U.S. patent application number 13/510485 was filed with the patent office on 2012-09-13 for organic el display.
This patent application is currently assigned to Sharp Kabushiki Kaisha. Invention is credited to Hideyo Nakamura.
Application Number | 20120228603 13/510485 |
Document ID | / |
Family ID | 44059293 |
Filed Date | 2012-09-13 |
United States Patent
Application |
20120228603 |
Kind Code |
A1 |
Nakamura; Hideyo |
September 13, 2012 |
ORGANIC EL DISPLAY
Abstract
An object of the present invention is to provide an organic EL
display that has a reduced optical loss and high efficiency, and
can be manufactured by an inexpensive method. The organic EL
display of the present invention is formed by bonding an organic EL
element substrate including a substrate, reflective electrode,
organic EL layer, separation wall, barrier layer, transparent
electrode, and color conversion layer; and a sealing substrate
together, wherein: the reflective electrode includes a plurality of
partial electrodes; the organic EL layer is formed on the
reflective electrode and includes a plurality of parts separated by
the separation wall; the transparent electrode is formed on the
organic EL layer; the barrier layer covers the separation wall and
the transparent electrode, and has a recessed part in a location
corresponding to the reflective electrode; and the color conversion
layer is formed in the recessed part.
Inventors: |
Nakamura; Hideyo;
(Matsumoto-shi, JP) |
Assignee: |
Sharp Kabushiki Kaisha
Osaka-shi
JP
|
Family ID: |
44059293 |
Appl. No.: |
13/510485 |
Filed: |
November 17, 2009 |
PCT Filed: |
November 17, 2009 |
PCT NO: |
PCT/JP2009/006171 |
371 Date: |
May 17, 2012 |
Current U.S.
Class: |
257/40 ;
257/E27.119 |
Current CPC
Class: |
H01L 51/0005 20130101;
H01L 51/5234 20130101; H01L 51/5228 20130101; H01L 51/5203
20130101; H01L 51/5225 20130101; H01L 2251/5315 20130101; H01L
27/322 20130101; H01L 51/5253 20130101; H01L 51/5218 20130101; H01L
51/525 20130101; H01L 27/3246 20130101 |
Class at
Publication: |
257/40 ;
257/E27.119 |
International
Class: |
H01L 27/32 20060101
H01L027/32 |
Claims
1. An organic EL display formed by bonding: an organic EL element
substrate comprising a substrate, a reflective electrode, an
organic EL layer, a separation wall, a barrier layer, a transparent
electrode, and a color conversion layer; and a sealing substrate to
each other, wherein: the reflective electrode is constituted of a
plurality of partial electrodes; the organic EL layer is formed on
the reflective electrode and is constituted of a plurality of parts
that are separated by the separation wall; the transparent
electrode is formed on the organic EL layer; the barrier layer
covers the separation wall and the transparent electrode, and has a
recessed part in a location corresponding to the reflective
electrode; and the color conversion layer is formed in the recessed
part.
2. The organic EL display according to claim 1, wherein a
refractive index of the color conversion layer is equal to or more
than a refractive index of the barrier layer.
3. The organic EL display according to claim 1, wherein the sealing
substrate further comprises a color filter.
4. The organic EL display according to claim 1, wherein: the
separation wall has a plurality of openings respectively
corresponding to the partial electrodes that constitute the
reflective electrode; and the organic EL layer is formed in the
plurality of openings.
5. The organic EL display according to claim 4, further comprising
auxiliary wiring for the transparent electrode, wherein the
auxiliary wiring is connected to the transparent electrode in an
area where the organic EL layer is not formed by the separation
wall.
6. The organic EL display according to claim 4, wherein: the
separation wall is formed of a metallic material; and the
transparent electrode is electrically connected to the separation
wall.
7. The organic EL display according to claim 1, wherein: the
separation wall is constituted of a plurality of striped parts that
are arranged in gaps between the plurality of partial electrodes
constituting the reflective electrode and extend in one direction;
and the organic EL layer is formed in a gap of the separation
wall.
8. The organic EL display according to claim 7, wherein the
transparent electrode is constituted of a plurality of striped
parts that are separated by the separation wall.
9. The organic EL display according to claim 8, wherein applied
voltage is individually controlled for each of the plurality of
striped parts of the transparent electrode.
10. The organic EL display according to claim 8, wherein an
electrical characteristic can be measured for each of the plurality
of striped parts of the transparent electrode.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a national stage application under 35
USC 371 of International Application No. PCT/JP2009/006171, filed
Nov. 17, 2009, the entire contents of which are incorporated herein
by reference.
FIELD OF THE INVENTION
[0002] The present invention mainly relates to an organic EL
display.
BACKGROUND OF THE INVENTION
[0003] A panel unit of an organic EL display having a top emission
structure typically has a configuration in which an organic EL
element substrate (a TFT substrate) and a color filter substrate
are bonded together.
[0004] An organic EL element substrate having a conventional
structure includes, for example, a glass substrate, a TFT
structure, planarizing resin, an inorganic passivation film that
may be optionally provided, an underlying layer for enhancing
adhesiveness, reflective electrodes, an insulating film that has
openings in locations serving as light emitting parts, an organic
EL layer, a transparent electrode (including semitransparent one),
and a barrier layer that covers a structure including and below the
transparent electrode within a display area, in this order. The
transparent electrode is connected to wiring in a circumferential
edge part of the organic EL element substrate.
[0005] On the other hand, a color filter substrate having a
conventional structure includes, for example, a glass substrate,
black matrix, color filters, and color conversion layers that may
be optionally provided, in this order. As a method for forming the
color filters and/or color conversion layers, in addition to a
conventional photolithography method, an application (coating)
method such as an inkjet method is also becoming widely used. In
the case of using the application method to form plural kinds of
color filters and/or color conversion layers, it is common to use a
separation wall to selectively form each of the color filters
and/or color conversion layers in a desired location.
[0006] Finally, an organic EL display is obtained by bonding the
organic EL element substrate and the color filter substrate
together while opposing the light emitting parts of the organic EL
element substrate against the color filters of the color filter
substrate with registering. The bonding can be performed by a
method such as a vacuum dripping bonding method that is commonly
used for liquid crystal display manufacturing. In order to highly
efficiently transmit light from the organic EL element substrate
side to the color filter substrate side and keep mechanical
strength, filler such as an adhesive may be enclosed in a bonding
gap. If accurate control of the bonding gap between the organic EL
element substrate and the color filter substrate is desired,
spacers can be provided on the color filter, or the like. If the
bonding gap is too wide, a crosstalk problem that light penetrates
into an adjacent pixel is concerned. On the other hand, if the
bonding gap is too narrow, influence of interference, mechanical
contact between the organic EL element substrate and the color
filter substrate in the display area, and the like are concerned.
In particular, in the case of enclosing the filler in the bonding
gap, if the bonding gap is too narrow, the included filler may
distribute unevenly.
[0007] For example, in the case of forming the color conversion
layer by an application method using a bank, the color conversion
layer is formed by forming a separation wall having a desired shape
and applying color conversion layer-forming ink with use of an
inkjet device or the like in the state that a processing surface,
on which the separation wall has been formed, faces upward, to form
the color conversion layer. The color conversion layer-forming ink
is generally prepared by dissolving or dispersing a color
converting material into a solvent. An ink droplet just after the
application has a raised shape to the extent that it protrudes from
an upper part of the separation wall. Then, by heat-drying the ink
droplet, a planar layer is formed in the bottom of the separation
wall. Usually, by repeating the application and heat-drying a
plurality of times, the color conversion layer having a desired
film thickness is obtained.
[0008] In this case, the separation wall is required to have a
height of about 3 to 7 .mu.m in order to prevent an ink droplet
from leaking at the time of the application. Such a height can not
be ignored as compared with a sub pixel size of about 40 to 60
.mu.m in a display having a resolution of 200 to 150 ppi, and
thereby the efficiency may be reduced by increase of a ratio of
emitted light that does not enter the color conversion layer of a
predetermined sub pixel but deviates transversely. In addition, in
the case where the transversely deviated light enters an adjacent
different color sub pixel, the color conversion layer of the
adjacent sub pixel may emit converted light and the emitted light
may produce undesired hue.
