JPS62173474A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body which has high sensitivity to visible light, and is highly resistant to printing and environment at a low cost by specifying the dielectric constant of an electric charge transfer layer thereby decreasing the corona current in the stage of electrostatic charge. CONSTITUTION:The photoconductive layer which generates the carriers movable by excitation of light and the electric charge transfer layer essentially consisting of amorphous carbon are laminated and the dielectric constant of the charge transfer layer is specified to 3-6. The amorphous carbon layer having the dielectric constant as small as 3-6 has the high implantation efficiency of the electric charge from the photoconductive layer and about the same electrophotographic characteristics are obtd. with the film thickness of 1/2-1/3 the film thickness of the photosensitive body formed of only the a-Si:H film. Gases such as CH4, C2H4, C2H6, C2H2, C3H8, and C6H6 which are more inexpensive than gaseous SiH4 are usable as the gaseous raw material in the case of using a plasma CWD method for forming the film of the amorphous carbon and therefore, the cost of forming the photosensitive body is considerably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor used in electrophotographic copying machines, optical printers, and the like.

Conventional technology As a photoconductor in an electrophotographic photoreceptor,
Amorphous silicon containing tm% of hydrogen as a modifier that reduces the localized density of states (hereinafter referred to as -a-3i:H)
is attracting attention and being used because of its high photosensitivity, non-polluting properties, and high hardness.

However, there are still many problems to be solved in the electrophotographic photoreceptor composed of the above a-3i:H.

For example, the first problem is that a-3i:H has a dielectric constant of approximately 11, which is larger than that of organic photoconductor materials (hereinafter referred to as OPC) or Se.
approx. 3, Se: approx. 6) Since the capacitance is large, a very large charging current is required when charging the surface.

Furthermore, in order to obtain a practical surface potential (~400V), the surface charge density is high, and a large amount of original energy is required to remove this charge with light, so it cannot be said that the actual photosensitivity is sufficiently high. .

Furthermore, in the plasma CVD method using silane (denoted as 5IH4) gas as the raw material gas, which is most commonly used for forming a-3i:H films, the deposition rate is slow at 10 μm/H or less, and the silane/gas is expensive. Therefore, it is difficult to reduce manufacturing costs.

In addition, since the film is used with a film thickness of 30 μm or less, the practical surface potential is 50 V compared to 800 V for Se photoreceptors.
Since it is used at a low potential of 0V or less, there is a problem in that a copy with sufficient image density cannot be obtained using a normal two-component developer.

Problems to be Solved by the Invention As a means to solve the above-mentioned problems,
No. 3645 discloses a functionally separated photoreceptor using an organic semiconductor material, and Japanese Patent Application Laid-open No. 58-24355 discloses a functionally separated photoreceptor using an inorganic semiconductor material.

When using the former organic semiconductor material, it is expected that the charging potential will be improved due to a decrease in the dielectric constant, but since the organic semiconductor material has low hardness, the high hardness of the a-5i:H film makes it possible to use it as a long-life photoreceptor. Since it cannot be used effectively, it cannot be called an effective method.

In addition, in the latter case, a chalcogen material that easily becomes polycrystalline or a material such as SiC with a high dielectric constant is used, resulting in a decrease in temperature characteristics or an improvement in surface potential. A charge transfer layer containing as a main component is laminated, and the dielectric constant of the charge transfer layer is set to 3 to 6.

Function Amorphous carbon has a low dielectric constant, and a film with covalent bonds has high hardness. For this reason, for example, a-
In the case of a functionally separated photoreceptor using 3i:H as a photoconductive layer and an amorphous carbon layer as a charge transfer layer, the charging current during charging decreases due to the decrease in dielectric constant of the photoreceptor as a whole, and the surface Since the charge density is also reduced, photosensitivity can also be improved.

In addition, the amorphous carbon layer, which has a small dielectric constant of 3 to 6, has a high charge injection efficiency from the photoconductive layer, which is 1/2 to 1/2 that of a photoconductor formed only with a-3L:H film. Comparable electrophotographic properties can be obtained with a film thickness of 3.

Furthermore, when plasma CVD is used to form an amorphous carbon film, α4. C2H4, C2H6, C2H2, C3H8
Since gases such as °C6H6 can be used, the manufacturing cost of the photoreceptor can be significantly reduced.

