JP2002217474A - Photoelectric conversion film and solid-state image sensor equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a conventional three-plate type image sensor being large and heavy, of spectral prism being required in order to make the image sensor small and lightweight and of a single-plate type constituted of a light-receiving element of one plate being desired. SOLUTION: The photoelectric conversion film is formed fundamentally of a structure, wherein a light absorption and photoelectric conversion layer in which various organic pigments are dispersed to an organic polymer is sandwiched between electrodes, and a solid-state image sensor which is provided uses the photoelectric conversion film. The photoelectric conversion film has a structure where light absorption and photoelectric conversion part (film), in which the organic pigments are dispersed to the organic polymer, is sandwiched between the electrodes. When the organic pigments dispersed in the polymer absorb light, electric charges are generated. When a DC voltage is applied to both the electrodes, the electric charge generated are transported by the polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device using a functional thin film in which various organic dyes are dispersed in an organic polymer, and more particularly to a single-plate solid-state imaging device which does not require a spectral prism. It concerns the device.

[0002]

2. Description of the Related Art At present, inorganic materials such as Si and a-Se films are mainly used as photoelectric conversion films used in imaging devices such as television cameras. Since inorganic materials do not have a sharp wavelength dependence in photoelectric conversion characteristics, in an imaging device using these inorganic materials as a photoelectric conversion film, a prism that separates incident light into three primary colors of red, green, and blue, and 3 composed of three photoelectric conversion films disposed after the prism
Plate type is the mainstream.

[0003]

However, the conventional three-plate type imaging device has a problem that it is large and heavy, and in order to reduce the size and weight of the imaging device, there is no need for a spectral prism and a light receiving element. Is a single plate type.

As a technique for solving this problem, use of an organic material is conceivable. Organic materials are being actively researched and developed as next-generation functional materials due to their variety and high degree of freedom in shape. Although the development of photoelectric conversion devices using organic materials is also active, at present the prospects for application to solar cells and electrophotographic photoreceptors are only rising.

[0005]

Means for Solving the Problems A photoelectric conversion film according to the present invention is dispersed in an organic polymer and the organic polymer.
An organic dye that absorbs light of a predetermined wavelength to generate charges transported in the organic polymer. According to the present photoelectric conversion film, it can be applied to a single-plate type imaging device having one light receiving element that does not require a spectral prism, and it is possible to reduce the size and weight of the imaging device. Further, since an organic material is used, the shape can be freely changed. In addition, driving can be performed at a low voltage, and power can be saved.

Further, the solid-state imaging device according to the present invention includes a photoelectric conversion film for converting incident light into electric charges, wherein the photoelectric conversion film is dispersed in an organic polymer and the organic polymer. An organic dye that absorbs light of a predetermined wavelength to generate charges transported in the organic polymer. According to the present solid-state imaging device, as described above, it can be applied to a single-plate imaging device having one light receiving element that does not require a spectral prism, and it is possible to reduce the size and weight of the imaging device.

Further, in the solid-state imaging device according to the present invention, there is provided a first photoelectric conversion film in which the organic dye absorbs red light, a second photoelectric conversion film in which the organic dye absorbs green light, and the organic dye. And a third photoelectric conversion film that absorbs blue light, and the first to third photoelectric conversion films are arranged in parallel or stacked. According to the solid-state imaging device, a full-color imaging device can be easily manufactured with a simple configuration.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a photoelectric conversion film having a structure in which a light absorption / photoelectric conversion layer in which various organic dyes are dispersed in an organic polymer is sandwiched between electrodes, and a solid-state imaging device using the same. It concerns the device. The device structure is similar to organic electroluminescence (hereinafter, abbreviated as organic EL device), which has been developed in many cases in recent years. However, the driving region of the organic EL device is such that current injection into an organic polymer layer is performed. While the applied voltage is equal to or higher than the applied voltage, the solid-state imaging device of the present invention is characterized in that it is driven in an applied voltage region before current injection to the organic polymer layer is started.

Hereinafter, the solid-state imaging device according to the present invention will be described in detail. The solid-state imaging device according to the present invention is a light absorption / photoelectric conversion unit (film) in which an organic dye is dispersed in an organic polymer.
Is sandwiched between electrodes, and the organic dye uniformly dispersed in the polymer generates light by absorbing light, and by applying a DC voltage to both electrodes,
The generated charges are transported by the polymer.

FIG. 1 is a sectional view of a solid-state imaging device according to the present invention. In FIG. 1, 11 is a substrate, 12 is an organic dye-dispersed polymer layer in which an organic dye is dispersed, and 13 is an electrode.
On a substrate 11, an electrode 13, an organic dye-dispersed polymer layer 12,
The electrodes 13 are provided sequentially. Therefore, the organic dye-dispersed polymer layer 12 is sandwiched between the electrodes 13. Substrate 1
As for 1, when light is irradiated from the substrate side, it is desirable that the transparency is high, and glass, polyethylene, polyethylene terephthalate, polyether sulfone, polypropylene, or the like is preferable. However, when light irradiation is not performed from the substrate 11 side, there is no limitation on the transparency of the substrate, and Si, Ge, GaAs, or the like can be used in addition to the above-described materials.

