Piezoelectric nanocomposites based nanogenerators (NGs) are gaining extensive attention as energy harvesters and self-powered tactile sensors for their applications in wearable electronics and personal healthcare. Herein, we report a facile, cost-effective and industrially scalable process flow for the fabrication of high performance mechanically robust nanocomposites based stretchable nanogenerator (SNG) on polydimethylsiloxane substrate. The inorganic / organic nanocomposite piezoelectric energy harvesting devices are realized by encapsulating the ZnO nanowires in a parylene C polymer matrix. The suggested fabrication process flow is implemented to fabricate SNG on flexible bank cards. The SNG devices exhibits excellent performances with a high open circuit voltage ~10 V, short-circuit current density ~0.11 µA/cm², and peak power ~3 µW under a vertical compressive force using a mechanical shaker. The obtained electricity from the SNG devices is used to drive electronic devices such as liquid crystal displays without employing any storage unit, implying the device significance in the field of consumer electronics. Besides, commercially available energy harvesting modules is used to store the generated electrical energy in capacitors. Furthermore, the SNG device can be adopted as self-powered wearable tactile sensor for detecting slight body movements which shows its potential applications in autonomous wearable electronics.

Controlling properties of one-dimensional (1D) semiconducting nanostructures is essential for the advancement of electronic devices. In this work, we present a low-temperature hydrothermal growth process enabling density control of aligned high aspect ratio ZnO nanowires (NWs) on seedless Au surface. A two order of magnitude change in ZnO NW density is demonstrated via careful control of the ammonium hydroxide concentration (NH4OH) in the solution. Based on the experimental observations, we further, hypothesized the growth mechanism leading to the density controlled growth of ZnO NWs. Moreover, the effect of NH4OH on the electrical properties of ZnO NWs, such as doping and field-effect mobility, is thoroughly investigated by fabricating single nanowire field-effect transistors. The electrical study shows the increase of free charge density while decrease of mobility in ZnO NWs with the increase of NH4OH concentration in the growth solution. These findings show that NH4OH can be used for simultaneous tuning of the NW density and electrical properties of the ZnO NWs grown by hydrothermal approach. The present work will guide the engineers and researchers to produce low-temperature density controlled aligned 1D ZnO NWs over wide range of substrates, including plastics, with tunable electrical properties.

In the present paper, the influence of manganese doping on the dielectric properties of BaSrTiO 3 thin films is presented. The real and imaginary parts of the material's permittivity have been measured in a large frequency range (100 Hz-1 MHz) and as a function of the electric field. The tunability and the figure of merit of the material have been obtained from the measurement of the permittivity under an applied DC bias electric field. For the undoped material, the dielectric losses become important for a large DC bias which leads to breakdown. At a suitable dopant rate, this effect disappears. In order to better understand the origin of the related phenomena, we measure the permittivity as a function of the AC excitation amplitude and we decompose the obtained permittivity with the hyperbolic law. This enables to extract the different contributions of the bulk (low frequency diffusion and high frequency lattice relaxation) and of the domain wall motions (vibration and pinning/unpinning) to the material's dielectric permittivity and to understand the effect of manganese doping on each contribution. Knowledge of the related mechanisms allows us to establish the optimum dopant rate (mainly conditioned by the lattice contribution) and to reduce the domain wall motion, which finally is beneficial for the desired properties of the ferroelectric thin film. A particular attention is paid to low frequency diffusion, an especially harmful effect when a DC biasing is mandatory (tunable electronic component in mobile telecommunication devices for example).