Method for producing an optoelectronic component

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 the array of diodes (D1, D2, D3) and an upper electrode layer (E1, E2, E3); depositing a dielectric layer (26) having a surface potential of substantially zero; 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); a first color conversion portion (P1) is generated by bringing a dielectric layer (26) into contact with a colloidal solution (S1) containing first photoluminescent particles (p1).

Description

Technical Field

[0001] The field of the invention is a method for manufacturing an optoelectronic device comprising an array of electroluminescent radiation emitting or detecting diodes associated with a color converting portion. The invention has particular application to display screens and image projectors. Background Art

[0002] Existing optoelectronic devices include an array of identical electroluminescent diodes at least partially covered by a color conversion portion. Such optoelectronic devices can form a display screen or image projection system including an array of light-emitting pixels of different colors.

[0003] In such optoelectronic devices, each light emitting pixel comprises one or more light emitting diodes associated with a color conversion portion. In order to obtain light emitting pixels adapted to emit light radiation of different colors (e.g., blue, green or red), the light emitting diodes may be adapted to all emit the same light (e.g., blue), and the green and red pixels comprise a light conversion portion adapted to at least partially absorb incident blue light and responsively emit green or red light.

[0004] Therefore, the light emitting diodes are preferably identical to each other and emit light radiation of the same wavelength. These light emitting diodes can be formed based on semiconductor materials containing elements of groups III and IV of the periodic table, such as compounds of groups III-IV, in particular gallium nitride (GaN), indium gallium nitride (InGaN) or aluminum gallium nitride (AlGaN). These light emitting diodes are arranged to form a light emitting diode array having a front face through which the generated light radiation is transmitted.

[0005] The light-converting portion may be formed of a bonded array comprising particles of a photoluminescent material, for example yttrium aluminum garnet (YAG) YAG:Ce activated by cerium ions. The photoluminescent particles may also be in the form of quantum dots, ie semiconductor nanocrystals in which the quantum confinement is essentially three-dimensional.

[0006] The manufacturing method may include depositing and then structuring the photoluminescent layer to form a first light conversion portion suitable for converting blue to red, for example. These steps are performed again to form a second light conversion portion suitable for converting blue to green, for example. However, the disadvantage 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 manufacturing method, which uses an electret layer covering a diode array. The method first includes a step of imparting a charge pattern on the upper end face of a dielectric layer to obtain an electret layer. For this reason, a polarized atomic force microscope (Atomic Force Microscopy, AFM) tip is used to locally inject charges. Then, a step of locally depositing colloidal nanocrystals on the charge pattern is performed. For this reason, the electret layer is contacted with a colloidal solution containing nanocrystals, and the nanocrystals are naturally deposited on the charge pattern under the action of dielectrophoretic force. However, this method has the following disadvantages in particular, that charges must be sequentially injected by moving the AFM tip on the surface of the upper end face to form a charge pattern therein.

[0008] Document WO2021 / 023656 describes a similar method in which the pattern of charges is defined by a stamping technique (i.e., by contacting an electrically 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. An electret layer having a charge pattern on the top face is thereby obtained. The electret layer is then contacted with a colloidal solution, and the existing nanocrystals are then deposited on the charge pattern by dielectrophoresis. However, a specific disadvantage of this method is that the buffer layer needs to be precisely positioned relative to the diode array. However, uncertainty in the positioning of the buffer layer relative to the diode array may become a problem, particularly for diode arrays with a small pixel pitch (e.g., about 5 μm). In fact, this positioning uncertainty or inaccuracy may result in poor positioning of the light conversion portion relative to the diode, resulting in reduced 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 the related art and, more specifically, to provide a method for manufacturing an optoelectronic device in which 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] To this end, the subject of the invention is a method for manufacturing an optoelectronic device, which comprises: a diode array, comprising a rear face and a front face opposite to each other, the front face being used to receive or transmit light radiation; an array of color conversion parts, arranged on the front face, the array of color conversion parts comprising a first color conversion part, which is arranged facing a diode in the diode array, called a first diode.

