JPH04328295A - Organic electroluminescence(el) element - Google Patents
Organic electroluminescence(el) elementInfo
- Publication number
- JPH04328295A JPH04328295A JP3097653A JP9765391A JPH04328295A JP H04328295 A JPH04328295 A JP H04328295A JP 3097653 A JP3097653 A JP 3097653A JP 9765391 A JP9765391 A JP 9765391A JP H04328295 A JPH04328295 A JP H04328295A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- film thickness
- transport layer
- luminance
- electron transport
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000005401 electroluminescence Methods 0.000 title claims description 3
- 230000005525 hole transport Effects 0.000 claims abstract description 16
- 150000002894 organic compounds Chemical class 0.000 claims description 3
- -1 aluminum quinolinol Chemical compound 0.000 claims description 2
- DCZNSJVFOQPSRV-UHFFFAOYSA-N n,n-diphenyl-4-[4-(n-phenylanilino)phenyl]aniline Chemical class C1=CC=CC=C1N(C=1C=CC(=CC=1)C=1C=CC(=CC=1)N(C=1C=CC=CC=1)C=1C=CC=CC=1)C1=CC=CC=C1 DCZNSJVFOQPSRV-UHFFFAOYSA-N 0.000 claims description 2
- 150000004866 oxadiazoles Chemical class 0.000 claims description 2
- 239000010408 film Substances 0.000 abstract description 49
- 239000000463 material Substances 0.000 abstract description 10
- 229910052751 metal Inorganic materials 0.000 abstract description 10
- 239000002184 metal Substances 0.000 abstract description 10
- 239000010409 thin film Substances 0.000 abstract description 5
- 238000000034 method Methods 0.000 abstract description 2
- 238000010030 laminating Methods 0.000 abstract 1
- 239000000758 substrate Substances 0.000 description 7
- 238000000295 emission spectrum Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- TVIVIEFSHFOWTE-UHFFFAOYSA-K tri(quinolin-8-yloxy)alumane Chemical compound [Al+3].C1=CN=C2C([O-])=CC=CC2=C1.C1=CN=C2C([O-])=CC=CC2=C1.C1=CN=C2C([O-])=CC=CC2=C1 TVIVIEFSHFOWTE-UHFFFAOYSA-K 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- KLCLIOISYBHYDZ-UHFFFAOYSA-N 1,4,4-triphenylbuta-1,3-dienylbenzene Chemical class C=1C=CC=CC=1C(C=1C=CC=CC=1)=CC=C(C=1C=CC=CC=1)C1=CC=CC=C1 KLCLIOISYBHYDZ-UHFFFAOYSA-N 0.000 description 1
- 101000582320 Homo sapiens Neurogenic differentiation factor 6 Proteins 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 102100030589 Neurogenic differentiation factor 6 Human genes 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 235000010290 biphenyl Nutrition 0.000 description 1
- 239000004305 biphenyl Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000013522 chelant Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007850 fluorescent dye Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 238000004020 luminiscence type Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- ZUOUZKKEUPVFJK-UHFFFAOYSA-N phenylbenzene Natural products C1=CC=CC=C1C1=CC=CC=C1 ZUOUZKKEUPVFJK-UHFFFAOYSA-N 0.000 description 1
- MCJGNVYPOGVAJF-UHFFFAOYSA-N quinolin-8-ol Chemical compound C1=CN=C2C(O)=CC=CC2=C1 MCJGNVYPOGVAJF-UHFFFAOYSA-N 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/80—Constructional details
- H10K50/85—Arrangements for extracting light from the devices
Landscapes
- Electroluminescent Light Sources (AREA)
- Luminescent Compositions (AREA)
Abstract
Description
【0001】0001
【技術分野】本発明は、電流の注入によって発光する物
質のエレクトロルミネッセンス(以下、ELという)を
利用して、かかる物質を薄膜に形成したEL層を備えた
EL素子に関し、特に発光物質が有機化合物である有機
EL素子に関する。TECHNICAL FIELD The present invention relates to an EL device that utilizes electroluminescence (hereinafter referred to as EL) of a substance that emits light when an electric current is injected, and has an EL layer formed of such a substance in a thin film. The present invention relates to an organic EL element that is a compound.
【0002】0002
【背景技術】この種の有機EL素子として、図1に示す
ように、金属陰極1と透明陽極2との間に、それぞれ有
機化合物からなり互いに積層された発光体薄膜からなる
EL層3及び正孔輸送層4が配された2層構造のものや
、図2に示すように、金属陰極1と透明陽極2との間に
互いに積層された有機化合物からなる電子輸送層5、E
L層3及び正孔輸送層4が配された3層構造のものが知
られている。ここで、正孔輸送層4は陽極から正孔を注
入させ易くする機能と電子をブロックする機能とを有し
、電子輸送層5は陰極から電子を注入させ易くする機能
を有している。BACKGROUND ART As shown in FIG. 1, this type of organic EL device has an EL layer 3 consisting of a luminescent thin film made of an organic compound and laminated on each other, and an anode layer 3 between a metal cathode 1 and a transparent anode 2. There may be a two-layer structure in which a hole transport layer 4 is arranged, or as shown in FIG.
A three-layer structure including an L layer 3 and a hole transport layer 4 is known. Here, the hole transport layer 4 has a function of facilitating injection of holes from the anode and a function of blocking electrons, and the electron transport layer 5 has a function of facilitating injection of electrons from the cathode.
