Monolithic rgb micro-led display

Abstract

A method of forming a light emitting diode array comprising a plurality of light emitting pixels, wherein at least one of the light emitting pixels comprises: a light emitting diode configured to emit light of a first dominant peak wavelength; and an organic semiconductor dispersed in a medium, wherein the organic semiconductor is configured to receive input light of the first dominant peak wavelength from the light emitting diode and convert to provide output light of a second dominant peak wavelength.

Description

Technical Field

[0001] This invention relates to a miniature light-emitting diode (LED) array and a method for forming an LED array. In particular, but not exclusively, this invention relates to a multicolor monolithic light-emitting diode array using down-conversion organic semiconductors and a method for forming a multicolor monolithic light-emitting diode array using down-conversion organic semiconductors. Background Technology

[0002] As is well known, light-emitting diode (LED) devices provide efficient light sources for a wide variety of applications. Improvements in LED light generation efficiency and extraction, along with the production of smaller LEDs (with smaller luminous surface areas) and the integration of LED emitters of different wavelengths in arrays, have led to the provision of high-quality color arrays for a variety of applications, especially in display technology.

[0003] To provide high-resolution LED arrays, such as micro-LED arrays, the luminous surface area of ​​the pixels is reduced compared to the luminous surface of conventional LEDs, and the pixel pitch is also reduced. However, when the pixel pitch in such arrays is reduced to very small pitches (e.g., less than 5 μm) to provide arrays with higher resolution, many difficulties arise. For example, quantum dots (QDs) are often used as color conversion layers to achieve full-color red, green, and blue (RGB) displays, where blue LEDs are typically used as the source of input light. This QD is often used to convert blue input light into red and green light using appropriate QDs. However, to achieve full color saturation, such QD layers typically require a thickness on the order of 20 μm to 30 μm. Therefore, at these thicknesses, the smallest pixels that can be produced are limited to widths greater than 20 μm.

[0004] Further difficulties are known to arise when fabricating quantum dots (QDs) for wavelength color conversion in micro-LED arrays. For example, the efficiency and lifetime of the wavelength conversion QDs decrease when forming the material layer including the QDs, for example, using photolithography and inkjet printing. Therefore, there are significant challenges in pursuing high-resolution micro-LED arrays, for which a pixel pitch of less than 10 μm would be beneficial. Summary of the Invention

[0005] To alleviate at least some of the above-mentioned problems, a light-emitting diode array including a plurality of light-emitting pixels is provided, as well as a method for forming a light-emitting diode array including a plurality of light-emitting pixels.

[0006] In one example, a method is provided for forming an array of light-emitting diodes comprising a plurality of light-emitting pixels, wherein at least one of the light-emitting pixels comprises: a light-emitting diode configured to emit light of a first dominant peak wavelength; and an organic semiconductor dispersed in a medium, wherein the organic semiconductor is configured to receive input light of the first dominant peak wavelength from the light-emitting diode and convert it to provide output light of a second dominant peak wavelength.

[0007] Also provided is a light-emitting diode array comprising a plurality of light-emitting pixels, wherein at least one of the light-emitting pixels comprises: a light-emitting diode configured to emit light of a first dominant peak wavelength; and an organic semiconductor dispersed in a medium, wherein the organic semiconductor is configured to receive input light of the first dominant peak wavelength from the light-emitting diode and convert it to provide output light of a second dominant peak wavelength.

[0008] Advantageously, the combination of a light-emitting diode (LED) array with organic semiconductors dispersed in a dielectric means that it is possible to provide light of a desired color that differs from the color of light generated by the LED array. Advantageously, the use of organic semiconductors dispersed in a dielectric means that it is possible to efficiently convert the dominant peak wavelength of light from a first wavelength to a second wavelength using a very thin film (typically on the order of 1 μm to 2 μm). This implies efficient color conversion using a very thin color-converting organic semiconductor film dispersed in a dielectric, with reduced absorption compared to known methods. Furthermore, the efficiency of light absorption and subsequent emission from the organic semiconductor means that an additional blue light blocking filter is unnecessary, which would otherwise be required if a highly efficient blue light emitting LED is used to provide the optical pump source for the color conversion layer and the blue light is not completely absorbed. Therefore, the combination of organic semiconductors and LED arrays provides excellent color saturation performance.

[0009] Preferably, at least one additional light-emitting pixel includes: another light-emitting diode configured to emit light of the first dominant peak wavelength; and another organic semiconductor dispersed in another medium, wherein the other organic semiconductor is configured to receive input light of the first dominant peak wavelength from the other light-emitting diode and convert it to output light of a third dominant peak wavelength.

[0010] Advantageously, the ability to control the absorption and emission properties of organic semiconductors means that it is possible to provide luminescent pixels with different emission wavelengths using an array of light-emitting diodes that utilize light-emitting diodes that emit light of the same wavelength (such as pumping both the green and red conversion layers and producing a blue LED with RGB emission when combined with the blue emission from an LED in the array of light-emitting diodes).

[0011] Preferably, the method includes depositing the medium and / or the other medium on the light-emitting diode array, preferably wherein depositing the medium and / or the other medium includes slit coating or spin coating of the medium and / or the other medium.

