KR102084703B1 - Car lamp using semiconductor light emitting device - Google Patents

Abstract

The present invention includes a light source unit including a plurality of semiconductor light emitting devices, formed in a plane shape, having a light emitting area for emitting light and a non-light emitting area formed at an edge of the light emitting area, and overlapping the light emitting area with a predetermined wavelength band. The filter unit for transmitting only light, and the light emitting region of the light source unit is composed of a plurality of areas, and at least one of the plurality of areas provides a vehicle lamp, characterized in that made to selectively emit light.

Description

Car Lamp Using Semiconductor Light-Emitting Device {CAR LAMP USING SEMICONDUCTOR LIGHT EMITTING DEVICE}

The present invention relates to a vehicle lamp, and more particularly, to a vehicle lamp using a semiconductor light emitting element.

The vehicle is equipped with various vehicle lamps having an illumination function and a signal function. In general, halogen lamps or gas discharge lamps have been mainly used, but in recent years, light emitting diodes (LEDs) have attracted attention as light sources of vehicle lamps.

In the case of a light emitting diode, the size of the light emitting diode is minimized to increase the degree of freedom of design of the lamp and the economical efficiency is due to the semi-permanent life, but most of the light emitting diode is produced in a package form. A light emitting diode (LED) itself, not a package, is a semiconductor light emitting device that converts current into light, and is being developed as a light source for display images of electronic devices including information communication devices.

However, vehicle lamps developed to date use light emitting diodes in the form of packages, and thus have a weak point of mass production yield and high cost, and a weak degree of flexibility.

An object of the present invention is to minimize the thickness of the vehicle lamp, and to minimize the lamp structure that can maximize the amount of light.

In addition, an object of the present invention is to enable a plurality of lamp functions through one light source unit.

In addition, an object of the present invention is to provide a vehicle lamp using a flexible light source.

In order to achieve the above object, the present invention includes a plurality of semiconductor light emitting device, a light source having a surface shape, and having a light emitting area for emitting light and a non-light emitting area formed on the edge of the light emitting area, The filter unit which overlaps the light emitting area and transmits only light of a predetermined wavelength band, and the light emitting area of the light source unit includes a plurality of areas, and at least one of the plurality of areas provides a vehicle lamp.

In example embodiments, a non-light emitting area in which no light is emitted may be formed at an edge of each of the plurality of areas, and the light blocking part may be disposed at an edge of each of the areas.

The filter unit may include a first filter unit overlapping with any one of the plurality of regions and transmitting only light of a predetermined wavelength band, and only light of a wavelength band overlapping with a region different from any one of the plurality of regions and different from light of the predetermined wavelength band. It may include a second filter unit for transmitting.

In example embodiments, the first and second filter parts may be disposed on the same plane, and the light blocking part may be stacked on the first and second filter parts.

In example embodiments, the light blocking part may be disposed to overlap a portion of the first and second filter parts.

In example embodiments, the first and second filter parts and the light blocking part may be disposed on the same plane.

In example embodiments, the width of the light blocking portion may be wider as the light blocking portion approaches the light source unit.

In one embodiment, the light source unit may be made to be bent.

In an embodiment, the vehicle lamp according to the present invention may further include a light transmitting layer formed to overlap the first and second light emitting regions and bendable.

In one embodiment, an uneven portion may be formed in the light transmitting layer so that the traveling direction of the light changes.

In example embodiments, each of the plurality of emission areas emits white light, the first filter part transmits red light, and the second filter part transmits yellow light.

In one embodiment, at least one of the plurality of light emitting regions may not overlap the filter unit so that white light is emitted to the outside.

In an embodiment, the vehicle lamp according to the present invention may further include a heat dissipation layer disposed under the light source unit.

In one embodiment, the vehicle lamp according to the invention further comprises a lens unit disposed on the upper side of the light source unit,

In some embodiments, a light blocking area that absorbs light may be formed in a portion of the lens unit.

In example embodiments, the light emitting area may include a plurality of light emitting devices in which a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are sequentially stacked.

In one embodiment, the vehicle lamp according to the present invention may further include a charge generating layer disposed between the plurality of light emitting devices, the upper surface is in contact with the hole injection layer, the lower surface is in contact with the electron injection layer.

