GB2439636A

GB2439636A - Organic devices

Info

Publication number: GB2439636A
Application number: GB0712216A
Authority: GB
Inventors: Stephen Clemmet; Deborah Stokes
Original assignee: POLYMERTRONICS Ltd
Current assignee: POLYMERTRONICS Ltd
Priority date: 2006-06-28
Filing date: 2007-06-25
Publication date: 2008-01-02
Also published as: WO2008001051A3; GB0612777D0; WO2008001051A2; GB0712216D0

Abstract

A device active layer comprises an inkjet printed polymer layer comprising a polymer network polymerised in a free-air atmosphere using a UV light source. Fabrication methods for forming organic electroluminescent displays, organic photovoltaic devices and organic touch sensors are disclosed.

Description

Multi-Layered Ultra-Violet Cured Or2anic Electronic Device The

presented invention relates to a multi-layered organic electronic device and in particular but not limited to an organic, or polymer light emitting diode (OLED / PLED).

The use of semi-conducting polymers in the fabrication of electronic devices and in particular light emitting diodes (LEDS) is well known. In their simplest form Organic LED's (OLED's) typically comprises a multi-layer structure fabricated on a substrate, including an anode, a multi-layer active polymer portion and a cathode. The substrate is typically glass, on which the anode material has been deposited. Typically, the anode comprises a transparent, hole-injecting material such as indium tin oxide (ITO), or the like, and the cathode comprises a low work function material such as aluminium, or calcium which acts as an electron injector.

The anode and cathode are typically deposited by a sputtering process. Sputtering requires a vacuum environment and an ion laser to knock' atoms from a metal target for deposition on the substrate.

The active polymer portion may comprise multiple layers of different types but in its simplest fonn comprises a single emissive layer of thickness less than lOOnm. The cathode comprises an appropriate metallic layer, which acts as the negative contact for the device. In operation a voltage (typically of magnitude 3V to 9V) is applied between the contacts to induce light emission from the emissive layer as a result of electroluminescence.

The most widely perceived application of organic LED technology is in the fabrication of thin film displays. In such displays each organic LED generally represents a single pixel in the case of monochromatic displays, and one of three pixel components (red, green, blue) in colour, flexible displays. Organic LED displays have the significant advantage over conventional amorphous / poly-silicon thin film transistor liquid crystal displays (TFT-LCD) that OLED's do not require backlighting. OLED displays can therefore be manufactured without the need for complex and expensive backlighting circuitry.

However, in display applications device quality and longevity are vital in order for the resulting product to be commercially viable. Organic materials, however, tend to degrade rapidly over time when compared to silicon based alternatives. Furthermore, the thin (typically < 1 OOnm) films of emissive polymer used are extremely vulnerable to pinholes and the like, which result from dust, or other contaminant particles settling on top of, or beneath the active layer.

The perception, therefore, is that the development of OLED's should focus on research into manufacturing technologies and/or device architectures, which minimise the risk of contamination and maximise the life of the device. Technologies and architectures, which do not meet these requirements are therefore rejected as being unsuitable.

The drive to produce higher quality films with greater longevity means that the technology for producing the films is relatively expensive. It is known, for example, to deposit a monomer, oligomer, photo-initiator and emissive mixture onto a substrate and then to polymerise and cross-link the mixture using a ultra-violet (UV) wavelength argon, or nitrogen ion laser. The use of laser polymerisation helps to provide controlled polymerisation but requires relatively expensive, cumbersome technology.

A suitable emissive material requires a high enough percentage of active polymer relative to a UV-curable resin material in order to achieve the required electronic characteristics.

The resin contains photoinitiators in order to promote solidification of the liquid film into a substantially solid layer upon application of a UV light. The properties of conventional electroluminescent materials result in a viscous or sludge-like mixture which is difficult to handle. Such materials are typically applied to a surface using industrial coating processes such as screen printing, spin coating or the like.

Whilst OLED technology has potential for high end consumer products such as computer and TV displays it precludes many applications for which investment in such technology is unrealistic for bespoke low volume products.

For a laser curing system, said laser is a focused, polarised light source. To create an appropriate light beam for curing purposes, a diffraction grating, or mechanical scanning system is required to cure a device. This adds cost, complexity and maintenance to the manufacturing system.

Furthermore, the laser cured polymer films are processed in a nitrogen, or other inert gas environment, partly to limit the effects of oxidation, and partly to reduce contamination.

This adds further to process complexity, cost, and cycle time.

By way of example, the competing technology in the field of two-dimensional light emitting displays involves an electroluminescence screen printing process. Such processes require bespoke tooling for each display, which results in product lead times of four to eight weeks. When one considers the significant potential of such light-emitting displays in the field of marketing and advertising, it will be apparent that such lead times are unacceptable. Thus there is a significant barrier inhibiting the widespread implementation of this technology.

Such technological barriers are particularly problematic in light of the recent growing demand for interactive advertising signage, for which such light emitting displays would be well suited.

It is the object of the present invention to provide an organic multi-layered electronic device, which is simple and inexpensive to manufacture, and a simple inexpensive method for fabricating such a device in small to large quantities.

According to one aspect of the present invention there is provided a multi-layered organic electronic device comprising: a substrate, first and second contact layers, and an active portion; said first contact layer being formed on said substrate, and the active portion being digitally inkjet printed between said first and second contact layers; wherein said active portion comprises an active polymer layer; and wherein said polymer layer comprises a polymer network polymerised using a UV light source.

According to a second aspect of the present invention there is provided a method for fabricating a multi-layered organic electronic device comprising: providing a substrate; fabricating a first contact layer on said substrate; fabricating an active portion on said first contact layer, and fabricating a second contact layer on said active portion; wherein said fabrication comprises printing a monomer based liquid on said first contact layer, and UV curing said liquid in a free air environment to form an active polymer layer.

The polymer network may be polymerised in free air or else in a controlled inert environment, such as for example and nitrogen environment.

In a preferred embodiment, the active portion is inkjet printed. Preferably the active polymer layer and one or more further layers are inkjet printed. Yet more preferably, the first and second contact layers and the active layer are printed.

The present invention is particularly advantageous since it allows suitable organic materials to be sprayed down using conventional inkjet printers. Thus the present invention can be fabricated by retrofitting well-established existing technology. It will be appreciated that the viscous nature of conventional materials is totally unsuitable for atomisation in order to produce a fine spray upon passage through a printer noIe. The present invention may be applied using conventional flat bed or roll-to-roll printers.

Conventional printers typically use UV lamps to cure inks and the Applicant has discovered the additional benefit that certain wavelengths emitted from such conventional lamps can be used to effectively cure the polymer layer according to the present invention.

Thus existing inkjet printers can be adapted for use in printing a multi-layered organic electronic device. This has the significant benefit that the production of marketing and advertising materials such as posters and the like can be achieved with short lead times and without the need to establish industrial production facilities or the retooling costs associated with screen printing.

