CN116261357A - Light emitting device and electronic apparatus including the same - Google Patents

Abstract

The present disclosure relates to a light emitting device and an electronic apparatus including the same. A light emitting device, comprising: a substrate; a plurality of first electrodes located on the substrate; a plurality of trenches disposed in an upper surface of the substrate, each trench of the plurality of trenches being located between adjacent first electrodes of the plurality of first electrodes; a stack of functional layers located over the plurality of first electrodes, the stack including at least a light emitting layer including a plurality of cells disposed in correspondence with respective ones of the plurality of first electrodes; and a second electrode over the stack, wherein an isolation structure extending from the substrate or the first electrode to a height of the plurality of cells or more to separate the plurality of cells is not provided between the plurality of cells.

Description

Light emitting device and electronic apparatus including the same

Technical Field

The present disclosure relates to the field of optoelectronic devices, and more particularly, to light emitting devices and electronic apparatuses including light emitting devices.

Background

Light emitting devices such as light emitting diodes are widely used in the field of lighting and display. In a display device, a Pixel Definition Layer (PDL) for defining pixels is generally provided. Typically, the pixel defining layer is in the form of an isolation structure (bank) to define pixels (or sub-pixels) to separate the pixels (or sub-pixels). The pixel defining layer is typically fabricated on a substrate, also referred to as a Thin Film Transistor (TFT) substrate, on which active devices, such as TFTs, are formed.

Disclosure of Invention

According to an aspect of the present disclosure, there is provided a light emitting device including: a substrate; a plurality of first electrodes located on the substrate; a plurality of trenches disposed in an upper surface of the substrate, each trench of the plurality of trenches being located between adjacent first electrodes of the plurality of first electrodes; a stack of functional layers located over the plurality of first electrodes, the stack including at least a light emitting layer including a plurality of cells disposed in correspondence with respective ones of the plurality of first electrodes; and a second electrode over the stack, wherein an isolation structure extending from the substrate or the first electrode to a height of the plurality of cells or more to separate the plurality of cells is not provided between the plurality of cells.

According to another aspect of the present disclosure, there is provided an electronic device comprising a light emitting apparatus according to any one of the embodiments of the present disclosure.

Other features of the present disclosure and its advantages will become more apparent from the following detailed description of exemplary embodiments of the disclosure, which proceeds with reference to the accompanying drawings.

Drawings

The foregoing and other features and advantages of the disclosure will be apparent from the following description of embodiments of the disclosure, as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the disclosure and to enable a person skilled in the pertinent art to make and use the disclosure. Wherein:

FIGS. 1A and 1B are schematic views showing a prior art method of producing a light emitting device by ink jet printing;

fig. 2A illustrates a schematic diagram of a light emitting device according to some embodiments of the present disclosure;

fig. 2B shows a photomicrograph of a printed Quantum Dot (QD) layer in the example light emitting device having the structure shown in fig. 2A, and fig. 2C shows a steppers scanning result corresponding to the region shown in fig. 2B;

fig. 3A and 3B illustrate schematic diagrams of light emitting devices according to further embodiments of the present disclosure;

fig. 4A to 4D schematically illustrate plan views of example arrangements of grooves of a light emitting device according to some embodiments of the present disclosure;

fig. 5A to 5C illustrate schematic diagrams of light emitting devices according to further embodiments of the present disclosure;

fig. 6A and 6B schematically illustrate plan views of example arrangements of auxiliary electrodes of a light emitting device according to some embodiments of the present disclosure;

fig. 7 illustrates a flowchart of a method of manufacturing a light emitting device according to some embodiments of the present disclosure;

fig. 8A to 8H illustrate schematic diagrams of an example manufacturing process of a light emitting device according to some embodiments of the present disclosure;

fig. 9A-9C illustrate schematic diagrams of a relationship of a cell of a printed light emitting layer to a first electrode, according to some embodiments of the present disclosure;

Fig. 10A and 10B illustrate schematic diagrams of a relationship of a cell of a printed light emitting layer to a first electrode according to some embodiments of the present disclosure.

Note that in the embodiments described below, the same reference numerals are used in common between different drawings to denote the same parts or parts having the same functions, and a repetitive description thereof may be omitted. In some cases, like numbers and letters are used to designate like items, and thus once an item is defined in one drawing, no further discussion thereof is necessary in subsequent drawings.

For ease of understanding, the positions, dimensions, ranges, etc. of the respective structures shown in the drawings and the like may not represent actual positions, dimensions, ranges, etc. Accordingly, the present disclosure is not limited to the disclosed positions, dimensions, ranges, etc. as illustrated in the accompanying drawings.

Detailed Description

Various exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless it is specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. That is, the structures and methods herein are shown by way of example to illustrate different embodiments of the structures and methods in this disclosure. However, those skilled in the art will appreciate that they are merely illustrative of the exemplary ways in which the disclosure may be practiced, and not exhaustive. Moreover, the figures are not necessarily to scale, some features may be exaggerated to show details of particular components.

In addition, techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate.

In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values.

Many light emitting devices are electroluminescent devices that emit light using an electroluminescence principle, such as quantum dot light emitting devices (QLEDs), organic Light Emitting Devices (OLEDs), and the like. Such electroluminescent devices typically comprise a stack of functional layers (including at least a light-emitting layer, optionally also an electron injection layer, an electron transport layer, a hole injection layer, etc.) arranged between an anode and a cathode. In general, the light emitting layer includes a separate unit dedicated to each pixel, and functional layers such as an electron injection layer, an electron transport layer, a hole injection layer, and the like may be shared by a plurality of pixels, and thus may also be referred to as a common layer.

Currently, electroluminescent devices are usually manufactured by wet processes (especially, specific functional layers of QLEDs can only be manufactured by wet processes), and mainly an inkjet printing (inkjet print) process is adopted. In printing processes, it is generally considered necessary for the skilled person to define the pixels with isolation structures (banks) because without such isolation structures different pixels would easily be caused to touch each other and interfere with each other. In order to achieve a good isolation effect, the height of the isolation structure is often set to be as high as several micrometers, well beyond the height of the stack of functional layers of the light emitting device.

However, the inventors of the present application have realized that, particularly when a functional layer such as a light-emitting layer is prepared by an inkjet printing process, ink droplets are affected by capillary effect at the isolation structure, and after drying, accumulation is formed at the edge of the isolation structure, resulting in uneven film formation, thereby making the light-emitting performance of the prepared light-emitting device poor. When a plurality of functional layers are formed, this edge build-up phenomenon may accumulate layer by layer. In addition, ink development is generally based on an open system to adjust the formulation and annealing process first, but in this case the optimized formulation is not necessarily suitable for substrates with isolated structures. In addition, the total thickness of the film layer of the device functional layer is generally several hundred nanometers (for example, 100 to 200 nanometers), and in the case of a top emission type light emitting device, the top electrode has to be formed relatively thin (typically, several tens nanometers, for example, 20 nanometers of silver electrode) in order not to hinder light emission, and the isolation structure of up to several micrometers may destabilize the lap joint of such thin top electrode, resulting in the occurrence of dead spots (pixels that do not emit light).