[0012] Advantageously, organic semiconductors are tunable to be completely dissolved in different media. This means they are deposited using techniques such as slot coating or spin coating, and are therefore unaffected by photolithography or inkjet printing, which are known to cause degradation of quantum dots dispersed in, for example, photodefinable materials.

[0013] Preferably, the method includes selectively covering one or more light-emitting diodes in the light-emitting diode array with a material before depositing the medium and / or the other medium, thereby enabling selective deposition of the medium and / or the other medium.

[0014] Advantageously, an efficient method for self-alignment of organic semiconductor materials is provided, which enables the formation of light-emitting pixels that emit light of different wavelengths based on input light of the same wavelength provided by an array of light-emitting diodes.

[0015] Preferably, the material is at least one of the following: a temporary material that is removable, allowing the medium and / or the other medium to be further deposited on the selectively covered one or more light-emitting diodes in a separate step after the medium and / or the other medium is deposited on the light-emitting diode array; and an optically transparent material that allows light to be emitted from the selectively covered one or more light-emitting diodes, wherein the one or more light-emitting diodes are configured to emit light having the dominant peak wavelength.

[0016] Advantageously, the use of temporary materials enables successive deposition steps for depositing different media, including organic semiconductors, and thus forming pixels that emit different colors of light associated with the light-emitting diode array.

[0017] Preferably, the medium and / or the other medium comprises at least one of the following: resin, epoxy resin, and polymer.

[0018] Advantageously, organic semiconductors are tunable to be completely dissolved in different types of media, thus enabling a range of processing techniques to be used to form multicolor LED arrays.

[0019] Preferably, the method includes patterning an insulating layer on a light-emitting diode array to define the boundary of the light-emitting surface of at least one light-emitting pixel.

[0020] Advantageously, an insulating layer separates the region associated with the light-emitting surface of the light-emitting diode in which the light-converting organic semiconductor is deposited. Advantageously, the insulating layer prevents the medium comprising the organic semiconductor from diffusing from one light-emitting surface associated with one light-emitting diode device to another light-emitting surface associated with another light-emitting diode device. Thus, a self-aligned method is provided in which organic semiconductors dispersed in a medium are directly and selectively deposited to be mixed with the light-emitting diode devices to form a light-emitting surface that emits light at a down-conversion wavelength relative to the dominant peak wavelength of the light emitted by the light-emitting diode devices in an array of light-emitting diode devices.

[0021] Preferably, the method includes depositing an insulating material layer on the light-emitting diode array and selectively etching the insulating material to provide the patterned insulating layer.

[0022] Advantageously, if the insulating material layer provides a controllable and efficient mechanism to enclose the area associated with the light-emitting surface of the LED device, selective etching is performed so that the color conversion material can selectively self-align within the enclosed area, thereby forming the light-emitting surface of the light-emitting pixel that provides light emission of a controllable wavelength.

[0023] Preferably, the method includes depositing a conformal reflective layer on the patterned insulating layer and etching the conformal reflective layer to provide a light-emitting surface associated with a light-emitting diode of at least one of the plurality of light-emitting pixels. Preferably, the method includes depositing the dielectric and / or the other dielectric on the light-emitting diode array after etching the conformal reflective layer.

[0024] Advantageously, the reflective layer provides optical isolation for the color conversion material provided by the organic semiconductor dispersed in the medium, since the reflective material is formed on an insulating layer that defines the boundaries of the luminescent pixels.

[0025] Preferably, the method includes curing the medium and / or the other medium and planarizing the surface of the light-emitting diode array.

[0026] Advantageously, planarization removes unwanted material, allowing access to previously covered layers while providing a relatively flat and smooth surface for subsequent processing steps.

[0027] Preferably, the method includes forming a passivation layer on the light-emitting diode array to protect the medium and / or the other medium.

[0028] Advantageously, the passivation layer protects multiple light-emitting pixels associated with the array of light-emitting diode devices in a single protection step.

[0029] Preferably, the organic semiconductor and / or the other organic semiconductor comprises a conjugated organic semiconductor having multiple conjugated structures. Preferably, the organic semiconductor and / or the other organic semiconductor is formed of an organic semiconductor material. More preferably, the multiple conjugated structures include a core and an arm. Even more preferably, at least two of the multiple conjugated structures have different functional properties.

[0030] Advantageously, organic semiconductors (such as downconversion organic semiconductors) possess the ability to tune their molecular structure to achieve desired physical properties. Specific values ​​can be achieved for the ionization potential or electron affinity, absorption and emission properties, charge transport properties, phase behavior, solubility, and processability of organic semiconductors. Specifically, for the requirements of monolithic RGB micro-LED displays, the ability to make subtle structural alterations to organic semiconductors allows for complete control over the display's performance.

[0031] Preferably, one functional property is the absorption of the first dominant peak wavelength, and wherein, one functional property is the emission of light absorbed at the second dominant peak wavelength.

[0032] Advantageously, the organic semiconductor absorbs input light with a first dominant peak wavelength from the light-emitting diodes in the light-emitting diode array, and emits light at a determined second dominant peak wavelength, different from the first dominant peak wavelength. Thus, an RGB array (and other multicolor arrays) of light-emitting pixels is realized.

