WO2008147191A1 - A multilayer structure comprising a chemically inert protective layer - Google Patents

A multilayer structure comprising a chemically inert protective layer Download PDF

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Publication number
WO2008147191A1
WO2008147191A1 PCT/NL2008/050327 NL2008050327W WO2008147191A1 WO 2008147191 A1 WO2008147191 A1 WO 2008147191A1 NL 2008050327 W NL2008050327 W NL 2008050327W WO 2008147191 A1 WO2008147191 A1 WO 2008147191A1
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Prior art keywords
multilayer structure
structure according
layer
electronic device
protective layer
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PCT/NL2008/050327
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French (fr)
Inventor
Fredericus Johannes Touwslager
Michel Josephus Marie Somers
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Polymer Vision Limited
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Publication of WO2008147191A1 publication Critical patent/WO2008147191A1/en

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/80—Constructional details
    • H10K59/87—Passivation; Containers; Encapsulations
    • H10K59/873—Encapsulations

Definitions

  • the invention relates to a multilayer structure comprising a permeation barrier for protecting a further layer from elements present in the atmosphere, and at least a part of the further layer is conceived to be formed using a process comprising a chemical agent.
  • the known multilayer structure is a flexible display comprising a substrate provided with a permeation barrier for preventing environmental elements, like water and oxygen from contacting sensitive components of the flexible display. Such sensitive components are elements forming the active matrix.
  • the known flexible display further comprises a coating provided on the permeation barrier for mitigating defect formation on a suitable subsequent layer of material conceived to be deposited on the permeation barrier.
  • a suitable subsequent layer comprises a gate line of the polymer electronics element forming a pixel of the active matrix of the flexible display.
  • the permeation barrier provided with the coating may be at least partially destroyed or damaged during subsequent steps of the manufacturing process of the flexible display thereby substantially reducing the lifetime of the flexible display.
  • the multilayer structure further comprises a protective layer that is chemically inert with respect to a chemical agent and being conceived to protect at least the permeation barrier from the chemical agent.
  • This technical measure is based on the insight that one of the standard requirements in building a multilayer stack, such as, for example, a flexible display, is the stack integrity.
  • a layer present in the stack should not influence, or be influenced by, another layer in the stack. The same is applicable for processing associated with the introduction of a layer.
  • incorporation of an inorganic barrier layer is needed.
  • the barrier layer should preferably be an aluminium oxide or aluminium oxynitride layer. The problem with each of these two materials is that chemical processing, notably etching of the subsequently applied metal layer, attacks the barrier layer.
  • metal layer usually gold is used for the metal layer.
  • copper, aluminium, molybdenum, chromium, silver, platinum, or another metal or a metal alloy like MoCr, AlCu, AlNd, or a conductive material containing metal and non-metal elements may be used.
  • organic conductors even when printed, also cause these problems.
  • Conducting polymers like PANI or PEDOT are doped with strong acids like camphor sulphonic acid CSA for PANI (yielding PANI/CSA) or polystyrene sulphonic acid PSA for PEDOT (yielding PEDOT/PSA). These sulphonic acids might also attack the barrier layer and lead to a deterioration of its properties.
  • the protective layer can be either an inorganic or an organic layer resistant to chemicals used in subsequent processing steps.
  • the material is resistant to gold etching chemicals. It is noted that in the case of a bottom gate based transistor active matrix, the material must also be resistant against other chemicals such as a stripping agent, a gate dielectric, a gate dielectric etchant, etc.
  • the further layer may comprise one layer, or two or more layers.
  • Chemical agents that are usually used during chemical etching comprise acids, salts, and alkali/salt solutions.
  • suitable materials comprise: HNO3 / HF solutions, potassium hexacyanoferrate(II) / potassium hexacyanoferrate(III) / potassium thiosulphate; KI/I2 solutions, or potassium cyanide / potassium carbonate solutions.
