Flexible thin film devices and methods of fabricating thin film devices using a roll-to-roll printing technique

Abstract

The present disclosure relates to a flexible thin film device, such as a photovoltaic device or OLED, comprising: a flexible substrate, conductive electrode layers or films, one or more functional layers, an insulating or barrier layer or film, a first conductive coating layer or film and a second conductive coating layer or film, wherein the first conductive coating layer or film provides a first contact terminal and the second conductive coating layer or film provides a second contact terminal for the flexible thin film device. The present disclosure also relates to a method for roll-to-roll printing of a flexible thin film device, such as a photovoltaic device or OLED, having contact terminals on the same side of the flexible thin film device, and a flexible thin film device fabricated according to a method of the disclosure. The present disclosure additionally relates to electronic display devices comprising one or more such flexible thin film devices, to flexible thin film devices or electronic display devices fabricated using the disclosed methods, and to the use of such flexible thin film devices as photovoltaic cells, OLEDs, or as electronic display devices for illuminating a visual element.

Description

[0001] P7398PC00

[0002] 1

[0003] Flexible thin film devices and methods of fabricating thin film devices using a roll-to-roll printing technique

[0004] The present disclosure relates to flexible thin film devices, such as a photovoltaic device or OLED, to methods for roll-to-roll printing of a flexible thin film device, to electronic display devices comprising such flexible thin film devices, to flexible thin film devices or electronic display devices fabricated using such methods, and to the use of such flexible thin film devices as photovoltaic cells, OLEDs, or an electronic display device for illuminating a visual element.

[0005] Background

[0006] The current state of the art in flexible thin film devices has enabled the production of lightweight, flexible solar cells that can be integrated into a diverse range of applications, including wearable electronics, architectural elements, and portable power sources. Recently, there has been a growing emphasis on enhancing the aesthetic appeal of these devices, with efforts focused on creating intricate and customised shapes and designs, while simultaneously striving to maintain or exceed the efficiency of current devices and improve production throughput.

[0007] One of the factors contributing to the aesthetic appeal and efficiency of flexible thin film devices is the placement of contact terminals. Back contact terminals, where all electrical contacts are positioned on the non-illuminated side of the device, allow the front surface to be less obstructed by metal contacts. By removing the shading effects caused by these front-facing terminals, back contact terminals maximise the active area available for light absorption, thereby enhancing energy conversion efficiency in photovoltaic devices, or ensuring unobstructed light emission in applications such as OLEDs.

[0008] Despite these advantages, current methods for implementing back contact terminals in flexible devices face significant challenges. Common approaches involve cutting openings in the front encapsulation layer and applying conductive paste or tape to form terminals. This method compromises the integrity of the encapsulation layer, creating pathways for water, oxygen, and other contaminants to infiltrate the device. Over time, this exposure accelerates degradation of the sensitive internal layers, reducing the device’s lifespan and overall reliability. Additionally, some techniques rely on metal crimping to create contact terminals, which can puncture the encapsulation layer.P7398PC00

[0009] 2

[0010] Other solutions exist for creating solar cells with back contacts, but these are primarily designed for rigid substrates and cannot be easily adapted for flexible devices. One commonly used approach involves laser scribing, where lasers are used to create vias within the substrate for electrical pathways to back contacts. However, laser scribing introduces significant drawbacks, including, for example, that the laser equipment is expensive and requires complex optical alignment systems.

[0011] It is therefore an objective of the present disclosure to provide a method for fabricating flexible thin film devices capable of producing high-resolution customised shapes while addressing the limitations of existing shape customization and contact terminal placement methods. The disclosure further seeks to ensure aesthetic integrity, durability, and scalability without compromising the functional efficiency or costeffectiveness of the manufacturing process.

[0012] Summary

[0013] Considering the prior art described above, a first aspect of the present disclosure provides a flexible thin film device as provided for in claim 1 that overcomes the limitations of existing devices by providing design features that reduce or completely eliminate the visibility of undesirable artefacts that would otherwise detract from the device’s appearance when used to illuminate visual elements. Among these design features is a configuration in which contact terminals are located on the same side of the device, preferably the back side. This configuration eliminates shading effects caused by front-facing terminals, maximises the active surface area for light absorption in photovoltaic applications, and enhances aesthetic appeal in applications where visual appearance is critical.

[0014] This solution allows for the development of versatile, lightweight, and adaptable thin-film devices suitable for a wide range of applications, including building-integrated photovoltaics, wearable electronics, decorative installations, and portable power solutions.

[0015] A second aspect of the present disclosure provides a method for roll-to-roll printing of a flexible thin film device, such as a photovoltaic device or OLED, having contact terminals on the same side of the flexible thin film device, the method comprising theP7398PC00

[0016] 3

[0017] steps of: a) providing a flexible substrate with a first conductive electrode layer or film and a second conductive electrode layer or film arranged thereon, wherein the first and second electrode films are arranged to be spaced apart on the flexible substrate, b) coating, using a roll-to-roll slot-die coating technique, one or more functional layers on the first conductive electrode film; c) coating, using a roll-to-roll slot die coating technique or a vacuum deposition technique, a third conductive electrode layer or film on the one or more functional layers and the second conductive electrode film; d) providing, such as using a roll-to-roll slot die coating or lamination technique, an insulating layer with holes provided therethrough on the third conductive electrode layer or film, optionally, wherein the holes are pre-punctured holes, e) depositing conductive material, such as conductive coating ink, paint or resin, on the insulating layer and through the holes of the insulating layer, and forming, with the conductive material, a first conductive coating layer or film and a second conductive coating layer or film such that at least a part of the first conductive coating layer or film is in contact with the first conductive electrode layer or film and at least a part of the second conductive coating layer or film is in contact with the second conductive electrode film; and wherein the first conductive coating layer or film provides a first contact terminal and the second conductive coating layer or film provides a second contact terminal for the flexible thin film device.

[0018] The method according to the second aspect provides the advantage of creating back contact terminals without the need for crimping metallic strips, as required in prior art devices where contact terminals extend from the front surface and are bent to the back side. This approach eliminates the mechanical stresses associated with bending or crimping metallic strips, which often lead to damage or breakage of protective encapsulation or barrier layers. By avoiding such breakages, the method enhances the durability of the device, as it minimizes the risk of water or contaminants penetrating the thin film device through compromised outer layers. This improvement not only extends the operational lifespan of the device but also ensures better protection of the sensitive internal components, maintaining the overall performance and reliability of the flexible thin-film device.

[0019] A third aspect of the present disclosure provides an electronic display device for illuminating a visual element, the electronic display device comprising a flexible thin film device according to the first aspect of the invention.P7398PC00

[0020] 4

[0021] A fourth aspect of the present disclosure further relates to a flexible thin film device or an electronic display device for illuminating a visual element fabricated using a method according to the present disclosure.

[0022] A fifth aspect of the present disclosure relates to the use of a flexible thin film device according to the present disclosure as a photovoltaic cell, such as a solar cell, as an OLED, or as part of an electronic display device for illuminating a visual element.

[0023] A sixth aspect of the present disclosure relates to the use of a flexible thin film device according to the first aspect as an electronic display device or the use of an electronic display device according to the third aspect for illuminating a visual element, such as a logo, motif, pictogram, decorative graphic, letter, number, symbol, or any combination thereof.

[0024] Description of the drawings

[0025] The present disclosure will in the following be described in greater detail with reference to the accompanying drawings. Various implementations are described hereinafter with reference to the drawings. The drawings are examples of implementations and are intended to illustrate some of the features of the presently disclosed solution, and are not limiting to the presently disclosed device and method.

[0026] Fig. 1 is a schematic view of an intermediate product during the fabrication of a flexible thin film device.

[0027] Fig. 2 is a schematic view illustrating the addition of an insulating layer or lamination film with pre-formed holes positioned over the third conductive electrode layer or film of the intermediate product shown in Fig. 1.

[0028] Fig. 3 is a schematic representation of the flexible thin film device after the deposition of first and second conductive coating layer or films through the holes in the insulating layer to form contact terminals.P7398PC00

[0029] 5

[0030] Fig. 4 is a schematic view of a flexible thin film device encapsulated with a barrier film containing holes aligned with the contact terminals to provide external access to the device.

[0031] Fig. 5 is a schematic view of the flexible thin film device illustrated in Fig. 4

[0032] showing conductive material filling the holes in the barrier film.

[0033] Fig. 6 is a schematic view of a tandem solar cell with multiple functional layers, showing electrical connections established through perforations or holes in the insulating layers.

