WO2009053890A2 - A colored organic electronic device - Google Patents

A colored organic electronic device Download PDF

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Publication number
WO2009053890A2
WO2009053890A2 PCT/IB2008/054306 IB2008054306W WO2009053890A2 WO 2009053890 A2 WO2009053890 A2 WO 2009053890A2 IB 2008054306 W IB2008054306 W IB 2008054306W WO 2009053890 A2 WO2009053890 A2 WO 2009053890A2
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Prior art keywords
layer
reflecting layer
device
providing
state
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PCT/IB2008/054306
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French (fr)
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WO2009053890A3 (en )
Inventor
Cristina Tanase
Mihaela-Ioana Popovici
Herbert Lifka
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Koninklijke Philips Electronics N.V.
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L51/00Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof
    • H01L51/50Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof specially adapted for light emission, e.g. organic light emitting diodes [OLED] or polymer light emitting devices [PLED];
    • H01L51/52Details of devices
    • H01L51/5262Arrangements for extracting light from the device
    • H01L51/5271Reflective means
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L51/00Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof
    • H01L51/42Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof specially adapted for sensing infra-red radiation, light, electro-magnetic radiation of shorter wavelength or corpuscular radiation and adapted for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation using organic materials as the active part, or using a combination of organic materials with other material as the active part; Multistep processes for their manufacture
    • H01L51/44Details of devices
    • H01L51/447Light trapping means
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L2251/00Indexing scheme relating to organic semiconductor devices covered by group H01L51/00
    • H01L2251/50Organic light emitting devices
    • H01L2251/53Structure
    • H01L2251/5307Structure specially adapted for controlling the direction of light emission
    • H01L2251/5323Two-side emission, i.e. TOLED
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L51/00Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof
    • H01L51/50Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof specially adapted for light emission, e.g. organic light emitting diodes [OLED] or polymer light emitting devices [PLED];
    • H01L51/52Details of devices
    • H01L51/5203Electrodes
    • H01L51/5221Cathodes, i.e. with low work-function material
    • H01L51/5234Transparent, e.g. including thin metal film
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L51/00Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof
    • H01L51/50Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof specially adapted for light emission, e.g. organic light emitting diodes [OLED] or polymer light emitting devices [PLED];
    • H01L51/52Details of devices
    • H01L51/5237Passivation; Containers; Encapsulation, e.g. against humidity
    • H01L51/5253Protective coatings
    • H01L51/5256Protective coatings having repetitive multilayer structures
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/54Material technologies
    • Y02E10/549Material technologies organic PV cells
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product
    • Y02P70/52Manufacturing of products or systems for producing renewable energy
    • Y02P70/521Photovoltaic generators

Abstract

This invention relates to a colored organic electronic device comprising a transparent substrate (100) provided with a first transparent conducting layer (110), a plurality of organic layers (120), from which at least one is optoelectronic active. The plurality of organic layers are arranged on the first transparent conducting layer. The device further comprises a second conducting layer (130) arranged above the plurality of organic layers, and a reflecting layer (140) arranged in conjunction with the second conducting layer. The reflecting layer has a first color which causes the device to have an appearance of the first color in the off-state. The on-state is defined by said device receiving a predetermined voltage from an external source and said off-state is defined by the device not receiving a voltage from an external source.

Description

A colored organic electronic device

FIELD OF THE INVENTION

The present invention relates to the field of organic electronic devices, and more particularly to a colored organic electronic device with a colored appearance in both the on-state and the off-state, and a corresponding method for manufacturing such a device.

