Highly crystalline Fe sub(2)GeS sub(4) nanocrystals: green synthesis and their structural and optical characterization

The olivine Fe sub(2)GeS sub(4) compound has attracted much attention as a thermodynamically stable derivative of pyrite FeS sub(2), which has been studied extensively as an earth-abundant light-absorbing candidate material. Nevertheless, reports on nanocrystalline Fe sub(2)GeS sub(4) and its optoel...

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Bibliographic Details
Published in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2015-01, Vol.3 (5), p.2265-2270
Main Authors: Park, Bo-In, Yu, Seunggun, Hwang, Yoonjung, Cho, So-Hye, Lee, Jae-Seung, Park, Cheolmin, Lee, Doh-Kwon, Lee, Seung Yong
Format: Article
Language:English
Subjects:
Derivatives
Micrographs
Nanocrystals
Optoelectronics
Photoluminescence
Sulfur
Sustainability
Synthesis
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Summary:The olivine Fe sub(2)GeS sub(4) compound has attracted much attention as a thermodynamically stable derivative of pyrite FeS sub(2), which has been studied extensively as an earth-abundant light-absorbing candidate material. Nevertheless, reports on nanocrystalline Fe sub(2)GeS sub(4) and its optoelectronic properties are limited. Herein, Fe sub(2)GeS sub(4) nanocrystals are synthesized viaa solvent-free mechanochemical process. This process not only reduces the synthesis time, but also avoids the use of hazardous solvents, thereby mitigating environmental concerns. The crystallinity of the synthesized nanocrystals is significantly enhanced by a post-heat treatment in a sulfur-containing atmosphere, showing no phase decomposition. Lattice-resolved micrographs reveal that the post-annealed nanocrystals have a hexagonal-faceted platelet structure with (002) base planes. The oxide layer near the surface region is removed by the post-annealing process, most likely due to the replacement of oxygen with sulfur in the controlled atmosphere. The post-annealed Fe sub(2)GeS sub(4) nanocrystals clearly exhibit an optical band gap of 1.43 eV and near-band-edge photoluminescent emission at 1.41 eV. This is the first experimental demonstration of the Fe sub(2)GeS sub(4) nanocrystals having optoelectronic properties that are suitable for solar applications.
ISSN:2050-7488
2050-7496
DOI:10.1039/c4ta05850j