TW201608741A - Illuminating device - Google Patents

Abstract

The present invention provides a light-emitting device that is less susceptible to thermal degradation. The light-emitting device 1 includes a light-emitting unit 30 and a light source 20 . The light emitting unit 30 includes quantum dots. The light source 20 emits light of an excitation wavelength of the quantum dot to the light-emitting portion 30. Among the light sources 20, the light-emitting intensity of the portion 20a opposite to the light-emitting portion 30 is higher than the light-emitting intensity of the portion of the light-emitting portion side 20b.

Description

Illuminating device

The present invention relates to a light emitting device.

In recent years, the improvement of the light-emitting device using the light-emitting diode has been remarkable, and it has been used for a backlight of a liquid crystal, a large display, or the like. In particular, since the short-wavelength light is gradually obtained by the development of the semiconductor material of the light-emitting element of short-wavelength light, the short-wavelength light can be used to excite the phosphor to obtain more wavelengths of light.

Light-emitting devices using quantum dots have been known since the prior art. For example, Patent Document 1 discloses a light-emitting device including a blue LED (light emitting diode) and a sealing portion for sealing a blue LED, and the sealing portion is made of a resin composition containing quantum dots. Composition.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2010-126596

However, the light-emitting surface of the blue LED of the light-emitting device disclosed in Patent Document 1 is in contact with a sealing portion including quantum dots which are easily deteriorated by heat. Further, the blue LED and the substrate on which the electrodes are arranged are connected via a bonding wire. Therefore, there is a problem in that the quantum dots of the sealing portion which is in contact with the light-emitting surface or the bonding wire of the blue LED are deteriorated by the heat generated when the blue LED emits light, and the luminous intensity and the like are lowered.

SUMMARY OF THE INVENTION A primary object of the present invention is to provide a light-emitting device that is less susceptible to thermal degradation.

A light-emitting device according to the present invention includes a light-emitting portion including a quantum dot and a light source that emits light of an excitation wavelength of the quantum dot to the light-emitting portion. Among the light sources, a portion of the light-emitting portion opposite to the light-emitting portion has a higher light-emitting intensity than a portion on the light-emitting portion side. Luminous intensity.

The light-emitting device of the present invention may further include a mounting substrate that is disposed on a side opposite to the light source and the light-emitting portion and that has a light source mounted thereon, and the light source is flip-chip mounted on the mounting substrate.

In the light-emitting device of the present invention, the light-emitting portion may be spaced apart from the light source.

The light-emitting device of the present invention may further include a mounting substrate on a side opposite to the light source and the light-emitting portion and having a light source mounted thereon, the mounting substrate having a concave portion in which the light source and the light-emitting portion are housed, and the light-emitting device further includes a cover The cover member of the recessed portion is provided on the surface of the cover member which is the recessed portion of the device.

The light-emitting device of the present invention may further include a unit that is disposed above the light source and that seals the light-emitting portion.

In the light-emitting device of the present invention, the light source may be composed of an LED element.

The light-emitting device of the present invention may further include a mounting substrate on a side opposite to the light source and the light-emitting portion and having a light source mounted thereon, the light-emitting portion further including a dispersion medium of quantum dots, and the thermal conductivity of the dispersion medium is lower than the mounting substrate Thermal conductivity.

According to the present invention, it is possible to provide a light-emitting device which is less susceptible to thermal deterioration.

1‧‧‧Lighting device

1a‧‧‧Lighting device

1b‧‧‧Lighting device

1c‧‧‧Lighting device

10‧‧‧Installation substrate

11‧‧‧1st component

11a, 11b‧‧‧ pads

11c, 11d‧‧‧through hole electrodes

11e, 11f‧‧‧ terminal electrodes

12‧‧‧2nd component

12a‧‧‧through hole

13‧‧‧ recess

13a‧‧‧ Sidewall

13b‧‧‧ bottom wall

20‧‧‧Light source

Section 20a‧‧‧

Section 20b‧‧‧

30‧‧‧Lighting Department

40‧‧‧covering components

40a‧‧‧Internal space

50‧‧‧ sealed space

60‧‧‧ unit

70‧‧‧Resin

Fig. 1 is a schematic cross-sectional view showing a light-emitting device of a first embodiment.

Fig. 2 is a schematic cross-sectional view showing a light-emitting device of a second embodiment.

Fig. 3 is a schematic cross-sectional view showing a light-emitting device of a third embodiment.

Fig. 4 is a schematic cross-sectional view showing a light-emitting device of a fourth embodiment.

