JPS60237455A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To attain high sensitivity in a longer wavelength range and superior stability to a temp. change by forming a photosensitive Se-As layer free from film defects such as pinholes and having a specified structure on an electrically conductive substrate. CONSTITUTION:A photosensitive layer consisting of the 1st layer 2 of 10-30mum thickness made of Se contg. about 20-30wt% As and the 2nd layer 3 of 10- 70mum thickness made of Se contg. about 30-45wt% As is formed on an electrically conductive substrate 1. Since the layer 2 having the lower As content is formed on the substrate 1 side, the temp. of the substrate 1 during vapor deposition can be reduced, so the release of occluded or adsorbed gas from the substrate 1 is inhibited, whereby film defects such as pinholes and image defects resulting from the film defects are prevented. Since the difference in As content between the layers 2, 3 is small, a sensitive body which is hardly affected by its heat history and has durability can be obtd. Since the average As content of the photosensitive layer is high, high sensitivity especially in a longer wavelength range of >=700mum can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to an electrophotographic photoreceptor having a photosensitive layer made of an -e-lene/arsenic-based photoconductive material.

[Prior art and points of interest]

The atomic composition of selenium/arsenic photosensitive I- is AsSe
3 alloy, 38.8% by weight selenium containing arsenic, is known. This vapor-deposited film made of AS 2 S e 3 has the advantage that the composition of the vapor-deposited film is more stable than that of the 5e-Te-based vapor-deposited film, and that it is highly sensitive in the long wavelength chain region. However, since the glass transition temperature of As2Se3 is as high as 175°C, a smooth surface cannot be obtained unless the temperature of the photoreceptor substrate is maintained at a high temperature during vapor deposition. It has the disadvantage that it is easily released by heating and causes film defects such as pinholes.

In order to prevent the occurrence of such defects, a degassing process such as preheating of gas is required before vapor deposition, which has the disadvantage of requiring a lot of man-hours. Further, the vapor deposition apparatus also has the drawback that it requires the ability to heat the substrate to a high temperature and equipment that can withstand high temperatures.

On the other hand, the photosensitive layer is made of two layers, and the first layer on the substrate side is made of pure selenium.
A second layer thereon having a composition of As4 Se3 or a composition close to it is known, for example, from JP-A-48-102623. However, such photoreceptors are susceptible to thermal history due to the difference in thermal expansion coefficient between pure selenium and selenium with a high arsenic concentration, and have the disadvantage that defects such as wrinkles occur in the photosensitive layer due to temperature changes. Furthermore, since the average As# degree of the photosensitive layer as a whole decreases, there is a drawback that the sensitivity in the long wavelength region also decreases.

Purpose of the Invention The present invention eliminates the above-mentioned drawbacks, and provides a photoreceptor for electrophotography that has few film defects such as pinholes, has high sensitivity in a long wavelength region, and is stable against temperature changes. The aim is to provide it at low cost.

[Key points of the invention]

The electrophotographic photoreceptor of the present invention has a first layer made of selenium containing 30% by weight of arsenic from the substrate side and having a thickness of 10 to 30 μm, and a photosensitive layer on a conductive substrate, and a first layer having a thickness of 10 to 45% by weight. The above object is achieved by having a second layer made of selenium containing 10 to 70 μm in thickness. The glass transition temperature of selenium including arsenic addition and nodule it% is 79
Since the temperature is 105° C., it is possible to perform deposition at a lower substrate temperature than when As25ea is deposited.

[Embodiments of the Invention] FIG. 1 shows a two-layer structure of a photoreceptor adopted according to the present invention, in which a first layer 2 and a second layer 3 are sequentially laminated on an aluminum base l.

Example 1: Base 1 of a cylindrical aluminum tube with an outer diameter of 100 III
A first layer 2 consisting of selenium containing 20% by weight of arsenic on top of
was formed by vacuum evaporation to a thickness of about 10 μm. At this time, the pressure in the vapor deposition tank was approximately 10-3 Pa, and the evaporation source temperature was 430°C. A smooth layer was obtained at a substrate temperature of 180'C. On top of this, a second layer 3 made of selenium containing 4% of arsenic 438.8.7N was formed to a thickness of about .mu.m.

At this time, the pressure inside the tank was approximately 10 Pa, and the evaporation source temperature was 45
Similarly, the substrate temperature was 180°C at 0°C.