For example, fig. 1A and 1B show schematic diagrams of a light emitting device manufactured by an inkjet printing method in the related art. As shown in fig. 1A, a plurality of bottom electrodes 1103 and a plurality of isolation structures 1105 for defining a pixel region are formed on a substrate 1101. Ink droplets 1207, 1209, 1211 containing a material for forming a functional layer are printed on the substrate 1101 through the nozzle 1205, so that the functional layers 1107, 1109, 1111, such as a light-emitting layer, or the like, are printed in the pixel region defined by the isolation structure. It can be seen that the printed ink droplets 1207, 1209, 1211 are affected by capillary effects at the spacer structure 1105, and wet along the surface of the spacer structure 1105, causing the film thickness at the edges to be greater than the film thickness at the center, thereby causing build-up of material at the edges of the spacer structure 1105 after drying, resulting in non-uniformity of the functional layers 1107, 1109, 1111 formed. This phenomenon is more serious when a stack of a plurality of functional layers (including, for example, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and the like) is formed. As shown in fig. 1B, the functional layers 1107, 1109, 1111 and the top of the isolation structure 1105 are typically covered with an entire top electrode 1113. Since the height of the isolation structure is greatly different from the total thickness of the film layer, especially when the light emitting device is configured as a top emission type, the top electrode is formed to be thin, breakage of the top electrode (as shown by a crack 1115) is easily caused, thereby causing unstable overlapping of the top electrode.

In addition, when both the light emitting layer and the common layer are prepared by a printing process, the difficulty of preparing ink for preparing the common layer is greater than that of a process of printing only the light emitting layer. This is because the formulation between the layers is required to meet the criteria of orthogonality, and the choice of solvents is limited, so it is very difficult to achieve a uniform film layer that is flat and does not build up for each layer of formulation under such conditions. Therefore, when a light emitting device is manufactured by a wet process, a light emitting layer is generally manufactured by a printing process only, and a common layer is manufactured by a mature evaporation process. However, the evaporation process has low material utilization and high equipment operation cost, and is not suitable for manufacturing a light emitting device of a large size. Therefore, it is also possible to prepare a common layer by a coating process and to prepare a light emitting layer by a printing process, which is simple and low in cost, and is very suitable for manufacturing a light emitting device such as an OLED or QLED of a large size.

However, as previously mentioned, it is generally recognized in the art that the printing process of the light emitting layer requires the use of an isolation structure to localize the printed ink droplets within the pixel area defined by the isolation structure. However, in either the vapor deposition and printing process or the coating and printing process, the common layer material is vapor deposited or coated on the isolation structure during vapor deposition or coating of the common layer material, which makes it very easy for leakage phenomena to occur, increases power consumption of the light emitting device, or causes other short circuit problems.

In view of the above problems caused by the isolation structure, the inventors of the present application have conducted the contrary, and have abandoned the isolation structure design in the prior art, and have provided a light emitting device having a novel structure. The novel structure of such a light emitting device is counter intuitive to the person skilled in the art, but the inventors of the present application have found through research that the light emitting performance thereof is not at all inferior, even significantly superior, to the light emitting device having the prior art design of the isolation structure. Embodiments of the present disclosure are specifically described below with reference to the accompanying drawings. In different implementations, the light emitting device according to various embodiments of the present disclosure may be a bottom emission type light emitting device that emits light through the bottom electrode and the substrate, a top emission type light emitting device that emits light through the top electrode, or a double-sided emission type light emitting device that emits light through both.

Fig. 2A illustrates a schematic diagram of a light emitting device 100 according to some embodiments of the present disclosure. As shown in fig. 2A, the light emitting device 100 includes a substrate 101. A plurality of first electrodes (also referred to as bottom electrodes) 103 are formed on the substrate 101. The light emitting device 100 further comprises a stack of functional layers (not denoted by a reference numeral) over the plurality of first electrodes 103. The stack comprises at least a light emitting layer comprising a plurality of mutually independent cells 107 arranged in correspondence with the respective first electrodes 103. In the embodiment shown in fig. 2A, a plurality of cells 107 are arranged in the same layer. In other words, the plurality of cells 107 are disposed in the same layer with substantially the same thickness within the range of process accuracy. However, in other embodiments, the thickness of the plurality of cells 107 capable of emitting light in different wavelength bands may also be different. The light emitting device 100 further comprises a second electrode (also referred to as top electrode) 111 located over the stack. Optionally, the stack further comprises a lower functional layer 105 below the light emitting layer and/or an upper functional layer 109 above the light emitting layer. The lower functional layer 105 and/or the upper functional layer 109 may each include one or more functional layers. Here, the functional layer has a general meaning in the art. As an exemplary description, the functional layer may mean: a layer for the light emitting unit disposed between the top electrode and the bottom electrode of the light emitting unit. The functional layer may include at least one of: a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, an electron transport layer, an electron blocking layer, a buffer layer, and/or any layer that performs other desired functions, and the like. In addition, although in the example shown in fig. 2A, one or more functional layers are shown as being integral, that is, the functional layers may be commonly used for a plurality of pixels or sub-pixels, in other embodiments, the functional layers may also include a plurality of units, and a single unit may be used for one or more pixels or sub-pixels.

In the light emitting device 100 according to the present embodiment, an isolation structure extending upward from the substrate 101 or the first electrode 103 to the height of the plurality of cells 107 or more to separate the plurality of cells 107 is not provided between the plurality of cells 107. In other words, in the light emitting device of the embodiment of the present disclosure, there is no pixel defining layer in the related art, whereby a uniform and flat film layer and a stable overlap of the top electrode can be achieved, thereby achieving improved light emitting performance. For example, as shown in fig. 2B and 2C, in the quantum dot light emitting device manufactured according to the present embodiment, the formed QD film layer is substantially uniform from the edge to the intermediate film layer, and the light emitting uniformity is good.

The inventors of the present application further note that, as indicated by the thick solid arrows in fig. 2A, the current should ideally flow from each first electrode 103 (e.g., as an anode) to the second electrode 111 (e.g., as a cathode) via the corresponding portion of the lower functional layer 105, the corresponding cell 107, the corresponding portion of the upper functional layer 109 that are located above that first electrode 103, but, especially when the lower functional layer 105 is commonly used for a plurality of pixels or sub-pixels, the common lower functional layer 105 will conduct laterally between adjacent first electrodes 103 due to the conductive capability of the material of the lower functional layer 105, as indicated by the dashed arrows in fig. 2A. Such lateral conduction may cause leakage of the device to increase power consumption of the device, degrading light emitting performance of the device.

In order to further solve the problem of lateral leakage of the common layer on the basis of ensuring uniform and flat film layers, the present disclosure further provides an improved light emitting device, which includes: a substrate; a plurality of first electrodes located on the substrate; a plurality of trenches disposed in an upper surface of the substrate, each trench of the plurality of trenches being located between adjacent first electrodes of the plurality of first electrodes; a stack of functional layers located over the plurality of first electrodes, the stack including at least a light emitting layer including a plurality of cells disposed in correspondence with respective ones of the plurality of first electrodes; and a second electrode over the stack, wherein an isolation structure extending from the substrate or the first electrode to a height of the plurality of cells or more to separate the plurality of cells is not provided between the plurality of cells. Thus, by providing the trench between the first electrodes in the substrate, the resistance of the electrical path between adjacent first electrodes can be increased in the presence of the common layer material between the adjacent first electrodes to suppress or even eliminate the flow of current on the electrical path. Such a light emitting device will be further described below with reference to the accompanying drawings.