【0003】これら有機EL素子において、透明陽極2
の外側にはガラス基板6が配されており、金属陰極1か
ら注入された電子と透明陽極2からEL層3へ注入され
た正孔との再結合によって励起子が生じ、EL層におけ
る正孔輸送層との境界面近傍にて励起子が放射失活する
過程で光を放ち、この光が透明陽極2及びガラス基板6
を介して外部に放出される(特開昭59−194393
号公報及び特開昭63−295695号公報参照)。[0003] In these organic EL devices, a transparent anode 2
A glass substrate 6 is disposed on the outside of the EL layer, and excitons are generated by recombination of electrons injected from the metal cathode 1 and holes injected from the transparent anode 2 into the EL layer 3, and holes in the EL layer In the process of radiation deactivation of excitons near the interface with the transport layer, light is emitted, and this light is transmitted to the transparent anode 2 and the glass substrate 6.
is released to the outside through the
(See Japanese Patent Application Laid-Open No. 63-295695).
【0004】しかしながら、上述した構成の従来の有機
EL素子は、EL層内でエネルギー消費し低電圧で発光
するけれども、EL層が500Å以下と薄い膜厚の場合
、一般に寿命が短い。例えば、図1に示す2層構造で膜
厚300ÅのEL層を有する有機EL素子を初期輝度4
00cd/m2となるように連続発光させると、該素子
は100時間以下で輝度が半減し劣化する。[0004] However, although the conventional organic EL element having the above-mentioned structure consumes energy within the EL layer and emits light at a low voltage, it generally has a short lifespan when the EL layer has a thin film thickness of 500 Å or less. For example, an organic EL element having a two-layer structure and a 300 Å thick EL layer shown in FIG. 1 has an initial luminance of 4
When continuously emitting light at a rate of 00 cd/m2, the device's brightness decreases by half and deteriorates in 100 hours or less.
【0005】一方、EL層の膜厚を大きくすると定電圧
駆動であっても膜厚の増大とともにその輝度は減少する
。EL素子の発光原理から考えると輝度は印加電流に比
例すると考えられるが、実際は異なる。On the other hand, when the thickness of the EL layer is increased, its brightness decreases as the thickness increases even when driven at a constant voltage. Considering the light emission principle of an EL element, it is thought that the brightness is proportional to the applied current, but this is actually different.
【0006】[0006]
【発明の目的】本発明は、長期間安定して高輝度発光す
る有機EL素子を提供することを目的とする。OBJECTS OF THE INVENTION An object of the present invention is to provide an organic EL element that emits light with high brightness stably for a long period of time.
【0007】[0007]
【発明の構成】本発明による有機EL素子は、有機化合
物からなり互いに積層された電子輸送層、EL層及び正
孔輸送層が陰極及び陽極間に配されたものであって、電
子輸送層は、膜厚輝度減衰特性の2次極大値を生ずる膜
厚を含みかつその振幅がその収束輝度値を越える輝度を
生ずる範囲内の膜厚を有していることを特徴とする。[Structure of the Invention] The organic EL device according to the present invention includes an electron transport layer, an EL layer, and a hole transport layer made of organic compounds and stacked on each other and arranged between a cathode and an anode, and the electron transport layer is , the film thickness is within a range that includes a film thickness that produces a second-order maximum value of the film thickness luminance attenuation characteristic, and that produces a luminance whose amplitude exceeds its convergent luminance value.
【0008】[0008]
【実施例】以下に本発明による実施例を図を参照しつつ
説明する。本実施例の有機EL素子は、図2に示すもの
と同様な、一対の金属陰極1と透明陽極2との間に電子
輸送層5、EL層3及び正孔輸送層4を薄膜として積層
、成膜した3層構造のものである。例えば陰極1には、
アルミニウム、マグネシウム、インジウム、銀又は各々
の合金等の仕事関数が小さな金属からなり厚さが約10
0〜5000Å程度のものが用い得る。また、例えば陽
極2には、インジウムすず酸化物(以下、ITOという
)等の仕事関数の大きな導電性材料からなり厚さが10
00〜3000Å程度で、又は金で厚さが 800〜1
500Å程度のものが用い得る。Embodiments Examples of the present invention will be described below with reference to the drawings. The organic EL device of this example is similar to that shown in FIG. 2, in which an electron transport layer 5, an EL layer 3, and a hole transport layer 4 are laminated as thin films between a pair of metal cathodes 1 and a transparent anode 2. It has a three-layer structure. For example, for cathode 1,
Made of a metal with a small work function such as aluminum, magnesium, indium, silver, or an alloy of each, and has a thickness of about 10
A thickness of about 0 to 5000 Å can be used. Further, for example, the anode 2 is made of a conductive material with a large work function such as indium tin oxide (hereinafter referred to as ITO) and has a thickness of 10
00 to 3000 Å or gold with a thickness of 800 to 1
A thickness of about 500 Å can be used.
