15 research outputs found
Harvesting Broadband Kinetic Impact Energy from Mechanical Triggering/Vibration and Water Waves
We invented a triboelectric nanogenerator (TENG) that is based on a wavy-structured Cu–Kapton–Cu film sandwiched between two flat nanostructured PTFE films for harvesting energy due to mechanical vibration/impacting/compressing using the triboelectrification effect. This structure design allows the TENG to be self-restorable after impact without the use of extra springs and converts direct impact into lateral sliding, which is proved to be a much more efficient friction mode for energy harvesting. The working mechanism has been elaborated using the capacitor model and finite-element simulation. Vibrational energy from 5 to 500 Hz has been harvested, and the generator’s resonance frequency was determined to be ∼100 Hz at a broad full width at half-maximum of over 100 Hz, producing an open-circuit voltage of up to 72 V, a short-circuit current of up to 32 μA, and a peak power density of 0.4 W/m<sup>2</sup>. Most importantly, the wavy structure of the TENG can be easily packaged for harvesting the impact energy from water waves, clearly establishing the principle for ocean wave energy harvesting. Considering the advantages of TENGs, such as cost-effectiveness, light weight, and easy scalability, this approach might open the possibility for obtaining green and sustainable energy from the ocean using nanostructured materials. Lastly, different ways of agitating water were studied to trigger the packaged TENG. By analyzing the output signals and their corresponding fast Fourier transform spectra, three ways of agitation were evidently distinguished from each other, demonstrating the potential of the TENG for hydrological analysis
Largely Enhanced Efficiency in ZnO Nanowire/p-Polymer Hybridized Inorganic/Organic Ultraviolet Light-Emitting Diode by Piezo-Phototronic Effect
ZnO nanowire inorganic/organic hybrid ultraviolet (UV)
light-emitting
diodes (LEDs) have attracted considerable attention as they not only
combine the high flexibility of polymers with the structural and chemical
stability of inorganic nanostructures but also have a higher light
extraction efficiency than thin film structures. However, up to date,
the external quantum efficiency of UV LED based on ZnO nanostructures
has been limited by a lack of efficient methods to achieve a balance
between electron contributed current and hole contributed current
that reduces the nonradiative recombination at interface. Here we
demonstrate that the piezo-phototronic effect can largely enhance
the efficiency of a hybridized inorganic/organic LED made of a ZnO
nanowire/p-polymer structure, by trimming the electron current to
match the hole current and increasing the localized hole density near
the interface through a carrier channel created by piezoelectric polarization
charges on the ZnO side. The external efficiency of the hybrid LED
was enhanced by at least a factor of 2 after applying a proper strain,
reaching 5.92%. This study offers a new concept for increasing organic
LED efficiency and has a great potential for a wide variety of high-performance
flexible optoelectronic devices
Piezotronic Effect in Solution-Grown p‑Type ZnO Nanowires and Films
Investigating the piezotronic effect
in p-type piezoelectric semiconductor
is critical for developing a complete piezotronic theory and designing/fabricating
novel piezotronic applications with more complex functionality. Using
a low temperature solution method, we were able to produce ultralong
(up to 60 μm in length) Sb doped p-type ZnO nanowires on both
rigid and flexible substrates. For the p-type nanowire field effect
transistor, the on/off ratio, threshold voltage, mobility, and carrier
concentration of 0.2% Sb-doped sample are found to be 10<sup>5</sup>, 2.1 V, 0.82 cm<sup>2</sup>·V<sup>–1</sup>·s<sup>–1</sup>, and 2.6 × 10<sup>17</sup> cm<sup>–3</sup>, respectively, and the corresponding values for 1% Sb doped samples
are 10<sup>4</sup>, 2.0 V, 1.24 cm<sup>2</sup>·V<sup>–1</sup>·s<sup>–1</sup>, and 3.8 × 10<sup>17</sup> cm<sup>–3</sup>. We further investigated the universality of piezotronic
effect in the as-synthesized Sb-doped p-type ZnO NWs and reported
for the first time strain-gated piezotronic transistors as well as
piezopotential-driven mechanical energy harvesting based on solution-grown
p-type ZnO NWs. The results presented here broaden the scope of piezotronics
and extend the framework for its potential applications in electronics,
optoelectronics, smart MEMS/NEMS, and human-machine interfacing
Optimizing Performance of Silicon-Based p–n Junction Photodetectors by the Piezo-Phototronic Effect
