JPH05190284A - Thin film electroluminescence element - Google Patents
Thin film electroluminescence elementInfo
- Publication number
- JPH05190284A JPH05190284A JP4002106A JP210692A JPH05190284A JP H05190284 A JPH05190284 A JP H05190284A JP 4002106 A JP4002106 A JP 4002106A JP 210692 A JP210692 A JP 210692A JP H05190284 A JPH05190284 A JP H05190284A
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- Prior art keywords
- light emitting
- emitting layer
- layer
- tfel
- secondary electron
- Prior art date
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- Devices For Indicating Variable Information By Combining Individual Elements (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、薄膜エレクトロルミネ
ッセンス素子（ＴＦＥＬ素子）に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film electroluminescence device (TFEL device).
【０００２】[0002]
【従来の技術】ＴＦＥＬ素子としては、発光層の両面に
誘電体層を設けた、いわゆる二重絶縁型ＴＦＥＬ素子が
知られている。かかる二重絶縁型ＴＦＥＬ素子の発光機
構を以下に説明する。2. Description of the Related Art As a TFEL element, a so-called double insulation type TFEL element in which dielectric layers are provided on both surfaces of a light emitting layer is known. The light emitting mechanism of such a double insulation type TFEL element will be described below.
【０００３】ＴＦＥＬ素子の膜面に対し、垂直方向に交
流電圧を印加する。この電圧を上げて、前記誘電体層間
に１０6 Ｖ／ｃｍ前後の電界を発生させると、前記発光
層と誘電体層の界面準位に存在する電子がプール・フレ
ンケル過程やトンネル過程により前記発光層の伝導帯に
注入される。注入された電子は、前記電界によって加速
され、ホットエレクトロンとなり発光層中の発光中心イ
オンに衝突する。発光中心イオンは、前記ホットエレク
トロンのエネルギーを得て励起される。そして、前記発
光中心イオンの電子が励起準位から基底準位に緩和され
る時に発光がなされる。ホットエレククトロンは、その
エネルギーを次第に失い、反対側の発光層と誘電体層の
界面にトラップされる。そして、電界が反転すると、前
述したのと同様な過程を経て発光中心イオンが励起され
て発光がなされる。ところで、前記ＴＦＥＬ素子の発光
輝度（Ｂ）は次式で見積もられる。 Ｂ＝４ηｆＣ1 （Ｖａ−Ｖｔ）ＶｚAn alternating voltage is applied vertically to the film surface of the TFEL element. By increasing this voltage, 10 6 is applied between the dielectric layers. When an electric field of about V / cm is generated, electrons existing at the interface state between the light emitting layer and the dielectric layer are injected into the conduction band of the light emitting layer by the Pool-Frenkel process or the tunnel process. The injected electrons are accelerated by the electric field, become hot electrons, and collide with emission center ions in the emission layer. The emission center ion is excited by obtaining the energy of the hot electrons. Light is emitted when the electrons of the emission center ion are relaxed from the excitation level to the ground level. The hot electron gradually loses its energy and is trapped at the interface between the light emitting layer and the dielectric layer on the opposite side. Then, when the electric field is reversed, the emission center ions are excited and light is emitted through the same process as described above. By the way, the emission brightness (B) of the TFEL element is estimated by the following equation. B = 4 ηfC 1 (Va-Vt) Vz
【０００４】ここで、ηは発光効率（１ｍ／Ｗ）、ｆは
駆動周波数、Ｃ1 は誘電体層の静電容量、ＶａはＴＦＥ
Ｌ素子に印加される交流電圧、Ｖｔは発光開始電圧、Ｖ
ｚは発光層に加わる電圧である。Here, η is the luminous efficiency (1 m / W), f is the driving frequency, C 1 is the capacitance of the dielectric layer, and Va is TFE.
AC voltage applied to the L element, Vt is the light emission start voltage, Vt
z is a voltage applied to the light emitting layer.
