JPH0797044B2 - Photoelectric conversion element and method for manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion element using a biopolymer composite having a photoelectric conversion function and a method for producing the same.

[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.

[0006]

However, the photoelectric response characteristics of the prior art photoelectric conversion device using photosynthetic granules, which are biopolymer composites having a photoelectric conversion function, are an excessive phenomenon and are accompanied by light irradiation. It was not possible to obtain steady power. This is because in the conventional device, the direction of the functional protein complex of the photosynthetic granules is disordered, so that the photoelectric response obtained as the output is between both electrodes in the sum of reactions having disordered directionality. It is considered that this is due only to a minute difference due to a small difference in the above or a weak response depending on the difference in the work function of the electron transfer between the electrodes.

Therefore, the observed photoelectric response output was very small. Therefore, it has been desired to improve the effective response output.

An object of the present invention is to provide a simple and effective method for improving the response output of a photoelectric conversion element using a biopolymer composite having a photoelectric conversion function.

[0009]

The photoelectric conversion element of the present invention comprises an active material composed of a dried and solidified film of a biopolymer composite having a photoelectric conversion function, between a pair of electrodes in which at least one electrode sufficiently transmits light. It is characterized in that a layer and an intermediate layer made of a conductive polymer film are laminated.

[0010]

In order to use the photoelectric conversion element using the biopolymer composite, improvement in response output has been desired. In order to achieve this object, improvement of device characteristics can be considered mainly from two viewpoints.

One is to orient the flow of electrons by orderly controlling the orientation of a biopolymer complex having a polar photoelectric conversion function. The other one is
From the aspect of the device structure, an electron transfer medium is formed to control the flow of electrons.

The present invention focuses on the layer structure of the photoelectric conversion element from the latter viewpoint. By further inserting a conductive polymer film as an electron transfer medium layer into the device structure of the photoelectric conversion active layer sandwiched by the electrodes, it was possible to obtain a device output higher than conventional ones.

[0013]

EXAMPLE A photoelectric conversion element according to an example of the present invention will be described in detail below with reference to FIG.

First, the transparent electrode 3 is formed on the glass substrate 4. As a transparent electrode, indium tin oxide (IT
It is preferable to use a semiconductor such as O), tin dioxide (SnO2), zinc oxide (ZnO), or a semitransparent evaporated gold thin film.

Next, an intermediate layer 7 made of a conductive polymer film is formed on the transparent electrode 3. The conductive polymer is preferably an oxidative polymerization type conductive polymer such as polythiophene or polypyrrole and derivatives thereof. As a method for forming a conductive polymer film, a method in which a polymer film is directly protruded from an monomer by an electrolytic polymerization method or a catalytic polymerization method,
Alternatively, there is a method of applying a polymer solution prepared in advance onto the electrode by a method such as brush coating, dipping, or spin coating.

Next, the photoelectric conversion active layer 1 is formed on the formed conductive polymer film 7. Examples of the biopolymer complex that constitutes the photoelectric conversion active layer include photosynthetic bacteria, preferably chromatophores derived from red photosynthetic bacteria, photosynthetic units (PRU), photosynthetic granules such as reaction centers (RC), and other photosynthetic organisms. And the photosynthetic protein complex.
As the forming method, there are methods such as brush coating, spin coating, and printing. After forming the active layer, it is dried by a technique such as natural drying or vacuum drying to obtain a solidified film.

Next, the upper counter electrode 2 is formed to complete the device. As a method of forming the upper counter electrode, for example, an electrode material such as gold is laminated by a method such as a vacuum deposition method. The lead wire 6 for deriving a signal is connected to both electrodes with silver paste 5 or the like.

The relative positional relationship between the transparent electrode 3 and the photoelectric conversion active layer 1 and the mediating layer 7 made of a conductive polymer may be reversed.

When light of sunlight, strobe light, LED or the like is irradiated from the transparent electrode side of the photoelectric conversion element through the conductive polymer film layer thus prepared, photoelectric response output can be obtained.

A specific example will be described below. Specific example (1). Cultivation of photosynthetic bacteria and preparation of chromatophores Red photosynthetic bacterium Rhodesudomonas 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). Formation of conductive polymer layer The conductive polymer layer was formed by an electrolytic polymerization method in a solution using an electrolytic polymerization apparatus as shown in FIG. A solution was prepared by dissolving 55 mM thiophene (or pyrrole) in high-purity acetonitrile and 55 mM tetraethylammonium perchlorate as a supporting electrolyte. After degassing under reduced pressure, transfer to the electrolytic cell, and from the N2 inlet 11 to N
2 flow in, discharge from N2 outlet 12, N2 for about 30 minutes
Bubbling was performed. In this way, the electrolyte solution 10
Prepared. Then, the element substrate 9 having the platinum (Pt) electrode 8 and the ITO electrode formed thereon was immersed in the solution to carry out electrolytic polymerization. By applying a constant voltage of 5 V for about 15 seconds, polythiophene (or polypyrrole) was formed on the positive electrode ITO substrate.

