Organic electroluminescent element

• US 9,105,873 B2
• Filed: 03/09/2012
• Issued: 08/11/2015
• Est. Priority Date: 03/24/2011
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Tsuji, Hiroya, Ohara, Satoshi, Ide, Nobuhiro
• Primary Examiner(s): Mandala, Victor A
• Assistant Examiner(s): JEFFERSON, QUOVAUNDA
• Application Number:
  US14/006,418
• Publication Number:
  US 20140008629A1
• Time in Patent Office: 1,250 Days
• Field of Search: 257/40
• US Class Current: 1/1
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/131 with spacer layers between the electroluminescent layers
• CPC Class Codes: H10K 50/85 Arrangements for extracting light from the devices
• CPC Class Codes: H10K 50/854 comprising scattering means
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 85/342 comprising iridium

Abstract

An organic electroluminescent element in accordance with the present invention includes: a transparent electrode; a blue light-emitting layer containing a blue light-emitting material having a maximum emission wavelength 460 nm or less; a first green light-emitting layer containing a first green light-emitting material having a maximum emission wavelength in the spectrum between 460 nm and 610 nm; a red light-emitting layer containing a red light-emitting material having a maximum emission wavelength of 610 nm or more; a second green light-emitting layer containing a second green light-emitting material having a maximum emission wavelength in the spectrum between 460 nm and 610 nm; and a reflecting electrode. The maximum emission wavelength of the first green light-emitting material is located on a short wavelength side of the spectrum. The maximum emission wavelength of the second green light-emitting material is located on a long wavelength side of the spectrum.

Claims

1. An organic electroluminescent element comprising:

a transparent electrode;

a fluorescent light-emitter including a blue light-emitting layer and a first green light-emitting layer, the blue light-emitting layer containing a blue light-emitting material having a maximum emission wavelength 460 nm or less, the first green light-emitting layer containing a first green light-emitting material having a maximum emission wavelength in a spectrum between 460 nm and 610 nm;

a phosphorescent light-emitter including green light-emitting layer and a red light-emitting layer, the red light-emitting layer containing a red light-emitting material having a maximum emission wavelength of 610 nm or more, the second green light-emitting layer containing a second green light-emitting material having a maximum emission wavelength in the spectrum between 460 nm and 610 nm; and

a reflecting electrode,

wherein;

the maximum emission wavelength of the first green light-emitting material is located on a short wavelength side of the spectrum;

the maximum emission wavelength of the second green light-emitting material is located on a long wavelength side of the spectrum;

the blue light-emitting material and the first green light-emitting material are fluorescent light-emitting materials;

the second green light-emitting material and the red light-emitting material are phosphorescent light emitting materials; and

the fluorescent light-emitter and the phosphorescent light-emitter are stacked such that an intermediate layer is interposed between the fluorescent light-emitter and the phosphorescent light-emitter.

2. The organic electroluminescent element according to claim 1, wherein:

the maximum emission wavelength of the first green light-emitting material is present between 460 nm and 540 nm; and

the maximum emission wavelength of the second green light-emitting material is present between 540 nm and 610 nm.

3. The organic electroluminescent element according to claim 1, wherein

a half width of an emission spectrum of at least one of the first green light-emitting material and the second green light-emitting material is 60 nm or more.

4. The organic electroluminescent element according to claim 1, wherein

a difference between the maximum emission wavelength of the first green light-emitting material and the maximum emission wavelength of the second green light-emitting material is 35 nm or more.

5. The organic electroluminescent element according to claim 1, wherein:

the fluorescent light-emitter is disposed close to the transparent electrode; and

the phosphorescent light-emitter is disposed close to the reflecting electrode.

6. An organic electroluminescent element comprising:

a transparent electrode;

a fluorescent light-emitter including a blue light-emitting layer and a first green light-emitting layer, the blue light-emitting layer containing a blue light-emitting material having a maximum emission wavelength 460 nm or less, the first green light-emitting layer containing a first green light-emitting material having a maximum emission wavelength between 460 nm and 540 nm;

a phosphorescent light-emitter including a second green light-emitting layer and a red light-emitting layer, the second green light-emitting layer containing a second green light-emitting material having a maximum emission wavelength between 540 nm and 610 nm, the red light-emitting layer containing a red light-emitting material having a maximum emission wavelength of 610 nm or more; and

a reflecting electrode,

wherein;

a quotient of an emission intensity of the second green light-emitting layer divided by an emission intensity of the red light-emitting layer is 0.66 or less;

a quotient of an emission intensity of the blue light-emitting layer divided by an emission intensity of the red light-emitting layer is 0.20 or more;

the organic electroluminescent element is designed to emit light having a color temperature in a range of 2500 K to 3500 K;

the blue light-emitting material and the first green light-emitting material are fluorescent light-emitting materials;

the second green light-emitting material and the red light-emitting material are phosphorescent light-emitting materials;

the fluorescent light-emitter and the phosphorescent light-emitter are stacked such that an intermediate layer is interposed between the fluorescent light-emitter and the phosphorescent light-emitter.

7. The organic electroluminescent element according to claim 6, wherein

a half width of an emission spectrum of at least one of the first green light-emitting material and the second green light-emitting material is 60 nm or more.

8. The organic electroluminescent element according to claim 6, wherein

a difference between the maximum emission wavelength of the first green light-emitting material and the maximum emission wavelength of the second green light-emitting material is 35 nm or more.

9. The organic electroluminescent element according to claim 6, wherein:

the fluorescent light-emitter is disposed close to the transparent electrode; and

the phosphorescent light-emitter is disposed close to the reflecting electrode.

10. An organic electroluminescent element comprising:

a transparent electrode;

a blue light-emitting layer containing a blue light-emitting material having a maximum emission wavelength 460 nm or less;

a first green light-emitting layer containing a first green light-emitting material having a maximum emission wavelength in a spectrum between 460 nm and 610 nm;

a red light-emitting layer containing a red light-emitting material having a maximum emission wavelength of 610 nm or more;

a second green light-emitting layer containing a second green light-emitting material having a maximum emission wavelength in the spectrum between 460 nm and 610 nm; and

a reflecting electrode,

wherein;

the maximum emission wavelength of the first green light-emitting material is located on a short wavelength side of the spectrum;

the maximum emission wavelength of the second green light-emitting material is located on a long wavelength side of the spectrum; and

the organic electroluminescent element has a special color rendering index R9 which is more than 30.

11. The organic electroluminescent element according to 10, wherein:

the blue light-emitting material and the first green light-emitting material are fluorescent light-emitting materials; and

the second green light-emitting material and the red light-emitting material are phosphorescent light-emitting materials.

12. The organic electroluminescent element according to 11, wherein

a fluorescent light-emitter including the blue light-emitting layer and the first green light-emitting layer, and a phosphorescent light-emitter including the second green light-emitting layer and the red light-emitting layer are stacked such that an intermediate layer is interposed between the fluorescent light-emitter and the phosphorescent light-emitter.

13. The organic electroluminescent element according to 12, wherein:

the fluorescent light-emitter is disposed closer to the transparent electrode than the phosphorescent light-emitter; and

the phosphorescent light-emitter is disposed closer to the reflecting electrode than the fluorescent light-emitter.