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Creators/Authors contains: "Kingon, Angus I."

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  1. Abstract

    The device concept of ferroelectric-based negative capacitance (NC) transistors offers a promising route for achieving energy-efficient logic applications that can outperform the conventional semiconductor technology, while viable operation mechanisms remain a central topic of debate. In this work, we report steep slope switching in MoS2transistors back-gated by single-layer polycrystalline PbZr0.35Ti0.65O3. The devices exhibit current switching ratios up to 8 × 106within an ultra-low gate voltage window of$$V_{{{\mathrm{g}}}} = \pm \! 0.5$$Vg=±0.5V and subthreshold swing (SS) as low as 9.7 mV decade−1at room temperature, transcending the 60 mV decade−1Boltzmann limit without involving additional dielectric layers. Theoretical modeling reveals the dominant role of the metastable polar states within domain walls in enabling the NC mode, which is corroborated by the relation between SS and domain wall density. Our findings shed light on a hysteresis-free mechanism for NC operation, providing a simple yet effective material strategy for developing low-power 2D nanoelectronics.

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  2. Abstract

    Key solutions for material selection, processing, and performance of environmentally friendly high‐power generators are addressed. High voltage and high power generation of flexible devices using piezoelectric Bi0.5(Na0.78K0.22)TiO3nanoparticle filler–polydimethylsiloxane (PDMS) elastomeric matrix for a lead‐free piezoelectric composite film on a cellulose paper substrate is demonstrated. To elucidate the principle of power generation by the piezoelectric composite configuration, the dielectric and piezoelectric characteristics of the composite film are investigated and the results are compared with those of theoretical modeling. The paper‐based composite generator produces a large output voltage of ≈100 V and an average current of ≈20 µA (max. ≈30 µA) through tapping stimulation, which is a record‐high performance compared to previously reported flexible lead‐free piezoelectric composite energy harvesters. Moreover, a triboelectric‐hybridized piezoelectric composite device using a micro‐patterned PDMS shows a much higher output voltage of ≈250 V and output power of ≈0.5 mW, which drives 300 light‐emitting diodes. These results prove that a new class of paper‐based and lead‐free energy harvesting device provides a strong possibility for enlarging the functionality and the capability of high‐power scavengers in flexible and wearable electronics such as sensors and medical devices.

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  3. Abstract

    In the past two decades, mechanical energy harvesting technologies have been developed in various ways to support or power small‐scale electronics. Nevertheless, the strategy for enhancing current and charge performance of flexible piezoelectric energy harvesters using a simple and cost‐effective process is still a challenging issue. Herein, a 1D–3D (1‐3) fully piezoelectric nanocomposite is developed using perovskite BaTiO3(BT) nanowire (NW)‐employed poly(vinylidene fluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)) for a high‐performance hybrid nanocomposite generator (hNCG) device. The harvested output of the flexible hNCG reaches up to ≈14 V and ≈4 µA, which is higher than the current levels of even previous piezoceramic film‐based flexible energy harvesters. Finite element analysis method simulations study that the outstanding performance of hNCG devices attributes to not only the piezoelectric synergy of well‐controlled BT NWs and within P(VDF‐TrFE) matrix, but also the effective stress transferability of piezopolymer. As a proof of concept, the flexible hNCG is directly attached to a hand to scavenge energy using a human motion in various biomechanical frequencies for self‐powered wearable patch device applications. This research can pave the way for a new approach to high‐performance wearable and biocompatible self‐sufficient electronics.

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