JPS6043662A - Selenium photosensitive body for electrophotography - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body having high sensitivity to long wavelength light by laminating successively a carrier transfer layer consisting of pure Se or an Se alloy contg. Te at a low concn., a carrier generating layer consisting of an Se alloy contg. Te at a high concn., a Te oxide layer having a specific thickness and an Se surface layer on a conductive base body. CONSTITUTION:A carrier transfer layer 2 consisting of pure Se or a Te-Se alloy metal contg. <=7wt% Te and contg. <=7atom% As or <=10,000ppm halogen is formed on a conductive bace body 1. A carrier generating layer 3 which consists of a Te-Se alloy metal contg. <=25wt% Te at the boundary on the layer 2 side and >=35wt% Te at the boundary on the opposite side and may contain <=7atom% As is formed on the layer 2 to 0.3-2mu thickness. A layer 4 in which >=50% Te is oxidized is formed and thereafter a surface layer 5 which consists of pure Se or an alloy contg. <=13.5% Te and which may contain <=7atom% Ge, As, Sb, etc. is then formed The electrophotographic sensitive body having high sensitivity to a long wavelength light source such as a semiconductor laser, LED or the like is thus obtd.

Description

Detailed Description of the Invention [Technical Field to which the Invention Pertains] The present invention relates to electrophotography used for a long wavelength light source such as an optical printer that uses an LED, a He-Ne laser, or a semiconductor laser as a light source. Regarding a selenium photoreceptor.

[Prior art and its problems]

As a selenium-based photoreceptor for long-wavelength light, a carrier transport layer made of a pure selenium-based material (
CTL), a carrier generation layer (CGL) made of a high-concentration Te/Se material containing 35% by weight or more of tellurium, and a surface layer (OCL) made of a pure selenium-based material useful for charge retention. It has been known. However, if the Te concentration of the high-concentration Te/Se layer is increased from the outside, for example, in order to make it sensitive to near-infrared light with a wavelength of approximately 800 μm for semiconductor laser printers, which have become the mainstream of optical printers in recent years, It is difficult to maintain good charge retention with the above-mentioned three-layer structure, which results in a photoreceptor having large dark decay.

[Purpose of the invention]

The present invention solves this problem (7) while having a high concentration Te/Se layer as a CGL that has sufficient sensitivity even in the semiconductor laser wavelength region, its charge retention ability is equivalent to that of a general selenium photoreceptor for PPC copying machines. An object of the present invention is to provide a selenium photoreceptor for electrophotography.

[Key points of the invention]

The electrophotographic photoreceptor according to the present invention includes CTL, which is made of pure selenium or a low-density selenium alloy, and CGL, which is made of a high-density tellurium-selenium alloy, on a conductive substrate.

The above object is achieved by sequentially laminating a tellurium oxide layer with a thickness of 20X or more and an OCL made of pure selenium or a selenium alloy.

The CTL has a film thickness of 30 to 100 μm and contains pure selenium or 7% by weight or less of Te, and 7 atoms or less of arsenic (As).
Or less than 10,000 ppm of halogen elements (I
, C6) is used as the 0 CGL, which has a film thickness of 0.3 to 2 μm and a Te content of 25% by weight or less at the CTL side interface and 35% by weight or more at the OCL side interface.
A layer is used which is made of a high concentration Se/Te alloy which may contain up to 7 atoms of As.

As the tellurium oxide layer, a layer in which at least 50% of Te present between cGL and 0CLO is oxidized is effective.

OCL may be single layer or multilayer, pure SE or 135
Te/Se alloy with a concentration of less than
, Sb, AS, Zn, Sn, etc., in an amount of 7 atoms or less, and a thickness of 0.5 to 5 μm is effective.

