JPH0640022B2 - Method for manufacturing photoelectric conversion element - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a photoelectric conversion element using a biopolymer composite having a photoelectric conversion function.

[0002]

2. Description of the Related Art Photosynthetic bacteria have a photosynthetic organ as an inner membrane structure. Photosynthetic organs contain lipids, photosynthetic units, oxidoreductases, etc., and the photosynthetic granules obtained as fragments are closed vesicles composed of a membrane consisting of chromatophores, proteins such as spheroplast vesicles, and lipids. Is. This kind of membrane has a photosynthetic reaction center protein complex that carries out a photoelectric conversion reaction, and it sandwiches the membrane by photostimulation to generate a potential difference.

A membrane fragment such as a chromatophore is obtained by crushing the cell membrane by a method such as ultrasonic treatment. Photosynthetic proteins (collectively called photosynthetic granules) such as photosynthetic membrane fragments such as chromatophores, photoreactive units, and reaction centers
A photoelectric conversion element utilizing the effect of causing charge separation and electron transfer upon light stimulation has been considered (Japanese Patent Laid-Open No. 1-11).
10224).

As shown in FIG. 2, this photoelectric conversion element has an I
On the glass substrate 4 on which the transparent electrode 3 such as TO (indium-tin oxide) is formed, the dried and solidified film of the photosynthetic granules to be the photoelectric conversion active layer 1 is provided, and the upper counter electrode 2 is further formed by Au vapor deposition or the like. There is. Silver paste 5 from each electrode 2 and 3
The lead wire 6 is led out via.

Electric power can be obtained by irradiating this element with light from the transparent electrode 3 side.

However, in such a conventional element, since vacuum deposition has been mainly used as a method for forming the upper counter electrode, the photoelectric conversion active layer 1 is a monolayer formed by the Langmuir-Blodgett (LB) method or the like. In the case where the film thickness is extremely thin, such as the case where the electrodes are laminated, there is a drawback that both electrodes penetrate through the element and become electrically conductive. Had to intervene. In this case, the element is of the capacitive type, and no direct current flows, so that a response signal is generated when the input changes.

Further, in the method of forming the upper counter electrode by vacuum vapor deposition, the biopolymer forming the photoelectric conversion active layer is exposed to the high temperature metal vapor or receives the heat thereof, so that the protein is locally denatured. I could not avoid it.

[0008]

DISCLOSURE OF THE INVENTION The present invention prevents deterioration of device characteristics due to thermal denaturation of biopolymer without causing short circuit between electrodes even on an extremely thin photoelectric conversion active layer prepared by the LB method or the like. It is intended to simply manufacture the upper counter electrode without causing the above.

[0009]

The present invention relates to the production of a photoelectric conversion element having a structure in which a transparent electrode, an active layer made of a dried and solidified film of a biopolymer composite having a photoelectric conversion function and an upper counter electrode are laminated. The method of forming the upper counter electrode is characterized in that the electrode material foil obtained by peeling off the vapor deposition film of the electrode material on the water surface is scooped on the active layer.

[0010]

Since the upper opposing electrode is formed by scooping the electrode material foil with the water surface peeled off on the active layer, the electrode pair can be formed without giving a strong stimulus to the active layer such as a vacuum deposition process.

Therefore, the electrodes can be formed on both surfaces of the thin active layer without causing a short circuit between the electrodes.

[0012]

EXAMPLES The method for producing a photoelectric conversion element according to the present invention will be described in detail below. The structure of the element is similar to that shown in FIG.

First, the transparent electrode 5 is formed on the substrate 4.
As the transparent electrode, indium tin oxide (ITO), tin dioxide (SnO2), zinc oxide (ZnO), a sufficiently thin evaporated gold electrode, or the like is used.

Next, the photoelectric conversion active layer 1 is provided on the transparent electrode 3. Examples of the biopolymer complex that constitutes the photoelectric conversion active layer include photosynthetic bacteria-derived chromatophores, photosynthetic granules such as photosynthetic units (PRU) and reaction centers (RC), and photosynthetic protein complexes derived from other photosynthetic organisms. Is mentioned. As photosynthetic bacteria, red photosynthetic bacteria are preferable. The chromatophore is obtained by disrupting photosynthetic bacteria by a method such as ultrasonic treatment. The chromatophore in purple photosynthetic bacteria has a structure in which a photosynthetic reaction unit is embedded in a lipid bilayer. The reaction center protein, which is a structure lacking the light-trapping protein complex from the photosynthetic reaction unit, can be obtained by treating the chromatophore with a surfactant.

As a method for forming an active layer composed of such a biopolymer composite, coating methods such as brush coating, spin coating, printing, etc., a film forming method by electrodeposition of photosynthetic granules, and a film by LB method etc. There is a cumulative method. After forming the active layer,
A solidified film is obtained by drying by a technique such as natural drying or reduced pressure drying.

The upper counter electrode 2 is formed by scooping the electrode material foil obtained by peeling off the vapor deposition film of the electrode material on the water surface onto the active layer. First, a thin film of an electrode material is formed on a suitable other substrate such as a slide glass or mica by a vacuum evaporation method. In this case, it may be effective to apply glycerin, grease or the like evenly thinly on the substrate in advance in order to promote later peeling of the deposited film on the water surface.

Then, as shown in FIG. 1 (A), the slide glass 7 is lowered into the distilled water 9 so that one side of the boundary of the vapor deposition film 8 is brought into contact with the water surface, and the water is kept between the substrate 7 and the thin film 8. Hold until intrusion. Then, the substrate 7 is slowly submerged in water according to the peeling of the thin film, and the foil 8 of the electrode material having a required area is formed.
Float on the surface of the water.

As shown in FIG. 1B, the ITO electrode 3,
The glass substrate 4 on which the photosynthetic granule film 1 is formed is submerged in water. The glass substrate 4 is gradually pulled up, and the release film 8 floating on the water surface is slowly scooped on the active layer 1. Excess water is removed and dried to complete device formation. Lead wires for external connection are connected to both electrodes with silver paste or the like.

It is also possible to scoop from the upper surface of the peeling film 8. In this case, when a release agent such as glycerin is provided, the release agent remains effective between the active layer 1 and the release agent 8 and is effective.

A photoelectric response output can be obtained from the photoelectric conversion element thus manufactured by irradiating light such as sunlight, strobe, or LED from the transparent electrode side.

Specific example

(1). Cultivation of photosynthetic bacteria and preparation of chromatophore Rhodose Pseudomonas viridis (Rhod)
opseudomonas viridis, ATCC 19567) 30
The cells were cultured at ℃, light irradiation and anaerobic conditions. The collected bacterial cells were suspended in a buffer solution, and the bacterial cell membrane was disrupted using ultrasonic waves. The chromatophore was then prepared by differential centrifugation. The chromatophore was homogenized in a buffer solution and uniformly suspended.

(2). Preparation of Reaction Center Protein The reaction center protein is prepared by using the above-mentioned chromatophore as a surfactant D.
It was prepared by solubilizing with DAO and fractionating the solubilized supernatant by gel filtration chromatography.

(3). Formation of Photoelectric Conversion Active Layer The formation of the photoelectric conversion active layer is carried out by expanding and compressing the above reaction center protein on the air-water interface and compressing the monomolecular film on the glass substrate on which the ITO electrode is formed. This was done by the LB method, which accumulates above.

In this example, 50 to 100 layers of photoelectric conversion active layers were used.

(4). Formation of upper counter electrode A thin gold film (film thickness: 20 nm) vapor-deposited on a slide glass through a mask having an opening pattern of a desired shape was peeled off on the water surface by the above-mentioned method to form a reaction center. It was scooped on the active layer of the LB film and dried to form an upper counter electrode.

When the upper facing electrode of the photoelectric conversion element having an extremely thin active layer such as the LB film was formed by the conventional direct vacuum evaporation method, conduction between both electrodes was unavoidable. For example, L of the 100-layer reaction center protein prepared in this example was used.
Even in an element having the B film as an active layer, the element becomes conductive, and it was necessary to interpose an insulating protective layer in the element.
On the other hand, in the above example, the upper counter electrode could be formed without conducting even on an extremely thin active layer having a cumulative number of layers of about 50. In the device with the insulating protective layer, only the transient photoelectric response could be observed, but in the device of this example, the photoelectric response including the constant current / voltage component accompanying light irradiation was observed. To be done.

Further, in the vacuum vapor deposition method, since the active layer comes into contact with the high temperature vapor of the electrode material, the possibility that the protein near the electrode is locally denatured cannot be denied. In this example, since the upper electrode is formed by a method similar to the accumulation method of the active layer, the risk of deterioration of device characteristics due to thermal denaturation of protein molecules can be reduced.

Such a photoelectric conversion element is used as an optical sensor
It is extremely useful as a device such as a solar cell.

The present invention has been described above with reference to the embodiments.
The present invention is not limited to these. For example,
It will be apparent to those skilled in the art that various changes, improvements, combinations and the like can be made.

[0031]

EFFECT OF THE INVENTION By using a biopolymer composite having a photoelectric conversion function, a photoelectric conversion element capable of effectively taking out a photoelectric response can be produced.

It is also possible to extract a direct current response.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a photoelectric conversion element according to an example of the present invention. FIG. 1 (A) shows the water surface peeling process of the electrode material vapor deposition film, and FIG. 1 (B) shows the scooping process of the water vapor-deposited electrode vapor deposition film onto the substrate.

FIG. 2 is a cross-sectional view showing a configuration of a photoelectric conversion element.

[Explanation of symbols]

 1 Photoelectric Conversion Active Layer (Photosynthetic Granule Film) 2 Upper Counter Electrode (Au Vapor Deposition Film Electrode) 3 Transparent Electrode 4 Transparent Substrate 5 Silver Paste 6 Lead Wire 7 Slide Glass 8 Electrode Material Vapor Deposition Film 9 Distilled Water

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Sugino 3-24-2 Namiki, Tsukuba City, Ibaraki Prefecture Corp Namiki A101

Claims (4)

[Claims] 1. A method for forming an upper counter electrode in the production of a photoelectric conversion element having a structure in which a transparent electrode, an active layer made of a dried and solidified film of a biopolymer composite having a photoelectric conversion function, and an upper counter electrode are laminated. A method for producing a photoelectric conversion element, characterized in that an electrode material foil obtained by peeling a vapor-deposited film of an electrode material on the water surface is scooped on the active layer. 2. The production method according to claim 1, wherein photosynthetic granules derived from purple photosynthetic bacteria are used in the active layer. 3. The production method according to claim 2, wherein the active layer comprises a thin film obtained by accumulating photosynthetic granules derived from purple photosynthetic bacteria by the LB method. 4. The manufacturing method according to claim 1, wherein the upper counter electrode is made of gold foil.