【０００５】前記式において、ＴＦＥＬ素子の構成材料
と各膜厚および駆動条件を一定とした場合、Ｂに対する
主な要因はηとＶｔとなる。前記発光過程での界面準位
は一定ではなく、ある広がりを有する。かかる状態は、
ＴＦＥＬ素子の各薄膜が単結晶でないことと相俟って成
膜条件で決定される膜質によって大きく変化する。しか
も、前記各界面準位に存在する電子濃度も変化する。こ
のため、ＴＦＥＬ素子の材料、構造を一定にしても前記
Ｖｔは変動する。また、ηは主に電子に対する発光中心
の衝突断面積が作用要因であるため、発光中心イオンの
濃度を固定した場合、前記作用要因は電子濃度となり、
結局界面準位に存在する電子の濃度となる。また、実際
に行われている成膜方法では発光層の中に多くの不純物
原子や格子欠陥が存在し、これらは電子の捕獲準位とな
る。In the above equation, when the constituent materials of the TFEL element, the respective film thicknesses and the driving conditions are constant, the main factors for B are η and Vt. The interface state in the light emitting process is not constant and has a certain spread. This situation is
Along with the fact that each thin film of the TFEL element is not a single crystal, it greatly changes depending on the film quality determined by the film forming conditions. Moreover, the electron concentration existing at each interface level also changes. Therefore, the Vt varies even if the material and structure of the TFEL element are constant. Further, η is mainly an action factor due to the collision cross section of the emission center with respect to electrons, so when the concentration of emission center ions is fixed, the action factor is the electron concentration,
After all, it becomes the concentration of electrons existing in the interface state. Further, in the film forming method which is actually performed, many impurity atoms and lattice defects are present in the light emitting layer, and these become electron trap levels.
【０００６】上述したＴＦＥＬ素子の構造から、ＴＦＥ
Ｌ素子の動作状態で外部からの電子の注入がないため、
発光層中の電子濃度は前記捕獲準位に電子がトラップさ
れて次第に減少していく。その結果、ＴＦＥＬ素子の輝
度は経時的に低下するという問題がある。From the structure of the TFEL element described above, TFE
Since there is no injection of electrons from the outside in the operating state of the L element,
The electron concentration in the light emitting layer gradually decreases as electrons are trapped in the trap level. As a result, there is a problem that the brightness of the TFEL element decreases over time.
【０００７】[0007]
【発明が解決しようとする課題】従来の二重絶縁型ＴＦ
ＥＬ素子の発行層中の電子濃度が経時的に変化したり、
発光領域が異なると、その電子濃度も変化する。このた
め、発光輝度の経時変化や発光開始電圧のバラツキを生
じる。[Problems to be Solved by the Invention] Conventional double insulation type TF
The electron concentration in the emitting layer of the EL element changes with time,
When the light emitting region is different, the electron concentration also changes. For this reason, the light emission luminance changes with time and the light emission start voltage varies.
【０００８】本発明は、従来構造におけるこれらの問題
を解決するのみならず、発光層中の電子濃度を外部から
の注入に依存せずに増加させ、発光輝度を向上させるこ
とが可能なＴＦＥＬ素子を提供しようとするものであ
る。The present invention not only solves these problems in the conventional structure, but also increases the electron concentration in the light emitting layer without depending on the injection from the outside to improve the emission brightness. Is to provide.
【０００９】[0009]
【課題を解決するための手段】本発明は、発光層と、前
記発光層の両面または片面に設けられた誘電体層とを具
備したＴＦＥＬ素子において、前記発光層と誘電体層の
間に二次電子放出機能を有する薄膜層を介在させたこと
を特徴とするＴＦＥＬ素子である。以下、本発明のＴＦ
ＥＬ素子を図１を参照して詳細に説明する。According to the present invention, there is provided a TFEL device comprising a light emitting layer and a dielectric layer provided on both sides or one side of the light emitting layer. A TFEL device having a thin film layer having a secondary electron emission function interposed. Hereinafter, the TF of the present invention
The EL element will be described in detail with reference to FIG.
