Self-Powered Smart Textile Based on Dynamic Schottky Diode for Human-Machine Interactions

Ferroelectric Polarization Electric Field Induced High Performance Graphene/LiNbO3 Dynamic Diode Generator

Substantial endeavors have been dedicated to continuously harvesting mechanical energy from the environment, where dynamic semiconductor diode generators (DDGs) have recently been drawing significant attention as the miniature, portable in situ energy device. However, despite their unique advantages of direct-current output and high current density, the output voltage of DDG is usually less than 1 V, which needs to be further improved to satisfy the demands of practical applications. Therefore, this study proposes a vertical graphene/LiNbO3 DDG that is conducive to an ultra-high voltage output. The coupling enhancement effect arising from the synergy between the ferroelectric polarization electric field on the LiNbO3 surface and the built-in electric field at the graphene/LiNbO3 interface has been identified as a key factor in achieving an impressively high open-circuit voltage output of 41.3 V and a short-circuit current of 1.53 µA. The vertical graphene/LiNbO3 DDG can effectively power an LED without the requirement of an external energy storage and conversion circuit. Moreover, it demonstrates outstanding stability, showing no evident performance attenuation after continuous operation exceeding 3 h. The graphene/LiNbO3 DDG has enhanced the feasibility of real-time energy supply for electronic components and paved the way for the efficient harvesting of mechanical energy from the environment.

Advanced Interface Design of Direct-Current Tribovoltaic Nanogenerator

Tribovoltaic nanogenerator (TVNG), which manifests distinct advantages of direct-current output characteristics and remarkable energy utilization efficiency, is an emerging energy technology relying on the coupling of semiconductor and contact electrification. Dynamic semiconductor interface is the key to TVNGs, as its performance and functionality largely depend on the design and optimization of interface. Hence, with the booming development of TVNGs, it is of great significance to timely update the fundamental understanding of its interface design, which is currently lacking. In this review, the frontier advances on interface design for TVNGs are elaborately outlined for the first time. First, the underlying mechanisms of tribovoltaic effect at the interface are elaborated, as well as some governing equations and key interface design concepts. Subsequently, diverse strategies for advanced interface design are highlighted, including modulating interfacial charge dynamics, multi-energy coupling, reducing interface wear loss, and extending flexible/wearable application. At last, some assumptions about the future direction and prospects of advanced interface design in efficient, multifunctional TVNGs are presented.

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

Tribovoltaic effect is a phenomenon of the generation of direct voltage and current by the mechanical friction on semiconductor interface, which exhibits a brand-new energy conversion mechanism by the coupling of semiconductor and triboelectrification. Here, the origin, interfaces, characteristics, mechanism, coupling effect and application of the tribovoltaic effect is summarized and reviewed. The tribovoltaic effect is first proposed in 2019, which has developed in various forms tribovoltaic nanogenerator (TVNG) including metal-semiconductor, metal-insulator-semiconductor, semiconductor-semiconductor, liquid-solid and flexible interfaces. Compared with triboelectric nanogenerator, the TVNG has the characteristics of direct-current, high current density (mA-A cm-2) and low impedance (Ω-kΩ). The two mainstream views on the tribovoltaic generation mechanism, one dominated by built-in electric fields and the other dominated by interface electric fields, have been elaborated and summarized in detail. The tribo-photovoltaic effect and tribo-thermoelectric effect are also discovered and introduced because they can easily interact with other multi-physical field effects. The TVNGs are suitable for making energy harvesting and self-powered sensing devices for micro-nano energy applications. This paper not only revisit the development of the tribovoltaic effect, but also makes prospects for mechanism research, device fabrication and integrated application, which can accelerate the evolution of smart wearable electronics and intelligent industrial components.

Redesigning Natural Materials for Energy, Water, Environment, and Devices

The United Nations Framework Convention on Climate Change (UNFCCC) acknowledges that global cooperation is paramount to mitigate climate change and further warming. The global community is committed to renewable energy and natural materials to tackle this challenge for all humankind. The widespread use of natural materials is embraced as one such action to reach net-zero carbon emissions. Given the hierarchical framework and earth abundance, cellulose-based materials extend their negative carbon benefits to our daily products and accelerate our pace toward carbon neutrality. Here, we present an overview of recent developments of cellulose-based materials in upsurging applications in radiative cooling, thermal insulation, nanofluidics, and wearable devices. We also highlight various modifications and functionalized processes that transform massive amounts of cellulose into green products. The prosperous development of functionalized cellulose materials aligns with a circular economy. Expedited interdisciplinary fundamental investigations are expected to make fibrillated cellulose penetrate more into carbon downdraw at speed and scale.