Light-driven electrochromic display

Abstract

The present invention relates to an optically driven display, a reflective display, comprising a first electrode layer and a second electrode layer, a photoconductor layer disposed between the electrode layers and comprising a material that is highly sensitive to infrared light, and an electrochromic material layer.

Description

[Technical field]

[0001] The present invention relates generally to the field of displays, and in particular to optically driven displays, passive displays, reflective displays, electrochromic displays and displays belonging to two or more of the above listed categories. [Background technology]

[0002] In recent years, efforts have been made to provide passive displays as an alternative to currently popular active displays such as liquid crystal displays (LCD) or organic light-emitting diode (OLED) displays. Such prior art displays have the disadvantages of emitting light and thereby tiring the human eye, having a relatively narrow viewing angle, having high energy consumption, having low contrast, and not being adapted to the changing ambient light, e.g., in outdoor conditions. In passive screens, on the other hand, the image is not produced by the emission of light such as light-emitting pixels, but by the reflection of ambient light on or within the screen. Viewing a passive display is more comparable to viewing a print medium than using a luminosity-based screen. Passive screens do not present the disadvantages listed above and may therefore be considered particularly advantageous for outdoor screens (higher contrast under direct sunlight) and for screen-based reading (high contrast, less tiring the human eye). Passive displays are also sometimes called electronic paper, e-paper, or ink displays.

[0003] Currently, there are few commercially available passive screens, and to the applicant's knowledge, there are currently no competing full-color passive displays on the market. Full-color e-paper has been devised, but its performance is generally poor in terms of color purity and / or color contrast. A drawback applicable to all active matrix based screens is that the display surface is generally limited to the size of the active matrix. Challenges with existing technologies for such displays relate to manufacturing costs, inflexibility in display size, generally slow switching times, and difficulty in achieving full-color displays.

[0004] Patent document 1 discloses a light-addressable display and a driving device for the display with a light application unit. The display mechanism comprises a light-modulating layer with liquid crystals and an organic photosensitive layer capable of absorbing address light, generating charge carriers and allowing current flow between two electrodes to act on the liquid crystals. It is not disclosed how crosstalk across the electrode-covered surface is prevented in this device when current flow is triggered by the address light. In addition, this device is a monochromatic device. Finally, the device requires backlighting to drive the display, otherwise it is expected that the address light will interfere with the image display.

[0005] Non-Patent Document 1 discloses a similar principle based on liquid crystals, but with a complex, multi-layered mechanism to assume full-color characteristics. In this device, two electrode pair devices are stacked on top of each other, in this case the top device with two stacked liquid crystal layers for blue and green, and the bottom device for red, to allow for a full-color display with RGB color mixing. This device is complex to manufacture and consumes more power due to the requirement of two stacked electrode pairs. As in Patent Document 1, backlighting is required.

[0006] US Patent No. 5,399,633 discloses a reflective color display that can be addressed from the front with light from a projector, LED or laser. The device comprises a color filter array (CFA), a bistable display medium and a photoconductor material (sandwiched between a pair of electrodes). The bistable medium means that the image displayed will remain displayed for a certain time even if the image is not updated quickly. The bistable medium is generally provided in the form of rotating bichromal spheres or cylinders, especially in the form of electrophoretic particles. This document is silent about avoiding crosstalk along the continuous electrodes used in this device. The device also requires potentials to be applied in the form of time-dependent waveforms, which may be achievable only with complex circuit designs. The color filter array (CFA) used on the display side may affect the clarity and / or brightness of the image displayed by the screen.

[0007] US Patent No. 5,399,633 discloses a full-color light-writing display with stacked layers, each having a pair of electrodes, a photoconductor layer, and an electrochromic (EC) layer. For full-color characteristics, different photoconductors with different spectral sensitivities are used, so that some photoconductors can be addressed by different driving lights. In another mode of operation, a bias voltage is selectively applied to such electrodes acting on the EC layer containing the EC material with the desired color.

[0008] US Patent No. 5,399,633 relates to an optically driven reflective display that utilizes a photoconductive material disposed between two electrodes to drive an electro-optic medium. This disclosure utilizes an electro-optic medium in the form of particles, such as bichromal spheres, to generate an image. US Patent No. 5,399,633 differs from US Patent No. 5,399,633 in that it relates to rear-face driven displays. In full color displays, particles of photoconductive material with different sensitivities are used, where the different migration behaviors or different electrophoretic properties of the different materials result in sub-pixels that display the appropriate color. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] U.S. Patent No. 8,547,313 [Patent Document 2] U.S. Patent No. 7,116,309 [Patent Document 3] U.S. Patent Application Publication No. 2020 / 0004098 [Patent Document 4] U.S. Patent Application Publication No. 2003 / 00776576 [Patent Document 5] International Publication No. 2014 / 180780 [Patent Document 6] U.S. Patent No. 6,592,783 [Non-Patent Document]

[0010] [Non-Patent Document 1] Haruo Harada et al, "Full-color photo-addressable electric paper using cholesteric liquid crystals and organic photoconductors", Journal of the SID 16 / 12, 2008 [Non-Patent Document 2] Hsin-Wei Chen et al, "A Switchable High-Sensitivity Photodetecting and Photovoltaic Device with Perovskite Absorber", J. Phys. Chem. Lett. 2015, 6, 1773-1779 [Non-Patent Document 3] Thomas Moehl etv al., "Strong Photocurrent Amplification in Perovskite Solar Cells with a Porous TiO2 Blocking Layer under Reverse Bias", J. Phys. Chem. Lett. 2014, 5, 3931-3936 [Non-Patent Document 4] Alesanco et al, "All-in-One Gel-Based Electrochromic Devices: Strengths and Recent Developments", Materials, 2018, 11, 414 Summary of the Invention [Problem to be solved by the invention]

[0011] It is an object of the present invention to provide a passive display that avoids the limitations found in the prior art. It is therefore an object of the present invention to provide a display that can be easily and cost-effectively realized in all desired sizes, including large, outdoor displays. It is an object to provide a technology that can also be used to provide full-color displays. It is further an object to provide a display that has fast switching times, allowing for rapid change of the displayed image, including rapid erasure and / or rapid generation of a new image on the display. It is an object of the present invention to provide a light-addressable display.

[0012] Further objects and problems addressed by the present invention will become apparent from the following description of the aspects and examples of the invention. [Means for solving the problem]

[0013] Surprisingly, the inventors provide a photoaddressable, preferably reflective display, which is based on one or more electrochromic materials, the colour state of which can preferably be controlled with the aid of a pair of electrodes.

[0014] In one aspect, the present invention provides a photoaddressable and / or photoaddressable display comprising a first electrode layer, a second electrode layer and a conductor layer, the electrical conductivity of which can be adjusted by application of electromagnetic radiation. This layer, called a photoconductor layer, is provided between the electrode layers. The display of the present invention further comprises an electrochromic material layer provided between the photoconductor layer and the first electrode layer.

[0015] In one aspect, the present invention provides a photoaddressable and / or photoaddressable display comprising first and second electrode layers, a photoconductor layer disposed between the electrode layers and comprising a material sensitive to infrared light (IR), an electrochromic material layer disposed between the photoconductor layer and the first electrode layer, and one or more infrared (IR) filtering materials disposed in a separate layer or within the electrochromic material layer.

[0016] In one aspect, the present invention provides a photoaddressable display comprising first and second electrode layers, a photoconductive layer disposed between said electrode layers and comprising a material that is sensitive to infrared light (IR), an electrochromic material layer disposed between the photoconductive layer and the first electrode layer, and a visible light reflective material and / or visible light reflective material layer, preferably reflecting all and / or substantially all light in the visible spectrum and providing a background for information and / or images displayed on the display.

