CN111370588B - Reflection-increasing film grating structure, electroluminescent device and manufacturing method thereof - Google Patents
Reflection-increasing film grating structure, electroluminescent device and manufacturing method thereof Download PDFInfo
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Abstract
The invention relates to a reflection-increasing film grating structure, an electroluminescent device and a manufacturing method thereof. The reflection increasing film grating is provided with high-refractive-index medium layers and low-refractive-index medium layers which are sequentially stacked and alternately arranged to form a reflection increasing combined film, two beams of reflected light reflected by the upper surface and the lower surface of the corresponding medium layers are mutually overlapped to form long interference, and the reflected light is enhanced. And a plurality of light transmitting slits are arranged in the reflection increasing combination film to form a grating, so that part of light enters the light transmitting slits and is reflected by the reflecting structure layer, the reflected light and the light reflected by the multilayer medium layer at the front form two adjacent beams of light, and the two beams of light can synchronously grow to form bright stripes, so that the integral reflected light is further enhanced. The reflection-increasing film grating structure is structurally designed for the side face of the electroluminescent device, so that the corresponding waveguide mode can be reduced, and the light-emitting efficiency of the electroluminescent device is enhanced.
Description
Technical Field
The invention relates to the technical field of electroluminescence, in particular to a reflection increasing film grating structure, an electroluminescence device and a manufacturing method thereof.
Background
An Organic Light Emitting Diode (OLED) device is a novel organic light emitting display device, and has many advantages of lightness, thinness, high light emitting efficiency, low power consumption, active light emission, flexible display and the like, so that research in semiconductor optoelectronics and semiconductor display industries is increasingly wide.
For OLED devices, light extraction rate has been the focus of research. This is because, for the OLED device, each functional layer is a stacked structure, only a small part of light generated between layers due to different refractive indexes of materials can be emitted from the substrate or the transparent cathode, and most of the rest light can be confined in the functional layer or emitted from the side due to various waveguide modes, so that the external quantum efficiency of the OLED device emitting light in the forward direction is only about 20%. Taking the bottom-emitting OLED device as an example, the light-emitting modes include four types, which are an external light-emitting mode, a substrate waveguide mode, an ITO/organic layer waveguide mode, and a surface plasmon effect mode, wherein only the external light-emitting mode is effective light-emitting of the OLED device. Therefore, the light extraction rate of the OLED device needs to be further improved.
In order to improve the light extraction efficiency of the OLED device, many studies have been made on the light extraction technology of the OLED, including an external light extraction technology for the substrate mode and an internal light extraction technology for the ITO/organic layer waveguide mode, and most studies have been made on reducing the light loss of the waveguide mode between the functional layers or the substrate surface, but this is not enough, and the light extraction efficiency of the OLED device cannot be further improved.
Disclosure of Invention
Therefore, an enhanced reflective film grating structure capable of effectively improving the light extraction rate of the OLED device, an electroluminescent device and a manufacturing method thereof are needed.
The technical scheme of the invention for solving the technical problems is as follows.
A reflection increasing film grating structure comprises a high-refractive-index medium layer and a low-refractive-index medium layer which are sequentially stacked, wherein the high-refractive-index medium layer and the low-refractive-index medium layer are the same in quantity, the high-refractive-index medium layer and the low-refractive-index medium layer are alternately arranged to form a reflection increasing combined film, and the refractive index of the low-refractive-index medium layer is smaller than that of the high-refractive-index medium layer in contact with the low-refractive-index medium layer;
the reflection-increasing combined film is provided with a plurality of light-transmitting slits, the light-transmitting slits extend from the outer surface of the high-refractive-index medium layer positioned on the outermost layer to the outer surface of the low-refractive-index medium layer positioned on the outermost layer in the reflection-increasing combined film so as to at least penetrate through part of the reflection-increasing combined film, and the reflection-increasing film grating structure is provided with a reflection structure below the light-transmitting slits.
In one embodiment, the light-transmitting slit penetrates through a part of the reflection-increasing combination film, and a part, which is located below the light-transmitting slit and is not provided with the light-transmitting slit, of the reflection-increasing combination film forms the reflecting structure; or
The light-transmitting slit penetrates through part of the reflection-increasing combined film, the reflection-increasing film grating structure further comprises a layer of reflection medium located on the outer surface of the low-refractive-index medium layer on the outermost layer of the reflection-increasing combined film, and the reflection medium and the part, located below the light-transmitting slit, of the reflection-increasing combined film and not provided with the light-transmitting slit jointly form the reflection structure.
