HK1073920A - A matrix-addressable optoelectronic apparatus and electrode means in the same - Google Patents

Description

Matrix-addressable optoelectronic device and electrode arrangement in such a device

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The invention relates to a matrix-addressable optoelectronic device comprising a functional medium in the form of an opto-electronically active material provided on a global layer (global layer) of a sandwich between first and second electrode arrangements having side-by-side strip-shaped electrodes, wherein the electrodes of the second electrode arrangement are oriented at an angle to the electrodes of the first electrode arrangement, and functional elements are formed in the volume of the active material defined by respective overlapping portions between the electrodes of the first electrode arrangement and the electrodes of the second electrode arrangement to provide a matrix-addressable array of electrodes in contact with the active material, wherein the functional elements in the active material can be activated by: by applying a voltage to crossing electrodes defining an element, thereby forming a light emitting, absorbing, reflecting or polarizing pixel in the display device, or alternatively, forming a pixel on a photodetector with incident light and outputting a voltage or current through electrodes crossing over the pixel, the active material is in both cases selected as an inorganic or organic material and is capable of emitting, absorbing, reflecting or polarizing light according to a predetermined function when activated by applying a voltage, or when stimulated by incident light to output a voltage or current, or both, whereby pixel addressing in any case takes place in a matrix-addressable scheme, and wherein the electrodes of at least one electrode group are made of a transparent or translucent material.

The invention also relates to an electrode arrangement for use in a matrix-addressable optoelectronic device, the arrangement comprising a thin-film electrode layer having electrodes in the form of side-by-side strip-shaped electrical conductors, wherein the electrode layer is provided on an insulating surface of a base plate.

The invention relates in particular to an apparatus and a device comprising a planar array of functional elements, wherein the functional elements are addressed by a first electrode means and a further electrode means, respectively, wherein the first electrode means has side by side strip-shaped electrodes arranged on one side in contact with the functional elements and the further electrode means has similar electrodes but oriented perpendicular to the electrodes of the first means and in contact with the opposite side of the functional elements. This constitutes a device called matrix-addressable device. Such matrix-addressable devices may comprise functional elements, for example in the form of logic cells, memory cells or, in the case of the present invention, pixels in a display or photodetector. The functional element may comprise one or more active switching devices, in which case the matrix-addressable device is referred to as an active matrix-addressable device, or the functional element may simply be constituted by a passive device, such as a resistive or capacitive device, in which case the matrix-addressable device is referred to as a passive matrix-addressable device.

The latter is considered to provide the most efficient way of addressing, for example in the case of memory devices, because no switching elements, i.e. transistors, are needed in the memory cells. It is desirable to obtain as high a storage density as possible, but the present design principle, which places a lower limit on the cell, also defines its fill factor, i.e. the active material area of the matrix-addressable device that is actually available for its functional elements.

In fig. 1a prior art passive matrix-addressable optoelectronic device is shown comprising a substantially planar global layer of electro-optically active material 3 sandwiched between a first electrode arrangement EM1 comprising side by side stripe shaped electrodes 1 of width w and being separated from each other by a distance d and a similar second electrode arrangement EM2 comprising side by side stripe shaped electrodes 2 of the same width w, but with the electrodes 2 being arranged perpendicular to the electrodes 1 of the first electrode arrangement EM 1. In the global layer of active material 3, the overlap between the electrodes 1, 2 of the respective electrode arrangements defines a pixel 5 in the active material 3. When the device is configured as a display, for example, the pixel 5 will emit light by applying a voltage to the electrodes 1, 2 crossing at this location, whereas when the device is configured as a photodetector, a detectable current will be output on the electrodes 1, 2 by incident light for the pixel 5.

