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Fabrication of luminescent monolayered tungsten dichalcogenides quantum dots with giant spin-valley coupling

Journal Article


Abstract


  • A high yield (>36 wt %) method has been developed of preparing monolayered tungsten dichalcogenide (WS2) quantum dots (QDs) with lateral size ���8-15 nm from multilayered WS2 flakes. The monolayered WS2 QDs are, like monolayered WS2 sheets, direct semiconductors despite the flake precursors being an indirect semiconductor. However, the QDs have a significantly larger direct transition energy (3.16 eV) compared to the sheets (2.1 eV) and enhanced photoluminescence (PL; quantum yield ���4%) in the blue-green spectral region at room temperature. UV/vis measurements reveal a giant spin-valley coupling of the monolayered WS2 QDs at around 570 meV, which is larger than that of monolayered WS2 sheets (���400 meV). This spin-valley coupling was further confirmed by PL as direct transitions from the conduction band minimum to split valence band energy levels, leading to multiple luminescence peaks centered at around 369 (3.36 eV) and 461 nm (2.69 eV, also contributed by a new defect level). The discovery of giant spin-valley coupling and the strong luminescence of the monolayered WS2 QDs make them potentially of interests for the applications in semiconductor-based spintronics, conceptual valley-based electronics, quantum information technology and optoelectronic devices. However, we also demonstrate that the fabricated monolayered WS 2 QDs can be a nontoxic fluorescent label for high contrast bioimaging application. �� 2013 American Chemical Society.

UOW Authors


  •   Lin, Liangxu (external author)

Publication Date


  • 2013

Citation


  • Lin, L., Xu, Y., Zhang, S., Ross, I. M., Ong, A. C. M., & Allwood, D. A. (2013). Fabrication of luminescent monolayered tungsten dichalcogenides quantum dots with giant spin-valley coupling. ACS Nano, 7(9), 8214-8223. doi:10.1021/nn403682r

Scopus Eid


  • 2-s2.0-84884914732

Start Page


  • 8214

End Page


  • 8223

Volume


  • 7

Issue


  • 9

Place Of Publication


Abstract


  • A high yield (>36 wt %) method has been developed of preparing monolayered tungsten dichalcogenide (WS2) quantum dots (QDs) with lateral size ���8-15 nm from multilayered WS2 flakes. The monolayered WS2 QDs are, like monolayered WS2 sheets, direct semiconductors despite the flake precursors being an indirect semiconductor. However, the QDs have a significantly larger direct transition energy (3.16 eV) compared to the sheets (2.1 eV) and enhanced photoluminescence (PL; quantum yield ���4%) in the blue-green spectral region at room temperature. UV/vis measurements reveal a giant spin-valley coupling of the monolayered WS2 QDs at around 570 meV, which is larger than that of monolayered WS2 sheets (���400 meV). This spin-valley coupling was further confirmed by PL as direct transitions from the conduction band minimum to split valence band energy levels, leading to multiple luminescence peaks centered at around 369 (3.36 eV) and 461 nm (2.69 eV, also contributed by a new defect level). The discovery of giant spin-valley coupling and the strong luminescence of the monolayered WS2 QDs make them potentially of interests for the applications in semiconductor-based spintronics, conceptual valley-based electronics, quantum information technology and optoelectronic devices. However, we also demonstrate that the fabricated monolayered WS 2 QDs can be a nontoxic fluorescent label for high contrast bioimaging application. �� 2013 American Chemical Society.

UOW Authors


  •   Lin, Liangxu (external author)

Publication Date


  • 2013

Citation


  • Lin, L., Xu, Y., Zhang, S., Ross, I. M., Ong, A. C. M., & Allwood, D. A. (2013). Fabrication of luminescent monolayered tungsten dichalcogenides quantum dots with giant spin-valley coupling. ACS Nano, 7(9), 8214-8223. doi:10.1021/nn403682r

Scopus Eid


  • 2-s2.0-84884914732

Start Page


  • 8214

End Page


  • 8223

Volume


  • 7

Issue


  • 9

Place Of Publication