Light-emitting device and electronic apparatus including the same
A light-emitting device and an electronic apparatus including the light-emitting device. The light-emitting device includes a first electrode, a second electrode, and an interlayer arranged between the first electrode and the second electrode, the interlayer includes an emission layer, the emission layer includes one or more m1 hosts, a sensitizer, and a fluorescent emitter, where m1 is an integer of 1 or more, and when m1 is 2 or more, the two or more hosts are each different from the other, the one or more m1 hosts, the sensitizer, and the fluorescent emitter are different from each other, and Expression 1 is satisfied. 0 debye ≤ ❘ "\[LeftBracketingBar]" PDM ( S ) - PDM ( H ) ❘ "\[RightBracketingBar]" ≤ 3 debye Expression 1 Expression 1 is the same as described in the present specification.
1 . A light-emitting device comprising:
a first electrode;
a second electrode; and
an interlayer arranged between the first electrode and the second electrode, wherein the interlayer comprises an emission layer,
the emission layer comprises m1 hosts, a sensitizer, and a fluorescent emitter,
where m1 is an integer of 1 or more, and when m1 is 2 or more, the two or more hosts are each different from the other,
the m1 hosts, the sensitizer, and the fluorescent emitter are each different from the other, and
Expression 1 is satisfied:
0 debye≤|PDM( S )−PDM( H )|≤3 debye Expression 1
wherein, in Expression 1,
PDM(S) is a permanent dipole moment of the sensitizer and has a unit of debye,
PDM(H) is
∑
x
=
1
m
1
PDM
(
Hx
)
·
W
(
Hx
)
which is an average value of permanent dipole moments of the m1 hosts included in the emission layer, and has a unit of debye, wherein i) x is a variable of 1 to m1, ii) PDM(Hx) is a permanent dipole moment of an x th host in the emission layer and has a unit of debye, and iii) W(Hx) is a weight fraction of the x th host relative to a total weight of the host in the emission layer, and is calculated as (a weight of the x th host in the emission layer/a total weight of the host in the emission layer), and
each of PDM(S) and PDM(H) is calculated based on density functional theory (DFT).
2 . The light-emitting device of claim 1 , wherein PDM(S) is about 0.1 debye to about 3.0 debye.
3 . The light-emitting device of claim 1 , wherein PDM(H) is about 0.01 debye to about 4.00 debye.
4 . The light-emitting device of claim 1 , wherein Expression 2 is further satisfied:
0
eV
≤
❘
"\[LeftBracketingBar]"
S
1
(
S
)
-
T
1
(
S
)
❘
"\[RightBracketingBar]"
≤
0.4
eV
Expression
2
wherein, in Expression 2,
S 1 (S) is singlet energy of the sensitizer and has a unit of eV,
T 1 (S) is triplet energy of the sensitizer and has a unit of eV, and
each of S 1 (S) and T 1 (S) is calculated based on DFT.
5 . The light-emitting device of claim 4 , wherein S 1 (S) is about 2.25 eV to about 2.65 eV.
6 . The light-emitting device of claim 4 , wherein T 1 (S) is about 2.2 eV to about 2.6 eV.
7 . The light-emitting device of claim 1 , wherein Expression 3 is further satisfied:
0
eV
≤
❘
"\[LeftBracketingBar]"
S
1
(
FE
)
-
T
1
(
FE
)
❘
"\[RightBracketingBar]"
≤
1.5
eV
Expression
3
wherein, in Expression 3,
S 1 (FE) is singlet energy of the fluorescent emitter and has a unit of eV,
T 1 (FE) is triplet energy of the fluorescent emitter and has a unit of eV, and
each of S 1 (FE) and T 1 (FE) is calculated based on DFT.
8 . The light-emitting device of claim 1 , wherein T 1 (FE) is about 1.0 eV to about 2.5 eV,
T 1 (FE) is triplet energy of the fluorescent emitter and has a unit of eV, and
T 1 (FE) is calculated based on DFT.
9 . The light-emitting device of claim 1 , wherein FWHM(FE) is about 5 nanometers to about 50 nanometers,
FWHM(FE) is a full width at half maximum of a photoluminescence spectrum of the fluorescent emitter and has a unit of nm, and
the photoluminescence spectrum is evaluated relative to a film including the fluorescent emitter.
10 . The light-emitting device of claim 1 , wherein λmax(FE) is about 500 nm to about 550 nm,
λmax(FE) is a maximum emission peak wavelength of a photoluminescence spectrum of the fluorescent emitter and has a unit of nm, and
the photoluminescence spectrum is evaluated with respect to a film including the fluorescent emitter.
11 . The light-emitting device of claim 1 , wherein the m1 hosts independently comprise a hole-transporting compound, an electron-transporting compound, a bipolar compound, or any combination thereof.
12 . The light-emitting device of claim 1 , wherein the sensitizer comprises a platinum-containing organometallic compound,
the platinum-containing organometallic compound comprises platinum and a tetradentate ligand bonded to the platinum, and
at least one of chemical bonds between the platinum and the tetradentate ligand is a platinum-carbon chemical bond.
13 . The light-emitting device of claim 12 , wherein one of the chemical bonds between the platinum and the tetradentate ligand is a platinum-oxygen chemical bond.
14 . The light-emitting device of claim 12 , wherein the tetradentate ligand comprises one benzimidazole group.
15 . The light-emitting device of claim 1 , wherein the fluorescent emitter does not comprise a transition metal.
16 . The light-emitting device of claim 1 , wherein the fluorescent emitter is a thermally activated delayed fluorescence emitter comprising at least one 6-membered ring comprising at least one nitrogen (N) and at least one boron (B).
17 . The light-emitting device of claim 1 , wherein the fluorescent emitter is a prompt fluorescence emitter comprising at least one 5-membered ring or 6-membered ring comprising at least one boron (B).
18 . The light-emitting device of claim 1 , wherein the interlayer comprises:
m light-emitting units comprising at least one emission layer; and
m−1 charge generation layers arranged between two adjacent light-emitting units among the m light-emitting units,
m is an integer of 2 or more, and
at least one light-emitting unit among the m light-emitting units comprises the emission layer comprising the m1 hosts, the sensitizer, and the fluorescent emitter, and the Expression 1 is satisfied.
19 . The light-emitting device of claim 18 , wherein the at least one light-emitting unit among the m light-emitting units emits blue light.
20 . An electronic apparatus comprising the light-emitting device of claim 1 .