Fig. 1b shows the prior art device of fig. 1a, in a cross-section along the line X-X in fig. 1a, so that the layout of the electrodes 1, 2, the global layer of sandwiched active material 3 and the position of the pixel 5 can be clearly seen. The active material 3 of the global layer typically has such properties that the application of a voltage to the crossing electrodes 1, 2 only acts on the pixels 5 of the crossing portion and not on the adjacent pixels or cells at the electrode crossings around the former. This can be achieved by: i.e. providing the active material with anisotropic conductive properties such that it is only conductive in a direction perpendicular to the surface of the active material and between the overlapping electrodes and no current flows through the global layers to other pixels. The size and density of the pixels 5 depend on the minimum feature size (feature) of the process constraints that can be achieved in the fabrication process. When the electrodes are designed as metallizations, for example, which are then patterned (patterrn) in a microlithography process, taking a photolithographic mask and, for example, etching, these feature sizes depend on the minimum feature size f of the process constraints, which can be defined by the mask, and whose value in turn depends on the wavelength of the light used. In other words, within the scope of the prior art, this characteristic dimension f is generally limited to, for example, 0.15-0.2 μm, so that the width w of the electrodes 1, 2 and the spacing between them is approximately that amount.

In this regard, it should be noted that the value 2f is commonly referred to as pitch (pitch) and that the maximum number of lines per unit length achievable using existing manufacturing techniques is given by a factor 1/2f, and correspondingly, the maximum number of features per unit area is given by a factor 1/4f²And (4) giving. Thus if the area 4 shown in fig. 1 is considered, the size of the pixel 5 passes through f²The giving is evident as is apparent from fig. 1c, which shows the area 4 in more detail. Each pixel 5 requires a real area (real state) corresponding to the area 4, the size of the pixel being 4f²In other words, the specific pixel area f²Four times larger. This consideration illustrates that the matrix in FIG. 1a has a fill factor of 0.25, i.e., f²/4f². The degree of area utilization provided by layer 3 is therefore very low. To obtain a higher fill factor in the global layer or a higher density of pixels 5, it would be desirable to increase the fill factor or to obtain a higher resolution in the feature size of the process constraints of the matrix, e.g. to the range below 0.1 μm. However,although this may increase the total number of pixels over the same area, a higher fill factor is not guaranteed.

In view of the above considerations, the main object of the present invention is to enable increasing the fill factor to values approaching unity in matrix-addressable optoelectronic devices of the kind described above and to achieve in these devices a maximum utilization of the actual area provided by the global layer of active material 3, practically independent of the practical or practical size of the minimum feature size f constrained by the process, since the fill factor is not affected by the reduction of f, although this reduction of course serves to further increase the maximum number of pixels available on the global layer of active material 3.

The above objects, together with other advantages and features, are achieved according to the present invention by a matrix-addressable optoelectronic device, which is characterized in that the electrodes of each electrode arrangement are provided on respective electrode layers, the electrodes of the electrode arrangements all having substantially the same width w, the electrodes of each electrode arrangement being electrically insulated from each other by an insulating film having a thickness δ, the size of δ being a fraction of the width w, and the minimum value of w corresponding to a process-constrained minimum feature size f, whereby the fill factor of pixels in an opto-electronically active material associated therewith is close to 1, and the number of pixels defined by the total area a of the active material sandwiched between the electrode arrangements reaches a maximum value, such that said feature size f, said maximum value being defined by a/f²To specify.

In an advantageous embodiment of the device according to the invention the electro-optically active material is an anisotropic conductive organic material having diode domains in contact with the electrodes of the electrode arrangement, which organic conductive material may then preferably be a conjugated light emitting and/or photo-electric polymer, whereby the matrix-addressable device may function as a display, or as a photo-detector, or both.

In this advantageous embodiment of the device according to the invention, the matrix-addressable device is capable of emitting light when the diode domains are activated by an applied voltage, whereby the matrix-addressable device can operate as a display, or can output a current or a voltage when the diode domains are activated by incident light, whereby the matrix-addressable device can operate as a photodetector.

The above objects, together with further advantages and features, are also achieved according to the present invention by an electrode arrangement, characterized in that the thin film electrode layer comprises a first group of electrodes provided on the base plate with a width w_aAnd has a thickness of h_aThe first group of electrodes is equal to or larger than w_aAre spaced apart from each other by a distance d, and a second set of widths w_bAnd has a thickness of h_bIs provided in the space between the electrodes of the first group and is electrically insulated from the electrodes of the first group by a film of an electrically insulating material of thickness delta extending at least along the side edges of the side by side electrodes forming between them an insulating wall of thickness delta, whether with w_aOr w_bIs smaller than the size of delta, the spacing distance between the first set of electrodes is w_b+2 δ and the electrode layer with electrodes and the insulating film form the global plane layer in the electrode arrangement on its base plate.

