Thin film device and method of manufacture

Thin film devices including a film of a functional organic material, inorganic material or mixtures which are either insoluble or sparingly soluble in water, and deposited by electroplating. Particles of the functional material are dispersed in a micelle solution of a surfactant which is oxidizable and reducible by electrolysis in a colloidal state. Thin film devices prepared include color filters, optical recording media, electrochemical photoreceptors, nonlinear switching elements, and other devices requiring thin films of materials which are substantially insoluble in water.

BACKGROUND OF THE INVENTION 
The invention relates generally to a thin film device and more 
particularly, to a method of electrochemically depositing a thin film of 
material that is substantially insoluble in water. Electrochemical 
deposition is made possible by increasing the solubility of the substance 
which is either sparingly soluble or insoluble in water by providing a 
micelle solution of a surfactant and electrochemically depositing the 
substance on an electrode. Such thin films are advantageously included in 
color filters for display devices, optical disks, electrophotographic 
photoreceptors and nonlinear switching elements as well as a wide variety 
of other applications. 
Organic pigments such as phthalocyanine have recently become of interest as 
functional materials. The characteristic structure of these organic 
pigments are useful for photoconductors or optical devices. Because these 
organic pigments are generally either only sparingly soluble or insoluble 
in water, liquid processes are rarely adopted for producing thin films. 
Attempts have been made at converting substantially insoluble organic 
pigments into solvent-soluble pigments and forming a thin film by emersion 
coating methods or the like. Unfortunately, this method only provides an 
extremely thin film which has seriously restricted application of this 
method. 
Employing a Langmuir Blodgett technique has similar drawbacks. Fine 
particles of an organic pigment can be kneaded with an organic binder and 
thinly coated to form a functional film. However, this method is 
inadequate for fully utilizing the properties of the functional substance 
to be formed in the thin film due to the presence of the binder. 
Thin films of these substantially insoluble substances are conventionally 
formed by deposition, sputtering or chemical vapor deposition (CVD), but 
these methods also have drawbacks. For example, when a thin film is formed 
by one of these methods, the chemical structure of the thin film produced 
differs from that of the raw material and reproduction of the initial 
crystalline structure is often impossible even if the same chemical 
structure is produced. Further, such vacuum processes are expensive and 
improperly suited to mass production. 
Another technique for forming these films has been proposed by Saji and 
others (Chem. Lett., 1431, (1987), J. Am. Chem. Soc., 109, 5881 (1987), 
Chem. Lett., 893 (1988), Synopses of Lectures of 55th Meeting of the 
Electrochemical Society of Japan). This method forms a thin film by 
solubilizing a hydrophobic pigment or a polymer in an aqueous micelle of 
an oxidizable and reducible surfactant formed of a ferrocene derivative in 
an aqueous medium. The solubilized pigment or polymer is deposited on an 
electrode by electrolysis. However, surfactants and other substances 
heretofore reported as adaptable to this method are extremely limited. 
Accordingly, it is desireable to provide an improved method of depositing 
thin films of substantially insoluble substances by electrolytic 
technique. 
SUMMARY OF THE INVENTION 
Generally speaking, in accordance with the invention, a method of 
depositing a thin film of a substance which is substantially insoluble or 
sparing soluble in water by electrolysis of a solution and thin film 
devices prepared by this method are provided. The substance to be 
deposited includes a functional organic material, inorganic material or a 
mixture thereof. A surfactant is present in the solution and solubilizes 
the material to make electroplating of the functional material possible. 
In one embodiment novel surfactants are provided for film formation such 
as surfactants that are effective for forming a film of an organic 
pigment, such as a metal phthalocyanine pigment. 
Accordingly, it is an object of the invention to provide an improved method 
for electrochemically depositing a thin film of a functional material that 
is substantially insoluble in water. 
Another object of the invention is to provide thin film devices including 
thin films of various functional substances. 
A further object of the invention is to provide surfactants that are useful 
in solubilizing materials to enable the formation of thin films of 
substances by electrolysis. 
Still another object of the invention is to provide a method of improving 
the characteristics of thin film devices by forming the thin films by 
electrochemical techniques. 
Yet another object of the invention is to provide an improved method of 
manufacturing color filters for display devices, optical disks, 
electrophotographic photoreceptors and nonlinear switching elements. 
Still other objects and advantages of the invention will in part be obvious 
and will in part be apparent from the specification and drawings. 
The invention accordingly comprises the several steps and the relation of 
one or more of such steps with respect to each of the others, and the 
article possessing the features, properties, and the relation of elements, 
which are exemplified in the following detailed disclosure, and the scope 
of the invention will be indicated in the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A thin film is prepared in accordance with the invention by preparing an 
electrolytic solution including a surfactant which is oxidizable, and 
preferably also reducible by electrolysis. The solution is an aqueous 
micellar solution of a surfactant which is at least positively charged by 
electrolytic oxidation and preferably also negatively charged by 
electrolytic reduction. A supporting electrolyte is dissolved in the 
aqueous solution. A quantity of fine particles of a material which is 
sparingly soluble or insoluble in water is dispersed in the aqueous 
solution in a colloidal state due to the action of the surfactant. This 
material will form the desired thin film of the device. 
In general, not all of the particles of the material for the film, which 
are dispersed in aqueous micelle solution, assume a colloidal state. 
Typically, only the secondary particles assume a colloidal state. The 
secondary particles are an aggregate of the primary particles and have a 
particle size which allows them to be separated from the aggregate and to 
continue Brownian movement in the state of being surrounded by the micelle 
of the surfactant. 
The particles dispersed in the aqueous micelle solution effectively assume 
a colloidal state when the solution is mechanically agitated vehemently by 
a propeller mixer or the like, or when the particles are ultrasonically 
dispersed by an ultrasonic homogenizer, or mechanically dispersed by a 
ball mill or the like. Immediately after dispersion, the particles which 
become colloidal particles and the particles which are too large to become 
colloidal particles and which will eventually precipitate out, are mixed 
with each other and should be separated. Thus, the dispersion is permitted 
to stand for several hours and then the supernatant is collected. 
Alternatively, the particles which are too large to become colloidal 
particles are separated by centrifugal separation or other suitable 
separation means. 
Appropriate electrodes (an anode and a cathode) are next inserted in the 
colloidal electrolytic solution. Electrolysis is carried out at a constant 
voltage greater than or equal to the oxidation potential of the surfactant 
and electrolytic oxidation occurs on the surface of the anode. The 
surfactant which forms the micelle surrounding the particles of material 
for forming a thin film becomes positively charged all at once and the 
surfactant separates from the particles charged all at once and the 
surfactant film. As a result, the particles of the material for the film 
are released and deposit on the anode. After sufficient time, the anode 
becomes coated with a thin film of the desired material. 
Appropriate surfactants which will at least become positively charged by 
oxidation from electrolysis, include those having a metallocene group 
having the following chemical composition at the hydrophobic end: 
##STR1## 
wherein M represents a metal such as Ti, Cu, V, Fe, Co, Ni, Ru and Os. 
Metallocene groups, such as those including Fe are known. However, it has 
been determined that metallocene groups including mainly Cr and Ti also 
exhibit good film-forming properties. Because the oxidation potential of 
the compound varies with the metal, the metallocene group can be 
appropriately selected in accordance with the material of the anode. 
It is preferred that the main chain of the surfactant have a hydrophilic 
portion and that the whole molecule is sufficiently hydrophilic to be 
soluble in water and that the surfactant forms a micelle. The absorptivity 
of surfactants which satisfy the above-described conditions can be 
enhanced by enlarging the hydrophobic group. The hydrophilic group can 
also be relatively enlarged to allow the material for the film to assume a 
stable micelle colloidal state in water. 
It has also been found that surfactants having Cr or Ti in the metallocene 
group of the hydrophobic end group exhibit good properties in the 
formation of a metal phthalocyanine film. The chemical structure of such 
surfactants are as follows: 
##STR2## 
wherein M represents Cr or Ti. 
The materials for the thin film produced in accordance with the invention 
is not limited to those recited herein and may be either in organic 
material or an inorganic material as long as the surface of particles of 
the material can be surrounded by the micelle of the surfactant. Even if 
the surface of the particles is not hydrophobic, it can be used if the 
surface nature can be converted to a hydrophobic nature. 
Almost all organic pigments are usable as materials for a film formed in 
accordance with the invention. Inorganic materials such as, oxides, 
nitrides, carbides and carbon can also be used. In particular, inorganic 
oxides are easily formed into a film by converting the surface into a 
hydrophobic nature. A mixture of organic material and inorganic material 
can also be used. Both organic materials and inorganic materials may be 
composites of two or more materials. For example, when forming a color 
filter for a display from an organic pigment, use of a composite of 
pigments can produce a pigment film having optimum spectral 
characteristics, as will be described later. 
When manufacturing a thin film according to the invention, because the 
Brownian movement of the colloidal particles is the principal film-forming 
energy, the adhesion between the particles and the substrate (electrode) 
and the adhesion between the particles are weak. Accordingly, it is 
necessary to increase adhesion between the particles and the substrate and 
adhesion between the particles, especially during film formation by making 
the primary particles as small as possible. This enhances the surface 
energy and the cohesiveness of the primary particles. The diameter of the 
primary particles of the material for the film is preferably about 0.005 
to 0.5 .mu.m and more preferably about 0.005 to 0.05 .mu.m. 