[0033] Preferably, the light-emitting diode array is a high-resolution monolithic micro-LED array. More preferably, the method includes forming a reflective layer between at least two light-emitting diodes in the high-resolution monolithic micro-LED array. More preferably, the pixel pitch of the high-resolution monolithic LED is less than 10 μm, preferably less than 4 μm. Preferably, the emitting surface area of ​​each of the plurality of emitting pixels is less than or equal to 100 μm. 2 Preferably less than 16 μm 2 .

[0034] Advantageously, a high-resolution array is provided through the combination of organic semiconductors and monolithic LED arrays, where the pixel size is reduced compared to known technologies. This combination of reduced pixel size and reduced pixel pitch is achieved without using photolithography or inkjet printing techniques that would otherwise degrade color conversion materials.

[0035] Further aspects of the invention will become apparent from the description. Attached Figure Description

[0036] The detailed description of embodiments of the present invention is given by way of example only, with reference to the accompanying drawings, in which:

[0037] Figure 1A A cross-sectional view of a single LED array is shown;

[0038] Figure 1B It shows Figure 1A A cross-sectional view of a fabricated version of a single-unit LED array;

[0039] Figure 1C It shows Figure 1B A cross-sectional view of a further processed version of a single-unit LED array;

[0040] Figure 1D It shows Figure 1C A cross-sectional view of a further processed version of a single-unit LED array;

[0041] Figure 1E It shows Figure 1D A cross-sectional view of a further processed version of a single-unit LED array;

[0042] Figure 1F It shows Figure 1E A cross-sectional view of a further processed version of a single-unit LED array;

[0043] Figure 2A A cross-sectional view of a multi-color LED array is shown;

[0044] Figure 2B It shows Figure 2A A plan view of a multi-color LED array;

[0045] Figure 3 A cross-sectional view of a multi-color LED array is shown;

[0046] Figure 4A It shows Figure 1D A cross-sectional view of a further processed version of a single-unit LED array;

[0047] Figure 4B It shows Figure 4A A cross-sectional view of a further processed version of a single-unit LED array;

[0048] Figure 4C It shows Figure 4B A cross-sectional view of a further processed version of a single-unit LED array;

[0049] Figure 4D It shows Figure 4C A cross-sectional view of a further processed version of a single-unit LED array;

[0050] Figure 4E It shows Figure 4DA cross-sectional view of a further processed version of a single-unit LED array;

[0051] Figure 4F It shows Figure 4E A cross-sectional view of a further processed version of a single-unit LED array;

[0052] Figure 4G It shows Figure 4F A cross-sectional view of a further processed version of a monolithic LED array; and

[0053] Figure 4H It shows Figure 4G A cross-sectional view of a further processed version of a single-unit LED array. Detailed Implementation

[0054] To address the shortcomings of existing technologies, a light-emitting diode (LED) array comprising multiple emitting pixels and a method for forming such an array are described with reference to Figures 1 to 4. How down-conversion organic semiconductors are dispersed in a dielectric is described, thereby improving the processing of the combination of color-conversion materials with the monolithic LED array. This facilitates the provision of emitting pixels with smaller emitting surfaces and a higher resolution monolithic LED array with a denser arrangement than allowed by conventional techniques. Advantageously, the described method enables the creation of such a high-resolution monolithic LED array with multiple emitting pixels without using lithography or inkjet patterning processes to form the color-conversion regions associated with the LEDs in the LED array, thus avoiding the detrimental effects of lithography and inkjet patterning processes as seen in conventional techniques using quantum dots to form the color-conversion regions.

[0055] refer to Figures 1A to 1F A method for forming a monochromatic single-cell LED array comprising multiple emitting pixels is described, wherein the dominant peak wavelength emitted by the emitting pixels is different from the dominant peak wavelength emitted by the LEDs in the array. Figure 1A A cross-sectional view 100A of a portion of a monolithic LED array is shown. Although the cross-sectional view and the layers as seen in the cross-section are referenced, those skilled in the art will understand that these layers extend laterally in a three-dimensional array to provide planar layers, for example, suitable for functional displays.

[0056] Three LED structures 104 forming part of a monolithic LED array are shown. However, in a further example, the number of LED structures 104 in the array is not limited.

[0057] LED structure 104 is a compound crystal semiconductor LED based on nitride epitaxial growth. In further examples, other LEDs are used, such as other III-V or II-VI based materials. Advantageously, LED structure 104 is monolithically grown, thus providing high-quality materials with excellent uniformity and efficiency without the need to transfer individual LED devices. Advantageously, the monolithic LED array is coupled to a backplane to enable control of individual LED structures 104 within the monolithic array. LED structure 104 is grown as part of the monolithic LED array using metal-organic chemical vapor deposition (MOCVD). In further examples, alternative and / or additional techniques are used to form LED structure 104 as part of the monolithic array, such as molecular beam epitaxy (MBE) and other suitable deposition / growth techniques. In further examples, other additional and / or alternative semiconductor fabrication and processing techniques are used to provide the monolithic array of LED structure 104.

[0058] LED structure 104 is formed on and shown embedded in a region of gallium nitride (GaN) 102. In a further example, additionally or alternatively, LED structure 104 is formed on a different material and positioned above the top surface of the monolithic LED array, resulting in a topological change on the surface of the monolithic LED array. In a further example, the region of GaN 102 is coupled to a complementary metal-oxide-semiconductor (CMOS) backplane, such that each LED structure 104 of the monolithic array is independently addressable, thereby controlling light emission from the array. Electrical connections to the LED structures 104 are not shown, and those skilled in the art will understand that such electrical connections can be implemented in various ways.

