KR20110027965A - Photo sensor comprising three-dimensional carbon nano tube networks, method for manufacturing the same - Google Patents

Abstract

PURPOSE: An optical sensor including three-dimensional carbon nano-tube network and a method for manufacturing the same are provided to improve the productivity by minimizing interference or interaction between electrodes and nano-materials. CONSTITUTION: An optical sensor including three-dimensional carbon nano-tube network includes a silicon electrode equipped with nano-rods or nano-holes, a counter electrode, and three dimensional carbon nano-tube network. The three dimensional carbon nano-tube network is parallelly floated in the nano-holes or between adjacent nano-rods. An optical conversion material is attached on the surface of the carbon nano-tube. The optical conversion material is quantum-dot compounds.

Description

Photoelectric sensor comprising three-dimensional carbon nanotube networks, method for manufacturing the same

The present invention relates to an optical sensor including a three-dimensional carbon nanotube network, and more particularly, to an optical sensor including a three-dimensional carbon nanotube network having a high photocurrent density and fast response speed, and a method of manufacturing the same.

An optical sensor is a carrier such as an electron or a hole in a material formed by an absorbed photon, and current is generated by the flow of the carrier to measure optical power or use it as a photoelectric switch. Say something. In general, an optical sensor includes a light transmitting part that emits light and a light receiving part that receives the changed light. Also, the light receiving part is also called a light receiving element, and the light receiving element includes a photodiode or a phototransistor. In the broad sense, an optical sensor is operated by light emitted by an object even without a light emitting part, an output is an analog output that is proportional to the amount of light input rather than an on / off signal, and multiple sensor elements are used such as an image sensor. This concept includes the inspection of dimensions and the detection of defects.

The conventional optical sensor has a low photocurrent density and requires a complicated manufacturing process such as requiring a source and a drain electrode during manufacturing. In the case of an organic optical sensor, there is a problem that the response speed is low.

For example, Korean Patent Publication No. 663326 discloses a photoconductive composite nanotube and describes that it can be used for an optical sensor operating in the visible and ultraviolet regions by using the same, but the sensitivity and the response speed are poor. There was this.

Recently, researches on optical sensors using nanowires or quantum dots have been conducted to improve the sensitivity and response speed of optical sensors, which are characteristic of nanomaterials such as large surface area, small size, and uniform physical properties of nanomaterials. This is because the characteristics of the conventional sensor can be greatly improved. However, the sensor using the nanomaterial can be classified into two types. The first is a type in which a single or a small number of nanowire sensing materials are placed in a specific region on the substrate, and the other is a nanowire composed of a plurality of nanowires. Randomly placed on the substrate using the aggregates. In the case of the former, there is a problem in that the productivity is low because the manufacturing process is complicated, such as the position of the nanowire to be checked using an electron scanning microscope or an atomic force microscope in order to contact the sensing electrode. In addition, in the latter case, as a plurality of nanowire aggregates are randomly arranged, the detection characteristics are not only affected by the interference or interaction between the nanowire sensing material itself but also by the interference or interaction with the substrate to which the nanowire aggregate is attached. There was a problem of deterioration. For example, Korean Patent Laid-Open Publication No. 2005-90285 discloses a nanowire optical sensor having improved resolution by measuring chemiluminescence and chemical fluorescence using a nanowire, but conducting a semiconductor nanowire between two metal electrodes. Since the manufacturing process is quite complicated and the optical sensor itself is a two-dimensional form, there is a problem in that the sensitivity and the reaction speed are lowered. In Korean Patent Laid-Open No. 2008-52297, a physical support is provided between two sensing electrodes. Float-type nanowire sensor including a nanowire sensing material is disclosed, but there was a problem that the manufacturing process is complex and production efficiency is low.

Accordingly, the first problem to be solved by the present invention is to provide an optical sensor having excellent sensitivity and response speed by minimizing the interference or interaction between the electrode and the nanomaterial, and a simple manufacturing process.

In addition, a second problem to be solved by the present invention is to provide a method of manufacturing the optical sensor.

The present invention to solve the first technical problem,

A silicon electrode in which nanorods or nano holes are formed;

An opposite electrode facing the silicon electrode; And

It comprises a three-dimensional network of carbon nanotubes floated horizontally in parallel between the nano-rods adjacent to each other in the silicon electrode or inside the nano-holes, the surface of the carbon nanotubes is attached to the photosensitive compound An optical sensor including a carbon nanotube three-dimensional network is provided.

According to an embodiment of the present invention, the photoelectric conversion material is preferably a quantum dot compound, the quantum dot compound is MgO, MgS, MgSe, MgTe, CaO, CaS, CaSe, CaTe, SrO, SrS, SrSe, SrTe, BaO , BaS, BaSe, BaTE, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgO, HgS, HgSe, HgTe, Al ₂ O ₃ , Al ₂ S ₃ , Al ₂ Se ₃ , Al ₂ Te ₃ , Ga ₂ O ₃ , Ga ₂ S ₃ , Ga ₂ Se ₃ , Ga ₂ Te ₃ , In ₂ O ₃ , In ₂ S ₃ , In ₂ Se ₃ , In ₂ Te ₃ , SiO ₂ , GeO ₂ , SnO ₂ , SnS, SnSe, SnTe, PbO, PbO ₂ , PbS, PbSe, PbTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, BP, Si, Ge, In _x Ga _(1-x) As (where 0 <x ≦ ₁ ), SiGe, In _n Ga _(1-n) N (where 0 < _n ≦ 1) and any one selected from the group consisting of core / shell structures thereof The above compound may be sufficient.