A supporting electrolyte, such as an inorganic salt or an organic salt is 
added to the electrolytic solution if necessary. Since the supporting 
electrolyte is added mainly to improve the electrical conductivity of the 
solution, it is not particularly restricted to any type of materials as 
long as it does not obstruct formation of the micelle or formation of the 
film. The supporting electrolyte is preferably added before formation of 
the micelle. If it is added after the formation of a micelle, the micelle 
may be broken due to the influence of the added ions. This will cause 
re-cohesion of the material for film and interfere with desired film 
formation. 
Electroplating techniques in accordance with the invention can be used to 
add dopant to a substrate. Doping has conventionally been tried with a 
phthalocyanine material in dry processes only. However, it is also 
possible to add dopant in a wet process in accordance with this embodiment 
of the invention to provide conductivity to a substrate. An organic 
material such as an organic pigment can be used as a material for the 
film. Phthalocyanine materials exhibit excellent conductivity properties 
and are preferable. A halogen, such as bromine and iodine is effective as 
a dopant. 
Doping can be carried out by a wet process selected from the following two 
methods. One doping method uses a halogenated material as a supporting 
electrolyte in the electrolytic solution or adds a halogenated material 
such as LiBr, LiI, NaBr and NaI as a part of a supporting electrolyte to 
mix a halogen component with the film material during electrolysis. In 
another method, a thin film device is immersed in a solution containing a 
halogenated material. The halogen is introduced into the thin film by 
further electrolysis. 
Examples of applications of the invention include, but are not limited to 
forming a thin film for: a color filter for a display device; a layer for 
an optical recording medium; an electrophotographic photoreceptor for a 
recording device; and a nonlinearly conductive layer for an active 
element. These will be described as follows. 
It is also known to dispose a color filter at the inside of a display panel 
to add color to a liquid crystal display or a plasmatic display. Color 
filters are conventionally manufactured by relief dying, printing, pigment 
dispersion, deposition, electrode position or the like. A color filter is 
formed differently in accordance with the invention than conventional 
processes. A colored layer of the color filter is formed solely of an 
organic pigment by a liquid process at a low cost. Since the colored layer 
is formed solely of pigment, the spectral characteristics have good color 
purity even if the film thickness is about 1 .mu.m or less. 
A color filter prepared in accordance with the invention includes a 
transparent indium tin oxide (hereinafter referred to as "ITO") electrode, 
tin oxide electrode or the like, formed on a transparent substrate in a 
predetermined pattern and an organic pigment layer selectively formed on 
the transparent electrode. The electrodes on the transparent substrate 
(used as an anode) and an energizing electrode (used as a cathode) are 
immersed in a solution of a solubilized water-insoluble organic pigment in 
an aqueous micelle solution of a surfactant. Electrical conduction is 
established between a selected pattern of the transparent electrode and 
the cathode to deposit particles of the organic pigment on the selected 
portion of the transparent electrode. This process is repeated in an 
electrolytic solution containing different organic pigments and an other 
selected portions of the transparent electrode to form a multi-color 
filter for a liquid crystal display or the like. Using a thin film formed 
in accordance with the invention as a color filter for a liquid crystal 
display is advantageous because the transparent electrode used during 
electrolysis can be used for driving the liquid crystal without further 
processing. 
The desired spectral characteristics are the most important characteristics 
of a color filter. It is sometimes difficult to obtain a particular 
wavelength absorbance using only one kind of pigment for one colored 
layer. The invention solves this problem by dispersing at least two kinds 
of pigments in an electrolytic solution, so that the deposited film 
contains both pigments. A colored layer is thereby formed with the desired 
spectral characteristic. 
When forming a colored pattern of two or more colors on an electrode 
portion on which a pigment film has already been formed, energizing during 
another film forming step can result in another pigment film being 
unintentionally formed on the existing pigment film. To solve this 
problem, an insulating film or a highly resistive film is disposed on the 
unselected portion of the electrode pattern. This will prevent pigment 
from being deposited at non-desired locations. Afterwards, the resistive 
film can be removed. 
The insulating film or the highly-resistive film can be formed by various 
printing methods and photolithography methods. However, electrochemical 
polymerization is preferable in light of the costs involved. The material 
for the insulating film or high-resistance film is not specified herein, 
and a wide variety of materials are acceptable. 
In a liquid crystal display device, a light-shielding film is provided to 
prevent transmitted backlight from leaking through gaps between the 
electrode patterns. Leaking diminishes contrast between ON and OFF 
portions. A light-shielding film can be formed between the transparent 
electrodes supporting pigment films to yield a black matrix color filter, 
for example, as follows: 
A first method for providing a light-shielding film employs 
photolithography in accordance with the following process. 
1. A transparent electrode is formed on a transparent substrate in a 
predetermined pattern. 
2. A metal film is formed on the transparent electrode by electroplating or 
electroless plating. Electroplating makes it possible to form the metal 
film solely on the transparent electrode. When employing electroless 
plating, the metal film is formed on the entire surface of the substrate. 
The unnecessary portion of the metal film is then removed by 
photolithography, using a photosensitive resist or etching to leave the 
metal film only on the transparent electrode. Alternatively, it is 
possible to form a metal film only on the transparent electrode by using a 
mixed catalyst of Sn and Pd, which is unlikely to be adsorbed by a 
transparent substrate formed of an inorganic materials such as glass, 
quartz and rock crystal. 
3. The surface of the substrate on which the transparent electrode covered 
with the metal film is coated with a photosetting type photosensitive 
resin. The photosensitive resin can contain a light-shielding dye 
dissolved therein or a light-shielding pigment dispersed therein. The 
photosensitive resin can also lack dye or pigment. 
4. The side of the substrate not coated with the light-shielding film is 
exposed with UV light. The metal film on the transparent electrode 
functions as an exposure mask and only the resin between the transparent 
electrode patterns is set by the UV exposure. 
5. Subsequent developing and baking steps form a light-shielding film 
between the transparent electrode patterns. When using a photosensitive 
resin which does not contain dye or pigment at coating step 3, the resin 
is dyed in a subsequent dying step. 
6. After etching the metal film on the transparent electrode, a pigment 
film is formed in accordance with the invention to yield a color filter 
provided with a light-shielding film (black matrix). 
A second method for providing a light-shielding film employs a printing 
method. A liquid crystal panel including a light-shielding film is formed 
in accordance with the invention. A light-shielding film is formed with an 
ink containing a light-shielding material at the gaps between the 
transparent electrode patterns at which no pigment film for a color filter 
has been formed. Alternatively, a light-shielding film is formed on the 
substrate opposing the substrate having the transparent electrode, at 
positions facing gaps between the transparent electrode patterns of the 
color filter. The light-shielding material contained in the ink is not 
specified herein, but a non-conductive black pigment is preferable. 
A thin film formed in accordance with the invention such as one that can be 
included in an optical recording medium is described as follows. It is 
known to include organic compounds such as pigments in an optical 
recording medium. However, when conventional vacuum deposition techniques 
are used to manufacture optical recording media, the characteristics of 
the thin film produced are unstable and vary with the positional 
relationship between the source of evaporation and the substrate in the 
chamber as well as heating conditions. Further, production yield is low 
and costs involved are high because vacuum processes are expensive. 
Coating the substrate with an organic compound which is dissolved in an 
organic solvent has many advantages. However, many desirable compounds are 
only sparingly soluble in water. This severely limits the materials that 
can be coated in the manner. 
To solve these shortcomings, the following method can be employed. 
Ultra-fine particles of an organic optical recording material, which is 
sparingly soluble or insoluble in water, are surrounded by a surfactant 
which is oxidizable and reducible by electrolysis and the particles assume 
a colloidal state. An electrically conductive optical disk substrate is 
immersed in the colloidal solution and a voltage is applied between the 
optical disk substrate and an energizing electrode. A plastic substrate 
such as a polycarbonate substrate is commonly used as an optical disk 
substrate and can be made conductive by coating the substrate with a 
conductive oxide material such as ITO or SnO.sub.2 or a metal, by 
sputtering or vacuum deposition. The ultra-fine particles of the organic 
compound surrounded by the surfactant are then deposited on the substrate. 
A thin film of optical recording material as thereby formed. 
An electrophotographic photoreceptor including a thin film may be formed in 
accordance with the invention as follows. An organic carrier generating 
layer ("GCL") of an electrophotographic photoreceptor is generally 
disposed on a drum by vacuum deposition; a coating method in which a 
carrier generating substance is dissolved in an appropriate solvent; an 
isochronous pulling method or the like; or a dispersion coating method in 
which a carrier generating substance is ground into fine particles in a 
dispersion medium by a ball mill or the like and the fine particles are 
dispersed with an adhesive, if necessary. 
However, conventional vacuum deposition is not well suited to mass 
production techniques. Conventional coating methods are also disadvantages 
because it is difficult to form a uniform film and because it lowers the 
density of the organic photosensitive material when a carrier generating 
substance is dispersed in a resin such as a binder. Low density film leads 
to deterioration of the desired characteristics. 
To solve these problems, a high-efficiency carrier generating layer ("CGL") 
prepared in accordance with the invention form various organic 
photosensitive materials with high productivity by forming a high-density 
and high-purity film. First, an organic photosensitive material (organic 
pigment) having a low solubility is solubilized in a solution by the 
micelle formed by a surfactant containing a metallocene group to yield an 
electrolytic solution. Second, a support having electric conductivity such 
as a conductive drum and a counter electrode are immersed in the 
electrolytic solution. Third, voltage is applied between the support and 
the counter electrode. The organic photosensitive material in the micelle 
is thereby deposited on the support and forms a thin film CGL. 
