U.S. patent application number 11/942306 was filed with the patent office on 2008-05-29 for organic light emitting display device and method of fabricating the same.
This patent application is currently assigned to Samsung SDI Co., Ltd.. Invention is credited to Hee-Seong Jeong, Sam-II Kho, Gun-Shik Kim, Seong-Taek Lee, Jun-Sik Oh, Byeong-Wook Yoo.
Application Number | 20080122348 11/942306 |
Document ID | / |
Family ID | 39218755 |
Filed Date | 2008-05-29 |
United States Patent
Application |
20080122348 |
Kind Code |
A1 |
Jeong; Hee-Seong ; et
al. |
May 29, 2008 |
ORGANIC LIGHT EMITTING DISPLAY DEVICE AND METHOD OF FABRICATING THE
SAME
Abstract
An organic light emitting display device (OLED) suppressing a
resonance effect and having an enhanced luminance, and a method of
fabricating the same, are disclosed. One embodiment of the OLED
includes: a substrate; a first electrode disposed over the
substrate and having a reflective layer; an organic layer disposed
over the first electrode and having a white emission layer; a
second electrode disposed over the organic layer; and a
transmittance controlled layer (TCL) disposed over the second
electrode and having an optical path length of about 260 to about
1520 .ANG..
Inventors: |
Jeong; Hee-Seong; (Suwon-si,
KR) ; Kho; Sam-II; (Suwon-si, KR) ; Yoo;
Byeong-Wook; (Suwon-si, KR) ; Lee; Seong-Taek;
(Suwon-si, KR) ; Oh; Jun-Sik; (Suwon-si, KR)
; Kim; Gun-Shik; (Suwon-si, KR) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Assignee: |
Samsung SDI Co., Ltd.
Suwon-si
KR
|
Family ID: |
39218755 |
Appl. No.: |
11/942306 |
Filed: |
November 19, 2007 |
Current U.S.
Class: |
313/504 ;
445/24 |
Current CPC
Class: |
H01L 51/5262 20130101;
H01L 2251/558 20130101; H01L 51/5036 20130101 |
Class at
Publication: |
313/504 ;
445/24 |
International
Class: |
H01J 9/00 20060101
H01J009/00; H01J 1/62 20060101 H01J001/62 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2006 |
KR |
10-2006-118378 |
Claims
1. An organic light emitting display device (OLED), comprising: a
substrate; a first electrode formed over the substrate, the first
electrode comprising a reflective layer, the reflective layer being
substantially reflective to visible light; an organic layer formed
over the first electrode, the organic layer comprising at least one
light emission layer configured to emit white light; a second
electrode formed over the organic layer; and a transmittance
controlled layer (TCL) formed on the second electrode, the
transmittance controlled layer having an optical path length of
about 260 .ANG. to about 1520 .ANG., wherein the optical path
length extends in the direction of the thickness of the
transmittance controlled layer.
2. The OLED of claim 1, wherein the reflective layer comprises at
least one selected from the group consisting of aluminum, silver
and an alloy thereof.
3. The OLED of claim 1, wherein the at least one light emission
layer is a single layer.
4. The OLED of claim 1, wherein the at least one light emission
layer comprises multiple layers.
5. The OLED of claim 4, wherein the multiple layers comprise an
orange-red emission layer and a blue emission layer.
6. The OLED of claim 4, wherein the multiple layers comprise at
least two of a blue emission layer, a green emission layer, and a
red emission layer.
7. The OLED of claim 1, wherein the second electrode comprises at
least one of MgAg and AlAg.
8. The OLED of claim 1, wherein the transmittance controlled layer
comprises at least one selected from the group consisting of SiNx,
SiO.sub.2, SiON, MgF.sub.2, ZnS, ZnSe, TeO.sub.2, ZrO.sub.2, an
arylenediamine derivative, a triamine derivative,
4,4'-N,N'-dicarbazol-biphenyl (CBP), and an aluminum quinoline
(Alq3) complex.
9. A method of fabricating an organic light emitting display device
(OLED), comprising: providing a substrate; forming a first
electrode including a reflective layer over the substrate; forming
an organic layer including a light emission layer over the first
electrode, the light emission layer being configured to emit white
light; forming a second electrode over the organic layer; and
forming a transmittance controlled layer (TCL) having an optical
path length of about 260 .ANG. to about 1520 .ANG. on the second
electrode.
10. The method of claim 9, wherein the organic layer is formed by
one of a vacuum deposition method, an inkjet printing method, and a
laser induced thermal imaging method.
11. The method of claim 9, wherein the transmittance controlled
layer is formed by a vacuum deposition method or a lithography
method.
12. An organic light emitting display device (OLED), comprising: an
anode electrode comprising a reflective layer configured to be at
least partially reflective to visible light; a cathode electrode
opposing the anode electrode and being partially reflective to
visible light; an organic light emitting layer interposed between
the anode and cathode electrodes, the organic light emitting layer
being configured to emit white light; and an optical layer
contacting the cathode electrode interposed between the optical
layer and the organic light emitting layer, wherein the optical
layer is at least partially transparent to visible light and is
configured to reduce optical resonance caused by multiple
reflections of visible light between the anode and cathode
electrodes, wherein the device is configured to emit the white
light through the cathode electrode and the optical layer.
13. The OLED of claim 12, wherein the optical layer has an optical
path length (OPL) represented by Formula 1: OPL=t.times.n Formula 1
wherein t is the thickness of the optical layer, and n is the
refractive index of the optical layer, and wherein the OPL of the
optical layer is from about 260 .ANG. to about 1520 .ANG..
14. The OLED of claim 12, wherein the cathode electrode has a
transmittance of less than about 90% to visible light.
15. The OLED of claim 12, wherein the cathode electrode comprises
at least one selected from the group consisting of MgAg and
AlAg.
16. The OLED of claim 12, wherein the optical layer comprises at
least one selected from the group consisting of SiNx, SiO.sub.2,
SiON, MgF.sub.2, ZnS, ZnSe, TeO.sub.2, ZrO.sub.2, an arylenediamine
derivative, a triamine derivative, 4,4'-N,N'-dicarbazol-biphenyl
(CBP), and an aluminum quinoline (Alq3) complex.