By retro-fitting the present invention on to existing printer platforms, organic devices can be printed with UV curable colour inks as a single printing process.

In addition, the present invention has been found to be particularly suited to marketing or advertising materials since advertising space is often sold for predetermined time periods such as a week or a fortnight. Exhibition and other special events are typically for one to three days. 45% of all digital prints created using platforms as illustrated are for advertising purposes. Globally, this equates to over 340,000,000m2 of printed graphics per annum. Thus the device according to the present invention is not required to operate indefinitely and degradation of the organic materials can be mitigated over the relevant time periods.In one embodiment, one or more layers are tiered. Thus the outer edge of the device may comprise a series of discontinuities or steps formed by offset edges of each adjacent layer. Such a staggered arrangement better accommodates registration errors between the layers. A mask may also be provided over the edges of the adjacent layers to conceal any edge effects.

In one embodiment, the polymer layer is an acrylated polymer-matrix.

According to a third aspect of the present invention there is provided a display comprising a display area, wherein: said display area comprises at least one organic electronic device according to the first aspect.

In one embodiment, the display is disposable. Preferably the display is inkjet printed. It will be appreciated that the present invention is advantageous in that a device according to the present invention can simply be printed in one or more selected portions of the display. Thus certain text and/or graphics, such as for example logos or slogans, can be highlighted according to the present invention, whilst the remainder of the display is printed in a conventional fashion.

Furthermore the present invention can be used in conjunction with conventional coloured inks to produce particularly effective visual displays.

According to a fourth aspect of the present invention there is provided a touch sensitive display comprising at least one organic electronic device according to the first aspect.

According to a fifth aspect of the present invention there is provided a display comprising a display area and a touch sensitive area, wherein: said display and touch sensitive area comprises at least one organic electronic device according to the first aspect.

The touch sensitive area may comprise a keypad, or the like.

According to sixth aspect of the present invention there is provided a display comprising a display area, wherein: said display area comprises at least one electronic device fabricated using the method of the second aspect. Further preferable features of the invention are recited in the dependent claims.

The present invention is not restricted solely to marketing materials but rather the present invention effectively removes a predominant barrier to market for the application of light emitting devices to many printed media. Generally, but not limited to; flexible plastics, glass and metals.

It will be appreciated that references to inkjet printing within the present application cover modes printing in which a fine spray is formed upon passage of fluid through nozzles. The spray impinges on the surface to be printed in a reproducible fashion. Thus in the context of inkjet printing, the term "printing" is not to be interpreted as being limited solely to printing by way of stamping or impression using a die. Furthermore it will be appreciated that references to photoemissive materials herein cover any light-emitting materials.

The invention will now be described, by way of example only, with reference to the attached figures in which: Figure 1 shows an embodiment of an organic light emitting diode according to the invention; Figure 2 shows an embodiment of an advanced organic fight emiting diode according to the invention; Figure 3 shows an embodiment of an organic capacitive touch sensor according to the invention; Figure 4 shows an alternative embodiment of an organic capacitive touch sensor according to the invention; Figure 5 shows a tiered embodiment of a deposited device according to the present invention; Figure 6 shows an embodiment of a deposited device with an edge effect mask; Figure 7 shows an embodiment of a deposited device with tracking and supporting resin around said device; Figure 8 shows a simplified flow chart illustrating a process for fabricating of an electronic multi-layered organic device according to the invention; Figure 9 shows a simplified flow chart illustrating an advanced process for fabricating of an electronic multi-layered organic device according to the invention; Figure 10 shows a diagram of the principal apparatus used in the curing process of figures 8, 9, inoperation; Figure 11 shows a diagram of the principal apparatus used in the dot-fixing process of figure 9, in operation; Figure 12 shows the spectral response of a mercury metal halide UV light source suitable for use in the curing process of figures 8, 9; Figure 13 shows the spectral response of a mercury metal halide-free UV light source suitable for use in the curing process of figures 8, 9; Figure 14 shows the spectral response of a UV emissive LED light source suitable for use in the dot-fixing process of figures 9; Figure 15 illustrates an application of the organic light emitting diode of figure 1 or 2; Figure 16 illustrates an application of the organic light emitting diode of figure 1 or 2; Figure 17 illustrates an application of the touch sensor of figures 3 or 4; Figure 18 illustrates an application of the organic light emitting diode of figure 1 or 2 and the touch sensor of figure 3 or 4; Figure 19 illustrates a typical flatbed wide-format inkjet printer for printing UV curable colour prints.

Figure 20 illustrates a typical wide-format printer-head assembly.

Figure 21 illustrates a principle print-head that may be used to print the component parts of figures 1,2,3, or4; Figure 22 illustrates an advanced embodiment of a print-head that may be used to print the component parts of figures 1, 2, 3, or 4; and Figure 23 illustrates a further, preferred, advanced embodiment of print-head that may be used to print the component parts of figures 1,2,3, or 4; In figure 1 a first embodiment of a multi-layered organic electronic device is shown generally at 20. The device 20 comprises an organic light emitting diode (OLED) having an active portion 22, and two contact layers 12, 18, fabricated on an appropriate substrate 10. It will be appreciated that the OLED 20 may also be referred to as a polymer light emitting diode (PLED).

A first of the contact layers 12 is fabricated directly onto the substrate 10 and comprises a conducting film of electronic properties suitable for the film 12 to function as an anode.

Typically, for example, the contact layer 12 comprises may comprise an appropriate conducting polymer film. Alternatively, or additionally, the contact layer 12 comprises a relatively low work function transparent material such as ITO, or the like, suitable for acting as acting as a hole-transporter. The use of a conducting polymer film, however, is particularly advantageous because it can be printed onto the substrate relatively cheaply, whilst a completely transparent polymer film is desirable, especially for pixelated displays, many applications only require a semi-transparent / translucent film. It will be appreciated that the contact layer 12 may comprise a single layer, or may comprise a plurality of different material layers.

The active portion 22, is fabricated onto the first contact layer 12 and comprises first and second active semi-conducting polymer layers. The first polymer layer 14 comprises a p-type' emissive layer deposited on the anode contact layer 12. The second polymer layer 16 comprises an n-type' electron-transporter layer 16 fabricated on the hole-transport layer 14. The active layers 14, 16 may comprise any suitable polymer-matrix, or the like.

Each layer thickness is detennined by the substrate's surface, the drop size, the volume of liquid supplied to the substrate and fluid dynamic properties of the material used such as viscosity and surface tension. For 1 Op1 drop size, layers for UV curable inks are approximately 8jtm and I tm for lpl drop sizes.

A second of the contact layers 18 is fabricated directly onto the second polymer layer 16 and comprises a conducting film of electronic properties suitable for the film 18 to function as a cathode. Typically, for example, the cathode comprises an appropriate conducting polymer film. Alternatively, or additionally, the contact layer 18 may comprise a relatively low work fimction material such as calcium, aluminium, magnesium, a magnesium/silver alloy or the like, suitable for acting as acting as an electron-injector. The use of a conducting polymer film is particularly advantageous because it can be printed onto the active layer relatively cheaply. It will be appreciated that the contact layer 18 may comprise a single layer, or may comprise a plurality of different material layers.

