JPS6381433A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide superior positive chargeability by forming a carrier transferring layer made of amorphous silicon carbide (a-SiC) contg. 0.1-10,000ppm group IIIa element of the periodic table and a carrier generating layer made of a-SiC contg. <=10,000ppm group IIIa element of the periodic table and by doping the layers with a specified relation. CONSTITUTION:At least a carrier transferring layer 5 and a carrier generating layer 3a are formed on an electrically conductive substrate 1. The layer 5 is made of a-SiC contg. 0.1-10,000ppm group IIIa element of the periodic table and the layer 3a is made of a-SiC contg. <=10,000ppm group IIIa element of the periodic table. The amount of the group IIIa element in the layer 3a is made smaller than that in the layer 5. In order to terminate the dangling bond of Si and C in the a-SiC of the carrier transferring layer 5, the a-SiC is doped with a halogen element and a prescribed amount of a group IIIa element of the periodic table is further incorporated. Thus, superior positive chargeability can be provided to the resulting sensitive body.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor that has a positive charging ability, maintains stable electrophotographic characteristics over a long period of time, and has excellent durability. be.

[Prior art and its problems]

2. Description of the Related Art In recent years, the development of ultra-high speed copying machines, laser beam printers, etc. has been actively progressing, and as a result, electrophotographic photosensitive drums installed in these devices are required to have stable operating characteristics and durability.

In response to this demand, hydrogenated amorphous silicon is attracting attention because of its excellent wear resistance, heat resistance, pollution-free property, and photosensitivity characteristics.

Such amorphous silicon (hereinafter abbreviated as a-3i)
As an electrophotographic photoreceptor, a laminated type photoreceptor as shown in FIG. 3 has been proposed.

That is, according to FIG. 3, an a-5i carrier injection blocking layer (2), an a-5
A photoconductive layer (3) and a surface protection layer (4) are sequentially laminated, and this carrier injection blocking layer (2) is used to prevent carrier injection from the substrate (1) and to reduce residual potential. A highly hard material is used for the surface protective layer (4) to increase the durability of the photoreceptor.

However, according to this a-si photoreceptor, the dark resistivity of the a-5i photoconductive N(3) itself is 101, Ω・cry
This increases the dark decay rate of this photoreceptor and makes it difficult to increase its own charging ability.As a result, when this photoreceptor is used for high-speed copying, the optical memory effect There is a problem in that the image remains without being completely cleared, and the previous image appears when the next image is formed (ghost phenomenon).

In order to solve this problem, a functionally separated photoreceptor as shown in FIG. 1 has been proposed.

That is, according to FIGS. 1 and 2, the basic structure is that a carrier transport N (5) and a carrier generation 1i (3a) are sequentially laminated on a conductive substrate (1), and if desired, a conductive substrate (1i) is laminated on a conductive substrate (1). Preventing carrier injection between the substrate (1) and the carrier transport layer (5) 7! (2a) or a surface protection layer N (4) is provided on the carrier generation layer (3a). The carrier transport layer (5) is formed of a material having high dark resistance and carrier mobility, thereby providing a high-performance photoreceptor with excellent surface potential and photosensitivity and low residual potential.

For this carrier transport layer (5), it is recommended to use hydrogenated amorphous silicon carbide, which has high resistance, wide bandgap, and semiconductor properties.
It has been proposed in Publication No. 192046 and the like.

On the other hand, when using electrophotography with a photoreceptor charged to a negative polarity, the surface of the photoreceptor deteriorates due to ozone generated by corona discharge, reducing the electrophotographic characteristics and providing stable images over a long period of time. Therefore, it is desired that the photoreceptor be charged to a positive polarity.

Therefore, in the prior art described above, the charging ability of positive polarity or negative polarity has not been sufficiently researched, and it is almost impossible to put it into practical use in terms of electrophotographic characteristics with positive charging ability.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a durable electrophotographic photoreceptor having excellent positive chargeability and electrophotographic properties, that is, excellent dark decay and light decay properties.

Another object of the present invention is to provide an electrophotographic photoreceptor suitable for use in laser printers and having spectral sensitivity to wavelengths in the near-infrared region.

