Papers by Keyword: Absorption Enhancement

Abstract: Metal nanoparticles (MNPs) induced light absorption enhancement using for the improvement of power conversion efficiency of organic solar cells (OSCs) is a new research direction in photovoltaics. However, the device performance influence of the shape and size of MNPs has not been well investigated. In this paper, we focused on the comparison study of the optical absorption enhancement between silver nanospheres (Ag-NSs) and silver nanocubes (Ag-NCs) which are embedded in the active layer of OSCs using finite element method (FEM) simulation. Influence of the structural parameters, including the size and shape of nanoparticels, and their relative distance are systematically discussed. The results indicated that the light absorption enhancement employing Ag-NCs is much higher than that of Ag-NSs in the 300–800 nm wavelength range. Meantime, once the distance between the adjacent nanoparticles is well controlled, the optimal absorption enhancement factor of OSCs can be obtained. As the scattering cross-section of Ag-NCs is much higher than that of Ag-NSs over a broad wavelength range, the optimized light enhancement of Ag-NCs reaches 19 % which is 1.26 times higher than that of Ag-NSs.

Abstract: The enhancement characteristics of carbon nanotubes (CNTs) on CO₂ absorption were investigated experimentally a stirred thermostatic reactor. A comparison of CNTs with micro active carbon was made. From the experimental results, significant enhancement of CO₂ absorption was obtained by both CNTs and micro active carbon, however, different change trends with stirring speed for the two solid particles was observed. With increasing stirring speed, the enhancement factor was decreased in AcC suspensions, whereas in CNT slurries it is increased. The experimental phenomena demonstrated a difference in enhancement mechanism for different size particles. For nanoparticles, besides the grazing effect, the micro-convection caused by Brownian motion should be also taken into account. The micro-convection strengthens the interaction of the concentration field around the particles and thus increases the diffusion rate of the solute. In addition, the agglomeration of the nanoparticle was also an important influencing factor. Due to the agglomeration of the particle, the enhancement factor for CNTs increases initially with increasing stirring speed. A three-dimensional microcosmic mass transfer model was developed to explain the experimental phenomena. Based on the model, the interaction of the flow field around the particles was analyzed.

Abstract: Enhancing absorption of solar cells over the solar spectrum is one of the most important ways to improve such devices’ performances. In this research, two-dimensional surface photonic designs were suggested to introduce rotationally distributed reciprocal vectors, which will match the guiding modes of the thin planar layer of an active material, and thus to further couple the incident light laterally into the layer. This allows the use of a fewer amount of active materials, increases the devices’ angle acceptance, and reduces costs for both fabrication and system installation.