JP2007063301A - Phosphor for el - Google Patents
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本発明は、発光材料、特に紫外線領域の光を放射するＥＬ用蛍光体に関するものである。 The present invention relates to a luminescent material, and more particularly to an EL phosphor that emits light in the ultraviolet region.
近年の環境問題から、有害物質や細菌・ウイルスなどを分離、分解、または殺菌する機能が強く要求されている。このような分解・殺菌等を行う手段として光触媒材料が注目されている。代表的な光触媒はＴｉＯ2であるが、これは一般には波長が４００ｎｍ以下の紫外線により光触媒機能を発揮する。 Due to recent environmental problems, a function of separating, decomposing or sterilizing harmful substances, bacteria, viruses and the like is strongly demanded. Photocatalyst materials are attracting attention as means for performing such decomposition and sterilization. A typical photocatalyst is TiO 2 , which generally exhibits a photocatalytic function with ultraviolet rays having a wavelength of 400 nm or less.
このような波長の光を放射させるデバイスとしては、水銀ランプや発光ダイオードもあるが、点または線光源であるため、大面積の光触媒を均一に励起するには適さない。大面積を均一に発光させるデバイスとして無機エレクトロルミネッセンス（以下、「ＥＬ」とする。）デバイスがある。これは、光を放射する機能を持つ蛍光体粉末を誘電体樹脂に分散させて、主として交流電界を印加して発光させるものである。 Devices that emit light of such a wavelength include mercury lamps and light emitting diodes, but they are point or line light sources and are not suitable for uniformly exciting a large area photocatalyst. As a device that uniformly emits light over a large area, there is an inorganic electroluminescence (hereinafter referred to as “EL”) device. In this method, phosphor powder having a function of emitting light is dispersed in a dielectric resin, and light is emitted mainly by applying an alternating electric field.
特に高効率で発光する蛍光体としてはＺｎＳ蛍光体が挙げられる。一般にＺｎＳ蛍光体の中で短波長の発光を示すものはＡｇで付活されたものであるが、発光波長は４５０ｎｍの青色であり、可視光領域の光しか放射しない。この発光機構は、ＺｎＳ中に添加された付活剤のＡｇがアクセプタ準位を形成し、共付活剤として添加されるＣｌやＡｌ等がドナー準位を形成し、このドナー準位とアクセプタ準位間で電子と正孔が再結合することにより波長４５０ｎｍ程度のＤ−Ａペア型（別名Ｇｒｅｅｎ−Ｃｕ型、以下、「Ｇ−Ｃｕ型」とする。）の青色の発光が生じる。このＧ−Ｃｕ型の発光は、蛍光体母材をＺｎＳとＺｎＳよりもバンドギャップの大きい化合物、例えばＭｇＳやＣａＳ等の２Ａ族元素硫化物との混晶にして蛍光体母材のバンドギャップを増大させることにより短波長化することができると考えられる（例えば、特許文献１が挙げられる。）。 In particular, a phosphor that emits light with high efficiency includes a ZnS phosphor. In general, among the ZnS phosphors, those that emit light of a short wavelength are activated by Ag, but the emission wavelength is blue of 450 nm and emits only light in the visible light region. In this light emission mechanism, Ag of the activator added in ZnS forms an acceptor level, and Cl, Al, etc. added as a coactivator form a donor level, and this donor level and acceptor By recombination of electrons and holes between levels, DA-type blue light emission with a wavelength of about 450 nm (also called “Green-Cu type”, hereinafter referred to as “G-Cu type”) is generated. In this G-Cu type light emission, the phosphor base material is mixed with a compound having a larger band gap than ZnS and ZnS, for example, a group 2A element sulfide such as MgS or CaS, and the band gap of the phosphor base material is increased. It is considered that the wavelength can be shortened by increasing (for example, Patent Document 1).
しかし、このようなＡｇをドーピングした蛍光体はＥＬ発光させることができなかった。この理由を以下に説明する。ＥＬ用蛍光体として最も一般的なＺｎＳ：Ｃｕ，Ｃｌ蛍光体は、蛍光体内部に多数の双晶（積層欠陥）が形成されており、双晶界面に沿って導電性の高いＣｕ−Ｓ系化合物が針状に存在する。電界印加時に針状導電相の先端で電界集中が生じて蛍光体母体であるＺｎＳが励起され、このエネルギーが蛍光体中の各種準位に移動してＥＬ発光する。 However, such a phosphor doped with Ag could not emit EL. The reason for this will be described below. The most common ZnS: Cu, Cl phosphor as an EL phosphor has a large number of twins (stacking faults) formed inside the phosphor, and a highly conductive Cu-S system along the twin interface. The compound exists in a needle shape. When an electric field is applied, electric field concentration occurs at the tip of the acicular conductive phase, and the phosphor matrix, ZnS, is excited, and this energy moves to various levels in the phosphor to emit EL.
