JPH01315765A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance photosensitivity by forming an amorphous silicon carbide photoconductive layer having a specified atomic composition containing a specified amount of specified element. CONSTITUTION:The amorphous silicon carbide photoconductive layer 2 forming a photosensitive layer on a conductive substrate together with an organic photosemiconductor layer has an atomic composition satisfying the atomic formula: (Si1-xCx)1-yAy (A is H or halogen), and 0<x<0.5, and 0.2<y<0.5, and contains an element of group IIIa of the periodic table in an amount of 1-1,000ppm, thus permitting the obtained electrophotographic sensitive body to be enhanced in photosensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor comprising a laminated layer of an amorphous silicon carbide photoconductive layer and an organic photoconductor layer.

[Prior art and its problems]

Photoconductive materials for electrophotographic photoreceptors include Se, 5e-Te,
.

A s z S e z + Z n O+ Cd S
There are inorganic materials such as % amorphous silicon and various organic materials, of which Se was first put into practical use, and ZnO, CdS, and amorphous silicon were also put into practical use. Among organic materials, PVK-TNF was first put into practical use, and later, a functionally separated photoreceptor was proposed in which the functions of charge generation and charge transport were shared between separate materials. development has progressed dramatically.

On the other hand, an electrophotographic photoreceptor in which an organic photoconductive layer is laminated on an inorganic photoconductive layer has also been proposed.

For example, there is a laminated photoreceptor with a Se layer and an organic optical semiconductor layer.
Although this photoreceptor has already been put into practical use, it has the disadvantage that Se itself is harmful and that the sensitivity is poor on the long wavelength side.

Therefore, Japanese Patent Application Laid-Open No. 56-14241 proposes a laminated photoconductor consisting of an amorphous silicon carbide photoconductive layer and an organic photoconductor layer, and this photoconductor solves the above problems and is non-polluting. Characteristics of high light sensitivity and light sensitivity were obtained.

The electrophotographic photoreceptor proposed above has the composition formula si, -XCXH,
(However, 0<x<1.0.05≦y≦0.2) It has a structure in which an amorphous silicon carbide layer and an organic optical semiconductor layer are sequentially laminated.

However, when the present inventors manufactured such an electrophotographic photoreceptor and measured its photosensitivity, it was found that satisfactory characteristics were not yet obtained and further improvement was required.

Therefore, the present invention was completed in view of the ridges, and its object is to provide an electrophotographic photoreceptor that has high photosensitivity.

[Means for solving problems]

The electrophotographic photoreceptor of the present invention has an amorphous silicon carbide photoconductive layer (hereinafter amorphous silicon carbide abbreviated as a-SiC) and an organic photoconductive layer sequentially laminated on a conductive substrate, and the a-5iC photoconductive layer described above is laminated in sequence. The constituent elements of the layer are the S'1 element, the C element, and hydrogen or halogen, where hydrogen or halogen is expressed as the element, and the element ratio of the core layer is expressed as the composition formula [Si1-XCX) ly A y. , then let X and y be h O < X < 0.
5.0.2 < y < 0.5 (7) Set within the range, and further add the periodic table 1 [[A group elements from 1 to 1 *
It is characterized in that it is contained within a range of 0,000 ppm.

The present invention will be explained in detail below.

FIG. 1 shows the layer structure of the electrophotographic photoreceptor of the present invention.
According to the figure, an a-5iC photoconductive layer (2) and an organic optical semiconductor N (3) are sequentially laminated on a conductive substrate (1). The a-5iC photoconductive layer (2) has a function of charge generation, and the other organic photoconductive layer (3) has a function of charge transport.

In the present invention, when the element ratio of the a-3iC photoconductive layer (2) and the content of Group IIIa elements of the periodic table (hereinafter abbreviated as Group IIIa elements) are set within the following ranges,
The feature is that the photosensitivity of this N(2) itself can be significantly increased.

Composition formula: [Si1-xc x) +□A.

(However, A is hydrogen or halogen) Q < x < 0.5, preferably 0.01 < x
< 0.40.2 < V < 0.5, preferably 0
．． 25 < y < 0.45 Group IIIa element content 1
: 1 to 1,000ppm When the X value is 0.5 or more, the photoconductivity becomes significantly low, and the excitation function of photocarriers deteriorates.

