U.S. patent application number 16/593060 was filed with the patent office on 2020-03-05 for display panel capable of preventing a defect in light emission of an organic light emitting element.
The applicant listed for this patent is Samsung Display Co., Ltd.. Invention is credited to Junkyung CHO, Byeongmin JANG, Woosik JEON, Jungyeon KIM, Sangyeol KIM, Ilseok PARK.
Application Number | 20200075884 16/593060 |
Document ID | / |
Family ID | 59350732 |
Filed Date | 2020-03-05 |
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United States Patent
Application |
20200075884 |
Kind Code |
A1 |
PARK; Ilseok ; et
al. |
March 5, 2020 |
DISPLAY PANEL CAPABLE OF PREVENTING A DEFECT IN LIGHT EMISSION OF
AN ORGANIC LIGHT EMITTING ELEMENT
Abstract
A display panel includes an auxiliary electrode on a base
substrate, a first electrode spaced from the auxiliary electrode, a
first light emitting unit on the auxiliary electrode and the first
electrode, an conductive thin film layer on the first light
emitting unit, a second light emitting unit on the conductive thin
film layer, a first contact hole through the conductive thin film
layer to expose the auxiliary electrode, a insulating layer in the
first contact hole, and a second electrode including a first
electrode part and a second electrode part, the first electrode
part being on the insulating layer in the first contact hole, and
the second electrode part overlapping the first electrode and being
on the second light emitting unit, in which the insulating layer is
between the first electrode part and the conductive thin film
layer.
Inventors: |
PARK; Ilseok; (Yongin-si,
KR) ; KIM; Sangyeol; (Yongin-si, KR) ; KIM;
Jungyeon; (Yongin-si, KR) ; JANG; Byeongmin;
(Yongin-si, KR) ; JEON; Woosik; (Yongin-si,
KR) ; CHO; Junkyung; (Yongin-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Display Co., Ltd. |
Yongin-si |
|
KR |
|
|
Family ID: |
59350732 |
Appl. No.: |
16/593060 |
Filed: |
October 4, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16020572 |
Jun 27, 2018 |
10439161 |
|
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16593060 |
|
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|
15646362 |
Jul 11, 2017 |
10020461 |
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16020572 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 27/3209 20130101;
H01L 27/3246 20130101; H01L 51/0096 20130101; H01L 51/56 20130101;
H01L 51/5206 20130101; H01L 51/5044 20130101; H01L 51/5228
20130101; H01L 2251/5392 20130101; H01L 2251/558 20130101; H01L
2251/301 20130101 |
International
Class: |
H01L 51/52 20060101
H01L051/52; H01L 51/00 20060101 H01L051/00; H01L 51/50 20060101
H01L051/50; H01L 27/32 20060101 H01L027/32; H01L 51/56 20060101
H01L051/56 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2016 |
KR |
10-2016-0090947 |
Claims
1. A display panel comprising: a base substrate including: a
display area including a first area and a second area; and a
non-display area adjacent to the display area; an auxiliary
electrode on the first area of the base substrate; a first
electrode on the second area of the base substrate; a first light
emitting unit on the auxiliary electrode and the first electrode; a
conductive thin film layer on the first light emitting unit; a
second light emitting unit on the conductive thin film layer; an
insulating layer on the second light emitting unit; and a second
electrode on the insulating layer, wherein the insulating layer
includes a first part covering a first contact hole that penetrates
the first light emitting unit, the conductive thin film layer, and
the second light emitting unit, which overlap with the first area,
to expose a portion of the auxiliary electrode, and wherein a
portion of the first part insulates the second electrode from the
conductive thin film layer.
2. The display panel of claim 1, wherein the portion of the first
part is in contact with an exposing surface of the conductive thin
film layer, which defines a portion of the first contact hole.
3. The display panel of claim 1, wherein another portion of the
first part is in contact with the auxiliary electrode.
4. The display panel of claim 1, wherein the insulating layer
further includes: a second part overlapping with the first
electrode; and a third part between the first part and the second
part.
5. The display panel of claim 4, further comprising a pixel
definition layer between the first electrode and the auxiliary
electrode, wherein at least a portion of the third part overlaps
with the pixel definition layer.
6. The display panel of claim 1, wherein the insulating layer is
spaced apart from the first electrode.
7. The display panel of claim 1, wherein the first light emitting
unit generates first light, and the second light emitting unit
generates light having a color different from a color of the first
light.
8. The display panel of claim 1, wherein a resistance of the
insulating layer is greater than a resistance of the conductive
thin film layer.
9. The display panel of claim 1, wherein a thickness of the
insulating layer is 10 nm or less.
10. The display panel of claim 1, wherein the insulating layer
includes at least one of LiF and LiQ.
11. A display panel comprising: a base substrate including: a
display area including a first area and a second area; and a
non-display area adjacent to the display area; an auxiliary
electrode on the first area of the base substrate; a first
electrode on the second area of the base substrate; a first light
emitting unit on the auxiliary electrode and the first electrode; a
conductive thin film layer on the first light emitting unit; a
second light emitting unit on the conductive thin film layer; an
insulating layer on the second light emitting unit; and a second
electrode on the insulating layer, wherein the insulating layer
includes a first part covering a first contact hole that penetrates
the first light emitting unit, the conductive thin film layer, and
the second light emitting unit, which overlap with the first area,
and is defined by exposed side surfaces, wherein the first contact
hole exposes a portion of the auxiliary electrode, and wherein a
portion of the first part is in contact with a side surface of the
second electrode, which defines a portion of the first contact
hole.
12. The display panel of claim 11, wherein the portion of the first
part is in contact with an exposing surface of the conductive thin
film layer, which defines a portion of the first contact hole.
13. The display panel of claim 11, wherein another portion of the
first part is in contact with the auxiliary electrode.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. patent
application Ser. No. 16/020,572, filed on Jun. 27, 2018, which is a
Divisional application of U.S. patent application Ser. No.
15/646,362, filed on Jul. 11, 2017, now issued as U.S. Pat. No.
10,020,461, which claims priority to and the benefit of Korean
Patent Application No. 10-2016-0090947, filed on Jul. 18, 2016,
each of which is hereby incorporated by reference for all purposes
as if fully set forth herein.
BACKGROUND
Field
[0002] The present disclosure relates to a display panel and a
method of manufacturing the same. More particularly, the present
disclosure relates to a display panel capable of preventing a
defect in light emission of an organic light emitting element from
occurring due to a lateral leakage current, a method of
manufacturing the display panel, and a display device having the
display panel.
Discussion of the Background
[0003] An organic light emitting device is a self-emissive device
and has advantages of a wide viewing angle and a superior contrast
ratio. In addition, the organic light emitting device has a fast
response speed, a high brightness, and a low driving voltage. In
general, the organic light emitting device includes an anode, a
hole transport layer, a light emitting layer, an electron transport
layer, and a cathode. The hole transport layer, the light emitting
layer, the electron transport layer, and the cathode are
sequentially stacked on the anode. The hole transport layer, the
light emitting layer, and the electron transport layer are organic
thin layers, each including an organic compound.
[0004] When different voltages are respectively applied to the
anode and the cathode of the organic light emitting device, holes
injected from the anode move to the light emitting layer through
the hole transport layer, and electrons injected from the cathode
move to the light emitting layer through the electron transport
layer. The holes are recombined with the electrons in the light
emitting layer to generate excitons, and the organic light emitting
device emits light by the excitons that return to a ground state
from an excited state.
SUMMARY
[0005] Embodiments provide a display panel including a base
substrate, an auxiliary electrode disposed on the base substrate, a
first electrode spaced apart from the auxiliary electrode when
viewed in a plan view, a first light emitting unit disposed on the
auxiliary electrode and the first electrode, an conductive thin
film layer disposed on the first light emitting unit, a second
light emitting unit disposed on the conductive thin film layer, a
insulating layer including a first part disposed in a first contact
hole defined through at least the first light emitting unit, the
conductive thin film layer, and the second light emitting unit to
expose the auxiliary electrode, and a second electrode including a
first electrode part and a second electrode part, the first
electrode part being disposed on the first part and including at
least a portion disposed in the first contact hole and the second
electrode part extending from the first electrode part, overlapped
with the first electrode when viewed in a plan view, and disposed
on the second light emitting unit. A portion of the first part is
disposed between the first electrode part and the conductive thin
film layer to insulate the first electrode part from the conductive
thin film layer.