この蛍光体の一般的な製法は以下の通りである。原料粉末であるＺｎＳにＣｕＳＯ4やＫＣｌをドーピングした混合粉末を不活性雰囲気中で１０００〜１１００℃で数時間焼成後、室温まで冷却する。焼成時に生じるＺｎＳの粒成長段階で、成長双晶と呼ばれる多数の双晶が形成される。さらに焼成後の室温までの冷却段階で、ＺｎＳは六方晶から立方晶への相転移が生じ、転移双晶と呼ばれる多数の双晶が形成される。この時、ドーピングしたＣｕ成分の内、ＺｎＳの固溶限界を超えたＣｕは双晶界面に針状のＣｕ−Ｓ系化合物として析出する。かかるＣｕ−Ｓ系化合物は一般的にはＣｕ2Ｓであると言われている。またＣｕの変わりにＡｇをドーピングした場合、双晶界面に析出するのはＡｇ2Ｓであり、導電性が低いために電界集中効果を示さないのである。 The general manufacturing method of this phosphor is as follows. A mixed powder obtained by doping CuS 4 or KCl with ZnS as a raw material powder is fired at 1000 to 1100 ° C. for several hours in an inert atmosphere, and then cooled to room temperature. A number of twins called growth twins are formed at the grain growth stage of ZnS generated during firing. Furthermore, in the cooling step to room temperature after firing, a phase transition from hexagonal to cubic occurs in ZnS, and a number of twins called transition twins are formed. At this time, of the doped Cu component, Cu exceeding the solid solubility limit of ZnS precipitates as a needle-like Cu-S compound at the twin interface. Such a Cu-S compound is generally said to be Cu 2 S. In addition, when Ag is doped instead of Cu, it is Ag 2 S that precipitates at the twin interface, and the electric field concentration effect is not exhibited because the conductivity is low.
一方、蛍光体粉末の表面に導電性粒子を付着させることで、電界印加時に該導電性粒子近傍に電界集中を生じさせてＥＬ発光させることが報告されている。しかし、このような蛍光体では、導電性粒子が付着することで蛍光体粉末表面の抵抗が低下するために、電界印加時に、蛍光体表面を伝って電界が逃げてしまうリーク現象が起こるために、極めて発光寿命が短いＥＬ用蛍光体しか得られなかった。
そこで本発明は、このようなリーク現象を抑制し、短波長域の光を高強度でかつ継続的にＥＬ発光させることができるＥＬ用蛍光体を提供することを目的とする。
またＡｇをドーピングした本来はＥＬ発光しない蛍光体粉末を用いてもＥＬ発光するＥＬ用蛍光体を提供することを目的とする。
On the other hand, it has been reported that by attaching conductive particles to the surface of the phosphor powder, an electric field is concentrated in the vicinity of the conductive particles when an electric field is applied to cause EL emission. However, in such a phosphor, the resistance of the phosphor powder surface decreases due to the adhesion of conductive particles, and therefore, a leak phenomenon occurs in which the electric field escapes through the phosphor surface when an electric field is applied. Only EL phosphors with a very short emission lifetime were obtained.
Therefore, an object of the present invention is to provide an EL phosphor that can suppress such a leak phenomenon and can continuously emit light in a short wavelength region with high intensity and EL.
It is another object of the present invention to provide an EL phosphor that emits EL even when phosphor powder originally doped with Ag and does not emit EL is used.
本発明は、上記課題を解決するために以下の特徴を持つ。
（１）蛍光体粉末と、該蛍光体粉末の表面の一部に形成された導電性粒子と、該蛍光体粉末及び該導電性粒子を被覆する絶縁層とからなるＥＬ用蛍光体。
（２）前記蛍光体粉末の母体が、硫化物を主な組成物とすることを特徴とする上記（１）記載のＥＬ用蛍光体。
（３）前記蛍光体粉末の主成分が、一般式Ｚｎ(1-x)ＡxＳ：Ａｇ，ＤまたはＺｎ(1-x)ＡxＳ：Ｃｕ，Ｄ（式中のＡは、Ｂｅ、Ｍｇ、Ｃａ、Ｓｒ及びＢａの群から選ばれる少なくとも１種の２Ａ族元素、Ｄは、３Ｂ族または７Ｂ族元素から選ばれる少なくとも１種、そして混合比率ｘが０≦ｘ＜１）で表される組成物であることを特徴とする上記（１）又は（２）記載のＥＬ用蛍光体。
The present invention has the following features to solve the above problems.
(1) An EL phosphor comprising a phosphor powder, conductive particles formed on a part of the surface of the phosphor powder, and an insulating layer covering the phosphor powder and the conductive particles.
(2) The phosphor for EL according to the above (1), wherein the matrix of the phosphor powder is mainly composed of sulfide.
