WO2006025433A1

WO2006025433A1 - Photoelectric transduction material, photoelectric transduction apparatus and process for producing photoelectric transduction material

Info

Publication number: WO2006025433A1
Application number: PCT/JP2005/015876
Authority: WO
Inventors: Yasuhiko Kasama; Kenji Omote
Original assignee: Ideal Star Inc.
Priority date: 2004-08-31
Filing date: 2005-08-31
Publication date: 2006-03-09
Also published as: JP2006073201A

Abstract

Hollow fullerenes have been used as an electron acceptor being a constituent of photoelectric transduction material. However, satisfactorily high photocurrent intensifying effect has not been realized. There is provided production of a photoelectric transduction material comprising employing an atom-confining endohedral fullerene as an electron acceptor and doping an electron donating organic material with the atom-confining endohedral fullerene. A striking increase of photocurrent as compared with that of conventional photoelectric transduction material has been achieved.

Description

Photoelectric conversion material, photoelectric conversion device, and method for manufacturing photoelectric conversion material

The present invention relates to a photoelectric conversion material made of an organic semiconductor and a photoelectric conversion device using the photoelectric conversion material.

Background art

[0002] Non-Patent Document 1: Fullerene Chemistry and Physics Nagoya University Press

Non-Patent Document 2: Current Status and Prospects of Organic Solar Cells p.425-428 Applied Physics No. 71 卷 No. 4 (200 2)

[0003] The use of alternative energy sources such as solar power generation and wind power generation has been promoted as a source of clean energy to replace petroleum energy that has problems such as air pollution. In particular, the power generation method using solar cells does not require a large-scale power generation facility, can be used anywhere, and is excellent in safety and quietness.

[0004] Solar cells are classified into an inorganic solar cell using an inorganic material such as a silicon semiconductor as a photoelectric conversion material and an organic solar cell using an organic material such as an organic semiconductor. Conventionally, inorganic solar cells with high energy conversion efficiency have been mainly developed (conversion efficiency is about 25% for single crystal silicon and about 12% for amorphous silicon), but inorganic solar cells are made of materials. Is expensive, and the manufacturing process is complicated, so it is difficult to reduce costs, which has been a major obstacle to the spread of solar cells.

[0005] In recent years, among organic solar cells, Gratzel-type dye-sensitized solar cells have obtained energy conversion efficiencies as high as 10%, which is equivalent to inorganic solar cells. Compared to inorganic solar cells, organic solar cells have the advantage of low manufacturing costs of 1/5 to 1/10, simple manufacturing processes with fewer resource constraints, and practical use such as improved energy conversion efficiency. Research is progressing toward the realization.

[0006] Gratzel-type dye-sensitized solar cells use an electrolytic solution containing iodine, and have many problems to be solved in terms of stability and durability. Meanwhile, among organic solar cells, Bulk Heteroj An organic solar cell, called an unction-type organic thin-film solar cell, has a simple structure in which a thin film made of a photoelectric conversion material consisting of a uniform mixture of electron donor and electron acceptor organic molecules is sandwiched between different electrodes. It is easy to fabricate, does not require high-temperature processes, has excellent stability and durability, and dislikes attention.

FIG. 6 is a cross-sectional view of a conventional bulk heterojunction type organic thin film solar cell. The organic thin-film solar cell shown in FIG. 6 includes a glass substrate 101, a positive electrode 102 made of a transparent material such as ITO, a photoelectric conversion material film in which an electron-donating organic material 103 is doped with fullerene 105, A 1 The negative electrode 104 is made up of.

[0008] Doping fullerene (C) into a conductive polymer serving as a host material of a photoelectric conversion material

60

Thus, the fluorescence intensity due to light irradiation is remarkably attenuated and the photocurrent is enhanced. This is because the electrons excited in the conductive polymer by light irradiation are trapped by fullerene having a high electron affinity, so the probability of recombination with holes generated simultaneously with the electrons is reduced. The generated electrons move between the fullerenes which are electron acceptors by hopping, and the generated holes move between the conductive polymers which are electron donors by hopping. The lifetime of electrons and holes, which are photoconductive carriers, is increased, so that the photocurrent increases.