When the y value is 0.2 or less, the dark conductivity tends to increase, and the photoconductivity tends to decrease, so that the desired photoconductivity cannot be obtained and the y value is 0.2 or less. If it is 5 or more, the adhesion to the substrate deteriorates and peeling becomes easy.

In addition, the Group IIIa element content is expressed by the average value per entire a-5iC layer, and the average content is 1
If it is less than 1,000 ppm, no improvement in photosensitivity is observed, whereas if it exceeds 1,000 ppm, the dark conductivity becomes significantly large, and the clouding rate of the photoconductivity relative to the dark conductivity is small. Therefore, the desired photosensitivity cannot be obtained.

In addition, when used as a positive charging photoreceptor, the above 1[1a
The group element content may be set within a range of 1100 pp or less. That is, within this range, the mobility of electrons among the excited carriers will be high, so that the positive charges on the surface of the photoreceptor can be smoothly neutralized, and as a result, the photosensitivity will be increased.

When a group IIIa element is contained in the a-SiC photoconductive layer (2), the doping distribution may be uniform or non-uniform over the layer thickness direction. In the case of non-uniform doping, there may be a layer region in a part of this layer (2) that does not contain group IIIa elements;
The average content of group IIIa elements in the entire a-SiC layer consisting of both the layer region containing group Ia elements and the layer region not containing group I[[[[a group elements] is 1 to 1 + 000 ppm.
Must be.

Group IIIa elements include B, AI, Ga, and In, and these eight elements have excellent covalent bonding properties and can sensitively change semiconductor properties, and in addition, provide excellent charging ability and photosensitivity. It is desirable in that sense.

Furthermore, the a-SiC photoconductive layer (2) contains hydrogen (H) element and halogen element for terminating dangling bonds, but among these elements, H element is easily incorporated into the terminating portion. This is desirable in that the local level density in the band gap is reduced.

The thickness of the a-SiC photoconductive layer (2) is 0.05 to 5 μm
, is preferably set within the range of 0.1 to 3 μm; within this range, high photosensitivity can be obtained and the residual potential will be low.

The substrate (1) includes a metal conductor such as copper, brass, SOS, or AI, or an insulator such as glass or ceramics coated with a conductive thin film on the surface. This is advantageous in terms of adhesion to the a-SiC layer.

Further, the electrophotographic photoreceptor of the present invention has an organic photoconductor layer (3).
It can be set to a negatively charged type or a positively charged type by selecting the material. That is, in the case of a negatively charged electrophotographic photoreceptor, an electron-donating compound is selected for the organic optical semiconductor layer (3);
In the case of a positively charged electrophotographic photoreceptor, an organic optical semiconductor layer (3
) is selected as an electron-withdrawing compound.

Electron-donating compounds include poly-N-
Examples include vinylcarbazole, polyvinylpyrene, polyvinylanthracene, pyrene-formaldehyde condensation polymer, and low molecular weight ones such as oxadiazole,
These include oxazole, pyrazoline, triphenylmethane, hydrazone, triarylamine, N-phenylcarbazole, and stilbene, and these low-molecular substances include polycarbonate, polyester, methacrylic resin, polyamide, acrylic epoxy, polyethylene, phenol, polyurethane, and butyral resin. It is used dispersed in a binder such as polyvinyl acetate or urea resin.

Electron-withdrawing compounds include 2.4.7-1-linitrofluorenone.

Next, a method for manufacturing the electrophotographic photoreceptor of the present invention will be described.

To form the a-SiC layer, there are thin film forming methods such as glow discharge decomposition method, ion blating method, reactive sputtering method, vacuum evaporation method, and CVO method.

When using the glow discharge decomposition method, Si element-containing gas and C
A film is formed by combining element-containing gases and plasma decomposing the mixed gas. This Si element-containing gas contains SiH4+
Si2H6, Si:lHa, 5iFa-+5iC14+
5iHC1:+, etc., and C element-containing gases include CH4, CzH4, CzH2+C3H1l, etc.
Among these, CzHz is preferable because it allows high-speed film formation.