Fig. 3A illustrates a light emitting device 200A according to some embodiments of the present disclosure. The light emitting device 200A includes a substrate 201, a plurality of first electrodes 203 positioned over the substrate 201, and a plurality of trenches 213 provided in an upper surface of the substrate 201. Each trench 213 is located between adjacent first electrodes 203. The substrate 201 may be a light-transmissive or light-impermeable substrate, and may be a rigid or flexible substrate; the present disclosure is not limited in this regard. In some embodiments, the substrate 201 may be a TFT substrate, each first electrode 203 may be electrically connected to a corresponding TFT in the TFT substrate via a via, and the trench 213 may be formed in a planar layer (e.g., may be formed of silicon nitride and/or silicon oxide, etc.) of the TFT substrate surface. The light emitting device 200A further includes a stack of functional layers (not shown with reference numerals) over the plurality of first electrodes 203. The stack comprises at least a light emitting layer comprising a plurality of cells 207 arranged in correspondence with respective first electrodes of said plurality of electrodes. In some embodiments, the cells 207 may be disposed in one-to-one correspondence with the first electrodes 203. In some embodiments, the front projection of each unit 207 on the substrate 201 covers the front projection of the first electrode 203 corresponding to the unit 207 on the substrate 201, which may improve the light emitting efficiency. The light emitting device 200A further includes a second electrode 211 located over the stack of functional layers. One of the first electrode 203 and the second electrode 211 may be configured as a cathode, and the other may be configured as an anode, without being particularly limited herein. In some embodiments, the second electrode 211 may be a full-face electrode (or, a blanket electrode) that may cover the functional layers of the plurality of pixels. However, the present disclosure is not limited thereto. In some embodiments, the second electrode 211 may be configured to allow light emitted by the light emitting layer to be transmitted therethrough.

Respective ones of the plurality of cells 207, corresponding first electrodes 203, and corresponding portions of the second electrodes 211 of the light emitting layer may be included in corresponding pixels. The corresponding first electrode 203, the corresponding portion in the stack of functional layers, and the corresponding portion of the second electrode 211 together constitute a light emitting unit. In general, a pixel may include one or more light emitting units. The pixel may also include a plurality of sub-pixels, each having a light emitting unit. For example, a pixel may include three light emitting units (which may also be referred to as sub-pixels) of red, green, and blue (RGB).

In the light emitting device 200A, an isolation structure extending from the substrate 201 or the first electrode 203 to the height of the plurality of cells 207 or more to separate the plurality of cells 207 is not provided between the plurality of cells 207, but a trench 213 is provided between adjacent first electrodes 203. The trench 213 may be used to separate different pixels or sub-pixels and does not generate a capillary effect of the isolation structure, so that a uniform and flat film layer may be realized in the pixel region.

In some embodiments, the stack may further include a lower functional layer 205 located below the light emitting layer. In some embodiments, the units of the light emitting layer are formed by cross-linking a printed or coated quantum dot composition. The crosslinking may be, for example, thermal crosslinking or photocrosslinking. This may form a quantum dot light emitting device. In some embodiments, the quantum dots may be configured to be uniformly dispersed in ink droplets for inkjet printing.

In some embodiments, a portion of the lower functional layer 205 (or one or more of them) below the light emitting layer may be treated to have a different surface property than the other portions, thereby affecting the printing of the ink drops. For example, a portion of the surface of the lower functional layer 205 (or one or more of the layers) may be uv treated to alter its hydrophilic-hydrophobic or other properties. However, since the functional layers are generally layers requiring photoelectric properties or other properties and have complex compositions, such treatment may adversely affect the photoelectric properties, chemical properties, surface flatness, or the like, thereby affecting device performance. In addition, in the process of patterning by the surface affinity and hydrophobicity treatment, the materials of each functional layer are required to have the same surface affinity, so that the materials of the functional layers are more severely selected, and the photoelectric performance of the light emitting device is required to be simultaneously considered. Thus, in a more preferred embodiment, such processing is not performed, but the surface properties of the respective portions of the lower functional layer 205 are made uniform. Thus, the process complexity is reduced, the preparation efficiency is improved, the cost is reduced, and the influence on the performance of the device is minimized. Thus, preferably, in some embodiments, the portion of the lower functional layer 205 that overlaps the cells 207 of the light emitting layer is consistent with the surface properties of the portion of the lower functional layer 205 that does not overlap the cells 207 of the light emitting layer.

The lower functional layer 205 includes a plurality of first portions located above the plurality of first electrodes 203 and a plurality of second portions located in the plurality of trenches 213. In the embodiment shown in fig. 3A, each first portion of the lower functional layer 205 is continuous with an adjacent second portion. However, compared to the case where the trench 213 is not present (for example, as shown in fig. 2A), the length of the electrical path (i.e., the distance between adjacent first electrodes along the lower functional layer) indicated by the dotted arrow in fig. 3A increases, and thus the resistance of the electrical path increases. In some embodiments, the lower functional layer 205 is formed by a coating process. The second portion of the lower functional layer 205 coated within the trench 213 may be non-uniform. For example, the portion of the lower functional layer 205 coated on the sidewall of the trench 213 is thinner than the portion of the lower functional layer 205 coated outside the trench 213, which further increases the resistance of the electrical path. Thus, since current generally tends to flow on an electrical path of small resistance, current may flow on a thick solid arrow, while current flow on a dashed arrow may be inhibited or even prohibited.

In other embodiments, such as the light emitting device 200B shown in fig. 3B, each first portion of the lower functional layer 205 is discontinuous with an adjacent second portion. This causes the electrical path indicated by the dashed arrow in fig. 2A to be broken or no longer present. Accordingly, the leakage phenomenon due to lateral conduction of the lower functional layer 205 is suppressed or eliminated.

In fact, whether the lower functional layer 205 is continuous or discontinuous at the respective trenches 213, the leakage phenomenon due to lateral conduction of the lower functional layer 205 can be effectively improved. For example, the particular shape of the trenches 213 may affect whether the lower functional layer 205 is continuous or discontinuous at each trench 213. The included angle between the bottom surface and the side surface of the trench 213 may be defined as a slope angle of the trench 213. When the sloped angle of the trench 213 is an acute or right angle, the cross-sectional shape of the trench 213 may be, for example, trapezoidal or rectangular as shown in fig. 3B, in which case the lower functional layer 205 may be more prone to discontinuity or break at the trench 213. When the slope angle of the trench 213 is an obtuse angle, the cross-sectional shape of the trench 213 may be, for example, an inverted trapezoid as shown in fig. 3A, in which case the lower functional layer 205 may be more prone to be continuous at the trench 213 than in the case where the slope angle of the trench 213 is an acute or right angle. In some cases, even though the lower functional layer 205 is continuous in the trench 213, it may be non-uniform, for example, due to gravity or the like, having a smaller thickness on the side surfaces of the trench 213 than on the bottom surface of the trench 213. In some cases, even if the slope angle of the trench 213 is an obtuse angle, the lower functional layer 205 may be discontinuous in the trench 213, for example, the lower functional layer 205 may be broken on the side surface of the trench 213 due to excessive thinning due to gravity or the like. The slope angle of the grooves 213 may be, for example, between 30 degrees and 150 degrees, or between 50 degrees and 130 degrees, or between 50 degrees and 75 degrees, 105 degrees and 130 degrees. The slope angle of the groove 213 at the side surface thereof does not necessarily need to be constant, in other words, the bottom surface and/or the side surface of the groove 213 is not limited to be planar, but may be curved. The cross-sectional shape of the groove 213 may also take any suitable shape, and is not particularly limited herein. In some embodiments, the trench 213 may satisfy at least one of the following conditions: the depth d of the trench 213 is greater than the thickness of the lower functional layer 205; the depth d of the trench 213 is smaller than the total thickness of the first electrode 203 and the stack; the width w1 of the trench 213 at the top (i.e., the upper surface of the substrate 201) is smaller than the pitch between adjacent first electrodes 203 of the plurality of first electrodes 203; the width w1 of the trench 213 at the top is not equal to the width w2 at the bottom. The width of the trench 213 may be, for example, between 0.2 and 40 microns, or between 1 and 10 microns, or may be 5 microns. The depth d of the trench 213 may be, for example, between 1 and 7 microns, or between 2 and 5 microns, or may be 3 microns. The aspect ratio (e.g., the ratio of depth d to width w 1) of the trench 213 may be, for example, 1:10 to 10:1, or may be between 1:5 to 5:1, or may be between 1:2 to 2: 1. Herein, as noted in fig. 3A and 3B, the depth d of the trench refers to the dimension of the trench in a direction perpendicular to the upper surface of the substrate 201, and the width of the trench refers to the dimension of the trench in a direction extending between adjacent first electrodes.