The organic dye dispersed in the organic dye-dispersed polymer layer 12 that absorbs light can be any organic dye that absorbs in the visible region, and includes acridine dyes, coumarin dyes, cyanine dyes, squarylium, Oxazine dyes,
Xanthene dyes and the like are used. Needless to say, if an organic polymer that absorbs in the ultraviolet is used, it can be applied to a photoelectric conversion element for ultraviolet rays.

On the other hand, the polymer in the organic dye-dispersed polymer layer 12 is preferably a non-conductive polymer represented by polyvinyl alcohol or polycarbonate, and is preferably polyparaphenylenevinylenes, polyfluorenes, polyvinylcarbazoles, polythiol. And π-electron conductive polymers such as polythiophenes, and σ-electron polymers such as polysilanes, polygermanes, and their network polymers are preferred.

The amount of the organic dye to be added must be 0.1 mol% or more in terms of a molar ratio with respect to the unit unit of the organic polymer in order to obtain a sufficient number of photocharges to be generated as a photoelectric conversion film.
The content is preferably at least 5 mol%.

The photoelectric conversion film is formed by a wet method such as a spin coating method, a bar coating method, a casting method, and a dipping method, and is formed from a mixed solution of a polymer and an organic dye. As the solvent, any organic solvent can be used as long as the polymer and the organic dye are soluble, and tetrahydrofuran,
Toluene, butyl acetate, monochlorobenzene, acetic acid 2-
Ethoxyethyl, ethyl carbitol acetate, propylene glycol monomethyl ether acetate, N-methyl-2-pyrrolidone, ethyl lactate, propylene glycol monomethyl ether, methanol, ethanol, propanol,
Dioxane or the like is used. Since a solvent in which both the polymer and the organic dye are soluble is not always obtained, in such a case, a single solution of each of the organic dye and the polymer using the above solvent is mixed to form a film.

On the other hand, there are also dry methods typified by co-vacuum vapor deposition using each polymer powder, multi-element organic molecular beam vapor deposition, co-laser ablation using dye and polymer pellets, and sputtering. In this case, it is necessary to pay attention to the irradiation of high-energy electromagnetic waves and the breaking of the polymer chains due to heat.

If the thickness of the photoelectric conversion film is too large, not only must a high voltage be applied to obtain a photocurrent,
The film surface may be cracked, and if it is too thin, a short circuit between the electrodes may occur. Therefore, the thickness is preferably adjusted to about 10 nm to 10 μm, preferably 100 nm to 5 μm.

Regarding the electrode 13, at least the light irradiation side is desirably a transparent electrode, which corresponds to indium tin oxide, indium oxide, tin oxide, and the like. For the other electrode, not only the transparent electrode but also aluminum and vanadium. Metals such as gold, silver, platinum, iron, cobalt, carbon, nickel, tungsten, palladium, magnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium and manganese or alloys thereof are used. The thickness of these electrodes may be about 100 nm to 200 nm, but if it is desired to obtain light transmittance, 50 nm to 100 nm
Can be used.

Of the above organic dyes, red absorption, green absorption,
By selecting those with blue absorption and arranging polymer films in which each dye is dispersed in parallel or in a stack,
A photoelectric conversion film for a full-color imaging device can be easily manufactured.

FIG. 2 is a sectional view of a parallel type solid-state imaging device according to the present invention. 2, reference numeral 21 denotes a substrate, 22A denotes a first organic dye-dispersed polymer layer, 22B denotes a second organic dye-dispersed polymer layer, and 22C denotes a third organic dye-dispersed polymer layer.
3A to 23F are electrodes. Substrate 21 and electrodes 23A-
The material of 23F conforms to the solid-state imaging device described with reference to FIG. First to third organic dye-dispersed polymer layers 22A-
22C is a red absorption layer, a green absorption layer, and a blue absorption layer, respectively. However, the order of arrangement is not particularly limited, and a different material can be used for each color absorption layer with respect to a polymer that performs charge transport.

FIG. 3 is a sectional view of a stacked solid-state imaging device according to the present invention. In FIG. 3, 31 is a substrate, 32A is a first organic dye-dispersed polymer layer, 32B is a second organic dye-dispersed polymer layer, and 32C is a third organic dye-dispersed polymer layer.
3A to 33F are electrodes, and 34A and 34B are insulating layers. As the material of the substrate 31, any of the materials described above can be used. The first to third organic dye-dispersed polymer layers 32A to 32C respectively include a red absorption layer, a green absorption layer,
Although it is a blue absorption layer, there is no particular limitation on the order of lamination of each color absorption layer, and a different material can be used for each color absorption layer also for a polymer that performs charge transport. Regarding the materials of the electrodes 33A to 33F, the above-described transparent electrodes such as indium tin oxide, indium oxide, and tin oxide are preferable, but aluminum, vanadium, gold, silver, platinum, iron, cobalt, carbon, nickel, Use a metal such as tungsten, palladium, magnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium, manganese, or an alloy thereof, and use a translucent electrode whose electrode thickness is adjusted to about 50 nm to 100 nm. Is also possible. For the insulating layers 11 and 12, a transparent insulating material such as glass, polyethylene, polyethylene terephthalate, polyether sulfone, or polypropylene is used.

