JPH0296769A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To remarkably reduce negative charge of a photosensitive body by doping a charge transfer layer of an Se function separating laminated type photosensitive body with a halogen element. CONSTITUTION:The title electrophotographic sensitive body is constituted of a charge transfer layer 2 having >=30mum and <=90mum thickness consisting of an Se-As alloy contg. >=5atom.% and <=40atom.% As, a charge generating layer 3 having >=0.5mum and <=2.0mum thickness consisting of an Se-Te alloy contg. >=20atom.% and <=40atom.% Te, and a surface protective layer 4 having >=2mum and <=5Xm thickness consisting of an Se-As alloy contg. >=5atom.% and <=40atom.% As, all being laminated successively on an electroconductive substrate 1, wherein >=2,000 and <=10,000ppm halogen element is contained in the charge transfer layer 2. By doping the Se-As alloy forming the charge transfer layer 2 with a halogen element such as Cl, Br, I, etc., a shallow impurity level is formed in an energy band gap of the Se-As alloy due to the halogen element, injection efficiency into holes from the electroconductive substrate into the charge transfer layer 2 is improved, and hole mobility in the charge transfer layer 2 is also improved. Thus, negative charge on the surface of the photosensitive body is retarded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an Se-based functionally separated laminated electrophotographic photoreceptor used in electrophotographic devices employing a reversal development method, such as electrophotographic printers and digital copying machines. Regarding.

[Conventional technology]

In an electrophotographic apparatus, an electrophotographic photoreceptor (hereinafter also simply referred to as a photoreceptor) is used as an image forming member, and the surface of the photoreceptor is charged in a dark place by corona discharge, and the surface of the charged photoreceptor is statically charged by image exposure 19. Formation of an electrostatic latent image, development of the formed electrostatic 74 latent image with toner, transfer of the developed toner image to paper, separation of the paper on which the image has been transferred from the surface of the photoreceptor, transfer of the toner image to the paper Image formation is performed through a process called fixing.

After paper separation, the photoreceptor is subjected to AC charge removal, residual toner removal, optical charge removal, etc., and is then reused.

The image forming process is divided into a positive charging method and a negative charging method depending on the charging polarity of the surface of the photoreceptor in the charging step. In addition, there are two types of development methods: a regular development method that obtains a solid image from a positive image, and a reversal development method that obtains a positive image from a negative image. The polarities of charging due to corona discharge on the back surface, so-called separation charging, are opposite to each other.

Se-based photoconductive materials are materials with high hole mobility, and Se-based functionally separated laminated electrophotographic photoreceptors (hereinafter also simply referred to as Se photoreceptors) having photosensitive layers made of such materials have a conductive support. The basic structure is that a charge transfer layer and a TL charge generation layer are sequentially laminated on a substrate, and the charge generation layer is located near the surface of the photoreceptor, and is used in a positive charging system.

In electrophotographic printers and digital copiers,
Generally, a laser or an LED is used as an exposure light source, and from the viewpoint of its lifespan, a reversal development method is usually adopted for the image forming process. When a Seg light body is used in such an electrophotographic apparatus, a positive charging type image forming process is adopted as described above. Therefore, during image formation, the surface of the Se photoreceptor is separately charged with negative polarity by negative corona discharge in the transfer process, and charged by AC corona discharge in the paper separation process and AC neutralization process.

The Se photoconductor has a large dark resistance against negative polarity charging, and also tends to form negative space charges inside the photoconductor, resulting in a low positive charging potential in the subsequent charging step of the image forming process. . In addition, the photosensitivity changes due to electrons deeply trapped in the energy bandgap of the Se photoreceptor. Normally, when images are produced continuously in an electrophotographic apparatus, the corona discharges in the transfer process and the paper separation process are performed continuously without interruption. When cut paper is used as the paper to which the toner image is transferred, the surface of the photoreceptor is charged via the cut paper during these steps during paper passing, but the difference between the cut paper and the cut paper that is passed one after another is In between, the surface of the photoreceptor is exposed without being covered by the cut paper, and the surface of the photoreceptor is directly charged in this area. In this way, in the transfer process and paper separation process, differences occur in the amount of surface charge and the electric field applied to the photoconductor between the part of the photoconductor surface that was covered with the cut paper and the part that was not covered. In the subsequent charging step, a difference appears in the decrease in the positive charging potential, and a difference also occurs in the photosensitivity, resulting in a difference in density on the resulting image.

