JPH021300B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a carrier propagation layer (hereinafter referred to as CTL).
and a functionally separated selenium photoreceptor for electrophotography having a carrier generation layer (hereinafter referred to as CGL).

[Prior art and its problems]

In a functionally separated photoreceptor, there is a difference in the concentration of component elements such as tellurium at the interface between CTL and CGL, making it difficult for carriers to move between CTL and CGL. For this purpose, it is known that a bonding layer is interposed between CTL and CGL to facilitate carrier movement. As a bonding layer for this type of functionally separated photoreceptor, for example, Japanese Journal of Applied Physics No. 20
Vol., No. 1 (1981), pp. 119-124, methods using pure selenium are known at the laboratory level, but they are still not sufficient. Especially in low electric fields (1 to 5 V/μm or less),
Since the carrier generated by light irradiation shows a shot barrier type injection at the joint, development occurs in which the sensitivity depends on this injection performance, and after all, within a limited exposure time, the light It is known that this results in a photoreceptor with an extremely high residual potential that cannot be completely attenuated. Needless to say, in a photoreceptor like this example, the residual potential during repeated copying tends to further increase.

Other bonding layers made of selenium doped with chlorine are known. In this case, although the intended purpose has been achieved in terms of realizing a low residual potential, it has the following drawbacks and is not sufficiently practical.

(1) Cl is a substance with strong sublimation properties, and it is extremely difficult to uniformly mix a predetermined amount of Cl with Se to create the desired Cl-added Se.

(2) During vapor deposition, Cl-doped Se adhered to the vacuum equipment together with Se and Se-Te, or Se and Se-Te from the photoreceptor.
It is extremely difficult to purify and reuse Cl-added Se recovered together with Te. In particular, if even a small amount of Cl is mixed into Se, the temperature characteristics will deteriorate significantly, making it impossible to use recovered raw materials.
Since the mixed Se and Se-Te must be disposed of, this leads to an increase in raw material costs.

Another way to improve the bonding properties of CTL and CGL is to use Se-Te systems, for example.
In addition to using low-concentration Te-Se for CTL and high-concentration Te-Se for CGL, a gradient is added to the Te concentration of CTL, and the Te concentration on the CGL side of the CGL is
The concentration is controlled so that the difference is 15 wt% or less (preferably 10 wt% or less). Alternatively, without adding a Te concentration gradient to the CTL,
Similar good bonding performance can be obtained even if the CGL is bonded under the above conditions with a Te concentration gradient. Alternatively, it goes without saying that similar good bonding performance can be obtained by applying a Te concentration gradient to both CTL and CGL and bonding under the above conditions. However, these cases have the following drawbacks.

(1) Desirable Te because Se and Te have different vapor pressures
It is a very difficult technique to create a concentration gradient stably with good reproducibility. Therefore, by appropriately controlling the Te concentration gradient of CTL, CGL, or both, it is difficult and unproductive to reduce the Te concentration difference between the CGL side of CTL and the CGL side to less than 10 wt%. .

(2) To obtain good conjugation between CTL and CGL,
It is extremely difficult to control the creation of large concentration gradients in CTLs with good reproducibility. because,
Since CTL is thicker than CGL and usually has a thickness of about several tens of micrometers,
It is difficult to control Te concentration with good reproducibility. Also,
In a photoreceptor, the surface Te concentration should be kept as low as possible to ensure bonding properties by keeping the CTL Te concentration as low as possible (for example, 0%) and creating a large gradient in the CGL Te concentration. Sensitivity decreases due to abrasion of the surface layer during repeated copying or refining due to a large difference between the Te concentration directly below it, or Te concentration that progresses when left at high temperatures.
Decrease in sensitivity due to diffusion may occur, causing serious problems in practical use.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks and provides a functionally separated type electrophotographic device in which a bonding layer for alleviating the influence of the barrier between CTL and CGL is provided by means that are easy to produce without deteriorating temperature characteristics or other characteristics. The purpose of the present invention is to provide a photoreceptor for use.

