OLED - BASED MATRIX LIGHT TRANSMITTER FOR HIGH-SPEED OPTICAL COMMUNICATION
20220320207 · 2022-10-06
Inventors
- Alexis FISCHER (Bessancourt, FR)
- Alex Chamberlain CHIME (Corbeil Essonnes, FR)
- Nixson LOGANATHAN (Epinay sur Seine, FR)
Cpc classification
H10K71/00
ELECTRICITY
H10K50/818
ELECTRICITY
International classification
Abstract
A light emitting system (1) intended for optical communication, which presents several OLEDs (2) whose activation allows to obtain different levels of light intensity corresponding to different levels of light modulation, and which comprises an organic optoelectronic device (3) of the OLED (2) type having actuatable zones (5) each with a specific geometric pattern, on a substrate (5) which supports a first layer (6) formed by a plurality of transparent or opaque and conductive anodes (6a, 6b, 6c) laterally separated by engravings (7); a second layer for insulation (8) on regions of the first layer (6), serving to electrically insulate the anodes (6a, 6b, 6c) and to guarantee the continuity of the two following layers and having a thickness e1; a third layer (9) of thickness e2 comprising at least one stack of organic layers (9a, 9b); a fourth layer of metal (10) with a thickness e3 having a plurality of cathodes (10a, 10b) laterally separated from one another and covering said stack of organic layers (9a, 9b), lateral separation profiles (11) of the cathodes (10a, 10b) and of the organic layers (9a, 9b), for electrically insulation the cathodes (10a, 10b), of thickness e4 greater than e1+e2+e3, deposited on the first layer (6) or on the second layer (8).
Claims
1. Light emitting system intended for optical communication, having several OLEDs whose activation allows to obtain different levels of light intensity corresponding to different levels of light modulation, the system comprising: an organic optoelectronic device with OLEDs, the organic optoelectronic device having laterally separated actuatable zones on a substrate which supports: a first layer composed of several transparent and conductive anodes, laterally separated by engravings, each anode Ai having a specific geometric pattern MAi; a second layer for insulation on parts of the first layer, serving to electrically insulate the anodes so as to have separated anodes, the second layer for insulation having a thickness e1; a third layer having a thickness e2 and comprising at least one stack of organic layers; a fourth layer in metal having a thickness e3, and comprising several cathodes laterally separated from each other and covering said at least one stack of organic layers, each cathode Kj having a specific geometrical pattern MKj; lateral separation profiles of the cathodes and of the organic layers, to electrically insulate the cathodes so as to have separated cathodes, the lateral separation profiles having a thickness e4 greater than e1+e2+e3, and being deposited on the first layer or on the second layer for insulation, wherein covering of the anodes, the at least one stack of organic layers, and the cathodes, is realized so as to present facing each other from among said anodes and said cathodes: separated anodes and a common cathode; separated anodes and separated cathodes; and/or a common anode and separated cathodes; defining separated actuatable zones, each actuatable zone comprising at least one part of any said cathode and at least one part of any said anode facing each other, a power supply, electrical wires and electrical contacts connected to the anodes and cathodes for their voltage supply so as to allow during an activation: a switching on of a combination of said actuatable zones, a surface of which is less than or equal to a common surface of facing activated anodes and activated cathodes, connected to the electric wires, means for selective activation and displaying, to activate and display at each activation a total luminous surface which varies according to the number of the actuatable zones turned on, so as to obtain different levels of luminous intensity of the system corresponding to different levels of light modulation, for different activations.
2. The system according to claim 1, wherein the cathodes Kj have specific geometrical patterns MKj different from the geometrical patterns MAj specific to the anodes.
3. The system according to claim 1, wherein the cathodes Kj have specific geometrical patterns MKj different from each other, and/or wherein the geometrical patterns MAi specific to the anodes have specific geometrical patterns MKj different from each other.
4. The system according to claim 1, wherein the organic optoelectronic device is a matrix which is rectangular or square, and which presents OLED with different forms configured to create the matrix.
5. The system according to claim 1, the cathodes and anodes being rectangular and/or L-shaped areas, and/or nested to form a matrix.
6. The system according to claim 1, wherein the OLEDs are micro-OLEDs.
7. The system according to claim 1, wherein the first layer, the fourth layer and a ground plane are separated by gaps without conductive material, the gaps having a size so as to adapt a speed of propagation of an electrical pulse in the device for limiting reflections due to passage of an electrical impulse between the electrical wires and the anodes and/or cathodes.