[0006] The other portion of the first part is disposed between the
first electrode part and the auxiliary electrode.
[0007] The other portion of the first part makes contact with the
auxiliary electrode.
[0008] The portion of the first part makes contact with an exposing
surface of the conductive thin film layer exposed through the first
contact hole.
[0009] A second contact hole is defined in the other portion of the
first part to expose at least a portion of an upper surface of the
auxiliary electrode, and a portion of the first electrode part is
disposed in the second contact hole defined in the insulating layer
to make contact with the auxiliary electrode.
[0010] The insulating layer further includes a second part
extending from the first part and disposed between the second light
emitting unit and the second electrode.
[0011] The display panel further includes a pixel definition layer
disposed between the auxiliary electrode and the first electrode
when viewed in a plan view, and the insulating layer further
includes a third part disposed on the pixel definition layer to
connect the first and second parts.
[0012] The second part is overlapped with the first electrode when
viewed in a plan view.
[0013] The insulating layer is spaced apart from the first
electrode when viewed in a plan view.
[0014] The first light emitting unit generates a first light, and
the second light emitting unit generates a light having a color
different from a color of the first light.
[0015] The insulating layer has a resistance greater than a
resistance of the conductive thin film layer.
[0016] The insulating layer has a thickness from about 1 nm to
about 10 nm.
[0017] The insulating layer includes at least one of LiF and
LiQ.
[0018] Embodiments also provide a method of manufacturing a display
panel, including forming an auxiliary electrode in a first area
defined in a base substrate, forming a first electrode in a second
area defined in the base substrate and spaced apart from the first
area when viewed in a plan view, forming a first light emitting
unit on the first electrode, forming an conductive thin film layer
on the first light emitting unit, forming a second light emitting
unit on the conductive thin film layer, removing at least a portion
of the first light emitting unit, the conductive thin film layer,
and the second light emitting unit to form a first contact hole
through which an upper surface of the auxiliary electrode is
exposed, forming a insulating layer on an exposing surface of the
conductive thin film layer, which is exposed through the first
contact hole, and forming a second electrode on the insulating
layer.
[0019] The method further includes removing a portion of the
insulating layer to form a second contact hole, through which at
least a portion of the upper surface of the auxiliary electrode is
exposed, through the insulating layer.
[0020] The forming the second contact hole is performed after the
forming the insulating layer and before the forming the second
electrode.
[0021] The first light emitting unit, the conductive thin film
layer, and the second light emitting unit are removed using a laser
drilling method.
[0022] Embodiments also provide a display device including a
display panel and a controller controlling the display panel. The
display panel includes a base substrate, an auxiliary electrode
disposed on the base substrate, a first electrode spaced apart from
the auxiliary electrode when viewed in a plan view, a first light
emitting unit disposed on the auxiliary electrode and the first
electrode, an conductive thin film layer disposed on the first
light emitting unit, a second light emitting unit disposed on the
conductive thin film layer, a insulating layer including a first
part disposed in a first contact hole defined through at least the
first light emitting unit, the conductive thin film layer, and the
second light emitting unit to expose the auxiliary electrode, and a
second electrode including a first electrode part disposed in the
first contact hole and disposed on the first par and a second
electrode part extending from the first electrode part, overlapped
with the first electrode when viewed in a plan view, and disposed
on the second light emitting unit. A portion of the first part is
disposed between the first electrode part and the conductive thin
film layer to insulate the first electrode part from the conductive
thin film layer.
[0023] The other portion of the first part is disposed between the
first electrode part and the auxiliary electrode.
[0024] The other portion of the first part makes contact with the
auxiliary electrode, and the portion of the first part makes
contact with an exposing surface of the conductive thin film layer
exposed through the first contact hole.
[0025] Additional aspects will be set forth in the detailed
description which follows, and, in part, will be apparent from the
disclosure, or may be learned by practice of the inventive
concept.
[0026] The foregoing general description and the following detailed
description are exemplary and explanatory and are intended to
provide further explanation of the claimed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The accompanying drawings, which are included to provide a
further understanding of the inventive concept, and are
incorporated in and constitute a part of this specification,
illustrate exemplary embodiments of the inventive concept, and,
together with the description, serve to explain principles of the
inventive concept.
[0028] FIG. 1 illustrates a plan view of a display device according
to an exemplary embodiment of the present disclosure;
[0029] FIG. 2 illustrates a plan view of a display panel according
to an exemplary embodiment of the present disclosure;
[0030] FIG. 3A illustrates a cross-sectional view along line I-I'
in FIG. 2;
[0031] FIG. 3B illustrates an enlarged cross-sectional view of a
first contact hole shown in FIG. 3A;
[0032] FIG. 3C illustrates an enlarged cross-sectional view of the
first contact hole shown in FIG. 3A;
[0033] FIG. 3D illustrates a cross-sectional view of a display
panel according to an exemplary embodiment of the present
disclosure;
[0034] FIG. 4 illustrates a plan view of a display panel according
to an exemplary embodiment of the present disclosure;
[0035] FIG. 5 illustrates a cross-sectional view along line II-If
in FIG. 2;
[0036] FIG. 6 illustrates a cross-sectional view of a display panel
according to an exemplary embodiment of the present disclosure;
[0037] FIG. 7 illustrates a schematic cross-sectional view of an
organic light emitting element according to an exemplary embodiment
of the present disclosure;
[0038] FIGS. 8A, 8B, 8C, 8D, 8E, and 8F illustrate cross-sectional
views of stages in a method of manufacturing a display panel
according to an exemplary embodiment; and
[0039] FIGS. 9A, 9B, and 9C illustrate cross-sectional views of
stages in a method of manufacturing a display panel according to an
exemplary embodiment.
DETAILED DESCRIPTION
[0040] In the following description, for the purposes of
explanation, numerous specific details are set forth in order to
provide a thorough understanding of various exemplary embodiments.
It is apparent, however, that various exemplary embodiments may be
practiced without these specific details or with one or more
equivalent arrangements. In other instances, well-known structures
and devices are shown in block diagram form in order to avoid
unnecessarily obscuring various exemplary embodiments.
[0041] In the accompanying figures, the size and relative sizes of
layers, films, panels, regions, etc., may be exaggerated for
clarity and descriptive purposes. Also, like reference numerals
denote like elements.
[0042] When an element or layer is referred to as being "on,"
"connected to," or "coupled to" another element or layer, it may be
directly on, connected to, or coupled to the other element or layer
or intervening elements or layers may be present. When, however, an
element or layer is referred to as being "directly on," "directly
connected to," or "directly coupled to" another element or layer,
there are no intervening elements or layers present. For the
purposes of this disclosure, "at least one of X, Y, and Z" and "at
least one selected from the group consisting of X, Y, and Z" may be
construed as X only, Y only, Z only, or any combination of two or
more of X, Y, and Z, such as, for instance, XYZ, XYY, YZ, and ZZ.
Like numbers refer to like elements throughout. As used herein, the
term "and/or" includes any and all combinations of one or more of
the associated listed items.
[0043] Although the terms first, second, etc. may be used herein to
describe various elements, components, regions, layers, and/or
sections, these elements, components, regions, layers, and/or
sections should not be limited by these terms. These terms are used
to distinguish one element, component, region, layer, and/or
section from another element, component, region, layer, and/or
section. Thus, a first element, component, region, layer, and/or
section discussed below could be termed a second element,
component, region, layer, and/or section without departing from the
teachings of the present disclosure.
[0044] Spatially relative terms, such as "beneath," "below,"
"lower," "above," "upper," and the like, may be used herein for
descriptive purposes, and, thereby, to describe one element or
feature's relationship to another element(s) or feature(s) as
illustrated in the drawings. Spatially relative terms are intended
to encompass different orientations of an apparatus in use,
operation, and/or manufacture in addition to the orientation
depicted in the drawings. For example, if the apparatus in the
drawings is turned over, elements described as "below" or "beneath"
other elements or features would then be oriented "above" the other
elements or features. Thus, the exemplary term "below" can
encompass both an orientation of above and below. Furthermore, the
apparatus may be otherwise oriented (e.g., rotated 90 degrees or at
other orientations), and, as such, the spatially relative
descriptors used herein interpreted accordingly.