According to another embodiment of the present invention on the surface of the quantum dot compound any one functional group selected from the group consisting of -OH, = O, -O-, -SS-, -SH, -P = O, -P and -PH It is preferred to be coated with a compound having

In addition, the quantum dot compound may have various sizes and shapes.

According to another embodiment of the present invention, the optical sensor according to the present invention may further include an electrolyte layer between the silicon electrode and the counter electrode.

According to a preferred embodiment of the present invention, the carbon nanotube three-dimensional network has a density per space of more than 1.5 / ㎛ ³ and the density per height of the carbon nanotubes formed between the pair of the nanorods or inside the nano holes is 3 Can be at least / μm.

According to another aspect of the present invention,

(a) preparing a Fe-Mo dicatalyst solution;

(b) modifying the surface with Si-OH by performing a piranha treatment, a UV-ozone treatment, or an oxygen plasma treatment on a silicon substrate on which nanorods or nano holes are formed;

(c) immersing the surface modified silicon substrate in the dicatalyst solution to adsorb the dicatalyst metal;

(d) manufacturing a silicon electrode on which carbon nanotubes having a three-dimensional network structure are formed by supplying a carbon source gas on the substrate; And

(e) providing a method of manufacturing an optical sensor comprising a three-dimensional carbon nanotube network comprising immersing the silicon electrode in a photoelectric conversion material solution and attaching the photoelectric conversion material to the surface of the carbon nanotubes.

According to one embodiment of the present invention, the Fe-Mo dicatalyst solution may include Fe (NO ₃ ) ₃ .9H ₂ O and an aqueous solution of Mo salt.

In addition, the concentration ratio of Fe and Mo in the Fe-Mo dicatalyst solution is preferably 5: 1 to 0.5: 1.

According to another embodiment of the present invention, the immersing the silicon substrate in the dicatalyst solution may be performed in parallel with the ultrasonic treatment.

According to another embodiment of the present invention, after heat treating the substrate on which the bicatalyst metal is adsorbed, NH ₃ or hydrogen gas may be supplied to reduce the catalytic metal.

In addition, the carbon source gas may be any one or more selected from the group consisting of methane, ethylene, acetylene, benzene, hexane, ethanol, methanol and propanol.

According to a preferred embodiment of the present invention, the height of the nanorods is 2 to 200㎛, the interval between the nanorods is 50 to 2000nm, the long-to-short ratio of the nanorods is preferably 2 to 100.

In addition, the depth of the nano-holes is 2 to 200㎛, the interval between the nano-holes may be 50 to 2000nm, the long-to-short ratio of the nano-holes may be 2 to 100.

In addition, the number of carbon nanotubes connected to two adjacent rods adjacent to each other or horizontally formed inside the nano holes to form a three-dimensional network may be 10 or more.

According to a preferred embodiment of the present invention, the photoelectric conversion material may be a quantum dot compound, the photoelectric conversion material solution may be a surface-modified quantum dot compound solution.

According to the present invention, by directly growing the carbon nanotubes floated horizontally in parallel between the silicon nanorods or inside the nano holes, the density of the carbon nanotubes is not only high per space, but the ends of the carbon nanotubes are conductive substrates. (Silicone electrode) Directly connected with itself, the conductivity is improved, and since the nanorods or nano holes are formed in the silicon electrode, the light reflectance is reduced, so that the overall photoelectric conversion efficiency can be increased, so that the photosensitivity and the response speed of the optical sensor are increased. great. In addition, by changing the photoelectric change material, it is possible to manufacture an optical sensor that operates in the infrared, visible, as well as the ultraviolet region, or a wide range of broadband regardless of the wavelength region in a simple process.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

The optical sensor including a carbon nanotube three-dimensional network according to the present invention comprises a silicon electrode formed with nanorods or nanoholes; An opposite electrode facing the silicon electrode; And a three-dimensional network of suspended carbon nanotubes horizontally grown in parallel between the nanorods adjacent to each other in the silicon electrode or inside the nano holes, wherein a photoelectric conversion material is formed on the surface of the carbon nanotubes. It is characterized by being attached. In addition, the density per space of the carbon nanotubes floated horizontally in parallel between the silicon nanorods or inside the nano holes is high, and the ends of the carbon nanotubes are directly connected to the conductive substrate (silicon electrode) to improve conductivity. There is an advantage. On the other hand, the silicon electrode is not a two-dimensional plane, but because the nano-rods or nano-holes are formed, the light reflectance is reduced, so that the overall photoelectric conversion efficiency can be increased, and the three-dimensional formation is formed to act as a guide of the electron flow to move It also has the advantage of speed and response speed.

On the other hand, the manufacturing method of the optical sensor according to the present invention comprises the steps of (a) preparing a Fe-Mo dicatalyst solution; (b) modifying the surface with Si-OH by performing a piranha treatment, a UV-ozone treatment, or an oxygen plasma treatment on a silicon substrate on which nanorods or nano holes are formed; (c) immersing the surface modified silicon substrate in the dicatalyst solution to adsorb the dicatalyst metal; (d) manufacturing a silicon electrode on which carbon nanotubes having a three-dimensional network structure are formed by supplying a carbon source gas on the substrate; And (e) attaching the photoelectric conversion material to the surface of the carbon nanotubes by immersing the silicon electrode in a photoelectric conversion material solution, and uniformly dense three-dimensional carbon nanostructures to the base as well as the top of the nanorods or nanoholes. Since the tube network can be formed, there is no need to purify, cut or disperse the carbon nanotubes separately by a post-process. Therefore, the productivity is improved because there is no need to adjust the position of the carbon nanotubes through an electron address microscope, etc., and since the carbon nanotube composites are not randomly dispersed, the problem of sensitivity deterioration due to mutual interference can also be solved.

In the configuration of the present invention, the three-dimensional network of single-walled carbon nanotubes floated between the nanorods made of silicon or inside the nanoholes has the advantages of high conductivity, high current density, and ballistic conductance. The surface area of the silicon electrode is very large. Therefore, the optical sensor according to the present invention has excellent photoelectric conversion efficiency.

In the present invention, the nanorods and nanoholes are not particularly limited in the distance between the rods and holes, and may be, for example, in a range of 10 nm or more to several tens of μm. If the spacing between adjacent nanoholes is several tens of nanometers, the portion of the substrate that exists in the gap between the nanoholes and adjacent nanoholes has a nanorod shape.

The density per space of the carbon nanotube three-dimensional network used in the present invention is more than 1.5 / ㎛ ³ , the density per height of the carbon nanotubes formed between a pair of the nanorods or inside the nano-holes is 3 / ㎛ or more It is preferable. As a result, the space-per-density of the carbon nanotubes floated horizontally in parallel is greatly improved, and ultimately, the photoelectric conversion material attached thereto can be attached with high density.

In the optical sensor according to the present invention, a dye, a quantum dot compound, or a mixture thereof used in a conventional dye-sensitized solar cell may be used as a photoelectric conversion material. Examples of the dye include ruthenium complexes, xanthine dyes, isine dyes, phenosafranin, basic dyes such as capriblue, thiocin and methylene blue, porphyrin compounds such as chlorophyll, zinc porphyrin, magnesium porphyrin, other azo dyes, Phthalocyanine compounds, complexes such as Ru trisbipyridyl, anthraquinone dyes, polycyclic quinone dyes and the like can be used. On the other hand, the quantum dot compound includes a compound consisting of a first element selected from Group 2, 12, 13 and 14 and a second element selected from Group 16; A compound consisting of a first element selected from Group 13 and a second element selected from Group 15; And at least one compound selected from the group consisting of compounds selected from Group 14, and specific examples thereof include MgO, MgS, MgSe, MgTe, CaO, CaS, CaSe, CaTe, SrO, SrS, SrSe, SrTe , BaO, BaS, BaSe, BaTE, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgO, HgS, HgSe, HgTe, Al ₂ O ₃ , Al ₂ S ₃ , Al ₂ Se ₃ , Al ₂ Te ₃ , Ga ₂ O ₃ , Ga ₂ S ₃ , Ga ₂ Se ₃ , Ga ₂ Te ₃ , In ₂ O ₃ , In ₂ S ₃ , In ₂ Se ₃ , In ₂ Te ₃ , SiO ₂ , GeO ₂ , SnO ₂ , SnS, SnSe, SnTe, PbO, PbO ₂ , PbS, PbSe, PbTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, BP, Si, Ge, In _x Ga _(1-x) As (where 0 <x ≦ ₁ ), SiGe, In _n Ga _(1-n) N (where 0 < _n ≦ 1) and core / shell structures thereof Any one or more compounds can be mentioned. The quantum dot compound may have a diameter of 1 to 10 nm, and when the quantum dot compounds having various sizes and shapes are mixed and used, the quantum dot compounds may absorb light in various wavelength ranges and thus may be used as optical sensors in a wide band band. Specifically, as the size of the quantum dot compound is smaller, the light absorption spectrum is shifted toward the shorter wavelength. The shape of the quantum dot compound may be various, such as dot, rod, tetra pot. In addition, the quantum dot compound may be a single material, but two or more kinds of materials may be mixed and used, and it is preferable to use quantum dot compounds having low energy, which generate a lot of light while simultaneously absorbing light. That is, in the present invention, the light conversion efficiency can be improved by varying the material, size, and shape of the quantum dot compound.

On the other hand, since the silicon itself as well as carbon nanotubes show photosensitivity in the infrared region, when the quantum dot compound uses a material having photosensitivity in the infrared region, it may be used as an infrared light sensor. For example, InGaAs, GeSi, or InGaN. By using a quantum dot compound made of such, it is possible to manufacture an infrared light sensor with excellent efficiency. In addition, when the quantum dot compound made of ZnO is used, an optical sensor showing optical sensitivity in the ultraviolet region may be manufactured. When the quantum dot compound made of CdSe is used, an optical sensor showing optical sensitivity in the visible region may be manufactured.

In order for the quantum dot compound to adhere well to the surface of the carbon nanotube, the surface of the quantum dot compound includes -OH, = O, -O-, -SS-, -SH, -P = O, -P, and -PH. It is preferred to be coated with a compound having any one functional group selected from the group. The compound having the functional group is not particularly limited, but in order to efficiently conduct electron transfer, the compound should be as short as possible and preferably do not absorb light.

Any counter electrode used in the present invention can be used as long as it is a conductive material, but any insulating material can be used as long as the conductive layer is provided on the side facing the silicon electrode. However, it is preferable to use an electrochemically stable material as an electrode, and it is preferable to use platinum, gold, carbon, etc. specifically ,. In addition, for the purpose of improving the catalytic effect of redox, it is preferable that the surface facing the silicon electrode is increased in a microstructure, for example, it is preferable that platinum is in a platinum black state and carbon is in a porous state. The platinum black state can be formed by platinum anodization, platinum chloride treatment, or the like, and carbon in the porous state can be formed by sintering carbon fine particles or firing organic polymers.

The optical sensor according to the present invention may further include an electrolyte layer between the silicon electrode and the counter electrode, wherein the electrolyte layer is formed of an electrolyte, and the electrolyte may be an acetonitrile solution of iodine, but is not limited thereto. It can be used without limitation as long as it has a hole conduction function.

1 shows a schematic diagram of an optical sensor manufactured according to an embodiment of the present invention. An n-type silicon substrate formed with a three-dimensional carbon nanotube network manufactured according to the present invention is included below, and a quantum dot compound is attached to the three-dimensional carbon nanotube. On the other hand, I ⁻ / I ₃ ⁻ is an electrolyte, and I ⁻ serves to provide electrons to the quantum dot compound, and oxidized I ₃ ⁻ receives electrons reaching the counter electrode and is reduced back to I ⁻ . Spacers are provided on the left and right sides of the electrolyte, and Pt electrodes and ITO glasses are provided on the upper portions thereof.

2 and 3 show a schematic diagram of the step of manufacturing a silicon electrode formed with a carbon nanotube three-dimensional network of the optical sensor manufacturing method according to the present invention. 2 is a schematic diagram using nano holes and Figure 3 is a schematic diagram using nanorods. Referring to FIG. 2, (a) first, a silicon substrate is etched through an etching process to form nano holes to form a three-dimensional structure, and (b) using a liquid immersion method on the substrate having the three-dimensional structure. After introducing the catalyst metal particles, (c) a carbon source gas is supplied to the substrate into which the catalyst metal particles are introduced to form a carbon nanotube having a three-dimensional network bridge structure.

In addition, referring to Figure 3 (a) first by etching the silicon substrate through the etching process to form nanorods to form a three-dimensional structure, the etching process is not particularly limited as long as it is commonly used in the art. For example, the Bosch process can be used. Next, (b) introducing the catalytic metal particles on the substrate having the three-dimensional structure by using a liquid phase immersion method, and then (c) supplying a carbon source gas to the substrate into which the catalytic metal particles are introduced to form a three-dimensional network bridge structure. To form a carbon nanotube having a. In addition, after forming the catalyst on the Si substrate in addition to the Bosch process as described above, a method of directly growing the Si nanorods on the Si substrate by supplying a Si source may be used.

After the carbon nanotubes having the three-dimensional network structure are formed, a step of applying and attaching a photoelectric conversion material to the surface of the carbon nanotubes is performed. In this step, a process of first modifying the surface of the carbon nanotubes is performed so that the photoelectric conversion material may be attached to the surface of the carbon nanotubes through chemical bonding. In the step of modifying the surface of the carbon nanotubes, it is preferable to modify the surface with a compound having a -COOR, -OCOR, -COSR, -NRR ', -OR or -OSR functional group, wherein R or R' are each independently Hydrogen atom, halogen atom, cyanide group, nitro group, substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, substituted or unsubstituted alkoxy having 1 to 10 carbon atoms A group, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms, or a value having 6 to 20 carbon atoms For example, pyrene carboxylic acid may be used to represent a cyclic or unsubstituted heteroaryloxy group. At this time, the pyrene group forms a strong bond with the carbon nanotubes by the Π-Π bonding force, and the surface of the carbon nanotubes is modified with a carboxylic acid group attached to the terminal group of the pyrene.

On the other hand, after modifying the surface of the carbon nanotubes can be attached to the photoelectric conversion material by immersing it in the photoelectric conversion material solution as it is, after modifying the surface of the photoelectric conversion material separately, and then immersed in a solution containing it It may be. The step of modifying the surface of the photoelectric conversion material is also preferable to modify the surface with a compound having a -COOR, -OCOR, -COSR, -NRR ', -OR or -OSR functional groups, wherein R or R' are each independently Hydrogen atom, halogen atom, cyanide group, nitro group, substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, substituted or unsubstituted alkoxy having 1 to 10 carbon atoms A substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms, or a substituted 6 to 20 carbon atoms Or an unsubstituted heteroaryloxy group. In particular, in the case of the quantum dot compound, it is preferable to modify the surface by replacing a part of the ligand of the quantum dot compound. For example, the surface may be modified using 3-mercapto propionic acid.

When manufacturing CNTs using metal catalysts and CVD in the production of carbon nanotubes, there is a restriction that the substrate on which CNTs are grown should not be sintered with the metal due to the heat applied during CNT growth. That is, for example, in the case of using a silicon substrate and using Fe as the metal catalyst, the Fe is sintered together to form Fe _x Si _y during CNT growth, and thus loses its activity as a CNT growth catalyst. The problem that the density of is lowered. Therefore, most conventional technologies use a silica (SiO ₂ ) substrate instead of a silicon substrate. Since the silica is an insulator, the surface of the nanorods or nano holes formed by etching them may also be insulators. However, in the present invention, by preventing the catalyst from being inactivated even by using a silicon substrate directly, the 3D CNT network can be grown to a high density up to the base of the nanorods or nanoholes, and the nanorods serve as a base electrode. The three-dimensional CNT network is directly connected on the base electrode has an advantage of excellent conductivity.

The reason why the Fe metal particles can be prevented from being sintered even when the silicon substrate is directly used in the present invention is because the Mo metal acts as a barrier for the sintering. According to one embodiment of the present invention, the Fe-Mo dicatalyst solution may include Fe (NO ₃ ) ₃ .9H ₂ O and an aqueous solution of Mo salt, but is not limited thereto.

The method of forming the nanorods or nanoholes in the silicon substrate used in the present invention is not particularly limited as long as it is commonly used in the art, for example, electrochemical etching, photolithography or direct synthesis method. It can be by.

The height of the nanorods, the depth of the nanoholes, the shape and the spacing between them is not particularly limited, but in order to form a three-dimensional network of carbon nanotubes, the height of the nanorods or the depth of the nanoholes is 2 to 200 μm, The spacing between the nanorods or between the nano holes is 50 to 2000 nm, and the aspect ratio of the nano rods or nano holes is preferably 2 to 100 nm. When the height of the nanorods or the depths of the nanoholes is less than 2 μm, the space where the carbon nanotubes are three-dimensionally formed is not preferable. It may be difficult to form uniformly. On the other hand, when the spacing between the nanorods or the spacing between the nano holes is less than 50nm, the spacing is too dense, so it is not preferable for the formation of carbon nanotubes. There is concern. In addition, the long-term ratio of the nanorods needs to be limited in order to improve the density of the three-dimensional carbon nanotube network per unit space. If the long-term ratio is less than 2 or more than 100, the density of the carbon nanotubes may decrease. have.

After the nanorods or nanoholes are formed on the silicon substrate, the surface is modified with Si-OH by washing with acetone, ethanol, deionized water, and the like, followed by pyranha treatment, UV-ozone treatment, or oxygen plasma treatment. Go through. This is to increase the interaction between the functional group and the metal catalyst or the catalytic ion by forming -OH functional groups on the surface of the nanorods or nano holes, so that the metal catalyst is not released during the cleaning step of the post process. The piranha treatment refers to a process of treating with a mixture of sulfuric acid and hydrogen peroxide.

The concentration ratio of Fe and Mo in the Fe-Mo dicatalyst solution is preferably 5: 1 to 0.5: 1. When the concentration ratio is less than 5: 1, Fe is sintered due to insufficient concentration of Mo, thereby inactivating If the density of the CNT falls and exceeds 0.5: 1, even though the amount of Mo is excessive, the Mo does not act as a seed of CNT growth.

According to an embodiment of the present invention, the Fe-Mo dicatalyst solution may be a mixture of a solution in which Fe (NO ₃ ) ₃ .9H ₂ O is dissolved in ethanol and an aqueous Mo salt solution. In the immersion step, the catalytic metal may be uniformly adsorbed on the silicon substrate by performing ultrasonic treatment in parallel.

Next, after mounting the substrate on which the bicatalyst metal is adsorbed to the reactor, and heat treatment, it may further comprise the step of reducing the catalytic metal by supplying NH ₃ or hydrogen gas. The heat treatment is carried out in a vacuum or air atmosphere containing oxygen, it can be heat-treated for about 10 to 60 minutes at a temperature of about 300 to 500 ℃ typically. The reason for the heat treatment is to prevent cross-aggregation by removing catalyst metals and organic / inorganic chemicals adhering to the substrate and oxidizing the surface of the catalyst particles to inhibit the movement of the catalyst metals at high temperatures. When the temperature is less than 300 ℃, the heat treatment temperature is not sufficient and when it exceeds 500 ℃ thermal energy is excessive, the thermal movement of the catalyst metals are activated, there is a fear that aggregation occurs. The heat treatment may be performed in a vacuum or in an air atmosphere containing oxygen. When the heat treatment is performed in an oxygen atmosphere containing oxygen, it is advantageous to remove organic chemicals, while the surface of silicon may be oxidized, but the heat treatment time is long. The amount of silicon oxidized is negligible.

Next, a metal oxide catalyst is formed on the surface of the substrate as a result of the heat treatment, and hydrogen or NH ₃ gas is supplied to the reactor to reduce it. Specifically, after the heat treatment, the temperature of the reactor is increased to about 700 to 900 ° C. while reducing the pressure of the reactor to about 10 ⁻² torr. For example, when the temperature of the reactor reaches about 800 ° C. and the reactor is stabilized, hydrogen or Ammonia gas may be supplied to the reactor, and hydrogen or ammonia gas may be supplied in the process of increasing the temperature, but the pressure and temperature are not limited thereto.

After reducing the catalytic metal as described above, a carbon source gas is supplied to prepare carbon nanotubes. The carbon source gas may be used without limitation as long as it is commonly used in the art, for example, methane, ethylene , At least one selected from the group consisting of acetylene, benzene, hexane, ethanol, methanol and propanol.

The carbon nanotubes formed according to the present invention are generally single-walled carbon nanotubes, but are not necessarily limited thereto, and multi-walled carbon nanotubes may be formed.

In the three-dimensional carbon nanotube network formed according to the present invention, the number of carbon nanotubes connected between the two nanorods is preferably 10 or more, the higher the density of the carbon nanotubes per unit space, the higher the electrical conductivity And because the surface area is increased, the efficiency of the optical sensor can be improved.

The optical sensor according to the present invention may be made of only the light receiving element, but may also be an optical sensor having a light transmitting unit and a light receiving unit together with the light emitting element.

Hereinafter, the present invention will be described in more detail with reference to preferred examples, but the present invention is not limited thereto.

Example 1

1- (1): Fabrication of Silicon Electrode with Three-Dimensional Carbon Nanotube Network

The n-type Si wafer was etched by Si using a conventional photolithography method and a Bosch process to form nanorods having a height of 2 μm, a distance between nanorods of 1 μm, and a diameter of about 1 μm. Next, the resultant was washed with acetone, ethanol and deionized water, and then subjected to Pirana treatment for 30 minutes to modify the surface of the Si wafer with -OH and with deionized water. Next, a solution in which Fe (NO ₃ ) ₃ 9H ₂ O (manufactured by Junsei) was dissolved in ethanol and an aqueous Mo salt solution (ICP / DCP standard solution, 10,000 μg / mL Mo in H ₂ O, manufactured by Aldrich) A dicatalyst solution was prepared. The concentration ratio of Fe and Mo in the dicatalyst solution was 4: 1. Subsequently, the Si wafer was immersed in the dicatalyst solution and subjected to ultrasonic waves, and the bicatalyst was evenly adsorbed on the entire surface of the wafer and the surface of the nanorod, washed with ethanol, and then mounted in a horizontal quartz tube reactor. The catalyst-adsorbed Si wafer was heat-treated for 30 minutes in an air atmosphere of 400 ° C. and heated to 800 ° C. while maintaining the pressure of the reactor at 1.0 × 10 ⁻² Torr. Then, the temperature in the reactor was stabilized at 800 ° C., and then 300 sccm of NH ₃ gas was supplied for 10 minutes to reduce the metal oxide catalyst to a pure metal catalyst. Finally, 20 sccm of C ₂ H ₂ was supplied as a carbon source gas for 10 minutes to form a three-dimensional single-wall carbon nanotube network. The pressure inside the reactor was 3.3 x 10 ^-1 Torr.

1- (2): Modification of the surface of carbon nanotubes

In order to modify the surface of the carbon nanotubes, a solution in which 0.01 M pyrene carboxylic acid (pyrene carboxilic acid) was added to 0.1 M KOH solution was prepared, followed by the three-dimensional carbon prepared in Example 1- (1). The silicon electrode on which the nanotube network was formed was immersed in the solution and stirred for 3 days. Next, the surface of the surface-modified three-dimensional carbon nanotube network formed silicon electrode is immersed in 0.1 M ethylene diamine and stirred for 1 day to carboxylic acid groups on the surface of the carbon nanotubes to the amine group (-NH ₂ ) 2 Tea modified.

1- (3): Photoelectric conversion material  Surface modification

Tributylphosphine, dissolved in Se Tributylphosphine (TBP) and trioctylphosphine (TOP) were added and reacted at 320 ° C. to synthesize CdSe quantum dot compounds (Q-dots). In order to change the ligand of the CdSe quantum dot compound synthesized above, 0.1 M of Q-dots was dissolved in toluene, and then 0.01 M of 3-mercaptopropionic acid (3-MPA) was added. It was refluxed at &lt; RTI ID = 0.0 &gt; Then, the refluxed solution was centrifuged and washed with CHCl ₃ solution to dissolve the remaining powder in a buffer solution of pH 7 to obtain a surface-modified CdSe quantum dot compound.

1- (4): on the surface of carbon nanotubes Photoelectric conversion material  apply

In Example 1- (2), the surface-modified silicon electrode was immersed in the surface-modified quantum dot solution in Example 1- (3) for 1 day, thereby applying CdSe quantum dots to the surface of the carbon nanotubes. .

1- (5): Manufacturing of optical sensor

A counter electrode was prepared by coating platinum on the surface of a conductive transparent glass substrate coated with ITO. Next, an ocean electrode serving as an anode and a silicon electrode prepared in Example 1- (4) were assembled. At the time of assembling the positive electrode, a sandwich-type device was manufactured by placing a polymer having a thickness of about 40 microns made of sulfin (SURLYN, manufactured by Du Pont) between the positive electrodes and heat-pressing the adhesive. Next, the space LiI in between the two electrodes through the micro hole formed in the surface of the counter electrode ^- / I ^{3 -} to fill the electrolyte solution was finally complete the optical sensor.

Example 2

The optical sensor was formed in the same manner as in Example 1 except that the height of the nanorods formed on the n-type Si wafer was 5 μm, the distance between the nanorods was 1.25 μm, and the diameter of the nanorods was about 0.75 μm. Prepared.

Example 3

The optical sensor was formed in the same manner as in Example 1 except that the height of the nanorods formed on the n-type Si wafer was 7 μm, the distance between the nanorods was 1.3 μm, and the diameter of the nanorods was about 0.7 μm. Prepared.

Example 4

The n-type Si wafer was immersed in a mixed solvent of HF and ethanol, and then, using conventional electrochemical etching, nano holes having a depth of 40 μm and a diameter of about 200 to 1000 nm were formed. Next, the resultant was washed with acetone, ethanol and deionized water, and then subjected to Pirana treatment for 30 minutes to modify the surface of the Si wafer with -OH and with deionized water. Next, a solution in which Fe (NO ₃ ) ₃ 9H ₂ O (manufactured by Junsei) was dissolved in ethanol and an aqueous Mo salt solution (ICP / DCP standard solution, 10,000 μg / mL Mo in H ₂ O, manufactured by Aldrich) The mixed dicatalyst solution was prepared. The concentration ratio of Fe and Mo in the dicatalyst solution was 5: 1. Subsequently, the Si wafer was immersed in the dicatalyst solution, ultrasonication was applied, and the dicatalyst was evenly adsorbed on the entire surface of the wafer and the inner surface of the nanoholes, washed with ethanol, and mounted in a horizontal quartz tube reactor. The catalyst-adsorbed Si wafer was heat-treated in a 400 ° C. air atmosphere for 30 minutes and heated up to 800 ° C. while maintaining the reactor pressure at 1.0 × 10 ⁻² Torr. Then, the temperature in the reactor was stabilized at 800 ° C., and then 300 sccm of NH ₃ gas was supplied for 10 minutes to reduce the metal oxide catalyst to a pure metal catalyst. Finally, 20 sccm of C ₂ H ₂ was supplied as a carbon source gas for 10 minutes to form a three-dimensional single-wall carbon nanotube network. The pressure inside the reactor was 3.3 x 10 ^-1 Torr. Subsequent processes were performed in the same manner as in Example 1 to prepare an optical sensor.

Test Example 1

For wafer SEM  Measurement of photograph

SEM photographs of the nanorods of the Si wafers formed in Examples 1 to 3 were taken and the results are shown in FIG. 4. Referring to FIG. 4, it can be seen that regular nanorods are formed.

