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Low-cost solar cells and methods for fabricating low cost substrates for solar cells

A substrate and wafer technology, applied in the field of battery device structures, can solve the problems of limited availability of pure silicon wafers, low photovoltaic conversion efficiency of thin-film silicon solar cells, and cost constraints, so as to avoid costs, health and environmental hazards, reduce cost, the effect of improving conversion efficiency

Inactive Publication Date: 2012-03-21
SUNPREME
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0014] 2. The photovoltaic conversion efficiency of thin-film silicon solar cells is low, sometimes less than half that of silicon wafer-based solar cells
Thus, the silicon wafer-based camp is limited by the availability of pure silicon wafers, while the thin-film camp is limited by conversion efficiencies mainly due to insufficient absorption of light in glass substrates, and by the production of thicker intrinsic hydrogenated silicon absorber layers Required SiH 4 gas cost constraints

Method used

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  • Low-cost solar cells and methods for fabricating low cost substrates for solar cells
  • Low-cost solar cells and methods for fabricating low cost substrates for solar cells
  • Low-cost solar cells and methods for fabricating low cost substrates for solar cells

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Embodiment 1

[0070] Three nines of metallurgical grade silicon was produced by induction melting two nines of silicon pellets in an approximately 1.5 m x 1.5 m graphite crucible, followed by slow cooling into a cylindrical shape over 24 hours. The carbon-rich surface shell is removed and the cylinders are crushed into grains or granules. The resulting material contains B and P, but is usually p-type with a resistivity in the range of 0.1-1 ohm·cm. The resulting material was then cast into metallurgical grade silicon boles of approximately 0.5m x lm x lm with controlled cooling and dopant adjustment. The block was cut into ingots of 16 square cross-sections with one side slightly larger than 5". Polygonal large grain structure exposed on the backside of the wafer. This produced about 500 metallurgical grade silicon wafers of four-nines and five-nines purity. The wafers were divided into two groups using 4-point probe measurements, the main group having 0.3- Resistivity of 0.5 ohm cm, the ...

Embodiment 2

[0073] Formation of intrinsic passivation layers on low-cost metallurgical-grade substrates by depositing nanoscale Si:H film stacks on the front, “device” side and oppositely doped a-Si:H films on the back, “contact” side Single heterojunction for device structures. Metallurgical grade substrates do not have to specifically thin the substrate from 500 μm to 250 μm as is done for crystalline Si substrates, eliminating losses. Thicker wafers provide more robust handling in automated production lines. The material also avoids the cost, cycle, and complexity of polysilicon-based gasification, solidification, melting, and pulling processes, as it passes just outside the metallurgical-grade substrate face passivated by nanoscale intrinsic a-Si:H films thin Si:H films to create the active device.

[0074] Metallurgical grade substrates can be formed in standard sizes such as 6 inches, 8 inches, and 12 inches, and can be processed in standard semiconductor PECVD processing equipmen...

Embodiment 3

[0076] Figure 9A Instructions are usually referred to in this article as SmartSi TM An example of a process for fabricating a prepared substrate for solar cells. In step 900, metallurgical grade quartz is melted and reduced in an electrolytic cell containing graphite electrodes, then allowed to cool and solidify to provide a metallurgical silicon ingot of about two nines. The ingot is broken into pellets, treated in chemicals to leach surface impurities, and cast into ingots. The ingot is then stripped of its outer shell and broken into three to five nines of metallurgical silicon blocks. The resulting blocks are sorted according to their resistivity.

[0077] In step 915 the sorted MG silicon ingots are cast. The melt is allowed to solidify into bulk, processed in step 920, cut into ingots, and sliced ​​into wafers, eg, 350 microns thick. In addition, each wafer is also etched to remove dicing damage and to clean and prepare the surface of the wafer for further processi...

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Abstract

The invention discloses low-cost solar cells and methods for fabricating low cost substrates for solar cells. Substrates for solar cells are prepared by etching a plurality of metallurgical grade wafers; depositing aluminum layer on backside of each wafer; depositing a layer of hydrogenated silicon nitride on front surface of each wafer; annealing the wafers at elevated temperature; removing the hydrogenated silicon nitride without disturbing the aluminum layer. A solar cell is then fabricated on the front surface of the wafer while the aluminum remains to serve as the back contact of the cell.

Description

technical field [0001] The present invention relates to solar photovoltaic cells, and more particularly to methods of manufacturing low cost matrix materials for use with such cells and methods for manufacturing low cost cells and resulting cell device structures. Background technique [0002] Conventional energy generation from fossil fuels poses the greatest threat to the peace of the planet since the last ice age. Of all the alternative energy sources, solar photovoltaic cells are arguably the cleanest, ubiquitous and probably the most reliable option compared to other sources such as ethanol, hydropower and wind energy, in addition to energy savings. The principle is a simple solid-state p-n junction that converts light into a small DC voltage. Batteries can be stacked to charge a car battery or feed into the grid through DC / AC conversion. Among the various semiconductor materials that can be used for this purpose, silicon accounts for 99% of the production of photovol...

Claims

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Application Information

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IPC IPC(8): H01L31/20H01L31/0352
CPCY02P70/50
Inventor 阿肖克·辛哈马雯
Owner SUNPREME
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