[0045] The terminology used herein is for the purpose of describing
particular embodiments and is not intended to be limiting. As used
herein, the singular forms, "a," "an," and "the" are intended to
include the plural forms as well, unless the context clearly
indicates otherwise. Moreover, the terms "comprises," "comprising,"
"includes," and/or "including," when used in this specification,
specify the presence of stated features, integers, steps,
operations, elements, components, and/or groups thereof, but do not
preclude the presence or addition of one or more other features,
integers, steps, operations, elements, components, and/or groups
thereof.
[0046] Various exemplary embodiments are described herein with
reference to sectional illustrations that are schematic
illustrations of idealized exemplary embodiments and/or
intermediate structures. As such, variations from the shapes of the
illustrations as a result, for example, of manufacturing techniques
and/or tolerances, are to be expected. Thus, exemplary embodiments
disclosed herein should not be construed as limited to the
particular illustrated shapes of regions, but are to include
deviations in shapes that result from, for instance, manufacturing.
The regions illustrated in the drawings are schematic in nature and
their shapes are not intended to illustrate the actual shape of a
region of a device and are not intended to be limiting.
[0047] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
disclosure is a part. Terms, such as those defined in commonly used
dictionaries, should be interpreted as having a meaning that is
consistent with their meaning in the context of the relevant art
and will not be interpreted in an idealized or overly formal sense,
unless expressly so defined herein.
[0048] FIG. 1 is a plan view showing a display device DD according
to an exemplary embodiment of the present disclosure.
[0049] Referring to FIG. 1, the display device DD may include a
display panel DP, a flexible printed circuit board FPC, and a
printed circuit board PCB. The display panel DP displays an image
through a display area DA. The display area DA is operated by a
control signal and image data provided from the printed circuit
board PCB.
[0050] The display panel DP includes gate lines GL1 to GLn, data
lines DL1 to DLm, and sub-pixels SPX, which are arranged in the
display area DA. The gate lines GL1 to GLn extend in a first
direction DR1 and are arranged, e.g., spaced apart, in a second
direction DR2. The data lines DL1 to DLm are insulated from the
gate lines GL1 to GLn while crossing the gate lines. For instance,
the data lines DL1 to DLm extend in the second direction DR2 and
are arranged, e.g., spaced apart, in the first direction DR1. In
the following descriptions, a direction substantially parallel to
the first and second directions DR1 and DR2 may be referred to as a
"horizontal direction".
[0051] The display panel DP includes a non-display area NDA
surrounding the display area DA when viewed in a plan view. The
sub-pixels SPX are not arranged in the non-display area NDA, and
the image is not displayed through the non-display area NDA. The
non-display area NDA may be referred to as a "bezel" of the display
device DD.
[0052] Each of the sub-pixels SPX is connected to a corresponding
gate line of the gate lines GL1 to GLn and a corresponding data
line of the data lines DL1 to DLm. The sub-pixels SPX may be
arranged in a matrix form along the first and second directions DR1
and DR2. Each sub-pixel SPX displays one of three primary colors of
red, green, and blue colors. The colors displayed by the sub-pixels
SPX are not be limited to red, green, and blue colors, and the
sub-pixels SPX may display a second primary color of white, yellow,
cyan, and magenta colors in addition to the red, green, and blue
colors.
[0053] The sub-pixels SPX may form the pixel PX. As an example,
four sub-pixels SPX may form one pixel PX, but the number of the
sub-pixels SPX required to form one pixel PX is not be limited to
four. That is, one pixel PX may include two, three, five, or more
sub-pixels SPX.
[0054] The pixel PX serves as an element to display a unit image,
and a resolution of the display panel DP is determined by the
number of the pixels PX included in the display panel DP. FIG. 1
shows only one pixel PX, and the other pixels may have the same
configurations as the one pixel PX. In the present exemplary
embodiment, the display panel DP may be, but not limited to, an
organic light emitting display panel, and each sub-pixel SPX may
include an organic light emitting element.
[0055] The display panel DP may have, for example, a plate-like
shape with a pair of short sides and a pair of long sides, which
are respectively parallel to the first and second directions DR1
and DR2. In the present exemplary embodiment, the display panel DP
may have various shapes. The display panel DP may have a shape
curved in at least one direction when viewed in a cross-section, or
the display panel DP may have at least one round-shaped edge when
viewed in a plan view.
[0056] The flexible printed circuit board FPC connects the display
panel DP and the printed circuit board PCB. FIG. 1 shows only one
flexible printed circuit board FPC, but the flexible printed
circuit board FPC may be provided in a plural number. The flexible
printed circuit boards FPC may be arranged in an edge of the
display panel along one direction. In the present exemplary
embodiment, the number of the flexible printed circuit boards may
vary.
[0057] As an example, the flexible printed circuit board FPC
includes a driving chip DC. The driving chip DC is mounted in a
tape carrier package (TCP) manner and includes a chip implemented
as a data driver. The driving chip DC may further include a chip
implemented as a gate driver. In addition, the gate driver may be
disposed in the non-display area NDA.
[0058] The printed circuit board PCB includes a controller to
control the display panel DP. The controller receives input image
signals and converts a data format of the input image signals to a
data format appropriate to an interface and a driving mode of the
data driver, the gate driver, and the display panel DP to generate
the image data. The controller outputs the image data and the
control signal. The image data include information with respect to
the image displayed in the display area DA.
[0059] The data driver receives the image data and the control
signal. The data driver converts the image data to data voltages in
response to the control signal and applies the data voltages to the
data lines DL1 to DLm. The data voltages may be analog voltages
corresponding to the image data.
[0060] Various electronic devices may be mounted on the printed
circuit board PCB to implement the controller. For instance, the
printed circuit board PCB may include a passive device, e.g., a
capacitor, a resistor, etc., an active device, e.g., a
microprocessor including an integrated circuit, a memory chip,
etc., and lines connecting them.
[0061] The display panel DP may further include an auxiliary
electrode 100. The auxiliary electrode 100 may be disposed between
the sub-pixels SPX when viewed in a plan view.
[0062] The auxiliary electrode 100 may have, for example, a grid
shape. The auxiliary electrode 100 includes a plurality of first
extension parts 100_a and a plurality of second extension parts
100_b. The first extension parts 100_a extend in the first
direction DR1 and are arranged in the second direction DR2. The
second extension parts 100_b extend in the second direction DR2 and
are arranged in the first direction DR1. The first and second
extension parts 100_a and 100_b may be disposed every one sub-pixel
SPX along the first and second directions DR1 and DR2, e.g., each
of the first extension parts 100_a may be disposed along
corresponding rows of sub-pixel SPX in a one-to-one correspondence,
and each of the second extension parts 100_b may be disposed along
corresponding columns of sub-pixels SPX in a one-to-one
correspondence. However, embodiments are not limited thereto or
thereby, e.g., the first and second extension parts 100_a and 100_b
may be disposed every two sub-pixels SPX along the first and second
directions DR1 and DR2.
[0063] The auxiliary electrode 100 may prevent an IR-drop from
occurring in the display panel DP. The IR-drop will be described in
detail later.
[0064] FIG. 2 is a plan view showing a display panel according to
an exemplary embodiment of the present disclosure, FIG. 3A is a
cross-sectional view taken along line I-I' in FIG. 2, FIG. 3B is an
enlarged cross-sectional view showing a first contact hole in FIG.
3A, and FIG. 3C is an enlarged cross-sectional view showing the
first contact hole in FIG. 3A.
[0065] Referring to FIG. 2, each of the pixels PX may include
first, second, third, and fourth sub-pixels SPX1, SPX2, SPX3, and
SPX4. The first to fourth sub-pixels SPX1 to SPX4 correspond to an
embodiment of the sub-pixels SPX shown in FIG. 1.
