JP2008300626A - Near field light power generation element and near field light power generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a near field light power generation element for generating power with near field light in an infrared-ray area, and to provide a near field light power generator. <P>SOLUTION: The power generation element for generating power with the near field light in the infrared-ray area which is generated in the neighborhood of an infrared-ray radiation body includes a power generation part arranged by opposing the infrared-ray radiation body and by elongation to have a distance to exhibit a significant near field light effect. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a near-field photovoltaic power generation element and a near-field photovoltaic power generation apparatus that generate power using near-field light in an infrared region.

  In a cogeneration system using an existing 1 kW class diesel engine or gas engine, the power generation efficiency is about 20 to 30%, while the exhaust heat released by the exhaust gas is about 50 to 60%. This waste heat energy is used for hot water supply, heating, etc., but in a general home or a medium-scale combined heat and power supply system, it is in a state of excess heat. In addition, since the exhaust gas temperature is relatively low at about 600 to 700 ° C., it is difficult to recover exhaust heat other than hot water. Moreover, the higher the power generation efficiency, the lower the exhaust heat temperature, and it becomes increasingly difficult to recover energy using the exhaust heat.

  By the way, normally, infrared rays having an intensity proportional to the fourth power of the surface temperature are emitted from the surface of the object (propagating light). In addition to this propagating light, near-field light is generated in the vicinity of the wavelength in the vicinity of the surface, and the electric field strength increases as it approaches the surface, which is 100 to 1000 times the intensity of the propagating light. It is predicted from the past that it will reach. Therefore, a gold disk with a thickness of 80 nm is heated to 200 ° C., the tungsten probe is brought close to the near-field region of the gold disk, the generated near-field light is scattered, and the scattered light is collected by a Cassegrain lens. An attempt was made to detect the intensity (Non-Patent Document 1).

In Non-Patent Document 2, an indium, gallium, arsenic photovoltaic cell or the like is placed near the heating element with a silica spacer between the heating element and a distance of 0.2 μm. It has been reported that electricity was generated by light.
Nature, Letters, Vol.444, 7 Dec., 2006, pp.740-743 | doi: 10.1038 / nature05265 Thermophotovoltaic Generation of Electiricity, 6th Conf. On TPV Gen. Electricity, Freiburg, Germany, 14-16, June, 2004, pp.42-51 | AIP Conf. Proc. Vol.738

  However, in the above attempt, since heat is conducted to the photovoltaic cell through the spacer, there is a problem that the photovoltaic cell is damaged by heat when the photovoltaic cell is in contact with the heating element through the spacer for a long time. Was inevitable. Therefore, a method of moving the photovoltaic cell away from the heating element before the temperature of the photovoltaic cell rises has been tried, but the results clearly demonstrating the power generation by the infrared near-field effect have been reported so far. It wasn't.

  Therefore, an object of the present invention is to solve the above-described problems and to provide a near-field photovoltaic element and a near-field photovoltaic power generation apparatus that generate power by using near-field light in the infrared region.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a power generation element that generates power by near-field light in an infrared region generated in the vicinity of an infrared radiator, and the near-field with respect to the infrared radiator. It is characterized by comprising a power generation unit arranged facing to a distance where the effect of light becomes significant.

  In this near-field photovoltaic power generation element, a near-field in the infrared region generated in the vicinity of the infrared radiator by a power generation unit arranged facing the infrared radiator at a distance where the effect of near-field light becomes significant. It becomes possible to convert light into electricity.

  The invention according to claim 2 is characterized in that the power generation unit is made of at least one compound semiconductor selected from a GaSb-based compound semiconductor, a GaInAs-based compound semiconductor, a GaInAsSb-based compound semiconductor, and an InPAsSb-based compound semiconductor. To do.

  In this near-field photovoltaic device, a power generation unit made of at least one compound semiconductor selected from a GaSb-based compound semiconductor, a GaInAs-based compound semiconductor, a GaInAsSb-based compound semiconductor, and an InPAsSb-based compound semiconductor generates near the infrared emitter. It is possible to convert near-field light in the infrared region into electricity.

  The invention according to claim 3 is characterized by comprising a wavelength selective emitter that is heated by the infrared radiator and that generates near-field light having a wavelength that can be generated by being incident on the power generation unit.