  • HNO3 / HF solutions potassium hexacyanoferrate(II) / potassium hexacyanoferrate(III) / potassium thiosulphate
  • KI/I2 solutions potassium cyanide / potassium carbonate solutions.
  • the protective layer is selected from a class of materials chemically resistive to chemical agents used in the named processing steps.
  • the protective layer may comprise a suitable inorganic or organic material
  • Examples of materials that are suitable for use as a protective layer against the said chemical agents comprise polyamides, polyimides, (negative) photo lacquers based on epoxy or polyesters or polyimide based negative resists
  • Embodiments of a suitable further layer forming a part of the multilayer structure according to the invention comprise an organic semiconductor and/or an electronic device.
  • the conductive layer may be formed from a polymer.
  • the electronic device forms a part of a display.
  • the multilayer structure may comprise a substrate which may be further arranged with a planarization layer for providing a substantially smooth surface at least for the permeation barrier.
  • the substrate further comprises a planarization layer for providing a smooth surface at least for the permeation barrier.
  • the permeation barrier can comprise a metal layer, or may preferably be implemented from an insulator material.
  • Figure 1 presents a schematic view of an embodiment of the flexible display according to the invention.
  • Figure 2a presents a schematic view of a top view of an embodiment of an active-matrix circuit of the flexible display according to the invention.
  • Figure 2b presents a schematic view of a cross-section of an embodiment of an active-matrix circuit of the flexible display according to the invention.
  • Figure 3 presents a schematic view of an embodiment of an equivalent circuit of an active-matrix pixel of Figure 1.
  • Figure 4 presents a schematic view of an embodiment of an electrophoretic ink capsule.
  • Figure 5 presents a schematic view of an embodiment of an electronic device with the flexible display.
  • FIG. 1 presents a schematic view of an embodiment of the multilayer structure according to the invention.
  • a flexible display 10 is selected for the multilayer structure.
  • the flexible display 10 comprises a substrate 2 on top of which a suitable planarization layer 4 is deposited.
  • the flexible display 10 further comprises a permeation barrier 5 comprising, for example, an aluminium oxide or an aluminium oxynitride layer 5a and a protective layer 5b arranged to be chemically inert for the chemical agents used during processing steps of the active matrix layers 6.
  • a permeation barrier 5 comprising, for example, an aluminium oxide or an aluminium oxynitride layer 5a and a protective layer 5b arranged to be chemically inert for the chemical agents used during processing steps of the active matrix layers 6.
  • the layers are illustrated schematically and are not intended to be interpreted as the layers' actual respective thicknesses.
  • the active matrix layers 6 may comprise at least two layers.
  • Chemical agents that are usually used during chemical etching comprise acids, salts, alkali/salt solutions.
  • suitable materials comprise HNO 3 / HF solutions, potassium hexacyanoferrate(II) / potassium hexacyanoferrate(III) / potassium thiosulphate; KI/I2 solutions, or potassium cyanide / potassium carbonate solutions.
  • materials that are suitable for use as a protective layer against said chemical agents comprise, for example, polyimides, polyamides, negative photo lacquers based on epoxy or polyesters.
  • FIG 2a presents a schematic view of an embodiment of an active - matrix circuit 50 of the flexible display according to the invention.
  • the active- matrix circuit 50 comprises a pixel pad 53, a data line 51, a gate line 54 and a semiconductor 55.
  • Figure 2a schematically depicts a cross-section of the pixel pad 53, the data line 51, the gate line 54 and the semiconductor 55.
  • a protective layer 58 is discussed with reference to item 5b of Figure 1, on top of which the gate line 54 is arranged.
  • the gate line 54 is electrically separated from the data line 51 and the pixel pad 53 by means of a suitable insulator layer 56.
  • the semiconductor 55 is positioned on top of the thus formed structure.
  • the active-matrix circuit is processed on plastic foils resulting in an active matrix (AM) backplane that can be integrated into a flexible display.
  • A active matrix
  • the materials potentially used for the various layers are shown, by way of example, in Table 1.