Disclosure of the invention

Problems to be solved by the invention

[0009] Conventional solar cells using photoelectric conversion materials with fullerenes (empty fullerenes) as electron acceptors did not have a sufficiently high photocurrent enhancement effect to replace inorganic solar cells.

Means for solving the problem

[0010] It was decided to use an electron-donating organic material as the electron donor constituting the photoelectric conversion material, and to use atom-encapsulated fullerenes as the electron acceptor.

[0011] The present invention (1) is a photoconductivity enhancer that also has the power of endohedral fullerenes.

In the present invention (2), the atoms encapsulated in the atom-encapsulated fullerenes are alkali metals.

The photoconductivity enhancer of the invention (1).

[0013] In the present invention (3), the atom encapsulated in the atom-encapsulated fullerene is Li.

It is a photoconductivity enhancer of (1). [0014] In the present invention (4), the fullerene is C 1, C 2 or a mixed fullerene thereof.

60 70

The photoconductivity enhancer according to the invention (1) to the invention (3).

[0015] The present invention (5) is a photoelectric conversion material comprising the photoconductivity enhancer of the above inventions (1) to (4).

[0016] The present invention (6) is the photoelectric conversion material according to the invention (5) comprising at least the above-described photoconductivity enhancer and an electron donating organic material.

The present invention (7) is a photoelectric conversion device comprising at least a substrate, the photoelectric conversion material of the invention (5), and an electrode.

[0018] The present invention (8) is the photoelectric conversion device of the invention (7), wherein the photoelectric conversion device is a photovoltaic cell or a photosensor.

[0019] The present invention (9) is a step of mixing and stirring a solution obtained by dissolving the photoconductivity enhancer according to the invention (1) to the invention (4) and a solution obtained by dissolving an electron donating organic material. Is a method for producing a photoelectric conversion material comprising

The invention's effect

[0020] 1. A photoelectric conversion material composed of an electron acceptor made of an endohedral fullerene and an electron donor made of an electron-donating organic material comprises a photoelectric conversion material using empty fullerene as an electron acceptor. In comparison, photoconductivity is significantly enhanced.

2. By using alkali metal as an atom encapsulated in the atomic inclusion fullerene, the photoelectric conversion enhancement effect of the photoelectric conversion material is particularly high.

3. When Li is used as an encapsulated atom, the production efficiency of endohedral fullerene is increased, and industrial use is promoted by mass production of endohedral fullerene, and the production cost is reduced.

4. C, C or mixed fullerenes are available in comparison with other higher order fullerenes.

60 70

Easy and inexpensive.

5. The photoelectric conversion efficiency can be improved by constituting a photoelectric conversion device using the photoelectric conversion material of the present invention. For example, it is highly effective in improving the sensitivity of photosensors and improving the energy conversion efficiency of photovoltaic cells.

6. A photoelectric conversion material can be produced by mixing and stirring a solution in which a photoconductive enhancer is dissolved and a solution in which an electron-donating organic material is dissolved. This is effective in reducing strikes.

Brief Description of Drawings

[FIG. 1] (a) and (b) are cross-sectional views of the organic thin film solar cell of the present invention.

FIG. 2 (a) and (b) are a plan view and a cross-sectional view of a photoelectric conversion characteristic measurement sample. (C)

It is sectional drawing of the measuring apparatus of a photoelectric conversion characteristic.

[Fig. 3] Photocurrent spectrum measurement data.

FIG. 4 (a) and (b) are cross-sectional views of an endohedral fullerene production apparatus.

[Fig. 5] Mass spectrometry data of endohedral fullerenes.

FIG. 6 is a cross-sectional view of a conventional organic thin film solar cell.