[Means for solving problems]

That is, according to the present invention, in an electrophotographic photoreceptor in which at least a carrier transport layer and a carrier generation layer are formed on a conductive substrate, the carrier transport layer has a thickness of 0°1 to 10,000°C.
Provided is an electrophotographic photoreceptor that can be charged to a positive polarity and is made of amorphous silicon carbide containing an element of Group IIIa of the periodic table of ppfn.

Furthermore, according to the present invention, in the electrophotographic photoreceptor in which at least a carrier transport layer and a carrier generation layer are formed on a conductive substrate, the carrier transport layer has a thickness of 0.1 to 10.0.
Provided is an electrophotographic photoreceptor that can be charged to a positive polarity and is made of amorphous silicon carbide containing 00 ppm of Group IIIa elements of the periodic table, and the carrier generation layer is made of amorphous silicon carbide.

Further, according to the present invention, in the electrophotographic photoreceptor in which at least a carrier transport layer and a carrier generation layer are formed on a conductive substrate, the carrier transport layer has a thickness of 0.1 to 10. O
The amorphous silicon carbide containing Group IIIa elements of the periodic table of OOppm and the carrier generation layer are t
positive polarity, characterized in that the amount of the group IIIa element of the periodic table in the carrier generation layer is smaller than that in the carrier transport layer; An electrophotographic photoreceptor that can be charged is provided.

The present invention will be explained in detail below.

The electrophotographic photoreceptor of the present invention is a functionally separated laminated photoreceptor having the structure shown in FIGS. 1 and 2 as a basic structure.

According to the present invention, in the above structure, the carrier transport layer has amorphous silicon carbide (hereinafter abbreviated as a-5iC) as a main constituent element, and in order to terminate the dangling bonds of Si and C, for example, H or F , Cl1Brl1
Doping with halogen elements such as
By containing the Group Ia element within a predetermined range, it is possible to impart excellent positive charging ability as a photoreceptor.

That is, the carrier transport layer becomes a P-type semiconductor due to the addition of the group IV a element of the periodic table.

Taking the photoreceptor with the configuration shown in FIG. 1 as an example, its electrophotographic characteristics will be explained based on FIGS. 4(a) and (b).
Apply positive charging using charging means such as corona discharge (Figure 4 (
(See a)) When the 0th exposure is performed, the carrier generation layer (5)
Electrons and holes are generated at
The total charge of the exposed area becomes zero. (Figure 4(b)
reference).

As mentioned above, the carrier transport layer in the electrophotographic photoreceptor of the present invention basically consists of a-5tC,
Specifically, it is expressed by the following formula (1) % formula % (1) where 0.01≦X≦0.9, especially 0.05≦
By setting X≦0.5, the dark resistance can be set to 10” or more.

In addition, the Group IIIa elements of the periodic table to be added are 13
．． 711. Examples include Ga and 1m, and boron is particularly desirable. These are 0.1 to 10,000 in the carrier transport layer.
ppm, especially in an amount of 0.5 to 11000 ppm, and if the content is less than 0.1 ppm, the periodic table III
There is no effect of adding the group a element, and the photoreceptor becomes negatively charged.

The content of H and halogen elements for terminating the dangling bonds of a-SiC in the carrier transport layer is preferably in the range of 5 to 40 atoms χ, preferably 10 to 30 atoms χ in the total composition.

Furthermore, the thickness of this carrier transport layer is 1 to 100 μm,
Preferably, it is set within the range of 5 to 50 micrometers,
If it is less than 1 .mu.m, the charge retention ability will be poor and the ghost phenomenon will become noticeable, and if it exceeds 100 .mu.m, the image resolution will deteriorate and the residual potential will increase.

Layers other than the carrier transport layer in the photoreceptor of the present invention can be made of well-known photoconductive materials, and the carrier generation layer can be polyvinylcarbazole-based, phthalocyanine-based, perylene-based, azo-based, or polycyclic quinone-based. organic semiconductors such as Se, 5e-Te+ Se-A s lCd
S + Z n S + a −S i: H+ a
-S iG e : H* a An inorganic semiconductor such as -S IC can be used.

