Publications

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2014
Mendes, MJ, S. Morawiec, I. Crupi, F. Simone, and F. Priolo. "{Colloidal self-assembled nanosphere arrays for plasmon-enhanced light trapping in thin film silicon solar cells}." Energy Procedia. 2014. Abstract
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Araújo, A., C. Caro, MJ Mendes, D. Nunes, E. Fortunato, R. Franco, H. Águas, and R. Martins. "{Highly efficient nanoplasmonic SERS on cardboard packaging substrates}." Nanotechnology. 25 (2014). Abstract

© 2014 IOP Publishing Ltd. This work reports on highly efficient surface enhanced Raman spectroscopy (SERS) constructed on low-cost, fully recyclable and highly reproducible cardboard plates, which are commonly used as disposable packaging material. The active optical component is based on plasmonic silver nanoparticle structures separated from the metal surface of the cardboard by a nanoscale dielectric gap. The SERS response of the silver (Ag) nanoparticles of various shapes and sizes were systematically investigated, and a Raman enhancement factor higher than 106for rhodamine 6G detection was achieved. The spectral matching of the plasmonic resonance for maximum Raman enhancement with the optimal local electric field enhancement produced by 60 nm-sized Ag NPs predicted by the electromagnetic simulations reinforces the outstanding results achieved. Furthermore, the nanoplasmonic SERS substrate exhibited high reproducibility and stability. The SERS signals showed that the intensity variation was less than 5{%}, and the SERS performance could be maintained for up to at least 6 months.

Morawiec, S., MJ Mendes, SA Filonovich, T. Mateus, S. Mirabella, H. Águas, I. Ferreira, F. Simone, E. Fortunato, R. Martins, F. Priolo, and I. Crupi. "{Photocurrent enhancement in thin a-Si: H solar cells via plasmonic light trapping}." Optics InfoBase Conference Papers. 2014. Abstract
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2013
Morawiec, Seweryn, Manuel J. Mendes, Salvatore Mirabella, Francesca Simone, Francesco Priolo, and Isodiana Crupi. "{Self-assembled silver nanoparticles for plasmon-enhanced solar cell back reflectors: correlation between structural and optical properties}." Nanotechnology. 24 (2013): 265601. AbstractWebsite

The spectra of localized surface plasmon resonances (LSPRs) in self-assembled silver nanoparticles (NPs), prepared by solid-state dewetting of thin films, are discussed in terms of their structural properties. We summarize the dependences of size and shape of NPs on the fabrication conditions with a proposed structural-phase diagram. It was found that the surface coverage distribution and the mean surface coverage (SC) size were the most appropriate statistical parameters to describe the correlation between the morphology and the optical properties of the nanostructures. The results are interpreted with theoretical predictions based on Mie theory. The broadband scattering efficiency of LSPRs in the nanostructures is discussed towards application as plasmon-enhanced back reflectors in thin-film solar cells.

Mendes, Manuel J., Estela Hernández, Esther López, Pablo García-Linares, Iñigo Ramiro, Irene Artacho, Elisa Antolín, Ignacio Tobías, Antonio Martí, and Antonio Luque. "{Self-organized colloidal quantum dots and metal nanoparticles for plasmon-enhanced intermediate-band solar cells}." Nanotechnology. 24 (2013): 345402. AbstractWebsite

A colloidal deposition technique is presented to construct long-range ordered hybrid arrays of self-assembled quantum dots and metal nanoparticles. Quantum dots are promising for novel opto-electronic devices but, in most cases, their optical transitions of interest lack sufficient light absorption to provide a significant impact in their implementation. A potential solution is to couple the dots with localized plasmons in metal nanoparticles. The extreme confinement of light in the near-field produced by the nanoparticles can potentially boost the absorption in the quantum dots by up to two orders of magnitude. In this work, light extinction measurements are employed to probe the plasmon resonance of spherical gold nanoparticles in lead sulfide colloidal quantum dots and amorphous silicon thin-films. Mie theory computations are used to analyze the experimental results and determine the absorption enhancement that can be generated by the highly intense near-field produced in the vicinity of the gold nanoparticles at their surface plasmon resonance. The results presented here are of interest for the development of plasmon-enhanced colloidal nanostructured photovoltaic materials, such as colloidal quantum dot intermediate-band solar cells.

Martí, Antonio, Elisa Antolín, Pablo {García Linares}, Iñigo Ramiro, Irene Artacho, Esther López, Estela Hernández, Manuel J. Mendes, Alex Mellor, Ignacio Tobías, David {Fuertes Marrón}, Cesar Tablero, Ana B. Cristóbal, Christopher G. Bailey, Maria Gonzalez, Michael Yakes, Mathew P. Lumb, Robert Walters, and Antonio Luque. "{Six not-so-easy pieces in intermediate band solar cell research}." Journal of Photonics for Energy. 3 (2013): 31299. AbstractWebsite

Abstract.  The concept of intermediate band solar cell (IBSC) is, apparently, simple to grasp. However, since the idea was proposed, our understanding has improved and some concepts can now be explained more clearly than when the concept was initially introduced. Clarifying these concepts is important, even if they are well known for the advanced researcher, so that research efforts can be driven in the right direction from the start. The six pieces of this work are: Does a miniband need to be formed when the IBSC is implemented with quantum dots? What are the problems for each of the main practical approaches that exist today? What are the simplest experimental techniques to demonstrate whether an IBSC is working as such or not? What is the issue with the absorption coefficient overlap and the Mott's transition? What would the best system be, if any?

