Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Reexamination Certificate
1998-03-02
2002-04-09
Wilson, James O. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
C556S489000, C428S446000, C428S447000
Reexamination Certificate
active
06369258
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a silicon-containing compound; a method for surface treatment of an electrode, using the silicon-containing compound; a surface-treating agent of an electrode, comprising the silicon-containing compound; and an organic electroluminescence device obtained by treating an anode with the silicon-containing compound.
2. Related Art of the Invention
Recently, many studies on electronic or photoelectronic devices using organic materials have intensively been made. However, few devices are composed only of the organic material and, in almost all of cases, a device structure is formed by laminating the organic material and inorganic material. Since such an electronic or photoelectronic device consists of many inorganic/organic interfaces, because it has a structure fabricated by laminating the organic material over the inorganic material in the device, it is important to control of the mechanical and electric characteristics of the interface to improve the device performance.
In an organic electroluminescence device, for example, an inorganic transparent conductive electrode of indium-tin oxide (hereinafter abbreviated to ITO, sometimes), tin oxide (SnO
2
), zinc oxide (ZnO), etc. is often used as a transparent conductive electrode for transmitting light and injecting holes. The device is constructed by forming a layer of an organic hole transporting material on this transparent conductive electrode, but the interface between the transparent conductive electrode and the organic hole transporting material has the following problem. That is, an ITO electrode, SnO
2
electrode or ZnO electrode is used after washing the surface according to solvent washing, plasma washing, etc. and the hydroxyl group or alkoxy group is formed on the surface of the surface-washed ITO electrode, SnO
2
electrode or ZnO electrode, thereby hydrophilizing the electrode. Since a hydrophobic functional organic material is generally used as a hole transporting film to be formed on the transparent conductive electrode, peeling of the film arises sometimes because of poor adhesion at the interface. No problem arises when a hydrophilic functional organic molecule is further formed on this hydrophilic conductive electrode. For example, Japanese Patent Kokai Publication No. 2-267888 discloses an organic electroluminescence device obtained by forming a polysilane thin film having the hole transporting property on an ITO electrode. Since a conventional polysilane compound has only a hydrophobic group on the side chain, satisfactory adhesion is still to be obtained, necessarily.
A surface-treating agent represented by a silane coupling agent is widely used as a modifier of the interface between composite materials prepared by using organic materials in combination with inorganic materials, such as elastomer, paint, adhesives, sealant, resin coat, etc., including fiber-reinforced plastic. It becomes possible to improve the adhesion between the inorganic layer and organic layer by treating with this surface-treating agent. Since almost all of surface-treating agent, which have hitherto been used, have no electron transporting property or hole transporting property, it serves only as an electric insulator, thereby to drastically deteriorate performance as the electronic or photoelectronic device.
On the other hand, the work function of the ITO electrode, SnO
2
electrode or ZnO electrode hardly agrees with the ionization potential of the organic hole transporting material, and a difference in potential between the transparent conductive electrode and organic hole transporting material arises. This difference in potential becomes an potential barrier to holes in case of injecting holes from the transparent conductive electrode into the organic hole transporting material, sometimes. This potential barrier causes reduction in probability of injection of holes from the transparent conductive electrode to the organic hole transporting material, thereby lowering the injection efficiency of holes. In order to solve this problem, an attempt of vacuum deposition of metal phthalocyanine having an intermediate ionization potential between the work function of the transparent conductive electrode and the ionization potential of the organic hole transporting material in the semitransparent state has been made. However, it is pointed out that the light transmission is lowered because the metal phthalocyanine has absorption in the visible light region.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a novel silicon-containing compound; a method for surface treatment of an electrode, using the silicon-containing compound wherein the mechanical/electric contact between an electrode (e.g. transparent conductive electrode, etc.) and an organic layer is improved; an surface-treating agent of an electrode, comprising the silicon-containing compound; and an organic electroluminescence device (hereinafter referred to as an “organic EL device”, sometimes) having excellent mechanical and electric contact between an electrode and an organic layer, which is obtained by treating an anode with the silicon-containing compound.
The present inventors have intensively studied about a surface-treating agent having the hole transporting property so as to solve the above mechanical and electric problems of the conventional technique. As a result, the present inventors have found that the injection efficiency of holes into the organic layer and adhesion can be improved a by treating the surface of the electrode with a specific silicon-containing compound. Thus, the present invention has been accomplished.
The present invention relates to [1] a silicon-containing compound having an oxidation potential of 0.3 to 1.5 V on the basis of a standard hydrogen electrode, wherein at least one alkoxy group is bonded to a silicon atom and at least one aromatic amine group is also bonded to the silicon atom.
Furthermore, the present invention relates to [2] the silicon-containing compound according to the term [1], wherein a structural formula is represented by the general formula (1):
wherein R
1
represents a hydrogen atom, or a straight-chain or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 10 carbon atoms or less, an aryl group having 6 to 24 carbon atoms or an aralkyl group having 7 to 26 carbon atoms; R
2
represents a straight-chain or branched alkyl group having 1 to 10 carbon atoms; R
3
represents a straight-chain or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 10 carbon atoms or less, an aryl group having 6 to 24 carbon atoms or an aralkyl group having 7 to 26 carbon atoms; Ar
1
represents an arylene group having 6 to 24 carbon atoms; Ar
2
represents a straight-chain or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 10 carbon atoms or less, an aryl group having 6 to 24 carbon atoms or an aralkyl group having 7 to 26 carbon atoms, or the general formula (2):
wherein Ar
3
represents an arylene group having 6 to 24 carbon atoms; and R
4
and R
5
independently represent a straight-chain or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 10 carbon atoms or less, an aryl group having 6 to 24 carbon atoms or an aralkyl group having 7 to 26 carbon atoms; s and t independently represent an integer from 1 to 3, which satisfy the expression 2≦s+t≦4; and a ring may be independently formed between R
3
and Ar
1
, R
3
and Ar
2
, or Ar
1
and Ar
2
, or alternatively a ring may be independently formed between R
4
and Ar
3
, or R
4
and R
5
when Ar
2
is represented by the general formula (2).
Also, the present invention relates to [3] a method for surface treatment of an electrode in a device having an organic layer in contact with the electrode, which comprises treating the surface of the electrode with the silicon-containing compound of the term [1] or [2] or a silicon-c
Kitano Makoto
Ueda Masato
Yahagi Isao
Fitch Even Tabin & Flannery
Owens, Jr. Howard V.
Sumitomo Chemical Company Limited
Wilson James O.
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