[Key points of the invention]

The present invention attempts to achieve smooth bonding performance by interposing an oxygen-added Se layer with a thickness of 2 to 10 μm between oxygen-free CTL and CGL.

It is known that when oxygen is added to Se, the DC electrical conductivity increases in an orderly manner and the activation energy significantly decreases. CTL and
Providing an oxygen-doped Se layer between the CGL and CGL is equivalent to alleviating the difference in energy gap due to the difference in concentration of alloying elements between the two by providing a layer with an intermediate energy gap. It is thought that this is the reason why smooth bonding performance is achieved.

The present invention can be effectively implemented not only for functionally separated photoreceptors having only CTL and CGL but also for those having a surface protective layer (OCL) on the surface.

[Embodiments of the invention]

The photoreceptor according to the present invention is made of pure Se on an aluminum substrate 1, for example, as shown in FIG.
CTL2, bonding layer 3 made of oxygen-doped Se, Se-Te
CGL4 consisting of is laminated.

Example 1 In order to form a photoreceptor having the structure shown in FIG.
An aluminum raw tube was attached to a rotating support shaft in a vacuum evaporation apparatus, and an evaporation source containing Se was heated by a resistance heating method to deposit a pure Se layer 2 on the raw tube 1 to a thickness of 63 μm. The substrate temperature was 61° C., and the degree of vacuum during deposition was 5×10 ⁻⁵ Torr or higher. When the deposition of pure Se layer 2 is completed, the vacuum is broken and oxygen is added to the evaporation source.
Inject the Se raw material, evacuate again, and form the oxygen-added Se layer 3 on top of the pure Se layer 2 under the same conditions as for pure Se.
Laminated to a thickness of 5 μm.

Fig. 2 shows a method for producing an oxygen-added Se raw material, in which selenium 11 is stored in a container 12 that is resistant to nitric acid, hydrogen peroxide, etc.
are sealed with a lid 13 having the same resistance.
A container 14 having the same resistance is filled with a solution 15 having oxidizing properties to selenium 11, such as nitric acid or hydrogen peroxide. If left in this state for a while, selenium 11 will be oxidized and the surface will become cloudy. To shorten the time left unattended, when leaving
The solution 15 may be exposed to light, heated, or both may be performed simultaneously. When the oxygenated Se obtained in this way was crushed and subjected to wet analysis,
It was 3.28×10 ³ O ₂ ppm by weight. After the oxygen-added Se vapor deposition, the vacuum was broken again, and 42 g of 13.5 wt% Se-Te alloy prepared to the size of 40 meshes and 980 meshes was arranged in the raw material supply system of the evaporation source, and then vacuum was drawn again. The carbon boat serving as the evaporation source is energized, and when the boat temperature rises to 450°C, the raw material is smoothly supplied to the boat, and a flash of SeTe alloy is deposited on the oxygen-added Se layer 3 to form CGL4 with a thickness of 2 μm. Created.

FIG. 4 shows the xerographic characteristics of the photoreceptor having the structure shown in FIG. 1 of Example 1 of the present invention.
Gain). According to the electric field dependence data (a) of Xerographic Gain, this photoreceptor is
µm, therefore approximately 14V). Therefore, it can be seen that the photoreceptor has good bonding performance with no barrier between CTL and CGL.

Figure 5 shows a comparative photoreceptor having the structure shown in Figure 3.
This is Xerographic Gain data.
Based on the electric field dependence data (a) of Xerographic Gain,
This photoreceptor has a threshold value at an electric field of about 1 V/μm, and therefore, it can be seen that the photoreceptor has a high residual potential, and the potential does not drop below about 70 V.