2011
Mendes, Manuel J., Ignacio Tobías, Antonio Martí, and Antonio Luque. "{Light concentration in the near-field of dielectric spheroidal particles with mesoscopic sizes}." Optics Express. 19 (2011): 16207-16222. AbstractWebsite
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Mendes, MJ, I. Tobías, A. Martí, and A. Luque. "{Near-field light focusing by wavelenght-sized dielectric spheroids for photovoltaic applications}." Optical Nanostructures and Advanced Materials for Photovoltaics - Concepts of Light Trapping and Photon Transport. Ed. Technical O. S. A. Digest. Vol. Renewable. Austin, Texas (USA): Optical Society of America, 2011. JThC. Abstract
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Mellor, A., I. Tobías, A. Martí, MJ Mendes, and A. Luque. "{Upper limits to absorption enhancement in thick solar cells using diffraction gratings}." Progress in Photovoltaics: Research and Applications. 19 (2011): 676-687. AbstractWebsite

The application of diffraction gratings to solar cells is a promising approach to superseding the light trapping limits of conventional Lambertian structures. In this paper a mathematical formalism is derived for calculating the absorption that can be expected in a solar cell equipped with a diffraction grating, which can be applied to any lattice geometry and grating profile. Furthermore, the formalism is used to calculate the upper limit of total absorption that can theoretically be achieved using a diffraction grating. The derived formalism and limits are valid when the solar cell thickness is greater than the coherence length of the illuminating solar spectrum. Comparison is made to the upper limit achievable using an angularly selective Rugate filter, which is also calculated. Both limits are found to be considerably higher than the Lambertian limit within the range of sunlight concentration factors practically employed in photovoltaic systems (1–1000×). The upper limit of absorption using the diffraction grating is shown to be equal to the thermodynamic limit for all absorbances and concentration factors. The limit for the Rugate filter is generally lower, but tends to the thermodynamic limit for lower cell absorbances. Copyright © 2011 John Wiley {&} Sons, Ltd.

2010
Mendes, MJ, E. Hernández, I. Tobías, A. Martí, and A. Luque. "{Embedment of metal nanoparticles in GaAs and Si for plasmonic absorption enhancement in intermediate band solar cells}." 25th European Photovoltaic Solar Energy Conference and Exhibition - 5th World Conference on Photovoltaic Energy Conversion. Valencia, Spain 2010. 218-222. Abstract
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Mendes, Manuel J., Ignacio Tobías, Antonio Martí, and Antonio Luque. "{Near-field scattering by dielectric spheroidal particles with sizes on the order of the illuminating wavelength}." J. Opt. Soc. Am. B. 27 (2010): 1221-1231. AbstractWebsite
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2009
Martí, A., E. Antolín, P. G. Linares, E. Cánovas, D. {Fuertes Marrón}, C. Tablero, M. Mendes, A. Mellor, I. Tobías, M. Y. Levy, E. Hernández, A. Luque, C. D. Farmer, C. R. Stanley, R. P. Campion, J. L. Hall, S. V. Novikov, C. T. Foxon, R. Scheer, B. Marsen, H. W. Schock, M. Picault, and C. Chaix. "{IBPOWER: Intermediate band materials and solar cells for photovoltaics with high efficiency and reduced cost}." Conference Record of the IEEE Photovoltaic Specialists Conference. 2009. Abstract
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Mendes, MJ, A. Luque, I. Tobias, and A. Marti. "{Plasmonic light enhancement in the near-field of metallic nanospheroids for application in intermediate band solar cells}." Applied Physics Letters. 95 (2009): 71105. Abstract

In order to enhance infrared light absorption in sub-bandgap transitions in an intermediate band solar cell, the scattered near-field potential from uncoated and coated metallic nanoparticles with a spheroidal shape is calculated with the electrostatic model. The absorption enhancement produced at the surface plasmon frequency of the nanoparticles can be of several orders of magnitude in some cases.

2008
Mendes, Manuel J., Howard K. Schmidt, and Matteo Pasquali. "{Brownian dynamics simulations of single-wall carbon nanotube separation by type using dielectrophoresis}." Journal of Physical Chemistry B (2008). AbstractWebsite
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Luque, A., A. Marti, MJ Mendes, and I. Tobias. "{Light absorption in the near field around surface plasmon polaritons}." Journal of Applied Physics. 104 (2008): 8. Abstract

A semiclassical method is developed to calculate the energy absorption of an electronic system located in the near field of a metal nanoparticle sustaining surface plasmons. The results are found to be similar to those of photon absorption from ordinary transversal radiation. However, they are affected by a geometrical factor that can increase the absorption by several orders of magnitude. As example, we investigate ellipsoidal-shaped metal nanoparticles which, under favorable conditions, may provide near field aborption enhancements almost as large as 10(4), and in many cases above 10. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3014035]

2006
Guedes, A., MJ Mendes, P. P. Freitas, and J. L. Martins. "{Study of synthetic ferrimagnet-synthetic antiferromagnet structures for magnetic sensor application}." Journal of Applied Physics (2006). AbstractWebsite
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