In order to solve these problems, a thin film that facilitates hole injection is provided between the conductive support substrate and the charge transfer layer to prevent the Seg light body from becoming negatively charged. It is known that

[Problem to be solved by the invention]

However, when such a thin film is provided as described above, there is a drawback that the charge transfer layer in contact with the thin film tends to crystallize from the interface, resulting in a problem that the originally necessary positive charging performance of the Se photoreceptor is deteriorated. Providing such a thin film, and
To stably obtain a Se photoreceptor with the required characteristics,
There are many difficult factors in terms of manufacturing technology, and there are many problems.

This invention was made in view of the above points, and
Se-based functionally separated layered electrophotographic photosensitive material that is difficult to charge with negative charges and is unlikely to cause image density differences due to negative charges during the transfer process or paper separation process when used in a reversal development type electrophotographic device. The purpose is to provide the body.

[Failure to solve the problem]

In order to achieve the above object, according to the present invention, a charge transfer layer made of an Se-As alloy containing 5 at% or more and 40 at% of As and having a thickness of 30 μm or more and 90 μm or less is formed on a conductive support substrate. , T of 20 atomic % or more and 40 atomic % or less
It is made of Se-Te alloy containing e and has a film thickness of 0.5 μm or more2
．． Charge generation layer of 0 μm or less and 5 at% or more and 40 at%
In an electrophotographic photoreceptor formed by sequentially laminating a surface protective layer made of the following Se-As alloy containing As and having a thickness of 2 μm or more and 5 μm or less, 2000 ppm in the charge transfer layer is provided.
The electrophotographic photoreceptor contains a halogen element of at least 110,000 pp or less. The halogen element may be contained in the charge transfer layer at a uniform concentration, but it is more preferable that the halogen element is contained in a concentration gradient that is high near the interface of the conductive supporting substrate and decreases as the distance from the substrate increases.

[Effect]

C1,8r in the Se-As alloy forming the charge transfer layer.

When doped with a halogen element such as I, a shallow impurity level is formed by the halogen element in the energy band gap of the Se-As alloy, improving the efficiency of hole injection from the conductive support substrate into the charge transfer layer. Moreover, the hole mobility in the charge transfer layer also increases. As a result, negative charging on the surface of the photoreceptor is suppressed. Increasing the amount of halogen element doped in the charge transfer layer will further suppress negative charging, but on the other hand, it will increase the initial dark decay when the photoreceptor surface is positively charged.
This will have an adverse effect on the essential characteristics of the Seg light body. By creating a concentration gradient in the halogen element doped into the charge transfer layer, that is, by increasing the concentration of the halogen element in the charge transfer layer near the interface of the conductive support substrate and decreasing the concentration as the distance from the substrate increases, this This is more suitable because negative charging can be suppressed while avoiding such adverse effects.

It is also effective to dope the halogen element at a high concentration near the substrate interface, and uniformly dope the other parts at a low concentration.

〔Example〕

FIG. 1 is a schematic cross-sectional view of an embodiment of the photoreceptor of the present invention, in which a charge transfer layer 2 made of a Se-based material is placed on an aluminum support base 1 as a conductive support base. Charge generation layer 3
8 shows a functionally separated laminated photoreceptor in which surface protective layers 4 are sequentially laminated.

Example 1 The Se photoreceptor of the example shown in FIG. 1 was manufactured using the following manufacturing process. Cutting process 1 The surface-treated and cleaned aluminum support substrate 1 is set in a vacuum evaporation device, and the temperature of the substrate 1 is heated to about 190°C and maintained at about IXl, 0-'To.
After reducing the pressure to rr, the halogen element iodine (1
) doped with ^52Se, an evaporation source loaded with about 40
It was heated to 0° C. to form a charge transfer layer 2 with a thickness of about 70 μm. At this time, 100 ppr was added to the evaporation source loaded with 52Se doped with 110,000 pp of iodine.
Using two evaporation sources, evaporation source B loaded with n iodine-doped As, Se, first, evaporation source Δ is heated to selectively evaporate 1 degree high iodine ^s, Se. The As
2Se is evaporated and ^s, Se is evaporated.

