Method for manufacturing optoelectronic devices

Abstract

The invention relates to a method for manufacturing an optoelectronic device (1) comprising an array of diodes (D1, D2, D3) and an array of color conversion portions (P1, P2), the method comprising the steps of: providing an array of diodes (D1, D2, D3) and an upper electrode layer (E1, E2, E3); depositing a dielectric layer (26) having a substantially zero surface potential; applying a potential difference between the electrode (2) and the first upper electrode layer (E1) such that a first pattern (M1) having a non-zero surface potential is formed in the dielectric layer (26); generating a first color conversion portion (P1) by contacting the dielectric layer (26) with a colloidal solution (S1) comprising first photoluminescent particles (p1).

Description

Technical Field

[0001] The field of this invention is a method for manufacturing an optoelectronic device comprising an array of electroluminescent emission or detection diodes associated with a color conversion section. This invention is particularly applicable to displays and image projectors. Background Technology

[0002] Existing optoelectronic devices include identical arrays of electroluminescent diodes, at least partially covered by color conversion components. These optoelectronic devices can form displays or image projection systems comprising arrays of emitting pixels of different colors.

[0003] In this type of optoelectronic device, each light-emitting pixel includes one or more light-emitting diodes associated with a color conversion section. In order to obtain light-emitting pixels suitable for emitting light radiation of different colors (e.g., blue, green, or red), the light-emitting diodes may be adapted to emit the same light (e.g., blue), and the green and red pixels may include light conversion sections adapted to at least partially absorb incident blue light and responsively emit green or red light.

[0004] Therefore, the light-emitting diodes (LEDs) are preferably identical and emit light radiation of the same wavelength. These LEDs can be formed based on semiconductor materials containing elements from Group III and Group IV of the periodic table, such as Group III-IV compounds, particularly gallium nitride (GaN), indium gallium nitride (InGaN), or aluminum gallium nitride (AlGaN). These LEDs are arranged to form an array with a front facet through which the generated light radiation is transmitted.

[0005] The light conversion portion can be formed by a bonding array comprising particles of photoluminescent material, such as yttrium aluminum garnet (YAG)YAG:Ce activated by cerium ions. The photoluminescent particles can also be quantum dots, i.e., in the form of semiconductor nanocrystals, where quantum confinement is essentially three-dimensional.

[0006] The fabrication method may include deposition, followed by the construction of a photoluminescent layer to form a first light conversion portion, for example, suitable for converting blue to red. These steps are then performed again to form a second light conversion portion, for example, suitable for converting blue to green. However, a drawback of this method is that it is not suitable for diode arrays with small pixel pitches (e.g., on the order of 5 μm) because there may be problems with aligning or overlapping the light conversion portions with each other.

[0007] Document WO2014 / 136023 describes another fabrication method using an electret layer covering a diode array. This method first includes a step of applying a charge pattern to the upper surface of a dielectric layer to obtain the electret layer. For this purpose, a polarized atomic force microscopy (AFM) tip is used for localized charge injection. Then, a step of locally depositing colloidal nanocrystals on the charge pattern is performed. For this, the electret layer is contacted with a colloidal solution containing nanocrystals, which are naturally deposited on the charge pattern under the action of dielectric force. However, this method has a particular drawback: the charge must be sequentially injected by moving the AFM tip on the surface of the upper surface to form the charge pattern therein.

[0008] Document WO2021 / 023656 describes a similar method in which a charge pattern is defined by a stamping technique (i.e., by contacting a polarized buffer layer with a dielectric layer intended to form an electret layer). The lower end face of the buffer layer is configured to form polarization teeth in contact with the dielectric layer. This yields an electret layer with a charge pattern on its top face. The electret layer is then contacted with a colloidal solution, and nanocrystals are deposited onto the charge pattern by dielectric electrophoresis. However, a specific drawback of this method is the need for precise positioning of the buffer layer relative to the diode array. The positioning uncertainty of the buffer layer relative to the diode array can be problematic, especially for diode arrays with small pixel pitches (e.g., approximately 5 μm). In fact, this positioning uncertainty or inaccuracy can lead to poor positioning of the light conversion section relative to the diode, resulting in a degraded performance of the optoelectronic device. Summary of the Invention

[0009] The object of the present invention is to at least partially overcome the disadvantages of related technologies, and more specifically, to provide a method for manufacturing optoelectronic devices, wherein a color conversion portion is generated on a corresponding diode in a localized and self-aligned manner, while limiting the risk of misalignment relative to the diode.

[0010] Therefore, the subject of this invention is a method for manufacturing an optoelectronic device, the optoelectronic device comprising: a diode array including a rear end face and a front end face opposite to each other, the front end face being used to receive or transmit light radiation; and a color conversion portion array disposed on the front end face, the color conversion portion array including a first color conversion portion facing a diode in the diode array referred to as a first diode.

[0011] The method includes the following steps:

[0012] - Provides a photoelectric structure, the photoelectric structure comprising: a diode array; at least one lower electrode layer disposed thereon.