Test Example 2

For 3D carbon nanotube networks SEM  Measurement of photograph

A front SEM photograph, an inclined SEM photograph, a side SEM photograph, and an enlarged SEM photograph of the silicon electrode including the three-dimensional carbon nanotube network formed in Examples 1 to 3 are taken and the results are shown in FIGS. 5 to 7. Shown. 5 to 7, it can be seen that the 3D carbon nanotube network is formed very uniformly to the base of the nanorods. Meanwhile, the TEM photographs of the Si nanorods and the carbon nanotube connection sites were measured and the results are shown in FIG. 8. Referring to this, all carbon nanotubes were directly connected to the Si nanorods. have.

Test Example 3

For 3D carbon nanotube networks SEM  Measurement of photograph

An inclined SEM photograph and an enlarged SEM photograph of the silicon electrode including the three-dimensional carbon nanotube network formed in Example 4 were taken and the results are shown in FIG. 9. Referring to FIG. 9, it can be seen that the 3D carbon nanotube network is uniformly formed not only on the surface of the hole but also inside. On the other hand, Figure 10 shows a SEM image of the three-dimensional carbon nanotube network coated with the CdSe quantum dot compound in Example 1. Referring to FIG. 10, it can be seen that quantum dots are attached around the carbon nanotubes.

Test Example 4

Average number of three-dimensional carbon nanotubes between nanorods

Based on the SEM photograph, the average number of three-dimensional carbon nanotubes between two nanorods was measured and the results are shown in FIG. 11. The average number of Example 1 was 11, Example 2 was 17 pieces, and Example 3 was 21 pieces. In other words, as the height of the nanorods increased, the average number of carbon nanotubes tended to increase.

Test Example 5

Raman Spectrum Measurement

The Raman spectrum (514 nm) of the three-dimensional carbon nanotube network prepared in Example 1 was measured and the results are shown in FIG. 12. The diameter of carbon nanotubes is ^{d 0 .93 (nm) = 238} / ν RBM It measured by the formula (cm <^-1> ) (In said formula, (ν _RBM). Is the frequency of radial breathing modes (RBMs) and d is the diameter of the carbon nanotubes). Referring to Figure 12 and RBMs is observed at about 100~300 cm ^-1, a weak D-band at 1330~1334 cm ^-1, the BWF-band was observed on the 1523~1574 cm ^-1 1588~1592 cm ^-1 The sharp G-band is observed at, which shows that uniform single-walled carbon nanotubes are formed in three dimensions over the entire space between nanorod structures. The diameter of the carbon nanotubes was about 0.8-1.1 nm.

Test Example 6

Performance test of the light sensor

The photocurrent property of the optical sensor manufactured according to the above embodiment was measured and shown in FIG. 13. White light (100 mW / cm ² : 1 Sun) was used as the light source. Referring to FIG. 13, in the optical sensor manufactured by using a substrate having a nanorod having a height of ² μm, a photocurrent density of 1 to 1.5 mA / cm ² was measured and manufactured using a substrate having a nanorod having a height of 5 μm. the light sensor in the 2.2~3 ㎂ / cm ² a photoelectric current density were measured of, in the photo sensor manufactured using a substrate formed of the nano-rods of the 7㎛ height was measured photocurrent density of 4.2~5.5 ㎂ / cm ^2. That is, as the height of the nanorods increases, the photocurrent density generated by the optical sensor increases. As shown in Test Example 4, the results were in good agreement with the tendency of increasing the average number of carbon nanotubes as the height of the nanorods increased.

On the other hand, the light reflectance of the surface of the optical sensor manufactured according to Example 3 and the surface of a general silicon wafer is measured and the results are shown. Compared to 14. Referring to FIG. 14, since the reflectance of the visible light region on the surface of a general silicon wafer is about 30%, the reflectance of the surface of the optical sensor according to the present invention exhibits a very low value close to 0%. It can be seen that the sensitivity is excellent.

1 is a schematic diagram of an optical sensor manufactured according to an embodiment of the present invention.

Figure 2 is a schematic diagram of a method for producing an organic-inorganic composite including a three-dimensional carbon nanotube network according to the present invention.

Figure 3 is another schematic diagram of a method for producing an organic-inorganic composite including a three-dimensional carbon nanotube network according to the present invention.

FIG. 4 is a SEM photograph of the nanorods of the Si wafers formed in Examples 1 to 3. FIG.

5 is a front SEM photograph and an enlarged SEM photograph of a silicon electrode including a three-dimensional carbon nanotube network formed in Examples 1 to 3;

6 is an inclined SEM photograph and an enlarged SEM photograph of a silicon electrode including a three-dimensional carbon nanotube network formed in Examples 1 to 3;

7 is a side SEM photograph and an enlarged SEM photograph of a silicon electrode including a three-dimensional carbon nanotube network formed in Examples 1 to 3. FIG.

FIG. 8 is a TEM photograph of a connection portion of Si nanorods and carbon nanotubes in a silicon electrode including a three-dimensional carbon nanotube network formed in Example 1. FIG.

FIG. 9 is an inclined SEM photograph and an enlarged SEM photograph of a silicon electrode including a three-dimensional carbon nanotube network formed in Example 4. FIG.

FIG. 10 is an SEM photograph and an enlarged SEM photograph of a three-dimensional carbon nanotube network coated with quantum dots prepared in Example 1. FIG.

FIG. 11 is a result of measuring an average number of three-dimensional carbon nanotubes between two nanorods based on SEM images of organic-inorganic composites including three-dimensional carbon nanotube networks formed in Examples 1 to 3. FIG.