(3) The main component of the phosphor powder is a general formula Zn (1-x) A x S: Ag, D or Zn (1-x) A x S: Cu, D (A in the formula is Be, At least one 2A group element selected from the group consisting of Mg, Ca, Sr and Ba, D is at least one selected from 3B group or 7B group element, and the mixing ratio x is represented by 0 ≦ x <1) The phosphor for EL according to the above (1) or (2), which is a composition comprising:
（４）前記導電性粒子の比抵抗が、１０-1Ωｃｍ以下である上記（１）〜（３）のいずれか一に記載のＥＬ用蛍光体。
（５）前記導電性粒子が、Ｃｕ−Ｓ系化合物、Ａｕ、Ａｇ、カーボンナノチューブ、カーボンナノホーンである上記（１）〜（４）のいずれかに記載のＥＬ用蛍光体。
（６）前記蛍光体粉末の表面を覆う導電性粒子の占有面積が、蛍光体粉末の表面積の１〜５０％である上記（１）〜（５）のいずれか一に記載のＥＬ用蛍光体。
（７）前記絶縁層が、Ａｌ2Ｏ3、ＡｌＮ、Ａｌ（ＮＯ3)3、ＳｉＯ2のいずれかである上記（１）〜（６）のいずれか一に記載のＥＬ用蛍光体。
(4) The phosphor for EL according to any one of (1) to (3), wherein the specific resistance of the conductive particles is 10 −1 Ωcm or less.
(5) The phosphor for EL according to any one of (1) to (4), wherein the conductive particles are a Cu—S compound, Au, Ag, a carbon nanotube, or a carbon nanohorn.
(6) The phosphor for EL according to any one of (1) to (5), wherein an area occupied by the conductive particles covering the surface of the phosphor powder is 1 to 50% of a surface area of the phosphor powder. .
(7) The phosphor for EL according to any one of (1) to (6), wherein the insulating layer is any one of Al 2 O 3 , AlN, Al (NO 3 ) 3 , and SiO 2 .
本発明品は、蛍光体粉末の表面に微小な導電性粒子が被覆されていることに加え、蛍光体粉末と導電性粒子全体を覆うように、最表面には絶縁層が被覆されている。ＥＬデバイスに電界を印加した時、蛍光体表面を伝って電界がリークすることなく、導電性粒子近傍に効率よく電界集中が生じることで安定したＥＬ発光が可能となる。 In the product of the present invention, the surface of the phosphor powder is coated with fine conductive particles, and the outermost surface is coated with an insulating layer so as to cover the phosphor powder and the entire conductive particles. When an electric field is applied to the EL device, the electric field is not leaked along the phosphor surface, and the electric field is efficiently concentrated in the vicinity of the conductive particles, thereby enabling stable EL emission.
蛍光体粉末の表面への導電性粒子の被覆は、コロイド法などを用い手行うことができる。例えば、Ｃｕ（ＯＣｌ4)2の水溶液中に蛍光体を分散させた後、これにＮａ2Ｓの水溶液を添加することで蛍光体表面にＣｕ2Ｓが付着する。Ｃｕ2Ｓの付着量は、各水溶液の濃度等を変化させることで可能である。最表面の絶縁層の被覆は、ゾルゲル法などでＳｉＯ2やＡｌ2Ｏ3を被覆する方法でもできるし、気相法でもよい。この最表面の絶縁層の被覆は、導電性粒子が表面に露出しないようにすることが好ましい。露出すると、表面を電界がリークする場合がある。 Coating of the conductive particles on the surface of the phosphor powder can be performed manually using a colloid method or the like. For example, after dispersing the phosphor in an aqueous solution of Cu (OCl 4 ) 2 , Cu 2 S adheres to the phosphor surface by adding an aqueous solution of Na 2 S thereto. The amount of Cu 2 S deposited can be changed by changing the concentration of each aqueous solution. The outermost insulating layer can be coated by a method of coating SiO 2 or Al 2 O 3 by a sol-gel method or the like, or by a vapor phase method. The coating of the outermost insulating layer is preferably performed so that the conductive particles are not exposed on the surface. When exposed, an electric field may leak from the surface.
導電性粒子は少なくとも蛍光体粉末よりも小さいことが好ましい。大きい場合、導電性粒子と蛍光体粉末表面の接触点が少なくなり電界集中しにくくなる。好ましくは、平均直径が１００ｎｍ以下である。平均直径が数ｎｍのナノ粒子が最も好ましい。
導電性粒子の比抵抗は１０-1Ωｃｍ以下であることが好ましい。これを上回ると電界集中効果が低下する。導電性粒子としては、Ｃｕ−Ｓ系化合物、Ａｕ、Ａｇ、カーボンナノチューブ（以下、「ＣＮＴ」とする。）、カーボンナノホーン（以下、「ＣＮＨ」とする。）等が好ましい。
The conductive particles are preferably at least smaller than the phosphor powder. If it is large, the number of contact points between the conductive particles and the phosphor powder surface is reduced, and it becomes difficult to concentrate the electric field. Preferably, the average diameter is 100 nm or less. Nanoparticles with an average diameter of several nm are most preferred.