  • the current stack starts with a highly conductive gate layer ⁇ e.g. metal, indium-tin oxide, or an organic conductor like PANI), followed by an inorganic or organic insulator layer, a second conductive layer and an organic semiconducting layer.
  • the organic layers are deposited, for example, by spin-coating.
  • the layers are patterned by photolithography, either by use of the intrinsic photosensitivity of the layers ⁇ e.g. the insulator layers) or by use of a photoresist ⁇ e.g. for most of the semiconductors and conductors).
  • Table 1 Examples of materials used for an active-matrix circuit with polymer electronics
  • FIG. 3 presents a schematic view of an embodiment of an equivalent circuit 20 of an active-matrix pixel of Figure 2.
  • Active-matrix displays are driven a row-at-a-time. In operation, during one frame time all the rows are sequentially selected by applying a voltage that changes the thin film transistors (TFTs) from a non-conducting to a conducting state. In this line selection time the pixel capacitors (i.e. the total capacitance at the drain side of the TFT) of the selected row are charged to the voltage supplied on the column electrodes. During the remaining frame time (i.e.
  • TFTs thin film transistors
  • the typical voltages are a row select voltage of -25 V, a row non-select voltage of +25 V, a column voltage between —15 V and +15 V and a common electrode voltage of 2.5 V. These are relatively high voltages, due to the high voltage E Ink display effect and the fact that polymer electronics devices have to be driven at somewhat higher voltages compared to amorphous silicon devices.
  • the advantage of using the electrophoretic ink as the display effect instead of liquid crystal (LC) material, as is generally used in Liquid Crystal Displays (LCDs), is that the electrophoretic ink is bi-stable. Addressing is therefore only necessary during an image update ( ⁇ 1 sec), while the active-matrix is at rest between image updates.
  • the disadvantage of using the electrophoretic ink is that one cannot apply frame inversion, i.e. apply alternatively positive and negative voltages on the columns (data lines) in subsequent frames, without changing the image content. This is commonly done in conventional LCDs to minimize the effect of ionic drift. As shown in Figure 3 a storage capacitor (Cst) is used.
  • FIG 4 presents a schematic view of an embodiment 30 of an electrophoretic capsule 33 comprising black microparticles 32 and white microp articles 31.
  • the capsule 33 is subjected to a specific external voltage by means of supplies 35a, 35b for displacing the black microparticles 32 and the white microparticles 31 in the capsule 33.
  • the new image information is written for a certain amount of time (500 ms - 1000 ms).
  • a typical dimension of the capsule 33 is about 20 micrometers.
  • Addressing of the electrophoretic ink from black to white requires the pixel capacitors to be charged to -15 V during 500 ms to 1000 ms. During this time the white particles drift towards the top (common) electrode, while the black particles drift towards the bottom (active-matrix back plane) electrode. Switching to black requires a negative pixel voltage, and applying 0 V on the pixels does not switch the electrophoretic ink .
  • the back plane only needs to be driven during an image update. Between image updates the pixel switches on the back plane are not driven.
  • the drive voltages for the electrophoretic ink are relatively high compared to standard LC effects.
  • the polymer electronics devices on the active-matrix back plane are therefore driven at relatively high voltages.
  • FIG. 5 presents a schematic view of an embodiment of an electronic device 70 with the flexible display 75.
  • the electronic device 70 may relate to a mobile telephone, an organizer, a palmtop computer, a music replay device, etc.
  • the electronic device 70 comprises a body of the housing 71 about which the flexible display 75 is arranged to be wrapped. It is noted that it is possible to arrange the flexible display 75 so that it is rolled up inside the housing 71 upon storage.
  • the housing 71 comprises a substantially rigid cover 72 arranged to receive the flexible display 75 and to be collapsed to a position 70a or to be extended together to a position 70b together with the flexible display 75.
  • the cover 72 comprises hinged bending areas 72a, 72b.
  • the electronic device 70 further comprises the edge protector 73 arranged with rigid portions 73a and with flexible portions 74a, 74b, the latter corresponding to hinged areas 72a, 72b of the cover 72.
  • the edge protector is easy to handle, and maintenance procedures can be carried out easily.