[0013] The rear end facet is configured to polarize the diode; and the front end facet is configured to polarize the diode, the upper electrode layer including a first upper electrode layer.

[0014] The electrode layer is configured to polarize the first diode and is different from the other upper electrode layers;

[0015] - A deposited dielectric layer covers the diode array and the top electrode layer, with the top surface of the dielectric layer opposite the front end face.

[0016] The surface potential is essentially zero;

[0017] - An electric current is applied between a temporary electrode disposed on a dielectric layer on one side and a first upper electrode layer on the other side.

[0018] The potential difference, thereby forming a first pattern with a non-zero surface potential in the dielectric layer, the first pattern being...

[0019] At a location facing only the first upper electrode layer; then remove the temporary electrode;

[0020] - The first color is generated by contacting the dielectric layer with a first colloidal solution containing first photoluminescent particles.

[0021] In the color conversion section, the first photoluminescent particles are deposited on the dielectric layer only facing the first pattern with a non-zero surface potential, thereby forming the first color conversion section.

[0022] Some preferred, but non-limiting, aspects of this manufacturing method are as follows.

[0023] The color conversion section array may include a second color conversion section, which is different from the first color conversion section and is positioned facing a diode referred to as a second diode in the diode array. Furthermore, the photoelectric structure may include a second upper electrode layer in the upper electrode layer, which is configured to polarize the second diode. After generating the second color conversion section, the method may include the following steps:

[0024] - Applying an electric current between a temporary electrode disposed on a dielectric layer on one side and a second upper electrode layer on the other side.

[0025] The potential difference, thereby forming a second pattern with a non-zero surface potential in the dielectric layer, the second pattern being...

[0026] At a position facing only the second upper electrode layer; then remove the temporary electrode;

[0027] - The second color is generated by contacting the dielectric layer with a second colloidal solution containing second photoluminescent particles.

[0028] In the color conversion section, the second photoluminescent particle is different from the first photoluminescent particle. The second photoluminescent particle is deposited on the dielectric layer only facing the second pattern with a non-zero surface potential, thereby forming the second color conversion section.

[0029] Each top electrode layer can completely cover the diode, and each top electrode layer is located on top of the diode it covers.

[0030] During the step of applying a potential difference between the temporary electrode and the upper electrode layer, the lower electrode layer may be non-polarized.

[0031] During the step of applying a potential difference between the temporary electrode and the upper electrode layer, the lower electrode layer, which is then polarized, may be interconnected.

[0032] The diodes can be in contact with the lower electrode layers, which are different from each other, so that each diode can be selectively activated.

[0033] After generating the color conversion portion, the method may include the following steps: interconnecting the first upper electrode layer and the second upper electrode layer.

[0034] After generating the color conversion section, the method may include the following steps: interconnecting all the upper electrode layers.

[0035] Diodes can have the same light emission or absorption characteristics.

[0036] Diodes can be generated based on organic semiconductor compounds or inorganic semiconductor compounds.

[0037] The present invention also relates to a method for jointly and simultaneously manufacturing multiple optoelectronic devices from the same substrate, comprising: simultaneously implementing the method according to any of the foregoing features for each optoelectronic device.

[0038] Within the scope of the common manufacturing method, during the step of applying a potential difference between the temporary electrode and the upper electrode layer, the temporary electrode can continuously cover the entire diode array. Furthermore, the then polarized upper electrode layer can be interconnected. Attached Figure Description

[0039] Other aspects, objects, advantages, and features of the invention will become clearer from the following detailed description of preferred embodiments, which is given by way of non-limiting example with reference to the accompanying drawings, in which:

[0040] Figures 1A to 1M Different steps of a method for manufacturing an optoelectronic device according to an embodiment are shown, wherein the electret dielectric layer is locally polarized by an upper electrode layer that provides polarization of the diode during diode activation;

[0041] Figure 2A This is a partial top view of an optoelectronic device according to another embodiment, wherein the upper electrode layers of the D1 type diodes are interconnected over the scope of the optoelectronic device, similar to the upper electrode layers of the D2 type diode.

[0042] Figure 2B This is a partial top view of a plurality of optoelectronic devices according to another embodiment, which are jointly manufactured from the same substrate (wafer), wherein the upper electrode layers of the diodes of the first type of light-emitting pixels are interconnected over the substrate, similar to the upper electrode layers of the diodes of the second type of light-emitting pixels.

[0043] Figures 3A to 3D Different steps of a method for manufacturing an optoelectronic device according to another embodiment are shown, wherein the diode is an organic light-emitting diode. Detailed Implementation

[0044] Throughout the accompanying drawings and the remainder of the specification, the same reference numerals denote the same or similar elements. Furthermore, for clarity, various elements are not shown to scale. Moreover, different embodiments and variations are not mutually exclusive but can be combined together. Unless otherwise stated, the terms "substantially," "about," and "approximately" mean within a range of 10%, preferably within a range of 5%. Furthermore, unless otherwise stated, the terms "between" and their equivalents mean including boundary values.

