JP3801330B2 - Organic electroluminescence device - Google Patents

Organic electroluminescence device Download PDF

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JP3801330B2
JP3801330B2 JP32885297A JP32885297A JP3801330B2 JP 3801330 B2 JP3801330 B2 JP 3801330B2 JP 32885297 A JP32885297 A JP 32885297A JP 32885297 A JP32885297 A JP 32885297A JP 3801330 B2 JP3801330 B2 JP 3801330B2
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group
hole transport
organic electroluminescence
electroluminescence device
organic
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JPH11162649A (en
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武彦 島村
尚登 伊藤
洋 成瀬
勝 和田
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Mitsui Chemicals Inc
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    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09BORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
    • C09B57/00Other synthetic dyes of known constitution
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C211/00Compounds containing amino groups bound to a carbon skeleton
    • C07C211/43Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton
    • C07C211/57Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings being part of condensed ring systems of the carbon skeleton
    • C07C211/61Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings being part of condensed ring systems of the carbon skeleton with at least one of the condensed ring systems formed by three or more rings
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    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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    • C09B23/00Methine or polymethine dyes, e.g. cyanine dyes
    • C09B23/0008Methine or polymethine dyes, e.g. cyanine dyes substituted on the polymethine chain
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    • C09B23/00Methine or polymethine dyes, e.g. cyanine dyes
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    • C09B57/008Triarylamine dyes containing no other chromophores
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    • C09B57/00Other synthetic dyes of known constitution
    • C09B57/08Naphthalimide dyes; Phthalimide dyes
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10KORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/60Organic compounds having low molecular weight
