White organic light emitting device including multiple stacks having three photoluminescence peaks and organic light emitting display device using the same
A white organic light emitting device, which is increased in color gamut and lifespan, is discussed and an organic light emitting display device using the same and in a stack having different emission layers disposed in contact with each other, particular properties of a host and a dopant in a major emission layer are used.
1. A white organic light emitting device, comprising:
first to third stacks sequentially disposed on a first electrode, and a second electrode on the third stack,
wherein one of the first to third stacks includes a first emission layer and a second emission layer that emit different colors of light, and the first emission layer and the second emission layer are in contact with each other,
wherein the first emission layer includes a single electron transport host and a first dopant having a lowest unoccupied molecular orbital (LUMO) energy level lower than a LUMO energy level of the single electron transport host,
wherein the second emission layer includes a second dopant different from the first dopant, and
wherein the first dopant has a highest occupied molecular orbital (HOMO) energy level higher than a HOMO energy level of the single electron transport host.
2. The device according to claim 1 , wherein the first dopant has an energy band gap ranging from 2.5 eV to 2.7 eV.
3. The device according to claim 2 , wherein the single electron transport host has an electron mobility ranging from 1.0×10 −4 cm 2 /Vs to 1.0×10 −2 cm 2 /Vs.
4. The device according to claim 1 , wherein the first emission layer is a green emission layer having a first photoluminescence peak within a wavelength range from 520 nm to 560 nm, and
wherein the second emission layer is a red emission layer having a second photoluminescence peak within a wavelength range from 600 nm to 650 nm.
5. The device according to claim 4 , wherein each of the two stacks having no first and second emission layers includes a blue emission layer having a third photoluminescence peak within a wavelength range from 440 nm to 470 nm.
6. The device according to claim 1 , wherein the first emission layer includes a plurality of first emission layers.
7. The device according to claim 6 , wherein the first emission layers respectively include the same host and the first dopant having different doping concentrations.
8. The device according to claim 1 , further comprising:
a first charge generation layer between the first stack and the second stack; and
a second charge generation layer between the second stack and the third stack.
9. The device according to claim 8 , wherein the first and second emission layers are located in the second stack, and the second emission layer is closer to the first charge generation layer than the first emission layer, and
wherein the first and third stacks include first and second blue emission layers, respectively.
10. The device according to claim 9 , further comprising a common layer on at least one location selected from a location between the first blue emission layer and the first electrode, a location between the second blue emission layer and the second electrode, a location between the second emission layer and the first charge generation layer, a location between the first emission layer and the second charge generation layer, a location between the first blue emission layer and the first charge generation layer, and a location between the second charge generation layer and the second blue emission layer.
11. The device according to claim 9 , further comprising a common layer provided on at least one location selected from among a location between the first blue emission layer and the first electrode, a location between the second blue emission layer and the second electrode, a location between the second emission layer and the first charge generation layer, a location between the first emission layer and the second charge generation layer, a location between the first blue emission layer and the first charge generation layer, and a location between the second charge generation layer and the second blue emission layer.
12. An organic light emitting display device comprising:
a plurality of sub-pixels on a substrate;
a driving transistor in each sub-pixel; and
an organic light emitting diode including a first electrode and a second electrode, one of which is connected to the driving transistor, opposite each other, and first to third stacks between the first electrode and the second electrode,
wherein one of the first to third stacks includes a first emission layer and a second emission layer that emit different colors of light, and the first emission layer and the second emission layer are in contact with each other,
wherein the first emission layer includes a single electron transport host and a first dopant having a LUMO energy level lower than a LUMO energy level of the single electron transport host,
wherein the second emission layer includes a second dopant different from the first dopant, and
wherein the first dopant has a highest occupied molecular orbital (HOMO) energy level higher than a HOMO energy level of the single electron transport host.
13. The device according to claim 12 , wherein the first emission layer is a green emission layer having a first photoluminescence peak within a wavelength range from 520 nm to 560 nm, and
wherein the second emission layer is a red emission layer having a second photoluminescence peak within a wavelength range from 600 nm to 650 nm.
14. The device according to claim 13 , wherein each of the other two stacks having no first and second emission layers includes a blue emission layer having a third photoluminescence peak within a wavelength range from 440 nm to 470 nm.
15. The device according to claim 12 , further comprising:
a first charge generation layer between the first stack and the second stack; and
a second charge generation layer between the second stack and the third stack.
16. The device according to claim 15 , wherein the first and second emission layers are located in the second stack, and the second emission layer is closer to the first charge generation layer than the first emission layer, and the first and third stacks include first and second blue emission layers, respectively.
17. The device according to claim 12 , wherein the first emission layer includes a plurality of first emission layers.
18. The device according to claim 17 , wherein the first emission layers respectively include the same host and the first dopant having different doping concentrations.