[0009] Further, the thin-film organic EL layer has extremely low
mechanical strength. Therefore in the organic EL display employing
the bonding structure as described above, mechanical bonding
strength in the display area can not be expected at all. For this
reason, concern on film peeling due to heat shock or impact applied
when used, shrinkage by curing at the time of solidifying the
enclosed filler, or the like is inherent in a large-screen
bonding-type organic EL display, even if a whole of the display
area is bonded by filling the adhesive into the bonding gap. Also,
a structure involving a hollow bonding gap has been proposed by
many institutions from the start time of the organic EL display;
however, it goes without saying that such a structure is not
advantageous to manufacturing of the large screen display.
[0010] In addition, in the top emission type organic EL display in
which the organic EL layer is formed by a vapor deposition, the
barrier layer for protecting the organic EL layer is substantially
essential. However, in the case where the structure in which the
filler is enclosed in the bonding gap is adopted and the filler has
a lower refractive index than that of the barrier layer, total
reflection occurs at an interface between the barrier layer and the
filler, preventing sufficient amount of light from being
transmitted, and therefore resulting in an optical loss. For
example, SiN or the like that is commonly used for the barrier
layer has a refractive index of about 1.7 to 1.9. On the other
hand, the types of resins having a higher refractive index than
this are very few, and therefore a range of filler selection is
narrowed to constrain a manufacturing method. In addition, such
filler is a special and expensive material, and therefore becomes a
factor for increasing manufacturing cost. Meanwhile, in the case of
forming the barrier layer with use of a material such as SiO having
a refractive index of about 1.5 in order to conform the refractive
index to that of typical resin, reflection at the interface between
the barrier layer and the filler is reduced, but a large loss
occurs in light on the way from the organic EL layer and
transparent electrode to the barrier layer. This is because the
organic EL layer and the transparent electrode typically have
reflective indices of about 2, respectively.
[0011] As a method for solving the optical loss caused by the
filler enclosed in the bonding gap as described above, Japanese
Patent Laid-Open No. 2006-32010 proposes a structure in which a
forward tapered shaped insulating film for separating a cathode is
used as a separation wall on which an organic EL layer, transparent
anode, and protective layer are formed, and on the protective
layer, a color filter and/or color conversion layer is formed (see
PTL 1). In this structure, the insulating film used as a bank and
the organic EL layer of a light emitting part are joined to each
other throughout a whole screen. Here, the insulating film that is
formed of an organic material and extremely thick as compared with
the other layers contains a large amount of outgas such as
moisture. An amount of outgas transmitted through the insulating
film increases because the film thickness is large. In a state
where the insulating film and the organic EL layer are joined to
each other throughout the whole screen, the outgas is easily
transmitted from the insulating film to the organic EL layer, which
may cause an area called as a dark spot or dark area to be spread
in a short period of time. Further, Japanese Patent Laid-Open No.
2006-32010 does not disclose sealing based on substrate bonding;
however, the sealing is practically required. Therefore, as
described above, there is a concern on insufficient mechanical
strength due to the thin film organic EL layer.
[0012] In addition, it is necessary to consider the transmission of
the outgas or solvent through the protective layer. Even if taking
countermeasures against the insulating film used as the bank (more
stringent heat treatment condition at the time of forming the
insulating film, or the formation of the insulating film with an
inorganic material), continuity of the organic EL layer over the
whole display area, per se, may cause broad area transmission of
the outgas that penetrates through the protective layer. In
particular, in the case of applying a color converting material on
the protective layer to form the color conversion layer by a wet
process such as an inkjet method, the organic EL layer is
significantly damaged by a component penetrating through the
protective layer. This is because it is necessary to dilute the
color converting material down to 1 to a few % with an organic
solvent that significantly damages the organic EL layer in the
formation of the color conversion layer by the wet process. This
situation is tantamount to applying the solvent on the organic EL
layer and protective layer, therefore dramatically increasing a
possibility that the component damaging the organic EL layer
penetrates from defects such as pinholes, which are sparsely
present in the protective layer, to give rise to dark areas in a
wide region of the display area.
[0013] On the other hand, Japanese Patent Laid-Open No. 2008-78038
or the like proposes an organic EL element substrate in which a
separation wall is used to separate an organic EL layer and the
like into plural parts (see PTL2 or the like). A structure in
Japanese Patent Laid-Open No. 2008-78038 is intended to use a vapor
deposition method having high directionality to separate the
organic EL layer with use of the separation wall. At the same time,
the structure is intended to expose an auxiliary electrode formed
on the substrate and to form a transparent electrode by a
sputtering method exhibiting relatively good coverage (i.e., having
low directionality) to connect the transparent electrode to the
auxiliary electrode. Besides this proposal, it is well known that,
an orthogonal grid shaped separation wall is formed on the organic
EL element substrate side in the case of using inkjet or the like
to form the organic EL layer itself. Alternatively, for example, if
a metal transparent electrode that is thin enough to transmit light
is formed by a vapor deposition method having high directionality
as done in the organic EL layer, and the transparent electrode is
separated into a plurality of lines by the separation wall, it
become possible not to control the display area as a whole, but to
control it for each of the lines. Accordingly, in view of
versatility of control, forming the separation wall on the organic
EL element substrate side itself could be easily thought. However,
in such an organic EL display in which the organic EL element
substrate is bonded to the color filter substrate having the color
conversion layer, it is easily inferred that a height of the
separation wall on the color filter side and a height of the
separation wall on the organic EL element substrate side are simply
summed, which further increases an optical loss.
[0014] PTL 1: Japanese Patent Laid-Open No. 2006-32010
[0015] PTL 2: Japanese Patent Laid-Open No. 2008-78038
[0016] PTL 3: Japanese Patent Laid-Open No. 2005-93398
SUMMARY OF THE INVENTION
[0017] Therefore, an object of the present invention is to provide
an organic EL display that has a reduced optical loss and high
efficiency and is inexpensive, in the field of a top emission type
organic EL display based on a color conversion system. Also,
another object of the present invention is to provide a large
screen organic EL display that has increased bonding strength in a
display area, and exhibits high resistance to heat shock and
impact. Further, still another object of the present invention is
to provide an organic EL display that enables selectivity of filler
included in a bonding gap to be expand and can be manufactured by a
simple method. An organic EL display of the present invention is
formed by bonding together: an organic EL element substrate
comprising a substrate, a reflective electrode, an organic EL
layer, a separation wall, a barrier layer, a transparent electrode,
and a color conversion layer; and a sealing substrate, wherein: the
reflective electrode is constituted of a plurality of partial
electrodes; the organic EL layer is formed on the reflective
electrode and is constituted of a plurality of parts that are
separated by the separation wall; the transparent electrode is
formed on the organic EL layer; the barrier layer covers the
separation wall and the transparent electrode, and has recessed
parts in a location corresponding to the reflective electrode; and
the color conversion layer is formed in the recessed parts. Here, a
refractive index of the color conversion layer is desirably equal
to or more than a refractive index of the barrier layer. Also, the
sealing substrate may further comprise a color filter.
[0018] In the organic EL display of the present invention, the
separation wall may have a plurality of openings respectively
corresponding to the partial electrodes that constitute the
reflective electrode; and the organic EL layer may be formed in the
plurality of openings. Here, the organic EL display may further
comprise auxiliary wiring for the transparent electrode, wherein
the auxiliary wiring may be connected to the transparent electrode
in an area where the organic EL layer is not formed by the
separation wall. Alternatively, the separation wall may be formed
of a metallic material; and the transparent electrode may be
electrically connected to the separation wall.
[0019] Further, in the organic EL display of the present invention,
the separation wall may be constituted of a plurality of striped
parts that are arranged in gaps between the plurality of partial
electrodes constituting the reflective electrode and extend in one
direction; and the organic EL layer may be formed in a gap of the
separation wall. Here, the transparent electrode may be constituted
of a plurality of striped parts that are separated by the
separation wall. In the case where the transparent electrode is
constituted of the plurality of striped parts, for each of the
plurality of striped parts of the transparent electrode, applied
voltage can be individually controlled or an electrical
characteristic can be measured.
[0020] The organic EL display of the present invention can achieve
significant improvement of color conversion efficiency. This
working effect arises from the facts that (a) in the present
invention, formation of the color conversion layer on the barrier
layer of the organic EL element substrate to discreate a distance
between the barrier layer and the color conversion layer
corresponds to making all of light exited from the barrier layer
reach a surface of the color conversion layer of an intended sub
pixel in the conventional structure, and that (b) the absence of a
low refractive index layer between the barrier layer and the color
conversion layer, i.e., in a path from the light emitting layer to
the color conversion layer reduces reflection losses at interfaces
between the respective layers.