Explanation of symbols

[0022] 1, 13 Glass substrate

2 Positive electrode

3 Electron donating organic materials

4 Encapsulated fullerenes

5 Negative electrode

6, 7 Wiring

11 Aluminum electrode

12 Photoelectric conversion material film

14 Dark room

15 Spectral light source

16 optics

17 Irradiation light

18 Measurement sample

19 Semiconductor parameter measuring device

31, 51 Vacuum container

32, 52 Vacuum pump

33, 53 Magnetic field generating coil

34, 54 Alkali metal sublimation oven 35, 55 Alkaline metal vapor inlet pipe

36, 56 Hot play

37, 57 Plasma flow

38, 58 Fullerene Sublimation Oven

39 Resublimation cylinder

59 Fullerene steam inlet pipe

40, 60 deposition plate

41, 61 Noise power supply

42, 62 Deposited film

101 glass substrate

102 Positive electrode

103 Electron donating organic materials

104 Negative electrode

105 Fullerene

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the meaning of each term according to the present invention will be clarified, and the best mode of the present invention will be described.

[0024] "Fullerenes" is a concept including repetitive bonds (ionic bonds, covalent bonds, etc.) of fullerenes such as fullerenes, heterofullerenes, chemically modified fullerenes, and fullerene dimers. “Fullerene” is a hollow carbon cluster material represented by C (n = 60, 70, 76, 78,...), And examples thereof include C 2. Also,

60 70

In the case of a repeated bond, atoms may be included in all fullerene units (for example, in the case of a dimer, an embodiment in which only one fullerene is included) can be mentioned.

[0025] "Atomic inclusion" is defined as a state in which atoms other than carbon are confined in a hollow portion of a cage-like fullerene molecule. The number of atoms to be included may be one or plural, but the maximum number of atoms to be included is limited to the size of the fullerene molecule and the size of the included atoms. When C includes Li, it is preferable to include one or two atoms. [0026] "Empty fullerene" is a fullerene in which atoms are not encapsulated in the hollow part of a cage-like fullerene molecule.

[0027] "Mixed fullerene" is a single carbon cluster material in which a plurality of different types of fullerenes are mixed. According to Non-Patent Document 1, when fullerene is produced by resistance heating method or arc discharge method, 70 to 85% of the fullerene produced is C, 10-1

60

5% is C, and the rest is higher order fullerene such as C, C, C, etc. Fullerene by combustion method

70 76 78 84

Also in the production of C, the weight ratio of C 1 and C 2 is larger than that of higher-order fullerene. Therefore, C, C

60 70 60 70 is easily available and inexpensive compared with other higher-order fullerenes. C

Mixed fullerenes with a strength of 60 and 70 are available on the market, including frontier carbon. C binding power

For example, an endohedral fullerene in which Li is encapsulated in the mixed fullerene as an encapsulated atom can be used as the photoconductive enhancer.

“Photoelectric conduction” refers to electric conduction caused by irradiating light. The photoconductivity enhancer is preferably an electron acceptor, an electron acceptor, a photoconductivity enhancer, or a combination thereof.

“Consisting” means “contains” t and “contains”. Therefore, the photoconductivity enhancer according to the present invention (1) may contain components other than the endohedral fullerenes.

[0030] An "electron donor" is a substance having a property (electron donating property) that allows electrons to be transferred to another substance. Electron donating organic materials include polythiophene such as poly-3-hexylthiophene (P3HT), poly p-phenylene, poly p-phenylene vinylene, polyaniline, polypyrrole, PEDOT, P30T, POPT, MDMO -High molecular weight polymers such as PPV and MEH-PPV and their derivatives are used. In addition, the electron-donating organic material is not limited to a polymer, for example, porphyrin compounds such as ZnPC, porphyrin, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, 1,1-bis {4- (Di-P-tolylamino) phenol} cyclohexane, 4,4 ', 4 "-trimethyltriphenyl-lamine, Ν, Ν, Ν', Ν'-tetrakis (P-tolyl)-P -Phenylenediamine, 1- (Ν, Ν-di-Ρ-triramino) naphthalene, 4,4'-bis (dimethylamino) -2-2'-dimethyltrimethane, Ν, Ν, Ν ', Ν '-Tetraphenyl-4,4'-diaminobiphenyl, Ν, Ν'-diphenyl-Ν, Ν'-di-m-tolyl-4 , 4'-diaminobiphenyl, N-phenolcarbazole and other aromatic tertiary amines, 4-di-P-tolylaminostilbene, 4- (di-P-tolylamino) -4 and {4- ( Di-P-tolylamino) styryl} stilbene compounds such as stilbene, triazole derivatives, oxazizazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, furanyleneamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole Derivatives, styryl anthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, polysilane-based phosphorus-based copolymers, polymer oligomers, styrylamine compounds, aromatic dimethylidin-based compounds, and polymethylthiophene are also used.