[0021]

The present invention will be described in more detail with reference to the following examples. Using coumarin 6 as an organic dye and polysilane as a polymer, dissolving 2.9 mg of coumarin 6 and 20 mg of polysilane in 1 ml of chloroform so that the molar ratio of coumarin 6 to unit mole of polysilane is 5.0 mol%. To prepare a mixed solution. 0.3 ml of this mixed solution was dropped onto a 20 mm × 20 mm quartz glass substrate provided with an indium tin oxide thin film (ITO) electrode to obtain a 1.0 μm-thick organic dye-added polymer layer. An aluminum electrode was formed thereon with a thickness of 2 mm × 2 mm and a thickness of 120 nm.

FIG. 4 is a graph showing spectral sensitivity characteristics when a DC voltage of 10 V is applied to the device obtained in this embodiment. A positive voltage was applied to the ITO electrode, and light of 50 μW / cm ² was irradiated from the quartz substrate side. For comparison, the figure also shows the characteristics of a film made of only polysilane that performs charge transport. As is clear from the figure, a photocurrent derived from the coumarin 6 dye was clearly observed.

FIG. 5 is a graph showing the voltage-current characteristics at the maximum photocurrent wavelength. It was possible to obtain a photocurrent about 10 times as large as that when no light was irradiated.

It should be noted that the present invention is not limited by the above-described embodiments and embodiments, and many variations and modifications are possible. For example, if an organic dye that absorbs light in the infrared region and generates a photocharge is used, it can be used as an infrared imaging element. In the above description, the separation into three primary colors has been described as an example. However, the present invention is not limited to the three primary colors, and it is needless to say that the present invention can be applied to the separation into arbitrary element colors.

[0025]

As described above, the present invention is a photoelectric conversion film comprising a light absorbing layer in which an organic dye is dispersed in an organic polymer. In particular, a photoelectric conversion film is characterized in that an organic dye generates a photocharge and the polymer layer transports the generated charge, and is characterized by absorbing only light of a specific wavelength by selecting an organic dye. And a solid-state imaging device comprising these photoelectric conversion films. Also, by appropriately selecting an organic dye, red, green,
A single-panel full-color solid-state imaging device can be realized by preparing each of the blue-absorbing photoelectric conversion films and arranging them in layers or in parallel.

[Brief description of the drawings]

FIG. 1 is a sectional view of a solid-state imaging device according to the present invention.

FIG. 2 is a sectional view of a parallel solid-state imaging device according to the present invention.

FIG. 3 is a sectional view of a stacked solid-state imaging device according to the present invention.

FIG. 4 is a graph of a spectral sensitivity characteristic of the photoelectric conversion element according to the embodiment of the present invention.

FIG. 5 is a graph showing a voltage of a photoelectric conversion element according to an embodiment of the present invention.
It is a graph of a current characteristic.

[Explanation of symbols]

 Reference Signs List 11 substrate 12 organic dye-dispersed polymer layer 13 electrode 21 substrate 22A first organic dye-dispersed polymer layer 22B second organic dye-dispersed polymer layer 22C third organic dye-dispersed polymer layer 23A to 23F electrode 31 substrate 32A First organic dye-dispersed polymer layer 32B Second organic dye-dispersed polymer layer 32C Third organic dye-dispersed polymer layer 33A-33F Electrode 34A, 34B Insulating layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04N 9/07 H01L 29/28 F term (Reference) 4M118 AA10 AB01 CA27 CB14 CB20 GA02 GC08 5C065 BB42 CC01 DD01 DD17 DD26 5F088 AA11 AB11 BA15 BB03 FA02 FA05 LA03

Claims (3)

[Claims] 1. An organic polymer and an organic dye dispersed in the organic polymer and absorbing light of a predetermined wavelength to generate a charge transported in the organic polymer. A photoelectric conversion film characterized by the above-mentioned. 2. A photoelectric conversion film for converting incident light into electric charge, wherein the photoelectric conversion film is dispersed in the organic polymer and the organic polymer, and absorbs light of a predetermined wavelength. A solid-state imaging device comprising: an organic dye that generates charges transported in the organic polymer. 3. The solid-state imaging device according to claim 2, wherein the organic dye absorbs red light, a first photoelectric conversion film, and the organic dye absorbs green light. A third photoelectric conversion film in which the organic dye absorbs blue light;
An apparatus comprising: the first to third photoelectric conversion films arranged in parallel or stacked.