Silicon Electrodeposition in a Water-Soluble KF–KCl Molten Salt: Properties of Si Films on Graphite Substrates

Yasuda, Kouji; Kato, Tomonori; Norikawa, Yutaro

doi:10.1149/1945-7111/ac3272

Cited by 15 publications

(36 citation statements)

References 31 publications

(100 reference statements)

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“…The semiconductor characteristics of Si films deposited can be modified based on the Si precursor metallic dopant added to the melt. For instance, Si films electrodeposited in KF–KCl–K 2 SiF 6 molten salts exhibit n-type semiconductor characteristics, while Si films deposited in KF–KCl–SiCl 4 melts exhibit p-type semiconductor characteristics ( Yasuda et al, 2021 ). The difference in the semiconductor characteristics can be attributed to the different impurities present in the Si films.…”

Section: Molten Saltsmentioning

confidence: 99%

Silicon electrowinning by molten salts electrolysis

Padamata

Sævarsdóttir

2023

Front. Chem.

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Electrochemically produced Si in molten salts can be used to fabricate electronic and photovoltaic devices. The major factors influencing the structure and morphology of Si deposits are electrolyte composition, applied current densities and overpotentials, type of precursors, operating temperature, and electrodeposition duration. For Si electrodeposition, a less corrosive electrolyte with the ability to dissolve Si species and easily soluble in water should be used. This review provides a brief analysis of the Si production by electrolysis in molten salts.

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Section: Molten Saltsmentioning

confidence: 99%

Silicon electrowinning by molten salts electrolysis

Padamata

Sævarsdóttir

2023

Front. Chem.

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“…Cl 2 gas evolution in the positive potential region was also confirmed by cyclic voltammetry. 20 The electrodeposition of Si was conducted by galvanostatic electrolysis at 923 and 1073 K. 1,[20][21][22]24 Si films were successfully electrodeposited at both temperatures using K 2 SiF 6 or SiCl 4 as the Si(IV) ion source. In general, the current efficiency is ∼90% under optimal conditions.…”

Section: Electrodeposition Of Siliconmentioning

confidence: 99%

“…Hence, the large grains of Si films obtained at higher temperatures are advantageous in the use of Si solar cells. Figure 3a shows cross-sectional SEM images of the samples obtained by the galvanostatic electrolysis of graphite plate electrodes at various current densities and K 2 SiF 6 concentrations in molten KF−KCl at 1073 K. 1 Si films with a smooth surface were obtained under certain conditions, for example, 3.5 mol % and −100 mA cm −2 . We then investigated the photoelectrochemical properties of the electrodeposited Si films.…”

Section: Electrodeposition Of Siliconmentioning

confidence: 99%

“…The difference in the type of electrodeposited Si film was caused by the difference in unintentional impurities in the molten salts. Table lists the impurity contents of the Si films electrodeposited in the KF–KCl molten salts . The Si film electrodeposited in molten KF–KCl–K 2 SiF 6 contains <35 ppmw of impurities, including 11 ppmw of P, resulting in an n-type semiconductor.…”

Section: Electrodeposition Of Siliconmentioning

confidence: 99%

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A New Concept of Molten Salt Systems for the Electrodeposition of Si, Ti, and W

Norikawa

2023

Acc. Chem. Res.

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Conspectus This Account describes the results of the electrodeposition of film-like Si, Ti, and W by utilizing molten salts selected based on a new concept. The proposed molten salt systems, KF–KCl and CsF–CsCl, have high fluoride ion concentrations, relatively low operating temperatures, and high solubility in water. First, KF–KCl molten salt was used for the electrodeposition of crystalline Si films to establish a new fabrication method for Si solar cell substrates. The electrodeposition of Si films from the molten salt at 923 and 1023 K was successfully achieved using K2SiF6 or SiCl4 as the Si ion source. The crystal grain size of Si was larger at higher temperatures, indicating that higher temperatures are advantageous for the application of Si solar cell substrates. The resulting Si films underwent photoelectrochemical reactions. Second, the electrodeposition of Ti films using the KF–KCl molten salt was investigated to easily impart the properties of Ti, such as high corrosion resistance and biocompatibility, to various substrates. Ti films with a smooth surface were obtained from the molten salt containing Ti(III) ions at 923 K. Electrochemical tests in artificial seawater revealed that the electrodeposited Ti films had no voids and cracks and that the obtained Ti-coated Ni plate had a high corrosion resistance against seawater. Finally, the molten salts were used for the electrodeposition of W films, which are expected to be used as diverter materials for nuclear fusion. Although the electrodeposition of W films was successful in the KF–KCl–WO3 molten salt at 923 K, the surface of the films was rough. Therefore, we used the CsF–CsCl–WO3 molten salt, which can be employed at lower temperatures than KF–KCl–WO3. We then successfully electrodeposited W films with a mirror-like surface at 773 K. Such a mirror-like metal film deposition has not been reported before using high-temperature molten salts. Further, the temperature dependence of the crystal phase of W was revealed by the electrodeposition of W films at 773–923 K. β-W was obtained at 773 and 823 K, α-W was obtained at 923 K, and a mixed phase of α- and β-W was obtained at 873 K. In addition, single-phase β-W films with a thickness of approximately 30 μm were electrodeposited, which has not been reported before. The results show that our proposed molten salt systems are advantageous for electroplating Si, Ti, and W. Our approach is also expected to be applicable for the electrodeposition of other metals such as Zr, Nb, Mo, Hf, and Ta.

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“…In [46], the effects of cathode current density, substrate material, source (K2SiF6, SiCl4), and silicon ion concentration in the KF-KCl melt on the morphology of electrolytic silicon deposits were studied for a temperature of 750 °C. The optimal conditions for obtaining smoothed silicon films with a thickness of 20 to 60 μm were determined and their photosensitivity were demonstrated.…”

Section: Electrolytic Silicon In Solar Cellsmentioning

confidence: 99%

Silicon Electrodeposition for Microelectronics and Distributed Energy: A Mini-Review

Suzdaltsev

2022

Electrochem

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Due to its prevalence in nature and its particular properties, silicon is one of the most popular materials in various industries. Currently, metallurgical silicon is obtained by carbothermal reduction of quartz, which is then subjected to hydrochlorination and multiple chlorination in order to obtain solar silicon. This mini-review provides a brief analysis of alternative methods for obtaining silicon by electrolysis of molten salts. The review covers factors determining the choice of composition of molten salts, typical silicon precipitates obtained by electrolysis of molten salts, assessment of the possibility of using electrolytic silicon in microelectronics, representative test results for the use of electrolytic silicon in the composition of lithium-ion current sources, and representative test results for the use of electrolytic silicon for solar energy conversion. This paper concludes by noting the tasks that need to be solved for the practical implementation of methods for the electrolytic production of silicon, for the development of new devices and materials for energy distribution and microelectronic application.

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Silicon Electrodeposition in a Water-Soluble KF–KCl Molten Salt: Properties of Si Films on Graphite Substrates

Cited by 15 publications

References 31 publications

Silicon electrowinning by molten salts electrolysis

Silicon electrowinning by molten salts electrolysis

A New Concept of Molten Salt Systems for the Electrodeposition of Si, Ti, and W

Silicon Electrodeposition for Microelectronics and Distributed Energy: A Mini-Review

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