Amongst 2-dimensional (2D) semiconductors of the transition-metal di-chalcogenide (TMDC) family [1], tungsten diselenide (WSe2) has shown ambipolar behavior [2], [3] coupled with high carrier mobility [4] and CMOS-like devices have been experimentally demonstrated using chemical doping of the material [5], [6]. However, since chemical doping is often non-compatible with conventional CMOS processes and is limited by the desorption of the chemical species used [5]–[7], we explore the possibilities offered by electrostatic doping. Here, we exploit the presence of Schottky barrier contacts in WSe 2 , and using electrostatic doping we achieve dynamic control of the polarity of the transistors. We fabricate, for the first time on a 2D material, a doping-free complementary inverter, providing a path for the realization of CMOS logic with a single ambipolar, undoped 2D semiconducting material.