A nonlinear switching element (active element) including a thin film formed 
in accordance with the invention can be prepared as follows. It is known 
that a thin film laminate structure including a first metal layer, an 
insulating film and a second metal layer (hereinafter referred to as a 
"MIM") exhibits a bi-lateral nonlinear voltage-current characteristic, as 
shown in FIG. 10. A MIM elements such as those formed of overlapping 
layers of Ta, Ta.sub.2 O.sub.5 and Cr have been put to practical use as 
liquid crystal switching elements for liquid crystal devices, such as LCD 
televisions. 
An important factor in the efficiency of a MIM element used as a liquid 
crystal driving switching element is a steep nonlinear drop of the 
resistance to current with increasing voltage. It is therefore necessary 
that a voltage applied to the switching element is sufficient for 
retaining the switching function. Specifically, if it is assumed that the 
MIM element and the liquid crystal device have a linear structure, the 
capacitance of the element, i.e. the capacitance of the insulating layer 
should be as small as is practical. 
When including inorganic oxides as the insulating material, the dielectric 
constant thereof is generally large. For example, it ranges from about 25 
to 27 in the case of a Ta.sub.2 O.sub.5 insulating layer. Therefore, in 
order to reduce the capacitance, the area of the element should be reduced 
or the thickness of the insulating material should be increased. This 
relationship is illustrated by the following equation: 
##EQU1## 
wherein: .epsilon. is the dielectric constant; 
S is the effective area; and 
d is thickness. 
However, when the thickness is increased, the resistance also increases, 
often to unacceptable values. Accordingly, the capacitance is generally 
reduced by reducing the effective area of the element. The area of the 
switching element commonly included in a liquid crystal television is 5 
.mu.m square. This requires precise manufacturing techniques. Further, 
extensive use of vacuum film-forming apparatuses and dry etching devices 
reduces manufacturing throughput, and disadvantageously raises 
manufacturing costs. 
As described above, it has not been possible to produce a bi-lateral 
nonlinear liquid crystal driving switching element conveniently at low 
cost. To solve the shortcomings of the prior art, an organic material 
having a small dielectric constant is used as an insulating material. This 
allows the switching element to be formed with a large area. For example, 
the insulating material can be formed from a phthalocyanine material, 
which is chemically stable, by an electrochemical process to reduce 
manufacturing costs. 
It is known that phthalocyanine materials exhibit what is called diode 
characteristics. However, it has not been previously reported that 
phthalocyanine materials exhibit uniform bi-lateral nonlinear 
characteristics such as that shown in FIG. 10. A nonlinear switching 
element can be formed in accordance with the invention by forming an 
insulating film on a conductive material with a wet electrochemical 
process. A film of a conductive material is then formed on the insulating 
film to yield a MIM element. 
The insulating film is formed by first dispersing the particles of a 
non-linearly conductive material in an aqueous micelle surfactant 
solution. The solution is then charged during electrolysis so that the 
particles are surrounded by the micelle of the surfactant in a colloidal 
state. A conductive material on the substrate of the thin film device is 
immersed in the solution as an electrode for effecting electrolysis. The 
current electrically destroys the micelle and the particles of the 
non-linearly conductive material surrounded by the micelle are deposited 
on the conductive material. 
A metal or an oxide conductive material such as In.sub.2 O.sub.3 and 
SnO.sub.2 and the like are preferable as the conductive materials for the 
substrate. A phthalocyanine material is preferable as the insulating 
material of the primary particles. A metal or an oxide conductive material 
are preferable as the conductive material covering the insulating film. 
The invention will now be explained in greater detail with reference to the 
following examples. These examples are presented for the purpose of 
illustration only, and are not intended to be construed in a limiting 
sense. 
EXAMPLE 1 
Several thin film devices were manufactured with various organic pigments 
as the thin films, including copper phthalocyanine, halogenated copper 
phthalocyanine, anthraquinone pigments, thioindigo pigments, 
monochlorocopper phthalocyanine, perylene pigments, quinacridone pigments, 
dioxazine pigments, nitro pigments, nitroso pigments, azo complex salt 
pigments, condensed azo pigments, metal complex pigments, benzoimidazolone 
pigments, aniline black, daylight fluorescent pigments, isoindolinone 
pigments, quinophthalone pigments, perinone pigments and 
diketopyrrolopyrrole pigments. 
The following four surfactants were used to form the micelle. 
##STR3## 
Surfactants A and B were developed by the inventors to obtain optimum 
film-forming properties of phthalocyanine materials. Surfactants C and D 
are commercially available. Experimental conditions and pigment films 
prepared are listed in Table 1. 
To form thin films of pigment on a substrate, the surfactant, and the 
supporting electrolyte were dissolved in 600 ml of water and 2 to 10 g/l 
of an organic pigment was added. The organic pigment will form the film. 
The pigment was dispersed for 1 hour by an ultrasonic homogenizer 
(RUS-600, produced by Nihon Seiki) and after the dispersion was allowed to 
stand for 12 hours, 100 ml of the supernatant was collected. 
The collected liquid was charged in an H-type cell and electrolysis was 
carried out for 30 minutes in a nitrogen atmosphere, using a glass 
substrate having an ITO film formed thereon as an anode; a platinum plate 
as a cathode; and a saturated calomel electrode (hereinafter referred to 
as "S.C.E.") as a reference electrode. After electrolysis was completed, 
the substrate on which the film was formed was washed with water and 
dried. 
Electrolysis was carried out in an N.sub.2 atmosphere to prevent oxidation 
of the surfactant. The pigment added to the liquid had been pulverized 
chemically or physically and had a particle diameter of not more than 
about 0.5 .mu.m. 
These experiments show that films of various pigments were acceptably 
produced by a wet electrochemical process. Typical films formed in 
accordance with the invention are shown in Table 1. However, the pigments, 
surfactants and supporting salts used in accordance with the invention are 
not limited to those shown in Table 1. Both surfactant A and B exhibited 
good film-forming properties with respect to metal phthalocyanine 
pigments. 
__________________________________________________________________________ 
Supporting 
Surfactant 
electrolyte 
anode thickness of 
Pigment Kind 
concn. 
Kind 
concn. 
potential* 
depo film 
Remark 
__________________________________________________________________________ 
1 
.alpha. type copper 
A 3.sup.mM 
LiBr 
0.05.sup.M 
+1.0V 0.9.sup..mu.m 
Dainichi 
phthalocyanine Seika K.K. 
2 
Phthalocyanine 
A .uparw. 
.uparw. 
.uparw. 
.uparw. 
1.1 BASF 
Green 
3 
Dianthraquinonyl 
A .uparw. 
.uparw. 
.uparw. 
.uparw. 
1.0 Pigment Red 177 
red 
4 
Thioindigo 
A .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.4 Pigment Violet 177 
Magenda 
5 
Monochlorocopper 
B 2 KCl 0.1 .uparw. 
0.7 Dainichi 
phthalocyanine Seika K.K. 
6 
Perylene B .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.8 Pigment Red 190 
Red 
7 
Quinacridone 
B .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.6 Pigment Violet 19 
Red 
8 
Dioxazine C 3 Li.sub.2 SO.sub.4 
0.05 
+0.45 0.8 Pigment Violet 23 
Violet 
9 
Naphthol C .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.4 Acid Yellow 1 
Yellow-S 
10 
Naphthol C .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.4 Pigment Green 8 
Green-B 
11 
Nickel C .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.5 -- 
Azoyellow 
12 
Chromophthal 
C .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.5 Pigment Yellow 95 
Yellow-GR 
13 
Irgazine C .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.4 Pigment Red 129 
Yellow-5GLT 
14 
Aniline C .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.4 Pigment Red 176 
Black 
15 
Lumogen C .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.4 Pigment Black 1 
Yellow 
16 
Benzoimida- 
C .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.4 BASF 
zolone HF3C 
17 
Isoendorinone 
D 2 .uparw. 
.uparw. 
+0.6 0.4 Pigment Yellow 109 
Yellow Greenish 
18 
Quinophthalone 
D .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.4 Pigment Yellow 138 
Yellow 
19 
Perinone D .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.5 Pigment Orange 43 
Orange 
20 
Irgazine DPP 
D .uparw. 
.uparw. 
.uparw. 
.uparw. 
0.4 Pigment Red 254 
Red 80 
__________________________________________________________________________ 
EXAMPLE 2 
Ferrocenyl-PEG (produced by Dojin Kagaku) having a metallocene group 
containing Fe was included as a surfactant for an electrolyte solution for 
forming a thin film. 1 liter of an aqueous micelle solution containing 4 
mM of Ferrocenyl-PEG was prepared and 0.1M/l of LiBr was added as a 
supporting electrolyte. 15 g of a carbon powder having a particle diameter 
of 0.05 .mu.m (the primary particles) was added to the solution as an 
inorganic material and dispersed by an ultrasonic homogenizer. 
A platinum plate counter electrode, a saturated calomel reference electrode 
(S.C.E.) and a glass substrate provided with an ITO film sample electrode 
were immersed in the dispersion. Electrolysis was conducted for 1 hour at 
an electrolytic potential of +0.5 V (vs. S.C.E.) and an acceptable carbon 
film was formed on the ITO film by this wet process. 
EXAMPLE 3 
An aqueous micelle solution containing Ferrocenyl-PEG was prepared as in 
Example 2. 15 g of a silica powder which had been treated to be 
hydrophobic was added and dispersed by an ultrasonic homogenizer. To make 
the silica powder hydrophobic, epoxy silane (SH-6040, produced by TORAY) 
was dissolved in silica sol (produced by Shokubai Kasei, particle 
diameter: 0.02 .mu.m) which had been dispersed in isopropyl alcohol and 
had a concentration of 5 wt %. After the solvent evaporated, the residue 
was baked at 120.degree. C. for 1 hour to introduce the epoxy group into 
the surface of the silica particles. After the residue was baked, the 
silica particles were pulverized into particles having a diameter of not 
more than about 0.4 .mu.m. 