FIG. 6 shows an apparatus for evaluating the repeated potential behavior of this photoreceptor. The photoreceptor 21 rotates in the direction of the arrow in the figure at a circumferential speed of 100 mm/sec. A charger 22 performs charging, and a probe 23 and a probe 25 measure this potential. The exposure light source 24 is blinked,
The exposure condition is set to five times the half-attenuation exposure amount. The static elimination light 26 is set to 10 times the half-attenuation exposure, and the potential after static elimination is measured with a probe 27. According to the measurement results, the final value of the potential after exposure of the photoreceptor having the bonding layer of Example 1 was 60 V, and the final value of the potential after static elimination was 5 V. On the other hand, the photoconductor having the structure shown in FIG. In the comparative example photoreceptor, the final value of the potential after exposure is 80V, and the final value of the potential after static elimination is 40V.
It was found that the photoreceptor according to the present invention has extremely good fatigue properties.

Next, under the same manufacturing conditions as Example 1, the thickness of the bonding layer was 0 (same as the comparative example) 0.5 μm, 1 μm, 2 μm, 5 μm,
After laminating with varying thickness of 10 μm, CGL is 25
The xerographic properties and cyclic fatigue properties of the photoreceptor formed of Se-Te alloy of % by weight were investigated.

FIG. 7 shows the Xerographic diagram shown in Example 1.
This diagram summarizes the electric field threshold value in the electric field dependence data of Gain in one diagram. C.G.L.
Even when the Te concentration is as high as 25% by weight, the effect of the oxygen-doped Se bonding layer is significant. in this case,
The appropriate thickness of the bonding layer is 2 μm or more, preferably 5 μm or more. FIG. 8 shows the final values of the post-exposure potential (potential of the probe 25) measured with the apparatus shown in FIG. 6. It can be said that the effect of the oxygen-doped Se bonding layer is remarkable. However, if the thickness of the bonding layer is made thicker than necessary, it will cause deterioration of temperature characteristics and increase in charge reduction, so it is preferably 10 μm or less.

Example 2 Two evaporation source boats were prepared in advance in the evaporation apparatus, and the CTL and bonding layer were prepared under the same conditions as in Example 1 without breaking the vacuum, and then CGL was prepared under the same conditions as in Example 1. When a photoreceptor prepared by vapor deposition was evaluated, results similar to those of the photoreceptor of Example 1 were obtained.

Example 3 SeO ₂ was used as a method for producing oxygen-doped Se.
A photoreceptor was manufactured under the same conditions as in Example 1 except that 1000 ppm of Se was added directly to pure Se, and the same results as in Example 1 were obtained.

Example 4 As shown in FIG. 9, after forming a CTL 2 made of pure Se on an aluminum substrate 1 under the same conditions as in FIG.
After evaporating to a thickness of 1 μm, 2 μm, 5 μm, and 10 μm, and arranging 21 g of 40 wt% Se-Te alloy in the raw material supply system of the evaporation source along with the one without oxygen-added Se layer for comparison. , in a similar manner to Example 1.
CGL4 with a thickness of 1 μm was fabricated by flash deposition of Se-Te alloy. After this, the vacuum is broken again,
Pure powder prepared to a particle size of 40 mesh to 80 mesh
After 2 kg of Se was placed in the raw material supply system, the system was evacuated again. Next, when the temperature of the evaporation source carbon boat has risen to 380℃, the raw material is smoothly supplied to the boat.
Thickness by flash deposition of pure Se on CGL
OCL5 of 1 μm was formed. Among these, the xerographic characteristics of the bonding layer 3 having a film thickness of 0.5 μm and 10 μm are shown in FIG. 10 and FIG. 11, respectively.
Paying attention to the electric field dependence of Xerographic Gain, the photoreceptor shown in FIG. 10 and the photoreceptor shown in FIG. 11 clearly behave differently in a low electric field. 1st
For the photoconductor shown in Figure 0, an electric field of 1 to 2 V/μm
The convergence of the Xerographic Gain is observed and the electric field threshold is high, indicating that the residual potential of this photoreceptor is high. The photoreceptor shown in FIG. 4 has an electric field threshold of 1 V/μm or less, is sensitive to low electric fields, has a low residual potential, and is thus found to have good bonding performance.