In example embodiments, the refractive index of the charge generation layer may be between the refractive index of the hole injection layer and the refractive index of the charge injection layer.

According to the present invention, it is possible to implement a lamp by laminating two or three sheets with each other, and thus the thickness of the lamp can be reduced.

In addition, according to the present invention, light of a plurality of different colors may be emitted from one light source unit. Through this, the present invention can implement a plurality of lamp functions with one light source unit.

In addition, according to the present invention, the light amount of the lamp can be increased because a light emitting device in which a plurality of unit devices including a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are stacked is used.

1 is a conceptual diagram illustrating an embodiment of a vehicle lamp using the semiconductor light emitting device of the present invention.
2 is a conceptual diagram illustrating a cross section of a light source unit according to the present invention.
3 is a plan view of a light source unit according to the present invention.
4 and 5 are cross-sectional views briefly illustrating part A of FIG. 1.
6 is a conceptual diagram illustrating various modified embodiments of a vehicle lamp according to the present invention.
7 is a cross-sectional view of a vehicle lamp including a lens having a light blocking area.
8 is a cross-sectional view of a vehicle lamp including a curved lens.
9 is a cross-sectional view of a vehicle lamp including a pattern portion.
10 is a cross-sectional view of a vehicle lamp with an adhesive layer.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, and the same or similar components will be given the same reference numerals regardless of the reference numerals, and redundant description thereof will be omitted. The suffixes "module" and "unit" for components used in the following description are given or mixed in consideration of ease of specification, and do not have distinct meanings or roles. In addition, in the following description of the embodiments disclosed herein, when it is determined that the detailed description of the related known technology may obscure the gist of the embodiments disclosed herein, the detailed description thereof will be omitted. In addition, it should be noted that the accompanying drawings are only for easily understanding the exemplary embodiments disclosed herein and are not to be construed as limiting the technical spirit disclosed in the present specification by the accompanying drawings.

Also, when an element such as a layer, region or substrate is referred to as being on another component "on", it is to be understood that it may be directly on another element or there may be an intermediate element in between. There will be.

Vehicle lamps described herein may include headlights (headlamps), taillights, vehicle lights, fog lights, turn signals, brake lights, emergency lights, reversing lights (tail lamps), and the like. However, it will be readily apparent to those skilled in the art that the configuration according to the embodiments described herein may be applied to a device including a luminaire even if a new product form is developed later.

1 is a conceptual diagram illustrating an embodiment of a vehicle lamp according to the present invention.

The vehicle lamp 10 according to the exemplary embodiment of the present invention includes a frame 11 fixed to a vehicle body and a light source unit 12 installed on the frame 11.

The frame 11 is connected to a wiring line for supplying power to the light source 12, and the frame 11 may be directly fastened to the vehicle body or fixed through a bracket. According to the illustration, a lens unit may be provided to more diffuse and clarify the light emitted from the light source unit 12.

The light source unit 12 may be a flexible light source unit that can be bent, twisted, folded, or rolled, which can be bent by an external force.

In a state where the light source unit 12 is not bent (for example, a state having an infinite curvature radius, hereinafter referred to as a first state), the light source unit 12 becomes a plane. In the first state bent by an external force (for example, a state having a finite radius of curvature, hereinafter referred to as a second state), the flexible light source unit may be a curved surface at least partially bent or curved.

The pixel of the light source unit 12 may be implemented by an organic light emitting device. In the present invention, a light emitting diode (LED) is exemplified as a type of semiconductor light emitting device that converts current into light. The light emitting diode is formed in a small size, thereby enabling it to serve as a pixel even in the second state.

The light source unit 12 may be formed of only the unit light source. Hereinafter, the unit light source will be described in detail through the light source unit 12 including only the unit light source. In the present specification, a structure of the light source unit 12 having a planar shape will be described for convenience of description, but the light source unit 12 according to the present invention may include a curved area.

2 is a conceptual view showing a cross section of the light source unit according to the present invention, FIG. 3 is a plan view of the light source unit according to the present invention, and FIGS. 4 and 5 are cross-sectional views schematically illustrating part A of FIG.

