A Shape‐Adaptive Thin‐Film‐Based Approach for 50% High‐Efficiency Energy Generation Through Micro‐Grating Sliding Electrification

Effectively harvesting ambient mechanical energy is the key for realizing self‐powered and autonomous electronics, which addresses limitations of batteries and thus has tremendous applications in sensor networks, wireless devices, and wearable/implantable electronics, etc. Here, a thin‐film‐based micro‐grating triboelectric nanogenerator (MG‐TENG) is developed for high‐efficiency power generation through conversion of mechanical energy. The shape‐adaptive MG‐TENG relies on sliding electrification between complementary micro‐sized arrays of linear grating, which offers a unique and straightforward solution in harnessing energy from relative sliding motion between surfaces. Operating at a sliding velocity of 10 m/s, a MG‐TENG of 60 cm² in overall area, 0.2 cm³ in volume and 0.6 g in weight can deliver an average output power of 3 W (power density of 50 mW cm^?2 and 15 W cm^?3) at an overall conversion efficiency of ～50%, making it a sufficient power supply to regular electronics, such as light bulbs. The scalable and cost‐effective MG‐TENG is practically applicable in not only harvesting various mechanical motions but also possibly power generation at a large scale.     

Charge storage coating based triboelectric nanogenerator and its applications in self-powered anticorrosion and antifouling

As a novel energy-harvesting device, a triboelectric nanogenerator (TENG) can harvest almost all mechanical energy and transform it into electrical energy, but its output is low. Although the micro-nano structures of triboelectrode surfaces can improve their output efficiency, they lead to high costs and are not suitable for large-scale applications. To address this problem, we developed a novel TENG coating with charge-storage properties. In this study, we modified an acrylic resin, a friction material, with nano-BaTiO₃ particles and gas phase fluorination. The charge-trapping ability of nanoparticles was used to improve the output of TENG. The short-circuit current and the output voltage of coating-based TENGs featuring charge storage and electrification reached 15 μA and 800 V, respectively, without decay for longtime working. On this basis, self-powered anticorrosion and antifouling systems are designed to reduce the open circuit potential of A3 steel by 510 mV and reduce the adhesion rate of algae on the surface of metal materials. This study presents a high-output, stable, coating-based TENG with potential in practical applications for anticorrosion and antifouling.     

Inductor‐Free Wireless Energy Delivery via Maxwell's Displacement Current from an Electrodeless Triboelectric Nanogenerator

Wireless power delivery has been a dream technology for applications in medical science, security, radio frequency identification (RFID), and the internet of things, and is usually based on induction coils and/or antenna. Here, a new approach is demonstrated for wireless power delivery by using the Maxwell's displacement current generated by an electrodeless triboelectric nanogenerator (TENG) that directly harvests ambient mechanical energy. A rotary electrodeless TENG is fabricated using the contact and sliding mode with a segmented structure. Due to the leakage of electric field between the segments during relative rotation, the generated Maxwell's displacement current in free space is collected by metal collectors. At a gap distance of 3 cm, the output wireless current density and voltage can reach 7 µA cm⁻² and 65 V, respectively. A larger rotary electrodeless TENG and flexible wearable electrodeless TENG are demonstrated to power light‐emitting diodes (LEDs) through wireless energy delivery. This innovative discovery opens a new avenue for noncontact, wireless energy transmission for applications in portable and wearable electronics.     

Large‐Area Direct Laser‐Shock Imprinting of a 3D Biomimic Hierarchical Metal Surface for Triboelectric Nanogenerators

Ongoing efforts in triboelectric nanogenerators (TENGs) focus on enhancing power generation, but obstacles concerning the economical and cost‐effective production of TENGs continue to prevail. Micro‐/nanostructure engineering of polymer surfaces has been dominantly utilized for boosting the contact triboelectrification, with deposited metal electrodes for collecting the scavenged energy. Nevertheless, this state‐of‐the‐art approach is limited by the vague potential for producing 3D hierarchical surface structures with conformable coverage of high‐quality metal. Laser‐shock imprinting (LSI) is emerging as a potentially scalable approach for directly surface patterning of a wide range of metals with 3D nanoscale structures by design, benefiting from the ultrahigh‐strain‐rate forming process. Here, a TENG device is demonstrated with LSI‐processed biomimetic hierarchically structured metal electrodes for efficient harvesting of water‐drop energy in the environment. Mimicking and transferring hierarchical microstructures from natural templates, such as leaves, into these water‐TENG devices is effective regarding repelling water drops from the device surface, since surface hydrophobicity from these biomicrostructures maximizes the TENG output. Among various leaves' microstructures, hierarchical microstructures from dried bamboo leaves are preferable regarding maximizing power output, which is attributed to their unique structures, containing both dense nanostructures and microscale features, compared with other types of leaves. Also, the triboelectric output is significantly improved by closely mimicking the hydrophobic nature of the leaves in the LSI‐processed metal surface after functionalizing it with low‐surface‐energy self‐assembled‐monolayers. The approach opens doors to new manufacturable TENG technologies for economically feasible and ecologically friendly production of functional devices with directly patterned 3D biomimic metallic surfaces in energy, electronics, and sensor applications.     