The active portion 22 is configured such that the application of an appropriate potential difference across the contact layers 12, 18, causes electrons to be injected into the emitter 16 from the cathode, and holes to be injected into the hole-transport layerl4 from the anode. The polymer characteristics are selected, and film thicknesses engineered such that charge carriers combine to form tightly bound electron-hole pairs (excitons), near the interface between the polymer layers, thereby to decay with the emission of light through the transparent anode. The band gaps of the active polymer layers are configured to give desired emission characteristics, for example, to give visible light of a required wavelength and hence colour (according to X=h/E).

The substrate 10 comprises a flexible thin insulating sheet material, for example, a clear plastics material, vinyl. or the like. Whilst a flexible plastics, or other material is preferable for many applications the substrate could comprise glass, or a rigid plastic.

A device according to any of the described embodiments of the present invention may be further provided with a scratch resistant encapsulation polymer layer (not shown) to protect the device once fabricated. Alternatively if the uppermost layer of the device is a polymer layer it could be fabricated to act as the scratch resistant encapsulation layer.

It will be appreciated that the device could alternatively be fabricated onto a non-transparent substrate. In such devices the anode contact layer could comprise a reflective conducting polymer layer and the cathode a transparent, semi-transparent, and/or translucent layer such that the photons generated in the active layer are visible through the cathode layer.

In a further embodiment of the multi-layered organic electronic device the cathode conducting layer 18 is fabricated onto the substrate, the active portion 22 onto the cathode layer 18 and the anode layer 12 onto the active portion 22. The active polymer layers 14, 16 in such a device are reversed, and the transparency of the substrate, cathode, and/or anode layers selected according to the application. The order of the anode and cathode layers may also be reversed.

Another embodiment of the multi-layered organic electronic device the cathode conducting layer 18 and the anode layer 12 are the same polymer, ITO type, or similar.

Both being transparent, semi-transparent, and/or translucent.

In another embodiment the multi-layered organic electronic device is configured as a photovoltaic device (PVD). In such a device the active layer 22 is configured to generate a voltage in response to light of sufficient intensity, incident on the active layer 22 through the anode, or cathode. In such a device, unlike the OLED/PLED, the active layer is configured to separate the opposing charges, to avoid recombination and photon emission.

In figure 2, a further embodiment of a multi-layered organic electronic device is shown generally at 36. The device 36 comprises an organic light emitting diode (OLED) having an active portion 38, and two contact layers 26, 34, fabricated on an appropriate substrate 24. It will be appreciated that the OLED 36 may also be referred to as a polymer light emitting diode (PLED).

Figure 2 with respect to figure 1 can be cross-referenced: Layer 24 is equivalent to layer 10, layer 26 is equivalent to layer 12, layer 30 is equivalent to layer 14, layer 32 is equivalent to layer 16 and layer 34 is equivalent to layer 18. It is appreciated that the explanations and attributes associated with the layers and substrate of figure 1, may also be applied to device 36.

The hole-transport layer 28, enhances the movement of holes from the emissive layer 30.

The effect being an increased light output of device 36, relative to device 20. Details of the hole-transport layer 28 will be omitted as a number of conventional materials will be apparent to the person skilled in the art.

In figure 3 a further embodiment of a multi-layered organic electronic device is shown generally at 52. The device 52 comprises an organic capacitive touch sensor having a sensing portion 50, and first and second contact layers 42, 46, fabricated on an appropriate substrate 40. The use for which may be a printed keypad, as illustrated in figures 17, 18.

Device 52 is depositioned with its layers 42, 44,46, directly onto the substrate. The layers are depositioned as illustrated in 52 such that they are oriented substantially perpendicular to, or else at an angle to, the plane of the substrate.

The contact layers 42, are fabricated directly onto the substrate 40 and comprises a conducting film of electronic properties suitable for the film 42, to function as an electrode for the sensor 52. Typically, for example, the film comprises an appropriate conducting polymer film. It will be appreciated that the film need not be a polymer and may alternatively, or additionally comprise a suitable non-organic conductive material such as calcium, aluminium, magnesium, a magnesium/silver alloy, or the like.

The sensing portion SO, is fabricated directly onto the substrate 40 and comprises first and second semi-conducting active polymer layers 44, between which a thin dielectric layer 46 is provided. The polymer layers 44 comprise an n-type', or p-type' layers. The dielectric layer 46 is between the active polymer layers 44. The active polymer layers 44 may comprise any suitable polymer, for example, acrylate polymers (polyacrylate), acrylated polymer-matrix, or the like. The dielectric layer 46, comprises of an insulating material, which may be an acrylate.

It will be appreciated that the active layers could alternatively comprise a conducting layer as opposed to a semi-conducting layer. Semi-conducting layers, however, have the advantage of ease of fabrication.

The dielectric layer 46 is provided at the interface between the active polymer layers 44 and may comprise any suitable insulating material, for example, an insulating polymer, or an oxidised layer of one, or both active layers 44. The thickness, area and dielectric properties of the film are configured to give a desired capacitance.

Typically, for example, the film comprises an appropriate conducting polymer film.

Hence, when a charge is induced in the sensing region 50, there is a corresponding change in charge on the first electrode, which may be sensed by appropriate control circuitry. The change in electric field may be induced by the presence of a person's fmger 48.

It will be appreciated that unlike the OLED and the photovoltaic device (PVD) neither contact layer 42 of the capacitive touch sensor 52 need not be transparent. It will be further appreciated that the contact layers 42 may each comprise a single layer, or may comprise a plurality of different material layers.

It will be appreciated that a simplified capacitor could potentially be produced by fabricating an insulating (dielectric) polymer layer of appropriate thickness between the two contact layers without additional layers 42 The active portion 50 is configured such that a person touching the device, or bringing a finger, or the like into close proximity to the second contact layer induces a change in charge in the contact layers, which may be sensed and responded to by external circuitry.

The substrate 40 comprises a thin insulating sheet material, for example, a flexible clear, or non transparent / translucent plastics material, or the like. Alternatively the substrate could comprise glass, rigid plastic, or other material.

The device 52 may be further provided with a scratch resistant polymer layer (not shown) to protect the device once fabricated.

In figure 4 a further embodiment of a multi-layered organic electronic device is shown generally at 66, in which the layers are arranged generally parallel with the substrate 54.

The device 66 comprises an organic capacitive touch sensor having a sensing portion 68, and first and second contact layers 56, 64, fabricated on an appropriate substrate 54.

The use of the device of figures 3 or 4 may be a printed keypad, as illustrated in figures 17, 18. Accordingly the touch sensitive area may be printed with indicia to delineate different areas which a user is intended to touch. Additionally, or else alternatively, indicia may be provided to indicate areas which are or are touch sensitive. The indicia typically provide a visual representation of a function associated with a touch sensitive area or key.