【００１０】透明基板１上には、一方の電極２ａが設け
られている。一方の誘電体層３ａは、前記電極２ａ上に
形成されている。一方の二次電子放出機能を有する薄膜
層（二次電子放出層）４ａは、前記誘電体層３ａ上に形
成されている。発光層５は、前記二次電子放出層４ａ上
に形成されている。他方の二次電子放出層４ｂは、前記
発光層５上に形成されている。他方の誘電体層３ｂは、
前記他方の二次電子放出層４ｂを含む前記一方の誘電体
層３ａ上に形成されている。他方の電極２ｂは、前記他
方の誘電体層３ｂ上に形成されている。図示しない電源
は、前記電極２ａ、２ｂに接続されている。前記透明基
板１は、例えばガラスにより形成される。One electrode 2a is provided on the transparent substrate 1. One dielectric layer 3a is formed on the electrode 2a. One thin film layer (secondary electron emission layer) 4a having a secondary electron emission function is formed on the dielectric layer 3a. The light emitting layer 5 is formed on the secondary electron emitting layer 4a. The other secondary electron emission layer 4b is formed on the light emitting layer 5. The other dielectric layer 3b is
It is formed on the one dielectric layer 3a including the other secondary electron emission layer 4b. The other electrode 2b is formed on the other dielectric layer 3b. A power source (not shown) is connected to the electrodes 2a and 2b. The transparent substrate 1 is made of glass, for example.
【００１１】前記電極２ａ、２ｂの中で、前記透明基板
１側に配置される一方の電極２ａは例えばＩＴＯなどの
透明導電材料により形成される。他方の電極２ｂは、例
えばＡｌ、Ｃｕなどの通常の導電材料により形成され
る。One of the electrodes 2a and 2b, which is arranged on the transparent substrate 1 side, is formed of a transparent conductive material such as ITO. The other electrode 2b is formed of a normal conductive material such as Al or Cu.
【００１２】前記誘電体層３ａ、３ｂは、例えばＴａ2
Ｏ5 、Ｙ2 Ｏ3 、Ａｌ2 Ｏ3 、Ｓｉ3 Ｎ4 、ＳｉＡｌＯ
Ｎ、ＳｉＯＮ、ＴｉＯ2 、ＳｉＯ2 、ＺｒＯ2 、Ｎｂ2
Ｏ5、ＳｎＯ2 、ＢａＴｉＯ3 、ＰｂＴｉＯ3 、ＨｆＯ
2 の単独またはそれらの複合材料により形成される。な
お、誘電体層は前記発光層５の上下の両側に必ずしも配
置する必要がなく、前記発光層５の一方の側にみに配置
してもよい。この場合、前記誘電体層と前記発光層の間
のみに前記二次電子放出層が介在され、２つの電極のい
ずれか一方の電極は前記発光層表面に直接配置される構
造となる。The dielectric layers 3a and 3b are made of, for example, Ta 2
O 5 , Y 2 O 3 , Al 2 O 3 , Si 3 N 4 , SiAlO
N, SiON, TiO 2 , SiO 2 , ZrO 2 , Nb 2
O 5 , SnO 2 , BaTiO 3 , PbTiO 3 , HfO
It is formed by two materials alone or a composite material thereof. The dielectric layers do not necessarily have to be arranged on both upper and lower sides of the light emitting layer 5, and may be arranged only on one side of the light emitting layer 5. In this case, the secondary electron emission layer is interposed only between the dielectric layer and the light emitting layer, and one of the two electrodes is directly arranged on the surface of the light emitting layer.
