JPH0293655A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance photosensitivity and to lower residual potential by successively laminating an a-SiGe photoconductive layer, a-Si photoconductive layer and a-SiC photoconductive layer. CONSTITUTION:The photoconductive layer 2 consisting of amorphous silicon germanium (a-SiGe), the photoconductive layer 3 consisting of amorphous silicon (a-Si), the photoconductive layer 4 consisting of amorphous silicon carbide (a-SiC), and an org. photosemiconductor layer 5 are successively laminated on a conductive substrate 1. The atomic compsn. ratio of the silicon (Si) element and carbon (C) element of the amorphous silicon germanium are in a 0.05<x<0.5 range in the X value of Si1-xGe and the atomic compsn. ratio of the silicon (Si) element and carbon (C) of the amorphous silicon carbide layer is in a 0.05<y<0.5 range in the y value of Si1-yCy. The high photosensitivity is obtd. in this way and the residual potential is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor comprising a laminated layer of an amorphous inorganic photoconductive layer and an organic photoconductor layer.

[Prior art and its problems]

Photoconductive materials for electrophotographic photoreceptors include Se, 5e-Te,
.

ASzS*3+ZnO+CdS+ There are inorganic materials such as amorphous silicon and various organic materials. Among them, Se was the first to be put into practical use, and then ZnO,
CdS.

Amorphous silicon has also been put into practical use. On the other hand, among organic materials, PVK-TNP was first put into practical use, and later, a functionally separated photoreceptor was proposed in which the functions of charge generation and charge transport were shared between separate organic materials, and this functionally separated photoreceptor The development of organic materials is progressing dramatically.

On the other hand, an electrophotographic photoreceptor in which an organic photoconductive layer is laminated on the inorganic photoconductive layer has also been proposed.

For example, there is a laminated photoreceptor with a Se layer and an organic optical semiconductor layer.
Although it has already been put into practical use, this photoreceptor has the disadvantage that Se itself is harmful and has poor sensitivity on the long wavelength side.

Therefore, JP-A-56-14241 proposes a laminated photoconductor consisting of an amorphous silicon carbide photoconductive layer and an organic photoconductor layer, and this photoconductor solves the above-mentioned problems. The properties of pollution resistance and high light sensitivity were obtained.

However, when the present inventors manufactured such an electrophotographic photoreceptor and measured its photosensitivity and residual potential, it was found that both characteristics were still unsatisfactory, and further improvements were needed. There was found.

Therefore, the present invention has been completed in view of the above,
The purpose is to provide an electrophotographic photoreceptor that has high photosensitivity and reduced residual potential.

[Means for solving problems]

According to the present invention, there is provided an electrophotographic photoreceptor in which an amorphous silicon germanium layer, an amorphous silicon layer, an amorphous silicon carbide layer, and an organic photoconductor layer are sequentially laminated on a conductive substrate, wherein the silicon ( Si) element and carbon (
C) The atomic composition ratio of the element is 0 with a 5i1-1lGeXOX value
．． 05 < x < 0.5, silicon (Si) of the amorphous silicon carbide layer
The atomic composition ratio of the element and carbon (C) element is St 1□C
An electrophotographic photoreceptor is provided, characterized in that the y value of y is within the range of 0.05 < V < 0.5.

The present invention will be explained in detail below.

FIG. 1 shows the layer structure of the electrophotographic photoreceptor of the present invention.
A photoconductive layer (hereinafter abbreviated as a-SiGe) made of amorphous silicon germanium (hereinafter abbreviated as a-SiGe) is formed on a conductive substrate (1).
2) Amorphous silicon (hereinafter abbreviated as a-5i)
A photoconductive layer (3) made of amorphous silicon carbide (hereinafter abbreviated as a-3iC)
) and an organic optical semiconductor layer (5) are sequentially laminated. The a-SiGe photoconductive layer (2), the a-3i photoconductive layer (3), and the a-3iC photoconductive layer (4) have a function of generating charges, and the other organic photoconductive layer (5) has a function called charge transport.

The present invention is a photosensitive layer (2) (3) having a charge generation function.
(4) are stacked in the above order, so that the light incident from the surface side of the organic optical semiconductor layer (5) is a-3iC
The light on the short wavelength side is mainly absorbed by the photoconductive layer (4), and then the remaining light, mainly on the long wavelength side, is absorbed by the a-SiGe photoconductive layer (2), and as a result, the overall photosensitivity is reduced. It is characterized by the fact that the residual potential is increased over the period of time, and the residual potential is reduced.

