Flexible Liquid‐Based Continuous Direct‐Current Tribovoltaic Generators Enable Self‐Powered Multi‐Modal Sensing

Abstract

Flexible tribovoltaic direct-current (DC) generators are urgently expected by wearable applications. Traditional rigid contact-separation type tribovoltaic DC generators normally have non-ignorable friction loss and cannot sustain outstanding outputs. This hinders their serviceability in continuous motion scenarios. Here, flexible liquid-based DC generators (FLGs) with metalliquid-semiconductor indium gallium zinc oxide (IGZO) stack structures are reported. The FLG with Pt/H 2 O/IGZO structure delivers a peak short-circuit current density up to 2.3 µA cm −2 , a peak open-circuit voltage up to 620 mV, and a power density up to 0.1 µW cm −2 . The differences in the properties of different liquid-solid interfaces are studied by density functional theory, showing that the bond formation, charge-transfer-induced dipole electric field at the solid-liquid interface, and the built-in electric field are responsible for the generation and separation of electron-hole pairs to form continuous DC. The proposed FLG can keep excellent performance even after >5 × 10 4 shaking cycles or exposing to ambient conditions for 30 days, showing extraordinary stability. Besides charging capacitors or driving LEDs, the FLG is further demonstrated to work for self-powered multifunctional sensing, enabling pressure, position-posture, or temperature detections. This design offers potential solutions and novel possibilities for next-generation self-powered wearable electronics.

Tribovoltaic Effect: Origin, Interface, Characteristic, Mechanism & Application

“…(Adapted from Huang et al. [ 85 ] with permission. Copyright 2022, WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim).…”

“…b) Powering the LED bulb with the carbon aerogel/Si TVNG. (Adapted from Huang et al[85] with permission. Copyright 2022, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).…”

Dynamic Perovskite Homojunction Based Light‐Assisted, Direct Current Tribovoltaic Nanogenerators

“…[22][23][24][25][26] As reported, such tribovoltaic nanogenerator (TVNG) can directly generate the continuous and stable DC output power through dynamic motions at the metal/semiconductor Schottky junction, P-N junction, or liquid/semiconductor interface, without any rectification strategies. [27][28][29] Inspired by this, Yang et al innovatively proposed a perovskite-based TVNG with Al/CsPbBr 3 Schottky junction, which demonstrated the feasibility of perovskite in generating high DC current density and further elaborated the interfacial tribo-photovoltaic effect. [30] Despite this effort, sufficient evidences indicate the redox reaction of Al and perovskite would occur at the contact interface and further induce the degradation of perovskite films.…”

A Review of Contact Electrification at Diversified Interfaces and Related Applications on Triboelectric Nanogenerator

“…Self-powered sensors are a universal application for CE at different interfaces. Self-powered sensors based on solid–solid interfaces can be used to monitor [ 153 ] a variety of human movements for signal transmission [ 154 ] and integrated with smart IoT devices [ 155 ], while those based on solid–liquid and solid–gas interfaces are more commonly used to monitor environmental conditions. In addition, TENG based on specialized interfaces offer an enhanced capability for precise sensing in specific conditions.…”