Example 2: Selenium 1-2 containing 30% by weight of arsenic was deposited on the same aluminum substrate 1 as in Example 1.
It was formed by Makabe vapor deposition at 0 Am. The vapor deposition conditions at this time were a pressure of 10 Pa, an evaporation source temperature of 430° C. for the first layer 2, 450° C. for the second layer 3, and a substrate temperature of ISO'C.

Comparative example...38 on the same aluminum substrate as in the example
．． Selenium containing 8% by weight arsenic, i.e. As2S
A photosensitive layer with a thickness of about 1 μm in a single layer of e4 is subjected to pressure IQ ”
Pa, evaporation source temperature 450'C, substrate temperature i 210
Vacuum deposition was performed under the deposition conditions of 'C.

Table 1 shows the characteristics of these photoconductors. 1-0 Table 1 Measurement conditions were that the photoconductor was rotated at a circumferential speed of 3g0m7m, and leakage through the substrate was measured. The charge tolerance is the value obtained by dividing the charging potential by the film thickness when a corona voltage such that the current is 280 μA is applied to the surface of the photosensitive layer, and the potential when exposing the photosensitive layer 501 and the fi The value obtained by subtracting the ratio from 1 to 1 is the optical attenuation rate, and the potential when exposed to 120 Ax is defined as the residual potential.Also, as the repeated fatigue characteristic, the charge decrease when the cycle of charging and exposure is repeated 200 times. and an increase in residual potential.

Table 2 shows the results of counting defects in white areas when a photoreceptor is installed in a copying machine and an entirely black original is copied.

In the second table, curve 21 is Example 11, strain n is Example 29, curve 3
3 is for a photoreceptor of a comparative example.

1st. The following can be seen from Table 2 and Figure 2.

Both Examples 1 and 2 have a slightly increased charge acceptance and a slightly lower optical attenuation rate than the comparative example, but have almost the same potential characteristics as an As2Se3 single layer. Both the charge reduction and the residual potential increase due to repeated cycles are equivalent to the Nor 52se3 single layer of the comparative example, indicating good characteristics. The wavelength spectral characteristics are also the same as those of the comparative example, with sensitivity in the long wavelength region of 700 yn or more. Regarding image defects, both Examples 1 and 2 are significantly improved compared to the comparative example. This is because the As concentration in the vicinity of the interface with the substrate is significantly reduced in the example compared to the comparative example, which makes it possible to deposit a smooth glass-like interface at the interface even at a low substrate temperature. This is the result of being able to suppress the release of occluded gas and adsorbed gas from the substrate during vapor deposition.

〔Effect of the invention〕

In the present invention, a first layer is provided on the side of the selenium/arsenic-based photosensitive layer closer to the substrate, and the arsenic content is kept low at 10 to 10% by weight, thereby lowering the substrate temperature during vapor deposition. As a result, release of occluded gas and adsorbed gas from the substrate during vapor deposition is suppressed, and film defects such as pinholes and image defects caused thereby are reduced. Therefore, it is possible to shorten or eliminate a degassing process such as preheating of the substrate before vapor deposition to prevent film defects, and manufacturing costs can be significantly reduced. In addition, the arsenic content of the first layer is from % to 4%, and the arsenic content of the second layer is from % to 4%.
Since the difference from 5% by weight is small, it is possible to obtain a durable photoreceptor that is less susceptible to the effects of thermal history. Further, according to the layer structure of the present invention, the average arsenic content of the entire layer is 23 to 43.
Since the amount of filtering is at a high level of %, the sensitivity, that is, the optical attenuation wheel is large, and the wavelength spectral characteristics also allow high sensitivity to be obtained in the long wavelength region of 700 m or more.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a photoreceptor according to an embodiment of the present invention;
FIG. 2 is a wavelength spectral sensitivity diagram of a photoreceptor according to an example of the present invention and a photoreceptor of a comparative example. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Low arsenic first layer, 3-...High arsenic second layer. Figure 1 Figure 2 Wavelength [nm] -

Claims (1)

[Claims] l) Adding arsenic to a conductive substrate as a photosensitive layer from the substrate side (
9) having a first layer of selenium containing 30 to 451% arsenic and a thickness of lO to 70μ; Characteristic electrophotographic photoreceptor.