It will be appreciated that devices 52, 66 may be deposited to create multilayer devices, thereby increasing said devices capacitance. Laying said devices increases the capacitance by a factor of N-i, where N is the total number of plates of said device.

It will be appreciated that the detection of a user's presence, or contact with the device 52, 66, as indicated at 48 and 62 by the user's digit, is detected by a change in electrical properties of said device. Where said device is a component of an electronic circuit, said presence of 48,62 may be frequency, or amplitude variations.

The first of the contact layers 56 is fabricated direciiy onto the substrate 54 and comprises a conducting film of electronic properties suitable for the film 56 to function as an electrode for the sensor 66. Typically, for example, the film comprises an appropriate conducting polymer film. It will be appreciated that the film need not be a polymer and may alternatively, or additionally comprise a suitable non-organic conductive material such as calcium, aluminium, magnesium, a magnesium/silver ahoy, or the like.

The sensing portion 68, is fabricated onto the first contact layer 56 and comprises first and second semi-conducting active polymer layers 58, between which a thin dielectric layer 60 is provided. The first and second polymer layers 58 comprise of n-type', or p-type' layers, the first of which is deposited on the first contact layer 56 and the second of whichis deposited on the dielectric layer 60. The active polymer layers 58 may comprise any suitable polymer, for example, acrylate polymers (polyacrylate), acrylated polymer-matrix, or the like. The dielectric layer 60, comprises of an insulating material, which may be an acrylate.

It will be appreciated that the active layers could alternatively comprise a conducting layer as opposed to a semi-conducting layer. Semi-conducting layers, however, have the advantage of ease of fabrication. Further, the active layers may both be the identical, or different p-type' layers.

The dielectric layer 60 is provided at the interface between the active polymer layers 58 may comprise any suitable insulating material, for example, an insulating polymer, or an oxidised layer of one, or both active layers 58. The thickness, area and dielectric properties of the film are configured to give a desired capacitance.

The second of the contact layers 64 is fabricated directly onto the second polymer layer 58 and comprises a conducting film of electronic properties similar to the first contact layer 56 to allow the film 64 to function as a second electrode for the sensor 66.

Hence, when a charge is induced on the second contact layer 64, there is a corresponding change in charge on the first electrode, which may be sensed by appropriate control circuitry.

It will be appreciated that unlike the OLED and the PVD neither contact layer 56, 64 of the capacitive touch sensor 66 do not need be transparent. It will be further appreciated that the contact layers 56, 64 may each comprise a single layer, or may comprise a plurality of different material layers.

It will be appreciated that a simplified capacitor could potentially be produced by fabricating an insulating (dielectric) polymer layer of appropriate thickness between the two contact layers without additional layers 58.

The active portion 68 is configured such that a person touching the device, or bringing a fmger 62, or the like into close proximity to the second contact layer induces a change in charge in the contact layers, which may be sensed and responded to by external circuitry.

The substrate 54 comprises a thin insulating sheet material, for example, a flexible clear, or non transparent I translucent plastics material, or the like. Alternatively the substrate could comprise glass, rigid plastic, or other material.

The device 66 may be further provided with a scratch resistant polymer layer (not shown) to protect the device once fabricated.

When printing device(s) 20, 36, 52, 68 on flexible or rigid metal substrates, an insulating layer (not shown) may be required between said device and substrate. Said insulating layer may be the dielectric material (if 58 is not by oxidation). For when printing said insulator on substrate, additional area must be printed to accommodate the printers XY offset print tolerance. Thus protecting against printing anode, cathode and/or active layer on said metallic substrate.

Figure 5 illustrates the accommodation of a given X-Y plotter's tolerance. Subsequent layers are printed with an inward step of a units, when printing device 72, of composition 74,on substrate 70. It will be appreciated that the inward step is greatly exaggerated in the figure for visual clarity and that the magnitude of a can in reality be prescribed to be at least the tolerance of a given X-Y plotter.

The stepped or tiered arrangement of figure 5 can be applied to any embodiment of the present invention.

If printing with on platforms with UV curable coloured inks and if said ink is of suitable qualities, said ink could be used as either/both the insulating layer if printing on metallic substrates and/or the dielectric material 58.

It will be appreciated that a plurality of multi-layered organic devices of different types may be fabricated on a single substrate to produce more complex integrated circuits. The control circuitry for each device may be fabricated onto the same medium for interface with any external control circuits, if required. External control circuits may be fabricated in a conventional manner, for example, on a flexible printed circuit board (PCB) and may include, for example, power supplies, decision making units, interface circuitry for onward connection to other electronic circuits, or the like.

Figure 6, illustrates the use of a non-conductive polymer matrix 78 to overlap the edge of OLED device 20, 36, by an distance of units. Edge effects of light emitting devices may be non uniform with respect to the middle of the device 78, upon substrate 76. A mask of this type is typically applied over the edge of the device once all the layers have been laid down by the printer.

In figure 7, device 90 illustrates how device 72 may have its electrodes supported to the active region 92. The device is depositioned directly on to substrate 84 and a non-conducting polymer network 88, is depositioned around the device as shown. Thus a discrete active region 92 is surrounded by a non-conducting material. The anode 86 and cathode 87 pass to and from the active region 92 across the non-conducting polymer region 88.

According to this embodiment, one or more electroluminescent sections of a display can be printed. The cathode 87 is typically transparent and the polymer network 88 may be opaque in order to provide the desired finish. Individual anode 86 and cathode 87 portions may be provided in respect of each active region 92 or else a common anode and cathode layer may serve a plurality of individual active portions.

In figure 8, a simplified flow chart shown generally at 106 illustrates a process for fabrication of a multi-layered organic electronic device according to the present invention.

The process begins with substrate preparation 104, during which the substrate material is prepared for the printing of the polymer layers. If a non-organic anode I cathode is to be formed on the substrate then it is during substrate preparation that the contact layer is formed. Where, for example, the substrate is an Indium Tin Oxide (ITO) coated glass, the preparation will involve coating the glass with ITO. Preparation may also include steps to promote polymer adhesion to the substrate, surface cleaning, or the like.

The process of substrate preparation 104 may require the substrate to be cleaned of contaminates and free of water upon said substrate. Cleaning said substrate may be by the use of a solvent based cleaner such as isopropronal, non-halogenated products, or the like. Drying of substrate at 104, prior to the deposition steps, is by the use of incident infra-red light energy as illustrated in figure 10. The applied heat energy to said substrate from said UV source may be controlled by the time at which said UV source is maintained at a given location on the said substrate. For the application of an inkjet printing platform, the temperature of the substrate can be controlled by altering the speed of said platform's print-head, whilst the lamp is at full power. If said platform's UV sources have a shutter mechanism to block UV exposure and if the substrate is susceptible to UV degradation, then said shutter mechanism may be closed, applying only heat and not UV radiation to dry the substrate of fluid.