Flexible Triboelectric Nanogenerator Based on High Surface Area TiO2 Nanotube Arrays

Triboelectric nanogenerators (TENGs) can harvest mechanical energy through coupling triboelectric effect and electrostatic induction. Typically, TENGs consist of organic materials, however on account of the potentially wide range of applications of TENGs as the self‐powered portable/wearable electronics, biomedical devices, and sensors; semiconductor metal oxide materials can be promising candidates to be incorporating in TENG structure. Here, flexible TENG based on self‐organized TiO₂ nanotube arrays (TNTAs) is fabricated via anodization method. The introduced flexible large area nanotubular electrode is employed as the moving electrode in contact with Kapton film in vertical contact separation mode of TENG. The fabricated TENG can deliver output voltage of 40 V with the current density of 1 μA cm^?2. To evaluate the role of nanostructured interface, its performance has been compared to the thin film flat compact TiO₂ electrode. The results of extracted charge measurements under short circuit condition indicate that larger triboelectric charge density formed in TNTA‐based electrode (about 110 nC per cycle of press and release) is in comparison to 15 nC in flat TiO₂ electrode. Due to the extensive range of applications of TiO₂, the introduced structure can potentially be applicable in various types of self‐powered systems such as photo‐detectors and environmental gas and bio‐sensors.

     

Fully Bioabsorbable Natural‐Materials‐Based Triboelectric Nanogenerators

Implantable medical devices provide an effective therapeutic approach for neurological and cardiovascular diseases. With the development of transient electronics, a new power source with biocompatibility, controllability, and bioabsorbability becomes an urgent demand for medical sciences. Here, various fully bioabsorbable natural‐materials‐based triboelectric nanogenerators (BN‐TENGs), in vivo, are developed. The “triboelectric series” of five natural materials is first ranked, it provides a basic knowledge for materials selection and device design of the TENGs and other energy harvesters. Various triboelectric outputs of these natural materials are achieved by a single material and their pairwise combinations. The maximum voltage, current, and power density reach up to 55 V, 0.6 µA, and 21.6 mW m^?2, respectively. The modification of silk fibroin encapsulation film makes the operation time of the BN‐TENG tunable from days to weeks. After completing its function, the BN‐TENG can be fully degraded and resorbed in Sprague–Dawley rats, which avoids a second operation and other side effects. Using the proposed BN‐TENG as a voltage source, the beating rates of dysfunctional cardiomyocyte clusters are accelerated and the consistency of cell contraction is improved. This provides a new and valid solution to treat some heart diseases such as bradycardia and arrhythmia.     

基于无机填料复合薄膜的摩擦纳米发电机研究进展

摩擦纳米发电机(Triboelectric Nanogenerator,TENG)是一种将微小机械能转化为电能并加以收集利用的绿色能源器件,具有活性材料种类广泛、器件结构简单以及易于集成等特点.较低的输出功率密度是目前阻碍其实际应用的主要因素之一.如何通过材料组分设计与制备提高其输出功率密度及能量转化效率,是目前该领域...     

