Organic light emitting device and organic light emitting display device using the same
An organic light emitting device and an organic light emitting display device using the same are discussed, for changing a structure of an emissive layer to enhance viewing angle characteristics and lifespan. Emissive layers having hosts with different characteristics are stacked to prevent visual reduction depending on a viewing angle and to enhance a lifespan.
1. An organic light emitting device comprising:
first and second electrodes facing each other; and
a light emitting portion comprising first and second emissive layers that contact each other in a thickness direction between the first and second electrodes,
wherein the first emissive layer comprises a first host and a first dopant, a photoluminescence (PL) spectrum of the first host having a peak in a first wavelength, and
wherein the second emissive layer comprises a second host and a second dopant, a PL spectrum of the second host having a peak in a second wavelength, and the peak in the second wavelength being apart from the peak in the first wavelength by approximately 15 nm to 123 nm.
2. The organic light emitting device according to claim 1 , wherein the first dopant and the second dopant has a PL spectrum having a peak in the same wavelength.
3. The organic light emitting device according to claim 2 , wherein the first and second dopants are the same and have PL spectrums with a peak in a wavelength of approximately 610 nm to 630 nm.
4. The organic light emitting device according to claim 3 , wherein PL spectrums of the first host and the second host have an overlapping region with the PL spectrum of the first and second dopants, and
wherein an overlapping region between the PL spectrum of the first host and the PL spectrum of the first and second dopants is greater than an overlapping region between the PL spectrum of the second host and the PL spectrum of the first and second dopants.
5. The organic light emitting device according to claim 4 , wherein the first wavelength is approximately 495 nm to 500 nm, and
wherein the second wavelength is spaced apart from the first wavelength in the left direction by approximately 15 nm to 30 nm.
6. The organic light emitting device according to claim 5 , wherein a full width of half maximum (FWHM) of the PL spectrum of the first host is approximately 100 nm to 130 nm, and
wherein a FWHM of the second host is ½ or less of the FWHM of the first host.
7. The organic light emitting device according to claim 4 , wherein an EL peak of the second emissive layer is on the right side of an electroluminescence (EL) peak of the first emissive layer.
8. The organic light emitting device according to claim 4 , wherein a thickness ratio of the first and second emissive layers is approximately 1:0.5 to 1:2.
9. An organic light emitting display device comprising:
a substrate comprising a plurality of sub pixels;
thin film transistors disposed in the respective sub pixels; and
an organic light emitting device connected to the thin film transistor in at least one of the sub pixels,
wherein the organic light emitting device includes:
first and second electrodes facing each other; and
a light emitting portion comprising first and second emissive layers that contact each other in a thickness direction between the first and second electrodes,
wherein the first emissive layer comprises a first host and a first dopant, a photoluminescence (PL) spectrum of the first host having a peak in a first wavelength, and
wherein the second emissive layer comprises a second host and a second dopant, a PL spectrum of the second host having a peak in a second wavelength spaced apart from the first wavelength by 15 nm to 123 nm.
10. The organic light emitting display device of claim 9 , wherein the first and second dopants are the same and have the same PL spectrum with a peak in a wavelength of approximately 610 nm to 630 nm.
11. An organic light emitting device comprising:
first and second electrodes facing each other; and
a light emitting portion comprising first and second emissive layers that contact each other in a thickness direction between the first and second electrodes,
wherein the first emissive layer comprises a first host of photoluminescence (PL) spectrum having a peak in a first wavelength,
wherein the second emissive layer comprises a second host of PL spectrum having a peak in a second wavelength spaced apart from the first wavelength by approximately 15 nm to 123 nm,
wherein the first and second emissive layers further comprise dopants of a PL spectrum having a peak in the same wavelength,
wherein PL spectrums of the first host and the second host have an overlapping region with the PL spectrum of the dopant, and
wherein an overlapping region between the PL spectrum of the first host and the PL spectrum of the dopant is greater than an overlapping region between the PL spectrum of the second host and the PL spectrum of the dopant.