    • H10K85/631Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
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    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2601/00Systems containing only non-condensed rings
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    • C07C2603/04Ortho- or ortho- and peri-condensed systems containing three rings
    • C07C2603/06Ortho- or ortho- and peri-condensed systems containing three rings containing at least one ring with less than six ring members
    • C07C2603/10Ortho- or ortho- and peri-condensed systems containing three rings containing at least one ring with less than six ring members containing five-membered rings
    • C07C2603/12Ortho- or ortho- and peri-condensed systems containing three rings containing at least one ring with less than six ring members containing five-membered rings only one five-membered ring
    • C07C2603/18Fluorenes; Hydrogenated fluorenes

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  • Materials Engineering (AREA)
  • Electroluminescent Light Sources (AREA)

Description

【0001】
【発明の属する技術分野】
本発明は、電気エネルギーを光エネルギーに直接交換できる有機エレクトロルミネッセンス素子に関するものである。
【0002】
【従来の技術】
有機正孔輸送物質を利用する技術として、有機エレクトロルミネッセンス素子が、実用化に向けて現在さかんに研究されている。有機エレクトロルミネッセンス素子は、陽極および陰極のそれぞれから注入された正孔と電子が有機層内を移動し、再結合した際のエネルギーで有機蛍光色素を励起し、光エネルギーを取り出す固体発光型の薄型光源であり、液晶ディスプレイのバックライトあるいは次世代の大面積表示素子と期待されている。2つの電極間に電子輸送層、発光層、正孔輸送層の有機層を積層した構造の素子が、低電圧駆動で発光輝度や発光効率が高く有効である。
【0003】
【発明が解決しようとする課題】
しかしながら、現在までの有機エレクトロルミネッセンス素子は、繰り返し使用時の発光安定性はいまだ十分でない。素子劣化の原因は種々提起されているが、その一つとして、発光の際の発熱等により正孔輸送物質の結晶化が起こり、ピンホール欠陥からのリーク電流が素子劣化につながる事が指摘されている。そのため、正孔輸送能力が高く、かつ結晶化の起きにくい正孔輸送物質の開発が望まれていた。
【0004】
本発明の目的は、耐久性に優れた有機エレクトロルミネッセンス素子を提供することにある。
【0005】
【課題を解決するための手段】
本発明者らは、前記目的の達成の為に鋭意検討した結果、下記一般式(1)
【化2】

Figure 0003801330
[式中、R1はアルキル基またはアラルキル基を示し、R2、R3、R4、R5、R6およびR7はそれぞれ独立に水素原子、アルキル基、アルコキシ基またはハロゲン原子を示し、nは0または1を示す。]で表される正孔輸送物質が結晶化が起きにくく、正孔輸送能力に優れており、該化合物を用いた有機エレクトロルミネッセンス素子が、耐久性に優れることを見いだし、本発明に至った。
【0006】
すなわち本発明は、一対の電極間に一層以上の多層の有機化合物から構成される有機エレクトロルミネッセンス素子において、少なくとも一層が下記一般式(1)で表される正孔輸送物質を含有す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に関するものである。
【0007】
【化3】
Figure 0003801330
[式中、R1、R2、R3、R4、R5、R6、R7、nは前記と同じ意味を示す。]
【0008】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明の一般式(1)で表される化合物は、特開平4−221328号公報記載の方法により合成することのできる下記一般式(2)に表されるフルオレン誘導体と、特開平8−151352号公報記載の方法により合成できる下記一般式(3)で表される2級アミン誘導体とを、金属銅、酸化銅、塩化銅等の金属触媒下で反応させるウルマン反応により合成される。このウルマン反応終了後、触媒等を濾別して溶媒を減圧下で留去する。得られた粗結晶から、再結晶等の精製操作により、目的生成物を単離する事ができる。もちろん、これ以外の方法によっても合成することができる。