Fig. 4A to 4D show several example arrangements of the grooves 213 by showing, without limitation, orthographic projections of different parts of the light emitting device on the substrate 201.

In fig. 4A, a 3 x 3 array of 9 square cells 207 is shown, each cell 207 being disposed corresponding to a respective one of the first electrodes 203, and the orthographic projection of the cell 207 on the substrate 201 overlapping the orthographic projection of the corresponding first electrode 203 on the substrate 201. Each trench 213 of the plurality of trenches 213 is located between adjacent first electrodes 203, and in the example of fig. 4A, these trenches 213 are connected to each other so as to completely isolate the respective first electrodes 203.

In fig. 4B, a 1 x 3 array of 3 elongated cells 207 is shown, each cell 207 being arranged corresponding to a respective three first electrodes 203, and the orthographic projection of the cell 207 on the substrate 201 covers the orthographic projection of the corresponding three first electrodes 203 on the substrate 201. Each trench 213 of the plurality of trenches 213 is located between adjacent first electrodes 203, and in the example of fig. 4A, these trenches 213 are connected to each other so as to completely isolate the respective first electrodes 203. In the example of fig. 4A, the cell 207 may include a first portion located over the first electrode 203 and a second portion located in the trench 213. The first portion of the cell 207 over the first electrode 203 will be flat, uniform, and neither continuous nor discontinuous with the second portion of the cell 207 will negatively affect the luminescence of the cell 207.

In fig. 4C, the arrangement of the cells 207 and the first electrodes 203 is the same as in fig. 4A, and further a via 215 associated with each first electrode 203 is depicted, via which via 215 the first electrode 203 can be electrically connected to a TFT in the underlying substrate 201. In some embodiments, the orthographic projection of the via 215 onto the substrate 201 is outside the orthographic projection of the cell 207 onto the substrate 201 so as not to affect the flatness, uniformity of the portion of the cell 207 over the first electrode 203. In fig. 4C, for each first electrode 203, a trench 213 is formed on the side of the first electrode 203 other than the side where the through hole 215 is formed. Although the trench 213 does not completely surround the first electrodes 203 in this example, the lateral leakage phenomenon between adjacent first electrodes 203 is still suppressed. This is because there is a large resistance between adjacent first electrodes 203, either the electrical path across the trench 213 or the electrical path bypassing the trench 213, thereby suppressing or even prohibiting the flow of current on that electrical path. Thus, the trench 213 may completely or partially enclose the first electrode 203.

In fig. 4D, a 1 x 3 array of 3 elongated cells 207 is shown, each cell 207 being arranged corresponding to a respective one of the first electrodes 203, and the orthographic projection of the cell 207 on the substrate 201 covers the orthographic projection of the corresponding first electrode 203 on the substrate 201. It can be seen that there is one trench 213 between each two adjacent first electrodes 203. These grooves 213 may not be connected to each other.

Although in the example of fig. 4A to 4C, the plurality of grooves 213 may be depicted as being integrally connected to each other, as shown in fig. 4D, the grooves 213 may be separated. The above are just a few non-limiting examples showing the layout of the trenches 213, it being understood that the trenches 213 may have any suitable arrangement as long as they exist such that the electrical path of lateral leakage between adjacent first electrodes 203 is suppressed.

Referring back to fig. 3A or 3B, in some embodiments, the stack may further include an upper functional layer 209 over the light emitting layer. The upper functional layer 209 may cover the plurality of cells 207 of the light emitting layer. In some embodiments, as shown in fig. 3A or 3B, the plurality of cells 207 of the light emitting layer are configured to be separated from each other, and at least a portion of the upper functional layer 209 is located between the cells of the plurality of cells 207. In some embodiments, between the cells, the at least a portion of the upper functional layer 209 is in contact with a portion of the lower functional layer 205 that is not obscured by the light emitting layer.

Although the lower functional layer 205 and the upper functional layer 209 are shown as a single layer in fig. 3A, 3B, they may be a plurality of layers. For example, when the first electrode 203 is configured as an anode and the second electrode 211 is configured as a cathode, the upper functional layer 209 may include one or more of an electron injection layer, an electron transport layer, and a hole blocking layer, and the lower functional layer 205 may include one or more of a hole transport layer, a hole injection layer, and an electron blocking layer. In addition, although in the embodiments shown in fig. 3A, 3B, one or more functional layers are shown as being integral, that is, the functional layers may be commonly used for a plurality of pixels or sub-pixels, in other embodiments, the functional layers may include a plurality of units, and a single unit may be used for one or more pixels or sub-pixels.

As shown in fig. 3A and 3B, due to the presence of the trench 213, portions of the upper functional layer 209 and the second electrode 111 each above the trench 213 may be recessed with respect to portions not above the trench 213, and may even partially enter the trench 213. This may result in unevenness, unevenness of the second electrode 211. When the second electrode 211 is commonly used for a plurality of pixels or sub-pixels, for example, when the second electrode 211 is a whole surface, unevenness of the second electrode 211 may cause unstable connection between portions of the second electrode 211 for different pixels or sub-pixels. When the light emitting device emits light from the bottom side, the connection stability between portions of the second electrode 211 for different pixels or sub-pixels can be improved by increasing the thickness of the second electrode 211. When the light emitting device needs to emit light from the top side, the second electrode 211 needs to be formed thin enough so that light emitted from the light emitting layer can be transmitted therethrough, in which case an auxiliary electrode may be provided to improve the electrical connection of the second electrode 211 between portions for different pixels or sub-pixels.

In some embodiments, for example as shown in fig. 5A, the light emitting device 300A further includes an auxiliary electrode 217, the auxiliary electrode 217 being located over the second electrode 211 and configured to electrically connect portions of the second electrode 211 corresponding to the plurality of cells 207 of the light emitting layer to each other. For example, the arrangement of the auxiliary electrode 217 may be more clearly understood in connection with fig. 6A. In fig. 6A (corresponding to fig. 4A), the areas of the orthographic projection of the first electrode 203, the cell 207, the trench 213 on the substrate are depicted with dashed boxes, respectively, and in addition the whole white area (which is partially covered by the gray area) is the area of the orthographic projection of the second electrode 211 on the substrate, and the gray area is the area of the orthographic projection of the auxiliary electrode 217 on the substrate. As can be seen in conjunction with fig. 5A and 6A, the auxiliary electrode 217 electrically connects portions of the second electrode 211 corresponding to the plurality of cells 207 of the light emitting layer to each other.

In the embodiment shown in fig. 5A, the auxiliary electrode is formed on the side of the second electrode 211 facing away from the substrate 201. In other embodiments, as shown in fig. 5B, the light emitting device 300B further includes a substrate 219, wherein the substrate 219 is located above the second electrode 211, and the auxiliary electrode 217 is formed on a side of the substrate 219 facing the substrate 201. When the light emitting device 300B needs to emit light from the top side, the substrate 219 may be configured to allow light emitted from the light emitting layer to be transmitted therethrough.

