JPS6026345A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve the photosensitivity by forming a charge transferring layer having a lower dielectric constant than the photosensitive layer under the photosensitive layer. CONSTITUTION:A charge transferring layer 112 and a photosensitive layer 115 of amorphous silicon or silicon-germanium contg. H are formed on an electrically conductive substrate 111. The layer 112 consists of a silicon compound contg. one or more among O, N and C and H or H and F such as amorphous silicon carbide and 1-100ppm B, Al, Ga, In or other IIIb group element in the periodic table in case of positive chargeability or 1-500ppm N, P, As, Sb or other Vb group element in case of negative chargeability. The layer 112 has a lower dielectric constant than the layer 115. An electrophotographic sensitive body having sensitivity to light of 350-950nm and useful for a laser printer, an LED printer, a copying machine or the like is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor having photosensitivity to light of 350 nm to 950 nm.

An object of the present invention is to provide an electrophotographic photoreceptor with high photosensitivity.

In recent years, amorphous silicon containing at least hydrogen (hereinafter abbreviated as a-8i) or amorphous silicon germanium containing at least hydrogen (hereinafter abbreviated as a-EIiGe) is used. Electrophotographic photoreceptor (
Hereinafter, it will be collectively referred to as a-8i.

It is abbreviated as a-8iGe electrophotographic photoreceptor. ) is being actively researched. The main a-8i is shown in Fig. 1 (a) to (θ).

a-8iGet child photographic exposure. 11°21
．． 31,41.51 is boron (hereinafter abbreviated as B) from 1 to
A-day 1 layer, 2 layers containing 100 ppm and having a thickness of 1 μm or more
5,52f'lB from 100 ppm to 500 ppm
A-8i pigeon with an included thickness of 0.05 to a5 μm, 63°46
．． 55 is the ratio of germanium (hereinafter abbreviated as Gθ) to silicon (S:t, ) (Ge/Si) 7>i 10
-11 to 9 composition ratio, thickness α5 to 10 μm + cDa -8
i: Go group 35.541fJB with 1~1100pp impregnated thickness so, 1~5 μm a-8i noso, 15,25
, 55, 45° 55 is a conductive substrate. Father is a-Si
The layer contains 10% or less of nitrogen, oxygen, and carbon.

A feature of each layer is that the dielectric constant is 11 or more.

This electrophotographic photoreceptor has the advantages of higher hardness, shock resistance, lower residual potential, and non-pollution than Se-based or OdS yarn electrophotographic photoreceptors. There is. On the other hand, when used for electrophotographic photoreceptors with high photosensitivity used in sieving speed printers such as laser printers and LED printers, and copying machines for business owners, the a-8i and a-8i
In the Gθ electrophotographic photoreceptor, the film thickness must be increased, and the a-8i, a-8i GeO production speed is slow.
15 .mu.m/hr), and this requires manufacturing time, which is the biggest factor hindering price reduction.

The present invention eliminates such drawbacks, and the conventional A-8i
, an electrophotographic photoreceptor with the same thickness and higher photosensitivity as an a-SiGe electrophotographic photoreceptor; This provides an electrophotographic photoreceptor in which the same photosensitivity can be obtained with a film 4 that is thinner than the film 4.

Before explaining the present invention, the function and thickness of the photoreceptor will be briefly explained.

As shown in FIG. 2, while the surface of the photosensitive layer is positively charged by a corona discharger, it is irradiated with light having photons having an energy (hv) larger than the forbidden band width of photosensitive I-. By this light
Electron-hole pairs are generated near the surface of the photosensitive member 7ii 101, that is, within the absorption region.

The electrons reach the surface of the photosensitive layer and cancel the positive band charge.

On the other hand, holes pass through the photosensitive layer 101 and the aluminum support 10
2, a current apparently flows through the window optical layer, the electrical charge disappears, and optical information, that is, an electrostatic image corresponding to an image is formed on the photoreceptor. Furthermore, even when negatively charged, the principle is the same as the above explanation except that the movements of electrons and holes generated by light are reversed.