In one embodiment, the light-transmitting slit penetrates through the entire antireflection combined film from the outer surface of one side of the antireflection combined film to the outer surface of the other side of the antireflection combined film;
the reflection increasing film grating structure also comprises a layer of reflection medium positioned on the outer surface of the low refractive index medium layer at the outermost layer of the reflection increasing combined film, and the reflection structure is formed by the layer of reflection medium.
In one embodiment, the high refractive index medium layer and the low refractive index medium layer are both multi-layered;
the refractive indexes of the high refractive index medium layers positioned at different layers are the same or different, and/or the refractive indexes of the low-refractive-index medium layers positioned at different layers are the same or different.
In one embodiment, the refractive index of each low-refractive-index medium layer is smaller than that of each high-refractive-index medium layer.
In one embodiment, the degree of the included angle between the light-transmitting slit and the thickness direction of the anti-reflection combination film is 0-60 °.
In one embodiment, the grating constant of the light-transmitting slit is 3-20 μm.
In one embodiment, the thicknesses d of the high refractive index medium layer and the low refractive index medium layer and the wavelength λ of incident light satisfy:
2nd+λ/2＝kλ
n is the refractive index of the corresponding dielectric layer, and k is a positive integer.
An electroluminescent device comprises a substrate, a bottom electrode layer, a pixel defining layer, a light emitting unit, a top electrode layer and the reflection-increasing film grating structure, wherein the bottom electrode layer, the pixel defining layer, the light emitting unit and the top electrode layer are arranged on the substrate, the reflection-increasing film grating structure is arranged on the substrate, the pixel defining layer is arranged around the bottom electrode layer and corresponds to the bottom electrode layer to form a pixel pit, the light emitting unit is arranged on the bottom electrode layer in the pixel pit, the top electrode layer is arranged on the light emitting unit, the reflection-increasing film grating structure is arranged on the side surface of the pixel defining layer in the pixel pit, and the outermost high-refractive-index medium layer is close to the light emitting unit in the pixel pit.
A manufacturing method of an electroluminescent device comprises the following steps:
manufacturing a pixel defining layer on a substrate, wherein pixel pits are formed on the pixel defining layer corresponding to preset positions of all light-emitting units;
fabricating an enhanced reflection film grating structure having the following structure within the pixel pits and on a side surface of the pixel defining layer: the reflection-enhanced film grating solution structure comprises a high-refractive-index medium layer and a low-refractive-index medium layer which are sequentially stacked, the high-refractive-index medium layer and the low-refractive-index medium layer are the same in number, the high-refractive-index medium layer and the low-refractive-index medium layer are alternately arranged to form a reflection-enhanced combined film, the refractive index of the low-refractive-index medium layer is smaller than that of the high-refractive-index medium layer in contact with the low-refractive-index medium layer, the low-refractive-index medium layer on the outermost layer in the reflection-enhanced combined film is close to the side surface, a plurality of light-transmitting slits are arranged in the reflection-enhanced combined film, the light-transmitting slits extend from the outer surface of the high-refractive-index medium layer on the outermost layer in the reflection-enhanced combined film to the outer surface of the low-refractive-index medium layer on the outermost layer in order to at least penetrate through part of the reflection-enhanced combined film, and the reflection-enhanced film grating structure is provided with a reflection structure below the light-transmitting slits;
and sequentially forming a bottom electrode layer, a light emitting unit and a top electrode layer in the pixel pit.
In one embodiment, the step of fabricating the reflection-enhanced film grating structure includes:
forming low-refractive-index dielectric layers and high-refractive-index dielectric layers on the side surfaces of the pixel defining layers in sequence to form the anti-reflection combination film;
and etching the reflection-enhanced combined film, and etching the outer surface of the high-refractive-index dielectric layer positioned on the outermost layer in the reflection-enhanced combined film to the outer surface of the low-refractive-index dielectric layer positioned on the outermost layer to form a light-transmitting slit penetrating through part of the reflection-enhanced combined film.
In one embodiment, the step of fabricating the reflection-enhanced film grating structure includes:
forming a layer of reflective medium over side surfaces of the pixel defining layer;
forming low-refractive-index dielectric layers and high-refractive-index dielectric layers on the reflecting medium in sequence to form the reflection-increasing combined film;
and etching the reflection-enhanced combined film, and etching the outer surface of the high-refractive-index dielectric layer positioned on the outermost layer in the reflection-enhanced combined film to the outer surface of the low-refractive-index dielectric layer positioned on the outermost layer to form a light-transmitting slit which penetrates through at least part of the reflection-enhanced combined film.