8. The system according to claim 7, the gaps having a size so that an effective dielectric permittivity of the organic optoelectronic device is equal to a dielectric permittivity of the electrical wires delivering the electrical impulse.
9. The system according to claim 1, wherein: at least one said anode extends between two of said cathodes on a same side of the substrate, at equal distance of the two cathodes, and is separated from the two cathodes with some gaps without conductive material; a transversal dimension T of the at least one anode and a transversal dimension G of the gap between said at least one anode and each of the two cathodes are such that an effective dielectric permittivity εr defined by: 1+(∈r−1)/2*β(γ.sub.2)β(γ.sub.1) is equal to εr.sub.0, which is the dielectric permittivity of the electrical wire; where: ε.sub.r is the dielectric permittivity of the dielectric substrate, γ.sub.1, γ.sub.2 and γ.sub.3 are geometrical parameters,
10. The system according to claim 1, wherein a ground plane is on one side of the substrate, and the anodes and the cathodes are tracks on another side of the substrate and are electrically linked to the ground plane with vias.
11. The system according to claim 1, wherein: the anodes are made of ITO for a downward emission and are made of copper-doped aluminum for an upward emission of the OLEDs; the stack of organic layers comprise: polymers, small molecules, phosphorescent materials, or heat actuatable materials; the substrate is a flexible substrate or made of glass, silicon, silicon oxide, silicon oxide on silicon, polymer, or gallium nitride.
12. The system according to claim 1, wherein the means for selective activation and displaying are configured to enable at least 3 levels of light intensity to be achieved with the actuatable zones: a first level of light intensity, by the activation of one actuatable zone, by the combination of an activated anode, and an activated cathode facing the anode, a second level of light intensity by the activation of two actuatable zones: by a combination of at least two activated anodes facing at least one activated cathode, or by a combination of at least one anode facing at least two cathodes, a third level of light intensity by the activation of three actuatable zones: by a combination of at least three anodes facing at least one cathode, or by a combination of at least one anode facing least three cathodes, or by a combination of at least two anodes facing least two cathodes.
13. The system according to claim 1, wherein the means for selective activation and displaying are configured to allow at least 3 levels of light intensity to be achieved with the actuatable zones: a first level of light intensity, by activation of one said actuatable zone, by the combination of, from among said anodes and said cathodes: a first activated anode, and a first common cathode activated facing the first anode, a second level of light intensity, by activation of at least two separated ones of said actuatable zones, by the combination of, from among said anodes and said cathodes: a first activated anode, and a second activated anode, and a first common cathode activated facing the first and second anodes, a third level of light intensity, by activation of at least three separated ones of said actuatable zones, by the combination of, from among said anodes and said cathodes: a first activated anode, a second activated anode and a third activated anode, and a first common cathode activated facing the first, second and third anodes.
14. The system according to claim 1, wherein the means for selective activation and displaying are configured to allow at least 3 levels of light intensity to be achieved with the actuatable zones: a first level of light intensity, by activation of one said actuatable zone, by the combination of, from among said anodes and said cathodes: a first common anode activated, and a first activated cathode facing the first anode, a second level of light intensity, by activation of at least two separated ones of said actuatable zones, by the combination of, from among said anodes and said cathodes: a first common anode activated, and a first activated cathode and a second activated cathode facing the first common anode, a third level of light intensity, by activation of at least three separated ones of said actuatable zones, by the combination of, from among said anodes and said cathodes: a first common anode activated, and a first activated cathode, a second activated cathode and a third activated cathode facing the first common anode.
15. The system according to claim 1, wherein the means for selective activation and displaying are configured to allow at least 3 levels of light intensity to be achieved with the actuatable zones: a first level of light intensity, by activation of one actuatable zone, by the combination of, from among said anodes and said cathodes: a first activated anode, and a first cathode activated facing the first anode, a second level of light intensity, by activation of at least two separated ones of said actuatable zones, by the combination of, from among said anodes and said cathodes: a first activated anode and a second activated anode, a first activated cathode facing the first anode and a second activated cathode facing the second anode, a third level of light intensity, by activation of at least three separated ones of said actuatable zones, by the combination of, from among said anodes and said cathodes: a first activated anode, a second activated anode and a third activated anode, a first activated cathode facing the first anode, a second activated cathode facing the second anode and a third activated cathode facing the third anode.