【0009】
【化4】
Figure 0003801330
[式中、R1、nは前記と同じ意味を示す。]
【0010】
【化5】
Figure 0003801330
[式中、R2、R3、R4、R5、R6およびR7は前記と同じ意味を示す。]
【0011】
本発明の一般式(1)で表される化合物において、R1はアルキル基またはアラルキル基を示し、R2、R3、R4、R5、R6およびR7はそれぞれ独立に水素原子、アルキル基またはハロゲン原子を示す。
【0012】
1の具体的例としては、メチル基、エチル基、プロピル基、1−メチルエチル基、ブチル基、1−メチルプロピル基、2−メチルプロピル基、1,1−ジメチルエチル基、ペンチル基、1−メチルブチル基、2−メチルブチル基、3−メチルブチル基、1,1−ジメチルプロピル基、1,2−ジメチルプロピル基、2,2−ジメチルプロピル基、1−エチルプロピル基、2−エチルプロピル基、ヘキシル基、シクロヘキシル基、ヘプチル基、メチルシクロヘキシル基、オクチル基、2−エチルヘキシル基、エチルシクロヘキシル基、ジメチルシクロヘキシル基、ノニル基、3,5,5−トリメチルヘキシル基、デシル基等の炭素数1〜10の直鎖、分岐または環状のアルキル基、ベンジル基、フェニルエチル基、トリルメチル基、メトキシフェニルメチル基、ナフチルメチル基、ナフチルエチル基等のアラルキル基が挙げられる。
【0013】
2〜R7の具体的例としては、水素原子、メチル基、エチル基、プロピル基、1−メチルエチル基、ブチル基、1−メチルプロピル基、2−メチルプロピル基、1,1−ジメチルエチル基、ペンチル基、1−メチルブチル基、2−メチルブチル基、3−メチルブチル基、1,1−ジメチルプロピル基、1,2−ジメチルプロピル基、2,2−ジメチルプロピル基、1−エチルプロピル基、2−エチルプロピル基、ヘキシル基、シクロヘキシル基、ヘプチル基、メチルシクロヘキシル基、オクチル基、2−エチルヘキシル基、エチルシクロヘキシル基、ジメチルシクロヘキシル基、ノニル基、3,5,5−トリメチルヘキシル基、デシル基等の炭素数1〜10の直鎖、分岐または環状のアルキル基、メトキシ基、エトキシ基、プロポキシ基、1−メチルエトキシ基、ブトキシ基、1−メチルプロポキシ基、2−メチルプロポキシ基、1,1−ジメチルエトキシ基、ペンチルオキシ基、1−メチルブトキシ基、2−メチルブトキシ基、3−メチルブトキシ基、1,1−ジメチルプロポキシ基、1,2−ジメチルプロポキシ基、2,2−ジメチルプロポキシ基、1−エチルプロポキシ基、3−エチルプロポキシ基、ヘキシルオキシ基、シクロヘキシルオキシ基、ヘプチルオキシ基、メチルシクロヘキシルオキシ基、オクチルオキシ基、2−エチルヘキシルオキシ基、エチルシクロヘキシルオキシ基、ジメチルシクロヘキシルオキシ基、ノニルオキシ基、3,5,5−トリメチルヘキシルオキシ基、デシルオキシ基等の炭素数1〜10の直鎖、分岐または環状のアルコキシ基、フッ素原子、塩素原子、臭素原子等のハロゲン原子を挙げる事ができる。
【0014】
一般式(1)で表される正孔輸送物質の代表例を具体的に表1に例示するが、これらに限定されるものではない。
【0015】
【表1】
Figure 0003801330
【0016】
【表2】
Figure 0003801330
【0017】
【表3】
Figure 0003801330
【0018】
エレクトロルミネッセンス素子の作製方法としては、特開昭58−194393号公報;Applyed Physics Letters,51(12),913(1987);Journal of Applyed Physics,65(9)3610(1989);Japan Journal of Applyed Physics 27(2)268(1988)、27(4)713(1988);宮田等『有機EL素子開発戦略』(サイエンスフォーラム社、1992)等の公知の文献記載の方法が利用できる。
【0019】
詳しくは、エレクトロルミネッセンス素子は、図1に示すように、ガラス基板(ITOガラス基板)5上に陽極4、本発明化合物を含有する正孔輸送層3、有機化合物からなる発光層2および金属陰極1が順に積層された構造を有している。さらに、図2に示すようにガラス基板(ITOガラス基板)5上に陽極4、本発明化合物を含有する正孔輸送層3、有機化合物からなる発光層2、電子輸送層6および金属陰極1が順に積層された構造を有していてもよい。上記素子構造における正孔輸送層に使用する本発明化合物は、単独または2種類以上を用いてもよい。一方、電子輸送層に用いる電子輸送物質として、下記式(4)のオキサジアゾール化合物、下記式(5)のペリノン誘導体等が用いられる。
【0020】
【化6】
Figure 0003801330
【0021】
発光層に用いられる蛍光色素としては、固体状態において強い蛍光性を示す色素で種々の構造の化合物が挙げられるが、蛍光色素の代表例として、下記構造式(6)〜(15)の化合物が例示できる。しかし、これに限定されるものではない。
【0022】
【化7】
Figure 0003801330
【0023】
正孔輸送層、発光層、電子輸送層、陰極および陽極は、蒸着、スパッタリング、塗布等の一般的に知られている薄膜形成法により作製する事ができる。
【0024】