Further, the carrier injection blocking layer (2a) is a carrier transporting layer (
5) is provided to prevent carrier injection into, for example, organic materials such as polyimide resin, SiO2+S
10. A1z03+SIC+513Na+ In addition to amorphous carbon, a-5i or a-SiC contains hydrogen, fluorine,
It is formed using an inorganic material doped with oxygen or nitrogen to control the resistance value. When Si-based or SiC-based materials are used, carrier injection prevention can be further enhanced by adding a group IIIa element of the periodic table such as boron or a group Va element such as P within a range of 50 to 50 QOppm. .

In addition, in the electrophotographic photoreceptor of the present invention, since the carrier transport layer having the composition described above can obtain a sufficiently large dark resistance, it is not necessary to form this carrier injection blocking layer. According to experiments repeatedly conducted by the present inventors, the dark resistivity of the carrier transport layer is 10+
It has been confirmed that if the resistance is 3Ω·0m or more, it can be sufficiently put to practical use as an electrophotographic photoreceptor without forming a carrier injection blocking layer.

In addition, various materials can be used for the surface protective layer as long as they themselves have high insulating properties, high corrosion resistance, and high hardness characteristics, such as inorganic materials similar to those used for the carrier injection blocking layer described above. or organic materials can be used, thereby increasing the durability and environmental resistance of the photoreceptor.

The thickness of each layer other than the carrier transport layer is O, L to 10 μm for the carrier injection blocking layer, and 0.1 μm for the carrier generation layer.
It is desirable to set the thickness of the surface insulating layer to 0.1 to 10 μI.

With the above-described structure, the functionally separated electrophotographic photoreceptor of the present invention can advantageously make its surface positive polarized by corona discharge, and according to experiments conducted by the present inventors, a charging ability of +600V or more can be obtained. This makes it possible to provide a photoreceptor with no practical problems.

Next, the present inventors found that the positive charging ability could be further improved by selecting amorphous silicon carbide as a carrier generation layer compatible with the carrier transport layer having the composition described above.

The a-5iC used is represented by the following formula (2) % formula % (2) where 0.01≦Y≦0.9, especially 0.05
It is desirable that ≦Y≦0.5.

In producing this carrier generation layer, a-SiC is also used.
As mentioned above, it is necessary to use H or a halogen element to terminate the dangling bonds, and the content of these elements is within the range of 5 to 40 atoms χ, preferably 10 to 30 atoms χ in the total composition. All you have to do is make it look like this.

As mentioned above, the photoreceptor of the present invention described above has a light wavelength of 300 to 900 nm.
It has photosensitivity in the range of 0 ns, but according to the present invention, by adding an element of group 111a of the periodic table to the carrier generation layer made of a-SiC, the photosensitivity can be increased particularly in the near-infrared region. This makes it possible to use it as a photoreceptor for laser printers. The amount of group n [a group element of the periodic table in the carrier generation layer is 1
It can be blended in a range of 0.000 ppn+ or less, especially 11000 ppn+, but
It is important that the amount is small compared to the amount of group a elements added.

When the amount added to the carrier generation layer exceeds the amount added to the carrier transport layer, injection of excited carriers from the carrier generation layer to the carrier transport layer is inhibited, sensitivity decreases, and residual potential increases. This is because in the energy band between the carrier generation layer and carrier transport layer, the energy level of the carrier generation layer shifts to a higher energy side than that of the carrier transport layer, so when holes are injected into the carrier transport layer, there is an energy barrier at the interface. This is because it is formed.

The Group IIIa elements of the periodic table used are the same as in the carrier transport layer, B + A I + G a +
Examples include In and the like, with B being particularly preferred.

When producing the photoreceptor of the present invention, the inorganic photoreceptor can be produced by glow discharge decomposition method, ion blating method,
Thin film forming techniques such as reactive sputtering, vacuum evaporation, and CVO can be used.