16. A process of manufacturing an organic optoelectronic device (3) of an OLED type, comprising the following steps: manufacturing of anodes, on a substrate, by: depositing a first transparent and conductive layer on the substrate, formed by several transparent and conductive anodes, separated laterally by engravings; predefined structuring of a specific geometric pattern for each anode; deposition of a second layer for insulation on parts of the first layer and on the engravings, serving to electrically insulate the anodes, the second layer for insulation having a thickness e1; manufacturing of lateral separation profiles of thickness e4; deposition of a third layer of organic layers with a thickness e2, by evaporation on: the separated anodes, the second layer for insulation, and the lateral separation profiles; deposition of a fourth layer of metal with a thickness e3, by evaporation of a metal on the organic layers and the lateral separation profiles, to form cathodes, which are separated laterally by the lateral separation profiles, the thickness e4 being greater than e1+e2+e3, wherein covering of the anodes, of the organic layers, and of the cathodes is realized so as to present facing each other from among said anodes and said cathodes: separated anodes and a common cathode; separated anodes and separated cathodes; and/or a common anode and separated cathodes; defining different actuatable zones, each actuatable zone comprising at least one cathode part and at least one anode part facing each other.
17. The process according to claim 16, further comprising the following steps: for structuring the anodes: deposition of a first photosensitive resin on the first layer; positioning of a first photolithography mask, having openings that allow the predefined structuring of a specific geometric pattern for each anode, on the first photosensitive resin; photolithography by exposure of the first photosensitive resin through the openings of the first photolithography mask, development, engraving in the first layer to make the separated anodes and cleaning of the first photosensitive resin; for depositing the second layer for insulation: deposition of a second layer for insulation comprising a second photosensitive resin with a thickness e1 on the separated anodes constituting the first layer; positioning of a second photolithography mask; exposure, photolithography and development of the second layer for insulation; for the realization of lateral separation profiles: deposition of at least one further photosensitive resin on the anodes and the second layer for insulation; positioning of a further photolithography mask having openings adapted to create the lateral separation profiles; UV exposure, photolithography and development of the further photosensitive resin to produce the lateral separation profiles.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Other advantages and characteristics of the disclosed devices and methods will become apparent from reading the description, illustrated by the following figures, where:
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DETAILED DESCRIPTION
[0084] The invention relates to a light emitting system 1 intended for optical communication, which presents several OLEDs 2 whose activation allows to obtain different levels of light intensity corresponding to different levels of light modulation.
[0085] The light emitting system 1 is represented schematically on
[0086] The light emitting system 1 comprises: [0087] an organic optoelectronic device 3 with OLEDs 2, as represented on
[0101] The power supply 13 can be a cell, a battery or a photovoltaic cell.
[0102] Advantageously, as represented on
[0103] In a possible embodiment, the lateral separation profiles 11 are produced by photolithography and development, and the second layer 8 is a negative photosensitive resin 11a.
[0104] Advantageously, the lateral separation profiles 11 have a thickness at least four times greater than the sum of the thicknesses e1+e2+e3. More precisely, the thickness of the lateral separation profiles 11 is one to several micrometers.
[0105] Advantageously, the lateral separation profiles 11 have inverted profiles whose tip is in contact with the first layer 6 or the second layer 8 and whose base widened with respect to the tip is located above the fourth layer 10.
[0106] Advantageously, the lateral separation profiles 11 have a long part 11a (composed of negative photosensitive) in contact with the layer for insulation 8 and a head 11b on the long part 11b, the head 11b is larger than the long part 11a, so as to create a space between the long part 11a and the cathodes 10a, 10b.
[0107] The OLEDs 2 can be milli-OLEDs and/or micro-OLEDs.
1) Fast OLED
[0108] More preferably, the OLEDs 2 are micro-OLEDs.
[0109] They can form the organic optoelectronic device 3 emitting a light impulse which can have a time response below tens of ns, for instance 10 ns, in response to an electrical impulse having a pulse duration time below 10 ns.
[0110] The organic optoelectronic device 3 can have two different possible structure.
[0111] 1a) CPW Electrodes
[0112] As shown in
[0113] The organic optoelectronic device 3 presents anode and cathode parts outside the actuatable zones 4, as represented on
[0114] These so-called outer parts allow the anode and the cathode to be connected to the means for selective activation and displaying 14, represented on
[0115] Advantageously in this configuration, the external parts of the cathodes are doubled to insure a 50 ohm characteristic impedance so as to maximize increase the speed of the response, for instance for one cathode 10a (respectively cathode 10b), there are two external parts K1 and K′1 (respectively K2 and K2′).
[0116] When the layers are deposited in this configuration, the lateral separation profiles 11 form a separation line allowing the fourth metal layer 10 to be separated in two and each part to be connected to the corresponding outer cathode parts.
