JP6905247B2 - Organic n-type semiconductor film and its manufacturing method - Google Patents

Description

The present invention relates to an organic n-type semiconductor film used in an organic semiconductor device such as an organic light emitting device (organic EL), an organic solar cell, and an organic transistor, and a method for producing the same.

Conductive conductors of organic semiconductor devices such as organic light emitting devices, organic solar cells, and organic transistors are generally manufactured without doping. In such a non-doped, since the conductivity is low, it is necessary to form an extremely thin thin film, but a high level of technology is required in the manufacturing process, and the cost is high. Further, it is necessary to use an electrode having a small work function for electron injection, and there is a problem that the device stability is low.

In particular, in the production by the wet method, stable doping is difficult, and among them, stable n-type doping is extremely difficult, which hinders practical use. The reason why n-type doping has been difficult so far is that stable n-type dopants are hardly dissolved in organic solvents.

On the other hand, the present inventors have developed an Evaporated Spray Deposition using Ultra dilute Solution (ESDUS) method capable of forming a polymer from an ultra-dilute solution on the order of ppm (see Patent Document 1).

Japanese Patent No. 354194

An object of the present invention is to provide an organic n-type semiconductor film having improved conductivity by improving doping efficiency, and a method for producing the same.

By using the ESDUS method developed by the present inventors, the present inventors have realized that n-type doping of a host organic semiconductor, which has been difficult in the past, can be stably performed. As a result of further diligent research, the present inventors improved the doping efficiency (increased carrier density / added dopant concentration) by adding a specific auxiliary agent that promotes charge separation together with the host organic semiconductor and the n-type dopant. , It has been found that the conductivity of an organic n-type semiconductor film can be improved. The present invention has been completed based on these findings.

That is, the present invention is as follows.
[1] An organic n-type semiconductor film containing a host organic semiconductor, an n-type dopant, and an auxiliary agent, wherein the LUMO energy level of the auxiliary agent is the LUMO energy level of the host organic semiconductor and the n-type dopant. the organic n-type semiconductor film, which lies between the energy levels.
[2] The organic n-type semiconductor film according to [1], wherein the surface free energy of the auxiliary agent is between the surface free energy of the host organic semiconductor and the surface free energy of the n-type dopant.
[3] The organic n according to [1] or [2], wherein the auxiliary agent is contained in an amount of 0.01 to 20 wt% with respect to the total amount of the host organic semiconductor, the n-type dopant and the auxiliary agent. Type semiconductor film.
[4] The organic n-type semiconductor film according to any one of [1] to [3], wherein the auxiliary agent is a low molecular weight compound having a molecular weight of 1000 or less.
[5] The organic n-type semiconductor film according to [4], wherein the auxiliary agent is basophenanthroline.
[6] The organic n-type semiconductor film according to any one of [1] to [5], wherein the host organic semiconductor is a conjugated polymer.
[7] The organic n-type semiconductor film according to [6], wherein the host organic semiconductor is a polyphenylene vinylene or a polyfluorene copolymer.
[8] The organic n-type semiconductor film according to any one of [1] to [7], wherein the n-type dopant is an alkali metal carbonate.
[9] The organic n-type semiconductor film according to [8], wherein the n-type dopant is cesium carbonate (Cs ₂ CO _3).

[10] An organic light emitting device comprising the organic n-type semiconductor film according to any one of [1] to [9].
[11] An organic solar cell comprising the organic n-type semiconductor film according to any one of [1] to [9].
[12] An organic transistor comprising the organic n-type semiconductor film according to any one of [1] to [9].

[13] The host organic semiconductor, the n-type dopant and the auxiliary agent produced by aerosolizing the raw material liquid in which the host organic semiconductor, the n-type dopant and the auxiliary agent are dissolved or dispersed in the solvent and vaporizing the solvent in the aerosol. The method for producing an organic n-type semiconductor film according to any one of [1] to [9], which comprises adhering fine particles containing an agent onto a base material to form a thin film on the base material.

The host organic semiconductor n-type semiconductor film of the present invention can realize high conductivity by improving the doping efficiency by adding an auxiliary agent.

