Superior piezoelectric performance of chemically synthesized transition metal dichalcogenide heterostructures for self-powered flexible piezoelectric nanogenerator

In addition to the superior electrical and optoelectronic attributes, ultrathin two-dimensional transition metal dichalcogenides (TMDCs) have evoked appreciable attention for their piezoelectric properties. In this study, we report, the piezoelectric characteristics of large area, chemically exfoliated TMDCs and their heterostructures for the first time, as verified by piezoelectric force microscopy measurements. Piezoelectric output voltage response of the MoS -WSe heterostructure piezoelectric nanogenerator (PENG) is enhanced by ∼47.5% if compared with WSe and ∼29% if compared to MoS PENG, attributed to large band offset induced by heterojunction formation. This allows the scalable fabrication of self-powered energy harvesting PENGs, which can overcome the various shortcomings of complicated synthesis processes, complex fabrication steps, low yield, and poor stability. The fabricated flexible, self-powered MoS -WSe heterostructure nanogenerator exhibits piezoelectric output ∼46 mV under a strain of ∼0.66% yielding a power output ∼12.3 nW, which offers better performance than other two-dimensional material based piezoelectric devices and also reveals the ability of bio-mechanical energy harvesting. This cost effective approach to fabricate eco-friendly MoS -WSe based fatigue free, superior performance piezoelectric-nanogenerators can be utilized to evolve flexible energy harvesting devices and may also be attractive as a self-powered, smart wearable sensor devices.