[0011] The method comprises the following steps:

[0012] -Providing a photovoltaic structure, the photovoltaic structure comprising: a diode array; at least one lower electrode layer, arranged

[0013] The upper electrode layer is disposed at the front end face and is configured to polarize the diode, and the upper electrode layer includes a first upper electrode layer, the first upper electrode layer

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

[0015] -Deposit a dielectric layer covering the diode array and the upper electrode layer, the upper end surface of the dielectric layer opposite to the front end surface

[0016] The surface potential is essentially zero;

[0017] - applying an electric current between the temporary electrode arranged on the dielectric layer on the one hand and the first upper electrode layer on the other hand

[0018] The potential difference is formed in the dielectric layer to form a first pattern with a non-zero surface potential.

[0019] at a position facing only the first upper electrode layer; and then removing the temporary electrode;

[0020] - generating a first color by contacting the dielectric layer with a first colloidal solution comprising first photoluminescent particles;

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

[0022] Certain preferred but non-limiting aspects of the manufacturing method are as follows.

[0023] The array of color conversion portions may include a second color conversion portion that is different from the first color conversion portion and is disposed facing a diode in the diode array referred to as a second diode. In addition, the optoelectronic structure may include a second upper electrode layer in the upper electrode layer that is configured to polarize the second diode. After generating the second color conversion portion, the method may include the following steps:

[0024] - applying an electric current between the temporary electrode arranged on the dielectric layer on the one hand and the second upper electrode layer on the other hand

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

[0026] at a position facing only the second upper electrode layer; and then removing the temporary electrode;

[0027] - generating a second color by contacting the dielectric layer with a second colloidal solution containing second photoluminescent particles

[0028] The second photoluminescent particles are different from the first photoluminescent particles, and the second photoluminescent particles are deposited on the dielectric layer only facing the second pattern having a non-zero surface potential, thereby forming the second color conversion portion.

[0029] Each upper electrode layer may completely cover the diode, and each upper 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 polarized lower electrode layers may then be interconnected.

[0032] The diodes may be in contact with lower electrode layers that 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 step of interconnecting the first upper electrode layer and the second upper electrode layer.

[0034] After generating the color conversion portion, the method may include the step of interconnecting all upper electrode layers.

[0035] The diodes may have mutually identical light radiation emission or absorption characteristics.

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

[0037] The invention also relates to a method for jointly and simultaneously manufacturing a plurality of optoelectronic devices from a same substrate, comprising: simultaneously carrying out the steps of the method according to any of the preceding features for each optoelectronic device.

[0038] Within the scope of the common manufacturing method, the temporary electrode can continuously cover all diode arrays during the step of applying a potential difference between the temporary electrode and the upper electrode layer. Furthermore, the polarized upper electrode layers can then be interconnected. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Other aspects, objects, advantages and features of the invention will become more apparent from a reading of the following detailed description of a preferred embodiment, 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 an electret dielectric layer is locally polarized by an upper electrode layer providing the electrical polarization of the diode during activation of the diode;

[0041] Figure 2A is a partial top view schematic diagram of an optoelectronic device according to another embodiment, wherein the upper electrode layers of the D1 type diode are connected to each other over the range of the optoelectronic device, similar to the upper electrode layers of the D2 type diode;

[0042] Figure 2B is a partial top view schematic diagram of a plurality of optoelectronic devices according to another embodiment, the plurality of optoelectronic devices being manufactured together from a same substrate (wafer), wherein upper electrode layers of diodes of first-type light-emitting pixels are connected to each other over the range of the substrate, similar to upper electrode layers of diodes of second-type light-emitting pixels;

[0043] Figures 3A to 3D Different steps of a method for producing an optoelectronic component according to a further exemplary embodiment are shown, wherein the diode is an organic light emitting diode. DETAILED DESCRIPTION

[0044] In the drawings and the rest of the specification, the same reference numerals represent the same or similar elements. In addition, in order to improve the clarity of the drawings, various elements are not shown to scale. In addition, different embodiments and variations are not mutually exclusive, but can be combined together. Unless otherwise specified, the terms "substantially", "approximately", "roughly" mean within a range of 10%, preferably within a range of 5%. In addition, unless otherwise specified, the term "between..." and its equivalents mean including boundary values.

