Organic electroluminescent element and electronic device drivable at low voltage with improved lifetime
An organic electroluminescence device includes a first emitting unit, a first charge generating layer, a second emitting unit, a second charge generating layer, and a third emitting unit provided between an anode and a cathode in this order from the anode, in which the second charge generating layer includes an N layer close to the anode and a P layer close to the cathode, the third emitting layer contains a blue fluorescent compound, at least one of the first or second emitting layer contains a blue fluorescent compound, the third emitting unit includes a hole transporting zone between the second charge generating layer and the third emitting layer, the hole transporting zone is in contact with the second charge generating layer, and a thickness of the hole transporting zone is in a range from 5 nm to 40 nm and smaller than a thickness of the N layer.
1. An organic electroluminescence device comprising:
an anode;
a cathode;
a first emitting unit comprising a first emitting layer;
a first charge generating layer;
a second emitting unit comprising a second emitting layer;
a second charge generating layer; and
a third emitting unit comprising a third emitting layer, wherein
the first emitting unit, the first charge generating layer, the second emitting unit, the second charge generating layer, and the third emitting unit are provided between the anode and the cathode in this order from the anode,
the second charge generating layer comprises an N layer close to the anode and a P layer close to the cathode,
the third emitting layer comprises a blue fluorescent compound,
at least one of the first emitting layer or the second emitting layer comprises a blue fluorescent compound,
the third emitting unit further comprises a hole transporting zone of the third emitting unit between the second charge generating layer and the third emitting layer,
the hole transporting zone of the third emitting unit is in contact with the second charge generating layer, and
a thickness of the hole transporting zone of the third emitting unit is in a range from 5 nm to 40 nm and smaller than a thickness of the N layer, and
the thickness of the N layer is 40 nm or more.
2. The organic electroluminescence device according to claim 1 , wherein
one of the anode and the cathode is a reflective electrode, and
the organic electroluminescence device satisfies numerical formulae (1-3) and (2-3),
n 3 −0.25< m 3 <n 3 +0.25 (1-3)
in the numerical formula (1-3), n 3 represents an integer of 0 or more, and m 3 represents an order of interference between the reflective electrode and a light emission center of the third emitting layer,
m 3 =2 L 3 /λ 3 +ϕ 3 /2π (2-3)
in the formula (2-3), m 3 represents the same as m 3 in the numerical formula (1-3), L 3 represents an optical distance (nm) between the reflective electrode and the light emission center of the third emitting layer, λ 3 represents a main peak wavelength (nm) of light emission from the third emitting layer, and ϕ 3 represents a phase change occurring when the light emission from the third emitting layer is reflected on the reflective electrode.
3. The organic electroluminescence device according to claim 2 , wherein
n 3 represents an integer from 0 to 3 in the formula (1-3).
4. The organic electroluminescence device according to claim 2 , wherein
the organic electroluminescence device further satisfies numerical formulae (1-2) and (2-2),
n 2 −0.25< m 2 <n 2 +0.25 (1-2)
in the numerical formula (1-2), n 2 represents an integer of 0 or more, and m 2 represents an order of interference between the reflective electrode and a light emission center of the second emitting layer,
m 2 =2 L 2 /λ 2 +ϕ 2 /2π (2-3)
in the formula (2-2), m 2 represents the same as m 2 in the numerical formula (1-2), L 2 represents an optical distance (nm) between the reflective electrode and the light emission center of the second emitting layer, λ 2 represents a main peak wavelength (nm) of light emission from the second emitting layer, and Φ 2 represents a phase change occurring when the light emission from the second emitting layer is reflected on the reflective electrode.
5. The organic electroluminescence device according to claim 4 , wherein
n 2 represents an integer from 0 to 3 in the formula (1-2).
6. The organic electroluminescence device according to claim 2 , wherein
the organic electroluminescence device further satisfies numerical formulae (1-1) and (2-1),
n 1 −0.25< m 1 <n 1 +0.25 (1-1)
in the numerical formula (1-1), n 1 represents an integer of 0 or more, and m 1 represents an order of interference between the reflective electrode and a light emission center of the first emitting layer,
m 1 =2 L 1 /λ 1 +ϕ 1 /2π (2-3)
in the formula (2-1), m 1 represents the same as m 1 in the numerical formula (1-1), L 1 represents an optical distance (nm) between the reflective electrode and the light emission center of the first emitting layer, λ 1 represents a main peak wavelength (nm) of light emission from the first emitting layer, and Φ 1 represents a phase change occurring when the light emission from the first emitting layer is reflected on the reflective electrode.
7. The organic electroluminescence device according to claim 6 , wherein
n 1 represents an integer from 0 to 3 in the formula (1-1).
8. The organic electroluminescence device according to claim 1 , wherein
a main peak wavelength of the light emission from the third emitting layer is in a range from 430 nm to 500 nm.
9. The organic electroluminescence device according to claim 1 , wherein
the hole transporting zone of the third emitting unit comprises two or more layers.
10. The organic electroluminescence device according to claim 1 , wherein
the second emitting unit further comprises a hole transporting zone of the second emitting unit between the first charge generating layer and the second emitting layer,
the hole transporting zone of the second emitting unit is in contact with the first charge generating layer, and
a thickness of the hole transporting zone of the second emitting unit is in a range from 5 nm to 40 nm.
11. The organic electroluminescence device according to claim 10 , wherein
the hole transporting zone of the second emitting unit comprises two or more layers.
12. The organic electroluminescence device according to claim 1 , wherein
the second emitting layer comprises a blue fluorescent compound.
13. The organic electroluminescence device according to claim 12 , wherein
a main peak wavelength of the light emission from the second emitting layer is in a range from 430 nm to 500 nm.
14. The organic electroluminescence device according to claim 1 , wherein
the first emitting unit further comprises a hole transporting zone of the first emitting unit between the anode and the first emitting layer,
the hole transporting zone of the first emitting unit is in contact with the anode, and
a thickness of the hole transporting zone of the first emitting unit is in a range from 5 nm to 40 nm.
15. The organic electroluminescence device according to claim 14 , wherein
the hole transporting zone of the first emitting unit comprises three or more layers.
16. The organic electroluminescence device according to claim 1 , wherein
the first emitting layer comprises a blue fluorescent compound.
17. The organic electroluminescence device according to claim 16 , wherein
a main peak wavelength of the light emission from the first emitting layer is in a range from 430 nm to 500 nm.
18. The organic electroluminescence device according to claim 1 , wherein
the anode is a reflective electrode and light is extracted through the cathode.
19. The organic electroluminescence device according to claim 1 , wherein
the cathode is a reflective electrode and light is extracted through the anode.
20. An electronic device comprising the organic electroluminescence device according to claim 1 .