Embodiment FIG. 1 schematically shows a cross section of an embodiment of the most basic electrophotographic photoreceptor according to the present invention.

The electrophotographic photoreceptor shown in FIG. 1 has at least hydrogen or halogen atoms (
Amorphous carbon containing X) (hereinafter referred to as a-C(:H:X
). However, X=F.

It has a charge transfer layer 2 made of C1, Br or 10) and a photoconductive layer 3 containing silicon, said photoconductive layer 3 having a free surface 4 on the one hand.

In the present invention, photoconductive layers containing silicon include a-3t (:H:X), a-3i1-yC, (:H:
X) (0<y<1), a-3t1-, Oa(:H:X
)(0<7<1), a-3t, -, N, (: H:
X) (0(7(1), a-3t1-2Go2
(:H:X) (0<Z<1), a-(S 11-z
Ge z ) 1-yNy(:H:X)(o<y, z<
1), , ,a-(Stl-2Go2
)1-. 0. (:H:X)(0(y, z(1), or a
−(S il,, zGe z ) 1++ , c y
It consists of a single layer of (: H:

The thickness of the charge transfer layer at this time is 5 to 60 μm.

The thickness of the photoconductive layer is preferably 10 to 25 μm and 0.6 μm.
~10 μm, preferably 1 to 5 μm.

In the present invention, in order to further improve the electrophotographic characteristics, in FIG. 1, between the support 1 and the charge transfer layer 2,
A barrier layer may be provided to effectively prevent carriers from being injected from the support 1 into the charge transfer layer 2.

The material for forming the barrier layer is Al2O3, Bad.

Bad2. Bed, Bi2O3, CaO1CeO2
, Ce2O3, La2O3°Dy2Q3. Lu2O3,
Cr2O3, Cuo, Cu2O, Fe01Pbo.

MgO, SrO, Ta2O3, The2. ZrO2,
HfO2, TiO2, TiO.

Metal oxides such as SiC2, GeO2, Sio, GeO,
Or TiN, AIN, SuN, NbN, TaN, Ga
Metal nitrides such as N, or WC, S n C, Ti
Metal carbides such as C, or stc, SiN, GeC,
Insulators such as GeN, BC, BN.

Polyethylene, polycarbonate, polyurethane.

Organic compounds such as polyhalaxylene are used.

In addition, in order to improve cleaning performance, abrasion resistance, or corona resistance, in Figures 1 and 2,
A surface coating layer is formed on the free surface 4. Suitable materials for the surface coating layer include 5ixQ1-x and 5iXC1-
E, 5ixN1-E, Ge! o1-e, GexCl-e.

GexNl-x, B, N1-, , B, C1-x, Al,
N1-, (0<!<1).

and inorganic materials such as layers containing hydrogen, polycarbonate, polypropylene, polyvinyl chloride, polyvinyl alcohol, polystyrene, polyamide, polytetrafluoroethylene, polytrifluorochloroethylene , polyvinylidene fluoride, polyurethane, and other synthetic resins.

To create a-C(:H:X), CH4tC2H6,C
3H6゜C4H1゜, C2H4, C3H6, C4H8,
Hydrocarbons such as C2H2, C3H4°C4H6, C6H6, CH3F, CH3Cl.

Allyl halides such as CH3I, C2H6C1, C2H3Bx, CClF3. CF4. CHF3. C2F6.
Freon gas such as C3F8, C6H6-mFm (m=1~
6) Plasma CVD method using C atom raw material gas such as benzene fluoride, or Ar, F2.6) using graphite as a target. F2. Reactive sputtering in C12, C2H4, C2H2 is used. At this time, the dielectric constant changes depending on the discharge conditions, from a film with strong covalent bonds to a polymer film, and its value changes greatly. Dielectric constant 3~
6, the film must be formed to contain 10 to 6 atoms of hydrogen.

a-3L (:H
:X).

a-3t1-aCa(: )i:xX O<3'<
' ) e a-8i1-vOy(:H:X)(0<
y<1) or a-3z 1-yNy (: H:
To create X) (0<y<1), 5tH4,S=
2H6, S rice-,.

5tF4, 5tC14, 5tHF3. SiH2F2. S
iH3F.

