Low-cost solar grade silicon powder through iterative gettering of thermally treated porous silicon

Studied on electrorefining metallurgical grade silicon to prepare solar grade silicon(SOG-Si) with electrochemical method in molten KCl and NaF mixture salt. Molten KCl and NaF mixture salt as electrolyte, the metallurgical grade silicon as anode and little metal nickel crucible for collecting silicon powder as cathode, electrorefining experiments were performed at 800 and 2.0V for 14h under dry argon atmosphere. The results showed that the metallurgical grade silicon could be dissolved and deposited on the cathode through molten potassium chloride (KCl) and sodium fluoride (NaF) mixture salt electrolyte. The nickel crucible was full of deposit, which was pure silicon by XRD and EDS. Purity of refined silicon was close to 99.99%, most of impurities like B and P were reduced significantly. Impurity level of silicon was reduced to the desired range for SOG-Si by advancement of the materials for the cell components.

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Ca-Si Alloy Addition Followed by Acid Leaching as a Route to Solar-Grade Silicon

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.881-883.1562 ◽

2014 ◽

Vol 881-883 ◽

pp. 1562-1567

Author(s):

Peng Zou ◽

Kui Xian Wei ◽

Wen Hui Ma ◽

Ke Qiang Xie ◽

Ji Jun Wu ◽

...

Keyword(s):

Phosphorus Content ◽

Low Cost ◽

Acid Leaching ◽

Impurity Phase ◽

Solar Grade Silicon ◽

Metallurgical Grade Silicon ◽

Before And After ◽

Alloy Addition ◽

Grade Silicon ◽

Leaching Condition

In present, refining of metallurgical grade silicon is one of the promising routes to low-cost solar grade silicon for solar cells. Alloying with Ca has shown a great potential as efficient refining method of MG-Si in combination with acid leaching. Compared with Ca metal, Ca-Si alloy is cheaper and more secure. Great removal of impurity depends on microstructure of MG-Si after alloyed with Ca-Si alloy. In the work, the change of impurity phase which was performed by the change of the microstructure of MG-Si before and after alloyed with Ca-Si alloy has been analyzed. It was determined that CaSi2phase contained significant phosphorus content after alloying with Ca-Si alloy, It also investigated the optimal acid leaching condition after leaching, which confirmed that metallurgical grade silicon with Ca-Si alloy addition followed by acid leaching could be a potential route to remove phosphorus from MG-Si.

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Solar-grade silicon powder prepared by combining combustion synthesis with hydrometallurgy

Solar Energy Materials and Solar Cells ◽

10.1016/j.solmat.2010.10.016 ◽

2011 ◽

Vol 95 (2) ◽

pp. 745-750 ◽

Cited By ~ 32

Author(s):

C.W. Won ◽

H.H. Nersisyan ◽

H.I. Won

Keyword(s):

Combustion Synthesis ◽

Silicon Powder ◽

Solar Grade Silicon ◽

Grade Silicon

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Determination of impurity distributions in ingots of solar grade silicon by neutron activation analysis

Radiochimica Acta ◽

10.1515/ract-2016-2687 ◽

2017 ◽

Vol 105 (7) ◽

Cited By ~ 1

Author(s):

Barbara Karches ◽

Jonas Schön ◽

Heiko Gerstenberg ◽

Gabriele Hampel ◽

Patricia Krenckel ◽

...

Keyword(s):

Neutron Activation Analysis ◽

Theoretical Model ◽

Activation Analysis ◽

Neutron Activation ◽

Low Cost ◽

Solar Grade Silicon ◽

Metal Impurities ◽

Crystallization Experiments ◽

Grade Silicon

AbstractIn a series of crystallization experiments, the directional solidification of silicon was investigated as a low cost path for the production of silicon wafers for solar cells. Instrumental neutron activation analysis was employed to measure the influence of different crystallization parameters on the distribution of 3d-metal impurities of the produced ingots. A theoretical model describing the involved diffusion and segregation processes during the solidification and cooling of the ingots could be verified by the experimental results. By successive etching of the samples after the irradiation, it could be shown that a layer of at least 60 μm of the samples has to be removed to get real bulk concentrations.

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