A mechanically tunable electromagnetic wave harvester and dual-modal detector based on quasi-static van der Waals heterojunction

Electromagnetic (EM) wave harvesting and detection have many implications for self-powered human health monitoring and robot intelligence. Heterojunction-based energy harvesters and detectors can convert various forms of energy into electricity. Here, we report a mechanically tunable electromagnetic wave harvester (EMH), operated by quasi-static contact of a metal/indium gallium zinc oxide/metal van der Waals heterojunction. The proposed EMH behaves as a rectenna responding to low-frequency signals (80–400 MHz), where the electrode works as an antenna, the heterojunction between two separated layers works as a rectifying diode, and the parallel structure works as a capacitor. It is found that the pressure on the EMH plays an important role on regulating electronic interfaces and thus the output characteristics. The two output states (on/off states) of the EMH can be reversibly controlled by mechanical pressure. The proposed design and mechanism have been verified by various materials pairings and structures, which proves their great universality. The simple-structure EMH can continuously generate DC power for 10 hours without signal attenuation. It can supply power to a capacitor, a LED and a resistive load inverter, which demonstrates its application potential as an energy source. Moreover, the EMH can work as a sensor to qualitatively detect electromagnetic waves in the ambient environment and pressure. This work has proposed a novel solution to harvest and detect electromagnetic energy by van der Waals heterojunction in a mechanically controllable way, providing new possibilities for wearable electronics, intelligent robots, and Internet of Things.