[0045] This invention relates to a method for manufacturing an optoelectronic device comprising a diode array, wherein at least a portion of the diodes in the diode array are covered by a color conversion portion to form an array of light-emitting pixels of different colors. The diodes may be emitting diodes, such that the optoelectronic device can be, for example, a display screen, or the diodes may be detection diodes, such that the optoelectronic device can be an array photodetector. Furthermore, the diodes may be organic (OLED) or inorganic (LED) light-emitting diodes, or organic or inorganic photodetectors.

[0046] The color conversion portion is generated by locally depositing photoluminescent particles on an electret dielectric layer, where a predefined pattern of non-zero surface potentials is used. As detailed below, these surface potentials are formed specifically by means of an upper electrode layer, which also provides polarization for the diode during activation. As detailed below, these upper electrode layers can be shared for each type of color pixel, but different for different types of color pixels. On the other hand, once the color conversion portion is generated, the upper electrode layers can remain shared for each type of color pixel, or they can be shared for all color pixels, or they can be different for each pixel. Sharing means that they are interconnected to apply the same potential.

[0047] As a general rule, an electret layer is a dielectric layer containing charge or quasi-permanent dipole polarization. Furthermore, the surface potential of the electret dielectric layer on its upper surface is not zero. This allows the electret dielectric layer to emit an external electric field without an applied field. Within the scope of this invention, the upper surface of the electret dielectric layer has regions with non-zero surface potential (referred to as patterns). Outside these patterns, the surface potential is essentially zero.

[0048] Therefore, during the generation of the color conversion portions, the upper electrode layers are distinct and distributed according to the color conversion pixel type. This results in a pattern of non-zero surface potential, where photoluminescent particles are naturally deposited locally via electrophoresis or dielectric electrophoresis during the formation of the color conversion portions. Furthermore, the light conversion portions are naturally located facing (i.e., "perpendicular to") the surface potential pattern, and not outside of these predetermined patterns. This method then allows for precise definition of the surface potential pattern on the upper surface of the electret dielectric layer, even when the diode array size is large (particularly when it is manufactured using 200mm wafer technology) and / or the pixel pitch of the diode array is small (e.g., approximately 5 μm).

[0049] Therefore, for example, in the case of a red, green, and blue pixel (RGB) array, where the diodes are identical and all emit the same blue light, during the generation of the red conversion section, only the upper electrode layer of the red pixel is activated, while the upper electrode layers of the other pixels (green and blue) are not activated. Similarly, during the manufacturing of the green conversion section, only the upper electrode layer of the green pixel is activated, while the upper electrode layers of the other pixels (red and blue) are not activated.

[0050] The color conversion portion is formed from particles made of at least one photoluminescent material, preferably nanoparticles with a maximum size between 0.2 nm and 1000 nm (e.g., between 0.2 nm and 100 nm, and e.g., between 1 nm and 30 nm). The size and / or composition of the photoluminescent particles are selected according to the desired emission wavelength. The particles can be of any shape, such as spherical, angular, flat, elongated, etc.

[0051] Photoluminescent particles can be quantum dots, i.e., quantum-confined semiconductor nanocrystals that are essentially three-dimensional. The average size of the quantum dots can then be between 0.2 nm and 50 nm, for example, between 1 nm and 30 nm. Photoluminescent particles can also be nanosheets, i.e., nanoparticles that are essentially two-dimensional in shape. Furthermore, the minimum dimension (thickness) is smaller than the other two dimensions, length and width, preferably with a ratio of at least 1.5.

[0052] Photoluminescent particles can be specifically formed from at least one semiconductor compound, selected from, for example, cadmium selenide (CdSe), indium phosphide (InP), indium gallium phosphide (InGaP), cadmium sulfide (CdS), zinc sulfide (ZnS), cadmium oxide (CdO) or zinc oxide (ZnO), zinc cadmium selenide (CdZnSe), zinc selenide (ZnSe) doped with, for example, copper or manganese, graphene, or other potentially suitable semiconductor materials. The nanoparticles can also have a core / shell structure, such as CdSe / ZnS, CdSe / CdS, CdSe / CdS / ZnS, PbSe / PbS, CdTe / CdSe, CdSe / ZnTe, InP / ZnS, etc. The particles can also have a perovskite crystal structure, including atoms as listed for nanoparticles, as well as Cs, Mn, and Br.

[0053] Furthermore, the light conversion section is adjusted to at least partially convert incident light radiation of a first wavelength λ1 into emitted light radiation of a larger wavelength λ2. For example, the light conversion section can be adjusted to absorb blue light, i.e., whose wavelength is between approximately 440 nm and approximately 490 nm, and emit green light, i.e., whose wavelength is between approximately 495 nm and approximately 560 nm, or emit red light, i.e., whose wavelength is between 600 nm and 650 nm. Here, wavelength refers to the wavelength at which the emission spectrum has an intensity peak.