17. The OLED of claim 12, further comprising a color filter layer
configured to filter the white light emitting from the organic
light emitting layer.
18. The OLED of claim 17, wherein the white light has at least two
emission peaks in the electroluminescence spectrum thereof, and
wherein the emission peaks have substantially more uniform peak
heights than those of white light emitting from the organic light
emitting layer in the absence of the optical layer.
19. The OLED of claim 12, wherein the organic light emitting layer
comprises at least two organic light emitting materials configured
to emit lights of different colors.
20. The OLED of claim 12, wherein the organic light emitting layer
comprises at least two sublayers stacked over each other, each of
the sublayers being configured to emit light of a different color.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Korean Patent
Application No. 10-2006-118378, filed on Nov. 28, 2006, the
disclosure of which is hereby incorporated herein by reference in
its entirety.
BACKGROUND
[0002] 1. Field
[0003] The present disclosure relates to an organic light emitting
display device (OLED) and a method of fabricating the same.
[0004] 2. Description of the Related Technology
[0005] An OLED typically includes a substrate, an anode disposed on
the substrate, an emission layer (EML) disposed on the anode, and a
cathode disposed on the emission layer. In such an OLED, holes and
electrons are injected into the emission layer when a voltage is
applied between the anode and the cathode. The holes and electrons
recombine with each other in the emission layer to generate
excitons. When these excitons transition from an excited state to a
ground state, light is emitted.
[0006] Full-color OLEDs may have emission layers, each emitting one
of red (R), green (G) and blue (B) colors. However, the R, G and B
emission layers in the OLEDs have different luminance efficiencies
(Cd/A). The difference in the luminance efficiency causes the
luminance of each emission layer to be different. The luminance is
generally proportional to a current value. Accordingly, if the same
current flows through emission layers of different colors, one
color may have a lower luminance whereas another color may have a
higher luminance. This makes it difficult to obtain proper color
balance or white balance.
[0007] For example, since the luminance efficiency of a G emission
layer is three to six times higher than those of R and B emission
layers, more current needs to be applied to the R and B emission
layers to achieve the white balance.
[0008] To solve this problem, a method has been proposed including
forming an emission layer that emits light of a single color, i.e.,
a white (W) color, and then forming a color filter layer for
extracting light corresponding to a predetermined color from the
emission layer, or alternatively a color conversion layer for
converting light from the emission layer to light of a
predetermined color.
[0009] FIG. 1 is a cross-sectional view of one example of a
top-emission OLED. Referring to FIG. 1, a substrate 100 is
provided. A first electrode 110 including a reflective layer is
formed on the substrate 100. A thin film transistor may be
interposed between the first electrode 110 and the substrate 100.
An organic layer 120 including an emission layer, which may have a
single layer or multiple sublayers, is formed on the first
electrode 110. In an arrangement in which a W emission layer and a
color filter are used to realize a full-color OLED, the organic
layer 120 may have a stacked structure of R, G, and B emission
layers. A second electrode 130 is formed of a transflective or
translucent material on the organic layer 120, thereby completing
the OLED. The transflective material may have a transmittance of
less than about 90%.
[0010] In the illustrated OLED, a resonance effect may occur
because the second electrode is formed of a transflective material.
Three peaks for R, G, and B light in the electroluminescence (EL)
spectrum thereof may not be uniform because of the resonance
effect, and thus the white light cannot be maintained. Also, light
of different wavelengths may be emitted depending on a viewing
angle due to the resonance effect. The resonance effect is
significantly affected by the thickness of the organic layer. Thus,
a wavelength band of light to be filtered varies depending on the
thickness distribution of the organic layer, causing color and
luminance to be adversely affected.
SUMMARY
[0011] One embodiment provides an organic light emitting display
device (OLED), comprising: a substrate; a first electrode formed
over the substrate, the first electrode comprising a reflective
layer, the reflective layer being substantially reflective to
visible light; an organic layer formed over the first electrode,
the organic layer comprising at least one light emission layer
configured to emit white light; a second electrode formed over the
organic layer; and a transmittance controlled layer (TCL) formed on
the second electrode, the transmittance controlled layer having an
optical path length of about 260 .ANG. to about 1520 .ANG., wherein
the optical path length extends in the direction of the thickness
of the transmittance controlled layer.
[0012] The reflective layer may comprise at least one selected from
the group consisting of aluminum, silver and an alloy thereof. The
at least one light emission layer may be a single layer. The at
least one light emission layer may comprise multiple layers. The
multiple layers may comprise an orange-red emission layer and a
blue emission layer. The multiple layers may comprise at least two
of a blue emission layer, a green emission layer, and a red
emission layer. The second electrode may comprise at least one of
MgAg and AlAg. The transmittance controlled layer may comprise at
least one selected from the group consisting of SiNx, SiO.sub.2,
SiON, MgF.sub.2, ZnS, ZnSe, TeO.sub.2, ZrO.sub.2, an arylenediamine
derivative, a triamine derivative, 4,4'-N,N'-dicarbazol-biphenyl
(CBP), and an aluminum quinoline (Alq3) complex.
[0013] Another embodiment provides a method of fabricating an
organic light emitting display device (OLED), comprising: providing
a substrate; forming a first electrode including a reflective layer
over the substrate; forming an organic layer including a light
emission layer over the first electrode, the light emission layer
being configured to emit white light; forming a second electrode
over the organic layer; and forming a transmittance controlled
layer (TCL) having an optical path length of about 260 .ANG. to
about 1520 .ANG. on the second electrode.
[0014] The organic layer may be formed by one of a vacuum
deposition method, an inkjet printing method, and a laser induced
thermal imaging method. The transmittance controlled layer may be
formed by a vacuum deposition method or a lithography method.
[0015] Yet another embodiment provides an organic light emitting
display device (OLED), comprising: an anode electrode comprising a
reflective layer configured to be at least partially reflective to
visible light; a cathode electrode opposing the anode electrode and
being partially reflective to visible light; an organic light
emitting layer interposed between the anode and cathode electrodes,
the organic light emitting layer being configured to emit white
light; and an optical layer contacting the cathode electrode
interposed between the optical layer and the organic light emitting
layer, wherein the optical layer is at least partially transparent
to visible light and is configured to reduce optical resonance
caused by multiple reflections of visible light between the anode
and cathode electrodes, wherein the device is configured to emit
the white light through the cathode electrode and the optical
layer.