It will be appreciated that the presence of the thermal energy from the UV system illustrated in figure 10, will assist in maintaining a low water vapour environment.

After the substrate is prepared at 104, a polymerisable ink comprising a liquid formed from a UV reactive resin (monomer), UV reactive thinner (oligomer) and photoinitiator, combined with urethane OLED is printed 102 onto the prepared substrate. The ink is configured for polymerisation by IJV exposure into a polymer film having the desired properties for the layer being deposited, for example, conducting and/or transparent/translucent' reflective properties as appropriate for polymer anodes/cathodes.

Similarly, in the case of the active polymer layers of an OLED, or other such device the ink will be engineered to be curable into layers having appropriate semi-conducting/conducting properties such as, for example, appropriate band gap width and Fermi level positioning.

The liquid monomer ink is printed in a free-air environment, generally using a wide format (WE), or large format (LF) digital UV printer of known design. Typically, for example, the ink is printed from a printer of the type used for printing advertising materials, or the like. Such printers typically have a resolution of 6-40 pa, which is sufficient for the fabrication of the devices concerned, 200-600dpi. The dot resolution for the OLED-s need not need to be exact for many applications. Whilst, X-Y offset may affect performance and is therefore generally perceived as being undesirable, acceptably functioning OLED-s may be fabricated where performance is not such an issue, or can be managed with external circuitry.

If the printed layer is to be polymerised before any subsequent films are to be printed (negative path of decision step 100) then the process goes into a UV curing step 98. It will be appreciated that whilst the UV curing and printing steps are described as separate steps for the purposes of clarity, the steps could be combined such that the polymer layer is cured, in situ, as it is being printed. Each layer is sprayed, or otherwise individually fabricated.

Alternatively, if a further printed layer associated with a further polymer layer is to be printed (positive path of decision step 100) then the printing step is repeated with an ink having appropriate properties. Several uncured layers may be built up in this way prior to polymerisation of the layered film, thereby reducing oxidation between layers. Cure depth is a function of the incident UV wavelength. Curing time for thick, or multiple layers will be longer than for single/thinner layers.

The determination of whether curing should be carried out before a subsequent liquid monomer layer is printed is dependent on several factors including: the required characteristics of the interface between the layers; the thickness of the deposited films; the avoidance of over-curing layers deposited early in the fabrication process; the minimisation, or maximisation of oxidation between layers; and other optimisation issues.

For example, the active layers in the OLED may both be deposited, prior to curing, to minimise oxidation between the layers. Contrastingly, oxidation could form at least part of the dielectric layer of the capacitive sensor, and so the first active layer may be deposited, cured and then oxidised, prior to deposition and curing of the dielectric layer / second active layer.

UV curing is completed in a free-air environment using a high intensity source of multi-spectra UV light. The UV source will comprise a mercury metal halide lamp (A-type bulb), mercury metal halide-free lamp (H-type bulb), or UV LED of mixed wavelength spectrum in the range 200-400nm. UV LED's offer the advantage over metal halide lamps that they can be instantly activated and deactivated without the need for warm up periods for optimum performance.

Halide affords additional spectra useful for depth cure. The power to A-type bulbs can be as low as 40% of the bulbs' maximum power rating. Below which the bulbs temperature drops and the halide comes out the gas solution. For H-type bulbs, the power level can be as low as 20% of said bulbs' maximum power rating. Increased power control using an H-type bulb affords better curing control of dosage, whereas an A-type bulb has better intensity characteristics. Both are recognised important parameters of UV curable ink.

Figure 9 a flow chart illustrating another process for fabrication of a multi-layered organic electronic device is shown generally at 124. The process begins with substrate preparation 122, which may be equivalent to step 104 in figure 8 and during which the substrate material is prepared for the printing of the polymer layers. If a non-organic anode or cathode is to be formed on the substrate then it is during substrate preparation that the contact layer is formed. Preparation may also include steps to promote polymer adhesion to the substrate, surface cleaning, or the like.

The presence of the thermal energy from the UV system illustrated in figure 10, will assist in maintaining a low water vapour environment which can have significant benefits on the operation of the product.

Printing step 120 in figure 9 is equivalent to printing step 102 in figure 8 as described above.

At step 116 a first stage of curing is carried out by way of dot fixing, which is generally not a through-cure process of the device. The wavelengths emitted and their respective intensity may not be sufficient to 100% cure said device. Most UV curable resins are polymerise-initiated by 365nm. A UV emissive LED can be instantly switched on and off. They are also small enough to integrated into an inkjet print-head, or close by to it.

If the printed layer is to be polymerised before any subsequent films are to be printed (negative path of decision step 114) then the process goes into a UV curing step 112.

Thus curing is essentially performed as a two stage process, with an intennediate dot fixing step followed by a through-curing step performed by a UV lamp. It will be appreciated that whilst the UV curing and printing steps are described as separate steps for the purposes of clarity, the steps could be combined such that the polymer layer is cured, in situ, as it is being printed. Each layer is sprayed, or otherwise individually fabricated.

Alternatively, if a further printed layer associated with a further polymer layer is to be printed (positive path of decision step 110) then the printing step is repeated with an ink having appropriate properties. Several uncured or partially cured layers may be built up in this way prior to polymerisation of the layered film, thereby reducing oxidation between layers. Cure depth is a function of the incident UV wavelength. Curing time for thick, or multiple layers will be longer than for single/thinner layers.

The UV curing step 112 is carried out under the conditions described in relation to step 98 of figure 8 and the factors affecting the decision of whether curing should be carried out before a subsequent liquid monomer layer is printed are discussed above. In the event that such factors require it, it is also possible to fully cure each layer individually prior to application of a subsequent layer as indicated at 110.

For both the processes of figures 8 and 9, the removal of moisture form the finished product can greatly enhance the operational life of the device. It will be appreciated that conventional UV arc lamps emit a broad spectrum of radiation, including visible light and JR radiation. Thus the UV lamp can also be used to heat the device during curing and drive off any unwanted water from the final product. This is of particular benefit when inkjet printable materials are used, which typically have lower viscosity than conventional electroluminescent materials.

In figure 10 curing apparatus suitable for use in the curing of the organic device are shown, in operation, generally at 136. The apparatus is comprises a reflector portion 132, a UV arc lamp source 134 and clear quartz window 130. The spectral output of the UV source is illustrated in figures 12 and 13. The reflector 132 is shaped in a generally curved proffle about the UV source 134. The UV source 134 and reflector 132 are located relative to each other for the focusing of light emitted by the source 134 and reflected by the reflector 132 onto the device 128. The reflector 132 is shaped to provide a focused region of UV light rays 138 at a predetermined vertical distance y' between the substrate 126 and quartz window 130. The reflector may, for example, be parabolic. In operation, the organic device 128 being processed (on substrate 126) is located beneath the apparatus 130 such that the focussed UV light rays 138 are incident on the upper surface of the film to be cured.