A platinum plate counter electrode, a saturated calomel electrode reference 
electrode (S.C.E.) and a glass substrate provided with an ITO film sample 
electrode were immersed in the dispersion. Electrolysis was conducted for 
1 hour at an electrolytic potential of +0.5 V (vs. S.C.E.). An acceptable 
SiO.sub.2 film was formed on the ITO film. 
EXAMPLE 4 
The following substance having a metallocene group containing Cr was used 
as the surfactant: 
##STR4## 
1 liter of an aqueous micelle solution containing 3 mM of the surfactant 
was prepared and 0.1M of LiBr was added thereto as a supporting 
electrolyte. 
Monochlorocopper phthalocyanine and a phthalocyanine pigment were 
pulverized by a sand mill so that the maximum particle diameter of the 
primary particles were not more than about 0.4 .mu.m. The average particle 
diameter was not more than about 0.05 .mu.m. Particle diameter was 
measured by an SEM (S-900, produced by Hitachi, Ltd.). 5 g of the 
thus-prepared phthalocyanine was added to the micelle solution and 
dispersed by an ultrasonic homogenizer. 
A platinum plate counter electrode, a saturated calomel electrode (S.C.E.) 
reference electrode and a glass substrate provided with an ITO film sample 
electrode were immersed in the dispersion. Electrolysis was conducted for 
30 minutes at an electrolytic potential of +1.0 V (vs. S.C.E.). An 
acceptable 4,000 .ANG. thick film of monochlorocopper phthalocyanine was 
formed on the ITO film. The substrate was washed with running water, dried 
by blowing air and then baked at 200.degree. C. for 1 hour. When adhesive 
tape was pressed to the substrate and stripped off, as an adhesion test, 
the monochlorocopper phthalocyanine film was not stripped from the ITO 
film at all. 
For comparison, 5 g of monochlorocopper phthalocyanine was added to a 
micelle solution prepared as in the above experiment. This sample was not 
pulverized with a sand mill. The maximum diameter of the primary particles 
was 1 .mu.m and more than 70% of the primary particles had a diameter 
larger than 0.5 .mu.m. Particle diameter was similarly measured by the 
SEM. 
These particles were dispersed in the micelle solution as above and film 
formation on a glass substrate having an ITO film was attempted. When the 
substrate was drawn out of the solution, almost half the area of the film 
was stripped off. Accordingly, it has been determined that particle 
diameter has significant influence on the adhesion and the particle 
diameter should be not more than 0.5 .mu.m. Preferably it should not be 
more than 0.05 .mu.m. 
EXAMPLE 5 
1 liter of an aqueous micelle solution containing 10 mM of Ferrocenyl-PEG 
was prepared. 20 g of carbon powder having an average primary particle 
diameter of about 0.05 .mu.m and 0.1M of LiBr were added as an inorganic 
material and a supporting electrolyte, respectively, and dispersed by an 
ultrasonic homogenizer. A carbon film was formed from the dispersion on a 
glass substrate provided with an ITO film as in Example 1. The substrate 
was immersed in still water, washed then dried with hot air. The carbon 
film was formed with good adhesion and without being stripped off. 
In the same manner, a carbon powder having an average primary particle 
diameter of 3 .mu.m was dispersed in the micelle solution. Although a 
carbon film was formed on a glass substrate provided with an ITO film in 
the same way, the adhesiveness of the carbon film was poor because of the 
large particle size and almost no film was formed. The particle diameter 
also an influence on the adhesion in an inorganic material. The preferred 
particle diameter is not more than about 0.5 .mu.m, more preferably not 
more than 0.05 .mu.m. 
EXAMPLE 6 
1 liter of an aqueous micelle solution containing 3 mM of the following 
sufficient was prepared: 
##STR5## 
0.1M of LiBr was added and as a supporting electrolyte and potassium 
iodide was added as an iodine doping electrolyte. 14 g of Heliogen Green 
D914 produced by BASF was added to the solution and suspended in the 
solution by a 15-minute ultrasonic treatment. The suspension was 
vehemently shaken for about 100 hours by a shaker and then allowed to 
stand. Thereafter the supernatant was collected and the particles which 
were not in a colloidal state were separated out. 
The supernatant was charged into an H-type cell, and a glass substrate 
provided with an ITO film anode, a platinum plate cathode and a saturated 
calomel reference electrode (S.C.E.) were immersed. Electrolysis was 
performed for 30 minutes in an N.sub.2 atmosphere at an electrolytic 
potential of +1.1 V (vs. S.C.E.). An iodine-doped phthalocyanine film was 
formed on the glass substrate provided with the ITO film. The film was 
about 5,000 .ANG. thick and an electric conductivity of about 1.0 S/cm. 
The film formed without iodine doping had an electric conductivity of only 
about 1.times.10.sup.-10 S/cm. 
EXAMPLE 7 
Pulse electrolysis was carried out by using a solution and a cell similar 
to those used in Example 6. Repetitive pulses of 9 seconds at an 
electrolytic potential of +0.9 V (vs. S.C.E.) were applied for 30 minutes 
to obtain a phthalocyanine-iodine film on the ITO film on the glass 
substrate. The film was about 4,500 .ANG. thick and had an electric 
conductivity of about 1.times.10.sup.-1 S/cm. 
EXAMPLE 8 
1 liter of an aqueous micelle solution containing 4 mM of a surfactant 
similar to that of Example 6 was prepared. 0.2M of LiI was added as both a 
supporting electrolyte and an iodine doping electrolyte. 10 of .alpha. 
type copper phthalocyanine was added to the solution as a phthalocyanine 
pigment and treated for 1 hour by an ultrasonic homogenizer. After the 
suspension was allowed to stand, the supernatant was collected. 
The supernatant was charged into an H-type cell, and a glass substrate 
provided with an ITO film, a platinum plate and a saturated calomel 
electrode (S.C.E.) were immersed as an anode, a cathode and a reference 
electrode, respectively. Electrolysis was performed for 40 minutes at an 
electrolytic potential of +0.7 V (vs. S.C.E.). An iodine-doped 
phthalocyanine film was formed on the glass substrate provided with the 
ITO film. The film was about 6,000 .ANG. thick and had an electric 
conductivity of about 2.0 S/cm. The film formed without iodine doping had 
an electric conductivity of about 1.times.10.sup.-11 S/cm. 
EXAMPLE 9 
1 liter of an aqueous micelle solution containing 4 mM of a surfactant 
similar to that of Example 6 was prepared. 0.2M of LiBr was added thereto 
as a combined supporting electrolyte and a bromine doping electrolyte. 10 
g of .alpha. type copper phthalocyanine was added to the solution as a 
phthalocyanine pigment and dispersed for 1 hour by an ultrasonic 
homogenizer. After the suspension was allowed to stand, the supernatant 
was collected. 
The supernatant was charged into an H-type cell, and a glass substrate 
provided with an ITO film, a platinum plate and a saturated calomel 
electrode (S.C.E.) were immersed as an anode, a cathode and a reference 
electrode, respectively. Electrolysis was performed for 30 minutes in an 
N.sub.2 atmosphere at an electrolytic potential of +1.0 V (Vs. S.C.E.). A 
bromine-doped phthalocyanine film was formed on the glass substrate 
provided with the ITO film. The film was about 5,000 .ANG. thick and had 
an electric conductivity of about 1.times.10.sup.-2 S/cm. Thus, the doping 
effect of lowered resistivity was observed. 
EXAMPLE 10 
1 liter of an aqueous micelle solution of 3 mM of the following surfactant 
was prepared: 
##STR6## 
0.1M of Li.sub.2 SO.sub.4 was added as a supporting electrolyte and 10 g 
of a .beta. type copper phthalocyanine was added to the solution as a 
phthalocyanine pigment and dispersed in the solution for 90 minutes by an 
ultrasonic homogenizer. After the dispersion was allowed to stand, the 
supernatant was collected and the particles which were not in a colloidal 
state were separated out. 
The supernatant was charged into an H-type cell, and a glass substrate 
provided with an ITO film, a platinum plate and a saturated calomel 
electrode (S.C.E.) were immersed as an anode, a cathode and a reference 
electrode, respectively, to effect electrolysis for 30 minutes in an 
N.sub.2 atmosphere at an electrolytic potential of +0.8 V (vs. S.C.E.). A 
5,000 .ANG. thick phthalocyanine film was formed on the ITO film on the 
glass substrate. 
The glass substrate provided with the ITO film and the phthalocyanine film 
formed thereon was immersed in a solution of 1.0M of potassium iodide. 
Electrolysis was carried out for 10 minutes at an electrolytic potential 
of +1.1 V (vs. S.C.E.) using the glass substrate with the ITO film and the 
phthalocyanine film formed thereon as an anode and a platinum plate as a 
cathode. After the iodine-doped phthalocyanine film was dried at 
150.degree. C., the electric conductivity was measured at 1.5 S/cm. The 
film formed without iodine doping had an electric conductivity of about 
1.times.10.sup.-10 S/cm. 
EXAMPLE 11 
A phthalocyanine film was formed on a glass substrate provided with an ITO 
film as in Example 10 and iodine was doped by using 1.0M of LiI solution 
as in Example 10. The electrolytic potential was +0.7 V (vs. S.C.E.) and 
the duration of electrolysis was 10 minutes. After the thus obtained 
iodine-doped phthalocyanine was heated and dried at 150.degree. C., the 
electric conductivity was measured 1.4 as S/cm. 