Abstract

The invention relates to a multilayer structure (1.0) comprising a permeation barrier layer (5a) for protecting a further layer (6) from elements present in atmosphere, wherein at least a part of the further layer is conceived to be formed using a processing comprising a chemical agent, the multilayer structure further comprising a protective layer (5b) being chemically inert with respect to the said agent and being conceived to protect at least the permeation barrier from the said agent.

Description

Title: A MULTILAYER STRUCTURE COMPRISING A CHEMICALLY INERT PROTECTIVE LAYER
FIELD OF THE INVENTION
The invention relates to a multilayer structure comprising a permeation barrier for protecting a further layer from elements present in the atmosphere, and at least a part of the further layer is conceived to be formed using a process comprising a chemical agent.
BACKGROUND OF THE INVENTION
An embodiment of a multilayer structure as is set forth in the opening paragraph is known from US2005/024266. The known multilayer structure is a flexible display comprising a substrate provided with a permeation barrier for preventing environmental elements, like water and oxygen from contacting sensitive components of the flexible display. Such sensitive components are elements forming the active matrix. The known flexible display further comprises a coating provided on the permeation barrier for mitigating defect formation on a suitable subsequent layer of material conceived to be deposited on the permeation barrier. In a case of a bottom-gate display configuration, for example, such subsequent layer comprises a gate line of the polymer electronics element forming a pixel of the active matrix of the flexible display.
It is a disadvantage of the known flexible display that the permeation barrier provided with the coating may be at least partially destroyed or damaged during subsequent steps of the manufacturing process of the flexible display thereby substantially reducing the lifetime of the flexible display.
SUMMARY OF THE INVENTION It is an object of the invention to provide a multilayer structure, notably a flexible display, with a prolonged life-time and improved operational characteristics.
To this end in the multilayer structure according to the invention, the multilayer structure further comprises a protective layer that is chemically inert with respect to a chemical agent and being conceived to protect at least the permeation barrier from the chemical agent.
This technical measure is based on the insight that one of the standard requirements in building a multilayer stack, such as, for example, a flexible display, is the stack integrity. A layer present in the stack should not influence, or be influenced by, another layer in the stack. The same is applicable for processing associated with the introduction of a layer. To protect the multilayer structure, notably the display, against the influence of water or other chemicals, like oxygen, present in the environment, incorporation of an inorganic barrier layer is needed. To meet the demands related to, for example, humidity protection, the barrier layer should preferably be an aluminium oxide or aluminium oxynitride layer. The problem with each of these two materials is that chemical processing, notably etching of the subsequently applied metal layer, attacks the barrier layer. Usually gold is used for the metal layer. Alternatively, copper, aluminium, molybdenum, chromium, silver, platinum, or another metal or a metal alloy like MoCr, AlCu, AlNd, or a conductive material containing metal and non-metal elements may be used. However, organic conductors, even when printed, also cause these problems. Conducting polymers like PANI or PEDOT are doped with strong acids like camphor sulphonic acid CSA for PANI (yielding PANI/CSA) or polystyrene sulphonic acid PSA for PEDOT (yielding PEDOT/PSA). These sulphonic acids might also attack the barrier layer and lead to a deterioration of its properties. To prevent the above-mentioned attack of a chemical agent used for forming a further layer on a previous material, it being a substrate or a permeation barrier layer, it is found to be advantageous to add a protective layer on top of the substrate layer or the permeation barrier layer. The protective layer can be either an inorganic or an organic layer resistant to chemicals used in subsequent processing steps. In particular, the material is resistant to gold etching chemicals. It is noted that in the case of a bottom gate based transistor active matrix, the material must also be resistant against other chemicals such as a stripping agent, a gate dielectric, a gate dielectric etchant, etc. It will be appreciated that the further layer may comprise one layer, or two or more layers.
Chemical agents that are usually used during chemical etching comprise acids, salts, and alkali/salt solutions. Examples of the suitable materials comprise: HNO3 / HF solutions, potassium hexacyanoferrate(II) / potassium hexacyanoferrate(III) / potassium thiosulphate; KI/I2 solutions, or potassium cyanide / potassium carbonate solutions. It is noted that in addition to etching, other processes are envisaged, such as resist stripping or deposition of a still further layer. The protective layer is selected from a class of materials chemically resistive to chemical agents used in the named processing steps. The protective layer may comprise a suitable inorganic or organic material