【００１３】前記二次電子放出層４ａ、４ｂは、二次電
子放出比が４〜８程度の材料から形成されることが好ま
しく、特に化学的安定性、成膜の容易性等を考慮する
と、例えばＭｇＦ、ＭｇＯ、ＳｒＯ、ＳｒＦ2 、ＭｇＯ
−ＳｒＯ、ＢａＦ2 等から形成されることが好ましい。
前記二次電子放出層４ａ、４ｂの厚さは、３００ｎｍ以
下にすることが好ましい。この理由は、３００ｎｍを越
えると交流電圧を印加した時の前記発光層５に加わる電
界を低下させる恐れがある。前記二次電子放出層４ａ、
４ｂのより好ましい厚さは、１０〜７０ｎｍの範囲であ
る。The secondary electron emission layers 4a and 4b are preferably formed of a material having a secondary electron emission ratio of about 4 to 8, and in consideration of chemical stability and film formation, For example, MgF, MgO, SrO, SrF 2 , MgO
It is preferably formed from —SrO, BaF 2 or the like.
The thickness of the secondary electron emission layers 4a and 4b is preferably 300 nm or less. The reason is that if it exceeds 300 nm, the electric field applied to the light emitting layer 5 when an AC voltage is applied may be lowered. The secondary electron emission layer 4a,
A more preferable thickness of 4b is in the range of 10 to 70 nm.
【００１４】前記発光層５は、母体としてＺｎＳ、Ｚｎ
Ｓｅ、ＳｒＳ、ＣａＳ等が用いられ、発光中心としては
ＭｎまたはＴｍ、Ｓｍ、Ｃｅなどのランタニド元素が用
いられる。The light emitting layer 5 has ZnS, Zn as a base material.
Se, SrS, CaS or the like is used, and Mn or a lanthanide element such as Tm, Sm or Ce is used as the emission center.
【００１５】[0015]
【作用】本発明によれば、発光層と、前記発光層の両面
または片面に設けられた誘電体層とを具備したＴＦＥＬ
素子において、前記発光層と誘電体層の間に二次電子放
出層を介在させたことによって、発光層中の電子濃度を
外部からの注入に依存せずに増加させ、発光輝度の向上
等を達成したＴＦＥＬ素子を得ることができる。According to the present invention, a TFEL having a light emitting layer and a dielectric layer provided on both sides or one side of the light emitting layer.
In the device, by interposing the secondary electron emission layer between the light emitting layer and the dielectric layer, the electron concentration in the light emitting layer is increased without depending on the injection from the outside, and the emission brightness is improved. The achieved TFEL device can be obtained.
【００１６】すなわち、ＴＦＥＬ素子の膜面に対し、垂
直方向に交流電圧を印加し、その電圧を上げて前記誘電
体層間の発光層に１０6 Ｖ／ｃｍ前後の高電界を加える
と、例えばＺｎＳ、ＳｒＳ、ＣａＳを母材とする発光層
中の電子エネルギー分布は数ｅＶの電子が最も多いが、
中には数十または数百ｅＶのエネルギーを有する電子も
存在する。これらの電子が前記誘電体層と前記発光層の
間に介在させた二次電子放出層に衝突すると、その二次
電子放出層の表面は二次電子を放出する作用を有するよ
うになる。ただし、高エネルギーの電子が衝突する側は
プラス電位であるため、実際には二次電子は放出されな
い。しかるに、前記二次電子放出層中の電子は前記高エ
ネルギーの衝突によって励起された状態になる。そし
て、極性が反転すると前記とは反対の電界が生成され、
この励起状態にある電子が発光層中に放出される。した
がって、発光層中の電子濃度は界面準位から注入された
電子と前記二次電子が合算されるため、二次電子放出層
が存在しない場合に比べてより高くなる。That is, an AC voltage is applied in the vertical direction to the film surface of the TFEL element, and the voltage is raised to 10 6 in the light emitting layer between the dielectric layers. When a high electric field of about V / cm is applied, the electron energy distribution in the light emitting layer containing ZnS, SrS, and CaS as the base material has the largest number of electrons of several eV.
