JPS62113155A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an a-Si type electrophotographic sensitive body superior in durability, printing resistance, and humidity resistance by coating the surface of an electrophotographic sensitive body having the a-Si type photosensitive layer with an a-C(H) film having an ESR spin density of 10<18>-10<19>cm<-3>. CONSTITUTION:The electrophotographic sensitive body is provided on a conductive substrate with an amorphous silicon (a-Si) type material, and further on this layer with the surface layer composed of amorphous carbon hydride {a-C(H)} having an electronic spin resonance density (ESR spin density) of 10<18>-10<19>cm<-3>. The photosensitive body is obtained by laminating on the conductive substrate 1, such as a stainless or aluminum plate, a blocking layer 2, the a-Si type photoconductive layer 3, a buffer layer 4, and the surface layer 5 made of a-C(H) or a-C(O, H), and the conductive substrate 1 may be of either cylindrical form or sheet, and a substrate prepared by subjecting the surface of a glass or resin plate to a treatment for giving electric conductivity may be used. The blocking layer 2 is used in order to block injection of electrostatic charge from the conductive substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electrophotographic photoreceptor using amorphous silicon as a photoconductive material.

[Prior art and its problems]

Conventionally, amorphous Se,
Alternatively, a photoreceptor made of amorphous Se doped with impurities such as As, Te, and Sb and used as a light-bending material, or a photoconductive material such as ZnO or CdS dispersed in a binder is used. Photoreceptors, etc. are used.However, these photoreceptors are heat resistant,
There are problems in terms of environmental pollution and mechanical strength.

In recent years, amorphous silicon (a
A technique has been proposed to solve the drawbacks of these conventional photoreceptors by using -Si). 100. In addition, the photoconductor (() is so small that it is not desirable as a light guide material for a photoreceptor (electrophotograph).

In this twisted a-8i, a so-called dangling bond is generated in which the 5i-8i bond is broken, and many localized levels exist within the energy gap due to this defect. For this reason, hopping conduction of thermally excited carriers occurs and the dark specific resistance becomes small, and the optically assisted carriers are guided to localized levels, resulting in poor light guiding.

On the other hand, in hydrogenated amorphous silicon (a-St (H)) produced by photochemical CVD using silane gas (S iH4) for one minute, the above defects are replaced by hydrogen atoms (Fi41L, The number of dangling bonds can be greatly reduced by using SiK H as a metallurgy, which improves the photoconductivity and improves p and 11.
The valence electron control of rjli has also become OT, but the dark specific resistance value is at most 10 to 10 Ω·m, which is still low compared to the dark specific resistance l1iiK of 10 Ω·m or more, which is sufficient for an electrophotographic photoreceptor. A photoreceptor made of this a-5i (H) has a high dark decay rate of surface potential and a low initial charge potential.

Therefore, in order to impart caustic retention ability to this a-8t(H), we doped an appropriate amount of 111Usong to increase its dark resistivity to over 100%, and applied it to the sperm process using the Carlnon method. A by making it possible.

Although a photoconductor with such a-Si (H) surface can produce good images initially, when evaluating manga that has been stored in the atmosphere or high humidity for a long period of time, Often picture 1'J! It has been found that defects occur. It is also known that as the copying process is repeated many times, image 1ψ blurring gradually occurs. Such a deteriorated photoreceptor is likely to cause image 11 blurring, especially in high humidity environments, and as the number of copies increases, image 11! It has been confirmed that there is an i1 direction in which the critical humidity at which blurring begins to gradually decrease.

As mentioned above, photoreceptors with a-5i(H) surfaces are exposed to chemical species (ozone, nitrogen oxides, etc.) that are generated due to long-term exposure to the atmosphere or moisture, or due to corona loss during the copying process.

It is believed that the outermost surface of the photoreceptor is susceptible to exposure to nascent oxygen (e.g., nascent oxygen) and that some kind of chemical deterioration causes image defects, but the mechanism of this deterioration has not yet been fully investigated. Not done. In order to prevent the occurrence of such image defects and improve printing durability, the surface of the a-8t(H) photoreceptor is coated with a coating. Attempts have been made to provide chemical stabilization by providing i1-.

For example, hydrogenated amorphous silica carbide as the surface layer m layer:
+7 (a −Sir Ct−x(H) + 0<X<
1) or hydrogenated amorphous silicon nitride (a
-8ixNl-x (H), 0 < X < 1
) has been proposed to prevent deterioration of the photoreceptor surface 1- due to the copying process or environmental atmosphere (7% Patent Publication No. 115559/1983). but,
If the carbon concentration or nitrogen 41f in the surface protective layer is selected to an optimal value, printing durability can be considerably improved, but it is not possible to maintain humidity resistance in a high humidity atmosphere (RE (80 koto or higher)). However, after undergoing the copying process for tens of thousands of copies, spitting and blurring occur at relative humidity levels of 60%, and even if these surface protective layers are applied, printing durability II and flit humidity cannot be significantly improved. It is in.

[Purpose of the invention]

The purpose of the present invention is to prevent deterioration even during long-term storage and repeated use, and to be able to withstand even high humidity atmosphere.
The photoreceptor's properties are always stable, with almost no deterioration in properties such as image defects observed, and its durability is almost unrestricted by the environment in which it is used.

It is an object of the present invention to provide an a-8i photoreceptor having excellent printing durability and moisture resistance and desirable electrical characteristics.

[Key points of the invention]

According to the present invention, in an electrophotographic photoreceptor having a light guide Kli made of an amorphous silicon (a-8i) based material on a conductive base, and further surrounded by a surface layer,
One of the above objects is achieved by the surface layer being made of carbon with a spin concentration due to electron spin resonance absorption (hereinafter also referred to as ESR spin at).

Hydrogenated amorphous carbon (a carbon layer dangling bond is stabilized by hydrogen and is represented by a-C(H) n
Rather, even if some of it contains crystalline parts, the proportion is low. Hydrogen combines with carbon and has an infrared absorption spectrum of at least 2900 m.
Absorption exists on one side.

In addition to hydrogen, it is also effective to use fluorine, oxygen, and nitrogen as a means of stabilizing carbon dangling bonds.

The a-8t-based light guide IL layer is made of hydrogenated amorphous silicon (a-5i(H)), 7kJ
Chemical 42 amorphous silicon (a -5i (F, H
) ), hydrogen f'r:, amorphous silicon carbide (a -Sit -x Cz(H) (0<X(1
), hydrogenated fluorine ratio amorphous disaster reaction (a −
Si1-x Cx(F,H)) (0<X<1), hydrogenated amorphous silicon nitride (a-St Nx(H)
) (0<X<4/3), hydrogenated fluorinated amorphous silicon oxide (a-SiOx (F,H))
This is a layer using at least one of (0<X<2) or a layer doped with impurities.

[Embodiments of the invention]

FIG. 1 shows the structure of an embodiment of a photoreceptor according to the present invention,
Blocking 112. is placed on the conductive substrate 1 made of Al or stainless steel. a-8i system light guide It/13.
Buffer 44. a-C(H) or ld a-C(0
, H) are laminated. The conductive substrate 1 may be either cylindrical or sheet-like, and may be made of glass or resin that has been specially treated.

The purpose of blocking 1 #4 is to prevent charge injection from conductive substrate 1. In terms of material, Al2O3,
AIN, SiO, 5in2. a-5fi-x
Cx(F,H).

a-8iNx(H) l &-C(H) I a-C(
F) l Iff period table ■ group, ■ Doping with mourning element A a-C(H), a-C(F), a-5
i(H) Use fx and J'f[*le.

Buffer I11 is for alleviating material heterogeneity between the leading layer and the surface layer, and is made of a-Siz material.
-x Cz(H), a -Si1-x Cz(F,
H), a-5tNx(H, a-5iOz(H)
, a-Stow(F,H), etc. can be used.

For example, it costs $2 to manufacture a photoreceptor having the structure shown in FIG.
1fflK - An amorphous film generating apparatus as shown in the example is used, in which a holding part 12 of the substrate 1 and an electrode 13 facing it are arranged inside a vacuum chamber 11, and holding part 12. 'The polarization 13 is equipped with heaters 14 and 15, respectively. After degreasing and cleaning with trichlorethylene, the fcAl cylindrical substrate 1 is fixed to the holding part 12, and the pressure inside the vacuum chamber 11 is reduced to 10
The exhaust is evacuated via the exhaust pulp 17 by the exhaust pump 16 so that the pressure becomes Torr. The base 1 and the electrode 13 are heated by the heaters 14 and 15 to a predetermined temperature. The holding portion 12 and the conductive substrate 1 are rotated to achieve uniformity of the film in the circumferential direction.

Next, the pulp 18 of the gas pressure vessel row 21 necessary for film formation is opened from among the raw material gas pressure vessels 21 to 25, passed through the flow rate controller 19, the stop pulp 20 is opened, and the pulp 18 is placed in the vacuum chamber 11. supply The same applies to other gases.

Next, the pressure inside the tank is set to a predetermined pressure, for example, 0.001 to 5.
Torr, after adjusting the frequency (13,56 MHz) from the radio frequency (RF) power #31, it is supplied to the opposing KtIi 13 through the insulating material 32i, and a glow discharge is generated between the 13 and the base 1. Do membrane.

Hereinafter, specific examples will be described.

Example 1 An AI cylindrical body 1 that had been degreased and cleaned with trichlorethylene was attached to the holding part 12 in the vacancy tank 11 of the apparatus shown in FIG. 2, and a blocking 'd 2 with a thickness of 0.2 μm was formed under the following conditions. did.

5iH4 (100%) flow = jt 250ee/min B2
H6 (5000ppM, H2 pace) flow rate 20cc
/min Gas pressure: 0.5 Torr RF power: 50 W Substrate temperature: 200°C Film forming time: 10 minutes On top of this, photoconductivity was applied under the following conditions using SiH4 and B2H6 as the ftK source gases in the same apparatus shown in Figure 2. 1-3 was formed to a thickness of 25 μm.

5iH4 (100X) flow rate 200cc 7 minutes B2H6
(20 ppM, H2 pace) Flow t 10 cc/min Gas pressure 1-2 Torr RF power 300 W Substrate temperature 200 C Film forming time 3 hours On top of this, 5IH4+ CH4+ as source gas
Pants 7114 were formed using B2H6 to a thickness of 0.1 μm.

5iHd100%) flow rate 100ee/min CH4 (10
0X) Flow rate gQcc/min B2H6 (2000ppM
, H2 pace) Flow rate 15cc/min Gas pressure
1.0 Torr RF power 200 W Substrate temperature 200° C. Film forming time 2 minutes Finally, an a-C(H) surface layer 5 was formed thereon to a thickness of 0.1 μm under the following conditions.

C3H11 (100%)fi view 20cc/min gas pressure
0. I TorrRF direct force 200
W Substrate temperature: 90 to 110° C. Film forming time: 5 minutes Substrate @ Change was measured using an infrared thermometer and an aging pair.

The energy gap Eg of the leading "F!L53" in the photoreceptor of Example 1 formed as described above is 1.8'
It is eV. Further, the composition of the buffer layer 4 is a-8io
, 7C0,3(H), and its Eg is 2. leV. Furthermore, the Eg of the surface layer 5 is 2.7 eV, and the ES
R spin concentration change is 5xlOL:Tn+:! The density of J( is 1
．． 7g/cm, refractive index is 2.1, 1 degree soup is 2000
Kff/-. Furthermore, the hydrogen concentration measured from heat release was 35@ziqin. An image was obtained. Also, 5
In a copy test after copying 10,000 copies, the temperature was 35℃.
Even when copying at a relative humidity of 85%, the image was very clear.

For comparison, a photoconductor similar to that in Example 1, which was affordable but without only the surface layer 5, was prepared, and after 50,000 copies were made in the same manner, a copy test was conducted by changing the atmosphere. ℃
Image resolution has already decreased in an atmosphere with relative humidity of 60%.
Iifi image blurring occurred. Therefore, it can be seen that the temperature resistance was improved by forming this surface layer.

In order to form the surface layer 5, it is not necessarily necessary to use C3f (8), but various hydrocarbons, such as CH4.

C2H6, C4H10, C2H4, CQH2, CaHa
It is possible to use gases such as, and mixtures of these gases with hydrogen or rats. The isobody temperature during surface rlI formation is preferably 50 to 150°C, and the energy required to decompose the gas per unit gas amount is 300 to 20°C.
000J/cc: 6E is extremely desirable. Gas pressure is 0.0
01 to 0.5 Torr is desirable. Applying an external bias voltage during film formation is also effective in controlling the film quality5.Furthermore, in the case of formula discharge, a bias naturally occurs, and this is usually called self-bias. bias voltage d+100~+500V, -100~-
1500V is suitable.

Example 2 Up to the buffer layer 4 was formed using the same procedure and conditions as in Example 1, and a-C(
H) A surface fabric layer was formed to examine its compatibility as a photoreceptor.

The results are shown in Table 1. The thickness of the surface layer at this time was approximately 1 μm.

The final image test was conducted in an atmosphere with a temperature of 25℃ and a relative humidity of 50℃. Copying in ambient air →
The results of the field image trial are shown by O.
Indicates that p was obtained, △ mark; size, shoulder and both images are defective, X
The mark is repaired! jlI! Indicates that a defect has occurred. When the ESR spin concentration is low, the surface image defect is caused by a high residual potential resulting in a dark image. High ES
The serious defect on the first side of R-spin 1 is due to high humidity and blurring of the surface image.