[0017] In one aspect, the invention provides an assembly comprising an inventive display and a light source, for example a projector, LED, laser, etc.

[0018] In a preferred embodiment, the display of the invention comprises a white light scattering material and / or a white light reflecting material provided within the electrochromic material layer, within the layer comprising infrared (IR) filter material, or in a separate layer, in which case the white light scattering material and / or the white light reflecting material preferably provide a background for information and / or images displayed on the display.

[0019] Further aspects and preferred embodiments of the invention are defined below and in the appended claims. Further features and advantages of the invention will become apparent to those skilled in the art from the description of the preferred embodiments provided below. [Brief description of the drawings]

[0020] [Figure 1A] FIG. 2 shows a schematic diagram of a display arrangement according to a first embodiment of the invention provided for a monochrome display; [Figure 1B] FIG. 2 shows a schematic diagram of a display arrangement according to a second embodiment of the invention provided for a full-color display. [Figure 2A] 2A-2C are diagrams illustrating the operation of a light driving operation of a display according to one embodiment of the invention; [Figure 2B] 2A-2C are diagrams illustrating the operation of a light driving operation of a display according to one embodiment of the invention; [Diagram 3] FIG. 2 is a more detailed schematic diagram of the mechanism of a full-color, front-light-driven display according to one embodiment of the invention. [Figure 4] FIG. 2 shows a more detailed schematic diagram of a full-color, front-light-driven display according to another embodiment of the invention. [Diagram 5] FIG. 2 shows a more detailed schematic diagram of a full-color display according to yet another embodiment of the invention. [Figure 6A] FIG. 2 shows a schematic diagram of a full-colour, backlit driven display according to a further embodiment of the invention. [Figure 6B]FIG. 2 shows a schematic diagram of a full-colour, backlit driven display according to a further embodiment of the invention. [Figure 7A] 2A-2C show schematic diagrams of a full-colour transparent display according to a further embodiment of the invention; [Figure 7B] 2A-2C show schematic diagrams of a full-colour transparent display according to a further embodiment of the invention; [Figure 8A] FIG. 1 shows a schematic diagram of a device according to one embodiment of the invention. [Figure 8B] FIG. 1 shows a photograph of a device according to one embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, preferred embodiments of the inventive device are described to illustrate the invention, without any intention of limiting the scope of the invention.

[0022] The present invention relates to a photoaddressable or photoaddressable display. In the inventive display, an image is preferably generated by illuminating the display with electromagnetic radiation, preferably with light in the infrared (IR), UV and / or visible spectrum, preferably by illuminating the display with IR light. In a preferred embodiment, said IR light comprises near-IR light. In another embodiment, said IR excludes near-IR light. In a preferred embodiment, the light for addressing the display has a wavelength in the range of 700-1000 nm.

[0023] In one embodiment, the inventive display comprises a light-emitting unit configured to emit IR light, preferably of three or more different wavelengths or wavelength ranges.

[0024] Preferably, the display is illuminated via an illumination source, such as, for example, a suitable projector, laser, laser projector, LCD projector, LED, etc. Preferably, the illumination source is suitable for projecting an image and / or generating a patterned image, preferably with IR light.

[0025] The term "image" is used herein, without any limitation, to refer to the graphical and visually displayed content of a document, including images, text, numbers, symbols, and information, as long as it can be made visible to the human eye on a display.

[0026] The term "display" as used in this specification is intended to include all kinds of objects with a preferably continuous surface suitable for making visible an image as defined above. Examples of displays include e-paper, flat screens, boards, paperboard type surfaces, flexible and rigid objects, windows, walls, projector surfaces, etc. Displays may be flexible or rigid. Furthermore, displays may be flat, curved, or otherwise configured. Preferably, displays are suitable for generating said images based on electronically stored information, such as information in the form of a computer readable file.

[0027] The display of the present invention is preferably "reflective" and / or "passive". These terms are intended to mean that the image shown on the display can be seen through the reflection of ambient light, as in print media such as books, magazines, etc., and is preferably not produced by a visible light emitting unit, such as, for example, LED displays, OELD displays, back-emitting LCDs and plasma displays. Thus, the display preferably provides a relatively large viewing angle, high contrast and excellent visibility in different outdoor conditions.

[0028] In a preferred embodiment, the inventive displays are front-driven, meaning that the illumination used to drive the display (to generate an image) is emitted towards the display and enters the display on the viewing side of the display. In another embodiment, the inventive displays are rear-driven, preferably meaning that the illumination used to drive the display is emitted towards the side opposite the viewing side. In a rear-driven display, the light that drives the generation of the image enters the device from the rear.

[0029] The display of the invention is described with respect to Figures 1A through 7B, in which like structures and / or features are similarly numbered.

[0030] Figure 1A shows a display 110 comprising first and second front and rear electrodes 11, 12 respectively. At least the front electrode 11 is provided towards the viewing side of the display and is preferably transparent to at least visible light, and preferably also transparent to IR light. The front electrode 11 is preferably associated with a front substrate 91, which is also preferably transparent to at least visible and IR light.

[0031] In a preferred embodiment, the display comprises a transparent front substrate 91, in which case the first electrode 11 is supported on and / or placed on the transparent front substrate 11, which is preferably permeable to IR light.

[0032] The viewing side of the display or display 110 is indicated with the reference numeral 15 , which viewing side is thereby provided on the side of the first electrode 11 and / or associated with the transparent substrate 91 .

[0033] The rear electrode 12 is preferably associated with a rear substrate 92. The rear electrode and rear substrate need not be transparent. The rear substrate 92 is preferably opaque to visible light, and preferably absorbs and / or reflects all visible light. In the embodiment shown, the rear substrate 92 forms the rear side 16 of the device, which in most embodiments faces the display side 15.

[0034] In one embodiment illustrated in Figures 7A and 7B, the display comprises a transparent rear substrate 93, and the second electrode 12 is supported by and / or placed on the transparent rear substrate 92.

[0035] Preferably, one or both electrodes 11, 12 are continuous electrodes, covering the front and / or rear substrates, preferably in a continuous manner. Preferably, one or both electrodes extend continuously over a number of pixels and / or sub-pixels of the device, more preferably over all pixels and / or sub-pixels of the device. Preferably, one or both electrodes extend continuously over the whole or a majority of the display surface. Preferably, one or both electrodes are each addressable as one single electrode (or together as a pair of opposing electrodes) and are not made up of multiple separate electrodes. Preferably, the electrodes are not part of an active matrix.

[0036] Preferably, displays of the invention do not have a stack of more than two electrodes and / or a stack of multiple electrochromic display members, each display member including an electrochromic layer and a photoconductor layer.

[0037] In one embodiment, the display comprises a bias voltage application unit 95 for providing a bias voltage between the first electrode 11 and the second electrode 12 .

[0038] The display 110 preferably comprises a photoconductor layer 20 and an electrochromic material layer 40 .

[0039] For the purposes of this specification, the term "layer" includes multiple types of "layer", and thus includes that a corresponding layer comprises and / or consists essentially of several layers. Furthermore, a layer may comprise different components that are shown as separate layers in the drawings. Thus, what is shown as separate layers in the drawings may, but need not, be incorporated into a single identifiable or distinguishable layer. For example, in some cases, electrochromic material layer 40, which includes one or more electrochromic materials, may further include one or more selected from an IR filtering material, a white light scattering material, and / or a white light reflecting material, and an anisotropic layer, which layers and materials may also be provided in the form of a layer separate and / or distinct from layer 40 in some embodiments. Instead of a single IR filtering material, there may be multiple IR filtering materials.

