The use of a low contrast nanosecond laser pulse with relatively low intensity (3 × 10 16 W cm -2 ) allowed enhancing the yield of induced nuclear reactions in advanced solid targets. In particular the "ultraclean" proton-boron fusion reaction, producing energetic alpha-particles without neutron generation, was chosen. A spatially well-defined layer of boron dopants in a hydrogenenriched silicon substrate was used as target. The combination of the specific target geometry and the laser pulse temporal shape allowed the production of an enormous yield of alpha-particles around 10 9 per steradian. This result can be ascribed to the nonlinear interaction of the long laser pulse with the expanding plasma and to the optimal target geometry and composition.

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Multi-walled carbon nanotube (MWCNT) films form efficient heterojunction solar cells with n-type crystalline silicon (n-Si), due to their superior optical and electrical properties. Here, we report air-stable photovoltaic devices with record photoconversion efficiency of 10%. We realized thin films consisting of MWCNTs arranged in semitransparent random networks deposited on n-Si substrates by a simple, rapid, reproducible, and inexpensive vacuum filtration process at room temperature. Such heterojunctions favor high and broadband carrier photogeneration, extending the Si spectral response from near infrared to near ultraviolet range; charge dissociation of ultrafast hot carriers [1]; transport of electrons through n-Si and high-mobility [2] holes through the MWCNT percolative network. Furthermore, by varying the MWCNT film thickness, it is possible tailoring its optical and electrical properties, therefore the overall device optoelectronic features.These results not only pave the way for low-cost, efficient, and broadband photovoltaics, but also are promising for the development of MWCNT-based optoelectronic applications. (Francesco De Nicola) URL: 0039 0672594532 (Francesco De Nicola) ultrafast exciton/charge transfer (1-10 ps) [1, 6-11]; extraordinary high mobility (10 5 cm 2 /Vs) [2]; simple, rapid, and inexpensive solution-processability [12]. Furthermore, the unique one-dimensional structure of CNTs and the inherent properties of the graphitic sp 2 carbon lattice allow the fabrication of photovoltaic cells that are highly thermally conductive, mechanical, chemical, and radiation resistant [13]. Moreover, high aspect ratio and flexibility enable CNTs to be weaved into two-dimensional networks with tunable electrical and optical properties, which can be easily deposited on the surface of several materials [12]. In general, heterojunctions [14] offer more choice of materials with appropriate band gaps covering a wider range of the solar spectrum, and also potential for the development of a variety of nanomaterial/semiconductor solar cells. So far, a number of researchers have investigated the possibility of utilizing CNT films in devices based on crystalline semiconductors such as Si for heterojunction solar cells (we suggest the review in Ref. [15]). In this framework, on one hand Si photogenerates electron-hole pairs and transports electrons to leads. On the other hand, the CNT film acts both as a photogenerating layer and as holetransporting layer, eventually avoiding metal wiring from the device surface, which shade a portion of incident light, thus replacing the costly indium tin oxide (ITO). In this way, charge generation, separation, transport, and collection can be realized partly by the semi-transparent and conductive CNT thin film itself. Currently, researcher main efforts have been focused on single-wall carbon nanotube/silicon (SWCNT/Si) heterojunctions, achieving a photoconversion efficiency (PCE) up to ≈ 12% [16] without any post-process treatments, up to ≈ 11% after chemical doping [17], up to ≈...

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Stoichiometric TI Bi2Se3 ultra-thin films suitable for infra-red optoelectronic applications are obtained from the by-products of nanowires/nanobelts. Tunnelling spectroscopy gives the position of the Fermi level inside the energy bandgap.