[0117] In this configuration, the cathodes 10a, 10b (and the outer parts of the cathodes K1, K1′, K2, K2′) have a rectangular shape, and the anodes 6a, 6b (A1 and A2) have a rectangular shape except at the intersection of the two anodes separated by step-shaped engravings 7.
[0118] Advantageously, the width of the cathode planes (K1 with K1′ or K2 with K2′) is at least three times as large as the anode (A1 or A2). The widths of the engraving 7 separating the anode A1 from A2 are few micrometers to few hundred of micrometers.
[0119] 1b) Biplanar Shape
[0120] As shown in
[0121] Advantageously, the anodes (A2, A3) have a “twin” anode (A2′, A3′) allowing a lower serial resistance, a better pulse delivery and therefore a faster response of the actuatable zones.
[0122] In this configuration, a ground plane 15 is located below the substrate 5 on which is the organic optoelectronic device 3.
[0123] Advantageously, the organic optoelectronic device 3 have different shape, more preferably a star shape (or a sun shape) and each branch is an electrode.
[0124] Advantageously, the number of branches can be designed adequately, a greater number of branches allows to delimit a greater number of actuatable zones.
[0125] The engravings 7 allow to separate the different anodes 6a, 6b, 6c between them, while the lateral separation profiles 11 separate the cathodes between them.
[0126] Advantageously, the cathodes occupy a part of the branches of the star and the anodes the other part, for example, the cathodes are located on the left branches and the anodes on the right branches, more precisely, the anodes follow each other then the cathodes follow each other, there is no alternation between cathode and anode.
[0127] In one possible embodiment, the anodes and cathodes follow each other intermittently (Anode—cathode—anode—cathode— . . . ).
[0128] As represented on
[0129] As represented on
[0130] The actuatable zones 4a, 4b are defined by the superposition of a part of anode and a part of cathode, each actuatable zone 4a, 4b is the surface of at least one OLED 2.
[0131] The anodes 6a, 6b, 6c can be contiguous to one another and the cathodes 10a, 10b can be contiguous to one another. For example, the distance between two anodes and two cathodes is a few micrometers (˜3 to 10 μm).
[0132] For example, the anodes 6a, 6b, 6c are made of ITO (tin-indium oxide) for a downward emission and are made of copper-doped aluminum (Al:Cu) for an upward emission of the OLEDs 2.
[0133] The second layer for insulation 8 can have dyes and/or quantum dots to absorb the light emitted from the separated actuatable zones 4a, 4b and re-emit light at another visible wavelength.
[0134] Advantageously, the second layer for insulation 8 is on parts of the first layer 6 or parts of the stack of organic layers 9a, 9b, serving to electrically insulate the anodes 6a, 6b, 6c and to ensure the continuity of the individual layers subsequently deposited for organic and metallic layer deposition and having a thickness e1.
[0135] Advantageously, the third layer 9 comprises: polymers, small molecules, phosphorescent materials, heat actuatable materials.
[0136] As represented on the
[0137] In another embodiment, the cathodes Kj have specific geometrical patterns MKj different from each other and/or the geometrical patterns MAj specific to the anodes having specific geometrical patterns MKj different from each other.
[0138] Preferably, the patterns are geometrical because the patterns are chosen to have precise actuatable zones 4a, 4b defining levels of light intensity.
[0139] Preferably, the geometrical patterns MAi and MKj are circles or polygons, more preferably, the polygons have a mathematical ratio allowing the repetition of the pattern. For example, in the case of parallel lines of the same size, the mathematical ratio is a proportionality coefficient equal to 1; in the case of an L shape composed of 3 micro-OLEDs, the mathematical ratio follows this sequence: (n+1)=(n)+2, n representing the number of micro-OLEDs in the pattern, the following sequence means that the next pattern (n+1), adds 2 micro-OLEDs to the number of micro-OLEDs of the previous pattern (n).
[0140] The activation of cathodes and anodes can be sequential or parallel.
[0141] 2) Speed of Propagation of the Electrical Pulse in the System 1 with CPW Electrodes or Biplanar Shape
[0142] Advantageously, the electrical wires are connected to the first layer 6 and to the fourth layer 10; and wherein the first layer 6, the fourth layer 10 and a ground plane 15 are separated by gaps without conductive material, the gaps having a size so as to adapt the speed of propagation of the electrical pulse in the system 1 for limiting the reflections due to the passage of the electrical impulse between electrical wire and the electrodes (anodes and cathodes).
[0143] The gaps can have a size so that an effective dielectric permittivity of the organic optoelectronic device 3 equal to the dielectric permittivity of the electrical wires delivering the electrical impulse.