In some embodiments, the front projection of the auxiliary electrode 217 on the substrate 201 does not cover the front projection of the plurality of first electrodes 203 on the substrate 201, as shown in fig. 6A, for example. In this way, the auxiliary electrode 217 does not affect light emission, no matter how thick it is formed, especially when the light emitting device needs to emit light from the top side. Accordingly, the auxiliary electrode 217 may be provided to a desired thickness to ensure good electrical connection of the second electrode 211 for portions of different pixels or sub-pixels.

In some embodiments, the orthographic projection of the auxiliary electrode 217 on the substrate 201 covers the orthographic projection of the plurality of trenches 213 on the substrate 201, for example as shown in fig. 6A. Since possible unevenness, non-uniformity of the second electrode 211 is caused by the presence of the trench 213, the position where the second electrode 211 may be problematic for electrical connection between portions of different pixels or sub-pixels may correspond to the position of the trench 213. By having the front projection of the auxiliary electrode 217 on the substrate 201 cover the front projection of the plurality of trenches 213 on the substrate 201, it helps to ensure a good electrical connection of the second electrode 211 for the various parts of the different pixels or sub-pixels.

In some embodiments, the shape of the orthographic projection of the auxiliary electrode 217 on the substrate 201 matches the shape of the orthographic projection of the plurality of grooves 213 on the substrate 201. As shown in fig. 6A, the grooves 213 are in a grid shape, and the auxiliary electrodes 217 are also in a corresponding grid shape. As also shown in fig. 6B (corresponding to fig. 4D, in which the areas of the orthographic projection of the first electrode 203, the cell 207, and the trench 213 on the substrate are also depicted with dashed boxes, respectively), the entire white area (which is partially covered by the gray area) is the area of the orthographic projection of the second electrode 211 on the substrate, and the gray area is the area of the orthographic projection of the auxiliary electrode 217 on the substrate), the trench 213 is in separate multiple stripes, so the auxiliary electrode 217 is also in corresponding separate multiple stripes. By matching the shape of the front projection of the auxiliary electrode 217 on the substrate 201 with the shape of the front projections of the plurality of trenches 213 on the substrate 201, it helps to reduce unnecessary waste of material of the auxiliary electrode 217 while ensuring a good electrical connection of the second electrode 211 for the various parts of the different pixels or sub-pixels. It can also be seen in connection with fig. 6A and 6B that the auxiliary electrode 217 need not be integral, for example as shown in fig. 6A, but may be multi-piece, for example as shown in fig. 6B, as long as portions of the second electrode 211 located above the plurality of cells 207 of the light emitting layer can be electrically connected to each other.

In some embodiments, the auxiliary electrode 217 is configured to allow light emitted by the plurality of cells 207 of the light emitting layer to be transmitted therethrough. For example, as shown in fig. 5C, the light emitting device 300C includes an auxiliary electrode 217 formed entirely on a side of the substrate 219 facing the substrate 201, wherein the auxiliary electrode 217 may be configured to allow light emitted by the plurality of cells 207 of the light emitting layer to be transmitted therethrough by selecting a material and/or thickness thereof. For example, the substrate 219 may be a transparent substrate plated with a Transparent Conductive Oxide (TCO) film, which may serve as the auxiliary electrode 217.

A method 400 of manufacturing a light emitting device according to some embodiments of the present disclosure is described below with reference to fig. 7. The preparation method 400 may include: at step S402, a substrate having a plurality of first electrodes thereon is provided; at step S404, forming a plurality of trenches in an upper surface of the substrate, each trench of the plurality of trenches being located between adjacent first electrodes of the plurality of first electrodes; at step S406, forming a stack of functional layers on the substrate, the stack including at least a light emitting layer including a plurality of cells disposed corresponding to respective first electrodes of the plurality of first electrodes; at step S408, a second electrode is formed on the stack. The order of formation of the first electrode and the trench in the substrate is not particularly limited. In some embodiments, a substrate may be provided, then a plurality of first electrodes may be formed on an upper surface of the substrate, and then a plurality of grooves may be formed on the substrate on which the plurality of first electrodes are formed such that each groove of the plurality of grooves is located between adjacent first electrodes of the plurality of first electrodes. In some embodiments, a substrate may be provided, a plurality of trenches may be formed on an upper surface of the substrate, and a plurality of first electrodes may be formed on the substrate formed with the plurality of trenches such that corresponding ones of the plurality of trenches exist between adjacent ones of the plurality of first electrodes.

In some embodiments, the orthographic projection of each cell on the substrate covers the orthographic projection of the first electrode corresponding to the cell on the substrate. In some embodiments, isolation structures extending from the substrate or the first electrode to a height of the plurality of cells or above to separate the plurality of cells are not formed between the plurality of cells. In some embodiments, forming the light emitting layer includes: forming liquid printing units corresponding to the units of the light emitting layer corresponding to the first electrodes, wherein the liquid printing units contain quantum dot compositions; and cross-linking the liquid printing unit to form the plurality of units of the luminescent layer.

In some embodiments, forming the stack further includes forming a lower functional layer that is located below the light emitting layer and includes a plurality of first portions located above the plurality of first electrodes and a plurality of second portions located in the plurality of trenches. In some examples, each first portion of the lower functional layer is continuous with an adjacent second portion. In some examples, each first portion of the lower functional layer is discontinuous with an adjacent second portion. In some embodiments, the lower functional layer is formed by a coating process.

In some embodiments, a trench of the plurality of trenches satisfies at least one of the following conditions: the depth of the groove is larger than the thickness of the lower functional layer; the depth of the groove is smaller than the total thickness of the first electrode and the laminated layer; the width of the trench at the top is less than the spacing between adjacent ones of the plurality of first electrodes; the width of the trench at the top is not equal to the width at the bottom.

In some embodiments, the method 400 further includes forming an auxiliary electrode over the second electrode and configured to electrically connect portions of the second electrode corresponding to the plurality of cells of the light emitting layer to each other. In some examples, the orthographic projection of the auxiliary electrode on the substrate does not cover the orthographic projection of the plurality of first electrodes on the substrate. In some examples, the orthographic projection of the auxiliary electrode on the substrate covers the orthographic projection of the plurality of grooves on the substrate. In some examples, the shape of the orthographic projection of the auxiliary electrode on the substrate matches the shape of the orthographic projection of the plurality of grooves on the substrate. In some examples, the auxiliary electrode is configured to allow light emitted by the plurality of cells of the light emitting layer to be transmitted therethrough. In some examples, forming the auxiliary electrode includes forming the auxiliary electrode on a side of the second electrode facing away from the substrate. In some examples, the substrate is a first substrate, and the method 400 of preparing further comprises: providing a second substrate having an auxiliary electrode formed thereon; the second substrate is bonded to the first substrate in such a manner that a side of the second substrate having the auxiliary electrode faces a side of the first substrate having the second electrode, such that the auxiliary electrode electrically connects portions of the second electrode corresponding to the plurality of cells of the light emitting layer to each other.

It is understood that the specific embodiment of the preparation method 400 may be similar to any embodiment of the light emitting device described above, and will not be described herein.

For ease of understanding, an example process for preparing the light emitting device 300B according to an embodiment of the present disclosure is specifically described below in conjunction with fig. 8A to 8H. Although in the example shown in fig. 8A to 8H, one or more functional layers are shown as being integral, that is, the functional layers may be commonly used for a plurality of pixels or sub-pixels, in other embodiments, the functional layers may also include a plurality of units, and a single unit may be used for one or more pixels or sub-pixels.