[0040] In a preferred embodiment, the photoconductor layer 20 comprises multiple layers, e.g., 2-10 or 2-5 layers, including one or more charge generating layers comprising the material sensitive to infrared light (IR), and one or more charge transport layers comprising a material selected from electron transport materials and hole transport materials.

[0041] For purposes of this specification, a "photoconductor" layer is a layer whose electrical conductivity can be adjusted by exposing the layer to electromagnetic radiation having a predefined wavelength or range of wavelengths, preferably IR light.

[0042] In one preferred embodiment, photoconductor layer 20 comprises and / or functions as a photodiode.

[0043] Preferably, the photoconductor layer 20 has the function of enabling and / or triggering a current flow and / or a voltage between the electrodes when illuminated with suitable light, especially IR light. The photoconductor layer may be provided as described in US Pat. No. 5,399,433, and comprises a charge transport layer sandwiched between two charge generation layers. US Pat. No. 5,399,433 is incorporated herein by reference in its entirety. The charge generation layer preferably comprises a photosensitive material that allows for absorbing address radiation, generating excitons, and effectively separating them into free charges within the charge generation layer or at the interface between the charge generation layer and the charge transport layer. The charge transport layer is a layer into which the charge carriers generated by radiation are poured and which has the function of floating in an electric field to which a bias signal is applied. Photoconductor layers that may be used according to the present invention are also referenced in US Pat. No. 5,399,433, which is incorporated herein by reference in its entirety.

[0044] In a preferred embodiment, the photoconductor layer 20 comprises a perovskite material, and preferably comprises an organic-inorganic perovskite photodiode layer, in particular an organic-oriented perovskite photodiode. In one embodiment, the photodiode has an external quantum efficiency of greater than 100%, preferably greater than 1000%, in the IR region.

[0045] In one preferred embodiment, the photoconductor layer 20 comprises an organoammonium metal halide perovskite, the metal being Cu. 2+ , Ni 2+ , Co 2+ , Fe 2+ , Mn 2+ , Cr 2+ , Pd 2+ , Zn 2+ , Cd 2+ , Ge 2+ , Sn 2+ , Pb 2+ ,EU 2+ , Yb 2+ , Bi 3+ and Sb 3+The cations may be selected from, for example, lead and / or tin cations. In one embodiment, the photoconductor layer 20 includes an organic-inorganic perovskite material, as disclosed in U.S. Patent No. 5,399,633. The perovskite material may be a mixed anion, for example, a mixed halide and / or mixed cation perovskite.

[0046] Such perovskite materials have been reported to be highly sensitive to IR light and generate charge carriers when illuminated with IR light. Typically, an organic-inorganic perovskite material is sandwiched between an electron conducting layer and a hole conducting layer.

[0047] In a preferred embodiment, photoconductor layer 20 comprises an organic-inorganic perovskite photodiode layer, and in particular an organic-inorganic perovskite photodiode exhibiting an external quantum efficiency of >100% in the IR region, more preferably >500%, and most preferably >1000%.

[0048] Suitable perovskite photodiodes are disclosed in "Photoconductive Materials for Photoelectron Microscopy" by Friedrich Schmidt and "Photoconductive Materials for Photoelectron Microscopy" by John Wiley & Sons, Inc., 1999. In some embodiments, photoconductor layer 20 comprises a mesoporous layer, such as porous TiO2.

[0049] In some embodiments, the NIR-sensitive photoconductor layer 20 comprises a photodiode based on a silicon material or another photoactive material. The photoactive materials other than silicon and perovskite mentioned above may be selected from, for example, GaAs, Ge, InP, PbS, PbSe, Ag2S, Ag2Se, Cu2S, CuO, titanyl phthalocyanine. The NIR-sensitive photoconductor layer may also include a combination of two or more different photoactive materials.

[0050] In one embodiment, the photoconductor layer 20 comprises a photosensitive pn junction.

[0051] Displays of the present invention preferably include one or more electrochromic materials. The electrochromic materials are preferably provided in electrochromic material layer 40.

[0052] An electrochromic material is a material that changes its color depending on its oxidation state, in particular depending on an applied voltage suitable for inducing the electrochromic material to undergo a redox reaction. The inventive display preferably comprises one or more, for example two, three or four, electrochromic material layers, which preferably comprise different electrochromic materials. Preferably, the one or more electrochromic materials are preferably independently capable of having at least a substantially transparent state and a colored state depending on an applied voltage. In the colored state, the electrochromic material preferably exhibits a dark color (dark blue, dark green, dark red or dark black) or a color selected from, for example, yellow, cyan, magenta and black. The particular display, as shown in FIG. 1A, is preferably a monochromatic display and comprises an electrochromic material that has a dark color in one state and is substantially transparent in another state.

[0053] The electrochromic material layer 40 may be provided in the form of an all-in-one (AIO) layer, where the electrochromic material or materials are preferably at least somewhat mobile, e.g., capable of moving towards and / or away from the electrodes. In this embodiment, the electrochromic material is preferably at least somewhat capable of diffusing within the electrochromic layer 40 and / or is preferably unconstrained. Diffusion preferably occurs within a matrix that includes a solvent or within an electrolyte. According to this embodiment, the electrochromic material or materials are preferably small or medium sized molecules and / or are not polymeric. Preferably, in an AIO configuration, the electrochromic material is not deposited.

[0054] Preferably, as used herein, the term "small or medium sized molecule" refers to a substance or compound having a molecular weight of less than 5000 Da, preferably less than 4000, more preferably less than 3000 and most preferably less than 2500 Da. In a preferred embodiment, a small or medium sized molecule has a molecular mass of ≦2000 Da. Typically, small or medium sized molecules are not polymers, proteins, polypeptides or nucleic acids, although they may include amino acids, di- and oligomers. "Small molecules" are generally molecules having a molecular mass of ≦800 Da.

[0055] In another embodiment, the electrochromic material is deposited, preferably forming a layer throughout electrochromic material layer 40, to form the electrochromic layer. In this case, the electrochromic material is preferably immobile, cannot move by diffusion, and may be polymeric. In this case, the electrochromic material is preferably deposited on a substrate, such as on an electrode or on a mesoporous material that is itself deposited and is immobile relative to the electrode.

[0056] Electrochromic material layer 40 preferably includes one or more solvents, one or more salts, an optional polymer and possibly other layers, such as an ion storage layer, and additives and / or redox species required to provide a functional electrochromic unit. Electrochromic material layer 40 preferably includes an electrolyte, such as a gelled electrolyte.

[0057] The display 110 preferably comprises a light reflecting material and / or light filtering layer 68. One function or main function of the layer 68 is to reflect all or most of the visible light and preferably to pass at least some IR light. By reflecting the visible light, the reflecting layer 68 preferably provides a bright and / or vibrant, preferably light-colored, e.g. light grey, or preferably white background layer. Preferably, the light reflecting material and / or light reflecting layer 68 provides a background against which information and / or images can stand out and thus be visible to a human observer on said display. Preferably, the layer 68 comprises a white light scattering material and / or a white light reflecting material.

[0058] Preferably, the light reflective material and / or the light reflective layer 68 provides a background for an image displayed by one or more electrochromic materials. Thus, the reflective layer 68 preferably scatters white light and / or substantially all light in the visible spectrum.

[0059] In a preferred embodiment, the reflective layer 68 does not reflect and / or absorb all IR light.

[0060] In a preferred embodiment, the visible light reflective material and / or the visible light reflective layer 68 is transparent to at least some wavelengths of IR light.

