JPS63300576A - Color sensor - Google Patents

Abstract

PURPOSE:To simplify the manufacture of a color sensor and to improve the stability of the operation by inserting first, second organic colorant layers containing specific skeleton between light transmissible first and second conductive materials and further a light transmissible third conductive material between the first and second organic colorant layers. CONSTITUTION:A first organic colorant layer 2 inserted between first and second conductive materials 1 and 5 contains at least tetra (4-pyridyl) porphyrin skeleton. A second organic colorant layer 4 contains at least phthalocyanine skeleton. Further, the working functions of the materials 1, 5 are larger than that of a transmissible third conductive material 3 inserted between first and second organic colorant layers 2 and 4. The first and second layers respectively have light absorption peaks at short and long wavelength sides, and further have N-and P-type semiconductor properties. Both have highly efficient photoelectric converting function, and an anisotropic junction is formed at the side in which the lights of the colorant layers are incident. A bias can be eliminated, and substantially all visible light wavelength bands can be identified.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a color sensor, and in particular, the present invention relates to a color sensor, and in particular, it creates two photodiodes with different sensitivities to light wavelengths, and calculates the optical output current of each photodiode using an electric circuit. This invention relates to a color sensor that can obtain an output corresponding to the wavelength of light through signal processing.

[Conventional technology]

Conventionally, such a color sensor has, for example, one in which semiconductors are arranged as shown in Figure 10 (Chuji Suzuki: Electronics, February 1981 issue, 181-
184 pages).

Figure 10 is a structural diagram (a) showing this semiconductor color sensor.
, and an equivalent circuit diagram (b). In this sensor, p
An n-type layer 55. is formed on the silicon substrate 54. Furthermore, p-type layer 5
6 and electrodes 51.52. and 53 are provided.

First, the short wavelength light is absorbed by the upper pn junction, and the 0th-order long wavelength light is absorbed by the lower np junction, resulting in the photocurrent of photodiode PD8 shown in Fig.
The photocurrent becomes t. As a result, the short circuit current of the two photodiodes is 1 +SC, I as shown in (b).
, sc is obtained, and this ratio 1, sc/I, sc
The value of corresponds to the wavelength of the incident light. Furthermore, as the four p-type or n-type soils used here, inorganic semiconductors such as single crystal silicon, amorphous silicon, CdS, and PbS have been used.

On the other hand, color sensors using organic semiconductor materials have also been proposed (K, Kudou and T, Mori Izumi (K, Kud).
o and T, Moriizumi); Applied Physics Letters, Volume 39 (8) (Ap
pl, Phys.

Lett,,39. (8)) 609 pages (1981
)) This is made by providing a zinc oxide film on an ITO substrate, providing an organic film of merocyanine dye and rhodamine B on it, and further providing an aluminum electrode. The current that flows through the element when a voltage of 1 is applied depends on the wavelength of the irradiated light.

However, all of the conventional color sensors described above have drawbacks. First, because the former uses an inorganic semiconductor as a material, the absorption wavelength range of light is broad;
In many cases, a filter must be used in the sensor, and the process for manufacturing the sensor with inorganic semiconductors is complicated and expensive. In contrast, sensors using organic materials are cheaper to manufacture, but the latter color sensor currently being proposed requires the application of a bias to the sensor, and the photovoltaic current is the most delicate. Since the sensor is used in a region that changes in temperature, there is a problem with the stability of the sensor's operation, and the wavelength range that the sensor can identify is from 480 nm (maximum absorption wavelength of rhodamine B) to 580 nm (maximum absorption wavelength of merocyanine dye). Therefore, it was insufficient in terms of discrimination of all visible light (approximately 400 nm to 650 nm).

[Problem that the invention seeks to solve]

Conventional color sensors are constructed as described above, so if inorganic materials are used, the manufacturing process is complicated and expensive, and if organic materials are used, there are problems in terms of operational stability and full visible light discrimination. There were problems such as insufficient.

This invention was made to solve the above problems, and has a simple manufacturing process and excellent operational stability.
The objective is to obtain a color sensor that is sensitive to a wide wavelength range for all visible light.