[Embodiments of the invention]

Example 1: Pure selenium was vacuum-deposited to a thickness of 60 μm on an aluminum tube having a length of 340 ran and a diameter of 120 III+1. At this time, the temperature of the raw tube was maintained at 65° C. As shown in FIG. 1, the raw tube 1 on which the CTL 2 was formed was once vacuum plated and taken out from the furnace. Next, 40% by weight high concentration Te/Se N3 was first flash deposited onto this drum to a thickness of 0.6 ttm. The time required is approximately 10 minutes, the cumulative tube temperature is 0°C, and the evaporation source boat temperature is 450°C. The drum on which CTL and CGL were thus formed was taken out from the vacuum deposition tank and left in a thermostat at 45° C. for 200 hours. As a result, a tellurium oxide layer 4 was formed on the drum.Pure selenium was then flash-deposited as OCL5 to a thickness of 2 .mu.m on the drum which was taken out from the thermostat. The boat temperature at this time was 420℃, the raw tube temperature was 40℃, and the time required was about 1
It was 5 minutes.

Example 2: Instead of leaving in a thermostat in Example 1, UV irradiation was performed under a 1 kW UV lamp for about 1 hour to form the tellurium oxide layer 4 shown in FIG. 1, and then 0CL5 was coated. Example 1 CT was performed on an aluminum tube using the same process as in Examples 1 and 2, except for leaving it in a thermostat and removing the ultraviolet irradiation.
After laminating L and CGL, OCL was successively formed.

Comparative Example 2 As in Comparative Example 1, the film was left in a constant temperature chamber and no UV irradiation was performed, but after the CTL and CGLflif layers were vacuum plated, the film was vacuumed again after about 1 hour, and 5×10-5
After exposure to Torr, pure selenium was flash-deposited to a thickness of 2 μm to form an OCL.

The following tests were conducted on the four types of photoreceptor samples thus obtained.

(1) Xerographic characteristics test A sample drum was corona charged while rotating at a rotation speed of 16 rpm, and after 174 rotations after being charged, the rotation was stopped and the dark decay characteristic of the surface potential at that point was measured for 1 second. , charge retention was calculated. After this, the sample drum was rotated again, the drum was stopped, and the potential discharge characteristics were measured while irradiating monochromatic light with a wavelength of 800 nm, and a half-attenuation exposure value related to the sensitivity of the photoreceptor was obtained. . The results obtained are shown in Table 1.

Table 1: Sensitivity to laser light is good as long as the amount of half-attenuated light is 2 μJ/Ca or less, so it can be seen from Table 1 that the formation of an oxide layer improves the charge retention within a range where the sensitivity is not a practical problem. . However, only the vacuum break (Comparative Example 2) has almost no effect.

When creating the sample drums of Examples 1 and 2 and Comparative Examples 1 and 2, CTL was performed simultaneously on the silicon plate on which At was vapor-deposited on the surface in advance.
, CGL formation and oxidation treatment were performed, and vG NESCALAB5 was used as an analysis sample without forming only OCL.
The high-temperature 'fe/Se layer was analyzed by electron spectroscopy, and near-surface analysis was performed by Auger electron spectroscopy. The results obtained are shown in Table 2.

As shown in Table 2, it was found that an oxide layer consisting of TeO2 was clearly present on the CGL surface. Note that the half-width indicates the depth to which the oxygen concentration becomes 1/2 of the value at the surface, and Figures 2 and 3 show the vicinity of the surface of the sample where each element was analyzed by Auger electron spectroscopy while sputtering the surface. The composition profile is shown in Figure 2 for Comparative Example 1 and Figure 3 for Example 2.
This is the value obtained by The etching speed by sputtering was 100 A/min.

(3) Light interference test: As shown in Figure 4, when monochromatic light 11 with a wavelength of 650 to 1l100n is incident at an angle of 45° from the surface normal 12, approximately 20 to 30 beams of light appear on the surface. is reflected as reflected light 13, but the remaining light passes through 0CL5.