【0009】本発明による有機EL素子の電子輸送層5
としては、オキサジアゾール誘導体であるBu−PBD
[2−(4´−tert−Butylphenyl)−
5−(biphenyl)−1,3,4−oxadia
zole](以下、PBDという)が好ましく用いられ
得る。本発明による有機EL素子のEL層3を形成する
有機蛍光化合物の具体的な例としては、アルミキノリノ
ール錯体すなわちAlオキシンキレート(以下、Alq
3という)、テトラフェニルブタジエン誘導体等が用い
られ得る。EL層3の膜厚は200Å以下で発光する限
度以上の膜厚が好ましい。正孔輸送層4には、トリフェ
ニルジアミン誘導体であるN,N´−ジフェニル−N,
N´−ビス(3メチルフェニル)−1,1´−ビフェニ
ル−4,4´−ジアミン(以下、TPDという)が好ま
しく用いられ、更にCTM(Carrier Tran
sporting Materials )として知ら
れる化合物を単独、もしくは混合物として用い得る。Electron transport layer 5 of organic EL device according to the present invention
As Bu-PBD, which is an oxadiazole derivative
[2-(4'-tert-Butylphenyl)-
5-(biphenyl)-1,3,4-oxadia
zole] (hereinafter referred to as PBD) can be preferably used. A specific example of the organic fluorescent compound forming the EL layer 3 of the organic EL device according to the present invention is an aluminum quinolinol complex, that is, Al oxine chelate (hereinafter referred to as Alq
3), tetraphenylbutadiene derivatives, etc. may be used. The thickness of the EL layer 3 is preferably 200 Å or less, which is at least the limit for emitting light. The hole transport layer 4 contains N,N′-diphenyl-N, which is a triphenyldiamine derivative.
N'-bis(3methylphenyl)-1,1'-biphenyl-4,4'-diamine (hereinafter referred to as TPD) is preferably used, and CTM (Carrier Tran
Compounds known as sporting materials may be used alone or in mixtures.
【0010】発明者は、3層構造の有機EL素子の電子
輸送層及びEL層の合計膜厚、発光スペクトル及び輝度
並びに視角の研究の結果、輝度と電子輸送層膜厚の間に
は輝度の膜厚依存性が、輝度の視角依存性があることを
知見した。すなわち、図3に示すように有機EL素子の
ガラス基板6側表面を目視者が見る角度によって発光ス
ペクトル及び輝度が変化する。目視者にとってEL層内
の発光源Pの1点から発した光には、図中の直接基板6
へ向かう経路A及び背面の金属電極1で反射し基板6へ
向かう経路Bの2つの光が含まれる。この2つの経路の
光は以下の数式1に示す光路差L、さらに数式2に示す
位相差ηyを保持しているので、互いに干渉する。(両
数式中、nはEL層3の屈折率を、yは発光源Pから金
属電極1までの距離を、θはEL層内における表示表面
の法線からそれる視角を、λは波長をそれぞれ示す。以
下、同じ)。[0010] As a result of research on the total film thickness, emission spectrum, brightness, and viewing angle of the electron transport layer and EL layer of a three-layer organic EL element, the inventor found that there is a difference between the brightness and the electron transport layer film thickness. We found that the film thickness dependence and the luminance dependence on the viewing angle. That is, as shown in FIG. 3, the emission spectrum and brightness change depending on the angle at which a viewer views the surface of the organic EL element on the glass substrate 6 side. For the viewer, the light emitted from one point of the light emitting source P in the EL layer has a direct contact with the substrate 6 in the figure.
Two types of light are included: a path A that goes toward the substrate 6, and a path B that is reflected by the metal electrode 1 on the back surface and goes toward the substrate 6. Since the lights in these two paths have an optical path difference L shown in the following equation 1 and a phase difference ηy shown in equation 2, they interfere with each other. (In both formulas, n is the refractive index of the EL layer 3, y is the distance from the light emitting source P to the metal electrode 1, θ is the viewing angle deviating from the normal to the display surface in the EL layer, and λ is the wavelength. (The same applies below).
【0011】[0011]
【数1】[Math 1]
【0012】0012
【数2】[Math 2]
【0013】よって、干渉効果としてその強度I(y,
λ)は数式3の如く表せる。Therefore, the intensity I(y,
λ) can be expressed as in Equation 3.
【0014】[0014]
【数3】[Math 3]
【0015】EL層中での発光強度f(y)の分布は、
図4に示すように正孔輸送層4の境界面においては強く
金属電極1に向かうほど減少し、膜厚に関する指数関数
分布として数式4の如く表せ、EL層全体としては数式
5の如く正規化できる(両数式中、dは発光源から金属
電極までの距離を、εは発光強度分布パラメータを、k
は定数をそれぞれ示す。以下、同じ)。The distribution of emission intensity f(y) in the EL layer is as follows:
As shown in FIG. 4, at the boundary of the hole transport layer 4, the decrease is stronger toward the metal electrode 1, and can be expressed as an exponential distribution with respect to the film thickness as shown in Equation 4, and for the entire EL layer, it is normalized as shown in Equation 5. (In both formulas, d is the distance from the emission source to the metal electrode, ε is the emission intensity distribution parameter, and k
represent constants, respectively. same as below).
【0016】[0016]
【数4】[Math 4]
【0017】[0017]
【数5】[Math 5]
【0018】発光源自体の発光スペクトルの強度分布F
(λ)は発光体特有の波長λの関数として表せる。よっ
て、目視者によって実際に観察されるEL素子の発光強
度T(λ,θ,d)は数式6のように表せる。Intensity distribution F of the emission spectrum of the light source itself
(λ) can be expressed as a function of the wavelength λ specific to the light emitter. Therefore, the emission intensity T(λ, θ, d) of the EL element actually observed by a viewer can be expressed as shown in Equation 6.