In an advantageous embodiment of the electrode arrangement according to the invention, the insulating wall between the first set of electrodes and the second set of electrodes forms a film portion of insulating material provided in a layer covering the sides of the first set of electrodes up to their top surface and covering the bottom plate over the space between the first set of electrodes, the second set of electrodes being provided between the insulating film wall portions and on a recessed portion above the portion thereof covering the bottom plate, the second set of electrodes being flush with the top edge of the insulating wall and with the top surface of the first set of electrodes, whereby the second set of electrodes has h_b＝h_aDelta, and the electrode layer with electrodes and the insulating material form a thickness h in the electrode arrangement on the base plate_aThe global plane layer of (2).

In the at least one electrode arrangement according to the invention, the electrodes as well as the base plate must be made of a transparent or translucent material when the electrode arrangement is used in the device of the invention. The invention will now be described in more detail with reference to exemplary embodiments and with reference to the accompanying drawings, in which

Fig. 1a-c show a prior art matrix-addressable optoelectronic device, illustrating the fill factor typically achievable in such devices,

figure 2a is a plan view of a matrix-addressable optoelectronic device according to the invention,

figure 2b is a cross-section taken along line X-X in figure 2a,

fig. 2c is a detail of fig. 2a, and illustrates the achievable fill factor of the invention,

figure 3 is a cross section through a first embodiment of an electrode arrangement according to the invention,

figure 4 is a cross-section through a second embodiment of an electrode arrangement according to the invention,

figure 5 is a schematic cross-section through a light-emitting pixel for use in a device according to the invention,

FIG. 6 is a schematic cross-section through a light detection pixel for use in a device according to the invention, an

Fig. 7 is a schematic structure of a preferred electro-optically active material for use in any of the pixels of fig. 5 and 6.

An apparatus according to the invention and comprising an electrode arrangement according to the invention will now be discussed with reference to fig. 2a, 2b and 2 c. From this discussion it will become clear how the electrode arrangement according to the invention allows a fill factor in such a device. A device similar in structure but configured as a matrix-addressable ferroelectric memory device is the subject of co-pending norwegian patent application No.20015509, which belongs to the same applicant as the present application.

The device according to the invention is shown in plan view in fig. 2a, which in one embodiment is limited to a passive matrix-addressable configuration, wherein one electro-optically active material 3 is deposited on a global layer and sandwiched between two electrode arrangements EM1, EM2 according to the invention. As shown, first electrode arrangement EM1, which may be any of the embodiments shown in fig. 3 or 4, is the same as electrode arrangement EM2, except that electrode arrangement EM2 has side-by-side strip-shaped electrodes 2, and that strip-shaped electrodes 2 are oriented at an angle, preferably perpendicular, to corresponding electrodes 1 in electrode arrangement EM 1. Where the electrodes 1, 2 overlap, a pixel 5 is defined between them with an electro-optically active material 3. The pixel 5 may be a semiconducting inorganic or organic material which, under appropriate excitation, for example by application of a voltage in the former case, or with illumination in the latter case, may emit light or generate a photocurrent. Most preferably, the electro-optically active material should be a conjugated polymer with anisotropic electrical conductivity, so that the electrical conductivity is only present between the overlapping electrodes 1, 2 and perpendicular to the plane of the active material layer. For clarity, the driving, sensing and control circuitry is not shown in fig. 2a, but may be implemented in a practical embodiment by silicon-based CMOS technology and may also be provided on the bottom plate 7 if made of the same material. All electrodes 1, 2 are thus suitably wired and connected to the circuit in a manner known to the person skilled in the art.

As mentioned above, the active material 3 is sandwiched between electrode arrangements EM1, EM2, as can be seen from figure 2b highlighting its advantages, figure 2b shows a cross section of the device of figure 2a along line X-X. At the overlapping or crossing portions of the electrodes 1, 2, pixels 5 are defined in the active material 3, i.e. the light emitting or photoconductive material. Since the electrodes 1, 2 in the respective electrode arrangements EM1, EM2 are in any case isolated only by a very thin film 6a of insulating material, the thickness δ of which is only a small fraction of the width w of the electrodes 1, 2 and most preferably corresponds to a process-constrained or process-defined minimum feature size f, it can be seen that the electrode arrangement EM according to the invention allows an increase of the fill factor towards one. It should be noted that the electrodes, electrodes epsilon, alternate on the electrode arrangement EM_a，ε_bIn any case, may have different widths W_a，w_bBut then w_a～w_bIn practice, their widths may be considered to have approximately the same value w.