[0034] Fig. 7 is a schematic view of a flexible thin film device integrating an energy storage component encapsulated with the functional layers between barrier films.

[0035] Fig. 8(a) shows a cross-sectional view of another example of a device according to the present disclosure, comprising an adhesive layer, film or coating arranged over exposed surfaces of the underlying layers.

[0036] Fig. 8(b) shows a front view of the device illustrated in Fig. 8(a) in which the adhesive layer, film, or coating masks internal structural features, such as an insulating gap or dead regions, such that these features are not visible from the illumination side.

[0037] Fig. 8(c) shows a front view of another device that lacks the masking present in the device of Fig. 8(a), leading to internal structural features, such as the insulating gap, to remain visible from the illumination side.

[0038] Fig. 9 is a schematic view of an implementation of a flexible thin film device comprising two functional cells arranged side-by-side (horizontally), showing the presence of a dead region between adjacent cells and an adhesive layer, film, or coating applied to conceal such dead regions when the device is viewed from an illumination side.P7398PC00

[0039] 6

[0040] Detailed description of the disclosure

[0041] Throughout the present disclosure, the term “holes” may, unless otherwise specified, also refer to any slot, cut-out, aperture, gap, or groove formed in the respective layer or film. Such holes may extend partially or entirely across the device, for example from one edge of the device to an opposing edge, and may in some cases run substantially along the full length of the flexible thin film device or electronic display device. In certain implementations, such elongated holes may divide the device into two longitudinal portions corresponding to positive and negative electrode regions.

[0042] The term “back contact terminal” as used herein refers to a configuration where all the electrical contacts for current collection are positioned on the back side (nonilluminated side) of the device, such as a solar cell. This arrangement differs from conventional solar cells, which typically include both front and back contact terminals. By placing all terminals on the back, the front surface is entirely free of metal grids or wires, thereby maximizing the surface area available for light absorption in solar cells or eliminating light obstructions in devices like OLEDs, where uninterrupted light emission is critical.

[0043] The term “patterned”, in reference to electrode films, denotes an arrangement where multiple electrode films are deposited on a substrate or another layer in a manner that ensures they remain electrically isolated from one another. This configuration is achieved by strategically spacing the films to prevent direct contact, thereby maintaining electrical separation and enabling independent functionality of the electrodes.

[0044] The following sets out preferred and / or optional features of the first aspect of the present disclosure. Unless stated otherwise, any of the preferred and / or optional features described herein may be combined in any technically feasible manner with one another, and with any preferred and / or optional feature of any other aspect of the present disclosure.

[0045] In some implementations of the device according to the first aspect, insulating or barrier layer or film comprises a first hole and a second hole, and wherein the first conductive coating layer or film extends through the first hole to contact the first conductive electrode film, and the second conductive coating layer or film extendsP7398PC00

[0046] 7

[0047] through the second hole of the insulating or barrier layer or film and electrically coupled to the second conductive electrode film.

[0048] By including holes in the insulating layer and extending both the first conductive coating layer or film and the second conductive coating layer or film through these holes, the device enables external electrical connections to be accessed from the same side, which is preferably configured to be the back side of the device. This configuration may therefore eliminate the need for front-facing terminals, thereby avoiding shading effects that could impact the functionality of the functional layers and maximising the active surface area available for light absorption in cases where the device is used as a photovoltaic cell. This enhances the efficiency of light capture and subsequent energy conversion.

[0049] The present disclosure therefore provides a flexible thin film device in which it is possible to position the contact terminals on the back side of the device. This offers significant advantages, as it not only allows the contact terminals to be concealed from view when the device is mounted on a surface, such as a wall, roof, or other structural element, with its back side facing the mounting surface, but it also greatly enhances the visual appeal of the device. In applications where aesthetic considerations are important, such as decorative installations that use photovoltaic devices, the absence of visible wiring or contact points on the front side ensures that the device maintains a clean and seamless appearance. For example, if the device is implemented as part of a company’s signage, such as a solar-powered logo or display, the concealed terminals ensure that the logo is aesthetically pleasing.

[0050] Additionally, positioning the terminals on the back side eliminates material obstructions that could block the passage of light to the functional layers. This uninterrupted exposure to light allows for maximum light absorption, which is crucial for achieving high energy conversion efficiency.

[0051] In some implementations, the one or more functional layers are configured to perform an electronic or optoelectronic function, such as light absorption, light emission and / or charge transport or injection.P7398PC00

[0052] 8

[0053] For example, in some implementations of the flexible thin film of the present disclosure, the one or more functional layers may comprise a single photovoltaic cell for light absorption. In other implementations, there may be three functional layers, comprising one photovoltaic cell sandwiched between two transport charge layers. Preferably, at least one of the functional layers is made from a material which absorbs, interacts with, or emits light.

[0054] In some implementations, a part of the first conductive coating layer or film is arranged on a surface of the first conductive electrode film, and a part of the second conductive coating layer or film is arranged on a surface of the second conductive electrode film.

[0055] This configuration ensures direct electrical contact between the respective coating and electrode films, eliminating the need for additional conductive materials or intermediary components, such as wires or connectors. By reducing the complexity of the design, the fabrication process becomes simpler. Moreover, minimizing the number of components decreases the likelihood of mechanical or electrical failures, thereby enhancing the overall durability of the device.

[0056] In some implementations, the flexible thin film further comprises a second insulating or barrier layer or film comprising a first hole and a second hole, and wherein the second insulating or barrier layer or film is disposed on a surface of the first conductive coating layer or film and a surface of the second conductive coating layer or film, the first hole aligning with the first conductive coating layer or film and the second hole aligning with the second conductive coating layer or film.

[0057] The inclusion of a second insulating or barrier layer or film with holes provides enhanced protection for internal layers by shielding them from moisture and oxygen ingress, which can lead to degradation of the device. This configuration ensures that the internal components remain isolated from contaminants while maintaining external access to the conductive coating layers or films, which are arranged between the first and second insulating or barrier film or layers and serve as back contact terminals.

[0058] In some implementations, the flexible thin film also comprises a first portion of conductive material arranged inside the first hole of the second insulating or barrier layer or film and / or a second portion of conductive material arranged inside the secondP7398PC00

[0059] 9

[0060] hole of the second insulating or barrier layer or film, the first and / second portion of conductive material extending the first and / or second terminal contact(s).

[0061] Incorporating conductive material inside the holes of the second insulating or barrier layer or film improves the accessibility of the contact terminals for external circuitry. Additionally, the conductive material may also function as a sealant. It may therefore provide additional protection to the second insulating or barrier layer or film by preventing the ingress of moisture, oxygen, and other contaminants through the holes in the second insulating or barrier layer or film.

[0062] In some implementations, the conductive material may be a moisture-resistant conductive paste, metallic foil, or conductive epoxy, offering both high conductivity and effective sealing properties. This dual-purpose approach extends the operational lifespan of the device by safeguarding the sensitive internal layers from environmental exposure. Furthermore, the use of precisely deposited conductive material ensures efficient electrical performance and compatibility with scalable manufacturing processes, such as roll-to-roll production.

[0063] In some implementations, the flexible thin film further comprises a third insulating or barrier layer or film, and wherein the flexible substrate, the one or more functional layers, the first, second and third conductive electrode layers or films, the first insulating or barrier layer or film, and the first and second conductive coating layer or films are encapsulated between the second and third insulating or barrier layers or films.

[0064] Preferably, the second and third insulating or barrier layers or films are self-adhering laminating foils, and, in some implementations, a UV- or thermally-curable or pressuresensitive adhesive connects the second and third insulating or barrier layers or films.

[0065] In some implementations, the first and / or second portion(s) of conductive material comprise a moisture-resistant material, and, optionally, the first and / or second portion of conductive material provide a first seal and / or a second seal for preventing ingress into the flexible solar cell.

[0066] Preferably, the conductive material is conductive adhesive, conductive polymer, a metallic foil, conductive paste, or conductive epoxy.P7398PC00

[0067] 10

[0068] In some implementations, the first conductive coating layer or film extends through the first hole and the second conductive coating layer or film extends through the second hole of the second insulating or barrier layer or film.

[0069] In some implementations, the insulating or barrier layer(s) or film(s) can be printed in unique shapes and / or comprise pigment(s) to achieve aesthetically appealing designs. In some implementations, the pigments may be conductive to enhance the electrical conductivity of the barrier layer. However, when electrically conductive pigments are used, a contact isolation gap is present in the insulating or barrier layer or film to electrically isolate the first and second contact terminals. The holes in the insulating or barrier layer or film may also be formed in patterns. By adjusting the pigment, opacity of the barrier film(s), and shape of the insulating or barrier layer(s) or film(s) and the holes provided therein, it is possible to create an aesthetically appealing flexible thin film device.