非接触式摩擦纳米发电机的最新研究进展

目的 随着科学技术的快速发展，人们对可持续能源的需求不断增加。摩擦纳米发电机(TENG)利用各类微弱机械能实现自供电，有利于缓解这一需求。非接触式摩擦纳米发电机(NC?TENG)可以提高稳定性和使用寿命。总结NC?TENG的最新研究进展，为NC?TENG的结构设计、性能优化提供有益参考。方法 根据NC?TENG的器件结构与输出性能优化方法，介绍不同NC?TENG及其性能，重点综述其在智能包装领域的应用，并对未来的性能优化和应用工作进行展望。结果 基于不同的组装结构，通过介电常数调制、添加电荷捕获中间层等性能优化方案可以有效地避免静电放电问题，提高NC?TENG的电荷保留率。结论 NC?TENG相较于TENG，有着更高的稳定性和更长的使用寿命，在应对能源危机和推动新兴电子产品方面显示出巨大的潜力，预计在智能包装领域有着广泛的应用前景。     

Liquid-FEP-based U-tube triboelectric nanogenerator for harvesting water-wave energy

Harvesting ambient mechanical energy is a key technology for realizing self-powered electronics. With advantages of stability and durability, a liquid–solid-based triboelectric nanogenerator (TENG) has recently drawn much attention. However, the impacts of liquid properties on the TENG performance and the related working principle are still unclear. We assembled herein a U-tube TENG based on the liquid–solid mode and applied 11 liquids to study the effects of liquid properties on the TENG output performance. The results confirmed that the key factors influencing the output are polarity, dielectric constant, and affinity to fluorinated ethylene propylene (FEP). Among the 11 liquids, the pure water-based U-tube TENG exhibited the best output with an open-circuit voltage (V_oc) of 81.7 V and a short-circuit current (I_sc) of 0.26 μA for the shaking mode (0.5 Hz), which can further increase to 93.0 V and 0.48 μA, respectively, for the horizontal shifting mode (1.25 Hz). The U-tube TENG can be utilized as a self-powered concentration sensor (component concentration or metalion concentration) for an aqueous solution with an accuracy higher than 92%. Finally, an upgraded sandwich-like water-FEP U-tube TENG was applied to harvest water-wave energy, showing a high output with V_oc of 350 V, I_sc of 1.75 μA, and power density of 2.04 W/m³. We successfully lighted up 60 LEDs and powered a temperature–humidity meter. Given its high output performance, the water-FEP U-tube TENG is a very promising approach for harvesting water-wave energy for self-powered electronics.

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Theory of Sliding‐Mode Triboelectric Nanogenerators

The triboelectric nanogenerator (TENG) is a powerful approach toward new energy technology, especially for portable electronics. A theoretical model for the sliding‐mode TENG is presented in this work. The finite element method was utilized to characterize the distributions of electric potential, electric field, and charges on the metal electrodes of the TENG. Based on the FEM calculation, the semi‐analytical results from the interpolation method and the analytical V‐Q‐x relationship are built to study the sliding‐mode TENG. The analytical V‐Q‐x equation is validated through comparison with the semi‐analytical results. Furthermore, based on the analytical V‐Q‐x equation, dynamic output performance of sliding‐mode TENG is calculated with arbitrary load resistance, and good agreement with experimental data is achieved. The theory presented here is a milestone work for in‐depth understanding of the working mechanism of the sliding‐mode TENG, and provides a theoretical basis for further enhancement of the sliding‐mode TENG for both energy scavenging and self‐powered sensor applications.     

Highly Transparent,Stretchable, and Self‐Healing Ionic‐Skin Triboelectric Nanogenerators for Energy Harvesting and Touch Applications

Recently developed triboelectric nanogenerators (TENGs) act as a promising power source for self‐powered electronic devices. However, the majority of TENGs are fabricated using metallic electrodes and cannot achieve high stretchability and transparency, simultaneously. Here, slime‐based ionic conductors are used as transparent current‐collecting layers of TENG, thus significantly enhancing their energy generation, stretchability, transparency, and instilling self‐healing characteristics. This is the first demonstration of using an ionic conductor as the current collector in a mechanical energy harvester. The resulting ionic‐skin TENG (IS‐TENG) has a transparency of 92% transmittance, and its energy‐harvesting performance is 12 times higher than that of the silver‐based electronic current collectors. In addition, they are capable of enduring a uniaxial strain up to 700%, giving the highest performance compared to all other transparent and stretchable mechanical‐energy harvesters. Additionally, this is the first demonstration of an autonomously self‐healing TENG that can recover its performance even after 300 times of complete bifurcation. The IS‐TENG represents the first prototype of a highly deformable and transparent power source that is able to autonomously self‐heal quickly and repeatedly at room temperature, and thus can be used as a power supply for digital watches, touch sensors, artificial intelligence, and biointegrated electronics.     

