Acoustically-Driven Trion and Exciton Modulation in Piezoelectric Two-Dimensional MoS2

Nano Lett. 2016 Feb 10;16(2):849-55. doi: 10.1021/acs.nanolett.5b02826. Epub 2016 Jan 7.

Abstract

By exploiting the very recent discovery of the piezoelectricity in odd-numbered layers of two-dimensional molybdenum disulfide (MoS2), we show the possibility of reversibly tuning the photoluminescence of single and odd-numbered multilayered MoS2 using high frequency sound wave coupling. We observe a strong quenching in the photoluminescence associated with the dissociation and spatial separation of electrons-holes quasi-particles at low applied acoustic powers. At the same applied powers, we note a relative preference for ionization of trions into excitons. This work also constitutes the first visual presentation of the surface displacement in one-layered MoS2 using laser Doppler vibrometry. Such observations are associated with the acoustically generated electric field arising from the piezoelectric nature of MoS2 for odd-numbered layers. At larger applied powers, the thermal effect dominates the behavior of the two-dimensional flakes. Altogether, the work reveals several key fundamentals governing acousto-optic properties of odd-layered MoS2 that can be implemented in future optical and electronic systems.

Keywords: MoS2; Two-dimensional materials; exciton; photoluminesence; piezoelectricity; surface acoustic waves; trion.

Publication types

  • Research Support, Non-U.S. Gov't