KR20100048604A - Composite material for energy converting and method for manufacturing thereof and nergy converting device - Google Patents

Abstract

PURPOSE: A composite material for energy conversion, a method for manufacturing the same, and an energy conversion device using the composite are provided to prevent reduction of electron transport ability and to enhance light emitting or photoelectric efficiency. CONSTITUTION: A composite material for an energy conversion comprises: a nanowire(2); a plurality of quantum dots(3) which are formed on each nanowire and are composed of a semiconductor material; a low molecular weight linker(4) interlinking nanowire and quantum dot by a non-covalent binding mode. The low molecular linker comprises amine or phosphine, which is selected from molecule having aliphatic chain with 4 or less carbon, or aromatic ring. Nanowire is composed of an oxide system in case of being used as an electron transport dragon.

Description

COMPOSITE MATERIAL FOR ENERGY CONVERTING AND METHOD FOR MANUFACTURING THEREOF AND NERGY CONVERTING DEVICE}

The present invention relates to an energy conversion device, a composite material for energy conversion, and a method of manufacturing the same. More particularly, the energy conversion device for enhancing light emission or photoelectric efficiency by allowing nanowires to act as an electron transfer medium between quantum dots. The present invention relates to a composite material, a method of manufacturing the same, and an energy conversion device using the same.

Quantum dots are nano-sized semiconductor materials that exhibit quantum confinement effects. These quantum dots receive energy from an excitation source and reach their energy excited state, and have their own energy bandgap. To release energy.

Therefore, when the size of the quantum dot is adjusted, the corresponding band gap can be adjusted. Therefore, the electrical and optical characteristics can be adjusted, and thus the quantum dot can be applied to various devices such as light emitting devices or photoelectric change devices.

1 is a cross-sectional view schematically showing an example of a light emitting device using a quantum dot according to the prior art.

Referring to FIG. 1, a first electrode layer 10, a hole transport layer 20, a quantum dot active layer 30, and a second electrode layer 40 may be formed.

The first electrode layer 10 is an anode for hole injection, and is made of a transparent metal oxide like an ITO electrode.

The hole transport layer 20 transfers holes from the first electrode layer 10, and TPD, which is a diamine derivative, is used.

The quantum dot active layer 30 emits light by recombination of holes and electrons transferred from the hole transport layer 20 and the second electrode layer 40, respectively.

The second electrode layer 40 is a cathode for electron injection.

The principle of such a light emitting device will be described with reference to FIGS. 2 and 3 as follows.

First, a positive voltage is applied to the first electrode layer 10 and a negative voltage is applied to the second electrode layer 20.

Then, holes injected from the first electrode layer 10 and electrons injected from the second electrode layer 20 are trapped in the quantum dots of the quantum dot active layer 10.

The electrons and holes trapped in each of the quantum dots are recombined, and the energy generated during the recombination is emitted to the outside in the form of light.

On the other hand, Figure 4 is a schematic cross-sectional view showing an example of a solar cell using a quantum dot according to the prior art.

Referring to FIG. 4, the counter electrode layer 100, an electrolyte layer 200, a light absorption layer 300, and a conductive transparent substrate 400 are included.

The counter electrode layer 100 is made of a conductive material, and the electrolyte layer 200 is made of an electrolyte.

The light absorption layer 300 includes a metal oxide layer 300a and a dye layer 300b formed of quantum dots (not shown).

Looking at the principle of the solar cell according to this structure is that the electrons generated by the sunlight incident on the light absorbing layer 300 through the opposing electrode layer 100 through the quantum dots due to the coupling (coupling) effect of the quantum dots to the external load To transfer electrical energy.

As such, since the quantum dots used in the optical devices such as the light emitting devices and the solar cells have low conductivity, the coupling efficiency between neighboring quantum dots is low and thus the electron transfer ability is lowered.

That is, the interface between the quantum dots acts as a resistor, the electrical conductivity is low, the electron transfer ability is low, the luminous efficiency is low in the light emitting device, the energy transfer efficiency is low in the case of a photoelectric device such as a solar cell.

In addition, in order to improve the efficiency in the thermoelectric element, it is essential to develop a material that lowers the thermal conductivity and increases the electrical conductivity. In the case of the quantum dot, the thermal conductivity is very low due to the small size, which is considered to be an ideal material.

However, not only the quantum dot is difficult to form a film but also has a problem in that the electrical conductivity is not high due to the contact resistance problem between the quantum dots.

An object of the present invention for solving the problems of the background art, by placing a quantum dot on a nanowire with excellent charge transport ability and non-covalent defects of the nanowire and the quantum dot using a low molecular linker, the quantum dot adjacent to the nanowire The present invention provides an energy conversion composite material, a method for manufacturing the same, and an energy conversion device using the same.

The present invention for solving the above problems in the composite material for energy conversion of the energy conversion element composed of quantum dots, nanowires, a plurality of quantum dots formed on each nanowire and composed of a semiconductor material, and the nanowires And a low molecular linker connecting the quantum dots in a non-covalent manner.