[0016] The optical layer may have an optical path length (OPL)
represented by Formula 1:
OPL=t.times.n Formula 1
wherein t is the thickness of the optical layer, and n is the
refractive index of the optical layer, and wherein the OPL of the
optical layer is from about 260 .ANG. to about 1520 .ANG..
[0017] The cathode electrode may have a transmittance of less than
about 90% to visible light. The cathode electrode may comprise at
least one selected from the group consisting of MgAg and AlAg. The
optical layer may comprise at least one selected from the group
consisting of SiNx, SiO.sub.2, SiON, MgF.sub.2, ZnS, ZnSe,
TeO.sub.2, ZrO.sub.2, an arylenediamine derivative, a triamine
derivative, 4,4'-N,N'-dicarbazol-biphenyl (CBP), and an aluminum
quinoline (Alq3) complex. The OLED may further comprise a color
filter layer configured to filter the white light emitting from the
organic light emitting layer.
[0018] The white light may have at least two emission peaks in the
electroluminescence spectrum thereof, and the emission peaks may
have substantially more uniform peak heights than those of white
light emitting from the organic light emitting layer in the absence
of the optical layer. The organic light emitting layer may comprise
at least two organic light emitting materials configured to emit
lights of different colors. The organic light emitting layer may
comprise at least two sublayers stacked over each other, each of
the sublayers being configured to emit light of a different
color.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The above and other features of the instant disclosure will
be described in respect to certain exemplary embodiments thereof
with reference to the attached drawings in which:
[0020] FIG. 1 is a cross-sectional view of an example of a
top-emission OLED;
[0021] FIG. 2 is a cross-sectional view of an OLED according to one
embodiment;
[0022] FIG. 3 is a graph showing an EL spectrum of Exemplary
Embodiment 1;
[0023] FIG. 4 is a graph showing an EL spectrum of Comparative
example 1;
[0024] FIG. 5 is a graph showing an EL spectrum of Exemplary
Embodiment 2;
[0025] FIG. 6 is a graph showing an EL spectrum of Exemplary
Embodiment 3;
[0026] FIG. 7 is a graph showing transmissive spectrums of
Exemplary Embodiment 4, Exemplary Embodiment 5, and Exemplary
Embodiment 6; and
[0027] FIG. 8 is a graph showing transmissive spectrums of
Exemplary Embodiment 7, Exemplary Embodiment 8, and Exemplary
Embodiment 9.
DETAILED DESCRIPTION
[0028] The instant disclosure will now be described below with
reference to the accompanying drawings, in which exemplary
embodiments are shown.
[0029] FIG. 2 is a cross-sectional view of an OLED according to an
exemplary embodiment. Referring to FIG. 2, a substrate 200 is
provided. A first electrode 210 may be formed on the substrate 200.
The first electrode 210 may have a double-layered structure or a
triple-layered structure, including a reflective layer. When the
first electrode 210 has a double-layered structure, it may have a
stacked structure of a reflective layer formed of aluminum, silver
or an alloy thereof, and a transparent conductivity layer formed of
one of indium tin oxide (ITO), indium zinc oxide (IZO) and an
indium tin zinc oxide (ITZO). When the first electrode 210 has a
triple-layered structure, it may have a stacked structure of a
first metal layer formed of one of titanium, molybdenum, ITO or an
alloy thereof, a second metal layer formed of aluminum, silver, or
an alloy thereof, and a third metal layer formed of one of ITO,
IZO, and ITZO. In addition, a thin film transistor, a capacitor or
the like may be interposed between the substrate 200 and the first
electrode 210.
[0030] An organic layer 220 including a white (W) emission layer is
formed on the first electrode 210. In one embodiment, the white
emission layer may be a single layer. The white emission layer may
include emissive materials emitting different colors and dopants.
In some embodiments, the white emission layer may include a
carbazole polymer (e.g., polyvinylcarbazole (PVK)) and
polybutadiene (PBD), tetraphenyl butadiene (TPB), Coumarin6, DCM1,
Nile red at a suitable ratio. Emissive materials of two different
colors may be mixed together and another emissive material of a
different color may be added to obtain a W color emissive material.
For example, an R color emissive material and a G color emissive
material may be mixed together, and a B color emissive material may
be added to obtain the W color emissive material. The R color
emissive material may be polythiophene (PT) or its derivative which
is a polymeric material. The G color emissive material may be one
of aluminum quinoline complex (Alq3),
10-benzo[h]quinolinol-beryllium complex (BeBq2) and
tris(4-methyl-8-quinolinolato)aluminum (III) (Almq) (low molecular
materials), and poly(p-phenylenevinylene) (PPV) and its derivative
(polymeric materials). The B color emissive material may be one of
ZnPBO, Balq, 4,4-bis(2,2-diphenylvinyl)1,1-biphenyl (DPVBi), and
OXA-D (low molecular materials), and polyphenylene (PPP) and its
derivative (polymeric materials).
[0031] The white emission layer may include multiple layers. In one
embodiment, the white emission layer may include two layers, each
emitting light of different wavelengths. One of the layers may be
an emission layer emitting light of an orange-red (OR) region while
the other layer may be an emission layer emitting light of a B
region. The emission layer emitting light of the OR region may be a
phosphorescent emission layer, while the emission layer emitting
light of the B region may be a fluorescent emission layer. The
phosphorescent emission layer has a good emissive characteristic
compared to the fluorescent emission layer emitting light of the
same wavelength range. The fluorescent emission layer has a good
lifetime characteristic compared to the phosphorescent emission
layer. Therefore, the W emission layer, which has the
phosphorescent emission layer emitting light of OR region and the
fluorescent emission layer emitting light of B region, can have
good luminous efficiency and good lifetime characteristics. Also,
the double-layered W emission layer may include a polymeric
material and/or a low molecular material.
