Defects-assisted piezoelectric response in liquid exfoliated MoS₂nanosheets

MoS₂is an intrinsic piezoelectric material which offers applications such as energy harvesting, sensors, actuators, flexible electronics, energy storage and more. Surprisingly, there are not any suitable, yet economical methods that can produce quality nanosheets of MoS₂in large quantities, hence limiting the possibility of commercialisation of its applications. Here, we demonstrate controlled synthesis of highly crystalline MoS₂nanosheets via liquid phase exfoliation of bulk MoS₂, following which we report piezoelectric response from the exfoliated nanosheets. The method of piezo force microscopy was employed to explore the piezo response in mono, bi, tri and multilayers of MoS₂nanosheets. The effective piezoelectric coefficient of MoS₂varies from 9.6 to 25.14 pm V^-1. We attribute piezoelectric response in MoS₂nanosheets to the defects formed in it during the synthesis procedure. The presence of defects is confirmed by x-ray photoelectron spectroscopy.