Fabrication and characterization of low-cost flexible triboelectric nanogenerators for efficient and sustainable ambient energy harvesting

Wearable and durable triboelectric nanogenerators via polyaniline coated cotton textiles as a movement sensor and self-powered system

3D printed flexible triboelectric nanogenerator with viscoelastic inks for mechanical energy harvesting

Ionic liquid-based molecular design for transparent, flexible, and fire-retardant triboelectric nanogenerator (TENG) for wearable energy solutions

Flexible triboelectric nanogenerators (TENGs) have attracted much attention because of its environmentally friendly, practical, and cost-producing advantages. In flexible TENGs, it is important to study the flexible electrodes in order to fabricate the fully flexible devices. Here, we compared electrical characteristics of the sponge porous polydimethylsiloxane (PDMS)-based flexible TENGs with two types of flexible electrodes, copper and carbon nanotube (CNT)-PDMS electrodes. The output voltage and maximum power density of sponge PDMS-based flexible TENGs with copper and CNTPDMS electrodes were compared. The voltage and power density of sponge PDMS-based flexible TENGs with CNT-PDMS electrodes were improved compare to those with copper electrodes. The output voltage and the maximum power density of sponge PDMS-based flexible TENGs with copper and CNT-PDMS electrodes increased 4 times and 7 times, respectively. It is attributed to higher electrical conductivity and stably flow electricity of CNT than those of copper.

Flexible carbon cloth-based single-electrode triboelectric nanogenerators with incorporated TiO[formula omitted] nanoparticles

Manipulation of the surface properties of the triboelectric layer has been proven to be one of the key parameters to achieve high-performance and stable triboelectric nanogenerators (TENG). Herein, a pragmatic surface engineering strategy that can substantially boost the performance and stability of flexible TENG is elaborated by incorporating the zwitterionic molecule dimethylethylammoniumpropane sulfonate (NDSB) as the surface modification layer. Given that zwitterionic molecules tend to form aggregated structures, realizing ordered arrangement on the substrate surface remains challenging to date. To address this issue, in this work, a combination of multiple surface treatments and molecular manipulation strategy is proposed. Our results prove that NDSB is effective in modifying the surface properties of the dielectric layer and electrode layer, leading to a remarkable power density and specific power of 2.86 W m-2 and 20.73 mW g-1 for flexible TENG, respectively. In addition, due to the strong interaction between the NDSB/dielectric and NDSB/electrode, a water-resistant long-term stable flexible TENG is realized. More encouragingly, our strategy is compatible with a cost-effective dip-coating technique, and an unprecedented demonstration of batch fabrication of TENG using NDSB to functionalize the surface of the dielectric layer and electrode layer synchronously can be realized, which is advantageous for rapid and up-scalable manufacturing of TENG. We also prove that the TENG based on zwitterionic materials reveals exceptional antibacterial properties against Escherichia coli. This study represents an important step towards the development of long-term stable flexible TENG that possesses a high output performance and excellent antibacterial activity based on a facile and economical strategy, enabling TENG technology to show bright prospects in a wide variety of application domains.

Flexible nanogenerators that efficiently convert mechanical energy into electrical energy have been extensively studied because of their great potential for driving low-power personal electronics and self-powered sensors. Integration of flexibility and stretchability to nanogenerator has important research significance that enables applications in flexible/stretchable electronics, organic optoelectronics, and wearable electronics. Progress in nanogenerators for mechanical energy harvesting is reviewed, mainly including two key technologies: flexible piezoelectric nanogenerators (PENGs) and flexible triboelectric nanogenerators (TENGs). By means of material classification, various approaches of PENGs based on ZnO nanowires, lead zirconate titanate (PZT), poly(vinylidene fluoride) (PVDF), 2D materials, and composite materials are introduced. For flexible TENG, its structural designs and factors determining its output performance are discussed, as well as its integration, fabrication and applications. The latest representative achievements regarding the hybrid nanogenerator are also summarized. Finally, some perspectives and challenges in this field are discussed.

With the advent of the smart era, the demand for clean energy is rising, and flexible triboelectric nanogenerators (F-TENGs) based on elastomers have garnered significant attention. Based on the principles of electrostatic induction and coupling, F-TENGs can convert mechanical motion into electrical energy and are widely utilized in wearable devices and blue energy. F-TENGs offer a simple design, ease of manufacturing, and flexible usage scenarios. However, several weaknesses still limit their development. For example, F-TENG materials cannot recover from fatigue damage and are prone to output performance degradation under frequent friction or complex external conditions, leading to failure. To address these issues, researchers have explored the use of self-healable flexible polymer-based friction layers and electrodes. This review will provide a detailed summary of the key scientific and technological challenges faced by F-TENGs in complex and harsh environments, including ambient, high and low temperatures, high humidity, and strong acids and bases. Furthermore, the detailed research progress addressing these issues and the future development of F-TENGs will also be presented and explored. This paper aims to provide valuable insights and guidance for in-depth research and broad applications of flexible TENGs.

