Traditional and current solar cells have limitations, such as high production costs, low operating efficiency, and durability, and many batteries rely on toxic and scarce materials. Researchers at Northwestern University have developed a new solar cell that, in principle, will minimize all of these limitations of solar technology.
Crystal Structure, Optical and Electrical Conductivity Properties of New Electrolyte Material CsSnI
In particular, this device solves for the first time the problem of the Gr.tzel cell, which is a promising low-cost, environmentally-friendly solar cell, but has a significant drawback: it is leakage. The electrolyte of the dye-sensitized cell is made of an organic liquid, leaks, and corrodes the solar cell itself.
Glazer cells use molecular dyes to absorb sunlight and convert it into electrical energy, like chlorophyll in plants. However, these batteries typically have a lifetime of less than 18 months, which makes them unusable for commercial use. Researchers have been looking for alternative materials for 20 years.
At Northwestern University, interdisciplinary collaboration was the basis, and nanotechnologist Robert PH Chang questioned and discussed with the chemist Mercouri Kanatzidis about the Glazer battery problem. The solution for Canaktivis is a new material for this kind of electrolyte. In fact, this material starts as a liquid and eventually becomes a solid material. In this way, this new all-solid-state solar cell is inherently stable.
"Grazell's battery is conceptually like a light bulb, but there is no tungsten or carbon material," said Cannadis, who needed to replace this troublesome liquid. "We have created a powerful new material that can make the Glazer battery even better. Our material is solid, not liquid, so it should not leak or corrode."
The postdoctoral researcher In Chung worked in the Karnatides group and worked closely with the graduate student Byunghong Lee, who belonged to Robert Zhang's group and developed the new battery and achieved overall performance improvement. It's about 1% per month.
In the solar cell of Northwestern University, the thin-film composite material is made of cesium, tin and iodine, called CsSnI3, which replaces the entire liquid electrolyte in the Glazer battery. This new solar cell is more efficient, more stable, and has a longer lifespan. Details are published in the May 24 issue of Nature.
Energy Level of CsSnI3 Solid-state Solar Cell Module
Robert Zhang said: "This is the first demonstration of an all-solid-state dye-sensitized solar cell system that is expected to exceed the performance of the Glazer battery. Our research opens up the possibility that these materials may become the most advanced, Produce much higher efficiency than what we have seen so far."
Northwestern University's solar cell exhibits the highest conversion efficiency of approximately 10.2%, which is the highest efficiency reported so far. This is true for solid-state solar cells using dye sensitizers. This value is close to the highest performance of the reported Glazer battery, which is approximately 11% to 12%. (Traditional solar cells are made of high purity silicon and can convert approximately 20% of incident light).
Unlike Grazl cells, this new solar cell uses both n-type and p-type semiconductors, and uses a single layer of dye molecules as a junction between the two. Each approximately spherical nanoparticle is made of titanium dioxide and is an n-type semiconductor. Canaxadis tin-iodine thin film material is a new type of soluble P-type semiconductor.
Electron microscopy image showing a cross-section of a CsSnI3/TiO2 cell on silicon
"Our cheap solar cells use nanotechnology entirely," said Robert Zhang. "We have hundreds of millions of nanoparticles, which gives us a huge effective surface area. We apply light-absorbing dyes to all of our particles."
The size of a single solar cell is half centimeter x half centimeter, about 10 microns thick. This dye-coated nanoparticle was incorporated and the new material of the company, which was initially liquid, could be poured in and flow around the nanoparticles. Much like paint, this solvent evaporates and forms a solid material. The photons in such a light-absorbing dye are converted into electricity, and the light-absorbing dye is between the two semiconductors.
Robert Zhang chose to use nanoparticles that are about 20 nanometers in diameter. This size will optimize the equipment, he said, increasing the surface area and creating enough space between the particles that the material of Canachtis can flow past and precipitate.
Technically, this new battery is not a true Grazl cell because CsSnI3, a material that conducts holes, absorbs light itself. In fact, this material absorbs more light and absorbs a wider spectrum of visible light than the typical dyes used in Glazer batteries. In the battery of Canaqidis-Robert Zhang, CsSnI3 also plays a role in the operation of the battery. This effect is not possessed by a liquid electrolyte couple. This function is to absorb light.
"This is just the beginning," said Robert Zhang. "Our concept applies to many types of solar cells. There is a lot of room for development."
This lightweight film structure is compatible with automated production, the researchers pointed out. They plan to make large solar arrays next.
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