The glow discharge decomposition device used in this example will be explained with reference to FIG.

In the figure, the first tank (4), second tank (5), third tank (6), and fourth tank (7) are filled with SiH, C, and
tHt, BiI3 and H2 are sealed, and these gases are passed through the corresponding first regulating valve (8), second regulating valve (9),
It is released by opening the third regulating valve (10) and the fourth regulating valve (11). The flow rate of the released gas is determined by the mass flow controller (12) (13) (14).
(15), each gas is mixed and sent to the main pipe (16). Note that (17) and (18) are stop valves.

The gas flowing through the main pipe (16) flows into the reaction tube (19), which is equipped with a capacitively coupled discharge electrode (20) and a cylindrical film-forming substrate. (21)
is placed on the substrate support (22), and
is rotationally driven by a motor (23), and the substrate (21) rotates accordingly. Then, power 50 is applied to the electrode (20).
A high frequency power of W to 3 KW and a frequency of 1 to 50 MHz is applied, and the substrate (21) is heated to a temperature of about 200 to 400°C, preferably about 200 to 350°C, by a suitable heating means. In addition, the reaction tube (19) is equipped with a rotary pump (24).
) and a diffusion pump (25), thereby maintaining the necessary vacuum state (gas pressure during discharge of 0.01 to 2.0 Torr) during film formation by glow discharge.

The substrate (2
When forming an a-SiC layer on 1), the first regulating valve (
8), open the second regulating valve (9), the third BM regulating valve (10), and the fourth regulating valve (11) to 5i14. CzH
z, BJ6, and Ih gases are released, and the amount of the released gases is controlled by a mass flow controller (12) (13) (14) (1
5), each gas is mixed and sent to the main pipe (16
) into the reaction tube (19). Then, by setting the vacuum inside the reaction tube, the substrate temperature, and the high-frequency power applied to the electrodes to predetermined conditions, a glow discharge occurs, and as the gas decomposes, the a-5iC film containing B element is rapidly spread onto the substrate. is formed.

After the a-SiC layer is formed by the thin film forming method as described above, an organic optical semiconductor layer is then formed.

The organic optical semiconductor layer is formed by a dip coating method or a coating method. That is, in the former method, the photosensitive material is immersed in a coating liquid dispersed in a solvent, then pulled up at a constant speed, and then subjected to natural drying and heat aging (approximately 150°C, approximately 1 hour). According to the latter coating method, a photosensitive material dispersed in a solvent is applied using a coater, and then hot air drying is performed.

〔Example〕

(Example 1) Using the glow discharge decomposition device shown in Figure 2, SiH4 gas is
Hydrogen diluted B2H-gas for 90 s at a flow rate of 00 sec
H2 gas at a flow rate of ecm and a flow rate of 270sec,
Then, the flow rate of the czt+z gas was changed, the gas pressure was set to 0.67 orr, the high frequency power was set to 150 W, and the substrate temperature was set to 250° C., and an a-5iC film (film size: 1 μm) was formed by glow discharge.

In this way, the carbon content ratio of the a-SiC film was changed, and the amount of carbon in the film was measured by the XMA method.
Further, when the photoconductivity and dark conductivity were measured, the results shown in FIG. 3 were obtained. In addition, when the B element content contained in each a-5iC film was measured using a secondary ion mass spectrometer, it was found to be approximately 15 ppm in each case.

The horizontal axis in FIG. 3 is the carbon content ratio, ie, 5iI-.

It is the y value of C8, the vertical axis represents the conductivity, the circle mark is a plot of photoconductivity for light with an exposure wavelength of 550 nm (light intensity of 50 μW/cm), the mark is a plot of dark conductivity, and , a, b are respective characteristic curves.

When the hydrogen content of each of the above a-SiC films was determined by infrared absorption measurement, the results shown in FIG. 4 were obtained.

In the figure, the horizontal axis is the x value of 5il-1ICX, and the vertical axis is the hydrogen content, that is, [5iI-8CX) +-y y of Hy
The O mark is a plot of the amount of hydrogen bonded to the Si atom, the * mark is the plot of the amount of hydrogen bonded to the C atom, and c and d are the respective characteristic curves.