【0019】[0019]
【数6】[Math 6]
【0020】ここで、EL素子の発光強度T(λ,θ,
d)を確認するために、合計膜厚(y=d)6000Å
とし発光強度分布パラメータεを200Åと一定にした
PBDからなる電子輸送層及びAlq3からなるEL層
を含む有機EL素子を作成し、視角θを0°から75°
まで種々変化させてその発光強度の試験を行った。図5
は、発光波長に対する発光強度分布を示す。かかる発光
強度分布と上記数式6の発光強度T(λ,θ,d)とが
略一致することが確認された。図から明らかなように、
目視者にとっては視角0°から75°までEL素子表示
面を見る方向によって色彩が順次異なるように見える。Here, the emission intensity T(λ, θ,
To confirm d), the total film thickness (y = d) was 6000 Å.
An organic EL device including an electron transport layer made of PBD and an EL layer made of Alq3 with a constant emission intensity distribution parameter ε of 200 Å was fabricated, and the viewing angle θ was varied from 0° to 75°.
The luminescence intensity was tested with various changes. Figure 5
shows the emission intensity distribution with respect to the emission wavelength. It was confirmed that this emission intensity distribution and the emission intensity T (λ, θ, d) of Equation 6 above substantially matched. As is clear from the figure,
To the viewer, the colors appear to vary sequentially depending on the direction in which the EL element display surface is viewed from a viewing angle of 0° to 75°.
【0021】さらに、実用に沿うように、波長λに対し
て特定値で感応する目視者または光検出器の視感度特性
E(λ)を考慮する。例えば視感度特性E(λ)を正規
分布とすると、かかる感度特性内おける電子輸送層及び
EL素子の輝度特性L(d)は、数式7のようにdの関
数として表せる(Kは定数を示す。)Furthermore, in order to be practical, consideration is given to the visibility characteristic E(λ) of a viewer or a photodetector that is sensitive to a wavelength λ at a specific value. For example, if the visibility characteristic E(λ) is a normal distribution, the luminance characteristic L(d) of the electron transport layer and the EL element within the sensitivity characteristic can be expressed as a function of d as shown in Equation 7 (K indicates a constant .)
【0022】[0022]
【数7】[Math 7]
【0023】図6は、PBDからなる電子輸送層及びA
lq3からなるEL層(θ=0,n=1.7)について
これらの合計膜厚の内、電子輸送層を0Åから8000
Åにわたって変化させ計算した場合の膜厚に対する輝度
/電流特性の膜厚輝度減衰(特性)曲線を示しており、
この減衰曲線が有機EL素子における輝度の膜厚依存性
を示している。FIG. 6 shows an electron transport layer made of PBD and a
Of these total film thicknesses for the EL layer (θ=0, n=1.7) consisting of lq3, the electron transport layer is 0 to 8000 Å.
It shows the film thickness brightness attenuation (characteristic) curve of the brightness/current characteristics against the film thickness when calculated by varying the film thickness over Å.
This attenuation curve shows the film thickness dependence of brightness in the organic EL element.
【0024】かかる有機EL素子の輝度の膜厚依存性を
確認するための有機EL素子を作成し試験を行うと、図
6と同様な減衰特性の結果が得られる。かかる有機EL
素子は、図6に示すように、最小膜厚かつ最大輝度を示
しこれを1次極大値として順次次数が増加(膜厚増加)
するにつれて周期的に輝度の極大値が現れ、この極大値
が減少する膜厚輝度減衰曲線の特性すなわち、輝度の電
子輸送層の膜厚依存性を示している。なお、実測した膜
厚輝度減衰曲線は、有機EL素子に膜厚500ÅのTP
D正孔輸送層を用いているために特性曲線全体が計算に
よる図6のものに比して変移する。When an organic EL element is prepared and tested to confirm the dependence of luminance on film thickness of such an organic EL element, results of attenuation characteristics similar to those shown in FIG. 6 are obtained. Such organic EL
As shown in Fig. 6, the element exhibits the minimum film thickness and maximum brightness, and this is taken as the first maximum value, and the order increases sequentially (film thickness increases).
As the brightness increases, the maximum value of the brightness appears periodically, and this maximum value decreases, indicating the characteristic of the film thickness brightness attenuation curve, that is, the dependence of the brightness on the film thickness of the electron transport layer. The actually measured film thickness luminance decay curve is based on a TP film with a film thickness of 500 Å in the organic EL element.
Due to the use of the D hole transport layer, the entire characteristic curve shifts compared to the calculated one in FIG.
【0025】かかる有機EL素子の内、好適な実施例は
、図6から明らかなようにAlq3のEL層膜厚を20
0Åと固定し、電子輸送層の厚さを2次極大値Cに対応
する2000ű300Åとした有機EL素子である。
この膜厚範囲の電子輸送層とすることによって、輝度を
確保しつつ高印加電流からEL層を守ることができる。
すなわち、この膜厚範囲は、図6に示す電子輸送層及び
EL層材質に応じた膜厚に対する輝度/電流特性の膜厚
輝度減衰曲線の2番目に高い輝度の2次極大値振幅がそ
の収束する輝度値(収束輝度値)を越える範囲Dであり
、特に電子輸送層を膜厚輝度減衰曲線における2番目に
高い輝度を示す2次極大値近傍に対応する膜厚とするこ
とにより高信頼性かつ高輝度の有機EL素子が得られ、
好ましい。As is clear from FIG. 6, in a preferred embodiment of such an organic EL device, the thickness of the EL layer of Alq3 is 20%.
