OLED array substrate with microcavity structure, and OLED display panel
The present disclosure provides an OLED array substrate comprising a plurality of pixel units each including a plurality of sub-pixel units, each of the sub-pixel units comprising a light-emitting portion, each light-emitting portion having a first electrode, a second electrode and an organic light-emitting layer sandwiched between the first electrode and the second electrode, wherein the sub-pixel unit further comprises an organic film layer and a semi-reflecting mirror layer disposed successively on a light exit side of the second electrode, the first electrode comprises a reflective layer, the second electrode is a transparent electrode, a structure between the first electrode and the semi-reflecting mirror layer constitutes a microcavity structure, and organic film layers of the sub-pixel units of different colors of each pixel unit have different thicknesses. The present disclosure further provides an OLED display panel, an OLED display device, and a method of manufacturing the array substrate.
1. An OLED array substrate comprising a plurality of pixel units each including a plurality of sub-pixel units, each of the sub-pixel units comprising a light-emitting portion, each light-emitting portion having a first electrode, a second electrode, and an organic light-emitting layer sandwiched between the first electrode and the second electrode, wherein the first electrode is located further from a light exit side than the second electrode,
wherein each sub-pixel unit further comprises an organic film layer and a semi-reflecting mirror layer disposed successively on a light exit side of the second electrode, the first electrode comprises a reflective layer, the second electrode is a transparent electrode, a structure between the first electrode and the semi-reflecting mirror layer constitutes a microcavity structure, and organic film layers of the sub-pixel units of different colors of each pixel unit have different thicknesses, and
wherein in each sub-pixel unit, the semi-reflecting mirror layer is a metal layer in which a plurality of holes are regularly arranged, and size, density and arrangement of the plurality of holes are related to a thickness of the organic film layer.
2. The OLED array substrate according to claim 1 , wherein the thickness of the organic film layer is designed according to an effective cavity length of the microcavity structure, a full width at half maximum of an emission peak and the Fabry-Perot formula, wherein
the effective cavity length L(λ) of the microcavity structure is calculated by the following formula:
L
(
λ
)
≈
λ
2
(
R
Δ
n
)
+
∑
j
n
j
d
j
cos
θ
+
|
Φ
m
4
π
λ
|
(
1
)
where λ is a resonant wavelength of light emitted from a corresponding light-emitting portion, R is an effective reflectance of the first electrode, Δn is a difference between refractive indexes of two materials that form the semi-reflecting mirror layer and the first electrode, n j and d j are a refractive index and a thickness of a material of a j-th layer, respectively, Φ m is a reflection-induced retardance of light on the semi-reflecting mirror layer and a term
∑
j
n
j
d
j
cos
θ
takes into account all the layers sandwiched between the first electrode and the semi-reflecting mirror layer,
the full width at half maximum Δλ of the emission peak is calculated by the following formula:
Δλ
=
λ
2
2
nL
(
λ
)
×
1
-
R
1
R
2
π
(
R
1
R
2
)
1
/
4
(
2
)
where λ is a resonant wavelength of light emitted from a corresponding light-emitting portion, R is an effective reflectance of the first electrode, L(λ) is the effective cavity length of the microcavity structure calculated according to the formula (1), and R 1 , R 2 are specular reflectances of the first electrode and the semi-reflecting mirror layer, respectively,
the Fabry-Perot formula is:
(
φ
1
+
φ
2
)
+
4
π
λ
∑
j
n
j
d
j
cos
[
arcsin
(
sin
θ
n
j
)
]
=
2
m
π
(
3
)
where m is a nonnegative integer, φ 1 and φ 2 are reflection-induced retardances of the first electrode and the semi-reflecting mirror layer, the units of which are radian, n j and d j are a refractive index and a thickness of a j-th layer, respectively,
arcsin
(
sin
θ
n
j
)
is an angle of light in the j-th layer measured from a normal line perpendicular to a plane of the light-emitting portion, λ is a resonant wavelength of light emitted from the light-emitting portion, and a term
4
π
λ
∑
j
n
j
d
j
cos
[
arcsin
(
sin
θ
n
j
)
]
takes into account all the layers sandwiched between the first electrode and the semi-reflecting mirror layer.
3. The OLED array substrate according to claim 1 , wherein the sub-pixel unit further comprises a color film layer disposed on a light exit side of the semi-reflecting mirror layer, and color film layers of the sub-pixel units of different colors of the pixel unit have different colors.
4. The OLED array substrate according to claim 3 , further comprising a secondary encapsulation layer disposed on a light exit side of the color film layer of each of the sub-pixel units, the secondary encapsulation layer having a thickness of about 3.0 to 3.5 μm.
5. The OLED array substrate according to claim 4 , wherein the secondary encapsulation layer includes an acrylate-based adhesive and a glass cover.
6. The OLED array substrate according to claim 1 , wherein the organic film layer is formed of a low-temperature curing material, and the low-temperature curing material has a curing temperature of not higher than about 100° C.
7. The OLED array substrate according to claim 6 , wherein the low-temperature curing material includes one or more of an epoxy resin, an acrylic resin, a phenol resin, and a polyurethane.
8. The OLED array substrate according to claim 1 , wherein the semi-reflecting mirror layer has a thickness of about 100 to 150 nm.
9. The OLED array substrate according to claim 1 , wherein the first electrode has a thickness of about 90 to 100 nm.
10. The OLED array substrate according to claim 1 , wherein the second electrode has a thickness of about 100 to 150 nm.
11. The OLED array substrate according to claim 1 , wherein the sub-pixel unit further comprises an encapsulation layer disposed between the second electrode and the organic film layer, the encapsulation layer having a thickness of about 3.0 to 3.5 μm, and the microcavity structure further comprising the encapsulation layer.
12. The OLED array substrate according to claim 1 , further comprising a pixel definition layer disposed between the first electrode and the organic light-emitting layer of each of the sub-pixel units, wherein the pixel definition layer has a thickness of about 1.0 to 1.5 μm.
13. The OLED array substrate according to claim 1 , wherein the organic light-emitting layer has a thickness of about 200 to 300 nm.
14. An OLED display panel comprising the OLED array substrate according to claim 1 .
15. The OLED display panel according to claim 14 , wherein the thickness of the organic film layer is designed according to an effective cavity length of the microcavity structure, a full width at half maximum of an emission peak and the Fabry-Perot formula,
wherein
the effective cavity length L( 2 ) of the microcavity structure is calculated by the following formula:
L
(
λ
)
≈
λ
2
(
R
Δ
n
)
+
∑
j
n
j
d
j
cos
θ
+
|
Φ
m
4
π
λ
|
(
1
)
where λ is a resonant wavelength of light emitted from a corresponding light-emitting portion, R is an effective reflectance of the first electrode, Δn is a difference between refractive indexes of two materials that form the semi-reflecting mirror layer and the first electrode, n j and d j are a refractive index and a thickness of a material of a j-th layer, respectively, Φ m is a reflection-induced retardance of light on the semi-reflecting mirror layer, and a term
∑
j
n
j
d
j
cos
θ
takes into account all the layers sandwiched between the first electrode and the semi-reflecting mirror layer,
the full width at half maximum Δλ of the emission peak is calculated by the following formula:
Δλ
=
λ
2
2
nL
(
λ
)
×
1
-
R
1
R
2
π
(
R
1
R
2
)
1
/
4
(
2
)
where λ is a resonant wavelength of light emitted from a corresponding light-emitting portion, R is an effective reflectance of the first electrode, L(λ) is the effective cavity length of the microcavity structure calculated according to the formula (1), and R 1 , R 2 are specular reflectances of the first electrode and the semi-reflecting mirror layer, respectively,
the Fabry-Perot formula is:
(
φ
1
+
φ
2
)
+
4
π
λ
∑
j
n
j
d
j
cos
[
arcsin
(
sin
θ
n
j
)
]
=
2
m
π
(
3
)
where m is a nonnegative integer, φ 1 and φ 2 are reflection-induced retardances of the first electrode and the semi-reflecting mirror layer, the units of which are radian, n j and d j are a refractive index and a thickness of a j-th layer, respectively,
arcsin
(
sin
θ
n
j
)
is an angle of light in the j-th layer measured from a normal line perpendicular to a plane of the light-emitting portion, λ is a resonant wavelength of light emitted from the light-emitting portion, and a term
4
π
λ
∑
j
n
j
d
j
cos
[
arcsin
(
sin
θ
n
j
)
]
takes into account all the layers sandwiched between the first electrode and the semi-reflecting mirror layer.
16. The OLED display panel according to claim 14 , wherein the sub-pixel unit further comprises a color film layer disposed on a light exit side of the semi-reflecting mirror layer, and color film layers of the sub-pixel units of different colors of the pixel unit have different colors.