[0144] Advantageously, the first layer 6, the fourth layer 10 and the ground plane 15 are structured to integrate an excitation or a characterization circuit, including at least a resistance, a capacitance and/or an inductance, which are disposed in series and/or parallel.
[0145] Advantageously, as represented on
[0148] The first layer 6 can extend between two ground planes 15 on the same side of the substrate 5, at equal distance of the two ground planes 15, and is separated from the two ground planes 15 with some gaps G without conductive material.
[0149] The transversal dimension T of the first layer 6 and the transversal dimension of the gap G between said first layer 6 and each of the two ground planes 15 can be such that the effective dielectric permittivity ∈.sub.r effective defined by
is equal to ∈.sub.r0 the dielectric permittivity of the electrical wire.
[0150] Thus, [0151] ∈.sub.r is the dielectric permittivity of the dielectric substrate 5, γ.sub.1, γ.sub.2 and γ.sub.3 are geometrical parameters,
defining β(γ) for γ.sub.1 and γ.sub.2 in the interval 1/√{square root over ((2))}<γ<1;
[0153] h being the thickness of the dielectric substrate 5, and ∈.sub.r represents the relative dielectric permittivity of the dielectric substrate 5. T represents the transversal dimension of the anode 6a, 6b, 6c. G is the distance between the anode 6a, 6b, 6c and ground planes 15 (cathode 10a, 10b in some configurations).
[0154] These ground planes 15 are present on either side of the anode 6a, 6b, 6c and are connected to each other either by the external circuit or by the geometry of the electrodes. For a given dielectric, the characteristic impedance of planar electrodes to produce fast opto-electronic components is given mainly by the form factor defined by the ratio γ1.
[0155] For example, the condition for obtaining the same effective relative dielectric permittivity for the electrodes as for the cables, results in ∈r effective=ε.sub.r=1.5.
[0156] So, we obtained a relation between T, G and the ratio T/(T+2G). To reduce or cancel these reflections, it is therefore possible to modify the geometry of the μ-OLED and in particular the ratio T/(T+2G).
[0157] Considering a glass substrate (ε.sub.r=7.75) of thickness H=1000 μm, and tin oxides and indium (ITO) electrodes with a conductivity σ=5.95e.sup.5 of 100 nm thickness.
[0158] Given a predefined Transversal dimension T value, we calculate Gap G value such as ε.sub.r effective=1.5 to obtain the following table of dimensions:
TABLE-US-00001 T G T/(T + 2G) 100 μm 30 μm 0.625 200 μm 60 μm 0.625 500 μm 146 μm 0.631 1 mm 267 μm 0.651 2 mm 433 μm 0.697 3 mm 548 μm 0.732 4 mm 640 μm 0.757 5 mm 720 μm 0.776 10 mm 1027 μm 0.829
[0159] In reference to
[0160] The dielectric substrate 5, can be a glass sample covered with a conductive layer 6, for example with ITO (
[0161] The following table illustrates the different geometries allowing the reduction of the impulsions:
TABLE-US-00002 Co-planar electrodes Bi-planar electrodes Substrate h T G Z h t T Z Glass 1100 μm 1000 μm 550 μm 50.0Ω 1100 μm 100 nm(Au) 1325 μm 50.0Ω ε.sub.r = 7.75 1100 μm 500 μm 175 μm 50.2Ω 1100 μm 100 μm 31 μm 50.2Ω 900 μm 100 μm 31 μm 50.2Ω Silicon 275 μm 250 μm 125 μm 49.9Ω 275 μm 100 nm(Au) 219 μm 50.0Ω ε.sub.r = 11.9 275 μm 50 μm 195 μm 50.0Ω 525 μm 500 μm 247 μm 50.0Ω 525 μm 100 nm(Au) 418 μm 50.0Ω 725 μm 500 μm 267 μm 50.0Ω 725 μm 100 nm(Au) 577 μm 50.0Ω 725 μm 1000 μm 437 μm 50.0Ω Germanium 500 μm 1000 μm 525 μm 50.0Ω 500 μm 100 nm(Au) 286 μm 50.0Ω ε.sub.r = 16 GaN 500 μm 1000 μm 130 μm 50.0Ω 500 μm 100 nm(Au) 822 μm ε.sub.r = 5.35 Soft substrate 500 μm 1000 μm 118 μm 50.0Ω (PET) 500 μm 500 μm 69 μm 50.0Ω ε.sub.r = 5 plexiglass 500 μm 242 μm 20 μm 50.0Ω ε.sub.r = 3.5
