MoS2 triboelectric nanogenerators based on depletion layers

We developed MoS2 triboelectric nanogenerators (TENGs) using a large-sized monolayer MoS2 grown by chemical vapor deposition. To investigate the effect of a depletion layer formed across a Schottky or pn junction on the output performance of MoS2 TENGs, three types of TENGs having different contacts, i.e., an ohmic contact, a Schottky contact, and a pn junction, were investigated. During pressing, the TENGs with the Schottky contact and pn junction generated a higher power efficiency than that with the ohmic contact. Additionally, they exhibited self-rectified behaviors. This was ascribed to the diffusion of charges, which resulted in the formation of a depletion layer across the Schottky or pn junction. When ferroelectric polyvinylidene fluoride (PVDF) was used to transfer MoS2, the power efficiency of the TENGs with the Schottky contact or pn junction was further enhanced by the synergistic effect of the depletion layer and the ferroelectric PVDF.