Charge Entrapment Research Articles

Coaxial tribonegative yarn TENG with aromatic polyimide as charge entrapment layer for real-time edge ball assessment in cricket sports

Energy harvesting yarns working on triboelectric effect by converting mechanical energy into electricity for running wearable electronics as well as operating as self-powered sensors, are superb choices for wearable electronics of current and future generations. However, current yarn-based triboelectric nanogenerators (TENGs) designed through electrospinning process are limited in achieving higher outputs, comfort, mechanical strength, washability, and industrial scalability. In this study, we introduce a flexible and durable tribonegative yarn TENG (TNY) with an electrospun polyimide (PI) intermediate charge trapping layer between the electrode and electrospun superhydrophobic polyvinylidene difluoride (PVDF)/Poly(dimethylsiloxane) (PDMS). In this coaxial arrangement, the PI charge entrapment layer enabled the TNY to exhibit an output voltage of 14 V in a 2.5 cm length, compared to only 8 V for TNY without PI layer. The TNY can be successfully woven and knitted into electronic textiles (E-Textiles), with their outputs compared based on various knitted and woven patterns. The E-Textile maintained considerable outputs after washing and withstood 5000 Martindale abrasion cycles. The superhydrophobic behavior also enabled TNY to harvest water energy from a running tap. We demonstrated the potential of these E-Textiles for edge ball sensing in cricket sports in real-time by leveraging the benefits of triboelectrification, thereby avoiding the need for complex camera setups and sound systems for judging ball movements at ± 140 km/hr in real sports. We also employed E-Textiles for smart switch functions, which can be beneficial in smart systems. This study demonstrates the improved performance of yarn-based TENGs and further extends the applications of TENGs in sports analysis. It provides a facile and high-efficiency approach for designing triboelectric sensors, offering a cost-effective alternative to complex and expensive sports equipment.

Gamma glycine enhances efficiency of organic hybrid piezoelectric-triboelectric nanogenerators

This study presents a comprehensive exploration of enhancing the electrical output of flexible hybrid piezoelectric-triboelectric nanogenerators (P-TENG) through the incorporation of γ-glycine (γ-GC) into fully organic γ-GC/chitosan (CS) composites. A systematic investigation of the effects of γ-GC content (wt%) on the material characteristics and resulting electrical output signal is conducted. The research demonstrates the pivotal role of optimized γ-GC and CS concentrations in achieving superior performance. Through adherence to the percolation threshold principle, a critical γ-GC content is identified, leading to the attainment of the highest output signal. Three theoretical explanations substantiate this observation: firstly, molecular polarization occurring at the interface; secondly, the establishment of a well-connected filler internetwork; and thirdly, mitigation of air breakdown limitations. The interaction of γ-GC and CS fosters a robust hydrogen bond network, aligning interface polarization coherently. Efficient internetwork connections between γ-GC fillers facilitate facile charge generation and transfer. Furthermore, utilizing an appropriate quantity of γ-GC ensures optimal charge entrapment while circumventing issues related to air breakdown. The optimal electrical output is achieved by using 50% γ-GC, resulting in an open-circuit voltage (VOC) of 79 V and a short-circuit current (ISC) of 64 µA. The maximum power output (Pmax) registers at 705.96 µW under an external load resistance of 1 MΩ. Importantly, practical applications are demonstrated, including capacitor charging (0.22 μF and 0.33 μF), illumination of 100 LEDs, and operation of a scientific calculator-equipped watch.

Utilizing trapped charge at bilayer 2D MoS2/SiO2 interface for memory applications

In this work we use conductive atomic force microscopy (cAFM) to study the charge injection process from a nanoscale tip to a single isolated bilayer 2D MoS2 flake. The MoS2 is exfoliated and bonded to ultra-thin SiO2/Si substrate. Local current–voltage (IV) measurements conducted by cAFM provides insight in charge trapping/de-trapping mechanisms at the MoS2/SiO2 interface. The MoS2 nano-flake provides an adjustable potential barrier for embedded trap sites where the charge is injected from AFM tip is confined at the interface. A window of (ΔV ∼ 1.8 V) is obtain at a reading current of 2 nA between two consecutive IV sweeps. This is a sufficient window to differentiate between the two states indicating memory behavior. Furthermore, the physics behind the charge entrapment and its contribution to the tunneling mechanisms is discussed.

The Band-Gap Modulation of Graphyne Nanoribbons by Edge Quantum Entrapment.

Using ab initio calculation coupled with the bond-order-length-strength (BOLS) approximation, we investigate the configurations and electronic properties of (α, β)-graphyne nanoribbons (GYNRs) with armchair (AGYNRs) and zigzag (ZGYNRs) edges. Our investigation shows that the armchair-edged β-GYNRs and all α-GYNRs are semiconductors with suitable band-gaps, and that their band-gaps increase as the widths of nanoribbons decrease; on the other hand, zigzag-edged β-GYNRs appear to be zero-band-gap materials. Observation results suggest that (i) atomic undercoordination shortens and stiffens the C–C bond, which contributes to the Hamiltonian and hence widens the band-gap intrinsically; (ii) zigzag-edged β-GYNRs lack a band-gap due to the edge-undercoordinated atoms lacking the energy to open the β-graphyne gap; and (iii) the edge-undercoordination of atoms occurs during charge entrapment.