Host organic semiconductor used in the organic n-type semiconductor film according to an embodiment of the present invention, is a diagram showing a relationship between n-type dopant and energy levels of adjuvants. It is a figure which shows the expected molecular arrangement of the host organic semiconductor, the n-type dopant and the auxiliary agent used for the organic n-type semiconductor film which concerns on Example of this invention. It is a figure which shows the energy level of the manufactured electron-only element. It is a figure which shows the JV characteristic of the manufactured element (Al / MEH-PPV: Cs ₂ CO ₃ (0.2wt%): Bphen (0-5wt%) / Al). It is a figure which shows the JV characteristic of the manufactured element (Al / MEH-PPV: Cs ₂ CO ₃ (2.0wt%): Bphen (0-10wt%) / Al) element. It is a figure which shows the CV characteristic of the element (Al / MEH-PPV: Cs ₂ CO ₃ (0.2wt%): Bphen (0.2wt%) / Al) element manufactured as the Example of this invention. It is a figure which shows the result of the motto Schottky plot of the element (Al / MEH-PPV: Cs ₂ CO _{3 (0.2wt%): Bphen (0.2wt%) / Al) element manufactured as the Example of this invention.} The prepared MEH-PPV: Cs ₂ CO ₃ (2.0wt%): Bphen (0, 0.2wt%) thin film TEM image, and the left figure shows Cs ₂ CO ₃ (2.0wt%): Bphen (0wt%). The figure on the right shows Cs ₂ CO ₃ (2.0 wt%): Bphen (0.2 wt%). The prepared MEH-PPV: Cs ₂ CO ₃ (2.0wt%): Bphen (2.0, 10.0wt%) thin film TEM image, the left figure is Cs ₂ CO ₃ (2.0wt%): Bphen (2.0wt%) The figure on the right shows Cs ₂ CO ₃ (2.0 wt%): Bphen (10.0 wt%). It is a figure which shows the JV characteristic of the manufactured element (Al / F8BT: Cs ₂ CO ₃ (0.2wt%): Bphen (0, 0.02wt%) / Al).

[Organic n-type semiconductor film]
The organic n-type semiconductor film of the present invention is a film containing a host organic semiconductor, an n-type dopant, and an auxiliary agent, and is characterized by containing an auxiliary agent. The organic n-type semiconductor film of the present invention can be suitably used as a conductive film in an organic light emitting element, an organic solar cell, an organic transistor and the like. For example, in an organic light emitting device, it can be used as a light emitting layer, an electron transport layer, or the like. In an organic solar cell, it can be used as an n-type organic semiconductor layer or the like at a pn junction. In an organic transistor, it can be used as a semiconductor active layer or the like.

(Auxiliary agent)
Auxiliaries in the organic n-type semiconductor film of the present invention, the LUMO energy level, characterized in that between the energy level of the LUMO energy level and the n-type dopant in a host organic semiconductor (see FIG. 1) .. Energy level is, n-type dopant, adjuvant, by selecting a material to be in the order of the host organic semiconductor, electrons move from the n-type dopant, occurs adjuvant, subsequent to the host organic semiconductor, doping efficiency Is expected to improve.

Further, it is preferable that the surface free energy of the auxiliary agent is between the surface free energy of the host organic semiconductor and the surface free energy of the n-type dopant. That is, it is preferable that the hydrophilicity of the auxiliary agent is between the host organic semiconductor and the n-type dopant. Due to the difference in surface free energy, it is expected that the auxiliary agent will be localized around the n-type dopant in the film, and the host organic semiconductor will surround the auxiliary agent (see FIG. 2). Therefore, it is considered that a redox reaction occurs between the n-type dopant and the auxiliary agent to cause charge transfer, and further electron transfer to the host organic semiconductor promotes charge separation.
When determining the magnitude of the surface free energy, it is not always necessary to obtain the surface free energy value itself, and the contact angles with water may be compared. If the contact angle with water is small, it can be judged that the surface free energy is large.

Auxiliary agents may be taking into account the energy level and the surface free energy of the host organic semiconductor and n-type dopants are selected appropriately.