The vehicle lamp according to the present invention includes a light source unit and a filter unit, and the light emitting area of the light source unit includes a plurality of areas, and at least one of the plurality of areas is selectively emitted. Hereinafter, a vehicle lamp including the above-described components will be described in detail.

2 and 3, the light source unit includes a plurality of semiconductor light emitting devices and has a planar shape. In this case, the light emitting surface of the semiconductor light emitting device does not necessarily have to cover the entire surface. Although the light emitting surfaces of the plurality of semiconductor light emitting elements are arranged at regular intervals, when the user recognizes the entire lamp as a surface, the semiconductor light emitting devices may be a light source unit having a surface shape.

Meanwhile, the light source unit 110 includes a light emitting region 111 emitting light and a non-light emitting region 112 formed at an edge of the light emitting region.

A plurality of semiconductor light emitting devices are disposed in the light emitting region 111. The light emitting area may be switched from one of the first state emitting light to the second state not emitting light to the other. Lighting of the plurality of light emitting regions 111 included in the light source unit 110 may be individually controlled. In this way, the present invention allows each of the light emitting regions 111 included in the light source unit 110 to be utilized as a different function. For example, the present invention enables one of the plurality of light emitting regions to be used as a stop light of a vehicle and the other to be used as a direction indicator. As the number of light emitting regions included in the light source unit increases, functions that can be implemented in a single light source unit may increase.

In the non-light emitting region 112, a wiring electrode for applying a voltage to each of the semiconductor light emitting devices may be disposed. In order to individually control the plurality of light emitting regions 111, a wiring structure may be complicated, and the wiring is disposed in the non-light emitting region 112.

Meanwhile, referring to FIG. 2, the light source unit 110 is supported by the bracket 130. In addition, the bracket 130 is supported by the housing 150. One surface of the housing 150 is covered with the lens 140.

The bracket 130 and the light source unit 110 may be coupled through an adhesive, or may be coupled in a slide or hook manner.

Meanwhile, an air gap may be formed between the bracket 130 and the light source unit 110, or a heat dissipation layer may be disposed. The bracket 130 is fixed to the housing 150 while supporting the light source unit 110. However, the present invention is not limited thereto, and the light source unit 110 may be directly fixed to the housing 150 without the bracket 130.

The bracket 130 or the housing 150 is not an essential component of the lamp according to the present invention, but may be used to facilitate assembly of the lamp or to form an appearance of the lamp.

On the other hand, the lens 140 collects the light emitted from the light source unit 110 in a specific direction, or serves to block some of the light emitted from the light source unit 110. This will be described later.

Meanwhile, the filter unit and the light shielding unit to be described later may be supported by the bracket 130 together with the light source unit 110 or may be fixed to the housing 150. Hereinafter, a description of the coupling relationship between the filter unit or the light blocking unit and the bracket 130 or the housing 150 will be omitted.

4 and 5, the filter unit 120 overlaps the emission area to transmit only light of a predetermined wavelength band. Depending on the function to be implemented in the vehicle lamp, the color to be emitted from the lamp may vary. For example, stop lights should emit red light, and turn signals should emit yellow light. When implementing a different function in each of the plurality of light emitting regions, light of different colors should be emitted to the outside for each light emitting region.

The filter unit 120 allows light of different colors to be emitted from each of the plurality of light emitting regions. Specifically, the filter unit 120 includes a first filter unit overlapping any one of the plurality of regions and transmitting only light of a predetermined wavelength band, and a region different from the light of the predetermined wavelength band and overlapping with a region different from any one of the plurality of regions. It may include a second filter unit for transmitting only light. As a result, the present invention may allow light of different colors to be emitted from each of the plurality of light emitting regions.

In one embodiment, white light may be emitted from all the light emitting regions 111 of the light source unit 110, the first filter unit may transmit red light, and the second filter unit may transmit yellow light. . In some embodiments, some of the emission regions 111 may not overlap with the filter unit 120. Accordingly, the white light emitted from the emission region 111 may be emitted to the outside as it is. Through this, the present invention can realize white light, red light, yellow light through one light source unit.