This is an organic EL device in which the thickness of the electron transport layer is fixed at 0 Å, and the thickness of the electron transport layer is set to 2000 ű300 Å, which corresponds to the secondary maximum value C. By forming the electron transport layer within this thickness range, the EL layer can be protected from high applied current while ensuring brightness. In other words, in this film thickness range, the second maximum amplitude of the second highest luminance of the film thickness luminance attenuation curve of the luminance/current characteristics with respect to the film thickness according to the material of the electron transport layer and EL layer shown in FIG. 6 converges. The range D exceeds the luminance value (convergent luminance value) of And a high brightness organic EL element can be obtained,
preferable.
【0026】さらに、視角の変化は膜厚が変化すること
と等しいので、電子輸送層を膜厚輝度減衰曲線における
2次極大値近傍に対応する膜厚と設定することにより、
視角が多少変化しても輝度の変化が小さい高輝度の有機
EL素子が得られる。図7は、上記したPBD電子輸送
層及びAlq3EL層及びTPD正孔輸送層の3層構造
の有機EL素子の各々について、視角度に対する輝度/
電流の相対値を測定した結果を示す。試験した複数の有
機EL素子は、膜厚500ÅのTPDの正孔輸送層、膜
厚200ÅのAlq3のEL層、及びが膜厚650Åか
ら7225ÅのPBDの電子輸送層の3層構造を有する
ものである。図から明らかなように、1次、2次及び3
次極大値に対応する電子輸送層膜厚650Å、2000
Å及び4065Åを有する有機EL素子は、視角の増加
に従って輝度が増加する視角による依存が少ない傾向に
あることが分かる。よって、膜厚輝度減衰曲線における
各々の振幅の極大値に対応するEL層及び電子輸送層膜
厚であれば、輝度及び発光スペクトルの視角依存性が小
さくなり視角による色彩の変化も小さい有機EL素子が
得られる。電子輸送層を膜厚輝度減衰曲線における2番
目に高い輝度を示す2次極大値近傍に対応する膜厚とす
る上記実施例も、輝度の視角依存性が小さい。Furthermore, since a change in viewing angle is equivalent to a change in film thickness, by setting the electron transport layer to a film thickness corresponding to the vicinity of the second-order maximum value in the film thickness brightness attenuation curve,
A high-luminance organic EL element whose luminance changes little even when the viewing angle changes somewhat can be obtained. FIG. 7 shows the brightness/brightness versus viewing angle for each of the three-layer organic EL elements of the above-mentioned PBD electron transport layer, Alq3EL layer, and TPD hole transport layer.
The results of measuring the relative value of current are shown. The organic EL devices tested had a three-layer structure: a hole transport layer of TPD with a thickness of 500 Å, an EL layer of Alq3 with a thickness of 200 Å, and an electron transport layer of PBD with a thickness of 650 Å to 7225 Å. be. As is clear from the figure, primary, secondary and tertiary
Electron transport layer thickness 650 Å, 2000 Å corresponding to the next maximum value
Å and 4065 Å, the brightness tends to be less dependent on the viewing angle, where the brightness increases as the viewing angle increases. Therefore, if the film thickness of the EL layer and electron transport layer corresponds to the maximum value of each amplitude in the film thickness brightness attenuation curve, the viewing angle dependence of the brightness and emission spectrum will be small, and the organic EL element will have a small change in color depending on the viewing angle. is obtained. The above embodiment in which the electron transport layer has a film thickness corresponding to the vicinity of the second maximum value indicating the second highest luminance in the film thickness luminance attenuation curve also has a small viewing angle dependence of luminance.
【0027】ここで、実施例として膜厚輝度減衰曲線に
おける2次極大値近傍に対応する電子輸送層膜厚とする
有機EL素子が好ましいのは、1次極大値の膜厚の電子
輸送層は薄いためにEL層を保護するに十分な厚さが確
保出来ず有機EL素子の寿命が短いものとなってしまい
、3次極大値以上のものは輝度/電流値が低くなってし
まう為である。すなわち、2次極大値の膜厚を有する上
記実施例が、有機EL素子の寿命と輝度の均衡がとれた
高信頼性かつ高輝度の有機EL素子であるからである。
電子輸送層膜厚を変化させているのは、電子輸送層材料
がEL層材料よりも比抵抗が小さく、即ち導電性が良い
ので、EL層膜厚を変化させ駆動電流を増加させなくと
もすむからである。[0027] Here, as an example, it is preferable to use an organic EL element in which the electron transport layer has a thickness corresponding to the vicinity of the second maximum value in the film thickness brightness attenuation curve. Because it is thin, it is not possible to ensure a sufficient thickness to protect the EL layer, which shortens the life of the organic EL element, and the brightness/current value becomes low when the 3rd maximum value or more is exceeded. . That is, the above-mentioned example having the film thickness of the second-order maximum value is a highly reliable and high-brightness organic EL device with a balance between the life span and brightness of the organic EL device. The reason why the electron transport layer thickness is changed is that the electron transport layer material has a lower specific resistance than the EL layer material, that is, it has better conductivity, so there is no need to change the EL layer thickness and increase the drive current. It is from.
【0028】さらに、本発明は、上記実施例の電子輸送
層材料及びEL層材料に限らず、電子輸送層材料及びE
L層材質に応じた図6に示す膜厚に対する輝度/電流特
性の膜厚輝度減衰曲線から2次極大値振幅に対応する電
子輸送層膜厚値を得ることが出来る。Furthermore, the present invention is not limited to the electron transport layer materials and EL layer materials of the above embodiments, but also applies to electron transport layer materials and EL layer materials.
