JP2010229541A - Molecular control film forming method and application to solar battery, el and optical switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molecular layer deposition (MLD) process having high throughput, and to provide a high-performance solar battery, an electroluminence element and an optical switch. <P>SOLUTION: The molecular region division type MLD which separates and arranges reactive gases into different molecular regions and is performed by replacing a base body or the molecular regions serves as a promising means for solving a problem. Further, the assembling of polymer chains/thin films, of which the molecular array is controlled by means of MLD into the solar battery, electroluminence element and optical switch, serves as a promising means for solving the problem. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

Detailed Description of the Invention

  The present invention relates to a polymer chain / thin film growth method (MLD) including a step of sequentially supplying a plurality of reactive molecules to a substrate and controlling the molecular arrangement, and in particular, a region in which reactive molecules are different for each type. (Hereinafter referred to as the molecular region), and moving the substrate and / or molecular region to sequentially supply multiple types of reactive molecules to the substrate, polymer chain / thin film growth method, and flowing gas between the molecular regions Polymer chain / thin film growth method in which a region (hereinafter referred to as gas curtain) is arranged, a polymer chain / thin film growth method in which a reactive molecule is carried by a carrier gas and supplied to a substrate, and a group that reacts with at least one kind of reactive molecule A polymer chain / thin film growth method in which molecules having a molecule are arranged on at least a part of the substrate, and a plurality of types of reactive molecules are sequentially supplied to the substrate to control the molecular arrangement The present invention relates to a solar cell, an electroluminescence (EL) element, and an optical switch, each of which includes a polymer chain / thin film produced by a polymer chain / thin film growth method including the following steps.

  FIG. 1 shows the principle of MLD (Non-Patent Documents 1, 2, 3, and Patent Documents 4 and 5). In the following, the case where a plate-like substrate is used as the growth substrate will be described. In this example, four types of molecules (molecules A1a, B1b, C1c, D1d) are used. Each molecule has two or more (in this example, two) reactive groups, the same type of molecule does not react, and different types of molecules are set to react and bond. By supplying multiple types of reactive molecules to the surface of the substrate in sequence, polymer chains with molecular arrangements grow. When a molecule having three or more reactive groups is introduced, the molecular wire can be branched. MLD is also possible by using ionic molecules. In this case, an electron donating molecule and an electron accepting molecule are alternately supplied to perform molecular arrangement controlled growth. Conventionally, as a method for embodying MLD, a substrate is placed in a vacuum chamber, and gasified reactive molecules are supplied one by one from the cell in time series on the surface (non-patent document). 1, 2, 3). In this case, since the time required for exchanging molecules by exhaustion takes minutes, there is a manufacturing problem that the process throughput is low. In addition, there was no solar cell or EL element containing a polymer whose molecular arrangement was controlled as a component, which had the potential for high performance.

  T.A. Yoshimura, S .; Tatsuura, and W.H. Sotoyama, "Polymer films formed with monolayer growth steps by molecular layer deposition," Appl. Phys, Lett. , Vol. 59, no. 4, pp. 482-484, 1991.   T.A. Yoshimura, S .; Tatsuura, W. et al. Sotoyama, A .; Matsuura, and T.M. Hayano, “Quantum wire and dot formation by chemical vapor deposition and molecular layer deposition of one-dimensional conjugated polymer,” Appl. Phys. Lett. , Vol. 60, no. 3, pp. 268-270, 1992.   T.A. Yoshimura, S .; Ito, T .; Nakayama, and K.K. Matsumoto, “Orientation-controlled molecule-by-molecular polymer wire, grow by the carrier-gas-type organic chemical and depletion of the population.” Phys. Lett. vol. 91, pp. 033103-1-3, 2007.   T.A. Yoshimura, E .; Yano, S .; Tatsuura, and W.H. Sotoyama, “Organic functional optical thin film, fabrication and use thereof,” US Patent 5,444,811, 1995.   Tetsuzo Yoshimura, “Polymer chain / thin film growth method”, JP 2008-216947, 2008.

Problems to be solved by the invention

  An object of the present invention is to improve process throughput in MLD, to realize a high-performance solar cell, an EL element, and an optical switch having a polymer whose molecular arrangement is controlled using MLD, and these elements Is to apply a high-throughput MLD.

Means for solving the problem

  In the polymer chain / thin film growth according to the first aspect of the present invention, reactive molecules are arranged in different molecular regions for each type, and a plurality of types of reactive molecules are sequentially transferred to the substrate by moving the substrate and / or the molecular region. It is characterized by supplying to. This eliminates the need for gas exchange and improves the process throughput.