[0061] In one embodiment, reflective layer 68 selectively reflects, absorbs, or filters IR light and is transparent to a particular passed wavelength of IR light.

[0062] In one embodiment, the reflective layer 68 is provided in the form of particles, such as microparticles or nanoparticles, for example as described elsewhere herein with respect to other embodiments.

[0063] In a preferred embodiment, the white light scattering material and / or the white light reflecting material 80 or white light scattering or white light reflecting layer 68 is provided between the photoconductor layer 20 and the electrochromic material layer 40 or within the electrochromic material layer.

[0064] In one embodiment the display comprises one or more IR filtering materials, either in a separate layer or in a film between the photoconductor layer 20 and the first electrode 11, preferably between the photoconductor layer 20 and the electrochromic material layer 40. If a conductive anisotropic layer is present (see further below), one or more IR filtering materials may be provided between the anisotropic layer and the first electrode 11, preferably between the anisotropic layer and the electrochromic layer 40.

[0065] In a single colour device, the display preferably includes one or no IR filtering material, and multiple different IR filtering materials 61, 62, 63, for example, as described with respect to Figures 3 and 4, are not required and are preferably not present.

[0066] In a preferred embodiment, the display of the invention comprises an anisotropic conductive layer 70. The function of this layer is to suppress crosstalk and to restrict and / or pass current flow in certain areas of the display that are illuminated. As mentioned above, the first electrode and / or the second electrode are preferably provided continuously over the entire area covered by the display area. The conductive anisotropic layer 70 ensures that the current flow is localized or limited only to those areas of the display where the address illumination impinges on the photoconductor layer 20. The conductive anisotropic layer 70 is preferably provided between the electrochromic material layer 40 and the photoconductor layer 20, more preferably between the reflective and / or filtering layer 68 and the photoconductor layer 20.

[0067] Anisotropic conductive layers and materials for producing them are commercially available or may be prepared, for example, according to the procedure described in US Pat. No. 5,399,633.

[0068] The anisotropic conductive layer 70 is preferably adapted to provide better image quality and / or resolution, however, an anisotropic conductive layer is not required as the invention may also be practiced without such a layer.

[0069] As can be seen in Fig. 1A, a photoconductor layer 20 is provided between said electrode layers 11 and 12. An electrochromic material layer 40 is preferably provided between said photoconductor layer 20 and said first electrode layer 11, i.e. layer 40 is closer to the viewing side 15 than photoconductor layer 20. A light filter layer and / or light reflecting layer 68 is preferably provided between layers 20 and 40. A preferably visible light reflecting material and / or visible light scattering material is preferably provided between the electrochromic material and the photoconductor layer, so as to prevent visible light entering from the viewing side 15 from reaching the photoconductor layer 20.

[0070] In a preferred embodiment, the inventive display comprises first, second and third different electrochromic materials 41, 42, 43. The first, second and third different electrochromic materials preferably have different first, second and third colors when activated. The terms "activated", "activated" and its various grammatical forms, in the context of electrochromic materials, are intended to refer to the colored state of an electrochromic material. The color state of the first, second and third different electrochromic materials preferably depends on the potential difference and / or current flow between the first electrode layer 11 and the second electrode layer 12. As mentioned elsewhere, the electrodes 11, 12 are arranged to have locally limited and / or locally defined current flow and / or voltage due to locally altered conductivity within the photodiode 20.

[0071] The different electrochromic materials are preferably provided to provide a multi-color and / or full color display. The different electrochromic materials are preferably provided in first, second, and third spatially distinct regions 44, 45, 46. For example, the first, second, and third different electrochromic materials may be provided in three separate layers one above the other, e.g., three stacked and / or three superimposed layers.

[0072] The display 110 shown in FIG. 1B comprises first, second and third spatially separated regions 44-46, which are here juxtaposed and / or arranged as substantially coplanar regions or areas of the electrochromic material layer 40. In a preferred embodiment, the first, second and third regions are separated and / or spaced apart on a horizontal axis and / or an axis parallel to the viewing side 15 or the axis of the first substrate 91 of the display. Preferably, the first, second and third regions 44-46 are vertically aligned (i.e., they are arranged at the same vertical position) on an axis extending perpendicular to the viewing side 15. Thus, as shown, the first, second and third regions extend parallel to the viewing side 15.

[0073] The spaced apart regions 44-46 preferably form pixels or subpixels of the display, and are also referred to as first, second and third electrochromic regions 44-46.

[0074] In one embodiment, the spaced apart regions 44-46 are each about 10 μm 2 From about 100 mm 2 , preferably about 50 μm 2 From about 50 mm 2 , most preferably about 100 μm 2 From about 20 mm 2 The surface of the coating is coated independently.

[0075] In one embodiment, the first, second and third different electrochromic materials 41, 42, 43 comprise electrochromic materials that are colored in their colored state and have red, green and blue, respectively, provided that they allow for RGB or other forms of additive color mixing. The invention also encompasses other types of color mixing, such as CMY and CMYK (cyan, magenta, yellow, black) and other forms of subtractive color mixing.

[0076] Although the display illustrated in FIG. 1B and other figures includes three different electrochromic materials, the invention may be implemented with four or more different electrochromic materials, in which case the display may or may not include four or more spaced apart regions.

[0077] Additionally, although the drawings show sharp separations between adjacent and / or adjacent regions 41-43, the invention encompasses cases in which the regions partially overlap and / or partially merge such that there is no sharply defined separation line between the separated regions.

[0078] In a preferred embodiment, the display of the invention includes one or more infrared (IR) filtering materials. The IR filtering materials may be provided within the electrochromic material layer 40, within the filtering layer and / or the reflective layer 68, or may be provided in a separate layer, as described in detail elsewhere herein. In a preferred embodiment, the IR materials are chemical compounds, preferably small or medium sized molecules.

[0079] In a preferred embodiment, the IR filtering material selectively filters out some IR radiation and / or is selectively transmissive to some IR radiation.

[0080] In one embodiment, the IR filtering material absorbs and / or reflects at least some IR light. Preferably, the IR filtering material filters, absorbs and / or reflects IR light characterized by a particular wavelength or a particular range of wavelengths.

[0081] In a preferred embodiment, the display comprises first, second and third different IR filtering materials and / or a plurality of first, second and third IR filtering materials, preferably the different IR filtering materials being transparent to different wavelengths and / or different wavelength ranges of IR light.

[0082] For purposes of this specification, "multiple IR filtering materials" encompasses the situation where two or more different IR filtering materials are combined to obtain a desired IR filtering effect. "Multiple IR filtering materials" encompasses "combinations," "groups," and / or "compositions" that include two, three, or more different IR filtering materials. There may be up to 10 different IR filtering materials in the multiple IR filtering materials, preferably up to five, and most preferably up to three different IR filtering materials. In particular, the IR filtering materials in the "multiple IR filtering materials" are selected to block, e.g., absorb, some IR light, but pass IR light of a particular wavelength and / or a particular wavelength range that is intended to activate an electrode associated with the corresponding region and / or area.

[0083] The first, second and third different IR filtering materials and / or different IR filtering materials, if applicable, are preferably provided in separate spatially separated regions, respectively. For example, with respect to the display 110 shown in Figure 1B, the first, second and third different IR filtering materials and / or different IR filtering materials may be provided in said first, second and third separate regions 41-43, respectively, or in separate layers 60 as described in more detail with respect to the embodiment shown in Figures 4 and 5.

[0084] In one embodiment, the first, second and third different IR filtering materials and / or different IR filtering materials are provided in different coplanar regions relative to each other, as described with respect to the embodiment shown in Figures 4 and 5.