BACKGROUND OF THE INVENTION

Organic electronic devices typically comprise a plurality of organic layers arranged between two transparent electrodes, amongst which organic layers at least one layer is optoelectronic active, e.g. light emitting or photovoltaic. A light emitting layer is an organic material that is capable of emitting light as a response to receiving a voltage in a light emitting mode. A photovoltaic layer generates a current and/or a voltage when receiving and absorbing light in a photovoltaic mode. Thus, applying a voltage across the electrodes in the light emitting mode causes light to be emitted from the light emitting organic layer, and shining light on the device in the photovoltaic mode results in a current and/or voltage generated at the electrodes. Organic electronic devices that utilize the light emitting mode are commonly known as organic light emitting diodes (OLED). Well known organic electronic devices that utilize the photovoltaic mode are solar cells. In the following mainly OLEDs are described, but the configuration of the devices described herein under also yields for solar cells. Organic light emitting diodes (OLED) are commonly used in backlighting and display applications. As illustrated in Fig. 1 OLEDs typically comprise a number of organic layers 120 based on small molecules and/or polymers. Each layer is optimized for its own functionality. In the basic OLED structure, the organic layers 120 comprising also a light emitting layer are stacked between two electrodes 110 and 130. The anode 110 is transparent and comprised of e.g. indium tin oxide (ITO) on a transparent substrate 100. Examples of prior art OLEDs in a) a bottom emission configuration and b) a dual-side emission configuration are illustrated in Fig. 1.

For the bottom emission OLED, the cathode 130 typically consists of e.g. Ba or LiF and a thick Al layer (the later is also used for solar cell devices). In this case, the cathode 130 is non-transparent and the main light output from the device is via the substrate 100 (and likewise the main input of ambient light to the device also enters via the substrate 100).

The dual-side emission OLED 20, as illustrated in Fig. 1 b), has a transparent cathode 130. Thus, light is output from the device both via the substrate 100 and via the transparent cathode 130. The material of the cathode 130 is e.g. LiF/Al/Ag. Optionally, the OLED-device is provided with a transparent dielectric layer 135 with high refractive index such as ZnSe or ZnS for enhancement of the optical transmission and hence the light output. When looking at the appearance of a bottom-emission OLED 10, in its on- state, i.e. when a voltage is applied over the electrodes, the OLED is a uniform diffuse light source, and in the off-state the OLED is mainly refractive due to its non-transparent upper electrode, i.e. the cathode 130. In some prior art solutions the cathode is more or less reflective, which helps enhance the brightness of the emission of the device in its on-state. The color of the typical OLED (and a solar cell) in the off- state is given mainly by the combination of the color of the organic material and the more or less reflecting cathode. WO 2005015640 Al discloses an OLED with a high reflectivity cathode which in addition gives the OLED a mirror like appearance in the off-state.

Furthermore, other solutions have been proposed in prior art in order to improve the appearance of the OLED, which solutions include adding layers on the basic OLED structure. These additional layers typically consist of filters, front diffusers, or polarizers etc. In these prior art solutions the luminescent light that is emitted in the light emitting layer may be affected in a negative way. For instance, when adding a polarizer to give a colored appearance of the device, up to 40% of intensity of the emitted light is absorbed in the polarizer.

European patent application EP 1 256 990 discloses an OLED in which the structure of the OLED is formed with an additional intermediate layer. In the basic OLED structure a thin intermediate layer is provided between a transparent cathode and an additional reflecting layer above the thin intermediate layer. The thin intermediate layer is arranged to reduce the amount of ambient light that is reflected in the reflecting layer, such that a higher display contrast is achieved arising from the reduced reflection of ambient light from the reflecting layer. SUMMARY OF THE INVENTION

It is an object of the present invention to provide an organic electronic device that alleviates the above-mentioned drawbacks of the prior art.

This object is achieved by a colored organic electronic device and a corresponding method for manufacturing a colored organic electronic device according to the present invention as defined in the independent claims 1 and 12.

The invention is based on an insight that by adding a highly reflecting colored layer to the organic electronic device structure, colored appearance for the organic electronic device is achieved by reflection of the emitted light in the on- state in the light emitting mode and reflection of the ambient light in the off-state.

