Issue 21, 2015

Spatiotemporal dynamics of excitons in monolayer and bulk WS2

Abstract

Spatiotemporal dynamics of excitons in monolayer and bulk WS2 at room temperature is studied by transient absorption microscopy in the reflection geometry. Excitons are formed from photocarriers injected by a tightly focused 390 nm pump pulse, and monitored by detecting different reflection of a time-delayed and spatially scanned 620 nm probe pulse. We obtain exciton lifetimes of 22 ± 1 and 110 ± 10 ps in monolayer and bulk WS2, respectively. Both lifetimes are independent of the exciton density, showing the absence of multi-exciton recombination processes. Exciton diffusion coefficients of 60 ± 20 and 3.5 ± 0.5 cm2 s−1 are obtained in monolayer and bulk samples, respectively. These results provide a foundation for understanding excitons in this new material and its optoelectronic applications.

Graphical abstract: Spatiotemporal dynamics of excitons in monolayer and bulk WS2

Article information

Article type
Paper
Submitted
10 Jan 2015
Accepted
16 Apr 2015
First published
27 Apr 2015

Nanoscale, 2015,7, 9526-9531

Spatiotemporal dynamics of excitons in monolayer and bulk WS2

J. He, D. He, Y. Wang, Q. Cui, F. Ceballos and H. Zhao, Nanoscale, 2015, 7, 9526 DOI: 10.1039/C5NR00188A

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