The specific resistance of the conductive particles is preferably 10 −1 Ωcm or less. Above this, the electric field concentration effect decreases. As the conductive particles, Cu—S compounds, Au, Ag, carbon nanotubes (hereinafter referred to as “CNT”), carbon nanohorns (hereinafter referred to as “CNH”), and the like are preferable.
蛍光体粉末の表面を覆う導電性粒子の占有面積は蛍光体粉末の表面積の１〜５０％であることが好ましい。好ましくは２０〜５０％である。１％より少ないと電界集中効果が極めて低下し、ＥＬ発光強度が激減する。２０％未満では、電界集中箇所が少ないために発光強度が低下し、５０％を越えると、蛍光体からの光が導電性粒子で遮られて発光強度が低下する。
絶縁層としては、アルミの酸化物、窒化物、酸窒化物及び酸化ケイ素を用いることが好ましい。これらの材料は耐湿性が高いために、耐湿コーティング層としても機能するので蛍光体の寿命を延ばす効果がある。好ましい絶縁層の厚さは２０〜３００ｎｍ程度である。３００ｎｍを越えると、材質によっては発光強度が低下する場合がある。
The area occupied by the conductive particles covering the surface of the phosphor powder is preferably 1 to 50% of the surface area of the phosphor powder. Preferably it is 20 to 50%. If it is less than 1%, the electric field concentration effect is extremely lowered and the EL emission intensity is drastically reduced. If it is less than 20%, the light emission intensity decreases because there are few electric field concentration sites, and if it exceeds 50%, the light from the phosphor is blocked by the conductive particles and the light emission intensity decreases.
As the insulating layer, it is preferable to use aluminum oxide, nitride, oxynitride, and silicon oxide. Since these materials have high moisture resistance, they also function as a moisture-resistant coating layer, and thus have an effect of extending the life of the phosphor. A preferable thickness of the insulating layer is about 20 to 300 nm. If it exceeds 300 nm, the emission intensity may decrease depending on the material.
本発明は、あらゆる蛍光体粉末を用いることができるが、特に発光効率の高い硫化物を主成分とする蛍光体粉末を用いることが好ましい。さらには、Ａｇのアクセプタ準位が浅く短波長発光しやすいＺｎＳ系蛍光体が好ましい。 In the present invention, any phosphor powder can be used, but it is particularly preferable to use a phosphor powder mainly composed of a sulfide having high luminous efficiency. Furthermore, a ZnS-based phosphor that has a shallow acceptor level of Ag and easily emits light at a short wavelength is preferable.
蛍光体粉末の主な成分が、一般式Ｚｎ（１−ｘ）ＡｘＳ：Ａｇ，Ｄ（式中のＡは、Ｂｅ、Ｍｇ、Ｃａ、Ｓｒ及びＢａの群から選ばれる少なくとも１種の２Ａ族元素、Ｄは、３Ｂ族または７Ｂ族元素から選ばれる少なくとも１種、０≦ｘ＜１）で表される組成物である場合、短波長発光させることができる。この蛍光体粉末は、ＺｎＳを基に、バンドギャップの大きいＭｇＳやＣａＳ等の２Ａ族硫化物を混合した混晶母体とし、アクセプタとしてＡｇを、ドナーとしてＣｌやＡｌ等の３Ｂ族または７Ｂ族元素を添加して作製され、Ｂｌｕｅ−Ｃｕ型発光機能を持つ蛍光体であり、ＥＬスペクトルのピーク波長を４００ｎｍ以下の領域にすることができる。このようなＢｌｕｅ−Ｃｕ型発光を持つ蛍光体は、付活剤（アクセプタ）であるＡｇを共付活剤（ドナー）のモル濃度以上のモル濃度で含有させることにより作製できる。 The main component of the phosphor powder is a general formula Zn (1-x) A x S: Ag, D (A in the formula is at least one 2A selected from the group of Be, Mg, Ca, Sr, and Ba) When the group element, D, is a composition represented by at least one selected from group 3B or group 7B elements, 0 ≦ x <1), light can be emitted at a short wavelength. This phosphor powder is a mixed crystal matrix in which 2S group sulfides such as MgS and CaS having a large band gap are mixed based on ZnS, Ag as an acceptor, and 3B or 7B group elements such as Cl and Al as donors. Is a phosphor having a Blue-Cu type light emitting function, and the peak wavelength of the EL spectrum can be in the region of 400 nm or less. Such a phosphor having a Blue-Cu type light emission can be prepared by containing Ag as an activator (acceptor) at a molar concentration equal to or higher than the molar concentration of the coactivator (donor).