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

[0046] The generation of the color conversion portion is obtained by locally depositing photoluminescent particles on the electret dielectric layer, wherein the pattern of non-zero surface potentials is predefined. As described in detail below, the formation of these surface potentials is carried out in particular with the aid of an upper electrode layer, which also provides the electrical polarization of the diode during the activation of the diode. As described in detail below, these upper electrode layers can be common for each type of color pixel and different for different types of color pixels. On the other hand, once the color conversion portion is generated, the upper electrode layer can remain common for each type of color pixel, or can be common for all color pixels, or can be different for each pixel. Sharing means that they are connected to each other to apply the same potential.

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

[0048] Thus, during the generation of the color conversion portions, the upper electrode layer is different and distributed per color conversion pixel type. Thus, a pattern of non-zero surface potential is formed, in which the photoluminescent particles are naturally deposited in a localized manner by electrophoresis or dielectrophoresis during the formation of the color conversion portions. Furthermore, the photoconversion portions are naturally located facing (i.e. "perpendicular") to the surface potential patterns and not outside these predetermined patterns. The method then makes it possible to precisely define the surface potential pattern on the upper end face of the electret dielectric layer, even if the diode array is large in size (in particular when it is produced with 200 mm wafer technology) and / or the pixel pitch of the diode array is small (e.g., about 5 μm).

[0049] Thus, for example, in the case of a red, green, blue pixel (RGB) array, where the diodes are identical and all emit the same blue light, during the generation of the red conversion portion, 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 manufacture of the green conversion portion, 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 of particles made of at least one photoluminescent material, and preferably of nanoparticles having a maximum dimension between 0.2 nm and 1000 nm, for example between 0.2 nm and 100 nm and for example 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, for example, spherical, angular, flat, elongated, etc.

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

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

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

[0054] Purely by way of illustration, the diodes may be of the emissive type and have an emission spectrum in the visible or infrared (e.g. NIR or SWIR) or even ultraviolet (200 nm to 400 nm) range. In the case of an array of light emitting diodes, the incident optical radiation is the radiation emitted by the diodes, while in the case of a photodiode, the incident optical radiation consists of optical radiation coming from the external environment and aimed at the photodiode. In the latter case, the diodes are tuned to absorb all incident optical radiation of different lengths 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 shown. In this example, the optoelectronic device 1 comprises an array of red, green, blue (RGB) type light-emitting pixels. Each pixel is formed by at least one light-emitting diode (here one diode per pixel). Alternatively, the optoelectronic device 1 may comprise an array of other types of light-emitting pixels, for example, an array of RGB-IR type (IR means infrared) light-emitting pixels. Furthermore, optionally, the diode may be a photodiode.

[0056] Here and in the following description, an orthogonal three-dimensional direct reference system XYZ is defined, wherein the X-axis and the Y-axis form a main plane in which the control substrate 10 extends, and wherein the Z-axis is oriented along the thickness of the diode array in the direction of the front face. The terms "lower" and "upper" are defined relative to increasing positioning along the direction +Z.

[0057] refer to Figure 1A , an array of light emitting diodes is provided. In this example, the diodes are divided into three types marked as D1, D2, and D3 according to the type of light emitting pixel to which they belong, for example, here, blue pixels are for diodes D1, red pixels are for diodes D2, and green pixels are for diodes D3. Here, the diodes are located on a control substrate 10, and here they are electrically polarized by one or more lower electrode layers 21 and upper electrode layers E1, E2, and E3. Other configurations may also be used, in particular 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, the rear end face being assembled and connected to the control substrate 10, and the front end face being used to receive or transmit light radiation. In the example where the diode is emitting, the front end face transmits the light radiation emitted by the diode.

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

[0059] The diodes D1, D2, D3 are here inorganic light-emitting diodes. They can be produced by conventional methods, for example by epitaxy of semiconductor layers from a growth substrate and then transferred to the control substrate 10. Each diode D1, D2, D3 can be formed by a stack of: a lower semiconductor portion 22 (towards the control substrate 10), doped with a first type of conductivity (e.g., p-type), in electrical contact with the lower electrode layer 21; an active zone 23 that emits the light radiation of the light-emitting diode; and an upper semiconductor portion 24, doped with a second type of conductivity (e.g., n-type), in electrical contact with the upper electrode layer E1, E2 or E3. The diodes D1, D2, D3 can be generated from the same semiconductor compound, for example based on III-V compounds such as GaN, InGaN, AlGaN.