First, regarding the a-3iC photoconductive layer (4), when the element ratio is set within the following range, this layer (4)
) can significantly increase its photosensitivity.

Composition formula: (Si+-x Cx) +-a^a (where 8 is hydrogen or halogen) 0.05 < x < 0.5, preferably 0.1 <
x < 0.40.2 < a < 0.5, preferably 0.25 < a < 0.45 If the X value is 0.05 or less, the photosensitivity on the short wavelength side cannot be increased and the X value becomes 0.5
In the above cases, the photoconductivity becomes extremely low, and the excitation function of photocarriers deteriorates.

When the a value is 0.2 or less, the dark conductivity tends to increase, and the photoconductivity tends to decrease, so that the desired photoconductivity cannot be obtained and the a value is 0.2 or less. If it is 5 or more, the internal stress of a-5iCi increases and the film becomes easy to peel off.

In addition, the a-3iC photoconductive layer (4) contains hydrogen (H) elements and halogen elements for terminating dangling bonds, but among these elements, element (1) is easily incorporated into the terminating portion; This is desirable in that the local level density in the band gap is reduced.

The thickness of the a-SiC photoconductive layer (4) is 0.05 to 2 μm,
It is preferable to set it within the range of 0.1 to 1 μm, and within this range, high photosensitivity can be obtained and the residual potential will be low.

Regarding the a-5iGe photoconductive layer (2), when the element ratio is set within the following range, the photosensitivity on the long wavelength side can be significantly increased.

Composition ratio: (Sil-y Gey) I-b B
b (where B is hydrogen or halogen) 0.05 < V < 0.5, preferably 0
．． 1 < y < 0.40.2 < b
< 0.5, preferably 0.25 < b < 0.45y
If the value is 0.05 or less, the absorption of long wavelength light is small, so the photosensitivity cannot be increased, and if the y value is 0.5 or more, internal defects in the film will increase and the photoconductivity will decrease. As a result, the excitation function of photocarriers decreases.

If the b value is 0.2 or less, sufficient photoconductivity as desired cannot be obtained, and if the b value is 0.5 or more, internal stress of the aSiGe photoconductive layer (2) itself is the cause. This makes the film easy to peel off.

Also in this a-SiGe photoconductive layer (2), H element is desirable as a dangling bond termination element in that the localized level density is reduced.

The thickness of the a-5iGe photoconductive layer (2) is 0.05 to 2 μm
, preferably set within the range of 0.1 to 1 μm,
Within this range, high photosensitivity can be obtained and the residual potential will be low.

Furthermore, regarding the electrophotographic photoreceptor of the present invention, the above a-S
An a-Si photoconductive layer (3) is formed between the iGe photoconductive layer (2) and the a-SiC photoconductive layer (4), thereby further increasing photosensitivity. For this purpose, the thickness of this layer (3) may be set within the range of 0.05 to 2 μm, preferably 0.1 to 1 μm.

The electrophotographic photoreceptor of the present invention can be set to be a negatively charged type or a positively charged type by selecting the material for the organic photosemiconductor layer (5). That is, in the case of a negatively charged electrophotographic photoreceptor, an electron donating compound is selected for the organic photosemiconductor layer (5), while in the case of a positively charged electrophotographic photoreceptor, an electron donating compound is selected for the organic photosemiconductor layer (5). An inhalable compound is chosen.

Examples of the electron-donating compounds include those having high molecular weight, such as poly-N-vinylcarbazole, polyvinylpyrene,
There are polyvinyl anthracene, pyrene-formaldehyde condensation polymer, etc., and low molecular weight ones include oxadiazole, oxazole, pyrazoline, triphenylmethane, hydrazone, triarylamine, N-phenylcarbazole, and stilbene. Low molecular weight substances include polycarbonate, polyester, methacrylic resin, polyamide, acrylic epoxy, polyethylene,
It is used after being dispersed in a binder such as phenol, polyurethane, butyral resin, polyvinyl acetate, or urea resin.

Examples of the electron-withdrawing compound include 2,4,7-trinitrofluorene.