[0085] The first, second and third different IR filtering materials and / or multiple IR filtering materials are preferably deposited to cover and / or be confined to have defined areas, regions and / or locations within the device. A first region may be provided with a first IR material or a first multiple different IR filtering materials. A second region may be provided with a second IR material or a second multiple different IR filtering materials. A third region may be provided with a third IR material or a third multiple different IR filtering materials. Thus, for some regions a single IR material may be sufficient, while other regions may independently comprise one, two or more different IR filtering materials. Different regions comprise different IR filtering materials and / or different combinations of IR filtering materials.

[0086] Having described the components of the embodiment shown in Figures 1A and 1B, the operating principles of the display of the invention will now be described with reference to Figures 2A and 2B in the full color display example of Figure 1B.

[0087] In Figure 2A, arrow 1 represents ambient electromagnetic radiation impinging on the display 120 from the front side 15. The front substrate 91 and first electrode 11 are transparent, allowing light to enter the display and reach the filtering and / or reflective layer 68. At this stage, the electrochromic material is considered to be unactivated, so all visible light passes unimpeded to the filtering and / or reflective layer 68.

[0088] All or nearly all light in the visible spectrum is preferably reflected at the filtering and / or reflective layer 68, as illustrated by arrow 2. However, layer 68 transmits at least a portion of the IR spectrum, so that, depending on the properties of layer 68, IR light having certain wavelengths passes through layer 68 and into photoconductor layer 20. It should be noted that the IR content in ambient radiation is generally not strong enough to activate photodiode 20, and conversely, photodiodes are not designed to be highly sensitive to ambient IR radiation.

[0089] Arrows 3.1, 3.2 and 3.3 illustrate a source of address light, e.g. IR light emitted by a projector as listed above. In the embodiment shown, the light source is capable of selectively emitting wavelengths or wavelength ranges of IR light.

[0090] In the embodiment shown, the first address light 3.1 has a wavelength in the range of 700-750 nm, the second address light 3.2 has a wavelength in the range of 750-800 nm, and the third address light 3.3 has a wavelength in the range of 800-850 nm. In this embodiment, the first, second and third IR filtering materials 61-63 respectively accept IR light of about 700 to about 750 nm, about 750 to about 800 nm, and about 800 to about 900 nm. In general, the first, second and third IR filtering materials accept IR light of different wavelengths or different wavelength ranges, with overlap preferably being avoided. For example, IR light having a wavelength of 750 nm will pass only one filtering material, but will be filtered, absorbed and / or reflected by two or more other IR filtering materials. Complementary filtering properties are applied to other filtering materials in a similar manner according to this example, i.e., IR light having a wavelength of, for example, 800 nm passes through only one filtering material, but is filtered, absorbed and / or reflected by two or more other IR filtering materials. The same is true for addressing light of another IR wavelength, i.e., a third and possibly a fourth IR wavelength.

[0091] Addressing IR light penetrates through the electrochromic layer 40 and, optionally, through the filtering layer and / or reflective layer 68. The display includes first, second and third IR light filtering materials that are locally separated and / or associated with first, second and third regions 44-46 that include the first, second and third electrochromic materials.

[0092] For purposes of this specification, the expression "associated," when used in the context of including one or more particular regions, is intended to mean that the corresponding material, compound, or materials are spatially distributed and / or confined to be within the particular region or aligned with that region such that they overlap or are substantially overlapping with the respective region when viewed perpendicular to the viewing surface 15 of the display.

[0093] As indicated by the numbers in the photoconductor layer 20 in FIG. 2A, the first IR filtering material is transparent to IR light having a wavelength located in the range of 700-750 nm. The first IR filtering material may be provided in the first electrochromic region 44, in a separate section of the layer 68, or in a separate layer. However, said first IR filtering material mostly overlaps with the first electrochromic region and / or substantially coincides spatially with such region. Preferably, it is applied in a direction perpendicular to the viewing surface 15, which corresponds to the main direction in which the addressing light 3.1, 3.2 and 3.3 enter the display.

[0094] Similarly, the second and third IR filtering materials are transparent to IR light having wavelengths lying within the ranges of 750-800 nm and 800-850 nm, respectively, and in this case the second and third IR filtering materials are disposed in substantial spatial alignment with the second and third electrochromic regions, respectively, in a direction perpendicular to the viewing surface 15.

[0095] As illustrated by the arrows of reference number 4, an address light 3.1 is generated that is sufficient to activate the photodiode 20 in a locally defined manner in the first electrochromic region 44. Free charge carriers generated by the photodiode trigger a current flow 4 through the first and second electrodes 11, 12, which current flow is collected in the region 44 of the first electrochromic material. An anisotropic conductive layer 70 is provided to locally restrict the current flow and thereby suppress crosstalk.

[0096] A current flow 4 through the electrochromic layer 40 induces a color change in the electrochromic material contained within the layer, as is typical for electrochromic materials. When a current flow is induced in the first electrochromic area 44, as illustrated in FIG. 2A by the arrow 4, the first electrochromic material in the first electrochromic area 44 changes color state from transparent to colored. Ambient light 1 entering the display from the front side 15 reflects the color of the first electrochromic material, which is illustrated here as red. As a result, red, or more generally a color with a red component, becomes visible to a user looking at the display in this area, i.e. in the pixels and / or subpixels illuminated with the address light 3.1.

[0097] 2B illustrates how a full-color passive (reflective) image can be generated that is addressed by IR light impinging from the front side. The first, second and third electrochromic regions 44-46 cooperate to generate a particular color through color mixing as a result of the intensities of the corresponding addressing IR wavelength ranges entering the display from the front side and / or from the viewing side 15.

[0098] The electrochromic regions 44-46 can be considered as sub-pixels that cooperate to produce a particular color by RGB color mixing, so that the three regions shown in Fig. 2B form one pixel with one color, where this color depends on the percentage of light of each of the address wavelengths or address wavelength ranges emitted by the light source and directed towards a particular area or pixel. The percentages x%, y% and z% reflect the amount or intensity of the different wavelengths that contribute to producing the color of the pixel. For example, if all three wavelength ranges impinging on the pixel have the same intensity, current flow will be induced in all regions 44-46 and all the red, green and blue electrochromic materials will become colored, which together display a dark or black pixel produced by RGB color mixing in this case. For example, if no IR light in the 750-900 nm range is emitted by the light source (y and z are zero) and only IR light is emitted that activates the photoconductor associated with the first electrochromic region 44, then only the first electrochromic material in the first region or subpixel 44 will change from transparent to colored, causing the entire pixel to reflect red light. Due to the white light reflecting layer 68, the pixel color becomes visible due to the contrast of the pixel color against a white background or at least a bright or vivid background 68. As can be seen, the pixel can be actuated by the address light 3 to have any color obtainable by RGB color mixing in this example by controlling the particular IR wavelength or range of IR wavelengths projected onto the viewing side of the display. Furthermore, a source of address light is provided to emit and / or project patterned light to impinge on the entire display and its pixels. Thus, the composition and patterning of the light projected onto the display can be utilized to generate images on the display. It should be noted that the projected light is preferably invisible IR light so that it does not interfere with the light reflected by the electrochromic materials in the device and thus with the image display.

[0099] To remove the image displayed by the pixel as described, bleaching of the electrochromic material is performed, which is preferably controlled via voltage application unit 95. For example, the voltage source may simply short between 11 and 12, or a reverse potential may be applied, so that the electrochromic material undergoes a redox reaction and changes to a transparent state across the entire display surface.

