Silicon is a semiconductor material whose properties fit perfectly in solar cells to produce electrical energy.
Pure silicon is a grayish crystalline elemental mineral with a metallic luster, very hard, brittle, and very high melting and boiling points. Furthermore, it is an intrinsic semiconductor. The amorphous form of the element occurs in brown, electrically conductive powders that can be easily melted and vaporized.
It is a widely used material in solar panels for its semiconductor properties. Its physical and chemical properties are very favorable to promoting the so-called photovoltaic effect.
Over 90% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust after oxygen. Rock crystals are made up of silicon, a mineral found in many different types of rocks. Silicon is widely distributed in space in planetoids, cosmic dust, and planets as different forms of silicon dioxide or silicates.
It is a chemical element belonging to the periodic table. Silicon atoms have the atomic number 14, and their symbol is Si. This chemical element belongs to group IV A of the periodic table.
What is the valency of silicon?
The valency of an element is a measure of its ability to combine with other elements.
The valency of silicon is four. This means that it can form compounds with other elements by sharing electrons. It strongly tends to form covalent bonds, which explains why it is a widely used semiconductor material.
Where is silicon obtained from?
Silicon is, after oxygen, the most abundant element in the earth's crust, constituting 26% by weight.
This chemical element is widely diffused in nature, and its presence has been detected in the Sun, stars, and meteorites.
How is silicon obtained?
Obtaining silicon is done by various methods according to the element's purpose. The most important commercial process is the reduction of silica with carbon in an electric furnace.
The preparation of high-purity silicon (99.7%) is obtained by transforming impure silicon into the volatile tetrachloride (SiCl4), purifying it by distillation, and subsequent reduction with zinc.
In electronics, it is obtained by zonal purification to eliminate boron, aluminum, phosphorus, gallium, arsenic, indium, and antimony. Subsequently, a single crystal is obtained by the Czochralski method. This method consists of immersing a small single crystal in a bath of liquid silicon heated to the melting temperature and slowly withdrawing it to cause the growth of the single crystal.
Who discovered silicon?
Jöns Jacob Berzelius was a Swedish chemist who discovered the element silicon. He is also credited with discovering the law of partial pressures, which states that the total pressure of a mixture of gases equals the sum of the partial pressures of the individual gases.
Berzelius was born in 1779 in Stockholm, Sweden, and studied medicine at Uppsala University. However, he soon turned his attention to chemistry and began conducting experiments in his basement laboratory.
In 1808, he published his first major work, entitled Essays on Elective Attractions, which laid the foundation for modern electrochemistry. In 1811, he discovered this chemical element while analyzing a sample of iron oxide from Sicily.
He initially thought it was a new chemical element but later realized it was actually an impurity in iron oxide. Nevertheless, this element became important in semiconductor manufacturing and other industries.
Uses and applications of silicon
Most silicon are used commercially without being separated and often with little processing of the natural mineral. Such use includes industrial construction with clays (silica brick), silica sand for glassmaking, fillers in plasters and putty, and ceramics such as porcelain. Silicates are used in portland cement for mortar and stucco and mixed with silica sand and gravel to make concrete for walkways, foundations, and roads.
They are also used in whiteware ceramics, such as porcelain dishes and electrical insulators. High-purity silicon wafers are used for computer chip fabrication and solar energy applications.
Some other uses examples are
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It plays a vital role in electronics manufacturing semiconductor devices.
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These semiconductors are the most used material for solar cell manufacturing. Silicon cells are the basis of solar power. It is the primary element of solar panels and converting solar energy into electricity.
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Photovoltaic panels can be built with amorphous or crystalline silicon. Solar cell efficiencies depend on the silicon configuration. In general, the better efficiency, the more expensive solar panel is.
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In metallurgy, it is used to prepare special steels and other alloys and to prepare various compounds.
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Silicon dioxide has various industrial applications, including its use as an additive in the food industry. It appears on the list of food additives as E-551.
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For medical uses, this material has many properties that make it ideal for use in the human body. It is biocompatible, meaning it does not trigger an immune response when it comes into contact with human tissue. It makes it an ideal material for implants and other medical devices that need to be in close contact with the human body. Silicon is also strong and durable, meaning that medical devices made from this material can withstand a lot of wear and tear..
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Silicon carbide is a compound of silicon and carbon, typically used as an abrasive or refractory material. It has a Mohs hardness of 9 and a melting point of 2,730 degrees Celsius. It is also known as carborundum.
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In compound form (silicates, silica, silicones), it is used in a very general way.
The role of silicon in solar cells
Silicon is a material that works perfectly to provoke the photovoltaic effect.
The photoelectric effect is the basis for solar cell technology. When light strikes a metal surface, electrons are emitted from the metal. When sunlight hits a silicon solar cell, the effect causes electrons to be dislodged from the silicon atoms. These free-flowing electrons can then be harnessed to generate electricity.
A perovskite solar cell is a type of solar cell and is a solar cell using a material having a perovskite structure as a light absorption layer. Organic-inorganic halides with lead or tin as the central metal are mainly used.
In contrast, organic materials have a relatively low dielectric constant for dissociating an excited electron-hole pair into free collectible charge carriers. Therefore, they have an inefficient energy conversion when used in PV cells.
Properties of silicon
|
Atomic Density |
5 x 1028 m-3 |
|
Atomic Weight |
28.09 |
|
Density (ρ) |
2.328 g cm-3 2328 kg m-3 |
|
Energy Band gap (EG) |
1.1242 eV |
|
Melting Point |
1415 °C |
|
Thermal Conductivity |
150 Wm-1K-1 |
|
Thermal Expansion Coefficient |
2.6 x 10-6 K-1 |
|
Effective Density of States in the Conduction Band (NC) |
3 x 1025 m-3 |
|
Effective Density of States in the Valence Band (NV) |
1 x 1025 m-3 |
|
Relative Permittivity (εr) |
11.7 |
|
Electron Affinity |
4.05 eV |