The light source unit 110 including the light emitting region 111 and the non-light emitting region 112 has a planar shape, and since the thickness thereof is very thin, it is easy to arrange in a narrow space. However, since the non-light emitting region 112 is made of distribution electrodes, when exposed to the outside, the aesthetics of the lamp may be damaged. The present invention provides a structure for preventing the non-light emitting area 112 from damaging the aesthetics of the lamp.

To this end, the lamp according to the invention further comprises a light shield. The light blocking portion absorbs light so as not to be emitted to the outside. The light blocking unit may be formed in a sheet form, and because the light blocking unit is configured to absorb light, the light emitted from the light emitting region 111 overlapping with the light blocking unit is not emitted to the outside.

The light blocking part is disposed to overlap with the non-light emitting area in which light is not emitted. The non-light emitting area 111 is not exposed to the outside due to the light blocking part.

In an embodiment, a non-light emitting area 112 may be formed on the edge of each of the plurality of light emitting areas 111, and the light blocking unit 170 is disposed at the edge of each of the areas. Thus, the non-light emitting area may not be exposed to the outside.

The light blocking part may be disposed on a layer different from the filter part. Alternatively, the light blocking part may be disposed on the same plane as the filter part.

First, an embodiment in which the light blocking part and the filter part are disposed on different planes will be described with reference to FIG. 4. The first and second filter units are disposed on the light source unit 110. The first and second filter parts may be disposed on the same plane, and a separate structure may not be formed between the first and second filter parts. The first and second filter units may form a sheet.

In this case, light leakage may occur at the interface between the first and second filter units. For example, when any one of the plurality of light emitting regions overlaps with the first filter unit, and one and the other are overlapped with the second filter unit, a part of the light emitted from any one of the plurality of light emitting regions may be formed. 2 may be emitted to the outside through the filter unit. In this case, light of unwanted color may be emitted from the vehicle lamp.

In order to prevent this, the lamp according to the present invention may further include a light blocking unit 170. The light blocking unit 170 may include a light blocking area 171 and a light transmitting area 172. The light blocking area 171 is disposed at the boundary between the first and second filter parts to prevent light leakage occurring at the boundary surface of the filter part, and overlaps with a portion of the first and second filter parts. The light transmitting region 172 and the light blocking region 171 may be disposed on the same plane to form a sheet. The light transmitting region 172 is not an essential configuration of the light blocking unit 170, but increases the contact area between the light blocking unit 170 and the filter unit 120 to prevent the light blocking unit 170 from being separated from the filter unit 120. It serves to prevent, and serves to prevent the surface of the filter unit 120 is damaged.

Next, the structure in which the filter part 120 and the light shielding part are arrange | positioned on the same plane is demonstrated with reference to FIG.

The first and second filter parts 121 and the light blocking part 122 may be disposed on the same plane. That is, both the first and second filter units 121 and the light blocking unit 122 may be disposed on the light source unit 110. In this case, the filter portion and the light shielding portion form one sheet. The light blocking unit is disposed between the first and second filter units to block light leakage generated at an interface between the first and second filter units.

Hereinafter, various modified embodiments of the lamp according to the present invention will be described.

6 is a conceptual diagram illustrating various modified embodiments of a vehicle lamp according to the present invention.

In FIG. 6, the above-described bracket 130, the housing 150, and the lens 140 are not shown. However, this is merely omitted for convenience of description, and the lamp 130 described above may have the bracket 130 described above. At least one of the housing 150 and the lens 140 may be included.

Referring to FIG. 6A, a light blocking part 122 may be disposed between different types of filter parts 121a to 121d. Here, different kinds of filter parts 121a to 121d and light blocking parts 122 may be disposed on the same plane and form a sheet.

In addition, referring to FIG. 6B, the light blocking portion may be disposed to overlap the non-light emitting region 112, and may be disposed not to overlap the light emitting region 111 to minimize light loss. The emission regions 111 overlap with each of the different filter units 121a to 121d.

On the other hand, the light source unit 110 may be made to be bent. In detail, when the organic light emitting diode is disposed in the light emitting region of the light source unit 110, the light source unit 110 may be bent. This allows the design of the lamp to be free.