The reflection increasing film grating structure and the electroluminescent device containing the reflection increasing film grating structure form a reflection increasing combined film by arranging high-refractive-index medium layers and low-refractive-index medium layers which are sequentially stacked and alternately arranged, so that light is emitted into the high-refractive-index medium layers from the light emitting unit and then emitted into the low-refractive-index medium layers from the high-refractive-index medium layers, and the light is alternately emitted into the optically denser medium from the optically thinner medium and then emitted into the beam medium from the optically denser medium. When light enters the optically thinner medium from the optically denser medium, the reflected light does not generate phase jump, and when the light enters the interface of the optically denser medium from the optically thinner medium for reflection, the reflected light has a phase pi jump, namely half-wave loss is generated. For refracted light, there is no abrupt phase change in any case. Therefore, when two reflected lights, one reflected from the optically sparse to optically dense interface and the other reflected from the optically dense to optically sparse interface, have an additional phase difference of π, i.e., an additional optical path difference of λ/2. If the optical path difference δ satisfies the formula δ =2nd + λ/2=k λ, at this time, as long as the thickness d of the corresponding dielectric layer is controlled to satisfy 1/4 of the optical length thickness of the incident light (λ/n, n is the refractive index of the corresponding dielectric layer), that is, the thickness d of the corresponding dielectric layer is controlled to be the minimum value d = λ/4n, two beams of reflected light reflected by the upper and lower surfaces of the corresponding dielectric layer are overlapped to form longer interference, and the reflected light is enhanced.
The reflection-increasing film grating structure is structurally designed for the side face of the electroluminescent device, so that the corresponding waveguide mode can be reduced, and the light-emitting efficiency of the electroluminescent device is enhanced.
Drawings
Fig. 1 is a schematic structural diagram of an enhanced reflective film grating structure according to an embodiment of the invention;
FIG. 2 is a diagram of an optical path in an anti-reflection combined film in the anti-reflection film grating structure shown in FIG. 1;
FIG. 3 is a schematic structural diagram of an enhanced reflection film grating structure according to another embodiment;
fig. 4 is a schematic structural diagram of an electroluminescent device according to an embodiment of the present invention.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully hereinafter with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1 and fig. 2, an embodiment of the invention provides an enhanced film grating structure 100, which includes a high refractive index medium layer 110 and a low refractive index medium layer 120 sequentially stacked. The high refractive index dielectric layers 110 and the low refractive index dielectric layers 120 are the same in number. The high refractive index medium layers 110 and the low refractive index medium layers 120 are alternately arranged to form the reflection increasing composition film 102. The total number of dielectric layers (i.e., high refractive index dielectric layers 110 and low refractive index dielectric layers 120) in the entire antireflection composite film 102 is an even number.
The low index dielectric layer 120 has a refractive index less than the refractive index of the high index dielectric layer 110 in contact therewith. That is, if both sides of a certain low refractive index medium layer 120 are contacted with the high refractive index medium layers 110, the refractive index of the low refractive index medium layer 120 is smaller than that of the high refractive index medium layer 110 contacted with any one side; if only one side of a low-refractive-index dielectric layer 120 is in contact with the high-refractive-index dielectric layer 110, the refractive index of the low-refractive-index dielectric layer 120 is smaller than that of the high-refractive-index dielectric layer 110 in contact with one side thereof.
In this embodiment, the reflection increasing composition film 102 has a plurality of light-transmitting slits 130 therein, so as to form a grating structure as a whole. The light-transmitting slits 130 extend from the outer surface of the outermost high refractive index dielectric layer 110 to the outer surface of the outermost low refractive index dielectric layer 120 in the antireflection combination film 102 to penetrate at least part of the antireflection combination film 102. The "outermost layer" is two layers on both sides as viewed from the thickness direction of the antireflection combined film 102, and the rest are inner layers. The reflection-enhanced film grating structure 100 has a reflection structure 104 under the light-transmitting slit 130 to reflect light out of the light-transmitting slit 130.
The high and low refractive indices described herein are relative and are not intended to be limiting. The high refractive index dielectric layer 110 preferably includes, but is not limited to, a dielectric layer having a refractive index of not less than 2.0, an inorganic dielectric layer formed of a metal oxide having a refractive index of not less than 2.0, and the like, and a corresponding metal oxide such as HfO 2 (refractive index of 2.0) or ZrO 2 (refractive index: 2.05). The low refractive index dielectric layer 120 preferably includes, but is not limited to, a dielectric layer having a refractive index of not more than 1.70, such as an inorganic dielectric layer formed of metal oxide or metal fluoride having a refractive index of not more than 1.70, and may be, for example, siO 2 Layer (refractive index 1.46), al 2 O 3 Layer (refractive index 1.63) or MgF 2 Layer (refractive index 1.38).