Ｇ−Ｃｕ型発光する蛍光体粉末、例えばＺｎＳ：Ａｇ，Ｃｌでは、ＡｇはＺｎＳ結晶格子のＺｎ位置を置換し、ＣｌはＳ位置を置換する。これに対して、本発明では、ＺｎＳ系蛍光体に共付活剤のモル濃度よりも高いモル濃度のＡｇを添加することで、Ｚｎ位置を置換するＡｇに加えて、新たに電荷補償されないＡｇをＺｎＳの結晶格子間に導入することで得られる。更に、蛍光体母材をＺｎＳとＢｅＳ、ＭｇＳ、ＣａＳ、ＳｒＳおよびＢａＳの中から少なくとも１種選ばれる２Ａ族硫化物との混晶にすることにより結晶格子を拡大させ、より多くのＡｇが格子間に侵入しやすいようにした。このような混晶蛍光体を用いると、ＥＬ発光スペクトルのピーク波長を３８８ｎｍ以下にすることができる。 In a phosphor powder that emits G-Cu type light, for example, ZnS: Ag, Cl, Ag substitutes the Zn position of the ZnS crystal lattice, and Cl substitutes the S position. On the other hand, in the present invention, by adding Ag at a molar concentration higher than the molar concentration of the coactivator to the ZnS-based phosphor, Ag that is not newly charge-compensated in addition to Ag replacing the Zn position. Is introduced between the crystal lattices of ZnS. Furthermore, the crystal lattice is expanded by making the phosphor base material a mixed crystal of ZnS and a group 2A sulfide selected from at least one of BeS, MgS, CaS, SrS and BaS, and more Ag is latticed. Made it easy to intrude in between. When such a mixed crystal phosphor is used, the peak wavelength of the EL emission spectrum can be reduced to 388 nm or less.
本発明は、蛍光体粉末が、一般式Ｚｎ(1-x)ＡxＳ：Ｃｕ，Ｄ（式中のＡは、Ｂｅ、Ｍｇ、Ｃａ、Ｓｒ及びＢａの群から選ばれる少なくとも１種の２Ａ族元素、Ｄは、３Ｂ族または７Ｂ族元素から選ばれる少なくとも１種、０＜ｘ＜１）で表される成分を主として含むものであっても良い。またＢｌｕｅ−Ｃｕ型発光機能を持つ蛍光体粉末の場合にも適用できる。ＺｎＳ：Ｃｕの場合は、通常の焼成時に蛍光体内部に形成される多くの双晶の界面にＣｕ−Ｓ系化合物が析出して、導電相として機能するので、本発明のような構造は特に必要ない。しかし、ＺｎＭｇＳやＺｎＣａＳ等のように、結晶構造が全温度域に亘って六方晶である蛍光体に対しては有効な方法となる。これは、これらの混晶蛍光体は、成長双晶が生成しにくく、また転移双晶が生成しないために、ＺｎＳと同じ通常の焼成では低輝度でしかＥＬ発光しない。本発明を用いることで高輝度でＥＬ発光させることができる。 In the present invention, the phosphor powder has the general formula Zn (1-x) A x S: Cu, D (wherein A is at least one 2A selected from the group consisting of Be, Mg, Ca, Sr and Ba). Group element D may contain at least one component selected from Group 3B or Group 7B elements and a component represented by 0 <x <1). It can also be applied to a phosphor powder having a Blue-Cu type light emitting function. In the case of ZnS: Cu, a Cu-S-based compound precipitates at many twin interfaces formed inside the phosphor during normal firing and functions as a conductive phase. unnecessary. However, this method is effective for phosphors whose crystal structure is hexagonal over the entire temperature range, such as ZnMgS and ZnCaS. This is because these mixed crystal phosphors are unlikely to form growth twins and do not generate transition twins, so that they emit EL only at low brightness in the same normal firing as ZnS. By using the present invention, EL light can be emitted with high luminance.
Ｃｕをドーピングする場合は、導電性粒子を別に被覆しなくても蛍光体の焼成時に自然に析出させることもできる。すなわち、蛍光体母体に固溶できなかったＣｕは蛍光体粉末表面に導電性粒子となる銅の硫化物として析出する。析出量の制御は、原料の仕込み段階で調整することができる。このような混晶蛍光体を用いると、ＥＬ発光スペクトルの一部を４００ｎｍ以下の波長域にすることができる。 In the case of doping with Cu, the phosphor can be naturally deposited at the time of firing the phosphor without coating the conductive particles separately. That is, Cu that could not be dissolved in the phosphor matrix is deposited on the phosphor powder surface as copper sulfide that becomes conductive particles. Control of the amount of precipitation can be adjusted at the raw material charging stage. When such a mixed crystal phosphor is used, a part of the EL emission spectrum can be in a wavelength region of 400 nm or less.
