Output power density enhancement of an intermittently contacted metal–semiconductor junction with a water interlayer

Abstract

It has been reported that an intermittently contacted metal–semiconductor junction could harvest vibration energy. However, how to increase the energy conversion efficiency is still challenging. Herein, we find that the output power density of an intermittently contacted gold–silicon (Au–Si) junction can be increased by about 3 orders of magnitude after introduction of a water (H₂O) interlayer between the Au and Si friction layers. Our results demonstrate that the electric double layer and built-in electric field in the Au–H₂O–Si junction induce large values of output current and transferred charges and thereby contribute a high output power. Through studies of the output electric characteristics of the intermittently contacted Au–H₂O–Si junctions with different wettabilities of the Si surfaces, we reveal that the hydrophobic Si surface has the best energy conversion efficiency due to the continual contact electrification at the dynamic H₂O–Si interface.