In figure 11 dot-fixing apparatus suitable for use in the dot-fixing of the organic device are shown, in operation, generally at 150. The apparatus is comprises a UV LED source 146 and slot aperture window 148, of light absorbing material 144. UV light rays 152 at a predetermined vertical distance 6' between the substrate 140 and window 148, dot-fix -the device to the substrate. In operation, the organic device 142 being processed (on substrate 140) is located beneath the apparatus 144 such that the focussed UV light rays 152 are incident on the upper surface of the film to be dot-fixed.

It will be appreciated that dot-fixing or through-curing may also be carried out from beneath the substrate if it is transparent. Furthermore processing cycle time could be reduced by dot-fixing or through-curing two layers substantially simultaneously with UV sources provided above and below the device, each source being individually tuned to the wavelength appropriate to the specific polymer layer.

The UV light source apparatus 136, 150 may be fitted to the print/spray head of the printer, and may be the same source as used by the printer for dot-fixing or through-curing UV curable coloured inks in the printing of images on posters, or the like. Separate print/spray heads may be provided for fabrication of the organic device and for the standard printing of coloured inks, thereby allowing organic devices to be fabricated along side printed images on the same substrate.

Figure 12 shows a typical spectrum of a mercury metal halide lamp, whilst figure 13 is that for a mercury metal halide-free lamp. Both are suitable for free-air curing of the printed fihns. As illustrated in figure 8, 9 the spectrum includes peaks in the UV-A (315nm -380nm), the UV-B (280nm -315nm) and the UV-C (200nm -280nm) regions.

S UV-A region peaks are particularly beneficial in the curing of thick polymer layers, UV-B region peaks support and maintain the triggered cross-linking reaction and promotes improved curing over the shorter wave-length peaks, and UV-C region peaks are beneficial for the controlled polymerisation of thin films and for ensuring complete curing.

Alternative metal halide lamps to mercury gas fill sources are listed in table 1 (following).

The type of lamp used in the curing process may be selected, according to its mixed wavelength characteristics, to give optimised polymerisation in dependence on the structure being cured: Gas Fill Indium (In) Iron (Fe) Iron Iodide (Fe!) Iron-lead (FePb) Gallium (Ga) Gallium-lead(GaPb) Gallium-lrori(GaFe) Gallium Iodide (Ga!) Mercury Iron(HgFe) Mercury Indium (HgIn) Mercury Gallium (llgGa)

TABLE!

Figure 14 shows a typjcal spectrum of 365nm and 375nm UV emissive LED's. Both are suitable for free-air dot-fixing of the printed films. 365nm is the preferred device, though a 375nm device may have sufficient energy its sidebands to dot-fix. UV emissive LED's will partially cure an organic device. As illustrated in figure 9 the spectrum includes peaks in the UV-A (31 5nm -380nm). There is no response the UV-B (280nm -31 5nm) and the UV-C (200nm -280nm) regions. UV-A region peaks are particularly beneficial in the curing of thick polymer layers.

S A plurality of parameters of the UV light are controlled to ensure optimum curing of the layer, or layers being cured. The photon flux at a given depth within the polymer is a function of the polymers' absorbance and the incident flux at a given wavelength according to the Bouger-Lainbert law. A low irradiance for a relatively long period is not equivalent to a higher irradiance for a short period, even if the overall the energy is the same. Typically peak intensity and energy are used as control parameters. Controlled UV peak intensity and dosage, for example, may be used to accurately control the curing process whilst maximising longevity of the organic device being fabricated.

If necessary the UV parameters are controlled to minimise the effect of curing newly deposited layers, on existing layers cured earlier during fabrication, by avoiding over exposure of the existing cured layers to UV radiation. Such over exposure can lead to significant reductions in longevity.

Referring to figure 8, 9, after the film, or plurality of films are cured, any further polymer layers required for the device structure, are deposited and subsequently cured, in an iterative process as generally described above by following the positive path of decision step 96, 110. After the polymer layers for the active device layer are fabricated, including any polymeric conduction layer, post processing is performed at 94 or 108 if required.

Post processing may, for example, include the deposition of an inorganic anode, or cathode layer, if necessary, using known techniques. Post processing may include further heating the device to dive off unwanted moisture. Alternatively, or additionally, post processing may include the fabrication of a hardwearmg, scratch resistant, polymer layer to protect the device. The protective layer may be fabricated in the same way as has been described for the other polymer layers, by the deposition and subsequent curing of an appropriate monomer based ink.

It will be appreciated that whilst a purely organic structure is desirable, inorganic layers may be deposited on organic layers at any time during the process, if required, for example to provide a dielectric layer between polymer layers.

An application of organic devices fabricated using the process of figures 8,9 is illustrated generally at 156, figure 15. The application 156 comprises a disposable display 160 comprising a poster, or the like, for exhibiting a desired colour/monochromatic image.

The poster 160 comprises a plurality of appropriately coloured display regions 154 making up the image to be exhibited. The poster further comprises at least one active display area 158 for highlighting at least one of the coloured display regions 154. The active display area 158 comprises at least one organic LED located for highlighting the associated region 154 when the OLED is emitting light.

An application of organic devices fabricated using the process of figures 8,9 is illustrated generally at 162, figure 16. The application 162 comprises a matrix of OLED devices 164. Each device may be controlled individually to create a static, or dynamic image.

An alternative application of organic devices fabricated using the process of figures 8, 9 is illustrated generally at 166, figure 17. The application 166 comprises a matrix of touch-sensor devices 168. Each device may be controlled individually to create a single, or a dynamic interface.

A further application of organic devices fabricated using the process of figures 8, 9 is illustrated generally at 170, figure 18. The application 170 comprises a matrix of OLED 174 and touch-sensor 172 devices. Each device may be controlled individually to create a static, or dynamic image. Interlacing devices has the application of an interactive display where lights can trace a moving finger, or object across (and on) the display.

It will be appreciated that other forms of OLED patterns can be printed in the embodiments of figures 16-18, such as hexagons and the like. It is appreciated that any printed device can have any shape -as permitted by the printing process. it is also appreciated that OLED's and touch-sensors may be printed in any combination. Shapes such as circles, hexagons and the like do not have the acute angles of a square, or triangle.

As such, in the case of an OLED The light will be more uniform across the device. For a capacitive touch-sensor, charge collects more readily at a point (the corners), so better sensitivity is achieved.

The mixing' of OLED and touch-sensors, for hexagon shapes are visually more uniform and may be suited to displays where the user is close to the material e.g. arms length (or closer) for an interactive display.

The UV curable liquid monomer forming the ink may include and suitable components, for example, the oligomer may comprise an aromatic urethane acrylate oligomer designed to give the cured ink film its final properties.

The monomer may comprise an acrylate low molecular weight resin configured to provide an ink of an appropriate viscosity for printing/spraying in dependence on inter alia the characteristics of the print/spray head of the printer to be used to deposit the ink.

