We integrate resonant-cavity light-emitting diodes containing quantum dots onto substrates with giant piezoelectric response. Via strain, the energy of the photons emitted by the diode can be precisely controlled during electrical injection over a spectral range larger than 20 meV. Simultaneously, the exciton fine-structure-splitting and the biexciton binding energy can be tuned to the values required for entangled photon generation.

Highly flexible bismuth Hall sensors on polymeric foils are fabricated, and the key optimization steps that are required to boost their sensitivity to the bulk value are identified. The sensor can be bent around the wrist or positioned on the finger to realize an interactive pointing device for wearable electronics. Furthermore, this technology is of great interest for the rapidly developing market of ­eMobility, for optimization of eMotors and magnetic bearings.

Abstract:In this work, stretchable magnetic sensorics is successfully established by combining metallic thin films revealing a giant magnetoresistance effect with elastomeric materials. Stretchability of the magnetic nanomembranes is achieved by specific morphologic features (e.g. wrinkles), which accommodate the applied tensile deformation while maintaining the electrical and magnetic integrity of the sensor device. The entire development, from the demonstration of the world-wide first elastically stretchable magnetic sensor to the realization of a technology platform for robust, ready-touse elastic magnetoelectronics with fully strain invariant properties, is described. The prepared soft giant magnetoresistive devices exhibit the same sensing performance as on conventional rigid supports, but can be stretched uniaxially or biaxially reaching strains of up to 270% and endure over 1,000 stretching cycles without fatigue. The comprehensive magnetoelectrical characterization upon tensile deformation is correlated with in-depth structural investigations of the sensor morphology transitions during stretching.With their unique mechanical properties, the elastic magnetoresistive sensor elements readily conform to ubiquitous objects of arbitrary shapes including the human skin. This feature leads electronic skin systems beyond imitating the characteristics of its natural archetype and extends their cognition to static and dynamic magnetic fields that by no means can be perceived by human beings naturally.Various application fields of stretchable magnetoelectronics are proposed and realized throughout this work. The developed sensor platform can equip soft electronic systems with navigation, orientation, motion tracking and touchless control capabilities. A variety of novel technologies, like smart textiles, soft robotics and actuators, active medical implants and soft consumer electronics will benefit from these new magnetic functionalities. Michael Melzer: Stretchable MagnetoelectronicsOutline 4

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Lithium-ion batteries (LIBs) have attracted considerable interest because of their wide range of environmentally friendly applications, such as portable electronics, electric vehicles (EVs), and hybrid electric vehicles (HEVs). [1][2][3][4][5] For the next generation of LIBs with high energy and high power density, improvements on currently used electrode materials are urgently needed. [6][7][8][9][10] Among various anode materials, Si has been extensively studied owing to its highest theoretical capacity (4200 mA h g À1 ), abundance in nature, low cost, and nontoxicity. However, Si-based anodes are notoriously plagued by poor capacity retention resulting from large volume changes during alloy/de-alloy processes (400 %). The intrinsic strain generated during such expansion and contraction easily leads to electrode pulverization and capacity fading. Thus, it is a big challenge to achieve both excellent cyclability and enhanced capacity of Si-based anode materials.Significant efforts have been devoted to circumvent this issue caused by the volume change of silicon. [11][12][13][14][15] Recently, a number of Si nanostructures, including nanoparticles, [15,16] nanowires/nanorods, [17][18][19] nanotubes, [20] and porous nanostructures [21,22] as well as their composites, [23] have been fabricated to achieve improved cycling performance.Among them, tubular structures, with extra interior space for electron and ion transport, as well as for accommodating volume changes, are one of the most attractive and promising configurations for LIBs. However, such anode materials are still far from commercialization, and new strategies for the synthesis of novel structures with superior cycling performance and stability are still much sought-after.Herein, we report a new tubular configuration made from naturally rolled-up C/Si/C trilayer nanomembranes, which exhibits a highly reversible capacity of approximately 2000 mA h g À1 at 50 mA g À1 , and approximately 100 % capacity retention at 500 mA g À1 after 300 cycles. The sandwich-structured C/Si/C composites, with moderate kinetic properties toward Li + ion and electron transport, are of the highest quality. The excellent cycling performance is related to the thin-film effect combined with carbon coating, which play a structural buffering role in minimizing the mechanical stress induced by the volume change of Si. The energy reduction in C/Si/C trilayer nanomembranes after rolling up into multi-winding microtubes results in a significantly reduced intrinsic strain, which can improve capacity and cycling performance. This synthetic process could be compatible with existing industrial sputtering deposition processes as well as roll-to-roll thin-film fabrication technology.The strategy for the self-release of C/Si/C trilayer nanomembranes using rolled-up nanotechnology [24] to form multilayer C/Si/C microtubes is shown in Scheme 1. First, a sacrificial layer (red color, photoresist ARP 3510) was deposited on top of the Si substrates by spin-coating, then trilayer C/Si/C (10/40/10 nm, ...