Light-emitting device and electronic apparatus including the same

1 . A tandem light-emitting device, comprising:

a first electrode;

a second electrode facing the first electrode;

m light-emitting units stacked between the first electrode and the second electrode, the m light-emitting units each comprising an emission layer; and

m−1 charge generation layers between two adjacent light-emitting units of the m light-emitting units, wherein

m is an integer of 5 or more,

the m light-emitting units comprise a first light-emitting unit, a second light-emitting unit, a third light-emitting unit, a fourth light-emitting unit, and a fifth light-emitting unit, in order of proximity to the first electrode,

the m−1 charge generation layers comprise a first charge generation layer, a second charge generation layer, a third charge generation layer, and a fourth charge generation layer, in order of proximity to the first electrode,

at least one of the first to fifth light-emitting units emits blue light,

at least one of the first to fifth light-emitting units emits green light,

the formula 3<D/(2*λ b )≤4 is satisfied,

D indicates a distance between the first electrode and the second electrode,

λ b indicates a maximum emission wavelength of the blue light, and

λ b is in a range of about 400 nm to about 480 nm.

2 . A tandem light-emitting device, comprising:

a first electrode;

a second electrode facing the first electrode;

m light-emitting units stacked between the first electrode and the second electrode, the m light-emitting units each comprising an emission layer; and

m−1 charge generation layers between two adjacent light-emitting units of the m light-emitting units, wherein

m is an integer of 5 or more,

the m light-emitting units comprise a first light-emitting unit, a second light-emitting unit, a third light-emitting unit, a fourth light-emitting unit, and a fifth light-emitting unit, in order of proximity to the first electrode,

the m−1 charge generation layers comprise a first charge generation layer, a second charge generation layer, a third charge generation layer, and a fourth charge generation layer, in order of proximity to the first electrode,

at least one of the first to fifth light-emitting units emits blue light,

at least one of the first to fifth light-emitting units emits green light,

the formula 3≤D/(2*λ b )≤4 is satisfied,

D indicates a distance between the first electrode and the second electrode,

λ b indicates a maximum emission wavelength of the blue light, and

λ b is in a range of about 400 nm to about 480 nm, wherein m is 5,

wherein the m-light emitting parts comprise:

three light-emitting units emitting blue light; and

two light-emitting units emitting green light.

3 . The tandem light-emitting device of claim 1 , wherein D is in a range of about 2,400 Å to about 3,800 Å.

4 . The tandem light-emitting device of claim 1 , wherein D is in a range of about 2,600 Å to about 3,400 Å.

5 . The tandem light-emitting device of claim 1 , further comprising:

a capping layer located outside the second electrode.

6 . The tandem light-emitting device of claim 2 , wherein

the first light-emitting unit, the third light-emitting unit, and the fifth light-emitting unit each emit blue light, and

the second light-emitting unit and the fourth light-emitting unit each emit green light.

7 . The tandem light-emitting device of claim 6 , wherein the first light-emitting unit, the third light-emitting unit, and the fifth light-emitting unit emit blue light of a same wavelength.

8 . The tandem light-emitting device of claim 6 , wherein the second light-emitting unit and the fourth light-emitting unit emit green light of a same wavelength.

9 . The tandem light-emitting device of claim 1 , wherein at least one of the m−1 charge generation layers comprises:

an n-type charge generation layer and a p-type charge generation layer.

10 . The tandem light-emitting device of claim 1 , wherein each of the m light-emitting units further comprises:

a hole transport region that transports holes to the emission layer; and

an electron transport region that transports electrons to the emission layer.

11 . The tandem light-emitting device of claim 10 , wherein the hole transport region comprises at least one of a hole injection layer, a hole transport layer, and an electron blocking layer.

12 . The tandem light-emitting device of claim 10 , wherein the electron transport region comprises at least one of an electron injection layer, an electron transport layer, and a hole blocking layer.

13 . The tandem light-emitting device of claim 11 , wherein each layer constituting the hole transport region in any light-emitting unit other than the first light-emitting unit and each layer constituting the electron transport region in the any light-emitting unit each have a thickness of less than or equal to about 100 Å.

14 . The tandem light-emitting device of claim 1 , wherein

at least one of the emission layers in the m light-emitting units comprises:

a first host; and

a second host, and

the first host and the second host are different from each other.

15 . The tandem light-emitting device of claim 1 , wherein at least one of the emission layers in the m light-emitting units comprises a plurality of emission layers.

16 . The tandem light-emitting device of claim 2 , wherein at least one of the plurality of emission layers of the first to fifth light-emitting units comprises an organometallic compound.

17 . An electronic apparatus comprising the tandem light-emitting device of claim 1 .

18 . The electronic apparatus of claim 17 , further comprising:

a thin-film transistor, wherein

the thin-film transistor comprises a source electrode and a drain electrode, and

the first electrode of the tandem light-emitting device is electrically connected to at least one of the source electrode and the drain electrode of the thin-film transistor.

19 . The electronic apparatus of claim 17 , further comprising:

at least one of a color filter, a color conversion layer, a quantum dot color conversion layer, a touch screen layer, and a polarizing layer.