[0059] A metal layer 106 is formed around the boundary of the LED structures 104 in the monolithic array, thereby providing optical isolation and preventing optical crosstalk between the LED structures 104. In a further example, alternatively or additionally, the metal layer 106 is not used. In a further example, alternative or additional layers are used between the LED structures 104 in the monolithic array to provide isolation between the LED structures 104, including optical isolation between the LED structures 104.

[0060] Once the array of individual LED structures 104 has been provided, an insulating layer 108 is patterned on the surface of the array, such as... Figure 1BA cross-sectional view 100B is shown. The insulating layer 108 is patterned such that the light-emitting surface of each pixel, defined by the light-emitting surface of the LED structure 104, is exposed. The insulating layer 108 is patterned by forming an insulating material layer on a monolithic array of LED structures 104 and anisotropically etching the insulating material to expose the light-emitting surface associated with each LED structure 104, while leaving a patterned insulating layer 108 disposed around the boundary of each LED, thereby enabling the light-emitting surface of each LED structure 104 to be defined and allowing subsequent material deposition to be confined within the individual selected LED structures 104. The insulating layer 108 is a patterned silicon dioxide layer. As a further example, alternatively or additionally, different insulating materials may be used to form the patterned insulating layer 108.

[0061] Once the insulation layer 108 has been as referenced Figure 1B The conformal reflective layer, formed on the monolithic array of LED structure 104, is deposited onto the surface of the array. Reflective layer 110 is an aluminum layer. In a further example, alternatively or additionally, different reflective layers, such as different metal reflective layers or other reflective material layers, may be used. In a further example, reflective layer 110 is omitted. Once as... Figure 1C The conformal reflective layer 110 was deposited, and the process was moved to... Figure 1D Although the conformal reflective layer 110 is shown in cross-sectional view 100C, those skilled in the art will understand that the conformal layer may extend laterally on the surface of the array of LED structures 104 as needed.

[0062] exist Figure 1D The diagram shows a cross-sectional view 100D of a monolithic array of LED structures 104, in which anisotropic etching has been performed to leave a metallic reflective layer 110 on the sidewalls of the insulating layer 108. This metallic reflective layer is patterned onto the surface of the array rather than the light-emitting surface associated with each individual LED structure 104. Anisotropic etching selectively exposes the light-emitting surface associated with each individual LED structure 104 in the array of LED structures 104. Advantageously, the metallic reflective layer 110 on the sidewalls of the insulating layer 108 provides an optical definition of the light-emitting surface of the light-emitting pixels, thereby providing better contrast between pixels. The process then continues to provide... Figure 1E The structure shown.

[0063] exist Figure 1E The reference is shown in the middle. Figure 1DThe diagram describes a cross-sectional view 100E of an array on which an organic semiconductor substrate has been deposited. It is well known that downconversion organic semiconductors can be tuned to achieve target physical properties. In particular, advantageously, specific values ​​can be achieved for the ionization potential or electron affinity, absorption and emission properties, charge transport properties, phase behavior, solubility, and processability of organic semiconductors. Typically, organic semiconductors are conjugated organic semiconductors comprising multiple conjugated structures. In the example, such conjugated structures include a core and arms. The function of these components of a macromolecule is tuned to provide specific properties.

[0064] For example, macromolecules are discussed in the following literature: Acc. Chem. Res 2019, 52, 1665–1674 and J. Mater. Chem. C, 2016, 4, 11499. Tunable macromolecules include conjugated macromolecules containing multiple conjugated structures. These are typically organic semiconductors. Multiple conjugated structures can be formed to have different functional properties, such as different absorption and / or emission characteristics associated with each different conjugated structure.

[0065] Advantageously, even using thin layers of organic semiconductors, these organic semiconductor macromolecules can efficiently absorb light of one wavelength and convert it into different emitted wavelengths. Figures 1 through 4 below illustrate a clever and advantageous technique for processing such organic semiconductors dispersed in a medium. Advantageously, this method does not rely on photolithography or inkjet patterning processes, which are known to degrade color-converting materials in conventional color-converting materials such as quantum dots. Advantageously, a self-aligned method is described that creates small features suitable for micro-LED arrays without the need for lithography or inkjet patterning processes to form color-converting regions.

[0066] The organic semiconductor material 112 includes a color-converting organic semiconductor dispersed in a medium. Advantageously, the ability to modulate the organic semiconductor makes it easy to control the color gamut of the final display. The organic semiconductor material 112 absorbs light from the LED structure 104 and emits light at different down-conversion wavelengths. The dominant peak wavelength of the light from the LED structure 104 is longer than the dominant peak wavelength of the light emitted from the color-converting organic semiconductor material 112. The light emitted from the LED structure 104 has a dominant peak wavelength of blue (approximately 450 nm). In a further example, the light emitted from the LED structure 104 has different dominant peak wavelengths. The organic semiconductor material 112 is configured to absorb light and emit light having a dominant peak wavelength corresponding to green light (approximately 550 nm). Additionally or alternatively, in a further example, the organic semiconductor material 112 is configured to emit light having a dominant peak wavelength corresponding to red light (approximately 650 nm). Additionally or alternatively, in a further example, the organic semiconductor material 112 includes an organic semiconductor configured to emit light at multiple wavelengths. Advantageously, the ability to modulate organic semiconductors allows for the option of multi-color, multi-emission from a single pixel, thereby contributing to the final display color gamut. Additionally or alternatively, in a further example, the organic semiconductor material 112 includes different organic semiconductors that emit light at different wavelengths in response to the absorption of light from the LED structure 104.

