionally substituted C ₁ to C ₆ alkyl, optionally substituted phenyl or halogen. 7. Electroluminescent devices according to claim 4 or 6, characterized in that M for a two- or dreiwer tiger metal, which forms chelates. 8. Electroluminescent devices according to claim 7, characterized in that the metal is selected from the group Al ³⁺ , Mg ²⁺ , In ³⁺ or Ga ³⁺ . 9. Electroluminescent arrangements according to claim 2, since characterized in that the electroluminescent element contains a transparent polymeric binder B. 10. Electroluminescent arrangements according to claim 9, since characterized in that the transparent binder is selected  is from the group polycarbonates, polyester carbonates, poly styrenes, copolymers of styrene such as SAN or styrene acrylates, Polymethacrylates, polyvinylpyrrolidones, polyvinylcarbazoles, Polyolefins, cyclic olefin copolymers, phenoxy resins, Po lyvinyl alcohols, polymers based on vinyl groups monomers, cellulose, cellulose derivatives. 11. Electroluminescent arrangement according to claim 2, since characterized in that the electroluminescent element arranged on a substrate and having an anode and a Cathode is contacted, wherein at least one of the two Electrodes in the visible spectral wavelength range trans parent, and the electroluminescent element of the series is built up from a hole-injecting area, egg a hole transporting area, an electroluminescent rende area, an electron-transporting area and an electron injecting region attached to the Katho de adjoins.