In the specific example shown in fig. 1, the light-transmitting slit 130 penetrates the entire antireflection combined film 102 from the outer surface of one side of the antireflection combined film 102 to the outer surface of the other side thereof. Accordingly, the reflection-enhanced film grating structure 100 further includes a layer of reflective medium. This layer of reflective medium is disposed on the outer surface of the low refractive index medium layer 120 at the outermost layer of the reflection increasing composition film 102. The layer of reflective medium constitutes the reflective structure 104.
The material of the reflective medium of the reflective structure 104 may be, but is not limited to, a metal layer with high reflectivity, such as an Ag layer, an Al layer, etc. Preferably, the reflective medium has a reflectivity of not less than 80%. It is further preferable that the reflection medium has a reflectance of not less than 90%.
In other embodiments, as shown in fig. 3, no reflective medium may be disposed in the reflection-enhanced grating structure 900, accordingly, the light-transmitting slits 930 penetrate through part of the reflection-enhanced combined film 902, and a part of the reflection-enhanced combined film 902, which is located below the light-transmitting slits 930 and is not provided with the light-transmitting slits 930, forms the reflective structure 904, for example, in fig. 3, neither the lowermost high-refractive-index dielectric layer 910 nor the lowermost low-refractive-index dielectric layer 920 is penetrated by the light-transmitting slits 930, and the lowermost high-refractive-index dielectric layer 910 and the lowermost low-refractive-index dielectric layer 920 may together serve as the reflective structure 904.
In addition, for the design of the reflection-increasing combined film at the part where the light-transmitting slit penetrates through, a layer of reflecting medium can be additionally arranged at the bottom of the reflection-increasing combined film, and the reflecting medium and the part which is positioned below the light-transmitting slit and is not provided with the light-transmitting slit form the reflecting structure together. Through setting up the reflection medium, can strengthen the reflection of setting a camera, improve the light-emitting effect.
In one specific example, each of the high refractive index medium layers 110 and the low refractive index medium layers 120 has a plurality of layers, and the plurality of high refractive index medium layers 110 and the plurality of low refractive index medium layers 120 are alternately stacked. The refractive indexes of the high refractive index medium layers 110 located at different layers may be the same or different; independently, the refractive indices of the low-index dielectric layers 120 in different layers may be the same or different. In the particular example shown in the figure, the refractive index of each low index dielectric layer 120 is less than the refractive index of each high index dielectric layer 110.
According to the Fresnel formula, when light enters an optically thinner medium from an optically denser medium, reflected light does not generate phase jump, and when light enters an optically denser medium from an optically thinner medium for reflection, the reflected light has a phase pi jump, namely half-wave loss is generated. For refracted light, there is no abrupt phase change in any case. Therefore, when two reflected lights, one reflected from the optically sparse to optically dense interface and the other reflected from the optically dense to optically sparse interface, have an additional phase difference of π, i.e., an additional optical path difference of λ/2. If the optical path difference δ satisfies the formula δ =2nd + λ/2=k λ, at this time, as long as the thickness d of the corresponding dielectric layer is controlled to satisfy the 1/4 optical length thickness of the incident light (λ/n, n is the refractive index of the corresponding dielectric layer), that is, the thickness d of the corresponding dielectric layer is controlled to be the minimum value d = λ/4n, two beams of reflected light reflected by the upper and lower surfaces of the corresponding dielectric layer are mutually superposed to form longer interference, and the reflected light is enhanced.
When the total number of layers of the high refractive index medium layer 110 and the low refractive index medium layer 120 in the antireflection combined film 102 is 2m (m is a natural number such as 1, 2, 3 …), the reflectance R of the entire antireflection combined film 120 satisfies the following formula, and the larger the refractive index difference, the larger the number of layers, the more the reflectance will be increased.
n H And n L The refractive indexes of the high refractive index medium layer 110 and the low refractive index medium layer 120, respectively, and n0 is the refractive index of the light emitting layer.
In a specific example, the included angle between the light-transmitting slit 130 and the thickness direction of the antireflection combined film 102 is 0 to 60 °, and is preferably an acute angle, that is, the light-transmitting slit 130 is disposed obliquely, for example, it may be inclined by 30 °, 45 °, or 60 °. The light emitting layer is obliquely arranged, so that light emitted by the light emitting layer can be emitted to different reflecting surfaces, and a plurality of beams of reflected light are formed to perform light interference so as to realize the enhancement effect of the reflected light.
Further, in a specific example, the width of the light-transmitting slits is a, the distance between adjacent light-transmitting slits is b, and the grating constant d = a + b, preferably 3 μm to 20 μm. .
