High-k water intermediate layer-mediated charge transfer modulation toward stable and augmented output generation of droplet-based electricity generators.

Droplet-based electricity generators (DEGs), which share structural analogies with field-effect transistors (FETs), have garnered increasing attention for droplet energy harvesting. DEGs typically exhibit sharp output peaks with short charge transfer durations, which need to be extended to enhance the root mean square (RMS) output for practical use in energy harvesting. To address this limitation, this study introduces a methodology for spontaneously forming a high-k water intermediate (WIn) layer by capturing working droplets, inspired by strategies for FET. Based on the operation mechanism of the DEG, this strategy yields both an increase in the amount of transferred charge and an extension in charge transfer duration, thereby augmenting current output. To further demonstrate its significance, RMS output enhancement is validated under conditions with similar peak output levels but an augmented charge transfer process, highlighting its practical advantage. In addition, the extended charge transfer duration enables sporadic peak overlapping, potentially resulting in a direct current (DC)-like output generation. This behavior contributes to RMS output enhancement, thereby improving the energy harvesting capacity. This study underscores the importance of the charge transfer process augmentation via the spontaneously generated high-k WIn layer, paving the way for the practical implementation of DEGs.