The auxiliary agent may be a high molecular weight compound, but is preferably a low molecular weight compound having a molecular weight of 1000 or less. Specifically, as an adjunct, vasofenanthroline (Bphen), 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 2,2', 2 "-(1,3,5) -Benzinetriyl)-tris (1-phenyl-1-H-benzimidazole) (TPBi), 2- (4-Biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole, 2,2' -(1,3-Phenylene) bis [5- (4-tert-butylphenyl) -1,3,4-oxadiazole], 8-Hydroxyquinolinolato-lithium, 1,3,5-Tri (p-pyrid-3-yl) -phenyl) benzene, 1,3,5-Tri (p-pyrid-3-yl-phenyl) benzene and the like can be mentioned.

Further, the auxiliary agent is preferably contained in an amount of 0.01 to 20.0 wt%, more preferably 0.1 to 15.0 wt%, based on the total amount of the host organic semiconductor, the n-type dopant and the auxiliary agent. It is preferably contained in an amount of 0.2 to 10 wt%. Since the organic n-type semiconductor film of the present invention is usually composed of a host organic semiconductor, an n-type dopant, and an auxiliary agent, the above ratio is the content ratio of the auxiliary agent in the film.

Further, it is particularly preferable that the auxiliary agent is contained in the same amount as the n-type dopant. As a result, the aggregation of the n-type dopant in the film is suppressed, the dispersibility is improved, and the conductivity of the film can be further improved. For example, the auxiliary agent is preferably 50 to 500 wt% of the n-type dopant.

(Host organic semiconductor)
The host organic semiconductor in the organic n-type semiconductor film of the present invention may be any organic semiconductor having electron transportability, preferably a polymer having electron transportability, preferably a conjugated polymer, and has a molecular weight of 1. It is preferably a polymer compound of about 10,000 or more. Specifically, as the host organic semiconductor, polyphenylene vinylene such as methoxy-ethylhexoxy-polyphenylene vinylene (MEH-PPV), polyfluorene copolymer, polyoxydiazole, polybenzobisimidazole benzophenanthrolin, poly [(1,4) -Dibinylene phenylene) (phenylborane)] and other high molecular weight semiconductors, as well as low molecular weight semiconductors such as fullerene, pentacene, fluoropentacene, and perylene tetracarboxylic acid diimide.

As the polyfluorene copolymer, a polymer having a structural unit represented by the following general formula (1) can be exemplified.

In the general formula (1), R ¹ and R ² each independently represent an alkyl group having 1 to 10 carbon atoms, and an octyl group is particularly preferable. G represents various copolymerization units as described above, and a benzothiadiazole group is particularly preferable.

(N-type dopant)
The n-type dopant of the present invention may be any as long as it forms a charge transfer complex with the host organic semiconductor. For example, an alkali metal salt is preferable, and an alkali metal carbonate is more preferable. Specifically, in addition to carbonates such as cesium carbonate (Cs ₂ CO ₃ ), barium carbonate, calcium carbonate, strontium carbonate, radium carbonate, sodium carbonate, lithium carbonate, potassium carbonate, rubidium carbonate, franchium carbonate, barium oxide, Oxides such as calcium oxide and sodium oxide can be mentioned, and cesium carbonate (Cs ₂ CO ₃ ) is preferable because of its high stability in air.

The amount of the n-type dopant added to the host organic semiconductor is preferably 0.001 to 50 wt%, more preferably 0.01 to 10 wt%.

[Manufacturing method of organic n-type semiconductor film]
The organic n-type semiconductor film of the present invention can be produced, for example, by using the Evaporated Spray Deposition using Ultra dilute Solution (ESDUS) method developed by the present invention. A specific method is disclosed in Japanese Patent No. 354194.

That is, in the organic n-type semiconductor film of the present invention, the raw material liquid in which the host organic semiconductor, the n-type dopant and the auxiliary agent described above are dissolved or dispersed in the solvent is aerosolized, and the solvent in the aerosol is vaporized. It can be produced by adhering fine particles containing a host organic semiconductor, an n-type dopant and an auxiliary agent, which are produced in the above, onto a base material to form a thin film on the base material.

