Integrated Calendar

Nanostructures and nanostructured substrates show enhanced coupling to artificial membranes, cells, and tissue. Such nano-bio interfaces offer better sensitivity and spatial resolution as compared to conventional planar structures. Here we report the electrical properties of silicon nanowires (SiNWs) interfaced with embryonic chicken hearts and cultured cardiomyocytes. In addition, by utilizing the bottom-up approach, we extend our work to the sub-cellular regime, and interface cells with the smallest reported device ever and thus exceed the spatial and temporal resolution limits of existing electrical recording techniques. The exceptional synthetic control and flexible assembly of nanowires provides powerful tools for fundamental studies and applications in life science, and opens up the potential of merging active transistors with cells such that the distinction between nonliving and living systems is blurred.

Hybrid materials, composed of organic and inorganic components, have shown to be useful in a variety of optoelectronic applications including electrochromic devices, light emitting diodes, photodetectors and solar cells. In such systems, the key processes of charge and/or energy transfer occur across the organic-inorganic interface and are therefore predominantly influenced by interfacial properties such as surface area, chemical composition and physical interactions. Inherent chemical incompatibility of the organic and inorganic components limits the interfacial surface area, but can be overcome by temperature, use of co-solvents, substrate surface chemistry, or use of suitable compatibilizers. Here we show that the nature of the compatibilizer can be used to direct contact and interactions at the organic-inorganic interface, thus governing the optoelectronic processes across the interface. Few examples will be discussed in which highly ordered conjugated polymer/metal oxide films were prepared using surfactant structure-directing agents (SDAs) with different molecular weights and architectures on flat substrates and in confined spaces. A combination of small X-ray scattering (SAXS), electron microscopy (SEM and TEM), solid-state NMR spectroscopy, and energy-filtered high resolution TEM (EFHRTEM) was used to determine the hierarchical structural ordering and orientation of the materials; and show that the extent to which the conjugated polymer interacts with the hydrophilic metal oxide framework depends on the molecular weight and architecture of the surfactant. Importantly, the molecular-level interactions between the different SDA blocks, the conjugated polymer and the metal oxide framework, are correlated with steady-state and timeresolved photoluminescence measurements of the photo-excitation dynamics of the conjugated polymer and macroscopic photocurrent generation in photovoltaic devices. Therefore, molecular understanding of the compositions and chemical interactions at organic-inorganic interfaces are shown to enable the design, synthesis and control of the photo-physcial properties of hybrid functional materials

Dye sensitized solar cells (DSSC), are low cost alternative to traditional silicon solar cells. Upon illumination the dye absorbs photons, and goes to excited state generating electron and hole pairs. The electrons are injected into the TiO2 conduction band and diffuse to the front contact, simultaneously the holes are injected into redox couple. This work will discuss three crucial topics for improving DSSC performance. (i) Replacing the organic dye molecules (sensitizer) by quantum dots (QDs), which have several advantages over the dye molecules. Semiconductor QDs belonging to group IV-VI, such as PbS and PbSe, are known as good absorbers in the visible and in the near IR regime. They have relatively large ground state cross-section of absorption, long excitonic lifetime, and exceptionally high quantum efficiency of the luminescence. A highly efficient solid state PbS (QDs)/TiO2 heterojunction solar cell will be presented. Importantly, the PbS QDs act here as photosensitizers and at the same time as hole conductors. Therefore no hole conductor is necessary in this type of cell. (ii) Changing the photo-anode (working electrode) of the DSSC using ZnO Nanowires (NWs), which were grown on conductive fluorine doped tin oxide glass. The combination of ZnO NWs with newly developed organic dye shows high power conversion efficiency. (iii) In DSSC a liquid electrolyte (usually iodide/triiodide in acetonitrile) is used, but the presence of organic solvents poses problems for practical implementation. In this topic the liquid electrolyte was replaced with radically new solid-state (or quasi-solid) conductors, in order to reduce potential environmental risks and ensure much greater stability in outdoor operating conditions. Nanomaterials with a porous or layered structure were used, those materials employed a high specific surface area and complex engineered architectures in order to host redox active species.

While stars have been historically considered to be eternal, we now know that some stars become un-stable and explode, producing dazzling cosmic fireworks shows. These events turn out to be very useful natural laboratories, where we can study fundamental physical processes extending from the smallest particle physics scales; nuclear physics questions like the origin of the elements; general relativity and gravitation in the strong field limit; and out to the largest cosmological scales of the Universe as a whole. I will review the various physical mechanisms that lead to the explosive death of stars as supernova ex-plosions, the progress we made during the last few years in understanding these events, and the pro-spects for further advances driven by new technologies.