[0066] In the present exemplary embodiment, the first, second,
third, and fourth sub-pixels SPX1, SPX2, SPX3, and SPX4
respectively correspond to red, green, blue, and white sub-pixels.
Each of the first to fourth sub-pixels SPX1 to SPX4 may have, e.g.,
a substantially quadrangular shape.
[0067] In the present exemplary embodiment, the display panel DP
may include a pixel definition layer PDL disposed between the first
to fourth sub-pixels SPX1 to SPX4. The pixel definition layer PDL
may define a boundary between the first to fourth sub-pixels SPX1
to SPX4 and a boundary between the pixels PX.
[0068] In the present exemplary embodiment, a first contact hole
CNT1 is defined through the display panel DP. The first contact
hole CNT1 is defined in an area in which the first and second
extension parts 100_a and 100_b cross each other.
[0069] Referring to FIG. 3A, the display panel DP may include a
base substrate BS, a pixel circuit layer PC, a first insulating
layer ILL an organic light emitting element 200, a insulating layer
300, and a second insulating layer IL2. The base substrate BS may
be transparent and may include, e.g., a rigid glass or a flexible
polymer.
[0070] The pixel circuit layer PC may be disposed on the base
substrate BS. The pixel circuit layer PC may include a circuit to
drive the organic light emitting element 200 and at least two
transistors. The pixel circuit layer PC may include, e.g., a
switching transistor turned on in response to a gate signal applied
thereto to transmit the data voltage and a driving transistor
applying a driving current corresponding to the data voltage from
the switching transistor to the organic light emitting element
200.
[0071] The first insulating layer IL1 may be disposed on the pixel
circuit layer PC. The first insulating layer IL1 may include a
contact hole defined therethrough to expose a portion of the pixel
circuit layer PC. The first insulating layer IL1 has a single- or
multi-layer structure of an organic material or an inorganic
material.
[0072] In the present exemplary embodiment, the organic light
emitting element 200 may include a first electrode 210, a first
light emitting unit 220, an conductive thin film layer 230, a
second light emitting unit 240, and a second electrode 250.
[0073] In the present exemplary embodiment, the first electrode 210
may be disposed on the first insulating layer IL1. For example, a
first end of the first electrode 210 makes contact with the pixel
circuit layer PC through the contact hole in the first insulating
layer IL1 to receive the driving current from the pixel circuit
layer PC.
[0074] The base substrate BS includes a first area A1 and a second
area A2 spaced apart from the first area A1 in a horizontal
direction. A second end of the first electrode 210 extends from the
first electrode 210 and is disposed in the second area A2.
[0075] The auxiliary electrode 100 is disposed in the first area
A1. The auxiliary electrode 100 includes a conductive material. The
auxiliary electrode 100 may be a transparent electrode, a
semi-transparent electrode, or a non-transparent electrode (or a
reflective electrode). In addition, the auxiliary electrode 100 may
have a single-layer structure of a single material or plural
different materials or a multi-layer structure of layers formed of
different materials.
[0076] In the present exemplary embodiment, the pixel definition
layer PDL is disposed on the auxiliary electrode 100 and the first
electrode 210. The pixel definition layer PDL covers an edge of the
auxiliary electrode 100 and exposes a center portion of the
auxiliary electrode 100. A portion of the pixel definition layer
PDL may be disposed between the first and second areas A1 and A2
when viewed in a plan view. The first area A1 may be defined to
correspond to the center portion of the auxiliary electrode
100.
[0077] The pixel definition layer PDL may cover an edge of the
first electrode 210 and expose a center portion of the first
electrode 210. The second area A2 may be defined to correspond to
the exposed center portion of the first electrode 210.
[0078] In the present exemplary embodiment, the first light
emitting unit 220 is disposed on the pixel definition layer PDL,
the first electrode 210, and the auxiliary electrode 100. The first
light emitting unit 220 generates, e.g., a first light having a
first color. The first light emitting unit 220 includes a plurality
of organic layers.
[0079] In the present exemplary embodiment, the conductive thin
film layer 230 may be disposed on the first light emitting unit
220. The conductive thin film layer 230 is disposed between the
first and second light emitting units 220 and 240 to provide
electric charges (electrons and/or holes) to the first and second
light emitting units 220 and 240 and to control a balance of the
electric charges.
[0080] In the present exemplary embodiment, the second light
emitting unit 240 may be disposed on the conductive thin film layer
230. The second light emitting unit 240 generates, e.g., a second
light having a second color. The second light emitting unit 240
includes a plurality of organic layers.
[0081] In the present exemplary embodiment, the organic light
emitting element 200 may be, but is not limited to, a white organic
light emitting element. A color obtained by mixing the first and
second colors may be white, and the first and second colors may
have a complementary color relationship with each other. The first
and second lights may be mixed with each other to generate white
light. For example, the first and second colors may be respectively
blue and yellow colors, but they are not limited thereto or
thereby, e.g., the first and second colors may be respectively red
and green colors.
[0082] The second electrode 250 may be disposed on the insulating
layer 300. The second electrode 250 includes a first electrode part
251 disposed in the first area A1 and a second electrode part 252
extending from the first electrode part 251 and disposed in the
second area A2. In more detail, the first electrode part 251 and
the second electrode part 252 are respectively overlapped with the
auxiliary electrode 100 and the first electrode 210 when viewed in
a plan view.
[0083] The second electrode 250 is disposed over the entire surface
of the base substrate BS. Accordingly, the IR-drop occurs in the
second electrode 250 along the horizontal direction, and a
brightness of the pixel PX becomes different in accordance with a
position of the display panel DP. To prevent the IR-drop from
occurring, the second electrode 250 may be connected to the
auxiliary electrode 100. Since the auxiliary electrode 100 is
connected to the second electrode 250 through a first part 310 of
the insulating layer 300, the IR-drop occurring in the second
electrode 250 may be prevented from occurring or may be
reduced.
[0084] In the present exemplary embodiment, the insulating layer
300 is disposed on the second light emitting unit 240, first,
second, and third exposing surfaces 221, 231, and 241, and a
portion of the auxiliary electrode 100. In the present exemplary
embodiment, the insulating layer 300 includes the first part 310, a
second part 320, and a third part 330.
[0085] In detail, at least a portion of the first part 310, i.e., a
first portion of the first part 310, is disposed, e.g., conformally
along sidewalls, in the first contact hole CNT1. Referring to FIGS.
3B and 3C, the first contact hole CNT1 is defined in the first area
A1 and is disposed above the auxiliary electrode 100. The first
contact hole CNT1 is defined through the first light emitting unit
220, the conductive thin film layer 230, and the second light
emitting unit 240 to expose the auxiliary electrode 100. In FIGS.
3B and 3C, some elements are not shown for the convenience of
explanation of the first contact hole CNT1 and the first part 310.
For instance, the insulating layer 300 and layers disposed above
the insulating layer 300 are not shown in FIG. 3C.
[0086] In the following descriptions, the expression "a contact
hole is defined in a layer" means that a space obtained by
partially removing the layer is defined as the contact hole.
Accordingly, the first contact hole CNT1 may be defined by an empty
space (an area hatched with dots in FIGS. 3B and 3C) formed by
partially removing the first light emitting unit 220, the
conductive thin film layer 230, and the second light emitting unit
240.
[0087] At least a portion of an upper surface of the auxiliary
electrode 100, the first exposing surface 221 of the first light
emitting unit 220, the second exposing surface 231 of the
conductive thin film layer 230, and the third exposing surface 241
of the second light emitting unit 240 are exposed through the first
contact hole CNT1. Since the first portion of the first part 310 is
disposed in the first contact hole CNT1, the first portion of the
first part 310 may be disposed only in an area surrounded by the
first, second, and third exposing surfaces 221, 231, and 241.
[0088] The first portion of the first part 310 is disposed between
the conductive thin film layer 230 and the first electrode part
251. A lower surface of the first portion of the first part 310
makes contact with the first, second, and third exposing surfaces
221, 231, and 241, and an upper surface of the first portion 310
makes contact with the first electrode part 251.