Hereinafter, preferred embodiments for carrying out the invention will be described. However, the following embodiments are merely illustrative. The present invention is not limited by the following embodiments.

In the drawings, which are referred to in the embodiments and the like, members having substantially the same functions are referred to by the same reference numerals. Moreover, the drawings referred to in the embodiments and the like are schematically described. The ratio of the size of the object depicted in the drawing and the like may be different from the ratio of the size of the object. In the case of patterns, there are also cases where the size ratio of the objects is different. The specific size ratio of the object should be judged by the following instructions.

(First embodiment)

Fig. 1 is a schematic cross-sectional view of a light-emitting device 1 according to a first embodiment.

The light-emitting device 1 is a device that emits light of a wavelength different from that of the excitation light when the excitation light is incident. The light-emitting device 1 may also be a mixed light that emits excitation light and light generated by irradiation of excitation light.

The light emitting device 1 has a mounting substrate 10. The mounting substrate 10 has a first member 11 that serves as a substrate and a second member 12 that serves as a frame member. The second member 12 is provided on the first member 11. The second member 12 is provided with a through hole 12a that opens to the first member 11. The concave portion 13 is configured by the through hole 12a. Further, the through hole 12a is tapered toward the tip end of the first member 11 side. Therefore, the side wall 13a of the recessed portion 13 is inclined with respect to the main surface of the first member 11.

The mounting substrate 10 can be constructed of any material. The mounting substrate 10 can be made of, for example, ceramic such as low-temperature co-fired ceramic, metal, resin, glass, or the like. The material constituting the first member 11 and the material constituting the second member 12 may be the same or different. When the material constituting the first member 11 is the same as the material constituting the second member 12, since the coefficient of thermal expansion is the same, peeling of the first member 11 and the second member 12 due to heat generated during light emission can be suppressed.

Solder pads 11a and 11b are provided on one surface of the first member 11 of the mounting substrate 10. The pads 11a and 11b are connected to the terminal electrodes 11e and 11f provided on the other surface of the first member 11 by the via electrodes 11c and 11d.

A light source 20 is disposed on the bottom wall 13b of the recess 13 of the mounting substrate 10. The light source 20 is flip-chip mounted on the first member 11 of the mounting substrate 10. Here, the "flip-chip mounting" means that an electronic component is placed on a bonding pad (bump) provided on a mounting surface of a mounting substrate, and an electrode of the electronic component and the pad are joined by a conductive material such as solder. This allows you to install electronic parts. Specifically, in the present embodiment, the light source 20 is placed on the pads 11a and 11b. The electrode of the light source 20 is bonded to the pads 11a and 11b via a conductive material such as solder.

The light source 20 can be configured by, for example, an LED (Light Emitting Diode) element, an LD (Laser Diode) element, or the like. In the present embodiment, an example in which the light source 20 is constituted by an LED element will be described.

The light emitting unit 30 is disposed in the recess 13 . The light emitting unit 30 and the light source 20 are housed in the recess 13 . That is, the light-emitting portion 30 is disposed in the concave portion 13 so that light from the light source 20 is incident. Specifically, the light-emitting portion 30 is disposed on the light source 20 so as to cover the light source 20 .

The light emitting unit 30 includes quantum dots. The light-emitting portion 30 may include one type of quantum dot or a plurality of quantum dots. By containing a plurality of quantum dots, the color tone of the converted light can be made to have a certain range.

The quantum dot system emits light of a wavelength different from the excitation light when the excitation light of the equivalent sub-point is incident. The wavelength of the light emerging from the quantum dots depends on the particle size of the quantum dots. That is, the wavelength of the obtained light can be adjusted by changing the particle diameter of the quantum dot. Therefore, the particle diameter of the quantum dot is set to a particle diameter corresponding to the wavelength of the light to be obtained. The particle size of the quantum dots is usually about 2 nm to 10 nm.

For example, a specific example of a quantum dot which emits blue visible light (fluorescence of a wavelength of 440 nm to 480 nm) when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 nm to 440 nm is exemplified by a particle diameter of about 2.0 nm to 3.0 nm. Crystallites of CdSe/ZnS, etc. As the excitation light of ultraviolet to near-ultraviolet light having a wavelength of 300 nm to 440 nm and the blue excitation light having a wavelength of 440 nm to 480 nm, green visible light is emitted (wavelength is 500 nm to 540 nm). Specific examples of the quantum dots of the fluorescent light include crystallites of CdSe/ZnS having a particle diameter of about 3.0 nm to 3.3 nm. Specific examples of quantum dots that emit yellow visible light (fluorescence with a wavelength of 540 nm to 595 nm) when irradiated with excitation light of ultraviolet to near ultraviolet light having a wavelength of 300 nm to 440 nm and blue light having a wavelength of 440 nm to 480 nm are exemplified. The crystallites of CdSe/ZnS having a diameter of about 3.3 nm to 4.5 nm are used. Specific examples of quantum dots that emit red visible light (fluorescence with a wavelength of 600 nm to 700 nm) when irradiated with excitation light of ultraviolet to near ultraviolet light having a wavelength of 300 nm to 440 nm and blue light having a wavelength of 440 nm to 480 nm are exemplified. The crystallites of CdSe/ZnS having a diameter of about 4.5 nm to 10 nm are used.