In order for the surface 1#5 to have sufficient performance as a lotus layer from the first layer, the ESR spin concentration of the a-C(H) model forming the S-plane layer must be 10(7) or more than 10 cm. It is desirable that the This means that in this range a-
This is thought to be due to the chemical resistance and mechanical strength of C(H)1-, which are readily stable. a-C(H: The bonded stool of carbon atoms contained in the surface 51J is formed a-C(H)
This is one of the major factors that determines whether eel can be applied as Xf--the surface of a photographic photoreceptor--and is important. The unsupported 11] bond of carbon has an unpaired electron and both the electron spin and 15 are detected. In other words, the history of carbon atoms, past and present, can be seen from the ESR spin/destruction. The carbon atoms; 1, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 1, 2 pins,
A film with low spin art, that is, a film with few defects Ial&, is considered to be of good quality, and it is known that a-C, which is close to a diamond structure with many SP3 bonds, has an ESR spin concentration of 10 to 10'8 tan. However, when a-CIJ is used as a surface layer of an electrophotographic photoreceptor, the optimum range is limited due to the following disadvantages.

When the ESR spin concentration is as low as 10 cm or less, that is, when the dangling bond of carbon 1 is efficiently compensated by water t4 atoms, S in 4? It has many bonds and is chemically stable, but the optical energy gap is about 3. Q
becomes eV. Amorphous silicon photoconductive! -3 optical energy gap is typically 1.6 to 1.9 eV
Therefore, in order to match the photoconductive layer 3 with the a-C(H) surface +15, the optical energy gap of the buffer layer 4 is continuously or It is necessary to increase stepwise, buffer Ii
The film thickness of i4 is 4.

This is undesirable in view of the characteristics of the photoreceptor because it increases the residual potential.

On the other hand, when the ESR spin concentration is high (more than 1ocrR), it is chemically unstable due to the large number of dangling bonds, and deterioration occurs due to ozone and nitrogen oxides generated by corona discharge in the image capture process. This is because the one-sided image of coffee bond in high humidity is poor.

Example 3 Table 2 shows the photoreceptor characteristics when the layers up to the buffer 14 were formed under the same conditions and conditions as in Example 1, and the film thickness of the surface r@5 was changed. Moisture resistance test: 35℃, 85%
These are the results of an image test/inspection using a copying machine in an atmosphere.

Table 2 From the results in Table 2, the film thickness of surface '15 is p
o, oos μm or more, preferably 1.0 μm or less in terms of residual potential and sensitivity, and more preferably 0.01 μm or less.
It is not less than μm and not more than 0.5 μm.

〔Effect of the invention〕

In the present invention, as a surface layer of an electrophotographic photoreceptor having an a-8t photoreceptor, 10 to 1019 ES
An a-C(H) film having an R spin iIt degree is used.

By forming such a surface layer, the excellent properties of the A-8i photoconductive material, such as high photosensitivity, high spectral nitrification sensitivity over the entire visible light range, and low residual potential, can be maintained while Excellent function as a protective film of the a-C(H) film containing hydrogen purposely combined with carbon provided in A photoreceptor that does not cause problems even during long-term storage and repeated use, and hardly any deterioration of characteristics such as image defects is observed even in a high-humidity atmosphere. It is possible to obtain an a-8i electrophotographic material which has stable properties at all times and is hardly restricted by the environment in which it is used, and which has excellent durability, printing durability, and moisture resistance. In this way, the life of the so-called photoreceptor will be extended dramatically.

The effects obtained are enormous.

[Brief explanation of drawings]

・Diagram 1 shows the layer structure of Honhakumei's Ichiji Pond example.
Figure 2 shows an example of the structure of the manufacturing process and equipment used to carry out the present invention.
It is a li diagram, 1...4-forming substrate, 2... blocking layer, 3...
a-8i system light guide awakening・-, 4...Buffer・-15・・
・a-C(H) surface layer. 2.・°−“ Figure 1 Figure 2

Claims (1)

[Claims] 1) In an electrophotographic photoreceptor having a photoconductive layer made of an amorphous silicon-based material on a conductive substrate and further covered with a surface layer, the surface layer has a spin concentration of 10^1^8 due to electron spin resonance absorption. An electrophotographic photoreceptor characterized by being made of hydrogenated amorphous carbon having a thickness of ^-^3 cm to 10^1^9^-^3 cm.