本発明の蛍光体は、蛍光体内部に導電相が無い場合でも効率よくＥＬ発光する蛍光体であり、特にＡｇをドーピングした本来はＥＬ発光しない蛍光体であっても、蛍光体粉末を選択することにより、短波長可視光や紫外線をＥＬ発光できる。 The phosphor of the present invention is a phosphor that efficiently emits EL even when there is no conductive phase inside the phosphor. In particular, a phosphor powder is selected even for a phosphor that originally doped Ag and does not emit EL. Thus, EL can be emitted from short-wavelength visible light or ultraviolet light.
以下、本発明の一実施態様を実施例に基づいて説明する。
実施例１
（ＥＬ用蛍光体の作製方法）
（１）原料
蛍光体母体：平均粒径１μｍのＺｎＳ
付活剤：平均粒径１μｍのＡｇ2Ｓ粉末
共付活剤：平均粒径２０μｍのＫＣｌ粉末
（２）混合
原料粉末を所定のドーピング組成になるようエタノール中に分散させ、更に超音波振動を印加して３時間混合を行った。その後、乾燥アルゴンを流入させたエバポレータを用い、各種溶媒を揮発させ原料混合物の乾燥を行った。
（３）焼成
回収した原料混合物は、２０×２００×２０ｍｍ（高さ）の蓋付きの石英るつぼに投入し、管状炉を用い、１気圧の１０％Ｈ2Ｓ−Ｈ2ガス中、１１００℃で６時間焼成を行った後、炉内で室温まで自然冷却することによって蛍光体粉末を作製した。
Hereinafter, one embodiment of the present invention will be described based on examples.
Example 1
(Method for producing phosphor for EL)
(1) Raw materials Phosphor matrix: ZnS with an average particle size of 1 μm
Activator: Ag 2 S powder with an average particle diameter of 1 μm Coactivator: KCl powder (2) mixed with an average particle diameter of 20 μm The raw material powder is dispersed in ethanol so as to have a predetermined doping composition, and further subjected to ultrasonic vibration. The mixture was applied for 3 hours. Then, using an evaporator into which dry argon was introduced, various solvents were volatilized and the raw material mixture was dried.
(3) Firing The collected raw material mixture is put into a quartz crucible with a lid of 20 × 200 × 20 mm (height) and is used in a tubular furnace at 1100 ° C. in 10% H 2 S—H 2 gas at 1 atm. After firing for 6 hours, phosphor powder was produced by naturally cooling to room temperature in a furnace.
（導電性粒子の被覆）
Ｃｕ（ＯＣｌ4)2またはＡｇ（ＯＣｌ4)2を純水に溶解して０．１ｍｏｌ％の水溶液Ａとした。Ｎａ２Ｓを純水に溶解して０．１ｍｏｌ％の水溶液Ｂとした。上記で得られた蛍光体粉末を１００ｃｍ3の水溶液Ａに浸漬し超音波混合を５分行った後、１００ｃｍ3の水溶液Ｂを加えて２０〜３０分放置した。その後濾紙で濾過して蛍光体を回収した。蛍光体粉末への導電性粒子の付着量は放置時間を調整して行った。導電性粒子の粒径と被覆率はＴＥＭで観察した。生成相はＸＲＤで同定した。
(Coating of conductive particles)
Cu (OCl 4 ) 2 or Ag (OCl 4 ) 2 was dissolved in pure water to obtain 0.1 mol% aqueous solution A. Na 2 S was dissolved in pure water to obtain a 0.1 mol% aqueous solution B. The phosphor powder obtained above was immersed in 100 cm 3 of aqueous solution A and subjected to ultrasonic mixing for 5 minutes, and then 100 cm 3 of aqueous solution B was added and left for 20 to 30 minutes. Thereafter, it was filtered with a filter paper to collect the phosphor. The amount of conductive particles adhering to the phosphor powder was adjusted by adjusting the standing time. The particle size and coverage of the conductive particles were observed with TEM. The product phase was identified by XRD.
（絶縁層の被覆）
上記で得られた蛍光体上にシリカ、アルミナをゾルゲル法を用いて各種条件で絶縁層を被覆することによりＥＬ用蛍光体を作製した。膜厚はＴＥＭで確認した。
（発光波長の評価方法）
５０×５０×１ｍｍの石英ガラス基板に、４０×４０×５０μｍ深さの凹加工を施した後、アルミを０．１μｍ厚さ蒸着して裏面電極とした。上記で得られたＥＬ用蛍光体をひまし油に、３５ｖｏｌ％の体積分率で超音波混合してスラリーにし、これを凹部に流し込んだ。最後に、厚さ０．１μｍの透明導電膜（表面電極）がコーティングされた５０×５０×１ｍｍの石英ガラス基板で蓋をしてＥＬデバイスとした。
(Insulation layer coating)
The phosphor for EL was produced by covering the phosphor obtained above with an insulating layer of silica and alumina under various conditions using a sol-gel method. The film thickness was confirmed by TEM.