[0067] Organic semiconductor material 112 is deposited on a monolithic array of LED structures 104 using a slot coating deposition technique. In a further example, alternative or additional techniques are used to deposit the organic semiconductor material 112 on the monolithic array of LED structures 104. For example, spin coating is used in a further example. The medium in which the organic semiconductor is dispersed is a resin. In a further example, alternative or additional media, such as epoxy resin materials or polymer materials, are used. The organic semiconductor is dispersed in the medium to form the organic semiconductor material 112 before being deposited on the array surface. The medium including the organic semiconductor is deposited on the LED structures 104 between insulating layers 108.

[0068] Once the organic semiconductor material 112 has been deposited, the surface of the array is planarized. This planarization is performed using an anisotropic etch-back process. Figure 1F As shown in [the image]. Figure 1F In, it is shown Figure 1EThe cross-sectional view 100F of the fabricated micro-LED array shown. Advantageously, a planarization structure is provided, wherein the organic semiconductor material 112 defining the pixel associated with each LED structure 104 is laterally isolated by an insulating layer 108 defining the pixel boundary and a reflective layer 110, such that the pixels are optically isolated from each other.

[0069] The micro-LED array has an LED structure 104 that provides source input light to color conversion regions of different pixels in the array, defined by an organic semiconductor material 112. While an anisotropic etch-back process is used to perform planarization, in a further example, chemical mechanical polishing is additionally or alternatively used to planarize the structure.

[0070] Although the color conversion layer provided by the organic semiconductor material 112 is shown to convert light from the LED structure 104 into light of different wavelengths, those skilled in the art will understand that, in further examples, different pixels have different organic semiconductor materials 112 deposited therein, thereby providing pixels of different colors. An example of this is illustrated with respect to Figure 2, which shows a view 200 of a multicolor monolithic LED array.

[0071] Figure 2A A cross-sectional view 200 of a multicolor single-cell LED array is shown, illustrating three emitting pixels 216a, 216b, and 216c. A complementary metal-oxide-semiconductor (CMOS) backplane 202 is shown, on which an array of microLEDs 204a, 204b, and 204c is provided. The CMOS backplane 202 is configured to work in conjunction with the microLEDs to selectively control light emission from the microLED array. Figure 2A Three microLEDs, 204a, 204b, and 204c, are shown. MicroLEDs 204a, 204b, and 204c are nitride-based epitaxial crystal semiconductor LEDs configured to emit light with a dominant blue peak wavelength (approximately 450 nm). To provide a red-green-blue (RGB) display, a color conversion layer formed on the microLEDs 204a, 204b, and 204c is used to convert the blue light emitted by the microLED structures 204a, 204b, and 204c.

[0072] Figure 2AView 200 shows a first microLED 204a configured to emit light with a blue main peak wavelength (approximately 450 nm), on which a transparent resin 212 is deposited. A passivation protective layer 214 is deposited on the transparent resin 212. The protective layer 214 is transparent to visible light and forms at least a portion of the light-emitting surface associated with the microLED 204a. The microLED 204a, the transparent resin 212, and the protective layer 214 form a first light-emitting pixel 216a.

[0073] Also shown is a second microLED 204b configured to emit light with a dominant blue peak wavelength (approximately 450 nm), on which a color conversion layer 208 is formed. This color conversion layer is configured to convert the light 204b from the microLED structure, such that the input light with a dominant blue peak wavelength is converted to a dominant red wavelength. On the color conversion layer 208 is a passivation protective layer 214. The protective layer 214 is transparent to visible light and forms at least a portion of the light-emitting surface associated with the microLED 204b. The microLED 204b, the color conversion layer 208, and the protective layer 214 form a second light-emitting pixel 216b.

[0074] A third microLED 204c configured to emit light with a dominant blue peak wavelength (approximately 450 nm) is also shown. On the third blue microLED 204c, a color conversion layer 210, different from the color conversion layer 208 associated with the second microLED 204b, is provided. The color conversion layer 210 is configured to receive input light from the third microLED 204c and convert it from light with a dominant blue peak wavelength to light with a dominant green peak wavelength. On the color conversion layer 210 is a passivation protection layer 214. The protection layer 214 is transparent to visible light and forms at least a portion of the light-emitting surface associated with the microLED 204b. The microLED 204a, the color conversion layer 210, and the protection layer 214 form a third light-emitting pixel 216c.