As shown in fig. 8A, a substrate 201 having a plurality of first electrodes 203 thereon is provided. For example, the substrate 201 may be sequentially washed with a detergent, an organic solvent, deionized water, or the like, and then dried, or may be additionally subjected to surface plasma treatment or the like. The first electrode 203 may be made of any suitable electrode material according to actual needs. The substrate 201 may be, for example, a TFT substrate. For example, the TFT substrate may be fabricated by: cleaning and/or surface plasma treating the substrate; depositing and patterning a layer of gate material to form a gate electrode layer (e.g., 45 nm molybdenum/200 nm tungsten); depositing a gate insulation layer (e.g., 400 nm silicon nitride/50 nm silicon oxide); depositing and patterning an active layer (e.g., 70 nm IGZO); depositing an etch stop layer (e.g., 100 nm silicon oxide); depositing and patterning a source/drain material layer to form a source/drain electrode layer (e.g., 45 nm molybdenum/200 nm aluminum/45 nm molybdenum); depositing a planar layer (e.g., 25 microns of silicon nitride/200 nanometers of silicon oxide); the planar layer is subjected to Chemical Mechanical Polishing (CMP). In some examples, a passivation layer may be additionally formed between the planarization layer and the source-drain electrode layer of the TFT substrate. In addition, a via hole penetrating the planarization layer to the source-drain electrode layer may be formed, then a first electrode material is deposited to fill the via hole and form a first electrode film, and then the first electrode film is patterned to form a plurality of first electrodes 203 electrically connected to the source-drain electrode layer via the corresponding via hole. When the first electrode 203 is configured as an anode, for example, 10 nm of ITO/150 nm of aluminum/35 nm of ITO may be used.

As shown in fig. 8B, a plurality of trenches 213 may be formed in the upper surface of the substrate 201, each trench 213 being located between adjacent first electrodes 203. For example, the trench 213 may be formed in a flat layer of the TFT substrate. For example, the trench 213 may be formed by photolithography, inductively Coupled Plasma (ICP) etching, photoresist stripping processes, wherein the ICP process may include carbon tetrafluoride (CF) at 800sccm at a pressure of 10 millitorr with 25kW of source power, 25kW of bias power applied to the sputtering apparatus ₄ ) And 1000sccm of oxygen (O) ₂ ) The flat layer of the TFT substrate is sputtered to remove silicon nitride and silicon oxide and photoresist in the flat layer.

Next, a stack of functional layers may be formed. As shown in fig. 8C, a lower functional layer 205 may be prepared on the substrate 201 where the first electrode 203 and the trench 213 are formed. The lower functional layer 205 includes a first portion located on the first electrode 203 and a second portion located in the trench 213. As previously described, the first and second portions of the lower functional layer 205 may be continuous or discontinuous. Although the lower functional layer 205 is illustrated as a single layer, it may include one or more layers. For example, when the first electrode 203 is configured as an anode, the lower functional layer 205 may include a hole injection layer and a hole transport layer located over the hole injection layer. The hole injection layer may be, for example, PEDOT: PSS, the hole transport layer may be for example TFB, or they may be of any other suitable material. Those skilled in the art will appreciate that a wide variety of methods (e.g., coating, etc.) can be employed to prepare the functional layer. In some implementations, the thickness of the hole injection layer may be in the range of tens to hundreds of nanometers, for example 20 to 300 nanometers, or 30 to 150 nanometers; the thickness of the hole transport layer may be in the range of several tens to several hundreds of nanometers, for example, 10 to 200 nanometers, or 15 to 100 nanometers.

After the lower functional layer 205 is prepared, a light emitting layer may be formed on the lower functional layer 205. As shown in fig. 8D, the light emitting layer includes a plurality of cells 207, and the plurality of cells 207 are disposed corresponding to respective first electrodes 203 among the plurality of first electrodes 203. In some implementations, the Quantum Dot (QD) light emitting layer may be prepared as follows: after the QD stock solution is subjected to centrifugal precipitation, the formula of the QD stock solution which is redispersed in a printing solvent is prepared into printable ink, and the printable ink is filled into printing equipment; according to the set printing parameters, the QD ink is precisely printed on the areas of the mutually independent first electrodes 203 of the substrate 201, and the corresponding areas of the first electrodes 203 are completely covered; substrate 201 is then transferred to a vacuum hotplate, dried, and QDs cured by thermal crosslinking. Of course, other methods than the printing combined with thermal crosslinking described above may be used to prepare the QD layer. For example, the QD layer may be prepared by a method of coating in combination with photocrosslinking. Specifically, QD material may be coated on the lower functional layer 205 to form a single QD film, then a photoresist is coated on the QD film and exposed and developed using a mask to expose the quantum dot region to be crosslinked, then QDs of the region not protected by the photoresist may be irradiated with ultraviolet light through the mask to be crosslinked, then the substrate 201 may be rinsed with a tetramethylammonium hydroxide TMAH solvent to remove the excess crosslinking liquid and the photoresist may be removed, and finally uncrosslinked QDs may be removed with a solvent such as toluene, octane, etc., thereby forming the unit 207. In some implementations, the QD light emitting layer may have a thickness in the range of tens to hundreds of nanometers, for example, 10 to 100 nanometers, or 15 to 50 nanometers.

Next, as shown in fig. 8E, an upper functional layer 209 may be formed over the light emitting layer. Although the upper functional layer 209 is illustrated as a single layer, it may include one or more layers. For example, when the first electrode 203 is configured as an anode, the upper functional layer 209 may include an electron transport layer, which may be formed of ZnO or any other suitable material, for example. The thickness of the electron transport layer may be in the range of tens to hundreds of nanometers, for example, 10 to 400 nanometers, or 20 to 100 nanometers.

Next, as shown in fig. 8F, a second electrode 211 may be formed over the upper functional layer 209. In this example, when the second electrode 211 is configured as a cathode, the second electrode may be formed by steaming aluminum or silver. In some implementations, the second electrode 211 may be configured to be formed entirely to cover an area of one or more pixels (or sub-pixels). The material and the formation of the second electrode may be selected according to the actual situation.

Next, as shown in fig. 8G, a substrate 219 on which the auxiliary electrode 217 is formed may be provided. Then, as shown in fig. 8H, the substrate 219 is bonded to the substrate 201 in such a manner that the side of the substrate 219 having the auxiliary electrode 217 faces the side of the substrate 201 having the second electrode 211, so that the auxiliary electrode 217 electrically connects portions of the second electrode 211 corresponding to the plurality of cells 207 of the light emitting layer to each other.

Fig. 9A-9C illustrate schematic top views of a relationship of a cell of a printed light emitting layer to a first electrode according to some embodiments of the present disclosure. In these embodiments, the first electrode 203 is shown as circular. The cells 207 of the light emitting layer are also shown as circles. This is merely exemplary and not limiting and the first electrode 203 and the cell 207 may have any other suitable shape. In a top view, the cells 207 of the light emitting layer cover the first electrode 203. That is, the orthographic projection of the unit 207 of the light emitting layer on the substrate 201 covers the orthographic projection of the corresponding first electrode 203 on the substrate. Here, it is easily understood by those skilled in the art that the shape of an actual ink droplet after drying may generally be close to a circle, but it is difficult to achieve a perfect circle, and theoretical calculation is made here taking a circle as an example. In practical applications, however, one skilled in the art can readily calculate according to actual needs based on the principles taught herein.