Examples of possible monomers include difunctional monomers, monofunctional monomers, tetrafunctional I pentafunctional monomers and trifunctional monomers.

The photoinitiator is configured to absorb the UV radiation of a desired wavelength, typically for example 365nrn, in order to initiate a chemical chain reaction between the resins and the monomers resulting in cross-linking and hence, the formation of the polymer layer.

Initiators for free-radical curing include crystal and flake benzophenone and acrylated amine synergists, which have a wide range of absorption bands which may be tailored to specific applications. They have a high reactivity, low odour, and good transparency.

An example of a possible photoinitiator is an acrylated amine synergist comprising a difunctional amine coinitiator which, when used in conjunction with a photosensitizer such as benzophenone, promotes rapid curing under UV light.

In the illustrative example, figure 15, 156 the active display area 158 comprises a plurality of OLED's arranged to form a border around display regions 154 comprising lettering, thereby to highlight the lettering in use. It will be appreciated, however, that other arrangements are possible. The OLEDS may, for example, be arranged in a geometric or other pattern simply to draw attention to the whole poster 156.

Furthermore, the poster 156 may alternatively, or additionally comprise active display areas including touch sensitive devices allowing the displayed image to be responsive to a users touch, for example, by highlighting a particular area, or by causing the execution of an external, off-poster, response. The sensors could, for example, form part of an image of a numeric keypad, capable of issuing different signals dependent on the key being pressed.

The use of the organic devices in such an application is particularly advantageous in advertising campaigns, or the like, because the posters used in such campaigns typically have a lifetime which is limited. Hence, issues of device longevity, a major concern for organic device developers, are rendered either irrelevant or at least lower priority.

It will be appreciated that other components may be fabricated in a similar manner using the method described with reference to figure 3. Such devices may include, for example, organic resistors, and transistors including both field effect and bipolar junction devices.

The printing of the constituent films is carried out in a clean environment to minimise contamination. It will be appreciated, however, that the cleanliness conditions required for the environment do not need to meet the same standards as those used for the manufacture of conventional display modules.

UV curing in the manner described has a number of distinct technical advantages. For example, the ink does not cure in the ink-head thereby blocking the print nozzle. Hence, printer down-time is minünised. The use of inks cured using UV lamps in a free-air atmosphere also allows printingon materials that solvent based inks do not. Furthermore, adhesion to many substrates is improved, printer dot fixation speed is enhanced, and dot-spread and bleeding between dots is reduced. Increased ink density is therefore possible.

UV curing in a free air atmosphere also allows for improved cycle time compared to fast drying print processes involving under-substrate heating and fans.

Solvent based inks are also known to lose 50-70% volume due to evaporation during curing. Contrastingly UV curing results in substantially no corresponding loss.

Figure 19 illustrates a typical flatbed printer used to print UV curable inkjet prints, generally shown at 184. Printed devices with colour inks (if required) are printed by 180 onto substrate 176. Fitted to each side of the inkjet system 180 are two UV lamp sources 178, 182. The complete print-head system moves in a X-axis direction across the substrate media 176, whilst the substrate media 176 moves in a Y-axis direction. The printing system of a roll-to-roll printer platform is similar.

When using the thermal heat from the UV arc lamps to drive off moisture from the substrate, the thermal energy can be controlled by the setting the lamps power level, or the speed at which the print head assembly illustrated by 178, 180 and 182 moves across the substrate. Typically, the temperature of a quartz plate (see 130 in figure 10) for a UV source attains a temperature of 200 -400 C during use. For a typical focal distance of 5mm, or thereabouts, sufficient thermal energy can be radiated to drive off any water. It is appreciated that care must be taken not thermally cure ink in the print-heads. It is further appreciated that care must be taken not to over-cure polymers that require further layers upon previous sprayed layers.

Figure 20 illustrates a typical complete print-head system, shown generally at 200. The print-head system 198 accommodates the individual print-heads 194, 192, 190, 188, 186, 212, 210, 208, 206, 204. Attached to each of the print-head housing 200 are two UV arc lamps 196,202.

The print head typically moves at a speed of roughly 50 cm/s (2Oin/s). UV light sources are typically carried relative to the print head to cure the layers as they are printed. The speed of the print head can be reduced to increase the heating effect of the UV lamp on the electronic device layers. Typically raising the temperature of the printed layers to above 40 C and preferably between 40 C and 70 C is sufficient to adequately dry the material, Print-heads 194, 192, 190, 188, 186 operate with IJV source 196 at the required power level, with UV source 202 in minimum power. Print-heads 212, 210, 208, 206, 204 operate with UV source 202 at the required power level, with UV source 196 in minimum power. For the direction of printer-head system travel, the lamp in minimum power is leading and the UV source set to the required power level is the trailing lamp. Curing of the device is by the trailing lamp after the print-heads have printed a device. This helps to avoid curing of the material in the print-head.

For colour printing system, the printed head slots are cyan, magenta, yellow, black (CMYK); Cyan 186, 212, magenta 188, 210, yellow 190, 208, black 192, 206. The spare print-head slot 194 or 204 on conventional printers is normally reserved for spot colours such as white or else brand-specific colours. In-bidirectional printers, there is often two such spare slots, 194,204 which can be used in accordance with the present invention for spraying the organic device and also a spot colour. Said slot is generally designed for a specific brand of print-head. Embodiments of print-heads are illustrated in figures 21 to 23at218,228,244.

It is appreciated that within the group CMYK plus spot colour, the order of the five print-heads may vary. It is further appreciated that some print-head systems may have only one set of print-heads. In one embodiment, UV curable colour inks can be used as light filters. In such an embodiment, white OLEDs' can be printed by the print-head with one or more coloured filter layers such as, for example, red, blue and/or green printed thereover.

Figure 21 illustrates a principle embodiment of a print-head, shown generally at 218, to deliver a single layer of a device. The print-head body 216 contains an inkwell and internal tubing 220 to deliver ink, plumbed into 214, to the piezo-head 222. For a device with N layers, N print-heads are required. It is appreciated that CYMK slots may also be traded for print-heads that print device layers. Preferably the liquid phase material of the device layers has a surface tension of 48 dyneslcm or less.

Figure 22 illustrates an embodiment of a print head, shown generally at 228, where the piezo head 230 can print two layers 234, 232 of a device. Layer one is piped into 224, for printing at 234. A second layer is piped into 226, for printing at 232. It is appreciated that that the number of nozzles per layer is half that available for a layer printed by print-head 218. For print-head system with two spot colour slots, a device and full colour range may be printed.

Figure 23 illustrates the preferred embodiment of a print-head, shown generally at 244.