[0162] In a possible embodiment, the system 1 comprises: [0163] the first layer 6 or the fourth layer 10 can be the ground plane 15; and/or [0164] the ground plane 15 is on one side of the substrate 5, and the first layer 6 and the fourth layer 10 are tracks on the other side of the substrate 5 and are electrically linked to the ground plane 15 with vias; and/or [0165] the geometry of the first layer 6 and of the ground plane 15 in regard to the geometry of the fourth layer 10 create an impedance of the device equal to 50 ohms or 75 ohms; and/or [0166] the first layer 6 and/or the fourth layer 10 presents a conductive and transparent layer; and/or [0167] the fourth layer 10 is the cathode made of ITO (indium tin oxide), and the first layer 6 is the anode and is made with a metallic layer; and/or [0168] the dielectric substrate 5 is Glass, silicon, silicon oxide, silicon oxide on silicon, polymers or flexible substrate; and/or [0169] the Organic Opto-Electronic device 3 is composed of OLEDs or Organic photodiodes; and/or [0170] the system 1 comprises superposed on the dielectric substrate 5, the first layer 6 with a first extremity; the fourth layer 10, with another extremity covering partially said first extremity and said organic layer stack 9a, 9b with a part, defining an actuatable zone 4a, 4b of the Micro Organic Opto-Electronic device 3; and/or [0171] the Micro Organic Opto-Electronic device 3 being modeled with a resistance in series with a diode which is in series with a resistance, or by a resistance in series with a dynamic resistance, at least one junction capacitance in parallel with the diode and the resistance, or in parallel with the dynamic resistance, for modelling the actuatable zone 4a, 4b; and/or [0172] the first layer 6 and/or the fourth layer 10 presents a transparent and conductive layer; and/or [0173] the branch connecting the two arms comprises one or several photonic elements; and/or [0174] the photonic element is chosen among the list: a waveguide, a grating, a Distributed Feedback mirror, a laser cavity, a laser cavity made of distributed feedback mirrors, a photonic crystal, a laser cavity made of a defect in a photonic crystal.
2) Activation Combinations
[0175] There are three different types of activation combinations:
[0176] 1. Separated Anodes—Common Cathode
[0177] In this case, the μOLEDs are defined by cutting the anode into several zones electrically separated from each other. This separation is achieved, for example, by etching the transparent and conductive ITO layer.
[0178] In the example of
[0179] In
[0180] In the classical display, the pixels have only two states: on or off, from a light point of view it is a 0 or a 1. In terms of information transmission, with pixels there are only two states, while with matrix OLEDs the number of states depends on the number of cathodes and anodes, for example with 3 anodes and 1 cathode, as shown in
[0181] 2. Common Anode, Separated Cathodes
[0182] In this configuration, the final patterns are not implemented by different areas at the transparent and conductive anode, but by different cathodes K1, K2, K3, as shown in
[0183] 3. Separated Anodes—Separated Cathodes (Definition of Patterns Jointly by Anode and Cathode)
[0184] Approach 2. (common anode, separate cathodes) may show limitations in some particular cases, especially when some patterns are almost nested in others, and when the electrical contacts to the excitation source are difficult to make.
[0185]
[0186] Advantageously, each actuatable zone can be turned on separately.
[0187] In
[0188] It is then possible to switch on level 1 by making contact between anode A1 and cathode K1; level 2 will be the combination of anode A1 and cathode K1 and K2; and to switch on level 3, all contacts A1, A2 and A3; K1, K2 and K3 must be made.
[0189] Another alternative to the problem of strangulation or nested patterns would be to print very fine conductive tracks of noble metal such as gold, for example, on the anode patterns. This improves the injection of current and its flow both within the patterns and at the choke points.
[0190] The system 1 for transmitting with several OLEDs 2 can be a matrix of organic light emitters, e.g. a 3×3 device (anodes×cathodes), as shown in
[0191] In this example, the structuring of this matrix is based on inverted profiles. The activation of the different parts of the matrix can be done by the activation of a combination of anode and cathode, in fact to switch on the different levels, a judicious combination of cathode/anode is activated.
[0192] In an example of embodiment, as shown in
[0193] In the configuration shown, the switching speed is limited by the series resistance and the parasitic capacitance of the largest OLED (64 μOLED). The series resistance decreases with the width of the electrodes and the parasitic capacitance increases with the surface of the OLED. So the capacitance increases faster than the resistance.