As is clear from FIG. 4, the a-SiC films of this example all have y values within the range of 0.3 to 0.4.

Also, as is clear from Figure 3, the carbon content ratio X is 0.
It can be seen that within the range of < x < 0.5, high photoconductivity was obtained and the ratio of photoconductivity to dark conductivity became significantly large, indicating that excellent photosensitivity was obtained.

(Example 2) Next, in this example, 5il14 gas is
CtH2 gas was introduced at a flow rate of 20 sec, hydrogen diluted B2H6 gas was introduced at a flow rate of 90 sec, H2 gas was introduced at a flow rate of θ~1000 sccIIl, and the high frequency power was 50~300 W.

The gas pressure was set at 0.3 to 1.2 Torr, and an a-5iC film (film size: 1 μm) was formed by glow discharge.

In this way, carbon content ratio x was set to 0.3, and various a-SiC films with varying hydrogen content y were formed, and the photoconductivity and dark conductivity of each film were measured. The results shown in Figure 5 were obtained. Furthermore, a-
When the B element content of the 3iC film was measured, it was approximately 1
It was 5 ppm.

The horizontal axis in Figure 5 is the hydrogen content, i.e. (SiO,?CG,
3) +-y is the y value of Hy, the vertical axis represents the conductivity, and the 0 mark is the exposure wavelength of 550 nm (light amount 50 p W
/cm”) is a plot of photoconductivity for light,
The marks are plots of dark conductivity, and e and f are respective characteristic curves.

As is clear from Figure 5, when the y value exceeds 0.2,
It can be seen that high photoconductivity as well as low dark conductivity are obtained.

(Example 3) In this example, hydrogen dilution B is performed using 5i14 gas at a flow rate of 200 seconds and CzHz gas at a flow rate of 20 seconds.
Z II & gas (concentration 0.2χ or 40ppm)
H2 gas at a flow rate of 5 to 500 sec for 200 sec
cm, and high frequency power was applied at 150 cm.
The gas pressure was set to 0.6 Torr, and B
An element-containing a-3iC film (film thickness: 1 μm) was formed.

In this way, various a-5iC films were formed with the carbon content ratio X set to 0.3 and the hydrogen content set to 0.35, and the B element content varied, and the photoconductivity and When the dark conductivity was measured, the results shown in FIG. 6 were obtained.

In this example, in place of the above B t 11 and gas, P
Various a-5iC films with varying P element contents were formed by introducing H2 gas, and the measurement results were also obtained.

In the figure, the horizontal axis represents the B element content (or P element content), the vertical axis represents the conductivity, and the circle indicates the exposure wavelength of 550 nm.
This is a plot of photoconductivity for light with a light intensity of 50 μW/cm”, and the symbol ・ is a plot of dark conductivity, and g
, h are characteristic curves.

As is clear from Figure 6, element B is 1-1.00011
It can be seen that when 111m is contained, the ratio of photoconductivity to dark conductivity becomes significantly large. Furthermore, for P element, the increase in photoconductivity and dark conductivity was even more remarkable.

Thus, it was confirmed that the a-5iC film had valence electrons controlled by the B element and the P element, and thus had excellent film quality as a semiconductor.

(Example 4) In this example, various a-
A 5iC photoconductive layer (sample NaA-1-A-5) was formed. Then, when the carbon element content ratio X and B element content of each were measured, the results shown in Table 1 were obtained.

[Margin below]

Next, when the spectral sensitivity characteristics of samples NaA-1, A-2, A-4, and A-5 were measured, the results shown in FIG. 7 were obtained. Furthermore, when the hydrogen content (y value) of each sample was measured, all were within the range of 0.2 < y < 0.4.

In Fig. 7, the horizontal axis is the wavelength, the vertical axis is the conductivity, and the O mark, △ mark, V mark, and X mark are the sample l1kL, respectively.
These are measurement plots of A-1, A-2, ^-4, and A-5.

As is clear from the figure, sample disease ^-1, A according to the present invention
It can be seen that high photoconductivity was obtained for Samples -2 and A-4.