[0021] Also, in the organic EL display of the present invention,
growth of a defect referred to as a dark area or dark spot is
hardly recognized. It is thought that this effect arises from the
fact that the separation wall is formed before the formation of the
organic EL layer in the present invention, which is distinct from
the conventional organic EL element substrate in which the
separation wall is formed after the formation of the organic EL
layer. This is because formation of the separation wall before
forming the organic EL layer make it possible to sufficiently carry
out a heating process as countermeasures against outgas from the
separation wall. Further, another factor of this effect is that the
organic EL layer is divided into the plurality of parts in the
organic EL display of the present invention. Thereby, the defect
referred to as the dark area or dark spot does not propagate
throughout the display area, even if outgas (such as moisture)
penetrates into the organic EL layer on the basis of the
transmission from the separation wall.
[0022] Further, in the organic EL display of the present invention,
no bonding gap is present in a light path from the organic EL layer
to the color conversion layer, and therefore a conventional
material such as a typical adhesive can be used as a material to be
filled at the time of bonding. To increase the number of options
for the filling material enables a manufacturing method to be
simplified and/or manufacturing cost to be reduced due to a
reduction in material cost. Also, in the organic EL display of the
present invention, without newly forming the separation wall, it is
possible to form a structure (such as the auxiliary wiring or
transparent electrode separated wiring), in which a separation wall
on the organic EL element substrate side is necessary to
manufacture. Even if such a structure is formed, the color
conversion layer can be formed by an application method. This is
also advantageous to reduction of the manufacturing cost of the
organic EL display.
[0023] In addition, in the organic EL display of the present
invention, the bonded parts, in which the organic EL element
substrate is adhered with the sealing substrate without
interposition of the organic EL layer, are present throughout a
whole of the display area, and therefore mechanical strength of the
bonding is increased to improve mechanical reliability. Besides,
acquisition of the mechanical strength in the display area leads to
a possibility of production of a display having an extremely narrow
circumferential frame in future, by eliminating necessity of an
outer circumferential seal part.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a top view illustrating an organic EL display of
the present invention;
[0025] FIG. 2A is a view illustrating a cross section of the
organic EL display according to a first embodiment of the present
invention, which is cut along a section line IIA-IIA;
[0026] FIG. 2B is a view illustrating a cross section of the
organic EL display according to the first embodiment of the present
invention, which is cut along a section line IIB-IIB;
[0027] FIG. 3A is a cross-sectional view illustrating an organic EL
display according to a second embodiment of the present
invention;
[0028] FIG. 3B is cross-sectional view illustrating the organic EL
display according to the second embodiment of the present
invention;
[0029] FIG. 4A is a cross-sectional view illustrating an organic EL
display according to a third embodiment of the present invention;
and
[0030] FIG. 4B is cross-sectional view illustrating the organic EL
display according to the third embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] FIG. 1 is a top view of a sealing substrate 210 side of an
organic EL display of the present invention. FIG. 1 illustrates an
embodiment in which a black matrix 220 and three types of color
filters 230 are formed on the sealing substrate 210. The organic EL
display illustrated in FIG. 1 has three types of sub pixels
indicated by red color filters 230R, green color filters 230G, and
blue color filters 230B, in which spacers 240 are arranged so as to
be adjacent to two green sub pixels and two blue sub pixels.
[0032] Cross-sectional views of the organic EL display according to
a first embodiment of the present invention are illustrated in
FIGS. 2A and 2B. FIG. 2A is the cross-sectional view along a
section line IIA-IIA illustrated in FIG. 1, and FIG. 2B is the
cross-sectional view along a section line IIB-IIB illustrated in
FIG. 1.
[0033] On a TFT substrate 110, a patterned electrically conductive
layer 121 and an insulating layer 122 are formed to form drive
circuit wiring. As illustrated in FIG. 2B, the drive circuit wiring
is covered by a protective layer 123 except for contact holes for
connecting the electrically conductive layer 121 with a reflective
electrode 142. Then, a planarizing layer 131 is formed so as to
cover the protective layer 123, and an upper surface of the
planarizing layer 131 is planarized. At this time, the contact
holes for connecting the electrically conductive layer 121 with the
reflective electrode 142 are also formed in the planarizing layer
131 as illustrated in FIG. 2B. The planarizing layer 131 is formed
from any resin material known in the art, and the contact holes can
be formed by patterning based on a photolithography method.
Subsequently, an inorganic passivation layer 132 for blocking
outgas from the planarizing layer 131 is formed. As illustrated in
FIG. 2B, the contact holes for connecting the electrically
conductive layer 121 with the reflective electrode 142 are also
formed in the inorganic passivation layer 132. The inorganic
passivation layer 132 is desirably formed so as to completely cover
a side surface of the planarizing layer 131 in each of the contact
holes. As described above, the electrically conductive layer 121 is
electrically connected to the reflective electrode 142 through the
contact holes that are formed in the protective layer 123,
planarizing layer 131, and inorganic passivation layer 132 with
being registered.
[0034] Then, an underlying layer 141 for the reflective electrode
is formed from electrically conductive oxide such as IZO or ITO.
The underlying layer 141 is a layer provided as needed. However, in
order to ensure adhesiveness between the reflective electrode 142
and the inorganic passivation layer 132, it is desirable to provide
the underlying layer 141. In the case where the underlying layer
141 is present, the underlying layer 141 is connected to the
electrically conductive layer 121 (parts of TFT elements) on bottom
surfaces of the contact holes provided through the protective layer
123, planarizing layer 131, and inorganic passivation layer 132.
Subsequently, the reflective electrode 142 is formed on the
underlying layer 141. The reflective electrode 142 may be a single
layer film made of a high reflectance metallic material such as
MoCr, CrB, Ag, Ag alloy, or Al alloy, or a stacked film of the high
reflectance metallic material and a transparent conductive oxide
material such as IZO or ITO. The transparent conductive oxide
material is effective in protection of the high reflectance
metallic material and in adjustment of an optical distance in the
resultant organic EL display. In the case where the underlying
layer 141 is absent, the reflective electrode 142 is directly
connected to the electrically conductive layer 121 (parts of the
TFT elements) on the bottom surfaces of the contact holes.
[0035] In the present invention, the underlying layer 141 is
divided into a plurality of parts, and each of the parts is formed
in a location corresponding to a light emitting part (sub pixel in
the configuration illustrated in FIGS. 1 to 2B). Accordingly, the
reflective electrode 142 is also constituted of a plurality of
partial electrodes that are formed in locations corresponding to
light emitting parts.
[0036] Subsequently, an insulating film 143a is formed so as to
cover shoulder parts of the partial electrodes which constitute the
reflective electrode 142. The insulating film 143a is formed of an
inorganic material, or an organic material (such as polyimide) that
can be sufficiently degassed or dehydrated. FIGS. 2A and 2B
illustrate a configuration in which the insulating film 143a is
covered by an insulating film barrier layer 143b that may be
provided optionally. The insulating film barrier layer 143b is
desirably formed from an inorganic material. The insulating film
barrier layer 143b is effective in preventing outgas such as
moisture from penetrating from the insulating film 143a into an
organic EL layer 160 or the like, especially in the case where the
insulating film 143a is formed from the organic material.
[0037] Subsequently, a separation wall 150 is formed on the
insulating film 143a and insulating film barrier layer 143b. In the
present embodiment, the separation wall 150 is constituted of: a
plurality of striped parts extending in a longitudinal direction
(direction of the section line IIB-IIB); and a plurality of striped
parts extending in a transverse direction (direction of the section
line IIA-IIA) orthogonal to the first direction, and the separation
wall 150 has a plurality of openings. In the respective openings of
the separation wall 150, the partial electrodes constituting the
reflective electrode 142 are exposed. The separation wall 150
desirably has a height of 3 to 7 .mu.m from a surface of the
reflective electrode 142, since the separation wall 150 will be
also used as a bank at the time of forming a color conversion layer
190 later.