In Examples 6 to 11, it was possible to subject the phthalocyanine pigment 
to doping treatment to make it conductive by a wet process simultaneously 
or continuously with formation of the thin film. 
Iodine and bromine were deposited only on the electrode and not on any 
other portions. Because doping is carried out in a solution, this method 
for making the pigment conductive dispenses with the need for 
countermeasures for the leakage of discharged gas or the like. Since it is 
possible to apply a uniform voltage to the electrode, the characteristic 
in plane is made uniform. 
This doping method has advantages over conventional doping methods using 
vapor techniques in terms of both cost and characteristics of the 
resulting film. It is expected that these film forming techniques will 
greatly increase the applications of phthalocyanine pigments in electronic 
materials. 
EXAMPLE 12 
A thin film device formed in accordance with the invention has applications 
in providing color filters for liquid crystal display panels. A 1,000 
.ANG. thick ITO film was formed by sputtering on a soda glass substrate 
having a 6 inch diagonal, while heating the substrate to 300.degree. C. 
The ITO film was patterned into a predetermined pattern by 
photolithography. A selected portion of the ITO film portion was connected 
to a power source and immersed together with a platinum plate as a counter 
electrode in an electrolytic solution with an organic pigment dispersed 
therein. 
The electrolytic solution was prepared as follows. A Ferrocenyl-PEG 
(produced by Dojin Kagaku) surfactant having a metallocene group was 
included. 1 liter of an aqueous micelle solution containing 3 mM of 
Ferrocenyl-PEG was prepared. 0.2M of LiBr was added as a supporting 
electrolyte and 1.2 g of a red anthraquinone pigment, Chromophthal A3B 
(produced by Chiba Geigy) was added as an organic pigment. Those 
substances were suspended in the aqueous micelle solution of the 
surfactant by stirring. The suspension was ultrasonically treated for 1 
hour by an ultrasonic homogenizer and after it was allowed to stand for 12 
hours, 0.8 liter of the supernatant was collected as the electrolytic 
solution. 
A voltage was applied to the predetermined pattern of the ITO film while 
using the selected portion of the ITO pattern on the glass substrate, a 
platinum plate, and a saturated calomel electrode (S.C.E.) as an anode, a 
cathode and a reference electrode, respectively, so as to effect 
electrolysis for 30 minutes at an electrolytic potential of +0.4 V (vs. 
S.C.E.). After electrolysis, the glass substrate provided with the ITO 
film was washed with water and dried. A 0.8 .mu.m thick red pigment film 
of Chromophthal A3B was formed on the selected portion of the ITO pattern. 
An electrolytic solution was prepared by mixing 1 liter of an aqueous 
micelle solution containing 3 mM of Ferrocenyl-PEG (produced by Dojin 
Kagaku) as a surfactant, 0.2M of LiBr as a supporting electrolyte and 1.2 
g of a blue anthraquinone pigment, Indanthrene Blue (Pigment Blue 60, CI 
69800) as an organic pigment. A voltage of +0.4 V (vs. S.C.E.) was applied 
to another selected portion of the ITO pattern using the glass substrate 
with the selected portion of the patterned ITO film and a platinum plate 
as an anode and a cathode, respectively, to effect electrolysis. A 0.7 
.mu.m thick blue pigment film was formed on the selected portion. 
An electrolytic solution was prepared containing using a green organic 
metal phthalocyanine pigment, Heliogen Green D9140 (produced by BASF). 
The ITO substrate with the red and blue pigment films formed thereon was 
immersed together with a platinum plate in the electrolytic solution. A 
potential of +0.5 V (vs. S.C.E.) was applied to a selected portion of the 
ITO pattern with no pigment film formed thereon for 30 minutes to effect 
electrolysis. A green phthalocyanine film of 0.8 .mu.m thick was formed on 
the selected portion. 
In this manner, a three-color filter having red, blue and green pigment 
film sections formed on predetermined portions of an ITO pattern was 
obtained, as shown in FIG. 1. Since the color filters included only 
pigment, it exhibited sufficient color densities in the respective film 
thicknesses. Using this color filter, a TN liquid crystal panel with a 
cell gap thickness of 10 .mu.m was assembled. 
By applying a voltage sine wave of 64 Hz to the red picture elements, the 
relationship between the practically applied voltage of the liquid crystal 
panel and the intensity of the light transmitted through the liquid 
crystal panel was examined. For comparison, a liquid crystal panel having 
a color filter produced by a relief dying method and a liquid crystal 
panel having no color filter were prepared and their properties were 
examined. The dyed color filter was obtained by spin coating a 1.5 .mu.m 
thick photosensitive gelatin layer on a glass substrate provided with an 
ITO pattern and dying the photosensitive gelatin layer red with an acidic 
dye. The film thickness was 1.5 .mu.m in order to obtain the color density 
of the same degree as that of the red pigment filter formed above in 
accordance with the invention. 
The results of these tests are shown in FIG. 2. The abscissa represents the 
effective applied voltage and the ordinate represents the transmittance 
ratio. The relationship between the voltage and transmittance is based on 
the assumption that the transmittance at an applied voltage of 0 is 0, and 
the maximum light transmittance of each panel is 100, to facilitate 
comparisons. 
The threshold potential of the liquid crystal panel formed in accordance 
with the invention, represented by a curve 1, is about 5% higher than that 
of the liquid crystal panel without a color filter layer, represented by a 
curve 2. However, when compared with the liquid crystal panel having a 
color filter produced by a relief dying method, represented by a curve 3, 
the liquid crystal panel of the invention (curve 2) exhibits a large 
reduction in the threshold voltage and a steep change in transmittance. 
These are desirable characteristics for a color liquid crystal panel. 
These desirable characteristics are ascribed to the fact that the color 
filters prepared in accordance with the invention were formed only of 
pigment. In addition to having superior voltage-transmittance 
characteristics, by manufacturing a color filter in accordance with the 
invention which uses photolithography only in patterning the ITO layer and 
does not employ a vacuum apparatus, the mass production characteristics 
are also superior. 
The electrode used for electrolysis in accordance with the invention is 
also the electrode for driving a liquid crystal display. However, the 
increase in driving voltage when a color filter layer is formed on the 
electrode is very small and the margin for the withstand voltage of a 
conventional integrated circuit ("IC") is increased. In addition, since it 
is possible to form an ITO film for driving a liquid crystal (the ITO film 
used for electrolysis) on a glass substrate the ITO film has high 
crystallinity, low resistivity and high durability, the color filter 
results in a liquid crystal panel having high reliability. 
EXAMPLE 13 
To form a blue violet colored layer, 100 ml of a colloidal solution of two 
different pigments having the following composition was prepared. 
1. Pigment: 
a. .beta. type copper phthalocyanine (blue green pigment)--7 mM 
b. Dianthraquinonyl Red (red violet pigment)--3 mM 
2. Surfactant which is oxidizable and reducible by electrolysis: 
Ferrocenyl-PEG (produced by Dojin Kagaku)--2.5 mM 
3. Supporting electrolyte: 
LiBr--0.05M 
A 1,500 .ANG. thick transparent ITO film electrode was formed into a stripe 
pattern on a borosilicate glass substrate having a 5 inch long diagonal, 
as shown in FIG. 3. Electric conduction was selectively established on a 
pattern 1. The borosilicate glass substrate, a platinum electrode and a 
saturated calomel electrode (S.C.E.) were immersed in the above aqueous 
solution as an anode, a cathode and a reference electrode, respectively. 
Electrolysis was carried out in a nitrogen atmosphere at an electrolytic 
potential of +0.4 V (vs. S.C.E.) for 30 minutes. After electrolysis, the 
substrate was washed with water and baked at 180.degree. C. so to enhance 
the adhesion of the deposited film. A 7,000 .ANG. thick vivid blue violet 
pigment thin film was formed on ITO stripe pattern 1. The spectral 
characteristic of the pigment thin film was sufficient as a color filter, 
as indicated by a curve 1 in FIG. 4. 
A green colored film was formed on the substrate provided with the blue 
violet film, electric conduction was selectively established on an ITO 
pattern 2. Electrolysis was carried out in a micelle colloidal solution 
containing two kinds of pigments having the following composition under 
the same conditions as in forming the blue violet film. 
1. Pigment: 
a. .beta. type phthalocyanine (blue green pigment)--6 mM 
b. Quinophthalone pigment (yellow pigment) Paliotol Yellow LO962HD, 
produced by BASF--4 mM 
The remainder of the composition was the same as in forming the blue violet 
film. 
An 8,500 .ANG. thick vivid green pigment thin film was formed selectively 
on conductive ITO stripe pattern 2. The spectral characteristic of the 
pigment film was sufficient as a color filter, as indicated by a curve 2 
in FIG. 4. 
A red colored layer was formed on the substrate already provided with the 
blue violet thin film and the green thin film, electric conduction was 
selectively established on an ITO pattern 3 in FIG. 3. Electrolysis was 
carried out in a micelle colloidal solution containing three kinds of 
pigments having the following composition, under the same conditions as in 
forming the blue violet film. 
1. Pigment: 
a. Dianthraquinonyl Red (red violet pigment)--7 mM 
b. Quinophthalone pigment (yellow pigment) Paliotol Yellow LO962HD, 
produced by BASF--2 mM 
c. Thioingido magenta (red violet pigment)--1 mM 
The remainder of the composition was the same as in forming the blue violet 
film. A 9,000 .ANG. thick vivid red pigment thin film was formed on a 
selectively conductive ITO stripe pattern 3. The spectral characteristic 
of the pigment thin film was sufficient as a color filter, as indicated by 
a curve 3 in FIG. 4. 