[0070] In some implementations, the flexible thin film comprises an energy storage component for receiving energy generated by the flexible thin film device, and, optionally, wherein the energy storage component is arranged between the one or more functional layers and the barrier film, and / or, optionally, wherein the energy storage component is encapsulated between the second and third insulating or barrier layers or films.

[0071] In some implementations, the holes in an insulation or barrier layer or film may each have a width less than 10 mm, such as less than 5 mm, and, optionally, the holes may each have a length less than 10 cm, such as less than 5 cm, such as less than 2 cm, such as less than 1 cm, such as less than 0.5 cm. In some implementations, the insulating or barrier layer or film may have a thickness between 0.0025 mm and 2 mm.

[0072] Smaller holes in the insulation layer permits the use of thinner conductive coating layer or films, which helps to reduce the risk of short-circuiting, since the thinner conductive coating layers or films are less likely to make contact with surrounding component parts of the thin film device.

[0073] Preferably, the flexible substrate and / or the barrier film(s) is / are electrically insulating layers. Ensuring that these layers are electrically insulating enhances the device's electrical isolation from its surroundings, which may improve user safety by preventingP7398PC00

[0074] 11

[0075] unintended current flow when the device is touched and reducing the risk of electrical shocks.

[0076] In some implementations, the flexible thin film device is a flexible thin film module. The flexible thin film module comprises: the flexible substrate, a plurality of functional cells arranged on the flexible substrate, such as photovoltaic cells or OLEDs, and the insulating layer. Preferably, each of the plurality of functional cells comprises a first conductive electrode layer or film and a second conductive electrode layer or film arranged on the flexible substrate, wherein the first and second conductive electrode layers or films are arranged to be spaced apart on the flexible substrate. Preferably, each one of the plurality of functional cells also comprises one or more functional layers arranged between and electrically coupled to the first conductive electrode layer or film and a third conductive electrode layer or film, and wherein the third conductive electrode layer or film is electrically coupled to the second conductive electrode film. Preferably, the insulating layer is arranged on the third conductive electrode layer or film of each of the plurality of functional cells and comprises a first hole and a second hole. Preferably, the plurality of functional cells are connected in series or parallel to one another. For example, functional cells may be electrically connected in series by depositing a conductive material (e.g., conductive ink or paste) in the gap between the second conductive electrode layer or film of one cell and the first conductive electrode layer or film of an adjacent cell. This conductive material bridges the gap and establishes an electrical connection, thereby allowing several functional cells to be connected together. Alternatively, the first and second conductive electrodes layers or films within different functional cells may be arranged on the flexible substrate such that the two layers or films come into contact with one another while coating the third conductive electrode layer or film, thereby allowing a plurality of functional cells to be connected in series or parallel depending on the configuration.

[0077] Preferably, the thin film module also comprises a first conductive coating layer or film extending through the first hole of the insulating layer and electrically coupled to the first conductive electrode layer or film of one of the plurality of functional cells, and a second conductive coating layer or film extending through the second hole of the insulating layer and electrically coupled to the second conductive electrode layer or film of another one, such as a last one in a line of connected functional cells formed by the plurality of functional cells, of the plurality of functional cells; and wherein the firstP7398PC00

[0078] 12

[0079] conductive coating layer or film provides a first contact terminal and the second conductive coating layer or film provides a second contact terminal for the flexible thin film module.

[0080] Preferably, the first and second conductive coating layer or films are electrically coupled to plurality of functional cells so that the potential difference across the first and second contact terminals is equal to the sum of the potential differences across each of the plurality of functional cells.

[0081] In some implementations, the flexible thin film module is a flexible thin film tandem solar module and the plurality of functional cells are solar cells. In other implementations, the flexible thin film module is a flexible thin film tandem OLED module and the plurality of functional cells are OLED cells.

[0082] In any of the examples described herein, any one or more layers of the flexible thin film device may comprise a pigment to mask structural features of the device. Suitable layers that may comprise such pigment include, for example, the insulating layer(s), the first and / or second conductive coating layer or film, the barrier film(s), the flexible substrate, and / or the one or more functional layers. The pigment may be selected to match one or more of the functional layers, which may, for example, be photovoltaic active layers. In this way, the pigment may make internal edges and interlayer boundaries substantially invisible when viewed from the illumination side of the device. This masking effect may provide a more uniform appearance to the device, and may allow the device to present a clearly defined brand, logo, sign, or other visual motif without visible structural features that are not part of the intended design.

[0083] In some implementations, the gap between the first conductive coating layer or film and the second conductive coating layer or film may have a width between 0.025 mm, and 2 mm. In preferred implementations, the gap has a width between 0.5 mm and 1.5 mm. Such a narrow gap may form only a minimally visible line or region when the first and second conductive coating layer or films comprise one or more pigments and the underlying layers of the device have a different colour from the conductive coating layer or films.P7398PC00

[0084] 13

[0085] In some implementations, if one or more of the underlying layers of the device are pigmented or otherwise provided in a colour matching that of the conductive coating layer or films, this gap may not be visible from the illumination side of the device. By matching the colouring of the conductive coating layer or films, the insulating or barrier layer or film, and / or the flexible substrate, it is possible to ensure that even the insulating gap between the first and second conductive coating layer or films is not visible, which may be particularly desirable when the device is used, for example, to form a sign, logo, symbol, or other display element.

[0086] In some implementations, the flexible thin film device further comprises a reflective layer, foil, film, or sticker. The reflective layer, foil, or film may be arranged on, above, or over an insulating layer or film; on, above, or over one or more functional layers; encapsulated between two barrier layers or films; on, above, or over an adhesive layer; positioned beneath or above a conductive coating layer or film; or incorporated anywhere within the device stack where the reflective layer, foil, or film can contribute to masking, light reflection, or enhanced visual definition. Such a reflective element may comprise a white-coloured surface. The reflective element is configured to reflect incident or unabsorbed light back toward the one or more functional layers to enhance optical performance.

[0087] The following sets out preferred and / or optional features of the second aspect of the present disclosure. Unless stated otherwise, any of the preferred and / or optional features described herein may be combined in any technically feasible manner with one another, and with any preferred and / or optional feature of any other aspect of the present disclosure.

[0088] In some implementations, the device comprises an adhesive layer arranged between the first insulating or barrier layer or film and the third conductive electrode layer or film, wherein the adhesive layer comprises one or more pigments configured to match an optical appearance and / or colour of the one or more functional layers and / or comprises metallic or metal-oxide nanoparticles, such as gold, silver, SiO2, or TiO2nanoparticles. The one or more pigments may help to visually mask underlying structural features when viewed from the side of the device opposite to the holes in an insulating or barrier layer or film providing the terminal connection points. For example, when the device is used in a solar-powered sign, the front surface opposite the back surface with theP7398PC00

[0089] 14

[0090] terminal connection points may be made to appear uniform in colour, for example, without any visible dead-space regions.

[0091] In some implementations, the adhesive layer may completely or partially cover exposed surfaces of the one or more functional layers, the third conductive electrode layer or film, and / or one or more edges of these layers. This may help to reduce visible contrast between active and inactive areas of the device. The adhesive layer may extend from a surface of the first conductive electrode film, across a surface of the third conductive electrode layer or film, and further to a surface of the second conductive electrode film. In this implementation, the adhesive layer may therefore cover and / or visually mask regions between these layers that would otherwise be visible when the device is viewed from an illumination side of the device, the illumination side being the side of the device opposite to the side comprising the holes in an insulating or barrier layer or film that provide terminal connection points for back-contact electrical access. For example, in a solar-powered sign, the illumination side forms the visible front surface of the sign, while the opposite side comprises the back-contact terminal connections, such that the adhesive layer contributes to a uniform and visually appealing front-facing appearance.

[0092] In some implementations, the adhesive layer may be applied as a continuous layer extending across a surface area encompassing at least 80% of the visible surface area of the device when viewed from the illumination side, such that the adhesive layer provides a dominant visible aesthetic. The continuous adhesive layer may extend across at least 85%, at least 90%, at least 95%, or at least 98% of the visible device area. This helps to ensure that substantially all dead regions in the device are concealed. In some implementations, the adhesive layer may be deposited as a printed, coated, laminated, or otherwise applied layer, including deposition techniques such as slot-die coating, screen printing, inkjet printing, flexographic printing, knife-coating, or lamination, all of which are compatible with roll-to-roll fabrication processes.

