U.S. patent application number 14/386007 was filed with the patent office on 2015-10-29 for optoelectronic device and method for producing an optoelectronic device.
The applicant listed for this patent is OSRAM Opto Semiconductors GmbH. Invention is credited to Carola Diez, Thomas Dobbertin, Arndt Jaeger, Ulrich Niedermeier, Guenter Schmid, Stefan Seidel.
Application Number | 20150311466 14/386007 |
Document ID | / |
Family ID | 47891702 |
Filed Date | 2015-10-29 |
United States Patent
Application |
20150311466 |
Kind Code |
A1 |
Jaeger; Arndt ; et
al. |
October 29, 2015 |
OPTOELECTRONIC DEVICE AND METHOD FOR PRODUCING AN OPTOELECTRONIC
DEVICE
Abstract
Various embodiments may relate to an optoelectronic device,
including a first organic functional layer structure, a second
organic functional layer structure, and a charge generating layer
structure between the first organic functional layer structure and
the second organic functional layer structure. The charge
generating layer structure includes a first electron-conducting
charge generating layer, a second electron-conducting charge
generating layer, and an interlayer between the first
electron-conducting charge generating layer and the second
electron-conducting charge generating layer. The interlayer
includes at least one phthalocyanine derivative. Various
embodiments may further relate to a method for producing the
optoelectronic device.
Inventors: |
Jaeger; Arndt; (Regensburg,
DE) ; Diez; Carola; (Regensburg, DE) ;
Niedermeier; Ulrich; (Leiblfing, DE) ; Seidel;
Stefan; (Wenzenbach, DE) ; Dobbertin; Thomas;
(Regensburg, DE) ; Schmid; Guenter; (Hemhofen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OSRAM Opto Semiconductors GmbH |
Regensburg |
|
DE |
|
|
Family ID: |
47891702 |
Appl. No.: |
14/386007 |
Filed: |
March 13, 2013 |
PCT Filed: |
March 13, 2013 |
PCT NO: |
PCT/EP2013/055132 |
371 Date: |
September 18, 2014 |
Current U.S.
Class: |
257/40 ;
438/46 |
Current CPC
Class: |
H01L 51/5278 20130101;
H01L 51/5088 20130101; H01L 51/5072 20130101; H01L 51/56 20130101;
H01L 51/0078 20130101; H01L 51/5056 20130101; H01L 51/5092
20130101 |
International
Class: |
H01L 51/50 20060101
H01L051/50; H01L 51/00 20060101 H01L051/00; H01L 51/56 20060101
H01L051/56 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2012 |
DE |
10 2012 204 327.6 |
Claims
1. An optoelectronic device, comprising: a first organic functional
layer structure; a second organic functional layer structure; and a
charge generating layer structure between the first organic
functional layer structure and the second organic functional layer
structure, wherein the charge generating layer structure comprises:
a first electron-conducting charge generating layer; wherein the
first electron-conducting charge generating layer comprises or is
formed from an intrinsically electron-conducting substance; a
second electron-conducting charge generating layer; and an
interlayer between the first electron-conducting charge generating
layer and the second electron-conducting charge generating layer;
and wherein the interlayer comprises at least one phthalocyanine
derivative.
2. The optoelectronic device as claimed in claim 1, wherein the
substance of the first electron-conducting charge generating layer
comprises or is formed from HAT-CN, Cu(I)pFBz, MoO.sub.x, WO.sub.x,
VO.sub.x, ReO.sub.x, F4-TCNQ, NDP-2, NDP-9, bi(III)pFBz or
F16CuPc.
3. The optoelectronic device as claimed in claim 1, wherein the
second organic functional layer structure comprises a hole
transport layer, and wherein the hole transport layer is formed
above or on the first electron-conducting charge generating
layer.
4. The optoelectronic device as claimed in claim 3, wherein the
hole transport layer is formed from an intrinsically
hole-conducting substance or from a substance mixture comprising
matrix and p-type dopant.
5. The optoelectronic device as claimed in any claim 1, wherein the
second electron-conducting charge generating layer comprises or is
formed from an intrinsically electron-conducting substance, or
wherein the second electron-conducting charge generating layer is
formed from a substance mixture comprising matrix and n-type
dopant.
6. The optoelectronic device as claimed in claim 1, wherein the
interlayer comprises or is formed from one substance or a plurality
of substances, selected from a group consisting of inorganic
substance, organic substance, and organic-inorganic hybrid
substance.
7. The optoelectronic device as claimed in claim 1, wherein the
interlayer comprises or is formed from the same substance or the
same substance mixture as the substance or the substance mixture of
the first electron-conducting charge generating layer, wherein
however the substance or the substance mixture has a different
physical structure, or wherein the interlayer comprises or is
formed from the same substance or the same substance mixture as the
substance or the substance mixture of the second
electron-conducting charge generating layer, wherein however the
substance or the substance mixture has a different physical
structure.
8. The optoelectronic device as claimed in claim 1, wherein the at
least one phthalocyanine derivative comprises or consists of at
least one metal phthalocyanine derivative or metal oxide
phthalocyanine derivative or unsubstituted phthalocyanine
derivative.
9. The optoelectronic device as claimed in claim 8, wherein the
phthalocyanine derivative is selected from the group consisting of:
vanadium oxide phthalocyanine (VOPc), titanium oxide phthalocyanine
(TiOPc), copper phthalocyanine (CuPc), unsubstituted phthalocyanine
(H.sub.2Pc), cobalt phthalocyanine (CoPc), aluminum phthalocyanine
(AlPc), nickel phthalocyanine (NiPc), iron phthalocyanine (FePc),
zinc phthalocyanine (ZnPc) or manganese phthalocyanine (MnPC).
10. The optoelectronic device as claimed in claim 1, wherein the
optoelectronic device is designed as an organic light emitting
diode.
11. A method for producing an optoelectronic device, the method
comprising: forming a first organic functional layer structure;
forming a charge generating layer structure above or on the first
organic functional layer structure; and forming a second organic
functional layer structure above or on the charge generating layer
structure, wherein forming the charge generating layer structure
comprises: forming a second electron-conducting charge generating
layer; forming an interlayer above or on the second
electron-conducting charge generating layer; wherein the interlayer
comprises at least one phthalocyanine derivative; and forming a
first electron-conducting charge generating layer above or on the
interlayer, wherein the first electron-conducting charge generating
layer comprises or is formed from an intrinsically
electron-conducting substance.
12. The method as claimed in claim 11, wherein the substance of the
first electron-conducting charge generating layer comprises or is
formed from HAT-CN, Cu(1)pFBz, MoO.sub.x, WO.sub.x, VO.sub.x,
ReO.sub.x, F4-TCNQ, NDP-2, NDP-9, bi(III)pFBz or F16CuPc.
13. The method as claimed in claim 11, wherein the at least one
phthalocyanine derivative of the interlayer comprises or consists
of at least one metal phthalocyanine derivative or metal oxide
phthalocyanine derivative or unsubstituted phthalocyanine
derivative.
14. The method as claimed in claim 13, wherein the metal oxide
phthalocyanine of the interlayer is selected from the group
consisting of: vanadium oxide phthalocyanine (VOPc), titanium oxide
phthalocyanine (TiOPc), copper phthalocyanine (CuPc), unsubstituted
phthalocyanine (H.sub.2Pc), cobalt phthalocyanine (CoPc), aluminum
phthalocyanine (AlPc), nickel phthalocyanine (NiPc), iron
phthalocyanine (FePc), zinc phthalocyanine (ZnPc) or manganese
phthalocyanine (MnPC).
15. The method as claimed in claim 11, wherein the optoelectronic
device is produced as an organic light emitting diode.
Description
RELATED APPLICATIONS
[0001] The present application is a national stage entry according
to 35 U.S.C. .sctn.371 of PCT application No.: PCT/EP2013/055132
filed on Mar. 13, 2013, which claims priority from German
application No.: 10 2012 204 327.6 filed on Mar. 19, 2012, and is
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] Various exemplary embodiments relate to an optoelectronic
device and a method for producing an optoelectronic device.
BACKGROUND
[0003] An optoelectronic device (e.g. an organic light emitting
diode (OLED), for example a white organic light emitting diode
(WOLED), a solar cell, etc.) on an organic basis is usually
distinguished by its mechanical flexibility and moderate production
conditions. Compared with a device composed of inorganic materials,
an optoelectronic device on an organic basis may be produced
potentially cost-effectively on account of the possibility of
large-area production methods (e.g. roll-to-roll production
methods).
[0004] A WOLED consists e.g. of an anode and a cathode with a
functional layer system therebetween. The functional layer system
consists of one or a plurality of emitter layer/s, in which the
light is generated, one or a plurality of charge generating layer
structure/s each composed of two or more charge generating layers
(CGL) for generating charges, and one or a plurality of electron
blocking layers, also designated as hole transport layer(s) (HTL),
and one or a plurality of hole blocking layers, also designated as
electron transport layer(s) (ETL), in order to direct the current
flow.
