LIGHT EMITTING MATERIAL, INK COMPOSITION, THIN FILM, LIGHT EMITTING DEVICE AND METHOD FOR MANUFACTURING LIGHT EMITTING DEVICE

• US 20130049571A1
• Filed: 01/28/2011
• Published: 02/28/2013
• Est. Priority Date: 01/29/2010
• Status: Active Grant

• Current Assignee: Sumitomo Chemical Company Limited
• Original Assignee: Sumitomo Chemical Company Limited
• Inventors: Anryu, Makoto, Asada, Kohei, Sasaki, Shigeru
• Granted Patent: US 8,922,109 B2
• Time in Patent Office: Days
• US Class Current: 313/498
• CPC Class Codes: C08G 2261/3142 fluorene-based, e.g. fluorene, indenofluorene, or spirobifluorene
• CPC Class Codes: C08G 2261/3162 Arylamines
• CPC Class Codes: C08G 2261/411 Suzuki reactions
• CPC Class Codes: C08G 2261/5222 electrofluorescent
• CPC Class Codes: C08G 2261/5242 electrophosphorescent
• CPC Class Codes: C08G 61/12 Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule
• CPC Class Codes: C08L 65/00 Compositions of macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain C08L7/00 - C08L57/00, C08L61/00 take precedence; Compositions of derivatives of such polymers
• CPC Class Codes: C09D 11/00 Inks
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: H10K 2101/00 Properties of the organic materials covered by group H10K85/00
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 85/115 Polyfluorene; Derivatives thereof
• CPC Class Codes: H10K 85/151 Copolymers
• CPC Class Codes: H10K 85/623 containing five rings, e.g. pentacene
• CPC Class Codes: H10K 85/626 containing more than one polycyclic condensed aromatic rings, e.g. bis-anthracene
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

An object of the invention is to provide a light emitting material which can improve the luminous lifetime of a light emitting device by being included in a light emitting layer of the light emitting device. A means for achieving the object is a light emitting material characterized by comprising wherein the material comprises a conjugated polymer having a conjugated part and a blue light emitting compound having a blue light emitting part and satisfies the following formula (1):

y≧log₁₀(5.1×x^0.2+1)  (1)

• • wherein y represents the amount of light emitted by the blue light emitting compound where the total amount of light emitted by the conjugated polymer and the blue light emitting compound in the light emitting material due to excitation caused by light having a wavelength of 370 nm is 1, and provided that the gram light absorption coefficient of the conjugated polymer and the blue light emitting compound in the light emitting material are expressed by ε₁ and ε₂, and further the content of the blue light emitting compound is expressed by P₂ (parts by mass) where the total content of the conjugated polymer and the blue light emitting compound in the light emitting material is 100 parts by mass, a value represented by (ε₂/ε₁)×P₂ corresponds to x.

Claims

1. A light emitting material, wherein the material comprises a conjugated polymer having a conjugated part and a blue light emitting compound having a blue light emitting part and satisfies the following formula (1):

[Mathematical Formula 1]

y≧

log₁₀(5.1×

x^0.2+1) 

 

(1)

wherein y represents the amount of light emitted by the blue light emitting compound where the total amount of light emitted by the conjugated polymer and the blue light emitting compound in the light emitting material due to excitation caused by light having a wavelength of 370 nm is 1, and provided that the gram light absorption coefficient of the conjugated polymer and the blue light emitting compound in the light emitting material are expressed by ε

₁ and ε

₂, and further the content of the blue light emitting compound is expressed by P₂ (parts by mass) where the total content of the conjugated polymer and the blue light emitting compound in the light emitting material is 100 parts by mass, x is defined by the formula;

[Mathematical Formula 2]

x=(ε

₂/ε

₁)×

P₂.

3. The light emitting material according to claim 1, wherein y is 0.7 or more.

4. The light emitting material according to claim 1, wherein x is 1.0 or less.

5. The light emitting material according to claim 1, wherein the conjugated part is a bivalent aromatic amine residue.

6. The light emitting material according to claim 1, wherein the conjugated part is a fluorenediyl group.

7. The light emitting material according to claim 1, wherein the blue light emitting compound has a molecular weight of 5000 or less.

8. The light emitting material according to claim 1, wherein the blue light emitting part has a fused polycyclic aromatic hydrocarbon structure.

9. The light emitting material according to claim 1, wherein the content ratio of the blue light emitting part to the total content of the conjugated part and the blue light emitting part is 0.1 to 10% by mass.

10. The light emitting material according to claim 1, wherein the relationship between the peak wavelength (λ

₁) of a light emission peak at the shortest wavelength side among light emission peaks in a wavelength range of 350 nm to 500 nm of the conjugated polymer and the peak wavelength (λ

₂) of a light emission peak at the shortest wavelength side among light emission peaks in a wavelength range of 350 nm to 500 nm of the blue light emitting compound meets λ

₂−

λ

₁≦

50 nm.

11. An ink composition comprising the light emitting material according to claim 1.

12. A thin film characterized by being made of the light emitting material according to claim 1.

13. A light emitting device that is a white light emitting device in which a plurality of light emitting layers including a blue light emitting layer are laminated, wherein the device comprises as the blue light emitting layer a light emitting layer made of the thin film according to claim 12.

2. A light emitting material, wherein the material comprises a conjugated polymer having a conjugated part and a blue light emitting part and satisfies the following formula (1):

[Mathematical Formula 3]

y≧

log₁₀(5.1×

x^0.2+1) 

 

(1)

wherein y represents the amount of light emitted by the blue light emitting part where the total amount of light emitted by the conjugated part and the blue light emitting part in the light emitting material due to excitation caused by light having a wavelength of 370 nm is 1, and provided that the gram light absorption coefficient of the conjugated part and the blue light emitting part in the light emitting material are expressed by ε

₁ and ε

₂, and further the content of the blue light emitting part is expressed by P₂ (parts by mass) where the total content of the conjugated part and the blue light emitting part in the light emitting material is 100 parts by mass, x is defined by the formula;

[Mathematical Formula 4]

x=(ε

₂/ε

₁)×

P₂.

14. A method for manufacturing a light emitting device with an improved luminous lifetime, wherein the method comprises making a light emitting layer in the light emitting device to contain a light emitting material that comprises a conjugated polymer having a conjugated part and a blue light emitting compound having a blue light emitting part and satisfies the following formula (1):

[Mathematical Formula 5]

y≧

log₁₀(5.1×

x^0.2+1) 

 

(1)

wherein y represents the amount of light emitted by the blue light emitting compound where the total amount of light emitted by the conjugated polymer and the blue light emitting compound in the light emitting material due to excitation caused by light having a wavelength of 370 nm is 1, and provided that the gram light absorption coefficient of the conjugated polymer and the blue light emitting compound in the light emitting material are expressed by ε

₁ and ε

₂, and further the content of the blue light emitting compound is expressed by P₂ (parts by mass) where the total content of the conjugated polymer and the blue light emitting compound in the light emitting material is 100 parts by mass, x is defined by the formula;

[Mathematical Formula 6]

x=(ε

₂/ε

₁)×

P₂.