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.