[0054] Purely for illustrative purposes, a diode can be an emitting type, and its emission spectrum can be in the visible or infrared (e.g., NIR or SWIR) or even ultraviolet (200 nm to 400 nm) range. In the case of a light-emitting diode array, the incident light radiation is radiation emitted by the diode, while in the case of a photodiode, the incident light radiation consists of light radiation from the external environment that is directed at the photodiode. In the latter case, the diode is tuned to absorb all different lengths of incident light radiation contained in the same predetermined absorption spectrum.

[0055] Figures 1A to 1M Different steps of a method for manufacturing an optoelectronic device 1 according to an embodiment are illustrated. In this example, the optoelectronic device 1 includes an array of red, green, and blue (RGB) type light-emitting pixels. Each pixel is formed by at least one light-emitting diode (one diode per pixel). Optionally, the optoelectronic device 1 may include an array of other types of light-emitting pixels, such as an array of RGB-IR type (IR stands for infrared) light-emitting pixels. Furthermore, the diode may optionally be a photodiode.

[0056] The description herein and below defines an orthogonal three-dimensional direct reference frame XYZ, in which the X and Y axes form a principal plane in which the control substrate 10 extends, and in which the Z axis is oriented along the thickness of the diode array in the front face direction. The terms "lower" and "upper" are defined relative to incremental positioning along the +Z direction.

[0057] refer to Figure 1A An array of light-emitting diodes (LEDs) is provided. In this example, the diodes are categorized into three types, labeled D1, D2, and D3, according to the type of light-emitting pixel they belong to. For example, here, blue pixels correspond to diode D1, red pixels to diode D2, and green pixels to diode D3. The diodes are located on the control substrate 10 and are polarized via one or more lower electrode layers 21 and upper electrode layers E1, E2, and E3. Other configurations are also possible, particularly when the control substrate 10 is conductive. The diode array has a rear end face and a front end face opposite to the rear end face, which is assembled and connected to the control substrate 10. The front end face is used to receive or transmit light radiation. In the example where the diodes are emitting, the front end face transmits the light radiation emitted by the diodes.

[0058] In this example, the control substrate 10 performs multiple functions: mechanical support for the diode array, polarization of the upper electrode layers E1 and E2 during the generation of light conversion sections P1 and P2, and polarization of diodes D1, D2, and D3 during optoelectronic device operation. Here, the control substrate includes a CMOS-type control circuit and has an electrical connection pad 11 flush with the upper surface and in contact with the lower electrode layers 21 of diodes D1, D2, and D3. These lower electrode layers 21 are distinct layers; that is, each lower electrode layer 21 of a diode is physically different from the lower electrode layer 21 of its adjacent diode. This configuration is described in detail in document WO2017 / 194845A1.

[0059] Here, diodes D1, D2, and D3 are inorganic light-emitting diodes (LEDs). They can be produced using conventional methods, for example, by epitaxially growing a semiconductor layer from a growth substrate and then transferring it onto a control substrate 10. Each diode D1, D2, and D3 can be formed by stacking the following: a lower semiconductor portion 22 (facing the control substrate 10), doped with a first type of conductivity (e.g., p-type), electrically contacting a lower electrode layer 21; an active region 23 emitting light radiation from the LED; and an upper semiconductor portion 24, doped with a second type of conductivity (e.g., n-type), electrically contacting an upper electrode layer E1, E2, or E3. Diodes D1, D2, and D3 can be formed from the same semiconductor compound, such as a III-V group compound based on GaN, InGaN, or AlGaN.

[0060] Preferably, diodes D1, D2, and D3 are structurally identical, such that the light radiation emitted from one diode is identical in wavelength to that from the other. In this example, diodes D1, D2, and D3 are tuned to emit light radiation in the blue range, i.e., their emission spectrum has an intensity peak at wavelengths between approximately 440 nm and 490 nm.

[0061] Figure 1B yes Figure 1A The diagram shows a top view of the diode array. This is obviously an example, as other configurations are possible. Here, each RGB pixel includes three diodes D1, D2, and D3. Here, the upper electrode layer E1, used to polarize diode D1, extends along a plurality of adjacent diodes D1. The same applies to the upper electrode layer E2, intended to polarize diode D2, and the upper conductor, intended to polarize diode D3. Preferably, the upper electrode layers E1 are interconnected via lateral conductive strips E1l. The upper electrode layers E2 are also interconnected via lateral conductive strips E2l. The upper electrode layers are connected to the control substrate via connecting pads 3 (pad 31 for electrode layer E1 and pad 32 for electrode layer E2), for example, via conductive vias extending through the dielectric filling material 25 surrounding diodes D1, D2, and D3.

[0062] Preferably, electrode layer E1 completely covers diode D1 in the XY plane, while electrode layer E2 completely covers diode D2, and electrode layer E3 completely covers diode D3. Clearly, electrode layers of the same type (e.g., E1) will not extend towards other types of diodes (e.g., D2 and D3).