(Example 5) In this example, various a
A -3iC photoconductive layer (sample NIILB-1-B-5') was formed. Then, when the C element content ratio (X4M) and B element content of each were measured, the results shown in Table 2 were obtained.

[Margin below]

Next, when the spectral sensitivity characteristics of samples NIIB-1, B-2, B-4, and B-5 were measured, the results shown in FIG. 8 were obtained. Furthermore, when the hydrogen content (y value) of each sample was measured, it was within the range of 0.2 < V < 0.4.

In FIG. 8, the horizontal axis is the wavelength, the vertical axis is the conductivity, and the O, Δ, and X marks are for the sample NctB-
1, B-2, B-4, and B-5 measurement plots.

As is clear from the figure, it can be seen that the sample according to the present invention had high photoconductivity.

(Example 6) Next, the present inventors used 0114 gas instead of C and H2 gas, and formed various a-5iC photoconductive layers (samples KC-1 to C-5) under the film forming conditions shown in Table 3. Formed. Then, the C element content ratio (X value), hydrogen content (y value), and B element content of each sample were measured, and the results shown in Table 3 were obtained.

[Margin below]

sample! When the spectral sensitivity characteristics of 1hc-1, C-2, and C-3 were measured, the results shown in FIG. 9 were obtained.

In the figure, the horizontal axis is the wavelength, the vertical axis is the conductivity, and the marks ○, Δ, and samples 11hC-1 and C~2, respectively.
．． It is a measurement plot of C-3.

As is clear from the figure, high conductivity was not obtained in any of the samples.

(Example 7) Next, the present inventors formed two types of a-SiC photoconductive layers as shown in Table 4 on an AI-made electrically conductive substrate, and added an organic layer on each layer as shown below. Optical semiconductor layer (thickness 15μm)
were laminated using a coating method.

[Method for applying organic optical semiconductor layer]

Hydrazone was dissolved in a 1,4-dioxane solvent, and polyester resin (Refsan-LS2-11) was added in the same weight as the hydrazone, followed by ultrasonic dispersion for 4δ minutes. Then, it was coated on both a-SiC photoconductive layers using a bar coater, and then dried with hot air.

In this way, two types of negatively charged electrophotographic photoreceptors were manufactured (
photoreceptor A, B).

[Margin below]

When the dark and light attenuation characteristics of photoreceptor A were measured, the results as shown in Figure 10 were obtained, and when the spectral sensitivity characteristics were measured, the results as shown in Figure 11 were obtained. Ta.

According to FIG. 10, the horizontal axis is the decay time (seconds), the vertical axis is the surface potential (volts), and i is the dark decay curve, and i-1, i-2, and i-3 are respectively Exposure wavelength is 400
The optical attenuation curves are shown for 450 nm, 450 nm, and 550 nm.

In addition, in FIG. 11, the horizontal axis is the wavelength, and the vertical axis is the wavelength.

The axis is the photosensitivity, and the circle mark is the measurement of the photoreceptor 4
This is a fixed plot. In addition, as a comparative example, sample C-1@
An a-SiC photoconductive layer was used, and an organic photoconductor layer was formed on this layer by the same method as in this example, to produce an electrophotographic photoreceptor. The measurement plot of this photoreceptor is indicated by Δ.

The measurement conditions were as follows: Charging was carried out using a corona charger applying a voltage of +6 KV, and the light intensity at each wavelength was 0.15 μl/cm'' for exposure. Measured using a meter.

As is clear from the results shown in FIG. 11, it can be seen that the photoreceptor A of the present invention had superior photosensitivity compared to the comparative example.

(Example 8) As a comparative example, the present inventors formed an a-SiC photoconductive layer as shown in Table 5 on an electrically conductive substrate made of AI, and on top of that layer, in the same manner as in (Example 7). Organic optical semiconductor layer (thickness 15μ
m) was laminated by a coating method, thus producing a negatively charged electrophotographic photoreceptor (photoreceptor C).

[Margin below]

When the dark and light attenuation characteristics of this photoreceptor C were measured, it was confirmed that its surface potential tended to rise slightly compared to that of the photoreceptor. Further, when the spectral sensitivity characteristics were measured, the results shown in FIG. 12 were obtained.