本発明の有機エレクトロルミネッセンス素子を作製するにあたり、正孔輸送層および電子輸送層の膜厚は、少なくともピンホールが発生しないような厚みが必要であるが、あまり厚いと素子の抵抗が増加し、高い駆動電圧が必要となり好ましくない。従って、正孔輸送層および電子輸送層の膜厚は、通常、1nm〜1000nm、好ましくは5nm〜200nmである。また発光層の膜厚は、輝度を高くし、かつピンホールが発生しないような厚みが必要であるが、あまり厚いと素子の抵抗が増加し、高い駆動電圧が必要となるため、通常、1nm〜1000nm、好ましくは3nm〜300nmである。電流密度を上げて発光効率を上げるために5nm〜200nmの範囲が好適に用いられる。
【0025】
本発明の有機エレクトロルミネッセンス素子に使用する陽極材料としては、仕事関数がなるべく大きなものがよく、例えば、ニッケル、金、白金、パラジウム、セレン、イリジウムやこれらの合金、あるいは酸化スズ、ITO、ヨウ化銅が好ましい。ポリフェニレンスルフィドあるいはポリアニリン等の導電性ポリマーも使用できる。一方、陰極材料としては、仕事関数が小さなもの、銀、鉛、スズ、マグネシウム、アルミニウム、カルシウム、インジウム、クロム、リチウムあるいはこれらの合金が用いられる。
【0026】
また陽極または陰極として用いられる材料の一方は、素子の発振波長領域における透過率が50%以上ある事が望ましい。
本発明に使用する透明電極基板としては、ガラスまたはプラスチックフィルムが用いられる。
【0027】
以上のように本発明の有機エレクトロルミネッセンス素子は、一般式(1)の正孔輸送物質の外、前記電子輸送物質、蛍光色素、陽極材料、陰極材料、透明電極基板から構成されるが、有機エレクトロルミネッセンス素子の他の構成要素は、有機エレクトロルミネッセンス素子の構成要素としての機能を有するものであれば、特に限定されるものではない。
【0028】
【実施例】
以下に実施例をもって詳細に説明するが、本発明は以下の例に限定されるものではない。なお、例中の部は重量部を示す。
【0029】
合成例1(例示化合物No.1の合成)
2−ヨード−9,9−ジメチルフルオレン16部をo−ジクロロベンゼン48部に加え、窒素雰囲気下に100℃に昇温する。同温度でN−(p−トリル)−N−(p−ビフェニル)アミン15.6部、銅粉8部、炭酸カリウム10.4部を装入した後、180℃に昇温して同温度で48時間、撹拌反応する。反応終了後、100℃に冷却して銅粉を濾別する。濾液から減圧蒸留でo−ジクロロベンゼンを留去する。その後、100℃で蒸留残渣を融解し、ここにN,N−ジメチルホルムアミド32部を加え、室温まで冷却する。析出した結晶を濾過、乾燥した後、カラムクロマトグラフィーにより、分離精製して淡黄色固体2.5部を得た。このものは元素分析値より、表1中の例示化合物No.1であるフルオレン化合物である事を確認した。
【0030】
Figure 0003801330
【0031】
実施例1
ITOガラス基板上に、表1中の例示化合物No.1を5×10-5torrの真空下で、抵抗加熱法により50nm積層する。次いで、式(7)の蛍光色素を50nm積層し、さらにアルミニウム電極を6×10-5torrの真空下で150nm蒸着した。この素子のITO側にプラス、アルミニウム側にマイナスの電場をかけて、素子のガラス基板面からの発光を観測した。5V以上の電圧を印加すると明るい青色発光が観測された。なお、その時の駆動電流は0.2〜80mA/cm2であった。
また、発光強度が初期値の80%になるまでの連続運転時間は2250時間と耐久性が良好な素子であることが判明した。
【0032】
実施例2〜15
実施例1と同様にして、正孔輸送物質および蛍光色素を変えて有機エレクトロルミネッセンス素子を作製し、同様の測定を行った。
使用した正孔輸送物質と蛍光色素の組み合わせと測定結果を、実施例1の測定結果と共に表2に示した。
【0033】
【表4】
Figure 0003801330
【0034】
比較例1
実施例1における正孔輸送物質を表1中の例示化合物No.1の代わりに下記式(16)を用いた以外は、実施例1と全く同様にして有機エレクトロルミネッセンス素子を作製したところ、発光強度等の特性は実施例1とほぼ一致していたが、耐久性が450時間と短く不良であった。
【0035】
【化8】
Figure 0003801330
【0036】
比較例2
実施例1における正孔輸送物質を、表1中の例示化合物No.1の代わりに下記式(17)を用いた以外は、実施例1と全く同様にして有機エレクトロルミネッセンス素子を作製したところ、発光強度等の特性は実施例1とほぼ一致していたが、耐久性が400時間と短く不良であった。
【0037】
【化9】
Figure 0003801330
【0038】
【発明の効果】
本発明の有機エクトロルミネッセンス素子は、有機薄膜層の少なくとも 1層が前記一般式(1)で表される化合物を正孔輸送層として含有するものであり、耐久性に優れ、実用上極めて価値の高いものである。
【図面の簡単な説明】
【図1】 ガラス基板上に陽極、正孔輸送層、発光層及び陰極の順に積層された有機EL素子の一例を示す断面図である。
【図2】 ガラス基板上に陽極、正孔輸送層、発光層、電子輸送層及び陰極が順に積層された有機EL素子の一例を示す断面図である。
【符号の説明】
1 金属電極
2 発光層
3 正孔輸送層
4 陽極
5 ガラス基板(ITOガラス基板)
6 電子輸送層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic electroluminescence device capable of directly exchanging electric energy with light energy.