[0063] The lower and upper electrode layers are made of conductive materials. The lower electrode layer 21 can be made of at least one metallic material selected from Ti, Ni, Pt, Sn, Au, Ag, Al, Pd, W, Pb, Cu, AuSn, TiSn, or alloys of these elements. They are preferably reflective to the light radiation emitted by the diode, and therefore can be based on Ag. Furthermore, the materials of the upper electrode layers E1, E2, and E3 are at least partially transparent to the light radiation emitted by the diode, and can be, for example, indium tin oxide (ITO) or a translucent fine metallic material (e.g., Ag).

[0064] refer to Figure 1CThen, a dielectric layer 26 is generated to form the electret layer. Dielectric layer 26 covers the diode array and thus the top electrode layers E1, E2, and E3. The surface potential of this dielectric layer is initially essentially zero, meaning there is no unwanted non-zero surface potential pattern. Dielectric layer 26 is made of a dielectric material, such as an inorganic material, like silicon oxide, nitrides, or oxynitrides, such as SiO2, Si3N4, Al2O3 (especially in the case of OLEDs), etc. The thickness of this dielectric layer can be on the order of several hundred nanometers, for example, approximately 400 nm.

[0065] refer to Figure 1D A surface potential pattern M1 is generated by locally electrostatically polarizing the dielectric layer 26, and then an electret dielectric layer is formed. For this purpose, a temporary electrode 2 is placed on top of the dielectric layer 26 and preferably in contact with it. Note that the temporary electrode 2 can be composed of a rigid conductive plate or a conductive liquid layer (metal, electrolyte, etc.). A potential difference is applied between the temporary electrode 2 on one side and only the upper electrode layer E1 on the other side. This potential difference can be on the order of tens or hundreds of volts, for example, between 10V and 200V. In this step, only the upper electrode layer E1 is activated, not the other upper electrode layers E2 and E3. The non-zero surface potential pattern M1 is locally formed on the upper end face of the electret dielectric layer 26, facing only diode D1 and not diodes D2 and D3. The temporary electrode 2 is then removed. Note that during this step, the lower electrode layer 21 remains non-polarized, so that diodes D1, D2, and D3 are in an inactive state.

[0066] Figure 1E and 1F The obtained structure is shown. The surface potential pattern M1 exists only at the location facing the upper electrode layer E1. In other words, the surface potential of the electret dielectric layer 26 is essentially zero anywhere except at the location facing the upper electrode layer E1. Note that in this example, the surface potential pattern M1 may not extend towards the lateral conductive strip E1l used to connect the upper electrode layer E1.

[0067] refer to Figure 1GThe first color conversion portion P1 is generated by locally depositing first photoluminescent particles p1 on the electret dielectric layer 26, facing only the surface potential pattern M1. For this purpose, a process similar to that described in documents WO2014 / 136023 and WO2021 / 023656 is followed. Therefore, a colloidal solution S1 containing the first photoluminescent particles p1 is in contact with the upper surface of the electret dielectric layer 26. The photoluminescent particles p1 are adapted to convert blue light to red light. Therefore, the entire stack can be immersed in the colloidal solution S1, or droplets of such solution can be deposited on the electret dielectric layer 26. Due to the non-zero surface potential located in the pattern M1, a non-uniform electric field is generated, which triggers the local deposition of the photoluminescent particles p1 by electrophoresis or dielectric electrophoresis. Furthermore, the photoluminescent particles p1 are deposited substantially facing the first pattern M1 (and therefore facing diode D1), and not substantially outside the pattern M1 (i.e., not facing diodes D2 and D3). The contact time of the colloidal solution S1 on the electret dielectric layer 26 depends specifically on the quality of the photoluminescent particles p1 to be deposited, and therefore on the desired thickness of the color conversion portion P1 and the value of the surface potential. For example, the thickness of the color conversion portion P1 can be on the order of several hundred nanometers, for example, approximately 400 nm. The colloidal solution S1 is then removed, and the electret dielectric layer can be dried.

[0068] Figure 1H and Figure 1I The resulting structure is shown. The color conversion portions P1 exist only facing the upper electrode layer E1 and therefore facing diode D1. They do not extend towards diodes D2 and D3. Therefore, the relative positioning of the color conversion portions P1 with respect to diode D1 is optimal for the red pixel. Portions P1 do not extend towards diodes D2 and D3 and advantageously completely cover diode D1 in the XY plane. Note that here, the color conversion portions P1 form different pads; however, the same pads extend towards multiple adjacent diodes D1. The color conversion portions P1 can be thinly encapsulated (e.g., in Al2O3).

[0069] The aforementioned steps can then be repeated to generate the color conversion section P2 at the position facing diode D2, where a green pixel is formed. In practice, the color conversion section P1 is adapted to convert blue light (wavelength between approximately 440nm and 490nm) into red light (wavelength between 600nm and 650nm). Conversely, the color conversion section P2 is adapted to convert blue light into green light (wavelength between approximately 495nm and 560nm).