(Evaluation method of emission wavelength)
A 50 × 50 × 1 mm quartz glass substrate was subjected to concave processing of a depth of 40 × 40 × 50 μm, and then aluminum was deposited to a thickness of 0.1 μm to form a back electrode. The EL phosphor obtained above was ultrasonically mixed with castor oil at a volume fraction of 35 vol% to form a slurry, which was poured into the recess. Finally, a 50 × 50 × 1 mm quartz glass substrate coated with a transparent conductive film (surface electrode) having a thickness of 0.1 μm was covered to obtain an EL device.
両電極にリード線を取り付け、電圧５００Ｖ、周波数３０００Ｈｚの交流電圧を印加した。発光スペクトルはフォトニックアナライザを用い、同じ感度で測定した。一部の試料に関して発光強度の比較を行った。得られた発光スペクトルのピーク波長の強度を相対比較した。発光寿命は輝度が半減するまでの時間を最長１００時間まで測定した。
結果を表１に示す。
Lead wires were attached to both electrodes, and an AC voltage having a voltage of 500 V and a frequency of 3000 Hz was applied. The emission spectrum was measured with the same sensitivity using a photonic analyzer. The emission intensity of some samples was compared. The relative intensities of the peak wavelengths of the obtained emission spectra were compared. The light emission lifetime was measured up to 100 hours until the luminance was reduced by half.
The results are shown in Table 1.
表１より明らかなように、導電性粒子がないとＥＬ発光を生じない（蛍光体Ｎo.１）。導電性粒子がＡｇ2Ｓの場合は、抵抗が高いのでＥＬ発光を生じない（蛍光体Ｎo.５）。また蛍光体粉末の表面に導電性粒子を形成しても絶縁層を被覆しないとＥＬ発光を生じないか（蛍光体Ｎo.２）、ＥＬ発光が生じてもその発光寿命が極めて短かった（蛍光体Ｎo.３）。さらに絶縁層厚が１８０ｎｍ以上にすると寿命は１００時間を超えた（蛍光体Ｎo.７〜９）。但し、絶縁層厚が厚くなるほど発光強度は低くなることが分かった。 As is apparent from Table 1, EL emission is not generated without the conductive particles (phosphor No. 1). When the conductive particles are Ag 2 S, the resistance is high, so EL emission does not occur (phosphor No. 5). Further, even if conductive particles are formed on the surface of the phosphor powder, if the insulating layer is not covered, EL emission does not occur (phosphor No. 2), or even if EL emission occurs, the emission lifetime is extremely short (fluorescence). Body No. 3). Furthermore, when the thickness of the insulating layer was 180 nm or more, the lifetime exceeded 100 hours (phosphor No. 7 to 9). However, it has been found that the emission intensity decreases as the insulating layer thickness increases.
実施例２
（蛍光体の作製方法）
（１）原料
蛍光体母体：平均粒径１μｍのＺｎＳ、ＭｇＳ、ＣａＳ、ＳｒＳ
付活剤：平均粒径１μｍのＡｇ2Ｓ粉末
共付活剤：平均粒径２０μｍのＫＣｌ粉末、Ａｌ、Ｆ、Ｂｒ
所定の組成になるように原料粉末を混合し、後の工程は実施例１と同様に蛍光体粉末を作製した。
Example 2
(Phosphor production method)
(1) Raw material Phosphor matrix: ZnS, MgS, CaS, SrS having an average particle diameter of 1 μm
Activator: Ag 2 S powder with an average particle diameter of 1 μm Coactivator: KCl powder with an average particle diameter of 20 μm, Al, F, Br
The raw material powder was mixed so as to have a predetermined composition, and the phosphor powder was prepared in the same manner as in Example 1 in the subsequent steps.
（導電性粒子の被覆）
Ｃｕ2Ｓの被覆は実施例１と同様に行った。
Ａｇ、Ａｕの被覆は、平均粒径が４ｎｍの金属ナノ粒子の分散液（各種濃度）に蛍光体粉末を浸漬して作製した。ＣＮＴの被覆は、濃度０．１ｗｔ％のＣＮＴ分散液に蛍光体粉末を浸漬して作製した。
(Coating of conductive particles)
The coating of Cu 2 S was performed in the same manner as in Example 1.
The coating of Ag and Au was prepared by immersing the phosphor powder in a dispersion (various concentrations) of metal nanoparticles having an average particle diameter of 4 nm. The CNT coating was prepared by immersing the phosphor powder in a CNT dispersion having a concentration of 0.1 wt%.
（絶縁層の被覆）
実施例１と同様に行った。
（発光波長の評価方法）
実施例１と同様に行った。その結果を表２に示す。
(Insulation layer coating)
The same operation as in Example 1 was performed.
(Evaluation method of emission wavelength)
The same operation as in Example 1 was performed. The results are shown in Table 2.