In some embodiments, the light emitting layer is made by a method of ink droplet printing, in which case the unit 207 formed by ink droplet printing preferably covers the first electrode 203. As shown in fig. 9A, assuming that the radius of the circular unit 207 formed after the ink droplet is dried (which can be regarded as half of the lateral dimension (diameter)) is R, the radius of the first electrode 203 is R, and the accuracy of printing (for example, deviation of the ink droplet landing point) is a. It is assumed that, in an ideal case, the center of the circular unit 207 formed after the printed ink droplets are dried coincides (is aligned) with the circular first electrode 203. Here, it should be noted that the alignment of the nozzles of the printing apparatus with the first electrode may be achieved by a function of the apparatus itself (for example, automatic alignment of the CCD camera), and the landing accuracy is determined by the printing apparatus.

The radius R of the circular unit 207 formed after the ink droplet is dried should be greater than or equal to the sum of the radius R of the first electrode 203 and the printing accuracy (e.g., printing drop error) a, that is, r+.r+a, in consideration of the printing accuracy (e.g., deviation of the ink drop point) a. Thus, it can be ensured that the unit 207 of the light emitting layer formed by printing can also completely cover the first electrode 203 under the condition of the printing precision a.

In general, only a portion of the printed light-emitting layer overlapping the first electrode emits light without significant leakage.

Fig. 9B shows two adjacent cells 207 of the light emitting layer and two corresponding adjacent first electrodes 203. As shown in fig. 9B, the radii of the two units 207 are R1 and R2, respectively, the printing accuracies are a1 and a2, respectively, and the radii of the two first electrodes 203 are R1 and R2, respectively. Which respectively meet the above conditions, namely R1 is larger than or equal to r1+a1, and R2 is larger than or equal to r2+a2.

The center-to-center distance D between two adjacent first electrodes 203 is configured to be greater than or equal to the sum of the radii R1, R2 of the two units 207 and the printing accuracies a1, a2. That is, D.gtoreq.R1+R2+a1+a2. In the case of a1=a2=a, the spacing D Σr1+r2+2a Σr1+r2+4a. In the case where r1=r2= R, R1 =r2=r and a1=a2=a, the spacing D is equal to or larger than 2r+2a is equal to or larger than 2r+4a.

It will be appreciated that the dimensions of the film layer and the dimensions and spacing of the first electrodes after drying of the ink drops may be considered for different display resolutions, different pixel designs (e.g., different geometries and sizes), device accuracy, and the like.

As an illustrative example, the following case may be considered. Setting initial conditions: at 150ppi resolution, 4 equally large circular first electrodes (1 red R, 1 green G, 2 blue B) were formed with a printing apparatus accuracy of 10 microns as shown in fig. 9C. The corresponding square pixel may have a side length of 169 microns (25400 microns/150), and the first electrode spacing is one half of the side length 169/2=84.5 microns. Since 2 r+2a.ltoreq.d, i.e. r.ltoreq.d-2 a/2= (84.5-2 x 10)/2=32.25 microns, i.e. the radius of the formed cell after drying of the ink drop is at most 32.25 microns. And R is less than or equal to R-a=22.25 microns, namely the maximum radius of the first electrode is 22.25 microns, and the corresponding maximum opening ratio is 21.7%.

Thus, the substrate resolution and pixel design determine the first electrode spacing, the first electrode spacing and the printing device accuracy determine the upper limit of the diameter of the cell formed by the ink droplet, and the diameter of the cell formed by the ink droplet (experimental value) determines the upper limit of the first electrode radius.

Here, the circular first electrode illustrated is merely exemplary, and its aperture ratio is relatively low as shown before, but it coincides with the natural dry shape of the printed ink droplet, and it is convenient to discuss the first electrode spacing. The same principle can be applied in a practical product to configure the cell and the electrode with the desired geometry. For example, rectangular electrodes are employed in the embodiments to be described later.

In addition, the radius R after drying of the unit formed by ink droplet printing may be affected by: ink formulation, size and shape of the first electrode. The formulation of the ink can be adjusted to change its spreading radius. In general, the higher the surface tension of the ink, the smaller the spread, and the lower the surface tension, the larger the spread. The surface tension of the ink is mainly adjusted by the proportion of various solvents in the formula (the surface tension of different solvents is different). Therefore, the ink drop of the formula can be adjusted according to actual needs so as to be printed out and not flow to the first electrode area of the adjacent sub-pixel when just covering the first electrode area. Depending on the formulation, the ratio of the diameters of the units formed by the ink droplets containing the quantum dot material before and after drying may be about 1.5:1 to about 1.1:1.

the film thickness can be changed by adjusting the solid content of the ink. Since there is no pixel isolation structure (no pixel defining member such as an isolation structure (bank)) in the embodiments of the present disclosure, the thickness of the film layer cannot be changed by increasing or decreasing the number of printing ink droplets; in this way, the solid content of the ink formula can be precisely controlled, so that the requirement of the spreading radius is met, and the thickness of the film layer is also met.

In addition, the volatilization rate of the ink can be regulated to regulate the spreading radius, and the integral volatilization rate is controlled, so that the solute in the ink drop just spreads to the required radius when the solvent with higher volatility just approaches to volatilize completely. If the radius is not yet reached, the solute may not move because of its increased viscosity in the remaining solvent, and thus the first electrode region may not be completely covered. If the solvent with higher volatility spreads to the radius, the radius may be exceeded, and adjacent sub-pixels may be disturbed, which may cause color mixing. It should be understood that these are not limiting and may be utilized in some instances instead.

Fig. 10A and 10B illustrate schematic diagrams of a relationship of a cell of a printed light emitting layer to a first electrode according to further embodiments of the present disclosure. In the embodiment shown in fig. 10A and 10B, an example of a stripe-shaped pixel is illustrated.

As shown in fig. 10A, a unit 207 formed by ink droplet (multiple) printing is elongated in shape, and has a width L; the first electrode 203 is correspondingly elongated and has a width l. Those skilled in the art will readily appreciate that a cell of a substantially elongated or any other shape of light emitting layer may be formed by printing a plurality of ink droplets and drying.

It is assumed that ideally, the center line of the unit 207 formed by ink droplet printing is aligned with the center line of the first electrode 203. Then, similarly, in order to secure coverage, the unit 207 is configured such that its half width (half of the lateral dimension, L/2) is greater than or equal to the sum of the half width (L/2) of the corresponding first electrode 203 and the printing accuracy (a), that is, L/2+.l/2+a.

Fig. 10B shows the case of adjacent cells 2071 and 2072 and the corresponding adjacent first electrodes 2031 and 2032. Each of the units 2071 and 2072 is elongated and parallel in the direction in which it extends. The corresponding first electrodes 2031 and 2032 are each elongated and parallel in the direction in which they extend. As shown in fig. 10B, the widths (lateral dimensions) of the two units 2071 and 2072 are L1 and L2, respectively, the printing accuracies are a1 and a2, respectively, and the widths (lateral dimensions) of the two first electrodes 2031 and 2032 are L1 and L2, respectively. Each of the units 2071 and 2072 and the corresponding first electrodes 2031 and 2032 satisfy the configuration described above, that is, the half width L1/2 of the unit 2071 is greater than or equal to the sum of the half width L1/2 of the corresponding first electrode 2031 and the printing accuracy a1 (L1/2. Gtoreq.l1/2+a1), and the half width L1/2 of the unit 2072 is greater than or equal to the sum of the half width L2/2 of the corresponding first electrode 2032 and the printing accuracy a2 (L2/2. Gtoreq.l2/2+a2).

