Patent Application
20130209794
The present invention relates to the technical field of luminescent materials, and particularly to a luminescent device. The present invention also relates to a method for manufacturing a luminescent device.
Conventional materials used as the luminescent substrate include fluorescent powder, nano-crystal, luminescent glass, transparent ceramic, and the like. Transparent ceramic has distinctive advantages over other luminescent materials. Compared with luminescent glass, transparent ceramic has higher luminescent efficiency. Compared with fluorescent powder and nano-crystal, transparent ceramic has characteristics of transparency, high mechanical strength, good chemical stability, etc., and is easier to be processed into products with various sizes and shapes, such as displays or illumination lighting sources with various sizes or shapes.
For example, in the field of vacuum microelectronics, luminescent ceramic is usually used as phosphor in a field emission device. Luminescent ceramic exhibits a broad application prospect in the aspects of illumination and displaying, and has attracted extensive attention from research institutes worldwide. The operation mechanism of a field emission device comprises the followings: an anode applies a forward voltage against field emissive arrays (FEAs) in vacuum to establish an accelerating electric field, in which the electrons emitted by the cathode are accelerated and bombard the luminescent material on the anode plate, leading to light emission. The field emission device has broad operation temperature range (−40° C. to 80° C.), short response time (<1 ms), simple structure, low power consumption, and meets the need of environmental protection.
However, when used as a luminescent material in a field emission device, transparent ceramic has a problem with regard to low luminescent efficiency.
To address the above problems, the present invention provides a luminescent device comprising transparent ceramic having a formula of Y3Al5O12:Tb as a luminescent substrate.
The luminescent device comprises a luminescent substrate, and a metal layer which is disposed on the surface of the luminescent substrate and has a metal microstructure; the material for the luminescent substrate being transparent ceramic having a formula of Y3Al5O12:Tb.
In the luminescent device, the material for the metal layer is at least one selected from the group consisting of gold, silver, aluminum, copper, titanium, iron, nickel, cobalt, chromium, platinum, palladium, magnesium and zinc, and the thickness of the metal layer may be in the range of 0.5 nm to 200 nm.
Another object of the present invention is to provide a method for manufacturing the luminescent device as described above, comprising the steps of:
In step S2 of the above manufacturing method, the material for the metal layer is at least one selected from the group consisting of gold, silver, aluminum, copper, titanium, iron, nickel, cobalt, chromium, platinum, palladium, magnesium and zinc, and the thickness of the metal layer may be in the range of 0.5 nm to 200 nm.
In step S3 of the above manufacturing method, the annealing process comprises: annealing at 50° C. to 650° C. in vacuum for 0.5 to 5 hours, and then naturally cooling to room temperature.
Compared with the prior art, the present invention has the following advantages:
The present invention provides a luminescent device 10 as shown in
The present invention also provides a method for manufacturing the luminescent device described above, as shown in
In step S01 of the above method, the luminescent substrate may be a Tb-doped yttrium aluminum garnet series transparent luminescent ceramic having a formula of Y3Al5O12:Tb. In practice, transparent ceramic is processed into various forms required by the applications by means of machining, polishing, and the like, to form the luminescent substrate.
The metal layer may be formed by depositing a source of a metal material having good chemical stability, for example a metal resistant to oxidative corrosion, or a common metal material, preferably at least one metal selected from gold, silver, aluminum, copper, titanium, iron, nickel, cobalt, chromium, platinum, palladium, magnesium and zinc, more preferably at least one metal selected from gold, silver and aluminum.
In step S02 of the above method, the metal layer is formed on a surface of the luminescent substrate by physical or chemical vapor deposition of at least one metal as described above, for example but not limited to the method of sputtering or evaporating. The thickness of the metal layer is in the range of 0.5 nm to 200 nm, preferably 1 nm to 100 nm.