A set of curves 4, 5 and 6 in FIG. 4 show examples of the spectral 
characteristics of conventional color filters formed of only one kind of 
pigment, i.e., .alpha. type copper phthalocyanine, halogen-substituted 
copper phthalocyanine, and dianthraquinonly red, respectively. As shown, 
all of these conventional color filters have insufficient spectral 
characteristics. However, as described above, a color filter including 
three primary colors, red, green and blue violet having good spectral 
characteristics such as those represented by curves 1, 2 and 3 in FIG. 4 
can be obtained when the films are prepared in accordance with the 
invention. 
Color filters formed in accordance with the invention are not restricted to 
a three-color filter and the order of layering the colored films is not 
restricted to that of Example 13. Accordingly, the manufacture of color 
filters having desired spectral characteristics is facilitated by using an 
electrolytic solution containing a mixture of a plurality of pigments. The 
electrochemical deposition in accordance with the invention facilitates 
the production of a rich variety of color tones and is therefore effective 
for the application of decoration or the like. 
EXAMPLE 14 
FIG. 5 above shows a 5 inch diagonal transparent substrate 50 having a 
transparent ITO electrode formed thereon in a stripe pattern. To form a 
blue violet colored layer, 1,000 ml of a colloidal solution containing a 
pigment and having the following composition was prepared. 
______________________________________ 
1. Pigment: 
Monochlorocopper phthalocyanine 
7 mM 
2. Surfactant which is charged by electrolysis: 
Ferrocenyl-PEG (produced by Dojin Kagaku) 
3 mM 
3. Supporting electrolyte: 
LiBr 0.05 M 
______________________________________ 
Electrical conduction was established selectively by disposing a carbon 
paste on a selected electrode pattern 1 at the position represented by a 
broken line 4 in FIG. 5. Transparent substrate 50 was immersed in the 
colloidal solution. The region of the transparent substrate immersed in 
the colloidal solution is represented by a double arrow 5. 
Electrolysis was carried out at a constant voltage of 0.9 V for 30 minutes, 
using transparent electrode 1 as an anode and a stainless plate as a 
cathode. In this manner, an 8,000 .ANG. thick blue violet pigment film of 
monochlorocopper phthalocyanine was formed on stripe electrode pattern 1 
in the region immersed in the solution. The substrate was washed with 
water and baked at 180.degree. C. to improve adhesion of the pigment film 
to electrode 1. 
An aqueous solution having the composition listed below was prepared. 
Electric conduction was selectively established at the position 
represented by a broken line 4 in FIG. 5 as described above. The substrate 
provided with the blue violet film was immersed in the solution in the 
region designated by a double arrow 6. Electrolysis was carried out at a 
constant potential of +0.7 V with respect to a saturated calomel electrode 
for 10 minutes. 
Composition of electrolytic solution: 
______________________________________ 
Aniline 0.1 M 
Mg(ClO.sub.4).sub.2 
0.05 M 
______________________________________ 
As a result, a 7,000 .ANG. thick electrochemically polymerized aniline film 
having a high electric resistance was formed only in a region represented 
by a double arrow 7 of electrode pattern 1. No aniline polymerized film 
was formed on the blue violet monochlorocopper phthalocyanine film, which 
was conductive, because the surface potential of the monochlorocopper 
phthalocyanine film does not reach the potential at which aniline is 
polymerized. This is due to the potential drop. The substrate was washed 
with water and dried at 120.degree. C. for 15 minutes. 
Electrical conduction was selectively established by disposing a carbon 
paste on the substrate at the position represented by a broken line 8 in 
FIG. 5, overlapping the aniline layer, so that conduction was not 
established with pattern electrode 1. Transparent substrate 50 was 
immersed in a colloidal solution containing a pigment, having the 
composition described below. Electrolysis was carried out under the same 
conditions in the above-described colloidal solution of the pigment. 
______________________________________ 
1. Pigment: 
Dianthraquinonyl Red 8 mM 
2. Surfactant which is charged by electrolysis: 
Ferrocenyl-PEG (produced by Dojin Kaguku) 
3 mM 
3. Supporting electrolyte: 
LiBr 0.05 M 
______________________________________ 
A red film of dianthraquinonyl red was formed only on an electrode pattern 
2 and was not formed on the blue violet pigment film formed on electrode 
pattern 1. 
The red pigment film was selectively formed only on electrode pattern 2 
because the aniline polymerized film present at the portion of electrode 
pattern 1 to which the carbon paste was applied insulated electrode 
pattern 1 so that electrical polymerization did not occur at pattern 1. 
The transparent substrate was heated and baked at 180.degree. C. for 30 
minutes to enhance the adhesion of the red pigment film. 
Electric conduction was established selectively only on an electrode 
pattern 3 at the position represented by a broken line 9 in FIG. 5. 
Electrolysis was carried out in a colloidal solution containing a pigment 
and having the composition described below. The conditions for 
electrolysis were the same as during formation of the above-described 
color pigment films. 
______________________________________ 
1. Pigment: 
Copper phthalocyanine bromochloride 
8 mM 
2. Surfactant which is charged by electrolysis: 
Ferrocenyl-PEG (produced by Dojin Kaguku) 
3 mM 
3. Supporting electrolyte: 
LiBr 0.05 M 
______________________________________ 
In this manner, an 8,500 .ANG. thick green pigment film was formed on 
electrode pattern 3. 
In this fashion, a color filter formed with the three primary colors of 
blue, red and green was obtained. However, the pigments, surfactant, 
supporting electrolyte and film-forming conditions in accordance with the 
invention are not restricted to those in Example 14. Further, materials 
for the insulating film or high resistance film formed by electrochemical 
polymerization and the film forming conditions are not restricted to those 
described in Example 14. Dimethyl aniline, diethyl aniline, pyrrole, 
dimethyl phenol and diethyl phenol are also effective as primary 
materials. 
As described above, it is easy to form a new color pigment film selectively 
on a substrate already supporting a conductive pigment film of another 
color on the desired electrode pattern without overlapping with the 
previously formed pigment film. The film forming method in accordance with 
invention is simple, low in cost and well suited for mass production. 
EXAMPLE 15 
1. An ITO film having a predetermined pattern 2 was formed on a transparent 
glass substrate 1 as shown in FIG. 6A. 
2. Substrate 1 was immersed in a mixed catalyst of Sn and Pd prepared in 
advance (HS-101B, produced by Hitachi Chemical Co., ltd.) for 1 minute 
then thoroughly washed with water. Thereafter, substrate 1 was immersed in 
inaqueous NaOH solution for 1 minute for acceleration then thoroughly 
washed with water. Substrate 1 was immersed in a nickel electroless 
plating solution (S680, produced by Nihon Kanizen) at 50.degree. C. for 5 
minutes. An electrolessly plated 4,000 .ANG. thick nickel film 3 was 
formed only on ITO film 2 as shown in FIG. 6B. 
3. Nickel-plated surface 3 of substrate 1 was coated with a 2 .mu.m thick 
black overcoat layer 4 having oxygen barrier properties by spin coating a 
black overcoat of a color mosaic system produced by Fuji Hanto Electronics 
Technology K.K. as shown in FIG. 6C. The side of the substrate opposite 
black layer 4, exposed with UV light and the substrate was developed in a 
predetermined solution. The self alignment exposure allowed unexposed 
black layer 4 to be removed from electrolessly plated nickel film 3, and 
exposed black layer 4 remained between the nickel films. Thereafter, 
substrate 1 was immersed in a concentrated nitric acid solution to 
dissolve and remove electrolessly plated nickel film 3 from ITO film 2 as 
shown in FIG. 6D. 
4. A set of red, green and blue pigment films 5 were formed on 
predetermined ITO electrode patterns 2 by an electrolytic method in 
accordance with the procedures of the invention, as shown in FIG. 6E. The 
electrolytic solutions for film formation of red, green and blue had the 
following compositions, respectively: 
______________________________________ 
Red: Ferrocenyl-PEG 2 mmol/l 
(produced by Dojin Kagaku) 
LiBr 0.1 mol/l 
Green: 
Ferrocenyl-PEG 2 mmol/l 
LiBr 0.1 mol/l 
Phthalocyanine Green (produced by BASF) 
10 g/l 
Blue: Ferrocenyl-PEG 2 mmol/l 
LiBr 0.1 mol/l 
Monochlorocopper phthalocyanine 
10 g/l 
(produced by Dainichi Seika) 
______________________________________ 
These electrolytic solutions were thoroughly dispersed by an ultrasonic 
homogenizer. A platinum plate was used as a counter electrode and a 
saturated calomel electrode was used as a reference electrode. The films 
were formed in the order of green, blue and red, but this order is 
arbitrary. In this way, a pigment film color filter having a black matrix 
was obtained. 
EXAMPLE 16 
A 4,000 .ANG. thick electrolessly plated nickel film was formed on an ITO 
electrode having a predetermined pattern as in Example 15. A 2 .mu.m thick 
photosetting gelatin layer was formed on the nickel film side of the 
substrate by spin coating. The side of the substrate opposite the gelatin 
layer was exposed to UV light and the substrate was developed in a 
predetermined solution. The self-alignment exposure allowed removal of the 
gelatin layer from the electrolessly plated nickel film, leaving the 
exposed gelatin layer between the ITO film pattern. The substrate was then 
immersed in a concentrated nitric acid solution to dissolve and remove the 
electrolessly plate nickel film from the ITO film. 