When considering the four pixels 5 shown in fig. 2c₁～5₄The advantages of (2) can be seen in the planar section (4). The area occupied by the insulating walls 6a between the electrodes defines the pixel 5₁...5₄And in any of the electrode arrangements EM1, EM2 the electrode itself will be 4f²+8fδ+4δ². This means that for δ being only f or a slight fraction of the width w of the electrodes 1, 2, the fill factor in the device according to the invention tends to unity, i.e. that close to 100% of the area of the active material 3 sandwiched between the electrode means EM1, EM2 is occupied by the pixels 5, then the average size of the pixels will be f². For example, if f w is set to one and δ is 0.01f, the area of the plane cross section will be 4+80.01+ 0.0004-4.08 and the fill factor will become 4/4.08-0.98, i.e. a fill factor of 98%. If the accessible area of the active material 3 is a, the maximum number of pixels 5 in the matrix will be close to a/f in a device according to the invention². For example, if the design rule used sets f to 0.2 μm, and the area A of the active material 3 is 10⁶μ m, can provide 0.9810⁶/0.2²＝24.5 10⁶One addressable pixel, which means about 2510⁶/mm²The pixel density of (2). Where the electrodes known in the prior art are isolated by a distance d defined by a minimum process-constrained feature size f, the planar cross-section 4 shown in fig. 2c will contain only one pixel 5, then the fill factor is 0.25 or 25% respectively, where the maximum number of pixels achievable will of course be 1/4 of the number achieved by the device according to the invention.

When a device according to the invention as shown in fig. 2a-c is configured as a display device, then the active material 3 is able to emit light when it is excited by a voltage applied to the respective crossed electrodes 1, 2 of the electrode arrangement EM1, EM2, and the pixel 5 defined by the overlap between the respective electrodes 1, 2 is now naturally a pixel in the display. Of course, since the fill factor will tend to be unity in any case, it is possible to obtain a high resolution display in which almost all of the area a of the display is dedicated to the pixels. Moreover, increasing the fill factor from said 0.25 to 1 will allow the display to have a correspondingly increased surface brightness. Since at least the pixels on one side of the display have to be exposed to the outside, this means that the electrode means EM 1; at least electrode 1 in one of EM 2; 2 must be transparent or translucent, which is also true for the material of one of the bottom plates 7. In fig. 2b the base plate 7 can be realized by means of circuits for driving, sensing and controlling as described above, while the counter-base plate 7', indicated with dashed lines, as well as the electrodes 2 must also be transparent or translucent for the light radiation. The insulating material used for the insulating film 6 is of course transparent or translucent in this case as well, and the electrode 2 may be made of Indium Tin Oxide (ITO) which is commonly used in light-emitting devices, as is well known to those skilled in the art.

A first preferred embodiment of the electrode arrangement EM is shown in fig. 3. Here, the electrode arrangement EM comprises a plurality of strip-shaped electrodes epsilon provided on a base plate 7_a，ε_b. Electrode epsilon_aCan be regarded as belonging to a first group of electrodes and is formed by a global layer of suitable electrode material, which is subsequently patterned in a photolithographic step using a suitable mask, with electrodes epsilon between the former_bCan be regarded as belonging to a second group of electrodes which are deposited after application of the insulating wall portions 6a and which deposit the electrodes epsilon generated in the patterning step_aWith a recessed portion therebetween. Two electrodes epsilon_aIs d, the electrodes epsilon_aIs w_aElectrode epsilon_bIs w_b. Now, the value w_a，w_bAnd the distance d has approximately the same magnitude, the minimum value of which passes through the electrodes for generating epsilon_aGiven the minimum feature size f of the process constraints achievable in the patterning process. At the same time, the electrodes epsilon_a，ε_bThe thickness delta of the insulating wall section 6a in between is not constrained by f and may have a thickness up to the value range of nanometers, the only constraint beingIs to provide an insulating film for preventing the electrodes epsilon_a，ε_bLeakage and breakdown therebetween. In other words, if the surface of the base plate 7 that is in contact with the desired electrodes is also electrically insulated, all the strip-shaped electrodes ε are arranged side by side_a，ε_bWill be electrically isolated from each other. It should be noted that the two electrodes epsilon_a，ε_bAnd the height of the insulating wall portion 6a is h and has the equation d ═ w_b+2 δ. If the distance d between the electrodes is chosen as w_a+2d, then the electrode ε_a；ε_bWidth w of_a；w_bWill be the same and equal to the value w, thus all electrodes epsilon_a，ε_bHave the same cross-sectional area and, if the electrodes are made of the same electrically conductive material epsilon, also have the same electrically conductive properties.

