This application claims priority to Taiwan Application Serial Number 105121774, filed Jul. 11, 2016, which is herein incorporated by reference.
The present disclosure relates to a method for forming tellurium/telluride nanowire arrays and tellurium/telluride thermoelectric devices. More particularly, the present disclosure relates to a method for forming large or small scale tellurium/telluride nanowire arrays on various conductive substrates and tellurium/telluride nanowire thermoelectric devices formed by the method.
Electricity is the necessity of everyday life. Many electric devices are driven by the electricity. There are various methods for generating electricity nowadays, such as solar cell power generation, wind power generation, hydraulic power generation and nuclear electricity generation. Owing to the resources depletion and the environmental issue, new kinds of electricity generation methods have been much concerned.
Thermoelectric devices are widely used in such as a heating/cooling system and a heat recovery/electricity generation system. The thermoelectric device is main equipment in the frozen industry, the air conditioning industry, the waste heat recovery industry, the temperature control industry and the thermoelectric power generation system. The operation of the thermoelectric device is based on the thermoelectric effect. The thermoelectric effect is a phenomena that transferring the thermal energy to the electrical energy or transferring the electrical energy to the thermal energy. The basic principle of the thermoelectric effect is that when a temperature difference is occurred on a thermoelectric material, an electromotive force is generated. The electromotive force can generate a current output thereby providing electricity. For example, in a thermoelectric device including a p-type thermoelectric material and a n-type thermoelectric material, a heat transportation is through the electrons and the holes flowing through the p-type or n-type thermoelectric material.
The thermoelectric device can transfer the thermal energy to the electrical energy without any external forces and mechanical energy, and can reduce energy loss, enhance energy usage and reduce thermal pollution. The efficiency of a thermoelectric material can be defined by a thermoelectric figure of merit ZT=S2σT/(K), where S is thermoelectric power or Seebeck coefficient, σ is electrical conductivity T is temperature and K is thermal conductivity. The parameters in the ZT are interacted, therefore an ideal thermoelectric material is hard to find. For reaching a maximum value of ZT, the ideal thermoelectric material should have high electrical conductivity for preventing electric power loss and low thermal conductivity for keeping the stability of the temperature difference on two sides of the thermoelectric material.
Thus, nanotechnology brings a new future to the thermoelectric material. When a dimension of a material is lowered to the nano scale range, a ratio of the surface atoms to the non-surface atoms is dramatically increased, thereby dramatically enhancing the surface effect. Furthermore, in the nano scale range, the quantum size effect of the material will also be increased. Therefore, there are distinct differences of the material characteristics between the bulk materials and the nano-scale materials. The nano-scale materials have new physical characteristics and interface phenomena, thus it is expected to break the bottleneck on low thermoelectric conversion efficiency of the thermoelectric material. For example, in the nano scale range, the lattice of the material will enhance the scatter frequency of the phonon, thereby lowering the thermal conductivity k, and the thermoelectric conversion efficiency can be enhanced. The application fields of the thermoelectric materials will be increased due to the increase of the thermoelectric conversion efficiency in the nano scale range. For example, the thermoelectric material can be applied in the commodity industry, the semiconductor industry or the medical industry. Furthermore, the thermoelectric material can also be used to recovery the waste thermal energy of industrial thermal energy (thermal energy from industrial emissions, waste material energy, heat exchanging energy), vehicle thermal energy (fuel engine thermal energy, engine thermal energy), environmental thermal energy (solar thermal energy, geothermal energy) and other thermal energy (heat water energy, residence thermal energy).
Although the thermoelectric material in the nano scale range can have higher thermoelectric conversion efficiency, however, nano-scale materials are such new materials that the material characteristics thereof cannot be totally understood and grasped. Complicated manufacturing processes are required for producing a large scale (area) nano-scale material for real use, thus the manufacturing cost is still high and it is not propitious to mass production.
Therefore, there is a need to develop a simple method that is capable of mass producing thermoelectric devices having large area in the nano scale range.
According to one aspect of the present disclosure, a method for forming tellurium/telluride nanowire arrays on a conductive substrate is provided. The method is used for forming tellurium/telluride nanowire thermoelectric materials on conductive substrates and producing thermoelectric devices, and the method includes: preparing a conductive substrate; preparing a mixture solution comprising a tellurium precursor and a reducing agent; immersing the conductive substrate into the mixture solution; reacting the tellurium precursor and the reducing agent for forming a plurality of tellurium/telluride nanowires on the conductive substrate; and arranging the tellurium/telluride nanowires for forming tellurium/telluride nanowire arrays. In this method, the conductive substrate can be rigid or flexible.
According to another aspect of the present disclosure, a tellurium/telluride nanowire thermoelectric device is provided. The tellurium/telluride nanowire thermoelectric device includes a first electrode, at least one tellurium/telluride nanowire array and a second electrode. The at least one tellurium/telluride nanowire array is formed on the first electrode. The second electrode is formed on the at least one tellurium/telluride nanowire array.