Some electrons have energies of tens or hundreds of eV. When these electrons collide with the secondary electron emission layer interposed between the dielectric layer and the light emitting layer, the surface of the secondary electron emission layer has a function of emitting secondary electrons. However, secondary electrons are not actually emitted because the side on which high energy electrons collide has a positive potential. However, the electrons in the secondary electron emission layer are excited by the high energy collision. Then, when the polarity is reversed, an electric field opposite to the above is generated,
The electrons in this excited state are emitted into the light emitting layer. Therefore, the electron concentration in the light emitting layer is higher than that in the case where the secondary electron emitting layer does not exist because the electrons injected from the interface state and the secondary electrons are added.
【００１７】このように本発明のＴＦＥＬ素子において
は、素子の外部回路から電子を注入することなく、発光
層中の電子濃度を上げることができる。このことは、発
光開始電圧を下げること、輝度の経時的低下を抑制する
こと、さらに輝度を向上させることに有効に働く。As described above, in the TFEL device of the present invention, the electron concentration in the light emitting layer can be increased without injecting electrons from the external circuit of the device. This effectively works to reduce the light emission start voltage, suppress the luminance from decreasing over time, and further improve the luminance.
【００１８】[0018]
【実施例】以下、本発明の実施例を前述した図１を参照
して詳細に説明する。 実施例１Embodiments of the present invention will be described in detail below with reference to FIG. Example 1
【００１９】図１において、透明基板１はガラスからな
り、一方の電極（透明電極）２ａは厚さ１７０ｎｍのＩ
ＴＯからなる。厚さ４００〜５００ｎｍのＴａ2 Ｏ5 か
らなる誘電体層３ａは、前記透明電極２ａ上に形成さ
れ、厚さ３０〜４０ｎｍのＭｇＯからなる二次電子放出
層４ａは前記誘電体層３ａ上には形成されている。厚さ
６００〜７００ｎｍのＺｎＳ：Ｍｎからなる発光層５
は、前記二次電子放出層４ａに形成されている。厚さ３
０〜４０ｎｍのＭｇＯからなる二次電子放出層４ｂは、
前記発光層５上に形成されている。厚さ４００〜５００
ｎｍのＴａ2 Ｏ5 からなる誘電体層３ｂは、前記二次電
子放出層４ｂ上に形成されている。Ａｌからなる電極２
ｂは、前記誘電体層３ｂ上に形成されている。 比較例１ 二次電子放出層を発光層とこの上下に配置した誘電体層
の間に介在させない以外、実施例１と同様な構造のＴＦ
ＥＬ素子を作製した。In FIG. 1, the transparent substrate 1 is made of glass, and one electrode (transparent electrode) 2a is I having a thickness of 170 nm.
Composed of TO. A dielectric layer 3a made of Ta 2 O 5 having a thickness of 400 to 500 nm is formed on the transparent electrode 2a, and a secondary electron emission layer 4a made of MgO having a thickness of 30 to 40 nm is placed on the dielectric layer 3a. Has been formed. Light-emitting layer 5 made of ZnS: Mn having a thickness of 600 to 700 nm
Is formed on the secondary electron emission layer 4a. Thickness 3
The secondary electron emission layer 4b made of 0 to 40 nm MgO is
It is formed on the light emitting layer 5. Thickness 400-500
A dielectric layer 3b made of Ta 2 O 5 having a thickness of nm is formed on the secondary electron emission layer 4b. Electrode 2 made of Al
b is formed on the dielectric layer 3b. Comparative Example 1 TF having the same structure as in Example 1 except that the secondary electron emission layer was not interposed between the light emitting layer and the dielectric layers arranged above and below this layer.
An EL device was produced.