Flexible triboelectric nanogenerators (TENGs) have attracted increasing interest since their advent in 2012. In comparison with other flexible electrodes, hydrogels possess transparency, stretchability, biocompatibility, and tunable ionic conductivity, which together provide great potential as current collectors in TENGs for wearable applications. The development of hydrogel‐based TENGs (H‐TENGs) is currently a burgeoning field but research efforts have lagged behind those of other common flexible TENGs. In order to spur research and development of this important area, a comprehensive review that summarizes recent advances and challenges of H‐TENGs will be very useful to researchers and engineers in this emerging field. Herein, the advantages and types of hydrogels as soft ionic conductors in TENGs are presented, followed by detailed descriptions of the advanced functions, enhanced output performance, as well as flexible and wearable applications of H‐TENGs. Finally, the challenges and prospects of H‐TENGs are discussed.

In this work, a flexible triboelectric nanogenerator (TENG) consisting of a flexible printed circuit and microcavity surface polydimethylsiloxane (PDMS) for harvesting power was proposed and studied. The electric power generated from the TENG is based on the triboelectric effect and electrostatic induction. The cavity surface demolded from the sandpaper was employed for improving the TENG performance. The TENG could be operated in the vertical contact mode and bending contact mode. In order to estimate the performance in the different motion modes, two measurement setups were designed for measuring the TENG output power. According to the measurement results, higher cavity density has better output performance. The maximum output power of 1.77 μW with the 6.55 MΩ loading resistance for the vertical contact mode and the maximum output power 0.38 μW with the 6.95 MΩ loading resistance for the bending contact was achieved, respectively.

The flexible triboelectric nanogenerator (TENG) has promising applications in portable electronic devices and micro wireless sensors. However, complex fabrication processes, high cost, and difficulty in coupling with the human body are still the challenges for the further development of TENG. Herein, a flexible double‐sided patterned titanium nitride/polydimethylsiloxane (DSP‐TiN/PDMS) composite film is prepared by a simple and low‐cost sandpaper template method. The double‐sided microporous structure on the PDMS increases the effective contact area and promotes more charge storage on the PDMS surface, thus improving the output performance of TENG. With the introduction of conductive TiN nanoparticles, the effective thickness of the composite film can be reduced, leading to the increase of the capacitance value of TENG. Therefore, the TENG fabricated under the conditions of optimized filling content and surface patterning microstructure can generate a high open‐circuit voltage of 51.8 V and a short‐circuit current of 36.8 μA, as well as a peak power of 11.25 μW. Furthermore, the proposed TENG can also achieve effective energy harvesting in human motions. This easy‐to‐prepare DSP‐TiN/PDMS composite film opens up a feasible way for the construction of high output performance TENG and presents promising applications in micro wearable devices.

A flexible triboelectric nanogenerator (TENG) is an indispensable part in future flexible self‐powered system. However, it is still a great challenge to establish a balance among the robust mechanical property, strong triboelectrification effect, and high conductivity of electrode materials. A flexible and enhanced‐performance TENG based on cellulose nanofibrils (CNFs)/transition metal carbides and nitrides (MXene) composite films is developed here for harvesting human movement energy. By introducing CNFs, the mechanical strength, flexibility of the composite film, and sensitive to the temperature change and strain are improved. The effect of CNFs concentration, working force, and frequency on the output performance of TENG is also demonstrated. At the optimized CNFs/MXene ratio of 2/5, the transferred charges and output voltage reach the maximum value of 7.4 nC and 24.9 V, respectively. The maximum instantaneous output power density of the as‐prepared TENG is 1.2 mW m−2. Moreover, a self‐powered flexible display system is demonstrated by integrating the TENG with a flexible alternating current electroluminescence. The flexible TENG based on cellulose nanofibrils‐reinforced MXene composite film is promising as a flexible energy source for self‐powered system.

Highly transparent and flexible triboelectric nanogenerators (TENGs) were fabricated using the subwavelength-architectured (SWA) polydimethylsiloxane (PDMS) with a nanoporous anodic aluminum oxide (AAO) template as a replica mold. The SWA PDMS could be utilized as a multifunctional film for a triboelectric layer, an antireflection coating, and a self-cleaning surface. The nanopore arrays of AAO were formed by a simple, fast, and cost-effective electrochemical oxidation process of aluminum, which is relatively impressive for fabrication of the TENG device. For electrical contacts, the SWA PDMS was laminated on the indium tin oxide (ITO)-coated polyethylene terephthalate (PET) as a bottom electrode, and the bare ITO-coated PET (i.e., ITO/PET) was used for the top electrode. Compared to the ITO/PET, the SWA PDMS on the ITO/PET improved the transmittance from 80.5 to 83% in the visible wavelength region and also had high transmittances of >85% at wavelengths of 430-455 nm. The SWA PDMS also exhibited the hydrophobic surface with a water contact angle (θCA) of ∼115°, which can be useful for self-cleaning applications. The average transmittance (Tavg) of the entire TENG device was observed to be ∼70% over a broad wavelength range. At an external pushing frequency of 0.5 Hz, for the TENG device with the ITO top electrode, open-circuit voltage (VOC) and short-circuit current (ISC) values of ∼3.8 V and ∼0.8 μA were obtained instantaneously, respectively, which were higher than those (i.e., VOC ≈ 2.2 V, and ISC ≈ 0.4 μA) of the TENG device with a gold top electrode. The effect of external pushing force and frequency on the output device performance of the TENGs was investigated, including the device robustness. A theoretical optical analysis of SWA PDMS was also performed.

Facile synthesis of sub-10 nm ZnS/ZnO nanoflakes for high-performance flexible triboelectric nanogenerators

Transparent and flexible touch on/off switch based on BaTiO3/silicone polymer triboelectric nanogenerator