[0002]
[Prior art]
Organic electroluminescence devices are currently being studied as a technology that uses organic hole transport materials for practical application. The organic electroluminescence device is a thin solid-state light-emitting type that takes out light energy by exciting organic fluorescent dyes with the energy generated when holes and electrons injected from the anode and cathode move through the organic layer and recombine. It is a light source and is expected to be a backlight for liquid crystal displays or a next-generation large-area display element. An element having a structure in which an organic layer such as an electron transport layer, a light-emitting layer, and a hole transport layer is stacked between two electrodes is effective with high emission luminance and light emission efficiency when driven at a low voltage.
[0003]
[Problems to be solved by the invention]
However, the organic electroluminescence elements up to now still have insufficient light emission stability upon repeated use. Various causes of device degradation have been proposed, but one of them is pointed out that crystallization of the hole transport material occurs due to heat generation during light emission, and that leakage current from pinhole defects leads to device degradation. ing. Therefore, it has been desired to develop a hole transport material having a high hole transport capability and hardly causing crystallization.
[0004]
The objective of this invention is providing the organic electroluminescent element excellent in durability.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have found that the following general formula (1)
[Chemical 2]
Figure 0003801330
[Wherein, R 1 represents an alkyl group or an aralkyl group, R 2 , R 3 , R 4 , R 5 , R 6 and R 7 each independently represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, n represents 0 or 1. It has been found that the hole transport material represented by the formula is hardly crystallized and has excellent hole transport ability, and the organic electroluminescence device using the compound is excellent in durability, and the present invention has been achieved.
[0006]
That is, the present invention is an organic electroluminescent device composed of one or more multilayer organic compounds between a pair of electrodes, wherein at least one layer contains a hole transport material represented by the following general formula (1). It relates to an organic electroluminescence element.
[0007]
[Chemical 3]
Figure 0003801330
[Wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and n have the same meaning as described above. ]
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The compound represented by the general formula (1) of the present invention includes a fluorene derivative represented by the following general formula (2) that can be synthesized by the method described in JP-A-4-221328, and JP-A-8-151352. It is synthesized by the Ullmann reaction in which a secondary amine derivative represented by the following general formula (3), which can be synthesized by the method described in Japanese Patent Publication No. Gazette, is reacted in the presence of a metal catalyst such as metallic copper, copper oxide or copper chloride. After completion of the Ullmann reaction, the catalyst and the like are filtered off and the solvent is distilled off under reduced pressure. The target product can be isolated from the obtained crude crystals by a purification operation such as recrystallization. Of course, it can be synthesized by other methods.
[0009]
[Formula 4]
Figure 0003801330
[Wherein, R 1 and n have the same meaning as described above. ]
[0010]
[Chemical formula 5]
Figure 0003801330
[Wherein R 2 , R 3 , R 4 , R 5 , R 6 and R 7 have the same meaning as described above. ]
[0011]
In the compound represented by the general formula (1) of the present invention, R 1 represents an alkyl group or an aralkyl group, and R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently a hydrogen atom, An alkyl group or a halogen atom is shown.
