A constant-current generator via water droplets driving Schottky diodes without a rectifying circuit

Abstract

A Schottky contact is formed through the creation of an energy barrier, which enhances the built-in electric field and realizes rectification, detection and energy storage. As a device that utilizes Schottky contacts, a Schottky metal–semiconductor–metal (MSM) exhibits attractive transport behaviors. However, the regulation of an MSM by micro-stimuli in nature is rarely investigated and the application is limited to the field of optoelectronics. Here, we present a Schottky MSM system that can generate up to 400 μA direct current under single water droplet excitation. This ultra-high output results from the redistribution of charges in the MSM system, which applies a bias voltage on the Schottky barrier by the triboelectric potential, thus controlling the built-in electric field and promoting carrier transport. We further demonstrate that a Schottky diode array based on the MSM structure can generate a constant current via multiple water droplet excitation without an additional rectifying circuit, thus improving the energy conversion efficiency greatly. The regulation mechanism of the MSM structure presented in this work will promote the broad applications of MSM structures towards passive networks, such as energy harvesters, droplet logic circuits and fluid monitoring.