White light-emitting organic electroluminescent element and white light-emitting organic electroluminescent panel
View Patent ↗A white light-emitting organic electroluminescent element includes at least four kinds of light-emitting dopants with different emission peak wavelengths which are present between a cathode and an anode. The four kinds of light-emitting dopants include a light-emitting dopant “A”, a light-emitting dopant “B”, a light-emitting dopant “C”, and a light-emitting dopant “D” having their own peak wavelengths which are longer in this order. The white light-emitting organic electroluminescent element has an emission spectrum which satisfies relations of: (first average luminance for an angle in a range of 50° to 70°/first front luminance)>(second average luminance for an angle in a range of 50° to 70°/second front luminance); and (third average luminance for an angle in a range of 50° to 70°/third front luminance)>(fourth average luminance for an angle in a range of 50° to 70°/fourth front luminance).
1. A white light-emitting organic electroluminescent element comprising:
a cathode,
an anode, and
at least four kinds of light-emitting dopants including a light-emitting dopant “A”, a light-emitting dopant “B”, a light-emitting dopant “C”, and a light emitting dopant “D”, the at least four kinds of light-emitting dopants being located between the cathode and the anode,
wherein
a peak wavelength of the light emitting dopant “A” is shorter than a peak wavelength of the light emitting dopant “B”, the peak wavelength of the light emitting dopant “B” is shorter than a peak wavelength of the light emitting dopant “C”, and the peak wavelength of the light emitting dopant “C” is shorter than a peak wavelength of the light emitting dopant “D”,
wherein
when
a first luminance is a luminance at the peak wavelength of the light-emitting dopant “A”, a second luminance is a luminance at the peak wavelength of the light-emitting dopant “D”, a third luminance is a luminance at the peak wavelength of the light-emitting dopant “C” and a fourth luminance is a luminance at the peak wavelength of the light-emitting dopant “B”, and
when
a normal direction of the white light-emitting organic electroluminescent element is in the 0° direction;
a first average luminance is an average luminance of the first luminance in a range of 50° to 70°,
a second average luminance is an average luminance of the second luminance in a range of 50° to 70°,
a third average luminance is an average luminance of the third luminance in a range of 50° to 70°, and
a fourth average luminance is an average luminance of the fourth luminance in a range of 50° to 70°, and
a first front luminance is a luminance of the first luminance in the normal direction,
a second front luminance is a luminance of the second luminance in the normal direction,
a third front luminance is a luminance of the third luminance in the normal direction, and
a fourth front luminance is a luminance of the fourth luminance in the normal direction,
wherein
a first ratio of the first average luminance to the first front luminance is more than a second ratio of the second average luminance to the second front luminance, and
a third ratio of the third average luminance to the third front luminance is more than a fourth ratio of the fourth average luminance to the fourth front luminance.
2. The white light-emitting organic electroluminescent element according to claim 1 , wherein:
the peak wavelength of the light-emitting dopant “B” is between 480 nm and 520 nm; and
the peak wavelength of the light-emitting dopant “C” is between 520 nm and 580 nm.
3. The white light-emitting organic electroluminescent element according to claim 1 , wherein:
the light-emitting dopant “A” is a blue light-emitting dopant; and
the light-emitting dopant “D” is a red light-emitting dopant.
4. The white light-emitting organic electroluminescent element according to claim 1 , wherein
the first ratio is more than 1.
5. The white light-emitting organic electroluminescent element according to claim 1 , wherein
the second ratio is less than 1.
6. The white light-emitting organic electroluminescent element according to claim 1 , further comprising:
a first light-emitting unit,
a second light-emitting unit stacked on the first light-emitting unit, and
an intermediate connecting layer connecting the first light-emitting unit and the second light-emitting unit, the intermediate connecting layer, the first light-emitting unit and the second light-emitting unit being disposed between the cathode and the anode, wherein:
the first light-emitting unit includes the light-emitting dopant “A” and the second light-emitting unit includes the light-emitting dopant “C” and the light-emitting dopant “D”.
7. The white light-emitting organic electroluminescent element according to claim 6 , wherein:
the first light-emitting unit further includes the light-emitting dopant “B”; and
the light-emitting dopant “B” is a singlet light-emitting material.
8. The white light-emitting organic electroluminescent element according to claim 6 , wherein:
one of the anode and the cathode is a reflective electrode;
the first lighting emitting unit is provided farther from the reflective electrode than the second light-emitting unit is provided; and
the white light-emitting organic electroluminescent element emits white light having a correlated color temperature in a range of 2000 K to 4500 K.
9. The white light-emitting organic electroluminescent element according to claim 1 , wherein
an emission spectrum is derived from only the at least four kinds of the light-emitting dopants.
10. The white light-emitting organic electroluminescent element according to claim 6 , wherein:
the second light-emitting unit further includes the light-emitting dopant “B”; and
the light-emitting dopant “B” is a triplet light-emitting material.
11. The white light-emitting organic electroluminescent element according to claim 1 , wherein:
the light-emitting dopant “A” is a singlet light-emitting material; and
the light-emitting dopant “C” and the light-emitting dopant “D” are triplet light-emitting materials.
12. The white light-emitting organic electroluminescent element according to claim 1 , further comprising:
a light diffusion layer scattering light and disposed on one of the anode and the cathode.
13. A white light-emitting organic electroluminescent panel, comprising:
a whitelight-emitting organic electroluminescent element comprising:
a cathode,
an anode, and
at least four kinds of light-emitting dopants including a light-emitting dopant “A”, alight-emitting dopant“B”, a light-emittingdopant“C”,and a light emitting dopant“D”, the at least four kinds of light-emitting dopants being located between the cathode and the anode,
wherein
a peak wavelength of the light emitting dopant“A” is shorter than a peak wavelength of the light emitting dopant “B”, the peak wavelength of the light emitting dopant “B” is shorter than a peak wavelength of the light emitting dopant “C”, and the peak wavelength of the light emitting dopant “C” is shorter than a peak wavelength of the light emitting dopant “D”,
wherein
when
a first luminance is a luminance at the peakwave length of the light-emitting dopant “A”, a second luminance is aluminance at the peak wavelength of the light-emitting dopant“D”, a third luminance is a luminance at the peak wavelength of the light-emitting dopant “C” and a fourth luminance is a luminance at the peak wavelength of the light-emitting dopant “B”, and
when
a normal direction of the white light-emitting organic electroluminescent element is in the 0° direction;
a first average luminance is an average luminance of the first luminance in a range of 50° to 70°,
a second average luminance is an average luminance of the second luminance in a range of 50° to 70°,
a third average luminance is an average luminance of the third luminance in a range of 50° to 70° ,and
a fourth average luminance is an average luminance of the fourth luminance in a range of 50° to 70° , and
a first front luminance is a luminance of the first luminance in the normal direction,
a second front luminance is a luminance of the second luminance in the normal direction,
a third front luminance is a luminance of the third luminance in the normal direction, and
a fourth front luminance is a luminance of the fourth luminance in the normal direction,
wherein
a first ratio of the first average luminance to the first front luminance is more than a second ratio of the second average luminance to the second front luminance, and
a third ratio of the third average luminance to the third front luminance is more than a fourth ratio of the fourth average luminance to the fourth front luminance; and
a light diffusion layer scattering light and disposed on a light-extracting face of the white light-emitting organic electroluminescent element.