[0089] In the present exemplary embodiment, a second portion of the
first part 310 is disposed between the first electrode part 251 and
the auxiliary electrode 100 to electrically connect the first
electrode part 251 to the auxiliary electrode 100. A lower surface
of the second portion of the first part 310 makes contact with the
auxiliary electrode 100. For example, referring to FIG. 3A, the
second portion of the first part 310 is a portion extending in
parallel to the base substrate BS, i.e., on a bottom of the first
contact hole CNT1, on the auxiliary electrode 100, and the first
portion of the first part 310 is a portion extending from the
second portion along sidewalls of the first contact hole CNT1.
[0090] In the present exemplary embodiment, the second part 320 is
disposed in the second area A2. The second part 320 is disposed on
the second electrode part 252 and disposed between the second light
emitting unit 240 and the second electrode part 252 in the second
area A2.
[0091] In the present exemplary embodiment, the third part 330 is
disposed between the first and second parts 310 and 320 when viewed
in a plan view and connects the first and second parts 310 and 320.
The third part 330 is disposed on the pixel definition layer
PDL.
[0092] The insulating layer 300 prevents the lateral leakage
current from flowing through the conductive thin film layer 230. If
the insulating layer 300 were to be omitted, the conductive thin
film layer 230 would directly contact the first electrode part 251
in the first contact hole CNT1, causing a first voltage applied to
the first electrode part 251 to be applied to the conductive thin
film layer 230, thereby causing lateral leakage current through the
conductive thin film layer 230 in the first contact hole CNT1.
Accordingly, the lateral leakage current could pass through the
first light emitting unit 220. In addition, a leakage voltage could
be applied in the second area A2 due to the lateral leakage
current. The leakage voltage may be voltage obtained by
voltage-dividing the voltage applied in the first contact hole CNT1
along a path of the lateral leakage current. The leakage voltage is
greater than the voltage applied to the first electrode 210 and
smaller than the first voltage.
[0093] If lateral leakage current and leakage voltage are applied
in the second areas A2, light emission of the light emitted from
the first light emitting unit 220 may be poor (hereinafter,
referred to as a "poor light emission"). For instance, if lateral
leakage current and leakage voltage are applied in the second areas
A2, e.g., when the insulating layer 300 is omitted, when voltage
corresponding to zero (0) grayscale level is applied to the first
electrode 210, the first light emitting unit 220 may emit light or
generate light corresponding to a grayscale level different from
the grayscale level of the voltage applied to the first electrode
210.
[0094] In contrast, according to the present exemplary embodiment,
the insulating layer 300 may insulate the conductive thin film
layer 230 from the second electrode 250, thereby preventing the
lateral leakage current and the leakage voltage between the
conductive thin film layer 230 and the first electrode part 251,
which in turn, prevents or substantially minimizes poor light
emission from occurring in the organic light emitting element 200.
In more detail, the first portion of the insulating layer 300 along
a sidewall of the first contact hole CNT1 may, e.g., completely or
partially, insulate the conductive thin film layer 230 from the
second electrode 250.
[0095] In the case that the insulating layer 300 completely
insulates the conductive thin film layer 230 from the second
electrode 250, the lateral leakage current does not flow to the
conductive thin film layer 230 from the first electrode part 251,
and the leakage voltage is not applied to the first part 310. In
the case that the insulating layer 300 partially insulates the
conductive thin film layer 230 from the second electrode 250, a
lateral leakage current equal to or smaller than a critical current
may flow, and leakage voltage equal to or smaller than a critical
voltage may be applied to the second part 320. When the leakage
voltage is smaller than the critical voltage and the lateral
leakage current is smaller than the critical current, the first
light emitting unit 220 may not emit the light, e.g., may not emit
light corresponding to voltage and/or current smaller than
respective critical values.
[0096] The insulating layer 300 has a resistance determined such
that poor light emission is prevented. The resistance of the
insulating layer 300 is greater than a resistance of the conductive
thin film layer 230. The insulating layer 300 has a thickness
determined such that the first electrode part 251 is electrically
connected to the auxiliary electrode 100 and the conductive thin
film layer 230 is insulated from the first electrode part 251.
[0097] The thickness of the insulating layer 300 is in a range from
about 1 nm to about 10 nm. The insulating layer 300 is required to
have the above indicated thickness, and thus the insulating layer
300 may have an insulating function in the first area A1. In
addition, it is preferred that the insulating layer 300 has the
above indicated thickness to perform an electron
injection/transport function or a hole injection/transport function
in the second area A2. These will be described in detail with
reference to FIG. 7. According to the above, in the present
exemplary embodiment, the insulating layer 300 insulates the
conductive thin film layer 230 from the second electrode 250, and
thus poor light emission of the organic light emitting element 200
due to the lateral leakage current may be prevented from occurring,
and the organic light emitting element 200 may be stably
driven.
[0098] Each of the first and second electrodes 210 and 250 includes
a conductive material. In more detail, each of the first and second
electrodes 210 and 250 is a transparent electrode, a
semi-transparent electrode, or a non-transparent electrode (or a
reflective electrode). In addition, the first and second electrodes
210 and 250 may have a single-layer structure of a single material
or plural different materials or a multi-layer structure of layers
formed of different materials.
[0099] In the case that each of the first and second electrodes 210
and 250 is a transparent electrode or a semi-transparent electrode,
each of the first and second electrodes 210 and 250 may include,
for example, Li, Ca, LiF/Ca, LiF/Al, Al, Mg, BaF, Ba, Ag, a
compound thereof, or a mixture thereof, e.g., a mixture of Ag and
Mg, each which is optically thin, or a transparent metal oxide,
e.g., indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide
(ZnO), indium tin zinc oxide (ITZO), Mo, Ti, etc. In the case that
each of the first and second electrodes 210 and 250 is a reflective
electrode, each of the first and second electrodes 210 and 250 may
include, e.g., Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca,
LiF/Ca, LiF/Al, Mo, Ti, a compound thereof, or a mixture thereof,
e.g., a mixture of Ag and Mg, each which is optically thick.
[0100] In the present exemplary embodiment, the organic light
emitting element 200 may be a rear surface light emitting type or a
front surface light emitting type. In the case that the organic
light emitting element 200 is a rear surface light emitting type,
the first electrode 210 is provided as a transparent or
semi-transparent electrode, and the second electrode 250 is a
reflective electrode. In this case, white light exits to the
outside through the first electrode 210. In the case that the
organic light emitting element 200 is a front surface light
emitting type, the first electrode 210 is provided as a reflective
electrode, the second electrode 250 is a transparent or
semi-transparent electrode, and accordingly, white light exits to
the outside through the second electrode 250.
[0101] As an example, the organic light emitting element 200 may
have a non-inverted structure or an inverted structure. When the
organic light emitting element 200 has a non-inverted structure,
the first electrode 210 is an anode, the second electrode 250 is a
cathode, and a voltage applied to the first electrode 210 is
greater than a voltage applied to the second electrode 250. On the
contrary, when the organic light emitting element 200 has an
inverted structure, the first electrode 210 is the cathode, the
second electrode 250 is the anode, and the voltage applied to the
first electrode 210 is smaller than the voltage applied to the
second electrode 250.
[0102] FIG. 3D is a cross-sectional view showing a display panel
according to an exemplary embodiment of the present disclosure. The
display panel DP in FIG. 3D is substantially the same as the
display panel DP in FIG. 3A, with the exception of the first
contact hole and the first part extending deeper than those in FIG.
3A.
[0103] Referring to FIG. 3D, the pixel circuit layer PC includes a
transistor TR. The transistor TR includes a gate electrode GE, a
source electrode SE, a drain electrode DE, and a semiconductor
layer SL. The semiconductor layer SL is disposed on the base
substrate BS. A first transistor insulating layer TRI1 is disposed
on the semiconductor layer SL. A second transistor insulating layer
TRI2 is disposed above the first transistor insulating layer TRI1.
The source electrode SE and the drain electrode DE are disposed on
the second transistor insulating layer TRI2 and spaced apart from
each other.
[0104] The source electrode SE is connected to one end of the
semiconductor layer SL through a contact hole defined through the
first and second transistor insulating layers TRI1 and TRI2, and
the drain electrode DE is connected to the other end of the
semiconductor layer SL through a contact hole defined through the
first and second transistor insulating layers TRI1 and TRI2. The
transistor TR applies voltage applied to the source electrode SE to
the first electrode 210 through the drain electrode DE in response
to a control signal applied to the gate electrode GE.