  In this near-field photovoltaic power generation element, the wavelength of the near-field light generated in the vicinity of the infrared radiator is adjusted by the wavelength selective emitter disposed in the infrared radiator, and the near-field light having a wavelength that can be generated by the power generation unit is generated. It can be efficiently converted into electricity by being incident on the power generation unit.

  The invention according to claim 4 is characterized in that the wavelength selective emitter includes a microcavity having a cavity size approximately equal to a half wavelength of the wavelength of the near-field light on the side facing the power generation unit. To do.

  This near-field photovoltaic power generation element is generated in the vicinity of the infrared radiator by having a microcavity having a cavity size approximately the same as the half wavelength of the wavelength of the near-field light on the side facing the power generation unit. The near-field light having a wavelength that can be generated by the power generation unit by adjusting the wavelength of the near-field light is incident on the power generation unit and can be efficiently converted into electricity.

  According to a fifth aspect of the present invention, there is provided a near-field photovoltaic power generation apparatus comprising a battery unit in which the near-field photovoltaic power generation elements are arranged in series and / or in parallel around an infrared radiator.

  In this near-field photovoltaic power generation device, the near-field photovoltaic power generation element is arranged in series and / or in parallel around the infrared radiator, and the near-field in the infrared region generated in the vicinity of the infrared radiator. Electricity can be generated by light.

  The near-field photovoltaic device of the present invention can generate electricity by converting near-field light in the infrared region generated in the vicinity of the infrared radiator into electricity. Therefore, the near-field photovoltaic power generation element of the present invention is deployed in various devices such as a mobile phone power source, a small household generator, and a commercial generator using exhaust heat from a factory. It is useful as a power generation element for generating power using the thermal energy discharged from the.

  The near-field photovoltaic power generation apparatus of the present invention can generate power using near-field light in the infrared region generated in the vicinity of the infrared radiator. For example, in a cogeneration system that supplies electricity and heat with a diesel engine or a gas engine, the heat energy of the exhaust gas can be converted into electric energy via near-field light to generate electricity. As a result, the energy conversion efficiency of the entire cogeneration system can be improved, and in the conventional cogeneration system, the waste heat energy that is used as hot water for hot water supply or heating and is discharged without using the remainder can be easily obtained. It can be used effectively by converting to electricity. Thus, when more electricity is required based on the amount of electric power from the engine, electricity is required for heat generation by waste heat power generation using the near-field photovoltaic power generation element or near-field photovoltaic power generation device of the present invention. It is possible to construct a flexible cogeneration system that can freely change the supply balance between heat and electricity, such as stopping exhaust heat power generation with a single switch and allocating it to hot water supply or heating.

Hereinafter, the near-field photovoltaic power generation element (hereinafter referred to as “the element of the present invention”) and the near-field photovoltaic power generation apparatus of the present invention will be described in detail.
The element of the present invention has a power generation unit arranged facing the infrared radiator, and converts the near-field light in the infrared region generated in the vicinity of the infrared radiator to electricity by the p-type semiconductor unit of the power generation unit. To do.

  In the present invention, the infrared radiator is not particularly limited as long as it can generate near-field light in an infrared region that can be generated by the power generation unit. In particular, when generating power by using near-field light in the infrared region generated near the surface of the part or the like heated by the exhaust heat, using the part, member, part, etc. heated by the exhaust heat as an infrared radiator. The device of the present invention is useful. For example, exhaust gas passages of internal combustion engines such as gas turbines, diesel engines, gas engines, etc. in stationary cogeneration systems, or exhaust gas passages of internal combustion engines mounted on moving automobiles such as passenger cars, buses, trucks, etc. For example, a furnace wall of a soaking furnace or preheating furnace, a furnace wall of a glass melting furnace, a furnace wall of various combustion furnaces, etc. . The element of the present invention generates power by using near-field light in the infrared region generated near the outer surface of the infrared radiator.