[0093] The following sets out preferred and / or optional features of the second aspect of the present disclosure. Unless stated otherwise, any of the preferred and / or optional features described herein may be combined in any technically feasible manner withP7398PC00

[0094] 15

[0095] one another, and with any preferred and / or optional feature of any other aspect of the present disclosure.

[0096] Preferably, a slot-die coating process is used to perform step d) of the method. Using a slot-die coating process for step d) may provide a high level of precision and uniformity in applying the insulating layer. In this approach, the insulating layer can be accurately deposited over the third conductive electrode layer or film, and access holes may subsequently be formed in the layer to enable connection with the first and second conductive electrode layers or films beneath. The formation of these holes may be achieved through methods such as laser cutting, mechanical punching, or CNC knife cutting. These techniques allow for precise alignment and size control of the holes, ensuring reliable electrical contact without compromising the structural or insulating properties of the layer.

[0097] In alternative implementations, the holes may be pre-punctured in a lamination layer or foil before the layer is arranged on the third conductive electrode layer or film. These pre-punctured holes can be created using automated punching machines, laser cutting, or CNC tools, allowing for efficient and scalable preparation of the insulating layer.

[0098] In other implementations, the insulating layer is printed onto the third conductive electrode layer or film. The layer may be printed, leaving voids that form the holes. These voids may be positioned beyond the peripheral edge(s) of the conductive electrode layers or films and the one or more functional layers. In such a configuration, a conductive coating layer or film, when arranged through the holes, is able to have electrical contact with the first or second conductive electrode layers or films below.

[0099] In some implementations, the conductive material is deposited on the insulating material in step d) such that the first conductive coating layer or film and the second conductive coating layer or film are separated by an insulating gap on a surface of the insulating layer.

[0100] The presence of an insulating gap between the first and second conductive coating layer or films prevents electrical short-circuiting between the two contact terminals. This configuration allows the electrodes to act as opposite polarity electrodes of the device.P7398PC00

[0101] 16

[0102] In some examples, the insulating gap is achieved by depositing the conductive materials in precisely controlled, non-overlapping regions using slot-die coating, screen printing, or other patterning techniques compatible with roll-to-roll manufacturing. In other examples, a mask may be used during the deposition process to ensure the conductive coatings are applied only to predefined areas, leaving the gap between them intact.

[0103] In some implementations, step e) of the method is carried out by a coating or printing process, such as by slot-die coating, screen printing, offset printing, inkjet printing, or flexographic printing.

[0104] In some examples, slot-die coating is employed to apply the conductive material in precise stripes, ensuring accurate alignment with the underlying electrode films. In other examples, screen printing is used to deposit conductive paste onto specific regions of the outer surface of the insulating layer, the surface facing away from the one or more functional layers of the device, allowing for customised back contact terminal designs. Additionally, methods such as inkjet printing or flexographic printing may also be utilised, along with any other technique capable of depositing or injecting material through the holes in the insulating film.

[0105] Preferably, the method further comprises a step of encapsulating the flexible substrate with the first and second conductive electrode layers or films, the one or more functional layers, the third conductive electrode layer or film, and the first insulating or barrier layer or film between a second insulating or barrier layer or film and a third insulating or barrier layer or film, wherein the second insulating or barrier layer or film comprises holes aligning with the first conductive coating layer or film and the second conductive coating layer or film.

[0106] Encapsulating the device between two insulating or barrier layers or films may provide enhanced protection against environmental factors such as moisture, oxygen, and contaminants, significantly improving the device's durability and operational lifespan. The inclusion of holes in one of the insulating or barrier layers or films ensures reliable external access to the back contact terminals.P7398PC00

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[0108] In some implementations, the method comprises the step of depositing conductive material in the holes of the second insulating or barrier layer or film so as to extend the first and second terminal contacts of the flexible thin film device.

[0109] Depositing conductive material in the holes of the insulating or barrier layer or film extends the back contact terminals, making those terminals more accessible for external wiring connections. The use of conductive material ensures efficient electrical contact while also enabling compatibility with various external circuitry configurations. In some examples, the conductive material may include moisture-resistant conductive adhesives, metallic paste, conductive tapes, or conductive epoxy, which not only establish strong electrical connections but may also function as protective seals, preventing the ingress of moisture, oxygen, or other contaminants that could degrade the device over time. Additionally, the conductive material can be deposited using techniques such as screen printing, inkjet printing, or other compatible dispensing methods.

[0110] In some implementations, the conductive material comprises carbon, graphite, or metallic ink or resins and, optionally, is opaque. Such materials may advantageously be used for making opaque functional cells of a flexible thin film device or module, thereby imparting a black or darker appearance to the cells. In some other implementations, the conductive material may comprise poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), metal nanowires, indium-tin oxide (ITO), fluorine-doped tin oxide (FTO), or aluminium-doped tin oxide (AZO). These materials are particularly advantageous for applications requiring transparent functional cells, such as in tandem solar cell construction, as they allow light to pass through while maintaining electrical conductivity. By adjusting the concentrations of these materials, the opacity or transparency of the functional cells can be controlled, enabling customization of the appearance of both individual functional cells and the overall combination of functional cells within a flexible thin film module.

[0111] In some implementations, the first and second conductive coating layer or films may be made from one or more of these opaque materials. When such materials are used for creating the back contact terminals, at least a portion of the device’s back side is opaque. The opacity of these materials, combined with the precision achievable whenP7398PC00

[0112] 18

[0113] depositing such materials onto the insulating layer by, for example, slot-die, inkjet, screen or flexographic coating, enables the creation of custom-shaped contact terminals. This method may be especially advantageous when making solar cell-powered logos, art or other installations in which aesthetic feature are important. Slotdie coating is a non-selective method which is ideal for creating uniform stripes, other methods like inkjet or screen printing enable selective deposition into custom shapes or dimensions, such as company logos.

[0114] In some implementations, the method is a method for fabricating a flexible thin film module, such as a flexible thin film tandem solar cell or OLED. The method comprises the step of: a) providing a flexible substrate with a plurality of functional cells, such as photovoltaic cells or OLEDs arranged thereon, wherein each of the plurality of functional cells comprises a first conductive electrode layer or film and a second conductive electrode layer or film arranged on the flexible substrate, wherein the first and second conductive electrode layers or films are arranged to be spaced apart on the flexible substrate.

[0115] The method also comprises the step of: b) coating, using a roll-to-roll slot-die coating technique, one or more functional layers (such as light absorbing layers and / or light emission layers, and / or charge transport layers) on the first conductive electrode layer or film of each one of the plurality of functional cells; and c) coating, using a roll-to-roll slot die coating technique or vacuum deposition, a third conductive electrode layer or film on the one or more functional layers and the second conductive electrode layer or film within each functional cell.

[0116] The method also, preferably, comprises the step of: d) providing an insulating or barrier layer or film with holes provided therethrough on the third conductive electrode layer or film within each functional cell, optionally, wherein the holes are pre-punctured holes; and e) depositing conductive material, such as conductive coating ink or resin, in gaps separating first and second conductive electrode layers or films within different functional cells so as to connect the plurality of functional cells in series.

[0117] Preferably, the method also comprises the step of: f) depositing conductive material, such as conductive coating ink or resin, on the insulating layer and through the holes of the insulating layer, and forming, with the conductive material, a first conductive coatingP7398PC00

[0118] 19

[0119] layer or film and a second conductive coating layer or film such that at least a part of the first conductive coating layer or film is in contact with a first conductive electrode layer or film of one of the functional cells and at least a part of the second conductive coating layer or film is in contact with a second conductive electrode layer or film of the last one of the functional cells; and wherein the first conductive coating layer or film provides a first contact terminal and the second conductive coating layer or film provides a second contact terminal for the flexible thin film module.

[0120] Step e) of the method, however, is not essential, as the first and second conductive electrode layers or films may alternatively, in other implementations of the present disclosure, be arranged on the flexible substrate in such a way that the functional cells are electrically connected in series without requiring any additional conductive material to fill the gaps between the first and second conductive electrode layers or films within different functional cells.

[0121] The following sets out preferred and / or optional features of the third aspect of the present disclosure. Unless stated otherwise, any of the preferred and / or optional features described herein may be combined in any technically feasible manner with one another, and with any preferred and / or optional feature of any other aspect of the present disclosure.

[0122] The electronic display device for illuminating a visual element may comprise one or more flexible thin film devices according to the first aspect of the present disclosure. A flexible thin film device forming part of the electronic display device may be shaped so as to represent, for example, one or more letters, numbers, symbols, logos, icons, pictograms, decorative motifs, or any combination thereof. A solar-powered sign represents one preferred implementation of such an electronic display device.