[0031] An "electron acceptor" is a substance that has the property (electron acceptability) that can easily accept electrons. According to Non-Patent Document 2, as an electron-accepting organic material, conventionally, C

60

For PCBM, MEHCN-PPV, MPP power ^!

[0032] "Photoelectric conversion material" refers to a material that converts an optical signal or optical energy into an electrical signal or electrical energy. Bulk Heterojunction type photoelectric conversion materials are produced by uniformly mixing an electron donor and an electron-accepting organic material. Electrons and holes are excited by light irradiation. Excited electrons are captured by the electron acceptor and move between the electron acceptors, and holes move between the electron donors to cause electrical conduction.

A “photoelectric conversion device” is a device that converts an optical signal or optical energy into an electrical signal or electrical energy using a photoelectric conversion material.

“Substrate” refers to a member that has a function of supporting a photoelectric conversion material, and “electrode” refers to an electrical signal or energy generated when light is applied to the photoelectric conversion material. It is an interface that outputs to.

A photoelectric conversion device that converts an optical signal or optical energy into an electrical signal is specifically defined as “one optical sensor”. Examples of the optical sensor include a digital camera, a light receiving sensor for optical communication, and a light detection switch.

[0035] A photoelectric conversion device that converts light energy into electrical energy is particularly defined as a "photocell". Photovoltaic cells include solar cells.

[0036] (Method for producing endohedral fullerenes) The endohedral fullerenes according to the present invention, for example, generate plasma by injecting encapsulated atomic vapor onto a hot plate heated in a vacuum vessel, and irradiate the generated plasma flow to a deposition plate disposed downstream of the plasma flow. It can be produced by a method of depositing endohedral fullerenes.

[0037] For example, the endohedral fullerenes according to the present invention can be produced by the production apparatus shown in FIG. 4 (a). An endohedral fullerene production apparatus includes a plasma generating unit, a fullerene introducing unit, a tubular vacuum vessel 31 having an encapsulating fullerene depositing unit, a vacuum pump 32 for exhausting the vacuum vessel 31, and a magnetic field generating coil 33 for confining plasma. Composed. First, encapsulated atomic materials such as Li are heated in an oven 34 and sublimated. The generated encapsulated atom vapor is introduced into the plasma generation section through the introduction pipe 35 and the encapsulated atom plasma is generated on the hot plate 36. The generated internal atomic plasma flows in the direction of the tube axis along a uniform magnetic field. In the fullerene introduction section, fullerenes such as C are removed by the oven 38.

60

By injecting the sublimated vapor into the plasma flow 37, the electrons that make up the plasma flow attach to the C and negative C ions are generated. Of positive atoms of encapsulated atoms and generated C

60 60 60 The plasma flow of negative ion force collides with the front surface of the deposition plate 40 to which a positive noise voltage is applied by the bias power source 41 in the inclusion fullerene deposition part, and the inclusion fullerenes accumulate on the surface of the deposition plate 40. .