[0100] It is also possible to illuminate the entire display with all IR addressing IR light, so that the addressing light passes through all filtering materials at each sub-pixel, thereby producing a white surface on the display through RBG mixing.

[0101] The displays of the invention may be implemented in many different ways, and the invention is not intended to be limited with respect to any particular method for functioning the claimed subject matter. Figures 3 through 6A relate to different specific embodiments, including an embodiment in which address light is provided from the rear (Figures 6A and 6B) and an embodiment in which the display is at least partially transparent (Figures 7A and 7B).

[0102] For the fabrication of the device, the layers and / or components are preferably deposited from the bottom up of the device as shown in the figures, with a back substrate 92 with the second electrode 12 being provided first, for example in the form of a conductive substrate, and additional components being deposited on top of the conductive substrate in subsequent steps. Finally, a transparent first substrate 91 with a transparent first electrode 11, preferably in the form of a conductive transparent substrate, is placed on top of the electrochromic layer 40. Alternatively, an electrolyte containing some or all of the constituents of the electrochromic layer is applied after deposition of the transparent conductive substrate 11, 91, preferably by infiltration through openings in the transparent conductive substrate.

[0103] In the description of the examples that follow, the different layers and different components of the display are discussed in an order that does not necessarily correspond to the order in which the corresponding layers are added during construction of the display.

[0104] The example display 130 shown in Figure 3 includes an electrochromic layer 40 deposited as a separate all-in-one layer, in which the electrochromic material is not deposited but is preferably selected from small and medium sized molecules capable of diffusing at least to some extent within the all-in-one (AIO) matrix.

[0105] Exemplary blue, green, and red electrochromic materials that can be deposited as components of an AIO composition are provided herein below. Exemplary compound 1 is 1-ethyl-1'-(2-phosphonoethyl)-[4,4'-bipyridine]-1,1'-diium cation, which has a chromium moiety of 1,1'-diethyl[4,4'-bipyridine]-1,1'-diium. Compound 1 becomes blue when activated. Exemplary compound 2 is 1-phenyl-1'-(4-(2-phosphonoethyl)phenyl)-[4,4'-bipyridine]-1,1'-diium cation. The chromium moiety of compound 2 includes 1,1'-diphenyl-[4,4'-bipyridine]-1,1'-diium. Compound 2 becomes green when activated. An exemplary compound 3 is the 1-ethyl-4-(4-(1-(2-phosphonoethyl)pyridin-1-ium-4-yl)phenyl)pyridin-1-ium cation, which contains 4,4'-(1,4-phenylene)bis(1-ethylpyridin-1-ium) as the chromium core. Compound 3 turns red upon activation. In solution, these compounds may be added in the form of a suitable salt, e.g., a halide anion. These compounds are preferably substantially transparent when not activated.

[0106] The AIO composition forming the electrochromic regions 44-46 preferably comprises a solvent, one or more salts, at least one electrochromic material, and preferably one or more additional redox active species, which may or may not be electrochromic. Suitable solvents may be selected from solvents including, for example, propylene carbonate, γ-butyrolactone, acetonitrile. Preferably, the AOI composition further comprises a thickener, such as a polymer or a monomer and an initiator, to thicken the composition after deposition.

[0107] Preferably, the AIO composition comprises and / or forms a liquid, gel, or semi-solid electrolyte. General meanings and information regarding AIOs based on electrochromic devices are referred to in "Electrochromic Devices Based AIOs," IEEE Transactions on Polymer Science, Vol. 13, No. 1, pp. 1171-1175, 2002.

[0108] In the embodiment shown in FIG. 3, the different regions 44-46 are coplanar and / or juxtaposed. In one embodiment, the different regions containing different electrochromic materials are provided next to each other and / or arranged side-by-side, preferably coplanar, substantially coplanar. In the embodiment shown, the different electrochromic regions are vertically aligned. The different electrochromic regions may be deposited as different AIO compositions, for example by printing techniques, for example by inkjet printing or other deposition means devices suitable for depositing different compositions at different locations on one surface. The different electrochromic materials contained in the different regions may thereby be contained in different compositions (different inks), each of which is deposited such that the different compositions form different regions. Alternatively, a single initial composition may be pre-deposited over an area covering several subpixels, for example over the entire area covered by the display, and the different regions are formed in separate steps, where the different electrochromic materials are deposited relative to the pre-deposited composition in the different regions. Such separate deposition of specific components relative to the overall pre-deposited composition may be performed with a suitable alignment device capable of depositing specific components at pre-defined locations of the pre-deposited composition. The physical separation between the regions may be created by selective curing, which may be performed before or after the separate deposition of the different electrochromic materials.

[0109] In one embodiment, the adjacent and / or side-by-side arrangement of the different regions 44-46 may involve partial overlap of adjacent regions. In some embodiments, there may be no overlap, but a particular region may still be in contact with one or more of its adjacent neighboring regions. In yet other embodiments, the regions are laterally spaced apart, e.g., separated by gaps and / or by separation walls.

[0110] In a preferred embodiment, the one or more IR filtering materials 61 are provided within the electrochromic material layer 40 .

[0111] 3, different IR filtering materials and / or different IR absorbing materials are provided within different regions, particularly within different AIO compositions in different regions. Specifically, a first IR filtering material 61 is included within the first electrochromic region 44, a second IR filtering material 62 is included within the second electrochromic region 45, and a third IR filtering material is included within the third electrochromic region 46. In this embodiment, the IR filtering materials are included within the AIO compositions forming the electrochromic regions as molecules or particles, preferably in the form of small or medium sized molecules.

[0112] Exemplary compounds of IR filtering materials having different IR filtering characteristics are selected from the compounds provided below.

[0113] Aluminum 1,8,15,22-tetrakis(phenylthio)-29H,31H-chlorophthalocyanine (CAS number 167093-23-4) absorbs IR light in the range of 752-759 nm (compound 4). Vanadyl 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (CAS number 105011-00-5) filters IR light from 805-811 nm (compound 5). Copper(II) 5,9,14,18,23,27,32,36-octabutoxy-naphthalocyanine (CAS number 155773-67-4) filters IR light from 850-856 nm (compound 6).

[0114] 2A, region 44 may be activated with 750 nm IR light and may correspond to a combination of compounds 5 and 6. Region 45 may be activated with 805 nm IR light and may correspond to a combination of compounds 4 and 6. Region 46 may be activated with 850 nm IR light and may correspond to a combination of compounds 4 and 5.

[0115] The IR filtering and / or IR absorbing materials may be added to the corresponding AIO compositions as described above for the different electrochromic materials, either as part of a different composition deposited in a different juxtaposed position, or as a compound added in a separate step after deposition of the entire initial composition. In one embodiment, the first IR reflecting material 61 and the first electrochromic material 41 are included in a solution that is deposited in a separate step on the previously deposited initial composition. The same applies to the second and third IR reflecting and electrochromic materials 42, 62 and 43, 63, respectively.

[0116] The embodiment shown in Figure 3 further comprises a white light scattering material or layer 80, which is preferably deposited as a separate layer on top of the anisotropic conductive layer 70, or on top of the photoconductor layer 20 if the latter is not present. Preferably, the light scattering material or layer 80 is deposited by screen printing in the form of a paste containing white light scattering nanoparticles, followed by evaporation of the solvent used to deposit the particles. Exemplary particles are disclosed elsewhere herein.