For grating diffraction, when the diffraction angle theta is the same, the optical path difference of the light emitted from two adjacent slits at a certain point P in space is equal, and when the diffraction angle theta meets the following conditions:
wherein a and b are the distance between two slits and the slit respectivelyThe diameter of the hole is measured,
is the incident light angle. All the light from the slits reaches the P point, interference and constructive formation of bright fringes occur, namely, light enhancement. The traditional common reflection grating is formed by preparing a layer of opaque metal on high-reflection metal and preparing stripes with equal intervals on the opaque metal. The reflection-enhanced film grating structure 100 of the present invention is based on the basic principle of reflection grating, except that the grating light-transmitting slit 130 formed by the reflection-enhanced combined film 102 is prepared on the reflective metal or highly reflective alloy layer. When light enters from the side of the low refractive index organic layer, as analyzed before, a strong reflected light is generated when the light passes through the reflection increasing composition film 102, and the reflected light and the light reflected from the reflection structure 104 through the light-transmitting slit 130 form two adjacent light beams, and a bright stripe is formed by the simultaneous phase growth between the two adjacent light beams, so that the reflected light of the whole reflection increasing film grating structure 100 is enhanced.
Further, as shown in fig. 4, the present invention also provides an electroluminescent device 10, which includes a substrate 200, a bottom electrode layer 300 disposed on the substrate 200, a pixel defining layer 400, a light emitting unit 500, a top electrode layer 600, and the reflection-enhanced film grating structure 100. In other examples, the electroluminescent device 10 may also include the reflection-enhanced film grating structure 900 shown in fig. 3 and described above.
The substrate 200 may be a hard or flexible material, and may be a transparent or non-transparent substrate, and correspondingly, the electroluminescent device 10 may be a bottom emission type device or a top emission type device. The bottom electrode layer 300 is disposed over the substrate 200. For a bottom emission device, the bottom electrode layer 300 is transparent, such as an ITO electrode layer. For a top emission type device, the top electrode layer 600 is transparent.
The pixel defining layer 400 is disposed around the bottom electrode layer 300, and a pixel pit 402 is formed corresponding to the bottom electrode layer 300. With the reflection-enhanced film grating structure 100, the pixel defining layer 400 may be made of a transparent material or an opaque material. The pixel pit 402 of the pixel defining layer 400 is preferably a truncated cone pit or a trapezoidal pit, whose upper end is large in size and lower end is small in size.
The light emitting unit 500 is disposed on the bottom electrode layer 300 within the pixel pit 402. The top electrode layer 600 is disposed on the light emitting unit 500. The light-emitting unit 500 includes a light-emitting layer 510, and the light-emitting layer 510 may be an organic light-emitting layer, an inorganic or quantum dot light-emitting layer, or the like, and is preferably an organic light-emitting layer. In the illustrated specific example, the light emitting unit 500 further includes a hole injection layer 520 and a hole transport layer 530 between the light emitting layer 510 and the bottom electrode layer 300, and an electron injection layer 540 and an electron transport layer 550 between the light emitting layer 510 and the top electrode layer 600. It is understood that in other specific examples, the light emitting unit 500 may only have the light emitting layer 510, or at least one of the hole injection layer 520, the hole transport layer 530, the electron injection layer 540 and the electron transport layer 550 and the light emitting layer 510, and may also have a structure such as an electron blocking layer and/or a hole blocking layer, which are not described herein again.
The antireflection film grating structure 100 is disposed on the side surface of the pixel defining layer 400 in the pixel pit 402, and the outermost high refractive index medium layer 110 faces the pixel pit 402, and the bottom reflection structure 104 is disposed on the side surface.
Preferably, the reflection-enhanced film grating structure 100 encloses a cylindrical structure to cover the side surface of the whole pixel defining layer 400, so as to form 360-degree uniform reflection, and effectively improve the light extraction efficiency of the whole electroluminescent device 10 at various angles.
It is further preferable that the reflection-enhanced film grating structure 100 surrounds the bottom electrode layer 300 on the substrate 200, so that the light emitted from the light-emitting unit 500 is prevented from being transmitted out through the bottom electrode layer 300, and thus the light-emitting efficiency of the whole electroluminescent device 10 can be improved.
In one specific example, as analyzed above, the thickness d of the high refractive index medium layer 110 and the low refractive index medium layer 120 and the wavelength λ of light emitted from the light emitting unit preferably satisfy: d = λ/4n, where n is the refractive index of the corresponding dielectric layer, so that the light reflected out through the reflection increasing composition film 102 can achieve a constructive purpose, enhancing the reflection effect.
The reflection-enhanced film grating structure 100 is designed for the side surface of the electroluminescent device 10, so that the corresponding waveguide mode can be reduced, and the light-emitting efficiency of the electroluminescent device 10 can be enhanced.