Silicon-based p–n junction photodetectors (PDs) play an essential role in optoelectronic applications for photosensing due to their outstanding compatibility with well-developed integrated circuit technology. The piezo-phototronic effect, a three-way coupling effect among semiconductor properties, piezoelectric polarizations, and photon excitation, has been demonstrated as an effective approach to tune/modulate the generation, separation, and recombination of photogenerated electron–hole pairs during optoelectronic processes in piezoelectric-semiconductor materials. Here, we utilize the strain-induced piezo-polarization charges in a piezoelectric n-ZnO layer to modulate the optoelectronic process initiated in a p-Si layer and thus optimize the performances of p-Si/ZnO NWs hybridized photodetectors for visible sensing <i>via</i> tuning the transport property of charge carriers across the Si/ZnO heterojunction interface. The maximum photoresponsivity <i>R</i> of 7.1 A/W and fastest rising time of 101 ms were obtained from these PDs when applying an external compressive strain of −0.10‰ on the ZnO NWs, corresponding to relative enhancement of 177% in <i>R</i> and shortening to 87% in response time, respectively. These results indicate a promising method to enhance/optimize the performances of non-piezoelectric semiconductor material (<i>e</i>.<i>g</i>., Si) based optoelectronic devices by the piezo-phototronic effect
Triboelectric Active Sensor Array for Self-Powered Static and Dynamic Pressure Detection and Tactile Imaging
We report an innovative, large-area, and self-powered pressure mapping approach based on the triboelectric effect, which converts the mechanical stimuli into electrical output signals. The working mechanism of the triboelectric active sensor (TEAS) was theoretically studied by both analytical method and numerical calculation to gain an intuitive understanding of the relationship between the applied pressure and the responsive signals. Relying on the unique pressure response characteristics of the open-circuit voltage and short-circuit current, we realize both static and dynamic pressure sensing on a single device for the first time. A series of comprehensive investigations were carried out to characterize the performance of the TEAS, and high sensitivity (0.31 kPa<sup>–1</sup>), ultrafast response time (<5 ms), long-term stability (30 000 cycles), as well as low detection limit (2.1 Pa) were achieved. The pressure measurement range of the TEAS was adjustable, which means both gentle pressure detection and large-scale pressure sensing were enabled. Through integrating multiple TEAS units into a sensor array, the as-fabricated TEAS matrix was capable of monitoring and mapping the local pressure distribution applied on the device with distinguishable spatial profiles. This work presents a technique for tactile imaging and progress toward practical applications of nanogenerators, providing potential solutions for accomplishment of artificial skin, human-electronic interfacing, and self-powered systems
Single-Electrode-Based Sliding Triboelectric Nanogenerator for Self-Powered Displacement Vector Sensor System
We report a single-electrode-based sliding-mode triboelectric nanogenerator (TENG) that not only can harvest mechanical energy but also is a self-powered displacement vector sensor system for touching pad technology. By utilizing the relative sliding between an electrodeless polytetraÂfluoroÂethylene (PTFE) patch with surface-etched nanoparticles and an Al electrode that is grounded, the fabricated TENG can produce an open-circuit voltage up to 1100 V, a short-circuit current density of 6 mA/m<sup>2</sup>, and a maximum power density of 350 mW/m<sup>2</sup> on a load of 100 MΩ, which can be used to instantaneously drive 100 green-light-emitting diodes (LEDs). The working mechanism of the TENG is based on the charge transfer between the Al electrode and the ground by modulating the relative sliding distance between the tribo-charged PTFE patch and the Al plate. Grating of linear rows on the Al electrode enables the detection of the sliding speed of the PTFE patch along one direction. Moreover, we demonstrated that 16 Al electrode channels arranged along four directions were used to monitor the displacement (the direction and the location) of the PTFE patch at the center, where the output voltage signals in the 16 channels were recorded in real-time to form a mapping figure. The advantage of this design is that it only requires the bottom Al electrode to be grounded and the top PTFE patch needs no electrical contact, which is beneficial for energy harvesting in automobile rotation mode and touch pad applications
Triboelectric Active Sensor Array for Self-Powered Static and Dynamic Pressure Detection and Tactile Imaging
We report an innovative, large-area, and self-powered pressure mapping approach based on the triboelectric effect, which converts the mechanical stimuli into electrical output signals. The working mechanism of the triboelectric active sensor (TEAS) was theoretically studied by both analytical method and numerical calculation to gain an intuitive understanding of the relationship between the applied pressure and the responsive signals. Relying on the unique pressure response characteristics of the open-circuit voltage and short-circuit current, we realize both static and dynamic pressure sensing on a single device for the first time. A series of comprehensive investigations were carried out to characterize the performance of the TEAS, and high sensitivity (0.31 kPa<sup>–1</sup>), ultrafast response time (<5 ms), long-term stability (30 000 cycles), as well as low detection limit (2.1 Pa) were achieved. The pressure measurement range of the TEAS was adjustable, which means both gentle pressure detection and large-scale pressure sensing were enabled. Through integrating multiple TEAS units into a sensor array, the as-fabricated TEAS matrix was capable of monitoring and mapping the local pressure distribution applied on the device with distinguishable spatial profiles. This work presents a technique for tactile imaging and progress toward practical applications of nanogenerators, providing potential solutions for accomplishment of artificial skin, human-electronic interfacing, and self-powered systems