[0194] For example, as shown in
[0199] In this example, it is possible to assign 3 bits (and starting 4.sup.th bit) and to have more than 4 levels:
TABLE-US-00003 Level bit OLEDs 0 000 off 1 001 OLED 1 on 2 010 OLED 2 on 3 011 OLEDs 1 & 2 on 4 100 OLED 3 on 5 101 OLEDs 1 & 3 on 6 111 OLEDs 2 & 3 on 7 1000 OLEDs 1 & 2 & 3 on
[0200] The means for selective activation and displaying 14 can be a processor, a computer or a microcontroller.
[0201] Preferably, the means for selective activation and displaying 14, activate one couple (one pair) anode-cathode to turn on one actuatable zone.
[0202] Advantageously, the means for selective activation and displaying 14 of the separated actuatable zones 4a, 4b are: a pulse circuit of the electrical clock or flip-flop type, with a positive and a negative output, switches controlled by the pulse circuit and connecting anodes and cathodes to the power source of the battery or accumulator or generator type (power supply 13).
[0203] The means for selective activation and displaying 14 can be configured to enable at least 3 levels of light intensity to be achieved with the actuatable zones 4a, 4b, through four examples.
EXAMPLES OF COMBINATION FOR THREE ACTUATABLE ZONES
Example 1
[0204] a first level of light intensity, by the activation of one actuatable zone 4a, 4b, by the combination of an activated anode, and a cathode activated facing the anode, [0205] a second level of light intensity by the activation of two actuatable zones 4a, 4b: [0206] by a combination of at least two activated anodes facing at least one activated cathode, or [0207] by a combination of at least one anode facing at least two cathodes, [0208] a third level of light intensity by the activation of three actuatable zones 4a, 4b: [0209] by a combination of at least three anodes facing at least one cathode, or [0210] by a combination of at least one anode facing least three cathodes, or [0211] by a combination of at least two anodes facing least two cathodes.
Example 2
[0212] a first level of light intensity, by the activation of one actuatable zone 4a, 4b, by the combination: [0213] a first activated anode, and [0214] a first common cathode activated facing the first anode, [0215] a second level of light intensity, by the activation of at least two separated actuatable zones 4a, 4b, by the combination: [0216] a first activated anode, and a second activated anode, and [0217] a first common cathode activated facing the two anodes, [0218] a third level of light intensity, by the activation of at least three separated actuatable zones 4a, 4b, by the combination: [0219] a first activated anode, a second activated anode and a third activated anode, and [0220] a first common cathode activated facing the three anodes.
Example 3
[0221] a first level of light intensity, by the activation of one actuatable zone 4a, 4b, by the combination: [0222] a first common anode activated, and [0223] a first activated cathode facing the first anode, [0224] a second level of light intensity, by the activation of at least two separated actuatable zones 4a, 4b, by the combination: [0225] a first common anode activated, and [0226] a first activated cathode and a second activated cathode facing the first common anode, [0227] a third level of light intensity, by the activation of at least three separated actuatable zones 4a, 4b, by the combination: [0228] a first common anode activated, and [0229] a first activated cathode, a second activated cathode and a third activated cathode facing the first common anode.
Example 4
[0230] a first level of light intensity, by the activation of one actuatable zone 4a, 4b, by the combination: [0231] a first activated anode, and [0232] a first cathode activated facing the first anode, [0233] a second level of light intensity, by the activation of at least two separated actuatable zones 4a, 4b, by the combination: [0234] a first activated anode and a second activated anode, [0235] a first activated cathode facing the first anode and a second activated cathode facing the second anode, [0236] a third level of light intensity, by the activation of at least three separated actuatable zones 4a, 4b, by the combination: [0237] a first activated anode, a second activated anode and a third activated anode, [0238] a first activated cathode facing the first anode, a second activated cathode facing the second anode and a third activated cathode facing the third anode.
[0239] The substrate 5 can be transparent for a Top Emission and not transparent for a Bottom Emission. More precisely, the substrate 5 is a flexible substrate or made of glass, silicon, silicon oxide, silicon oxide on silicon, polymer, gallium nitride, diamond.
[0240] Advantageously, the fourth layer 10 is a metallic layer and depending on the thickness, the metallic layer 10 (the fourth layer) can be transparent (20 nm thick) or opaque (>100 nm). More precisely, in the case of a Top Emission, a transparent cathode will be used and for a Bottom Emission, an opaque cathode will be used.