[0038] The separation wall 150 may be formed from any of organic
and inorganic materials. Here, it is desirable to use an organic
material, from the perspective of easily increasing a film
thickness and being able to suppress manufacturing cost. In the
case of using an organic material, it is necessary to sufficiently
remove moisture contained in the material through a baking
operation or the like, to suppress outgas from being generated as
much as possible. Also, in the case of using an organic material,
the separation wall 150 desirably has a reverse tapered cross
section, in order to divide the organic EL layer 160 formed by a
vapor deposition method into a plurality of parts.
[0039] Inorganic materials that can be used to form the separation
wall 150 include metal. In the case of using metal to form the
separation wall 150, the separation wall 150 can be formed by a
plating method or the like, in order to ensure the height from the
surface of the reflective electrode 142. As described in Japanese
Patent Laid-Open No. 2005-93398, the separation wall 150 may have a
cross-sectional shape such as a reverse tapered shape or
rectangular shape, in the case of using metal to form the
separation wall 150 (see Patent literature 3). Metallic materials
that can be used to form the separation wall 150 include Cu, Al,
Ag, Au, Ni, Mo, and Ti. In particular, in the case where the
organic EL display has the light emitting parts having a relatively
small size, the separation wall 150 made of metal functions as
auxiliary wiring of a transparent electrode 170 which will be
formed later. The separation wall 150 made of metal is effective in
suppressing the occurrence of luminance unevenness and the increase
in power consumption, on the basis of a reduction in wiring
resistance of the transparent electrode 170.
[0040] Subsequently, the organic EL layer 160 is deposited on a
stacked body in which the separation wall 150 has been formed. The
organic EL layer 160 at least comprises an organic light emitting
layer, and may further comprise one or more layers for facilitating
injection and/or transport of electrons and/or holes. For each of
layers constituting the organic EL layer 160, any material known in
conventional technique can be used.
[0041] In the case where the separation wall 150 has a reverse
tapered cross-sectional shape, the organic EL layer 160 is formed
on an upper surface of the reflective electrode 142 (including an
upper surface of the insulating film barrier layer 143b around the
reflective electrode 142) and an upper surface of the separation
wall 150. The organic EL layer 160 formed on the upper surface of
the reflective electrode 142 is divided into the plurality of parts
by the separation wall 150. In the present embodiment, the
plurality of parts of the organic EL layer 160 are formed with
corresponding one-to-one to the plurality of partial electrodes
constituting the reflective electrode 142. In other words, the
organic EL layer 160 is formed with being separated for each of the
plurality of light emitting parts (sub pixels). Also, each of the
plurality of parts of the organic EL layer 160 formed on the upper
surface of the reflective electrode 142 is not in contact with any
of side surfaces (walls) of the separation wall 150. By the facts
that the organic EL layer 160 formed on the upper surface of the
reflective electrode 142, which is involved in light emission, is
not in contact with the separation wall 150 and that the
transparent electrode 170 intervenes (described later) between the
organic EL layer 160 and the separation wall 150, moisture from the
separation wall 150 can be blocked from penetrating. Also, even if
moisture penetrates from the separation wall 150, or if moisture
penetrates from outside through a defect present in a barrier layer
180 (described later), the organic EL layer 160 deteriorates only
in a part where moisture penetrates, and the deterioration (i.e.,
area referred to as a dark spot or dark area) does not propagate
throughout the organic EL layer 160, since the organic EL layer 160
is separated into the plurality of parts. Further, even if a defect
is present in the insulating film barrier layer 143b, and outgas
penetrates through the insulating film 143a, the deterioration does
not propagate throughout the organic EL layer 160 as well.
[0042] Subsequently, the transparent electrode 170 is formed on the
organic EL layer 160. The transparent electrode 170 in the present
invention may be transparent or semitransparent. The transparent
electrode 170 can be formed by depositing transparent conductive
oxide such as ITO or IZO by a sputtering method. The transparent
electrode 170 is formed so as to cover an upper surface of the
organic EL layer 160 and the upper and side surfaces of the
separation wall 150. At this time, in order to reduce
sputtering-based damage to the organic EL layer 160, a highly
transparent metal thin film such as MgAg or Au (not illustrated)
may be formed before the deposition of the transparent conductive
oxide. If present, the metal thin film desirably has a film
thickness of a few nm.
[0043] In a circumferential edge part of the display area, the
transparent electrode 170 is connected to a power supply line, GND
wiring, and the like in a contact hole different from the contact
holes for the light emitting parts illustrated in FIG. 2B.
[0044] Then, the barrier layer 180 is formed so as to cover a
structure including and below the transparent electrode 170. The
barrier layer 180 is a layer for preventing moisture and gas from
outside from penetrating into the organic EL layer 160. Meanwhile,
the barrier layer 180 desirably has high transmittance, because it
is present on a path through which emitted light of the organic EL
layer 160 is transmitted. Also, the barrier layer 180 desirably has
a high refractive index equivalent to that of the transparent
electrode 170, from the perspective of preventing reflection at an
interface between the barrier layer 180 and the transparent
electrode 170 or color conversion layer 190 in order to improve
transmission efficiency of the emitted light of the organic EL
layer 160. A single layer film of SiN or SiON or a multi-layered
film of SiN and SiON can be used as the barrier layer 180. A
sputtering method, CVD method, or the like can be used to form the
barrier layer 180. In order to pursue better coverage, the barrier
layer 180 is desirably formed by the CVD method. Thereby, the
barrier layer 180 that has recessed parts in gaps between the parts
of the separation wall 150 (i.e. positions corresponding to the
partial electrodes of the reflective electrode 142) is formed.
[0045] Then, the color conversion layer 190 constituted of a
plurality of parts is formed in the recessed parts of the barrier
layer 180 which are formed on the basis of the height of the
separation wall 150. In other words, the separation wall 150 is
used as the bank to form the color conversion layer 190 constituted
of the plurality of parts. FIG. 2A illustrates an embodiment where
two kinds of color conversion layers 190 consisting of red color
conversion layers 190R and green color conversion layers 190G are
formed The color conversion layer 190 can be formed by an
application method in a broad sense, such as an inkjet method,
dispenser method, or printing method. The color conversion layer
190 desirably has a refractive index equal to or more than that of
the barrier layer 180. If the color conversion layer 190 has such a
refractive index, reflection at an interface between the barrier
layer 180 and the color conversion layer 190 can be prevented to
improve incident efficiency of the emitted light of the organic EL
layer 160 into the color conversion layer 190.
[0046] In order to prevent the color conversion layer 190 from
being deteriorated and also a color converting material from being
eluted into filler when the filler is enclosed in a bonding gap, a
protective layer (not illustrated) may be further provided on the
color conversion layer 190. The protective layer can be formed from
an inorganic material or resin.
[0047] The organic EL display of the present embodiment is obtained
by bonding the sealing substrate 210 to the organic EL element
substrate formed as described above. The sealing substrate 210 may
be a plate-like member made of a transparent material, or a
substrate in which the color filters 230 and/or black matrix 220
are formed on the plate-like member. FIGS. 2A and 2B illustrate the
embodiment where the black matrix 220 and the color filters 230
including the red color filter 230R, green color filter 230C, and
blue color filter 230B are provided on the sealing substrate 210.
The sealing substrate 210 can be formed from a transparent material
such as glass. The black matrix 220 and color filters 230 can be
formed from commercially available materials for flat panel
display.
[0048] In the case of forming the black matrix 220, the black
matrix 220 is formed so as to have openings in locations
corresponding to the light emitting parts (locations corresponding
to the sub pixels, the partial electrodes of the reflective
electrodes 142, or the like) of the organic EL element substrate.
In the case of forming the color filters 230, the color filters 230
are formed in locations corresponding to desired light emitting
parts (sub pixels) of the organic EL element substrate. In the case
of forming both of the black matrix 220 and the color filters 230,
it is desirable to form the black matrix 220 first and then form
the color filters 230. In this case, circumferential parts of the
color filters 230 may overlap the black matrix 220.
