# US 7,745,016 B2 · White organic electroluminescence device

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- Number: US 7,745,016 B2
- Document ID: US7745016B2
- Status: Granted
- Kind: B2
- Application number: 10/563,353
- Filed: 2004-06-24
- Published: 2006-08-03
- Granted: 2010-06-29
- Earliest claimed: 2003-07-11
- Assignees: Idemitsu Kosan Co., Ltd.
- Inventors: Masahide Matsuura; Kenichi Fukuoka; Hiroshi Yamamoto; Chishio Hosokawa
- Web page: https://patentgrep.com/patent/US7745016B2

## CPC

- H10K 50/125: specially adapted for multicolour light emission, e.g. for emitting white light
- H10K 85/324: {comprising aluminium, e.g. Alq3}
- H10K 85/342: {comprising iridium}
- H10K 85/40: Organosilicon compounds, e.g. TIPS pentacene
- H10K 85/611: {Charge transfer complexes}
- H10K 85/615: {Polycyclic condensed aromatic hydrocarbons, e.g. anthracene}
- H10K 85/621: {Aromatic anhydride or imide compounds, e.g. perylene tetra-carboxylic dianhydride or perylene tetracarboxylic di-imide}
- H10K 85/624: {containing six or more rings}
- H10K 85/626: {containing more than one polycyclic condensed aromatic rings, e.g. bis-anthracene}
- H10K 85/631: {Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine}
- H10K 85/633: {comprising polycyclic condensed aromatic hydrocarbons as substituents on the nitrogen atom}
- H10K 85/654: {comprising only nitrogen as heteroatom (H10K85/652 takes precedence)}
- H10K 85/657: {Polycyclic condensed heteroaromatic hydrocarbons}
- H10K 85/6572: {comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole}
- Y10S 428/917: Electroluminescent
- Y10T 428/24942: including components having same physical characteristic in differing degree
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An organic electroluminescence device emitting white light which comprises at least two light emitting layers and an electron transporting layer comprising a heterocyclic derivative having nitrogen atom or silicon atom which are disposed between a pair of electrodes, wherein the energy gap of a host compound in each light emitting layer is in a specific range, the energy gap of the heterocyclic derivative having nitrogen atom or silicon atom in the electron transporting layer is in a specific range, and the ionization potential of the heterocyclic derivative having nitrogen atom or silicon atom in the electron transporting layer and the ionization potential of the host compound in the light emitting layer adjacent to the electron transporting layer satisfy a specific relation. The organic electroluminescence device provides a great efficiency of light emission under a low voltage and has a long lifetime, and exhibits no change in the chromaticity.

## Claims

### Claim 1

An organic electroluminescence device emitting white light which comprises a pair of electrodes, at least two light emitting layers and an electron transporting layer comprising a heterocyclic derivative having a nitrogen atom, the light emitting layers and the electron transporting layer being between the pair of electrodes, wherein
an energy gap of a host compound comprised in each light emitting layer Eg(Host-i) satisfies following relation (I):
2.9 eV≦Eg(Host-i) (I)
wherein Eg(Host-i) represents an energy gap of a host compound comprised in an i-th light emitting layer from the electron transporting layer, i representing an integer of 1 to n,
an energy gap of the heterocyclic derivative having a nitrogen atom comprised in the electron transporting layer Eg(ETM) satisfies following relation (II):
2.9 eV<Eg(ETM) (II)
and
an ionization potential of a host compound comprised in a light emitting layer adjacent to the electron transporting layer (Ip(Host-1)) and an ionization potential of the heterocyclic derivative having a nitrogen atom comprised in the electron transporting layer (Ip(ETM)) satisfy following relation (III):
Ip(ETM)≦Ip(Host-1)+0.3 eV (III);
wherein the host compound is capable of emitting blue light and is selected from the group consisting of anthracene derivatives, styryl derivatives, aromatic amines, aluminum chelates having mixed ligands and carbazole derivatives;
the energy gap is an excited singlet energy gap which is determined by obtaining an absorption spectrum of a 10−5 mole/liter toluene solution of a sample using an ultraviolet visible absorption meter and converting a wavelength at an absorption end on the absorption spectrum into energy value; and
the ionization potential is measured by obtaining a curve showing a change of discharged photoelectrons with a photon energy of irradiation using a photoelectron spectrometer, and determining by extrapolation a threshold value of the discharge of photoelectrons on the curve.