[0117] The first electrode 11 is preferably transparent and may comprise or essentially consist of a transparent conductive material, preferably selected from, for example, transparent conductive oxides and transparent conductive polymers. For example, the conductive electrode material may be selected from SnO2, fluorine-doped tin oxide (FTO), indium-doped tin oxide (ITO), aluminum zinc oxide and PEDOT. The first substrate 91 and the first electrode 11 may be provided in the form of a transparent conductive substrate, such as transparent glass or transparent plastic, on which one of the conductive materials listed above is deposited.

[0118] The second electrode 12 and the second substrate 92 of the embodiment shown in Fig. 3 may be provided as in the first electrode and substrate, with the difference that they do not have to be transparent. Thus, the second electrode 12 may also be formed by, for example, a metal film.

[0119] Photoconductor layer 20 and anisotropic conductive layer 70 have already been described above with reference to Figures 1A and 1B.

[0120] 3 is that the electrochromic layer 40 is provided in the form of different AIO compositions containing different non-deposited and / or diffusing electrochromic materials, and that different IR filtering materials are included in the AIO compositions in different regions of the electrochromic layer. Additionally, a white light scattering layer 80 is deposited adjacent the anisotropic layer 70, e.g., toward a lower portion or bottom of the electrochromic material layer, where "lower" and "bottom" refer to the side of layer 40 that is closer to the second substrate 12 and / or backside 16 of the display.

[0121] It should be noted that the IR filtering materials 61-63 and the white light scattering and / or white light reflecting layers 80 in Figure 3 correspond to what is indicated to be the light reflecting material layers and / or light filtering layers 68 in Figures 1A-2B. In this case, all materials may be integrated within the electrochromic layer 40 instead of being provided as vertically spaced layers.

[0122] FIG. 4 shows a display 140 which differs from the embodiment shown in FIG. 3 in that the different IR filtering materials 61-63 (or multiple filtering materials) are deposited as separate IR filtering layers 60 and are thus preferably no longer included as diffused or dissipated compounds within the electrochromic layer 40.

[0123] The different IR filtering materials, such as the first, second and third different IR filtering materials 61-63, are deposited in a spatially separated manner. Preferably, they are aligned with and / or substantially overlap the first, second and third regions 44-46 of the electrochromic material layer 40. Thus, in the separate IR filtering material layer 60, the first IR filtering material 61 is disposed vertically below the first region 44, the second IR filtering material 62 is disposed vertically below the second region 45 and the third IR filtering material 63 is disposed vertically below the first region 46. Furthermore, the surfaces covered by the different IR filtering materials in the layer 60 are preferably substantially similar or identical to the corresponding surfaces of the different regions of the electrochromic layer 40. Thus, each IR wavelength and / or IR wavelength range that is able to pass through a corresponding (e.g., first, second or third) IR filtering material will effectively activate the photoconductor layer 20 only in the area defined by the corresponding IR filtering material, thereby activating the respective (first, second or third) electrochromic material that is vertically above the corresponding IR filtering material.

[0124] In the embodiment shown in Figure 4, the IR filtering layer 60 is an anisotropic conductive layer and is therefore conductive. Commercially available anisotropic layers are typically provided with an insulating layer, however this layer can be made conductive by stretching conductive lines contained in the anisotropic layer. Different IR filtering materials can be provided within the insulating layer and made conductive by the conductive lines, as shown by the multiple vertical conductive line crossings 60 and 70 in Figure 4 in each area defined by the different IR filtering materials.

[0125] 5 shows a display 150 in which the electrochromic layer 40 is of the layered type according to the specifics provided in the above-cited non-patent document 4. In such layered devices, one or more electrochromic materials are deposited and / or provided in the form of a layer, as opposed to a diffuse material. The electrochromic materials in layered devices include polymers and deposited particles.

[0126] Layered electrochromic device architectures generally have faster switching times, and displays 150, 165 and 175 (FIGS. 5, 6B and 7B) may be preferred for displays where the switching time of the structure is relatively important.

[0127] In one embodiment, the electrochromic material layer 40 comprises a mesoporous layer and / or nanoparticles 47-49. Preferably, one or more electrochromic materials 41-43 are deposited on the mesoporous layer and / or on the nanoparticles. In another embodiment, one or more electrochromic materials 41-43 are provided in mesoporous form and / or in nanoparticle form.

[0128] In one embodiment, the electrochromic material layer 40 includes an electrolyte 50 .

[0129] 5, the different regions 44-46 in the electrochromic layer 40 are defined in a spaced apart, spatially separate manner by different electrochromic materials 41-43 deposited in the form of different particles 47-49 or by different (e.g. first, second and third) electrochromic materials 41-43 deposited on or fixed to a mesoporous layer, e.g. a mesoporous TiO2 layer, preferably formed from nanoparticles 47-49. The different electrochromic materials 41-43 and / or the mesoporous layer may be conventionally deposited on the first electrode 11, preferably on a transparent conductive substrate comprising the first electrode 11, including, if appropriate, a sintering step to anneal the nanoparticles on the transparent electrode.

[0130] In one embodiment, the nanoparticles 47-49 are immobilized within the electrochromic material layer 40, e.g. deposited in a permanent manner on another layer and / or on another electrode layer. Preferably, the nanoparticles are not provided in a manner that allows them to move within the electrochromic material layer 40, e.g. during operation of the display. For example, deposition of the nanoparticles on the first electrode followed by annealing results in a permanent, immobile configuration of the nanoparticles within the display.

[0131] In one embodiment, a white light scattering and / or white light reflecting material 80 is provided within the electrochromic material layer 40, preferably between the mesoporous layer and / or nanoparticles 47-49 and the photoconductor layer 20 or, if present, the anisotropic material layer 70, more preferably the electrolyte 50.

[0132] The white light scattering and / or white light reflecting material layer 80 is preferably provided in the form of particles deposited on the different electrochromic materials 41-43. The particles for layer 80 are preferably selected from nanoparticles or microparticles having a diameter of 100 nm to 5 μm, preferably 150 to 2000 nm, more preferably 200 to 1000 nm. They may be selected from TiO2, SiO2, Al2O3 or other and / or related particulate metal oxide materials, preferably in the form of, for example, white nanoparticles.

[0133] An electrolyte 50 is provided within the electrochromic layer 40, and preferably includes one or more salts and optionally redox active species to render the electrochromic device functional. An ion storage layer is not specifically shown in Figure 5, but may be provided within the electrochromic layer as well, preferably on the side of layer 40 oriented toward the backside 16 of the device, for example near the IR filtering layer 60.

[0134] The IR filtering layer 60 and the anisotropic layer 70 of the display 150 are preferably as described with respect to the device 140 shown in FIG.

[0135] Figures 6A and 6B show rear-driven displays 160 and 165, respectively. In these displays, the rear substrate 94 at the rear surface 16 is preferably transparent to IR light and opaque to visible light or partially transparent (semi-transparent) to visible light.

[0136] In one embodiment, the display comprises a rear substrate 94, which is transparent to IR light and optionally opaque to visible light, in which case the second electrode 12 is supported by and / or deposited on the rear substrate 94, and in which case the one or more IR filtering materials 61 are deposited on the rear substrate 94, provided in a separate layer on the rear substrate 94, and / or provided between the second electrode layer (12) and the rear substrate 94.

[0137] In one embodiment, the display includes a white light and / or all light scattering material and / or light reflecting material 81. The white light and / or all light scattering layer may be provided, for example, between the electrochromic material layer 40 and the photoconductor layer 20 or may be provided within the electrochromic material layer 40. Preferably, the white light and / or all light scattering material and / or light reflecting material 81 is provided between the one or more electrochromic materials 41-43 and the photoconductor layer 20. A scattering layer may also be provided elsewhere, such as anywhere between the first electrode layer and the second electrode layer, or even outside the first electrode layer and / or the second electrode layer.