[0005] In the simplest embodiment, the charge generating layer
structure conventionally consists of a p-doped and a n-doped charge
generating layer, which are directly connected to one another, with
the result that illustratively a pn junction is formed. In the pn
junction, a depletion region is formed, in which electrons of the
n-doped charge generating layer migrate into the p-doped charge
generating layer. As a result of a voltage being applied to the pn
junction in the reverse direction, in the depletion region
Wannier-Mott-excitons are generated which may generate
electromagnetic radiation in the emitter layers as a result of
recombination (e.g. visible light).
[0006] An OLED may be produced with good efficiency and lifetime by
means of conductivity doping by the use of a p-i-n
(p-doped-intrinsic-n-doped) junction analogously to the
conventional inorganic LED. In this case, the charge carriers from
the p-doped and respectively n-doped layers are injected in a
specific manner into the intrinsic layer, in which the excitons are
formed.
[0007] By stacking one or a plurality of intrinsic layers one above
another, it is possible to obtain an OLED, with practically the
same efficiency and identical luminance, significantly longer
lifetimes compared with an OLED including only one intrinsic layer.
For the same current density, double to triple the luminance may
thus be realized. For the stacking one above another, charge
generating layers consisting of a highly doped pn junction are
required.
[0008] The p-doped and n-doped charge generating layers may each
consist of one or a plurality of organic and/or inorganic
substance(s) (Matrix). In the production of the charge generating
layer, the respective matrix is usually admixed with one or a
plurality of organic or inorganic substances (dopants) in order to
increase the conductivity of the matrix. This doping may produce
electrons (n-doped; dopants e.g. metals having a low work function,
e.g. Na, Ca, Cs, Li, Mg or compounds thereof e.g. Cs.sub.2CO.sub.3,
Cs.sub.3PO.sub.4, or organic dopants from the company NOVALED, e.g.
NDN-1, NDN-26) or holes (p-doped; dopant e.g. transition metal
oxides, e.g. MoO.sub.x, WO.sub.x, VO.sub.x, organic compounds, e.g.
Cu(I)pFBz, F4-TCNQ, or organic dopants from the company NOVALED,
e.g. NDP-2, NDP-9) as charge carriers in the matrix.
[0009] In the context of this description, an organic substance may
be understood to mean a carbon compound which, regardless of the
respective state of matter, is present in chemically uniform form
and is characterized by characteristic physical and chemical
properties. Furthermore, in the context of this description, an
inorganic substance can be understood to mean a compound which,
regardless of the respective state of matter, is present in
chemically uniform form and is characterized by characteristic
physical and chemical properties, without carbon or a simple carbon
compound. In the context of this description, an organic-inorganic
substance (hybrid substance) can be understood to mean a compound
which, regardless of the respective state of matter, is present in
chemically uniform form and is characterized by characteristic
physical and chemical properties, including compound portions which
contain carbon and are free of carbon. In the context of this
description, the term "substance" encompasses all abovementioned
substances, for example an organic substance, an inorganic
substance, and/or a hybrid substance. Furthermore, in the context
of this description, a substance mixture can be understood to mean
something which has constituents consisting of two or more
different substances, the constituents of which are very finely
dispersed, for example.
[0010] The use of a CGL in an optoelectronic device presupposes a
simple construction, i.e. as few layers as possible, which are as
easy as possible to produce. Furthermore, a small voltage drop
across the CGL and a high transmission of the CGL layers are
necessary, i.e. low absorption losses in the spectral range of the
electromagnetic radiation emitted by the OLED.
[0011] Different to inorganic layers in semiconductor devices at
high temperatures molecules of the organic layers may diffuse into
other organic layers (partial layer interdiffusion), e.g. parts of
the n-doped charge generating layer into the p-doped charge
generating layer of a charge generating layer structure in an OLED.
When an electric field is applied to the charge generating layer
structure, a voltage drop across this layer structure by means of
the layer interdiffusion is measurable. Said voltage drop increases
with the operating period, since the diffusion of conductive
organic substances is directed in an electric field. This limits
the time of the operating period of organic optoelectronic
devices.
[0012] In order to suppress the partial layer interdiffusion
(barrier effect), a diffusion barrier layer may be inserted between
the individual organic layers, e.g. between the p-doped and n-noped
charge generating layer. However, the diffusion barrier layer
constitutes an optoelectronic resistance in the charge generating
layer structure and may reduce the efficiency of the optoelectronic
device. The optoelectronic resistance of a layer, in various
embodiments, may be understood to mean an absorption of
electromagnetic radiation, for example visible light, in the layer
and an electrical resistance, for example as a result of a voltage
drop across said layer.
SUMMARY
[0013] In various embodiments, an optoelectronic device and a
method for producing it are provided, with a hole-conducting charge
generating layer and a diffusion barrier layer having a lower
optoelectronic resistance.
[0014] In various embodiments, an optoelectronic device is provided
including: a first organic functional layer structure; a second
organic functional layer structure; and a charge generating layer
structure between the first organic functional layer structure and
the second organic functional layer structure, wherein the charge
generating layer structure includes: a hole-conducting charge
generating layer; an electron-conducting charge generating layer
and a diffusion barrier layer between hole-conducting charge
generating layer and electron-conducting charge generating layer;
wherein the diffusion barrier layer includes at least one
phthalocyanine derivative.
[0015] In one embodiment, the hole-conducting charge generating
layer may include or be formed from an intrinsically
hole-conducting substance.
[0016] In another embodiment, the substance of the intrinsically
hole-conducting charge generating layer may include or be formed
from HAT-CN.
[0017] In another embodiment, the substance of the intrinsically
hole-conducting charge generating layer may include or be formed
from of at least one of F16CuPc or LG-101.
[0018] In another embodiment, the hole-conducting charge generating
layer may be formed from a substance mixture composed of matrix and
p-dopant.
[0019] The dopant of the hole-conducting charge generating layer
may be a substance selected from the group of substances consisting
of MoO.sub.x, WO.sub.x, VO.sub.x, Cu(I)pFBz, F4-TCNQ, NDP-2, NDP-9,
or similiar.
[0020] In another embodiment, the substance of the hole-conducting
charge generating layer may have a transmission greater than about
90% in a wavelength range from about 450 nm to about 600 nm.
[0021] In another embodiment, the hole-conducting charge generating
layer may have a layer thickness in a range of approximately 1 nm
to approximately 500 nm.
[0022] In another embodiment, the electron-conducting charge
generating layer may include or be formed from an intrinsically
electron-conducting substance.
[0023] In another embodiment, the intrinsically electron-conducting
charge generating layer may include or be formed from a substance
from the group of the substances: NDN-1, NDN-26, MgAg, or
similar.
[0024] In another embodiment, the electron-conducting charge
generating layer may be formed from a substance mixture composed of
matrix and n-type dopant.
[0025] In another embodiment, the matrix of the electron-conducting
charge generating layer may be a substance selected from the group
of substances consisting of: NET-18, or similiar.
[0026] In another embodiment, the dopant of the electron-conducting
charge generating layer may be a substance selected from the group
of substances consisting of: NDN-1, NDN-26, Na, Ca, Cs, Li, Mg,
Cs.sub.2CO.sub.3, Cs.sub.3PO.sub.4, or similiar.
[0027] In another embodiment, the electron-conducting charge
generating layer may have a layer thickness in a range of
approximately 1 nm to approximately 500 nm.
[0028] In another embodiment, the valence band of the substance or
substance mixture of the electron-conducting charge generating
layer may be higher than the conductance band of the substance or
substance mixture of the hole-conducting charge generating
layer.
[0029] In another embodiment, the diffusion barrier layer may
include or be formed from an inorganic substance.
[0030] In another embodiment, the diffusion barrier layer may
include or be formed from an organic substance.
[0031] In another embodiment, the diffusion barrier layer may be
formed from an organic-inorganic hybrid substance.
[0032] In another embodiment, the diffusion barrier layer may
include a substance mixture composed of two or more substances,
wherein the substances are selected from a group consisting of an
inorganic substance, an organic substance and an organic-inorganic
hybrid substance.
[0033] In another embodiment, the diffusion barrier layer may
include the same substance or the same substance mixture as the
substance or the substance mixture of the hole-conducting charge
generating layer, wherein however the substance or the substance
mixture may have a different physical structure.
[0034] In another embodiment, the diffusion barrier layer may
include the same substance or the same substance mixture as the
substance or the substance mixture of the electron-conducting
charge generating layer, wherein however the substance or the
substance mixture may have a different physical structure in the
diffusion barrier layer than in the electron-conducting charge
generating layer.
[0035] In another embodiment, the physical structure may include at
least one other parameter of the following parameters: the density
of the substance or of the substance mixture; the crystallinity of
the substance or of the substance mixture; the crystal orientation
of the substance or of the substance mixture; and/or the local
doping density of the substance or of the substance mixture.
[0036] In another embodiment, the diffusion barrier layer may have
a heterogeneous layer cross section.
[0037] In another embodiment, the heterogeneous layer cross section
may include or be formed from regions of different crystallinity of
the substance or of the substance mixture.