  The polymer chain / thin film growth according to the second aspect of the present invention is characterized in that a gas curtain is arranged between the molecular regions. Thereby, mixing of the gas between molecular regions can be suppressed.

  The polymer chain / thin film growth according to the third aspect of the present invention is characterized in that reactive molecules are carried by a carrier gas and supplied to a substrate. Thereby, mixing of the gas between molecular regions can be suppressed. Further, by-products and impurities can be excluded from the polymer chain / thin film growth region by the carrier gas.

  The polymer chain / thin film growth according to the fourth aspect of the present invention is characterized in that a molecule having a substituent that reacts with at least one kind of reactive molecule is disposed on at least a part of the substrate. As a result, the polymer chain / thin film can be selectively grown on the necessary portion of the substrate.

  According to a fifth aspect of the present invention, there is provided a solar cell comprising as a component a polymer chain / thin film produced by a polymer chain / thin film growth method including a step of sequentially supplying a plurality of types of reactive molecules to a substrate and controlling the molecular arrangement, EL elements and optical switches. This makes it possible to improve the performance of these elements. Furthermore, the polymer chain / thin film growth method according to the first to fourth aspects is applied as the polymer chain / thin film growth method. Thereby, a solar cell, an EL element, and an optical switch can be manufactured with high throughput.

  The present embodiment will be described below with reference to the drawings. In each figure, the same reference numerals indicate the same elements, and duplicate descriptions are omitted. The following description explains an embodiment to which the present invention is applicable, and the scope of the present invention is not limited to this description. For clarity of explanation, the following descriptions are omitted and simplified as appropriate. Further, those skilled in the art will be able to easily change, add, and convert each element of the following embodiments within the scope of the present invention.

[First to Third Embodiments]
FIG. 2 is a conceptual diagram of a molecular region separation type MLD according to the present invention. An example where two types of reactive molecules A1a and B1b are used will be described. A molecule A region 2a where the molecule A exists and a molecule B region 2b where the molecule B exists are arranged. In order to prevent the mixing of the molecule A and the molecule B, a gas curtain is inserted between the molecule A region and the molecule B region. Because it uses N ₂ in gas flow in this example the N ₂ curtain 3. When the substrate 4 is moved, the substrate is sequentially exposed to the molecules A and B, and MLD can be performed. The MLD can be similarly performed by moving the molecular gas region instead of moving the substrate.

FIG. 3 is a schematic view of a molecular region separation type MLD according to the present invention. A plurality of types of reactive molecules are loaded into a cell (not shown), and each is heated (or cooled) to an appropriate temperature and gasified. A gas such as N ₂ , Ar, or He is introduced into these cells as a carrier gas. The reactive molecular gas is carried by the carrier gas and is ejected from the molecule A nozzle 7a and the molecule B nozzle 7b to form a molecule A region and a molecule B region, respectively. Forming the _{N 2} curtain by spraying N ₂ gas. The substrate 4 in the chamber 5 is rotated by the spin stage 8 to execute MLD.

  In the above example, the emission end of the nozzle can take various shapes such as a circle, an ellipse, a square, and a rectangle. The exit end can also be meshed. Multiple nozzles can also be installed for each molecular region and gas curtain. It is also possible to introduce reactive molecules directly without using a carrier gas. It is also possible to omit the gas curtain by arranging the molecular regions so that no molecular mixing occurs. For example, there are methods such as injecting gas in different directions and keeping the injection positions away from each other.

FIG. 4 is another schematic view of a molecular region separation type MLD according to the present invention. In this case, a large number of substrates are arranged around the spin stage 9. The nozzle for molecule A, the N ₂ curtain nozzle, and the nozzle for molecule B are arranged in order, and spraying is performed. Thereby, the molecule A region, the N ₂ curtain, and the molecule B region are formed. By moving the substrate by the spin stage, the substrate is sequentially exposed to the molecule A and the molecule B, and MLD is executed. The MLD can be similarly performed by moving the molecular gas region / N ₂ curtain by moving the nozzle instead of moving the substrate.