Further, the invention also provides a manufacturing method of the electroluminescent device, which comprises the following steps:
the method comprises the following steps: manufacturing a pixel defining layer on the substrate, wherein the pixel defining layer forms a pixel pit corresponding to the preset position of each light-emitting unit;
step two: an anti-reflection film grating structure with the following structure is manufactured in the pixel pit and on the side surface of the pixel defining layer: the reflection-enhanced film grating solution structure comprises a high-refractive-index medium layer and a low-refractive-index medium layer which are sequentially stacked, the number of the high-refractive-index medium layers is the same as that of the low-refractive-index medium layers, the high-refractive-index medium layers and the low-refractive-index medium layers are alternately arranged to form a reflection-enhanced combined film, the refractive index of the low-refractive-index medium layers is smaller than that of the high-refractive-index medium layers in contact with the low-refractive-index medium layers, the low-refractive-index medium layers on the outermost layers in the reflection-enhanced combined film are close to the side surface, a plurality of light-transmitting slits are arranged in the reflection-enhanced combined film, the light-transmitting slits extend from the outer surface of the high-refractive-index medium layers on the outermost layers in the reflection-enhanced combined film to the outer surface of the low-refractive-index medium layers on the outermost layers so as to at least penetrate through part of the reflection-enhanced combined film, and the reflection-enhanced film grating structure is provided with a reflection structure below the light-transmitting slits;
step three: a bottom electrode layer, a light emitting unit, and a top electrode layer are sequentially formed in the pixel pit.
In a specific example, the step of fabricating the reflection-enhanced film grating structure includes:
forming low-refractive-index dielectric layers and high-refractive-index dielectric layers on the side surfaces of the pixel defining layers in sequence in an alternating manner to form an anti-reflection combination film;
and etching the reflection increasing combined film, and etching the outer surface of the high-refractive-index dielectric layer positioned on the outermost layer in the reflection increasing combined film to the outer surface of the low-refractive-index dielectric layer positioned on the outermost layer to form a light-transmitting slit penetrating through part of the reflection increasing combined film.
In this example, the part of the reflection increasing and combining film, which is located below the light-transmitting slit and is not provided with the light-transmitting slit, constitutes the reflection structure.
In another specific example, the step of fabricating the reflection-enhanced film grating structure includes:
forming a layer of reflective medium over side surfaces of the pixel defining layer;
forming low-refractive-index dielectric layers and high-refractive-index dielectric layers on the reflecting medium in sequence to form an anti-reflection combination film;
and etching the reflection increasing combined film, and etching the outer surface of the high-refractive-index dielectric layer positioned on the outermost layer in the reflection increasing combined film to the outer surface of the low-refractive-index dielectric layer positioned on the outermost layer to form a light-transmitting slit which penetrates through at least part of the reflection increasing combined film.
In this example, when the light-transmitting slit does not penetrate through the reflection increasing combination film, the reflection medium and the part of the reflection increasing combination film, which is located below the light-transmitting slit and is not provided with the light-transmitting slit, together form the reflection structure; when the light-transmitting slit penetrates through the reflection-increasing combined film, the reflecting medium forms a reflecting structure.
In the first step, after the substrate is cleaned, the substrate is dried by nitrogen, dried at 50-80 ℃, and irradiated by an ultraviolet ozone machine for 5-10 min to make the substrate hydrophilic; and then forming a pixel definition mother layer on the substrate, and forming a pixel pit corresponding to the preset position of each light-emitting unit by adopting an etching or plasma bombardment mode and the like.
In the second step, the low refractive index medium layer and the high refractive index medium layer may be formed by, but not limited to, an atomic layer deposition method, a magnetron sputtering method, a vacuum evaporation method, and the like.
Preferably, before forming the first low refractive index medium layer or the reflective medium, a step of irradiating the side surface of the pixel defining layer with an ultraviolet ozone machine or the like for a period of time, for example, for 50s to 120s, to make the side surface of the pixel defining layer hydrophilic is further included, so as to facilitate deposition of the low refractive index medium layer or the reflective structure.
The etching manner of the light-transmitting slit may be, but is not limited to, laser etching or wet etching.
The materials or related parameters of the various structural layers in the fabrication method are the same as those of the electroluminescent device 10. The manufacturing method is simple in principle, uncomplicated in manufacturing process and capable of being widely popularized and used.
Through experimental comparison, the electroluminescent device 10 having the reflection-enhanced film grating structure 100 is compared with a conventional electroluminescent device without the reflection-enhanced film grating structure 100. In a specific embodiment, the side reflection increasing film can reflect at least 90% of side light back to the inside of the device, and at least 80% of reflected light reflected by the reflection structure and at the same time, two adjacent light beams are subjected to constructive formation to form bright stripes, so that the reflected light of the whole reflection increasing film grating structure is enhanced.