In the embodiment of the electrode arrangement EM according to the invention shown in fig. 4, the electrodes epsilon_aFormed by globally applied layers of electrode material in a patterning step, and then globally depositing an insulating film 6 covering the substrate 7 and the electrodes epsilon_a. The conductive material is now at the electrode epsilon_aIs deposited so as to fill and cover the insulating layer 6b in the recess between, and then in a subsequent planarization step, the insulating film 6 is removed to cover the electrodes epsilon_aAnd due to electrodes epsilon_bDepositing the resulting excess electrode material to leave electrodes epsilon exposed at the surface of the electrode layer_a，ε_bAnd is flush with the top edge of the wall portion 6a of the insulating film 6. Whereby all electrodes epsilon_a，ε_bAre exposed on the top surface and can form an ohmic contact with any opto-electronically active material 3 applied thereon, but in the case of capacitive coupling if the active material is a dielectric, for example a liquid crystal material, it is even possible to cover the top surfaces of the electrodes 1, 2 with an insulating film 6 in this particular environment. This of course also applies to the above described embodiments. About electrode epsilon_a，ε_bMinimum width w of_a，w_bThe considerations of (a) are also valid here. And can be seen as electrode epsilon_aHeight h of_aDifferent from the electrode epsilon_bIs highDegree h_bThe difference is an amount δ corresponding to the thickness δ of the portion 6b of the film 6 covering the substrate 7. As mentioned before, this means that, in order to obtain electrodes ε with equal cross-sections_a，ε_b(if desired), e.g. at the electrodes ε_a，ε_bIn case of being made of conductive materials having the same conductivity, it is necessary to increase the electrode epsilon in the patterning process in order to obtain the same conductivity_aThe distance d between them.

The planarization of the electrode layer of the electrode arrangement EM according to the invention may be performed in any suitable way, such as mechanochemical polishing, controlled etching or controlled micro-abrasion processes, in both embodiments as shown in fig. 3, 4. For details regarding the processing of embodiments of the electrode arrangements according to the invention as shown in fig. 3, 4, and their method of manufacture, reference is made to the above-mentioned co-pending norwegian application No. 20015509.

As regards the electrode materials of the electrode means EM used in the device according to the invention, they may be any suitable conductive material mentioned above, such as metals like titanium or aluminium, which are commonly used in electronic devices. The electrode material may also be an organic material, such as a conductive polymer, but must be compatible with the process used to form the insulating thin film layer or any process used to remove portions thereof. Furthermore, as mentioned above, it is clear that the electrodes of at least one electrode means EM must be transparent or translucent to optical radiation, so that the device can be used as a display or photodetector.

It should be understood that the electrode width w of the electrode arrangement EM according to the invention should have a minimum value defined by the minimum feature size f of the process constraints, which of course in the first case is only the first set of electrodes epsilon that have to be formed by patterning_aAnd the distance between the electrodes is limited. Electrode epsilon_bMay be deposited by a process that is not limited by the design rules for the patterning process. Of course, the same applies to the application of insulating films which may be applied, for example, by oxidation, vapor deposition or spraying or sputteringApplied as almost monoatomic sizes. The only requirement being adjacent electrodes epsilon in each set of electrodes of the electrode arrangement EM_aAnd ε_bShould provide the necessary electrical insulation therebetween. Also, while f in conventional microlithographic processes is typically in the range of 0.2 μm or slightly smaller, other currently established or developing techniques allow feature sizes in the nanometer scale range, i.e. electrode widths down to tens of nanometers, and allow, for example, the use of mechanochemical treatments in the nanometer scale range to achieve the necessary planarization, which in any case will yield an electrode arrangement EM having a highly planarized top surface, and in which all the constituent components, i.e. the electrodes ε_a，ε_bAnd the insulating film 6 is flush on the top surface.