Si such as 5IHC13, 5iH2C12, 5iH3C1
Ar and F2 (and F2
A reactive sputtering method in a mixed gas (or C12 may be mixed) is used. Also a-3i, -aCa(:
H:X) (0<y<1), a-8i1-AOy(:H
:x) (o<y+), a-3i1-, N, (:H:
X) (○<y<1) Hydrocarbons such as C4H3 and C6H6, CH3F, CH3Cl.

/%0 of CH3I, C2H5C1, C2H3Bx, etc.
Genated Asialyl ClF3. CF4. CHF3. C2F
6. Fluogas such as C3F8, C6H6-mF (m-1
The raw material gas of C atoms such as benzene fluoride in ~6) is mixed with the silicon raw material gas used in the plasma CVD method, or mixed with a sputtering gas such as Ar in the reactive sputtering method. In addition, as oxygen sources, C2, CQ, C
O2゜No, No2, etc., and N2 as a nitrogen source. N
Use a mixture of H3°No, etc.

Also, when adding Go to a-3L(:H:X),
GeHGe HGe HGeF GeCl4. GeH
F3゜4e 269 3B' 4j
GeH2F2. GeH3F, GeHCl3. GeH2C
It can also be formed by a plasma CVD method by mixing a gas such as 12°G e H3C1 with the source gas of the S1 atoms.

Furthermore, in the present invention, the above a-3i(:H:X)
.

a-3i C(:H:X)(0(y(1), a-
S 11-yOy-F7 (:H:X) (0<y<1), a-311-, Ny(
:H:X)((y<1), or a film with Ge added thereto, or a-C(:H:X) film by adding impurities to control the conductivity and obtain the desired property. Electrophotographic properties can be obtained.In particular, a
The carrier transport characteristics of -C(:H:X) greatly change due to the addition of this impurity. Examples of p-type impurities that provide p-type conductivity include B and Al, which belong to Group Ⅰ of the periodic table.
, Ga, In, etc., preferably B, Al.

Ga is used, and the n-type impurities that provide n-type conductivity include Group II b of the periodic table [belonging to N, P, and As.

sb, etc., and P and As are preferably used.

In addition, as a method of adding these impurities, (C2H
6) 3Ga, InCl3. (C2H5)3In, n-type T [material] tJJ, N2. NH3, No, N20. No
2. PH3゜P2H4, PH41, PF3. PF5. P
Cl3. PCl3. PBr3゜PBr3. Pi3. As
H3, AgF2. AsCl3. AsBr3゜SbHSb
F SBF 5bCI 5bCL5 etc. 3+
In the plasma CVD method, 3=5' 31 gases or gases obtained by diluting these gases with H2, Ha, and Ax are used as the raw material gases such as the above-mentioned C atoms and SL atoms used during the formation of each film. They may be used in combination, and in the reactive sputtering method, they may be used in combination with Ar, H2, or F2°C12. Examples will be described below.

Example 1 A mirror-polished aluminum substrate was placed in a parallel plate type capacitively coupled plasma CVD apparatus having a 6-inch discharge electrode, and after evacuating the inside of the reaction vessel to 5×1Q-6 Torr or less, the substrate was heated to a temperature of 150 to 300 Torr. °C2 suitably 200-25
Heated to 0°C. C2H4 for 10-80 sec
, B2H6 diluted with He at a concentration of 1% for 0.5-20 s
Introduced into the Cam device, and the pressure inside the reaction vessel was set to 0.1 to 0.
．． Adjusted to 8 Torr. A boron-doped aC:H layer with a thickness of 25 μm was formed as a charge transport layer using a high frequency power of 80 to 150 W at 13 and 56 MHz, and then SiH4 was introduced at 10 to 4 oscCm, and the pressure was set to 0.2 to 0.
2-1, OTorr, high frequency power of 60 to 160 W, 5i1-, Cx:H(0(x(1)) was formed as a surface covering layer to a thickness of 0.08 to 0.3 μm to prepare an electrophotographic photoreceptor.

The dielectric constant of the aC:H layer at this time was 3.6 to 5, which was a small value. Furthermore, when this electrophotographic photoreceptor was corona charged at 3KV, a surface potential of +3000V was obtained, and when exposed to white light, a residual potential of +30V was obtained.
At V or less, the half-potential exposure amount was 11 ux m sea or less, and very high sensitivity was obtained. In addition, this photoconductor is +5o
When charged to ov and similarly exposed to white light, the half-potential exposure amount was 0.31 ux * sea or less, and the sensitivity was very high. This is the conventional 20p consisting of a-3t:H.
Compared to the case where the photoreceptor of M is charged to +400V and exposed to white light, the sensitivity is 2 times higher, and when exposure was performed again only to visible light and compared, it was confirmed that the sensitivity was more than 2.5 times higher. . Also, when charged at the same corona potential, a-8t
: Compared to H only, the charging potential was three times or more, indicating that a highly sensitive photoreceptor could be obtained with a small charging current.