[0070] refer to Figure 1JA surface potential pattern M2 is generated by locally electrostatically polarizing the electret dielectric layer 26. For this purpose, a temporary electrode 2 is placed again on top of the electret dielectric layer 26, preferably in contact with the top of the electret dielectric layer 26. In this example, the temporary electrode 2 is a liquid metal (or electrolyte) layer, but it could obviously be composed of a rigid conductive plate. A potential difference is applied between the temporary electrode 2 and only the upper electrode layer E2. This potential difference can be, for example, between 10V and 200V. In this step, only the upper electrode layer E2 is activated, not the other upper electrode layers E1 and E3. The non-zero surface potential pattern M2 is formed locally at the upper end face of the electret dielectric layer 26, facing only diode D2 and not diodes D1 and D3. The temporary electrode is then removed.

[0071] Figure 1K The resulting structure is shown, in which the electret dielectric layer 26 comprises only the surface potential pattern M2. In practice, the patterns M1 may have disappeared after a predetermined time, or may have been removed (e.g., during cleaning). They may also be present, but shielded by the opposing pad P1. The surface potential pattern M2 exists only facing the upper electrode layer E2. In this example, the surface potential of the electret dielectric layer 26 is essentially zero everywhere except where it faces the upper electrode layer E2. Note that in this example, the surface potential pattern M2 may not extend towards the transverse conductive strip E2l used to connect to the upper electrode layer E2, because the temporary electrode 2 is not positioned on top of the transverse conductive strip.

[0072] refer to Figure 1LThe color conversion portion P2 is generated by locally depositing a first photoluminescent particle p2 (facing only the surface potential pattern M2) on the electret dielectric layer 26. For this purpose, as described above, a colloidal solution S2 containing the photoluminescent particle p2 is brought into contact with the upper surface of the electret dielectric layer 26. The photoluminescent particle p2 differs from particle p1 in that it is adapted to convert blue light into green light. Therefore, the entire stack can be immersed in the colloidal solution S2, or droplets of this solution can be deposited onto the electret dielectric layer. Due to the non-zero surface potential located in the surface potential pattern M2, a non-uniform electric field is generated, which triggers the local deposition of the photoluminescent particle p2 through electrophoresis or dielectric electrophoresis. Furthermore, the photoluminescent particle p2 is deposited substantially facing the pattern M2 (and therefore facing the diode D2), and is not deposited substantially outside the pattern M2 (i.e., not facing the diodes D1 and D3). The contact time of the colloidal solution S2 on the electret dielectric layer 26 depends specifically on the quality of the photoluminescent particles p2 to be deposited, and therefore on the desired thickness of the color conversion portion P2. For example, the thickness of the color conversion portion P2 can be on the order of several hundred nanometers, e.g., approximately 400 nm. The colloidal solution S2 is then removed, and the electret dielectric layer 26 can be dried. An encapsulation layer can then be deposited.

[0073] Figure 1M The obtained optoelectronic device 1 is shown. Color conversion portion P1 exists only facing diode D1 and defines a red pixel; color conversion portion P2 is located only facing diode D2 and defines a green pixel. Here, diode D3 is not covered by the color conversion portions, thus forming a blue pixel. An RGB pixel array device is obtained, wherein the color conversion portions P1 and P2 have been deposited locally and self-aligned towards the desired diodes via electrophoresis or dielectric electrophoresis on the electret dielectric layer 26, in which local polarization has been achieved using upper electrode layers E1 and E2 for polarizing the diodes. Therefore, during the operation of optoelectronic device 1, it is not necessary to specifically generate an upper electrode for generating the light conversion portion, which is different from the upper diode polarization electrode.

[0074] Therefore, this avoids the step of locally injecting charge into an initially uncharged dielectric layer using an AFM tip or conductive buffer layer. Furthermore, the method is also fast and the generation of the light conversion portion is spatially precise, even in the case of diode arrays made from large substrates (e.g., 200 mm) and / or where the pixel pitch is very small (e.g., 5 μm).

[0075] Figure 2A It is based on Figure 1B A top view of a modified optoelectronic device 1. The emitting surface of optoelectronic device 1 is defined by dashed lines.

[0076] Here, each upper electrode layer E1 of different pixels is electrically connected to the same connection pad 31 via a lateral conductive strip E1l extending on the edge of the emitting surface. The connection pad 31 may be a conductive via that passes through the dielectric filling layer 25 of the optoelectronic structure to contact the conductive pad 11 of the control substrate 10 (see [link]). Figure 1A Similarly, each upper electrode layer E2 is electrically connected to the same connecting pad 32 via a lateral conductive strip E2l. The connecting pad 32 may also be a conductive via connected to the control substrate 10.

[0077] Furthermore, in this example, each upper electrode layer E3 is in contact with a conductive via 33 connected to the control substrate 10. Here, since the pixel is a blue pixel, the diode D3 is not covered by the light conversion portion.

[0078] Therefore, during the localized and self-aligned deposition step of photoluminescent particles p1, the upper electrode layers E1 are all interconnected and simultaneously polarized, while the upper electrode layers E2 and E3 are non-polarized. During the localized deposition step of photoluminescent particles p2, the upper electrode layer E2 is all interconnected and simultaneously polarized, while the upper electrode layers E1 and E3 are non-polarized.