【００２０】本実施例１および比較例１のＴＦＥＬ素子
の透明電極２ａとＡｌ電極２ｂの間に周波数１ｋＨｚの
交流電圧を印加し、輝度−電圧特性を調べた。その結果
を図２に示す。図２から明らかなように実施例１のＴＦ
ＥＬ素子は、二次電子放出層のない比較例１のＴＦＥＬ
素子に比べて発光開始電圧が５５Ｖ低く、かつ飽和輝度
が６０％向上することがわかる。An AC voltage having a frequency of 1 kHz was applied between the transparent electrode 2a and the Al electrode 2b of the TFEL elements of Example 1 and Comparative Example 1 to examine the luminance-voltage characteristics. The result is shown in FIG. As is clear from FIG. 2, the TF of Example 1
The EL element is the TFEL of Comparative Example 1 without the secondary electron emission layer.
It can be seen that the light emission starting voltage is 55 V lower than that of the device, and the saturation luminance is improved by 60%.
【００２１】また、本実施例１および比較例１のＴＦＥ
Ｌ素子の透明電極２ａとＡｌ電極２ｂの間に周波数１ｋ
Ｈｚの交流電圧を印加し、初期輝度８５０ｎｔの発光状
態を１時間維持した後の発光開始電圧の変化を測定し
た。その結果、二次電子放出層のない比較例１のＴＦＥ
Ｌ素子では、初期の発光開始電圧が１４５Ｖであった
が、１時間後の発光開始電圧は１９５Ｖに上昇した。こ
れに対し、二次電子放出層を有する実施例１のＴＦＥＬ
素子では初期の発光開始電圧が９５Ｖ、１時間後の発光
開始電圧は１００Ｖであった。したがって、発光開始電
圧の上昇率は比較例１のＴＦＥＬ素子が３４％であるの
に対し、実施例１のＴＦＥＬ素子は僅か５％に止まって
いることがわかる。In addition, the TFEs of Example 1 and Comparative Example 1
Frequency 1k between the transparent electrode 2a and the Al electrode 2b of the L element
A change in the light emission start voltage was measured after applying an AC voltage of Hz and maintaining the light emission state with an initial luminance of 850 nt for 1 hour. As a result, the TFE of Comparative Example 1 without the secondary electron emission layer
In the L element, the initial light emission start voltage was 145V, but the light emission start voltage after 1 hour increased to 195V. On the other hand, the TFEL of Example 1 having the secondary electron emission layer
In the device, the initial light emission start voltage was 95V, and the light emission start voltage after 1 hour was 100V. Therefore, it can be seen that the increase rate of the light emission start voltage is 34% in the TFEL element of Comparative Example 1, whereas it is only 5% in the TFEL element of Example 1.
【００２２】さらに、実施例１および比較例１のＴＦＥ
Ｌ素子について初期輝度を１００として、その低下率を
経時的な調べたところ、図３に示す結果が得られた。１
０時間後の低下率は、二次電子放出層のない比較例１の
ＴＦＥＬ素子が４８％低下しているのに対し、二次電子
放出層を有する実施例１のＴＦＥＬ素子は８％に止まっ
ていることがわかる。 実施例２ ＢａＦ2 からなる二次電子放出層を用いた以外、実施例
１と同様なＴＦＥＬ素子を作製した。Furthermore, the TFE of Example 1 and Comparative Example 1
When the initial luminance of the L element was set to 100 and its reduction rate was examined over time, the results shown in FIG. 3 were obtained. 1
The reduction rate after 0 hour was 48% in the TFEL element of Comparative Example 1 having no secondary electron emission layer, whereas it was 8% in the TFEL element of Example 1 having the secondary electron emission layer. You can see that Example 2 A TFEL device similar to that of Example 1 was prepared, except that the secondary electron emission layer made of BaF 2 was used.