[0060] Preferably, the diodes D1, D2, D3 are identical in structure so that the light radiation emitted from one diode is identical in wavelength to another diode. In this example, the diodes D1, D2, D3 are adapted to emit light radiation in the blue range, i.e. their emission spectrum has an intensity peak at a wavelength between about 440 nm and 490 nm.

[0061] Figure 1B yes Figure 1A . This is obviously an example, as there may be other configurations. Here, each RGB pixel includes three diodes D1, D2, and D3. Here, the upper electrode layer E1 for polarizing the diode D1 extends along a plurality of adjacent diodes D1. The same applies to the upper electrode layer E2 intended to polarize the diode D2 and the upper conductor intended to polarize the diode D3. Preferably, the upper electrode layer E1 is interconnected by transverse conductive strips E11. The upper electrode layer E2 is also interconnected by transverse conductive strips E21. The upper electrode layer is connected to the control substrate via a connecting pad 3 (pad 31 for electrode layer E1 and pad 32 for electrode layer E2), for example, by a conductive through hole extending through the dielectric filling material 25 surrounding the diodes D1, D2, and D3.

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

[0063] The lower electrode layer and the upper electrode layer are made of conductive materials. The lower electrode layer 21 can be made of at least one metal material selected from the following: Ti, Ni, Pt, Sn, Au, Ag, Al, Pd, W, Pb, Cu, AuSn, TiSn or alloys of these elements. They can be preferably reflective for the light radiation emitted by the diode, and can therefore be made based on Ag. In addition, the material of the upper electrode layers E1, E2, E3 is 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 metal material (e.g., Ag).

[0064] refer to Figure 1C, then a dielectric layer 26 for forming an electret layer is generated. The dielectric layer 26 covers the diode array and therefore covers the upper electrode layers E1, E2 and E3. The surface potential of the dielectric layer is initially substantially zero, so that there is no unwanted non-zero surface potential pattern. The dielectric layer 26 is made of a dielectric material, which is, for example, an inorganic material, such as silicon oxide, nitride or oxynitride, such as SiO2, Si3N4, Al2O3 (especially in the case of OLED), etc. The thickness of the dielectric layer can be on the order of several hundred nanometers, for example, about 400nm.

[0065] refer to Figure 1D , a surface potential pattern M1 is generated by local electrostatic polarization of the dielectric layer 26, and then an electret dielectric layer is formed. To this end, 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 the one hand and only the upper electrode layer E1 on the other hand. The potential difference can be on the order of tens of volts or hundreds of volts, for example, between 10V and 200V. In this step, only the upper electrode layer E1 is activated, but not the other upper electrode layers E2 and E3. A non-zero surface potential pattern M1 is formed locally at the upper end face of the electret dielectric layer 26, facing only the diode D1, but not the 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 the 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 position facing the upper electrode layer E1. In other words, the surface potential of the electret dielectric layer 26 is substantially zero at any other place except the position facing the upper electrode layer E1. Note that in this example, the surface potential pattern M1 may not extend toward the transverse conductive strip E11 for connecting the upper electrode layer E1.

[0067] refer to Figure 1G, the first color conversion portion P1 is generated by locally depositing the first photoluminescent particles p1 on the electret dielectric layer 26 only facing the surface potential pattern M1. To this end, a process similar to that described in documents WO2014 / 136023 and WO2021 / 023656 is followed. Thus, a colloidal solution S1 containing the first photoluminescent particles p1 is in contact with the upper end face of the electret dielectric layer 26. The photoluminescent particles p1 are suitable for converting blue light into red light. Thus, the entire stack can be immersed in the colloidal solution S1, or droplets of such a 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 dielectrophoresis. In addition, the photoluminescent particles p1 are deposited substantially facing the first pattern M1 (and therefore facing the diode D1), and are not deposited substantially outside the pattern M1 (i.e., not facing the diodes D2 and D3). The contact time of the colloidal solution S1 on the electret dielectric layer 26 depends in particular on the mass of the photoluminescent particles p1 to be deposited, and therefore on the desired thickness of the color conversion portion P1, and on the value of the surface potential. For example, the thickness of the color conversion portion P1 may be of the order of a few hundred nanometers, for example, equal to about 400 nm. The colloidal solution S1 is then removed, and the electret dielectric layer may be dried.

