JPH03197955A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body superior in printing resistance and heat resistance and good in dark decay characteristics and fatigue characteristics and stable even under high temperature by forming an electric charge injection restraining layer made of an Se-As-S alloy between a charge generating layer and a surface protective layer. CONSTITUTION:The electrophotographic sensitive body is formed by successively laminating on a conductive substrate 1 the charge transfer layer 2 made of an Se-As alloy, the charge generating layer 3 made of an Se-Te alloy, the charge injection restraining layer 4 made of the Se-As-S alloy, and the surface protective layer 5 made of an Se-As alloy. The layer 4 restrains heat excited carriers generated in the photosensitive body, especially, in the layer 3 at high temperature from transferring to the layer 5, thus permitting electrophotographic sensitive body to be superior in printing resistance and heat resistance, good in dark decay characteristics and fatigue characteristics and stable in even under environment high temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor used in digital copying machines, printers, etc. that use long wavelength light as exposure light.

[Conventional technology]

In this type of electrophotographic application equipment, a semiconductor laser diode + HeNe laser is used as an exposure light source.

Light emitting diodes and the like are mainly used. Since the light from these light sources has a long wavelength of 630 nm to 800 nm, the electrophotographic photoreceptor (hereinafter simply referred to as photoreceptor) used has high sensitivity even in such a long wavelength light region. A charge generation layer made of a selenium/tellurium alloy with a high tellurium concentration, a charge transport layer made of a selenium/arsenic alloy that transports the charges (holes) generated in this charge generation layer to a conductive substrate, and a charge generation layer. Functionally separated multilayer laminated photoreceptors equipped with a surface protective layer for protection from external stress have generally been used. As the material for the above-mentioned surface protective layer, a selenium-arsenic alloy is used from the viewpoints of rigidity resistance, chemical stability, heat resistance, etc. The higher the arsenic concentration of the alloy used, the better the printing durability and heat resistance of the surface protective layer will be. However, as the arsenic concentration increases, the problem arises that the dark decay characteristics and fatigue characteristics of the photoreceptor deteriorate. .

As one solution to these problems, Japanese Patent Application Laid-Open No. 1-112250, filed by the applicant, discloses a method of combining a charge generation layer made of a selenium-tellurium alloy with a high tellurium concentration and a surface protective layer. By interposing a charge injection suppressing layer made of pure selenium or a selenium-arsenic alloy with a low arsenic concentration of 10% by weight or less, the surface protective layer can be formed without deteriorating the dark decay characteristics and fatigue characteristics of the photoreceptor. It has been disclosed that it is now possible to use a selenium-arsenic alloy with a high arsenic concentration as a material, and a photoreceptor with excellent characteristics, including a surface protective layer with significantly improved printing durability and heat resistance, can be obtained. .

In addition, amorphous silicon and amorphous silicon nitride other than selenium-based materials are known as surface protective layer materials aimed at increasing printing durability. Crystalline boron nitride and amorphous silicon nitride oxide are also known in Japanese Patent Application Laid-open No. 81430/1983.

[Problem to be solved by the invention]

However, a charge injection suppressing layer made of pure selenium or a selenium-arsenic alloy is laminated on the charge generation layer made of the selenium-tellurium alloy mentioned above, and then a charge injection suppressing layer made of a selenium-arsenic alloy with a high arsenic concentration is layered on top of the charge-injection suppressing layer made of pure selenium or a selenium-arsenic alloy. A photoreceptor with a laminated surface protective layer has a large charge injection suppressing layer effect in a room temperature environment, and has good dark decay characteristics and fatigue characteristics.
In a high-temperature environment, this effect is no longer sufficient, and a problem arises in that deterioration of dark decay characteristics and fatigue characteristics cannot be prevented completely.

Furthermore, when using the above-mentioned materials other than the selenium-arsenic alloy as the material for the surface protective layer, it takes a long time to form the surface protective layer because the film is formed on the charge generation layer by glow discharge. In short, it has the disadvantage that the price of the photoreceptor becomes high.