[Means for solving problems]

The color sensor according to the present invention includes a first color sensor, at least one of which has translucency. A first organic dye layer containing a small amount of tetra(4-pyridyl)porphyrin skeleton and a second organic dye layer containing at least a phthalocyanine skeleton are inserted between the second tetraelectric material; A third conductive material having translucency is inserted between the two organic dye layers, and the first to third conductive materials are anisotropically bonded to the surface of each organic dye layer on which light enters. , and is made of a material having a work function such that it forms an isotropic junction with the surface opposite to the light incident surface.

[Effect]

In this invention, each photoelectric conversion material has tetra(
2 containing 4-pyridyl) porphyrin and phthalocyanine
By using two organic dye layers, each organic dye layer has light absorption peaks on the short wavelength side and long wavelength side, respectively, and also has n-type and p-type semiconducting properties. It has a conversion function, and adjusts the p-type or n-type characteristics of each organic dye layer and the size of the work function of each conductive material (combining them to form an anisotropic junction on the light incident side of each organic dye layer). By forming such a structure, a bias is not required, operational stability is improved, and discrimination can be performed over almost the entire visible light wavelength range of 450 to 600 nm.

〔Example〕 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a color sensor according to an embodiment of the present invention. In the figure, ■ is a first conductive material, 2 is a first organic dye layer, 3 is a third conductive material, and 4 is a The second organic dye layer 5 is a second tetraelectric material.

In this device, the first organic dye layer 2 contains at least a tetra(4-pyridyl)porphyrin skeleton, the second organic dye layer 4 contains at least a phthalocyanine skeleton, and the first... The work function of the second conductive material 1°5 is greater than the work function of the third conductive material 3. Further, when the first organic dye layer 2 contains at least a phthalocyanine skeleton, the second organic dye layer 4 contains at least a tetra(4-pyridyl) skeleton.
It contains a porphyrin skeleton, and the first. The work function of the second conductive material 1.5 is smaller than the work function of the third conductive material 3.

To explain in more detail, tetra (4
-pyridyl) porphyrins are visible light in the short wavelength region (400
It is a dye that has a light absorption peak at 440 nm), exhibits n-type semiconducting properties (due to the effect of the presence of 4-pyridyl group), and exhibits highly efficient photoelectric conversion properties.
, 10.15.20-tetra(4-pyridyl)porphyrin and 5.10.15.20-tetra(4-pyridyl)porphyrin of Fe, Co, Ni, Zn', Cu, M
Metal complexes such as g are used alone, in combination, or by being trapped in a polymer matrix by chemical or physical methods.

In addition, phthalocyanine, contrary to tetra(4-pyridyl)porphyrin, has a long wavelength range of visible light (550 to 700 nm).
It is a dye that has a light absorption peak in
Metal complexes such as Co, Ni, Zn, Cu, Mg, Pb, Mn, and Ag are used alone or in combination, or by being trapped in a polymer matrix by a chemical or physical method.

Further, for forming these organic dye layers, commonly used methods such as the usual casting method, spin code method, vacuum W'tr method, etc. can be used as they are.

In addition, in FIG. 1, when the first organic dye layer 2 contains a tetra(4-pyridyl)porphyrin skeleton,
1st. Second conductive material 1. 5 is larger than the work function of the third conductive material 3, and the first conductive material 1 and the first
Organic dye layer 2. The third conductive material 3 and the second organic dye layer 4 both form an anisotropic junction, and the third conductive material 3 and the first organic dye layer 2. The second conductive material 5 and the second organic dye layer 4 must both form an isotropic junction. Examples of the first and second conductive materials that satisfy this condition include Au, Cr, Pt, Ni, and T.
Metals such as I, conductive polymers doped with acceptors such as polyacetylene, polypyrrole, polythiophene, etc. are used singly or in combination, and as the third conductive material, metals such as AI and In, and conductive polymers doped with acceptors are used.
Metal oxides such as Oz, ITO+ZnO, etc. are used.