Examples of materials that are suitable for use as a protective layer against the said chemical agents comprise polyamides, polyimides, (negative) photo lacquers based on epoxy or polyesters or polyimide based negative resists
Embodiments of a suitable further layer forming a part of the multilayer structure according to the invention comprise an organic semiconductor and/or an electronic device. In the electronic device the conductive layer may be formed from a polymer. Preferably, the electronic device forms a part of a display. The multilayer structure may comprise a substrate which may be further arranged with a planarization layer for providing a substantially smooth surface at least for the permeation barrier.
Preferably, in a flexible display according to the invention the substrate further comprises a planarization layer for providing a smooth surface at least for the permeation barrier. The permeation barrier can comprise a metal layer, or may preferably be implemented from an insulator material.
These and other aspects of the invention will be discussed in more detail herein below.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 presents a schematic view of an embodiment of the flexible display according to the invention.
Figure 2a presents a schematic view of a top view of an embodiment of an active-matrix circuit of the flexible display according to the invention. Figure 2b presents a schematic view of a cross-section of an embodiment of an active-matrix circuit of the flexible display according to the invention.
Figure 3 presents a schematic view of an embodiment of an equivalent circuit of an active-matrix pixel of Figure 1. Figure 4 presents a schematic view of an embodiment of an electrophoretic ink capsule.
Figure 5 presents a schematic view of an embodiment of an electronic device with the flexible display.
DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 presents a schematic view of an embodiment of the multilayer structure according to the invention. In this exemplary embodiment a flexible display 10 is selected for the multilayer structure. The flexible display 10 comprises a substrate 2 on top of which a suitable planarization layer 4 is deposited. In order to protect the subsequent layers from ambient chemicals, such as water and/or oxygen, the flexible display 10 further comprises a permeation barrier 5 comprising, for example, an aluminium oxide or an aluminium oxynitride layer 5a and a protective layer 5b arranged to be chemically inert for the chemical agents used during processing steps of the active matrix layers 6. It is noted that the layers are illustrated schematically and are not intended to be interpreted as the layers' actual respective thicknesses. It will be appreciated that the active matrix layers 6 may comprise at least two layers.
Chemical agents that are usually used during chemical etching comprise acids, salts, alkali/salt solutions. Examples of the suitable materials comprise HNO 3 / HF solutions, potassium hexacyanoferrate(II) / potassium hexacyanoferrate(III) / potassium thiosulphate; KI/I2 solutions, or potassium cyanide / potassium carbonate solutions. Examples of materials that are suitable for use as a protective layer against said chemical agents comprise, for example, polyimides, polyamides, negative photo lacquers based on epoxy or polyesters.
Figure 2a presents a schematic view of an embodiment of an active - matrix circuit 50 of the flexible display according to the invention. The active- matrix circuit 50 comprises a pixel pad 53, a data line 51, a gate line 54 and a semiconductor 55. Figure 2a schematically depicts a cross-section of the pixel pad 53, the data line 51, the gate line 54 and the semiconductor 55. A protective layer 58 is discussed with reference to item 5b of Figure 1, on top of which the gate line 54 is arranged. The gate line 54 is electrically separated from the data line 51 and the pixel pad 53 by means of a suitable insulator layer 56. The semiconductor 55 is positioned on top of the thus formed structure.
In the illustrative example, the active-matrix circuit is processed on plastic foils resulting in an active matrix (AM) backplane that can be integrated into a flexible display. The materials potentially used for the various layers are shown, by way of example, in Table 1. The current stack starts with a highly conductive gate layer {e.g. metal, indium-tin oxide, or an organic conductor like PANI), followed by an inorganic or organic insulator layer, a second conductive layer and an organic semiconducting layer. The organic layers are deposited, for example, by spin-coating. The layers are patterned by photolithography, either by use of the intrinsic photosensitivity of the layers {e.g. the insulator layers) or by use of a photoresist {e.g. for most of the semiconductors and conductors).
Table 1: Examples of materials used for an active-matrix circuit with polymer electronics
Layer Material
Substrate* Polycarbonate, Polyethylene naphtalate, etc
Gate line Au, Al, Cu, Indium-tin oxide, PANI/CSS,
PEDOT/PSS etc Insulator layer Photoresist: HPR504, SClOO, BCB, inorganic layer, etc
Data line/ Pixel Au, Pd, Pt, ZnSnO3, SnO2:F, Ag, etc pad