Reliability of High-Voltage Molding Compounds: Particle Size, Curing Time, Sample Thickness, and Voltage Impact on Polarization

Reliability of dielectric composite materials (DCMs) is a multifaceted problem. Both high voltage and dimensional miniaturization decrease the path length for charge dissipation in the DCMs. This results in short life due to charge entrapment and uncontrolled release. The source of trapped charges in the DCM arises due to the intrinsic interfacial polarization in the filled system. From the compound perspective, at least four interacting variables are involved in determining relative reliability of DCMs: filler size, curing time, thickness, and polarization voltage magnitude. Experimental and data analysis of all four variables, with uncertainty propagated for each factor, is paramount to understanding behavior of each property and its interactions, shaping DCMs characteristics. Combining views from The Design of Experiments (Fisher, 1935), modern statistics (Hand, 2008), and analytical computer software (NIST Dataplot 2015) yields a free graphic user interface tool to optimize the design of compound mixtures to minimize the polarization for increased reliability.

Electric-Field Assisted Desorption of Water Molecules in DNA Functionalized CNT Network

This paper introduces the concept of electric field assisted desorption (EAD) of water molecules from the surface of DNA functionalized carbon nanotube (DFC) resistive network when a bias voltage VDS is applied across it. EAD at a given VDS is measured in terms of the characteristic life-time of desorption τ. The bias voltage produces an electric field E that aligns the molecular dipoles of water parallel to E. Mutually aligned neighboring dipole moments of water maximize the potential energy and drives them into a nonequilibrium state. The molecular dipoles return to the minimum potential energy state when water molecules escape from the surface of DFC. We find an exponential decrease in τ for V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> <; V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cr</sub> , which is attributed to EAD. Beyond Vcr, we observe a linear increase in τ which is due to charge entrapment within ultrathin layer of water sandwiched between dielectric layers of DNA and air that prevents fast desorption of water molecules.

Dynamics of space and polarization charges of ferroelectric thin films measured by atomic force microscopy

Retention behavior and local hysteresis characteristics in Pb(Zr 0.52Ti 0.48)O 3 (PZT) thin films on Pt electrodes have been investigated by electrostatic force microscopy (EFM). A sol–gel method is used to synthesize PZT thin films and drying conditions are carefully explored over a wide range of temperature. Decay and retention mechanisms of single-poled and reverse-poled regions of the ferroelectric thin films are explained by space charge redistribution. Trapping behavior of space charges is dependent on the nature of interface between ferroelectric thin films and bottom electrodes. Local measurement of polarization–electric field curves by EFM shows inhomogeneous space charge entrapment.

Wide-linear-range subthreshold OTA for low-power, low-Voltage, and low-frequency applications

We propose a novel configuration of linearized subthreshold operational transconductance amplifier (OTA) for low-power, low-voltage, and low-frequency applications. By using multiple input floating-gate (MIFG) MOS devices and implementing a cubic-distortion-term-canceling technique, the linear range of the OTA is up to 1.1 Vpp under a 1.5-V supply for less than 1% of transconductance variation, according to testing results from a circuit designed in a double-poly, 0.8-/spl mu/m, CMOS process. The power consumption of the OTA remains below 1 /spl mu/W for biasing currents in the range between 1-200 nA. The offset voltage due to secondary effects (contributed by parasitic capacitances, errors and mismatches of parameters, charge entrapment, etc.) is of the order of a few ten millivolts, and can be canceled by adjusting biasing voltages of input MIFG MOS transistors.

Nanoscale observation of photoinduced domain pinning and investigation of imprint behavior in ferroelectric thin films

Piezoresponse force microscopy has been used to investigate the nanoscale mechanism of imprint behavior of ferroelectric PbTiO3 thin films by studying the photoinduced changes in the hysteresis loops of individual grains. Illumination of the film with UV light resulted in a voltage shift opposite to that observed in ferroelectric thin film capacitors. This effect is attributed to the generation of an electric field within the surface dielectric layer as a result of the interaction between photoinduced charges and polarization charges. Application of a small nonswitching bias to the film with simultaneous UV illumination resulted in domain pinning in the grains where the polarization direction coincided with the direction of the applied field, in agreement with the proposed model. Domain pinning was also observed in grains with polydomain structure suggesting that charge entrapment at the existing domain boundaries in the bulk of the film contributes to the suppression of switchable polarization. However, a symmetric character of hysteresis loops observed in such grains implies that charge entrapment in the bulk of the film does not cause the voltage shift. It has been suggested that a thin high-dielectric interfacial layer can improve the imprint behavior of ferroelectric capacitors.

Space-charge influenced-injection model for conduction in Pb(ZrxTi1−x)O3 thin films

A comprehensive study of leakage conduction in Pb(ZrxTi1−x)O3films with Pt electrodes is carried out. The conduction properties of films prepared in different ways (sol–gel coating, metalorganic chemical vapor deposition, sputtering) were studied by using different experimental techniques including variation of the applied voltage profile, photoassisted measurements, measurements at elevated temperatures, and variation of the prehistory of the samples. Based on the collective data, it is concluded that two different regimes of carrier injection (with the critical electric field of the crossover between these regimes being independent of the measuring technique) are responsible for true leakage conduction in Pt–Pb(ZrxTi1−x)O3–Pt films. A space-charge influenced-injection model is proposed for the interpretation of the experimental results obtained. This model describes well the main features of the observed current–voltage characteristics and provides a reasonable fit for the current–voltage curves measured at elevated temperatures, the values of the fitting parameters being in good agreement with the results of other studies. The true leakage current in the Pt–Pb(ZrxTi1−x)O3–Pt system is shown to be time dependent because of the influence of the injected charge entrapment during measurement. According to the present results, an activation energy of about 0.9 eV describes the temperature dependence of conduction in the range of 70–200 °C. It is shown that a possible origin of the crossover in the activation energy at the temperature range 120–140 °C widely reported in the literature can be a consequence of the measuring procedure.