The present invention solves the above-mentioned problems, and has a charge generation layer made of a selenium-tellurium alloy with a high tellurium concentration and highly sensitive to long wavelength light, a charge generation layer made of a selenium-arsenic alloy with a high arsenic concentration, which has excellent printing durability, It is an object of the present invention to provide a photoreceptor which is provided with a surface protective layer having excellent heat resistance, has good dark decay characteristics and FM working characteristics, and is stable and suffers little deterioration even in a high temperature environment.

[Means to solve the problem]

To achieve the above object, the present invention provides a charge transport layer made of a selenium-arsenic alloy and a charge generation layer made of a selenium-tellurium alloy on a conductive substrate.

In a photoreceptor in which a surface protective layer made of a selenium-arsenic alloy is laminated, a charge injection suppressing layer made of a selenium-arsenic-sulfur alloy is interposed between the charge generation layer and the surface protection layer. Alternatively, a charge injection suppressing layer made of a selenium-arsenic-sulfur alloy is interposed between the conductive substrate and the charge transport layer. Alternatively, a charge injection suppressing layer made of a selenium-arsenic-sulfur alloy is interposed between the conductive substrate and the charge transport layer and between the charge generation layer and the surface protective layer.

[Effect]

The present invention has a small coefficient of thermal expansion.
) was created based on the fact that an alloy with an arbitrarily high resistance value can be obtained as shown in Figure 2. The charge injection suppression layer made of a high-resistance selenium-arsenic-sulfur alloy suppresses the movement of thermally excited carriers generated inside the photoreceptor, especially in the charge generation layer, to the surface protective layer at high temperatures, improving dark decay characteristics and fatigue. Deterioration of characteristics can be suppressed.

In addition, the layer made of a high-resistance selenium-arsenic-sulfur alloy provided between the conductive substrate and the charge transport layer functions well as a charge injection suppression layer even in high-temperature environments, and is The charge injection can be effectively suppressed, and an increase in dark decay can be prevented.

Furthermore, by interposing a high-resistance charge injection suppressing layer both between the conductive substrate and the charge transport layer and between the charge generation layer and the surface protective layer, fatigue properties in high-temperature environments are reduced. It is possible to reduce the drop in charge when static elimination is repeated.

〔Example〕

FIG. 1 is a schematic cross-sectional view of one embodiment of a photoreceptor according to the present invention, in which a charge transport layer 2 and a charge generation layer 3 are laminated on a conductive substrate 1, and selenium, arsenic, sulfur, etc. A surface protective layer 5 is provided with a charge injection suppressing layer 4 made of a base alloy interposed therebetween.

Example 1 A conductive substrate 1 made of a machined and cleaned aluminum cylindrical tube with a diameter of 80 nm was attached to a rotating support shaft of a vapor deposition apparatus, and the temperature of the conductive substrate 1 was heated to about 190° C. and maintained at this temperature. , I x 111' Torr, and then the evaporation source filled with Asm5es alloy was
Heated to 00°C and placed about 6
After depositing the charge transport layer 2 with a uniform thickness of 0 -, a 5e-Te alloy containing 34 atomic % of Te was deposited as the charge generation layer 3 to a thickness of about 0.5 nm by flash evaporation. ,
AS*Sel+S-rich alloy is used as the charge injection suppressing layer 4.
J! A surface protective layer 5 of Hes, Se, and an alloy was sequentially deposited to a thickness of about 1.1 mm, and then layered to a thickness of about 2 mm to form a photoreceptor. For flash deposition, the rotating support shaft temperature is 60°C and the pressure is IX.
The experiment was carried out under the conditions of 10-' Torr and evaporation source temperature of 350°C.

Example 2 In Example 1, the vapor deposition material of the charge injection suppressing layer 4 was As.
A photoreceptor was produced in the same manner as in Example 1, except that the 655g5 alloy was used and the thickness of the deposited film was reduced to about 0.5-.

Comparative Example 1 In Example 1, except that the vapor deposition material of the charge injection suppressing layer 4 was changed to a 5s-As alloy containing 5 at% As.
A photoreceptor was produced in the same manner as in Example 1.

The temperature dependence of the dark decay characteristics of the photoreceptors of Examples and Comparative Examples thus produced was investigated. The results are shown in FIG. 3. The dark decay amount on the vertical axis in FIG. 3 is the percentage of the dark decay potential 1 second after charging with respect to the initial charging potential. Furthermore, as fatigue characteristics, the amount of charge reduction after 250 cycles of charging and exposure was measured, and its temperature dependence was investigated.