The light-emitting portion 30 includes a dispersion medium that disperses quantum dots. The dispersion medium is not particularly limited as long as it can disperse the quantum dots. The dispersion medium may be, for example, a solid such as a resin, or may be a liquid. In the present embodiment, an example in which the dispersion medium is a resin will be described. Specific examples of the resin to be preferably used include, for example, a polyoxyxylene resin, an epoxy resin, and an acrylic resin.

The light-emitting portion 30 may further contain, for example, a light dispersant or the like in addition to the resin and the quantum dot. Specific examples of the light-scattering agent to be used preferably include highly-reflecting inorganic compound particles such as alumina particles, titania particles, and cerium oxide particles, and highly-reflecting white resin particles. As described above, by including the light-scattering agent in the light-emitting portion 30, the in-plane unevenness of the light-emission intensity in the light-emitting portion 11 can be reduced.

The light-emitting portion 30 may be composed of a laminate of a plurality of light-emitting layers. In this case, the plurality of light-emitting layers may include a plurality of light-emitting layers including quantum dots that emit light of mutually different wavelengths. For example, the light-emitting unit 30 can be configured by a laminate including a first light-emitting layer including quantum dots that emit light of the first wavelength and a plurality of light-emitting layers including a second light-emitting layer that emits quantum dots of light having a second wavelength. . By stacking a plurality of light-emitting layers, the color tone of the first light-emitting layer can be measured, and the color tone of the second light-emitting layer can be adjusted in accordance with the obtained color tone, so that uneven color tone between batches can be suppressed.

The light-emitting portion 30 can be filled in the entire concave portion 13, but in the present embodiment, it is provided in One part of the recess 13.

The recess 13 is covered by the cover member 40. The cover member 40 is joined to the mounting substrate 10. The sealed space 50 is defined by the cover member 40 and the mounting substrate 10. The light source 20 and the light emitting portion 30 are sealed in the sealed space 50.

The cover member 40 is preferably made of an inorganic material. Specifically, since the cover member 40 must be translucent, it is preferably made of, for example, glass, ceramics or the like. As described above, by making the lid member 40 an inorganic material, it is possible to suppress entry of oxygen or moisture into the sealed space 50, and thus it is possible to suppress deterioration of quantum dots due to contact with oxygen or moisture.

In the light-emitting device 1, the light source 20 emits light including the excitation wavelength of the quantum dots included in the light-emitting portion 30 to the light-emitting portion 30. When the light from the light source 20 is incident on the light-emitting portion 30, the quantum dots included in the light-emitting portion 30 emit light of a wavelength corresponding to the particle diameter of the quantum dot. The self-luminous device 1 emits light of the quantum dots or mixed light of the quantum dots and light from the light source 20.

In the light-emitting device 1, the first member 11 of the mounting substrate 10 is located on the opposite side of the light source 20 and the light-emitting portion 30. Further, the light source 20 is flip-chip mounted on the first member 11. Therefore, among the light sources 20, the light-emitting intensity of the portion 20a opposite to the light-emitting portion 30 is higher than the light-emitting intensity of the portion 20b on the light-emitting portion 30 side. Thereby, the light-emitting portion 30 including the quantum dots can be isolated from the portion of the light source 20 that is at a high temperature. Moreover, when the light source 20 is flip-chip mounted, it is not necessary to connect the light source 20 and the first member 11 by a bonding wire. As a result, deterioration of the quantum dots contained in the light-emitting portion 30 due to heat generated from the light source 20 or the bonding wires can be suppressed. Therefore, the light-emitting device 1 which is not easily deteriorated thermally can be realized.

When the light-emitting portion 30 is constituted by an element that emits a large amount of heat when the LED element or the LD element emits light, the light source 20 easily reaches a high temperature. Therefore, as the light source 20 emits light, the light-emitting portion 30 is easily deteriorated. Therefore, it is more effective to make the light-emitting intensity of the portion 20a of the light source 20 opposite to the light-emitting portion 30 higher than the light-emitting intensity of the portion 20b on the side of the light-emitting portion 30.