[0079] Finally, at the end of the fabrication of optoelectronic device 1, the upper electrode layers E1 and E2 can be interconnected to form a common upper electrode for diodes D1 and D2. This can be accomplished by means of a lateral conductive strip E12l extending from the lateral conductive strip E1l of layer E1 along the direction of the lateral conductive strip E2l of layer E2. A conductive pad 4 (dashed line) can then be deposited to connect the interconnecting lateral conductive strip E12l to the lateral conductive strip E2l. This can consist of a conductive paste deposited using an inkjet printing technique. Thus, during the activation of diodes D1 and D2, the upper electrode layers E1 and E2 form a single interdigitated upper electrode that can reach a certain potential. Selective activation of diodes D1 and D2 can then be performed to polarize a specific lower electrode layer 21.

[0080] Furthermore, it should be noted that the upper electrode layer E3 can also be connected to the upper electrode layers E1 and E2, thereby forming a single interdigitated common upper electrode. Different conventional techniques (depositing conductive pads to provide interconnection, laser irradiation, etc.) can be used.

[0081] Figure 2B This is a top view of several identical optoelectronic devices 1 according to an alternative embodiment, showing the manner in which the transverse strips are connected to the peripheral polarization strips.

[0082] In this example, the method involves jointly and simultaneously manufacturing the same optoelectronic device 1 on the same substrate 5 (or wafer) with a larger size (e.g., a diameter of 200 or 300 mm).

[0083] Here, during the generation of the color conversion section P1, the upper electrode layer E1 is fully interconnected and in Figure 1D The same transverse conductive strip E1l is polarized together during the process. Therefore, the same transverse conductive strip E1l is along multiple adjacent optoelectronic devices (see...). Figure 2A The temporary electrode 2 extends and contacts the main lateral conductive strip E1lp located on the edge of the substrate. Note that the temporary electrode 2 preferably extends in a manner that continuously covers all diode arrays.

[0084] Similarly, during the generation of the color conversion section P2, the upper electrode layer E2 is fully interconnected and in Figure 1J The same transverse conductive strip E2l is polarized together during the process. For this purpose, the same transverse conductive strip E2l runs along multiple adjacent optoelectronic devices (see...). Figure 2A It extends and contacts the main transverse conductive strip E2lp located on the edge of the substrate.

[0085] At the end of the manufacturing process, the substrate 5 is cut to form a single optoelectronic device 1.

[0086] Furthermore, this manufacturing method enables the generation of color conversion portions P1 and P2 on the substrate 5 by localized and self-aligned deposition of photoluminescent particles according to the desired diodes.

[0087] Figures 3A to 3D Different steps of a method for manufacturing an optoelectronic device 1 according to another embodiment are shown. Here, optoelectronic device 1 and... Figure 1A The main difference between this and the optoelectronic device described below is that diodes D1, D2, and D3 are organic light-emitting diodes, specifically top-emitting diodes. Therefore, the optoelectronic device can be an OLED screen with high resolution (small pixels) and high brightness (associated with significant quantum efficiency). In this example, a blue OLED emitting layer is deposited on all pixels, and coloring is achieved by selectively depositing converters on the green and red pixels, respectively.

[0088] refer to Figure 3A A control substrate 10 (CMOS) is provided with connection pads 11 flush with the upper end face. These connection pads 11 form the lower electrode layer, while other connection pads 12.1, 12.2 (not shown), and 12.3 are designed to provide polarization for the upper electrode layers E1, E2, and E3.

[0089] refer to Figure 3B Then, a stack 30 of organic semiconductor layers is formed, which extends along the control substrate 10 and covers the lower electrode layer 11. Typically, the stack consists of a stack of HTL layers, light-emitting layers, and ETL layers. Then, upper electrode layers E1, E2, and E3 are formed on the organic semiconductor stack 30. Upper electrode layer E1 is connected to the same connection pad 12.1, and upper electrode layer E2 is similarly connected to connection pad 12.2 (not shown).

[0090] refer to Figure 3C Then, a thin-film encapsulation (TFE) layer 26 is deposited, which covers the organic semiconductor stack 30 and the top electrode layers E1, E2, and E3. This TFE layer 26 is made of a dielectric material and is intended to form an electret dielectric layer. It can be noted that, depending on the variation, the TFE layer can be used as an electret. Typically, the TFE layer is placed first, followed by the electret on top.

[0091] refer to Figure 3D Then, color conversion pads P1 and P2 are generated, located facing the upper electrode layers E1 and E2, respectively. These color conversion pads are referenced above. Figure 1A And as described below. Thus, an optoelectronic device with organic diodes is obtained, which has high resolution, wherein the color conversion pads P1 and P2 are fabricated locally and self-aligned by means of the upper electrode layers E1 and E2.

[0092] Some specific embodiments have been described above. Various modifications and variations will be apparent to those skilled in the art.