In general, the use of an electrode arrangement EM in an apparatus according to the invention, with an active medium sandwiched by two electrode arrangements of the invention and side-by-side strip-shaped electrodes, and oriented at an angle to each other, preferably in a vertical direction, in order to form a matrix-addressable display or photodetector, will allow a fill factor of towards unity, and the maximum number of definable pixels is only subject to design rules applicable to the electrode patterning process.

Fig. 5 schematically shows the structure of a single pixel in an embodiment wherein the device according to the invention is a display. Between the electrode 1 of the first electrode arrangement EM1 and the electrode 2 of the second electrode arrangement EM2, a photo-electro-active material 3 is provided, which comprises light-emitting domains (light-emitting domains) 10, preferably in the form of light-emitting polymer diodes. The light-emitting polymer diode 10 is supplied with an operating voltage V via electrodes 1, 2 connected to a power supply 8_EIt will of course be appreciated that electrodes 1, 2 are each electrode means EM 1; strip electrode 1 of EM 2; 2, in any case the electrode 2 is preferably oriented perpendicularly to the electrode 1. The light emitting diode 10 may be wavelength tunable and in this case the active material 3 will comprise a light emitting diode, wherein the wavelength may be varied by varying the voltage V_ETo tune, for example as described in international published patent application WO 95/031515.

It should be noted that the device according to the invention may also be a non-emissive display, i.e. a display in which the pixels may reflect, absorb or polarize light in response to an applied voltage. This will be the case when the electro-optically active material is a liquid crystal material and such displays are of course well known in the art, but the same advantages as the embodiments with light emitting pixels can be obtained by using the electrode arrangement according to the invention. As described above, since the liquid crystal material is a dielectric, it should be noted that the contact top surface of the electrode device may be actually covered with the insulating film 6. In this regard, reference may be made to the already cited co-pending norwegian application, in which relevant alternative embodiments of the electrode arrangement are disclosed.

Fig. 6 schematically shows one pixel 5 in case the device according to the invention is an embodiment of a light detector. The opto-electronically active material 3 is similar to the luminescent material in the embodiment of fig. 5 and is provided in the interlayer between the electrodes 1, 2, oriented in a similar manner. When the active material is excited by incident light to generate a current or voltage, the electrodes 1, 2 will transmit a signal voltage V_DTo the sense amplifier 9.

It is of course obvious that at least one of the electrodes 1, 2 in fig. 5 or 6 must be transparent, and the same applies to the substrate (not shown) 7 where the electrodes are provided. As regards the opto-electronically active material 3, it may be a light emitting diode or a photodiode as described above, and particularly preferably an organic diode, this type of diode being based on conjugated polymers as already described in international published patent application WO 95/031515. It should be noted that such light emitting polymer diodes may be wavelength tunable and capable of emitting light at multiple wavelengths by varying the operating voltage of the diode. The diodes also have opto-electronic properties in this case and are therefore suitable for use in a detector pixel as shown in figure 6, it being noted that the peak sensitivity wavelengths of the diodes will differ from their peak emission wavelengths and shift towards wavelengths shorter than those emitting light. This is a phenomenon known to those of ordinary skill in the art as Stokes shift (Stokes shift). The diode of the opto-electronically active material can be fabricated as a polymer film having conjugated polymer domains and having a thickness of tens of nanometers or less. The size of the individual diodes should not be very large.