[0012]
Specific examples of R 1 include methyl group, ethyl group, propyl group, 1-methylethyl group, butyl group, 1-methylpropyl group, 2-methylpropyl group, 1,1-dimethylethyl group, pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group, 1-ethylpropyl group, 2-ethylpropyl group , Hexyl group, cyclohexyl group, heptyl group, methylcyclohexyl group, octyl group, 2-ethylhexyl group, ethylcyclohexyl group, dimethylcyclohexyl group, nonyl group, 3,5,5-trimethylhexyl group, decyl group, etc. -10 linear, branched or cyclic alkyl group, benzyl group, phenylethyl group, tolylmethyl group, methoxy Enirumechiru group, naphthylmethyl group, an aralkyl group such as a naphthylethyl group.
[0013]
Specific examples of R 2 to R 7 are hydrogen atom, methyl group, ethyl group, propyl group, 1-methylethyl group, butyl group, 1-methylpropyl group, 2-methylpropyl group, 1,1-dimethyl. Ethyl group, pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group, 1-ethylpropyl group 2-ethylpropyl group, hexyl group, cyclohexyl group, heptyl group, methylcyclohexyl group, octyl group, 2-ethylhexyl group, ethylcyclohexyl group, dimethylcyclohexyl group, nonyl group, 3,5,5-trimethylhexyl group, decyl A linear, branched or cyclic alkyl group having 1 to 10 carbon atoms such as a group, a methoxy group, an ethoxy group, a propoxy group, -Methylethoxy group, butoxy group, 1-methylpropoxy group, 2-methylpropoxy group, 1,1-dimethylethoxy group, pentyloxy group, 1-methylbutoxy group, 2-methylbutoxy group, 3-methylbutoxy group, 1,1-dimethylpropoxy group, 1,2-dimethylpropoxy group, 2,2-dimethylpropoxy group, 1-ethylpropoxy group, 3-ethylpropoxy group, hexyloxy group, cyclohexyloxy group, heptyloxy group, methylcyclohexyl Straight chain having 1 to 10 carbon atoms such as oxy group, octyloxy group, 2-ethylhexyloxy group, ethylcyclohexyloxy group, dimethylcyclohexyloxy group, nonyloxy group, 3,5,5-trimethylhexyloxy group, decyloxy group, Branched or cyclic alkoxy group, fluorine atom, Mention may be made of halogen atoms such as chlorine and bromine atoms.
[0014]
Although the typical example of the hole transport material represented by General formula (1) is specifically illustrated in Table 1, it is not limited to these.
[0015]
[Table 1]
Figure 0003801330
[0016]
[Table 2]
Figure 0003801330
[0017]
[Table 3]
Figure 0003801330
[0018]
As a method for manufacturing an electroluminescent element, JP-A-58-194393; Applied Physics Letters, 51 (12), 913 (1987); Journal of Applied Physics, 65 (9) 3610 (1989); Japan Journal of Japan. Physics 27 (2) 268 (1988), 27 (4) 713 (1988); Miyata et al., “Organic EL Device Development Strategy” (Science Forum, 1992) can be used.
[0019]
Specifically, as shown in FIG. 1, the electroluminescence element includes an anode 4 on a glass substrate (ITO glass substrate) 5, a hole transport layer 3 containing the compound of the present invention, a light emitting layer 2 made of an organic compound, and a metal cathode. 1 has a structure in which layers are sequentially stacked. Further, as shown in FIG. 2, an anode 4, a hole transport layer 3 containing the compound of the present invention, a light emitting layer 2 made of an organic compound, an electron transport layer 6 and a metal cathode 1 are formed on a glass substrate (ITO glass substrate) 5. You may have the structure laminated | stacked in order. This invention compound used for the positive hole transport layer in the said element structure may use individually or two or more types. On the other hand, as an electron transport material used for the electron transport layer, an oxadiazole compound of the following formula (4), a perinone derivative of the following formula (5), and the like are used.
[0020]
[Chemical 6]
Figure 0003801330
[0021]
Examples of the fluorescent dye used in the light-emitting layer include dyes that exhibit strong fluorescence in a solid state and compounds having various structures. As typical examples of fluorescent dyes, compounds represented by the following structural formulas (6) to (15) are given. It can be illustrated. However, it is not limited to this.