Claims

1. A method for manufacturing an optoelectronic device (1) comprising: - an array of diodes (Dl, D2, D3) having mutually opposite back and front faces, the front face being intended to receive or transmit optical radiation; - an array of color conversion portions (Pl, P2) disposed on the front face, the array of color conversion portions comprising a first color conversion portion (Pl) disposed facing a diode of the array of diodes called first diode (Dl); the method comprising the steps of: - providing an optoelectronic structure comprising: • the array of diodes (Dl, D2, D3); • at least one lower electrode layer (21) disposed at the back face and configured to polarize the diodes; and • an upper electrode layer (El, E2, E3) disposed at the front face and configured to polarize the diodes, the upper electrode layer comprising a first upper electrode layer (El) configured to polarize the first diode (Dl) and distinct from the other upper electrode layers (E2, E3); - depositing a dielectric layer (26) covering the array of diodes (Dl, D2, D3) and the upper electrode layer (El, E2, E3), the surface potential of the upper face of the dielectric layer opposite the front face being substantially zero; - applying a potential difference between, on the one hand, a temporary electrode (2) disposed on the dielectric layer (26) and, on the other hand, the first upper electrode layer (El), thereby forming in the dielectric layer (26) a first pattern (Ml) having a non-zero surface potential, the first pattern being located in a position facing only the first upper electrode layer (El); then removing the temporary electrode (2); - generating the first color conversion portion (Pl) by contacting the dielectric layer (26) with a first colloidal solution (Sl) containing first photoluminescent particles (pl) which are deposited on the dielectric layer (26) facing only the first pattern (Ml) having a non-zero surface potential, thereby forming the first color conversion portion (Pl).

2. The method according to claim 1, - the array of color conversion portions comprising a second color conversion portion (P2) distinct from the first color conversion portion (Pl) and disposed facing a diode of the array of diodes called second diode (D2); - the optoelectronic structure comprising a second upper electrode layer (E2) of the upper electrode layer (El, E2, E3) configured to polarize the second diode (D2); - after generating the first color conversion portion (Pl), the method comprising the steps of: - depositing a dielectric layer (26) covering the array of diodes (Dl, D2, D3) and the upper electrode layer (El, E2, E3), the surface potential of the upper face of the dielectric layer opposite the front face being substantially zero; - applying a potential difference between, on the one hand, a temporary electrode (2) disposed on the dielectric layer (26) and, on the other hand, the first upper electrode layer (El), thereby forming in the dielectric layer (26) a first pattern (Ml) having a non-zero surface potential, the first pattern being located in a position facing only the first upper electrode layer (El); then removing the temporary electrode (2); - generating the first color conversion portion (Pl) by contacting the dielectric layer (26) with a first colloidal solution (Sl) containing first photoluminescent particles (pl) which are deposited on the dielectric layer (26) facing only the first pattern (Ml) having a non-zero surface potential, thereby forming the first color conversion portion (Pl). applying a potential difference between a temporary electrode (2) arranged on said dielectric layer (26) on the one hand and said second upper electrode layer (E2) on the other hand, thereby forming in said dielectric layer (26) a second pattern (M2) having a non-zero surface potential, said second pattern being located in a position facing only said second upper electrode layer (E2); then removing said temporary electrode (2); generating said second color conversion portion (P2) by contacting said dielectric layer (26) with a second colloidal solution (S2) comprising second photoluminescent particles (p2) different from said first photoluminescent particles (pl), said second photoluminescent particles being deposited on said dielectric layer (26) facing only said second pattern (M2) having a non-zero surface potential, thereby forming said second color conversion portion (P2).

3. The method of claim 1, wherein, Each upper electrode layer (El, E2, E3) completely covers a diode, said each upper electrode layer being located on top of said covered diode.

4. The method of claim 1, wherein, During the step of applying a potential difference between said temporary electrode (2) and said upper electrode layers (El, E2), said lower electrode layers (21) are non-polarized.

5. The method of claim 1, wherein, During the step of applying a potential difference between said temporary electrode (2) and said upper electrode layers (El, E2), said then polarized upper electrode layers are interconnected.

6. The method of claim 1, wherein, Said diodes are in contact with lower electrode layers (21) which are different from each other to enable selective activation of each diode.

7. The method according to claim 2, comprising the step of interconnecting said first upper electrode layer (El) and said second upper electrode layer (E2) after generating said first color conversion portion (Pl) and said second color conversion portion (P2).

8. The method according to claim 2, comprising the step of interconnecting all said upper electrode layers (El, E2, E3) after generating said first color conversion portion (Pl) and said second color conversion portion (P2).

9. The method of claim 1, wherein, Said diodes have mutually identical light radiation emission or absorption properties.

10. The method of claim 1, wherein, Said diodes are generated on the basis of organic semiconductor compounds or inorganic semiconductor compounds.

11. A method for the co-fabrication and simultaneous production of a plurality of optoelectronic devices (1) from the same substrate (5), comprising: The steps of the method according to claim 1 are implemented simultaneously for each optoelectronic device (1).

12. The method of claim 11, wherein, During the step of applying a potential difference between said temporary electrode (2) and said upper electrode layers (El, E2), said temporary electrode (2) continuously covers all diode arrays, and wherein said then polarized upper electrode layers are interconnected.

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