JPH0217021B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field to Which the Invention Pertains] The present invention relates to a selenium photoreceptor for 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. [Prior art and its problems] As a selenium-based photoreceptor for long-wavelength light, from the conductive substrate side, there is a carrier transport layer (CTL) made of pure selenium-based material, a high-concentration Te/35% by weight tellurium or more, A photoreceptor having a three-layer structure is known, in which a carrier generation layer (CGL) made of a Se material and a surface layer (OCL) useful for charge retention made of a pure selenium-based material are sequentially laminated. However, for example, if the Te concentration of the high-concentration Te/Se layer is increased in order to make semiconductor laser printers, which have become the mainstream of optical printers in recent years, sensitive to near-infrared light with a wavelength of approximately 800 μm, charge retention It is difficult to maintain good properties with the above three-layer structure, resulting in a photoreceptor with large dark decay. [Object of the Invention] In order to solve this problem, the present invention provides a highly concentrated Te/Se layer that has sufficient sensitivity even in the semiconductor laser wavelength region.
It is an object of the present invention to provide a selenium photoreceptor for electrophotography, which has a charge retention ability equivalent to that of a general selenium photoreceptor for PPC copying machines, while being a CGL. [Summary of the Invention] The electrophotographic photoreceptor according to the present invention is made of pure selenium or a low concentration selenium alloy on a conductive substrate.
CTL, CGL made of highly concentrated tellurium-selenium alloy;
The above object is achieved by sequentially laminating a tellurium oxide layer with a thickness of 20 Å or more and an OCL made of pure selenium or a selenium alloy. As the CTL, a layer of pure selenium or a selenium alloy containing 7% by weight or less of Te, 7 atomic% or less of arsenic (As), or 10,000ppm or less of halogen elements (I, Cl) is used as the CTL. . As a CGL, the film thickness is 0.3 to 2 μm and the CTL side interface is
Te less than 25% by weight, more than 35% by weight at the OCL side interface
A layer is used that is made of a high concentration Se/Te alloy which may contain 7 atomic % or less of As. As the tellurium oxide layer, a layer in which at least 50% of Te existing between CGL and OCL is oxidized is effective. OCL may be single layer or multilayer, and may be pure Se or
It is made of a Te/Se alloy with a concentration of 13.5% or less, or may contain Ge, Sb, As, Zn, Sn, etc. in an amount of 7 atomic % or less, and a thickness of 0.5 to 5 μm is effective. [Embodiments of the Invention] Invention 1: Pure selenium was vacuum-deposited to a thickness of 60 μm on an aluminum tube with a length of 340 mm and a diameter of 120 mm. At this time, the temperature of the raw tube was maintained at 65°C. As shown in Figure 1
The raw tube 1 on which the CTL 2 was formed was once vacuum-broken and taken out from the furnace. Next, a high concentration Te/Se layer 3 of 40% by weight was first flash-deposited on this drum to a thickness of 0.6 μm. The time required is approximately 10 minutes, the temperature of the raw tube is 40℃, and the temperature of the evaporation source boat is 450℃. The drum with CTL and CGL formed in this way was taken out of the vacuum deposition tank and placed in a constant temperature chamber at 45℃.
I left it for 200 hours. As a result, a tellurium oxide layer 4 was formed. Next, pure selenium was flash-deposited as OCL5 to a thickness of 2 μm on the drum taken out from the thermostat. The boat temperature at this time was 420℃.
The temperature of the raw tube was 40°C, and the time required was about 15 minutes. Example 2: Instead of leaving in a thermostat in Example 1
After UV irradiation was performed for about 1 hour under a 1kW UV lamp to form the tellurium oxide layer 4 shown in FIG. 1, OCL 5 was deposited. Comparative Example 1 This is the same process as in Examples 1 and 2, except for leaving it in a constant temperature chamber and irradiating it with ultraviolet rays.CTL and CGL were laminated on an aluminum tube and then continued.
OCL was formed. Comparative Example 2 As in Comparative Example 1, the product was left in a constant temperature oven and no UV irradiation was performed, but after laminating CTL and CGL, the vacuum was broken and then vacuumed again after about 1 hour.
After setting the temperature to ×10 ⁻⁵ 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 The sample drum was corona charged while rotating at a rotation speed of 16 rpm, and after 1/4 rotation after being charged, the rotation was stopped and the dark decay characteristics of the surface potential at that point for 1 second were measured. , 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 to obtain a half-attenuation exposure dose related to the sensitivity of the photoreceptor. The results obtained are shown in Table 1.

[Table] Sensitivity to laser light is at half-attenuation exposure of 2μJ/
Table ¹ shows that the formation of the oxide layer improves the charge retention within a range that does not impede the sensitivity in practical terms, since it is sufficient that the oxidation layer is not more than cm 2 . However, only the vacuum break (Comparative Example 2) has almost no effect. (2) Analytical test When preparing sample drums for Examples 1 and 2 and Comparative Examples 1 and 2, CTL and CGL formation and oxidation treatment were performed simultaneously on the silicon plate whose surface had been pre-evaporated with Al, and analysis was performed without forming only OCL. As a sample,
The high concentration Te/Se layer was analyzed using electron spectroscopy using VG's ESCALAB5, and near-surface analysis was performed using Auger electron spectroscopy. The results obtained are shown in Table 2.

〔Effect of the invention〕

The present invention uses pure selenium-based CTL and high-concentration Te/Se.
In a three-layer structure photoreceptor for light in the long wavelength region such as laser light, which is made of CGL and surface-protected OCL, by interposing a tellurium oxide layer through active oxidation at the interface between CGL and OCL, it is possible to absorb light in the long wavelength region. It provides extremely good surface retention ability while having sufficient sensitivity to. 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 sectional view of the structure of a photoreceptor according to the present invention;
FIG. 2 is a composition profile diagram showing the results of near-Augier surface analysis of the sample of Comparative Example 1, FIG. 3 is a similar composition profile diagram of the sample of Example 2, and FIG. 4 is a conceptual diagram of the optical interference test. FIG. 5 shows 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...OCL.

Claims (1)

[Claims] 1. On a conductive substrate, a carrier transport layer having a thickness of 30 to 100 μm and made of pure selenium or a selenium alloy containing 7% by weight or less of tellurium, 7% or less of arsenic, or 10,000ppm or less of a halogen element;
A carrier generation layer with a film thickness of 0.3 to 2 μm and made of a tellurium-selenium alloy containing tellurium of 25% by weight or less at the interface on the carrier transport layer side and 35% or more by weight at the opposite interface, and a carrier generation layer with a thickness of 20 Å or more and containing tellurium of 25% by weight or less at the interface on the opposite side. Of the tellurium present between the layer and the surface layer, at least
Tellurium oxide layer with 50% oxidation and film thickness 0.5~
A selenium photoreceptor for electrophotography, characterized in that a surface layer of pure selenium or a selenium alloy containing 13.5% by weight or less of tellurium is sequentially laminated with a thickness of 5 μm.