  The power generation unit is provided on the side facing the infrared radiator, and converts near-field light in the infrared region generated in the vicinity of the infrared radiator into electricity. The power generation unit is disposed facing the infrared radiator so as to be separated by a distance where the effect of near-field light generated in the vicinity of the infrared radiator becomes significant. Here, the distance at which the effect of near-field light is significant refers to the distance that the power generation unit can generate power with incident near-field light. For example, for near-field light in the infrared region, the distance is about several tens of nm. As a method of arranging the power generation unit at a distance similar to the wavelength of the near-field light with respect to the infrared radiator and keeping the distance between the infrared radiator and the power generation unit constant, for example, infrared Detects the capacitance between the radiator and the collector electrode provided on the surface of the power generation unit, and measures the distance between the infrared radiator and the power generation unit based on the detected capacitance Then, based on the measured distance, a method of keeping the infrared radiator and the power generation unit parallel and at a predetermined distance, or a power generation unit via a piezo actuator or the like as shown in FIG. And a method of keeping the distance between the power generation unit and the infrared radiator constant according to the generated power in the power generation unit can be adopted. By these methods, the infrared emitter and power generation unit are driven completely independently, and while maintaining parallelism, a nano-order gap is provided between the two to generate power using near-field light for a long time. Is possible. At this time, the space between the infrared radiator and the power generation unit is preferably a vacuum in order to avoid heat transfer due to heat conduction of gas.

The power generation unit is not particularly limited as long as it can generate power by using near-field light in an infrared region incident from an infrared radiator. And at least one compound semiconductor selected from the group consisting of: These compound semiconductors may be undoped or appropriately doped with a dopant such as Zn or Be. Among these, the GaSb-based compound semiconductor can generate power by near-field light having a wavelength of 1.8 μm (cutoff wavelength) or less. In addition, a GaInAs-based compound semiconductor has a composition represented by the formula: Ga _1-x In _x As (x is a positive number), and power is generated by near-field light having a wavelength of 2.5 μm (cutoff wavelength) or less. It is possible. Furthermore, the GaInAsSb-based compound semiconductor can generate power with near-field light having a wavelength of 2.5 μm (cutoff wavelength) or less. The InPAsSb-based compound semiconductor can generate power with near-field light having a wavelength of 3.5 μm (cutoff wavelength) or less. These compound semiconductors can be appropriately selected according to the wavelength, wavelength distribution, and the like of near-field light generated in the vicinity of the infrared radiator.

  Further, in the element of the present invention, between the infrared radiator and the power generation unit, a wavelength selective emitter that is heated by the infrared radiator and is incident on the power generation unit and generates near-field light with a wavelength that can be generated is provided. ,preferable. This wavelength selective emitter adjusts the wavelength of the near-field light generated in the vicinity of the infrared radiator, and makes the near-field light having a wavelength that can be generated by the power generation unit incident on the power generation unit to efficiently generate the near-field light. It becomes possible to convert to. In particular, the wavelength selective emitter has a cavity size L (the length of the side of the cavity whose opening surface is a cubic shape) on the side facing the power generation unit, which is about the same as the half wavelength of the wavelength of the near-field light. The thing of the structure which has a microcavity comprised by these is preferable. This microcavity may be engraved on the metal surface by photolithography and fast atomic beam etching (FAB), and depending on the type of metal used, silicon has a projection corresponding to the microcavity by photolithography. After producing the mold, it may be formed by reverse transfer by electrolytic casting. The wavelength selective emitter having a structure having the groove adjusts the wavelength of near-field light generated in the vicinity of the infrared radiator and causes the near-field light having a wavelength that can be generated by the power generation unit to be incident on the power generation unit. It can be efficiently converted into electricity.

  Moreover, the near-field photovoltaic power generation apparatus of this invention has the structure formed by arrange | positioning the battery part which consists of an element of this invention in series and / or parallel around the infrared radiator. This battery part is configured by arranging battery parts comprising the element of the present invention in series and / or in parallel around the infrared radiator so that a required voltage or current can be obtained in accordance with the form of the infrared radiator. Is done. At this time, the element of the present invention can select forms such as a power generation unit and a wavelength selection emitter according to the form of the infrared radiator. For example, when the infrared radiator is a cylindrical exhaust gas path, the power generation apparatus includes a near-field photovoltaic power generation element having a power generation unit and a wavelength selection emitter that are formed in a cylindrical shape so as to cover the exhaust gas path Can be configured.

Hereinafter, the present invention will be described specifically and in detail based on embodiments of the near-field photovoltaic device and the near-field photovoltaic device.
FIG. 1A is an exploded perspective view showing a structure of a near-field photovoltaic device according to an embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view of the near-field photovoltaic device.
A near-field photovoltaic device 1 shown in FIG. 1 includes a power generation unit 2 and a wavelength selective emitter 3 disposed so as to face the power generation unit 2.