[0105] The auxiliary electrode 100 is disposed between the first
insulating layer IL1 and the second transistor insulating layer
TRI2, and the first insulating layer IL1 includes an intermediate
contact hole CNT_M defined therethrough to expose the auxiliary
electrode 100. That is, the upper surface of the auxiliary
electrode 100 is exposed through the intermediate contact hole
CNT_M. Portions of the first and second light emitting units 220
and 240 and the conductive thin film layers 230, which are disposed
in the first area A1, are disposed in the intermediate contact hole
CNT_M.
[0106] The first contact hole CNT1 is defined through the portions
of the first and second light emitting units 220 and 240 and the
conductive thin film layers 230, which are disposed in the
intermediate contact hole CNT_M. The upper surface of the auxiliary
electrode 100 is exposed through the first contact hole CNT1. For
example, as illustrated in FIG. 3D, the first and intermediate
contact holes CNT1 and CNT_M may be in fluid communication with
each other, e.g., portions of the first light emitting unit 220 may
extend along sidewalls of the first contact hole CNT1 and
continuously extend along sidewall of the intermediate contact hole
CNT_M. For example, as further illustrated in FIG. 3D, the
intermediate contact hole CNT_M may be between the first contact
hole CNT1 and sidewalls of the first insulating layer ILL e.g., the
intermediate contact hole CNT_M may extend radially from the first
contact hole CNT1 toward the sidewalls of the first insulating
layer IL1.
[0107] In the present exemplary embodiment, the first part 310 of
the insulating layer 300 is disposed in the first contact hole
CNT1. At least the portion of an upper surface of the auxiliary
electrode 100, the first exposing surface 221 of the first light
emitting unit 220, the second exposing surface 231 of the
conductive thin film layer 230, and the third exposing surface 241
of the second light emitting unit 240 are exposed through the first
contact hole CNT1. Since the first part 310 is disposed in the
first contact hole CNT1, the first part 310 may be disposed only in
the area surrounded by the first, second, and third exposing
surfaces 221, 231, and 241 and the first electrode part 251.
[0108] The first portion of the first part 310, e.g., on sidewalls
of the first contact hole CNT1, is disposed between the conductive
thin film layer 230 and the first electrode part 251. A lower
surface of the portion of the first part 310 makes contact with the
first, second, and third exposing surfaces 221, 231, and 241, and
an upper surface of the first portion 310 makes contact with the
first electrode part 251. In the present exemplary embodiment, the
second portion of the first part 310, e.g., on a bottom of the
first contact hole CNT1, is disposed between the first electrode
part 251 and the auxiliary electrode 100 to electrically connect
the first electrode part 251 to the auxiliary electrode 100. A
lower surface of the second portion of the first part 310 makes
contact with the auxiliary electrode 100. In addition, according to
another embodiment, the auxiliary electrode 100 may be disposed
between the first and second transistor insulating layers TRI1 and
TRI2. The first contact hole CNT1 is defined in the first
transistor insulating layer TRI1 to expose the upper surface of the
auxiliary electrode 100, and the first portion 310 may be disposed
in the first contact hole CNT1.
[0109] FIG. 4 is a plan view showing a display panel according to
an exemplary embodiment of the present disclosure, and FIG. 5 is a
cross-sectional view taken along line II-II' in FIG. 2. The display
panel DP in FIGS. 4 and 5 is substantially the same as the display
panel DP shown in FIGS. 2-3, except for a second contact hole CNT2
and the conductive thin film layer. Thus different features of the
second contact hole CNT2 and the conductive thin film layer will be
mainly described, and details of the others will be omitted.
[0110] Referring to FIG. 4, the second contact hole CNT2 may be
further defined in the display panel DP. The second contact hole
CNT2 may be defined in the first contact hole CNT1 when viewed in a
plan view.
[0111] Referring to FIG. 5, the second contact hole CNT2 is defined
in the first area A1 above the auxiliary electrode 100. The second
contact hole CNT2 is defined through the insulating layer 300. In
more detail, the second contact hole CNT2 is defined in the first
part 310, and at least a portion of an upper surface of the
auxiliary electrode 100 and a fourth exposing surface 301 of the
insulating layer 300 are exposed through the second contact hole
CNT2.
[0112] In the present exemplary embodiment, at least a portion of
the first electrode part 251 is disposed in the second contact hole
CNT2 and makes contact with the portion of the auxiliary electrode
100 exposed through the second contact hole CNT2. As described
above, since the second electrode 250 is directly connected to the
auxiliary electrode 100, a voltage drop does not occur between the
second electrode 250 and the auxiliary electrode 100. Accordingly,
the IR-drop may be effectively prevented, and a voltage-current
characteristic of the organic light emitting element 200 may be
improved.
[0113] FIG. 6 is a cross-sectional view showing a display panel
according to an exemplary embodiment of the present disclosure. The
display panel DP in FIG. 6 is substantially the same as the display
panel DP shown in FIG. 5, except for the insulating layer. Thus
different features of the insulating layer will be mainly
described, and details of the others will be omitted.
[0114] Referring to FIG. 6, the insulating layer 300 is not
disposed in the second area A2. The insulating layer 300 is
disposed spaced apart from the second area A2 without being
overlapped with the second area A2 when viewed in a plan view. In
other words, the second and third parts 320 and 330 may be
omitted.
[0115] In the present exemplary embodiment, the insulating layer
300 is not disposed between organic layers of the organic light
emitting element 200 in the second area A2. Accordingly, the
insulating layer 300 does not exert an influence on the balance of
electric charge and the voltage-current characteristic of the
organic light emitting element 200. Thus, a design of the organic
light emitting element 200 to maintain the electric charge balance
and a design of the insulating layer 300 to prevent the lateral
leakage current from occurring may be independently performed.
[0116] FIG. 7 is a schematic cross-sectional view of the organic
light emitting element 200.
[0117] Referring to FIG. 7, the first light emitting unit 220
includes a first hole control layer HCL1, a first light emitting
layer EML1, and a first electron control layer ECL1. The second
light emitting unit 240 includes a second hole control layer HCL2,
a second light emitting layer EML2, and a second electron control
layer ECL2.
[0118] The first and second light emitting layers EML1 and EML2 are
disposed between the first electrode 210 and the second electrode
250. In the present exemplary embodiment, each of the first and
second light emitting layers EML1 and EML2 includes a host material
and a dopant material. Each of the first and second light emitting
layers EML1 and EML2 is formed by applying a fluorescent material
or a phosphorescent material to the host material.
[0119] As the host, for example,
Alq3(tris(8-hydroxyquinolino)aluminum),
CBP(4,4'-bis(N-carbazolyl)-1,1'-biphenyl),
PVK(poly(n-vinylcabazole),
ADN(9,10-di(naphthalene-2-yl)anthracene),
TCTA(4,4',4''-Tris(carbazol-9-yl)-triphenylamine),
TPBi(1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene),
TBADN(3-tert-butyl-9,10-di(naphth-2-yl)anthracene),
DSA(distyrylarylene),
CDBP(4,4'-bis(9-carbazolyl)-2,2''-dimethyl-biphenyl),
MADN(2-Methyl-9,10-bis(naphthalen-2-yl)anthracene) may be used.
However, embodiments are not limited thereto or thereby.
[0120] Colors of the light emitting layers may be determined by a
combination of the host material and the dopant material. For
instance, when the light emitting layers emit red light, the light
emitting layers may include a fluorescent material containing,
e.g., PBD:Eu(DBM)3(Phen)(tris(dibenzoylmethanato)phenanthoroline
europium) or Perylene. When the light emitting layers emit the red
light, the dopant included in the organic light emitting layers may
be a metal complex, e.g.,
PIQIr(acac)(bis(1-phenylisoquinoline)acetylacetonate iridium),
PQIr(acac)(bis(1-phenylquinoline)acetylacetonate iridium),
PQIr(tris(1-phenylquinoline)iridium), PtOEP(octaethylporphyrin
platinum), etc., or organometallic complex.