Thus, in accordance with an aspect of the present invention, there is provided a colored organic electronic device comprising a transparent substrate provided with a first transparent conducting layer, a plurality of organic layers, from which at least one organic layer is optoelectronic active. The plurality of organic layers are arranged on the first transparent conducting layer. The device further comprises a second conducting layer arranged above the plurality of organic layers, and a reflecting layer arranged in conjunction with the second conducting layer. The reflecting layer has a first color which causes the device to have an appearance of the first color in an off-state. An on-state is defined by the device receiving a predetermined voltage from an external source and the off- state is defined by the device not receiving a voltage from an external source.

Thus, a device which is optoelectronic active and which has a reflecting colored layer that reflects ambient light in the off-state is achieved. Due to this the device has an attractive appearance in the off-state. This is attractive in many applications, for example when integrating an optoelectronic active device in a mosaic environment, and the device must present the same color in its off- state as the mosaic tiles.

In accordance with an embodiment of the device, as defined in claim 2, the plurality of organic layers further comprises at least one layer that absorbs light in a photovoltaic mode. Thus, the principle of the present invention further provides an attractive colored appearance for organic electronic devices that utilize a photovoltaic mode. By choosing the color of the reflecting layer appropriately, the devices can be designed to fit in the environment in which they are placed, e.g. a roof or a wall.

In accordance with an embodiment of the device as defined in claim 3, the optoelectronic active layer emits light of a second color in the on-state. Thus, a colored organic light emitting diode device, OLED, is provided, which device have a colored appearance due to the colored reflecting layer in the off-state and which emits light of a second color in the on-state. This is convenient when integrating the device in an environment in which the device should blend in or provide a decorative appearance.

Furthermore, the light provided by the optoelectronic active device in the off-state and the on-state are decoupled, such that no change in the electroluminescence of the OLED in the on-state is observed.

In accordance with an embodiment of the device, as defined in claim 4, the second conducting layer is transparent and the reflecting layer is arranged above the second transparent conducting layer. Thus, the application of the reflecting layer onto the OLED is made simple, as the reflecting layer may be added in for instance a moulding process.

Additionally, the reflecting layer provides an extra encapsulation layer for protecting the

OLED device against mechanical damages.

In accordance with an embodiment of the device, as defined in claim 5, the second conducting layer comprises an electron injecting layer and a conductive metal layer, and wherein the reflecting layer is arranged between the electron injecting layer and the conductive metal layer. Thus, the reflecting layer is an integrated part of the cathode system which is advantageous.

In accordance with an embodiment of the device, as defined in claim 6, the reflecting layer is a multilayer comprising a metal and metal oxide selected from a group composed of Cr, Ni, Au, and Cu. By realizing the reflecting layer with these materials a wide range of colors for the appearance if the device in the on- and off-states are obtainable.

In accordance with an embodiment of the device, as defined in claim 7, the reflecting layer is a compound selected from a group composed of TiN, ZrN, CrxN, and

ZrCxNy. By realizing the reflecting layer with these materials a wide range of colors for the appearance of the device in the on- and off-states are obtainable.

In accordance with an embodiment of the device, as defined in claim 8, the device further comprises a thin film encapsulating multilayer, "TFE", arranged between the second transparent conducting layer and the reflecting layer. Thin film encapsulation protects the polymer materials from moist and air and elongates the lifetime of the device. In accordance with an embodiment of the device, as defined in claim 9, the first and second colors are the same color. The reflecting layer will increase the efficiency of the emitted light from the device. When letting the first color and the second color be the same the color intensity in the on-state is increased. In accordance with an embodiment of the device, as defined in claim 10, the reflecting layer is patterned. Thus, in the off-state a colored patterned reflection is obtained from device. The pattering may be performed such that the device has highly reflecting areas and areas of at least much lower reflectivity. The patterning may also be used to provide reflecting areas of different colors which allows for creation of attractive patterns and optical effects from the device.

In accordance with an embodiment of the device, as defined in claim 11, the reflecting layer is diffusive. By having a highly reflecting and at the same time diffusive layer, light from the device is not only increased, but additionally more diffuse. This results in less visibility of non homogeneous defects within the device.

Further, in accordance with a second aspect of the present invention as defined in claim 12, there is provided a method for manufacturing a colored organic electronic device comprising the steps of: providing a transparent substrate with a first transparent conducting layer, - providing a plurality of organic layers, providing a top layer comprising a second conducting layer and a reflecting layer.

The device has an on-state which is defined by the device receiving a predetermined voltage from an external source, and an off-state which is defined by the device not receiving a voltage from an external source. Further, at least one layer of the plurality of organic layers is optoelectronic active. The reflecting layer has a first color which causes the device to have an appearance of the first color in the off-state. Thus, an advantageous and simple method for creating a color improved organic electronic device is provided. In accordance with an embodiment of the method, as defined in claim 13, the optoelectronic active layer absorbs light in a photovoltaic mode, which is advantageous for manufacturing applications like solar cells with a colored appearance.

In accordance with an embodiment of the method, as defined in claim 14, the optoelectronic active layer emits light of a second color in the on-state which is advantageous for manufacturing applications like organic light emitting diode devices with a colored appearance in the on-state and the off-state.

In accordance with an embodiment of the method, as defined in claim 15, the step of providing the top layer comprises first providing the second conducting layer, the second layer being a transparent conducting layer, and secondly providing the reflecting layer. This allows for a variety of techniques and materials to be used when applying the reflecting layer which is advantageous.

In accordance with an embodiment of the method, as defined in claim 16, the method further comprises a step of providing a thin film encapsulation before the step of providing the reflecting layer, which will improve the protection of the organic layers against moist and air. This increases the life time of the device.

In accordance with an embodiment of the method, as defined in claim 17, the step of providing a thin film encapsulation is done by applying an inorganic/inorganic multilayer stack. In accordance with an embodiment of the method, as defined in claim 18, the step of providing a thin film encapsulation is done by applying inorganic/organic multilayer stack.

In accordance with an embodiment of the method, as defined in claim 19, the step of providing the top layer comprises the steps of: - providing an electron injecting layer providing the reflection layer; and providing a conductive metal layer.

In accordance with an embodiment of the method, as defined in claim 20, the reflecting layer is provided by sputtering alloys of metals into a multilayer, wherein the metals are selected from a group consisting of Cr, Ni, Au, and Cu, which allows for realizing a number of different colors of the reflecting layer.

In accordance with an embodiment of the method, as defined in claim 21, the reflecting layer is provided by reactive plasma deposition of compounds selected from a group consisting of TiN, ZrN, CrxN, and ZrCxNy, which allows for realizing a number of different colors of the reflecting layer.

In accordance with an embodiment of the method, as defined in claim 22, the reflecting layer is applied by using one of a method from a group of spin-coating, printing, lamination and molding.

In accordance with an embodiment of the method, as defined in claim 23, the reflecting layer material is a hydrophobic sol-gel coating.

In accordance with an embodiment of the method, as defined in claim 24, the first color is provided in the reflecting layer by integrating organic or inorganic pigments in the sol-gel coating. In accordance with an embodiment of the method, as defined in claim 25, the step of providing the reflecting layer further comprises patterning the reflecting layer.

These and other aspects, features, and advantages of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail and with reference to the appended drawings in which:

Fig. 1 a) and b) illustrate a cross-sectional view of prior art organic electronic device configurations.

Fig. 2 illustrates a cross-sectional view of an embodiment of a colored organic electronic device according to the present invention.

Fig. 3 illustrates a cross-sectional view of an embodiment of a colored organic electronic device according to the present invention. Fig. 4 illustrates a cross-sectional view of an embodiment of a colored organic electronic device according to the present invention.

Fig. 5 depicts schematic illustrations of alternative embodiments of the main steps of a method for manufacturing a colored organic electronic device according to the present invention Fig. 6 a) and b) show the reflectivity as a function of the wavelength of applied light for the colored reflecting layer in two embodiments according to the present invention.