  The power generation unit 2 includes an n-type semiconductor unit 6 and a p-type semiconductor unit 5 formed on the side of the n-type semiconductor unit 6 facing the wavelength selective emitter 3. The n-type semiconductor unit 6 is formed of n-type GaSb doped with Te. The n-type semiconductor portion 6 can be manufactured by a Czochralski method or the like, and a commercially available one may be used, or one formed by molecular beam epitaxial growth on a Ge / Au intermetallic compound substrate. The p-type semiconductor part 5 is formed by molecular beam epitaxial growth of GaSb, Zn-doped GaSb, or Be-doped GaSb on the surface of the n-type semiconductor part 6 or Zn in an n-type GaSb layer in a 600 ° C. thermostat. It can be formed by a diffusion method or the like. A film made of a compound semiconductor constituting the p-type semiconductor portion 5 is usually formed to a thickness of about 200 nm to 1000 nm.

  The wavelength selective emitter 3 is disposed on the side facing the power generation unit 2, and has a grid-like microcavity 4 engraved in a cubic column shape on the surface of the base material 3 facing the power generation unit 2. The cavity size L of the microcavity 4 (the length of the side of the cubic pillar) is, for example, that the power generation unit 2 has a GaSb-based compound semiconductor (cut-off wavelength: 1.8 nm) and a GaInAs-based compound semiconductor (cut-off wavelength: 2.. 5 nm), GaInAsSb-based compound semiconductor (cutoff wavelength: 2.5 nm), or InPAsSb-based compound semiconductor (cutoff wavelength: 3.5 nm). It is formed to be half the length of the wavelength of the near-field light. For example, the power generation unit 2 includes a GaSb compound semiconductor (cutoff wavelength: 1.8 μm), a GaInAs compound semiconductor (cutoff wavelength: 2.5 μm), a GaInAsSb compound semiconductor (cutoff wavelength: 2.5 μm), or InPAsSb. In the case of being formed of a system compound semiconductor (cutoff wavelength: 3.5 μm), the cavity size L of the microcavity 4 is formed to be about half the cutoff wavelength. Moreover, the depth of the microcavity 4 is usually about L or more. The microcavity 4 can adjust the wavelength of the generated near-field light and cause the near-field light having a wavelength that can be generated by the power generation unit 2 to enter the power generation unit 2 to efficiently convert the near-field light into electricity. It becomes possible.

  Further, the distance between the wavelength selective emitter 3 and the power generation unit 2, that is, the distance W between the tip of the convex portion 4a of the microcavity 4 and the power generation unit 2 is the same as the half wavelength of the wavelength of the near-field light. It is kept at a certain size. Thereby, the power generation unit 2 can convert near-field light in the infrared region generated in the vicinity of the infrared radiator to electricity.

  The method of keeping the distance W between the wavelength selective emitter 3 and the power generation unit 2 at the same level as the half wavelength of the near-field light is obtained by changing the distance W between the two to the half wavelength of the near-field light, That is, the method is not particularly limited as long as the distance can be kept constant at the nano-order distance. For example, using a piezo actuator, the distance W between the wavelength selection emitter 3 and the power generation unit 2 can be calculated as follows. A method of maintaining the maximum distance, a method of keeping the distance between the power generation unit 2 and the magnetic force unit of the same polarity attached to the wavelength selection emitter 3 constant by the attractive force or repulsive force, and the like are employed.

As a specific example of the method of keeping the distance between the wavelength selective emitter 3 and the power generation unit 2 constant using a piezoelectric actuator, a method of adopting the structure of the near-field photovoltaic power generation element 11 shown in FIG. It is done.
The near-field photovoltaic power generation element 11 shown in FIG. 2 (A) has a structure in which a power generation unit 12 and a microcavity 14a of a wavelength selective emitter 14 are housed in a vacuum vessel VC composed of a ceiling wall 19 and a side wall 19a. Have The power generation unit 12 includes a battery cell 13, and the battery cell 13 includes a p-type semiconductor unit 15 formed on the side facing the wavelength selection emitter 14 and an n-type semiconductor unit 16 formed on the opposite side. . In addition, on the surface of the p-type semiconductor portion 15 facing the wavelength selective emitter 14, four pairs of finger electrodes 17 a, 17 b, 17 c and 17 d are provided on the surface of the p-type semiconductor portion 15 as shown in FIG. Is embedded so as to be flat, and an electrode 18 is provided on the outer surface of the n-type semiconductor portion 16. Furthermore, between the electrode 18 and the ceiling wall 19 of the near-field photovoltaic device 11, four support columns 20a, 20b, 20c, and 20d are installed at four corners. Piezoactuators are disposed inside the columns 20a, 20b, 20c, and 20d. The piezo actuators disposed on the columns 20a, 20b, 20c, and 20d can expand and contract in the longitudinal direction of the columns 20a, 20b, 20c, and 20d according to the voltage applied to both ends thereof.

  The near-field light generating element 11 is generated in the power generation unit 12 by the near-field light incident from the wavelength selective emitter 14. In the power generation in the power generation unit 12, a voltage generated between the p-type semiconductor unit 15 and the n-type semiconductor unit 16 is electrically connected to the finger electrodes 17a, 17b, 17c, and 17d (or the finger electrodes, An electrode provided on the ceiling wall 19 (not shown) and the electrode 18 are applied to the piezo actuators disposed on the columns 20a, 20b, 20c, and 20d. At this time, if the voltage applied to the piezo actuator provided on the support column 17a is adjusted in accordance with the change in the voltage generated between the finger electrode 17a and the electrode 18, that is, the change in the generated voltage, the applied voltage is applied. The piezo actuator expands and contracts according to the applied voltage, and the support column 17a expands and contracts. Similarly, each of the support columns 20b, 20c, and 20d expands and contracts in accordance with a voltage change that occurs between each electrode of the finger electrodes 17b, 17c, and 17d and the electrode 18. Thereby, the distance between the wavelength selective emitter 14 and the power generation unit 12 is adjusted.

  Therefore, in the near-field photovoltaic power generation element 11, first, facing the wavelength selective emitter 14 that is an infrared radiation surface, the power generation unit 12 is brought close to a distance where the near-field effect becomes significant, and the wavelength selective emitter 14 and the power generation The maximum value of the generated voltage generated between each electrode of the finger electrodes 17 b, 17 c and 17 d and the electrode 18 is recorded together with the surface temperature of the wavelength selective emitter 14 in a range where the part 12 does not contact. In actual use, four voltages generated between each of the finger electrodes 17b, 17c and 17d and the electrode 18 are measured independently, and the generated voltage is always close to the maximum value. The distance between the wavelength selective emitter 14 and the power generation unit 12 is extended by driving the piezo actuator provided on each of the columns 20a, 20b, 20c, and 20d so that the columns 20a, 20b, 20c, and 20d expand and contract. However, it is possible to adjust the generated voltage so as to be the maximum value. Thus, a predetermined distance can be maintained between the wavelength selective emitter 3 and the power generation unit 2.

  Further, the distance W is measured by a non-contact method such as measurement of the dielectric constant between the wavelength selective emitter 3 and the power generation unit 2, and the columns 20a, 20b, 20c, The piezo actuator provided in each of 20d is driven to expand and contract the pillars 20a, 20b, 20c, and 20d, and the distance between the wavelength selection emitter 14 and the power generation unit 12 is set so that the generated voltage becomes the maximum value. It is also possible to adjust to.

  The near-field photovoltaic device 1 is heated by an infrared emitter (not shown) disposed outside the wavelength selective emitter 3 (upper side of the drawing in FIG. 1B), and is heated near the microcavity 4. Near-field light having a wavelength in the infrared region corresponding to the wavelength is generated. At this time, the wavelength of the generated near-field light is adjusted according to the size of the cavity of the microcavity 4 (the length of the side of the cavity) L, and the near-field light having a wavelength that can be generated by the p-type semiconductor unit 5 is generated. It becomes possible to make it. The generated near-field light is incident on the p-type semiconductor unit 5 of the power generation unit 2, and thereby generates power using the compound semiconductor that constitutes the p-type semiconductor unit 5. The generated electricity is supplied to the outside through an electrode (not shown) electrically connected to the power generation unit 2.