3) Process of Manufacturing
[0241] As represented on
[0255] The process can be use photolithography and engraving, and advantageously comprises the following steps: [0256] for structuring the anodes 6a, 6b, 6c: [0257] deposition of a photosensitive resin R1 on the first layer 6; [0258] positioning of a photolithography mask T1, whose openings allow the predefined structuring of a specific geometric pattern for each anode, on the photosensitive resin R1; [0259] photolithography by exposure of the photosensitive resin R1 through the first openings, development, engraving in the first layer to make the separated anodes and cleaning of the resin; [0260] for depositing the second layer for insulation 8: [0261] deposition of a second layer for insulation 8 comprising a photosensitive resin R2 with a thickness e1 on the separated anodes constituting the first layer 6; [0262] positioning of a photolithography mask T2; [0263] exposure photolithography and development of the second layer for insulation 8; [0264] for the realization of lateral separation profiles 11: [0265] deposition of at least one photosensitive resin R3 on the anodes and the second layer for insulation 8; [0266] positioning of a photolithography mask T3 whose openings make it possible to create the lateral separation profiles 11; [0267] UV exposure photolithography and development of the photoresist to produce the lateral separation profiles 11.
[0268] Advantageously, before the second layer for insulation 8 is applied to the first layer 6, the following steps are carried out: [0269] deposition of a layer of photosensitive resin R2 on the anodes 6a, 6b, 6c; [0270] positioning of a photolithography mask T2 whose openings define the locations intended to receive a metallic layer to produce a metallic contour and/or metallic lines and/or metallic area 12; [0271] photolithography by exposing the positive photosensitive resin layer R2 through the openings and developing; [0272] deposition of the metal layer 12 in such a way that the areas of the anodes 6a, 6b, 6c not covered by the second layer 8 are covered by the metal layer in direct contact with the first layer; [0273] cleaning the photosensitive resin layer R2 to remove it.
[0274] Advantageously, before depositing the light-sensitive resin on the anodes and/or on the second layer for insulation 8, a non-photosensitive resin is deposited on this light-sensitive resin, in order to produce inverted lateral separation profiles 11 which have: [0275] a tip which is in contact with the layer formed by a plurality of separated anodes; and [0276] a base widened in relation to the tip and located above the layer formed by the separated cathodes.
[0277] Advantageously, the photosensitive resin R1 deposited on the first layer 6 is positive or negative, the photosensitive resin R2 forming the second layer 8 is negative, and the photosensitive resin R3 for making the lateral separation profiles 11 is positive.
[0278] The openings of the second mask T2 can be arranged on the second layer for insulation 8, so that photolithography and etching of the second layer for insulation 8 leave the spaces between the anodes filled by the second layer for insulation 8.
[0279] The first layer 6 can be an ITO layer to make the anodes 6a, 6b, 6c and in which aluminum or chromium gold is deposited by evaporation to make the cathodes 10a, 10b.
[0280] Advantageously, the gold-chromium is deposited just after the structuring (engraving) of the anode in order to improve the conductivity in the case of Bottom Emission. More precisely, in the case of Top Emission, the Gold-Chromium deposit is not necessary or even not useful and silver is used for the Top Emission and aluminum can be used in Bottom Emission.
[0281] Details of the Process
[0282] The organic optoelectronic device 3 can be fabricated on different types of rigid substrates such as Glass, Silicon or Gallium Nitride with top emission.
[0283] In another possible embodiment, the manufacturing process can follow the following steps: [0284] Step 1—the realization of the anodes 6a, 6b, 6c on a substrate 5 (Structuring of the anode) [0285] Cleaning step [0286] Photolithography step [0287] Engraving step [0288] Cleaning step [0289] Step 2—Metallization [0290] Cleaning step [0291] Photolithography step [0292] Metallization [0293] Lift-Off [0294] Step 3—Structuring of the partition lines of the cathode in “cap profile” [0295] Cleaning step [0296] Photolithography on base plate of separation profile [0297] Step 4—Organic layer and cathode deposition (Aluminum) [0298] The last step in the OLED manufacturing process consists of depositing the organic and metallic layers. [0299] Vacuum Thermal Evaporation [0300] Encapsulation
[0301] Results
[0302] In
[0303] the
[0304] In
[0305] the figures show the excitation signal, the electrical response and the optical response for pulses of 300 ps up to 1 ns. [0306] Polymer-based μOLEDs respond at 300 ps, a first in the world.
[0307] The results of these matrix OLEDs reach world records, optical responses of less than 800 ps have been recorded following an electrical excitation for ultra-short pulse durations on μOLEDs and 300 ps for Polymer OLEDs. These worldwide results are a revolution for applications such as optical telecommunications, optical buses, Lifi, etc.