OCL made of pure selenium or a low concentration alloy hardly absorbs light in this wavelength range. If the refractive indexes of OCL5 and the layer 6 below it are significantly different, the light 15 reflected at the interface 14 will interfere with the light 13. The degree of this interference is layer 4.6
depends on the difference in refractive index at the interface. For example, the refractive index for light of 700 nm is about 2.5 for pure selenium, whereas it is not so large when 40% by weight 15 is CGI below the OCL. The degree of interference between the reflected lights 13 and 15 was examined for each sample drum by continuously changing the wavelength of the incident light. As a result, in the comparative example, the intensity of the reflected light was mostly due to interference, or in the case of the drum of Example 7, an extremely clear interference pattern was observed as shown in FIG. 5, and the same was true for the drum of Example 2. Te, OCL
It can be easily seen that within the CGLO there are layers with significantly different optical properties. Such a layer is a tellurium oxide layer, as is clear from the above analysis results. From the above tests, we were able to accurately determine the film thickness of the surface OCL to the order of 1/100 μm from the interference pattern shown in Figure 5. It was revealed that the formation of the tellurium oxide layer 4 improved the E charge retention ability.

Note that the compositions of the CTL, CGL, and OCL layers are not limited to those in the above embodiments, and can be changed as in a known three-layer structure photoreceptor.

〔Effect of the invention〕

The present invention uses pure se4-based CTL, high concentration Te/se CTL,
In a photoreceptor with a three-layer structure, which is a reservoir for light in the long wavelength region such as a laser beam, consisting of GL and a surface layer @OCL, CG
By interposing a tellurium oxide layer by active oxidation at the interface between L and OCL, it is possible to provide extremely good surface retention ability while having sufficient sensitivity to light in the long wavelength region.

This tellurium oxide layer is presumed to function to prevent electrons from among the carriers generated within the CGL from being injected into the surface layer after the surface of the photoreceptor is positively charged by corona discharge in the dark. As a result, the charge retention ability is improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the structure of the photoreceptor according to the present invention, FIG. 2 is a composition profile diagram showing the results of near-Auger surface analysis of a 1Ω sample of comparative example, and FIG. 3 is a similar composition profile diagram of the sample of Example 2. , FIG. 4 is a conceptual diagram of the optical interference test, and FIG. 5 is a reflection pattern obtained with the sample of Example 1 when the wavelength of the incident light changes. 1... Conductive substrate, 2... CTL, 3
...CGL, 4...Tellurium oxide layer, 5
・・・・・・OCL0Q Table of Contents Invitation

Claims (1)

[Claims] 1) A carrier transport layer made of pure selenium or a low concentration selenium alloy, a carrier generation layer made of a highly strained tellurium-selenium alloy, a tellurium oxide layer with a thickness of 20X or more, and a pure A selenium photoreceptor for electrophotography, characterized by a surface layer of selenium or a low-concentration selenium alloy laminated in sequence. 2. Between the photoreceptors according to claim 1, the carrier transport layer has a film thickness of 3 to 100 μm and is made of pure selenium, tellurium of 7 atoms or less, arsenic of 7 atoms or less, or 10. A selenium photoreceptor for electrophotography, characterized in that it contains a selenium metal containing a halogen element of O'OOppm or less. 3) In the photoreceptor according to claim 1 or 2, the carrier generation layer has a film thickness of 0.3 to 2 μm at the carrier transport layer side interface, 25' M it: −m or less, and at the opposite side field W1+. 1. A selenium photoreceptor for electrophotography, comprising a layer containing tellurium in an amount of 35% by weight, and may contain arsenic in an amount of 7 or less by weight. 4) In the photoreceptor according to any one of claims 1 to 3, in the tellurium oxide layer, at least 50 of the tellurium present between the carrier generation layer and the surface layer is oxidized. A selenium photoreceptor for electrophotography characterized by layers. 5] In the photoreceptor according to any one of claims 1 to 4, the surface layer is formed of a single layer or a multilayer, and has a thickness of 0.5 to 5 μm and is made of pure selenium or 135
It is a layer similar to a Te/Se alloy with a concentration of less than 7 atoms, in which germanium, antimony, arsenic,
A selenium photoreceptor for electrophotography, which may contain zinc or soot.