This is because the B-added aC:H layer with a dielectric constant of 3.5 to 5 functions as a charge transfer layer for holes and reduces the dielectric constant of the electrophotographic photoreceptor.

Also, when 200 to 3000 ppm of oxygen is added to a 0.2-2 pm a-3i:Hfi conductive layer, B is added to 0.2-2 pm.
Even when 6 to 5 ppm of the compound was added, an electrophotographic photoreceptor exhibiting characteristics similar to those described above could be formed.

Also, by mixing 1% CF4 with C2H4, a-C(:H:X
) When a film was formed, the dielectric constant was 3 to 4.5, and the same characteristics as above were obtained.

Example 2 A mirror-polished aluminum drum was placed in a capacitively coupled plasma CVD apparatus having a cylindrical discharge electrode with a length of 450 mm and an inner diameter of 16 ffiφ, and the interior of the reaction vessel was
After evacuation to below 10-6 Torr, the aluminum drum is heated to 150~a o o'C, preferably 200~250''C.
heated to. S L H4 for 50-150 sec.

H2 diluted 4001)I)mnoB2)16 from 5Q~
Introduced for 150sec, pressure 0.2~1, OTorr
, a p-type A-3T:H layer was formed as a barrier layer at a thickness of 0.3-1.5 pm with a high frequency power of 100-250 W, and then S I H4 was applied at a power of 60-150 sec and a pressure of 0.2-1.5 pm.
1. ○ To r r , a non-doped a-3t:H layer with a thickness of 1 to 5 μm is formed using high-frequency power of 100 to 250 W, and in addition to S t H4, 20 to 5011 cc of C2H2 is formed.
m was introduced to form a-Si□-xc layer of 0.5 to 1 μm. Next, S x H4 was blocked and c2H2 alone was formed to a thickness of 5 to 10 μm to form an electrophotographic photoreceptor.

The dielectric constant of the a-C:H layer at this time was 4 to 6. This photoreceptor was installed in a former printer using a 670 nm LED as a light source, and clear printing was achieved with a surface potential of +500 to 800 V when positively charged. confirmed. In addition, a-3i which is a photoconductive layer
:H layer instead of a-3i (:H:F), a-8114
a-S t 1-ρ1 layer instead of Cx layer.

An electrophotographic photoreceptor having characteristics similar to those described above could also be formed using the a-S t 1-EN layer.

Also, a-3i:H or a-3i(:H:F) has G
a-3i1-, Ge2: H, a-3iG with addition of e
e:H.

a-3t, -zGez(: H: X) (0(z(
Using method 1) further improved the sensitivity.

Example 3 The electrophotographic photoreceptor produced in Example 2 was coated with a-Ge 1-, Cx with a thickness of 0.1 to 0.5 μm as a surface coating layer.
When H (○<x<1) was formed using the plasma CVD method and mounted on the optical printer used in Example 2, the electrophotographic photoreceptor with this configuration had excellent heat resistance and moisture resistance, and was able to withstand 800,000 sheets. It was confirmed that the printability was good.

Example 4 A polycarbonate resin was uniformly applied as a surface coating layer to the electrophotographic photoreceptor produced in Example 2 so that the film thickness after drying was 1 μm to obtain an electrophotographic photoreceptor. When installed in the optical printer used in Example 2, it was confirmed that the electrophotographic photoreceptor with this configuration had excellent moisture resistance and a printing life of 50,000 sheets or more.

Example 6 Plasma C of Example 1 was applied onto a substrate on which MO was vapor-deposited.
VD method Niyori, a-C:H layer containing 500 to 100 atomic ppm of P, 6 μm thick, 0.6 to 50 atomic ppm of P
An electrophotographic photoreceptor was prepared by sequentially laminating an a-3i:H layer with a thickness of 0.5 to 2 pm and a 5i1-xNx:H layer with a thickness of 0.1 to 0.2 μm. Take this photoreceptor. ○K
When corona charging was carried out with V, a surface potential of -800V was obtained, and the sensitivity was high with a half-reduced potential exposure of 0.7 lux*sea to white light, and the residual potential was less than -13V. In this case, the P-doped aC:H layer functions as an electron charge transfer layer.

