Nanoparticle plasmonics for 2D-photovoltaics: mechanisms, optimization, and limits.
ABSTRACT Plasmonic nanostructures placed within or near photovoltaic (PV) layers are of high current interest for improving thin film solar cells. We demonstrate, by electrodynamics calculations, the feasibility of a new class of essentially two dimensional (2D) solar cells based on the very large optical cross sections of plasmonic nanoparticles. Conditions for inducing absorption in extremely thin PV layers via plasmon near-fields, are optimized in 2D-arrays of (i) core-shell particles, and (ii) plasmonic particles on planar layers. At the plasmon resonance, a pronounced optimum is found for the extinction coefficient of the PV material. We also characterize the influence of the dielectric environment, PV layer thickness and nanoparticle shape, size and spatial distribution. The response of the system is close to that of a 2D effective medium layer, and subject to a 50% absorption limit when the dielectric environment around the 2D layer is symmetric. In this case, a plasmon induced absorption of about 40% is demonstrated in PV layers as thin as 10 nm, using silver nanoparticle arrays of only 1 nm effective thickness. In an asymmetric environment, the useful absorption may be increased significantly for the same layer thicknesses. These new types of essentially 2D solar cells are concluded to have a large potential for reducing solar electricity costs.
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ABSTRACT: Evenly separated crystalline CuIn0.8Ga0.2Se2 (CIGS) nanoparticles are deposited on ITO-glass substrate by pulsed laser deposition. Such CIGS layers are introduced between conjugated polymer layers and ITO-glass substrates for enhancing light absorbance of polymer solar cells. The P3HT:PCBM absorbance between 300 and 650 nm is enhanced obviously due to the introduction of CIGS nanoparticles. The current density-voltage curves of a P3HT:PCBM/CIGS solar cell demonstrate that the short-circuit current density is improved from 0.77 to 1.20 mA/cm(2). The photoluminescence spectra show that the excitons in the polymer are obviously quenched, suggesting that the charge transfer between the P3HT:PCBM and CIGS occurred. The results reveal that the CIGS nanoparticles may exhibit the localized surface plasmon resonance effect just as metallic nanostructures.Nanoscale Research Letters 06/2014; 9(1):308. DOI:10.1186/1556-276X-9-308 · 2.48 Impact Factor
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ABSTRACT: In my Ph.D. work, I investigated novel optical phenomena in individual and arrays of dielectric microspheres and microcylinders. I addressed the challenging problem of overcoming the diffraction-limit in optical microscopy and invented the immersed microsphere-assisted super-resolution imaging technique. I demonstrated that high-index microspheres or microcylinders immersed in a liquid are capable of collecting the sub-diffraction-limited details of the imaging object and transmit them to the far-field with magnification enabling super-resolution imaging. I proposed that, in principle, such microspheres can also be implanted in elastomers for imaging. I provided a physical explanation for successive beam focusing and extraordinarily small attenuation of light in arrays of coupled microspheres and discovered a novel wave-guiding mechanism in chains of microspheres based on the polarization properties of the coupled optical beam that leads to the formation of periodically focused modes (PFMs) with radial polarization. I used the concept of PFMs and designed, fabricated, and characterized a laser scalpel composed of arrays of sapphire/ruby microspheres placed inside a hollow waveguide coupled to an Er:YAG laser source for ultra-precise laser tissue-surgery. My Ph.D. dissertation was published with open access for all readers who are interested in my work.04/2013, Degree: Ph.D.
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ABSTRACT: We present a soft method for the fabrication of well controlled plasmonic nanodots on large ITO substrate for organic solar cells. Masks of nanopatterned aluminum oxide are elaborated and deposited on ITO substrates before metal deposition. After removal of the mask, well organized and isolated metallic nanodots are observed. In this article, we focus on gold or silver nanostructures: they show a Surface Plasmon Resonance (SPR) in the visible region, an important feature for their integration in organic thin film solar cells and the final improvement of the optical properties of the cell. In addition, their near field enhancement capacity is also clearly demonstrated by surface enhanced Raman spectroscopy and FDTD method simulation. An additional advantage of this protocol is that it can be used on any kind of surface and with different metals, depending on the final application.Solar Energy Materials and Solar Cells 10/2013; 117:657-662. DOI:10.1016/j.solmat.2012.12.018 · 5.03 Impact Factor