(3). Formation of photoelectric conversion active layer Using the chromatophore prepared by the method of (1), a chromatophore layer is formed by superposing it on the conductive polymer layer formed in (2). First, the chromatophore concentration was adjusted so that the optical density OD = 100 with respect to the main absorption peak of the chromatophore at 1020 nm. The prepared solution was uniformly applied on the conductive polymer layer, and evaporated and dried in a cool dark place. After drying, the same operation was repeated twice to complete the chromatophore layer.

(4). Formation of upper counter electrode The upper counter electrode 2 is formed on the chromatophore layer formed in (3).
Was formed to complete the device. As the upper counter electrode, a gold thin film electrode was formed on the chromatophore layer by using vacuum deposition.

After that, a lead wire 6 for deriving a signal was connected to both electrodes with a silver paste 5. Thus, the photoelectric conversion element using the chromatophore of red photosynthetic bacteria
When a conductive polymer layer was newly provided between the O electrode and the photoelectric conversion active layer, the current response, which was transient with respect to the conventional light irradiation time, was improved.

That is, in this device, as shown in FIG. 4, a component showing a steady current was observed following light irradiation, following a large initial transient response. It is considered that the conductive polymer acts as a promoter or a mediator of electron transfer between the chromatophore and the ITO electrode to make the electron transfer to the electrode smoother.

When the voltage was measured using the same photoelectric conversion element, as shown in FIG. 5, a larger voltage output than the conventional one was obtained. It is considered that this is because the electrons were smoothly transferred between the chromatophore and the ITO electrode due to the same reason as described above, and as a result, the flow of the generated charge was directional.

Furthermore, when the two elements of this example were connected in series and in parallel, the steady-state values of the voltage and current response were each doubled. This result showed that the device had the characteristics as a battery.

From the above, the photoelectric conversion element of the present invention is extremely useful as an element such as an optical sensor or 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.

[0030]

EFFECTS OF THE INVENTION A photoelectric conversion element using a biopolymer composite having a new structure provides characteristics superior to conventional ones.

Not only a transient response but also a steady photoelectric response can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a photoelectric conversion element according to the present invention.

FIG. 2 is a schematic sectional view of a conventional photoelectric conversion element.

FIG. 3 is a diagram showing an electropolymerization apparatus for a conductive polymer.

FIG. 4 is a diagram showing a photoelectric response (current) of the photoelectric conversion element of the present invention.

FIG. 5 is a diagram showing a photoelectric response (voltage) of the photoelectric conversion element of the present invention.

[Explanation of symbols]

 1 Photoelectric conversion active layer (dried and solidified film of photosynthetic granules) 2 Upper counter electrode (Au film) 3 Transparent electrode (ITO electrode) 4 Glass substrate 5 Silver paste 6 Lead wire 7 Mediation layer (conductive polymer film) 8 Pt electrode 9 Element substrate 10 Electrolyte solution 11 N2 inlet 12 N2 outlet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayuki Hara Inventor, 1-3-1, Higashi Tsukuba, Ibaraki Prefectural Institute of Microbial Science and Technology (72) Inventor Masami Awai 5-9, Tokodai, Tsukuba, Ibaraki Stanley Electric Co., Ltd. Tsukuba Research Institute (72) Inventor Hiroaki Sugino 5-9 Tokodai, Tsukuba City, Ibaraki Prefecture 5 Stanley Electric Co., Ltd. Tsukuba Research Institute (72) Inventor Shuichi Aji, 5-9 Tokodai, Tsukuba City, Ibaraki Prefecture No. 5 Stanley Electric Co., Ltd. Tsukuba Research Institute (72) Inventor Hideki Toyoda 5-5-9 Tokodai, Tsukuba City, Ibaraki Prefecture Stanley Electric Co., Ltd. Tsukuba Research Laboratory Examiner Hiroyuki Sekine (56) Reference JP-A-4-270926 (JP, A) JP-A-4-125425 (JP, A) JP-A-1-110224 ( P, A) JP Akira 62-63823 (JP, A)

Claims (6)

[Claims] 1. An active layer composed of a dried and solidified biopolymer composite film having a photoelectric conversion function, and an intermediate layer composed of a conductive polymer film, between a pair of electrodes in which at least one electrode sufficiently transmits light. A photoelectric conversion element, characterized in that 2. The photoelectric conversion element according to claim 1, wherein photosynthetic granules derived from purple photosynthetic bacteria are used in the active layer. 3. The photoelectric conversion device according to claim 1, wherein an oxidative polymerization type conductive polymer and a derivative thereof are used as the conductive polymer. 4. The photoelectric conversion element according to claim 3, wherein the conductive polymer is polythiophene. 5. The photoelectric conversion element according to claim 3, wherein the conductive polymer is polypyrrole. 6. An active layer made of a biopolymer composite dry-solidified film having a photoelectric conversion function and a mediating layer made of a conductive polymer film, between at least one of the pair of electrodes that sufficiently transmits light. A method of manufacturing a photoelectric conversion element, wherein the conductive polymer film is formed by bending the conductive polymer film onto an electrode by electrolytic polymerization.