The electron transport layer thickness value corresponding to the second maximum amplitude can be obtained from the film thickness luminance attenuation curve of the luminance/current characteristic with respect to film thickness shown in FIG. 6 according to the material of the L layer.
【0029】[0029]
【発明の効果】以上説明したように、本発明による互い
に積層された電子輸送層、EL層及び正孔輸送層からな
る有機EL素子は、電子輸送層は、膜厚輝度減衰曲線の
2番目に高い輝度の2次極大値の振幅がその収束する輝
度値を越える範囲内の膜厚を有しているので、耐久性を
向上させつつ低電圧にて効率良く高輝度で発光させるこ
とができる。本発明によれば、発光スペクトルの視角依
存性が小さいために視角による色彩の変化も小さい高信
頼性かつ高輝度有機EL素子が得られる。Effects of the Invention As explained above, in the organic EL device according to the present invention consisting of an electron transport layer, an EL layer, and a hole transport layer which are laminated together, the electron transport layer is located at the second position in the film thickness brightness decay curve. Since the film thickness is within a range in which the amplitude of the secondary maximum value of high brightness exceeds the convergent brightness value, it is possible to efficiently emit light with high brightness at low voltage while improving durability. According to the present invention, a highly reliable and high-brightness organic EL element can be obtained in which the viewing angle dependence of the emission spectrum is small and the change in color due to the viewing angle is also small.
【図1】2層構造の有機EL素子を示す構造図である。FIG. 1 is a structural diagram showing an organic EL element with a two-layer structure.
【図2】3層構造の有機EL素子を示す構造図である。FIG. 2 is a structural diagram showing a three-layer organic EL element.
【図3】2層構造の有機EL素子における光の干渉を説
明する部分拡大断面図である。FIG. 3 is a partially enlarged cross-sectional view illustrating light interference in a two-layer organic EL element.
【図4】2層構造の有機EL素子におけるEL層の膜厚
発光強度分布を説明するグラフである。FIG. 4 is a graph illustrating the film thickness and emission intensity distribution of an EL layer in an organic EL element with a two-layer structure.
【図5】2層構造の有機EL素子におけるEL層の波長
発光強度分布を説明するグラフである。FIG. 5 is a graph illustrating the wavelength emission intensity distribution of an EL layer in an organic EL element with a two-layer structure.
【図6】2層構造の有機EL素子におけるEL層の単体
層の膜厚輝度減衰曲線を説明するグラフである。である
。FIG. 6 is a graph illustrating a film thickness luminance attenuation curve of a single EL layer in a two-layer organic EL element. It is.
【図7】EL層及び正孔輸送層の2層構造の有機EL素
子における実測した視角度輝度特性曲線を示すグラフで
ある。FIG. 7 is a graph showing an actually measured viewing angle luminance characteristic curve of an organic EL element having a two-layer structure of an EL layer and a hole transport layer.
1……金属陰極 2……透明陽極 3……EL層 4……正孔輸送層 5……電子輸送層 6……ガラス基板 1...metal cathode 2...Transparent anode 3...EL layer 4...Hole transport layer 5...Electron transport layer 6...Glass substrate
Claims (3)
電子輸送層、エレクトロルミネッセンス層及び正孔輸送
層が陰極及び陽極間に配された有機エレクトロルミネッ
センス素子であって、前記電子輸送層は、膜厚輝度減衰
特性の2次極大値を生ずる膜厚を含みかつその振幅がそ
の収束輝度値を越える輝度を生ずる範囲内の膜厚を有し
ていることを特徴とする有機エレクトロルミネッセンス
素子。1. An organic electroluminescent element in which an electron transport layer, an electroluminescence layer, and a hole transport layer made of organic compounds and stacked on each other are arranged between a cathode and an anode, the electron transport layer having a film thickness of 1. An organic electroluminescent element having a film thickness within a range that includes a film thickness that produces a second-order maximum value of luminance attenuation characteristics and that produces a luminance whose amplitude exceeds its convergent luminance value.
特性の2次極大値を生ずる膜厚のみを有していることを
特徴とする請求項1記載の有機エレクトロルミネッセン
ス素子。2. The organic electroluminescent device according to claim 1, wherein the electron transport layer has only a thickness that produces a second-order maximum value of the thickness luminance attenuation characteristic.