[0049] When the organic EL element substrate and the sealing
substrate 210 are bonded together, the spacers 240 may be formed on
any of the substrates. In the case of forming the spacers 240 on
the organic EL element substrate, it is convenient to form the
spacers 240 on the barrier layer 180 that has been formed on the
separation wall 150. In this case, it is not necessary to provide
the spacers 240 on the whole of the separation wall 150. For
example, as illustrated in FIGS. 1 to 2B, the spacers 240 can be
provided only at the positions adjacent to the two green light
emitting parts (sub pixels) and two blue light emitting parts (sub
pixels), where the striped parts of the separation wall 150
intersect with each other,. On the other hand, in the case of
providing the spacers 240 on the sealing substrate 210, the spacers
240 is preferably provided in locations where the emitted light of
the organic EL layer 160 does not pass through. Also, in the case
of using the sealing substrate 210 provided with the black matrix
220 and/or color filters 230, the spacers 240 maybe provided on the
black matrix 220 or on overlapped parts of the black matrix 220 and
the color filters 230.
[0050] Following the formation of the spacers 240, the organic EL
element substrate and the sealing substrate 210 are bonded
together. As illustrated in FIGS. 2A and 2B, in the case where the
color filters 230 and black matrix 220 are provided on the sealing
substrate 210, the bonding is performed such that the locations of
the light emitting parts of the organic EL element substrate and
the locations of the openings of the black matrix 220 on the
sealing substrate 210 are accurately in registration. The bonding
can be performed by means of a UV curable adhesive that is provided
in a circumferential edge part of the organic EL element substrate
or sealing substrate 210 so as to surround the display area of the
organic EL element substrate. At the time of the bonding, gas
(atmospheric gas at the time of the bonding) may be filled in the
boding gap that is formed between the organic EL element substrate
and the sealing substrate 210. However, liquid or solid having a
refractive index of 1.3 or more is preferably filled into the
bonding gap, in order to prevent the occurrence of an interference
pattern and the reduction of light transmission efficiency due to
reflection at interfaces adjacent to the bonding gap. Further, in
order to increase mechanical strength of the resultant organic EL
display, it is more desirable to fill a liquid adhesive or the like
in the bonding gap at the time of the bonding, and then after the
bonding, cure and solidify it. Methods for filling a liquid
material at the time of the bonding include, for example, a vacuum
dripping bonding method.
[0051] In the organic EL element substrate of the present
embodiment, the organic EL layer 160 having low mechanical strength
is not formed in areas where the separation wall 150 is formed.
Accordingly, in the case where the liquid adhesive is filled in the
bonding gap to perform the bonding, the areas where the separation
wall 150 is formed contribute to improvement of strength of the
adhesion to the sealing substrate 210. Therefore, in the organic EL
display of the present invention, mechanical strength of the
bonding in the display area can be ensured to narrow a
circumferential edge of the display area, which is so-called as a
"frame". The necessity of the UV curable adhesive (so-called an
"outer circumferential seal part") provided in the substrate
circumferential edge part may be eliminated by the above technique,
in future.
[0052] Cross sections of a second embodiment of the organic EL
display of the present invention are illustrated in FIGS. 3A and
3B. The cross sections illustrated in FIGS. 3A and 3B correspond to
those illustrated in FIGS. 2A and 2B, respectively. The present
embodiment has auxiliary wiring 145 that is advantageous to
enlarging a size of the organic EL display. The auxiliary wiring
145 is effective in, suppressing occurrence of luminance unevenness
and increase of power consumption, which are caused by wiring
resistance of the transparent electrode 170. A configuration
including and below an inorganic passivation layer 132 of the
organic EL display in the present embodiment is the same as that in
the first embodiment, and therefore can be formed by the same
method as that described above.
[0053] Subsequently, an underlying layer 144 for the auxiliary
wiring and the auxiliary wiring 145 are formed simultaneously with
the formation of an underlying layer 141 for a reflective electrode
(if it exists) and the reflective electrode 142. That is, the
auxiliary wiring 145 is made of a low resistance metallic material,
and therefore has lower resistance than that of the transparent
electrode 170 made of transparent conductive oxide. Each of the
underlying layer 144 and the auxiliary wiring 145 is constituted of
a plurality of parts. Also, each of the plurality of parts is
formed in a gap between the underlying layer 141 and the reflective
electrode 142 that constitute a light emitting part. The auxiliary
wiring 145 is connected to a power supply line, GND wiring, and the
like in a contact hole different from those for the light emitting
parts illustrated in FIG. 3B.
[0054] Then, an insulating film 143 is formed so as to cover
shoulder parts of partial electrodes that constitute the reflective
electrode 142. In the present embodiment, openings for connecting
the auxiliary wiring 145 with the transparent electrode 170 are
formed in the insulating film 143. The insulating film 143 can be
formed with use of the same material and process as those used for
the insulating film 143a in the first embodiment, except that
patterning is performed to form the openings. Also in the present
embodiment, an insulating film barrier layer may be formed under
the condition that it does not block the openings of the insulating
film 143.
[0055] Subsequently, a separation wall 150 is formed on the
insulating film 143. The separation wall 150 of the present
embodiment has a reverse tapered cross-sectional shape, and are
arranged such that the openings of the insulating film on the
auxiliary wiring 145 are positioned below an upper surface of the
separation wall 150. Such cross-sectional shape and arrangement
enable an after-mentioned organic EL layer 160 to be formed so as
not to block the openings of the insulating film 143.
[0056] Then, the organic EL layer 160 and transparent electrode 170
are formed with use of the same methods and materials as those in
the first embodiment. As in the first embodiment, the organic EL
layer 160 is formed with being separated by the separation wall 150
for each of the plurality of light emitting parts. The transparent
electrode 170 is formed by a sputtering method that exhibits
superior coverage, and therefore formed on the upper and side
surfaces of the separation wall and an upper surface of the organic
EL layer 160, and also the transparent electrode 170 is
electrically connected to the auxiliary wiring 145 below the upper
surface of the separation wall, where the organic EL layer 160 is
not formed. By connecting the transparent electrode 170 to the low
resistive auxiliary wiring 145, wiring resistance of the
transparent electrode 170 can be reduced to suppress occurrence of
luminance unevenness and increase of power consumption.
[0057] The separation wall 150 desirably has a height of about 1.5
to 3 .mu.m, from the perspectives of the separation of the organic
EL layer 160 and the connection of the auxiliary wiring 145 with
the transparent electrode 170. However, as in the first embodiment,
the separation wall 150 desirably has a height of 3 to 7 .mu.m, in
order to also use the separation wall 150 as a bank for separating
a color conversion layer 190.
[0058] A barrier layer 180 and the color conversion layer 190 can
be formed with use of the same materials and methods as those in
the first embodiment. Also, a sealing substrate 210 may have the
same material and configuration (color filters 230, black matrix
220, and the like) as those in the first embodiment. Bonding to the
sealing substrate 210 can also be performed by the same method as
that in the first embodiment.
[0059] The organic EL display of the present embodiment is suitable
for the case where the light emitting parts have a relatively large
size, since an area of each of the light emitting parts is reduced
by the presence of the auxiliary wiring 145. In the case where a
size of each of the light emitting parts is relatively small, it is
effective to form the separation wall 150 made of metal in the
first embodiment, and use the separation wall 150 as the auxiliary
wiring.
[0060] Cross sections of a third embodiment of the organic EL
display of the present invention are illustrated in FIGS. 4A and
4B. The cross sections illustrated in FIGS. 4A and 4B correspond to
the cross sections illustrated in FIGS. 2A and 2B, respectively.
The present embodiment has: an organic EL layer 160 constituted of
a plurality of parts that are separated for each of light emitting
part lines (sub pixel lines); and a transparent electrode 170
constituted of a plurality of partial electrodes that are separated
for each of the light emitting part lines (sub pixel lines). The
transparent electrode 170 constituted of the plurality of partial
electrodes enables various types of control, such as current
measurement for each of the light emitting part lines, and voltage
control for each of the light emitting part lines. A configuration
including and below an insulating film 143 of the organic EL
display in the present embodiment is the same as that in the second
embodiment, and therefore can be formed by the same methods as
those described above. It is noted that FIGS. 4A and 4B illustrate
a configuration in which an insulating film barrier layer is not
provided; however, even in the present embodiment, the insulating
film barrier layer can be formed.
[0061] A separation wall 150 in the present embodiment is
constituted of a plurality of striped parts that extend in one
direction. The striped parts of the separation wall 150 are
respectively arranged in gaps between a plurality of partial
electrodes that constitute a reflective electrode 142. FIGS. 4A and
4B illustrate an embodiment of the separation wall 150 that extends
in a longitudinal direction (direction of the section lines IIB-IIB
in FIG. 1). Except for the above-described point, the separation
wall 150 can be formed with use of the same material and method as
those in the first embodiment.