FIG. 5 is another schematic view of a molecular region separation type MLD according to the present invention. Although it is basically the same as the example of FIG. 4, the case where four types of reactive gases are used is illustrated. Nozzles are arranged like a nozzle for molecule A, N ₂ curtain nozzle, nozzle for molecule B, N ₂ curtain nozzle, nozzle for molecule C 7c, N ₂ curtain nozzle, nozzle for molecule D 7d, N ₂ curtain nozzle, and spraying Do. Thereby, the molecule A region, the N ₂ curtain, the molecule B region, the N ₂ curtain, the molecule C region 2c, the N ₂ curtain, the molecule D region 2d, and the N ₂ curtain are formed. Here, although the nozzle is partially drawn, in practice, a pipe is connected to the nozzle from above in the drawing or from below through a hole in the center of the stage. Excess gas is exhausted 11 by an exhaust route arranged facing each nozzle. In this case, since each reaction gas component is exhausted independently, it can be reused after appropriate purification. Alternatively, it is possible to perform collective exhaust without using independent exhaust. By moving the substrate by the spin stage, the substrate is sequentially exposed to molecule A, molecule B, molecule C, and molecule D, and MLD is executed. The MLD can be similarly performed by moving the molecular gas region and the N ₂ curtain by rotating and moving the nozzle instead of moving the substrate. By the above method, a polymer chain such as the molecular sequence A-B-C-D-A-B-C-D-A-B-... Can be formed.

  Various arrangements can be realized by controlling On / Off of each type of molecular gas injection independently. For example, when creating an array such as A-D-C-B-C-D-A-B-C-D-..., The first rotation turns the molecule A nozzle and the molecule D nozzle on. In the second rotation, the nozzle for molecule C is turned On, the third rotation is the nozzle for molecule B, the nozzle for molecule C, the nozzle for molecule D is turned on, the fourth rotation is the nozzle for molecule A, the nozzle for molecule B, the molecule The nozzle for C and the nozzle for molecule D may be turned on.

FIG. 6 is another schematic view of a molecular region separation type MLD according to the present invention. Although it is basically the same as the example of FIG. 5, in this case, the nozzles are the molecule A nozzle, the N ₂ curtain nozzle, the molecule B nozzle, the N ₂ curtain nozzle, the molecule C nozzle, and the N ₂ curtain nozzle. , Arranged in an array like a nozzle for molecule D and an N ₂ curtain nozzle to form a corresponding molecular region and an N ₂ curtain, and the substrate moves through it. Excess gas is exhausted by an exhaust route arranged facing each nozzle. In this case, since each reaction gas component is exhausted independently, it can be reused after appropriate purification. Alternatively, it is possible to perform collective exhaust without performing independent exhaust. By moving the substrate by the transfer device, the substrate is sequentially exposed to molecule A, molecule B, molecule C, and molecule D, and MLD is executed. The MLD can be similarly performed by moving the molecular gas region / N ₂ curtain by moving the nozzle instead of moving the substrate. Here, in FIG. 6, the nozzle for molecule A, the nozzle for molecule B, the nozzle for molecule C, and the nozzle for molecule D are drawn one by one, but a larger number of nozzles can be arranged. It is also possible to return the substrate that has once passed through the molecular region and repeatedly pass through the molecular region. Thereby, the total number of nozzles can be reduced. By the above method, a polymer chain such as the molecular sequence A-B-C-D-A-B-C-D-A-B-... Can be formed. Similarly to the example of FIG. 5, various arrangements can be realized by independently controlling On / Off of each type of molecular gas injection.

FIG. 7 shows an example of reaction molecules and reactions to be used. Poly-azomethine (AM), which is a conjugated polymer chain, grows by the reaction of p-phenylenediamine (PPDA) and terephthalaldehyde (TPA). A by-product is H ₂ O. In addition, a polymer chain grows by the reaction of oxalic dihydrazide (ODH) and oxalic acid (OA), and becomes a conjugated polymer poly-oxadiazole (OXD) by heat treatment at 200-300 ° C. FIG. 8 shows an example of molecular chain growth by MLD. A self-assembled monolayer (SAM) of aminoalkanethiol (11-Amino-1-undecanethiol) is formed on the gold film. The surface is covered with —NH ₂ groups. When TPA is supplied thereon, the —CHO group is bonded to the —NH ₂ group of the SAM, and the surface is covered with the —CHO group. When PPDA is supplied thereon, the —NH ₂ group is bonded to the —CHO group of SAM, and the surface is covered with the —NH ₂ group. Further, when a molecule having two —CHO groups is supplied on PPDA, the —CHO group is bonded to the —NH ₂ group, and the surface is covered with the —CHO group. Supplying molecular group -NH ₂ with two thereon -NH ₂ group is bound to the surface and -CHO are covered with -NH ₂ group. By repeating this, a molecularly arranged polymer chain is formed. Here, PPDA and TPA are heated to about 50 to 150 ° C., whereby gasification is promoted, and molecular introduction is efficiently performed. By-product H ₂ O is removed from the growth surface by the carrier gas.

  Polymer chain growth by MLD can be achieved by adjusting the substrate temperature, etc., even if there is no reactive group on the substrate surface. As is done in Atomic Layer Deposition (ALD), MLD using adsorbed gas molecules as a growth core is possible. Further, as a feature of MLD, it is possible to uniformly grow a polymer on a surface such as an uneven surface, a pore, or a three-dimensional object. Therefore, various objects other than the normal substrate can be used as the substrate.

An example in which molecular region separation type MLD is performed on a glass substrate using PPDA and TPA as reaction molecules will be described. N ₂ was used for the carrier gas and the gas curtain. The flow rate of the N ₂ curtain was 8 NL / min, the flow rate of the carrier gas was 1-4 NL / min, and the substrate was rotated at 0.25 rpm by a spin stage while exhausting with a rotary pump. As a result, poly-AM could be grown. A total of two molecular steps of growth of one PPDA molecule and one TPA molecule occurs per rotation. As a result of measuring the light absorption intensity of the poly-AM film grown at 9 rotations (18 molecular steps) and the poly-AM film grown at 20 rotations (40 molecular steps), the light absorption intensity was almost proportional to the number of steps. increased. This indicates that a molecular region separation type MLD is realized.

[Fourth Embodiment]
FIG. 9 shows an example of three-dimensional selective orientation growth by the polymer chain / thin film growth method of the present invention. A SAM 24 is formed on the gold surface and / or wall surface to produce a seed core 22. A place where SAM is not desired to be formed on gold is covered with, for example, SiO ₂ 23. Polymer wires 25 grow upward from the seed core surface and laterally from the wall surface. A desired polymer wire network 26 is constructed by distributing seed cores in a pre-designed pattern. Any seed core other than SAM can be used as long as the surface can be chemically modified. The underlayer is not limited to gold, and any material that can be chemically modified on the surface, such as glass, Si, ITO (Indium Tin Oxide), or ZnO can be used.

[Fifth Embodiment]
FIG. 10 shows a solar cell, an EL element, and an optical switch according to the present invention. A polymer wire having quantum dots 31 and / or a polymer wire having a quantum wire structure is used. In the case of a solar cell, for example, a light absorption layer made of a polymer wire having quantum dots and / or a polymer wire having a quantum wire structure is inserted between the thin film of the n-type semiconductor 32 and the thin film of the p-type semiconductor 33. When ZnO is used for the n-type semiconductor, its absorption edge is near 3.3 eV, and the amount of absorption of visible light is small. Therefore, dye sensitization is usually performed. In the present invention, visible light is absorbed and sensitized by a polymer wire having quantum dots that are tougher than a dye and / or a polymer wire having a quantum wire structure. The light absorption wavelength is variable depending on the quantum dot length. Therefore, the light absorption wavelength, that is, the sensitization spectrum can be controlled by controlling the molecular arrangement inside the polymer and changing the length of the quantum dots. The light irradiation may be performed from outside the surface, or may be guided in the surface as illustrated. The latter is advantageous when the light absorption layer is thin. The structure of this solar cell works as an organic EL as it is by applying a forward bias. Furthermore, polymer wires having quantum dots are useful as electro-optic materials for optical switches as shown in FIG. In this example, a polymer wire having quantum dots is laminated on the optical waveguide 34 as the electro-optic material 35.

FIG. 11 shows a polymer wire structure formed by controlling the arrangement of TPA, PPDA, and ODH using MLD. Poly-AM is a quantum wire, OTPTPT is connected in the order of --ODH-TPA-PPDA-TPA-PPDA-TPA ---, and OTPT is connected in the order of --ODH-TPA-PPDA-TPA ---. The wires OT are wires connected in the order of --- ODH-TPA ---, and the portion sandwiched between the ODHs is a quantum dot. The quantum dot lengths of OTPTP, OTPT, and OT are about 3 nm, 2 nm, and 0.8 nm, respectively. FIG. 12 shows absorption spectra of OTPTPT, OTPT, and OT produced by poly-AM and MLD. As the length of the quantum dot becomes shorter, the wavelength shifts shorter. This shift almost coincides with the shift derived from the molecular orbital method and the free electron model, and it can be concluded that the quantum confinement effect appears. By utilizing this effect, as described above, it works effectively as a light absorption layer of a solar cell, a light emitting layer of an EL, and an electro-optic material. As a typical oxide semiconductor-based solar cell / EL structure example, there is a laminated structure such as ITO / Cr ₂ O ₃ (p-type) thin film / poly-AM multiple quantum dots / ZnO (n-type) thin film / Al. Can be mentioned. Further, a dye-sensitized solar cell structure in which a solid or liquid electrolyte is arranged instead of a p-type semiconductor is also possible. The light absorption layer by MLD plays a role of a dye in a normal dye-sensitized solar cell. By using a molecular region separation type MLD as the MLD, the throughput is improved.