[0022]
[Chemical 7]
Figure 0003801330
[0023]
The hole transport layer, the light emitting layer, the electron transport layer, the cathode, and the anode can be produced by a generally known thin film forming method such as vapor deposition, sputtering, and coating.
[0024]
In preparing the organic electroluminescence device of the present invention, the hole transport layer and the electron transport layer need to have a thickness that does not generate pinholes at least, but if the thickness is too thick, the resistance of the device increases. A high driving voltage is required, which is not preferable. Therefore, the film thicknesses of the hole transport layer and the electron transport layer are usually 1 nm to 1000 nm, preferably 5 nm to 200 nm. The thickness of the light emitting layer needs to be high enough to increase luminance and prevent pinholes. However, if the thickness is too large, the resistance of the element increases and a high driving voltage is required. ˜1000 nm, preferably 3 nm to 300 nm. A range of 5 nm to 200 nm is preferably used in order to increase the current density and increase the luminous efficiency.
[0025]
As an anode material used for the organic electroluminescence device of the present invention, a material having a work function as large as possible is good, for example, nickel, gold, platinum, palladium, selenium, iridium or an alloy thereof, tin oxide, ITO, or iodide. Copper is preferred. Conductive polymers such as polyphenylene sulfide or polyaniline can also be used. On the other hand, as the cathode material, those having a small work function, silver, lead, tin, magnesium, aluminum, calcium, indium, chromium, lithium, or alloys thereof are used.
[0026]
Moreover, it is desirable that one of the materials used as the anode or the cathode has a transmittance of 50% or more in the oscillation wavelength region of the element.
As the transparent electrode substrate used in the present invention, glass or a plastic film is used.
[0027]
As described above, the organic electroluminescence device of the present invention is composed of the electron transport material, the fluorescent dye, the anode material, the cathode material, and the transparent electrode substrate in addition to the hole transport material of the general formula (1). Other components of the electroluminescence element are not particularly limited as long as they have a function as a component of the organic electroluminescence element.
[0028]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples. In addition, the part in an example shows a weight part.
[0029]
Synthesis Example 1 (Synthesis of Exemplified Compound No. 1)
16 parts of 2-iodo-9,9-dimethylfluorene are added to 48 parts of o-dichlorobenzene, and the temperature is raised to 100 ° C. in a nitrogen atmosphere. After charging 15.6 parts of N- (p-tolyl) -N- (p-biphenyl) amine, 8 parts of copper powder and 10.4 parts of potassium carbonate at the same temperature, the temperature was raised to 180 ° C. and the same temperature. For 48 hours. After completion of the reaction, the mixture is cooled to 100 ° C. and the copper powder is filtered off. O-Dichlorobenzene is distilled off from the filtrate by vacuum distillation. Thereafter, the distillation residue is melted at 100 ° C., 32 parts of N, N-dimethylformamide is added thereto, and the mixture is cooled to room temperature. The precipitated crystals were filtered and dried, and then separated and purified by column chromatography to obtain 2.5 parts of a pale yellow solid. From the elemental analysis values, this compound has the Exemplified Compound Nos. It was confirmed that the fluorene compound was 1.
[0030]
Figure 0003801330
[0031]
Example 1
On the ITO glass substrate, Exemplified Compound Nos. 1 is laminated in a thickness of 50 nm by a resistance heating method under a vacuum of 5 × 10 −5 torr. Next, 50 nm of the fluorescent dye of formula (7) was laminated, and an aluminum electrode was further deposited by 150 nm under a vacuum of 6 × 10 −5 torr. A positive electric field was applied to the ITO side of the device and a negative electric field was applied to the aluminum side, and light emission from the glass substrate surface of the device was observed. When a voltage of 5 V or higher was applied, bright blue light emission was observed. The driving current at that time was 0.2 to 80 mA / cm 2 .
Further, it was found that the continuous operation time until the emission intensity reached 80% of the initial value was 2250 hours, and the device had good durability.
[0032]
Examples 2-15
In the same manner as in Example 1, an organic electroluminescence device was produced by changing the hole transport material and the fluorescent dye, and the same measurement was performed.