[0123] The electronic display device may comprise a front face and a back face, wherein the front face presents the visual element to be illuminated. The back face is positioned on the side of the device opposite the front face. The front face may be formed by the flexible substrate, and the back face may be formed by any layer comprising holes through which external terminal connections are established. Positioning the holes on the back face of the electronic display device ensures that no terminal connection is visible on the front face.P7398PC00

[0124] 20

[0125] Preferably, one or more layers of the flexible thin film device used in the electronic display device comprise a pigment selected to match the appearance of the functional layers, as described with respect to the first aspect of the present disclosure. The pigment may mask structural features within the device, such as, for example, dead spaces arising from inter-cell connections or regions between layers, so that these features are not visible from the front face of the electronic display device. Such features, being unintended artefacts, would otherwise interfere with the intended visual display. This ensures that the electronic display device more accurately represents the intended visual element, which is particularly advantageous in applications involving logos, designs, signage, branding elements, decorative graphics, or other shapes requiring visual reproduction.

[0126] The following sets out preferred and / or optional features of the fifth aspect of the present disclosure. Unless stated otherwise, any of the preferred and / or optional features described herein may be combined in any technically feasible manner with one another, and with any preferred and / or optional feature of any other aspect of the present disclosure.

[0127] In one example relating to the fifth aspect of the present disclosure, the flexible thin film device is used as part of an electronic display device shaped to represent a visual element, such as a logo, motif, pictogram, decorative graphic, letter, number, symbol, or any combination thereof. In such implementations, the flexible thin film device may be mounted on a surface, such as a wall or panel, with the back side of the device facing the mounting surface. The back side comprises the holes for establishing external electrical connections to the contact terminals of the flexible thin film device. By positioning the device such that this back side is secured against the mounting surface, the holes and associated external connections are concealed from view. This arrangement ensures that the visual element presented on the front side of the device remains unobstructed by electrical contacts.

[0128] The electronic display device may advantageously comprise one or more layers that include a pigment or nanoparticles as described with respect to the preceding aspects of the present disclosure, or comprise an adhesive layer or film as described with respect to the preceding aspects of the present disclosure, so that the illumination sideP7398PC00

[0129] 21

[0130] of the display device, i.e. the side facing outward from the mounting surface, is not visually impaired by internal structural features of the flexible thin film device.

[0131] Examples

[0132] Even though the following examples are described herein as being photovoltaic or solar cells, they could also function as other devices such as OLEDs simply by selecting the one or more functional layers to suit the intended electronic or optoelectronic application.

[0133] Fig. 1 is a schematic view of an intermediate product fabricated as part of the initial steps of the method according to the present disclosure, which will ultimately produce a flexible thin-film device 100. In the first step of the method, a flexible substrate 112 is provided, for example, as part of a roll, serving as the foundational layer for subsequent deposition of additional layers. A first conductive electrode layer or film 114 is arranged on the flexible substrate 112. This electrode may be made from transparent conductive materials, such as transparent conductive oxides (e.g., Indium Tin Oxide (ITO), Aluminium-doped Zinc Oxide (AZO), or Fluorine-doped Tin Oxide (FTO)), conductive polymers (e.g., PEDOT:PSS), transparent metals (e.g., ultra-thin silver, aluminium, or gold films), or metallic nanowires (e.g., silver nanowires).

[0134] A functional layer 118 is then deposited onto the first conductive electrode layer or film 114, for example, using a roll-to-roll (R2R) slot-die coating process. The functional layer 118 is designed to perform electronic or optoelectronic functions, depending on the intended application of the device. For example, in a photovoltaic device, the functional layer acts as a light-absorbing layer to generate electrons and holes.

[0135] Alternatively, in an OLED, the functional layer serves as a light-emitting layer. In some implementations, the functional layer may comprise a stack of layers, including any combination of the following: one or more light-absorbing layers, one or more lightemitting layers, and one or more charge transport or injection layers. Preferably, a light absorbing or light emitting layer is positioned between two charge transport or injection layers, with one charge transport or injection layer (an electron transport or injection layer) selectively allowing the flow of electrons to or from the functional layer and the other charge transport or injection layer (a hole transport or injection layer) selectively allowing the flow of holes to or from the functional layer. In other applications, such asP7398PC00

[0136] 22

[0137] sensors or capacitors, the functional layer may enable charge storage or interact with particles for detection.

[0138] A second conductive electrode layer or film 116 is arranged on the flexible substrate 112, adjacent to but separated from the first conductive electrode layer or film 114, forming a gap between the two conductive films 114 and 116. The first and second conductive electrode layers or films 114, 116 may be arranged on the flexible substrate 112 simultaneously or one after the other (e.g. the second conductive electrode layer or film 116 may be arranged on the flexible substrate 112 prior to the first conductive electrode layer or film 114 or vice versa). A third conductive electrode layer or film 120 is deposited on top of the functional layer 118, optionally using the same roll-to-roll slotdie coating process. The third conductive electrode layer or film 120 extends beyond the periphery of the functional layer 118 to establish electrical contact with the second conductive electrode layer or film 116, which will function as the bottom electrode, having a polarity opposite to that of the first conductive electrode layer or film 114.

[0139] A portion of the first conductive electrode layer or film 114 is deliberately left exposed to enable subsequent deposition of additional layers from above, in the direction extending from the third conductive electrode layer or film 120 toward the flexible substrate 112. This exposed region allows for the deposition of a first conductive film 122 (not shown in Fig. 1) directly onto the first conductive electrode layer or film 114. Similarly, a portion of the second conductive electrode layer or film 116 is also left exposed to permit subsequent layer deposition, which, in the examples described below, facilitates the deposition of a second conductive film 124 (not shown in Fig. 1) onto the second conductive electrode layer or film 116. This arrangement ensures proper electrical connectivity for the functional structure of the device while maintaining separation between conductive pathways.

[0140] Fig. 2 illustrates the addition of an insulating layer 121 onto the third conductive electrode layer or film 120 as part of the fabrication process described. The insulating layer 121 serves as a protective and / or isolating barrier that prevents unintended electrical contact between layers while maintaining accessibility to the underlying conductive electrodes. This insulating layer can be applied directly onto the third conductive electrode layer or film 120 using adhesive, which may be transparent, or it can be deposited using a slot-die coating process, screen printing technique, orP7398PC00

[0141] 23

[0142] flexographic printing process, all of which are compatible with the roll-to-roll technique. The insulating layer material may be transparent or opaque and can include barrier lamination foil, self-adhesive laminating foil, thermal laminating foil, or transparent insulating resin or paint, with options for thermal or UV curing. The thickness of this layer may range from several hundred nanometers to approximately 125 microns, such as between 100 nm and 125 microns, between 200 nm and 100 microns, between 400 nm and 50 microns, or between 600 nm and 10 microns.

[0143] The insulating layer 121 includes pre-formed holes 125a, 125b that align with the first and second conductive electrode layers or films 114 and 116, respectively. These holes 125a, 125b enable the formation of contact terminals by providing direct access to the underlying electrodes (including the first, second, and third electrodes) from the side of the insulating layer 121 facing away from the flexible substrate 112. The holes 125a, 125b may be created prior to lamination using automated punching machines, laser cutting, or knife-cutting CNC tools. In instances where the insulating layer is printed, it may be patterned with uncoated gaps corresponding to the electrode contact regions. Alternatively, the holes may be formed after the insulating layer 121 has been arranged on the third conductive electrode layer or film 120.

[0144] The holes 125a, 125b can be circular, square, rectangular, triangular, pentagonal, hexagonal, or other shapes, with dimensions ranging from as small as 0.25 mm to as large as 30 cm in length. In some implementations, the holes have a length of up to 5 cm. Widths extending to several millimeters.

[0145] This step ensures that the insulating layer not only provides necessary protection and isolation but also allows for access to the conductive layers beneath, facilitating the transport of charge from the functional layer (or one or more functional layers, as applicable) to external circuitry.

[0146] Fig. 3 is a schematic representation of the flexible thin film device 100 after conductive coating layer or films 122 and 124 have been deposited through the holes 125a, 125b of the insulating layer 121. These conductive coating layer or films 122, 124 establish electrical connections with the underlying first and second conductive electrode layers or films 114 and 116, respectively. The conductive coating may be applied by depositing conductive material over the holes 125a, 125b. The materials used for theP7398PC00

[0147] 24

[0148] conductive coatings may be opaque, such as carbon, graphite, graphene, or metallic inks (e.g., silver, copper, aluminium, gold), or transparent, such as PEDOT:PSS, metal nanowires, indium tin oxide (ITO), fluorine-doped tin oxide (FTO), or aluminium-doped zinc oxide (AZO).