[0075] Blue emitting microLEDs 204a, 204b, and 204c are epitaxially grown as a monolithic array of blue emitting microLEDs. Filler 206 is provided between each emitting pixel 216a, 216b, and 216c formed by a combination of microLEDs with or without a color conversion layer. Filler 206 separates the emitting pixels. In a further example, additional or alternative structures and / or layers are used to separate the microLEDs 204a, 204b, and 204c and / or the emitting pixels 216a, 216b, and 216c. Although the microLEDs 204a, 204b, and 204c are configured to emit blue light at the same wavelength, in a further example, alternative or additional LEDs may be provided in the array, wherein these alternative or additional LEDs emit light at different predetermined dominant peak wavelengths. For example, blue and green LEDs may form part of the monolithic LED array, and red conversion material may be selectively deposited on some LEDs, such as some blue LEDs, thereby providing an RGB display.

[0076] Figure 2B It shows about Figure 2A A plan view 200′ of the described light-emitting pixel array. Each LED pixel 216 has a light-emitting surface (these are in... Figure 2B The image shows a square surface (in a further example, the luminescent surface has different shapes and different configurations). Pixel 216 corresponds to having about Figure 2A The described color conversion layers 208, 210, or resin 212 are used with any combination of micro LEDs 204a, 204b, and 204c, and... Figure 2B The text shows information about... Figure 2A The blue, green, and red luminescent pixels 216a, 216b, 216c, and other luminescent pixels 216. Although Figure 2A and Figure 2B The light-emitting pixels 216a, 216b, 216c are shown in a specific arrangement, but in a further example, the light-emitting pixel array includes any suitable arrangement and any appropriate number of light-emitting pixels having any suitable light-emitting surface associated with each light-emitting pixel.

[0077] The luminescent pixel 216 has a luminescent surface corresponding to the planar view area of ​​the pixel 216. Although the pixel is shown as a square in the planar view, in further examples, alternatively or additionally, the shape of the pixel planar view may be different. For example, the pixel 216 may have a hexagonal luminescent surface.

[0078] Figure 3 Another cross-sectional view 300 shows an implementation of organic semiconductors dispersed in a medium to provide color conversion films with different pixels without the need for offset or inkjet printing techniques. It also shows... Figure 2A The common components are shown. Additionally, another micro-LED 204d is shown. This layer has a color conversion layer 210 that is thinner than the color conversion layer associated with micro-LED 204c, and a transparent resin 212. This allows white light to be generated at pixel 216d as part of a red-green-blue-white array. This enables improved emission, even under low-light conditions.

[0079] Although Figure 3 The diagram shows that the associated color conversion layer 210 of LED 204c is thicker than the color conversion layer 210 associated with LED 204d. However, in a further example, alternatively or additionally, different thicknesses, sizes, shapes, and combinations of color conversion layers forming the surfaces of the light-emitting pixels can be implemented at different pixels to provide light suitable for their respective applications.

[0080] Figure 4 illustrates a method for forming a multicolor, high-resolution microLED array with luminescent pixels. This method enables the efficient formation of luminescent pixel arrays that emit different dominant peak wavelengths at a smaller scale than that achievable using quantum dot materials, and processes the color conversion materials in a manner that does not adversely affect their ability to convert light from an input color of one LED into different output colors.

[0081] Figure 4A It is shown in relation to the reference Figure 1D A fabricated monomer array 400A of LED structure 104 is provided, formed in the same manner as the provided structure. However, instead of depositing organic semiconductor material onto the fabricated monomer LED 104 array, an optically transparent resin 402 is formed to cover the LED structures 104 in the LED array that are not associated with the color-converting organic semiconductor material to be deposited. This is in Figure 4B The processed array 400B is shown. The optically transparent resin 402 can be formed using a photoconceptual method because it does not contain organic semiconductors (which would otherwise be affected by the lithographic printing techniques involved in the photoconceptual method).

[0082] For reference Figure 4B Once the selected LED has been covered by the optically transparent resin 402, the process moves to... Figure 4C .exist Figure 4C The image shows a fabricated array 400C, in which organic semiconductor material 404 has been deposited on a monolithic array of fabricated LED structures 104. The organic semiconductor material 404 is a medium comprising organic semiconductors, configured to absorb light from the LED structure 104 and downconvert it, such that it emits light with a shorter wavelength than the input light absorbed from the LED structure 104, as shown in the reference image. Figures 1A to 1FThe organic semiconductor material 404 is configured to absorb blue light and emit green light. Advantageously, the efficiency of the organic semiconductor layer means that a blue light blocking filter is not required on the organic semiconductor layer. The organic semiconductor material 404 comprises an organic semiconductor mixed with a dielectric material before deposition using a suitable processing technique. The dielectric material is a resin. In a further example, the dielectric material is additionally or alternatively an epoxy resin or a polymer. Once the organic semiconductor material 404 has been deposited, the structure is planarized using an anisotropic etching process. This is done in... Figure 4D As shown in the image.

[0083] exist Figure 4D The diagram illustrates a planarized structure 400D in which the organic semiconductor material 404 has been removed to expose the optically transparent resin 402, which is formed to selectively cover some of the LED structures 104. While an anisotropic etching-back process is used to perform planarization, in a further example, a chemical mechanical polishing process may be used to planarize structure 400D additionally or alternatively. Once structure 400D has been planarized, the optically transparent resin 402 is selectively removed from the LED structures 104 that are associated with different color-conversion organic semiconductors.