[0038] The endohedral fullerenes according to the present invention can also be produced by the production apparatus shown in Fig. 4 (b). The apparatus for producing endohedral fullerenes consists of a tubular vacuum vessel 51 consisting of a plasma generation unit, fullerenes introduction unit, inclusion fullerenes deposition unit, a vacuum pump 52 for exhausting the vacuum vessel 51, and a magnetic field generating coil for confining the plasma. 53. First, the encapsulated atomic material such as Li is heated in an oven 54 and sublimated. The generated encapsulated atomic vapor is introduced into the plasma generator through the introduction pipe 55, and the encapsulated atomic plasma is generated on the hot plate 56. The generated encapsulated atomic plasma flows in the tube axis direction along a uniform magnetic field, and is applied to the deposition plate 60. At the same time, steam obtained by sublimating fullerenes such as C by the oven 58 is introduced in the fullerene introduction section disposed in front of the deposition plate 60.

60

Spray onto the deposition plate. A negative bias voltage is applied to the deposition plate 60 by a bias power source 61. Li positive ions composing the plasma by the negative noise voltage are accelerated. Then, the fullerenes deposited on the deposition plate 60 collide with each other and are contained in the fullerene molecules, and the inclusion fullerenes are deposited on the surface of the deposition plate 60.

[0039] (Purification of endohedral fullerenes)

In addition to the endohedral fullerenes, the resulting film deposited on the deposition plate includes encapsulated atoms that are not encapsulated in empty fullerenes or fullerenes. When producing a photoelectric conversion material using endohedral fullerenes as an electron acceptor, in order to increase the photoelectric conduction effect, remove substances other than endohedral fullerenes as much as possible to increase the purity of the endohedral fullerenes. Is preferred.

[0040] A method for increasing the purity of the endohedral fullerenes is to peel off the produced film from the deposition plate and form a powder, and then in the solution due to the difference in solubility between the endohedral fullerenes and substances other than the endohedral fullerenes in a specific solution. Alternatively, a method of concentrating the endohedral fullerene in a residue insoluble in the solution is used. For example, for fullerene, empty fullerene has higher solubility than Li-encapsulated fullerene, and Li-encapsulated fullerene can be concentrated by repeating the work of dissolving in toluene and collecting the residue.

[0041] From the product containing concentrated endohedral fullerenes, the endohedral fullerenes are finally isolated by HPLC (high performance liquid chromatography method) according to the difference in retention time in the column.

[0042] (Encapsulated fullerenes and photoelectric conversion film consisting of an electron-donating organic material)

Hereinafter, the best mode of the photoconductive enhancement agent according to the present invention will be described by taking electron-accepting endohedral fullerenes and electron-donating organic materials as examples. The technical scope of the present invention is not limited to the following embodiments.

[0043] FIGS. 1 (a) and 1 (b) are cross-sectional views of the organic thin-film solar cell of the present invention. The organic thin-film solar cell shown in Fig. 1 (a) is composed of a glass substrate 1, a positive electrode 2 made of a transparent material such as ITO, an electron-donating organic material 3 made of P3HT, and an endohedral fullerene that has Li-containing fullerene force 4 It is composed of a photoelectric conversion material film doped with a negative electrode 5 having A1 force.

[0044] As shown in Fig. 1 (b), light represented by hV is incident on a photoelectric conversion material made of P3HT doped with Li-containing fullerene through a glass substrate 1 and a transparent positive electrode 2. . In P3HT, an electron-hole pair is generated when excited by light energy. The generated electrons have an electron affinity. Since it is trapped by the large Li-encapsulated fullerene, the probability of recombination with holes generated simultaneously with electrons is reduced. Li @ C LUMO is lower than C LUMO, so excited electrons are

60 60

Efficiently captured by Li-encapsulated fullerene. The trapped electrons move by hopping between the Li-encapsulated fullerene molecules. The generated holes move between the P3HT electron donors by hobbing. The lifetime of electrons and holes, which are carriers for photoconduction, is increased, so that photoconduction is promoted and photocurrent is increased.

