Light-emitting device and apparatus including the same
A light-emitting device includes: a first electrode; a second electrode facing the first electrode; light-emitting units in the number of n between the first electrode and the second electrode; and a charge-generation unit(s) in the number of n−1 between the adjacent light-emitting units. The light-emitting units each include an emission layer, and at least one of the charge-generation unit(s) includes an n-type charge-generation layer, a p-type charge-generation layer, and an interlayer between the n-type charge-generation layer and the p-type charge-generation layer. The p-type charge-generation layer includes a first material and a second material, the first material includes a hole-transporting organic compound, an inorganic insulation compound, or any combination thereof, the second material includes at least one inorganic semiconductor compound, the interlayer comprises a third material, and the third material is selected from an organic compound, an inorganic semiconductor compound, and an inorganic insulation compound.
1. A light-emitting device comprising:
a first electrode;
a second electrode facing the first electrode;
light-emitting units in the number of n between the first electrode and the second electrode; and
a charge-generation unit(s) in the number of n−1 between the adjacent light-emitting units,
wherein n is a natural number of 2 or more,
the light-emitting units each comprise an emission layer,
at least one of the charge-generation unit(s) comprises an n-type charge-generation layer, a p-type charge-generation layer, and an interlayer between the n-type charge-generation layer and the p-type charge-generation layer,
the p-type charge-generation layer comprises a first material and a second material,
the first material comprises a hole-transporting organic compound, an inorganic insulation compound, or any combination thereof,
the second material comprises at least one inorganic semiconductor compound, and
the interlayer consists of a third material, the third material being at least one selected from a quinone derivative, 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN), and a compound represented by Formula 221:
wherein in Formula 221,
each of R 221 to R 223 is independently selected from a substituted or unsubstituted C 3 -C 10 cycloalkyl group, a substituted or unsubstituted C 1 -C 10 heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10 cycloalkenyl group, a substituted or unsubstituted C 1 -C 10 heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted C 1 -C 60 heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, and
wherein at least one selected from R 221 to R 223 has at least one substituent selected from a cyano group, —F, —Cl, —Br, —I, a C 1 -C 20 alkyl group substituted with —F, a C 1 -C 20 alkyl group substituted with —Cl, a C 1 -C 20 alkyl group substituted with —Br, and a C 1 -C 20 alkyl group substituted with —I.
2. The light-emitting device of claim 1 , wherein the first material is equal to or greater in volume than the second material.
3. The light-emitting device of claim 1 , wherein the first material comprises a hole-transporting organic compound, and a volume ratio of the first material to the second material is in a range of about 99:1 to about 80:20, or
the first material comprises an inorganic insulation compound, and a volume ratio of the first material to the second material is in a range of about 99:1 to about 50:50.
4. The light-emitting device of claim 1 , wherein a band gap of the third material is about 2.5 eV or more.
5. The light-emitting device of claim 1 , wherein a lowest unoccupied molecular orbital (LUMO) energy level of the third material is about −4.5 eV to about −6.5 eV.
6. The light-emitting device of claim 1 , wherein the n-type charge-generation layer comprises a first fourth material and a fifth material,
the fourth material comprises an alkali metal, an alkaline earth metal, a lanthanoid metal, a transition metal, a late transition metal, or any combination thereof, and
the fifth material comprises at least one electron-transporting organic compound.
7. The light-emitting device of claim 6 , wherein a LUMO energy level of the fifth material is smaller than a LUMO energy level of the third material.
8. The light-emitting device of claim 6 , wherein a difference between a LUMO energy level of the fifth material and a LUMO energy level of the third material is about 1 eV or less.
9. The light-emitting device of claim 1 , wherein the first electrode is an anode,
the second electrode is a cathode, and
the light-emitting unit comprises:
an n th light-emitting unit between the first electrode and the second electrode;
an n−1 th light-emitting unit between the first electrode and the n th light-emitting unit; and
an n−1 th charge-generation unit between the n th light-emitting unit and the n−1 th light-emitting unit,
wherein the n th light-emitting unit comprises an n th emission layer,
the n−1 th light-emitting unit comprises an n−1 th emission layer;
an n−1 th hole transport region is between the first electrode and the n−1 th emission layer;
an n−1 th electron transport region is between the n−1 th emission layer and the n−1 th charge-generation unit;
an n th hole transport region is between the n−1th charge-generation unit and the n th emission layer; and
an n th electron transport region is between the n th emission layer and the second electrode,
wherein the plurality of hole transport regions each independently comprise a hole injection layer, a hole transport layer, an electron blocking layer, or any combination thereof, and
the plurality of electron transport regions each independently comprise a hole blocking layer, an electron transport layer, an electron injection layer, or any combination thereof.
10. The light-emitting device of claim 9 , wherein the hole injection layer comprises a sixth material and a seventh material,
the sixth material and the seventh material are different from each other,
the sixth material comprises a halide of a lanthanoid metal, a halide of a transition metal, a halide of a late transition metal, tellurium, a telluride of a lanthanoid metal, a telluride of a transition metal, a telluride of a late transition metal, a selenide of a lanthanoid metal, a selenide of a transition metal, a selenide of a late transition metal, or any combination thereof, and
the seventh material comprises a hole-transporting organic compound, a halide of an alkali metal, a halide of an alkaline earth metal, a halide of a lanthanoid metal, or any combination thereof.
11. The light-emitting device of claim 10 , wherein the seventh material comprises at least one hole-transporting organic compound, and a volume ratio of the sixth material to the seventh material is in a range of about 1:99 to about 20:80, or
the seventh material comprises a halide of an alkali metal, a halide of an alkaline earth metal, a halide of a lanthanoid metal, or any combination thereof, and a volume ratio of the sixth material to the seventh material is in a range of about 1:99 to about 50:50.
12. The light-emitting device of claim 9 , wherein the electron injection layer comprises an eighth material, and
the eighth material comprises a halide of an alkali metal, a halide of an alkaline earth metal, a halide of a lanthanoid metal, or any combination thereof.
13. The light-emitting device of claim 12 , wherein the electron injection layer consists of the eighth material.
14. The light-emitting device of claim 12 , wherein the electron injection layer further comprises a ninth material,
the eighth material and the ninth material are different from each other, and
the ninth material comprises an alkali metal, an alkaline earth metal, a lanthanoid metal, or any combination thereof.
15. The light-emitting device of claim 14 , wherein the eighth material is represented by Formula X, and the ninth material is represented by Formula Y:
A n B m Formula X
C, Formula Y
wherein, in Formulae X and Y,
A and C each independently comprise an alkali metal, an alkaline earth metal, a lanthanoid metal, or any combination thereof,
B is a halogen,
n and m are each independently an integer of 1 or more, to make the eighth material neutral, and
A and C are different from each other.
16. The light-emitting device of claim 9 , wherein
the hole transport layer is in direct contact with the emission layer,
the hole transport layer comprises a tenth material and an eleventh material,
the tenth material and the eleventh material are different from each other,
the tenth material comprises at least one hole-transporting organic compound, and
the eleventh material comprises a halide of an alkali metal, a halide of an alkaline earth metal, a halide of a lanthanoid metal, or any combination thereof.
17. The light-emitting device of claim 9 , wherein the electron transport layer is in direct contact with the emission layer,
the electron transport layer comprises a twelfth material and a thirteenth material,
the twelfth material and the thirteenth material are different from each other,
the twelfth material comprises at least one electron-transporting organic compound, and
the thirteenth material comprises a halide of an alkali metal, a halide of an alkaline earth metal, a halide of a lanthanoid metal, or any combination thereof.