### Claim 2 (depends on 1)

The organic electroluminescence device emitting white light according to claim 1, wherein the energy gap of a host compound comprised in each light emitting layer Eg(Host-i) and the energy gap of the heterocyclic derivative having a nitrogen atom comprised in the electron transporting layer Eg(ETM) satisfy following relation (IV):
2.9 eV<Eg(ETM)≦Eg(Host-i) (IV).

### Claim 3 (depends on 1)

The organic electroluminescence device emitting white light according to claim 1, wherein at least one light emitting layer comprises a dopant having an energy gap of 2.9 eV or smaller.

### Claim 4 (depends on 1)

The organic electroluminescence device emitting white light according to claim 1, which comprises at least two light emitting layers having different peak wavelengths of light emission.

### Claim 5 (depends on 1)

The organic electroluminescence device emitting white light according to claim 1, wherein a difference between a greatest peak wavelength of light emission and a second greatest peak wavelength of light emission is 50 nm or greater.

### Claim 6 (depends on 1)

The organic electroluminescence device emitting white light according to claim 1, wherein the electron transporting layer or an interfacial region between the electron transporting layer and a cathode comprises a metal having a work function of 2.8 eV or smaller or a compound of the metal.

### Claim 7 (depends on 6)

The organic electroluminescence device emitting white light according to claim 6, wherein the metal is Na, K, Rb, Cs, Ca, Sr or Ba.

### Claim 8 (depends on 1)

The organic electroluminescence device emitting white light according to claim 1, wherein the electron transporting layer comprises a heterocyclic derivative having a nitrogen atom represented by following general formula (1):
HAr-L-Ar1—Ar2 (1)
wherein HAr represents a substituted or unsubstituted heterocyclic group having a nitrogen atom, Ar1 represents a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 40 carbon atoms, Ar2 represents a substituted or unsubstituted aryl group having 6 to 40 carbon atoms or a substituted or unsubstituted heteroaryl group having 3 to 40 carbon atoms, and L represents a single bond or a substituted or unsubstituted arylene group.

### Claim 9 (depends on 8)

The organic electroluminescence device emitting white light according to claim 8, wherein HAr represents a heterocyclic group represented by one of following formulae (2) to (24):
wherein R represents a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 40 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted alkoxyl group having 1 to 20 carbon atoms, n represents an integer of 0 to 5 and, when n represents an integer of 2 or greater, a plural R may represent a same group or different groups, and the plurality of groups represented by R may be bonded to each other to form a cyclic structure;
and formula (A):
wherein a plural R1 each independently represent hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 40 carbon atoms or a group forming a condensed aromatic group, Z represents oxygen atom, sulfur atom or a group represented by NR′, R′ representing a same atom or group as that represented by R1, and x represents an integer of 2 to 8;
or a substituted or unsubstituted carbazolyl group.

### Claim 10 (depends on 8)

The organic electroluminescence device emitting white light according to claim 8, wherein HAr represents a group expressed by one of following formulae (25) to (44):

### Claim 11 (depends on 8)

The organic electroluminescence device emitting white light according to claim 8, wherein L represents a group represented by one of following formulae (45) and (46):
wherein R2 represents a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 40 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted alkoxyl group having 1 to 20 carbon atoms, m represents an integer of 0 to 4 and, when m represents an integer of 2 or greater, a plural R2 may represent a same group or different groups, and a plural group represented by R2 may be bonded to each other to form a cyclic structure.

### Claim 12 (depends on 8)

The organic electroluminescence device emitting white light according to claim 8, wherein Ar2 represents a group represented by one of following formulae (47) to (53):
wherein R3 represents a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 40 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted alkoxyl group having 1 to 20 carbon atoms, p represents an integer of 0 to 9, q represents an integer of 0 to 5 and, when p or p+q represents an integer of 2 or greater, a plural R3 may represent a same group or different groups, and a plural group represented by R3 may be bonded to each other to form a cyclic structure.

### Claim 13 (depends on 8)

The organic electroluminescence device emitting white light according to claim 8, wherein Ar1 represents a group represented by one of following formulae (54) and (55):
wherein R4 to R17 each independently represent hydrogen atom, a halogen atom, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted aryloxyl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 40 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted alkoxyl group having 1 to 20 carbon atoms, and Ar3 and Ar4 each represent a substituted or unsubstituted aryl group having 6 to 40 carbon atoms or a substituted or unsubstituted heteroaryl group having 3 to 40 carbon atoms.