The pixel may comprise a number of physically separated light emitting or light absorbing domains 10, 10', as shown in fig. 7, which may be regarded as a schematic cross-section through a single pixel 5 in a device according to the invention. Of course, the layer 3 of active material has formed therein global layer portions with domains 10, 10', each being only one type of light emitting polymer or light absorbing polymer, and having different light emitting or absorbing wavelength bands. Also, the conjugated polymer film may be an anisotropic electric conductor, and thus a current applied to the active material layer sandwiched between the electrodes 1, 2 flows only between the electrodes defining each isolated pixel 5, and does not flow in the lateral direction. In order to obtain the full effect of light emission or a photo-electric effect, whether light emission or light absorption, all domains 10, 10' should be in contact with the electrodes 1, 2, and it can be seen that in the device according to the invention with the electrode arrangement according to the invention the fill factor tends towards unity, which will in practice be the case, so that in the device according to the invention either one can provide a display with maximum surface brightness or a photo-detector with maximum sensitivity, as is often the case. Furthermore, since the thickness δ of the insulating material 6 is only a small fraction of the electrode width, it is clear that ensuring a high fill factor will allow a high pixel density and an effective pixel area towards the total area a of the global layer of active material 3. Also, the resolution or degree of pixelation, i.e., the number of pixels available in the device, will be at a maximum allowed by the size of the minimum feature size f of the process constraints. In summary, any of the above considerations serve to emphasize the fundamental improvement in the performances that can be obtained by the device according to the invention, whether it is configured as a display or as a photodetector.

When it is configured as a display, it may be monochrome or colorA display. In the latter case, the active material may comprise diode domains 10, 10' emitting light at different wavelengths, depending on the applied operating voltage V_E. For example, V_EAn increase in this would shift the main emission towards shorter wavelengths if the diode domains 10, 10' had their peak emission, for example in the red and blue range, respectively, within the optical radiation spectrum. In other words, the wavelength tuning of an individual pixel is in this case performed by varying the voltage V applied via the electrodes 1, 2 of the contacted pixel_ETo obtain the final product.

Also as mentioned above, the active material may be a liquid crystal material, in which case, of course, the pixel is either capable of reflecting, absorbing light or polarizing when actuated, as is well known to those of ordinary skill in the art.

When the device is configured as an optical detector, it can be used as a detector for a photo camera, in order to highlight its advantages, and necessary modifications have been made to enable a color camera in which the diode domains 10, 10' have different wavelength sensitivities and generate a current response or voltage V_DAnd has components that depend on the wavelength of the incident light. The high resolution (i.e., high pixel density of the apparatus of the present invention) is comparable to conventional photographic film, which may have a format of over 3 · 10 in a 24 × 36mm format⁷And depending on the characteristics of the photosensitive emulsion, linear resolution on the order of 5 μm can be obtained. Scaling the photodetector according to the present invention, to the extent that it is pixilated, designing a 1.2 x 1.2mm detector chip with f ═ 0.20 μm will yield the same performance as a 24 x 36mm film format. However, when the device according to the invention is used as a light detector in an electronic camera, the person skilled in the art should bear in mind that the effective pixel size must be compatible with the wavelength λ of the incident light, i.e. at least 1/2 λ, in other words about 0.1 μ to 1.0 μ for a range from the ultraviolet to the near infrared. This, of course, means that the active area of the active material and the size of the detector must be adjusted accordingly to obtain a resolution comparable to that obtainable with an emulsion.

Claims (9)

1. A matrix-addressable optoelectronic device comprising a functional medium (3) in the form of an electro-optically active material provided on a global layer in a sandwich between first and second electrode arrangements (EM1, EM2), each having parallel strip-shaped electrodes (1; 2), wherein the electrodes (2) of the second electrode arrangement (EM2) are oriented at an angle to the electrodes (1) of the first electrode arrangement (EM1), wherein functional elements (5) are formed in the volume of active material (3) defined by respective overlapping portions between the first electrodes (1) of the first electrode arrangement (EM1) and the second electrodes (2) of the second electrode arrangement (EM2) so as to provide a matrix-addressable array having electrodes (1, 2) in contact with the active material (3), wherein the functional elements (5) in the active material can be addressed by crossing the electrodes (1, 2) -applying a voltage to activate to form a light emitting, light absorbing, reflecting or polarizing pixel in a display device, or alternatively-using incident light to activate to form a pixel in a photodetector and outputting a voltage through electrodes (1, 2) crossing over the pixel, -the active material (3) being in either case selected to be an inorganic or organic material and being capable of emitting, absorbing, reflecting or polarizing light according to a predetermined function when activated by the applied voltage, or being capable of outputting a voltage or current, or both, when stimulated by incident light, whereby addressing of the pixel (5) occurs in any case in a matrix-addressable scheme, and wherein the set of electrodes (EM 1; EM2) in at least one of the electrodes (1; 2) is made of a transparent or semi-transparent material,