Step S03 of the above method specifically comprises: forming a metal layer on a surface of the luminescent substrate, annealing at 50° C. to 650° C. in vacuum for 1 to 5 hours, and naturally cooling to room temperature, wherein the annealing temperature is preferably 100° C. to 500° C. and the annealing time is preferably 1 to 3 hours.
As shown in
In practice, the light emitting process of the luminescent device according to the present invention, as shown in
In practice, step S12 may be carried out by using a field emission display or a lighting source. In a vacuum environment, the anode applies a forward voltage against field emissive arrays to establish an accelerating electric field, and accordingly the cathode emits cathode rays. Under the excitation of cathode rays, an electron beam first passes through the metal layer and then excites the luminescent substrate to emit light. In this process, the surface plasmon effect is produced at the interface between the metal layer and the luminescent substrate, which lead to significant increase of the internal quantum efficiency of the luminescent substrate, i.e. enhancing the spontaneous radiation of the luminescent material, and great improvement of the luminescent efficiency of the luminescent material.
As described above, an electron beam passes through the metal layer and then excites the luminescent substrate to emit light, wherein surface plasmon is produced at the interface between the luminescent substrate and the metal layer, so that the light emission of ceramic Y3Al5O12:Tb is promoted. Surface Plasmon (SP) is a wave propagating along the interface between a metal and a medium, and the amplitude thereof exponentially decays with the distance from the interface. When the structure of the metal surface is changed, the properties, dispersion relationship, excitation mechanism, coupling effect, etc., of surface plasmon polaritons (SPPs) would significantly vary. The electromagnetic field induced by SPPs can not only limit the wave propagation in a sub-wavelength structure, but also produce and control electromagnetic radiations ranging from optical frequency to microwave band, so as to achieve active control on the light propagation. Therefore, the present embodiment employs the excitation property of SPPs to enhance the optical state density and the spontaneous radiation rate of the luminescent substrate. Moreover, the coupling effect of surface plasmon may be utilized; when the luminescent substrate emits light, a coupling resonance effect may occur between surface plasmon and the luminescent substrate, which leads to significant increase in the inner quantum efficiency of the luminescent substrate and improvement in the emission efficiency of the luminescent substrate. Preferred examples of the present invention will be described in more details with reference to the drawings.
A Tb-doped yttrium aluminum garnet series transparent ceramic plate, i.e. a luminescent ceramic having a formula of Y3Al5O12:Tb, is used as the luminescent substrate. A silver layer having a thickness of 10 nm is deposited on a surface of the transparent ceramic plate with a magnetron sputtering equipment. The resulted device is placed in a vacuum environment have a vacuity of <1×10−3 Pa, annealed at 300° C. for half an hour, and then cooled to room temperature, to give a luminescent device with a metal layer having a metal microstructure.
A spectral test is carried out on the luminescent device manufactured above, wherein the luminescent device is bombarded by cathode rays produced by an electron gun. An electron beam first passes through the metal layer and then excites transparent ceramic Y3Al5O12:Tb to emit light, yielding a luminescent spectrum as shown in
Example 2 is basically the same as Example 1, excepted that a gold layer having a thickness of 0.5 nm is deposited on a surface of the luminescent substrate, the resulted device is placed in a vacuum environment have a vacuity of <1×10−3 Pa, annealed at 650° C. for 1 hour, and then cooled to room temperature, to give a luminescent device with a metal layer having a metal microstructure.
Example 3 is basically the same as Example 1, excepted that an aluminum layer having a thickness of 200 nm is deposited on a surface of the luminescent substrate, the resulted device is placed in a vacuum environment have a vacuity of <1×10−3 Pa, annealed at 50° C. for 5 hours, and then cooled to room temperature, to give a luminescent device with a metal layer having a metal microstructure.
It shall be understood by those skilled in the art that, while detailed description has been provided for preferred embodiments of the present invention, these should not be understood as limitations to the scope of the present invention, and the scope sought protection in the present invention should subject to the appended claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CN2010/080030 | 12/20/2010 | WO | 00 | 4/23/2013 |