[0084] Figure 4E Structure 400E is shown, which is Figure 4D The structure 400D has been constructed and the optically transparent resin 402 has been removed from one of the covered LED structures 104. Once the optically transparent resin 402 has been selectively removed, another dielectric, including another organic semiconductor, is deposited on the array.

[0085] Figure 4F Structure 400F is shown, which is Figure 4E The structure 400E has an additional organic semiconductor material 406 deposited on it. The organic semiconductor material 406 is formed from a medium in which the organic semiconductor is dispersed. The organic semiconductor material 404 is a medium comprising the organic semiconductor, configured to absorb light from the LED structure 104 and downconvert it, thereby emitting light with a shorter wavelength than the input light absorbed from the LED structure 104. The organic semiconductor is configured to absorb blue light and emit red light. Advantageously, the efficiency of the organic semiconductor layer means that a blue blocking filter is not required on the organic semiconductor layer. The organic semiconductor material 404 comprises an organic semiconductor mixed with a medium prior to deposition. The medium is a resin. In a further example, the medium is additionally or alternatively an epoxy resin or a polymer. Once the organic semiconductor material 406 has been deposited, the structure is planarized using an anisotropic etching process. This is done in… Figure 4G As shown in the image.

[0086] exist Figure 4GThe diagram shows a planarized structure 400G in which the organic semiconductor material 406 has been removed to expose the optically transparent resin formed to selectively cover some LEDs, as well as the organic semiconductor material 404 associated with some LED structures 104. While anisotropic etching-back processes are used to perform planarization, in a further example, a chemical mechanical polishing process may be used to planarize the structure, additionally or alternatively. Once the structure is planarized, Figure 4G The 400G structure is covered by a passivation layer 408. This is in Figure 4H The structure 400H is shown. The passivation layer 408 is formed using atomic layer deposition (ALD) technology. In a further example, the passivation layer 408 is formed using other suitable techniques.

[0087] The resulting structure, as described above, is a monolithic array of LED structures 104 configured to independently emit light with a dominant peak wavelength. The light emitted by the LED structures 104 is absorbed at corresponding organic semiconductor materials 404, 406, or passes through the optically transparent resin 402, thereby emitting three different colors of light. In a further example, alternatively or additionally, the light-emitting pixels are configured to emit light with another dominant peak wavelength. In an even further example, multiple layers of different organic semiconductor materials are associated with each LED structure 104, thereby emitting light with multiple wavelengths. In an even further example, organic semiconductor materials comprising different organic semiconductors with different functional properties are used.

[0088] Although a cross-sectional view of three light-emitting pixels and their associated light-emitting diodes is depicted with reference to Figure 4, those skilled in the art will understand that the methods described herein can be used to generate any number of such arrays of light-emitting pixels, thereby providing a high-resolution monolithic light-emitting pixel array based on the association of a medium containing organic semiconductors with a high-resolution monolithic light-emitting diode array.

[0089] Advantageously, a self-aligned process flow is provided for providing high-resolution micro LED pixel arrays. This process avoids the need for lithography or inkjet patterning processes during the deposition of organic semiconductor materials, thus avoiding any associated detrimental effects, while also enabling the provision of small features.

[0090] Advantageously, conjugated organic semiconductors can achieve full color saturation within very thin films (typically on the order of 1 μm–2 μm) without the need for additional blue-blocking filters. Quantum dot films require thicknesses exceeding 20 μm to achieve similar color saturation performance. Advantageously, full color saturation within the thin film allows organic semiconductors to define pixels with smaller spacing than conventional quantum dot films. The methods described herein provide luminescent pixel arrays based on high-resolution microLEDs with luminescent surface areas less than or equal to 100 μm.2 And preferably less than or equal to 16 μm 2 Furthermore, the methods described herein provide light-emitting pixel arrays based on high-resolution micro-LEDs, wherein the pixel pitch of the high-resolution individual LEDs is less than 10 μm, preferably less than 4 μm. While the methods and arrays described herein are implemented with reference to micro-LEDs, those skilled in the art will understand that these examples are also applicable to LEDs of different sizes and LED arrays of different sizes.

[0091] Advantageously, the ability to tune organic semiconductors allows for their complete dissolution within light-confined materials, thus enabling the use of standard semiconductor processing techniques. Economical batch processing can be achieved using existing technologies. Quantum dots tend to suffer increased degradation in light-confined media, a problem not present in the described method. Advantageously, the use of a thin color conversion layer results in significantly higher efficiency than conventional quantum dots due to less reabsorption, and advantageously, the ability to tune the absorption and emission spectra of organic semiconductors leads to significantly higher efficiency than conventional color conversion techniques.

Claims

1. A method for forming a high-resolution, single-unit micro-light-emitting diode array comprising multiple light-emitting pixels, wherein, The array comprises multiple light-emitting pixels with a pixel pitch of less than 4 μm, and the method includes: An insulating layer is patterned on the light-emitting diode array to define the boundary of the light-emitting surface of the first light-emitting pixel associated with the first light-emitting diode and the boundary of the light-emitting surface of the second light-emitting pixel associated with the second light-emitting diode. A conformal reflective layer is deposited on the patterned insulating layer and the conformal reflective layer is etched to expose the light-emitting surface of the first light-emitting pixel associated with the first light-emitting diode and the light-emitting surface of the second light-emitting pixel associated with the second light-emitting diode. The second light-emitting diode is selectively covered with a material formed within the light-emitting surface boundary of the second light-emitting pixel associated with the second light-emitting diode; Subsequently, a medium in which organic semiconductors are dispersed is deposited within the light-emitting surface boundary of the first light-emitting pixel associated with the first light-emitting diode, wherein the first light-emitting diode is configured to emit light of a first dominant peak wavelength, and wherein the organic semiconductor is configured to receive and convert the input light of the first dominant peak wavelength from the first light-emitting diode to provide output light of a second dominant peak wavelength. The planarized deposition of the dielectric material in which organic semiconductors are dispersed; and A passivation layer is formed on the light-emitting diode array to protect the dielectric.