FIG. 12 shows the Raman spectrum (514 nm) of the three-dimensional carbon nanotube network obtained in Example 1. FIG.

13 is a result of measuring the photocurrent properties of the optical sensor manufactured according to an embodiment of the present invention.

14 is a result of reflectance measurement of the optical sensor manufactured in Example 3.

Claims (17)

A silicon electrode in which nanorods or nano holes are formed; An opposite electrode facing the silicon electrode; And It includes a three-dimensional network of carbon nanotubes floated horizontally in parallel between the nano-rods adjacent to each other in the silicon electrode or inside the nano-holes, the photoelectric conversion material is attached to the surface of the carbon nanotubes An optical sensor comprising a carbon nanotube three-dimensional network characterized in that. The method of claim 1, The photoelectric conversion material is an optical sensor comprising a carbon nanotube three-dimensional network, characterized in that the quantum dot compound. 3. The method of claim 2, The quantum dot compounds are MgO, MgS, MgSe, MgTe, CaO, CaS, CaSe, CaTe, SrO, SrS, SrSe, SrTe, BaO, BaS, BaSe, BaTE, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgO, HgS, HgSe, HgTe, Al ₂ O ₃ , Al ₂ S ₃ , Al ₂ Se ₃ , Al ₂ Te ₃ , Ga ₂ O ₃ , Ga ₂ S ₃ , Ga ₂ Se ₃ , Ga ₂ Te ₃ , In ₂ O ₃ , In ₂ S ₃ , In ₂ Se ₃ , In ₂ Te ₃ , SiO ₂ , GeO ₂ , SnO ₂ , SnS, SnSe, SnTe, PbO, PbO ₂ , PbS, PbSe, PbTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, BP, Si, Ge, In _x Ga _(1-x) As (where 0 <x≤1), SiGe, In _n Ga _(1-n) An optical sensor comprising a carbon nanotube three-dimensional network, characterized in that any one or more compounds dls selected from the group consisting of N (where 0 < _n ≦ 1) and core / shell structures thereof. The method of claim 1, The surface of the quantum dot compound is coated with a compound having any one functional group selected from the group consisting of -OH, = O, -O-, -SS-, -SH, -P = O, -P and -PH An optical sensor comprising a carbon nanotube three-dimensional network. The method of claim 1, The quantum dot compound is an optical sensor comprising a carbon nanotube three-dimensional network, characterized in that it has a variety of sizes and shapes. The method of claim 1, An optical sensor comprising a three-dimensional network of carbon nanotubes, further comprising an electrolyte layer between the silicon electrode and the counter electrode. The method of claim 1, The carbon nanotube three-dimensional network has a density per space of more than 1.5 / ㎛ ³ and the carbon nanotube formed between the pair of the nanorods or inside the nano-holes, the density per height of the carbon is characterized in that more than 3 / ㎛ An optical sensor comprising a nanotube three-dimensional network. (a) preparing a Fe-Mo dicatalyst solution; (b) modifying the surface with Si-OH by performing a piranha treatment, a UV-ozone treatment, or an oxygen plasma treatment on a silicon substrate on which nanorods or nano holes are formed; (c) immersing the surface modified silicon substrate in the dicatalyst solution to adsorb the dicatalyst metal; (d) manufacturing a silicon electrode on which carbon nanotubes having a three-dimensional network structure are formed by supplying a carbon source gas on the substrate; And (e) immersing the silicon electrode in a photoelectric conversion material solution and attaching the photoelectric conversion material to the surface of the carbon nanotubes. The method of claim 8, The Fe-Mo dicatalyst solution is a method of manufacturing an optical sensor comprising a three-dimensional carbon nanotube network, characterized in that the Fe (NO ₃ ) ₃ · 9H ₂ O and Mo salt aqueous solution. The method of claim 8, The concentration ratio of Fe and Mo in the Fe-Mo dicatalyst solution is 5: 1 to 0.5: 1 manufacturing method of an optical sensor comprising a three-dimensional carbon nanotube network. The method of claim 8, The immersing the silicon substrate in the dicatalyst solution is a method of manufacturing an optical sensor comprising a three-dimensional carbon nanotube network characterized in that the parallel processing of the ultrasonic wave. The method of claim 8, And heat-treating the substrate on which the bicatalyst metal is adsorbed, and then supplying NH ₃ or hydrogen gas to reduce the catalytic metal. The method of claim 8, The carbon source gas is a method of manufacturing an optical sensor comprising a three-dimensional carbon nanotube network, characterized in that any one or more selected from the group consisting of methane, ethylene, acetylene, benzene, hexane, ethanol, methanol and propanol. The method of claim 8, The height of the nanorods is 2 ~ 200㎛, the interval between the nanorods is 50 ~ 2000nm, the long-term ratio of the nanorods is 2-100, characterized in that the manufacturing method of the optical sensor comprising a three-dimensional carbon nanotube network. The method of claim 8, The depth of the nano-holes is 2 ~ 200㎛, the interval between nano holes is 50 ~ 2000nm, the nano-holes ratio of 2 to 100, characterized in that the manufacturing method of the optical sensor comprising a three-dimensional carbon nanotube network. The method of claim 8, Optical sensor including a three-dimensional carbon nanotube network, characterized in that the number of carbon nanotubes connected to each other between the two adjacent rods adjacent to each other or formed horizontally inside the nano-hole to form a three-dimensional network of 10 or more Manufacturing method. The method of claim 8, The photoelectric conversion material is a quantum dot compound, the photoelectric conversion material solution is a method of manufacturing an optical sensor comprising a three-dimensional carbon nanotube network, characterized in that the surface of the modified quantum dot compound solution.

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