The present invention for solving the above problems is a method of manufacturing a composite material for energy conversion of the energy conversion element consisting of quantum dots, forming a plurality of conductive nanowires, the step of placing a quantum dot on the nanowires And sequentially placing a plurality of quantum dots on the plurality of nanowires.

In addition, the present invention for solving the above problems is an energy conversion layer that emits light by recombination of electron-holes or converts energy incident from the outside into electrical energy or heat applied from the outside is converted into electrical energy to transfer the energy conversion layer. In the energy conversion device having, the energy conversion layer is formed of a nanowire and each of the nanowires and composed of a plurality of quantum dots consisting of a semiconductor material and a low molecular linker connecting the nanowires and the quantum dots in a non-covalent manner Consisting of a composite material for energy conversion.

Advantageous Effects of the Invention The present invention allows the conductive nanowires to act as a medium for improving electron transfer ability between neighboring quantum dots, thereby preventing emission degradation due to interfacial resistance between quantum dots, thereby improving luminous efficiency and photoelectric conversion efficiency. There is this.

In addition, the surface of the quantum dots or nanowires is designed to preserve the electrical properties of the quantum dots and nanowires and to facilitate adsorption, thereby maximizing charge transfer from the quantum dots to the nanowires, thereby improving luminous efficiency, photoelectric conversion efficiency, and thermoelectric efficiency. .

In addition, the composite material for energy conversion according to the present invention can be utilized in various electronic devices, sensors, and the like.

The present invention provides energy such as a light emitting device that emits light by recombination of electron-holes, an optoelectronic device that converts light energy flowing from the outside into electrical energy, and a thermoelectric device that converts and transfers heat transferred from the outside into electrical energy. It relates to a conversion element.

FIG. 5 illustrates an energy conversion composite material constituting the energy conversion device of the present invention. FIG. 6 is an enlarged view of a portion of FIG. 5, wherein the energy conversion layer 30 of the energy conversion device according to the present invention is nanowire. (2) and a quantum dot (3) and a linker low molecular weight (4) composed of a composite material for energy conversion.

The nanowires 2 and the quantum dots 3 are connected in a non-covalent manner by a low molecular linker.

Here, the quantum dots 3 are made of a semiconductor material and are continuously formed on each nanowire.

The quantum dots may be selected from the group consisting of II-VI, III-V, IV-VI, and IV semiconductor compounds, and mixtures thereof. Specifically, the quantum dots may be CdS, CdSe, CdTe, ZnS, ZnSe , ZnTe, HgS, HgSe, HgTe, PbS, PbSe, PbTe, AlN, AlP, AlAs, GaN, GaP, GaAs, InN, InP, InAs, or mixtures thereof.

In addition, when the quantum dots 3 are used to absorb light to generate electron holes, and the nanowires 2 are used to transfer electrons generated by the quantum dots 3, the nanowires 2 are oxides. It is preferable that the band gap is wider than the quantum dot such as a series and the like and have an energy level for electron movement.

In addition, when the quantum dot (3) is used to generate electron holes by absorbing light, and the nanowire is used for electron and hole transfer, the nanowire (2) is a low band gap wire such as carbon nanotubes (CNT) It is preferable to make it.

In this case, the carbon nanotubes include carbon nanotubes, carbon nanofibers, carbon nanotubes doped with metal or semiconductor materials based on carbon.

In the energy conversion layer of the present invention, since the quantum dots 3 are disposed on the nanowires 2, in which charge transfer is smooth, electron exchange from the quantum dots to the nanowires is performed well.

That is, in the conventional quantum dots used in the energy conversion device, the interface between the respective quantum dots acts as a resistor, the electrical conductivity is lowered, the electron transfer ability is reduced, the present invention nanowires act as electron and hole transfer medium between the quantum dots Do it.

In the present invention, when the quantum dots are attached to the nanowires, the solution stability and optical properties of the quantum dots are maintained and at the same time, amines such as pyridine, which are easily adsorbed to the nanowires, include phosphine-based aromatic rings, or have 4 or less carbon atoms. Small molecules with aliphatic chains are used as linkers.

That is, when the linker plays a role of absorbing light itself, recombination of electrons and holes in itself, and exothermic heat, it is not effective to transfer charges generated from absorbed light from the quantum dots to nanowires.

Therefore, the linker with high reactivity by light such as sulfur (sulfur) decreases the stability of the composite material. Therefore, the proposed linker molecule is insensitive to light and has excellent light stability. In addition to the transfer, it is desirable to use low molecular weight molecules that are easy to attach to quantum dots and nanowires.

Accordingly, the luminous efficiency is improved in the light emitting device, the electrical energy generation efficiency is improved in the photoelectric device, and the thermoelectric efficiency is improved in the thermoelectric device.

Hereinafter, a method for manufacturing an energy conversion composite material of the present invention will be described with reference to FIG. 7.

First, the nanowires 2 are formed.

In this case, the nanowires 2 are formed of a material having a smooth transfer of charges, but when used for electron transfer of the quantum dots 3, the nanowires 2 have a wider band gap than the quantum dots such as oxide based electrons. Formed with energy levels for movement.