[0149] To prevent short-circuiting, an insulating gap 126 is maintained between the conductive coating layer or films 122, 124. This gap 126 may be achieved by depositing the conductive coatings in separate, isolated regions, preferably in stripes or shapes. Each separated conductive stripe or shape corresponds to a distinct contact: one serving as the positive (+) contact and the other as the negative (-) contact. This ensures complete electrical isolation between the two electrodes while providing accessible, well-defined connections on the side which is intended to be the back side of the device.

[0150] The conductive coatings can be patterned into a variety of shapes and sizes, enabling customisation of the device for aesthetic purposes or functional requirements. While slot-die coating is the primary technique used for this step, other methods such as screen printing, offset printing, inkjet printing, or flexographic printing can also be employed in an R2R setup. Additionally, conductive epoxy may be applied to fill the contact holes before depositing the conductive coatings to enhance the electrical and mechanical connection to the underlying electrodes.

[0151] This step not only ensures proper electrical connectivity and device functionality but also provides flexibility in device design by enabling tailored patterns for both technical and aesthetic applications. The insulating gap and precise alignment of conductive coatings play a critical role in maintaining device integrity and preventing electrical failures.

[0152] The device may be arranged such that the window for particles, such as photons of light, to either enter or exit the device is via the flexible substrate 112. In this configuration, the flexible substrate should be designed to allow passage of the relevant particles, for example, by being optically transparent to a specific range of wavelengths or by not interacting with the particular particle. With this arrangement, the contacts are positioned on the back side of the device, opposite the flexible substrate. This configuration is advantageous because it conceals the contacts from view,P7398PC00

[0153] 25

[0154] creating a more aesthetically pleasing appearance for the user. Furthermore, it prevents the contacts from interfering with the passage of particles, such as photons, into or out of the device, thereby avoiding any reduction in efficiency due to blocking or shading effects.

[0155] Fig. 4 illustrates the flexible thin film device 100 with a barrier film 128 positioned over the first and second conductive coating layer or films 122 and 124. The barrier film 128, which may be opaque or transparent, features holes 130 and 132 aligned with the underlying conductive coating layer or films 122, 124. These holes provide access to the (+) and (-) contacts formed by the conductive films 122, 124. Additionally, another barrier film 138 is arranged below the flexible substrate (i.e. on the side of the flexible substrate facing away from the first and second conductive electrode layers or films), and together with the barrier film 128, encapsulates the device, providing protection against environmental factors such as moisture and oxygen.

[0156] Fig. 5 provides a schematic view of the flexible thin film device 100. Conductive material portions 134, 136 extend through the holes 130, 132 in the barrier film 128, thereby forming accessible contact terminals while ensuring the device is effectively protected by the barrier film 128. Preferably, these holes 130, 132 are filled with conductive adhesives, metallic foil or tape, or conductive paste to establish robust and reliable electrical connections.

[0157] In some examples, moisture-resistant conductive paste is used to enhance the sealing properties, protecting the internal layers of the device from environmental factors such as moisture and oxygen, and thus extending the device's operational lifespan. The preferred direction of incident light 101 is also illustrated. This direction ensures that the device has its optimal orientation for light absorption (or emission, in the case of an OLED). In this configuration, light entering or exiting the device is not obstructed by the two contact terminals provided by the first and second portions of conductive material 134, 136, which are positioned on the same side of the device.

[0158] When the flexible thin film device is in use, it is preferable to arrange the device on a surface such that the side with the two contact terminals 134, 136 becomes the rearfacing side. For example, this rear-facing side may serve as the mounting surface for the device when it is attached to a wall or another supporting structure. ThisP7398PC00

[0159] 26

[0160] configuration conceals the contact terminals from view, thus preserving a clean and visually appealing appearance for the front-facing surface. By positioning the terminals on the rear side, the functional surface of the device remains entirely unobstructed, allowing for maximum light absorption in photovoltaic applications or optimal light emission in devices such as OLEDs.

[0161] Alternatively, any contact terminals of the flexible thin film device may be provided, by one or more solder pads or solder disks arranged within the holes of the barrier film 128, or within any other holes provided for establishing external electrical connections. The solder pads or disks may be pre-embedded within whichever layer comprises the holes that ultimately provide access for forming the terminal connections, for example, the holes of the barrier film 128 or, in implementations lacking a barrier film, the holes of the insulating layer. In other implementations, the solder pads or disks are inserted after the relevant layer has been arranged.

[0162] Fig. 6 illustrates a schematic view of a flexible thin film device 200 configured as a tandem solar cell. The device 200 comprises multiple functional layers 240a, 240b, and 240c, each integrated with corresponding conductive electrode layers or films 214a, 214b, and 214c, which serve as the first conductive electrode layers or films for each stack layer of the tandem solar cell. Similarly, 216a, 216b, and 216c function as the second conductive electrode layers or films for each stack layer. Within each stack layer, a conductive electrode layer or film 220a, 220b, or 220c is arranged on its respective functional layer 240a, 240b, or 240c, following the configuration described for device 100, as shown in Figs. 1-5.

[0163] Insulating layers 242a, 242b, and 242c are positioned between adjacent stack layers to provide electrical isolation and structural integrity. These insulating layers are perforated with holes that allow first and second conductive coating layer or films 222 and 224 to establish electrical connections with the electrode films functioning as the first conductive electrode layers or films 214a, 214b, 214c and with the second conductive electrode layers or films 216a, 216b, and 216c of each layer, respectively. The entire multilayered structure is encapsulated within barrier films 228 and 238, which protect the device from environmental factors such as moisture and oxygen ingress, thereby improving its durability and operational lifespan.P7398PC00

[0164] 27

[0165] In this example, the tandem solar cell comprises three stacked layers, each functioning as an individual solar cell optimised for different segments of the light spectrum. The first solar cell incorporates an absorbing layer tuned for UV or blue light, the second solar cell for green and yellow light, and the third solar cell for red and infrared light. However, in alternative examples, the solar cells may be tuned to absorb other wavelength ranges, which may either not overlap or partially overlap with those corresponding to UV, blue, green, yellow, red, or infrared light. These layers are fabricated using the same roll-to-roll method outlined above for device 100.

[0166] While this example illustrates a configuration with three solar cells connected in parallel, the approach is highly scalable. It can accommodate an arbitrary number of solar cell layers connected either in series or parallel, provided that the conductive coating layer or films extend through the perforations in the insulating layers and establish proper contact with the respective first and second conductive electrode layers or films of each stack layer. This scalability enables efficient conversion of a broader range of the solar spectrum into electricity, making the tandem solar cell adaptable to diverse applications requiring enhanced power output and performance.

[0167] Fig. 7 illustrates a flexible thin-film device 300 that integrates an energy storage component 344. The energy storage component is arranged adjacent to the functional layer 318 and is encapsulated within barrier films 328 and 338. This design provides a compact solution for generating and storing energy within a single device. The alignment of contact terminals 321 and 332 with the energy storage component ensures seamless operation.

[0168] Figs. 8(a)-8(c) illustrate the effect of providing a pigmented adhesive layer, film, or coating on the visual appearance of the flexible thin film device when viewed from an illumination side (i.e. a front side). Fig. 8(a) shows a cross-sectional view of an implementation in which an adhesive layer, film, or coating 846 is arranged over exposed surfaces of the underlying layers, such as, in this illustrative example, the third conductive electrode layer or film 820 and the functional layer 818, and extends to surfaces of the first and second conductive electrode layers or films 814, 816. In this implementation, the adhesive layer may completely cover the exposed side and edges of the third conductive electrode layer or film 820 and the functional layer 818.

[0169] However, in other implementations the adhesive layer may only partially cover one orP7398PC00

[0170] 28

[0171] more of the underlying layers, provided that the dead regions and / or the insulating gap 826 are no longer visible from the illumination side (i.e. the front side) of the device.

[0172] The adhesive layer 846 may be pigmented to match the optical appearance or colour of one or more of the functional layers 818. When this pigmented adhesive layer is present, it visually masks internal structural features such as the insulating gap 826 between the first and second conductive coating layers or films 822, 824, and masks any “dead regions” within the device (not shown in this illustrative example, but such regions may occur in implementations comprising multiple horizontally arranged cells in the form of areas between adjacent cells) where no functional layer is present.

[0173] Soldering pads 848 may be arranged within holes in an insulating or barrier layer or film 838 to provide external terminal connections at the back side of the device. The adhesive layer 846 therefore helps to ensure that the device presents a uniform appearance when viewed from the front surface 850, without visual artefacts that would otherwise be visible.