【００２３】実施例２および前述した比較例１のＴＦＥ
Ｌ素子について、実施例１と同様な方法により輝度−電
圧特性、発光開始電圧の上昇率および１０時間後の輝度
低下率を調べた。その結果、実施例２のＴＦＥＬ素子は
発光開始電圧が比較例１のＴＦＥＬ素子に比べて３０Ｖ
低く、発光開始電圧の上昇率では１２％となり、そして
１０時間後の輝度低下率は１８％となった。 実施例３ 発光層をＺｎＳ：Ｔｂ、誘電体層をＳｉＯＮ、二次電子
放出層をＭｇＯで形成した以外、実施例１と同様な構造
のＴＦＥＬ素子を作製した。 比較例２TFE of Example 2 and the above-mentioned Comparative Example 1
With respect to the L element, the luminance-voltage characteristics, the increase rate of the light emission start voltage, and the luminance decrease rate after 10 hours were examined by the same methods as in Example 1. As a result, the TFEL device of Example 2 had an emission start voltage of 30 V as compared with the TFEL device of Comparative Example 1.
The rate of increase in the light emission starting voltage was 12%, and the rate of decrease in luminance after 10 hours was 18%. Example 3 A TFEL device having the same structure as in Example 1 was prepared, except that the light emitting layer was formed of ZnS: Tb, the dielectric layer was formed of SiON, and the secondary electron emission layer was formed of MgO. Comparative example 2
【００２４】発光層をＺｎＳ：Ｔｂ、誘電体層をＳｉＯ
Ｎで形成し、二次電子放出層を前記を発光層と誘電体層
の間に介在させない以外、実施例１と同様な構造のＴＦ
ＥＬ素子を作製した。The light emitting layer is ZnS: Tb, and the dielectric layer is SiO.
TF having the same structure as in Example 1 except that it is formed of N and the secondary electron emission layer is not interposed between the light emitting layer and the dielectric layer.
An EL device was produced.
【００２５】本実施例３および比較例２のＴＦＥＬ素子
の透明電極とＡｌ電極の間に周波数１ｋＨｚの交流電圧
を印加し、輝度−電圧特性を調べた。その結果を下記表
１に示す。 表１ 実施例３ 比較例２ 発光開始電圧 １００ｖ １６０Ｖ 飽和輝度 ２８００ｎｔ １８００ｎｔ また、実施例３のＴＦＥＬ素子は発光開始電圧と輝度の
経時変化が実施例１と同様な結果となり、二次電子放出
層の効果が明瞭に認められた。An AC voltage having a frequency of 1 kHz was applied between the transparent electrode and the Al electrode of the TFEL elements of Example 3 and Comparative Example 2 to examine the luminance-voltage characteristics. The results are shown in Table 1 below. Table 1 Example 3 Comparative example 2 Light emission starting voltage 100v 160V Saturation luminance 2800nt 1800nt In addition, the TFEL device of Example 3 has the same results as those of Example 1 with respect to the change of the light emission starting voltage and the luminance over time, and the secondary electron emission layer The effect was clearly recognized.
【００２６】[0026]
【発明の効果】以上詳述したごとく、本発明に係わるＴ
ＦＥＬ素子によれば発光層と誘電体層の間に二次電子を
放出する機能を有する薄層を介在させることによって発
光開始電圧を低くすることができ、かつ発光開始電圧の
経時的上昇および発光輝度の経時的低下を抑制でき、さ
らに発光輝度を向上でき等顕著な効果を奏する。As described above in detail, the T according to the present invention is
According to the FEL element, the light emission starting voltage can be lowered by interposing a thin layer having a function of emitting secondary electrons between the light emitting layer and the dielectric layer, and the light emission starting voltage can be increased with time. It is possible to suppress a decrease in luminance over time, and further to achieve remarkable effects such as improvement in emission luminance.
【図１】本発明の実施例１におけるＴＦＥＬ素子を示す
断面図。FIG. 1 is a sectional view showing a TFEL element according to Example 1 of the present invention.
【図２】実施例１および比較例１のＴＦＥＬ素子におけ
る輝度−電圧特性を示す線図。FIG. 2 is a diagram showing luminance-voltage characteristics in the TFEL elements of Example 1 and Comparative Example 1.