[0062] Then, the organic EL layer 160 is formed with use of the
same materials and methods as those in the first embodiment. The
organic EL layer 160 is formed on an upper surface of the
reflective electrode 142 and an upper surface of the separation
wall 150, as done in the first embodiment. However, in the present
embodiment, the resultant organic EL layer 160 is constituted of a
plurality of striped parts that are continuous in each of the light
emitting part lines as illustrated in FIG. 4B, differently from
that of the first embodiment illustrated in FIG. 2B.
[0063] Subsequently, the transparent electrode 170 is formed from a
semitransparent metallic material such as MgAg or Au. The
transparent electrode 170 in the present embodiment has a film
thickness of about 10 to 50 nm. To form the transparent electrode
170, a vapor deposition method is used. A metallic material film is
formed on an upper surface of the organic EL layer 160 which is on
the reflective electrode 142 and separation wall 150. In the
present embodiment, the part formed on the upper surface of the
organic EL layer 160 functions as the transparent electrode 170,
and the metallic film 171 formed on the separation wall 150 is
separated from the transparent electrode 170 and does not function
as an electrode. Accordingly, as illustrated in FIG. 4B, the
transparent electrode 170 is constituted of the plurality of
striped partial electrodes that extend in the same direction as
that of the separation wall 150. Each of the plurality of partial
electrodes constituting the transparent electrode 170 is connected
to a power supply line, GND wiring, and the like in a contact hole
different from contact holes for light emitting parts, in a
circumferential edge part of a display area.
[0064] The separation wall 150 desirably has a height of about 1.5
to 3 .mu.m, from the perspective of separating the organic EL layer
160 and transparent electrode 170 into the pluralities of striped
parts. However, as in the first embodiment, the separation wall 150
desirably has a height of 3 to 7 .mu.m, in order to also use the
separation wall 150 as a bank for separating a color conversion
layer 190.
[0065] A barrier layer 180 and the color conversion layer 190 can
be formed with use of the same methods and materials as those in
the first embodiment. Also, a sealing substrate 210 may have the
same materials and configuration (color filters 230, black matrix
220, and the like) as those in the first embodiment. Bonding to the
sealing substrate 210 can also be performed by the same method as
that in the first embodiment.
[0066] In the present embodiment, the transparent electrode 170 is
separated into the plurality of partial electrodes respectively for
the light emitting part lines, and therefore current can be
measured for each of the light emitting part lines. Also, the
organic EL display can be controlled variously, such as voltage
control for each of the light emitting part lines.
EXAMPLES
Example 1
[0067] The present example is an example of the organic EL display
of the first embodiment of the present invention. An organic EL
display in the present example has a nominal size of 3 inches, and
each pixel has a size of 60 .mu.m.times.180 .mu.m.times.RGB. Also,
a color filter substrate was used, in which the black matrix 220
and three types of color filters 230 were formed on the sealing
substrate 210.
[0068] On alkali-free glass having a size of 200 mm.times.200
mm.times.0.7 mm (manufactured by Asahi glass, AN-100), the
electrically conductive layer 121 (including switching elements and
wiring), insulating layer 122, and protective layer 123 for a
plurality of display parts were formed. Then, the planarizing layer
131 was formed on the protective layer 123. The planarizing layer
131 was patterned to form a contact hole for connecting the
electrically conductive layer 121 with the reflective electrode 142
in each of the sub pixels (light emitting parts) by a
photolithography method, wherein the contact hole had a size of 20
.mu.m square.
[0069] Subsequently, an SiO.sub.2 film having a film thickness of
300 nm was formed on a whole surface by a sputtering method. Then,
an opening that is smaller than the bottom surface was formed on a
bottom surface of each of the contact holes by a dry etching
method, to obtain the inorganic passivation layer 132. By the above
operations, the planarizing layer 131 was completely covered by the
inorganic passivation layer 132, and at the same time, the
electrically conductive layer 121 was brought into a state of being
exposed on the bottom surface of each of the contact holes.
[0070] Subsequently, an IZO film having a film thickness of 50 nm
was formed by an RF-planar magnetron sputtering method in Ar
atmosphere. Then, a resist material "OFPR-800" (manufactured by
Tokyo ohka) was applied followed by exposure and development to
form a pattern. The IZO film was wet etched with using the pattern
as a mask, to form the underlying layer 141 constituted of the
plurality of parts separated for the respective sub pixels. Each of
the parts constituting the underlying layer 141 was connected to
the electrically conductive layer 121 through the contact hole
formed in the planarizing layer 131 and inorganic passivation layer
132. Then, an Ag alloy film having a film thickness of 200 nm was
formed by a sputtering method, so as to cover the underlying layer
141, and, then, a similar patterning process was carried out to
form the reflective electrode 142 constituted of the plurality of
parts. Each of the plurality of parts constituting the reflective
electrode 142 was arranged so as not to protrude from the
underlying layer 141.
[0071] Then, a novolac-based photosensitive resin film having a
film thickness of 1 .mu.m was applied by a spin coat method.
Subsequently, patterning of the resin film was performed by a
photolithography method, so as to provide the openings on the
reflective electrode 142, the openings being both longitudinally
and transversely about 2 to 4 .mu.m larger than the size (about 36
.mu.m.times.about 150 .mu.m) of the light emitting parts. Thereby,
the insulating film 143a was formed. The resultant insulating film
143a was baked at about 230.degree. C. to sufficiently discharge
off outgas such as moisture. Then, an SiN film having a film
thickness of 300 nm was formed by a CVD method. The resultant SiN
film was patterned by a dry etching method, to form the openings
having the above-described size of the light emitting part. Then,
the insulating film barrier layer 143b was formed, thereby the
insulating film 143a was completely covered by the insulating film
barrier layer 143b. Besides, the insulating film barrier layer 143b
had openings for providing required electrical connection parts, in
circumferential edge parts of display areas of the plurality of
display parts arrayed on the substrate, in addition to the
above-described openings.
[0072] Then, photosensitive resin (manufactured by Hitachi
chemical, CR-600) was applied and patterned by a photolithography
method to form the separation wall 150 that was constituted of the
plurality of striped parts extending longitudinally and the
plurality of striped parts extending transversely, and had the
openings in the locations corresponding to the respective light
emitting parts. Each of the striped parts of the separation wall
150 had the reverse tapered (reverse trapezoidal shaped) cross
section having an upper bottom of about 10 .mu.m, lower bottom of
about 6 .mu.m, and height of about 5 .mu.m from the electrode
surface. The resultant separation wall 150 was baked at about
220.degree. C. to discharge off outgas such as moisture. By this
operation, the separation wall 150 having a transverse opening
width of about 50 .mu.m with respect to a transverse sub pixel
pitch of 60 .mu.m was obtained. It is noted that the "transverse"
direction in the present example refers to a right-left direction
in FIG. 2A.
[0073] Subsequently, a stacked body wherein the separation wall 150
had been formed was loaded into a resistive heating vapor
deposition device. By a vapor deposition method using a mask having
openings corresponding to the display areas of the plurality of
display parts arrayed on the substrate, the following layers were
formed on the reflective electrode 142 and on the upper surface of
the separation wall 150 in the following order, to obtain the
organic EL layer 160: a buffer layer made of Li and having a film
thickness of a 1.5 nm; an electron transport layer made of
tris(8-hydroxyquinolinato) aluminum (Alq.sub.3) and having a film
thickness of 20 nm; a light emitting layer made of
4,4'-bis(2,2'-diphenylvinyl(biphenyl)) (DPVBi) and having a film
thickness of 30 nm; a hole transport layer made of
4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (.alpha.-NPD) and
having a film thickness of 10 nm; and a hole injection layer made
of copper phthalocyanine (CuPc) and having a film thickness of 100
nm. Further, a damage buffer layer (not illustrated) made of MgAg
and having a film thickness of 5 nm was formed on the organic EL
layer 160. The organic EL layer 160 and damage buffer layer were
separated for each of the light emitting parts by the separation
wall 150, and not in contact with any of side surfaces (walls) of
the separation wall 150.