ルミキノリノール錯体からなり、前記正孔輸送層はトリ
フェニルジアミン誘導体からなり、さらに前記電子輸送
層はオキサジアゾール誘導体からなり、前記収束輝度値
を越える輝度を生ずる範囲が2000ű300Åであ
ることを特徴とする請求項1記載の有機エレクトロルミ
ネッセンス素子。3. The electroluminescent layer is made of an aluminum quinolinol complex, the hole transport layer is made of a triphenyldiamine derivative, and the electron transport layer is made of an oxadiazole derivative, and the electroluminescent layer has a luminance exceeding the convergent luminance value. 2. The organic electroluminescent device according to claim 1, wherein the resulting range is 2000 ű300 Å.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3097653A JP3065705B2 (en) | 1991-04-26 | 1991-04-26 | Organic electroluminescence device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3097653A JP3065705B2 (en) | 1991-04-26 | 1991-04-26 | Organic electroluminescence device |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH04328295A true JPH04328295A (en) | 1992-11-17 |
JP3065705B2 JP3065705B2 (en) | 2000-07-17 |
Family
ID=14198045
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP3097653A Expired - Fee Related JP3065705B2 (en) | 1991-04-26 | 1991-04-26 | Organic electroluminescence device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP3065705B2 (en) |
Cited By (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0945477A (en) * | 1995-07-28 | 1997-02-14 | Canon Inc | Light emitting element and its manufacture |
JP2001102175A (en) * | 1999-09-29 | 2001-04-13 | Junji Kido | Organic electroluminescent device, organic electroluminescent device group and method of controlling its emission spectrum |
WO2001039554A1 (en) * | 1999-11-22 | 2001-05-31 | Sony Corporation | Display device |
US6327554B1 (en) | 1997-12-15 | 2001-12-04 | Tdk Corporation | Simulation method and system for organic electroluminescent device, and electroluminescent device |
EP1089361A3 (en) * | 1999-09-29 | 2001-12-19 | Junji Kido | Organic electroluminescent device and method of controlling the emission spectrum |
KR20030093016A (en) * | 2002-06-01 | 2003-12-06 | 삼성에스디아이 주식회사 | Organic electroluminescence device |
US6737800B1 (en) | 2003-02-18 | 2004-05-18 | Eastman Kodak Company | White-emitting organic electroluminescent device with color filters and reflective layer for causing colored light constructive interference |
KR100490535B1 (en) * | 2001-12-17 | 2005-05-17 | 삼성에스디아이 주식회사 | Organic electroluminescence device |
US7326473B2 (en) | 1998-02-17 | 2008-02-05 | Junji Kido | Organic electroluminescent devices |
US7397064B2 (en) | 2000-01-11 | 2008-07-08 | Semiconductor Energy Laboratory Co., Ltd. | Semiconductor display device |
US7400088B2 (en) | 2004-07-22 | 2008-07-15 | Samsung Sdi Co., Ltd. | Organic electroluminescent display device |
US7470933B2 (en) | 2004-06-18 | 2008-12-30 | Samsung Sdi Co., Ltd. | Organic light emitting display device |
US7511420B2 (en) | 2003-07-09 | 2009-03-31 | Hitachi Displays, Ltd. | Light emitting display suppressing color variations due to viewing angle |
JP2009140894A (en) * | 2007-11-14 | 2009-06-25 | Canon Inc | Light-emitting element |
JP2010045415A (en) * | 2009-11-25 | 2010-02-25 | Junji Kido | Organic electroluminescent device organic electroluminescent device group, and its emission spectrum control method |
US7808173B2 (en) | 2005-03-16 | 2010-10-05 | Samsung Mobile Display Co., Ltd. | Organic light emitting display device and method of fabricating the same |
JP2010287484A (en) * | 2009-06-12 | 2010-12-24 | Sony Corp | Organic light-emitting element, and display device and lighting system equipped therewith |
US7923920B2 (en) | 2006-10-24 | 2011-04-12 | Canon Kabushiki Kaisha | Organic light-emitting elements of LED with light reflection layers in each spaced on opposite sides of transparent conductive layer |
JP2012134128A (en) * | 2010-11-30 | 2012-07-12 | Canon Inc | Display device |
JP2014072204A (en) * | 2012-09-27 | 2014-04-21 | Kaneka Corp | Organic el light-emitting system |
WO2014167758A1 (en) * | 2013-04-12 | 2014-10-16 | パナソニック株式会社 | Light-emitting device |
US9203046B2 (en) | 2003-10-17 | 2015-12-01 | Junji Kido | Organic electroluminescent device and production process thereof |
-
1991
- 1991-04-26 JP JP3097653A patent/JP3065705B2/en not_active Expired - Fee Related
Cited By (37)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0945477A (en) * | 1995-07-28 | 1997-02-14 | Canon Inc | Light emitting element and its manufacture |
US6327554B1 (en) | 1997-12-15 | 2001-12-04 | Tdk Corporation | Simulation method and system for organic electroluminescent device, and electroluminescent device |
US7326473B2 (en) | 1998-02-17 | 2008-02-05 | Junji Kido | Organic electroluminescent devices |
US6589673B1 (en) | 1999-09-29 | 2003-07-08 | Junji Kido | Organic electroluminescent device, group of organic electroluminescent devices |
JP2001102175A (en) * | 1999-09-29 | 2001-04-13 | Junji Kido | Organic electroluminescent device, organic electroluminescent device group and method of controlling its emission spectrum |
EP1089361A3 (en) * | 1999-09-29 | 2001-12-19 | Junji Kido | Organic electroluminescent device and method of controlling the emission spectrum |
US7102282B1 (en) | 1999-11-22 | 2006-09-05 | Sony Corporation | Display device with a cavity structure for resonating light |
WO2001039554A1 (en) * | 1999-11-22 | 2001-05-31 | Sony Corporation | Display device |
US7218049B2 (en) | 1999-11-22 | 2007-05-15 | Sony Corporation | Display device |
US7397064B2 (en) | 2000-01-11 | 2008-07-08 | Semiconductor Energy Laboratory Co., Ltd. | Semiconductor display device |