The gelatin layer remaining between the ITO electrode patterns was dyed 
with a black dye. Specifically, 10 g/liter of B181 produced by Nippon 
Kayaku Co., Ltd. was heated to 60.degree. C. and the substrate was 
immersed therein. Red, green and blue pigment films were selectively 
formed on portions of the ITO film pattern by the same process as in 
Example 15 to yield a multi-color filter having a black matrix background. 
EXAMPLE 17 
A 4,000 .ANG. thick electrolessly plated nickel film was formed on an ITO 
electrode having a predetermined pattern as in Example 15. A 2 .mu.m thick 
layer of photosetting resin containing a light-shielding material kneaded 
by two rollers, was formed on the nickel film side of the substrate by 
spin coating. The photosetting resin had the following composition: 
______________________________________ 
Denacole 100 g 
Benzophenone 2 g 
Titanium Black 20 g 
(produced by Mitsubishi Metal Corp.) 
______________________________________ 
After the side of the substrate opposite the photosetting resin layer was 
exposed with UV light, the substrate was developed in a predetermined 
solution. The self-alignment exposure allowed removal of the unexposed 
gelatin layer from the electrolessly plated nickel film, thereby leaving 
resin only between the ITO film pattern. The substrate was then immersed 
in a concentrated nitric acid solution to dissolve and remove the 
electrolessly plated nickel film from the ITO film. 
Red, green and blue pigment films were formed on predetermined patterns of 
the ITO film as in Example 15 to yield a multi-color filter having a black 
matrix background. 
EXAMPLE 18 
A transparent ITO electrode having a predetermined pattern was formed on a 
transparent substrate. Red, green and blue pigment films were formed on 
predetermined ITO electrode patterns. 
Electrolytic solutions for the film formation of the red, green and blue 
films had the following compositions and the following surfactant was 
used: 
______________________________________ 
Surfactant: 
##STR7## 
Red: Surfactant 2 mM 
LiBr 0.1 M 
Dianthraquinonyl Red 6 g/l 
(produced by Chiba Geigy) 
Green: Surfactant 2 mM 
LiBr 0.1 M 
Phthalocyanine Green 10 g/l 
(produced by BASF) 
Blue: Surfactant 2 mM 
LiBr 0.1 M 
Monochlorocopper phthalocyanine 
10 g/l 
(produced by Dainichi Seika) 
______________________________________ 
These electrolytic solutions were dispersed thoroughly for 1 hour by an 
ultrasonic homogenizer and the supernatant was collected after the 
dispersion stood for 10 hours. 
Electrolysis was carried out at a potential of +1.0 V (vs. S.C.E.) for 30 
minutes, using a platinum plate as a counter electrode and a S.C.E. as a 
reference electrode. Pigment films were obtained, each having a thickness 
of about 1 .mu.m. The films were formed in the order of green, blue and 
red but this order is arbitrary. 
A black ink layer was printed between the transparent electrode patterns on 
the substrate with the red, green and blue pigment films formed thereon by 
offset printing to form a light-shielding film. The black layer was 
printed with a TORAY waterless lithography plate (negative plate) and the 
ink layer was only formed between the transparent electrode patterns. The 
black ink contained a red pigment and a black pigment with a slight amount 
of carbon dispersed therein. 
EXAMPLE 19 
A black ink layer of the same pattern as in Example 18 was formed by offset 
printing on a counter electrode surface formed to oppose a color filter 
used for a liquid crystal display panel. The counter electrode substrate 
was pasted to the color filter provided with red, green and blue pigment 
films to form a liquid crystal panel having a constant cell gap. The black 
ink layer on the opposing substrate served as a light-shielding film. 
The substrates formed in Examples 15 to 19 were able to prevent lowering of 
contrast of the liquid crystal display due to light leaking from the gap 
between the red, green and blue pigment films. The resulting black-matrix 
color-filter liquid crystal panels exhibited superior qualities, compared 
to conventional panels. 
EXAMPLE 20 
FIGS. 7A, 7B, 7C and 7D are sectional views illustrating the steps for 
manufacturing an optical recording medium (ORM) in accordance with the 
invention. A 1.2 .mu.m thick optical recording disk substrate 1 was formed 
of polycarbonate by injection molding. To provide conductivity to the 
substrate, a 600 .ANG. thick ITO film 2 was formed on the surface of a 
plurality of disk substrate grooves by sputtering to form a conductive 
substrate 72. The inner and outer periphery of disk 1 was masked to 
prevent formation of ITO film 2 at those portions. 
Coated substrate 72 was immersed in a micelle electrolytic solution 
containing fine particles of an indolenine cyanine pigment surrounded by a 
surfactant, in a colloidal state. Electrolysis was carried out by applying 
a voltage between conductive layer 2 of substrate 72 as an anode and a 
stainless steel plate as a cathode to form an 800 .ANG. thick organic 
pigment film 3 on the surface of ITO layer 2 to form a coated substrate 73 
as shown in FIG. 7C. A double-sided optical disk 70 was completed by 
pasting two similarly prepared coated substrates 73 together, separated by 
a spacer 4. 
Pigment layer 3 was formed in accordance with the invention by using 
Ferrocenyl-PEG (produced by Dojin Kagaku) as the surfactant in the 
electrolytic solution. The composition of the electrolytic solution and 
the conditions for the electrolysis were as follows: 
______________________________________ 
Composition: 
Ferrocenyl-PEG 2 mM 
LiBr (supporting electrolyte) 
0.2 M 
Indolenine cyanine pigment 
7 mM 
Conditions for electrolysis: 
Potential 0.9 V 
Time 5 min. 
Temperature 25.degree. C. 
Stirring Gentle stirring 
______________________________________ 
EXAMPLE 21 
A second optical recording medium 74 was formed in accordance with the 
invention. The preparation of second ORM 74 is also explained with 
reference to FIGS. 7A through 7D. A 1.2 mm thick polycarbonate optical 
disk substrate 1 was produced by injection molding. An 800 .ANG. thick ITO 
(indium tin oxide) film 2 was formed on the surface of the grooves of 
substrates by sputtering to form a conductive substrate 72. The inner and 
outer periphery of substrate 1 was masked to prevent formation of ITO film 
2 at those positions. 
Conductive substrate 72 was immersed in an electrolytic solution containing 
fine particles of an indolinobenzopyran compound that were surrounded by a 
surfactant and were in a colloidal state. Electrolysis was carried out by 
applying a voltage between file 2 of substrate 72 as an anode and a 
stainless steel plate as a cathode to form a 1,000 .ANG. thick organic 
photochromic film 3 on the surface of conductive substrate 72 to form a 
coated substrate 73. 
A double-sided optical disk 74 was completed by pasting two coated optical 
disk substrates 73 together, separated by a spacer 4. 
Ferrocenyl-PEG (produced by Dojin Kagaku) was the surfactant in the 
electrolytic solution to form layer 3. The composition of the electrolytic 
solution and the conditions for electrolysis were as follows: 
______________________________________ 
Composition: 
Ferrocenyl-PEG 3 mM 
LiBr (supporting electrolyte) 
0.4 M 
Indolinobenzopyran pigment 
9 mM 
Spiropyran 
Conditions for electrolysis: 
Potential 1.0 V 
Time 7 min. 
Temperature 30.degree. C. 
Stirring Gentle stirring 
______________________________________ 
As shown in Examples 20 and 21, methods in accordance with the invention 
facilitate the formation of an organic pigment thin film on an optical 
disk substrate by a wet process which is accomplished with a simple 
apparatus and has high productivity. Thus, mass production of 
high-efficiency optical disks at a low cost is possible. 
EXAMPLE 22 
FIGS. 8A, 8B, 8C and 8D are sectional views illustrating the steps for 
manufacturing an optical recording medium (ORM) in accordance with another 
embodiment of the invention. 
An optical disk substrate 1 is a 1.2 mm thick glass substrate having 
grooves that were formed on the surface by plasma etching. To provide 
conductivity, a 700 .ANG. thick ITO (indium tin oxide) film 2 was formed 
on the surface of the grooves by sputtering to yield a conductive 
substrate 82. 
Substrate 82 was immersed in an electrolytic solution containing fine 
particles of tetrasodium tetraporphyrin (hereinafter referred to as 
"TSTP") and polymethyl methacrylate (hereinafter referred to as "PMMA") 
that were surrounded by a surfactant, oxidizable and reducible by 
electrolysis to be in a micellar colloidal state. Electrolysis was carried 
out by applying a voltage between conductive substrate 82 as an anode and 
a stainless steel plate as a cathode to deposit both TSTP and PMMA on 
conductive surface 2 of conductive optical disk substrate 82. A 1,000 
.ANG. thin film 3 of a compound having a photochemical hole burning 
(hereinafter referred to as "PHB") effect was deposited to yield a coated 
substrate 83. An optical recording medium 84 was completed by providing a 
protective coat 4 on coated surface 3 of coated substrate 83. 
Ferrocenyl-PEG (produced by Dojin Kagaku) was used as the surfactant in the 
electrolytic solution. The composition of the electrolytic solution and 
the conditions for electrolysis were as follows: 
______________________________________ 
Composition: 
Ferrocenyl-PEG 3 mM 
LiBr (supporting electrolyte) 
0.4 M 
TSTP 8 mM 
PMMA 10 mM 
Conditions for electrolysis: 
Potential 1.0 V 
Time 10 min. 
Temperature 28.degree. C. 
Stirring Vehement stirring 
______________________________________ 
As described above, the invention facilitates the formation of a thin film 
of a compound having a PHB effect on an optical disk substrate by a wet 
process. A thin film of a compound having a PHB effect which is formed in 
accordance with the invention can be formed uniformly on a disk substrate. 