[0032] In yet another embodiment, the W emission layer may include
three layers, e.g., R, G and B emission layers stacked over one
another. The layers may be stacked in any order. The R emission
layer may include low molecular materials such as Alq3
(host)/DCJTB(4-(Dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolid-
yl-9-enyl)-4H-pyran; fluorescent dopant),
Alq3(host)/DCM(4-(dicyanomethylene)-2-methyl-6-[p-(dimethylamino)styryl]--
4H-pyran; fluorescent dopant), 4,4'-N,N'-dicarbazol-biphenyl (CBP)
(host)/PtOEP (phosphorescent organic metal complex), and polymeric
materials such as a PFO-based polymer and a PPV-based polymer. The
G emission layer may include low molecular materials such as Alq3,
Alq3(host)/C545t(dopant), CBP(host)/IrPPY(phosphorescent organic
complex), and polymeric materials such as a PFO-based polymer and a
PPV-based polymer. The G emission layer may also include low
molecular materials such as DPVBi, spiro-DPVBi, spiro-6P,
distylbenzene (DSB), distrylarylene (DSA), and polymeric materials
such as a PFO-based polymer and a PPV-based polymer.
[0033] The organic layer 220 may further include at least one of a
hole injection layer, a hole transport layer, an electron injection
layer, an electron transport layer, and a hole blocking layer.
[0034] The hole injection layer serves to facilitate injection of
holes into the organic emission layer of the OLED to increase the
lifetime of the OLED. The hole injection layer may be formed of an
arylamine compound, starburst type amine, and the like. In one
embodiment, it may be formed of
4,4,4-tris(3-metylphenylamino)triphenylamino (m-MTDATA),
1,3,5-tris[4-(3-metylphenylamino)phenyl]benzene (m-MTDATB), or
phthalocyanine copper (CuPc).
[0035] The hole transport layer may be formed of an arylene diamine
derivative, a starburst type compound, a biphenyldiamine derivative
having a spiro radical, a ladder type compound, and the like. In
one embodiment, it may be formed of
N,N-diphenyl-N,N-bis)4-metylphenyl)-1,1-biphenyl-4,4-diamine (TPD)
or a 4,4-bis[N-(1-napril)-N-phenylamino]biphenyl (NPB).
[0036] The hole blocking layer serves to prevent holes from moving
into the electron injection layer when the electron mobility is
higher than the hole mobility in the organic emission layer. The
hole blocking layer may be formed of
2-biphenyl-4-il-5-(4-t-butylphenyl)-1,3,4-oxydiazole (PBD),
spiro-PBD, or
3-(4-t-butylphenyl)-4-phenyl-5-(4-biphenyl)-1,2,4-triazole
(TAZ).
[0037] The electron transport layer may be formed of a metallic
compound which has good electric conductivity. The electron
transfer layer may be formed of 8-hydroquinoline aluminum salt
(Alq3). The electron transfer layer facilitates transporting
electrons supplied from the cathode electrode. The electron
injection layer may include at least one material selected from the
group consisting of a 1,3,4-oxydiazole derivative, 1,2,4-trizole
derivative, and LiF. The organic layer 220 may be formed by one of
a vacuum deposition method, an inkjet printing method, and a laser
induced thermal imaging method.
[0038] A second electrode 230 is formed on the organic layer 220.
The second electrode 230 may be formed of a transflective or
translucent material. The transflective material may have a
transmittance of less than about 90%. Examples of the transflective
material include, but are not limited to, MgAg and AlAg. A MgAg
layer may be formed by depositing Mg and Ag simultaneously. AlAg
may be formed by sequentially depositing Al and Ag to have a
stacked structure. Also, a transparent conductivity layer such as
ITO or IZO may be further formed on the second electrode 230.
[0039] A transmittance controlled layer 240 (TCL) is formed on the
second electrode 230. The TCL 240 is configured to control the
transmittance and reflectance of the second electrode 230 using
interference effect.
[0040] The TCL 240 serves to adjust the intensity of transmissive
spectrum per wavelength band. An OLED emitting W color needs to
have a characteristic that the transmittance in a visible
wavelength band (particularly, about 450 to about 650 nm) is almost
uniform throughout the display array thereof. However, a
possibility of having different R, G and B color intensities in the
light source spectrum thereof is high, and the TCL 240 functions to
adjust the intensities.
[0041] Here, the transmissive spectrum refers to an emission rate
depending on the wavelength when light emits from the organic layer
220 to the outside of the OLED. Further, the interference effect in
the context of this document refers to an effect that light
reflected at an interface between the TCL 240 and the outer air is
reflected again at a surface of the second electrode 230 before
emitting outside. The refractive index of the TLC 240 is a
controlling factor affecting the interference effect. The
refractive index, however, may vary depending on the thickness of
the TCL 240 and the wavelength of light.
[0042] Furthermore, the TCL 240 may have an Optical Path Length
(OPL) of about 260 to about 1520 .ANG.. When the TCL 240 has such
an OPL, an optimal emission can be obtained such that the
transmissive spectrum of the OLED emitting W color light becomes
substantially uniform over a wavelength band of about 450 nm to
about 650 nm.
[0043] In addition, when the transmittance for the optimal design
is set as reference transmittance and the transmittance is at least
a half of the reference transmittance in a visible wavelength band
of about 450 to about 650 nm, the optical path length of 260 to
1520 .ANG. of the TCL 240 is met. Here, the optical path length
refers to a value resulting from the thickness multiplied by the
refractive index of the TCL 240. The optical path length (OPL) may
be represented by Formula 1:
OPL=t.times.n Formula 1
[0044] In Formula 1, t is the thickness of the TCL 240, and n is
the refractive index of the TCL 240. The OPL is generally
proportional to the wavelength corresponding to the transmissive
spectrum. As described above, the refractive index of the TCL 240
may vary depending on the wavelength. The thickness of the TCL 240
may also vary depending on the refractive index of the material for
the TCL 240. Thus, the refractive index and the thickness are not
specifically limited as long as a product of the refractive index
and the thickness falls within the optical path length range of the
TCL 240 described above.