[0068] Figure 1H and Fig. 1I The structure obtained is shown. The color conversion portions P1 are present only facing the upper electrode layer E1 and therefore facing the diode D1. They do not extend facing the diodes D2 and D3. Thus, a red pixel is obtained in which the relative positioning of the color conversion portion P1 with respect to the diode D1 is optimal. The portion P1 does not extend facing the diodes D2 and D3 and advantageously completely covers the diode D1 in the plane XY. Note that here, the color conversion portions P1 form different pads, whereas the same pads extend facing a plurality of adjacent diodes D1. The color conversion portion P1 can be encapsulated in a thin layer (for example in Al2O3).

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

[0070] refer to Figure 1J, a surface potential pattern M2 is generated by local electrostatic polarization of the electret dielectric layer 26. To this end, a temporary electrode 2 is placed again on top of the electret dielectric layer 26, and preferably the temporary electrode 2 is 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 can obviously be composed of a rigid conductive plate. A potential difference is applied between the temporary electrode 2 on the one hand and only the upper electrode layer E2 on the other hand. The potential difference can be, for example, between 10V and 200V. In this step, only the upper electrode layer E2 is activated, but not the other upper electrode layers E1 and E3. A non-zero surface potential pattern M2 is formed locally at the upper end face of the electret dielectric layer 26, facing only the diode D2, but not facing the diodes D1 and D3. The temporary electrode is then removed.

[0071] Figure 1K The structure obtained is shown, wherein the electret dielectric layer 26 only includes the surface potential pattern M2. In fact, the pattern M1 may have disappeared after a predetermined time, or may have been removed (for example, during cleaning). They may also exist, but are shielded by the relative pad P1. The surface potential pattern M2 only exists facing the upper electrode layer E2. In this example, the surface potential of the electret dielectric layer 26 is substantially zero anywhere except facing the upper electrode layer E2. Note that in this example, the surface potential pattern M2 may not extend toward the lateral conductive strip E21 for connecting the upper electrode layer E2, because the temporary electrode 2 is not arranged on the top of the lateral conductive strip.

[0072] refer to Figure 1L, the color conversion portion P2 is generated by locally depositing first photoluminescent particles p2 on the electret dielectric layer 26 (facing only the surface potential pattern M2). To this end, the steps are as described above, and a colloidal solution S2 containing the photoluminescent particles p2 is brought into contact with the upper end face of the electret dielectric layer 26. The photoluminescent particles p2 differ from the particles p1 in that the photoluminescent particles p2 are suitable for converting blue light into green light. Therefore, the entire stack can be immersed in the colloidal solution S2, or droplets of such a solution can be deposited on 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 particles p2 by electrophoresis or dielectrophoresis. In addition, the photoluminescent particles p2 are deposited substantially facing the pattern M2 (and therefore facing the diode D2), and are 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 in particular on the mass 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 may be of the order of a few hundred nanometers, for example, equal to about 400 nm. The colloidal solution S2 is then removed and the electret dielectric layer 26 may be dried. An encapsulation layer may be deposited.

[0073] Figure 1M The obtained optoelectronic device 1 is shown. The color conversion portion P1 is present at a position facing only the diode D1 and defines a red pixel; the color conversion portion P2 is located at a position facing only the diode D2 and defines a green pixel. Here, the diode D3 is not covered by the color conversion portion, so a blue pixel is formed. An RGB pixel array device is obtained, in which the color conversion portions P1, P2 have been deposited in a local and self-aligned manner toward the required diodes by electrophoresis or dielectrophoresis on the electret dielectric layer 26, in which the local polarization has been obtained using the upper electrode layers E1, E2 for polarizing the diodes. Therefore, during the operation of the optoelectronic device 1, there is no need to specifically generate an upper electrode for generating the light conversion portion, which is different from the upper diode polarization electrode.

[0074] This thus avoids having to use a step of locally injecting charge in an initially charge-free dielectric layer by means of an AFM tip or a conductive buffer layer. Furthermore, the method is also fast and the generation of the photoconverted parts is spatially precise, even in the case of diode arrays made of substrates of larger dimensions (e.g., 200 mm) and / or in which the pixel pitch is very small (e.g., 5 μm).

[0075] Figure 2A is based on Figure 1B 1 shows a top view of a variant of an optoelectronic device 1. The emission surface of the optoelectronic device 1 is delimited by a dashed line.