For example, when forming the carrier transport layer as described above in the photoreceptor of the present invention, the glow discharge decomposition method is preferable, and the gaseous raw material used is 5t)14+51zH, Si.
, H, Si-based gases such as CH4, CJ4. Czlh,
You can use a C-based gas such as Ctlli or C3118 (
, 11□, IIe+Ne, Ar, etc. may be used as a carrier gas.

Periodic Table 1 [[As a gas containing group a elements, BZI16
．． BF3Al(C)la) i, Ga(CH3):
l+ In(CIIIa) 3. Ga(C113) 3
etc. According to experiments conducted by the present inventors, it has been found that an extremely high film forming rate (approximately 5 to 20 .mu.ts/h) can be obtained when C and H are used as the C-containing gas among the above-mentioned gases. Therefore, as preferable reactive gases for forming the carrier transport layer, at least CtHz gas, Si-containing gas, and gas containing 104 to 1 mole χ of Group IV a elements of the periodic table are selected. The specific composition of the reaction gas is (CJz
Gas: Si-containing gas) composition ratio is 0.05:1 to 3:1
It is desirable that

According to the present invention, a-SiC is used as a carrier generation layer for the purpose of further improving the positive charging ability, but even in the formation of this carrier generation layer, at least C21
1□ gas and a Si-containing gas are used in the same composition ratio as when forming the carrier transport layer, and this reaction gas is decomposed by glow discharge to form on the carrier transport layer.

Furthermore, according to the present invention, a-SiC containing Group IIIa elements of the periodic table is used as a carrier generation layer for the purpose of improving spectral sensitivity to near-infrared light.
In forming this carrier generation layer, as in the case of forming the carrier transport layer, gas, Si-containing gas, and gas containing elements of group IIIa of the periodic table were used for CZ)1, and
The gas containing the Group IIa element is blended in a ratio of 1 mol 2 or less, but for the reasons mentioned above, the proportion of the gas containing the Group Ia element of the periodic table in the reaction gas when forming the carrier generation layer is higher than that of the carrier transport layer. It is important that the amount is smaller than when it is formed.

When the photoreceptor of the present invention is provided with a carrier injection blocking layer or a surface protective layer as shown in FIG. 1 or 2,
When using SiC, a-Si:H, a-SiC1 amorphous carbon, or those doped with impurities as the material, it can be formed continuously using the same film-forming equipment, and the film-forming time can be reduced. It can be made significantly smaller.

In the layer structure of the photoreceptor of the present invention, when organic materials are used, they can be formed by well-known means. Specifically, polymer materials, organic pigments, organic dyes, etc. are mixed in a volatile solvent. It can be provided by a dipping method, a doctor blade method, or the like using a coating solution dissolved or dispersed in a liquid.

Next, a capacitively coupled glow discharge decomposition device used in an embodiment of the present invention will be explained with reference to FIG.

In addition, B is used as a gas containing Group IIIa elements of the periodic table.

An example will be given using H gas.

In the figure, 1st. Second. Third. 4th tank (6) (7)
(8) and (9) each have 5IHt+CJz+B
Ji+ (38 ppm BJa diluted in Hz gas) H2 gas is sealed, and H2 is also used as a carrier gas. These gases correspond to the first.
Second. Third. Fourth regulating valve (10) (11) (12)
(13) is released by opening the mass flow controller (14) (15) (16)
(17) and sent to the main pipe (18).

Note that (19) is a stop valve.

The gas flowing through the main pipe (18) passes through the reaction tube (2).
A capacitively coupled discharge electrode (21) is installed inside this reaction tube, and the power applied to this is 50-3KW, and the frequency is IMHz.
10MHz to 10MHz is suitable. Inside the reaction tube (20), there is a cylindrical conductive substrate for film formation (2) made of aluminum.
2) is placed on a sample holder (23), this holder (23) is rotated by a motor (24), and the substrate (22) is heated appropriately. It is uniformly heated by means to a temperature of about 50 to 400°C, preferably about 150 to 300°C. Furthermore, the reaction tube (
20) is in a high vacuum state (discharge voltage 0.1 to 2.0T) during the formation of a-Si 119 or a-SiC film, etc.
orr) is connected to the rotary pump (25) and the diffusion pump (26).