In this method, first, a raw material liquid in which a host organic semiconductor, an n-type dopant, and an auxiliary agent as raw materials are dissolved or dispersed in a solvent is previously aerosolized. That is, the raw material liquid forms an aerosol suspended in the transport gas as liquid particles (usually particles having a size of about 1 to 100 μm). Then, by vaporizing and removing the solvent from the liquid particles constituting the aerosol, the particles (usually, having a size of about 10 to 1000 nm), which are substantially composed of only the host organic semiconductor, the n-type dopant and the auxiliary agent, have a smaller particle size. Particles) are generated, and the fine particles are sprayed (sprayed) onto the surface of the substrate to adhere them, thereby forming a thin film on the substrate.

Examples of the solvent used in the ESDUS method include tetrahydrofuran (THF), 1,4 dioxane, toluene, xylene, chlorobenzene, dichlorobenzene, chloroform, methylene chloride, acetone, methyl ethyl ketone, N, N dimethylformamide, N methylmorpholine and ethyl acetate. , Butyl acetate, methanol, ethanol, isopropanol, water and the like. In the ESDUS method, it is preferable that the raw material is dissolved or dispersed in the organic solvent at a concentration of about 0.001% or more. Therefore, it is preferable to select the raw material and the organic solvent so as to have such a concentration.

In the production of the organic n-type semiconductor film of the present invention, a conventionally known film forming method such as a spin coating method or an inkjet method may be used in addition to the ESDUS method.

Examples of the present invention are shown below, but the scope of the present invention is not limited thereto.

[Example 1]
1. 1. Outline of the experiment In order to verify the effect of adding an auxiliary agent to an organic n-type semiconductor, an electron-only element in which only electrons move as carriers was prepared and its characteristics were evaluated.

Poly [2-methoxy-5- (2-ethylhexyloxy) -1, 4-phenylenevinylene] (MEH-PPV, manufactured by Aldrich, HOMO: 5.2eV, LUMO: 3.1eV) is used as the host organic semiconductor (host polymer). board. As the n-type dopant, cesium carbonate (Cs ₂ CO ₃ , manufactured by Japan High Purity Chemical Company, work function 2.96 eV) was used. In addition, basophenanthroline (Bphen, manufactured by Aldrich, HOMO: 6.4eV, LUMO: 3.0eV) was used as an auxiliary agent (low molecular weight electron transporting additive). MEH-PPV is a bipolar transport material, and it has been confirmed that n-type doping of _{Cs 2} CO _{3 improves current density and doping efficiency.}

Here, as shown in FIG. 1, LUMO energy level of the MEH-PPV is a host organic semiconductor is 3.1 eV, energy levels of Cs ₂ CO ₃ is an n-type dopant, 2.96EV The LUMO energy level of the auxiliary agent Bphen is 3.0 eV. That, LUMO energy level of the auxiliary agent is between energy level of LUMO energy level and the n-type dopant in a host organic semiconductor.

Moreover, when the contact angles of MEH-PPV, which is a host organic semiconductor, and Bphen, which is an auxiliary agent, with respect to water were measured, MEH-PPV was about 93 ° and Bphen was about 42 °. _{Since Cs 2} CO ₃ which is an n-type dopant has high solubility in water, the relationship between these surface free energies is "Cs ₂ CO ₃ >Bphen>MEH-PPV", and the auxiliary agent ( The surface free energy of Bphen) is between the surface free energy of the host organic semiconductor and the surface free energy of the n-type dopant. Due to this relationship between the surface free energies, it is expected that each molecule will have the arrangement shown in FIG. 2 in the produced film.

2. Fabrication of Electron-Only Device by ESDUS Method The configuration of the device manufactured as an example of the present invention is "Al (50 nm) / MEH-PPV: Cs ₂ CO ₃ : Bphen (110 nm) / Al (50 nm)". The configuration of the device manufactured as a comparative example is "Al (50 nm) / MEH-PPV: Cs ₂ CO ₃ (110 nm) / Al (50 nm)". FIG. 3 shows an energy level diagram of the manufactured electron-only element.

