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In this work, a hybrid structure of multilayer transition-metal dichalcogenides (TMDs) and a ferroelectric polymer is designed to achieve passive control of optical properties in situ. The electrical polarization in the ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) polymer can regulate the photoluminescence (PL) in bilayer WSe 2 . The total PL emission intensity is substantially suppressed or enhanced under large gate voltage in bilayer WSe 2 . This is because electrons transfer between the conduction band K valley and the conduction band Λ valley by the electrostatic field in the P(VDF-TrFE) polymer. This electron transfer further adjusts the proportion of direct and indirect excitons and, in turn, changes the overall optical radiation efficiency. We also illustrate that the engineered PL originates from the external electric-field-dependent transferred electron effect. The theoretical result matches the experimental data well. This work demonstrates a device platform in which passive regulation is achieved using 2D TMDs modulated by polarized ferroelectric materials.

In recent years, the electrical characteristics of WSe 2 field-effect transistors (FETs) have been widely investigated with various dielectrics. Among them, being able to perfectly tune the polarity of WSe 2 is meaningful and promising work. In this work, we systematically study the electrical properties of bilayer WSe 2 FETs modulated by ferroelectric polymer poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)). Compared to traditional gate dielectric SiO 2 , the P(VDF-TrFE) can not only tune both electron and hole concentrations to the same high level, but also improve the hole mobility of bilayer WSe 2 to 265.96 cm 2 V -1 s -1 under SiO 2 gating. Its drain current on/off ratio is also improved to 2 × 10 5 for p-type and 4 × 10 5 for n-type driven by P(VDF-TrFE). More importantly, the ambipolar behaviors of bilayer WSe 2 are effectively achieved and maintained because of the remnant polarization field of P(VDF-TrFE). This work indicates that WSe 2 FETs with P(VDF-TrFE) gating have huge potential for complementary logic transistor applications, and paves an effective way to achieve in-plane p-n junctions.