Table 2 shows the combination of the hole transport material and the fluorescent dye used and the measurement results together with the measurement results of Example 1.
[0033]
[Table 4]
Figure 0003801330
[0034]
Comparative Example 1
The hole transport material in Example 1 is represented by the exemplified compound No. 1 in Table 1. When an organic electroluminescence device was produced in the same manner as in Example 1 except that the following formula (16) was used instead of 1, the characteristics such as emission intensity were almost the same as those in Example 1, but the durability was The property was as short as 450 hours.
[0035]
[Chemical 8]
Figure 0003801330
[0036]
Comparative Example 2
The hole transport material in Example 1 is represented by the exemplified compound No. 1 in Table 1. When an organic electroluminescence device was produced in the same manner as in Example 1 except that the following formula (17) was used instead of 1, the characteristics such as light emission intensity were almost the same as those in Example 1, but the durability was The property was as short as 400 hours and was poor.
[0037]
[Chemical 9]
Figure 0003801330
[0038]
【The invention's effect】
The organic electroluminescence device of the present invention is one in which at least one of the organic thin film layers contains the compound represented by the general formula (1) as a hole transport layer, and is excellent in durability and extremely practically valuable. Is high.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an organic EL device in which an anode, a hole transport layer, a light emitting layer, and a cathode are laminated in this order on a glass substrate.
FIG. 2 is a cross-sectional view showing an example of an organic EL device in which an anode, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode are sequentially laminated on a glass substrate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Metal electrode 2 Light emitting layer 3 Hole transport layer 4 Anode 5 Glass substrate (ITO glass substrate)
6 Electron transport layer

Claims (1)

一対の電極間に一層以上の多層の有機化合物から構成される有機エレクトロルミネッセンス素子において、少なくとも一層が下記一般式(1)で表される正孔輸送物質を正孔輸送層に含有することを特徴とする耐久性に優れた有機エレクトロルミネッセンス素子。
Figure 0003801330
[式中、R1はアルキル基またはアラルキル基を示し、R2、R3、R4、R5、R6およびR7はそれぞれ独立に水素原子、アルキル基、アルコキシ基またはハロゲン原子を示し、nは0または1を示す。]
In the organic electroluminescence device composed of one or more multilayer organic compounds between a pair of electrodes, at least one layer contains a hole transport material represented by the following general formula (1) in the hole transport layer. An organic electroluminescence device excellent in durability .
Figure 0003801330
[Wherein, R 1 represents an alkyl group or an aralkyl group, R 2 , R 3 , R 4 , R 5 , R 6 and R 7 each independently represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, n represents 0 or 1. ]
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WO2013118846A1 (en) 2012-02-10 2013-08-15 出光興産株式会社 Aromatic amine derivative, organic electroluminescent element and electronic device
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KR102563248B1 (en) * 2007-12-03 2023-08-04 가부시키가이샤 한도오따이 에네루기 켄큐쇼 Carbazole derivative, and light-emitting element, light-emitting device, and electronic device using carbazole derivative
WO2013118812A1 (en) * 2012-02-10 2013-08-15 出光興産株式会社 Organic electroluminescent element
WO2014034795A1 (en) 2012-08-31 2014-03-06 出光興産株式会社 Aromatic amine derivative, and organic electroluminescent element using same
CN113233988B (en) * 2019-01-23 2023-05-02 苏州久显新材料有限公司 Fluorene derivative and electronic device
DE102020117123A1 (en) * 2019-07-05 2021-01-07 Semiconductor Energy Laboratory Co., Ltd. MATERIAL FOR HOLE TRANSPORT LAYER, MATERIAL FOR HOLE INJECTION LAYER, ORGANIC COMPOUND, LIGHT EMITTING DEVICE, LIGHT EMITTING DEVICE, ELECTRONIC DEVICE AND LIGHTING DEVICE

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US9871203B2 (en) 2012-02-10 2018-01-16 Idemitsu Kosan Co., Ltd. Aromatic amine derivative, organic electroluminescent element and electronic device
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