【図３】実施例１および比較例１のＴＦＥＬ素子におけ
る発光輝度の経時的変化を示す線図。FIG. 3 is a diagram showing a change with time in emission luminance of the TFEL elements of Example 1 and Comparative Example 1.
１…透明基板、２ａ、２ｂ…電極、３ａ、３ｂ…誘電体
層、４ａ、４ｂ…二次電子放出層、５…発光層。1 ... Transparent substrate, 2a, 2b ... Electrode, 3a, 3b ... Dielectric layer, 4a, 4b ... Secondary electron emission layer, 5 ... Light emitting layer.
Claims (1)
に設けられた誘電体層とを具備した薄膜エレクトロルミ
ネッセンス素子において、 前記発光層と誘電体層の間に二次電子放出機能を有する
薄膜層を介在させたことを特徴とする薄膜エレクトロル
ミネッセンス素子。1. A thin film electroluminescent device comprising a light emitting layer and a dielectric layer provided on both surfaces or one surface of the light emitting layer, wherein the thin film electroluminescent element has a secondary electron emitting function between the light emitting layer and the dielectric layer. A thin film electroluminescent device having a thin film layer interposed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4002106A JPH05190284A (en) | 1992-01-09 | 1992-01-09 | Thin film electroluminescence element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4002106A JPH05190284A (en) | 1992-01-09 | 1992-01-09 | Thin film electroluminescence element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05190284A true JPH05190284A (en) | 1993-07-30 |
Family
ID=11520099
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4002106A Pending JPH05190284A (en) | 1992-01-09 | 1992-01-09 | Thin film electroluminescence element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05190284A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001223073A (en) * | 2000-02-07 | 2001-08-17 | Tdk Corp | Composite substrate and el element using the same |
| US7445946B2 (en) | 2002-04-30 | 2008-11-04 | Semiconductor Energy Laboratory Co., Ltd. | Method of driving a light emitting device |
| US7723721B2 (en) | 2001-11-09 | 2010-05-25 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting device having TFT |
-
1992
- 1992-01-09 JP JP4002106A patent/JPH05190284A/en active Pending
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4563539B2 (en) * | 2000-02-07 | 2010-10-13 | アイファイヤー アイピー コーポレイション | Composite substrate and EL device using the same |
| JP2001223073A (en) * | 2000-02-07 | 2001-08-17 | Tdk Corp | Composite substrate and el element using the same |
| US9577016B2 (en) | 2001-11-09 | 2017-02-21 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting device |
| US7723721B2 (en) | 2001-11-09 | 2010-05-25 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting device having TFT |
| US8324618B2 (en) | 2001-11-09 | 2012-12-04 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting device |
| US9054199B2 (en) | 2001-11-09 | 2015-06-09 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting device |
| US9905624B2 (en) | 2001-11-09 | 2018-02-27 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting device |
| US10461140B2 (en) | 2001-11-09 | 2019-10-29 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting device |
| US10680049B2 (en) | 2001-11-09 | 2020-06-09 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting device |
| US11063102B2 (en) | 2001-11-09 | 2021-07-13 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting device |
| US8101439B2 (en) | 2002-04-30 | 2012-01-24 | Semiconductor Energy Laboratory Co., Ltd. | Method of driving a light emitting device |
| US8502241B2 (en) | 2002-04-30 | 2013-08-06 | Semiconductor Energy Laboratory Co., Ltd. | Method of driving a light emitting device |
| US9006757B2 (en) | 2002-04-30 | 2015-04-14 | Semiconductor Energy Laboratory Co., Ltd. | Method of driving a light emitting device |
| US7445946B2 (en) | 2002-04-30 | 2008-11-04 | Semiconductor Energy Laboratory Co., Ltd. | Method of driving a light emitting device |
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