表２より明らかなように、蛍光体母体をＭｇＳ、またはＣａＳ等との混晶にすることにより発光波長は短波長化した。導電性粒子の占有率が１％より小さくなると発光強度が激減した（蛍光体Ｎo.１２）。
また導電性粒子の粒径が増大すると発光強度が低下することが分かった（蛍光体Ｎo.１９）。また、導電性粒子としてＡｇ、Ａｕ、ＣＮＴを用いると発光強度が向上した（蛍光体Ｎo.２１〜２３）。これはＣｕ２Ｓよりも抵抗が低いためと考えられる。
As is clear from Table 2, the emission wavelength was shortened by making the phosphor matrix a mixed crystal with MgS or CaS. When the occupation ratio of the conductive particles was smaller than 1%, the emission intensity was drastically decreased (phosphor No. 12).
It was also found that the emission intensity decreased as the particle size of the conductive particles increased (phosphor No. 19). Further, when Ag, Au, or CNT was used as the conductive particles, the emission intensity was improved (phosphor Nos. 21 to 23). This is probably because the resistance is lower than that of Cu 2 S.
実施例３
（蛍光体の作製方法）
（１）原料
蛍光体母体：平均粒径１μｍのＺｎＳ、ＭｇＳ
付活剤：平均粒径１μｍのＣｕ２Ｓ粉末
共付活剤：平均粒径２０μｍのＢｒ粉末 所定の組成になるように原料粉末を混合し、後の工程は実施例１と同様に蛍光体粉末を作製した。なお蛍光体粉末の表面には導電性粒子としてＣｕ２Ｓが析出した。
Example 3
(Phosphor production method)
(1) Raw materials Phosphor matrix: ZnS, MgS having an average particle diameter of 1 μm
Activator: Cu 2 S powder having an average particle diameter of 1 μm Coactivator: Br powder having an average particle diameter of 20 μm The raw material powder is mixed so as to have a predetermined composition, and the subsequent steps are the same as in Example 1. A powder was prepared. Cu 2 S was deposited as conductive particles on the surface of the phosphor powder.
（絶縁層の被覆）
実施例１と同様に行った。
（発光波長の評価方法）
実施例１と同様に行った。その結果を表３に示す。
(Insulation layer coating)
The same operation as in Example 1 was performed.
(Evaluation method of emission wavelength)
The same operation as in Example 1 was performed. The results are shown in Table 3.
本発明の蛍光体は、ＥＬにより短波長の光を安定して発光させることができるＥＬ用蛍光体である。これを用いたＥＬシートは、コンパクトで薄型の紫外面発光源となるため、光触媒と組み合わせることにより有害物や細菌等を含む気体、液体及び半流動体等を浄化することができ、ＮＯｘ、ＳＯｘ、ＣＯガス、ディーゼルパティキュレート、花粉、埃、ダニ等の分解除去、下水中に含まれる有機化合物の分解除去、一般の細菌、ウイルス等の殺菌光源、化学プラントで発生する有害ガスの分解、臭い成分の分解等もできる。 The phosphor of the present invention is a phosphor for EL that can stably emit light having a short wavelength by EL. The EL sheet using this becomes a compact and thin ultraviolet light emitting source, so it can purify gases, liquids and semi-fluids containing harmful substances and bacteria, etc. by combining with a photocatalyst. NOx, SOx , CO gas, diesel particulates, pollen, dust, mites, etc., decomposition and removal of organic compounds in sewage, sterilization light sources such as general bacteria and viruses, decomposition of harmful gases generated in chemical plants, smell The components can be decomposed.
Claims (7)
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| WO2009047899A1 (en) * | 2007-10-12 | 2009-04-16 | Panasonic Corporation | Light emitting element and display device |
| WO2009057317A1 (en) * | 2007-11-01 | 2009-05-07 | Panasonic Corporation | Light-emitting device and display device |
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| WO2009047899A1 (en) * | 2007-10-12 | 2009-04-16 | Panasonic Corporation | Light emitting element and display device |
| US20100213450A1 (en) * | 2007-10-12 | 2010-08-26 | Eiichi Satoh | Phosphor element and display device |
| JPWO2009047899A1 (en) * | 2007-10-12 | 2011-02-17 | パナソニック株式会社 | LIGHT EMITTING ELEMENT AND DISPLAY DEVICE |
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| JP2009221469A (en) * | 2008-02-21 | 2009-10-01 | Semiconductor Energy Lab Co Ltd | Method for manufacturing inorganic electroluminescent blue-light emitting body, inorganic electroluminescent blue-light emitting body, and light-emitting device |
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| US8450766B2 (en) | 2008-03-17 | 2013-05-28 | Panasonic Corporation | Light emitting device |
| JP5351882B2 (en) * | 2008-03-17 | 2013-11-27 | パナソニック株式会社 | Light emitting element |
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