All possible combinations of the technical features of the above embodiments may not be described for the sake of brevity, but should be considered as within the scope of the present disclosure as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (17)
1. The reflection-enhanced film grating structure is characterized by comprising a high-refractive-index medium layer and a low-refractive-index medium layer which are sequentially stacked, wherein the number of the high-refractive-index medium layers is the same as that of the low-refractive-index medium layers, the high-refractive-index medium layers and the low-refractive-index medium layers are alternately arranged to form a reflection-enhanced combined film, and the refractive index of the low-refractive-index medium layers is smaller than that of the high-refractive-index medium layers which are in contact with the low-refractive-index medium layers;
the reflection-increasing combined film is provided with a plurality of light-transmitting slits, and the reflection-increasing film grating structure is provided with a reflection structure below the light-transmitting slits; wherein the content of the first and second substances,
the light-transmitting slit penetrates through the whole antireflection combined film from the outer surface of one side of the antireflection combined film to the outer surface of the other side of the antireflection combined film; the reflection increasing film grating structure also comprises a layer of reflection medium positioned on the outer surface of the low refractive index medium layer at the outermost layer of the reflection increasing combined film, and the reflection structure is formed by the layer of reflection medium; or the like, or, alternatively,
the light-transmitting slit penetrates through part of the reflection-increasing combined film, the reflection-increasing film grating structure further comprises a layer of reflection medium located on the outer surface of the low-refractive-index medium layer on the outermost layer of the reflection-increasing combined film, and the reflection medium and the part, located below the light-transmitting slit, of the reflection-increasing combined film and not provided with the light-transmitting slit jointly form the reflection structure.
2. The reflection-enhanced film grating structure of claim 1, wherein the high refractive index medium layer and the low refractive index medium layer each have a plurality of layers;
the refractive indexes of the high refractive index medium layers positioned on different layers are the same or different, and/or the refractive indexes of the low refractive index medium layers positioned on different layers are the same or different.
3. The reflection-enhanced film grating structure of claim 2, wherein the refractive index of each of the low-refractive-index medium layers is less than the refractive index of each of the high-refractive-index medium layers.
4. The reflection-enhanced film grating structure of any one of claims 1 to 3, wherein the degree of the included angle between the light-transmitting slit and the thickness direction of the reflection-enhanced combined film is 0 to 60 °.
5. The reflection-enhanced film grating structure according to any one of claims 1 to 3, wherein the grating constant of the light-transmitting slit is 3 μm to 20 μm.
6. The reflection-enhanced film grating structure according to any one of claims 1 to 3, wherein the thicknesses d of the high refractive index medium layer and the low refractive index medium layer and the wavelength λ of incident light satisfy:
2nd+λ/2＝kλ
n is the refractive index of the corresponding dielectric layer, and k is a positive integer.
7. An electroluminescent device is characterized by comprising a substrate, a bottom electrode layer, a pixel defining layer, a light emitting unit, a top electrode layer and an anti-reflection film grating structure, wherein the bottom electrode layer, the pixel defining layer, the light emitting unit, the top electrode layer and the anti-reflection film grating structure are arranged on the substrate, the pixel defining layer is arranged around the bottom electrode layer and forms a pixel pit corresponding to the bottom electrode layer, the light emitting unit is arranged in the pixel pit and is arranged on the bottom electrode layer, the top electrode layer is arranged on the light emitting unit, the anti-reflection film grating structure is arranged in the pixel pit and is arranged on the side surface of the pixel defining layer, and a high-refractive-index medium layer on the outermost layer is close to the light emitting unit in the pixel pit;
the reflection increasing film grating structure comprises a high-refractive-index medium layer and a low-refractive-index medium layer which are sequentially stacked, the number of the high-refractive-index medium layers is the same as that of the low-refractive-index medium layers, the high-refractive-index medium layers and the low-refractive-index medium layers are alternately arranged to form a reflection increasing combined film, and the refractive index of the low-refractive-index medium layers is smaller than that of the high-refractive-index medium layers which are in contact with the low-refractive-index medium layers;
the reflection-increasing combined film is provided with a plurality of light-transmitting slits, the light-transmitting slits extend from the outer surface of the high-refractive-index medium layer positioned on the outermost layer to the outer surface of the low-refractive-index medium layer positioned on the outermost layer in the reflection-increasing combined film so as to at least penetrate through part of the reflection-increasing combined film, and the reflection-increasing film grating structure is provided with a reflection structure below the light-transmitting slits.