[0121] When the light emitting layers emit green light, the light
emitting layers may include a fluorescent material containing,
e.g., Alq3(tris(8-hydroxyquinolino)aluminum). When the light
emitting layers emit the green light, the dopant included in the
light emitting layers may be a metal complex, e.g.,
Ir(ppy)3(fac-tris(2-phenylpyridine)iridium), or organometallic
complex.
[0122] When the light emitting layers emit blue light, the light
emitting layers may include a fluorescent material including, e.g.,
any one from the groups consisting of spiro-DPVBi, spiro-6P,
DSB(distyryl-benzene), DSA(distyryl-arylene),
PFO(Polyfluorene)-based polymer, and PPV(poly(p-phenylene
vinylene)-based polymer. When the light emitting layers emits blue
light, the dopant included in the light emitting layers may be a
metal complex, e.g., (4,6-F2ppy)2Irpic, or organometallic
complex.
[0123] The first light emitting layer EML1 generates light having a
wavelength shorter than a wavelength of a light generated by the
second light emitting layer EML2. As described above, the first
light may be the blue light and have a wavelength range equal to or
greater than about 450 nm and equal to or smaller than about 595
nm. As described above, the second light may be the yellow light
and have a wavelength range equal to or greater than about 570 nm
and equal to or smaller than about 590 nm.
[0124] Meanwhile, the first and second light emitting layers EML1
and EML2 may be designed to generate lights having various colors
according to embodiments. The first and second light emitting
layers EML1 and EML2 may be formed by various methods, e.g., a
vacuum deposition method, a spin coating method, a cast method, an
LB (Langmuir-Blodgett) method, an inkjet printing method, a laser
printing method, an LITI (Laser Induced Thermal Imaging) method,
etc.
[0125] The conductive thin film layer 230 is disposed between the
first and second light emitting layers EML1 and EML2 to improve a
current efficiency and a light efficiency of the organic light
emitting element 200. When voltage is applied to the conductive
thin film layer 230, the conductive thin film layer 230 generates
electric charges by a complex formation due to oxidation-reduction
reaction.
[0126] In the present exemplary embodiment, the conductive thin
film layer 230 may include first and second conductive thin film
layers 231 and 232 sequentially stacked. The first and second
conductive thin film layers 231 and 232 may be respectively N-type
and P-type conductive thin film layers. The N-type conductive thin
film layer may include an alkali metal, e.g., Li, Na, K, Cs, or the
like, or an organic layer doped with an alkali earth metal, e.g.,
Mg, Sr, Ba, Ra, or the like, but it should not be limited thereto
or thereby. The P-type conductive thin film layer may include an
organic layer with a P-type dopant, but it should not be limited
thereto or thereby.
[0127] The first hole control layer HCL1 is disposed between the
first electrode 210 and the first light emitting layer EML1. The
second hole control layer HCL2 is disposed between the electric
charge layer 230 and the second light emitting layer EML2.
[0128] When the first electrode 210 is an anode electrode layer,
holes injected from the first electrode 210 are provided to the
first light emitting layer EML1 through the first hole control
layer HCL1. The holes generated by the conductive thin film layer
230 are provided to the second light emitting layer EML2 through
the second hole control layer HCL2.
[0129] Each of the first and second hole control layers HCL1 and
HCL2 may correspond to at least one of a hole injection area, a
hole transport area, a buffer area, and an electron block area.
Each of the first and second hole control layers HCL1 and HCL2 may
have a single-layer structure of a single material or plural
different materials or a multi-layer structure of layers formed of
different materials.
[0130] For instance, each of the first and second hole control
layers HCL1 and HCL2 may include at least one of a hole injection
layer corresponding to the hole injection layer, a hole transport
layer corresponding to the hole transport area, and a single layer
having a hole injection function and a hole transport function.
[0131] Each of the first and second hole control layers HCL1 and
HCL2 may include at least one of a hole injection material and a
hole transport material. The hole injection material and the hole
transport material may be known materials.
[0132] The hole transport material may include, but not limited to,
e.g., carbazole-based derivatives, e.g., n-phenyl carbazole,
polyvinyl carbazole, etc., fluorine-based derivatives,
triphenylamine-based derivatives, e.g.,
TPD(N,N-bis(3-methylphenyl)-N,N-diphenyl[1,1-biphenyl]-4,4'-diamine),
TCTA(4,4',4''-tris(N-carbazolyl)triphenylamine), etc.,
NPB(N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine), or
TAPC(4,4'-Cyclohexylidene bis[N,N-bis(4-methylphenyl)benzenamine]).
The hole injection material may include, but not limited to, at
least one of a phthalocyanine compound such as copper
phthalocyanine, DNTPD
(N,N'-diphenyl-N,N'-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4'-d-
iamine),
m-MTDATA(4,4',4''-tris(3-methylphenylphenylamino)triphenylamine),
TDATA(4,4'4''-Tris(N,N-diphenylamino)triphenylamine),
2TNATA(4,4',4''-tris{N,-(2-naphthyl)-N-phenylamino}-triphenylamine),
PEDOT/PSS(Poly(3,4-ethylenedioxythiophene)/Poly(4-styrenesulfonate),
PANI/DBSA(Polyaniline/Dodecylbenzenesulfonic acid),
PANI/CSA(Polyaniline/Camphor sulfonicacid),
PANI/PSS((Polyaniline)/Poly(4-styrenesulfonate), etc.
[0133] Each of the first and second hole control layers HCL1 and
HCL2 may be formed by similar process of forming the first and
second light emitting layers EML1 and EML2. For instance, each of
the first and second hole control layers HCL1 and HCL2 may be
formed by various methods, e.g., a vacuum deposition method, a spin
coating method, a cast method, an LB (Langmuir-Blodgett) method, an
inkjet printing method, a laser printing method, an LITI (Laser
Induced Thermal Imaging) method, etc.
[0134] Meanwhile, each of the first and second hole control layers
HCL1 and HCL2 may include a hole block layer corresponding to the
hole block area. In this case, each of the first and second hole
control layers HCL1 and HCL2 may include a hole block material. In
addition, each of the first and second hole control layers HCL1 and
HCL2 may further include an electric charge generating
material.
[0135] The first electron control layer ECL1 is disposed between
the first light emitting layer EML1 and the conductive thin film
layer 230. The electrons generated by the conductive thin film
layer 230 are provided to the first light emitting layer EML1
through the first electron control layer ECL1.
[0136] The second electron control layer ECL2 is disposed between
the second light emitting layer EML2 and the second electrode 250.
When the second electrode 250 is a cathode electrode layer, the
electrons injected from the second electrode 250 are provided to
the second light emitting layer EML2 through the insulating layer
300 and the second electron control layer ECL2.
[0137] Each of the first and second electron control layers ECL1
and ECL2 may correspond to at least one of an electron injection
area, an electron transport area, and a hole block area. Each of
the first and second electron control layers ECL1 and ECL2 may have
a single-layer structure of a single material or plural different
materials or a multi-layer structure of layers formed of different
materials.
[0138] For instance, each of the first and second electron control
layers ECL1 and ECL2 may include at least one of an electron
injection layer corresponding to the electron injection layer, an
electron transport layer corresponding to the electron transport
area, and a single layer having an electron injection function and
an electron transport function.
[0139] Each of the first and second electron control layers ECL1
and ECL2 may include at least one of an electron transport material
and an electron injection material. For instance, the electron
transport material may include, but not limited to,
Alq3(Tris(8-hydroxyquinolinato)aluminum),
TPBi(1,3,5-Tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl),
BCP(2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline),
Bphen(4,7-Diphenyl-1,10-phenanthroline),
TAZ(3-(4-Biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole),
NTAZ(4-(Naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole),
tBu-PBD(2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole),
BAlq(Bis(2-methyl-8-quinolinolato-N1,O8)-(1,1'-Biphenyl-4-olato)aluminum)-
, Bebq2(berylliumbis(benzoquinolin-10-olate),
ADN(9,10-di(naphthalene-2-yl)anthracene), or a compound
thereof.
