MIT achieves 3.2% conversion efficiency through "thermal photovoltaic power generation"
The Massachusetts Institute of Technology (MIT) has announced that it has developed a new method of converting solar energy into electricity. This is a technique called thermophotovoltaic (TPV) power generation.
The idea of ​​TPV's power generation is to convert all the electromagnetic waves from the sun, such as visible light, into heat, and then convert the heat into light of a specific wavelength through solid elements called Emitters. Finally, these solar cells receive these using ordinary solar cells. Light and convert it into electricity. As a technology to increase the efficiency of solar cell power generation, the relevant parties are studying wavelength conversion technology that converts only ultraviolet and infrared rays into visible light. TPV can be said to be one of them, but TPV is different from other technologies in that it also wavelength-converts visible light. .
Existing solar cells can only convert light energy near a specific wavelength that supports the solar cell bandgap into electricity. TPV power generation is expected to use almost all solar energy, so "under ideal conditions, can achieve more than 80% conversion efficiency" (MIT).
The concept of TPV power generation has existed more than 10 years ago, and relevant research institutions around the world are conducting research. However, MIT said, "The highest conversion efficiency was only about 1%." And the new method developed by the school achieved a conversion efficiency of 3.2%, more than three times the past, and found a way to improve conversion efficiency, "through technology Improvement is expected to achieve 20% conversion efficiency."
The reason why the efficiency cannot be improved before is that it is difficult to obtain only a specific wavelength of radiation from an electromagnetic wave that is in a hot state. In the past, attempts have been made to use some rare earth elements, special quantum wells, and photonic crystals to form emitters.
This time, MIT uses a double-layered material as an emitter, consisting of multi-walled carbon nanotubes (CNTs) and one-dimensional photonic crystals using Si/SiO2. Multi-layered CNTs absorb light and infrared rays with high efficiency. Photonic crystals serve to release the energy absorbed by the CNTs through specific wavelengths.
The size of the TPV power generation emitter used by MIT was 1 cm square. Simulated sunlight was irradiated in accordance with the effect of a condensing mirror of 750 times. After heating the emitter to 962°C, a conversion efficiency of 3.2% was obtained.
MIT predicts that the larger the area of ​​the emitter, the smaller the heat loss and the higher the conversion efficiency. Therefore, MIT will make a 10cm square emitter and verify its performance in the near future. (Reporter: Nozawa Tetsuru, Nikkei Electronics)
Optical Microscopy
In optical microscopy different filters are used to improve contrast and emphasize specific features based on material properties. This can be achieved with magnifications typically ranging from 2.5 times up to 1,000 times. In materialography, reflected light is the most commonly used type of light optical microscopy. Transmitted optical microscopy is also used, but mainly for mineralogy specimens.
Stereo Optical Microscopy
The stereo microscope is an optical microscope variant, designed for low magnification observation of a specimen, using the light reflected from the specimen surface.
Scanning Electron Microscopy
A scanning electron microscope (SEM) is a type of electron microscope that produces images of a specimen by scanning the specimen surface with a focused beam of electrons. The electrons interact with the atoms in the specimen, producing various signals that can be translated into information about the surface topography and the composition of the specimen.
Transmission Electron Microscopy
Transmission electron microscopy (TEM) uses a beam of electrons transmitted through an ultra-thin specimen and that interacts with the specimen as it passes through it. Generated signals can be translated into various types of information, including information on the type and orientation of individual crystals.
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