Conversely, in FIG. 1, when the first organic dye layer 2 contains a phthalocyanine skeleton, the first organic dye layer 2 contains a phthalocyanine skeleton.
The work functions of the second tetraelectric materials 1 and 5 are smaller than the work functions of the third conductive material 3, and the first conductive material 1 and the first organic dye layer 2. and third conductive material 3 and second organic dye N4
form an anisotropic junction, and the third conductive material 3 and the first
Organic dye layer 2. The second conductive material 5 and the second organic dye layer 4 must both form an isotropic junction. Examples of the second conductive material include metals such as AI and In, and Snow
, ITo, ZnO and other metal oxides, and donor-doped conductive polymers such as polyacetylene, polypyrrole, polythiophene, etc., and the third conductive material is Au, Cr, Pt, etc.
, Nt, 'rt, and the like are used.

In addition, in FIG. 1, when the light irradiation on the sensor is performed from the first conductive material 1 side, the first conductive material 1
Needless to say, in the case of performing from the second conductive material 5 side, each second conductive material 5 must have light-transmitting properties.

Next, the operating principle of the color sensor according to this embodiment will be explained in the case where the first organic dye layer 2 contains a tetra(4-pyridyl)porphyrin skeleton and light irradiation is performed from the first tetraelectric material 1 side. Let me explain using an example.

1st. The second organic dye layers 2 and 4 are each of n-type.

It is p-type, and its photoelectric conversion spectrum is each wavelength λ
1. It is assumed that the spectra have a maximum at λ2, and their spectra do not overlap with each other, but are in contact at their base regions. This situation is shown in FIG.

When the device is configured in this way, it can be seen that the device is one in which conventionally proposed organic photoelectric conversion devices are arranged in series. That is, the first and third conductive materials 1 and 3
The portion consisting of the first organic dye layer 2 and the first organic dye layer 2 generates a negative photovoltaic force on the first conductive material 1 side with respect to light of wavelength λ1. Also, the second. The portion consisting of the third conductive material 5.3 and the second organic dye layer 4 generates a positive photovoltaic force on the second conductive material 5 side with respect to light of wavelength λ2. At this time, light is irradiated from the first conductive material 1 side, but when the light of wavelength λ8 is incident, the first organic dye layer 2 passes through without sensing it, and the light is almost attenuated. The second organic dye layer 4 is reached without any problems. Therefore, for incident light that changes continuously after the light intensity is constant from wavelength λ to λ2, the photovoltaic material appearing on the first and second conductive materials 1.5 with respect to the third conductive material 3 will be The state of the electric power is as shown in Fig. 3 ((a) is the first conductive material side, (bl is the second conductive material side).

Therefore, the third conductive material 3 is grounded, and the first conductive material 1
If the output from the second conductive material 5 is led to a logarithmic compression circuit and then input to the (+) and (-) inputs of an operational amplifier amplifier, an output having wavelength characteristics as shown in Fig. 4 is obtained. It becomes possible to specify the wavelength of the incident light in the range from λ to λ2.

Based on this operating principle, a color sensor that uses inexpensive organic materials, n-type porphyrin dyes and p-type phthalocyanine dyes, is capable of actual operation, and has excellent characteristics such as high sensitivity, reliability, and stability. became possible.

Note that in the above operating principle, even when the first organic dye N2 contains a phthalocyanine skeleton, the principle itself is the same as above, and only the polarity of the output of photovoltaic force is reversed.

A more detailed explanation will be given below using specific examples.

Specific Example 1 As shown in FIG. 5, a total of 14,000 phthalocyanine NttW bodies 14 were deposited on a soda-lime glass 10 substrate on which Cr-Au 15 was vacuum-deposited (thickness: 800 and 1,000, respectively).
Vacuum-deposited to a thickness of about 100 yen, and then sputtered 3 layers on top.
A Zn complex 12 of 5.10.15.20-tetra(4-pyridyl)porphyrin is vacuum-deposited to a thickness of about 700 mm, and then Transmittance of Au1L on top is about 70% (
At 550 nm), color sensor 1 was obtained.