[0038] The different heterogeneous regions may be partial or
complete crystallizations in an amorphous portion of the substance
or of the substance mixture of the diffusion barrier layer.
[0039] In another embodiment, the heterogeneous layer cross section
may include or be formed regions of different crystal orientation
of the substance or of the substance mixture.
[0040] The barrier effect of the diffusion barrier layer may be
increased by an at least local orientation of the molecules of the
diffusion barrier layer, for example if the longest crystal axis of
the crystallized regions is oriented parallel to at least one
interface of the p-doped and n-doped charge generating layers
connected by the diffusion barrier layer.
[0041] In another embodiment, the longest crystal axis of the
crystallized substance or of the crystallized substance mixture of
the diffusion barrier layer may be oriented parallel to the
interface of the diffusion barrier layer with the
electron-conducting charge generating layer.
[0042] In another embodiment, the longest crystal axis of the
crystallized substance or of the crystallized substance mixture of
the diffusion barrier layer may be oriented parallel to the
interface of the diffusion barrier layer with the hole-conducting
charge generating layer.
[0043] In another embodiment, the heterogeneous layer cross section
of the diffusion barrier layer may include two or more layers each
composed of a substance of the substance mixture of the diffusion
barrier layer or different physical structures of the substance of
the diffusion barrier layer.
[0044] In another embodiment, the physical layer distinction may
include at least one of the following parameters: the density of
the substance or of the substance mixture; the crystallinity of the
substance or of the substance mixture; the crystal orientation of
the substance or of the substance mixture; and/or the local doping
density of the substance or of the substance mixture.
[0045] In another embodiment, the diffusion barrier layer may have
a layer thickness of approximately 1 nm to approximately 200
nm.
[0046] In another embodiment, the common interface of the diffusion
barrier layer with the hole-conducting charge generating layer may
have plane-parallelism with respect to the common interface of the
diffusion barrier layer with the electron-conducting charge
generating layer.
[0047] In another embodiment, the diffusion barrier layer may be
formed from an electrically insulating substance or substance
mixture and the valence band of the diffusion barrier layer may be
energetically above the conduction band of the physically connected
hole-conducting charge generating layer and above the valence band
of the physically connected electron-conducting charge generating
layer, i.e. the charge carrier conduction takes place by means of a
tunneling current.
[0048] In another embodiment, the diffusion barrier layer should
influence the optoelectronic efficiency of the optoelectronic
device by up to a maximum of approximately 10% in a wavelength
range of approximately 450 nm to approximately 600 nm.
[0049] In another embodiment, the diffusion barrier layer may have
a transmission of greater than approximately 90% in the wavelength
range of approximately 450 nm to approximately 600 nm.
[0050] In another embodiment, the layer cross section of the
diffusion barrier layer may be structurally stable up to a
temperature of up to approximately 120.degree. C.
[0051] In another embodiment, the at least one phthalocyanine
derivative may include or consist of at least one metal oxide
phthalocyanine derivative.
[0052] In another embodiment, the metal oxide phthalocyanine, may
be selected from the group of phthalocyanines consisting of: VOPc,
TiOPc, CuOPc.
[0053] In another embodiment, the optoelectronic device may be
designed as an organic light emitting diode.
[0054] In various aspects, a method for producing an optoelectronic
device is provided, wherein the method includes: forming a first
organic functional layer structure, forming a charge generating
layer structure above or on the first organic functional layer
structure, and forming a second organic functional layer structure
above or on the charge generating layer structure, wherein forming
the charge generating layer structure includes: forming a
electron-conducting charge generating layer, forming an diffusion
barrier layer above or on the electron-conducting charge generating
layer, wherein the diffusion barrier layer includes at least one
phthalocyanine derivative, and forming a hole-conducting charge
generating layer above or on the diffusion barrier layer.
[0055] In another embodiment, the hole-conducting charge generating
layer may be formed from an intrinsically hole-conducting
substance.
[0056] In another embodiment, the substance of the intrinsically
hole-conducting charge generating layer may include or be formed
from HAT-CN.
[0057] In another embodiment, the substance of the intrinsically
hole-conducting charge generating layer may include or be formed
from at least one of F16CuPc or LG-101.
[0058] In another embodiment, the hole-conducting charge generating
layer may be formed from a substance mixture composed of matrix and
p-type dopant.
[0059] In another embodiment, the dopant of the hole-conducting
charge generating layer may include a substance from the group of
substances consisting of MoO.sub.x, WO.sub.x, VO.sub.x, Cu(I)pFBz,
F4-TCNQ, NDP-2, NDP-9, or similiar.
[0060] In another embodiment, the substance of the hole-conducting
charge generating layer may have a transmission of greater than
approximately 90% in a wavelength range of approximately 450 nm to
approximately 600 nm.
[0061] In another embodiment, the hole-conducting charge generating
layer may be formed with a layer thickness in a range of
approximately 1 nm to approximately 500 nm.
[0062] In another embodiment, the electron-conducting charge
generating layer may include or be formed from an intrinsically
electron-conducting substance.
[0063] In another embodiment, the substance of the intrinsically
electron-conducting charge generating layer may be a substance from
the group of substances consisting of: NDN-1, NDN-26, MgAg, or
similiar.
[0064] In another embodiment, the electron-conducting charge
generating layer may be formed from a substance mixture composed of
matrix and n-type dopant.
[0065] In another embodiment, the matrix of the electron-conducting
charge generating layer may be a substance from the group of
substances consisting of: NET-18, or similiar.
[0066] In another embodiment, the dopant of the electron-conducting
charge generating layer may be a substance from the group of
substances consisting of: NDN-1, NDN-26, Na, Ca, Cs, Li, Mg,
Cs2CO3, Cs3PO4, or similar.
[0067] In another embodiment, the electron-conducting charge
generating layer may be formed with a layer thickness in a range of
approximately 1 nm to approximately 500 nm.
[0068] In another embodiment, the valence band of the substance or
substance mixture of the electron-conducting charge generating
layer is energetically higher than the conduction band of the
substance or substance mixture of the hole-conducting charge
generating layer.
[0069] In another embodiment, the diffusion barrier layer may
include or be formed from an inorganic substance.
[0070] In another embodiment, the diffusion barrier layer may
include or be formed from an organic substance.
[0071] In another embodiment, the diffusion barrier layer may
include or be formed from an organic-inorganic hybrid
substance.
[0072] In another embodiment, the diffusion barrier layer may
include or be formed from a substance mixture composed of two or
more substances, wherein the substances may be selected from the
group consisting of: an inorganic substance, an organic substance
and an organic-inorganic hybrid substance.
[0073] In another embodiment, the diffusion barrier layer may
include or may be formed from the same substance or the same
substance mixture as the substance or the substance mixture of the
hole-conducting charge generating layer, wherein however the
substance or the substance mixture has a different physical
structure.
[0074] In another embodiment, the diffusion barrier layer may
include or be formed from the same substance or the same substance
mixture as the substance or the substance mixture of the
electron-conducting charge generating layer, wherein however the
substance or the substance mixture has a different physical
structure.
[0075] In another embodiment, the physical structure of the
diffusion barrier layer may include at least one other parameter of
the following parameters: the density of the substance or of the
substance mixture; the crystallinity of the substance or of the
substance mixture; the crystal orientation of the substance or of
the substance mixture; and/or the local doping density of the
substance or of the substance mixture.
[0076] In another embodiment, the diffusion barrier layer may be
formed having a heterogeneous layer cross section.
[0077] In another embodiment, the heterogeneous layer cross section
may include or be formed by regions of different crystallinity of
the substance or of the substance mixture.
[0078] In another embodiment, the heterogeneous layer cross section
may include or may be formed by regions of different crystal
orientation of the substance or substance mixture.
[0079] In another embodiment, at least one of the crystallinity or
the crystal orientation of the substance of the diffusion barrier
layer may be set by means of process parameters.
[0080] In another embodiment, the process parameters may include at
least one of the following parameters: presence and alignment of
electromagnetic fields; formation of nucleation nuclei on the
electron-conducting layer before the formation of the diffusion
barrier layer.
[0081] In another embodiment, the longest crystal axis of the
crystallized substance or of the crystallized substance mixture of
the diffusion barrier layer may be oriented parallel to the
interface of the diffusion barrier layer with the
electron-conducting charge generating layer.
[0082] In another embodiment, the longest crystal axis of the
crystallized substance or substance mixture of the diffusion
barrier layer may be oriented parallel to the interface of the
diffusion barrier layer with the hole-conducting charge generating
layer.
[0083] In another embodiment, the heterogeneous layer cross section
of the diffusion barrier layer may include two or more layers each
composed of a substance of the substance mixture of the diffusion
barrier layer or different physical structures of the substance of
the diffusion barrier layer.
[0084] In another embodiment, the distinctive physical structure
may include at least one of the following parameters: the density
of the substance or of the substance mixture; the crystallinity of
the substance or of the substance mixture; the crystal orientation
of the substance or of the substance mixture; or the local doping
density of the substance or of the substance mixture.
[0085] In another embodiment, the diffusion barrier layer may be
formed with a layer thickness of approximately 1 nm to
approximately 200 nm.
[0086] In another embodiment, the common interface of the diffusion
barrier layer with the hole-conducting charge generating layer may
have plane-parallelism with respect to the common interface of the
diffusion barrier layer with the electron-conducting charge
generating layer.
[0087] In another embodiment, the diffusion barrier layer may be
formed from an electrically insulating substance or substance
mixture and the valence band of the diffusion barrier layer may be
energetically above the conduction band of the physically connected
hole-conducting charge generating layer and above the valence band
of the physically connected electron-conducting charge generating
layer.
[0088] In another embodiment, the diffusion barrier layer may
influence the optoelectronic efficiency of the optoelectronic
device by up to a maximum of approximately 10% in a wavelength
range of approximately 450 nm to approximately 600 nm.
[0089] In another embodiment, the diffusion barrier layer may have
a transmission of greater than approximately 90% in the wavelength
range of approximately 450 nm to approximately 600 nm.
[0090] In another embodiment, the diffusion barrier layer may be
formed such that the layer cross section of the diffusion barrier
layer is structurally stable up to a temperature of up to
approximately 120.degree. C.
[0091] In another embodiment, the diffusion barrier layer may
include or be formed from at least one metal oxide phthalocyanine
derivative.
[0092] In another embodiment, the diffusion barrier layer may
include or be formed from a metal oxide phthalocyanine from the
group of phthalocyanines consisting of: VOPc, TiOPc, CuOPc.
[0093] In another embodiment, the method may furthermore include:
forming an electron conductor layer; forming the
electron-conducting charge generating layer on or above the
electron conductor layer; forming a hole conductor layer on or
above the hole-conducting charge generating layer.
[0094] In another embodiment, the method may furthermore include:
forming a first electrode; forming the first organic functional
layer structure on or above the first electrode; and forming a
second electrode on or above the second organic functional layer
structure.
[0095] In another embodiment, the optoelectronic device may be
produced as an organic light emitting diode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0096] In the drawings, like reference characters generally refer
to the same parts throughout the different views. The drawings are
not necessarily to scale, emphasis instead generally being placed
upon illustrating the principles of the disclosed embodiments. In
the following description, various embodiments described with
reference to the following drawings, in which:
[0097] FIG. 1 shows a cross-sectional view of an optoelectronic
device in accordance with various exemplary embodiments;
[0098] FIG. 2 shows a cross-sectional view of a functional layer
system of an optoelectronic device in accordance with various
exemplary embodiments;
[0099] FIG. 3 shows a cross-sectional view of a charge generating
layer structure of an optoelectronic device in accordance with
various exemplary embodiments;
[0100] FIG. 4 shows a measured optical transmission of a diffusion
barrier layer of a charge generating layer structure in accordance
with a first and second implementation;
[0101] FIG. 5 shows a measured temperature/voltage stability of a
charge generating layer structure in accordance with a first and
second implementation; and
[0102] FIG. 6 shows a measured current-voltage characteristic curve
of a charge generating layer structure in accordance with a first
and second implementation.
DETAILED DESCRIPTION
[0103] In the following detailed description, reference is made to
the accompanying drawings, which form part of this description and
show for illustration purposes specific embodiments in which the
disclosure may be implemented. In this regard, direction
terminology such as, for instance, "at the top", "at the bottom",
"at the front", "at the back", "front", "rear", etc. is used with
respect to the orientation of the figure(s) described. Since device
parts of embodiments may be positioned in a number of different
orientations, the direction terminology serves for illustration and
is not restrictive in any way whatsoever. It goes without saying
that other embodiments may be used and structural or logical
changes may be made, without departing from the scope of protection
of the present disclosure. It goes without saying that the features
of the various exemplary embodiments described herein may be
combined with one another, unless specifically indicated otherwise.
Therefore, the following detailed description should not be
interpreted in a restrictive sense, and the scope of protection of
the present disclosure is defined by the appended claims.
[0104] In the context of this description, the terms "connected"
and "coupled" are used to describe both a direct and an indirect
connection and a direct or indirect coupling. In the figures,
identical or similar elements are provided with identical reference
signs, insofar as this is expedient.
[0105] In various exemplary embodiments, an optoelectronic device
may be formed as a light emitting device, for example as an organic
light emitting diode (OLED) or as an organic light emitting
transistor. In various exemplary embodiments, the optoelectronic
device may be part of an integrated circuit. Furthermore, a
plurality of light emitting devices may be provided, for example in
a manner accommodated in a common housing. In various exemplary
embodiments, the optoelectronic device may also be formed as a
solar cell. Even though the various exemplary embodiments are
described below on the basis of an OLED, these exemplary
embodiments may, however, readily also be applied to the other
optoelectronic devices mentioned above.
[0106] FIG. 1 shows a cross-sectional view of an optoelectronic
device 100 in accordance with various exemplary embodiments.
[0107] The optoelectronic device 100 in the form of a light
emitting device, for example in the form of an organic light
emitting diode 100, may have a substrate 102. The substrate 102 may
serve for example as a carrier element for electronic elements or
layers, for example light emitting elements. By way of example, the
substrate 102 may include or be formed from glass, quartz, and/or a
semiconductor material or any other suitable material. Furthermore,
the substrate 102 may include or be formed from a plastic film or a
laminate including one or including a plurality of plastic films.
The plastic may include or be formed from one or more polyolefins
(for example high or low density polyethylene (PE) or polypropylene
(PP)). Furthermore, the plastic may include or be formed from
polyvinyl chloride (PVC), polystyrene (PS), polyester and/or
polycarbonate (PC), polyethylene terephthalate (PET), polyether
sulfone (PES) and/or polyethylene naphthalate (PEN). The substrate
102 may include one or more of the materials mentioned above. The
substrate 102 may be embodied as translucent or even
transparent.
[0108] In various exemplary embodiments, the term "translucent" or
"translucent layer" may be understood to mean that a layer is
transmissive to light, for example to the light generated by the
light emitting device, for example in one or more wavelength
ranges, for example to light in a wavelength range of visible light
(for example at least in a partial range of the wavelength range of
from 380 nm to 780 nm). By way of example, in various exemplary
embodiments, the term "translucent layer" should be understood to
mean that substantially the entire quantity of light coupled into a
structure (for example a layer) is also coupled out from the
structure (for example layer), wherein part of the light may be
scattered in this case.
[0109] In various exemplary embodiments, the term "transparent" or
"transparent layer" may be understood to mean that a layer is
transmissive to light (for example at least in a partial range of
the wavelength range of from 380 nm to 780 nm), wherein light
coupled into a structure (for example a layer) is also coupled out
from the structure (for example layer) substantially without
scattering or light conversion. Consequently, in various exemplary
embodiments, "transparent" should be regarded as a special case of
"translucent".
[0110] For the case where, for example, a light emitting
monochromatic or emission spectrum-limited electronic device is
intended to be provided, it suffices for the optically translucent
layer structure to be translucent at least in a partial range of
the wavelength range of the desired monochromatic light or for the
limited emission spectrum.
[0111] In various exemplary embodiments, the organic light emitting
diode 100 (or else the light emitting devices in accordance with
the exemplary embodiments that have been described above or will be
described below) may be designed as a so-called top and bottom
emitter. A top and bottom emitter may also be designated as an
optically transparent device, for example a transparent organic
light emitting diode.
[0112] In various exemplary embodiments, a barrier layer (not
illustrated) may optionally be arranged on or above the substrate
102. The barrier layer may include or consist of one or more of the
following materials: aluminum oxide (alumina), zinc oxide,
zirconium oxide, titanium oxide, hafnium oxide, tantalum oxide,
lanthanum oxide, silicon oxide, silicon nitride, silicon
oxynitride, indium tin oxide, indium zinc oxide, aluminum-doped
zinc oxide, and mixtures and alloys thereof. Furthermore, in
various exemplary embodiments, the barrier layer may have a layer
thickness in a range of approximately 0.1 nm (one atomic layer) to
approximately 5000 nm, for example a layer thickness in a range of
approximately 10 nm to approximately 200 nm, for example a layer
thickness of approximately 40 nm.
[0113] An electrically active region 104 of the light emitting
device 100 may be arranged on or above the barrier layer. The
electrically active region 104 may be understood as that region of
the light emitting device 100 in which an electric current for the
operation of the optoelectronic device, for example of the light
emitting device 100, flows. In various exemplary embodiments, the
electrically active region 104 may have a first electrode 106, a
second electrode 108 and a functional layer system 110, as will be
explained in even greater detail below.
[0114] In this regard, in various exemplary embodiments, the first
electrode 106 (for example in the form of a first electrode layer
106) may be applied on or above the barrier layer (or on or above
the substrate 102 if the barrier layer is not present). The first
electrode 106 (also designated hereinafter as bottom electrode 106)
may be formed from an electrically conductive material, such as,
for example, a metal or a transparent conductive oxide (TCO) or a
layer stack including a plurality of layers of the same metal or
different metals and/or the same TCO or different TCOs. Transparent
conductive oxides are transparent conductive materials, for example
metal oxides, such as, for example, zinc oxide, tin oxide, cadmium
oxide, titanium oxide, indium oxide, or indium tin oxide (ITO).
Alongside binary metal-oxygen compounds, such as, for example, ZnO,
SnO.sub.2, or In.sub.2O.sub.3, ternary metal-oxygen compounds, such
as, for example, AlZnO, Zn.sub.2SnO.sub.4, CdSnO.sub.3 ,
ZnSnO.sub.3, MgIn.sub.2O.sub.4, GaInO.sub.3,
Zn.sub.2In.sub.2O.sub.5 or In.sub.4Sn.sub.3O.sub.12, or mixtures of
different transparent conductive oxides also belong to the group of
TCOs and may be used in various exemplary embodiments. Furthermore,
the TCOs do not necessarily correspond to a stoichiometric
composition and may furthermore be p-doped or n-doped.
[0115] In various exemplary embodiments, the first electrode 106
may include a metal; for example Ag, Pt, Au, Mg, Al, Ba, In, Ca, Sm
or Li, and compounds, combinations or alloys of these
materials.
[0116] In various exemplary embodiments, the first electrode 106
may be formed by a layer stack of a combination of a layer of a
metal on a layer of a TCO, or vice versa. One example is a silver
layer applied on an indium tin oxide layer (ITO) (Ag on ITO) or
ITO-Ag-ITO multilayers.
[0117] In various exemplary embodiments, the first electrode 106
may provide one or a plurality of the following materials as an
alternative or in addition to the abovementioned materials:
networks composed of metallic nanowires and nanoparticles, for
example composed of Ag; networks composed of carbon nanotubes;
graphene particles and graphene layers; networks composed of
semiconducting nanowires.
[0118] Furthermore, the first electrode 106 may include
electrically conductive polymers or transition metal oxides or
transparent electrically conductive oxides.
[0119] In various exemplary embodiments, the first electrode 106
and the substrate 102 may be formed as translucent or transparent.
In the case where the first electrode 106 is formed from a metal,
the first electrode 106 may have for example a layer thickness of
less than or equal to approximately 25 nm, for example a layer
thickness of less than or equal to approximately 20 nm, for example
a layer thickness of less than or equal to approximately 18 nm.
Furthermore, the first electrode 106 may have for example a layer
thickness of greater than or equal to approximately 10 nm, for
example a layer thickness of greater than or equal to approximately
15 nm. In various exemplary embodiments, the first electrode 106
may have a layer thickness in a range of approximately 10 nm to
approximately 25 nm, for example a layer thickness in a range of
approximately 10 nm to approximately 18 nm, for example a layer
thickness in a range of approximately 15 nm to approximately 18
nm.
[0120] Furthermore, for the case where the first electrode 106 is
formed from a transparent conductive oxide (TCO), the first
electrode 106 may have for example a layer thickness in a range of
approximately 50 nm to approximately 500 nm, for example a layer
thickness in a range of approximately 75 nm to approximately 250
nm, for example a layer thickness in a range of approximately 100
nm to approximately 150 nm.
[0121] Furthermore, for the case where the first electrode 106 is
formed from, for example, a network composed of metallic nanowires,
for example composed of Ag, which may be combined with conductive
polymers, a network composed of carbon nanotubes which may be
combined with conductive polymers, or from graphene layers and
composites, the first electrode 106 may have for example a layer
thickness in a range of approximately 1 nm to approximately 500 nm,
for example a layer thickness in a range of approximately 10 nm to
approximately 400 nm, for example a layer thickness in a range of
approximately 40 nm to approximately 250 nm.
[0122] The first electrode 106 may be formed as an anode, that is
to say as a hole-injecting electrode, or as a cathode, that is to
say as an electron-injecting electrode.
[0123] The first electrode 106 may have a first electrical
terminal, to which a first electrical potential (provided by an
energy source (not illustrated), for example a current source or a
voltage source) may be applied. Alternatively, the first electrical
potential may be applied to the substrate 102 and then be fed
indirectly to the first electrode 106 via said substrate. The first
electrical potential may be, for example, the ground potential or
some other predefined reference potential.
[0124] Furthermore, the electrically active region 104 of the light
emitting device 100 may have a functional layer system 110, also
designated as an organic electroluminescent layer structure 110,
which is applied on or above the first electrode 106.
[0125] The organic electroluminescent layer structure 110 may
include a plurality of organic functional layer structures 112,
116. In various exemplary embodiments, the organic
electroluminescent layer structure 110 may, however, also include
more than two organic functional layer structures, for example 3,
4, 5, 6, 7, 8, 9, 10, or even more.
[0126] A first organic functional layer structure 112 and a second
organic functional layer structure 116 are illustrated in FIG.
1.
[0127] The first organic functional layer structure 112 may be
arranged on or above the first electrode 106. Furthermore, the
second organic functional layer structure 116 may be arranged on or
above the first organic functional layer structure 112. In various
exemplary embodiments, a charge generating layer structure 114
(charge generation layer, CGL) may be arranged between the first
organic functional layer structure 112 and the second organic
functional layer structure 116. In exemplary embodiments in which
more than two organic functional layer structures are provided, a
respective charge generating layer structure may be provided
between in each case two organic functional layer structures.
[0128] As will be explained in even greater detail below, each of
the organic functional layer structures 112, 116 may include in
each case one or a plurality of emitter layers, for example
including of at least one of a fluorescent or a phosphorescent
emitters, and one or a plurality of hole-conducting layers (not
illustrated in FIG. 1) (also designated as hole transport
layer(s)). In various exemplary embodiments, one or a plurality of
electron-conducting layers (also designated as electron transport
layer(s)) may alternatively or additionally be provided.
[0129] Examples of emitter materials which may be used in the light
emitting device 100 in accordance with various exemplary
embodiments for the emitter layer(s) include organic or
organometallic compounds such as derivatives of polyfluorene,
polythiophene and polyphenylene (e.g. 2- or 2,5-substituted
poly-p-phenylene vinylene) and metal complexes, for example iridium
complexes such as blue phosphorescent
FIrPic(bis(3,5-difluoro-2-(2-pyridyl)phenyl(2-carboxypyridyl)iridium
III), green phosphorescent Ir(ppy).sub.3
(tris(2-phenylpyridine)iridium III), red phosphorescent
Ru(dtb-bpy).sub.3*2(PF.sub.6)
(tris[4,4'-di-tert-butyl-(2,2')-bipyridine]ruthenium (III) complex)
and blue fluorescent DPAVBi
(4,4-bis[4-(di-p-tolylamino)styryl]biphenyl), green fluorescent
TTPA (9,10-bis[N,N-di(p-tolyl)amino]anthracene) and red fluorescent
DCM2 (4-dicyanomethylene)-2-methyl-6-julolidyl-9-enyl-4H-pyran) as
non-polymeric emitters. Such non-polymeric emitters may be
deposited by means of thermal evaporation, for example.
Furthermore, it is possible to use polymer emitters, which may be
deposited, in particular, by means of a wet-chemical method such as
spin coating, for example.
[0130] The emitter materials may be embedded in a matrix material
in a suitable manner.
[0131] It should be pointed out that other suitable emitter
materials are likewise provided in other exemplary embodiments.
[0132] The emitter materials of the emitter layer(s) of the light
emitting device 100 may be selected for example such that the light
emitting device 100 emits white light. The emitter layer(s) may
include a plurality of emitter materials that emit in different
colors (for example blue and yellow or blue, green and red);
alternatively, the emitter layer(s) may also be constructed from a
plurality of partial layers, such as a blue fluorescent emitter
layer or blue phosphorescent emitter layer, a green phosphorescent
emitter layer and a red phosphorescent emitter layer. By mixing the
different colors, the emission of light having a white color
impression may result. Alternatively, provision may also be made
for arranging a converter material in the beam path of the primary
emission generated by said layers, which converter material at
least partly absorbs the primary radiation and emits a secondary
radiation having a different wavelength, such that a white color
impression results from a (not yet white) primary radiation by
virtue of the combination of primary and secondary radiation.
Moreover, the emitter materials of different organic functional
layer structures may be chosen such that although the individual
emitter materials emit light of different colors (for example blue,
green or red or arbitrary other color combinations, for example
arbitrary other complementary color combinations), for example the
overall light which is emitted overall by all the organic
functional layer structures and is emitted toward the outside by
the OLED is a light of predefined color, for example white
light.
[0133] The organic functional layer structures 112, 116 may
generally include one or a plurality of electroluminescent layers.