Fig. 7 illustrates a patterned reflecting layer in an embodiment according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention addresses transparent organic electronic devices which comprise at least one optoelectronic active organic layer, such as organic light emitting diode devices, OLEDs, and solar cells, which devices are provided with a reflecting layer. The OLEDs thus omits most of the light in a direction perpendicular to the OLED plane in a bottom emission configuration and likewise ambient light enters the device in the opposite direction. In the following the principles of the present invention will be described mainly by referring to an OLED, although the main principles of the present invention also applies for the organic electronic device in a photovoltaic mode as utilized for a solar cell. Fig. 2 illustrates an embodiment of a colored organic electronic device according to the present invention, which will be referred to as a colored OLED 200 in the following. The colored OLED device 200 comprises a transparent substrate 100, made of e.g. a glass or polymer, on which substrate 100 a first transparent conducting layer 110 is provided. The first transparent conducting layer, herein after referred to as the anode 110, is a sputtered thin layer of ITO. On top of the transparent anode 110 a plurality of organic layers from which one is light emitter 120 are arranged, which layers form a light emitting layer 120 which they will be referred to hereinafter.

Furthermore, a second conducting layer, hereinafter referred to as the cathode 130 is arranged on the light emitting layer 120. The cathode 130 may be comprised of a multiple of layers of suitable materials to form a cathode system. The cathode 130 is transparent and comprises of e.g. LiF/Al/Ag. Above the cathode 130 a reflecting layer 140 is arranged. The reflecting layer 140 is highly reflecting and is arranged to have a first color. In the on- state, the light emitting layer 120 emits light of a second color. The emitted light is strong in comparison to normal ambient light and even thought some of the ambient light and also emitted light is reflected in the reflecting layer 140, the direct light output from the light emitting layer 120 via the transparent anode 110 and the transparent substrate 100 is of greater intensity and is substantially dominated by the second color, i.e. the color of the light emitted from the light emitting layer 120. In the off- state, no light is emitted from the light emitting layer 120. Thus, only ambient light enters the device 200. When, the ambient light is reflected in the reflecting layer 140, the color of the reflecting layer 140 is dominating the reflection and the device appears to have the first color. A colored organic light emitting diode device 200 according to the present invention is thus achieved, which device is colored in both the on- state and the off-state.

In an alternative embodiment the first color, i.e. the color of the reflecting layer is set to match the second color, i.e. the color of the light emitted from the light emitting layer 120. This will give an improved color intensity to the light output from the device 200 in the on-state, while providing the same color appearance of the device 200 in the off-state. In the two embodiments above, i.e. both when having a first and second color that differs from each other and when having the first and second colors matched, the light emitted towards the cathode is fully reflected back such that the intensity of the light leaving the device via the anode is increased by 30% as compared to not having a reflecting layer. According to an embodiment of the present invention the plurality of organic layers 120 comprises an organic layer that absorbs light in a photovoltaic mode. In this configuration the device 200 is utilized in applications like solar cells. Typically the on- state is not utilized for these applications, i.e. they work in the off-state. Thus, only ambient light enters the device 200. When, the ambient light is reflected in the reflecting layer 140, the color of the reflecting layer 140 is dominating the reflection and the device appears to have the first color. A colored organic photovoltaic device 200 according to the present invention, which device is colored in the off- state is thus achieved.

Referring now to Fig. 3, in an embodiment of the colored organic electronic device 300, an additional thin film encapsulating layer (TFE) 150 is arranged between the transparent cathode 130 and the reflecting layer 140. The purpose of the TFE multilayer 150 is to seal the device and to protect the material within the organic layer 120 from moist and air.

In one embodiment the TFE multilayer 150 is arranged to have two inorganic materials stacked. In an alternative embodiment the TFE multilayer 150 is arranged to have one inorganic material and one organic material stacked. Some examples of the inorganic materials used in the thin film encapsulation as described above are silicone nitride and silicon oxide. The organic material is preferably an application specific polymer.