Print-head 244 prints four device layers. The configuration allows for two print-heads of 244 to be sprayed, or one print-head and one spot colour. The piezo-head 246 sprays different layers at 254, 252, 250, 248. The respective inputs for monomer solutions are 236, 238, 240, 242. UV curable materials which are printable, are normally in a stable oxidation state and have the typical characteristics shown in table 2:

Parameter Description Preferred Parameter Value

Surface energy (48mN/m) ambient 50-IOOmPA.s @ ambient Ink viscosity l0-2OIOOmPA.s @ 55 C Average Particle size <15im, Preferably < Ink droplet volume i-lOpl Thermal curing temperature 70-100 C Cure time 0.4 -4s UV curing energy 800 mW/cm2

TABLE 2

Claims

Claims 1 A method for fabricating a multi-layered organic electronic

device comprising: providing a substrate; fabricating a first contact layer on said substrate; fabricating an active portion on said first contact layer; and fabricating a second contact layer on said active portion; wherein said active portion fabrication comprises printing a monomer based liquid on said first contact layer, and UV curing said monomer based liquid in a free air environment to form an electroluminescent polymer layer.

2 A method as claimed in claim 1 wherein said printing step comprises digital printing.

3 A method as claimed in claim I or 2 wherein the printing step comprises inkjet printing.

4 A method as claimed in claim 2 or 3 wherein one or more moving print heads each deposit a single layer of said multi-layered organic electronic device.

A method as claimed in claim 2 or 3 wherein one or more moving print heads each deposit multiple layers of said multi-layered organic electronic device.

6 A method as claimed in any preceding claim wherein the monomer based liquid has a viscosity of less than 1 OOmPA.s at 20 C.

7 A method as claimed in any preceding claim wherein the monomer based liquid has a surface tension of at least 4SmN/m.

8 A method as claimed in any preceding claim wherein the monomer based liquid comprises particles having a particle size of less than lOjtm.

9 A method as claimed in any preceding claim further comprising heating one or more of said layers once printed.

A method as claimed in any preceding claim wherein said active portion comprises an n-type polymer layer.

11 A method as claimed in any one of claims I to 10 wherein said active portion comprises a p-type polymer layer.

12 A method as claimed in any preceding claim, wherein said device is printed on a metallic substrate and an insulator is printed between the substrate and the first contact layer.

13 A method as claimed in any preceding claim wherein said polymer layer is formed from an acrylate monomer.

14 A method as claimed in any preceding claim, wherein said active portion comprises an acrylated-polymer matrix.

A method as claimed in claim 14, wherein the said active portion comprises an acrylated polymer-matrix.

16 A method as claimed in any preceding claim wherein at least one of said first and second contact layers comprises an indium tin oxide layer.

17 A method as claimed in any preceding claim wherein at least one of said first and second contact layers comprises an aluminium layer.

18 A method as claimed in any preceding claim wherein at least one of said first and second contact layers comprises a conducting polymer layer.

19 A method as claimed in any preceding claim wherein an edge of at least one of said layers is offset from a corresponding edge of an adjacent layer.

A method as claimed in claim 19, wherein the layers are tiered.

21 A method as claimed in any preceding method claim wherein said device has its edges masked by a non-conducting polymer matrix.

22 A method as claimed in any preceding method claim wherein said UV light source comprises a metal halide lamp.

23 A method as claimed in any preceding method claim wherein said UV light source comprises a metal halide-free lamp.

24 A method as claimed in any preceding method claim wherein said UV light source comprises a UV light emitting diode.

A method as claimed in any preceding claim wherein said UV curing is performed in two stages.

26 A method as claimed in claim 25 wherein the first stage comprises dot-fixing at least said active portion.

27 A method as claimed in claim 26 wherein dot-fixing is performed using a UV light emitting diode.

28 A method as claimed in any one of claims 22 to 27 wherein the second stage comprises through-curing.

29 A method as claimed in any preceding method claim wherein said device comprises a plurality of polymer layers, each layer being UV cured substantially simultaneously.

A method as claimed in any of claims ito 28 wherein said device comprises a plurality of polymer layers, and wherein at least one of said polymer layers is cured prior to the printing and curing the or at least one further polymer layer.

31 A method as claimed in any preceding method claim wherein said device is fabricated on a transparent substrate, and wherein at least one polymer layer is IJV cured by UV light emitted through said substrate.

32 A multi-layered organic electronic device comprising: a substrate, first and second contact layers, and an active portion; said first contact layer being formed on said substrate, and the active portion being formed between said first and second contact layers; wherein said active portion comprises an electroluminescent printed polymer layer; and wherein said polymer layer comprises a polymer network polymerised in a free-air atmosphere using a UV light source.

33 An electronic device as claimed in claim 32 wherein said active portion comprises an n-type polymer layer.

34 An electronic device as claimed in claim 32 or 33 wherein said active portion comprises a p-type polymer layer.

An electronic device as claimed in any one of claims 32 to 34 wherein said polymer layer is formed from an acrylate monomer.

36 An electronic device as claimed in any one of claims 32 to 34, wherein said polymer layer is an acrylated polymer.

37 An electronic device as claimed in any one of claims 32 to 36 wherein at least one of said first and second contact layers comprises an indium tin oxide layer.

38 An electronic device as claimed in any one of claims 32 to 37 wherein at least one of said first and second contact layers comprises an aluminiwn layer.

39 An electronic device as claimed in any one of claims 32 to 38 wherein at least one of said first and second contact layers comprises a conducting polymer layer.

An electronic device as claimed in any one of claims 32 to 39 wherein said active portion is configured to convert incident light into a corresponding voltage.

41 An electronic device as claimed in any one of claims 32 to 40 wherein at least one of said first and second contact layers comprises a eutectic metal alloy.

42 An electronic device as claimed in any one of claims 32 to 41 wherein said active portion is sensitive to a user touching the device, and produces a measurable deviation in an electronic parameter in response to said touch.

43 An electronic device as claimed in any one of claims 32 to 42 when fabricated according to the method of any one of claims 1 to 31.

44 A display comprising an active display area, wherein: said active display area comprises at least one electronic device according to any of claims 32 to 43.

A display according to claim 44 wherein said display is disposable.

46 A display according to claim 44 or 45, wherein said active display area borders at least one further display area.

47 A display according to any of claims 44 to 46 wherein at least a portion of said active display area is touch sensitive.

48 A multi-layered organic electronic device comprising: a substrate, first and second contact layers, and an active portion; said first contact layer being formed on said substrate, and the active portion being formed between said first and second contact layers; wherein said active portion comprises an active polymer layer polymerised using a UV light source; and wherein said active portion is sensitive to a user touching the device, and produces a measurable deviation in an electronic parameter in response to said touch.

49 An electronic device as claimed in any claim 48 wherein said electronic parameter is capacitance.

An electronics device as claimed in any claim 48 wherein said electronic device is stacked one atop another to increase said devices capacitance.

51 An electronic device as claimed in any claim 48 wherein said electronic parameter is indicative of a fluctuation in charge.

52 An electronic device as claimed in any one of claims 48 to 51 when fbricated in accordance with the method of any one of claims I to 31.