3D Fiber-Based Hybrid Nanogenerator for Energy Harvesting and as a Self-Powered Pressure Sensor
In the past years, scientists have shown that development of a power suit is no longer a dream by integrating the piezoelectric nanogenerator (PENG) or triboelectric nanogenerator (TENG) with commercial carbon fiber cloth. However, there is still no design applying those two kinds of NG together to collect the mechanical energy more efficiently. In this paper, we demonstrate a fiber-based hybrid nanogenerator (FBHNG) composed of TENG and PENG to collect the mechanical energy in the environment. The FBHNG is three-dimensional and can harvest the energy from all directions. The TENG is positioned in the core and covered with PENG as a coaxial core/shell structure. The PENG design here not only enhances the collection efficiency of mechanical energy by a single carbon fiber but also generates electric output when the TENG is not working. We also show the potential that the FBHNG can be weaved into a smart cloth to harvest the mechanical energy from human motions and act as a self-powered strain sensor. The instantaneous output power density of TENG and PENG can achieve 42.6 and 10.2 mW/m<sup>2</sup>, respectively. And the rectified output of FBHNG has been applied to charge the commercial capacitor and drive light-emitting diodes, which are also designed as a self-powered alert system
Single-Electrode-Based Sliding Triboelectric Nanogenerator for Self-Powered Displacement Vector Sensor System
We report a single-electrode-based sliding-mode triboelectric nanogenerator (TENG) that not only can harvest mechanical energy but also is a self-powered displacement vector sensor system for touching pad technology. By utilizing the relative sliding between an electrodeless polytetraÂfluoroÂethylene (PTFE) patch with surface-etched nanoparticles and an Al electrode that is grounded, the fabricated TENG can produce an open-circuit voltage up to 1100 V, a short-circuit current density of 6 mA/m<sup>2</sup>, and a maximum power density of 350 mW/m<sup>2</sup> on a load of 100 MΩ, which can be used to instantaneously drive 100 green-light-emitting diodes (LEDs). The working mechanism of the TENG is based on the charge transfer between the Al electrode and the ground by modulating the relative sliding distance between the tribo-charged PTFE patch and the Al plate. Grating of linear rows on the Al electrode enables the detection of the sliding speed of the PTFE patch along one direction. Moreover, we demonstrated that 16 Al electrode channels arranged along four directions were used to monitor the displacement (the direction and the location) of the PTFE patch at the center, where the output voltage signals in the 16 channels were recorded in real-time to form a mapping figure. The advantage of this design is that it only requires the bottom Al electrode to be grounded and the top PTFE patch needs no electrical contact, which is beneficial for energy harvesting in automobile rotation mode and touch pad applications
Single-Electrode-Based Sliding Triboelectric Nanogenerator for Self-Powered Displacement Vector Sensor System
We report a single-electrode-based sliding-mode triboelectric nanogenerator (TENG) that not only can harvest mechanical energy but also is a self-powered displacement vector sensor system for touching pad technology. By utilizing the relative sliding between an electrodeless polytetraÂfluoroÂethylene (PTFE) patch with surface-etched nanoparticles and an Al electrode that is grounded, the fabricated TENG can produce an open-circuit voltage up to 1100 V, a short-circuit current density of 6 mA/m<sup>2</sup>, and a maximum power density of 350 mW/m<sup>2</sup> on a load of 100 MΩ, which can be used to instantaneously drive 100 green-light-emitting diodes (LEDs). The working mechanism of the TENG is based on the charge transfer between the Al electrode and the ground by modulating the relative sliding distance between the tribo-charged PTFE patch and the Al plate. Grating of linear rows on the Al electrode enables the detection of the sliding speed of the PTFE patch along one direction. Moreover, we demonstrated that 16 Al electrode channels arranged along four directions were used to monitor the displacement (the direction and the location) of the PTFE patch at the center, where the output voltage signals in the 16 channels were recorded in real-time to form a mapping figure. The advantage of this design is that it only requires the bottom Al electrode to be grounded and the top PTFE patch needs no electrical contact, which is beneficial for energy harvesting in automobile rotation mode and touch pad applications