2. The method according to claim 1, wherein, At least one additional light-emitting pixel includes: Another light-emitting diode configured to emit light at the first main peak wavelength; and Another organic semiconductor dispersed in another medium, wherein the other organic semiconductor is configured to receive and convert input light of the first main peak wavelength from the other light-emitting diode to output light of the third main peak wavelength.

3. The method of claim 2, wherein depositing the medium and / or the other medium comprises slot coating or spin coating of the medium and / or the other medium.

4. The method of claim 1, wherein depositing the medium comprises slot coating or spin coating the medium.

5. The method of claim 3, further comprising selectively covering one or more light-emitting diodes in the light-emitting diode array with a material prior to depositing the other medium, thereby enabling selective deposition of the other medium.

6. The method according to claim 5, wherein, The material is at least one of the following: Temporary material, which is removable, allows the medium and / or the other medium to be further deposited on the selectively covered one or more light-emitting diodes in separate steps after the medium and / or the other medium has been deposited on the light-emitting diode array; as well as An optically transparent material that enables light to be emitted from one or more selectively covered light-emitting diodes, wherein the one or more light-emitting diodes are configured to emit light having the dominant peak wavelength.

7. The method according to any one of claims 1 to 6, wherein, The medium and / or another medium includes at least one of the following: resin, epoxy resin, and polymer.

8. The method according to any one of claims 1 to 6, comprising depositing an insulating material layer on the light-emitting diode array and selectively etching the insulating material to provide the patterned insulating layer.

9. The method according to any one of claims 1 to 6, comprising curing the medium and / or another medium.

10. The method according to any one of claims 1 to 6, wherein, The organic semiconductor and / or another organic semiconductor includes a conjugated organic semiconductor having multiple conjugated structures, wherein at least two of the multiple conjugated structures have different functional properties.

11. The method according to claim 10, wherein, One functional property is the absorption of the first dominant peak wavelength, and another functional property is the emission of light absorbed at the second dominant peak wavelength.

12. The method according to any one of claims 1 to 6, wherein, Each of the plurality of light-emitting pixels has a size of less than or equal to 100 μm. 2 The luminescent surface.

13. A high-resolution, single-cell micro-light-emitting diode array, wherein, The high-resolution single-cell micro-light-emitting diode array includes multiple light-emitting pixels with a pixel pitch of less than 4μm, and comprises: A patterned insulating layer on a light-emitting diode array, the patterned insulating layer defining the boundary of the light-emitting surface of a first light-emitting pixel associated with a first light-emitting diode and the boundary of the light-emitting surface of a second light-emitting pixel associated with a second light-emitting diode; A conformal reflective layer on the patterned insulating layer exposes the light-emitting surface of the first light-emitting pixel associated with the first light-emitting diode and the light-emitting surface of the second light-emitting pixel associated with the second light-emitting diode; A flat and smooth medium within the light-emitting surface boundary of the first light-emitting pixel associated with the first light-emitting diode, wherein organic semiconductors are dispersed, wherein the first light-emitting diode is configured to emit light of a first dominant peak wavelength, and wherein the organic semiconductors are configured to receive and convert input light of the first dominant peak wavelength from the light-emitting diode to provide output light of a second dominant peak wavelength; and A passivation layer is applied to the light-emitting diode array to protect the dielectric.

14. The light-emitting diode array according to claim 13, wherein, At least one additional light-emitting pixel includes: Another light-emitting diode configured to emit light at the first main peak wavelength; and Another organic semiconductor dispersed in another medium, wherein the other organic semiconductor is configured to receive and convert input light of the first main peak wavelength from the other light-emitting diode to output light of the third main peak wavelength.

15. The light-emitting diode array according to claim 13 or 14, wherein, One or more of the light-emitting diodes include a material covering the light-emitting surface of the one or more light-emitting diodes, wherein the material is an optically transparent material that enables light to be emitted from the covered one or more light-emitting diodes, and wherein the one or more light-emitting diodes are configured to emit light having the dominant peak wavelength.

16. The light-emitting diode array according to claim 13 or 14, wherein, The medium and / or another medium includes at least one of the following: resin, epoxy resin, and polymer.

17. The light-emitting diode array according to claim 13 or 14, wherein, The organic semiconductor and / or another organic semiconductor includes a conjugated organic semiconductor having multiple conjugated structures, wherein at least two of the multiple conjugated structures have different functional properties.

18. The light-emitting diode array according to claim 13 or 14, wherein, Each of the plurality of light-emitting pixels has a light-emitting surface area of ​​less than or equal to 100 μm2.

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