[0138] In the embodiment shown in Figures 6A and 6B, an IR-reflective layer 60, preferably comprising different IR-reflective materials, is deposited on a rear substrate 94. In the case of a (full-) colour device, the different IR-reflective materials are spatially separated within the IR-reflective layer 60, for example as described with respect to Figures 4 and 5.

[0139] In Fig. 6A the electrochromic layer 40 is of the AIO type as described with reference to Fig. 3 and Fig. 4, whereas in Fig. 6B the electrochromic layer is of the layered type as described with reference to Fig. 5. Thus the white light scattering layer and / or the white light reflecting layer 80 are respectively deposited towards the bottom at the bottom of the electrochromic layer in Fig. 6A and on the mesoporous layer comprising the electrochromic materials 41-43 in Fig. 6B.

[0140] Displays 160 and 165 are preferably back-driven, in other words, addressing IR light enters the device, and in particular the photoconductor layer, via the back side 16 of the display. In this embodiment, the display side 15, considered here as the front side, faces the optically addressed side, which is the back side 16.

[0141] Rear-driven displays 160 and 165 as shown in Figures 6A and 6B, respectively, are useful, for example, for outdoor use where a projector can be placed behind the display. Alternatively, displays 160 and 165 also encompass displays in which addressable light sources are integrated directly into the device and / or rigidly mounted to the display at or towards the rear side 16.

[0142] 7A and 7B show displays 170 and 175 that are transparent to at least some visible light and thus may be considered transparent or translucent. Such displays may be used integrated into buildings where transparency is desired, such as partially transparent walls and / or windows.

[0143] Displays 170 and 175 differ from displays 140 and 150 shown in Figures 4 and 5, respectively, in that rear substrate 93 is transparent to visible light in addition to being transparent to IR light. Furthermore, photoconductor layer 20 is preferably transparent to visible light, but can still be driven by IR light as described elsewhere. Because displays 170 and 175 strive to be as transparent as possible, white light scattering layer 80 is preferably not present.

[0144] Displays 170 and 175 are preferably front driven, so addressing IR light preferably enters the light from the front side 16 as described with respect to Figures 2A and 2B.

[0145] Displays 170 and 175 differ from each other with respect to electrochromic layer 40, which in FIG. 7A is of the AIO type and in FIG. 7B is of the layered type, as described herein above with respect to FIGS. 4 and 5, respectively.

[0146] Figure 8A shows the schematics of a single-color display 180 made according to one example, and Figure 8B shows a photograph of this example device.

[0147] To prepare the device, referring to Figure 8A, two fluorine doped tin oxide (FTO) electrodes 111 and 112 are deposited on glass substrates 191 and 192, respectively. The photoconductor layer 20 is formed by a compact titanium dioxide (TiO2) layer, a mesoporous TiO2 layer, an organic-inorganic halide perovskite layer and a hole transport layer, deposited in that order on the bottom FTO electrode 112.

[0148] The EC layer 140 is composed of a viologen-loaded mesoporous TiO2 layer 141 and a liquid electrolyte 150 deposited on the electrode 111. A reflective material composed of Al2O3 nanoparticles 180 is deposited on top of the viologen-loaded mesoporous TiO2 layer 141. An anisotropic conductive intermediate layer 170 is added between the photoconductive diode 120 and the EC layer. The device is driven with a suitable light source.

[0149] While a particular preferred embodiment of the invention has been described and specifically exemplified above, it is not intended that the invention be limited to such embodiment. Various modifications may be made thereto without departing from the spirit and scope of the invention, as set forth in the following claims.

Claims

1. An optically addressable display (110), comprising: - first and second electrode layers (11, 12), a photoconductor layer (20) disposed between said electrode layers and comprising a material sensitive to infrared (IR) light; an electrochromic material (41 to 43) and / or an electrochromic material layer (40) provided between the conductor layer (20) and the first electrode layer (11); An optically addressable display (110) comprising:

2. 10. The display of claim 1, further comprising a visible light reflective material and / or layer (68, 60) that reflects all and / or substantially all light in the visible spectrum and provides a preferably bright and / or vibrant background for information and / or images displayed on the display, the visible light reflective material and / or layer being transparent to at least some wavelengths of IR light.

3. 3. A display according to claim 1 or 2, comprising one or more infrared (IR) filtering materials (61) provided in a separate layer (60) or provided in the electrochromic material layer (40).

4. 3. The display of claim 1, wherein the electrochromic material layer (40) comprises first, second and third different electrochromic materials (41-43) provided in first, second and third spaced apart regions (44-46) within the electrochromic material layer (40).

5. 5. A display according to claim 4, wherein the first, second and third different electrochromic materials can change to red (41), green (42) and blue (43), respectively, upon application of a current and / or voltage thereto, depending on the current and / or voltage occurring between the first electrode layer (11) and the second electrode layer (12), provided that RGB color mixing is possible.

6. 4. The display of claim 3, wherein the one or more infrared (IR) filtering materials (61) are a first IR filtering material or a first plurality of IR filtering materials, and the display further comprises a second IR filtering material or a second plurality of IR filtering materials (62) and a third IR filtering material or a third plurality of IR filtering materials (63), wherein the first, second and / or third plurality of IR filtering materials are different with respect to at least one IR filtering material present within each plurality of IR filtering materials.

7. 5. The display of claim 4, wherein the first, second and / or third IR filtering material and / or the plurality of IR filtering materials (61-63) are provided within the first, second and / or third spaced apart regions (44-46) comprising first, second and / or third different electrochromic materials (41-43), respectively.

8. 7. The display of claim 6, wherein the first, second and / or third IR filtering material and / or the plurality of IR filtering materials (61-63) are provided in separate IR filter layers (60), the IR filter layers comprising the first, second and / or third IR filtering material and / or the plurality of IR filtering materials in spatially separated regions.

9. 7. The display of claim 6, wherein the first, second and / or third IR filtering material and / or the plurality of IR filtering materials (61-63) are aligned with and / or substantially overlap first, second and / or third regions (44-46) of the electrochromic material layer (40).

10. 3. A display according to claim 1 or 2, comprising a layer of anisotropically conductive material (70) provided between the layer of electrochromic material (40) and the photoconductor layer (20).

11. 3. A display as claimed in claim 1 or 2, comprising a white light scattering and / or white light reflecting material (80) provided within the electrochromic material layer (40), within the layer (60) comprising the one or more infrared (IR) filtering materials (61) or in a separate layer, the white light scattering and / or white light reflecting material (80) preferably providing a background for information and / or images displayed on the display.

12. 12. The display of claim 11, wherein the white light scattering and / or white light reflecting material (80) is provided between the photoconductor layer (20) and the electrochromic material layer (40) or within the electrochromic material layer.

13. 12. A display according to claim 11, wherein the white light scattering and / or white light reflecting material (80) is preferably permissive to IR light.

14. 3. A display according to claim 1 or 2, further comprising a light illumination unit configured to emit IR light, preferably of three or more different wavelengths or wavelength ranges.

15. 3. The display of claim 1, wherein the electrochromic material layer (40) comprises a mesoporous layer and / or nanoparticles (47-49) on which one or more electrochromic materials (41-43) are deposited, the electrochromic material layer (40) comprising an electrolyte (50).

16. 12. The display of claim 11, wherein a white light scattering and / or white light reflecting material (80) is provided within the electrochromic material layer (40), preferably between the mesoporous layer and / or nanoparticles (47-49) and the photoconductor layer (20) or, if present, the anisotropic material layer (70), more preferably within the electrolyte (50).

Images