[0045] An organic solar cell is manufactured by sandwiching a thin film made of a photoelectric conversion material composed of an electron donor and an electron acceptor between an electrode 2 made of ITO and an electrode 5 made of A1. Due to the difference in the band structure of the ITO electrode 2, the photoelectric conversion film, and the A1 electrode 5, the holes generated in the photoelectric conversion film move to the ITO electrode 2 side, and the generated electrons move to the A1 electrode 5 side. When an external load (not shown) is connected between the ITO electrode 2 and the A1 electrode 5 via the wirings 6 and 7, current flows from the ITO electrode 2 to the A1 electrode 5 through the external load. When Li-encapsulated fullerene is used as an electron acceptor, Li-encapsulated fullerene has higher electron mobility than empty fullerene, and can increase photocurrent.

[0046] (Method for producing photoelectric conversion film)

A photoelectric conversion film using the photoelectric conversion material of the present invention can be produced by an extremely simple process. The powdered endohedral fullerenes produced and separated by the above-described endohedral fullerene production method and purification method are dissolved in a solvent such as carbon disulfide. The electron-donating organic material is dissolved in a solvent such as toluene. The endohedral fullerene solution and the electron donating organic material solution are agitated ultrasonically to disperse the endohedral fullerene sufficiently uniformly in the electron donating organic material.

The amount of endohedral fullerene doped is, for example, the weight percentage of Li @ C relative to P3HT.

60

Lwt% or more and 60 wt% or less is preferable. If the endohedral fullerene is too small, electrons excited by light irradiation are not efficiently captured by the endohedral fullerene, and the photocurrent cannot be increased sufficiently. In addition, the endohedral fullerene is an expensive material as compared with the electron donating organic material, and when the amount of the endohedral fullerene is increased, there is a problem that the production cost increases. Even if the number of electron donors is too small compared to the electron acceptor, the number of electron-hole pairs excited by light irradiation decreases, so that photoconductivity occurs. Of endohedral fullerenes and electron-donating organic materials It is possible to optimize the photoelectric conversion efficiency by setting the ratio within the appropriate range described above.

[0047] (Photo battery)

A photovoltaic cell such as a solar cell can be fabricated by sandwiching the photoelectric conversion film between a positive electrode and a negative electrode.

[0048] For the positive electrode, it is preferable to use an electrode material having the same or larger work function than the HOMO level of the photoelectric conversion film. Further, in view of the use as a photovoltaic cell, it is preferable that at least one of the positive electrode and the negative electrode is transparent or translucent. Examples of such electrode materials include gold (for example, in the form of a semipermeable membrane) and ITO (Indium Tin Oxide).

Next, for the negative electrode, it is preferable to use a stable electrode material having a smaller work function than the work function of the anode. For example, alloys such as aluminum, silver, Mg-In, Mg-Ag can be cited. Note that, as described above, it is preferable that at least one of the positive electrode and the negative electrode is transparent or semi-transmissive in relation to the use of the photovoltaic cell.

[0050] (Light sensor)

An optical sensor using a bulk heterojunction type photoelectric conversion film is an optical sensor that operates on a principle similar to that of animal photoreceptors, and functions as an extremely sensitive optical sensor. The number of carriers, which are excited electrons and hole power, is controlled by the difference in the light intensity incident on the optical sensor. Therefore, the electrodes arranged between the electrodes arranged at a certain interval on the photoelectric conversion film or the photoelectric conversion film are vertically moved. The incident light intensity can be measured by measuring the current, voltage, or resistance between the sandwiched electrodes.

[0051] The optical sensor manufactured using the photoelectric conversion material using the endohedral fullerene of the present invention as an electron acceptor is an optical sensor manufactured using a conventional photoelectric conversion material using an empty fullerene as an electron acceptor. In contrast, the endohedral fullerene has a higher efficiency of capturing electrons and the mobility of the electron in the endohedral fullerene is larger, so that it is possible to detect light with higher sensitivity than a conventional photosensor.

[0052] The method for manufacturing the photoelectric conversion device of the present invention is manufactured by a well-known conventional method. Those skilled in the art can appropriately set various conditions.

Example

[0053] Hereinafter, the present invention will be described in detail with reference to examples. The present invention is not limited to the following examples.