Semiconductor Poly-(thienylene vinylene), pentacene, etc * Base material that can be coated with a number of permeation barrier layers Figure 3 presents a schematic view of an embodiment of an equivalent circuit 20 of an active-matrix pixel of Figure 2. Active-matrix displays are driven a row-at-a-time. In operation, during one frame time all the rows are sequentially selected by applying a voltage that changes the thin film transistors (TFTs) from a non-conducting to a conducting state. In this line selection time the pixel capacitors (i.e. the total capacitance at the drain side of the TFT) of the selected row are charged to the voltage supplied on the column electrodes. During the remaining frame time (i.e. the hold time) the other rows are addressed. The TFTs are then in their non-conducting state, and the charge on the pixel capacitors is retained. This puts severe requirements on TFT's on- and off-current. For example, for polymer electronics active-matrix back planes with the electrophoretic ink, the typical voltages are a row select voltage of -25 V, a row non-select voltage of +25 V, a column voltage between —15 V and +15 V and a common electrode voltage of 2.5 V. These are relatively high voltages, due to the high voltage E Ink display effect and the fact that polymer electronics devices have to be driven at somewhat higher voltages compared to amorphous silicon devices. The advantage of using the electrophoretic ink as the display effect instead of liquid crystal (LC) material, as is generally used in Liquid Crystal Displays (LCDs), is that the electrophoretic ink is bi-stable. Addressing is therefore only necessary during an image update (~ 1 sec), while the active-matrix is at rest between image updates. The disadvantage of using the electrophoretic ink is that one cannot apply frame inversion, i.e. apply alternatively positive and negative voltages on the columns (data lines) in subsequent frames, without changing the image content. This is commonly done in conventional LCDs to minimize the effect of ionic drift. As shown in Figure 3 a storage capacitor (Cst) is used. It is used so that the requirements on TFT off-current are not too high and in order to reduce optical artifacts that may occur due to unwanted stray capacitances. Figure 4 presents a schematic view of an embodiment 30 of an electrophoretic capsule 33 comprising black microparticles 32 and white microp articles 31. The capsule 33 is subjected to a specific external voltage by means of supplies 35a, 35b for displacing the black microparticles 32 and the white microparticles 31 in the capsule 33. In order to change image content on an electrophoretic ink display, the new image information is written for a certain amount of time (500 ms - 1000 ms). As the refresh rate of the active- matrix is usually higher this results in addressing the same image content during a number of frames (at a frame rate of 50 Hz, 25 to 50 frames). A typical dimension of the capsule 33 is about 20 micrometers. Addressing of the electrophoretic ink from black to white, for example, requires the pixel capacitors to be charged to -15 V during 500 ms to 1000 ms. During this time the white particles drift towards the top (common) electrode, while the black particles drift towards the bottom (active-matrix back plane) electrode. Switching to black requires a negative pixel voltage, and applying 0 V on the pixels does not switch the electrophoretic ink .
As the electrophoretic display effect is bi-stable, the back plane only needs to be driven during an image update. Between image updates the pixel switches on the back plane are not driven. The drive voltages for the electrophoretic ink are relatively high compared to standard LC effects. The polymer electronics devices on the active-matrix back plane are therefore driven at relatively high voltages. For the electrophoretic material to function optimally, there is a specific humidity window in which the display is used. Outside of this humidity window electro optical properties may deteriorate.
Figure 5 presents a schematic view of an embodiment of an electronic device 70 with the flexible display 75. The electronic device 70 may relate to a mobile telephone, an organizer, a palmtop computer, a music replay device, etc. The electronic device 70 comprises a body of the housing 71 about which the flexible display 75 is arranged to be wrapped. It is noted that it is possible to arrange the flexible display 75 so that it is rolled up inside the housing 71 upon storage. In this particular embodiment, the housing 71 comprises a substantially rigid cover 72 arranged to receive the flexible display 75 and to be collapsed to a position 70a or to be extended together to a position 70b together with the flexible display 75. For this purpose the cover 72 comprises hinged bending areas 72a, 72b. The electronic device 70 further comprises the edge protector 73 arranged with rigid portions 73a and with flexible portions 74a, 74b, the latter corresponding to hinged areas 72a, 72b of the cover 72. In this embodiment a back protection of the flexible display 75 is provided next to the side protection. The edge protector is easy to handle, and maintenance procedures can be carried out easily.
It will be appreciated that although specific embodiments of the electronic device according to the invention are discussed separately for clarity purposes, interchangeability of compatible features discussed with reference to isolated figures is envisaged. While specific embodiments have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described in the foregoing without departing from the scope of the claims set out below.