The thermal conductivity of the dispersion medium of the light-emitting portion 30 is preferably lower than the thermal conductivity of the mounting substrate 10, and more preferably the thermal conductivity of the mounting substrate 10, from the viewpoint of more effectively suppressing thermal deterioration of the light-emitting device 1. 0.5 times or less, further preferably 0.25 times or less. This is because the heat of the light source 20 is preferentially transmitted to the side of the mounting substrate 10 and is not easily transmitted to the light-emitting portion 30. Therefore, the quantum dots contained in the light-emitting portion 30 are not easily thermally deteriorated.

As shown in FIG. 1, when the light-emitting device 1b in which the light-emitting portion 30 is provided to cover the light source 20 in the concave portion 13, the light source 20 disposed in the concave portion 13 of the device body 10 is used, and the drop is used. A tube or the like will drip the resin in which the quantum dots (optionally containing a light dispersing agent) are dispersed onto the light source 20. Then, the resin layer is dried in an environment where air or moisture is small to form the light-emitting portion 30. Thereafter, the cover member 40 is placed on the apparatus body 10 to engage the cover member 40 with the apparatus body 10. In this manner, as shown in FIG. 1, the light-emitting device 1 in which the light-emitting portion 30 is provided in the recess 13 so as to cover the light source 20 can be obtained.

Hereinafter, other examples of preferred embodiments of the present invention will be described. In the following description, members having functions substantially the same as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

(Second embodiment)

Fig. 2 is a schematic cross-sectional view showing a light-emitting device 1a according to a second embodiment.

In the light-emitting device 1 of the first embodiment, an example in which the light-emitting portion 30 is provided on the bottom wall 13b of the concave portion 13 so as to cover the light source 20 has been described. However, in the present invention, the position of the light-emitting portion is not particularly limited as long as it is a position at which light from the light source is incident.

As shown in FIG. 2, in the light-emitting device 1a of the second embodiment, the light-emitting portion 30 is provided on the surface of the cover member 40 which is the recess 13 side. The light-emitting portion 30 is provided on substantially the entire surface of the cover member 40 exposed on the concave portion 13. The light emitting unit 30 is spaced apart from the light source 20. A gap is provided between the light emitting unit 30 and the light source 20. Therefore, the heat of the light source 20 is not easily transmitted by the light emitting portion 30. Thereby, the quantum dots contained in the light-emitting portion 30 are not easily thermally deteriorated. Therefore, thermal deterioration of the light-emitting device 1a can be more effectively suppressed.

Further, such a light-emitting portion 30 can be formed, for example, by applying a slurry containing a quantum dot and a resin onto the cover member 40 and drying it.

(Third embodiment)

Fig. 3 is a schematic cross-sectional view showing a light-emitting device 1b according to a third embodiment.

As shown in FIG. 3, in the light-emitting device 1b of the present embodiment, the light-emitting portion 30 is provided above the light source 20 in a unit 60 provided spaced apart from the light source 20. The light emitting portion 30 is sealed in the internal space 40a of the unit 60.

In the light-emitting device 1b, since the light-emitting portion 30 is isolated from the light source 20 by the unit 60, heat transfer from the light source 20 to the light-emitting portion 30 is more effectively suppressed. Therefore, the quantum dots contained in the light-emitting portion 30 are not easily thermally deteriorated. Therefore, the thermal deterioration of the light-emitting device 1b can be further effectively suppressed.

In view of effectively suppressing the heat transfer from the light source 20 to the light-emitting portion 30, it is preferable that the thermal conductivity of the unit 60 is low. The thermal conductivity of the unit 60 is, for example, preferably 30 or less, more preferably 10 or less. The thermal conductivity of unit 60 is typically 1 or greater. The unit 60 may be composed of, for example, glass, ceramic, resin, or the like.

(Fourth embodiment)

Fig. 4 is a schematic cross-sectional view showing a light-emitting device of a fourth embodiment.

In the second embodiment, an example in which the sealed space 50 between the light source 20 and the light-emitting portion 30 is constituted by a space has been described. However, the present invention is not limited to this configuration.

As shown in FIG. 4, in the light-emitting device 1c of the fourth embodiment, the resin 70 is filled in the sealed space 50. In this case, the difference in refractive index between the resin 70 and the light-emitting portion 30 and the difference in refractive index between the resin 70 and the light source 20 can be reduced. Therefore, the light emission efficiency can be improved.

The resin 70 can be composed of, for example, a polyoxyxylene resin, an epoxy resin, an acrylic resin, or the like.

The resin 70 may also contain a light dispersing agent. In this case, the uniformity of light from the light source 20 to the light-emitting portion 30 can be further improved.

As shown in FIG. 4, when the light-emitting device 1c in which the resin 70 is filled in the sealed space 50 is obtained, first, the resin 70 is used by using a dropper or the like so as to cover the light source 20 disposed in the concave portion 13 of the apparatus body 10. (If necessary, a light dispersing agent is included) is dropped onto the light source 20 and dried. Next, a resin which disperses a quantum dot (optionally containing a photo-dispersing agent) is applied to one surface of the lid member 40 and dried to form a resin layer. Thereafter, the cover member 40 is placed on the apparatus body 10 such that the light-emitting portion 30 is housed in the recess 13 of the apparatus body 10, and the cover member 30 is joined to the apparatus body 10. In this manner, as shown in FIG. 4, the light-emitting device 1c filled with the resin 70 in the sealed space 50 can be obtained.

Further, as the resin 70 for filling the sealed space, a resin having a small surface tension or a resin having a large wettability to the second member 12 serving as the frame member is used, whereby the center is more easily obtained when it is dried. The resin layer filling the sealed space 50 is thinner and thicker toward the outside. Further, as a resin for dispersing quantum dots (including a photo-dispersing agent) to be the light-emitting portion 30, a resin having a large surface tension or a resin having a small wettability to the lid member 40 is used, whereby it is more easily obtained. The central portion has a thick resin layer which is gradually reduced in thickness toward the outer side, and is more easily obtained in the light-emitting device 1 in which the thickness of the light-emitting portion 30 of the light-emitting portion 30 is gradually decreased toward the outer side. Further, in the second and fourth embodiments, as a method of forming the light-emitting portion 30 on one surface of the lid member 40, the resin that disperses the quantum dots is applied and the light-emitting portion 30 is formed directly on one surface of the lid member 40. The method has been described, but the present invention is not limited to the method. For example, a resin in which quantum dots are dispersed may be filled in a mold having a desired shape to be formed and dried, whereby the light-emitting portion 30 is formed in advance, and the formed light is formed using an adhesive having a refractive index adjusted. The portion 30 is then on one of the surfaces of the cover member 40. According to this aspect, the light-emitting portion 30 having the same shape can be mass-produced, and unevenness in color tone due to the shape of the thickness of the light-emitting portion or the like can be suppressed.

1‧‧‧Lighting device

10‧‧‧Installation substrate

11‧‧‧1st component

11a, 11b‧‧‧ pads

11c, 11d‧‧‧through hole electrodes

11e, 11f‧‧‧ terminal electrodes

12‧‧‧2nd component

12a‧‧‧through hole

13‧‧‧ recess

13a‧‧‧ Sidewall

13b‧‧‧ bottom wall

20‧‧‧Light source

Section 20a‧‧‧

Section 20b‧‧‧

30‧‧‧Lighting Department

40‧‧‧covering components

50‧‧‧ sealed space

Claims (7)

A light-emitting device comprising: a light-emitting portion including quantum dots; and a light source that emits light of an excitation wavelength of the quantum dot to the light-emitting portion; and a portion of the light source that is opposite to the light-emitting portion The intensity of the light is higher than the portion of the light-emitting portion side. The light-emitting device of claim 1, further comprising a mounting substrate positioned on a side opposite to the light-emitting portion with respect to the light source, and the light source is mounted thereon, and the light source is flip-chip mounted on the mounting substrate. The light-emitting device of claim 1 or 2, wherein the light-emitting portion is disposed apart from the light source. The light-emitting device of claim 3, further comprising: a mounting substrate on a side opposite to the light source and the light-emitting portion, wherein the light source is mounted, the mounting substrate having a recess in which the light source and the light-emitting portion are housed Further, the light-emitting device further includes a cover member that covers the concave portion, and the light-emitting portion is provided on a surface of the cover member on the side of the concave portion. The light-emitting device of claim 3, further comprising: a unit disposed above the light source and sealing the light-emitting portion. A light-emitting device according to any one of claims 1 to 5, wherein said light source is constituted by an LED element. The light-emitting device according to any one of claims 1 to 6, further comprising: a mounting substrate on a side opposite to the light source and the light-emitting portion, wherein the light source is mounted, wherein the light-emitting portion further includes the quantum dot The dispersion medium, and the thermal conductivity of the dispersion medium is lower than the thermal conductivity of the mounting substrate.