(Preparation of solution)
29.4 mg of MEH-PPV was added to 50 mL of tetrahydrofuran (hereinafter, THF), and the mixture was stirred at 50 ° C. and 500 rpm overnight. This was added to THF 3L and mixed. At this time, the concentration of MEH-PPV with respect to THF is 11 ppm. _{Furthermore, Cs 2} CO ₃ (purity 99.999%) with a weight ratio of 0.2 and 2.0 wt% to MEH-PPV and Bphen with a weight ratio of 0.2, 2.0 and 10.0 wt% were added to 1 mL of dehydrated ethanol, respectively. And stirred at 50 ° C. and 500 rpm overnight. Due to its deliquescent property, _{all Cs 2} CO ₃ was handled in the glove box. 1 mL of this ethanol solution in which Cs ₂ CO ₃ and B phen were dissolved was added to the MEH-PPV solution and stirred. Table 1 shows the conditions for solution adjustment.

_{Hereinafter, the weight ratio of Cs 2} CO ₃ or Bphen to MEH-PPV is referred to as a doping concentration. Therefore, _{the doping concentration of Cs 2} CO ₃ is 0.2, 2.0 wt%, and the doping concentration of Bphen is 0.2, 2.0, 5.0, 10.0 wt%.

(Manufacturing of element)
An Al electrode (50 nm) patterned through a mask as a lower electrode was deposited on a glass substrate. Furthermore, the MEH-PPV: Cs ₂ CO ₃ layer or the MEH-PPV: Cs ₂ CO ₃ : Bphen layer was formed into a 110 nm film using the ESDUS method. The film formation by the ESDUS method was performed using a slit type nozzle. Table 2 shows the film forming conditions of the ESDUS method. Finally, the Al electrode of the upper electrode was deposited by 50 nm through the mask so that the cross point was 4 mm ^2. From the vapor deposition of the lower electrode to the measurement, the vacuum state was maintained in the vapor deposition apparatus EO-6 (manufactured by Eiko Engineering).

3. 3. Confirmation of the effect of the auxiliary agent (1) Current density-voltage characteristics _{JV of the manufactured element (Al / MEH-PPV: Cs 2} CO ₃ (0.2wt%): Bphen (0 to 5wt%) / Al) shown in Fig. 4. The characteristics are shown, and FIG. 5 shows the JV characteristics of the manufactured element (Al / MEH-PPV: Cs ₂ CO ₃ (2.0 wt%): Bphen (0 to 10 wt%) / Al). JV characteristics were evaluated using a Keithley 238 source meter.

FIG. 4 is a diagram when Cs ₂ CO ₃ is doped at a concentration of 0.2 wt%. In any case, when Bphen is added, compared with the case where Bphen, which is an auxiliary agent, is not added (non-doping). The electron density was also high. In particular, the current density when Bphen was doped in 0.2 wt% was the highest, which was about an order of magnitude higher than that when Bphen was not added.

FIG. 5 is a diagram when Cs ₂ CO ₃ is doped at a concentration of 2.0 wt%. In any case, when Bphen is added, compared with the case where Bphen, which is an auxiliary agent, is not added (non-doping). The electron density was also high. In particular, the current density when Bphen was doped at 2.0 wt% was the highest, which was about an order of magnitude higher than that when Bphen was not added.

(2) Calculation of doping efficiency by CV measurement
CV of the element of the example (Al / MEH-PPV: Cs ₂ CO ₃ (0.2wt%): Bphen (0.2wt%) / Al) using Solartron SI 1260 Impedance / gain-phase analyzer and Solartron dielectric interface 1296 The characteristics were measured, and the carrier density was calculated by the Mott Schottky plot using the following formula (1).
FIG. 6 shows the CV characteristics, and FIG. 7 shows the results of the Mott Schottky plot.

Here, V _bi is the built-in potential, V is the applied voltage, q is the elementary charge, ε ₀ is the permittivity of the vacuum, ε _r is the relative permittivity of the MEH-PPV thin film, and N _D is the electron density.

The electron density calculated from the Mottshot key plot is 1.0 × 10 ²⁴ [m ^-3 ], which is about 2 compared to the electron density 6.2 × 10 ²³ [m ^-3 _{] of an element doped with only Cs 2} CO _{3 by 0.2 wt%.} The value was doubled, and it became clear that the improvement in electron density brought about the improvement in current density.