Example 6 A glass substrate on which aluminum was vapor-deposited was placed in a 6-inch target MAGUTRON SNOKUTSU device, and the substrate temperature was set at 150 to 300'C. ~20m Torr.

02 to 10 to 40 m Torr, high frequency power 100
0.1-0.5pm of Dy2O3 layer under ~3oOW condition
then target graphite and 1 Ar
A C:H layer having a thickness of 5 μm was formed under conditions of ~10 mTorr, H2 of 9 to 90 mTorr, and high frequency power of 100 to 600 W.

The dielectric constant at this time was 4.5 to 6. Next, targeting polycrystalline 7 recon, Ar was applied at 5 to 10 m To
r r , H2 was introduced at 0.3 to 4 mTorr, and a-3t, which is a photoconductive layer, was formed at high frequency power of 200 to 800 W:
H was formed to a thickness of 0.5 to 2 μm, and then H2 was changed to N2 and a″'511-xNx was polished to a surface coating layer of 0.08 to 0.2 μm. This photoreceptor was coated with -e+, oKV corona. Through charging treatment, the surface potential is charged to -650■, and when exposed to white light, the potential is halved with an exposure amount of 1.2 lux @ sea
f Confirmed. 1 on aluminum support 1, C2
Optical bandgap width 1 was determined by plasma CVD using H2.
．． Non-doped MeC with 8-2.1eV and dielectric constant 3-6:
Form a 10 to 15 μm thick H layer, then S i H4 and S
a-3i as a photoconductive layer using a mixed gas of IF4.
:H:F layer was formed with a thickness of 1 to 3 μm.

Next, SiF4 was switched to N2 and a
−3il, −, N, (0<X<1) by 0.08,
A 2 μm thick film was formed to obtain an electrophotographic photoreceptor.

This photoreceptor was charged with a corona voltage of -s, o KV. A high surface potential of -1300V can be obtained, and the potential exposure amount is 0.5 lux・S when the potential is halved by white light.
eC and high sensitivity were demonstrated. This confirms that the non-doped C:H layer with a dielectric constant of 3 to 5 functions as an efficient charge transfer layer for electrons in the above range.

In addition, a -Ge, -xCx: H(
The photoreceptor in which o(x<1) is formed in a thickness of 0.1 to 0.5 μm is particularly excellent in reproducing one charge repeatedly and exhibits the same characteristics as above. Effects of the Invention The electrophotographic photoreceptor according to the present invention has an amorphous By laminating the charge transfer layer, which is mainly composed of carbon and has a dielectric constant of 3 to 6, and the optical four-layer, the corona current during charging is small.
It is highly sensitive to visible light, is low cost, and has excellent printing durability and environmental resistance (heat resistance, moisture resistance, etc.).

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are sectional views of an electrophotographic photoreceptor in an example of the present invention, respectively. 1...Support, 2...Charge transfer layer, 3
...Photoconductive layer, 4...Free surface. Name of agent: Patent attorney Toshio Nakao and 1 other person7-
11 branch special object Z -m-charge transport 1 3-1 Nikobu tW 4- own surface Fig. 1 Fig. 2

Claims (6)

[Claims] (1) In an electrophotographic photoreceptor in which a photoconductive layer that generates movable carriers by photoexcitation and a charge transfer layer mainly composed of amorphous carbon are laminated, the charge transfer layer has a dielectric constant of 3 to 6. An electrophotographic photoreceptor. (2) The electrophotographic photoreceptor according to claim 1, wherein the amorphous carbon layer contains at least hydrogen or a halogen element. (3) The electrophotographic photoreceptor according to claim 1, wherein the photoconductive layer is an amorphous layer containing a modifier that reduces the localized density of states. (4) The electrophotographic photoreceptor according to claim 3, wherein the photoconductive layer contains at least either hydrogen or a halogen element. (5) The electrophotographic photoreceptor according to claim 1, wherein the amorphous carbon layer contains an element of Group III B or Group V of the periodic table. (6) The electrophotographic photoreceptor according to claim 1, wherein a surface coating layer is formed on the free surface.