At this time, the amount of charge Q per unit area on the photoreceptor before light irradiation is given by Become. Father, the photoconductor capacitance is 0, the relative dielectric constant of the photoconductor is εr,
If the thickness of the photoreceptor is d, then 0=ε0·εr/a . . .■ However, C0 is the dielectric constant in vacuum.

becomes. From ■ and ■, Q=εO・εr−ve/d ・・・・・・■Also, since the light absorbed by the photoreceptor Vζ forms one electron/hole pair per photon, to make it easier to understand Considering monochromatic light that is sufficiently absorbed by the photoreceptor, if the energy of the monochromatic light is E, the number N of electron-hole pairs generated is N=B ・(1-R)/(h ・ν)... ...■ However, R is the reflectance of the photoreceptor, 1-R is the absorption rate, xhH
The blank constant ν is the frequency of light.

If the doubly charged charge on the electron-hole pair generated by light is canceled out with a quantum efficiency of 4, then the amount of canceled charge per unit area is: 'usQ = ηNθ...
...■ However, θ is the unit charge amount, η×1. Also, the change in surface potential due to the irradiated light ΔV
l+ is the surface potential after light irradiation and the amount of charged charge per unit of light is θ' and Q'', respectively, then ΔV=Vs-■a/ ■From the formula = (Q-Q'')・d/ (C0・ε・)=Q′
・d/(εQ, εr) From formula 00 = yl-e-d>-C1-G/Ch-ν・εO・εr
)......■.

■To summarize the physical meaning of the equation: 1. When light energy E5 quantum efficiency η and reflectance R are constant, to increase the change in surface potential, that is, to increase photosensitivity, increase the film thickness. Either the dielectric constant should be reduced (that is, the capacitance of the photoreceptor should be reduced).

2. When film thickness a, scavenging efficiency η, and reflectance R are kept constant,
In order to increase the amount of change in surface potential, either increase the light energy E or decrease the photoreceptor capacity.

Originally, materials other than the film thickness of formula (■), for example, a -8i, a
Rounding of the physical property values, which are determined once -81Ge is determined, and K, which greatly improves photosensitivity, cannot be achieved except by increasing the film thickness. Although it is possible to bring the quantum efficiency close to 1, for example, in the case of an a-ElillE photoreceptor, η = 0.8.
~1.0, and it is impossible to have a wide range of photosensitivity.

The present invention is based on the fact that a-8i and a-8iGe sufficiently absorb light used in printers, copiers, etc. at a thickness of 1 to 5 μm or less, so that light can be injected from 1 to 5 μm from the surface of the photoreceptor to the conductive substrate. Paying attention to the fact that carriers (photocarriers) are only transported within the photoreceptor by the electric field, the relative dielectric constants of the photoreceptor parts other than the light absorption part are a-8i and a-8i.
The present invention is explained in detail with numerical examples, in which the photoreceptor'g1 is reduced and the photosensitivity is made the same by replacing the charge transport layer with a charge transport layer that is smaller than ()θ and has sufficient photocarrier transport ability. explain. Seven points for simplification Consider the single-layer photoreceptor shown in FIG. 1(a) as a conventional electrophotographic photoreceptor, and the two-layer photoreceptor shown in FIG. 3(a) as the electrophotographic photoreceptor of the present invention. 115 is an a-8i layer, and 112 is an amorphous silicon carbide layer containing hydrogen and doped with boron to maintain transport ability.

The capacitance of the a-Si single layer is Qa, the capacitance in the case of the two-way structure of the present invention is Qa, and the 4th charged position is v8゜'ya, respectively.
Letting the charges required for each be Q- and Qa, Q s = Oa V-... (1)'Q, a=
= o a V a , = f21' When the charging potential is the same, that is, vII = vd, the ratio of both charges is Qd/Q""' 0610n, 13)/.

In the photoreceptor shown in FIG. 3(a), the thickness of the a-81 photosensitive layer 115 is a, and the thickness of the SiO layer 112 is d2.The capacitance per unit area is ε 0... ...(4)' Cd = C0・, C1, C2 are the permittivity of vacuum, a-8t, respectively
These are the dielectric constant of the photosensitive layer and the dielectric constant of the SiO charge transport layer.