In an embodiment of the colored organic electronic device 400, as depicted in Fig. 4, the device 400 comprises a transparent substrate 100, a transparent anode 110 consisting of a thin layer of ITO arranged on the transparent substrate 100, a stacked organic layer 120 arranged above the transparent anode 110, and, on top of the light emitting layer 120, a second conducting layer, and a reflecting layer 140. The second conductive layer is composed of an electron injecting layer 130a, and a conductive metal layer 130b. The reflecting layer 140 is arranged between the electron injecting layer 130a and the conductive metal layer 130b.

The electron injecting layer 130a, is in this exemplifying embodiment, implemented as a layer of Ba, and the conductive metal layer is a 100 nm thick layer of Al. The reflecting layer 140 is arranged as a multilayer. The multilayer comprises a metal and a corresponding metal oxide, which metal is selected from a group composted of Cr, Ni, Au and Cu. Alternatively, the reflecting layer 140 is a compound selected from a group composed of TiN, ZrN, CrxN, and ZrCxNy.

In an embodiment of the colored organic electronic device 200, 300, 400, the highly reflecting colored layer 140 is diffusive in order to provide a reflection of light which is smooth and which helps providing a colored even reflection from the colored electronic device 200, 300, 400.

In an alternative embodiment the reflecting layer 140 is patterned. When the reflecting layer 140 is arranged such that subareas of the organic electronic device 200, 300, 400 are covered with the reflecting layer, while having subareas of a chosen pattern, which subareas are not covered with the reflecting layer, it is possible to achieve an attractive appearance with a pattern reflecting from the device 200, 300, 400 in the off-state.

A second aspect of the present invention provides a method for manufacturing a colored organic electronic device. The method is illustrated in Fig. 5, in which the steps of alternative embodiments of the method are represented by boxes and possible flow-paths through the flow-chart. In the following an example of the method as for manufacturing an OLED is presented. Starting at step 500, a transparent substrate 100 is provided on which a first transparent conducting layer of thin (100 nm) film ITO is sputtered. If desired the ITO- layer may be patterned by conventional patterning techniques. In step 510 a plurality of organic light emitting layers 120 are provided. The plurality of light emitting layers 120 comprises at least one layer that is optoelectronic active. When manufacturing an OLED device, the optoelectronic active layer material emits light in the on-state. When manufacturing a solar cell the optoelectronic active layer material absorbs light and produces a current or a voltage. In this example, the organic layers are formed by conventional OLED techniques which are well described in prior art, Nature 1990,347, p539; APL 1987,51, p913; Adv. Mat. 2000,12,17, pl249, and will not be further discussed here. In the following steps a top layer comprising a second conducting layer 130 and a reflecting layer 140 is formed. Some alternative embodiments of the method are discussed hereinafter:

In step 520 a second conducting layer 130 is first provided on top of the organic layers 120. The second conducting layer 130 is provided by applying very thin layers of LiF/ Al/ Au, such that a transparent cathode is achieved. The method then continues to step 523, wherein a reflecting layer 140 is formed on top of the second conducting layer 130. In this exemplifying non- limiting example, the reflecting layer 140 has a color which is white, i.e. the first color is white, and is obtained by spin coating a precursor hydrophobic sol-gel onto the second conducting layer 130. The sol-gel material contains TiO2 in form of rutile phase (n=2.7) which is embedded in a SiO2 matrix via a sol-gel process. The sol-gel process takes place under controlled conditions of processing. The process is carried out at room temperature which assures the integrity of the device 200. Usually the drying temperature for sol-gel based materials is too high for an OLED but this is not the case for the sol-gel used in this application.

The resulting sol-gel coating contains titania nanoparticles and provides a high and diffuse reflection from the obtained reflecting layer 140. In Fig. 6 a) the measured reflectivity versus wavelength for the obtained sol-gel coating 140 is plotted. As it can be seen the reflectivity for the coating is high for all visible wavelengths of light. The coating thus provides a white reflection. Furthermore, the reflectivity of the reflecting layer 140 is controllable by varying the layer thickness.