When a part of the light source unit 110 is formed to be bent, as shown in FIGS. 6C and 6D, the lamp according to the present invention overlaps the light emitting regions and is bent to allow light transmission. It may further comprise layers 123 and 160.

The light transmitting layers 123 and 160 protect the light source unit 110 and serve to uniformly emit light from the curved light source. The light transmitting layers 123 and 160 may be disposed to overlap the light source unit 110 as a separate layer.

On the other hand, the light transmitting layer may be formed as a partial region of the light shielding portion, not a separate layer. That is, the light transmitting area included in the light blocking part may serve as the light transmitting layer described above. In the present specification, the light transmitting layer and the light transmitting region are described as the same components.

On the other hand, when the light source is formed in a convexly curved form toward the outside, the light is spread widely. In this case, the lamp including the light source unit may not collect light in a specific area and thus may not provide sufficient visibility to the driver. In order to prevent this, the present invention may further include an uneven portion formed in the light transmitting layer.

Specifically, the light transmitting layer may be formed with an uneven portion so that the traveling direction of the light changes. The uneven portion serves to concentrate the light emitted from the curved light source to a point. Through this, the present invention can concentrate the light in a specific area even when using a curved light source.

Meanwhile, referring to FIG. 6E, the width of the light blocking part may be wider as the light source is closer to the light source, and may be narrower as it is farther from the light source. Through this, the light shielding portion may minimize the area covering the light source unit to maximize the light emitting area.

In example embodiments, the light blocking part may be formed of a material having high reflectance. Specifically, the light blocking part may be made of a metal material having a high reflectance, or a coating layer having a high reflectance may be formed on a surface of the light blocking part. In this case, the light blocking unit reflects the light traveling toward the side of the filter unit and emits the light to the outside. Through this, the present invention can increase the amount of light of the lamp.

Meanwhile, the lens 140 included in the vehicle lamp according to the present invention may be implemented in various forms. Hereinafter, various modified embodiments of the lens provided in the vehicle lamp according to the present invention will be described.

7 is a cross-sectional view of a vehicle lamp including a lens having a light blocking area, FIG. 8 is a cross-sectional view of a vehicle lamp including a curved lens, and FIG. 9 is a cross-sectional view of a vehicle lamp including a pattern portion.

The lens included in the lamp according to the present invention may block some of the light emitted from the light emitting area. Specifically, referring to FIG. 7, the lens 140 included in the vehicle lamp according to the present invention includes a light transmitting area 141 and a light blocking area 142. The illumination pattern may vary according to the pattern of the light blocking region 142 formed in the lens 140. The present invention can increase the degree of freedom of design by forming the light shielding region 142 on the lens 140.

Meanwhile, the lens included in the vehicle lamp according to the present invention may include a curved area. Specifically, referring to FIG. 8, the curved area formed on the lens 140 ′ allows the illumination pattern of the lamp to be seen in three dimensions. Through this, the present invention can realize a three-dimensional lighting effect even if a plurality of light emitting regions are arranged on the same plane.

Meanwhile, referring to FIG. 9, the lens included in the vehicle lamp according to the present invention may include a pattern portion 141. Specifically, the pattern portion 141 included in the lens 140 plays a role similar to that of the uneven portion formed in the light transmitting layer. The pattern part 141 serves to condense the light emitted from the emission area in a specific direction. In addition, a three-dimensional lighting effect may be implemented according to the shape of the pattern portion 141.

The auxiliary light source 173 may be disposed on the light blocking area 171 of the light blocking unit 170. The auxiliary light source 173 increases the amount of light directed in a specific direction so that the lamp can satisfy the light distribution law.

On the other hand, the light source unit provided in the vehicle lamp according to the present invention can be directly coupled to the housing without a bracket.

10 is a cross-sectional view of a vehicle lamp with an adhesive layer.

As shown in FIG. 10, the light source unit 110 may be coupled to the housing 150 through an adhesive. In this case, an adhesive layer 180 is formed between the light source unit 110 and the housing 150. The thickness of the lamp may be thinner because the structure of FIG. 10 does not use a bracket.

On the other hand, the lamp according to the present invention provides a structure for increasing the light amount of the lamp. Specifically, the organic light emitting device used in the lamp according to the present invention has a structure in which a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer and an electron injection layer are sequentially stacked.

