Excitons Bound To Defects

What Has Been Achieved

A photoluminescence feature has been identified as excitons bound to charged sulfur vacancies in 2D WS2.

Importance of Achievement

The study identifies a fast, inexpensive, and non-destructive characterization method to assess the quality of 2D transition metal dichalcogenide crystals.

Unique Features of the MIP That Enabled Project

Close collaboration between synthesis, characterization, and theory efforts.


V. Carozo, Y. Wang, K. Fujisawa, B. R. Carvalho, A. McCreary, S. Feng, Z. Lin, C. Zhou, N. Perea-López, A. L. Elías, B. Kabius, V. H. Crespi, and M. Terrones, “Optical identification of sulfur vacancies: Bound excitons at the edges of monolayer tungsten disulfide”, Sci. Adv. 3, e1602813 (2017).

Identifying Defects. An atomically thin WS2 flake is shown to be excited by a laser and emit light at a different wavelength at the three edges of the triangular flake. The inset illustrates an electron-hole pair being trapped at a sulfur vacancy site.
Carozo, Wang, Fujisawa, Carvalho, McCreary, Feng, Lin, Zhou, Perea-López, Elías, Kabius, Crespi, Terrones, Penn State, Universidade Federal de Minas Gerais
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