In the glow discharge decomposition device configured as above,
For example, a B-doped a-SiC film is used as a substrate (22
1.). Second. Open the 3rd and 4th regulating valves (10), (11), (12), and (13), and open the 1st. 2nd゜3rd. 4th tank (6) (7) (8
) From (9), SiH4 gas, Cdh gas, B
Ji gas and H8 gas are released, and the amount of these released is controlled by the mass flow controller (10) (11) (12) (1
3) into the reaction tube (20) via the main pipe (18), and then the reaction tube (20).
The interior is in a vacuum state of 0.1 to 2.0 Torr, the substrate temperature is 50 to 400°C, and high frequency power with a frequency of 1 to 10 MHz is applied to the capacitive discharge electrode (21) at a voltage of 50 to 3 V.
In conjunction with this application, a glow discharge occurs, the gas is decomposed, and a boron-containing a-SiC film is formed on the substrate at high speed.

〔Example〕

The present invention will be explained below using examples.

(Example 1) An aluminum drum for a substrate finished to a mirror finish using an ultra-precision lathe using a diamond cutting tool was cleaned by ultrasonic cleaning and steam cleaning using an organic solvent, and then by drying.
It was installed in the reaction tube (20) of the capacitively coupled glow discharge decomposition apparatus shown in FIG.

Then, from the first tank (6), SiH<gas was added to 1010
05e, CJz gas from the second tank (7) for 20 seconds
m, B, H, gas from the third tank (8) for 200 seconds
m, nz gas was released from the fourth tank (9) at a flow rate of 300 sec, the gas pressure was set to 0.4 Torr, the high frequency power was set to 200 W, and the substrate temperature was set to 300°C, and a- A carrier injection blocking layer made of StC:H:B:N:O was formed.

Furthermore, using the same apparatus, under the conditions shown in Table 1, a carrier transport layer (5) made of a-3iC doped with about 30 ppm of B, a carrier generation layer (3a) made of a-Si, and a carrier generation layer made of SiC are sequentially formed. A surface protective layer (4) was formed to obtain a photoreceptor having a thickness of 30 μm.

When the surface potential, dark decay, and light decay characteristics of the electrophotographic photoreceptor thus obtained were measured, the results shown in FIG. 6 were obtained. This is positively charged by a corona discharge of V to +5.6 in the dark, and the change in surface potential over time in the dark and 6.
The graph shows the change in surface potential over time immediately after irradiation with 50 nm monochromatic light (exposure dose: 0.3 μW'/cm). In the figure, A is a dark decay curve and B is a light decay curve.

As is clear from Figure 6, the surface potential after 2 seconds is approximately 750
V, which is high enough for practical use, and as a result of optical attenuation, the surface potential becomes smaller instantaneously than exposure, and the residual potential also becomes significantly smaller.

(Example 2) In this example, a laminate consisting of three layers from (Example 1) except for the carrier injection blocking layer was molded, and the charging ability in both positive and negative types was examined. Note that the film formation conditions and measurement conditions were the same as in (Example 1). The results are shown in FIGS. 7 and 8.

That is, Fig. 7 shows the case of charging with a +5.6 KV corona discharge, C is a dark decay curve, D is a light decay curve, and in contrast, -5.6 KV is shown in Fig. S.
In this case, E is a dark decay curve and F is a light decay curve.

As is clear from this result, according to positive charging, +65
The surface potential becomes large up to 0V, making it sufficiently practical, whereas with negative charging, a surface potential of only about -55ν can be obtained.

(Example 3) Next, in the same manner as in the first example, using each of the gases of 5iHn+Hz, Czlh, and B2H4, a carrier injection blocking layer consisting of a-St:B:N:O was formed at a flow rate not shown in Table 2. i
'7 (Oppm) A carrier transport layer (5) made of a-5iC doped with B, a carrier generation layer (3a) made of a-St, and a surface protection layer (4) made of SiC were formed to a thickness of 30 μm. A photoreceptor was obtained.