A Small‐Molecule “Charge Driver” enables Perovskite Quantum Dot Solar Cells with Efficiency Approaching 13%

Halide perovskite colloidal quantum dots (CQDs) have recently emerged as a promising candidate for CQD photovoltaics due to their superior optoelectronic properties to conventional chalcogenides CQDs. However, the low charge separation efficiency due to quantum confinement still remains a critical obstacle toward higher‐performance perovskite CQD photovoltaics. Available strategies employed in the conventional CQD devices to enhance the carrier separation, such as the design of type‐Ⅱ core–shell structure and versatile surface modification to tune the electronic properties, are still not applicable to the perovskite CQD system owing to the difficulty in modulating surface ligands and structural integrity. Herein, a facile strategy that takes advantage of conjugated small molecules that provide an additional driving force for effective charge separation in perovskite CQD solar cells is developed. The resulting perovskite CQD solar cell shows a power conversion efficiency approaching 13% with an open‐circuit voltage of 1.10 V, short‐circuit current density of 15.4 mA cm^?2, and fill factor of 74.8%, demonstrating the strong potential of this strategy toward achieving high‐performance perovskite CQD solar cells.     

On‐Skin Triboelectric Nanogenerator and Self‐Powered Sensor with Ultrathin Thickness and High Stretchability

Researchers have devoted a lot of efforts on pursuing light weight and high flexibility for the wearable electronics, which also requires the related energy harvesting devices to have ultrathin thickness and high stretchability. Hence, an elastic triboelectric nanogenerator (TENG) is proposed that can serve as the second skin on human body. The total thickness of this TENG is about 102 µm and the device can work durably under a strain of 100%. The carbon grease is painted on the surface of elastomer film to work as stretchable electrode and thus the fine geometry control of the electrode can be achieved. This elastic TENG can even work on the human fingers without disturbing body movement. The open‐circuit voltage and short‐circuit current from the device with a contact area of 9 cm² can reach 115 V and 3 µA, respectively. Two kinds of self‐powered sensor systems with optimized identification strategies are also designed to demonstrate the application possibility of this elastic TENG. The superior characteristics of ultrathin thickness, high stretchability, and fine geometry control of this TENG can promote many potential applications in the field of wearable self‐powered sensory system, electronics skin, artificial muscles, and soft robotics.     

Single‐Mode Lasing from Colloidal Water‐Soluble CdSe/CdS Quantum Dot‐in‐Rods

Core–shell CdSe/CdS nanocrystals are a very promising material for light emitting applications. Their solution‐phase synthesis is based on surface‐stabilizing ligands that make them soluble in organic solvents, like toluene or chloroform. However, solubility of these materials in water provides many advantages, such as additional process routes and easier handling. So far, solubilization of CdSe/CdS nanocrystals in water that avoids detrimental effects on the luminescent properties poses a major challenge. This work demonstrates how core–shell CdSe/CdS quantum dot‐in‐rods can be transferred into water using a ligand exchange method employing mercaptopropionic acid (MPA). Key to maintaining the light‐emitting properties is an enlarged CdS rod diameter, which prevents potential surface defects formed during the ligand exchange from affecting the photophysics of the dot‐in‐rods. Films made from water‐soluble dot‐in‐rods show amplified spontaneous emission (ASE) with a similar threshold (130 μJ/cm²) as the pristine material (115 μJ/cm²). To demonstrate feasibility for lasing applications, self‐assembled microlasers are fabricated via the “coffee‐ring effect” that display single‐mode operation and a very low threshold of ～10 μJ/cm². The performance of these microlasers is enhanced by the small size of MPA ligands, enabling a high packing density of the dot‐in‐rods.     

A New Route to Low Resistance Contacts for Performance‐Enhanced Organic Electronic Devices

The barrier to charge carrier injection across the semiconductor/electrode interface is a key parameter in the performance of organic transistors and optoelectronic devices, and the work function of the electrode material plays an important role in determining the size of this barrier. We present a new, chemical route for making metal surfaces with low work functions, by functionalizing gold surfaces with self‐assembled monolayers of n,n‐dialkyl dithiocarbamates. Ultraviolet photoemission spectroscopy measurements show that work functions of 3.2 eV ± 0.1 eV can be achieved using this surface modification. Electronic structure calculations reveal that this low work function is a result of the packing‐density, polarization along the N‐C bond, and charge rearrangement associated with chemisorption. We demonstrate that electrodes functionalized with these monolayers significantly improve the performance of organic thin‐film transistors and can potentially be employed in charge selective contacts for organic photovoltaics.     