(Li-included fullerene production example)

For the production of the endohedral fullerene containing Li, a production apparatus having a structure shown in FIG. 4 (b) in which an electromagnetic coil was arranged around a cylindrical stainless steel container was used. The raw material Li is Lid made by Aldrich, and the raw material C is C made by Frontier Carbon.

60 60 was used. The vacuum vessel was evacuated to a vacuum degree of 4.2 X 10- ⁵ Pa, by the electromagnetic coil, to generate a magnetic field having a field strength 0.2 T. The encapsulated atom sublimation oven was filled with solid Li and heated to a temperature of 480 ° C to sublimate Li and generate Li gas. The generated Li gas was introduced through a gas inlet tube heated to 500 ° C and injected onto a hot plate heated to 2500 ° C. A plasma flow consisting of positive ions of Li ionized on the hot plate surface and electron force was generated, and the deposition plate was irradiated with the plasma flow. At the same time, the deposition plate was irradiated with C vapor heated and sublimated to 610 ° C in a fullerene oven. -20V bias for deposition plate

60

A voltage was applied to deposit a thin film containing endohedral fullerene on the surface of the deposition plate. After about 1 hour of deposition, a thin film with a thickness of 0.9 m was deposited.

[0055] The deposited thin film is peeled off from the deposition plate, and the powdered thin film is dissolved in a solvent containing carbon dioxide, and Li is encapsulated using HPLC !, NA! /, Fullerene and Li inclusion Fullerenes were separated.

[0056] FIG. 5 shows mass spectrometry data of Li-encapsulated fullerene produced by the above-described method for producing endohedral fullerene. The 720 peak corresponding to C and the 727 peak corresponding to ⁷ Li @ C

60 60

Observed. The measurement sample in which the peak at mass number 727 was confirmed was further dissolved in a hydrochloric acid solution, and the residue insoluble in the hydrochloric acid solution was subjected to mass spectrometry again. Appeared in the intensity. From this, Li is outside the C molecule.

It was confirmed that it was encapsulated in the interior of the C molecule.

60

[0057] <Production example 2> (Preparation of photocurrent characteristics measurement sample)

2 (a) and 2 (b) are a plan view and a cross-sectional view of a sample for measuring photoelectric conversion characteristics. In order to compare the photoelectric conversion material of the present invention with a conventional photoelectric conversion material, in addition to samples A and B (conductive polymer doped with Li-containing fullerene), sample C (empty fullerene was doped) Conductive polymer) and Sample D (non-doped conductive polymer) were prepared.

The measurement sample was prepared according to the following procedure.

(1) Samples A to D: A glass substrate 13 (18 mm X 18 mm, thickness 0.12 to 0.17 mm) was prepared, and a plurality of rectangular A1 patterns were formed on the glass substrate by vapor deposition. The no-turn interval L was set to 0.5 mm.

(2) Sample A: Toluene lwt% in which P3HT (poly 3 hexylthiophene) is dissolved 2 ml of Li2C dissolved in CS2 solution 0.4 ml (Li @ C concentration: 10 wt%), over 60 minutes Sonic stirring

60 60

It was. The prepared solution was dropped onto the A1 pattern deposition substrate prepared in (1) and spin coated at a rotational speed of 2000 rpm for 20 seconds to form a photoelectric conversion film.

(3) Sample B: 2 ml of toluene lwt% solution in which P3HT (poly 3 hexylthiophene) is dissolved 0.4 ml of CS2 solution in which 1 mg of Li®C is dissolved (Li @ C concentration: 5 wt%) for more than 60 minutes Sonic stirring

60 60

(4) Sample C: C was added to 2 ml of toluene lwt% solution in which P3HT (poly-3-hexylthiophene) was dissolved.

60

0.4 ml of CS2 solution in which 2 mg was dissolved was mixed (C concentration: 10 wt%) and ultrasonically stirred for 60 minutes. Product

60

The prepared solution was dropped onto the patterned vapor deposition substrate prepared in (1) and spin coated at a rotational speed of 2000 rpm for 20 seconds to form a photoelectric conversion film.

