Silicon of the area-related balance of systems
Silicon is a chemicalcompound with symbol Si and its atomic number inthe periodic table is 14. It is a hard and brittle crystalline solid witha blue-grey metallic glint. It is the 8th most common element in the universe by mass.
Earth’s crust iscomposed about 90% of silicate minerals, making silicon the second most abundant element in the Earth’s crustafter oxygen. Silicon accounts for 28% of the weight of Earth’s crust. 15 Figure 1: Silicon 16 Figure 2: Silicon Structure17There are many uses of silicon in the world. It has alarge impact on modern world economy. It is used in electronics, alloys and infact in mechanical watches.
Most free silicon is used in the steel refining, aluminium-casting, and fine chemicalindustries. (often to make fumed silica). Even more visible, therelatively small portion of very highly purified silicon used in semiconductorelectronics (< 10%) is essential to integrated circuits most computers, cell phones, and moderntechnology depend on it. Silicon is the basis ofwidely used polymer which is known as silicone.The crystalline silicon can be classified in this way:· Monocrystalline silicon (mono-Si)· Multi-crystalline silicon (multi-Si)· Ribbonsilicon (ribbon-Si), has currently no market. 18 Crystallinesilicon is abundant, non-toxic, low-cost that allows the fabrication of cellswith high and stable conversion efficiency, is the most mature photovoltaicmaterial which is the long-term market leader.
There is very widespreadinfrastructure available in crystalline silicon technology, both within thephotovoltaic and integrated circuit industries. Crystalline silicon moduleshave substantially higher efficiency than any non-concentrating modules on themarket, which reduces the cost of the area-related balance of systemscomponents. 19Single crystal silicon is perhaps the most importanttechnological material of the last few decades the “silicon era” 20. Monocrystallinesilicon is the base material for silicon chips that are usedworldwide in all electronic equipment today. Silicon chips are the base ofmodern electronics and computing system.
The dominant photovoltaic material is crystallinesilicon. Monocrystalline silicon used in photovoltaic cell because of its much lowerimpurity levels than those required for solar cells. 2.2: Solar cell2.2.1: HistoryThe photovoltaic effect wasfirst experimented by French physicist EdmondBecquerel. In 1839, at age 19, he built the world’s firstphotovoltaic cell in his father’s laboratory 21.
WilloughbySmith first described the “Effect of Light onSelenium during the passage of an Electric Current” in a 20 February 1873.First solid state photovoltaiccell in 1883 by CharlesFritts. He made it by coating the semiconductor selenium witha thin layer of gold inorder to form the junctions, the device was only around 1% efficient.In1888 Russian physicist Aleksandr Stoletov builtthe first cell based on the outer photoelectric effect discoveredby Heinrich Hertz in1887 22.In 1905 Albert Einstein proposeda new quantum theory of light and explained the photoelectric effect, for whichhe received the Nobel Prize in Physics in1921 23. Vadim Lashkaryov discovered p-n-junctionsin Cu{displaystyle _{2}}O and silver sulphideprotocells in 1941 24.
RussellOhl patentedthe modern junction semiconductor solar cell in 1946 while working on theseries of advances that would lead to the transistor 2526. Thefirst practical photovoltaic cell was publicly experimented on 25 April 1954at Bell Laboratories invented by Calvin Souther Fuller and GeraldPearson 27 28.Solar cells gained prominence with their incorporation into the 1958 VanguardI satellite.Solar cells made of crystalline silicon areoften called conventional, traditional, or first-generation solarcells, as they were developed in the 1950s and remained the most common type upto the present time. 29302.2.
2: Classifications of solarcell: Thevarious types of materials applied for photovoltaic solar cells includes mainlyin the form of silicon (single crystal, multi-crystalline, amorphous silicon) 3133 cadmium-telluride 31 32, copper-indium-gallium-selenide 34, andcopper-indium-gallium-sulfide 35 36. On the basis of these materials, thephotovoltaic solar cells are categorized into various classes as discussed inthe following sections.2.2.
3: First generation solar cell: Thefirst-generation silicon cell is produced in silicon wafers. It is the oldestand most popular method for producing solar cell because of its high-powerefficiency. The first-generation solar cell can be classified into two sections35 36.1. Single/Monocrystalline silicon solar cell2. Poly/Multycrystalline silicon solar cell 2.2.
4: Second generation solar cell:Secondgeneration solar cells are mainly thin film solar cell and amorphous-Silicon.These are more economical compared to 1st generation silicon wafersolar cells. Thin film solar cells have very thin light absorbing layer up to 1?m thick whereas Silicon wafer cells have 350 ?m thick.
Secondgeneration solar cell can be classified as1. Amorphoussilicon thin film solar cell.2. CadmiumTelluride thin film solar cell.
3. CopperIndium Gallium Di-Selenide solar cell. Figure: Second generation solar cell37 2.2.5: Third Generation Solar Cell: Thirdgeneration solar cells are the new promising technologies. But these are notcommercially investigated in detail.
Most developed 3rd generationsolar cells are 38· Nano crystal-based solar cell.· Polymer -based solar cell.· Dye-sensitized solar cell.
· Concentrated solar cell.Inthis thesis work, we have given our concentration in monocrystalline siliconsolar cells.2.2.6: Monocrystalline silicon solar cell:Monocrystalline silicon solar cell is produced fromthe single crystal of silicon. The process of manufacturing solar cell iscalled Czochralski. 39 During the process, Si crystals are sliced from thebig sized ingots.
Theselarge single crystal manufactures require exact process because the process of”recrystallizing” the cell is more expensive and also a multi process. Theefficiency of mono-crystalline single-crystalline silicon solar cells liesbetween 17% – 18% 34.