[0045] The TCL 240 may be formed of an at least partially
transparent material. The material may not have too high absorption
and reflectance properties or too low transmittance. In one
embodiment, the TCL 240 may include at least one of SiNx,
SiO.sub.2, SiON, MgF.sub.2, ZnS, ZnSe, TeO.sub.2, ZrO.sub.2, an
arylenediamine derivative, a triamine derivative,
4,4'-N,N'-dicarbazol-biphenyl (CBP), and an Alq3 complex. The TCL
240 may be formed by a vacuum deposition method or a lithography
method.
[0046] Hereinafter, the instant disclosure will be described in
detail with reference to exemplary embodiments, but it is not
limited to the exemplary embodiments.
Exemplary Embodiment 1
[0047] Silver having a thickness of 1000 .ANG. was formed on a
substrate, and ITO having a thickness of 70 .ANG. was formed on the
silver. IDE406 (available from IDEMITSU Kosan Co., Ltd., Tokyo,
Japan) having a thickness of 250 .ANG. was formed on the ITO as a
hole injection layer. IDE320 (available from IDEMITSU Co., Ltd.)
having a thickness of 150 .ANG. was formed on the hole injection
layer as a hole transport layer. Further, a B emission layer
containing BH215 available from IDEMITSU Co. as a host material and
BD052 available from IDEMITSU Co. as a dopant material in the
amount of 1 wt % was formed to a thickness of 80 .ANG. on the hole
transport layer. A G emission layer containing CBP available from
Universal Display Corporation (UDC; Ewing, N.J.), as a host
material and GD33 available from UDC Co. as a dopant material in
the amount of 7 wt % was formed to a thickness of 120 .ANG. on the
B emission layer. Also, an R emission layer containing CBP
available from UDC Co. as a host material and TER004 available from
COVION Co., Frankfurt, Germany, as a dopant material in the amount
of 12 wt % was formed to a thickness of 100 .ANG. on the G emission
layer. Balq having a thickness of 50 .ANG. and available from UDC
Co. was formed on the R emission layer as a hole blocking layer,
and Alq3 having a thickness of 100 .ANG. was formed on the hole
blocking layer as an electron transport layer. LiF having a
thickness of 5 .ANG. was formed on the electron transport layer as
an electron injection layer. Al having a thickness of 20 .ANG. and
Ag having a thickness of 70 .ANG. were formed on the electron
injection layer as a second electrode, and IDE320 available from
IDEMITSU Co. was formed to a thickness of 400 .ANG. on the Ag as a
TCL.
Exemplary Embodiment 2
[0048] Silver having a thickness of 1000 .ANG. was formed on a
substrate, and ITO having a thickness of 70 .ANG. was formed on the
silver. IDE406 (available from IDEMITSU Co.) having a thickness of
250 .ANG. was formed on the ITO as a hole injection layer. IDE320
(available from IDEMITSU Co.) having a thickness of 150 .ANG. was
formed on the hole injection layer as a hole transport layer.
Further, a B emission layer containing BH215 available from
IDEMITSU Co. as a host material and BD052 available from IDEMITSU
Co. as a dopant material in the amount of 1 wt % was formed to a
thickness of 80 .ANG. on the hole transport layer. A G emission
layer containing CBP available from UDC Co. as a host material and
GD33 available from UDC Co. as a dopant material in the amount of 7
wt % was formed to a thickness of 120 .ANG. on the B emission
layer. Also, an R emission layer containing CBP available from UDC
Co. as a host material and TER004 available from COVION Co. as a
dopant material in the amount of 12 wt % was formed to a thickness
of 100 .ANG. on the G emission layer. Balq having a thickness of 50
.ANG. and available from UDC Co. was formed on the R emission layer
as a hole blocking layer, and Alq3 having a thickness of 200 .ANG.
was formed on the hole blocking layer as an electron transport
layer. LiF having a thickness of 5 .ANG. was formed on the electron
transport layer as an electron injection layer. Al having a
thickness of 20 .ANG. and Ag having a thickness of 70 .ANG. were
sequentially formed on the electron injection layer as a second
electrode, and IDE320 having a thickness of 300 .ANG. and available
from IDEMITSU Co. was formed on the Ag as a TCL.
Exemplary Embodiment 3
[0049] Silver having a thickness of 1000 .ANG. was formed on a
substrate, and ITO having a thickness of 70 .ANG. was formed on the
silver. IDE406 having a thickness of 250 .ANG. and available from
IDEMITSU Co. was formed on the ITO as a hole injection layer.
IDE320 having a thickness of 150 .ANG. and available from IDEMITSU
Co. was formed on the hole injection layer as a hole transport
layer. Also, a B emission layer containing BH215 available from
IDEMITSU Co. as a host material and BD052 available from IDEMITSU
Co. as a dopant material in the amount of 1 wt % was formed to a
thickness of 80 .ANG. on the hole transport layer, and a G emission
layer containing CBP available from UDC Co. as a host material and
GD33 available from UDC Co. as a dopant material in the amount of 7
wt % was formed to a thickness of 120 .ANG. on the blue emission
layer. Further, an R emission layer containing CBP available from
UDC Co. as a host material and TER004 available from COVION Co. as
a dopant material in the amount of 12 wt % was formed to a
thickness of 100 .ANG. on the G emission layer. Balq having a
thickness of 50 .ANG. and available from UDC Co. was formed on the
R emission layer as a hole blocking layer, and Alq3 having a
thickness of 200 .ANG. was formed on the hole blocking layer as an
electron transport layer. LiF having a thickness of 5 .ANG. was
formed on the electron transport layer as an electron injection
layer, and Al having a thickness of 20 .ANG. and Ag having a
thickness of 70 .ANG. were sequentially formed on the electron
injection layer as a second electrode. IDE320 having a thickness of
500 .ANG. and available from IDEMITSU Co. was formed on the Ag as a
TCL.
Exemplary Embodiment 4
[0050] Silver having a thickness of 1000 .ANG. was formed on a
substrate. ITO having a thickness of 70 .ANG. was formed on the
silver. IDE406 having a thickness of 250 .ANG. and available from
IDEMITSU Co. was formed on the ITO as a hole injection layer.