[0074] Then, without breaking vacuum, the stacked body in which the
damage buffer layer had been formed was moved into a facing type
sputtering device. Through a mask having openings corresponding to
the plurality of display parts arrayed on the substrate, IZO having
a film thickness of 200 nm was deposited to obtain the transparent
electrode 170. The IZO film was formed on the organic EL layer 160
including the upper surface of the separation wall 150 and also on
the side surfaces of the separation wall 150 to provide the
transparent electrode 170 that functioned as an integrated
electrode in each of the display parts. Also, the transparent
electrode 170 was connected to the electrically conductive layer
121 through unillustrated contact holes in the circumferential edge
parts of the display area of the respective display parts. By the
above operations, the organic EL layer 160 in each of the light
emitting parts was surrounded by the reflective electrode 142, and
the underlying inorganic passivation layer 132, insulating film
barrier layer 143b, and transparent electrode 170, all of which
were formed of inorganic materials.
[0075] Then, without breaking vacuum, the stacked body in which the
transparent electrode 170 had been formed was moved into a CVD
device. An SiN film having a film thickness of 2 .mu.m was
deposited by a CVD method, to form the barrier layer 180. The
resultant barrier layer 180 had a refractive index of about
1.8.
[0076] Subsequently, the stacked body in which the barrier layer
180 had been formed was placed in a multi-nozzle type inkjet device
(droplet-landing accuracy of .+-.5 .mu.m) that was located in an
environment of an oxygen concentration of 50 ppm or less and a
moisture concentration of 50 ppm or less. After registration by
means of markers, color converting material ink was applied onto
the barrier layer in banks resulted from the separation wall 150.
The application of the ink was performed under the conditions that
an ink droplet formed into a sphere having a diameter of about 30
.mu.m during flight. Also, in each of the banks, three ink droplets
were applied. After the ink droplets had been applied over a whole
of the substrate, the substrate was heated to 100.degree. C. to dry
the ink. By repeating the above-described ink application and
drying, the red color conversion layer 19OR and green color
conversion layer 190G respectively having film thicknesses of 0.5
.mu.m were formed to obtain the organic EL element substrate. In
this process, a so-called "color mixing" phenomenon, in which ink
flowed into a bank adjacent to a predetermined bank, was not
recognized.
[0077] In the present example, ink for forming the red color
conversion layer 190R was a mixture of 1000 pbw (parts by weight)
of toluene and 50 pbw of a pigment mixture of coumarin 6 and DCM
(molar ratio between coumarin 6 and DCM was 48:2). Further, ink for
forming the green color conversion layer 190G was a mixture of 1000
pbw of toluene and 50 pbw of a pigment mixture of coumarin 6 and
DEQ (molar ratio between coumarin 6 and DEQ was 48:2).
[0078] On the other hand, onto the alkali-free glass (manufactured
by Corning, Eagle 2000) sealing substrate 210 having a size of 200
mm.times.200 mm.times.0.7 mm, CK-7001 (available from Fujifilm
corporation) was applied and patterned by a photolithography method
to form the black matrix 220 having a film thickness of 1 .mu.m in
the display areas of the plurality of display parts. The black
matrix 220 had a structure in which the plurality of openings
having a size of 46 .mu.m.times.160 .mu.m were arrayed in the
longitudinal and transverse directions. Here, a transverse line
width (interval between the openings in the transverse direction)
was set to 14 .mu.m, and a longitudinal line width (interval
between the openings in the longitudinal direction) was set to 20
.mu.m.
[0079] Subsequently, CR-7001, CG-7001, and CB-7001 (all available
from Fuji film corporation) were applied and patterned to form the
red, green, and blue color filters 230R, 230G, and 230B,
respectively, having film thicknesses of 1.5 .mu.m. Each of the
color filters 230 was constituted of the plurality of striped parts
that extend longitudinally.
[0080] Then, photosensitive resin (manufactured by Hitachi
chemical, CR-600) was applied onto the grid points of the black
matrix 220, each of the grid points being adjacent to two openings
of the black matrix 220 into which the green color filter 230G was
provided, and two openings of the black matrix 220 into which the
blue color filter 230B was provided. By the above operation, the
cylindrically shaped spacers 240 having a diameter of 20 .mu.m and
a height of 2 .mu.m were formed, to obtain the color filter
substrate.
[0081] The organic EL element substrate and color filter substrate
obtained in the above-described manner were moved into a bonding
device that was installed in an environment of an oxygen
concentration of 5 ppm or less and a moisture concentration of 5
.mu.ppm or less. The color filter substrate was placed with the
surface, on which the spacers 240 had been formed, facing upward,
and an epoxy-based UV curable adhesive (manufactured by Nagase
chemtex, XNR-5516) is continuously applied by a dispenser onto
outer circumferential parts of areas corresponding to the plurality
of display parts. Then, a thermosetting epoxy adhesive having lower
viscosity was dripped by a mechanical measuring valve (delivery
accuracy of .+-.5% or less) onto central parts of the areas
corresponding to the plurality of display parts.
[0082] Subsequently, the organic EL element substrate was arranged
with the surface, on which the color conversion layer 190 had been
formed, facing downward and opposing against the color filter
substrate coated with the adhesives. The interior of the device was
evacuated to a pressure of about 10 Pa or less, and then the both
substrates were brought close to each other with the both
substrates being kept parallel, until a distance between the
substrates became about 30 .mu.m. In a state where the UV curable
adhesive was in contact with the organic EL element substrate, the
both substrates were registered by an alignment mechanism. Then, a
slight weight was applied to the both substrates while restoring
pressure in the device to atmospheric pressure. At this time, the
thermosetting epoxy adhesive was spread from the central parts of
the areas corresponding to the plurality of display parts toward
circumferential edge parts. Bringing the both substrates close to
each other was stopped when the tops of the spacers came into
contact with the separation wall 150 of the organic EL element
substrate.
[0083] Subsequently, UV irradiation was carried out from the color
filter substrate side through a mask, such that only the UV curable
adhesive was irradiated with UV light and temporarily cured, and
then the temporarily bonded body was removed from the bonding
device. As a result of observing the temporarily bonded body, the
thermosetting epoxy adhesive was spread over the whole areas
corresponding to the respective display parts. Neither bubble
generation in the areas nor protrusion beyond the UV curable
adhesive in the outer circumferences of the areas was not
recognized.
[0084] Subsequently, the temporarily bonded body was divided into
the areas corresponding to the individual display parts, by means
of an automatic glass scriber and a breaking device. The divided
displays were heated at 80.degree. C. for 1 hour in a heating
furnace to cure the thermosetting epoxy adhesive, and then
naturally cooled for 30 minutes. Finally, the barrier layer 180 on
terminal parts for connecting to an external drive circuit and on
IC connecting pads was removed by a dry etching method, to obtain a
plurality of organic EL display.
[0085] The organic EL display obtained as described above in the
present example exhibited improved efficiency by 30%, as compared
with the organic EL display having the conventional structure in
which the color conversion layer was provided on the color filters
of the color filter substrate rather than the organic EL element
substrate, and special resin having a refractive index of 1.7 was
filled in the bonding gap. In the present example, manufacturing
cost was able to be reduced, since the thermosetting epoxy adhesive
used for filling the bonding gap was a general-purpose adhesive.
Further, no remarkable expansion of a defect referred to as a dark
area or dark spot was not recognized, when subjecting the organic
EL display in the present example to a high-temperature shelf test.
Also, no breakage occurred, when subjecting the organic EL display
in the present example to a heat shock test.
Example 2
[0086] The present example is another example of the organic EL
display of the, first embodiment of the present invention. An
organic EL display in the present example has a nominal size of 3
inches, and each pixel has a size of 60 .mu.m.times.180
.mu.m.times.RGB. Also, a color filter substrate, in which the black
matrix 220 and three types of color filters 230 were formed on the
sealing substrate 210, was used.
[0087] First, in the same procedure as that in Example 1, the
layers including and below the inorganic passivation layer 132 were
formed.
[0088] Then, the separation wall 150 made of Cu was formed by a Cu
plating method. The separation wall 150 was constituted of the
plurality of striped parts extending longitudinally and the
plurality of striped parts extending transversely. The separation
wall 150 had the openings in the locations corresponding to the
respective light emitting parts. Further, each of the striped parts
constituting the separation wall 150 had a rectangular
cross-sectional shape having a width of about 10 .mu.m and a
thickness of about 4 .mu.m. A height of the separation wall 150
from the upper surface of the reflective electrode 142 was about 5
.mu.m.