The present disclosure can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows:
It is a purpose of the present disclosure to provide a method for forming tellurium/telluride nanowire thermoelectric materials and devices. The present disclosure demonstrates a simple method for forming tellurium/telluride nanowire arrays on a conductive substrate. The method can be performed at room temperature to produce tellurium/telluride nanowire thermoelectric device having large area thus it is favorable for mass production. Through the method, the electrical conductivity can be enhanced and the thermal conductivity can be reduced for increasing the thermoelectric conversion efficiency by the tellurium/telluride nanowire thermoelectric materials in the nano scale range.
A step S101 for preparing a conductive substrate.
A step S102 for cleaning a surface of the conductive substrate.
A step S103 for preparing a mixture solution comprising a tellurium precursor and a reducing agent.
A step S104 for immersing the conductive substrate into the mixture solution.
A step S105 for reacting the tellurium precursor and the reducing agent for forming a plurality of tellurium/telluride nanowires.
A step S106 for arranging the tellurium/telluride nanowires on the conductive substrate thereby forming tellurium/telluride nanowire arrays.
In the step S103, the tellurium precursor can be made from TeTeOTeO2TeO3Te2O5H2TeO3K2TeO3Na2TeO3H2TeO4K2TeO4Na2TeO4H2TeNaHTe(NH4)2TeTeCl4MezTeZn(TePh)2(tmeda) (tmeda=N,N,N′,N′-teramethylethylenediamine) or Ph2SbTeR (R=Et, Ph). In one example, the mixture solution can be formed by pouring the tellurium precursor powders into the reducing agent solution.
In the Step S101, the conductive substrate can be fiber shaped, thin-film shaped, bulk shaped, sheet shaped, irregularly shaped, mesh shaped or porously shaped. For example, in
In the step S105 and the step S106 of
In some embodiments, the conductive substrate 110 can be fiber shaped, thin-film shaped, bulk shaped, sheet shaped, irregularly shaped, mesh shaped or porously shaped. The conductive substrate 110 can also be made from lithium, rubidium, potassium, cesium, barium, strontium, calcium, sodium, magnesium, aluminum, manganese, beryllium or carbon which has stronger reducibility. When the conductive substrate 110 is made from such kind of materials having stronger reducibility, the tellurium/telluride nanowires 112a can be well arranged.
In
Similarly, in
Then, a colloidal metal or a solid metal can be coated or evaporated on the tellurium/telluride nanowire arrays 230 as a second electrode 220, thereby forming an essential structure of the tellurium/telluride nanowire thermoelectric device 200.
The second electrode 220 can be a metal, a conductive oxide or a conductive polymer, it can be made from an Indium tin oxide (ITO), Gold (Au), Silver (Ag), Platinum (Pt), Aluminum (Al), Nickel (Ni), Copper (Cu), Titanium (Ti), Chromium (Cr), Selenium (Se) or alloys thereof. Preferably, a conductive polymer 240 can be formed between the tellurium/telluride nanowire arrays 230 and the second electrode 220, it can be made from polyaniline (PANI), polythiophene (PTH), poly (3, 4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS), polyacetylene (PA), polypyrrole (PPY), polycarbazoles (PC) or polyphenylenevinylene (PPV).
The conductive polymer 240 can enhance the electrical conductivity of the tellurium/telluride nanowire thermoelectric device 200. When a temperature difference is formed between the top and the bottom of the tellurium/telluride nanowire arrays 230, an electromotive force is generated thereby generating a voltage difference. For balancing charges, the free electrons of the first electrode 210 and the second electrode 220 flow to an external circuit and produce a current output.
In
In
Based on the thermoelectric effect, the aforementioned the tellurium/telluride nanowire thermoelectric device 300 is not only capable of collecting thermal energy but also providing cooling effect. For example, the tellurium/telluride nanowire thermoelectric device 300 can be assembled with an electric chip for cooling the electric chip. In another embodiment, the aforementioned the tellurium/telluride nanowire thermoelectric device 300 also can act as a temperature controlling device.
In sum, in the present disclosure, the method for forming tellurium/telluride nanowire arrays on a conductive substrate and the tellurium/telluride nanowire thermoelectric device have the following advantages: (a) the manufacturing cost is low and the manufacturing processes are simple, and a large area of the tellurium/telluride nanowire array can be produced at one time; (b) organic solvents are not required in the manufacturing processes, thus the environmental requirements can be met; (c) the tellurium/telluride nanowire thermoelectric device is thin and portable, thus it can be applied on many kinds of objects; (d) by selecting the tellurium/telluride nanowire thermoelectric materials having the same lattice directions, the thermal conductivity can be lowered and the thermoelectric conversion efficiency can be increased; (e) the tellurium/telluride nanowire arrays can be selected as n-type or p-type.
Although the present disclosure has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the present disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims.
Number | Date | Country | Kind |
---|---|---|---|
105121774 | Jul 2016 | TW | national |