Layer‐Dependent Exciton Modulation Characteristics of 2D MoS2 Driven by Acoustic Waves

Abstract

AbstractAcoustic waves were recently utilized to modulate and control the electronic, optical, and magnetic properties of 2D materials. Among 2D materials, the mechanically exfoliated MoS2 with a perfect crystal structure provides an ideal platform to study its exciton characteristics. However, layer‐dependent exciton modulation characteristics of the 2D materials are still not systematically investigated under acoustic waves. Here, the in situ confocal fluorescence spectroscopy is used to probe the behavior of the excitons in 2D MoS2 under acoustic excitation. The high‐frequency acoustic field with a radial vibration frequency of 200 kHz is used as the excitation source which is produced by the piezoelectric ceramic chip. The results show that the exciton characteristics strongly depend on the layer numbers of the MoS2: under acoustic excitation, the fluorescence quenching degree in the odd layers of the sheets with intrinsic piezoelectricity is remarkably larger than that in the even layers without piezoelectricity; moreover, the PL peak position of the MoS2 with the odd layers is blue‐shifted with increase of the applied power while that with the even layers remains unchanged. Thus, this work paves the way to develop high‐performance optical and optoelectronic devices driven by acoustic waves.