The results are shown in FIG. 4. The charge reduction amount on the vertical axis in FIG. 4 is the percentage of the potential difference between the initial charge potential and the charge potential after 250 cycles with respect to the initial charge potential.

From FIG. 3 and FIG. 4, it is clear that the photoconductors of Examples 1 and 2 have significantly improved dark decay characteristics and fatigue characteristics at high temperatures compared to the photoconductor of Comparative Example 1. be.

FIG. 5 is a schematic sectional view of another embodiment of the photoreceptor according to the present invention, in which parts common to those in FIG. 1 are given the same reference numerals. That is, on a conductive substrate 1, a charge injection suppressing layer 4 made of a selenium-arsenic-sulfur alloy, a charge transport layer 2 made of a selenium-arsenic alloy, a charge generation layer 3 made of a selenium-tellurium alloy, and a selenium - It has a structure in which a surface protection layer 5 made of an arsenic alloy is laminated.

Example 3 Diameter 80m processed and cleaned in the same way as Example 1
A conductive substrate 1 made of an aluminum cylindrical tube was attached to a rotating support shaft of a vapor deposition device, the temperature of the conductive substrate 1 was heated to about 60° C., maintained at this temperature, and evacuated to 1×10 −′ Torr. A charge injection suppressing layer 4 is formed by depositing AsSe+, □S+, and tS alloys to a thickness of 1 μm on the rotating conductive substrate 1 using a flash deposition method, and then the temperature of the conductive substrate 1 is lowered to about 1 μm. The evaporation source filled with As1Se3 alloy was heated to 190°C and then heated to about 400°C to deposit a charge transport layer 2 having a uniform film thickness of about 60μ. A Ss-Te alloy containing 34 atomic % of To was deposited to a thickness of about 0.5μ as the charge generation layer 3, and a ^s@Se2 alloy was deposited to a thickness of about 2N as the surface protection layer 5. A photoreceptor having the configuration shown in FIG. 5 was manufactured.

The conditions for flash deposition are the same as in Example 1.

FIG. 6 is a schematic cross-sectional view of still another embodiment of the photoreceptor according to the present invention. Components common to those in FIG. 5 are given the same reference numerals. That is, a charge injection suppressing layer 4 is provided between the charge generation layer and the surface protection layer 5 of the photoreceptor shown in FIG. 5, similar to the photoreceptor shown in FIG.

Example 4 After the charge generation layer 3 was deposited in Example 3, a charge injection suppressing layer was again deposited on AsSe+, xsse+, and ts gold alloys to a thickness of about 1 nm, and then the same surface protective layer 5 as in Example 3 was deposited. were laminated by flash vapor deposition to produce a photoreceptor having the structure shown in FIG.

Comparative Example 2 A photoreceptor was produced in the same manner as in Example 3.4 except that the charge injection suppressing layer 4 was not provided.

The temperature dependence of dark decay was investigated for the photoreceptors of Example 3.4 and Comparative Example 2 produced in this way. The results are shown in FIG. 7. The dark decay rate on the vertical axis in FIG. 7 is the percentage of the dark decay potential 1 second after charging with respect to the initial charged potential, as in the case of FIG. Further, as fatigue characteristics, as in the case of FIG. 4, the amount of charge reduction when charging and exposure were repeated 250 cycles was measured, and its temperature dependence was investigated.

The results are shown in FIG.

From FIG. 7 and FIG. 8, it is clear that the photoconductors of Examples 3 and 4 have significantly improved dark decay characteristics and fatigue characteristics at high temperatures compared to the photoconductor of Comparative Example 2. be. In particular, the photoreceptor of Example 4, in which the charge injection suppressing layer was provided at two locations, between the conductive substrate and the charge transport layer and between the charge generation layer and the surface protective layer, had a It can be seen that the material has excellent properties because charge injection into the photoreceptor and transfer of thermally excited carriers generated in the charge transport layer and charge generation layer inside the photoreceptor to the surface protective layer (photoreceptor surface) are suppressed.

