Intra-cavity laser-assisted solar-energy conversion

It is shown how to efficiently convert solar into electrical energy, taking advantage of laser amplification and intra-cavity use of a low-efficiency converter. The latter may consist of a low-efficiency transparent photovoltaic cell or a thermoelectric cell integrated into a metallic laser-cavity mirror, constituting a minor intra-cavity loss for the laser operation. The overall power conversion efficiency is derived and discussed for solar end and side pumping geometries and for a variety of current solid-state laser materials. It is shown that power conversion efficiencies comparable with commercial silicon photovoltaic cells are obtained with current laser materials

Surface Morphology of Vapor-Deposited Chitosan: Evidence of Solid-State Dewetting during the Formation of Biopolymer Films

Chitosan is a useful and versatile biopolymer with several industrial and biological applications. Whereas its physical and physicochemical bulk properties have been explored quite intensively in the past, there is a lack of studies regarding the morphology and growth mechanisms of thin films of this biopolymer. Of particular interest for applications in bionanotechnology are ultrathin films with thicknesses under 500 Å. Here, we present a study of thin chitosan films prepared in a dry process using physical vapor deposition and <i>in situ</i> ellipsometric monitoring. The prepared films were analyzed with atomic force microscopy in order to correlate surface morphology with evaporation parameters. We find that the surface morphology of our final thin films depends on both the optical thickness, i.e., measured with ellipsometry, and the deposition rate. Our work shows that ultrathin biopolymer films can undergo dewetting during film formation, even in the absence of solvents and thermal annealing