Next, FIG. 3A is a schematic cross-sectional view showing a configuration example of the near-field photovoltaic power generation apparatus 21 according to the embodiment of the present invention, and FIG. 3B shows a part of the near-field photovoltaic power generation apparatus 21. It is a perspective view cut and shown.
As shown in FIG. 3A, the near-field light power generation apparatus 21 covers the outer periphery of the exhaust gas path 24 on the outer periphery of the exhaust gas path 24 of a generator EG of a cogeneration system, for example, a diesel generator. In addition, a plurality of near-field photovoltaic elements 22 having a circular arc cross section are arranged in parallel and in series.

  In this near-field power generation device 21, the near-field photovoltaic power generation element 22 includes a wavelength-selective emitter having a circular arc cross section formed so as to be in close contact with the outer periphery of the cylindrical exhaust gas passage 24 as shown in FIG. And a power generation unit 25 disposed outside the wavelength selective emitter 23.

  The wavelength selective emitter 23 has a microcavity 26 carved in the outer peripheral direction on the outer periphery thereof, that is, on the side facing the power generation unit 25. The size of the cavity of the microcavity 26 is formed to be about the cut-off wavelength of the compound semiconductor constituting the power generation unit 2, that is, about the half wavelength of the necessary near-field light wavelength. The microcavity 26 adjusts the wavelength of the generated near-field light so that the near-field light having a wavelength that can be generated by the p-type semiconductor unit 28 (see FIG. 2B) is incident on the p-type semiconductor unit 28. It becomes possible to efficiently convert the field light into electricity.

  The power generation unit 25 is disposed outside the wavelength selection emitter 23 with a small gap G interposed therebetween, and is formed in a circular arc shape that covers the wavelength selection emitter 23. The power generation section 25 includes an n-type semiconductor section 27 having a circular arc cross section and a p-type semiconductor section 28 provided on the side facing the wavelength selective emitter 23.

  The p-type semiconductor portion 28 is formed by forming a film made of the compound semiconductor on the surface of the n-type semiconductor portion 27 formed by the Czochralski method or the like by molecular beam epitaxy growth or the like.

  In this near-field light power generation device 21, the wavelength selection emitter 23 is heated by the exhaust gas flowing through the exhaust gas passage 24, and the wavelength of the generated near-field light is adjusted by the microcavity 26 of the wavelength selection emitter 23 to generate power. The near-field light having a wavelength that can be generated by the unit 25 is incident on the power generation unit 25 to efficiently convert the near-field light into electricity. A plurality of near-field photovoltaic elements 22 arranged in parallel and in series generate power of a required voltage value or current value, and electricity can be supplied to the outside through an electrically connected current path. It becomes possible.

  In the cogeneration system having the near-field photovoltaic power generation device 21, as shown in FIG. 2A, the ratio of the energy used for power generation, that is, the power generation efficiency, is usually the scale of the energy generated by the generator EG. However, if it is a system with an output of 100 kW or higher, it is roughly 40%. Since the energy lost by cooling the generator is about 30%, the exhaust gas has about 30% of the energy generated by the generator EG, and the temperature is about 600 to 700 ° C. Become. Using the thermal energy of the exhaust gas, the near-field photovoltaic power generation device 21 provided in the exhaust gas path 24 generates power, and about 40% of the thermal energy of the exhaust gas, that is, about 10% of the total. Energy can be converted to electrical energy. Thereby, in the cogeneration system, the conversion efficiency into electric power can be improved. And in the conventional cogeneration system, by turning on and off the near-field photovoltaic power generation device, which is inefficient, such as a heat surplus state where the heat supply is large compared to the power supply, Since the balance between power supply and heat supply can be easily selected with a single switch, energy can be used effectively as a whole.

  Further, the near-field photovoltaic power generation apparatus of the present invention is not limited to the one using the exhaust heat energy of the cogeneration system, and can be applied to power generation by various heating elements. For example, exhaust gas passages of internal combustion engines such as gas turbines, diesel engines, gas engines, etc. in stationary cogeneration systems, or exhaust gas passages of internal combustion engines mounted on moving automobiles such as passenger cars, buses, trucks, etc. For example, furnace walls of soaking and preheating furnaces, furnace walls of glass melting furnaces, furnace walls of various combustion furnaces, etc. Thus, it is possible to generate power, which is useful for effective use of energy or optimization of the balance of thermoelectric supply. In these near-field photovoltaic power generation devices, power generation can be performed by modularizing the element of the present invention and arranging the module unit in accordance with the heating element. Furthermore, module units may be arranged to serve as exhaust heat passages such as exhaust gas passages.

  Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples.

Example 1
As shown in FIG. 3A, an infrared radiator (infrared radiator) 32 and a battery unit 33 are arranged facing each other in a vacuum container (not shown) decompressed to 10 ⁻⁴ Pa. Using near-field light power generation experimental apparatus 31, power was generated by near-field light.

  In this experimental apparatus 31, the infrared radiator device 32 includes a goniometer 34 and a tungsten block infrared radiator 35 mounted on the end face of the goniometer 34. The goniometer 34 can adjust the inclination angle of the tungsten block 35 in the Z-axis direction. Further, the infrared radiator 32 has a laser passage 36 (see FIG. 3B) that reaches the upper surface of the tungsten block 35 from above the goniometer 34 through the goniometer 34.

  The battery unit 33 includes a base 38 of the micrometer 37, a copper block 39 mounted on the base 38, and a photovoltaic device made of a gallium / antimony compound semiconductor attached to the top of the copper block 39. Power battery element 40. The photovoltaic cell element 40 has a p-type semiconductor part on the side facing the tungsten block infrared radiator 35 and an n-type semiconductor part on the opposite side, like the power generation part. Inside the copper block 39, a cooling water flow path (not shown) is provided. A grid-shaped collecting electrode (not shown) is attached to the surface of the photovoltaic cell element 40 in parallel with the surface of the photovoltaic cell element 40. Further, the micrometer 37 is capable of adjusting the position of the base 38 in the X-axis, Y-axis, and Z-axis directions and adjusting the rotation angle of the base 38 in the Z-axis direction.

In this experimental apparatus 31, as shown in FIG. 3B, first, the tungsten block infrared radiator 35 mounted on the goniometer 34 and the photovoltaic cell element 40 mounted on the micrometer 37 were faced to each other. . Next, in a state where the temperature of the tungsten block infrared radiator 35 is normal temperature, the surface of the tungsten block infrared radiator 35 is inclined by the goniometer 34, and the current collecting electrode attached to the surface of the photovoltaic cell element 40; The energization when contacting with the tungsten block infrared radiator 35 was detected, and the tilt angle of the tungsten block infrared radiator 35 at that time was measured. Further, the goniometer 34 tilts the surface of the tungsten block infrared radiator 35 in the reverse direction to detect energization when the tungsten block infrared radiator 35 contacts the collecting electrode, and the tungsten block infrared radiator 35 at that time is detected. The inclination angle of was measured. Then, from these two inclination angles, the inclination angle of the tungsten block infrared radiator 35 in which the tungsten block infrared radiator 35 and the photovoltaic cell element 40 having the collector electrode attached on the surface thereof are parallel to each other. The position was determined. This operation was performed in two axial directions (X-axis direction and Y-axis direction) orthogonal to the Z-axis direction (the vertical direction in FIG. 3). A groove is provided on the surface of the tungsten block infrared radiator 35 so that the tungsten block infrared radiator 35 is not in contact with the current collecting electrode.
Furthermore, while detecting the presence or absence of energization due to contact between the tungsten block infrared radiator 35 and the collecting electrode, the micrometer 37 does not contact the tungsten block infrared radiator 35 and the photovoltaic cell element 40, And the photovoltaic cell element 40 was positioned so that it might become parallel.

  Next, the tungsten block infrared radiator 35 was once separated from the photovoltaic cell element 40 by the goniometer 34 and then irradiated with a carbon dioxide laser through the laser passage 36 to heat the tungsten block infrared radiator 35. After the temperature of the tungsten block infrared radiator 35 reached 650 ° C., the amount of heating by the carbon dioxide laser was made constant, and the tungsten block infrared radiator 35 was brought close to the surface of the photovoltaic cell element 40 by the goniometer 34. At this time, the area of the tungsten block infrared radiator 35 facing the photovoltaic cell element 40 is 0.2 cm × 0.8 cm, and the photovoltaic cell element 40 receives infrared rays, that is, contributes to power generation. The effective area (the area where the tungsten block infrared radiator 35 and the photovoltaic cell element 40 actually face each other) was also 0.2 cm × 0.8 cm.