(5) Sample D: 2 ml of toluene lwt% solution in which P3HT (poly 3 hexylthiophene) is dissolved is dropped onto the pattern deposition substrate prepared in (1) and spin coated at a rotational speed of 2000 rpm for 20 seconds to form a photoelectric conversion film. Formed.

FIG. 2 (c) is a cross-sectional view of a photoelectric conversion characteristic measuring apparatus. Spectral light source 15 (JASCO CT10T), optical system 16 for controlling the wavelength of irradiation light, and sample 18 are placed in dark room 14. A1 putter next to each other A 100 V noise voltage was applied between the two electrodes using a semiconductor parameter measurement device 19 (Agilent 4155), and the value of the current flowing between the A1 patterns was measured. The irradiation light intensity was 25.3 W at a wavelength of 400 nm. Irradiation light intensity at each wavelength was measured, and the measured photocurrent value was corrected so that the irradiation light intensity was constant. In addition, the current value (light current) when light irradiation is not performed is measured, the dark current is subtracted from the current measurement value during light irradiation, and the current value (photocurrent) generated by light irradiation is calculated. The wavelength dependence of photocurrent was plotted.

FIG. 3 shows measurement data of the photocurrent spectrum. All of the measured photoelectric conversion films were found to have a photocurrent spectrum having a peak between 600 nm and 650 nm. For example, comparing the photocurrent at 6 OOnm,

Photoelectric conversion film Photocurrent

Li @ C 10wt% doped P3HT 45.8nA

60

Li @ C 5wt% doped P3HT 29.9nA

60

C 10wt% doped P3HT 18.5nA

60

non-doped P3HT 2.3nA

The power of being

(1) P3HT doped with 10 wt% Li @ C has a photocurrent increased approximately 20 times compared to undoped P3HT.

60

Add.

(2) P3HT doped with 10 wt% Li @ C has a photocurrent higher than that of P3HT doped with 10 wt% C.

60 60

Increase by about 2.5 times.

(3) Increasing the doping amount of Li @ C for P3HT increases the photocurrent.

60

I understood it.

Industrial applicability

[0060] 1. A photoelectric conversion material composed of an electron acceptor composed of an atom-encapsulated fullerene and an electron donor composed of an electron-donating organic material is a photoelectric conversion material using empty fullerene as an electron acceptor. In comparison, photoconductivity is significantly enhanced.

3. Inclusion fullerene with high generation efficiency of inclusion fullerene when Li is used as the inclusion atom It is effective in promoting industrial use and producing costs by mass production.

60 70

Easy and inexpensive.

6. A photoelectric conversion material can be manufactured by mixing and stirring a solution in which a photoconductive enhancer is dissolved and a solution in which an electron-donating organic material is dissolved. This simplifies the manufacturing process and reduces manufacturing costs. Is effective.

Claims

The scope of the claims

[1] Photoconductivity enhancer with the power of endohedral fullerenes.

[2] The photoconductivity enhancer according to [1], wherein the atom encapsulated in the atom-encapsulated fullerene is an alkali metal.

3. The photoconductive enhancer according to claim 2, wherein the atom encapsulated in the atom-encapsulated fullerene is Li.

[4] The fullerene according to any one of claims 1 to 3, wherein the fullerene is C 1, C 2 or a mixed fullerene thereof.

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A photoconductivity enhancer according to any one of the preceding claims.

[5] A photoelectric conversion material comprising the photoelectric conductivity enhancer according to any one of claims 1 to 4.

6. The photoelectric conversion material according to claim 5, comprising at least the photoelectric conductivity enhancer and an electron donating organic material.

[7] A photoelectric conversion device comprising at least a substrate, the photoelectric conversion material according to claim 5, and an electrode.

8. The photoelectric conversion device according to claim 7, wherein the photoelectric conversion device is a photovoltaic cell or a photosensor.

[9] A method for producing a photoelectric conversion material, comprising a step of mixing and stirring a solution in which the photoelectric enhancement agent according to any one of claims 1 to 4 is dissolved and a solution in which an electron-donating organic material is dissolved.