The iodine concentration in the film is initially high at IOoooppm, and then decreases over time.As shown in Figure 2, the iodine concentration in the film is high on the substrate interface side and decreases as the distance from the substrate increases. A charge transfer layer with a

Next, as the charge generation layer 3, Se with a Tefi degree of 30 at%
A thin film layer of -Te alloy with a thickness of about 1 μm is formed by a flash/yellow vapor deposition method, and on top of that, a surface protective layer 4 of ^52Se not doped with a halogen element is vacuum-deposited to a thickness of about 3 μm to form a photoreceptor. Toshi Iko.

Example 2 The layer structure and film thickness were the same as in Example 1, but the evaporation source of the charge transfer layer was doped with IOoooppm iodine.
A photoreceptor with a uniform iodine concentration in the charge transfer layer was manufactured using only an evaporation source loaded with Se.

Comparative Example A photoreceptor was fabricated having the same layer structure and film thickness as in Example I, but in which the charge transfer layer was formed by vapor deposition of As or Se that was not doped with iodine.

The photoreceptors of Examples 1 and 2 and Comparative Example were subjected to positive charging, n-light, negative charging for transfer, AC charging for paper separation, and AC static elimination in the same way as in the actual printer, and the surface potential of the photoreceptor was umicolled. went. When the initial positive charging potential was set to 800V, the results shown in Table 1 were obtained.

Table 1 From Table 1, it is clear that when the charge transfer layer is doped with iodine, the negative charge of the photoreceptor is reduced by about 1/2, and the subsequent decrease in positive charge can be reduced. Additionally, when the charge transfer layer is doped with iodine, the initial dark decay of positive charge increases; however, by increasing the amount of iodine doped near the substrate interface and decreasing it as it moves away from the substrate, such dark decay can be suppressed. It can be seen that it is possible to suppress the increase and also to reduce the negative charge.

When the photoreceptors of Examples 1 and 2 were installed in a printer and a printing test was conducted, good printing with little variation in density was obtained.

〔Effect of the invention〕

According to this invention, by doping the charge transfer layer of the Se-based functionally separated layered photoreceptor with a halogen element, negative charging of the photoreceptor can be significantly reduced. By using the Sag light body according to the present invention in a reversal development type electrophotographic device, the amount of negative charge on the surface of the photoconductor in the paper separation process of transfer process 1 is reduced, so that variations in the negative band im due to whether or not paper is passed are reduced. Therefore, the difference in image density due to the difference in the amount of negative charge can be significantly reduced, and a good image can be obtained. moreover,
When the halogen-doped bond in the charge transfer layer has an appropriate concentration gradient, negative charging can be reduced without deteriorating the essential characteristics of the Se photoreceptor, which is more effective.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a photoreceptor according to embodiments of the present invention;
FIG. 2 is a diagram showing an example of the concentration profile of the amount of iodine doped in the charge transfer layer according to the present invention. Reference Signs List: 1 aluminum support substrate, 2 charge transfer layer, 3 charge generation layer, 4 surface protection layer.

Claims (1)

[Scope of Claims] 1) A charge transfer layer made of an Se-As alloy containing 5 at % or more and 40 at % As and having a thickness of 30 μm or more and 90 μm or less, on a conductive support substrate, and a charge transfer layer containing 20 at % or more and 40 at % or more. Made of Se-Te alloy containing less than atomic % of Te, film thickness 0.5
An electrophotographic photosensitive material formed by sequentially laminating a charge generation layer with a thickness of 2.0 μm or more and a surface protective layer made of an Se-As alloy containing 5 at. 20 in the charge transfer layer in the body.
An electrophotographic photoreceptor characterized in that it contains a halogen element in an amount of 00 ppm or more and 10,000 ppm or less. 2) The photoreceptor according to claim 1, characterized in that the concentration of the halogen element in the charge transfer layer is high near the interface of the conductive support substrate and has a concentration gradient that decreases as the distance from the substrate increases. Electrophotographic photoreceptor.