Similarly, the center-to-center distance D between the adjacent two first electrodes 2031 and 2032 is configured to be greater than or equal to the sum of half widths L1/2, L2/2 of the two units 2071 and 2072 and the printing accuracy a1, a2. That is, D.gtoreq.L1/2+L2/2+a1+a2. In the case of a1=a2=a, the spacing D. Gtoreq.L1/2+L2/2+2a. Gtoreq.L1/2+l2/2+4a. In the case of l1=l2= L, L1 =l2=l and a1=a2=a, the spacing D Σl+2a Σl+4a.

As an illustrative example, an initial condition is set: the resolution of 100ppi, the equal width of red, green and blue pixels and equal distance, the printing device precision is 10 microns. The corresponding square pixel side length was 254 microns (25400 microns/100), and the first electrode spacing d=254/3=84.7 microns. The width L of the cell formed by the ink is less than or equal to D-2a=64.7 microns, and the width L of the first electrode is less than or equal to L-2a=64.7-20=44.7 microns.

According to yet another aspect of the present disclosure, there is also provided an electronic device, which may include a light emitting apparatus according to any embodiment or implementation of the present disclosure.

The words "left", "right", "front", "back", "top", "bottom", "upper", "lower", "high", "low", and the like in the description and in the claims, if present, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the disclosure described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. For example, when the device in the figures is inverted, features that were originally described as "above" other features may be described as "below" the other features. The device may also be otherwise oriented (rotated 90 degrees or at other orientations) and the relative spatial relationship will be explained accordingly.

In the description and claims, an element is referred to as being "on," attached "to," connected "to," coupled "to," etc., another element, which may be directly on, attached to, coupled to, or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly on," "directly attached to," directly connected to, "directly coupled" to, or "directly coupled" to another element, there are no intervening elements present. In the description and claims, a feature being disposed "adjacent" to another feature may refer to a feature having a portion that overlaps with, or is located above or below, the adjacent feature.

As used herein, the word "exemplary" means "serving as an example, instance, or illustration," and not as a "model" to be replicated accurately. Any implementation described herein by way of example is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, this disclosure is not limited by any expressed or implied theory presented in the technical field, background, brief summary or the detailed description.

As used herein, the term "substantially" is intended to encompass any minor variation due to design or manufacturing imperfections, tolerances of the device or element, environmental effects and/or other factors. The word "substantially" also allows for differences from perfect or ideal situations due to parasitics, noise, and other practical considerations that may be present in a practical implementation.

In addition, for reference purposes only, the terms "first," "second," and the like may also be used herein, and are thus not intended to be limiting. For example, the terms "first," "second," and other such numerical terms referring to structures or elements do not imply a sequence or order unless clearly indicated by the context.

It will be further understood that the terms "comprises" and/or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components, and/or groups thereof.

In this disclosure, the term "providing" is used in a broad sense to cover all ways of obtaining an object, and thus "providing an object" includes, but is not limited to, "purchasing," "preparing/manufacturing," "arranging/setting," "installing/assembling," and/or "ordering" an object, etc.

As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Those skilled in the art will recognize that the boundaries between the above described operations are merely illustrative. The operations may be combined into a single operation, the single operation may be distributed among additional operations, and the operations may be performed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be altered in other various embodiments. However, other modifications, variations, and alternatives are also possible. Aspects and elements of all of the embodiments disclosed above may be combined in any manner and/or in combination with aspects or elements of other embodiments to provide a number of additional embodiments. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. The embodiments disclosed herein may be combined in any desired manner without departing from the spirit and scope of the present disclosure. Those skilled in the art will also appreciate that various modifications might be made to the embodiments without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims (16)

1. A light emitting device, comprising:

a substrate;

a plurality of first electrodes located on the substrate;

a plurality of trenches disposed in an upper surface of the substrate, each trench of the plurality of trenches being located between adjacent first electrodes of the plurality of first electrodes;

a stack of functional layers located over the plurality of first electrodes, the stack including at least a light emitting layer including a plurality of cells disposed in correspondence with respective ones of the plurality of first electrodes; and

a second electrode located over the stack,

wherein an isolation structure extending from the substrate or the first electrode to a height of the plurality of cells or more is not provided between the plurality of cells to separate the plurality of cells.

2. The light emitting device of claim 1, wherein the stack further comprises a lower functional layer located below the light emitting layer and comprising a plurality of first portions located above the plurality of first electrodes and a plurality of second portions located in the plurality of trenches.

3. The light emitting device of claim 2, wherein each first portion of the lower functional layer is continuous with an adjacent second portion.

4. The light emitting device of claim 2, wherein each first portion of the lower functional layer is discontinuous with an adjacent second portion.

5. The light emitting device of claim 2, wherein a trench of the plurality of trenches satisfies at least one of the following conditions:

the depth of the groove is larger than the thickness of the lower functional layer;

the depth of the groove is smaller than the total thickness of the first electrode and the laminated layer;

the width of the trench at the top is less than the spacing between adjacent ones of the plurality of first electrodes;

the width of the trench at the top is not equal to the width at the bottom.

6. The light emitting device of claim 2, wherein the lower functional layer is formed by a coating process.

7. The light-emitting device according to claim 1, further comprising an auxiliary electrode that is located over the second electrode and is configured to electrically connect portions of the second electrode corresponding to the plurality of cells of the light-emitting layer to each other.

8. The light emitting device of claim 7, wherein the auxiliary electrode satisfies at least one of:

the orthographic projection of the auxiliary electrode on the substrate does not cover the orthographic projection of the plurality of first electrodes on the substrate;

orthographic projection of the auxiliary electrode on the substrate covers orthographic projection of the plurality of grooves on the substrate;

the shape of the orthographic projection of the auxiliary electrode on the substrate is matched with the shape of the orthographic projection of the plurality of grooves on the substrate;

the auxiliary electrode is configured to allow light emitted from the plurality of cells of the light emitting layer to be transmitted therethrough.

9. The light-emitting device according to claim 7 or 8, wherein the auxiliary electrode is formed on a side of the second electrode facing away from the substrate.

10. The light-emitting device according to claim 7 or 8, wherein the substrate is a first substrate, and the light-emitting device further comprises a second substrate over the second electrode,

Wherein the auxiliary electrode is formed on a side of the second substrate facing the first substrate.

11. The light-emitting device of claim 1, wherein the orthographic projection of each of the plurality of cells on the substrate covers the orthographic projection of a first electrode of the plurality of first electrodes corresponding to the cell on the substrate,

wherein the plurality of cells are disposed in one-to-one correspondence with the plurality of first electrodes.

12. The light emitting device of claim 1, wherein the plurality of cells are configured to be separated from one another, and wherein the stack further comprises an upper functional layer located over the light emitting layer, at least a portion of the upper functional layer being located between cells of the plurality of cells.

13. The light-emitting device of claim 12, wherein between the cells, the at least a portion of the upper functional layer is in contact with a portion of a lower functional layer below the light-emitting layer that is not obscured by the light-emitting layer.

14. The light-emitting device according to claim 2, wherein a portion of the lower functional layer overlapping with the unit of the light-emitting layer conforms to surface properties of a portion of the lower functional layer not overlapping with the unit of the light-emitting layer.

15. The light-emitting device of claim 1, wherein the plurality of cells of the light-emitting layer are formed by printed ink droplets, the plurality of cells configured to, in a top view:

for any one unit, the lateral dimension of the unit is greater than or equal to the sum of the lateral dimension of the first electrode corresponding to the unit and twice the printing precision of the nozzle for printing;

between the adjacent two units, the center-to-center distance of the two first electrodes corresponding to the adjacent two units is greater than or equal to the sum of half of the respective lateral dimensions of the adjacent two units and twice the printing accuracy of the nozzles for printing.

16. An electronic device comprising the light-emitting device according to any one of claims 1 to 15.

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