The obtained photoreceptor was charged with +5.6 KV corona discharge in the same manner as in Example 1), and the dark attenuation and light attenuation were measured.
The results shown in Figure 9 were obtained.

As is clear from FIG. 9, excellent positive chargeability was exhibited.

(Example 4) A carrier injection blocking layer consisting of a-Si:B:N:0 was prepared using 5iIIIa, Ht, CzHh and BzIIb gases in the same manner as in Example 1 at the flow rates shown in Table 3.
A carrier transport layer (5) made of a-SiC doped with about 30 ppm B, a carrier generation layer (3a) made of a-SiC doped with about 15 ppm B, and a Si
Form a surface protection Ji (4) consisting of C with a thickness of 30 μm.
A photoreceptor was obtained.

The obtained photoreceptor was charged by +5.6 KV corona discharge in the same manner as in Example 1), and the dark attenuation and light attenuation were measured, and the results shown in FIG. 10 were obtained.

In addition, when the spectral sensitivity of the photoreceptors manufactured in (Example 1), (Example 3), and (Example 4) was determined using light with a wavelength of 770 nn+, (Example 1) was 0.18 cm"/erg. (Example 3
) is 0.15cm2/erg, (Example 4) is 0.26c
A remarkable improvement in sensitivity was confirmed in the layer structure of m''/erg (Example 4).

〔Effect of the invention〕

As detailed above, the electrophotographic photoreceptor of the present invention has a carrier transport layer made of amorphous silicon carbide doped with an element of group IIIa of the periodic table, and a carrier generation layer made of amorphous silicon carbide or amorphous silicon carbide doped with a group IIIa element of the periodic table. By doping Group IIIa elements in a specific relationship, it exhibits practically excellent positive charging ability and electrophotographic properties, and also has excellent sensitivity in the near-infrared region, so it can be used for laser printers, etc. can also expand its applications.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the layer structure of a photoreceptor used in an embodiment of the present invention, FIG. 2 is a sectional view showing the layer structure of a photoreceptor used in another embodiment of the invention, and FIG. 4(a) and (b) are diagrams for explaining the electrophotographic characteristics of the electrophotographic photoreceptor of the present invention, and FIG. 5 is a cross-sectional view showing the general layer structure of the photoreceptor. Explanatory diagrams of the capacitively coupled glow discharge decomposition device used in the example, FIGS. 6 to 10 are diagrams showing the dark attenuation surface' line and the light attenuation curve,
FIG. 7, FIG. 9, and FIG. 10 show the photoreceptor of the present invention, and FIG. 8 shows a comparative example. 1...Substrate 2.2a...Carrier injection blocking layer 3.3a...Carrier generation layer 4...Surface protection layer 5...Carrier transport layer Patent applicant (663) Kyocera Corporation Takao Kawamura

Claims (3)

[Claims] (1) In an electrophotographic photoreceptor in which at least a carrier transport layer and a carrier generation layer are formed on a conductive substrate, the carrier transport layer is made of amorphous silicon carbide containing 0.1 to 10,000 ppm of Group IIIa elements of the periodic table. An electrophotographic photoreceptor that can be charged to positive polarity. (2) In an electrophotographic photoreceptor in which at least a carrier transport layer and a carrier generation layer are formed on a conductive substrate, the carrier transport layer is amorphous silicon carbide containing 0.1 to 10,000 ppm of Group IIIa elements of the periodic table. An electrophotographic photoreceptor capable of being positively charged, characterized in that the carrier generation layer is made of amorphous silicon carbide. (3) In an electrophotographic photoreceptor in which at least a carrier transport layer and a carrier generation layer are formed on a conductive substrate, the carrier transport layer is amorphous silicon carbide containing 0.1 to 10,000 ppm of Group IIIa elements of the periodic table. and the carrier generation layer is made of amorphous silicon carbide containing 10,000 ppm or less of a Group IIIa element of the periodic table, and the amount of the Group IIIa element of the periodic table in the carrier generation layer is smaller than that of the carrier transport layer. An electrophotographic photoreceptor that can be charged to positive polarity.