An embodiment of the present method further provides a way of providing color in the reflecting layer 140 by integrating organic or inorganic pigments, or a combination of organic and inorganic pigments, in the sol-gel coating which was described above. Pigments integrated in the sol-gel matrix reflect light of a certain color and absorb light of other colors. This induces a modification of the reflectivity as a function of the wavelength of light. In Fig. 6 b) the measured reflectivity versus wavelength for the obtained sol-gel coating 140 when one type of red pigments are integrated in the sol-gel coating is plotted.

In alternative embodiments of the method, and depending on the utilized material, the reflecting layer 140 is obtained by other applying methods, such as lamination of a sheet material, printing or molding. In an alternative embodiment step 520, in which the second conducting layer

130 is applied, is followed by step 521. In step 521 a thin film encapsulation (TFE) 150 is provided before the step of obtaining a reflecting layer 140. The TFE layer 150 is applied by providing a multilayer stack, i.e. alternatively providing a plurality of thin films of material. The multilayer stack is arranged by applying an inorganic/inorganic multilayer stack comprising e.g. silicon nitride and silicone oxide. In an alternative embodiment the multilayer stack is arranged by applying an inorganic/organic multilayer stack comprising e.g. silicon nitride and silicone oxide in combination with a suitable organic material.

Let us consider another embodiment of the present method, in which embodiment the method after step 510, i.e. after having provided the organic light emitting layers 120, continues to step 530. In step 530 an electron injecting layer 130a, i.e. a cathode, is provided. In step 532 the reflecting layer 140 is provided on top of the electron injecting layer 130a, and the method is continued to step 533 in which a conductive metal layer 130b is provided on top of the reflecting layer 140. The cathode 130a comprises e.g. Ba, while the conductive metal layer 130b is a 100 nm thick metal layer of Al or any other suitable metal like e.g. Ag or Au.

The reflecting layer 140 is provided by sputtering alloys of metals into a multilayer. The composition of the multilayer is designed to provide a requested color, which is done by mixing layers of metals and their alloys in an appropriate multilayer. The metals are selected from a group consisting of Cr, Ni, Au, and Cu.

In an alternative embodiment of the method, reactive plasma deposition of TiN is used to provide the device with a reflecting layer 140. Other suitable compounds for creating a reflecting layer 140 of a requested color by reactive plasma deposition are ZrN, CrxN, and ZrCxNy.

In alternative embodiments of the method according to the present invention as described above, further one step, 522 and 531, respectively, is incorporated in the method flow-chart. Steps 522 and 531 both comprise patterning of the reflecting layer 140. In Fig. 7 a top view of a patterned reflecting layer 140 is illustrated. The patterning is performed by utilizing prior art patterning techniques, e.g. shadow masks or lithography. When patterning the reflecting layer 140, the locations of reflecting areas 142 may be chosen in a convenient way to produce a desired pattern. A plurality of colors of the reflecting material on patterned areas can be used to create a desired picture to be shown in the off-state of the device. The patterns may be created having no physical connection between them, and further keeping areas that are still transparent 141.

Above, embodiments of the organic electronic device and the corresponding method for manufacturing an organic electronic device according to the present invention as defined in the appended claims have been described. These should be seen as merely non- limiting examples. As understood by a skilled person, many modifications and alternative embodiments are possible within the scope of the invention.

Thus, as explained by means of the embodiments above, an organic electronic device which is colored both in the on-state and off-state is provided by adding a colored reflecting layer to the organic electronic device structure. The reflecting layer is provided with a convenient manufacturing method. It is to be noted, that for the purposes of this application, and in particular with regard to the appended claims, the word "comprising" does not exclude other elements or steps, that the word "a" or "an", does not exclude a plurality, which per se will be apparent to a person skilled in the art.