[0174] In alternative implementations, one or more other layers, coatings, or films of the device, such as the insulating layer, a barrier film, the flexible substrate, or the conductive coating layers, may themselves comprise a pigment selected to match the appearance of the functional layers 818, which would negate the need for a separate pigmented adhesive layer, film, or coating. In other implementations, rather than using one or more pigments, one or more layers, such as an adhesive layer as provided in the implementation illustrated in Fig. 8(a), may comprise metallic (such as gold and / or silver) or metal-oxide (such as SiC>2 or TiCh) nanoparticles. The concentration of nanoparticles is selected to be sufficient to provide the desired masking effect.

[0175] Preferably, when conductive nanoparticles are used, their concentration lies between 0.1 wt% and 10wt%, although concentrations up to 20wt% may also be used. When non-conductive nanoparticles are used, they may be present in concentrations up to 20 wt%. Such nanoparticles can produce light scattering effects, reflection of unabsorbed lights and Localized Surface Plasmon Resonance (LSPR) effect that enhances the amount of light absorbed in the active layers hence enhances over all device performance while also helping to mask undesirable internal structural features such as the insulating gap 826 or dead regions.P7398PC00

[0176] 29

[0177] Fig. 8(b) shows the corresponding front view of a device incorporating the pigmented adhesive layer 846, where the insulating gap 826 and any dead regions are effectively masked and therefore not visible from the front surface 850.

[0178] Fig. 8(c) shows a front view of a device lacking the pigmented adhesive layer 846 (or comprising a non-pigmented adhesive), in which case internal features such as the insulating gap 826 remain visible as a visual artefact. When the flexible thin film device is used to form an electronic display device for illuminating a visual element, these undesirable visual artefacts may interfere with or distort the intended visual display.

[0179] Fig. 9 illustrates an implementation of a flexible thin film device 900 comprising two functional cells arranged side by side (i.e. horizontally) between the flexible substrate 912 and an overlying insulating or barrier layer or film 938 provided with holes for establishing external terminal connections, as described herein in the present disclosure. Each of the two horizontally arranged functional cells includes the layered structure described above with reference to Fig. 8(a), namely one or more functional layers arranged between a first conductive electrode layer or film, a second conductive electrode layer or film, and a third conductive electrode layer or film 920, with the first and second conductive electrode layers or films spaced apart on the flexible substrate 912. The one or more functional layers and conductive electrodes (as illustrated for a single-cell configuration in Fig. 8(a)) are therefore repeated for each cell within the horizontally arranged pair shown in Fig. 9.

[0180] A dead region 952 is defined between the two adjacent functional cells. This dead region corresponds to an area in which no portion of any functional layer is present and which arises from the interconnection between the neighbouring cells. In the absence of any masking, such a region would appear as an undesirable visual artefact when the device is viewed from an illumination side (i.e. an intended display side).

[0181] In the implementation shown in Fig. 9, an adhesive layer, film, or coating 946 is arranged over the exposed surfaces of the underlying first, second, and third conductive electrode layers or films, as well as over the exposed surfaces and edges of the underlying functional layer and across the dead region 952 between the two cells. The adhesive layer may, as shown in Fig. 9, extend continuously across an interface separating the cells, and therefore conceal the interspace between them. However, fullP7398PC00

[0182] 30

[0183] coverage across the device is not necessary. In alternative implementations, the adhesive layer, film, or coating 946 may be applied so as to cover only one or more of the dead regions 952 situated between adjacent functional cells of the device, provided that these dead regions are no longer visible from the illumination side of the device.

[0184] This masking is particularly advantageous when the flexible thin film device 900 is used to form an electronic display device for illuminating a visual element, such as a digital sign, solar-powered sign, illuminated logo, motif, pictogram, decorative graphic, symbol, or other element intended for visual display. By providing a pigmented or nanoparticle-containing adhesive layer, film, or coating that conceals the dead region(s) 952 of the device, the device may present a consistent and uniform front surface 950 that does not interfere with, distort, or visually disrupt the design of the visual element.

[0185] Moreover, although Fig. 9 shows an implementation of the device comprising two horizontally arranged functional cells, this configuration is only exemplary. In other implementations, the flexible thin film device may comprise any number of functional cells arranged in a horizontal row, a vertical column, or any two-dimensional matrix of cells. The functional cells may be electrically connected in series, in parallel, or in any combination of series and parallel connections, depending on the desired electrical characteristics. Furthermore, the stacked structural layers shown in Fig. 8(a), namely the one or more functional layers and the first, second, and third conductive electrode layers or films, may be repeated for each of the functional cells in such multi-cell arrangements. In all such configurations, one or more dead regions situated between adjacent cells may arise, and any of the masking techniques described herein (including the use of a pigmented and / or nanoparticle-containing adhesive layer, film, or coating) may be applied to conceal these regions when the device is viewed from the illumination side. This ensures that even multi-cell arrays can display a uniform front surface suitable for forming electronic display devices, illuminated signs, or visual elements of arbitrary shape.P7398PC00

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[0187] Further details of drawings

[0188] 100, 200, 300, 800, 900 - flexible thin film device

[0189] 101 , 201 , 301 - direction of incident light

[0190] 112, 212, 312, 812, 912 - flexible substrate

[0191] 114, 214a, 214b, 214c, 314, 814 - first conductive electrode layer or film 116, 216a, 216b, 216c, 316, 816 - second conductive electrode layer or film 118, 318, 818 - functional layer(s)

[0192] 120, 220a, 220b, 220c, 320, 820 - third conductive electrode layer or film 121 , 321 , 821 - insulating layer or barrier layer or film

[0193] 122, 222, 822 - first conductive coating layer or film

[0194] 124, 224, 824 - second conductive coating layer or film

[0195] 125a, 125b - first and second hole in the insulating layer

[0196] 126, 226, 826 - insulating gap

[0197] 128, 228, 328, 828 - insulating or barrier layer or film

[0198] 130, 330 - first hole in the insulating or barrier layer or film

[0199] 132, 332 - second hole in the insulating or barrier layer or film

[0200] 134 - first portion of conductive material

[0201] 136 - second portion of conductive material

[0202] 138, 238, 338, 838, 938 - another insulating or barrier layer or film 240a, 240b, 240c - first, second and third functional layers

[0203] 242a, 242b, 242c - first, second and third insulating layers

[0204] 344 - energy storage component

[0205] 846, 946 - adhesive layer, film, or coating

[0206] 848 - soldering pads arranged in the holes

[0207] 850 - front surface of the device

[0208] 952 - dead region of the device

Claims

P7398PC0032Claims1. A flexible thin film device, such as a photovoltaic device or OLED, comprising:- a flexible substrate with a first conductive electrode layer or film and a second conductive electrode layer or film arranged thereon, wherein the first and second electrode films are spaced apart on the flexible substrate;- one or more functional layers arranged between and electrically coupled to the first conductive electrode layer or film and a third conductive electrode layer or film, the third conductive electrode layer or film being electrically coupled to the second conductive electrode film;- an insulating or barrier layer or film arranged on the third conductive electrode layer or film;- a first conductive coating layer or film arranged on the insulating or barrier layer or film and electrically coupled to the first conductive electrode film; and- a second conductive coating layer or film arranged on the insulating or barrier layer or film and electrically coupled to the second conductive electrode film;wherein the first conductive coating layer or film provides a first contact terminal and the second conductive coating layer or film provides a second contact terminal for the flexible thin film device.

2. The flexible thin film device according to claim 1 , wherein the insulating or barrier layer or film comprises a first hole and a second hole,and wherein the first conductive coating layer or film extends through the first hole to contact the first conductive electrode film,and the second conductive coating layer or film extends through the second hole of the insulating or barrier layer or film and electrically coupled to the second conductive electrode film.

3. The flexible thin film device according to claim 1 or 2, wherein the one or more functional layers are configured to perform an electronic or optoelectronic function, such as light absorption, light emission and / or charge transport or injection.P7398PC00334. The flexible thin film device according to any preceding claim, wherein a part of the first conductive coating layer or film is arranged on a surface of the first conductive electrode film, and a part of the second conductive coating layer or film is arranged on a surface of the second conductive electrode film.

5. The flexible thin film device according to any preceding claim, further comprising a second insulating or barrier layer or film comprising a first hole and a second hole, and wherein the second insulating or barrier layer or film is disposed on a surface of the first conductive coating layer or film and a surface of the second conductive coating layer or film, the first hole aligning with the first conductive coating layer or film and the second hole aligning with the second conductive coating layer or film.