In addition, as a result of calculating the doping efficiency from these values, in _{the device of the comparative example in which only Cs 2} CO ₃ was doped by 0.2 wt%, 16.5% was doped, and _{in addition to Cs 2} CO ₃ 0.2 wt%, Bphen was doped by 0.2 wt%. In the example device, it was 27%, demonstrating an improvement in doping efficiency.

_{(3) TEM measurement MEH-PPV: Cs 2} CO ₃ (2.0wt%): Bphen (0) produced using a transmission electron microscope JEM-2100XS (JEOL Ltd.) to investigate the aggregation state of dopants. , 0.2, 2.0, 10.0wt%) A TEM image of the thin film was taken. The captured TEM images are shown in FIG. 8 (Bphen 0, 0.2 wt%) and FIG. 9 (Bphen 2.0, 10.0 wt%).

In _{contrast to Cs 2} CO ₃ 2.0 wt%, the same degree of aggregation was observed in both the Bphen-undoped thin film and the 0.2 wt% -doped thin film. However, aggregation was suppressed in the thin film doped with 2.0 wt% of Bphen, which had the highest current density, and aggregation occurred again in the thin film doped with 10 wt% of Bphen.

[Example 2]
1. 1. Outline of the experiment Poly (9,9'-dioctylfluorene-alt-benzothiadiazole) (F8BT, manufactured by Lumitec, HOMO: 5.9eV, LUMO: 3.5eV) was used as the host organic semiconductor (host polymer) in the same manner as in Example 1. _{, Cesium carbonate (Cs 2} CO ₃ , manufactured by Nippon High Purity Chemical Co., Ltd., work function 2.96 eV) is used as an n-type dopant, and vasophenantroline (Bphen, manufactured by Aldrich) as an auxiliary agent (small electron transporting additive). , HOMO: 6.4eV, LUMO: 3.0eV) was used to verify the effect of adding an auxiliary agent to organic n-type semiconductors. F8BT has been confirmed to be an electron transporting material.

Here, the LUMO energy level of F8BT, which is a host organic semiconductor, is 3.5 eV. Since as shown in Example 1, energy levels of Cs ₂ CO ₃ is an n-type dopant is 2.96EV, LUMO energy level of Bphen an auxiliary agent is 3.0 eV, LUMO energy level of the auxiliary agent (Bphen) is between energy level of LUMO energy level and the n-type dopant in a host organic semiconductor.

The contact angle of F8BT with water is about 95 °, the surface free energy is in the order of "Cs ₂ CO ₃ >Bphen>F8BT", and the surface free energy of the auxiliary agent (Bphen) is the surface of the host organic semiconductor. It is between the free energy and the surface free energy of the n-type dopant.

2. Fabrication of Electron-Only Device by ESDUS Method The configuration of the device manufactured as an example of the present invention is "Al (50 nm) / F8BT: Cs ₂ CO ₃ : Bphen (110 nm) / Al (50 nm)". The configurations of the devices manufactured as comparative examples are "Al (50nm) / F8BT: Cs ₂ CO ₃ (110nm) / Al (50nm)" and "Al (50nm) / F8BT (110nm) / Al (50nm)". Is.

(Preparation of solution)
29.4 mg of F8BT was added to 4 mL of chlorobenzene and stirred at 50 ° C. and 500 rpm overnight. This was stirred with an ultrasonic cleaner for 1 hour, added to 3 liters of THF and mixed. At this time, the concentration of F8BT with respect to THF is about 11 ppm. _{Furthermore, Cs 2} CO ₃ (purity 99.999%) adjusted to a weight ratio of 0.02 wt% to F8BT and Bphen adjusted to 0.02 wt% were added to 1 mL of dehydrated ethanol, respectively, and stirred overnight at 50 ° C. and 500 rpm. did. Due to its deliquescent property, _{all Cs 2} CO ₃ was handled in the glove box. 1 mL of an ethanol solution in which Cs ₂ CO ₃ and B phen were dissolved was added to the F8BT solution and stirred. Hereinafter, _{the weight ratio of Cs 2} CO ₃ to Bphen to F8BT is referred to as a doping concentration. Therefore, _{the doping concentration of Cs 2} CO ₃ is 0.02 wt%, and the doping concentration of Bphen is 0.02 wt%.