As the semiconductor material, in addition to ZnO and CrOx, for example, TiOx, WOx, IrOx, SrTiO ₃ : oxide semiconductor such as Cr—Ta, III-V group semiconductor such as GaN, carbon nanotube, polyazomethine, polythiophene, poly Organic materials such as oxadiazole, pentacene, and phthalocyanine can be used. Examples of the film forming method include sputtering, vapor deposition, chemical vapor deposition (CVD), ALD, MLD, and organic CVD. The semiconductor thin film can be formed on a growth substrate, and then peeled off from the substrate by epitaxial lift-off (ELO) or a similar technique. As a result, the film can be embedded.

  This is the concept of MLD.   1 is a conceptual diagram of a molecular region separation type MLD according to the present invention.   1 is a schematic diagram of a molecular region separation type MLD according to the present invention.   It is another schematic diagram of the molecular region separation type MLD according to the present invention.   It is another schematic diagram of the molecular region separation type MLD according to the present invention.   It is another schematic diagram of the molecular region separation type MLD according to the present invention.   This is an example of the molecules and reactions used.   It is a schematic diagram of polymer wire growth from SAM.   It is a schematic diagram of polymer wire growth from a seed core.   It is a schematic diagram of the optical switch, EL element, and solar cell by this invention.   It is the structure and energy band figure of the quantum dot and quantum wire by this invention.   It is an absorption spectrum of OTPTPT, OTPT, OT produced by poly-AM and MLD according to the present invention.

Molecule A 1a, molecule B 1b, molecule C 1c, molecule D 1d, molecule A region 2a, molecule B region 2b, molecule C region 2c, molecule D region 2d, N ₂ curtain 3, substrate 4, chamber 5, for molecule A Nozzle 7a, Nozzle for molecule B 7b, Nozzle for molecule C 7c, Nozzle for molecule D 7d, Spin stage 8, Spin stage 9, N ₂ curtain nozzle 10, Exhaust 11, Seed core 22, SiO ₂ 23, SAM 24, Polymer wire 25, polymer wire network 26, quantum dot 31, n-type semiconductor 32, p-type semiconductor 33, optical waveguide 34, electro-optic material 35

Claims (7)

  In the polymer chain / thin film growth method including the step of sequentially supplying a plurality of types of reactive molecules to the substrate and controlling the molecular arrangement, the reactive molecules are arranged in different regions (hereinafter referred to as molecular regions) for each type, A polymer chain / thin film growth method characterized by sequentially supplying a plurality of types of reactive molecules to a substrate by moving the substrate.   In a polymer chain / thin film growth method including a step of sequentially supplying a plurality of types of reactive molecules to a substrate and controlling the molecular arrangement, the reactive molecules are arranged in different molecular regions for each type, and the molecular regions are moved. A polymer chain / thin film growth method characterized in that a plurality of types of reactive molecules are sequentially supplied to a substrate by the above method.   3. The polymer chain / thin film growth method according to claim 1-2, wherein a region (hereinafter referred to as a gas curtain) in which a gas flows is arranged between molecular regions.   4. The polymer chain / thin film growth method according to claim 3, wherein the reactive molecules are carried by a carrier gas and supplied to the substrate.   4. The polymer chain / thin film growth method according to claim 1-3, wherein a molecule having a group that reacts with at least one kind of reactive molecule is disposed on at least a part of the substrate. .   A solar cell and an electroluminescence device comprising a polymer chain / thin film produced by a polymer chain / thin film growth method including a step of sequentially supplying a plurality of types of reactive molecules to a substrate and controlling the molecular arrangement.   The polymer chain / thin film growth method according to claim 6, wherein the polymer chain / thin film growth method including a step of sequentially supplying a plurality of types of reactive molecules to the substrate and controlling the molecular arrangement is the polymer chain / thin film growth method according to claim 1-5. A solar cell, an electroluminescence element, and an optical switch.

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