characterized in that the electrodes (1; 2) of each electrode arrangement (EM 1; EM2) are provided on respective electrode layers, the electrodes (1; 2) in the electrode arrangements (EM 1; EM2) all having substantially the same width w, the electrodes (1; 2) of each electrode arrangement (EM1, EM2) being electrically insulated from each other by an insulating film (6) having a thickness delta, the size delta being a fraction of the width w, and the minimum value of w is comparable in size to the minimum feature size f of the process constraints, whereby the fill factor of the pixel (5) in the electro-optically active material (3) associated therewith is close to 1, and the number of pixels (5) is close to a maximum defined by the total area A of the active material (3) sandwiched between the electrode means (EM 1; EM2) and the characteristic dimension f, whereby the maximum passes A/f.²To be defined.

2. A matrix-addressable optoelectronic device according to claim 1, characterized in that the electro-optically active material (3) is an anisotropic conductive organic material having diode domains (10) in contact with the electrodes (1, 2) of the electrode means (EM1, EM 2).

3. A matrix-addressable optoelectronic device according to claim 2, characterized in that the organic conducting material (3) is a conjugated light-emitting and/or optoelectronic polymer, whereby the matrix-addressable device can function as a display or as a photodetector or both.

4. A matrix-addressable optoelectronic device according to claim 2, characterized in that the diode domains (10) are capable of emitting light when activated by an applied voltage, whereby the matrix-addressable device can operate as a display.

5. A matrix-addressable optoelectronic device according to claim 2, characterized in that the diode domain (10) is capable of outputting a current or a voltage when excited by incident light, whereby the matrix-addressable device can operate as a photodetector.

6. A matrix-addressable optoelectronic device according to claim 1, characterized in that the electro-optically active material (3) is a liquid crystal material, whereby the matrix-addressable device can be operated as a display with reflective, absorptive or polarizing pixels (5).

7. An electrode arrangement (EM) for use in a matrix-addressable optoelectronic device according to claim 1, comprising an electrode (epsilon) in the form of parallel strip-shaped electrical conductors_a，ε_b) Wherein the electrode layer is provided on an insulating surface of the base plate (7),

characterised in that the thin film electrode layer comprises a thin film electrode layer of width w provided on the base plate (7)_aAnd has a thickness of h_aOf said first group of strip-shaped electrodes (epsilon)_a) Electrodes in the first group (. epsilon.)_a) To be equal to or greater than w_aAre spaced apart from each other; width w_bAnd a thickness h_bSecond set of said strip-shaped electrodes (epsilon)_b) Is provided on a first set of electrodes (epsilon)_a) In the space between, and through a thickness delta of electrically insulating materialThe membrane (6) is electrically insulated from the first set of electrodes, the membrane (6) being at least along the parallel electrodes (epsilon)_a，ε_b) Extend and form between them an insulating wall (6a) of thickness delta, the magnitude of delta and w_aOr w_bRelatively small, first set of electrodes (epsilon)_a) Is spaced apart by a distance d of w_a+2 delta and having an electrode (epsilon)_a，ε_b) And the electrode layer of the insulating film (6) forms a global plane layer in the electrode arrangement (EM) on its base plate (7).

8. An electrode arrangement (EM) as claimed in claim 7, characterized in that the electrodes (ε) in the first set_a) And electrodes in the second group (. epsilon.)_b) With insulating walls (6a) forming part of a thin film (6) of insulating material provided on a layer covering the side edges of the first group of electrodes (ε a) up to its top surface, and on the bottom plate (7) in the space between the former, the electrodes (ε) in the second group_b) A recess portion provided between the wall portions (6a) of the insulating film (6) and located above the portion (6b) covering the bottom plate (7), the electrodes (epsilon) in the second group_b) With the top edge of the insulating wall (6a) and the electrodes (epsilon) in the first group_a) Is flush with the top surface of the first group, whereby the electrodes (epsilon) in the second group_b) Has a height h_b＝h_a- δ and has electrodes (ε)_a，ε_b) And an electrode layer of insulating material (6) is formed in the electrode arrangement (EM) on its base plate (7) to a thickness h_aThe global plane layer of (2).

9. An electrode arrangement (EM) according to claim 7, characterised in that the electrodes (epsilon)_a，ε_b) And the bottom plate (7) is made of a transparent or translucent material.