The one or the plurality of electroluminescent layers may include
organic polymers, organic oligomers, organic monomers, organic
small, non-polymeric molecules ("small molecules") or a combination
of these materials. By way of example, the organic
electroluminescent layer structure 110 may include one or a
plurality of electroluminescent layers embodied as a hole transport
layer, so as to enable for example in the case of an OLED an
effective hole injection into an electroluminescent layer or an
electroluminescent region. Alternatively, in various exemplary
embodiments, the organic functional layer structures 112, 116 may
include one or a plurality of functional layers embodied as an
electron transport layer, so as to enable for example in an OLED an
effective electron injection into an electroluminescent layer or an
electroluminescent region. By way of example, tertiary amines,
carbazol derivatives, conductive polyaniline or polyethylene
dioxythiophene may be used as material for the hole transport
layer. In various exemplary embodiments, the one or the plurality
of electroluminescent layers may be embodied as an
electroluminescent layer.
[0134] As illustrated in FIG. 2, in various exemplary embodiments,
the first organic functional layer structure 112 may include a hole
injection layer 202, which may be applied, for example
deposited.
[0135] A first emitter layer 206 may be applied, for example
deposited, on or above the hole transport layer 204. The emitter
materials which may be provided for example for the first emitter
layer 206 are described above.
[0136] Furthermore, a first electron transport layer 208 may be
arranged, for example deposited, on or above the first emitter
layer 206. In various exemplary embodiments, the first electron
transport layer 208 may include or consist of one or more of the
following materials: NET-18, LG-201 or similiar. The first electron
transport layer 208 may have a layer thickness in a range of
approximately 10 nm to approximately 50 nm, for example in a range
of approximately 15 nm to approximately 10 nm, for example in a
range of approximately 20 nm to approximately 30 nm.
[0137] As described above, the (optional) hole injection layer 202,
the (optional) first hole transport layer 204, the first emitter
layer 206, and the (optional) first electron transport layer 208
form the first organic functional layer structure 112.
[0138] A charge generating layer structure (CGL) 114 is arranged on
or above the first organic functional layer structure 112, and will
be described in even greater detail below.
[0139] In various exemplary embodiments, the second organic
functional layer structure 116 is arranged on or above the charge
generating layer structure 114.
[0140] In various exemplary embodiments, the second organic
functional layer structure 116 may include a second hole transport
layer 210, wherein the second hole transport layer 210 is arranged
on or above the charge generating layer structure 114. By way of
example, the second hole transport layer 210 may be in physical
contact with the surface of the charge generating layer structure
114; to put it another way, they share a common interface. In
various exemplary embodiments, the second hole transport layer 210
may include or consist of one or more of the following materials:
HT-508, or similiar. The second hole transport layer 210 may have a
layer thickness in a range of approximately 10 nm to approximately
50 nm, for example in a range of approximately 15 nm to
approximately 40 nm, for example in a range of approximately 20 nm
to approximately 30 nm.
[0141] Furthermore, the second organic functional layer structure
116 may include a second emitter layer 212, which may be arranged
on or above the second hole transport layer 210. The second emitter
layer 212 may include the same emitter materials as the first
emitter layer 206. Alternatively, the second emitter layer 212 and
the first emitter layer 206 may have different emitter materials.
In various exemplary embodiments, the second emitter layer 212 may
be designed in such a way that it emits electromagnetic radiation,
for example light, having the same wavelength(s) as the emitted
electromagnetic radiation of the first emitter layer 206.
Alternatively, the second emitter layer 212 may be designed in such
a way that it emits electromagnetic radiation, for example light,
having a different wavelength or different wavelengths than the
emitted electromagnetic radiation of the first emitter layer 206.
The emitter materials of the second emitter layer may be materials
such as have been described above.
[0142] Other suitable emitter materials may, of course, be provided
both for the first emitter layer 206 and for the second emitter
layer 212.
[0143] Furthermore, the second organic functional layer structure
116 may include a second electron transport layer 214, which may be
arranged, for example deposited, on or above the second emitter
layer 212.
[0144] In various exemplary embodiments, the second electron
transport layer 214 may include or consist of one or more of the
following materials: NET-18, LG-201, and similar.
[0145] The second electron transport layer 214 may have a layer
thickness in a range of approximately 10 nm to approximately 50 nm,
for example in a range of approximately 15 nm to approximately 40
nm, for example in a range of approximately 20 nm to approximately
30 nm.
[0146] Furthermore, an electron injection layer 216 may be applied,
for example deposited, on or above the second electron transport
layer 214.
[0147] As described above, the (optional) second hole transport
layer 210, the second emitter layer 212, the (optional) second
electron transport layer 214, and the (optional) second electron
injection layer 216 form the second organic functional layer
structure 116.
[0148] In various exemplary embodiments, the organic
electroluminescent layer structure 110 (that is to say for example
the sum of the thicknesses of hole transport layer(s) and emitter
layer(s) and electron transport layer(s), etc.) may have a layer
thickness of a maximum of approximately 1.5 .mu.m, for example a
layer thickness of a maximum of approximately 1.2 .mu.m, for
example a layer thickness of a maximum of approximately 1 .mu.m,
for example a layer thickness of a maximum of approximately 800 nm,
for example a layer thickness of a maximum of approximately 500 nm,
for example a layer thickness of a maximum of approximately 400 nm,
for example a layer thickness of a maximum of approximately 300 nm.
In various exemplary embodiments, the organic electroluminescent
layer structure 110 may have for example a stack of a plurality of
organic light emitting diodes (OLEDs) arranged directly one above
another, wherein each OLED may have for example a layer thickness
of a maximum of approximately 1.5 .mu.m, for example a layer
thickness of a maximum of approximately 1.2 .mu.m, for example a
layer thickness of a maximum of approximately 1 .mu.m, for example
a layer thickness of a maximum of approximately 800 nm, for example
a layer thickness of a maximum of approximately 500 nm, for example
a layer thickness of a maximum of approximately 400 nm, for example
a layer thickness of a maximum of approximately 300 nm. In various
exemplary embodiments, the organic electroluminescent layer
structure 110 may have for example a stack of two, three or four
OLEDs arranged directly one above another, in which case for
example the organic electroluminescent layer structure 110 may have
a layer thickness of a maximum of approximately 3 .mu.m.
[0149] The light emitting device 100 may optionally generally
include further organic functional layers, for example arranged on
or above the one or the plurality of emitter layers or on or above
the electron transport layer(s), which serve to further improve the
functionality and thus the efficiency of the light emitting device
100.
[0150] The second electrode 108 (for example in the form of a
second electrode layer 108) may be applied on or above the organic
electroluminescent layer structure 110 or, if appropriate, on or
above the one or the plurality of further organic functional
layers, as described above.
[0151] In various exemplary embodiments, the second electrode 108
may include or be formed from the same materials as the first
electrode 106, metals being particularly suitable in various
exemplary embodiments.
[0152] In various exemplary embodiments, the second electrode 108
(for example for the case of a metallic second electrode 108) may
have for example a layer thickness of less than or equal to
approximately 50 nm, for example a layer thickness of less than or
equal to approximately 45 nm, for example a layer thickness of less
than or equal to approximately 40 nm, for example a layer thickness
of less than or equal to approximately 35 nm, for example a layer
thickness of less than or equal to approximately 30 nm, for example
a layer thickness of less than or equal to approximately 25 nm, for
example a layer thickness of less than or equal to approximately 20
nm, for example a layer thickness of less than or equal to
approximately 15 nm, for example a layer thickness of less than or
equal to approximately 10 nm.
[0153] The second electrode 108 may generally be formed in a
similar manner to the first electrode 106, or differently than the
latter. In various exemplary embodiments, the second electrode 108
may be formed from one or more of the materials and with the
respective layer thickness, as described above in connection with
the first electrode 106. In various exemplary embodiments, both the
first electrode 106 and the second electrode 108 are formed as
translucent or transparent. Consequently, the light emitting device
100 illustrated in FIG. 1 may be designed as a top and bottom
emitter (to put it another way as a transparent light emitting
device 100).
[0154] The second electrode 108 may be formed as an anode, that is
to say as a hole-injecting electrode, or as a cathode, that is to
say as an electron-injecting electrode.
[0155] The second electrode 108 may have a second electrical
terminal, to which a second electrical potential (which is
different than the first electrical potential), provided by the
energy source, may be applied. The second electrical potential may
have for example a value such that the difference with respect to
the first electrical potential has a value in a range of
approximately 1.5 V to approximately 20 V, for example a value in a
range of approximately 2.5 V to approximately 15 V, for example a
value in a range of approximately 3 V to approximately 12 V.
[0156] An encapsulation 118, for example in the form of a barrier
thin-film layer/thin-film encapsulation 118, may optionally also be
formed on or above the second electrode 108 and thus on or above
the electrically active region 104.
[0157] In the context of this application, a "barrier thin-film
layer" or a "barrier thin film" 118 may be understood to mean, for
example, a layer or a layer structure which is suitable for forming
a barrier against chemical impurities or atmospheric substances, in
particular against water (moisture) and oxygen. In other words, the
barrier thin-film layer 118 is formed in such a way that
OLED-damaging substances such as water, oxygen or solvent cannot
penetrate through it or at most very small proportions of said
substances may penetrate through it.
[0158] In accordance with one configuration, the barrier thin-film
layer 118 may be formed as an individual layer (to put it another
way, as a single layer). In accordance with an alternative
configuration, the barrier thin-film layer 118 may include a
plurality of partial layers formed one on top of another. In other
words, in accordance with one configuration, the barrier thin-film
layer 118 may be formed as a layer stack. The barrier thin-film
layer 118 or one or a plurality of partial layers of the barrier
thin-film layer 118 may be formed for example by means of a
suitable deposition method, e.g. by means of an atomic layer
deposition (ALD) method in accordance with one configuration, e.g.
a plasma enhanced atomic layer deposition (PEALD) method or a
plasmaless atomic layer deposition (PLALD) method, or by means of a
chemical vapor deposition (CVD) method in accordance with various
embodiments, e.g. a plasma enhanced chemical vapor deposition
(PECVD) method or a plasmaless chemical vapor deposition (PLCVD)
method, or alternatively by means of other suitable deposition
methods.
[0159] By using an atomic layer deposition (ALD) method, it is
possible for very thin layers to be deposited. In particular,
layers having layer thicknesses in the atomic layer range may be
deposited.
[0160] In accordance with one configuration, in the case of a
barrier thin-film layer 118 having a plurality of partial layers,
all the partial layers may be formed by means of an atomic layer
deposition method. A layer sequence including only ALD layers may
also be designated as a "nanolaminate".
[0161] In accordance with an alternative configuration, in the case
of a barrier thin-film layer 118 including a plurality of partial
layers, one or a plurality of partial layers of the barrier
thin-film layer 118 may be deposited by means of a different
deposition method than an atomic layer deposition method, for
example by means of a vapor deposition method.
[0162] In accordance with one configuration, the barrier thin-film
layer 118 may have a layer thickness of approximately 0.1 nm (one
atomic layer) to approximately 1000 nm, for example a layer
thickness of approximately 10 nm to approximately 100 nm in
accordance with one configuration, for example approximately 40 nm
in accordance with one configuration.
[0163] In accordance with one configuration in which the barrier
thin-film layer 118 includes a plurality of partial layers, all the
partial layers may have the same layer thickness. In accordance
with various embodiments, the individual partial layers of the
barrier thin-film layer 118 may have different layer thicknesses.
In other words, at least one of the partial layers may have a
different layer thickness than one or more other partial
layers.
[0164] In accordance with one configuration, the barrier thin-film
layer 118 or the individual partial layers of the barrier thin-film
layer 118 may be formed as a translucent or transparent layer. In
other words, the barrier thin-film layer 118 (or the individual
partial layers of the barrier thin-film layer 118) may consist of a
translucent or transparent material (or a material combination that
is translucent or transparent).
[0165] In accordance with one configuration, the barrier thin-film
layer 118 or (in the case of a layer stack having a plurality of
partial layers) one or a plurality of the partial layers of the
barrier thin-film layer 118 may include or consist of one of the
following materials: aluminum oxide (alumina), zinc oxide,
zirconium oxide, titanium oxide, hafnium oxide, tantalum oxide,
lanthanum oxide, silicon oxide, silicon nitride, silicon
oxynitride, indium tin oxide, indium zinc oxide, aluminum-doped
zinc oxide, and mixtures and alloys thereof. In various exemplary
embodiments, the barrier thin-film layer 118 or (in the case of a
layer stack having a plurality of partial layers) one or a
plurality of the partial layers of the barrier thin-film layer 118
may include one or a plurality of high refractive index materials,
to put it another way one or a plurality of materials having a high
refractive index, for example having a refractive index of at least
2.
[0166] In various exemplary embodiments, on or above the
encapsulation 118, it is possible to provide an adhesive and/or a
protective lacquer 120, by means of which, for example, a cover 122
(for example a glass cover 122) is fixed, for example adhesively
bonded, on the encapsulation 118. In various exemplary embodiments,
the optically translucent layer composed of adhesive and/or
protective lacquer 120 may have a layer thickness of greater than 1
.mu.m, for example a layer thickness of several .mu.m. In various
exemplary embodiments, the adhesive may include or be a lamination
adhesive.
[0167] In various exemplary embodiments, light-scattering particles
may also be embedded into the layer of the adhesive (also
designated as adhesive layer), which particles may lead to a
further improvement in the color angle distortion and the
coupling-out efficiency. In various exemplary embodiments, the
light-scattering particles provided may be dielectric scattering
particles, for example, such as metal oxides, for example, such as
e.g. silicon oxide (SiO.sub.2), zinc oxide (ZnO), zirconium oxide
(ZrO.sub.2), indium tin oxide (ITO) or indium zinc oxide (IZO)),
gallium oxide (Ga.sub.2O.sub.a), aluminum oxide, or titanium oxide.
Other particles may also be suitable provided that they have a
refractive index that is different than the effective refractive
index of the matrix of the translucent layer structure, for example
air bubbles, acrylate, or hollow glass beads. Furthermore, by way
of example, metallic nanoparticles, metals such as gold, silver,
iron nanoparticles, or the like may be provided as light-scattering
particles.
[0168] In various exemplary embodiments, between the second
electrode 108 and the layer composed of adhesive and/or protective
lacquer 120 an electrically insulating layer (not shown) may also
be applied, for example SiN, for example having a layer thickness
in a range of approximately 300 nm to approximately 1.5 .mu.m, for
example having a layer thickness in a range of approximately 500 nm
to approximately 1 .mu.m, in order to protect electrically unstable
materials, during a wet-chemical process for example.
[0169] Furthermore, it should be pointed out that, in various
exemplary embodiments, an adhesive 120 may also be completely
dispensed with, for example in embodiments in which the cover 122,
for example composed of glass, is applied to the encapsulation 118
by means of plasma spraying, for example.
[0170] Furthermore, in various exemplary embodiments, one or a
plurality of antireflective layers (for example combined with the
encapsulation 118, for example the thin-film encapsulation 118) may
additionally be provided in the light emitting device 100.
[0171] FIG. 3 illustrates the construction of a charge generating
layer 114 in accordance with various exemplary embodiments in a
cross-sectional view.
[0172] In various exemplary embodiments, the charge generating
layer structure 114 may include an electron-conducting charge
generating layer 302 and a hole-conducting charge generating layer
306, wherein the electron-conducting charge generating layer 302
may be arranged on or above the first electron transport layer 208,
for example may be in physical contact with the latter. The
hole-conducting charge generating layer 306 may be arranged on or
above the electron-conducting charge generating layer 302, wherein
a diffusion barrier layer 304 is provided between these two layers
302, 306. The second hole transport layer 210 may be arranged on or
above the hole-conducting charge generating layer 306.
[0173] Different to inorganic layers in the manufacture of
semiconductor devices, organic layers may diffuse into other layers
(partial layer interdiffusion), e.g. parts of the
electron-conducting charge generating layer 302 into the
hole-conducting charge generating layer 306 of a charge generating
layer structure 114 in an optoelectronic device, for example an
OLED. In order to suppress the partial layer interdiffusion (that
is to say, illustratively, to achieve a barrier effect), the
diffusion barrier layer 304 may be inserted between the individual
organic layers, e.g. between the hole-conducting charge generating
layer 306 and the electron-conducting charge generating layer
302.
[0174] In various exemplary embodiments, the charge generating
layer structure 114 is extended by means of the diffusion barrier
layer 304 (interlayer 304) between the charge generating layers 302
and 306 in order to prevent a partial layer interdiffusion between
the charge generating layers 302 and 306.
[0175] In various exemplary embodiments, the electron-conducting
charge generating layer 302 may be composed of a plurality of
substances, that is to say for example a substance mixture, or of a
single substance (for this reason, the electron-conducting charge
generating layer 302 may also be designated as an undoped n-type
charge generating layer 302). The substance forming the
electron-conducting charge generating layer 302, that is to say for
example the substance of which the electron-conducting charge
generating layer 302 consists, may have a high electron
conductivity. Furthermore, the substance of the electron-conducting
charge generating layer 302 may have a low work function (for
example a work function of less than or equal to approximately 3
eV) and a low absorption of visible light. In various exemplary
embodiments, as substance of the electron-conducting charge
generating layer 302 it is possible to provide any substance which
fulfills these stated conditions, for example an NET-18 matrix with
NDN-26 dopant (substance mixture) or NDN-26 (substance).
[0176] In various exemplary embodiments, the electron-conducting
charge generating layer 302 may have a layer thickness in a range
of approximately 1 nm to approximately 500 nm, for example in a
range of approximately 3 nm to approximately 100 nm, for example in
a range of approximately 10 nm to approximately 90 nm, for example
in a range of approximately 20 nm to approximately 80 nm, for
example in a range of approximately 30 nm to approximately 70 nm,
for example in a range of approximately 40 nm to approximately 60
nm, for example a layer thickness of approximately 50 nm.