However, the light emitting device including each of the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer, and the electron injection layer is not large in quantity, and thus a lamp using the same does not satisfy the light distribution law.

The present invention uses a device in which a plurality of unit devices in which a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are stacked in this order is used to increase the light amount of the lamp. Specifically, the organic light emitting device according to the present invention uses a light emitting device in which two or three unit devices are stacked.

Meanwhile, in order to maximize the luminous efficiency of each of the unit devices, a charge generation layer may be disposed between the unit devices. The charge generating layer is in contact with the hole injection layer of the unit device disposed above and the electron injection layer of the unit device disposed below. That is, the upper surface of the charge generating layer is in contact with the hole injection layer, and the lower surface is in contact with the electron injection layer.

When the unit elements are stacked in the above-described structure, the light extraction efficiency of the unit elements disposed on the lower side is inevitably lower than the light extraction efficiency of the unit elements disposed on the upper side.

The present invention provides a refractive index of the hole injection layer in which the charge generation layer is in contact with the top surface of the charge generation layer and a refractive index of the electron injection layer in contact with the bottom surface of the charge generation layer in order to increase light extraction efficiency of the unit device disposed on the lower side. Have a refractive index between. In this way, the present invention prevents the light emitted from the unit elements disposed on the lower side from being totally reflected in the charge generation layer.

It is apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential features of the present invention.

In addition, the above detailed description should not be interpreted as limiting in all aspects and should be considered as illustrative. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

Claims (17)

A light source unit including a plurality of semiconductor light emitting devices, the light source unit having a planar shape, and having a light emitting area for emitting light and a non-light emitting area formed at an edge of the light emitting area;
A filter unit overlapping the emission area to transmit only light of a predetermined wavelength band;
The light emitting area of the light source unit is
Consists of multiple areas,
At least one of the plurality of regions is made to selectively emit light,
A non-light emitting area in which no light is emitted is formed at an edge of each of the plurality of areas,
Further comprising a light blocking unit disposed on the edge of each of the areas,
The filter unit,
A first filter unit overlapping any one of the plurality of regions and transmitting only light of a predetermined wavelength band; And
A second filter unit overlapping with the other region different from the one and transmitting only light of the predetermined wavelength band and light of a different wavelength band,
The first and second filter parts are disposed on the same plane,
In the form of a single sheet,
The light shielding portion,
Disposed on the boundary of the first and second filter units,
It is disposed to overlap with part of the first and second filter portion,
Vehicle lamp, characterized in that formed in one sheet form. delete delete delete delete delete The method of claim 1,
The width of the light shielding portion,
The vehicle lamp, characterized in that the wider the closer to the light source. The method of claim 1,
Vehicle lamp, characterized in that the light source is made to be bent. The method of claim 8,
The lamp of claim 1, further comprising a light transmitting layer formed to overlap the first and second light emitting regions, the light transmitting layer being bendable. The method of claim 9,
The light transmitting layer is a vehicle lamp, characterized in that the uneven portion is formed so that the traveling direction of the light changes. The method of claim 1,
Each of the plurality of emission areas emits white light,
The first filter unit transmits red light,
The second filter unit is a vehicle lamp, characterized in that the transmission of yellow light. The method of claim 11,
At least one of the plurality of light emitting regions,
A vehicle lamp, characterized in that it does not overlap with the filter unit so that white light is emitted to the outside. The method of claim 1,
Vehicle lamp further comprises a heat dissipation layer disposed under the light source. The method of claim 1,
Further comprising a lens unit disposed above the light source unit,
The light shielding area for absorbing light is formed in a portion of the lens unit. The method of claim 1,
The light emitting area,
A vehicle lamp comprising a plurality of light emitting elements in which a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are stacked in this order. The method of claim 15,
And a charge generating layer disposed between the plurality of light emitting devices, the upper surface of the light emitting layer being in contact with the hole injection layer, and the lower surface of the light emitting element being in contact with the electron injection layer. The method of claim 16,
The refractive index of the charge generating layer is a vehicle lamp, characterized in that between the refractive index of the hole injection layer and the refractive index of the electron injection layer.

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