Claims

Claims
1. A multilayer structure comprising a permeation barrier layer for protecting a further layer from elements present in an atmosphere, at least a part of the further layer being conceived to be formed using a process comprising a chemical agent, wherein the multilayer structure further comprises a protective layer that is chemically inert with respect to the chemical agent and conceived to protect at least the permeation barrier from the chemical agent.
2. A multilayer structure according to claim 1, wherein the further layer comprises an organic semiconductor.
3. A multilayer structure according to claim 1 or 2, wherein the further layer comprises an electronic device.
4. A multilayer structure according to claim 3, wherein the electronic device forms a part of a display.
5. A multilayer structure according to any one of the preceding claims, wherein the further layer is arranged on a substrate that is separated from the further layer by the protective layer.
6. A multilayer structure according to claim 5, wherein the substrate further comprises a planarization layer for providing a substantially smooth surface at least for the permeation barrier.
7. A multilayer structure according to any of claims 3 - 6, wherein at least part of the electronic device comprises a metal
8. A multilayer structure according to claim 7 wherein the metal is gold.
9. A multilayer structure according to claim 7, wherein the said processing comprises any one of etching, resist stripping, or a deposition of a still further layer.
10. A multilayer structure according to any one of the preceding claims 3 - 8, wherein the electronic device comprises a first conducting layer formed by a polymer.
11. A multilayer structure according to claim 10, wherein the polymer is doped with an acid, the protective layer being chemically inert to the said acid.
12. A multilayer structure according to claim 11, wherein the acid is camphor sulphonic acid (CSA) or polystyrene sulphonic acid (PSA).
13. A multilayer structure according to any one of the preceding claims, wherein the protective layer comprises an organic material.
14. A multilayer structure according to claim 13, wherein the organic material comprises any one of the following materials: polyimide, photo lacquer, parylene or polyester.
15. A multilayer structure according to any one of the preceding claims, wherein the electronic device comprises an electrophoretic material.
16. A flexible display comprising a multilayer structure according to any one of the preceding claims.
17. An apparatus comprising the flexible display according to claim 16.
PCT/NL2008/050327 2007-06-01 2008-05-30 A multilayer structure comprising a chemically inert protective layer WO2008147191A1 (en)

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US9947882B2 (en) 2015-09-25 2018-04-17 Apple Inc. Electronic devices with robust flexible displays

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WO2000065670A1 (en) * 1999-04-28 2000-11-02 E.I. Du Pont De Nemours And Company Flexible organic electronic device with improved resistance to oxygen and moisture degradation
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CN101852963A (en) * 2010-05-19 2010-10-06 友达光电股份有限公司 Display device
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US9947882B2 (en) 2015-09-25 2018-04-17 Apple Inc. Electronic devices with robust flexible displays

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