On the other hand, let the thickness of the photoconductor with only the a-81 layer be aO, and the same thickness as the photoconductor with the two-layer structure do = (11+dt(3)')
, (4)', C5)' to ε1%12, ε! For example, dl-5μm, l@=15
/jm, then Q 117 Q s # 0.65 That is, compared to a single layer, the 2)-structure requires about 65% of the amount of charge to obtain the same 4-position charge with the same thickness.

Therefore, the number of photons required to annihilate this charge is also 6.
It can be seen that 5% is sufficient and the sensitivity is good.

The charge transport layer according to the present invention is an amorphous silicon carbide containing hydrogen or hydrogen and fluorine (a-8ix01-x:
α1≦xα9), amorphous silicon (a-stXN
+-X: 0.1≦x<0.9), amorphous silicon oxide (a-8iz01-2: 0.1≦z<0.5), amorphous silicon carbonitride (a-8ixOyN1-' z-y:
0.1<x<0.9, 0.1≦y [17], amorphous silicon oxycarbide (a-8ixOyO1-z-y: α
1≦x<0.90.1≦y≦0,7, amorphous silicon oxynitride (a-day 1xNyO1-X-y: α1≦X≦0
．． 9,0.1≦y≦L1.7), amorphous silicon oxycarbonitride (a-81xoyNz01-X-y-Z: α1≦
x<0.8, 0.1≦y≦0.5. L], 1≦2≦0.
5), and in order to have charge transport ability, the band! When the polarity is positive, 1 to 1000 ppm of boron, aluminum, gallium, indium, etc. from Group JIB of the periodic table,
In the case of a negative electrode, 1 to 500 ppm of nitrogen, phosphorus, arsenic, antimony, etc. from group 1b of the periodic table is mixed. The manufacturing method is plasma OV:O method + sputtering method, ion beam sputtering method.

It is formed by an OVD method or the like. Figure 3 (a) to (f)
K shows the structure of an electrophotographic photoreceptor according to the present invention. 111゜121.131, 141, 151, 161 are conductive substrates 112, 122, 132゜142.1 made of aluminum etc.
52,162 is a charge transport layer according to the present invention, 123,14
3,163 is a 0.1-1 μm thick a-8i layer containing 100-500 ppm boron, 134,144,154
, 164 is a- with a Ge/st ratio of 10-3 to 9.
+31Gθ layer, 115 125 135 145 15
5165 is 1-100 pp) a-8i containing n boron
It is a layer.

As an example, amorphous silicon carbide (A-8
1xO1-x), and the structures shown in Figure 5(a) to (0
) The electrophotographic photoreceptor having the structure will be described below.

First, the reduction in dielectric constant and the change in transport capacity, which are the premise described above, will be explained.

FIG. 4 shows the change in dielectric constant of a-8ixO1-z with respect to the carbon content. A decrease in relative dielectric constant is observed as the amount of carbon increases.

Figure 5 shows a-8ixC1- of the same film thickness with respect to the amount of boron.
The relative surface of x indicates a change in position. By adding the amount of boron, the charge transport ability changes and a decrease in surface potential can be confirmed.

Example 1 In an electrophotographic photoreceptor of the present invention having the structure shown in FIG. 6(a), the total film thickness was set to 20 μm, and a-8ixO1-X was used.
The relative surface change obtained by dividing the change in surface potential when the film thickness of 112 is changed from 5 to 17.5 μm by the surface change of the a-Eli single j- photoreceptor with a film thickness of 20 μm and a -S i
The relationship between the film thickness of x O1-x is shown in Figure 6 (light is 6
It is a monochromatic light of 50 nm and the energy is constant. ).

a is the relative surface potential change of the a-8i monolayer. As is clear from the figure, as the number of a-8ix (,1-1) layers with a small dielectric constant increases, the change in surface potential increases with the same light energy. m w /- A-8i layer when irradiated is 5 μm.

a Si x O+ -X 15 μm photoreceptor a-
8ixO1-.