IDE320 having a thickness of 150 .ANG. and available from IDEMITSU
Co. was formed on the hole injection layer as a hole transport
layer. Also, a B emission layer containing BH215 available from
IDEMITSU Co. as a host material and BD052 available from IDEMITSU
Co. as a dopant material in the amount of 1 wt % was formed to a
thickness of 80 .ANG. on the hole transport layer. A G emission
layer containing CBP available from UDC Co. as a host material and
GD33 available from UDC Co. as a dopant material in the amount of 7
wt % was formed to a thickness of 120 .ANG. on the B emission
layer. Also, an R emission layer containing CBP available from UDC
Co. as a host material and TER004 available from COVION Co. as a
dopant material in the amount of 12 wt % was formed to a thickness
of 100 .ANG. on the G emission layer. Balq having a thickness of 50
.ANG. and available from UDC Co. was formed on the R emission layer
as a hole blocking layer. Alq3 having a thickness of 100 .ANG. was
formed on the hole blocking layer as an electron transport layer.
LiF having a thickness of 5 .ANG. was formed on the electron
transport layer as an electron injection layer. Al having a
thickness of 20 .ANG. and Ag having a thickness of 70 .ANG. were
formed on the electron injection layer as a second electrode, and
MgF2 having a thickness of 550 .ANG. was formed on the Ag as a
TCL.
Exemplary Embodiment 5
[0051] Silver having a thickness of 1000 .ANG. was formed on a
substrate. ITO having a thickness of 70 .ANG. was formed on the
silver. IDE406 having a thickness of 250 .ANG. and available from
IDEMITSU Co. was formed on the ITO as a hole injection layer.
IDE320 having a thickness of 150 .ANG. and available from IDEMITSU
Co. was formed on the hole injection layer as a hole transport
layer. Further, a B emission layer containing BH215 available from
IDEMITSU Co. as a host material and BD052 available from IDEMITSU
Co. as a dopant material in the amount of 1 wt % was formed to a
thickness of 80 .ANG. on the hole transport layer. A G emission
layer containing CBP available from UDC Co. as a host material and
GD33 available from UDC Co. as a dopant material in the amount of 7
wt % was formed to a thickness of 120 .ANG. on the B emission
layer. Also, an R emission layer containing CBP available from UDC
Co. as a host material and TER004 available from COVION Co. as a
dopant material in the amount of 12 wt % was formed to a thickness
of 100 .ANG. on the G emission layer. Balq having a thickness of 50
.ANG. and available from UDC Co. was formed on the R emission layer
as a hole blocking layer. Alq3 having a thickness of 100 .ANG. was
formed on the hole blocking layer as an electron transport layer.
LiF having a thickness of 5 .ANG. was formed on the electron
transport layer as an electron injection layer. Al having a
thickness of 20 .ANG. and Ag having a thickness of 70 .ANG. were
formed on the electron injection layer as a second electrode, and
MgF2 having a thickness of 703 .ANG. was formed on the Ag as a
TCL.
Exemplary Embodiment 6
[0052] Silver having a thickness of 1000 .ANG. was formed on a
substrate. ITO having a thickness of 70 .ANG. was formed on the
silver. IDE406 having a thickness of 250 .ANG. and available from
IDEMITSU Co. was formed on the ITO as a hole injection layer.
IDE320 having a thickness of 150 .ANG. and available from IDEMITSU
Co. was formed on the hole injection layer as a hole transport
layer. Further, a B emission layer containing BH215 available from
IDEMITSU Co. as a host material and BD052 available from IDEMITSU
Co. as a dopant material in the amount of 1 wt % was formed to a
thickness of 80 .ANG. on the hole transport layer. A G emission
layer containing CBP available from UDC Co. as a host material and
GD33 available from UDC Co. as a dopant material in the amount of 7
wt % was formed to a thickness of 120 .ANG. on the B emission
layer. Also, an R emission layer containing CBP available from UDC
Co. as a host material and TER004 available from COVION Co. as a
dopant material in the amount of 12 wt % was formed to a thickness
of 100 .ANG. on the G emission layer. Balq having a thickness of 50
.ANG. and available from UDC Co. was formed on the R emission layer
as a hole blocking layer. Alq3 having a thickness of 100 .ANG. was
formed on the hole blocking layer as an electron transport layer.
LiF having a thickness of 5 .ANG. was formed on the electron
transport layer as an electron injection layer. Al having a
thickness of 20 .ANG. and Ag having a thickness of 70 .ANG. were
formed on the electron injection layer as a second electrode, and
MgF2 having a thickness of 1101 .ANG. was formed on the Ag as a
TCL.
Exemplary Embodiment 7
[0053] Silver having a thickness of 1000 .ANG. was formed on a
substrate. ITO having a thickness of 70 .ANG. was formed on the
silver. IDE406 having a thickness of 250 .ANG. and available from
IDEMITSU Co. was formed on the ITO as a hole injection layer.
IDE320 having a thickness of 150 .ANG. and available from IDEMITSU
Co. was formed on the hole injection layer as a hole transport
layer. Further, a B emission layer containing BH215 available from
IDEMITSU Co. as a host material and BD052 available from IDEMITSU
Co. as a dopant material in the amount of 1 wt % was formed to a
thickness of 80 .ANG. on the hole transport layer. A G emission
layer containing CBP available from UDC Co. as a host material and
GD33 available from UDC Co. as a dopant material in the amount of 7
wt % was formed to a thickness of 120 .ANG. on the B emission
layer. Also, an R emission layer containing CBP available from UDC
Co. as a host material and TER004 available from COVION Co. as a
dopant material in the amount of 12 wt % was formed to a thickness
of 100 .ANG. on the G emission layer. Balq having a thickness of 50
.ANG. and available from UDC Co. was formed on the R emission layer
as a hole blocking layer. Alq3 having a thickness of 100 .ANG. was
formed on the hole blocking layer as an electron transport layer.
LiF having a thickness of 5 .ANG. was formed on the electron
transport layer as an electron injection layer. Al having a
thickness of 20 .ANG. and Ag having a thickness of 70 .ANG. were
formed on the electron injection layer as a second electrode, and
ZnSe having a thickness of 250 .ANG. was formed on the Ag as a
TCL.
Exemplary Embodiment 8
[0054] Silver having a thickness of 1000 .ANG. was formed on a
substrate. ITO having a thickness of 70 .ANG. was formed on the
silver. IDE406 having a thickness of 250 .ANG. and available from
IDEMITSU Co. was formed on the ITO as a hole injection layer.