[0076] Here, each upper electrode layer E1 of different pixels is electrically connected to the same connection pad 31 through a lateral conductive strip E11 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 Figure 1A Similarly, each upper electrode layer E2 is electrically connected to the same connection pad 32 via a transverse conductive strip E21. The connection pad 32 may also be a conductive through hole 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] Thus, during the localized and self-aligned deposition step of the photoluminescent particles p1, the upper electrode layer E1 is all interconnected and simultaneously polarized, while the upper electrode layers E2 and E3 are non-polarized. During the localized and self-aligned deposition step of the 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 manufacture of the optoelectronic device 1, the upper electrode layers E1 and E2 can be interconnected to form a common upper electrode for the diodes D1 and D2. This can be performed by means of a transverse conductive strip E12l, which extends from the transverse conductive strip E1l of the layer E1 in the direction of the transverse conductive strip E2l of the layer E2. Then a conductive pad 4 (dashed line) can be deposited to connect the interconnected transverse conductive strip E12l to the transverse conductive strip E2l. This can be composed of a conductive paste deposited using an inkjet type technology. Therefore, during the activation of the diodes D1 and D2, the upper electrode layers E1 and E2 form a single interdigitated upper electrode, which can reach a certain potential. Then a selective activation of the diodes D1 and D2 can be performed to polarize a specific lower electrode layer 21.

[0080] Furthermore, it should be noted that the top electrode layer E3 may also be connected to the top electrode layers E1 and E2 to form a single interdigitated common top electrode. Different conventional techniques may be used (deposition of conductive pads to provide interconnections, laser irradiation, etc.).

[0081] Figure 2B is a top view of a plurality of 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 collectively and simultaneously manufacturing identical optoelectronic devices 1 on the scale of the same substrate 5 (or wafer) of relatively large size (eg, 200 or 300 mm in diameter).

[0083] Here, during the generation of the color conversion portion P1, the upper electrode layer E1 is all interconnected and Figure 1D Therefore, the same transverse conductive strip E11 is polarized together along multiple adjacent optoelectronic devices (see Figure 2A ) and contacts the main transverse conductive strip E11p located on the edge of the substrate. Note that the temporary electrode 2 preferably extends in a manner to continuously cover all diode arrays.

[0084] Similarly, during the generation of the color conversion portion P2, the upper electrode layer E2 is all interconnected and Figure 1J To this end, the same transverse conductive strip E21 is polarized together along a plurality of adjacent optoelectronic devices (see Figure 2A ) extends and contacts the main lateral conductive strip E21p located on the edge of the substrate.

[0085] At the end of the manufacturing method, the substrate 5 is cut to form the individual optoelectronic devices 1 .

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

[0087] FIG. 3A to FIG. 3D 1 shows different steps of a method for manufacturing an optoelectronic device 1 according to another embodiment. Figure 1A The main difference from the optoelectronic device in the following is that the diodes D1, D2, D3 are organic light-emitting diodes, here top-emitting. 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, there is a blue OLED emission layer deposited on all pixels, and coloring is performed by selectively depositing converters on 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 on the one hand form the lower electrode layer, while other connection pads 12.1, 12.2 (not shown), 12.3 are intended to provide the electrical polarization of the upper electrode layers E1, E2, E3.

[0089] refer to Figure 3B , then a stack 30 of organic semiconductor layers is generated, 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 generated on the organic semiconductor stack 30. The upper electrode layer E1 is connected here to the same connection pad 12.1, and the upper electrode layer E2 is similarly connected to the 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 upper 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, according to a variant, the TFE layer can be used as an electret. In the usual case, there is a TFE layer first and then an electret on top.

[0091] refer to Figure 3D Then, color conversion pads P1 and P2 are generated, which are located facing the upper electrode layers E1 and E2, respectively. These color conversion pads are as described above with reference to Figure 1A Thus, an optoelectronic device with an organic diode is obtained, the resolution of which is high, in which the color conversion pads P1 and P2 are produced in a localized and self-aligned manner by means of the upper electrode layers E1 and E2.