[0089] Subsequently, in the same procedure as that in Example 1,
the organic EL layer 160 was formed. The organic EL layer 160 was
formed on the upper surface of the reflective electrode 142 and the
upper surface of the separation wall 150, but not formed on any of
the side surfaces of the separation wall 150. Then, in the same
procedure as that in Example 1, the transparent electrode 170 was
formed. The transparent electrode 170 was continuously formed on
the upper surface of the organic EL layer and on the side and upper
surfaces of the separation wall 150, and thereby electrically
connected to the separation wall 150 formed of Cu.
[0090] Subsequently, the formation of the barrier layer 180;
formation of the color filter substrate; bonding of the organic EL
element substrate and the color filter substrate; and separation of
the plurality of display parts were carried out in the same
procedures as those in Example 1, to obtain a plurality of organic
EL displays.
[0091] The organic EL display in, the present example also
exhibited the same effect as that of the display in Example 1. It
is considered that the same effect as that in Example 1 was
obtained by the fact that the separation wall 150 was made of
metal, and therefore moisture was not transferred from the
separation wall 150 to the organic EL layer 160 in the present
example, although the organic EL layer 160 was in contact with the
bottom part of the separation wall 150. Furthermore, luminance
unevenness was not noticeable, since the electrically conductive
separation wall 150 made of Cu reduced wiring resistance of the
transparent electrode 170.
Example 3
[0092] The present example is an example of the organic EL display
of the second embodiment of the present invention. An organic EL
display in the present example has a nominal size of 6 inches, and
each pixel has a size of 100 .mu.m.times.300 .mu.m.times.RGB. Also,
a color filter substrate was used, in which the black matrix 220
and three types of color filters 230 were formed on the sealing
substrate 210.
[0093] First, in the same procedure as that in Example 1 except
that the size of each pixel was changed, the layers including and
below the inorganic passivation layer 132 were formed.
Subsequently, an IZO film was formed by a sputtering method and
patterned in the same procedure as that in Example 1, to form the
underlying layer 141 constituted of the plurality of parts
separated for each of the sub pixels, and the underlying layer 144
for auxiliary wiring constituted of the plurality of striped parts
having a width of 16 .mu.m in gaps between transversely adjacent
sub pixels. Each of the striped parts of the underlying layer 144
for auxiliary wiring extended to the outer circumferential part of
the display part along the longitudinally arranged sub pixel line,
and was connected to the power supply line provided in the outer
circumferential part of the display part.
[0094] Then, an Ag alloy film having a film thickness of 200 nm was
formed by a sputtering method so as to cover the underlying layer
141, and patterned by a similar process, to form the reflective
electrode 142 constituted of the plurality of parts and the
auxiliary wiring 145 constituted of the plurality of striped parts.
Each of the plurality of parts constituting the reflective
electrode 142 was arranged so as not to protrude beyond the
underlying layer 141. In the same manner, each of the striped parts
of the auxiliary wiring 145 was arranged so as not to protrude
beyond the underlying layer 144 for auxiliary wiring.
[0095] Then, a polyimide-based photosensitive resin film having a
film thickness of 1 .mu.m was formed by a spin coat method, and
then patterned by a photolithography method, to form the insulating
film 143. The insulating film 143 had the openings having a size of
transversely 60 .mu.m.times.longitudinally 270 .mu.m on the
reflective electrode 142, and the longitudinally extending striped
openings on the auxiliary wiring 145. A stacked body in which the
insulating film 143 had been formed was baked at about 250.degree.
C. to sufficiently discharge off outgas such as moisture.
[0096] Then, photosensitive resin (manufactured by Hitachi
chemical, CR-600) was applied and patterned by a photolithography
method, to form the separation wall 150 constituted of the
plurality of striped parts extending longitudinally and the
plurality of striped parts extending transversely. The separation
wall 150 had the opening in the locations corresponding to the
respective light emitting parts. Each of the striped parts of the
separation wall 150 had a reverse tapered (reverse trapezoidal
shaped) cross section having an upper bottom of about 14 .mu.m,
lower bottom of about 6 .mu.m, and height of about 7 .mu.m from the
electrode surface. Here, the opening parts provided in the
insulating film 143 on the auxiliary wiring 145 were positioned
below the upper surface of the separation wall 150. The resultant
separation wall 150 was baked at about 220.degree. C. to discharge
off outgas such as moisture. By this operation, the separation wall
150 having a transverse opening width of about 86 .mu.m with
respect to a transverse sub pixel pitch of 100 .mu.m was
obtained.
[0097] Subsequently, the organic EL layer 160 was formed by the
same procedure as that in Example 1. The organic EL layer 160 was
separated for each of the light emitting parts by the separation
wall 150, in the same manner as that in Example 1. Further, the
organic EL layer 160 was not in contact with any of the side
surfaces of the separation wall 150, or completely left any of the
openings of the insulating film 143 on the auxiliary wiring 145
unblocked.
[0098] Then, the transparent electrode 170 was formed by the same
procedure as that in Example 1. At this time, the transparent
electrode 170 was formed along the side surfaces of the separation
wall 150, in addition to the upper surface of the organic EL layer
160 and the upper surface of the separation wall 150. Thereby, the
transparent electrode 170 was connected to the auxiliary wiring 145
through the opening parts of the insulating film 143.
[0099] Subsequently, the formation of the barrier layer 180;
formation of the color filter substrate; bonding of the organic EL
element substrate and the color filter substrate; and separation of
the plurality of display parts were carried out in the same
procedures as those in Example 1, to obtain a plurality of organic
EL displays.
[0100] The organic EL display in the present example also exhibited
the same effect as that of the display in Example 1. Also, even
though the display was enlarged in size, luminance unevenness was
not noticeable, due to reduction of the wiring resistance of the
transparent electrode 170 by the auxiliary wiring 145.
Example 4
[0101] The present example is an example of the organic EL display
of the third embodiment of the present invention. An organic EL
display in the present example has a nominal size of 3 inches, and
each pixel has a size of 60 .mu.m.times.180 .mu.m.times.RGB. Also,
a color filter substrate, in which the black matrix 220 and three
types of color filters 230 were formed on the sealing substrate
210, was used.
[0102] First, the layers including and below the inorganic
passivation layer 132 were formed by the same procedure as that in
Example 1.
[0103] Then, photosensitive resin (manufactured by Hitachi
chemical, CR-600) was applied and patterned by a photolithography
method, to form the separation wall 150 constituted of the
plurality of striped parts that extended longitudinally. The
striped parts of the separation wall 150 were positioned in gaps
between the light emitting part lines that extended longitudinally.
Each of the striped parts of the separation wall 150 had a reverse
tapered (reverse trapezoidal shaped) cross section having an upper
bottom of about 10 .mu.m, lower bottom of about 6 .mu.m, and height
of about 5 .mu.m from the electrode surface. The resultant
separation wall 150 was baked at about 220.degree. C. to discharge
off outgas such as moisture. By this operation, the separation wall
150 having a transverse opening width of about 50 .mu.m with
respect to a transverse sub pixel pitch of 60 .mu.m was
obtained.
[0104] Subsequently, the organic EL layer 160 was formed by the
same procedure as that in Example 1. The organic EL layer 160 was
formed on the upper surface of the reflective electrode 142 and the
upper surface of the separation wall 150, but not formed on any of
the side surfaces of the separation wall 150. The organic EL layer
160 in the present example was constituted of the plurality of
striped parts that extended longitudinally.
[0105] Then, a stacked body, in which the organic EL layer 160 had
been formed, was moved into another chamber of the resistive
heating vapor deposition device to form an MgAg film having a film
thickness of about 30 nm. The MgAg film was positioned on the
organic EL layer 160, and separated into: the transparent electrode
170 consisting of the plurality of striped parts extending
longitudinally; and the MgAg film 171 formed on the separation wall
150.
[0106] Subsequently, the formation of the barrier layer 180;
formation of the color filter substrate; bonding of the organic EL
element substrate and the color filter substrate; and separation of
the plurality of display parts were carried out in the same
procedures as those in Example 1, to obtain a plurality of organic
EL displays.
[0107] The organic EL display in the present example also exhibited
the same effect as that of the display in Example 1.
* * * * *