  FIG. 4 shows the measured current-voltage characteristics of the photovoltaic cell element in this experimental apparatus 31. As shown in FIG. 5, when the distance between the tungsten block infrared radiator 35, which is a heating element, and the photovoltaic cell element 40 is 50 μm or less, the form factor (radiation from the surface of the tungsten block infrared radiator 35) is achieved. The rate at which the generated energy reaches the surface of the photovoltaic cell element 40; if there are two infinite flat plates, the light emitted from one will always reach the other surface, so the shape factor will always be 1) When the tungsten block infrared radiator 35 and the photovoltaic cell element 40 are close to each other and the distance between the two becomes 1 μm or less, the open circuit voltage is 1.4 compared to the power generation by propagating light. The short circuit current jumped up to 4 times. The distance between the surface of the photovoltaic cell element and the surface of the tungsten block was determined from the moving distance of the micrometer. For comparison, the amount of power generated by propagating light proportional to the fourth power of the surface temperature of the heating element is shown by black circles in FIG. As shown in FIG. 5, the amount of power generated by this propagating light is constant regardless of the distance.

  Since the current-voltage characteristic of the photovoltaic cell element in this experimental apparatus does not change whether it is propagating light or near-field light, the current-voltage characteristic due to the near-field effect is shown in FIG. It is thought that it becomes. Here, since the power generation amount can be expressed by multiplying those increases, it can be seen that the power generation amount 5.6 times that of the case of propagating light is expected due to the near-field effect.

(A) is a disassembled perspective view which shows the structure of the near-field photovoltaic device which concerns on embodiment of this invention, (B) is a cross-sectional schematic diagram of the near-field photovoltaic device. (A) is a disassembled perspective view explaining the structure for adjusting the position of the electric power generation part in the near-field photovoltaic device which concerns on embodiment of this invention, (B) is a cross-sectional schematic diagram of the near-field photovoltaic device It is. (A) is a schematic cross section which shows the structural example of the near field photovoltaic power generation apparatus which concerns on embodiment of this invention, (B) is a perspective view which notches and shows a part of the near field photovoltaic power generation apparatus. (A) is an exploded perspective view showing the configuration of an experimental apparatus for near-field light power generation used in the examples, and (B) is a diagram for explaining an experimental method using the experimental apparatus. It is a graph which shows the electric power generation result by the near field light in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Near field photovoltaic device 2 Electric power generation part 3 Wavelength selection emitter 4 Microcavity 5 P type semiconductor part 6 N type semiconductor part 11 Near field photovoltaic element 12 Electric power generation part 13 Battery cell 14 Wavelength selection emitter 15 P type semiconductor part 16 N type Semiconductor part 17a, 17b, 17c, 17d Finger electrode 18 Electrode 19 Ceiling wall 20a, 20b, 20c, 20d Post 21 Near field power generation device 22 Near field photovoltaic device 23 Wavelength selection emitter 23
24 Exhaust gas passage 25 Power generation unit 26 Microcavity 27 Substrate 28 P-type semiconductor unit 31 Experimental device 32 Infrared radiator device 33 Battery unit 34 Goniometer 35 Tungsten block infrared radiator 36 Laser passage 37 Micrometer 37
38 Base 39 Copper block 40 Photovoltaic battery element

Claims (5)

A power generation element that generates power by near-field light in an infrared region generated in the vicinity of an infrared radiator,
A near-field photovoltaic element, comprising: a power generation unit disposed facing the infrared radiator at a distance where the effect of the near-field light is significant.   2. The proximity according to claim 1, wherein the power generation unit is made of at least one compound semiconductor selected from a GaSb compound semiconductor, a GaInAs compound semiconductor, a GaInAsSb compound semiconductor, and an InPAsSb compound semiconductor. Photovoltaic power generation element.   The near-field light according to claim 1, further comprising a wavelength-selective emitter that is heated by the infrared radiator and is incident on the power generation unit to generate near-field light having a wavelength capable of power generation. Power generation element.   4. The proximity according to claim 3, wherein the wavelength selective emitter includes a microcavity having a cavity size approximately the same as a half wavelength of the wavelength of the near-field light on a side facing the power generation unit. Photovoltaic power generation element.   5. A near-field photovoltaic power generation apparatus comprising a battery unit in which the near-field photovoltaic power generation element according to claim 1 is arranged in series and / or in parallel around an infrared radiator.

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