6. The flexible thin film device according to claim 5, further comprising a first portion of conductive material arranged inside the first hole of the second insulating or barrier layer or film and / or a second portion of conductive material arranged inside the second hole of the second insulating or barrier layer or film, the first and / second portion of conductive material extending the first and / or second terminal contact(s).

7. The flexible thin film device according to claim 5 or claim 6, further comprising a third insulating or barrier layer or film, and wherein the flexible substrate, the one or more functional layers, the first, second and third conductive electrode layers or films (CEF1; CEF2; CEF3), the first insulating or barrier layer or film, and the first and second conductive coating layer or films (CCF1 ; CCF2) are encapsulated between the second and third insulating or barrier layers or films.

8. The flexible thin film device according to claim 7, wherein the second and third insulating or barrier layer or film are self-adhering laminating foils.

9. The flexible solar cell according to claim 8, wherein a UV- or thermally-curable or pressure sensitive adhesive connects the second and third insulating or barrier layer or film.

10. The flexible thin film device according to any one of claims 6 to 9, wherein the first and / or second portion(s) of conductive material comprise a moisture-P7398PC0034resistant material, and, optionally, the first and / or second portion of conductive material provide a first seal and / or a second seal for preventing ingress into the flexible solar cell.

11. The flexible thin film device according to any one of claims 6 to 10, wherein the conductive material is conductive adhesive, conductive polymer, a metallic foil or tape, conductive paste, or conductive epoxy.

12. The flexible thin film device according to any one of claims 6 to 11, wherein the first conductive coating layer or film extends through the first hole and the second conductive coating layer or film extends through the second hole of the second insulating or barrier layer or film.

13. The flexible thin film device according to any preceding claim, further comprising an energy storage component for receiving energy generated by the flexible thin film device, and, optionally, wherein the energy storage component is arranged between the one or more functional layers and the second insulating or barrier layer or film, and / or, optionally, wherein the energy storage component is encapsulated between the second and third insulating or barrier layer or film.

14. The flexible thin film device according to any preceding claim, wherein the holes in the first insulating or barrier layer or film have a width less than 10 mm, such as less than 5 mm, and, optionally, the holes have a length less than 30 cm, such as less than 5 cm, such as less than 2 cm, such as less than 1 cm, such as less than 0.5 cm.

15. The flexible thin film device according to any preceding claim, wherein the first insulating or barrier layer or film has a thickness between 0.025 mm and 5 mm.

16. The flexible thin film device according to any preceding claim, wherein the flexible substrate and / or the first, second, and / or third barrier layers or film(s) is / are electrically insulating layers.

17. The flexible thin film device according to any preceding claims, further comprising an adhesive layer arranged between the first insulating or barrier layer or film and the third conductive electrode layer or film,P7398PC0035wherein the adhesive layer comprises one or more pigments configured to match an optical appearance and / or colour of the one or more functional layers, and / orwherein the adhesive layer comprises metallic or metal-oxide nanoparticles, such as gold, silver, SiO2, orTiO2nanoparticles, configured to scatter light and / or provide optical masking so as to reduce or prevent the visibility of internal structural features of the device when viewed from an illumination side.

18. The flexible thin film device according to claim 17, wherein the adhesive layer comprises conductive metallic or metal-oxide nanoparticles in an amount between 0.1 wt% and 15wt%.

19. The flexible thin film device according to claim 17 or claim 18, wherein the adhesive layer comprises non-conductive nanoparticles in an amount between 0.1 wt% and 20wt%.

20. A method for roll-to-roll printing of a flexible thin film device, such as a photovoltaic device or OLED, having contact terminals on the same side of the flexible thin film device, the method comprising the steps of:a) providing a flexible substrate with a first conductive electrode layer or film and a second conductive electrode layer or film arranged thereon, wherein the first and second electrode films are arranged to be spaced apart on the flexible substrate,b) coating, using a roll-to-roll slot-die coating technique, one or more functional layers on the first conductive electrode film;c) coating, using a roll-to-roll slot die coating technique or a vacuum deposition technique, a third conductive electrode layer or film on the one or more functional layers and the second conductive electrode film;d) providing a first insulating or barrier layer or film with holes provided therethrough on the third conductive electrode layer or film, optionally, wherein the holes are pre-punctured holes,e) depositing conductive material, such as conductive coating ink or resin, on the first insulating or barrier layer or film and through the holes of the first insulating or barrier layer or film, and forming, with the conductive material, a first conductive coating layer or film and aP7398PC0036second conductive coating layer or film such that at least a part of the first conductive coating layer or film is in contact with the first conductive electrode layer or film and at least a part of the second conductive coating layer or film is in contact with the second conductive electrode film; andwherein the first conductive coating layer or film provides a first contact terminal and the second conductive coating layer or film provides a second contact terminal for the flexible thin film device.

21. The method according to claim 20, wherein a slot-die coating process can be used to perform step d) of the method.

22. The method according to claim 20 or claim 21 , wherein the conductive material is deposited on the first insulating or barrier layer or film in step d) such that the first conductive coating layer or film and the second conductive coating layer or film are separated by an insulating gap on a surface of the first insulating or barrier layer or film.

23. The method according to any one of claims 20 to 22, wherein step e) of the method is carried out by a coating or printing process, such as by slot-die coating, screen printing, offset printing, inkjet printing, or flexographic printing.

24. The method according to any one of claims 20 to 23, wherein the method further comprises a step of encapsulating the flexible substrate with the first and second conductive electrode layers or films, the one or more functional layers, the third conductive electrode layer or film, and the first insulating or barrier layer or film between a second insulating or barrier layer or film and a third insulating or barrier layer or film, wherein the second insulating or barrier layer or film comprises holes aligning with the first conductive coating layer or film and the second conductive coating layer or film.

25. The method according to claim 24, wherein the method further comprises the step of depositing conductive material in the holes of the second insulating or barrier layer or film so as to extend the first and second terminal contacts of the flexible thin film device.P7398PC003726. The method according to any one of claims 20 to 25, wherein the conductive material comprises carbon, graphite, or metallic ink or resins, poly(3,4- ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), metal nanowires, indium-tin oxide (ITO), fluorine-doped tin oxide (FTO), oraluminium- doped tin oxide (AZO).

27. An electronic display device for illuminating a visual element, the electronic display device comprising one or more flexible thin film devices according to any one of claims 1 to 19.

28. The electronic display device according to claim 27, wherein a flexible thin film device forming part of the electronic display device is shaped so as to represent one or more letters, numbers, symbols, logos, icons, pictograms, decorative motifs, or any combination thereof.

29. The electronic display device according to claim 27 or claim 28, wherein the device is configured such that the visual element is visible on a front face of the device, and wherein a back face of the device comprises one or more holes through which external terminal connections to the flexible thin film device are established.

30. The electronic display device according to any one of claims 27 to 29, wherein one or more layers of the flexible thin film device comprise a pigment selected to match an optical appearance or colour of one or more of the functional layers.

31. The electronic display device according to any one of claims 27 to 30, wherein the pigment masks internal structural features of the flexible thin film device, such as dead spaces or regions between layers, such that the internal structural features are not visible from the front face of the electronic display device.

32. The electronic display device according to any one of claims 27 to 31 , wherein one or more layers, coatings, or films of the flexible thin film device comprise metallic or metal-oxide nanoparticles, such as gold, silver, SiO2, or TiO2P7398PC0038nanoparticles, configured to scatter light and / or visually mask internal structural features of the device when viewed from the front face.

33. The electronic display device according to any one of claims 27 to 32, wherein the electronic display device is a solar-powered sign, and wherein at least one of the one or more functional layers of the flexible thin film device is a photoactive layer configured to absorb light and generate electrical energy for powering the electronic display device, and at least another one of the one or more functional layers is configured to emit light to provide the illuminated visual element.

34. A flexible thin film device or an electronic display device fabricated using a method according to any one of claims 20 to 26.

35. The use of a flexible thin film device according to any one of claims 1 to 19 as a photovoltaic cell, such as a solar cell, or as an OLED.

36. The use of a flexible thin film device according to any one of claims 1 to 19 as an electronic display device or the use of an electronic display device according to any one of claims 27 to 33 for illuminating a visual element, such as a logo, motif, pictogram, decorative graphic, letter, number, symbol, or any combination thereof.

37. The use according to claim 36, wherein the electronic display device is mounted on a mounting surface with a back side of the flexible thin film device facing the mounting surface, the back side comprising holes for establishing external electrical connections, such that the holes and external connections are concealed from view and the illumination side of the display device remains visually unobstructed.

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