Changes in the boron content and residual potential are shown. It can be seen that the charge transport ability of B i x O1X was increased by mixing boron.

Actual example 2, the total film thickness of the structure shown in FIG. 3(C) of the present invention is 10
μm, a-8i layer (135) 1 μm, a-EliGe
'(154) 1.5μm, a-8ixO1x(13
2) 7 μm electrophotographic photoreceptor and conventional structure shown in FIG. 1(d), total film thickness 10 μm, a-day 1 layer (44) 1 μm 1a
-8iGe layer (43) 1.5 μm, a-8i layer (41
) 7 μm electrophotographic photoreceptor with a light wavelength of 850 μm to 65 μm
FIG. 8 shows the change in surface potential when changing between 0 μm. FIG. 8 shows the wavelength and surface potential change (a) of the conventional electrophotographic photoreceptor, normalized to 1.

Obviously, the uninvented electrophotographic photoreceptor (b) is photosensitive.
Improvement is visible.

As described above, according to the embodiments, the photosensitivity can be improved by providing a charge transport layer having a small dielectric constant and sufficient charge transport ability, which is useful.

Also, similar results were obtained for all structures in Figure 3, and 7'CL
Similar results can be obtained with aluminum, gallium, indium, or phosphorus, arsenic, and antimony in the case of negative electrode charging. In addition, amorphous silicon nitride, amorphous silicon oxide, amorphous silicon carbonitride, amorphous silicon oxide carbide, amorphous silicon oxide, amorphous silicon containing hydrogen or hydrogen and fluorine as a charge transport layer Similar results were obtained when oxidized silicon carbide was mixed with Group MB of the periodic table for the positive electrode and Group Vb of the periodic table for the negative electrode.

According to the present invention, it can be usefully used as an electrophotographic photoreceptor for laser printers, high-medium speed printers such as LffiD printers, and copying machines.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(e) are conventional views of a conventional electrophotographic photoreceptor. FIG. 2 is a model diagram of an electrophotographic photoreceptor. FIGS. 6(a) to 6(f) σ are structural diagrams of the electrophotographic photoreceptor of the present invention. FIG. 4 is a diagram showing the relationship between the amount of carbon in a-8i x O+ -X and the lucent rate. FIG. 5 is a diagram showing the relationship between the amount of boron in a S l go + -X and the surface concentration. Diagram M6 is a diagram showing the relationship between the thickness of a-BixOl-X and the change in surface potential. FIG. 7 shows the relationship between the amount of boron in a-8ixO1y and the residual potential. FIG. 8 is a diagram showing the relationship between the light source length and the surface potential change. 101... Photoreceptor 1- 102... Conductive substrate 112, 122, 132... Charge transport layer and above Applied Human Body System Company Suwa Seikodai (i) (1)) (Q) (d) Ce) Chapter Figure 1 Figure 4 Figure 5 Figure 6 Figure 7

Claims (3)

[Claims] (1) In an electrophotographic photoreceptor using hydrogen-containing amorphous silicon or amorphous silicon germanium as a photoreceptor layer, a charge transport layer is not formed under the photoreceptor layer. An electrophotographic photoreceptor characterized in that the relative dielectric constant of the charge transport layer is smaller than the relative dielectric constant of the photoreceptor layer. (2) The charge transport layer is formed by containing at least one of oxygen, nitrogen, and carbon, and is a silicon compound containing hydrogen or hydrogen and fluorine. The electrophotographic photoreceptor according to scope 1. (3) the 'charge transport layer μ is formed by containing at least one of oxygen, a phoneme, and carbon, and is a silicon compound containing hydrogen or hydrogen and fluorine;
When the photoreceptor layer is positively charged, the silicon compound is mixed with Group MB of the periodic table, and when the photoreceptor layer is negatively charged, the silicon compound is mixed with Group VB of the periodic table. An electrophotographic photoreceptor according to claim 1, characterized in that: