• Energy Research
• Open Source close
• Embargo close
• physical sciences close
• IT close

Silicon carbide/silicon rich carbide multilayers, aimed at the formation of silicon nanodots for photovoltaic applications, have been studied. The electrical properties have been investigated at the nano-scale by conductive Atomic Force Microscopy (c-AFM) and at macro-scale by temperature dependent conductivity measurements. The mixture is composed of highly conductive Si nanoclusters and moderately conductive SiC nanoclusters in a disordered matrix. The conduction mechanism takes place via band states induced by the disorder at the interface between nanodot clusters. Structural properties have been extracted by optical spectroscopy analyses. The results contribute to the understanding of the microscopical electronic mechanisms of the composite material, which is a candidate for third generation photovoltaics.

Self-organizing nanopatterns can enable economically competitive, industrially applicable light-harvesting platforms for thin-film solar cells. In this work, we present transparent solar cell substrates having quasiperiodic uniaxial nanowrinkle patterns with high optical haze values. The self-organized nanowrinkle template is created by controlled heat-shrinking of metal-deposited pre-stretched polystyrene sheets. A scalable UV nanoimprinting method is used to transfer the nanopatterns to glass substrates on which single-junction hydrogenated amorphous silicon p-i-n solar cells are subsequently fabricated. The structural and optical analyses of the solar cell show that the nanowrinkle pattern is replicated throughout the solar cell structure leading to enhanced absorption of light. The efficient broadband light-trapping in the nanowrinkle solar cells results in very high 18.2 mA/cm2 short-circuit current density and 9.5% energy-conversion efficiency, which respectively are 35.8% and 39.7% higher than the values obtained in flat-substrate solar cells. The cost- and time-efficient technique introduces a promising new approach to customizable light-management strategies in thin-film solar cells.

Understanding how the deformation history affects the retraction dynamics of viscoelastic liquid films can provide a tool to design materials. In this paper, we investigate the stretching and retraction of circular viscoelastic liquid films through finite element numerical simulations. We consider a discoid domain made of a viscoelastic liquid. Its central hole is first ‘closed’ and then released, being left free to open under the effect of inertial, surface, viscous, and elastic forces. We perform a parametric study of film retraction, aiming at understanding the effects of the physical and operating parameters on it. In particular, we consider different viscoelastic constitutive equations, namely, Oldroyd-B, Giesekus (Gsk), and Phan Thien-Tanner (PTT) models, and different values of the film initial thickness. For each liquid and geometry, we investigate the effects of the film stretching rate and of liquid inertia, elasticity, and flow-dependent viscosity on the dynamics of the hole opening.