In the photoreceptor of each example, the charge generation layer is formed of a selenium-tellurium alloy with a high tellurium concentration, and the surface protective layer is formed of a selenium-arsenic alloy with a high arsenic concentration. Therefore, the photoreceptor of the example has high sensitivity to long wavelength light, good dark decay characteristics and fatigue characteristics, and has excellent characteristics that do not deteriorate even in high-temperature environments.
It has a surface protection layer with excellent heat resistance.

〔Effect of the invention〕

According to the present invention, a high-resistance selenium-arsenic-sulfur alloy is provided between the charge generation layer and the surface protective layer, between the conductive substrate and the charge transport layer, or between each of them. By providing a charge injection suppressing layer consisting of a selenium-arsenic alloy, the charge-transport layer is formed of a selenium-arsenic alloy, a charge-generating layer is formed of a selenium-tellurium alloy with a high tellurium concentration, and a surface protective layer is formed of a selenium-tellurium alloy with a high arsenic concentration.・If formed from an arsenic alloy, it has a surface protective layer with excellent rigidity and heat resistance, has high sensitivity to long wavelength light, and has good dark decay characteristics and fatigue characteristics, even in high temperature environments. It becomes possible to obtain a photoreceptor that is stable and rarely deteriorates.

The photoreceptor according to the present invention has become rapidly popular in recent years.
It can be suitably used in digital copiers, printers, etc. that use long wavelength light from semiconductor laser diodes, light emitting diodes, etc. as exposure light. Furthermore, high quality images can be obtained even under high temperature environments, and the effects of this invention are remarkable.

In addition, the surface protective layer material in the present invention is a selenium-arsenic alloy, and unlike the case of non-selenium-based materials such as amorphous silicon, the surface protective layer is formed using a method that requires a long time such as glow discharge. It also has the advantage that it can be easily formed by vacuum evaporation without using it, and the photoreceptor can be manufactured at low cost.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of an embodiment of a photoreceptor according to the present invention, and Figure 2 shows the relationship between the electrical resistance of a selenium-arsenic-sulfur alloy and the amount of sulfur added to Aa and Set in the alloy. 3 and 4 are diagrams showing the temperature dependence of the dark decay characteristics and fatigue characteristics of the photoconductors of Example 1.2 and Comparative Example 1, respectively, and FIGS. FIGS. 7 and 8, which are schematic cross-sectional views of further different examples of the photoreceptor according to the invention, are diagrams showing the temperature dependence of the dark decay characteristics and fatigue characteristics of Example 3.4 and Comparative Example 2, respectively. be. 1 conductive substrate, : charge transport layer, 3 : charge photoform layer, : charge injection suppression layer, : surface protection layer. 10 20゜King [1 degree (°C) 0 0 Fig. 3 0 0 0 0 iH, temperature (0C) Fig. 4 Fig. 1 Amount of S permeated into AS2Se3 (atomic %) 2nd island Fig. 5 Figure 6

Claims (1)

[Claims] 1) A charge transport layer made of a selenium/arsenic alloy, a charge generation layer made of a selenium/tellurium alloy, and a surface protection layer made of a selenium/arsenic alloy are laminated on a conductive substrate. selenium between the charge generation layer and the surface protective layer.
A photoreceptor for electrophotography characterized by having a charge injection suppressing layer made of an arsenic-sulfur alloy. 2) A conductive substrate in which a charge transport layer made of a selenium/arsenic alloy, a charge generation layer made of a selenium/tellurium alloy, and a surface protection layer made of a selenium/arsenic alloy are laminated on a conductive substrate. selenium between the charge transport layer and the charge transport layer.
A photoreceptor for electrophotography characterized by having a charge injection suppressing layer made of an arsenic-sulfur alloy. 3) A conductive substrate in which a charge transport layer made of a selenium/arsenic alloy, a charge generation layer made of a selenium/tellurium alloy, and a surface protection layer made of a selenium/arsenic alloy are laminated on a conductive substrate. An electrophotographic photoreceptor characterized in that a charge injection suppressing layer made of a selenium-arsenic-sulfur alloy is interposed between the charge transport layer and the charge generation layer and the surface protective layer.