IDE320 having a thickness of 150 .ANG. and available from IDEMITSU
Co. was formed on the hole injection layer as a hole transport
layer. Further, a B emission layer containing BH215 available from
IDEMITSU Co. as a host material and BD052 available from IDEMITSU
Co. as a dopant material in the amount of 1 wt % was formed to a
thickness of 80 .ANG. on the hole transport layer. A G emission
layer containing CBP available from UDC Co. as a host material and
GD33 available from UDC Co. as a dopant material in the amount of 7
wt % was formed to a thickness of 120 .ANG. on the B emission
layer. Also, an R emission layer containing CBP available from UDC
Co. as a host material and TER004 available from COVION Co. as a
dopant material in the amount of 12 wt % was formed to a thickness
of 100 .ANG. on the G emission layer. Balq having a thickness of 50
.ANG. and available from UDC Co. was formed on the R emission layer
as a hole blocking layer. Alq3 having a thickness of 100 .ANG. was
formed on the hole blocking layer as an electron transport layer.
LiF having a thickness of 5 .ANG. was formed on the electron
transport layer as an electron injection layer. Al having a
thickness of 20 .ANG. and Ag having a thickness of 70 .ANG. were
formed on the electron injection layer as a second electrode, and
ZnSe having a thickness of 250 .ANG. was formed on the Ag as a
TCL.
Exemplary Embodiment 9
[0055] Silver having a thickness of 1000 .ANG. was formed on a
substrate. ITO having a thickness of 70 .ANG. was formed on the
silver. IDE406 having a thickness of 250 .ANG. and available from
IDEMITSU Co. was formed on the ITO as a hole injection layer.
IDE320 having a thickness of 150 .ANG. and available from IDEMITSU
Co. was formed on the hole injection layer as a hole transport
layer. Further, a B emission layer containing BH215 available from
IDEMITSU Co. as a host material and BD052 available from IDEMITSU
Co. as a dopant material in the amount of 1 wt % was formed to a
thickness of 80 .ANG. on the hole transport layer. A G emission
layer containing CBP available from UDC Co. as a host material and
GD33 available from UDC Co. as a dopant material in the amount of 7
wt % was formed to a thickness of 120 .ANG. on the B emission
layer. Also, an R emission layer containing CBP available from UDC
Co. as a host material and TER004 available from COVION Co. as a
dopant material in the amount of 12 wt % was formed to a thickness
of 100 .ANG. on the G emission layer. Balq having a thickness of 50
.ANG. and available from UDC Co. was formed on the R emission layer
as a hole blocking layer. Alq3 having a thickness of 100 .ANG. was
formed on the hole blocking layer as an electron transport layer.
LiF having a thickness of 5 .ANG. was formed on the electron
transport layer as an electron injection layer. Al having a
thickness of 20 .ANG. and Ag having a thickness of 70 .ANG. were
formed on the electron injection layer as a second electrode, and
ZnSe having a thickness of 400 .ANG. was formed on the Ag as a
TCL.
COMPARATIVE EXAMPLE 1
[0056] Silver having a thickness of 1000 .ANG. was formed on a
substrate. ITO having a thickness of 70 .ANG. was formed on the
silver. IDE406 having a thickness of 250 .ANG. and available from
IDEMITSU Co. was formed on the ITO as a hole injection layer.
IDE320 having a thickness of 150 .ANG. and available from IDEMITSU
Co. was formed on the hole injection layer as a hole transport
layer. A blue emission layer containing BH215 available from
IDEMITSU Co. as a host material and BD052 available from IDEMITSU
Co. as a dopant material in the amount of 1 wt % was formed to a
thickness of 80 .ANG. on the hole transport layer. A G emission
layer containing CBP available from UDC Co. as a host material and
GD33 available from UDC Co. as a dopant material in the amount of 7
wt % was formed to a thickness of 120 .ANG. on the B emission
layer. Also, an R emission layer containing CBP available from UDC
Co. as a host material and TER004 available from COVION Co. as a
dopant material in the amount of 12 wt % was formed to a thickness
of 100 .ANG. on the G emission layer. Balq having a thickness of 50
.ANG. and available from UDC Co. was formed on the R emission layer
as a hole blocking layer. Alq3 having a thickness of 200 .ANG. was
formed on the hole blocking layer as an electron transport layer.
LiF having a thickness of 5 .ANG. was formed on the electron
transport layer as an electron injection layer. Al having a
thickness of 20 .ANG. and Ag having a thickness of 70 .ANG. were
sequentially formed on the electron injection layer as a second
electrode.
[0057] FIG. 3 is a graph showing an electroluminescence (EL)
spectrum of Exemplary Embodiment 1, and FIG. 4 is a graph showing
an EL spectrum of Comparative example 1. The x axis of each of the
graphs denotes a wavelength (unit: nm) while the y axis of each of
the graphs denotes an intensity (a.u.: arbitrary unit).
[0058] Referring to FIG. 3, the B peak has a maximum peak in a
wavelength region of 424 to 468 nm and its intensity is
approximately 4.5. The G peak has a maximum peak in a wavelength
region of 512 to 556 nm and its intensity is approximately 0.8. The
R peak has a maximum peak in a wavelength region of 644 nm and its
intensity is approximately 1. Here, the refractive index of the TCL
of Exemplary Embodiment 1 is 1.8 in the visible light wavelength
band, and the optical path length of the TCL of Exemplary
Embodiment 1 is 780 .ANG..
[0059] Referring to FIG. 4, the B peak has a maximum peak in a
wavelength region of 468 nm and its intensity is approximately 0.2.
The G peak has a maximum peak in a wavelength region of 512 to 556
nm and its intensity is approximately 0.5. The R peak has a maximum
peak in a wavelength region of 644 nm and its intensity is
approximately 1. It can be seen that the B, G, and R peaks of
Exemplary Embodiment 1 having the TCL are more uniform than those
of Comparative example 1 having no TCL.
[0060] FIG. 5 is a graph showing an EL spectrum of Exemplary
Embodiment 2. The x axis of the graph denotes a wavelength (unit:
nm), and the y axis of the graph denotes an intensity (a.u.:
arbitrary unit).