US7629610B2 (en) | 2000-01-11 | 2009-12-08 | Semiconductor Energy Laboratory Co., Ltd. | Semiconductor display device |
US6906457B2 (en) | 2001-12-17 | 2005-06-14 | Samsung Sdi Co., Ltd. | Organic electroluminescent device |
KR100490535B1 (en) * | 2001-12-17 | 2005-05-17 | 삼성에스디아이 주식회사 | Organic electroluminescence device |
KR20030093016A (en) * | 2002-06-01 | 2003-12-06 | 삼성에스디아이 주식회사 | Organic electroluminescence device |
US7166370B2 (en) * | 2002-06-01 | 2007-01-23 | Samsung Sdi Co., Ltd. | Organic electroluminescence device |
US6908697B2 (en) | 2002-06-01 | 2005-06-21 | Samsung Sdi Co., Ltd. | Organic electroluminescence device |
JP2004253389A (en) * | 2003-02-18 | 2004-09-09 | Eastman Kodak Co | Multicolor organic light-emitting display |
US6737800B1 (en) | 2003-02-18 | 2004-05-18 | Eastman Kodak Company | White-emitting organic electroluminescent device with color filters and reflective layer for causing colored light constructive interference |
JP4663993B2 (en) * | 2003-02-18 | 2011-04-06 | グローバル オーエルイーディー テクノロジー リミティド ライアビリティ カンパニー | Multicolor organic light emitting display |
US7511420B2 (en) | 2003-07-09 | 2009-03-31 | Hitachi Displays, Ltd. | Light emitting display suppressing color variations due to viewing angle |
US8274218B1 (en) | 2003-07-09 | 2012-09-25 | Hitachi Displays, Ltd. | Light emitting display |
US8183770B2 (en) | 2003-07-09 | 2012-05-22 | Hitachi Displays, Ltd. | Light emitting display |
US9203046B2 (en) | 2003-10-17 | 2015-12-01 | Junji Kido | Organic electroluminescent device and production process thereof |
US7470933B2 (en) | 2004-06-18 | 2008-12-30 | Samsung Sdi Co., Ltd. | Organic light emitting display device |
US7667388B2 (en) | 2004-07-22 | 2010-02-23 | Samsung Mobile Display Co., Ltd. | Organic electroluminescent display device and method for fabricating the same |
US7400088B2 (en) | 2004-07-22 | 2008-07-15 | Samsung Sdi Co., Ltd. | Organic electroluminescent display device |
US7808173B2 (en) | 2005-03-16 | 2010-10-05 | Samsung Mobile Display Co., Ltd. | Organic light emitting display device and method of fabricating the same |
US7923920B2 (en) | 2006-10-24 | 2011-04-12 | Canon Kabushiki Kaisha | Organic light-emitting elements of LED with light reflection layers in each spaced on opposite sides of transparent conductive layer |
JP2009140894A (en) * | 2007-11-14 | 2009-06-25 | Canon Inc | Light-emitting element |
US8405098B2 (en) | 2009-06-12 | 2013-03-26 | Sony Corporation | Organic light emitting device, display unit including the same, and illuminating device including the same |
JP2010287484A (en) * | 2009-06-12 | 2010-12-24 | Sony Corp | Organic light-emitting element, and display device and lighting system equipped therewith |
JP2010045415A (en) * | 2009-11-25 | 2010-02-25 | Junji Kido | Organic electroluminescent device organic electroluminescent device group, and its emission spectrum control method |
JP2012134128A (en) * | 2010-11-30 | 2012-07-12 | Canon Inc | Display device |
JP2014072204A (en) * | 2012-09-27 | 2014-04-21 | Kaneka Corp | Organic el light-emitting system |
WO2014167758A1 (en) * | 2013-04-12 | 2014-10-16 | パナソニック株式会社 | Light-emitting device |
JPWO2014167758A1 (en) * | 2013-04-12 | 2017-02-16 | パナソニックIpマネジメント株式会社 | Light emitting device |
US9595648B2 (en) | 2013-04-12 | 2017-03-14 | Panasonic Intellectual Property Management Co., Ltd. | Light-emitting device |
Also Published As
Publication number | Publication date |
---|---|
JP3065705B2 (en) | 2000-07-17 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP3065705B2 (en) | Organic electroluminescence device | |
US6429451B1 (en) | Reduction of ambient-light-reflection in organic light-emitting devices | |
US7224114B2 (en) | Display device and display unit using the same | |
JP3297619B2 (en) | Organic EL color display | |
JP5452853B2 (en) | Organic electroluminescence device | |
US6831406B1 (en) | Electroluminescent device having a very thin emission layer | |
US6750609B2 (en) | OLEDs having light absorbing electrode | |
JP3287344B2 (en) | Organic EL device | |
JP2843925B2 (en) | Organic EL device | |
JP2772019B2 (en) | EL device | |
JP3242992B2 (en) | Organic electroluminescence device | |
JP3852518B2 (en) | Organic electroluminescence device | |
JP3065704B2 (en) | Organic electroluminescence device | |
JP3820752B2 (en) | Organic electroluminescence device | |
EP1578174A1 (en) | Organic electroluminescence element and organic electroluminescence display | |
JP2004063349A (en) | White organic electroluminescent element and design method of white organic electroluminescent element | |
JP3852517B2 (en) | Organic electroluminescence device | |
JP2843924B2 (en) | Surface emitting device | |
KR100572654B1 (en) | Organic Electroluminescent Device | |
JPH10223372A (en) | Organic electroluminescent element and flat panel display using it | |
JP2004103247A (en) | Organic el display device | |
KR100699966B1 (en) | Organic electroluminescence device and organic electroluminescence display | |
JP3852520B2 (en) | Organic electroluminescence device | |
US20090066228A1 (en) | Organic electroluminescence element | |
KR100544120B1 (en) | Electroluminescence device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080512 Year of fee payment: 8 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080512 Year of fee payment: 8 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090512 Year of fee payment: 9 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090512 Year of fee payment: 9 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100512 Year of fee payment: 10 |
|
LAPS | Cancellation because of no payment of annual fees |