Since the dispersion of the material having a PHB effect as a guest into a 
host (transparent solid medium) is homogeneous, the characteristics can be 
very stable. Since this method can be performed with a simple apparatus 
and can lead to high productivity, mass production of high-efficiency 
optical disks at a low cost is possible. 
EXAMPLE 23 
FIG. 9 shows the structure of a multi-film electrophotographic 
photosensitive drum 90 formed in accordance with an embodiment of the 
invention. In this embodiment a 30 mm diameter, 1.5 mm thick and 20 cm 
long aluminum cylinder 1 was used as a conductive support. The surface of 
cylinder 1 was plated with a 2 .mu.m thick layer of copper (Cu) 4. After 
copper layer 4 was mirror polished, an X-type phthalocyanine 
photosensitive layer 2 (carrier generating layer, hereinafter referred to 
as "CGL") was formed on copper layer 4 to a thickness of about 0.5 .mu.m. 
A 20 .mu.m thick carrier transporting layer 3 (hereinafter referred to as 
"CTL") of polyvinyl carbazole (hereinafter referred to as "PVK") was 
formed on CGL 2. 
Photoconductive drum 90 was produced as follows. Aluminum drum 1 was 
finished with a diamond turning method to have a surface roughness of 
0.002 .mu.m. The polished surface of drum 1 was plated with a 2 .mu.m 
thick layer of copper 4 and the surface was finished with a #6000 
polishing tape. Polished copper plated drum 1 was immersed in an 
electrolytic solution in which X-type phthalocyanine was solubilized and 
electrolysis was carried out between plated drum 1 and a counter electrode 
to form X-type phthalocyanine CGL thin film 2 on the surface of copper 
layer 4 of drum 1. X-type phthalocyanine is difficult to dissolve in a 
solvent. This material was solubilized by including a surfactant 
containing a metallocene group in the electrolytic solution. The surface 
of CGL 2 was coated with PVK which had been dissolved in a solvent by an 
isochronous pulling method to yield a CTL coating 3 which had a thickness 
of 20 .mu.m after drying. 
The electrophotographic characteristics of the thus-produced 
electrophotographic photoreceptor were measured by a dynamic system using 
an electrostatic copying paper testing device SP-428 (produced by 
Kawaguchi Denki Seisakusho) and a 780 nm buffer filter. In the testing 
experiment, the surface potential V.sub.a of the photosensitive layer of 
the photoreceptor which had been charged for 5 seconds at a voltage of -6 
K was measured. Light from a tungsten lamp was projected on the 
photosensitive layer and the illumination on the surface was 35 lux. The 
exposure (erg/cm.sup.2) necessary to attenuate the initial surface 
potential V.sub.a to one half its value was designated E.sub.1/2. The 
voltage after an exposure of 15 erg/cm.sup.2 was designated V.sub.b. 
The measurement was repeated 200 times, and the results of the first and 
200th measurements are shown in the following table. 
______________________________________ 
First 200th 
______________________________________ 
V.sub.a (v) -1250 -1280 
E1/2 erg/cm.sup.2 
3.5 3.6 
V.sub.b (v) 0 0 
______________________________________ 
It is evident from the above table that an electrophotographic 
photoreceptor formed in accordance with this embodiment of the invention 
has sufficient charge retaining force, high sensitivity, and small 
residual potential. In addition, these desireable characteristics are 
maintained even after repeated use. Accordingly, the invention can provide 
an electrophotographic photoreceptor having excellent characteristics. 
EXAMPLE 24 
An aluminum drum formed as in Example 23 was immersed in an electrolytic 
solution in which a bisazo pigment was solubilized. A bisazo pigment thin 
film, about 0.3 .mu.m thick, was formed on the surface of the aluminum 
drum as the photosensitive layer (CGL) as in Example 23. Triphenyl amine 
and polycarbonate were dissolved in 1,2-dichloroethane and the solution 
was applied to the CGL to form a CTL thereon, having a thickness of 20 
.mu.m after drying. 
The photosensitive efficiency of the resulting photoreceptor was evaluated 
as in Example 23. The results are shown in the following table. 
______________________________________ 
First 200th 
______________________________________ 
V.sub.a (v) -900 -890 
E1/2 erg/cm.sup.2 
3.8 3.9 
V.sub.b (v) 0 0 
______________________________________ 
It is evident from the above table that an electrophotographic 
photoreceptor formed in accordance with the invention has sufficient 
charge retaining force, high sensitivity, and small residual potential. In 
addition, these desireable characteristics are maintained even after 
repetitive use. Accordingly, the invention can provide an 
electrophotographic photoreceptor having excellent characteristics. 
EXAMPLE 25 
A 0.25 .mu.m thick perylene pigment CGL was formed by electrolysis as in 
Example 23. A PVK CTL, about 20 .mu.m thick, was formed thereon as in 
Example 23. The results from the resulting photoreceptor are shown in the 
following table. 
______________________________________ 
First 200th 
______________________________________ 
V.sub.a (v) -1100 -1150 
E1/2 erg/cm.sup.2 
3.7 3.9 
V.sub.b (v) 0 0 
______________________________________ 
It is clear from the above table that the electrophotographic photoreceptor 
formed in accordance with the invention has sufficient charge retaining 
force, high sensitivity, and small residual potential. In addition, these 
desireable characteristics are maintained even after repetitive use. The 
invention can provide an electrophotographic photoreceptor having 
excellent characteristics. 
In Examples 23 to 25, when the sensitivity was measured at an initial 
potential as low as 600 V, a sufficient value was obtained in each case. 
As described above, since a uniform high-density and high-purity CGL films 
are formed in process in accordance with the invention, it is possible to 
produce a photoreceptor having good characteristics. Furthermore, the 
invention enables high productivity and hence, production of a 
photoreceptor at a low cost. 
EXAMPLE 26 
FIGS. 11A, 11B and 11C show the processing steps involved in the 
manufacture of an active element 110 in accordance with the invention. A 
1,000 .ANG. thick conductive indium tin oxide (ITO) film 2 was formed on a 
glass substrate 1. A 1 .mu.m thick photosensitive epoxy acrylate film 3 
was formed on ITO film 2. Photosensitive epoxy acrylate is an insulating 
material and film 3 was formed by patterning. Other insulating materials 
which allow film formation by patterning in addition to epoxy acrylate may 
be substituted. Minute 15.times.15 .mu.m holes 6 where therein formed to 
expose portions of ITO film 2. Electrolysis was carried out in an 
elecrolytic solution in which metal-free phthalocyanine was dispersed in a 
colloidal state. ITO film 2 on glass substrate 1 was used as an anode and 
a platinum electrode was used as a cathode. 
______________________________________ 
Metal-free phthalocyanine 
5 g/l 
Surfactant charged by electrolysis: 
Ferrocenyl-PEG (produced by Dojin Kagaku) 
1 mM 
Supporting salt (LiBr) 0.05 M 
______________________________________ 
Metal-free phthalocyanine was dispersed in the electrolytic solution in a 
colloidal state by an ultrasonic homogenizer, and the supernatant was 
collected. 
Electrolysis was carried out at a constant voltage of +0.4 V (vs. S.C.E.) 
for 10 minutes, and a 3,000 .ANG. thick metal-free phthalocyanine film 4 
was formed at minute hole portions 6 (15.times.15 .mu.m) where ITO film 2 
was exposed, as shown in FIG. 11B. After film 4 was dried at 150.degree. 
C. for 15 minutes, a second 2,000 .ANG. thick ITO film 5 was formed on the 
phthalocyanine film by sputtering as shown in FIG. 11C. Thus, element 110 
having a thin-film structure of ITO--metal-free phthalocyanine--ITO was 
obtained. 
When a voltage was applied between ITO film 2 as a positive electrode and 
ITO film 5 as a negative electrode and the voltage is gradually raised, 
the nonlinear characteristic represented by a curve 1 in FIG. 12 were 
obtained. When positive electrode 2 and negative electrode 5 were reversed 
and a voltage was again applied and gradually raised, the nonlinear 
characteristics represented by a curve 2 in FIG. 12 were obtained. 
Nonlinear characteristic curve 2 was similar to nonlinear characteristic 
curve 1. Accordingly, this element exhibits almost the same nonlinear 
characteristic when the polarities of the applied voltage are reversed, 
showing that element 110 has a nearly symmetrical bi-directional nonlinear 
characteristic. 
EXAMPLE 27 
Metal-free octacyanophthalocyanine was used as an insulating material in 
forming an active element structure described in Example 26. Nearly the 
same bi-directional nonlinear characteristics as in Example 26 were 
obtained. 
As described above, a nonlinear switching element having the same nonlinear 
characteristics as a conventional MIM (Metal-Insulator-Metal) element can 
be obtained. However, the element can have a larger effective area which 
facilitates patterning and it is possible to obtain a chemically stable 
phthalocyanine film by a wet process. Thus, the electrochemical deposition 
not only contributes to enhancing the performance per cost, but also 
facilitates manufacture of a large-sized active matrix color liquid 
crystal panel such as those which will become more popular and widespread. 
It will thus be seen that the objects wet forth above, among those made 
apparent from the preceding description, are efficiently attained and, 
since certain changes may be made in carrying out the above method and in 
the articles set forth without departing from the spirit and scope of the 
invention, it is intended that all matter contained in the above 
description and shown in the accompanying drawings shall be interpreted as 
illustrative and not in a limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention herein described 
and all statements of the scope of the invention which, as a matter of 
language, might be said to fall therebetween. 
Particularly, it is to be understood that in said claims, ingredients or 
compounds recited in the singular are intended to include compatible 
mixtures of such ingredients wherever the sense permits.