Fully enclosed hybrid electromagnetic–triboelectric nanogenerator to scavenge vibrational energy

We propose a fully enclosed hybrid nanogenerator consisting of five electromagnetic generators (EMGs) and four triboelectric nanogenerators (TENGs).Under a vibration frequency of 15.5 Hz,one TENG can deliver a high output voltage of approximately 24 V and a low output current of approximately 24 μA,whereas one EMG can deliver a low output voltage of approximately 0.8 V and a high output current of approximately 0.5 mA.By integrating five rectified EMGs in series and four rectified TENGs in parallel,the hybrid nanogenerator can be used to charge a home-made Li-ion battery from 1 to 1.9 V in 6.3 h.By using the hybrid nanogenerator to scavenge the vibrational energy produced by human hands,a temperature-humidity sensor can be sustainably powered by the nanogenerator,which is capable of charging the 200 μF system power capacitor from 0 to 2 V in 15 s,and sustainably power the sensor in 29 s.     

Surface Triboelectrification of MXenes with Fluorine Groups for Flexible Energy Harvesting and Sensing

Triboelectric nanogenerator (TENG) has attracted attention for flexible electronics in the past decade. MXene is gradually applied in TENGs for performance enhancement, but the surface triboelectrification mechanism still needs to be further investigated experimentally. Herein, an experimental approach of regulating MXene fluorine groups by alkalization as a contrast to validate the mechanism is proposed. The MXene film and alkalized MXene film are studied to exploit the surface state. Compared with alkalized MXene-based TENGs, MXene-based TENG obtains enhancement in open-circuit voltage, short-circuit current, and output power by 4.1 times, 4.6 times, and even 136.6 times, respectively. The excellent performance enables flexible sensing and energy harvesting. Notably, this work reveals MXene surface triboelectrification mechanism and might motivate a new approach for TENG performance enhancement.     

The Pine‐Needle‐Inspired Structure of Zinc Oxide Nanorods Grown on Electrospun Nanofibers for High‐Performance Flexible Supercapacitors

Flexible supercapacitors with high electrochemical performance and stability along with mechanical robustness have gained immense attraction due to the substantial advancements and rampant requirements of storage devices. To meet the exponentially growing demand of microsized energy storage device, a cost‐effective and durable supercapacitor is mandatory to realize their practical applications. Here, in this work, the fabrication route of novel electrode materials with high flexibility and charge‐storage capability is reported using the hybrid structure of 1D zinc oxide (ZnO) nanorods and conductive polyvinylidene fluoride‐tetrafluoroethylene (P(VDF‐TrFE)) electrospun nanofibers. The ZnO nanorods are conformably grown on conductive P(VDF‐TrFE) nanofibers to fabricate the light‐weighted porous electrodes for supercapacitors. The conductive nanofibers acts as a high surface area scaffold with significant electrochemical performance, while the addition of ZnO nanorods further enhances the specific capacitance by 59%. The symmetric cell with the fabricated electrodes presents high areal capacitance of 1.22 mF cm^?2 at a current density of 0.1 mA cm^?2 with a power density of more than 1600 W kg^?1. Furthermore, these electrodes show outstanding flexibility and high stability with 96% and 78% retention in specific capacitance after 1000 and 5000 cycles, respectively. The notable mechanical durability and robustness of the cell acquire both good flexibility and high performance.     

Advanced designs for output improvement of triboelectric nanogenerator system

The large-scale popularization of 5G mobile network technology accelerates the arrival of modern intelligent society. In this society, billions of distributed sensors are needed as the sense organ for information collection, posing a grand challenge of high precision sensor and distributed power supply. As an emerging technology, triboelectric nanogenerator (TENG) can effectively harvest varied environmental low frequency mechanical energy and convert it into electricity with the merits of low cost, environmentally friendliness and strong adaptability, showing a great potential as a distributed power source. However, there is still a distance for its commercial use due to the insufficient function modes and output performance of TENG. Therefore, in order to push forward its commercial process, here we systematically review TENG, from the basic characteristics, improving output performance of alternating current (AC) TENG, working modes of direct current (DC) TENG to effective power management. Besides, we suggest some unified and standardized terminologies on energy efficiency to solve some confusing nomenclature. At last, challenges and future research focus in this field are also predicted to provide a significant guideline for the next stage development of TENG for the research community.