[0140] In addition, the electron injection material may include a
lanthanide-based metal, e.g., LiF, LiQ (Lithium quinolate),
Li.sub.2O, BaO, NaCl, CsF, Yb, etc., or a metal halide, e.g., RbCl,
RbI, etc., but it should not be limited thereto or thereby. The
electron transport layer may include a mixture of an electron
transport material and an organo metal salt with insulating
property.
[0141] The organo metal salt has an energy band gap of about 4 eV
or more. In detail, the organo metal salt may include, e.g., metal
acetate, metal benzoate, metal acetoacetate, metal acetylacetonate,
or metal stearate.
[0142] Each of the first and second electron control layers ECL1
and ECL2 may be formed by various methods, e.g., a vacuum
deposition method, a spin coating method, a cast method, an LB
(Langmuir-Blodgett) method, an inkjet printing method, a laser
printing method, an LITI (Laser Induced Thermal Imaging) method,
etc.
[0143] The organic light emitting element 200 according to the
present disclosure should not be limited to the above-mentioned
structure and function. For instance, the organic light emitting
element 200 may include three light emitting units and two
conductive thin film layers interposed between the three light
emitting units. In this structure, the insulating layer 300 may
insulate the two conductive thin film layers from the second
electrode 250.
[0144] As an example, the insulating layer 300 corresponds to a
separate component disposed on the second light emitting unit 240,
but the present disclosure should not be limited thereto or
thereby. That is, the insulating layer 300 may be provided as a
layer that performs a function of the second light emitting unit
240. For instance, the insulating layer 300 may correspond to the
electron injection area, and the second electron control layer ECL2
of the second light emitting unit 240 may include the electron
transport area and the hole block area. In this structure, the
insulating layer 300 may perform a function of the electron
injection area of the second light emitting unit 240. Similarly,
the insulating layer 300 may be not only the electron injection
area but also the electron transport area and the hole block area.
In addition, in the case that the organic light emitting element
200 has the inverted structure, the insulating layer 300 may be one
of the hole injection area, the hole transport area, and the
electron block area.
[0145] The insulating layer 300 may include, for example, at least
one of LiQ and LiF. As an example, in the non-inverted structure,
the insulating layer 300 may include the host material of the first
and second hole control layers HCL1 and HCL2 to block the
injection/transport of the electrons or a material of the first and
second electron control layers ECL1 and ECL2, which has a low
electron conductivity. Accordingly, the electrons injected from the
first electrode part 251 that is the cathode are blocked, and thus
the lateral leakage current may be effectively prevented.
[0146] The insulating layer 300 has a thickness of about 1 nm to
about 10 nm. When the thickness of the insulating layer 300 is
smaller than about 1 nm, the insulating layer 300 may not be
sufficiently thick to properly perform an insulating function with
respect to the conductive thin film layer 230 in the first area A1
(refer to FIG. 3A). When the thickness of the insulating layer 300
exceeds about 10 nm, the insulating layer 300 may be too thick to
perform the function of the electron injection/transport with
respect to the second light emitting unit 240 in the second area A2
(refer to FIG. 3A).
[0147] As an example, in the inverted structure, the insulating
layer 300 may include the host material of the first and second
electron control layers ECL1 and ECL2 to block the
injection/transport of the holes or a material of the first and
second hole control layers HCL1 and HCL2, which has a low hole
conductivity. Accordingly, the holes injected from the first
electrode part 251 that is the anode are blocked, and thus the
lateral leakage current may be effectively prevented.
[0148] FIGS. 8A to 8F are cross-sectional views showing stages in a
method of manufacturing a display panel according to an exemplary
embodiment.
[0149] Referring to FIG. 8A, the pixel circuit layer PC is formed
on the base substrate BS, and the first insulating layer IL1 is
formed on the pixel circuit layer PC. A driving contact hole CNT_Dr
is formed through the first insulating layer IL1. A portion of the
pixel circuit layer PC is exposed through the driving contact hole
CNT_Dr.
[0150] Referring to FIG. 8B, the first electrode 210 and the
auxiliary electrode 100 are formed on the first insulating layer
IL1. As described above, the first end of the first electrode 210
is disposed in the driving contact hole CNT_Dr formed through the
first insulating layer IL1 and makes contact with the pixel circuit
layer PC. The second end of the first electrode 210 extends from
the first end of the first electrode 210 and is disposed in the
second area A2. The auxiliary electrode 100 is spaced apart from
the first electrode 210 and disposed in the first area
[0151] Al.
[0152] As shown in FIG. 8C, the pixel definition layer PDL is
formed on the first electrode 210 and the auxiliary electrode 100.
Then, the first light emitting unit 220, the conductive thin film
layer 230, and the second light emitting unit 240 are sequentially
formed on the pixel definition layer PDL, the first electrode 210,
and the auxiliary electrode 100.
[0153] Referring to FIG. 8D, the first contact hole CNT1 is formed
in the first area A1. The first contact hole CNT1 is formed by
removing portions (hereinafter, referred to as "removed layers") of
the first light emitting unit 220, the conductive thin film layer
230, and the second light emitting unit 240 in the first area A1 to
expose a portion, e.g., of the upper surface, of the first
auxiliary electrode 100. As an example, since the removed layers
are removed, the first, second, and third exposing surfaces 221,
231, and 241 are formed, e.g., the first through third exposing
surfaces 221 through 241 are lateral surfaces facing the interior
of the first contact hole CNT1 and defining a sidewall of the first
contact hole CNT1.
[0154] Referring to FIG. 8E, the insulating layer 300 is formed,
e.g., conformally, on the second light emitting unit 240. The first
part 310 is formed, e.g., conformally, in the first contact hole
CNT1 and makes contact with the exposed auxiliary electrode 100.
Then, as shown in FIG. 8F, the first electrode part 251 and the
second insulating layer IL2 are formed on the insulating layer
300.
[0155] FIGS. 9A to 9C are cross-sectional views showing stages in a
method of manufacturing a display panel according to an exemplary
embodiment.
[0156] Referring to FIG. 9A, components including the pixel circuit
layer PC, the insulating layer 300, and elements disposed between
the pixel circuit layer PC and the insulating layer 300 are
sequentially stacked on the base substrate BS. A method of stacking
the pixel circuit layer PC, the insulating layer 300, and elements
disposed between the pixel circuit layer PC and the insulating
layer 300 are the same as the manufacturing method described with
reference to FIGS. 8A to 8E, and thus details thereof will be
omitted.
[0157] Referring to FIG. 9B, the second contact hole CNT2 is formed
through the insulating layer 300. The second contact hole CNT2 is
formed by removing a portion of the first part 310 in the first
area A1 to expose a portion of the auxiliary electrode 100. As an
example, the portion of the first part 310 may be removed by using
a laser drilling method. When the portion of the first part 310 is
removed, the fourth exposing surface 301 is formed.
[0158] As shown in FIG. 9C, the second electrode 250 is formed on
the insulating layer 300. The first electrode part 251 makes
contact with the auxiliary electrode 100 exposed through the second
contact hole CNT2. The second insulating layer IL2 is formed on the
second electrode 250.
[0159] By way of summation and review, the present disclosure
provides a display panel capable of preventing poor emission of an
organic light emitting element due to a lateral leakage current.
The present disclosure also provides a method of manufacturing the
display panel, as well as a display device having the display
panel.
[0160] That is, according to embodiments, a insulating layer is
disposed between the conductive thin film layer and the second
electrode to insulate the conductive thin film layer from the
second electrode. Accordingly, the lateral leakage current may be
prevented from flowing through the conductive thin film layer, and
defect in light emission of the organic light emitting element may
be prevented from occurring due to the lateral leakage current.
[0161] Example embodiments have been disclosed herein, and although
specific terms are employed, they are used and are to be
interpreted in a generic and descriptive sense only and not for
purpose of limitation. In some instances, as would be apparent to
one of ordinary skill in the art as of the filing of the present
application, features, characteristics, and/or elements described
in connection with a particular embodiment may be used singly or in
combination with features, characteristics, and/or elements
described in connection with other embodiments unless otherwise
specifically indicated. Accordingly, it will be understood by those
of skill in the art that various changes in form and details may be
made without departing from the spirit and scope of the present
invention as set forth in the following claims.
* * * * *