[0177] In various exemplary embodiments, the hole-conducting charge
generating layer 306 may be composed of a plurality of substances,
that is to say for example a substance mixture, or of a single
substance (for this reason, the hole-conducting charge generating
layer 306 may also be designated as an undoped p-type charge
generating layer 306). The substance forming the hole-conducting
charge generating layer 306, that is to say for example the
substance of which the hole-conducting charge generating layer 306
consists, may have a high hole conductivity. Furthermore, the
substance of the hole-conducting charge generating layer 306 may
have a high work function and a low absorption of visible light. In
various exemplary embodiments, as substance of the hole-conducting
charge generating layer 306 it is possible to provide any material
or any substance which fulfills these stated conditions, for
example HAT-CN6, LG-101, F16CuPc, or similar.
[0178] In various exemplary embodiments, the hole-conducting charge
generating layer 306 may have a layer thickness in a range of
approximately 1 nm to approximately 500 nm, for example in a range
of approximately 3 nm to approximately 100 nm, for example in a
range of approximately 10 nm to approximately 90 nm, for example in
a range of approximately 20 nm to approximately 80 nm, for example
in a range of approximately 30 nm to approximately 70 nm, for
example in a range of approximately 40 nm to approximately 60 nm,
for example a layer thickness of approximately 50 nm.
[0179] In various exemplary embodiments, the hole-conducting charge
generating layer 306 may include a substance or substance mixture
having high hole conductivity and an energetically low conduction
band (Lowest Unoccupied Molecule Orbital, LUMO) relative to the
valence band (Highest Occupied Molecule Orbital, HOMO) of the
directly or indirectly adjacent electron-conducting charge
generating layer 302. To put it another way, the substance or the
substance mixture of the hole-conductive charge generating layer
306 has a LUMO that is energetically at the same level as or is
energetically lower than the HOMO of the substance of the
electron-conducting charge generating layer 302.
[0180] The diffusion barrier layer 304 may have a layer thickness
in a range of approximately 1 nm to approximately 200 nm, for
example in a range of approximately 3 nm to approximately 100 nm,
for example in a range of approximately 5 nm to approximately 10
nm, for example a layer thickness of approximately 6 nm. The charge
carrier conduction through the diffusion barrier layer 304 may take
place directly or indirectly.
[0181] The substance or the substance mixture of the diffusion
barrier layer 304 may be an electrical insulator in the case of an
indirect charge carrier conduction. The HOMO of the electrically
insulating substance of the diffusion barrier layer 304 may be
higher than the LUMO of the directly adjacent hole-conducting
charge generating layer. 306 and higher than the HOMO of the
directly adjacent electron-conducting charge generating layer 302.
A tunneling current through the diffusion barrier layer 304 may be
effected as a result.
[0182] Suitable substance for the diffusion barrier layer 304 are
phthalocyanine derivatives, for example metal oxide phthalocyanine
compounds, for example vanadium oxide phthalocyanine (VOPc),
titanium oxide phthalocyanine (TiOPc); for copper oxide
phthalocyanine (CuOPc).
[0183] In a first specific implementation of various exemplary
embodiments, which, however, is not intended to be of any
restrictive character whatsoever, the charge generating layer
structure 114 includes the following layers: [0184]
electron-conducting charge generating layer 302: NDN-26 dopant in
an NET-18 matrix having a layer thickness of approximately 5 nm;
[0185] diffusion barrier layer 304: VOPc having a layer thickness
of approximately 6 nm; and [0186] hole-conducting charge generating
layer 306: HAT-CN having a layer thickness of approximately 5
nm.
[0187] In this implementation, the first electron transport layer
208 may include NET-18 having a layer thickness of approximately 50
nm. Furthermore, the second hole transport layer 210 in this
implementation may include HT-508 having a layer thickness of
approximately 50 nm.
[0188] In a second specific implementation of various exemplary
embodiments, which, however, is not intended to be of any
restrictive character whatsoever, the charge generating layer
structure 114 includes the following layers: [0189]
electron-conducting charge generating layer 302: NDN-26 dopant in
an NET-18 matrix having a layer thickness of approximately 3 nm;
[0190] diffusion barrier layer 304: TiOPc having a layer thickness
of approximately 6 nm; and [0191] hole-conducting charge generating
layer 306: HAT-CN having a layer thickness of approximately 15
nm.
[0192] In this implementation, the first electron transport layer
208 may include NET-18 having a layer thickness of approximately 50
nm. Furthermore, the second hole transport layer 210 in this
implementation may include HT-508 having a layer thickness of
approximately 50 nm.
[0193] FIG. 4 shows a measured optical transmission diagram 400 of
a charge generating layer structure 114 in accordance with a first
specific implementation 406 and a second specific implementation
408 of the charge generating layer structure 114 in comparison with
an optical transmission of an diffusion barrier layer of a charge
generating layer structure 114 including the previously used
substance NET-39 410 for the diffusion barrier layer 304 in a
transmission diagram 400. The illustration shows the measured
transmission 402 as a function of the wavelength of the incident
light 404 in characteristic curves 406, 408 and 410. It is evident
that the transmission of the metal oxide phthalocyanines VOPc 406
and TiOPc 408 in the spectral range of approximately 450 nm to
approximately 600 nm is higher than the transmission of NET-39
410.
[0194] FIG. 5 shows a measured temperature/voltage diagram 500 of a
charge generating layer structure 114 in accordance with a first
specific implementation 512 and a second specific implementation
510 of the charge generating layer structure 114 and an diffusion
barrier layer 304 including the previously used substance NET-39
508 and without 506 diffusion barrier layer 304 in the charge
generating layer structure 114. In the temperature/voltage diagram
500, a measured voltage drop 502 across the charge generating layer
structure 114 is illustrated as a function of time 504 at a
predefined temperature (85.degree. C.) and a predefined current
density (10 mA/cm.sup.2). The diagram reveals a high voltage
stability of the charge generating layer structure 114 including
VOPc 512 and TiOPc 510 as substance for the diffusion barrier layer
304 in comparison with the previously used substance NET-39 508 and
without 506 diffusion barrier layer 304.
[0195] FIG. 6 shows a conductivity diagram 600 of a charge
generating layer structure 114 in accordance with a first specific
implementation 608 and a second specific implementation 606 of the
charge generating layer structure 114 and an diffusion barrier
layer 304 including previously used substance NET-39 610.
[0196] In the conductivity diagram 600, a measured current density
602 is illustrated at a function of an applied voltage 604.
[0197] It is evident that the characteristic curves of VOPc 608,
TiOPc 606 and NET-39 610 have the form of a characteristic curve of
a pn diode.
[0198] In various exemplary embodiments, a charge generating layer
structure is provided for an optoelectronic device, for example for
an OLED, wherein the optoelectronic resistance of the charge
generating layer structure is lower than in charge generating layer
structures used heretofore.
[0199] In various exemplary embodiments, a charge generating layer
structure is provided, wherein the hole-conducting charge
generating layer is formed from a single substance and thus without
doped layers, for example HAT-CN. To put it another way, a layer
including a dopant in a matrix is not realized.
[0200] In various exemplary embodiments, a charge generating layer
structure is provided, wherein the diffusion barrier layer includes
as substance one or a plurality of phthalocyanine derivatives, for
example metal oxide phthalocyanines.
[0201] The used metal oxide phthalocyanine derivatives for the
diffusion barrier layer, for example VOPc, TiOPc, CuOPc, by means
of their crystallization structure, exhibit a better barrier effect
than the substance NET-39 used heretofore. This is manifested in
the better voltage stability of the charge generating layer
structure including metal oxide phthalocyanine as substance of the
diffusion barrier layer. As a result, an increase of the operating
period of the optoelectronic device is possible, compared with the
substance for the diffusion barrier layer NET-39 used
heretofore.
[0202] The optical resistance is particularly low in the case of a
combination of HAT-CN (hole-conducting charge generating layer
composed of a single substance) and the metal oxide phthalocyanine,
which is manifested in a higher transmission in the wavelength
range of 450 nm to 650 nm than in the case of the substance NET-39
used heretofore for the diffusion barrier layer.
[0203] As a result of the lower optoelectronic resistance of the
substance combination of HAT-CN and metal phthalocyanine or metal
oxide phthalocyanine, i.e. the low absorption and the higher
voltage stability, the efficiency of the optoelectronic device may
be increased compared with substance combinations used
heretofore.
[0204] A process engineering advantage of this approach in
accordance with various exemplary embodiments may furthermore be
seen in the fact that for the hole-conducting charge generating
layer and/or for the electron-conducting charge generating layer,
in each case only a small number of organic substances are
required, which may be evaporated in vacuo from evaporator sources
(also designated as substance source) at temperatures of below
500.degree. C.
[0205] While the disclosed embodiments have been particularly shown
and described with reference to specific embodiments, it should be
understood by those skilled in the art that various changes in form
and detail may be made therein without departing from the spirit
and scope of the disclosed embodiments as defined by the appended
claims. The scope of the disclosed embodiments is thus indicated by
the appended claims and all changes which come within the meaning
and range of equivalency of the claims are therefore intended to be
embraced.
* * * * *