Superior Piezoelectric Performance of Chemically Synthesized Transition Metal Dichalcogenides 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 MoS2-WSe2 heterostructure piezoelectric nanogenerator (PENG) is enhanced by ~47.5% if compared with WSe2 and ~ 29% if compared to MoS2 PENG, attributed to large band offset induced by heterojunction formation. This allows the scalable fabrication of self-powered energy harvesting piezoelectric nanogenerators, which can overcome the various shortcomings of complicated synthesis processes, complex fabrication steps, low yield and poor stability. The fabricated flexible, self-powered MoS2-WSe2 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 MoS2-WSe2 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.