(Manufacturing of element)
An Al electrode (50 nm) patterned through a mask as a lower electrode was deposited on a glass substrate. Furthermore, F8BT layer with ESDUS method, F8BT: Cs ₂ CO _{3 layer, F8BT: Cs 2 CO 3:} Bphen layer was 80nm film formation, respectively. The film formation by the ESDUS method was performed using a slit type nozzle. Table 3 shows the film forming conditions of the ESDUS method. Finally, the Al electrode of the upper electrode was deposited by 50 nm through the mask so that the cross point was 4 mm ^2. From the vapor deposition of the lower electrode to the measurement, the vacuum state was maintained in the Eiko Engineering vapor deposition apparatus EO-6.

3. 3. Confirmation of the effect of the auxiliary agent (1) Current density-voltage characteristics _{The JV characteristics of the manufactured element Al / F8BT: Cs 2} CO ₃ (0, 0.02wt%): Bphen (0, 0.02wt%) / Al are shown in Fig. 10. Is shown. JV characteristics were evaluated using a Keithley 238 source meter.

As shown in FIG. 10, the current density of the device obtained by doping 0.02 wt% of Bphen with respect to the doping concentration of 0.02 wt% of _{Cs 2} CO _{3 is the largest, which is about two orders of magnitude higher than that of the device containing only F8BT (F8BT only).} It increased by about an order of magnitude compared to _{the device containing only Cs 2} CO ₃ 0.02 wt% _{without adding Bphen (Cs 2} CO _{3 0.02 wt% only).}

The organic n-type semiconductor film of the present invention is industrially useful because it can be suitably used as a conductive film for organic light emitting devices, organic solar cells, organic transistors, and the like.

Claims (13)

An organic n-type semiconductor film containing a host organic semiconductor, which is a polymer having electron transportability, an n-type dopant, and an auxiliary agent.
The LUMO energy level of the auxiliary agent, an organic n-type semiconductor film, which is between the energy level of the LUMO energy level and the n-type dopant in a host organic semiconductor. The organic n-type semiconductor film according to claim 1, wherein the surface free energy of the auxiliary agent is between the surface free energy of the host organic semiconductor and the surface free energy of the n-type dopant. The organic n-type semiconductor film according to claim 1 or 2, wherein the auxiliary agent is contained in an amount of 0.01 to 20 wt% with respect to the total amount of the host organic semiconductor, the n-type dopant and the auxiliary agent. The organic n-type semiconductor film according to any one of claims 1 to 3, wherein the auxiliary agent is a low molecular weight compound having a molecular weight of 1000 or less. The organic n-type semiconductor film according to claim 4, wherein the auxiliary agent is basophenanthroline. The organic n-type semiconductor film according to any one of claims 1 to 5, wherein the host organic semiconductor is a conjugated polymer. The organic n-type semiconductor film according to claim 6, wherein the host organic semiconductor is a polyphenylene vinylene or a polyfluorene copolymer. The organic n-type semiconductor film according to any one of claims 1 to 7, wherein the n-type dopant is an alkali metal carbonate. The organic n-type semiconductor film according to claim 8, wherein the n-type dopant is cesium carbonate (Cs ₂ CO _3). An organic light emitting device comprising the organic n-type semiconductor film according to any one of claims 1 to 9. An organic solar cell comprising the organic n-type semiconductor film according to any one of claims 1 to 9. An organic transistor comprising the organic n-type semiconductor film according to any one of claims 1 to 9. Contains the host organic semiconductor, n-type dopant and auxiliary agent produced by aerosolizing the raw material liquid in which the host organic semiconductor, n-type dopant and auxiliary agent are dissolved or dispersed in the solvent and vaporizing the solvent in the aerosol. The method for producing an organic n-type semiconductor film according to any one of claims 1 to 9, wherein a thin film is formed on the base material by adhering the fine particles to the base material.

Images