The Polyx photovoltaic technology: progress and prospects

Fally, J.; Fabre, E.; Chabot, B.

doi:10.1051/rphysap:01987002207052900

Cited by 16 publications

(7 citation statements)

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“…Other 'metallic' impurities are also found in photovoltaic wafers. Depending on the type of metal, even very low concentrations can have a negative influence on the minority carrier lifetime and solar cell efficiency [12,13].…”

Section: Impuritiesmentioning

confidence: 99%

New crystalline silicon ribbon materials for photovoltaics

Hahn

Schönecker

2004

J. Phys.: Condens. Matter

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The objective of this article is to review, in relation to photovoltaic applications, the current status of crystalline silicon ribbon technologies as an alternative to technologies based on wafers originating from ingots. Increased wafer demand, the foreseeable silicon feedstock shortage, and the need for a substantial module cost reduction are the main issues that must be faced in the booming photovoltaic market. Ribbon technologies make excellent use of silicon, as wafers are crystallized directly from the melt at the desired thickness and no kerf losses occur. Therefore, they offer a high potential for significantly reducing photovoltaic electricity costs as compared to technology based on wafers cut from ingots. However, the defect structure present in the ribbon silicon wafers can limit material quality and cell efficiency. We will review the most successful of the ribbon techniques already used in large scale production or currently in the pilot demonstration phase, with special emphasis on the defects incorporated during crystal growth. Because of the inhomogeneous distribution of defects, mapped characterization techniques have to be applied. Al and P gettering studies give an insight into the complex interaction of defects in the multicrystalline materials as the gettering efficiency is influenced by the state of the chemical bonding of the metal atoms. The most important technique for improvement of carrier lifetimes is hydrogenation, whose kinetics are strongly influenced by oxygen and carbon concentrations present in the material. The best cell efficiencies for laboratory-type (17%-18%; cell area: 4 cm 2) as well as industrial-type (15%-16%; cell area: 80 cm 2) ribbon silicon solar cells are in the same range as for standard wafers cut from ingots. A substantial cost reduction therefore seems achievable, although the most promising techniques need to be improved.

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Section: Impuritiesmentioning

confidence: 99%

New crystalline silicon ribbon materials for photovoltaics

Hahn

Schönecker

2004

J. Phys.: Condens. Matter

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“…For example, when using MG-Si with a phosphorus content of 30 mass ppm, the targeted P content of SOG-Si material is below 0.1 mass ppm, 3) and the allowable P content of the SOG-Si wafer for obtaining 95% of the maximum conversion efficiency (conversion ratio of solar to electric energy) with 0% P is below 0.012 mass ppm. 4) Directional solidification is used to remove certain impurities, but is not effective for dephosphorization of molten silicon because the equilibrium partition coefficient of P is 0.35. 5) High frequency vacuum melting and resistor heating 6,7) and electron beam (EB) melting 8) were investigated as possible phosphorous removal techniques.…”

Section: Introductionmentioning

confidence: 99%

Evaporation of Phosphorus in Molten Silicon by an Electron Beam Irradiation Method

Hanazawa¹,

Yuge²,

Kato³

2004

Mater. Trans.

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The evaporation behavior of phosphorus in molten silicon during electron beam irradiation was investigated with the aim of producing solar grade silicon (SOG-Si) from metallurgical grade silicon (MG-Si) by a sequential metallurgical process. Batch experiments showed that the evaporation rate of phosphorus increased in proportion to the power of the electron beam and phosphorus content. The phosphorus removal rate was controlled by free evaporation from the molten silicon surface. Electron beam irradiation makes it possible to secure a higher temperature at the free liquid surface, which results in more efficient dephosphorization. A continuous flow experiment indicated that the phosphorus concentration at the outlet increased when the silicon feed rate was raised, which was attributed to the fact that the hearth residence time of the molten silicon was proportionally shorter. Thus, the flow of molten silicon in the hearth did not behave as a complete mixed reactor flow type reaction, but was close to a plug flow type reaction. With a 150 kg scale pilot manufacturing plant, MG-Si containing about 25 mass ppm of phosphorus was successfully purified to P < 0.1 mass ppm.

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“…Therefore, much research has done into the development of silicon resistant refractory materials with the aim of minimising the resulting contamination [37]. The result was that most ceramic materials produced in combination with metal-oxide binders cannot be used due to the very low contamination tolerance of silicon wafers to metallic impurities [38,39]. The same is true for ceramics including doping elements, such as B in BN or Al in SiAlON.…”

Section: Refractory Materialsmentioning

confidence: 99%

New Crystalline Si Ribbon Materials for Photovoltaics

Hahn¹,

Schönecker²,

Gutjahr³

2009

Advances in Materials Research

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Abstract. The objective of this chapter is to review, for photovoltaic application, the current status of crystalline silicon ribbon technologies as an alternative to wafers originating from ingots. Increased wafer demand, the current silicon feedstock shortage and the need of a substantial module cost reduction are the main issues that must be faced in the booming photovoltaic market. Ribbon technologies make excellent use of the silicon, as wafers are crystallised directly from the melt in the desired thickness and no kerf losses occur. Therefore, they offer a high potential to significantly reduce photovoltaic electricity costs when compared to wafers cut from ingots. Nevertheless, the defect structure present in the ribbon silicon wafers can limit material quality and cell efficiency. Ribbon GrowthTo provide an answer to the rapidly growing demand for cheap and easily available solar electricity, the photovoltaic industry is looking for more cost efficient and faster manufacturing processes for all steps of the value chain from silicon feedstock to crystallisation and wafering, cell processing and finally module fabrication. Silicon ribbons, as an alternative to silicon wafers that have been crystallised in the form of ingots and then cut into wafers, have, due to their higher silicon usage and potential for high production speed, significant advantages with respect to cost and throughput. However, a more complex technology and different wafer properties that often result in slightly lower conversion efficiencies are obstacles to be overcome.In principle, all ribbon processes have the characteristics that almost all silicon supplied into the process is converted into wafers. There is also no wafer cutting from a block, although in dependence upon the production method separation of larger sheets into wafers may be needed. Depending upon the type of crystallisation, silicon ribbon growth processes are either relatively slow processes, which can be run on rather low-cost equipment or high-speed processes operated with rather complex machinery.

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The Polyx photovoltaic technology: progress and prospects

Cited by 16 publications

References 0 publications

New crystalline silicon ribbon materials for photovoltaics

New crystalline silicon ribbon materials for photovoltaics

Evaporation of Phosphorus in Molten Silicon by an Electron Beam Irradiation Method

New Crystalline Si Ribbon Materials for Photovoltaics

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