As is clear from FIGS. 11 and 12, it can be seen that photoreceptor A has improved photosensitivity compared to photoreceptor C.

The present inventors also measured the dark and light attenuation characteristics and spectral sensitivity characteristics of photoreceptor B, and confirmed that similarly excellent photosensitivity characteristics were obtained for both photoreceptors.

(Example 9) Next, the present inventors formed five types of a-3iC photoconductive layers according to the film formation conditions shown in Table 6, and then on each layer (Example 7
) An organic photoconductor layer having a thickness of 15 μm was coated and formed by the method shown in (a) to prepare a negatively charged photoreceptor D-11. still,
In each photoreceptor, the carbon element content ratio X was 0.25, and the hydrogen content y was within the range of 0.2 to 0.4.

[Margin below]

The B element content and photosensitivity of these electrophotographic photoreceptors,
When the surface potential and residual potential were measured, the results shown in Table 7 were obtained.

The photosensitivity in the same table is classified into three levels, ◎, ○, and Δ, based on relative evaluation.■ marks indicate the best photosensitivity, and O marks indicate slightly higher photosensitivity. is obtained, and the mark Δ is a case where the photosensitivity is slightly inferior to the others.

Characteristic evaluation of surface potential is also divided into three stages: ◎ mark, ○ mark, and Δ mark. ◎ mark is the case where the highest surface potential is obtained;
The ○ mark indicates a case where a somewhat high surface potential was obtained, and the Δ mark indicates a case where a higher surface potential was not observed compared to others.

In addition, the residual potential is also evaluated relative to three levels.
The ■ mark is the case where the residual potential is the smallest, the ○ mark is the case where the decrease in the residual potential is somewhat suppressed, and the Δ mark is the case where the reduction in the residual potential is not observed compared to the others. be.

[Margin below]

Table 7 As is clear from Table 7, photoreceptor D-G has excellent photosensitivity and a reduction in residual potential.
Even higher photosensitivity was observed for photoreceptors E, P, and G. However, it can be seen that the photoreceptor 11 has not been improved in any of the characteristics of photosensitivity, surface potential, and residual potential.

〔Effect of the invention〕

As described above, according to the present invention, the amount of carbon, the amount of the dangling bond terminating element, and the group IIIa element content of the a-SiC photoconductive layer are set within predetermined ranges, and the a-3iC photoconductive layer is By combining the organic photoconductor layer and the organic photosemiconductor layer, an electrophotographic photoreceptor with excellent photosensitivity could be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the layer structure of the electrophotographic photoreceptor of the present invention, FIG. 2 is a schematic diagram of a glow discharge decomposition device used in Examples, and FIG. 3 is a line showing the relationship between carbon content ratio and electrical conductivity. Figure 4 is a diagram showing the relationship between carbon content ratio and hydrogen content, Figure 5 is a diagram showing the relationship between hydrogen content and electrical conductivity, and Figure 6 is a diagram showing the relationship between group IIIa elements of the periodic table. or Chapter V
FIG. 2 is a diagram showing the relationship between group a element content and electrical conductivity. Further, FIGS. 7, 8, and 9 are diagrams representing conductivity, FIG. 10 is a diagram representing surface potential, and FIGS. 11 and 12 are diagrams representing photosensitivity. 1... Conductive substrate 2... Amorphous silicon carbide photoconductive layer 3... Organic optical semiconductor layer Ratio”≠(X discussion) Q O, + 0.2 0.3 0.4
0.5 Suito/? Waste + (Biji 2 Figure 7 U Ryo A Cnr-) "Ko Awe (Wayy +) Ji Tomonaga (Hari

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor in which an amorphous silicon carbide photoconductive layer and an organic photoconductive layer are sequentially laminated on a conductive substrate, wherein the constituent elements of the amorphous silicon carbide photoconductive layer are Si element, C element, and hydrogen. or halogen, hydrogen or halogen is expressed as element A, and the element ratio of the layer is represented by the composition formula [Si_1_-_xC_x]_1_-_
When expressed as yA_y, x and y are each 0<x<
0.5, 0.2<y<0.5, and the layer further contains a Group IIIa element of the periodic table in a range of 1 to 1,000 ppm. Photographic photoreceptor.