Claims

CLAIMS:
1. A colored organic electronic device comprising: a transparent substrate (100) provided with a first transparent conducting layer (110); a plurality of organic layers (120), from which at least one organic layer is optoelectronic active, and wherein said plurality of organic layers are arranged on said first transparent conducting layer; a second conducting layer (130) arranged above said plurality of organic layers; and a reflecting layer (140) arranged in conjunction with said second conducting layer; wherein said reflecting layer has a first color which causes said device to have an appearance of said first color in an off- state, and wherein an on-state is defined by said device receiving a predetermined voltage from an external source and said off-state is defined by said device not receiving a voltage from an external source.
2. A colored organic electronic device according to claim 1, wherein said optoelectronic active layer absorbs light in a photovoltaic mode.
3. A colored organic electronic device according to claim 1, wherein said optoelectronic active layer emits light of a second color in the on-state.
4. The device according any of claims 1 to 3, wherein said second conducting layer is transparent and said reflecting layer is arranged above said second transparent conducting layer.
5. The device according to any of claims 1 to 3, wherein said second conducting layer comprises an electron injecting layer (130a) and a conductive metal layer (130b), and wherein said reflecting layer (140) is arranged between said electron injecting layer and said conductive metal layer.
6. The device according to claim 5, wherein said reflecting layer is a multilayer comprising a metal and metal oxide selected from a group composed of Cr, Ni, Au, and Cu.
7. The device according to claim 5, wherein said reflecting layer is a compound selected from a group composed of TiN, ZrN, CrxN, and ZrCxNy.
8. The device according to claim 4, further comprising a thin film encapsulating multilayer (150), "TFE", arranged between said second transparent conducting layer and said reflecting layer.
9. The device according to any of the previous claims, wherein said first and second colors are the same color.
10. The device according to claim 2 or 3, wherein said reflecting layer is patterned.
11. The device according to claim 2 or 3, wherein said reflecting layer is diffusive.
12. A method for manufacturing a colored organic electronic device comprising the steps of: providing a transparent substrate with a first transparent conducting layer (500); providing a plurality of organic layers (510); - providing a top layer comprising a second conducting layer (520) and a reflecting layer (523); wherein said device has an on-state which is defined by said device receiving a predetermined voltage from an external source, and an off-state which is defined by said device not receiving a voltage from an external source, wherein at least one layer of said plurality of organic layers is optoelectronic active, and wherein said reflecting layer has a first color which causes said device to have an appearance of said first color in said off-state.
13. A method according to claim 12, wherein said optoelectronic active layer absorbs light in a photovoltaic mode.
14. A method according to claim 12, wherein said optoelectronic active layer emits light of a second color in said on-state.
15. A method according to claim 13 or 14, wherein the step of providing said top layer comprises first providing said second conducting layer, said second layer being a transparent conducting layer, and secondly providing said reflecting layer.
16. A method according to claim 15, further comprising a step of providing a thin film encapsulation (521) before said step of providing said reflecting layer.
17. A method according to claim 16, wherein said step of providing a thin film encapsulation is done by applying an inorganic/inorganic multilayer stack.
18. A method according to claim 16, wherein said step of providing a thin film encapsulation is done by applying inorganic/organic multilayer stack.
19. A method according to claim 13 or 14 , wherein the step of providing said top layer comprises the steps of: - providing an electron injecting layer (530); providing said reflection layer (532); and providing a conductive metal layer (533).
20. A method according to claim 19, wherein said reflecting layer is provided by sputtering alloys of metals into a multilayer, wherein said metals are selected from a group consisting of Cr, Ni, Au, and Cu.
21. A method according to claim 19, wherein said reflecting layer is provided by reactive plasma deposition of compounds selected from a group consisting of TiN, ZrN, CrxN, and ZrCxN5,.
22. A method according to any of claims 12 to 18, wherein said reflecting layer is applied by using one of a method from a group of spin-coating, printing, lamination and molding.
23. A method according to claim 22, wherein the reflecting layer material is a hydrophobic sol-gel coating.
24. A method according to claim 23, wherein said first color is provided in said reflecting layer by integrating organic or inorganic pigments in said sol-gel coating.
25. A method according to any of claims 12 to 24, wherein the step of providing said reflecting layer further comprises patterning said reflecting layer (522, 531).
PCT/IB2008/054306 2007-10-23 2008-10-20 A colored organic electronic device WO2009053890A3 (en)

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