Of this Xerographic Gain data, 500mm
Based on optical measurement data, Xerographic Gain is
FIG. 12 shows the relationship between the thickness of the bonding layer 3 and the electric field threshold value, when the electric field at 10 ^-2 is represented as an amount corresponding to the electric field threshold value, together with the values of comparative examples. As in the case of FIG. 7, the presence of the bonding layer lowers the electric field threshold, leading to a decrease in residual potential. In particular, it was found that when a bonding layer of 5 μm or more was added, extremely good bonding performance was exhibited.

As a result of repeatedly measuring the potential behavior of photoreceptors with bonding layer thicknesses of 0.5 μm and 10 μm using the apparatus shown in Figure 6, the final value of the post-exposure potential of the photoreceptor with a bonding layer of 0.5 μm was 130 V, after static elimination. The final value of the potential was 110V, which indicates that this photoreceptor does not necessarily exhibit satisfactory fatigue characteristics.
On the other hand, the final value of the potential after exposure of the photoreceptor having a bonding layer of 10 μm is 40 V, and the final value of the potential after static elimination is 25 V, indicating that this photoreceptor exhibits good fatigue characteristics.

Figure 13 shows the final value of the post-exposure potential (probe 25 potential) among the data on repeated potential behavior, and as in Figure 8, the effect of the oxygen-doped Se bonding layer is remarkable, and the film By increasing the thickness,
It can be seen that further improvement in bonding performance can be achieved.
However, CTL and CGL have a bonding layer with a thickness exceeding 10μm.
As with the photoreceptor having the structure shown in FIG. 1, sandwiching between the two must be avoided.

〔Effect of the invention〕

According to the invention, CTL and CGL, or even
Oxygen is added as a bonding layer between CTL and CGL in a functionally separated photoreceptor with OCL on top of CGL.
By incorporating the Se layer, CTL and CGL
Good bonding performance, i.e. low residual potential, regardless of the large or small concentration difference of alloying elements, e.g. Te, between Effects that can be easily manufactured can be obtained. Also, Se-Te alloy
Even when the Te content of CGL is high, good bonding performance can be achieved by controlling the thickness of the bonding layer. The thickness of the bonding layer can be easily controlled by simply changing the input amount of raw materials.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the structure of one embodiment of the present invention, and Figure 2 is an oxygen-added
FIG. 3 is a cross-sectional view of a conventional functionally separated photoreceptor for comparison, and FIG. 4 shows the Xerographic Gain of an embodiment of the present invention.
a is a relationship diagram with electric field strength using wavelength as a parameter, b is a relationship diagram with wavelength in an electric field of 10 V/μm, Figure 5 shows the Xerographic Gain of a comparative example, and Figure 5 a and b are respectively Figure 4 shows the relationship between electric field strength and wavelength, Figure 6 shows the layout of the evaluation device for repeated potential behavior, and Figure 7 shows the relationship between electric field threshold and bonding layer thickness. Relationship diagram, Figure 8 is a relationship diagram between repeated residual potential and bonding layer thickness.
FIG. 9 is a sectional view showing the structure of another embodiment of the present invention, and FIG. 10 is a Xerographic gain of a photoreceptor having the structure shown in FIG. 9 and having a bonding layer with a thickness of 0.5 μm.
Figures 10a and 10b are the same relationship diagrams with electric field strength and wavelength as in Figure 4, respectively, and Figure 11 shows a photoconductor with the same structure but a bonding layer 10 μm thick. Figures 11a and 11b also show the relationship diagram with the electric field strength, respectively.
Figure 12 is a graph showing the relationship between the electric field threshold value of the photoreceptor having the structure shown in Figure 9 and the thickness of the bonding layer. It is a relationship diagram with film thickness. DESCRIPTION OF SYMBOLS 1... Aluminum base, 2... CTL, 3... Oxygenated Se layer, 4... CGL, 5... OCL.

Claims (1)

[Claims] 1. In an electrophotographic selenium photoreceptor having a carrier propagation layer and a carrier generation layer to which no oxygen is added, an oxygen-added selenium layer with a thickness of 2 to 10 μm is interposed between the carrier propagation layer and the carrier generation layer. A selenium photoreceptor for electrophotography characterized by the following.