Further, the substrate (1) is made of copper, brass, SOS, A
There are metal conductors such as I, or insulators such as glass and ceramics coated with a conductor thin film.Among these, ^l is advantageous in terms of cost and adhesion to the a-SiGe layer. be.

Thus, according to the invention, a-3iGc photoconductive layer, a-
By sequentially laminating the Si photoconductive layer and the a-SiC photoconductive layer, the photosensitivity could be increased over the entire wavelength range.

Further, as shown in FIG. 2, the electrophotographic photoreceptor of the present invention has an a-SiC photoconductive layer (4) and an organic photoconductor layer (5).
) may be formed between the carbon (C) element-rich N region (4a) and the organic photoconductive N (4). The difference in dark conductivity between the semiconductor layers (5) is reduced, so that carriers are no longer trapped at the interface between both layers (4) and (5).

That is, the dark conductivity of the a-SiC photoconductive layer (4) is approximately 10-
The dark conductivity of the other organic optical semiconductor layer (5) is approximately 10-10"-10" (Ωcm).
Therefore, the photoconductive layer (2
) (3) The carriers generated in (4) do not flow smoothly to the organic optical semiconductor layer (5) due to the large difference in dark conductivity. Therefore, the inventors of the present invention found that Ji? fI
forming a layer region (4a), thereby forming a layer region (4a)
It was found that the difference in dark conductivity between the two layers (4) and (5) could be reduced, and as a result, both the characteristics of photosensitivity and residual potential were improved. .

Such C element high content layer region (4a) is composed of C as described below.
It is expressed by element content ratio and thickness.

The C element content ratio is 0.2 < X value of Si layer-xc
x < 0.5, preferably within the range of 0.3 < If the difference in ratio cannot be made as small as required, thereby making it impossible to improve the respective characteristics of photosensitivity and residual potential, and if the X value is 0.5 or more, the a-5iC photoconductive layer carriers become more likely to be trapped, and the photosensitivity characteristics deteriorate.

Also, the thickness is 10 to 2000, preferably 500 to 10
If the number of people is less than 10, the characteristics of photosensitivity and residual potential cannot be improved, and if the number of people is more than 2,000, the residual potential tends to increase. be.

The C element content of each of the a-5iC photoconductive layer (4) and the C element high content layer region (4a) may be varied in the layer thickness direction. For example, there are examples shown in FIGS. 3 to 8, in which the horizontal axis is the layer thickness direction, and a is the a-3i photoconductive N(3) and the a-5iC photoconductive N(
4), b is the interface between the a-5iC photoconductive layer (4) and the C element high content N region (4a), and C is the interface between the C element high content layer region (4a) and the organic optical semiconductor layer (5). The vertical axis represents the C element content.

Furthermore, in the electrophotographic photoreceptor of the present invention, the photoconductive layer (2) (3) (4) contains 1 to 500 p of a Ma group element.
pn+, preferably 2 to 200 ppm.

Regarding this ma group element content, layer (2) (3)
(4) It is expressed by the average value of light per layer as a whole, and when the average content is less than ippm, the dark conductivity tends to increase, and moreover, a decrease in photosensitivity is observed; In this case, the dark conductivity becomes significantly large, and the ratio of the photoconductivity to the dark conductivity becomes small, making it impossible to obtain the desired photosensitivity.

When the photoconductive layer (2) (3) (4) contains the Ma group element, the doping distribution may be either uniform or non-uniform over the layer thickness direction. When doped non-uniformly, part of this layer (2) (3) (4) is
There may be a layer region that does not contain group a elements, in which case ([IEJ Si region containing group Ia elements and ma
Consists of both layer regions that do not contain group elements (2)
(3) (4) The average content of the l1la group elements in the entire layer must be 1 to 500 ppm.

The MA group elements include B, AI, Ga, In, etc., but B has excellent covalent bonding properties and can sensitively change semiconductor properties, and is said to have excellent charging ability and photosensitivity. desirable in that respect.

Next, a method for manufacturing the electrophotographic photoreceptor of the present invention will be described.

To form the a-Si layer, the a-5iC layer, or the a-5iGe layer, there are thin film forming methods such as a glow discharge decomposition method, an ion blating method, a reactive sputtering method, a vacuum evaporation method, and a CVD method.

a-SiC layer or a-SiG using glow discharge decomposition method
When forming the e-layer, a film is formed by combining a Si element-containing gas and a C element-containing gas or a Si element-containing gas and a Ge element-containing gas, and plasma decomposing the respective mixed gases. This Si element-containing gas contains 5illa, 5i211
5i311e, SiF4.5iC14, 5iHC1:
+ etc., and C element-containing gases include CH4, Czt14
．． Cztlz, Czlls, etc., and Ge element-containing gases include, for example, Getla, GeHCl3. GeH
2C1z, GetlCIs, GeCl4. GeF41G
There are i3ztlb and GeJs.

The glow discharge decomposition device used in this example will be explained with reference to FIG.

In the figure, the first tank (6), second tank (7), third tank (8), and fourth tank (9) are SiJ and CJ, respectively.
2. Gel+4 and 11□ are sealed, and these gases are passed through the corresponding first regulating valve (10) and second regulating valve (11), respectively.
, by opening the third regulating valve (12) and the fourth regulating valve (13), and the flow rate of the released gas is controlled by the mass flow controllers (14), (15), and (16), respectively.
(17). And S i Ha,
The gases C2H21G e Ha and Hz are mixed and sent to the main pipe (18). Note that (19) is a stop valve.

Gas flowing through the main pipe (18) flows into the reaction tube (20), and a capacitively coupled discharge electrode (21) is installed inside this reaction tube (21), and a cylindrical film-forming electrode (21) is installed inside the reaction tube (21). A substrate (22) is placed on a substrate support (23), and the substrate support (23) is rotationally driven by a motor (24).
Along with this, the substrate (22) is rotated. Then, the electrode (21) has a power of 50w to 3Kw and a frequency of 1 to 50M.
Hz high frequency power is applied and the substrate (22) is heated by suitable heating means to a temperature of about 200-400°C, preferably about 200-350°C. In addition, the reaction tube (
20) is connected to a rotary pump (25) and a diffusion pump (26), which maintain the necessary vacuum state (gas pressure during discharge of 0.1 to 2.0 T) during film formation by glow discharge.
orr) is maintained.

The substrate (2
When forming the a-5iC layer on 2), the first regulating valve (
10), the second regulating valve (11) and the fourth regulating valve (13) are discharged, and the discharge amount is controlled by the mass flow controller (14).
(15) Controlled by (17), each gas is mixed and flows into the reaction tube (20) via the main pipe (18). When the vacuum inside the reaction tube, substrate temperature, and high-frequency power applied to the electrodes are set to predetermined conditions, glow discharge occurs, and an a-SiC film is rapidly formed on the substrate as the gas decomposes. .

The organic optical semiconductor layer is formed as follows.

The organic photosemiconductor layer is formed by a dip coating method or a coating method, in which the photosensitive material is immersed in a coating solution in which it is dispersed in a solvent, then pulled up at a constant speed, and then air-dried and heated. According to the latter coating method, a photosensitive material dispersed in a solvent is applied using a coater, and then dried with hot air. I do.

〔Example〕

Next, examples of the present invention will be described.

(Example 1) The present inventors used the glow discharge decomposition apparatus shown in FIG.
The a-SiGe photoconductive layer, a-S
The t photoconductive layer and the a-5iC photoconductive layer were sequentially laminated on an aluminum substrate, and then an organic photoconductive layer (film thickness approximately 15 μm) made of polycarbonate in which a hydrazone compound was dispersed
11) was formed and used as an electrophotographic photoreceptor.

[Margin below]

In addition, the above a-SiGe photoconductor 1 (2) and a-Si
The amount of Ge and the amount of C in each C photoconductive layer (4) are expressed as
When the amount of H in each layer was measured using an ay Micro Analyzer and an infrared absorption method, the results shown below were obtained.

a-SiGe photoelectric layer (2) (Sio, aJll!a, 3+) o, t Ho
, 3 The patent evaluation of the thus obtained electrophotographic photoreceptor was measured using an electrophotographic property measuring device, and it was found that excellent photosensitivity was obtained.

(Example 2) In manufacturing the electrophotographic photoreceptor of the above (Example 1),
a-3iGe photoconductive layer (2) and a-SiC photoconductive layer (4) are formed without forming a-S+ photoconductive layer (3); The -3iC photoconductive layer (4) was formed under exactly the same film forming conditions, and the respective thicknesses were set to 0.6 μm and 0.8 μm, thereby producing an electrophotographic photoreceptor. When the photosensitivity of this electrophotographic photoreceptor was measured, it was found to be about 10x lower than that of the electrophotographic photoreceptor of (Example 1).

(Example 3) Furthermore, in manufacturing the electrophotographic photoreceptor of (Example 1), the present inventors changed the gas flow rate of CH, gas, Get (4 gas, etc.), and as a result, as shown in Table 2, a -3i
Twelve types of electrophotographic photoreceptors (from photoreceptor to L) were manufactured in which the C pattern of the C photoconductive layer and the amount of Ge in the a-5iGe photoconductive layer were changed.

When the photosensitivity and residual potential of these electrophotographic photoreceptors were measured, the results shown in Table 2 were obtained.

In the same table, photosensitivity is classified into three levels based on relative evaluation: ◎, ○, and △. ◎ indicates the best photosensitivity, and ○ indicates slightly more expensive light This is a case where sensitivity was obtained, and the mark △ indicates a case where photosensitivity was slightly inferior to the others.

In addition, the residual potential is also evaluated relative to three levels.
The ○ mark indicates the case where the residual potential is the smallest, the Δ mark indicates the case where the increase in the residual potential has been slowed down somewhat, and the X mark indicates the case where the residual potential has increased more than the others and is a practical problem. This is the case when there is.

Photoreceptors marked with * are outside the scope of the present invention.

As is clear from Table 2, the photoreceptors C to J of the present invention had high photosensitivity and a significantly reduced residual potential.

However, the photoreceptor ^, B has poor photosensitivity, and the photoreceptor has
In L, both the photosensitivity and residual potential were significantly deteriorated.

(Example 4) Next, in manufacturing the electrophotographic photoreceptor of (Example 1), the present inventors created an a-5iGe layer, an a-3i layer, and an a-5i
By varying the thickness of each C layer, ten types of electrophotographic photoreceptors (photoreceptors to V) shown in Table 3 were manufactured.

When the photosensitivity and residual potential of each photoreceptor were measured, the results shown in Table 3 were obtained.

[Margin below]

Table 3 As is clear from Table 3, the photoreceptor 0-T has excellent photosensitivity and has a significantly reduced residual potential.

〔Effect of the invention〕

As described above, according to the electrophotographic photoreceptor of the present invention, a-Si
By sequentially laminating the Ge photoconductive layer, the a-3i photoconductive layer, and the a-SiC photoconductive layer, the photosensitivity was increased and the residual potential was significantly reduced.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing the layer structure of the electrophotographic photoreceptor of the present invention, and FIGS. 3, 4, 5, 6, 7, and 8 show carbon elements. Diagram showing content, No. 9
The figure is an explanatory diagram of a glow discharge decomposition device. (1)... Conductive substrate (2)... Amorphous silicon germanium photoconductive layer (3)... Amorphous silicon photoconductive layer (4)...
・Amorphous silicon carbide photoconductive layer (5)...Organic optical semiconductor layer Patent applicant (663) Kyocera Corporation Representative Kinjudo Anjo Takao Kawamura

Claims (4)

[Claims] (1) An electrophotographic photoreceptor in which an amorphous silicon germanium layer, an amorphous silicon layer, an amorphous silicon carbide layer, and an organic photoconductor layer are sequentially laminated on a conductive substrate, the silicon element and carbon of the amorphous silicon germanium layer The atomic composition ratio of the elements is 0.05<x<0.
5, and the atomic composition ratio of silicon element and carbon element in the amorphous silicon carbide layer is within the range of Si
An electrophotographic photoreceptor characterized in that the y value of _1_-_yC_y is in the range of 0.05<y<0.5. (2) The electrophotographic photoreceptor according to claim 1, wherein the thickness of the amorphous silicon germanium layer is within the range of 0.05 to 2 μm. (3) The thickness of the amorphous silicon layer is 0.05~
The electrophotographic photoreceptor according to claim 1, wherein the thickness is within the range of 2 μm. (4) The electrophotographic photoreceptor according to claim 1, wherein the thickness of the amorphous silicon carbide layer is within the range of 0.05 to 2 μm.