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

Claims

1. A method for manufacturing an optoelectronic device (1), the optoelectronic device comprising: An array of diodes (D1, D2, D3) having a rear face and a front face opposite to each other, the front face being used to receive or transmit optical radiation; an array of color conversion portions (P1, P2) disposed on the front face, the array of color conversion portions including a first color conversion portion (P1) disposed facing a diode called a first diode (D1) in the diode array; The method comprises the following steps: An optoelectronic structure is provided, the optoelectronic structure comprising: The diode (D1, D2, D3) array; at least one lower electrode layer (21) disposed at the rear facet and configured to polarize the diode; and An upper electrode layer (E1, E2, E3) disposed at the front end face and configured to polarize the diode, the upper electrode layer comprising a first upper electrode layer (E1), the first upper electrode layer being configured to polarize the first diode (D1) and being different from the other upper electrode layers (E2, E3); Depositing a dielectric layer (26) to cover the diode (D1, D2, D3) array and the upper electrode layer (E1, E2, E3), wherein the surface potential of the upper end face of the dielectric layer opposite to the front end face is substantially zero; Applying a potential difference between a temporary electrode (2) disposed on the dielectric layer (26) on the one hand and the first upper electrode layer (E1) on the other hand, thereby forming a first pattern (M1) with a non-zero surface potential in the dielectric layer (26), the first pattern being located at a position facing only the first upper electrode layer (E1); and then removing the temporary electrode (2); The first color conversion portion (P1) is generated by contacting the dielectric layer (26) with a first colloidal solution (S1) containing first photoluminescent particles (p1), the first photoluminescent particles (p1) being deposited on the dielectric layer (26) only facing the first pattern (M1) having a non-zero surface potential, thereby forming the first color conversion portion (P1).

2. The manufacturing method according to claim 1, The array of color conversion sections includes a second color conversion section (P2) which is different from the first color conversion section (P1) and is arranged facing a diode in the diode array, referred to as a second diode (D2); The optoelectronic structure comprises a second upper electrode layer (E2) among the upper electrode layers (E1, E2, E3), wherein the second upper electrode layer is configured to polarize the second diode (D2); After generating the second color conversion portion (P2), the method comprises the following steps: Applying a potential difference between a temporary electrode (2) arranged on the dielectric layer (26) on the one hand and the second upper electrode layer (E2) on the other hand, thereby forming a second pattern (M2) with a non-zero surface potential in the dielectric layer (26), the second pattern being located at a position facing only the second upper electrode layer (E2); and then removing the temporary electrode (2); The second color conversion portion (P2) is generated by contacting the dielectric layer (26) with a second colloidal solution (S2) containing second photoluminescent particles (p2), the second photoluminescent particles being different from the first photoluminescent particles (p1), the second photoluminescent particles being deposited on the dielectric layer (26) only facing the second pattern (M2) having a non-zero surface potential, thereby forming the second color conversion portion (P2).

3. The manufacturing method according to claim 1, wherein: Each upper electrode layer (E1, E2, E3) completely covers the diode, and each upper electrode layer is located on top of the diode it covers.

4. The manufacturing method according to claim 1, wherein: During the step of applying a potential difference between the temporary electrode (2) and the upper electrode layer (E1, E2), the lower electrode layer (21) is non-polarized.

5. The manufacturing method according to claim 1, wherein: During the step of applying a potential difference between the temporary electrode (2) and the upper electrode layers (E1, E2), the lower electrode layers are then polarized and interconnected.

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

7. The manufacturing method according to claim 1, comprising the step of interconnecting the first upper electrode layer and the second upper electrode layer (E1, E2, E3) after generating the color conversion portion (P1, P2).

8. The manufacturing method according to claim 1, comprising the step of interconnecting all of the upper electrode layers (E1, E2, E3) after generating the color conversion portion (P1, P2).

9. The manufacturing method according to claim 1, wherein: The diodes have mutually identical light radiation emission or absorption characteristics.

10. The manufacturing method according to claim 1, wherein: The diodes are produced based on organic semiconductor compounds or inorganic semiconductor compounds.

11. A method for collectively and simultaneously manufacturing a plurality of optoelectronic devices (1) from a same substrate (5), comprising: The steps of the method according to claim 1 are carried out simultaneously for each optoelectronic component (1).

12. The co-manufacturing method according to claim 11, wherein: During the step of applying a potential difference between the temporary electrode (2) and the upper electrode layers (E1, E2), the temporary electrode (2) continuously covers all diode arrays and the lower electrode layers therein, which are then polarized, are interconnected.

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