[0061] Referring to FIG. 5, the B peak has a maximum peak near a
wavelength region of 468 nm and its intensity is approximately 0.4.
The G peak has a maximum peak in a wavelength region of 512 to 556
nm and its intensity is approximately 0.7. The R peak has a maximum
peak in a wavelength region of 644 to 688 nm and its intensity is
approximately 1. Also, the refractive index of the TCL of Exemplary
Embodiment 2 is 1.8 in the visible light wavelength band, and the
optical path length of the TCL of Exemplary Embodiment 2 is 540
.ANG..
[0062] FIG. 6 is a graph showing an EL spectrum of Exemplary
Embodiment 3. The x axis of the graph denotes a wavelength (unit:
nm), and the y axis of the graph denotes an intensity (a.u.:
arbitrary unit). Referring to FIG. 6, the B peak has a little
shoulder peak in a wavelength region of 424 to 468 nm and its
intensity is approximately 0.3. The G peak has a maximum peak in a
wavelength region of 512 to 556 nm and its intensity is
approximately 1. The R peak has a maximum peak in a wavelength
region of 644 to 688 nm and its intensity is approximately 0.7.
Here, the refractive index of the TCL of Exemplary Embodiment 3 is
1.8 in the visible light wavelength band, and the optical path
length of the TCL of Exemplary Embodiment 3 is 900 .ANG..
[0063] As such, referring to FIGS. 3 to 5, it can be seen that the
intensity of the B peak decreases and the intensity of the G peak
increases as the thickness of the TCL increases. Also, it can be
seen that the R peak decreases when the thickness of the TCL is not
greater than a predetermined level.
[0064] FIG. 7 is a graph showing transmissive spectrums of
Exemplary Embodiment 4, Exemplary Embodiment 5, and Exemplary
Embodiment 6. The x axis of the graph denotes a wavelength (unit:
nm), and the y axis of the graph denotes a transmittance.
[0065] Referring to FIG. 7, the transmittance in a wavelength
region of 450 to 650 nm has a smooth curve between 0.35 and 0.70 in
Exemplary Embodiment 4. The transmittance in a wavelength region of
450 to 650 nm has a smooth curve between 0.35 and 0.70 in Exemplary
Embodiment 5. Also, the transmittance of Exemplary Embodiment 6 is
approximately 0.9 in a wavelength region of 500 to 550 nm and is
0.35 to 0.9 in a wavelength region of 450 to 650 nm.
[0066] MgF2 used for the TCL has a refractive index of 1.38 in
Exemplary Embodiment 4, Exemplary Embodiment 5, and Exemplary
Embodiment 6. The optical path length of the TCL of the instant
disclosure is 260 to 1520 .ANG.. The optical path lengths of the
TCL of Exemplary Embodiment 4, Exemplary Embodiment 5, Exemplary
Embodiment 6 are 760 .ANG., 970 .ANG., and 1520 .ANG.,
respectively. Accordingly, it can be seen that the optical path
length of the embodiments is in a range of the optical path length
of the TCL described above.
[0067] Also, it can be seen that transmissive spectrums become
substantially flat near approximately 0.6 of the transmittances of
Exemplary Embodiment 4 and Exemplary Embodiment 5. This
transmittance is referred to as a reference transmittance. It can
be seen that transmissive spectrums of Exemplary Embodiment 4,
Exemplary Embodiment 5, and Exemplary Embodiment 6 are positioned
at a transmittance not less than 0.3 which is half the reference
transmittance.
[0068] FIG. 8 is a graph showing transmissive spectrums of
Exemplary Embodiment 7, Exemplary Embodiment 8, and Exemplary
Embodiment 9. The x axis of the graph denotes a wavelength (unit:
nm), and the y axis of the graph denotes a transmittance.
[0069] Referring to FIG. 8, the transmittance in a wavelength
region of 450 to 650 nm has a constant value of 0.4 to 0.6 in
Exemplary Embodiment 7. The transmittance in a wavelength region of
550 to 600 nm has a maximum peak in Exemplary Embodiment 8, and its
transmittance is approximately 0.9. Also, the transmittance of
Exemplary Embodiment 8 is approximately 0.27 to 0.9 in a wavelength
region of 450 to 650 nm.
[0070] ZnSe used for the TCL of Exemplary Embodiment 7, Exemplary
Embodiment 8, and Exemplary Embodiment 9 has a refractive index of
2.6, so that the optical path lengths of Exemplary Embodiment 7,
Exemplary Embodiment 8, and Exemplary Embodiment 9 are 260 .ANG.,
650 .ANG., and 1040 .ANG., respectively.
[0071] Also, the transmissive spectrum of Exemplary Embodiment 7
becomes substantially flat when the transmittance is approximately
0.5, which is referred to as a reference transmittance. The
transmissive spectrums of Exemplary Embodiment 8 and Exemplary
Embodiment 9 are positioned at a transmittance not less than 0.25
which is half the reference transmittance, which is suitable for
the reference of the TCL of the present invention.
[0072] Table 1 shows color coordinates of Exemplary Embodiment 1,
Exemplary Embodiment 2, Exemplary Embodiment 3, and Comparative
example 1.
TABLE-US-00001 TABLE 1 X color coordinate Y color coordinate
Exemplary Embodiment 1 0.364 0.339 Exemplary Embodiment 2 0.382
0.376 Exemplary Embodiment 3 0.333 0.412 Comparative example 1
0.443 0.400
[0073] Referring to Table 1, the color coordinates of Exemplary
Embodiment 1 is the best, and the color coordinates are better in
the order of Exemplary Embodiment 2, Exemplary Embodiment 3, and
Comparative example 1. Here, the color coordinates of the OLED
including the W emission layer are better when it is closer to
(0.31, 0.31). The TCL disposed on the second electrode can minimize
the resonance effect while enhancing luminance of the OLED.
[0074] Although the instant disclosure has been described with
reference to certain exemplary embodiments thereof, it will be
understood by those skilled in the art that a variety of
modifications and variations may be made to the embodiments without
departing from the spirit or scope of the instant disclosure
defined in the appended claims, and their equivalents.
* * * * *