In addition, when the nanowires 2 are used for electron and hole transfer of the quantum dots 3, the nanowires 2 are preferably formed of a low band gap wire such as carbon nanotubes (CNT).

Then, a plurality of quantum dots are formed on the nanowires 2.

In this case, in order to arrange the quantum dots on the nanowires 2, the plurality of nanowires 2 are supported in an organic solvent, and then the quantum dots on the nanowires 2 are bonded through non-covalent bonds.

Here, the quantum dots may be formed through a general chemical wet method using a high temperature dispersion solvent.

In addition, the quantum dots may be formed to have a core or core / shell structure, and may be selected from the group consisting of II-VI, III-V, IV-VI, and IV semiconductor compounds, and mixtures thereof. The quantum dots are CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, PbS, PbSe, PbTe, AlN, AlP, AlAs, GaN, GaP, GaAs, InN, InP, InAs, InSb or their It may be formed of a material selected from the group consisting of a mixture.

In the present embodiment, the quantum dots use CdSe of group II VI semiconductors that absorb light in the visible light region to form electron holes, and carbon nanotubes that receive electron holes simultaneously as nanowires and move them to the electrode.

Then, the surface is modified by a low molecular linker containing an amine, phosphine-based and aromatic ring, such as pyridine, which is easy to adsorb onto the nanotubes, while maintaining the solution stability and optical properties of the quantum dots after forming through a wet method.

At this time, the modification of the surface can be obtained by stirring for 3 to 24 hours in a state heated to 50-100 ℃ after excessive injection of the molecule to be replaced.

8 is a view of the energy conversion composite material according to the present invention observed with a transmission electron microscope, Figure 9 is a photocurrent of the FET device consisting of a FET device made of the energy conversion composite material according to the present invention and a quantum dot according to the prior art A graph showing the characteristics.

9, (a) shows the photocurrent characteristics of the FET device according to the prior art (b) shows the photocurrent characteristics of the FET device according to the present invention, according to the present invention quantum dots are formed on the nanowire by a low molecular linker Since it is disposed in, the efficiency of charge transfer between the quantum dots through the nanowires can be seen that the photocurrent is increased compared to the prior art.

1 is a cross-sectional view schematically showing an example of a light emitting device using a quantum dot according to the prior art.

2 and 3 are views illustrating the operation of the light emitting device of FIG.

4 is a cross-sectional view schematically showing an example of a solar cell using a quantum dot according to the prior art.

5 is a schematic diagram of the composite material for energy conversion of the present invention.

6 is an enlarged view of a portion of FIG. 5;

Figure 7 is a schematic diagram illustrating a method of forming a composite material for energy conversion according to an embodiment of the present invention.

Figure 8 is a picture of observation of the composite material for energy conversion according to the present invention with a transmission electron microscope.

9 is a graph showing the photocurrent characteristics of the FET device made of a composite material for energy conversion according to the present invention and the FET device made of a quantum dot according to the prior art.

<Description of the symbols for the main parts of the drawings>

1: Composite material for energy conversion

2: nanowires

3: quantum dot

Claims (10)

Regarding the composite material for energy conversion of the energy conversion element composed of quantum dots, With nanowires, A plurality of quantum dots formed on each nanowire and composed of a semiconductor material, and Energy conversion composite material comprising a low molecular linker for connecting the nanowires and the quantum dots in a non-covalent manner. The method of claim 1, The low molecular weight linker comprises an amine or a phosphine and is selected from among an molecule having an aromatic ring or an aliphatic chain having the same carbon number of 4 or less. The method of claim 1, The quantum dot is a composite material for energy conversion, characterized in that selected from the group consisting of II-VI, III-V, IV-VI, Group IV semiconductor compounds and mixtures thereof. The method of claim 3, wherein The quantum dots are CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, PbS, PbSe, PbTe, AlN, AlP, AlAs, GaN, GaP, GaAs, InN, InP, InAs, InSb or their Energy conversion composite material, characterized in that selected from the group consisting of a mixture. 5. The method according to any one of claims 1 to 4, When the nanowires are used for electron transfer, the composite material for energy conversion, characterized in that the oxide-based. 5. The method according to any one of claims 1 to 4, When the nanowires are used for electron and hole transfer, nanowires are carbon nanotubes or II-VI, III-V semiconductor compound, characterized in that made of a semiconductor compound. The method according to any one of claims 1 to 6, An energy conversion device having the energy conversion composite material as an energy conversion layer. In the method for producing a composite material for energy conversion of the energy conversion element consisting of quantum dots, Forming a plurality of conductive nanowires, Disposing a quantum dot on the nanowire, Method for producing a composite material for energy conversion comprising the step of sequentially placing a plurality of quantum dots on the plurality of nanowires. The method of claim 8, Placing a quantum dot on the plurality of nanowires, Method of producing a composite material for energy conversion, characterized in that the quantum dots are adsorbed or covalently bonded on the nanowires in a solvent. The method of claim 9, Placing the quantum dots on the nanowires and then connecting the nanowires and the quantum dots in a non-covalent manner by using a low molecular linker through the surface modification method of producing a composite for energy conversion.

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