8. The electroluminescent device according to claim 7, wherein the light-transmitting slits penetrate through a portion of the reflection-enhanced combined film, and a portion of the reflection-enhanced combined film, which is located below the light-transmitting slits and is not provided with the light-transmitting slits, constitutes the reflective structure; or alternatively
The light-transmitting slit penetrates through part of the reflection-increasing combined film, the reflection-increasing film grating structure further comprises a layer of reflection medium located on the outer surface of the low-refractive-index medium layer on the outermost layer of the reflection-increasing combined film, and the reflection medium and the part, located below the light-transmitting slit, of the reflection-increasing combined film and not provided with the light-transmitting slit jointly form the reflection structure.
9. The electroluminescent device of claim 7, wherein the light-transmitting slit extends through the entire anti-reflection combined film from the outer surface of one side of the anti-reflection combined film to the outer surface of the other side thereof;
the reflection increasing film grating structure also comprises a layer of reflection medium positioned on the outer surface of the low refractive index medium layer at the outermost layer of the reflection increasing combined film, and the reflection structure is formed by the layer of reflection medium.
10. The electroluminescent device according to any of claims 7 to 9, characterized in that the high refractive index medium layer and the low refractive index medium layer each have a plurality of layers;
the high refractive index medium layers located in different layers have the same or different refractive indexes, and/or the low refractive index medium layers located in different layers have the same or different refractive indexes.
11. The device of claim 10, wherein the low index dielectric layers each have a refractive index less than the refractive index of the high index dielectric layers.
12. An electroluminescent device according to any one of claims 7 to 9 and 11, wherein the degree of the angle between the light-transmitting slit and the thickness direction of the anti-reflection combined film is 0 to 60 °.
13. An electroluminescent device as claimed in any one of claims 7 to 9 and 11, characterized in that the grating constant of the light-transmitting slits is between 3 μm and 20 μm.
14. An electroluminescent device as claimed in any one of claims 7 to 9 and 11, characterized in that the thickness d of the high-refractive-index dielectric layer and the low-refractive-index dielectric layer satisfies, with the wavelength λ of the incident light:
2nd+λ/2＝kλ
n is the refractive index of the corresponding dielectric layer, and k is a positive integer.
15. A method for manufacturing an electroluminescent device is characterized by comprising the following steps:
manufacturing a pixel defining layer on a substrate, wherein pixel pits are formed on the pixel defining layer corresponding to preset positions of all light-emitting units;
fabricating an enhanced reflection film grating structure having the following structure within the pixel pits and on a side surface of the pixel defining layer: the reflection-enhanced film grating solution structure comprises a high-refractive-index medium layer and a low-refractive-index medium layer which are sequentially stacked, the high-refractive-index medium layer and the low-refractive-index medium layer are the same in number, the high-refractive-index medium layer and the low-refractive-index medium layer are alternately arranged to form a reflection-enhanced combined film, the refractive index of the low-refractive-index medium layer is smaller than that of the high-refractive-index medium layer in contact with the low-refractive-index medium layer, the low-refractive-index medium layer on the outermost layer in the reflection-enhanced combined film is close to the side surface, a plurality of light-transmitting slits are arranged in the reflection-enhanced combined film, the light-transmitting slits extend from the outer surface of the high-refractive-index medium layer on the outermost layer in the reflection-enhanced combined film to the outer surface of the low-refractive-index medium layer on the outermost layer in order to at least penetrate through part of the reflection-enhanced combined film, and the reflection-enhanced film grating structure is provided with a reflection structure below the light-transmitting slits;
and sequentially forming a bottom electrode layer, a light-emitting unit and a top electrode layer in the pixel pit.
16. The method of fabricating an electroluminescent device of claim 15, wherein the step of fabricating the reflection-enhanced film grating structure comprises:
forming a low-refractive-index dielectric layer and a high-refractive-index dielectric layer on the side surface of the pixel defining layer in sequence to form the anti-reflection combination film;
and etching the reflection increasing combined film, and etching the outer surface of the high-refractive-index medium layer positioned on the outermost layer in the reflection increasing combined film to the outer surface of the low-refractive-index medium layer positioned on the outermost layer to form a light-transmitting slit penetrating through part of the reflection increasing combined film.
17. The method of fabricating an electroluminescent device of claim 15, wherein the step of fabricating the reflection-enhanced film grating structure comprises:
forming a layer of reflective medium over side surfaces of the pixel defining layer;
forming a low-refractive-index dielectric layer and a high-refractive-index dielectric layer on the reflecting medium in sequence to form the reflection increasing combined film;
and etching the reflection-enhanced combined film, and etching the outer surface of the high-refractive-index dielectric layer positioned on the outermost layer in the reflection-enhanced combined film to the outer surface of the low-refractive-index dielectric layer positioned on the outermost layer to form a light-transmitting slit which penetrates through at least part of the reflection-enhanced combined film.
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