Organic light-emitting device comprising host, phosphorescent dopant and fluorescent dopant
According to an aspect, an organic light-emitting device includes: a first electrode; a second electrode facing the first electrode; and an emission layer disposed between the first electrode and the second electrode and including a host and a dopant, wherein the host is an exciplex host, which is a combination of a hole transporting host and an electron transporting host which form an exciplex, or a delayed fluorescent organic compound, and the dopant includes both a phosphorescent dopant and a fluorescent dopant.
1. An organic light-emitting device comprising:
a first electrode;
a second electrode facing the first electrode; and
an emission layer disposed between the first electrode and the second electrode and comprising a delayed fluorescent host and a dopant,
wherein the delayed fluorescent host comprises:
an exciplex host which is a combination of a hole transporting host and an electron transporting host that combine together to form an exciplex; or
a delayed fluorescent organic compound in the form of D-C-A (an electron donation group: D—a connecting group: C—an electron accepting group: A), in the form of D-C-A-C-D, or in the form of A-C-D-C-A, and
the dopant comprises both a phosphorescent dopant and a fluorescent dopant
wherein a triplet excited state energy level of the phosphorescent dopant is higher than a singlet excited state energy level and a triplet excited state energy level of the fluorescent dopant, and
wherein a photoluminescence spectrum of the delayed fluorescent host overlaps an absorption spectrum of the fluorescent dopant, and a photoluminescence spectrum of the phosphorescent dopant overlaps an absorption spectrum of the fluorescent dopant.
2. The organic light-emitting device of claim 1 , wherein a difference between a singlet exciplex energy level and a triplet exciplex energy level of the exciplex host is about 0 eV or more to less than about 0.3 eV.
3. The organic light-emitting device of claim 1 , wherein the singlet exciplex energy level and the triplet exciplex energy level of the exciplex host are higher than a singlet excited energy level of the fluorescent dopant.
4. The organic light-emitting device of claim 1 , wherein a lower unoccupied molecular orbital (LUMO) of the hole transporting host is higher than that of the electron transporting host by about 0.2 eV or more, but not as high as a band gap of the hole transporting host, and a highest occupied molecular orbital (HOMO) of the hole transporting host is higher than that of the electron transporting host by about 0.2 eV or more, but not as high as a band gap of the hole transporting host.
5. The organic light-emitting device of claim 1 , wherein, when the delayed fluorescent host comprises the exciplex host, a weight ratio of the hole transporting host to the electron transporting host is in a range of about 20:80 to about 80:20.
6. The organic light-emitting device of claim 1 , wherein, when the delayed fluorescent host comprises the delayed fluorescent organic compound, a difference between a singlet excited state energy level and a triplet excited state energy level of the delayed fluorescent organic compound is about 0 eV or more to less than about 0.3 eV.
7. The organic light-emitting device of claim 1 , wherein, when the delayed fluorescent host comprises the delayed fluorescent organic compound, a singlet excited state energy level and a triplet excited state energy level of the delayed fluorescent organic compound are higher than a singlet excited state energy level of the fluorescent dopant.
8. The organic light-emitting device of claim 1 , wherein a singlet excited state energy of the exciplex or a singlet excited state energy of the delayed fluorescent organic compound is transferred to the fluorescent dopant.
9. The organic light-emitting device of claim 1 , wherein the hole transporting host comprises a carbazole derivative or an aromatic amine compound.
10. The organic light-emitting device of claim 1 , wherein the electron transporting host comprises a π-electron deficient heteroaromatic ring.
11. The organic light-emitting device of claim 1 , wherein the electron transporting host comprises a phosphine oxide group-containing compound, a sulfur oxide group-containing group, or a triazine derivative.
12. The organic light-emitting device of claim 1 , wherein the phosphorescent dopant comprises a transition metal complex.
13. The organic light-emitting device of claim 1 , wherein the phosphorescent dopant comprises a complex comprising iridium (Ir), platinum (Pt), osmium (Os), gold (Au), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), or thulium (Tm).
14. The organic light-emitting device of claim 1 , wherein a weight ratio of the delayed fluorescent host:phosphorescent dopant:fluorescent dopant is in a range of about 99.8:0.1:0.1 to about 70:15:15.
15. The organic light-emitting device of claim 1 , further comprising a hole transporting region between the emission layer and the first electrode.
16. The organic light-emitting device of claim 1 , further comprising an electron transporting region between the emission layer and the second electrode.