Concrete Example 2 As shown in FIG. 6, a polypyrrole film 26 doped with Cl 04- by electrolytic polymerization was formed on the substrate used in Concrete Example 1.
Established with a thickness of about 3,000 people (H, Koezuka () 1.K
oezuka ) et al; Journal of Applied
Physics, Vol. 54, p. 2511 (J, Appl.
Phys, 54.2511 (1983)), and on top of this, approximately 1500% of metal-free phthalocyanine 24 is added.
Vacuum evaporated to the thickness of a person, and then coated with AI (AlzO).
s>23 was vacuum evaporated to a transmittance of about 60% (at 550 nm), and then a chloroform solution of 5.10.15.20-tetra(4-pyridyl)porphyrin 22 was formed into a film with a thickness of about 1000 nm using a spin code method. Au21 is formed on top of it with a transmittance of about 70% (at 5
50 rpm) to obtain a color sensor 2.

Specific example 3 As shown in FIG. 7, ITO substrate 10.35C surface resistance 5
0Ω/mouth) with polyvinyl chloride (PVC) and 5.10
．． 15.20-tetra(4-pyridyl)porphyrin (
A tetrahydrofuran solution with a weight ratio of 30nse (0)34 was formed to a film thickness of approximately 2000 nm using the spin code method, and Au33 was deposited on top of it at a transmittance of approximately 70% (at 550nse).
The color sensor 3 I got it.

Color sensors 1 to 3 obtained in the above specific examples 1 to 3
were connected as shown in FIG. 8, and light was irradiated from above each sensor. A tungsten lamp was used for light irradiation, and a monochromator G-250 (manufactured by Kon Co., Ltd.) was used as a spectrometer.
The experiment was carried out in the wavelength range of 400 nm to 650 nm.

For each sensor, when the gain of the logarithmic compression circuit and operational amplifier 6 shown in Fig. 8 was adjusted 8 times, it was found that all sensors had good wavelengths in the light irradiation wavelength range of approximately 450 nm to 600 nm, as shown in Fig. 9.・Output voltage characteristics were obtained.

In addition, color sensors 1 to 3 were each molded with silicone resin, and changes in the above characteristics over time were measured. Almost no change over time was observed in any of the color sensors for at least 4 months.

〔Effect of the invention〕

As described above, according to the present invention, the first. A first organic dye layer containing a tetra(4-pyridyl)porphyrin skeleton and a second organic dye layer containing a phthalocyanine skeleton are inserted between the second conductive material; A third conductive material is inserted between the second organic dye layers, and the first to third quaternary materials are arranged to form an anisotropic junction with the light incident side surface of each of the organic dye layers. Since the material has a work function, it is possible to construct two photoelectric conversion layers that have light absorption peaks on the short wavelength side and long wavelength side, respectively, and both have a highly efficient charge conversion function, and do not require a bias. This has the advantage that a color sensor that has excellent operational stability and can discriminate over almost the entire visible light wavelength range from 450 to 600 nm can be obtained at a low cost.

[Brief explanation of drawings]

1 is a cross-sectional view of a color sensor according to an embodiment of the present invention, and FIG. 2 is a sectional view of a color sensor having a wavelength of λ1. The first one has a maximum at λ2. Second
FIG. 3 is a diagram showing the photovoltaic cass vector generated by each organic dye layer, FIG. 4 is a diagram showing the output characteristics of the color sensor according to the present invention, and FIG. figure. FIGS. 6 and 7 are cross-sectional views of color sensors prepared according to specific examples 1 and 2 of the present invention, and FIG. 8 is an element connection diagram for extracting the output of the color sensor according to an embodiment of the present invention. 9 is a diagram showing wavelength/output voltage characteristics of a color sensor according to an embodiment of the present invention, and FIG. 10 is a diagram showing a conventional semiconductor color sensor. l: first conductive material, 2: first organic dye layer, 3:
...Third conductive material, 4...Second organic dye layer, 5...
Second conductive material. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) first and second organic dye layers are inserted between first and second conductive materials, at least one of which is translucent;
Furthermore, a color sensor comprising a third conductive material having translucency inserted between the first and second organic dye layers, wherein the first organic dye layer contains at least tetra(4-pyridyl). the second organic dye layer contains at least a phthalocyanine skeleton;
The conductive material has a work function such that it forms an anisotropic junction with the surface of each of the organic dye layers on the light incident side and an isotropic junction with the surface opposite to the light incident surface. A color sensor characterized by: