@article {Panigrahi20241930, title = {MXene-Enhanced Nanoscale Photoconduction in Perovskite Solar Cells Revealed by Conductive Atomic Force Microscopy}, journal = {ACS Applied Materials and Interfaces}, volume = {16}, number = {1}, year = {2024}, note = {

cited By 4

}, pages = {1930-1940}, abstract = {n/a}, doi = {10.1021/acsami.3c16245}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85181118270\&doi=10.1021\%2facsami.3c16245\&partnerID=40\&md5=d3d7204c74657256fcf5ec18a562e91c}, author = {Panigrahi, S. and Jana, S. and Calmeiro, T and Fortunato, E. and Mendes, MJ and Martins, R.} } @article {Haque2024, title = {Photon shifting and trapping in perovskite solar cells for improved efficiency and stability}, journal = {Light: Science and Applications}, volume = {13}, number = {1}, year = {2024}, note = {

cited By 0

}, abstract = {n/a}, doi = {10.1038/s41377-024-01559-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85203301279\&doi=10.1038\%2fs41377-024-01559-2\&partnerID=40\&md5=932a291919743f257abcbb16aa4eb83b}, author = {Haque, S. and Alexandre, M. and Vicente, A.T. and Li, K. and Schuster, C.S. and Yang, S. and {\'A}guas, H. and Martins, R. and Ferreira, R.A.S. and Mendes, MJ} } @article {Akalin2024, title = {Physically-Deposited Hole Transporters in Perovskite PV: NiOx Improved with Li/Mg Doping}, journal = {Advanced Materials Technologies}, volume = {9}, number = {7}, year = {2024}, note = {

cited By 3

}, abstract = {n/a}, doi = {10.1002/admt.202301760}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85185139996\&doi=10.1002\%2fadmt.202301760\&partnerID=40\&md5=332af4e3fa4cf8e8a3f888baa7194762}, author = {Akalin, S.A. and Erol, M. and Uzunbayir, B. and Oguzlar, S. and Yildirim, S. and Gokdemir Choi, F.P. and Gunes, S. and Yilmazer Menda, U.D. and Mendes, MJ} } @article {Alexandre2024, title = {SCATMM: Easy-to-Use Graphical User Interface for Light Propagation in Arbitrary Multilayers}, journal = {Journal of Open Research Software}, volume = {12}, number = {1}, year = {2024}, note = {

cited By 0

}, abstract = {n/a}, doi = {10.5334/jors.511}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85204445598\&doi=10.5334\%2fjors.511\&partnerID=40\&md5=227d9e260f9ddb866bcddb409ca12b9e}, author = {Alexandre, M. and Santos, I.M. and Martins, R. and Mendes, MJ} } @article {S.Fernandes2024, title = {Solar fuels design: Porous cathodes modeling for electrochemical carbon dioxide reduction in aqueous electrolytes}, journal = {Heliyon}, volume = {10}, number = {4}, year = {2024}, note = {

cited By 0

}, abstract = {n/a}, doi = {10.1016/j.heliyon.2024.e26442}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85186220209\&doi=10.1016\%2fj.heliyon.2024.e26442\&partnerID=40\&md5=f46643dab92be1d3b22329b3dc0d9e15}, author = {S. Fernandes, I. and D. Antunes and Martins, R. and Mendes, MJ and Reis-Machado, A. S.} } @article {Marques202412397, title = {Surface modification of halide perovskite using EDTA-complexed SnO2 as electron transport layer in high performance solar cells}, journal = {RSC Advances}, volume = {14}, number = {18}, year = {2024}, note = {

cited By 1

}, pages = {12397-12406}, abstract = {n/a}, doi = {10.1039/d3ra08900b}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85190717482\&doi=10.1039\%2fd3ra08900b\&partnerID=40\&md5=7c45f90d3a0e433696c6345bc688ecb9}, author = {Marques, N. and Jana, S. and Mendes, MJ and {\'A}guas, H. and Martins, R. and Panigrahi, S.} } @article {Akalin2024, title = {Ultra-flexible, high-performing NAN transparent electrodes for bendable optoelectronic applications}, journal = {Journal of Materials Science: Materials in Electronics}, volume = {35}, number = {25}, year = {2024}, note = {

cited By 0

}, abstract = {n/a}, doi = {10.1007/s10854-024-13442-2}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85203271747\&doi=10.1007\%2fs10854-024-13442-2\&partnerID=40\&md5=7f66162d56dd903847fe67defe7edc3e}, author = {Akalin, S.A. and Mateus, T and Ribeiro, G. and Deuermeier, J and Calmeiro, T and {\'A}guas, H. and Martins, R. and Vicente, A.T. and Mendes, MJ and Yilmazer Menda, U.D.} } @article {Alexandre2024, title = {Understanding the Potential of Light Absorption in Dots-in-Host Semiconductors}, journal = {ACS Photonics}, year = {2024}, note = {

cited By 0

}, abstract = {n/a}, doi = {10.1021/acsphotonics.4c00760}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85199568570\&doi=10.1021\%2facsphotonics.4c00760\&partnerID=40\&md5=4ef5caeeba0b7e37dead9db7da78ea62}, author = {Alexandre, M. and {\'A}guas, H. and Fortunato, E. and Martins, R. and Mendes, MJ} } @article {Santos2023, title = {Optically-Boosted Planar IBC Solar Cells with Electrically-Harmless Photonic Nanocoatings}, journal = {Advanced Optical Materials}, volume = {11}, number = {15}, year = {2023}, note = {

cited By 1

}, abstract = {n/a}, doi = {10.1002/adom.202300276}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85154548376\&doi=10.1002\%2fadom.202300276\&partnerID=40\&md5=08356a36b331a795ca9493e12f0ed7a3}, author = {Santos, I.M. and Alexandre, M. and Mihailetchi, V.D. and Silva, J.A. and Mateus, T and A. Mouquinho and Boane, J. and Vicente, A.T. and Nunes, D. and Menda, U.D. and {\'A}guas, H. and Fortunato, E. and Martins, R. and Mendes, MJ} } @article {Pinheiro2023, title = {Parylene-Sealed Perovskite Nanocrystals Down-Shifting Layer for Luminescent Spectral Matching in Thin Film Photovoltaics}, journal = {Nanomaterials}, volume = {13}, number = {1}, year = {2023}, note = {

cited By 0

}, abstract = {n/a}, doi = {10.3390/nano13010210}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85145838802\&doi=10.3390\%2fnano13010210\&partnerID=40\&md5=deff68bc0281c7462ce71acf83c85b4e}, author = {Pinheiro, A. and Ruivo, A. and Rocha, J. and Ferro, M. and Pinto, JV and Deuermeier, J and Mateus, T and Santa, A. and Mendes, MJ and Martins, R. and Gago, S. and Laia, C A T and {\'A}guas, H.} } @article {Ribeiro2023, title = {Sub-Bandgap Sensitization of Perovskite Semiconductors via Colloidal Quantum Dots Incorporation}, journal = {Nanomaterials}, volume = {13}, number = {17}, year = {2023}, note = {

cited By 0

}, abstract = {n/a}, doi = {10.3390/nano13172447}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85170250858\&doi=10.3390\%2fnano13172447\&partnerID=40\&md5=f01d08a2842d894a74839f1e631a468f}, author = {Ribeiro, G. and Ferreira, G. and Menda, U.D. and Alexandre, M. and Brites, M. J. and Barreiros, M.A. and Jana, S. and {\'A}guas, H. and Martins, R. and Fernandes, P.A. and Salom{\'e}, P. and Mendes, MJ} } @article {Menda20233647, title = {Thermal-Carrier-Escape Mitigation in a Quantum-Dot-In-Perovskite Intermediate Band Solar Cell via Bandgap Engineering}, journal = {ACS Photonics}, volume = {10}, number = {10}, year = {2023}, note = {

cited By 0

}, pages = {3647-3655}, abstract = {n/a}, doi = {10.1021/acsphotonics.3c00738}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85174815018\&doi=10.1021\%2facsphotonics.3c00738\&partnerID=40\&md5=9f3cd21f4205ae486fe1df6b720ac2e4}, author = {Menda, U.D. and Ribeiro, G. and Deuermeier, J and L{\'o}pez, E. and Nunes, D. and Jana, S. and Artacho, I and Martins, R. and Mora-Ser{\'o}, I. and Mendes, MJ and Ramiro, I.} } @article {nano12193268, title = {Copper-Arsenic-Sulfide Thin-Films from Local Raw Materials Deposited via RF Co-Sputtering for Photovoltaics}, journal = {Nanomaterials}, volume = {12}, number = {19}, year = {2022}, note = {n/a}, abstract = {

The inexorable increase of energy demand and the efficiency bottleneck of monocrystalline silicon solar cell technology is promoting the research and development of alternative photovoltaic materials. Copper-arsenic-sulfide (CAS) compounds are still rather unexplored in the literature, yet they have been regarded as promising candidates for use as p-type absorber in solar cells, owing to their broad raw material availability, suitable bandgap and high absorption coefficient. Here, a comprehensive study is presented on the structural and optoelectronic properties of CAS thin-films deposited via radio-frequency magnetron co-sputtering, using a commercial Cu target together with a Cu-As-S target with material obtained from local resources, specifically from mines in the Portuguese region of the Iberian Pyrite Belt. Raman and X-ray diffraction analysis confirm that the use of two targets results in films with pronounced stoichiometry gradients, suggesting a transition from amorphous CAS compounds to crystalline djurleite (Cu31S16), with the increasing proximity to the Cu target. Resistivity values from 4.7 m\&$\#$8486;\·cm to 17.4 \&$\#$8486;\·cm are obtained, being the lowest resistive films, those with pronounced sub-bandgap free-carrier absorption. The bandgap values range from 2.20 to 2.65 eV, indicating promising application as wide-bandgap semiconductors in third-generation (e.g., multi-junction) photovoltaic devices.

}, issn = {2079-4991}, doi = {10.3390/nano12193268}, url = {https://www.mdpi.com/2079-4991/12/19/3268}, author = {Centeno, Pedro and Alexandre, Miguel and Neves, Filipe and Fortunato, Elvira and Martins, Rodrigo and {\'A}guas, Hugo and Mendes, Manuel J} } @article {Panigrahi202219367, title = {Observation of Grain Boundary Passivation and Charge Distribution in Perovskite Films Improved with Anti-solvent Treatment}, journal = {Journal of Physical Chemistry C}, volume = {126}, number = {45}, year = {2022}, note = {

cited By 2

}, pages = {19367-19375}, abstract = {n/a}, doi = {10.1021/acs.jpcc.2c05055}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85141971303\&doi=10.1021\%2facs.jpcc.2c05055\&partnerID=40\&md5=41e4a21b1379eb57b65b3248b704bae9}, author = {Panigrahi, S. and Calmeiro, T and Mendes, MJ and {\'A}guas, H. and Fortunato, E. and Martins, R.} } @article {doi:10.1021/acsphotonics.2c00446, title = {Photonic-Structured Perovskite Solar Cells: Detailed Optoelectronic Analysis}, journal = {ACS Photonics}, volume = {9}, number = {7}, year = {2022}, note = {n/a}, pages = {2408-2421}, abstract = {n/a}, doi = {10.1021/acsphotonics.2c00446}, url = {https://doi.org/10.1021/acsphotonics.2c00446}, author = {Haque, Sirazul and Alexandre, Miguel and Baretzky, Clemens and Rossi, Daniele and De Rossi, Francesca and Vicente, Ant{\'o}nio T and Brunetti, Francesca and {\'A}guas, Hugo and Ferreira, Rute A. S. and Fortunato, Elvira and Auf der Maur, Matthias and W{\"u}rfel, Uli and Martins, Rodrigo and Mendes, Manuel J} } @article {15862, title = {Photonic Strategies for Photovoltaics: New Advances Beyond Optics}, journal = {Modern Environmental Science and Engineering}, volume = {7}, number = {7}, year = {2021}, note = {n/a}, month = {jul}, pages = {642{\textendash}652}, abstract = {n/a}, url = {http://academicstar.us/UploadFile/Picture/2022-1/2022117123040516.pdf} } @article {Oliveira2021, title = {Colloidal lithography for photovoltaics: An attractive route for light management}, journal = {Nanomaterials}, volume = {11}, number = {7}, year = {2021}, note = {

cited By 1

}, abstract = {n/a}, doi = {10.3390/nano11071665}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85108432450\&doi=10.3390\%2fnano11071665\&partnerID=40\&md5=b9a0c7fae6c5524f39189545124e730d}, author = {Oliveira, R.D. and A. Mouquinho and Centeno, P. and Alexandre, M. and Haque, S. and Martins, R. and Fortunato, E. and {\'A}guas, H. and Mendes, MJ} } @article {Grey2021, title = {Combining Soft with Hard Condensed Matter for Circular Polarized Light Sensing and Logic Operations}, journal = {Advanced Optical Materials}, volume = {9}, number = {6}, year = {2021}, note = {

cited By 1

}, abstract = {n/a}, doi = {10.1002/adom.202001731}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85099320273\&doi=10.1002\%2fadom.202001731\&partnerID=40\&md5=465832b5bf1aed4f2034bf5e276bd57d}, author = {Grey, P and Chapa, M. and Alexandre, M. and Mateus, T and Fortunato, E. and Martins, R. and Mendes, MJ and Pereira, L.} } @article {Alishah2021149, title = {Effect of Bathocuproine Concentration on the Photovoltaic Performance of NiOx-Based Perovskite Solar Cells}, journal = {Journal of the Mexican Chemical Society}, volume = {65}, number = {2}, year = {2021}, note = {

cited By 3

}, pages = {149-160}, abstract = {n/a}, doi = {10.29356/jmcs.v65i2.1461}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85104148141\&doi=10.29356\%2fjmcs.v65i2.1461\&partnerID=40\&md5=7b81f4e853d9d1505b2c7568df39bb80}, author = {Alishah, H.M. and Choi, F.P.G. and Menda, U.D. and Kahveci, C. and Rodop, M.C. and Mendes, MJ and Gunes, S.} } @article {Menda20216344, title = {High-performance wide bandgap perovskite solar cells fabricated in ambient high-humidity conditions}, journal = {Materials Advances}, volume = {2}, number = {19}, year = {2021}, note = {

cited By 0

}, pages = {6344-6355}, abstract = {n/a}, doi = {10.1039/d1ma00432h}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85116614626\&doi=10.1039\%2fd1ma00432h\&partnerID=40\&md5=9a481b5550fa8762609e6c7202aebc51}, author = {Menda, U.D. and Ribeiro, G. and Nunes, D. and Calmeiro, T and {\'A}guas, H. and Fortunato, E. and Martins, R. and Mendes, MJ} } @article {Alexandre2021, title = {Light management with quantum nanostructured dots-in-host semiconductors}, journal = {Light: Science and Applications}, volume = {10}, number = {1}, year = {2021}, note = {

cited By 0

}, abstract = {n/a}, doi = {10.1038/s41377-021-00671-x}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85119093617\&doi=10.1038\%2fs41377-021-00671-x\&partnerID=40\&md5=4fb8f48f6c1e918acd859906e84aa26c}, author = {Alexandre, M. and {\'A}guas, H. and Fortunato, E. and Martins, R. and Mendes, MJ} } @article {micro1020016, title = {Soft-Microstructured Transparent Electrodes for Photonic-Enhanced Flexible Solar Cells}, journal = {Micro}, volume = {1}, number = {2}, year = {2021}, note = {n/a}, pages = {215{\textendash}227}, abstract = {

Microstructured transparent conductive oxides (TCOs) have shown great potential as photonic electrodes in photovoltaic (PV) applications, providing both optical and electrical improvements in the solar cells{\textquoteright} performance due to: (1) strong light trapping effects that enhance broadband light absorption in PV material and (2) the reduced sheet resistance of the front illuminated contact. This work developed a method for the fabrication and optimization of wavelength-sized indium zinc oxide (IZO) microstructures, which were soft-patterned on flexible indium tin oxide (ITO)-coated poly(ethylene terephthalate) (PET) substrates via a simple, low-cost, versatile, and highly scalable colloidal lithography process. Using this method, the ITO-coated PET substrates patterned with IZO micro-meshes provided improved transparent electrodes endowed with strong light interaction effects{\textemdash}namely, a pronounced light scattering performance (diffuse transmittance up to ~50\%). In addition, the photonic-structured IZO mesh allowed a higher volume of TCO material in the electrode while maintaining the desired transparency, which led to a sheet resistance reduction (by ~30\%), thereby providing further electrical benefits due to the improvement of the contact conductance. The results reported herein pave the way for a new class of photonic transparent electrodes endowed with mechanical flexibility that offer strong potential not only as advanced front contacts for thin-film bendable solar cells but also for a much broader range of optoelectronic applications.

}, issn = {2673-8023}, doi = {10.3390/micro1020016}, url = {https://www.mdpi.com/2673-8023/1/2/16}, author = {Boane, Jenny L. N. and Centeno, Pedro and Mouquinho, Ana and Alexandre, Miguel and Calmeiro, Tom{\'a}s and Fortunato, Elvira and Martins, Rodrigo and Mendes, Manuel J and {\'A}guas, Hugo} } @article {Haque2020, title = {Design of wave-optical structured substrates for ultra-thin perovskite solar cells}, journal = {Applied Materials Today}, volume = {20}, year = {2020}, note = {

cited By 1

}, abstract = {n/a}, doi = {10.1016/j.apmt.2020.100720}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086499623\&doi=10.1016\%2fj.apmt.2020.100720\&partnerID=40\&md5=a82d8bed27ee63d55e1a2198e90c26ce}, author = {Haque, S. and Alexandre, M. and Mendes, MJ and {\'A}guas, H. and Fortunato, E. and Martins, R.} } @article {Li20201377, title = {Light trapping in solar cells: Simple design rules to maximize absorption}, journal = {Optica}, volume = {7}, number = {10}, year = {2020}, note = {

cited By 18

}, pages = {1377-1384}, abstract = {n/a}, doi = {10.1364/OPTICA.394885}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092451492\&doi=10.1364\%2fOPTICA.394885\&partnerID=40\&md5=97fd6a1269dd17d782cf49abea9ec28d}, author = {Li, K. and Haque, S. and A. Martins and Fortunato, E. and Martins, R. and Mendes, MJ and Schuster, C.S.} } @article {Sanchez-Sobrado202092, title = {Photonic-structured TCO front contacts yielding optical and electrically enhanced thin-film solar cells}, journal = {Solar Energy}, volume = {196}, year = {2020}, note = {

cited By 1

}, pages = {92-98}, abstract = {n/a}, doi = {10.1016/j.solener.2019.11.051}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076254591\&doi=10.1016\%2fj.solener.2019.11.051\&partnerID=40\&md5=61f0df2d9c723cf5601f9b32c5210b5a}, author = {Sanchez-Sobrado, O. and Mendes, MJ and Mateus, T and Costa, J. and Nunes, D. and Aguas, H. and Fortunato, E. and Martins, R.} } @article {Centeno2020, title = {Self-Cleaned Photonic-Enhanced Solar Cells with Nanostructured Parylene-C}, journal = {Advanced Materials Interfaces}, volume = {7}, number = {15}, year = {2020}, note = {

cited By 0

}, abstract = {n/a}, doi = {10.1002/admi.202000264}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083985083\&doi=10.1002\%2fadmi.202000264\&partnerID=40\&md5=e103c7e287140b63746a687bb1cb8270}, author = {Centeno, P. and Alexandre, M.F. and Chapa, M. and Pinto, JV and Deuermeier, J and Mateus, T and Fortunato, E. and Martins, R. and {\'A}guas, H. and Mendes, MJ} } @article {Louren{\c c}o2020, title = {Sunlight-driven CO2-to-fuel conversion: Exploring thermal and electrical coupling between photovoltaic and electrochemical systems for optimum solar-methane production}, journal = {Materials Today Energy}, volume = {17}, year = {2020}, note = {

cited By 1

}, abstract = {n/a}, doi = {10.1016/j.mtener.2020.100425}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086501385\&doi=10.1016\%2fj.mtener.2020.100425\&partnerID=40\&md5=e457cef3038ac6fc30ff0d3c0ca65dd2}, author = {Louren{\c c}o, A.C. and Reis-Machado, A. S. and Fortunato, E. and Martins, R. and Mendes, MJ} } @inbook {Mendes2020, title = {{Wave-optical front structures on silicon and perovskite thin-film solar cells}}, booktitle = {Solar Cells and Light Management}, year = {2020}, note = {n/a}, pages = {315{\textendash}354}, publisher = {Elsevier}, organization = {Elsevier}, abstract = {n/a}, doi = {10.1016/B978-0-08-102762-2.00009-4}, url = {https://linkinghub.elsevier.com/retrieve/pii/B9780081027622000094}, author = {Mendes, Manuel J and Sanchez-Sobrado, Olalla and Haque, Sirazul and Mateus, Tiago and {\'A}guas, Hugo and Fortunato, Elvira and Martins, Rodrigo} } @booklet {Morawiec2019, title = {{Plasmonic nanostructures for light trapping in thin-film solar cells}}, journal = {Materials Science in Semiconductor Processing}, volume = {92}, year = {2019}, note = {n/a}, month = {mar}, pages = {10{\textendash}18}, publisher = {Elsevier Ltd}, abstract = {

The optical properties of localized surface plasmon resonances (LSPR) sustained by self-assembled silver nanoparticles are of great interest for enhancing light trapping in thin film photovoltaics. First, we report on a systematic investigation of the structural and the optical properties of silver nanostructures fabricated by a solid-state dewetting process on various substrates. Our study allows to identify fabrication conditions in which circular, uniformly spaced nanoparticles are obtainable. The optimized NPs are then integrated into plasmonic back reflector (PBR) structures. Second, we demonstrate a novel procedure, involving a combination of opto-electronic spectroscopic techniques, allowing for the quantification of useful and parasitic absorption in thin photovoltaic absorber deposited on top of the PBR. We achieve a significant broadband useful absorption enhancement of 90{\%} for 0.9 {\textmu}m thick $μ$c-Si:H film and demonstrate that optical losses due to plasmonic scattering are insignificant below 730 nm. Finally, we present a successful implementation of a plasmonic light trapping scheme in a thin film a-Si:H solar cell. The quantum efficiency spectra of the devices show a pronounced broadband enhancement resulting in remarkably high short circuit current densities (Jsc).

}, keywords = {Localized surface plasmon resonance, nanoparticles, Photovoltaics, Plasmonic-enhanced light trapping, Self-assembly, Subwavelength nanostructures, Thin film solar cells}, issn = {13698001}, doi = {10.1016/j.mssp.2018.04.035}, author = {Morawiec, S. and Mendes, MJ and Priolo, F. and Crupi, I.} } @article {Brites2019, title = {{Ultrafast Low-Temperature Crystallization of Solar Cell Graded Formamidinium-Cesium Mixed-Cation Lead Mixed-Halide Perovskites Using a Reproducible Microwave-Based Process}}, journal = {ACS Applied Energy Materials}, volume = {2}, number = {3}, year = {2019}, note = {n/a}, month = {mar}, pages = {1844{\textendash}1853}, abstract = {n/a}, issn = {2574-0962}, doi = {10.1021/acsaem.8b02005}, url = {https://pubs.acs.org/doi/10.1021/acsaem.8b02005}, author = {Brites, Maria Jo{\~a}o and Barreiros, Maria Alexandra and Corregidor, Victoria and Alves, Luis C. and {V. Pinto}, Joana and Mendes, Manuel J and Fortunato, Elvira and Martins, Rodrigo and Mascarenhas, Jo{\~a}o} } @article {Chapa2019, title = {{All-Thin-Film Perovskite/C-Si Four-Terminal Tandems: Interlayer and Intermediate Contacts Optimization}}, journal = {ACS Applied Energy Materials}, volume = {2}, number = {6}, year = {2019}, note = {n/a}, month = {jun}, pages = {3979{\textendash}3985}, publisher = {American Chemical Society}, abstract = {

Combined perovskite/crystalline-silicon four-terminal tandem solar cells promise {\textgreater}30{\%} efficiencies. Here we propose all-thin-film double-junction architectures where high-bandgap perovskite top cells are coupled to ultrathin c-Si bottom cells enhanced with light trapping. A complete optoelectronic model of the devices was developed and applied to determine the optimal intermediate layers, which are paramount to maximize the cells{\textquoteright} photocurrent. It was ascertained that by replacing the transparent conductive oxides by grid-based metallic contacts in the intermediate positions, the parasitic absorption is lowered by 30{\%}. Overall, a 29.2{\%} efficiency is determined for \~{}2 um thick tandems composed of the optimized interlayers and improved with Lambertian light trapping.

}, keywords = {four-terminal double-junction solar cells, light trapping, perovskite/Si tandems, Photovoltaics, transparent contacts}, issn = {25740962}, doi = {10.1021/acsaem.9b00354}, author = {Chapa, Manuel and Alexandre, Miguel F. and Mendes, Manuel J and {\'A}guas, Hugo and Fortunato, Elvira and Martins, Rodrigo} } @article {Vieira2019, title = {{Prediction of sunlight-driven CO2 conversion: Producing methane from photovoltaics, and full system design for single-house application}}, journal = {Materials Today Energy}, volume = {14}, year = {2019}, note = {n/a}, month = {dec}, publisher = {Elsevier Ltd}, abstract = {

CO2 capture and utilization (CCU) technologies are being immensely researched as means to close the anthropogenic carbon cycle. One approach known as artificial photosynthesis uses solar energy from photovoltaics (PV), carbon dioxide and water to generate hydrocarbon fuels, being methane (CH4) a preferential target due to the already in place infrastructures for its storage, distribution and consumption. Here, a model is developed to simulate a direct (1-step) solar methane production approach, which is studied in two scenarios: first, we compare it against a more conventional 2-step methane production route, and second, we apply it to address the energetic needs of concept buildings with usual space and domestic hot water heating requirements. The analysed 2-step process consists in the PV-powered synthesis of an intermediate fuel {\textendash} syngas {\textendash} followed by its conversion to CH4 via a Fischer{\textendash}Tropsch (methanation) process. It was found that the 1-step route could be adequate to a domestic, small scale use, potentially providing energy for a single-family house, whilst the 2-step can be used in both small and large scale applications, from domestic to industrial uses. In terms of overall solar-to-CH4 energy efficiency, the 2-step method reaches 13.26{\%} against the 9.18{\%} reached by the 1-step method. Next, the application of the direct solar methane technology is analysed for domestic buildings, in different European locations, equipped with a combination of solar thermal collectors (STCs) and PV panels, in which the heating needs that cannot be fulfilled by the STCs are satisfied by the combustion of methane synthesized by the PV-powered electrolyzers. Various combinations of situations for a whole year were studied and it was found that this auxiliary system can produce, per m2 of PV area, in the worst case scenario 23.6 g/day (0.328 kWh/day) of methane in Stockholm, and in the best case scenario 47.4 g/day (0.658 kWh/day) in Lisbon.

}, keywords = {Artificial photosynthesis, Building-integrated solar methane, CO2 electrolysis, Fisher{\textendash}Tropsch synthesis, Photovoltaic-powered electrochemical conversion}, issn = {24686069}, doi = {10.1016/j.mtener.2019.07.004}, author = {Vieira, F. and Sarmento, B. and Reis-Machado, A. S. and Fac{\~a}o, J. and Carvalho, M. J. and Mendes, MJ and Fortunato, E. and Martins, R.} } @article {Torrisi2019, title = {{Colloidal-structured metallic micro-grids: High performance transparent electrodes in the red and infrared range}}, journal = {Solar Energy Materials and Solar Cells}, volume = {197}, year = {2019}, note = {n/a}, month = {aug}, pages = {7{\textendash}12}, publisher = {Elsevier B.V.}, abstract = {

One of the most promising approaches to produce industrial-compatible Transparent Conducting Materials (TCMs) with excellent characteristics is the fabrication of TCO/metal/TCO multilayers. In this article, we report on the electro-optical properties of a novel high-performing TCO/metal/TCO structure in which the intra-layer is a micro-structured metallic grid instead of a continuous thin film. The grid is obtained by evaporation of Ag through a mask of polystyrene colloidal micro-spheres deposited by the Langmuir-Blodgett method and partially dry-etched in plasma. IZO/Ag grid/IZO structures with different thicknesses and mesh dimensions have been fabricated, exhibiting excellent electrical characteristics (sheet resistance below 10 ${\O}mega$/□) and particularly high optical transmittance in the near-infrared spectral region as compared to planar (unstructured) TCM multilayers. Numerical simulations were also used to highlight the role of the Ag mesh parameters on the electrical properties.

}, keywords = {Ag micro-grid, IR trasmittance, Multilayer thin film, Transparent conductive electrodes}, issn = {09270248}, doi = {10.1016/j.solmat.2019.03.046}, author = {Torrisi, Giacomo and Luis, Jo{\~a}o S. and Sanchez-Sobrado, Olalla and Raciti, Rosario and Mendes, Manuel J and {\'A}guas, Hugo and Fortunato, Elvira and Martins, Rodrigo and Terrasi, Antonio} } @article {Alexandre2019, title = {{Optimum Luminescent Down-Shifting Properties for High Efficiency and Stable Perovskite Solar Cells}}, journal = {ACS Applied Energy Materials}, volume = {2}, number = {4}, year = {2019}, note = {n/a}, month = {apr}, pages = {2930{\textendash}2938}, abstract = {n/a}, issn = {2574-0962}, doi = {10.1021/acsaem.9b00271}, url = {https://pubs.acs.org/doi/10.1021/acsaem.9b00271}, author = {Alexandre, Miguel and Chapa, Manuel and Haque, Sirazul and Mendes, Manuel J and {\'A}guas, Hugo and Fortunato, Elvira and Martins, Rodrigo} } @article {Sanchez-Sobrado2019, title = {{Lightwave trapping in thin film solar cells with improved photonic-structured front contacts}}, journal = {J. Mater. Chem. C}, volume = {7}, year = {2019}, note = {n/a}, pages = {6456{\textendash}6464}, abstract = {n/a}, doi = {10.1039/C8TC06092D}, author = {Sanchez-Sobrado, Olalla and Mendes, Manuel J and Haque, Sirazul and Mateus, T and Aguas, H. and Fortunato, E. and Martins, R.} } @article {Haque2019, title = {{Photonic-structured TiO2 for high-efficiency, flexible and stable Perovskite solar cells}}, journal = {Nano Energy}, volume = {59}, year = {2019}, note = {n/a}, pages = {91{\textendash}101}, abstract = {n/a}, doi = {10.1016/j.nanoen.2019.02.023}, url = {(in press)}, author = {Haque, Sirazul and Mendes, Manuel J and Sanchez-Sobrado, O. and Aguas, H. and Fortunato, E. and Martins, R.} } @article {Araujo2018, title = {{Ultra-fast plasmonic back reflectors production for light trapping in thin Si solar cells}}, journal = {Solar Energy}, volume = {174}, year = {2018}, note = {n/a}, month = {nov}, pages = {786{\textendash}792}, publisher = {Elsevier Ltd}, abstract = {

A fast method is presented to fabricate plasmonic light trapping structures in just ten minutes ({\textgreater}5 {\texttimes} faster than the present state of art), with excellent light scattering properties. The structures are composed of silver nanoparticles (Ag NPs) deposited by thermal evaporation and self-assembled using a rapid thermal annealing (RTA) system. The effect of the RTA heating rate on the NPs production reveals to be crucial to the decrease of the annealing process. The Ag NPs are integrated in thin film silicon solar cells to form a plasmonic back reflector (PBR) that causes a diffused light reflectivity in the near-infrared (600{\textendash}1100 nm wavelength region). In this configuration the thicknesses of the AZO spacer/passivating layers between NPs and rear mirror, and between NPs and silicon layer, play critical roles in the near-field coupling of the reflected light towards the solar cell absorber, which is investigated in this work. The best spacer thicknesses were found to be 100 and 60 nm, respectively, for Ag NPs with preferential sizes of about 200 nm. The microcrystalline silicon ($μ$c-Si:H) solar cells deposited on such improved PBR demonstrate an overall 11{\%} improvement on device efficiency, corresponding to a photocurrent of 24.4 mA/cm2 and an efficiency of 6.78{\%}, against 21.79 mA/cm2 and 6.12{\%}, respectively, obtained on flat structures without NPs.

}, keywords = {Plasmonic light trapping, rapid thermal annealing, Silver nanoparticle self-assembled structures, Thin film Si solar cells}, issn = {0038092X}, doi = {10.1016/j.solener.2018.08.068}, author = {Ara{\'u}jo, Andreia and Mendes, Manuel J and Mateus, Tiago and Costa, Jo{\~a}o and Nunes, Daniela and Fortunato, Elvira and {\'A}guas, Hugo and Martins, Rodrigo} } @article {Mendes2018, title = {{Optimal-Enhanced Solar Cell Ultra-thinning with Broadband Nanophotonic Light Capture}}, journal = {iScience}, volume = {3}, year = {2018}, note = {n/a}, month = {may}, pages = {238{\textendash}254}, publisher = {Elsevier}, abstract = {

{\textless}h2{\textgreater}Summary{\textless}/h2{\textgreater}{\textless}p{\textgreater}Recent trends in photovoltaics demand ever-thin solar cells to allow deployment in consumer-oriented products requiring low-cost and mechanically flexible devices. For this, nanophotonic elements in the wave-optics regime are highly promising, as they capture and trap light in the cells{\textquoteright} absorber, enabling its thickness reduction while improving its efficiency. Here, novel wavelength-sized photonic structures were computationally optimized toward maximum broadband light absorption. Thin-film silicon cells were the test bed to determine the best performing parameters and study their optical effects. Pronounced photocurrent enhancements, up to 37{\%}, 27{\%}, and 48{\%}, respectively, in ultra-thin (100-~and 300-nm-thick) amorphous, and thin (1.5-$μ$m) crystalline silicon cells are demonstrated with honeycomb arrays of semi-spheroidal dome or void-like elements patterned on the cells{\textquoteright} front. Also importantly, key advantages in the electrical performance are anticipated, since the photonic nano/micro-nanostructures do not increase the cell roughness, therefore not contributing to recombination, which is a crucial drawback in state-of-the-art light-trapping approaches.{\textless}/p{\textgreater}

}, keywords = {Computational Method in Materials Science, Energy Materials, Optical Materials}, issn = {25890042}, doi = {10.1016/j.isci.2018.04.018}, url = {https://linkinghub.elsevier.com/retrieve/pii/S2589004218300506}, author = {Mendes, Manuel J and Haque, Sirazul and Sanchez-Sobrado, Olalla and Ara{\'u}jo, Andreia and {\'A}guas, Hugo and Fortunato, Elvira and Martins, Rodrigo} } @article {T.Vicente2018, title = {{Multifunctional cellulose-paper for light harvesting and smart sensing applications}}, journal = {Journal of Materials Chemistry C}, volume = {6}, number = {13}, year = {2018}, note = {n/a}, month = {mar}, pages = {3143{\textendash}3181}, publisher = {The Royal Society of Chemistry}, abstract = {

{\textless}p{\textgreater}Opto-electronics on/with paper is fostering a novel generation of flexible and recyclable devices for sunlight harvesting and intelligent optical sensing.{\textless}/p{\textgreater}

}, issn = {2050-7526}, doi = {10.1039/C7TC05271E}, url = {http://xlink.rsc.org/?DOI=C7TC05271E}, author = {{T. Vicente}, Ant{\'o}nio and Ara{\'u}jo, Andreia and Mendes, Manuel J and Nunes, Daniela and Oliveira, Maria J. and Sanchez-Sobrado, Olalla and Ferreira, Marta P. and {\'A}guas, Hugo and Fortunato, Elvira and Martins, Rodrigo} } @article {Neves2018, title = {{Investigation of single phase Cu2ZnSnxSb1-xS4 compounds processed by mechanochemical synthesis}}, journal = {Physical Review Materials}, volume = {2}, number = {7}, year = {2018}, note = {n/a}, month = {jul}, publisher = {American Physical Society}, abstract = {

The copper zinc tin sulfide (CZTS) compound is a promising candidate as an alternative absorber material for thin-film solar cells. In this study, we investigate the direct formation of Cu1.92ZnSnx(Sb1-x)S4 compounds [CZT(A)S], with x=1, 0.85, 0.70, and 0.50, via a mechanochemical synthesis (MCS) approach, starting from powders of the corresponding metals, zinc sulfide, and sulfur. The thermal stability of the CZT(A)S compounds was evaluated in detail by in situ synchrotron high-energy x-ray diffraction measurements up to 700 {\textdegree}C. The CZT(A)S compounds prepared via MCS revealed a sphalerite-type crystal structure with strong structural stability over the studied temperature range. The contribution of the MCS to the formation of such a structure at room temperature is analyzed in detail. Additionally, this study provides insights into the MCS of CZTS-based compounds: the possibility of a large-scale substitution of Sn by Sb and the production of single phase CZT(A)S with a Cu-poor/Zn-poor composition. A slight increase in the band gap from 1.45 to 1.49-1.51 eV was observed with the incorporation of Sb, indicating that these novel compounds can be further explored for thin-film solar cells.

}, issn = {24759953}, doi = {10.1103/PhysRevMaterials.2.075404}, author = {Neves, F. and Stark, A. and Schell, N. and Mendes, MJ and Aguas, H. and Fortunato, E. and Martins, R. and Correia, J.B. and Joyce, A.} } @booklet {BenWannes2018, title = {{Study of the stabilizer influence on the structural and optical properties of sol-gel spin coated zinc oxide films}}, journal = {Materials Science in Semiconductor Processing}, volume = {74}, year = {2018}, note = {n/a}, month = {feb}, pages = {80{\textendash}87}, publisher = {Elsevier Ltd}, abstract = {

In this work, we highlight the influence of three different sol stabilizers, namely diethanolamine (DEA), Ammonium Hydroxide (NH4OH), and Nitric Acid (HNO3), on the optical and structural properties of spin-coated zinc oxide (ZnO) thin films. The XRD patterns related to all films exhibit a hexagonal crystal structure with a preferential orientation along the (0 0 2) direction. However an additional {\textless}100{\textgreater} peak arises when the films are prepared with DEA and NH4OH showing a better crystallinity than that displayed by HNO3-prepared films. The elaborated films show a high transparency reaching 80{\%} for DEA-prepared films. The analysis of the transmittance and the reflectance measurements confirms a direct band-to-band transition. Depending on the sol stabilizer, the optical band gap energy is varying from 3.16 to 3.22 eV. The relatively wide band-gap of DEA-prepared ZnO films is correlated to their high crystallinity. Room temperature photoluminescence spectra indicate strong UV emission at around 377 nm originated from nearby band-edge transitions. Yet, the use of DEA as a stabilizer leads to a net intensity increase of the blue peak emission.

}, keywords = {Optical band gap, photoluminescence, sol stabilizer, Structural properties, ZnO}, issn = {13698001}, doi = {10.1016/j.mssp.2017.10.017}, author = {{Ben Wannes}, H. and Zaghouani, R. Benabderrahmane and Ouertani, R. and Ara{\'u}jo, A and Mendes, MJ and Aguas, H. and Fortunato, E. and Martins, R. and Dimassi, W.} } @article {HB2018, title = {{Li-doped ZnO Sol-Gel Thin Films: Correlation between Structural Morphological and Optical Properties}}, journal = {Journal of Textile Science {\&} Engineering}, volume = {08}, number = {01}, year = {2018}, note = {n/a}, publisher = {OMICS Publishing Group}, abstract = {n/a}, doi = {10.4172/2165-8064.1000328}, author = {HB, Wannes and WR, Dimassi and B, Zaghouani and MJ, Mendes} } @article {Martins2018, title = {{Papertronics: Multigate paper transistor for multifunction applications}}, journal = {Applied Materials Today}, volume = {12}, year = {2018}, note = {n/a}, abstract = {

{\textcopyright} 2018 The Authors The use of disposable recyclable, eco-friendly, sustainable and low-cost devices with multiple functions is becoming a demand in the emerging area of the Internet of Things as a way to decrease the degree of complexity of the electronic circuits required to serve a plethora of applications. Moreover, for low-cost disposable applications, it is relevant the systems to be recyclable. The idea beyond the present study concerns to exploit our imagination with simple questions such as: What happens if it is possible to have a simple and universal device architecture, easy to implement on paper substrates, but capable to provide different multiple functionalities? It would be possible to have a common template for electronic systems on paper that would be then easily customized depending on the final application? The present study answers to these demands by reporting the physics and electronics behavior of a multigate paper transistor where paper is simultaneously the substrate and the dielectric, while a metal-oxide-semiconductor (IGZO) is used as the active channel. Moreover, the same device is able to present logic functionalities simply by varying the amplitude and frequency of the input gate signals. These transistors operate at drain voltages of 1 V with low power, exhibiting ION/IOFF{\textgreater} 104and a mobility ≈2 cm2V-1s-1, serving the specifications for a broad range of smart disposable low power electronics. To sustain all this, an analytical compact model was developed able to precisely reproduce the response of paper-based dual-gate FETs and provide full understanding of their unique and innovative operational characteristics.

}, keywords = {Dual gate paper transistors, Multifunction paper transistors, paper electronics, Paper functionalization, Papertronics}, issn = {23529407}, doi = {10.1016/j.apmt.2018.07.002}, author = {Martins, R. and Gaspar, D and Mendes, MJ and Pereira, L. and J. Martins and Bahubalindruni, P. and Barquinha, P. and Fortunato, E.} } @inbook {Vicente2017a, title = {{Optoelectronics and Bio Devices on Paper Powered by Solar Cells}}, booktitle = {Nanostructured Solar Cells}, year = {2017}, note = {n/a}, month = {feb}, publisher = {InTech}, organization = {InTech}, abstract = {

The employment of printing techniques as cost-effective methods to fabricate low cost, flexible, disposable and sustainable solar cells is intimately dependent on the substrate properties and the adequate electronic devices to be powered by them. Among such devices, there is currently a growing interest in the development of user-oriented and multipurpose systems for intelligent packaging or on-site medical diagnostics, which would greatly benefit from printable solar cells as their energy source for autonomous operation. This chapter first describes and analyzes different types of cellulose-based substrates for flexible and cost effective optoelectronic and bio devices to be powered by printed solar cells. Cellulose is one of the most promising platforms for green recyclable electronics and it is fully compatible with large-scale printing techniques, although some critical requirements must be addressed. Paper substrates exist in many forms. From common office paper, to packaging cardboard used in the food industry, or nanoscale engineered cellulose (e.g. bacterial cellulose). However, it is the structure and content of paper that determines its end use. Secondly, proof-of-concept of optoelectronic and bio devices pro-duced by inkjet printing are described and show the usefulness of solar cells as a power source or as a chemical reaction initiator for sensors.

}, doi = {10.5772/66695}, author = {Vicente, Ant{\'o}nio T and Ara{\'u}jo, Andreia and Gaspar, Diana and Santos, L{\'\i}dia and Marques, Ana C. and Mendes, Manuel J and Pereira, Lu{\'I}s and Fortunato, Elvira and Martins, Rodrigo} } @article {Pimentel2017, title = {{3D ZnO/Ag surface-enhanced Raman scattering on disposable and flexible cardboard platforms}}, journal = {Materials}, volume = {10}, number = {12}, year = {2017}, note = {n/a}, abstract = {

{\textcopyright} 2017 by the authors. In the present study, zinc oxide (ZnO) nanorods (NRs) with a hexagonal structure have been synthesized via a hydrothermal method assisted by microwave radiation, using specialized cardboard materials as substrates. Cardboard-type substrates are cost-efficient and robust paper-based platforms that can be integrated into several opto-electronic applications for medical diagnostics, analysis and/or quality control devices. This class of substrates also enables highly-sensitive Raman molecular detection, amiable to several different operational environments and target surfaces. The structural characterization of the ZnO NR arrays has been carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical measurements. The effects of the synthesis time (5-30 min) and temperature (70-130 {\textdegree}C) of the ZnO NR arrays decorated with silver nanoparticles (AgNPs) have been investigated in view of their application for surface-enhanced Raman scattering (SERS) molecular detection. The size and density of the ZnO NRs, as well as those of the AgNPs, are shown to play a central role in the final SERS response. A Raman enhancement factor of 7 {\texttimes} 105was obtained using rhodamine 6 G (RG6) as the test analyte; a ZnO NR array was produced for only 5 min at 70 {\textdegree}C. This condition presents higher ZnO NR and AgNP densities, thereby increasing the total number of plasmonic "hot-spots", their volume coverage and the number of analyte molecules that are subject to enhanced sensing.

}, keywords = {Ag nanoparticles, Cardboard substrates, Microwave synthesis, SERS, ZnO nanorods}, issn = {19961944}, doi = {10.3390/ma10121351}, author = {Pimentel, A. and Ara{\'u}jo, A and Coelho, B.J. and Nunes, D. and Oliveira, M.J. and Mendes, MJ and {\'A}guas, H. and Martins, R. and Fortunato, E.} } @article {Vicente2017, title = {{A statistics modeling approach for the optimization of thin film photovoltaic devices}}, journal = {Solar Energy}, volume = {144}, year = {2017}, note = {n/a}, abstract = {

{\textcopyright} 2017 The growing interest in exploring thin film technologies to produce low cost devices such as n-i-p silicon solar cells, with outstanding performances and capability to address the highly relevant energy market, turns the optimization of their fabrication process a key area of development. The usual one-dimensional analysis of the involved parameters makes it difficult and time consuming to find the optimal set of conditions. To overcome these difficulties, the combination of experimental design and statistical analysis provides the tools to explore in a multidimensional fashion the interactions between fabrication parameters and expected experimental outputs. Design of Experiment and Multivariate Analysis are demonstrated here for the optimization of: (1) the low temperature deposition (150 {\textdegree}C) of high quality intrinsic amorphous silicon (i-a-Si:H); and (2) the matching of the n-, i-, and p-silicon layers thickness to maximize the efficiency of thin film solar cells. The multiple regression method applied, validated through analysis of variance and evaluated against exact numerical simulations, is shown to predict the overall intrinsic layer properties and the devices performance. The results confirm that experimental design and statistical data analysis are effective approaches to improve, within a minimum time frame and high certainty, the properties of silicon thin films, and subsequently the layer structure of solar cells.

}, keywords = {Design of experiment, Multivariate analysis, PECVD, Solar cells, thin films}, issn = {0038092X}, doi = {10.1016/j.solener.2017.01.029}, author = {Vicente, A.T. and Wojcik, PJ and Mendes, MJ and {\'A}guas, H. and Fortunato, E. and Martins, R.} } @article {Sanchez-Sobrado2017, title = {{Colloidal-lithographed TiO2 photonic nanostructures for solar cell light trapping}}, journal = {J. Mater. Chem. C}, year = {2017}, note = {n/a}, abstract = {n/a}, doi = {10.1039/C7TC01756A}, author = {Sanchez-Sobrado, Olalla and Mendes, Manuel J and Haque, Sirazul and Mateus, Tiago and Araujo, Andreia and Aguas, Hugo and Fortunato, Elvira and Martins, Rodrigo} } @article {Araujo2017, title = {{Direct growth of plasmonic nanorod forests on paper substrates for low-cost flexible 3D SERS platforms}}, journal = {Flexible and Printed Electronics}, volume = {2}, number = {1}, year = {2017}, note = {n/a}, abstract = {

Paper substrates, coated with ZnO nanorods (NRs) decorated with Ag nanoparticles (NPs), allowed the production of inexpensive, highly-performing and extremely reproducible three-dimensional (3D) SERS platforms. The ZnO NRs were synthesized by a simple, fast and low-temperature hydrothermal method assisted by microwave radiation and made SERS-active by decorating them with a dense array of silver nanoparticles deposited via a single-step thermal evaporation technique. Using Rhodamine 6G (R6G) as a probe molecule, with an amount down to 10-9 M, the SERS substrates allowed a Raman signal enhancement of 107. The contribution of the inter-Ag-NPs gaps for 3D geometry, ZnO NRs orientation and the large sensing area allowed by theNRscaffolds, were determinant factors for the significant Raman enhancement observed. The results demonstrate that plasmonic nanorod forests, covered with Ag NPs, are efficient SERS substrates with the advantages of being recyclable, flexible, lightweight, portable, biocompatible and extremely low-cost.

}, keywords = {Paper substrates, Plasmonics, SERS, Silver nanoparticles, ZnO nanorods}, issn = {20588585}, doi = {10.1088/2058-8585/2/1/014001}, author = {Ara{\'u}jo, A and Pimentel, A. and Oliveira, M.J. and Mendes, MJ and Franco, R and Fortunato, E. and {\'A}guas, H. and Martins, R.} } @article {Marouf2017, title = {{Low-temperature spray-coating of high-performing ZnO:Al films for transparent electronics}}, journal = {Journal of Analytical and Applied Pyrolysis}, volume = {127}, year = {2017}, note = {n/a}, abstract = {

{\textcopyright} 2017 Elsevier B.V. Ultrasonic spray pyrolysis deposition of ZnO-based materials offers an attractive high-throughput low-cost route towards industrial production of high-quality transparent conductive oxide (TCO) thin-films. In this work, undoped and aluminium-doped ZnO films have been grown employing ultrasonic spray pyrolysis at relatively low-temperate (300 {\textdegree}C), followed by a post-annealing treatment. The role of Al concentration in the starting solution, as well as the rapid thermal annealing (RTA) atmosphere, were investigated and correlated to the morphological, structural, electrical and optical properties of the films. The remarkable enhancement of electrical conductivity attained here is mainly ascribed to the combined effects of: (1) homogenous incorporation of Al3+into the ZnO matrix, which enhances crystal quality providing higher electronic mobility; and (2) the RTA which releases the localized electrons caused by oxygen absorption and thereby increases the free carrier density. Under optimum deposition conditions, a low resistivity and a high optical transmittance around 4 {\texttimes} 10-3${\O}mega$ cm and 87{\%}, respectively, were obtained. The application of the RTA post-process after low temperature growth has several advantages relative to the direct growth at high temperature (usually 400{\textendash}575 {\textdegree}C), such as shorter growth time and lower cost associated to the spray pyrolysis equipment requirements and usage. The results suggest that the electrical and optical properties of the ZnO:Al films can be further improved for solar cell applications by controlling the temperature of the post-deposition annealing in reducing atmosphere.

}, keywords = {Photovoltaics, rapid thermal annealing, Spray pyrolysis, transparent conducting oxides, ZnO:Al films}, issn = {01652370}, doi = {10.1016/j.jaap.2017.07.021}, author = {Marouf, S. and Beniaiche, A. and Kardarian, K. and Mendes, MJ and Sanchez-Sobrado, O. and {\'A}guas, H. and Fortunato, E. and Martins, R.} } @article {Mendes2016, title = {{Design of optimized wave-optical spheroidal nanostructures for photonic-enhanced solar cells}}, journal = {Nano Energy}, volume = {26}, year = {2016}, note = {n/a}, pages = {286{\textendash}296}, publisher = {Elsevier}, abstract = {

The interaction of light with wavelength-sized photonic nanostructures is highly promising for light management applied to thin-film photovoltaics. Several light trapping effects come into play in the wave optics regime of such structures that crucially depend on the parameters of the photonic and absorbing elements. Thus, multi-parameter optimizations employing exact numerical models, as performed in this work, are essential to determine the maximum photocurrent enhancement that can be produced in solar cells.Generalized spheroidal geometries and high-index dielectric materials are considered here to model the design of the optical elements providing broadband absorption enhancement in planar silicon solar cells. The physical mechanisms responsible for such enhancement are schematized in a spectral diagram, providing a deeper understanding of the advantageous characteristics of the optimized geometries. The best structures, composed of TiO2 half-spheroids patterned on the cells{\textquoteright} top surface, yield two times higher photocurrent (up to 32.5 mA/cm2 in 1.5 $μ$m thick silicon layer) than the same devices without photonic schemes.These results set the state-of-the-art closer to the theoretical Lambertian limit. In addition, the considered light trapping designs are not affected by the traditional compromise between absorption enhancement versus current degradation by recombination, which is a key technological advantage.

}, keywords = {High-index dielectric scatterers, light trapping, Nanophotonics, Photovoltaics, Thin film solar cells, Wave-optics}, isbn = {2211-2855}, issn = {22112855}, doi = {10.1016/j.nanoen.2016.05.038}, url = {http://dx.doi.org/10.1016/j.nanoen.2016.05.038}, author = {Mendes, Manuel J and Ara{\'u}jo, Andreia and Vicente, Ant{\'o}nio and {\'A}guas, Hugo and Ferreira, Isabel and Fortunato, Elvira and Martins, Rodrigo} } @article {Morawiec2016, title = {{Experimental quantification of useful and parasitic absorption of light in plasmon-enhanced thin silicon films for solar cells application}}, journal = {Scientific Reports}, year = {2016}, note = {n/a}, abstract = {n/a}, doi = {10.1038/srep22481}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84960171786{\&}partnerID=MN8TOARS}, author = {Morawiec, S. and Holovsk{\'y}, J and Mendes, MJ and M{\"u}ller, M and Ganzerov{\'a}, K and Vetushka, A and Ledinsk{\'y}, M and Priolo, F. and Fejfar, A and Crupi, I.} } @article {Lyubchyk2016, title = {{Influence of post-deposition annealing on electrical and optical properties of ZnO-based TCOs deposited at room temperature}}, journal = {Physica Status Solidi (A) Applications and Materials Science}, volume = {213}, number = {9}, year = {2016}, note = {n/a}, abstract = {

{\textcopyright} 2016 WILEY-VCH Verlag GmbH {\&} Co. KGaA, Weinheim The post-deposition modification of ZnO-based transparent conductive oxides (TCOs) can be the key to produce thin films with optoelectronic properties similar to indium tin oxide (ITO), but at a much lower cost. Here, we present electro-optical results achieved for post-deposition annealing of Al{\textendash}Zn{\textendash}O (AZO), AZO:H, Ga{\textendash}Zn{\textendash}O:H (GZO:H), and Zn{\textendash}O:H (ZNO:H) thin films deposited by RF sputtering at room temperature. These studies comprise results of thermal annealing at atmospheric pressure, vacuum, forming gas, H2and Ar atmospheres, and H2and Ar plasmas, which lead to significant enhancement of their electro-optical properties, which are correlated to morphological and structural improvements. The post-deposition annealing leads to an enhancement in resistivity above 40{\%} for AZO, AZO:H, and GZO:H, reaching $\rho$ ≈ 2.6{\textendash}3.5 {\texttimes} 10-4${\O}mega$cm, while ZnO:H showed a lower improvement of 13{\%}. The averaged optical transmittance in the visible region is about 89{\%} for the investigated TCOs. Such results match the properties of state-of-art ITO ($\rho$ ≈ 10-4${\O}mega$cm and transmittance in VIS range of 90{\%}) employing much more earth-abundant materials.

}, keywords = {Annealing, hydrogenation, thin films, transparent conductive oxides, ZnO}, issn = {18626319}, doi = {10.1002/pssa.201532891}, author = {Lyubchyk, A and Vicente, A and Alves, P.U. and Catela, B. and Soule, B. and Mateus, T and Mendes, MJ and {\'A}guas, H. and Fortunato, E. and Martins, R.} } @article {Araujo2016, title = {{Influence of the Substrate on the Morphology of Self-Assembled Silver Nanoparticles by Rapid Thermal Annealing}}, journal = {Journal of Physical Chemistry C}, year = {2016}, note = {n/a}, abstract = {n/a}, doi = {10.1021/acs.jpcc.6b04283}, url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2{\&}SrcAuth=ORCID{\&}SrcApp=OrcidOrg{\&}DestLinkType=FullRecord{\&}DestApp=WOS{\_}CPL{\&}KeyUT=WOS:000381778000040{\&}KeyUID=WOS:000381778000040}, author = {Araujo, Andreia and Mendes, Manuel J and Mateus, Tiago and Vicente, Antonio and Nunes, Daniela and Calmeiro, Tomas and Fortunato, Elvira and Aguas, Hugo and Martins, Rodrigo} } @article {Lyubchyk2016a, title = {{Mapping the Electrical Properties of ZnO-Based Transparent Conductive Oxides Grown at Room Temperature and Improved by Controlled Postdeposition Annealing}}, journal = {Advanced Electronic Materials}, volume = {2}, number = {1}, year = {2016}, note = {n/a}, pages = {1500287}, abstract = {

Indium tin oxide (ITO) is the current standard state-of-the-art transparent conductive oxide (TCO), given its remarkable optical and electrical properties. However, the scarcity of indium carries an important drawback for the long-term application due to its intensive use in many optoelectronic devices such as displays, solar cells, and interactive systems. Zinc oxide-based TCOs can be a cost-effective and viable alternative, but the limitations imposed by their transmittance versus resistivity tradeoff still keep them behind ITO. In this work, an in-depth study of the structural and compositional material changes induced by specific postannealing treatments is presented, based on aluminum zinc oxide (AZO) and hydrogenated AZO (AZO:H) thin films grown by rf-magnetron sputtering at room temperature that allows an extensive understanding of the films{\textquoteright} electrical/structural changes and the ability to tune their physical parameters to yield increasingly better performances, which put them in line with the best ITO quality standards. The present investigation comprises results of thermal annealing at atmospheric pressure, vacuum, forming gas, H2 and Ar atmospheres and plasmas. Overall the study being performed leads to a decrease in resistivity above 40{\%}, reaching $\rho$ ≈ 3 {\texttimes} 10-4 ${\O}mega$ cm, with an average optical transmittance in the visible region around 88{\%}. Such results are equivalent to the properties of state-of-the-art ITO.

}, keywords = {aluminum zinc oxide, annealing maps, electrical properties, thin films}, isbn = {2199-160X}, doi = {10.1002/aelm.201500287}, url = {http://dx.doi.org/10.1002/aelm.201500287}, author = {Lyubchyk, Andriy and Vicente, Ant{\'o}nio and Soule, Bertrand and Alves, Pedro Urbano and Mateus, Tiago and Mendes, Manuel J and {\'A}guas, Hugo and Fortunato, Elvira and Martins, Rodrigo} } @article {Mendes2015, title = {{Broadband light trapping in thin film solar cells with self-organized plasmonic nanocolloids}}, journal = {Nanotechnology}, volume = {26}, number = {13}, year = {2015}, note = {n/a}, abstract = {

{\textcopyright} 2015 IOP Publishing Ltd. The intense light scattered from metal nanoparticles sustaining surface plasmons makes them attractive for light trapping in photovoltaic applications. However, a strong resonant response from nanoparticle ensembles can only be obtained if the particles have monodisperse physical properties. Presently, the chemical synthesis of colloidal nanoparticles is the method that produces the highest monodispersion in geometry and material quality, with the added benefits of being low-temperature, low-cost, easily scalable and of allowing control of the surface coverage of the deposited particles. In this paper, novel plasmonic back-reflector structures were developed using spherical gold colloids with appropriate dimensions for pronounced far-field scattering. The plasmonic back reflectors are incorporated in the rear contact of thin film n-i-p nanocrystalline silicon solar cells to boost their photocurrent generation via optical path length enhancement inside the silicon layer. The quantum efficiency spectra of the devices revealed a remarkable broadband enhancement, resulting from both light scattering from the metal nanoparticles and improved light incoupling caused by the hemispherical corrugations at the cells{\textquoteright} front surface formed from the deposition of material over the spherically shaped colloids.

}, keywords = {light trapping, Mie scatterers, Photovoltaics, Plasmonics, Thin film silicon solar cells}, issn = {13616528}, doi = {10.1088/0957-4484/26/13/135202}, author = {Mendes, MJ and Morawiec, S. and Mateus, T and Lyubchyk, A and {\'A}guas, H. and Ferreira, I. and Fortunato, E. and Martins, R. and Priolo, F. and Crupi, I.} } @conference {Tobias2015, title = {{HIT intermediate-band solar cells with self-assembled colloidal quantum dots and metal nanoparticles}}, booktitle = {2015 IEEE 42nd Photovoltaic Specialist Conference, PVSC 2015}, year = {2015}, note = {n/a}, abstract = {n/a}, doi = {10.1109/PVSC.2015.7355804}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84961677921{\&}partnerID=MN8TOARS}, author = {Tobias, I and Mendes, MJ and Boronat, A and Lopez, E and Garcia-Linares, P and Artacho, I and Marti, A and Silvestre, S and Luque, A} } @article {Lyubchyk2015, title = {{Nanocrystalline thin film silicon solar cells: A deeper look into p/i interface formation}}, journal = {Thin Solid Films}, year = {2015}, note = {n/a}, abstract = {n/a}, doi = {10.1016/j.tsf.2015.08.016}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84942037268{\&}partnerID=MN8TOARS}, author = {Lyubchyk, A and Filonovich, SA and Mateus, T and Mendes, MJ and Vicente, A and Leit{\~a}o, JP and Falc{\~a}o, BP and Fortunato, E. and {\'A}guas, H. and Martins, R.} } @article {Schuster2015, title = {{Plasmonic and diffractive nanostructures for light trapping - an experimental comparison}}, journal = {Optica}, volume = {2}, number = {3}, year = {2015}, note = {n/a}, pages = {194{\textendash}200}, publisher = {OSA}, abstract = {

Metal nanoparticles and diffractive nanostructures are widely studied for enhancing light trapping efficiency in thin-film solar cells. Both have achieved high performance enhancements, but there are very few direct comparisons between the two. Also, it is difficult to accurately determine the parasitic absorption of metal nanoparticles. Here, we assess the light trapping efficiencies of both approaches in an identical absorber configuration. We use a 240 nm thick amorphous silicon slab as the absorber layer and either a quasi-random supercell diffractive nanostructure or a layer of self-assembled metal nanoparticles for light trapping. Both the plasmonic and diffractive structures strongly enhance the absorption in the red/near-infrared regime. At longer wavelengths, however, parasitic absorption becomes evident in the metal nanoparticles, which reduces the overall performance of the plasmonic approach. We have formulated a simple analytical model to assess the parasitic absorption and effective reflectivity of a plasmonic reflector and to demonstrate good agreement with the experimental data.

}, keywords = {Diffraction gratings, nanostructures, Photovoltaic, Plasmonics, Subwavelength structures}, doi = {10.1364/optica.2.000194}, url = {http://www.opticsinfobase.org/optica/abstract.cfm?URI=optica-2-3-194}, author = {Schuster, Christian S and Morawiec, Seweryn and Mendes, Manuel J and Patrini, Maddalena and Martins, Emiliano R and Lewis, Liam and Crupi, Isodiana and Krauss, Thomas F} } @article {Vicente2015, title = {{Solar cells for self-sustainable intelligent packaging}}, journal = {Journal of Materials Chemistry A}, volume = {3}, number = {25}, year = {2015}, note = {n/a}, pages = {13226{\textendash}13236}, publisher = {The Royal Society of Chemistry}, abstract = {

Nowadays there is a strong demand for intelligent packaging to provide comfort, welfare and security to owners, vendors and consumers by allowing them to know the contents and interact with the goods. This is of particular relevance for low cost, fully disposable and recyclable products, such as identification tags and medical diagnostic tests, and devices for analysis and/or quality control in food and pharmaceutical industries. However, the increase of complexity and processing capacity requires continuous power and can be addressed by the combined use of a small disposable battery, charged by a disposable solar cell, which is able to work under indoor lighting. Herein, we show a proof-of-concept of the pioneering production of thin-film amorphous silicon (a-Si:H) solar cells with an efficiency of 4{\%} by plasma enhanced chemical vapour deposition (PECVD) on liquid packaging cardboard (LPC), which is commonly used in the food and beverage industries. Such accomplishment put us one step closer to this revolution by providing a flexible, renewable and extremely cheap autonomous energy packaging system. Moreover, such Si thin films take advantage of their good performance at low-light levels, which also makes them highly desirable for cheap mobile indoor applications.

}, isbn = {2050-7488}, doi = {10.1039/c5ta01752a}, url = {http://dx.doi.org/10.1039/C5TA01752A}, author = {Vicente, Antonio and Aguas, Hugo and Mateus, Tiago and Araujo, Andreia and Lyubchyk, Andriy and Siitonen, Simo and Fortunato, Elvira and Martins, Rodrigo} } @article {Aguas2015, title = {{Thin Film Silicon Photovoltaic Cells on Paper for Flexible Indoor Applications}}, journal = {Advanced Functional Materials}, volume = {25}, number = {23}, year = {2015}, note = {n/a}, pages = {3592{\textendash}3598}, abstract = {

The present development of non-wafer-based photovoltaics (PV) allows supporting thin film solar cells on a wide variety of low-cost recyclable and flexible substrates such as paper, thereby extending PV to a broad range of consumer-oriented disposable applications where autonomous energy harvesting is a bottleneck issue. However, their fibrous structure makes it challenging to fabricate good-performing inorganic PV devices on such substrates. The advances presented here demonstrate the viability of fabricating thin film silicon PV cells on paper coated with a hydrophilic mesoporous layer. Such layer can not only withstand the cells production temperature (150 {\textdegree}C), but also provide adequate paper sealing and surface finishing for the cell{\textquoteright}s layers deposition. The substances released from the paper substrate are continuously monitored during the cell deposition by mass spectrometry, which allows adapting the procedures to mitigate any contamination from the substrate. In this way, a proof-of-concept solar cell with 3.4{\%} cell efficiency (41{\%} fill factor, 0.82 V open-circuit voltage and 10.2 mA cm-2 short-circuit current density) is attained, opening the door to the use of paper as a reliable substrate to fabricate inorganic PV cells for a plethora of indoor applications with tremendous impact in multi-sectorial fields such as food, pharmacy and security.

}, keywords = {disposable electronics, flexible electronics, Paper substrates, Photovoltaics, thin film silicon}, isbn = {1616-3028}, doi = {10.1002/adfm.201500636}, url = {http://dx.doi.org/10.1002/adfm.201500636}, author = {{\'A}guas, Hugo and Mateus, Tiago and Vicente, Ant{\'o}nio and Gaspar, Diana and Mendes, Manuel J and Schmidt, Wolfgang A and Pereira, Lu{\'I}s and Fortunato, Elvira and Martins, Rodrigo} } @article {Gaspar2014, title = {{Ag and Sn Nanoparticles to Enhance the Near-Infrared Absorbance of a-Si:H Thin Films}}, journal = {Plasmonics}, volume = {9}, number = {5}, year = {2014}, note = {n/a}, pages = {1015{\textendash}1023}, publisher = {Springer US}, abstract = {n/a}, keywords = {61.46.Df{\textendash}Structure of nanoparticles, 78.67.Bf{\textendash}Optical properties of nanoscale materials, 81.15.Jj{\textendash}Film deposition, a-Si:H, electron beam-assisted d, light trapping, Silver and tin nanoparticles, Surface plasmons}, isbn = {1557-1955}, doi = {10.1007/s11468-014-9709-0}, url = {http://dx.doi.org/10.1007/s11468-014-9709-0}, author = {Gaspar, D and Pimentel, AC and Mendes, MJ and Mateus, T and Falc{\~a}o, BP and Leit{\~a}o, JP and Soares, J and Ara{\'u}jo, A and Vicente, A and Filonovich, SA and {\'A}guas, H. and Martins, R. and Ferreira, I.} } @article {Morawiec2014a, title = {{Broadband photocurrent enhancement in a-Si:H solar cells with plasmonic back reflectors}}, journal = {Optics Express}, volume = {22}, number = {S4}, year = {2014}, note = {n/a}, pages = {A1059{\textendash}A1070}, publisher = {OSA}, abstract = {

Plasmonic light trapping in thin film silicon solar cells is a promising route to achieve high efficiency with reduced volumes of semiconductor material. In this paper, we study the enhancement in the opto-electronic performance of thin a-Si:H solar cells due to the light scattering effects of plasmonic back reflectors (PBRs), composed of self-assembled silver nanoparticles (NPs), incorporated on the cells{\&}{\#}x2019; rear contact. The optical properties of the PBRs are investigated according to the morphology of the NPs, which can be tuned by the fabrication parameters. By analyzing sets of solar cells built on distinct PBRs we show that the photocurrent enhancement achieved in the a-Si:H light trapping window (600 {\&}{\#}x2013; 800 nm) stays in linear relation with the PBRs diffuse reflection. The best-performing PBRs allow a pronounced broadband photocurrent enhancement in the cells which is attributed not only to the plasmon-assisted light scattering from the NPs but also to the front surface texture originated from the conformal growth of the cell material over the particles. As a result, remarkably high values of Jsc and Voc are achieved in comparison to those previously reported in the literature for the same type of devices.

}, keywords = {particles, Plasmonics, Scattering, Solar energy}, doi = {10.1364/oe.22.0a1059}, url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-22-104-A1059}, author = {Morawiec, Seweryn and Mendes, Manuel J and Filonovich, Sergej A and Mateus, Tiago and Mirabella, Salvatore and {\'A}guas, Hugo and Ferreira, Isabel and Simone, Francesca and Fortunato, Elvira and Martins, Rodrigo and Priolo, Francesco and Crupi, Isodiana} } @article {Mendes2014, title = {{Colloidal plasmonic back reflectors for light trapping in solar cells}}, journal = {Nanoscale}, volume = {6}, number = {9}, year = {2014}, note = {n/a}, abstract = {

A novel type of plasmonic light trapping structure is presented in this paper, composed of metal nanoparticles synthesized in colloidal solution and self-assembled in uniform long-range arrays using a wet-coating method. The high monodispersion in size and spherical shape of the gold colloids used in this work allows a precise match between their measured optical properties and electromagnetic simulations performed with Mie theory, and enables the full exploitation of their collective resonant plasmonic behavior for light-scattering applications. The colloidal arrays are integrated in plasmonic back reflector (PBR) structures aimed for light trapping in thin film solar cells. The PBRs exhibit high diffuse reflectance (up to 75{\%}) in the red and near-infrared spectrum, which can pronouncedly enhance the near-bandgap photocurrent generated by the cells. Furthermore, the colloidal PBRs are fabricated by low-temperature ({\textless}120 {\textdegree}C) processes that allow their implementation, as a final step of the cell construction, in typical commercial thin film devices generally fabricated in a superstrate configuration. {\textcopyright} 2014 the Partner Organisations.

}, issn = {20403372}, doi = {10.1039/c3nr06768h}, author = {Mendes, MJ and Morawiec, S. and Simone, F and Priolo, F. and Crupi, I.} } @conference {Mendes2014a, title = {{Colloidal self-assembled nanosphere arrays for plasmon-enhanced light trapping in thin film silicon solar cells}}, booktitle = {Energy Procedia}, year = {2014}, note = {n/a}, abstract = {n/a}, doi = {10.1016/j.egypro.2013.12.026}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84893377546{\&}partnerID=MN8TOARS}, author = {Mendes, MJ and Morawiec, S. and Crupi, I. and Simone, F and Priolo, F.} } @article {Araujo2014, title = {{Highly efficient nanoplasmonic SERS on cardboard packaging substrates}}, journal = {Nanotechnology}, volume = {25}, number = {41}, year = {2014}, note = {n/a}, abstract = {

{\textcopyright} 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.

}, keywords = {Plasmonics, SERS substrates, Silver nanoparticles}, issn = {13616528}, doi = {10.1088/0957-4484/25/41/415202}, author = {Ara{\'u}jo, A and Caro, C. and Mendes, MJ and Nunes, D. and Fortunato, E. and Franco, R and {\'A}guas, H. and Martins, R.} } @conference {Morawiec2014, title = {{Photocurrent enhancement in thin a-Si: H solar cells via plasmonic light trapping}}, booktitle = {Optics InfoBase Conference Papers}, year = {2014}, note = {n/a}, abstract = {n/a}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84906861303{\&}partnerID=MN8TOARS}, author = {Morawiec, S. and Mendes, MJ and Filonovich, SA and Mateus, T and Mirabella, S and {\'A}guas, H. and Ferreira, I. and Simone, F and Fortunato, E. and Martins, R. and Priolo, F. and Crupi, I.} } @article {Morawiec2013, title = {{Self-assembled silver nanoparticles for plasmon-enhanced solar cell back reflectors: correlation between structural and optical properties}}, journal = {Nanotechnology}, volume = {24}, number = {26}, year = {2013}, note = {n/a}, pages = {265601}, abstract = {

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.

}, isbn = {0957-4484}, url = {http://stacks.iop.org/0957-4484/24/i=26/a=265601}, author = {Morawiec, Seweryn and Mendes, Manuel J and Mirabella, Salvatore and Simone, Francesca and Priolo, Francesco and Crupi, Isodiana} } @article {Mendes2013, title = {{Self-organized colloidal quantum dots~and metal nanoparticles for plasmon-enhanced intermediate-band solar cells}}, journal = {Nanotechnology}, volume = {24}, number = {34}, year = {2013}, note = {n/a}, pages = {345402}, abstract = {

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.

}, isbn = {0957-4484}, url = {http://stacks.iop.org/0957-4484/24/i=34/a=345402}, author = {Mendes, Manuel J and Hern{\'a}ndez, Estela and L{\'o}pez, Esther and Garc{\'\i}a-Linares, Pablo and Ramiro, I{\~n}igo and Artacho, Irene and Antol{\'\i}n, Elisa and Tob{\'\i}as, Ignacio and Mart{\'\i}, Antonio and Luque, Antonio} } @article {Marti2013, title = {{Six not-so-easy pieces in intermediate band solar cell research}}, journal = {Journal of Photonics for Energy}, volume = {3}, number = {1}, year = {2013}, note = {n/a}, pages = {31299}, abstract = {

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{\textquoteright}s transition? What would the best system be, if any?

}, isbn = {1947-7988}, doi = {10.1117/1.jpe.3.031299}, url = {http://dx.doi.org/10.1117/1.JPE.3.031299}, author = {Mart{\'\i}, Antonio and Antol{\'\i}n, Elisa and {Garc{\'\i}a Linares}, Pablo and Ramiro, I{\~n}igo and Artacho, Irene and L{\'o}pez, Esther and Hern{\'a}ndez, Estela and Mendes, Manuel J and Mellor, Alex and Tob{\'\i}as, Ignacio and {Fuertes Marr{\'o}n}, David and Tablero, Cesar and Crist{\'o}bal, Ana B and Bailey, Christopher G and Gonzalez, Maria and Yakes, Michael and Lumb, Mathew P and Walters, Robert and Luque, Antonio} } @article {Mendes2011a, title = {{Light concentration in the near-field of dielectric spheroidal particles with mesoscopic sizes}}, journal = {Optics Express}, volume = {19}, number = {17}, year = {2011}, note = {n/a}, pages = {16207{\textendash}16222}, publisher = {OSA}, abstract = {n/a}, keywords = {Electromagnetic optics, particles, Photovoltaic, Scattering}, url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-19-17-16207}, author = {Mendes, Manuel J and Tob{\'\i}as, Ignacio and Mart{\'\i}, Antonio and Luque, Antonio} } @conference {Mendes2011, title = {{Near-field light focusing by wavelenght-sized dielectric spheroids for photovoltaic applications}}, booktitle = {Optical Nanostructures and Advanced Materials for Photovoltaics - Concepts of Light Trapping and Photon Transport}, volume = {Renewable}, year = {2011}, note = {n/a}, pages = {JThC}, publisher = {Optical Society of America}, organization = {Optical Society of America}, address = {Austin, Texas (USA)}, abstract = {n/a}, author = {Mendes, MJ and Tob{\'\i}as, I and Mart{\'\i}, A and Luque, A}, editor = {Digest, O S A Technical} } @article {Mellor2011, title = {{Upper limits to absorption enhancement in thick solar cells using diffraction gratings}}, journal = {Progress in Photovoltaics: Research and Applications}, volume = {19}, number = {6}, year = {2011}, note = {n/a}, pages = {676{\textendash}687}, publisher = {John Wiley {\&} Sons, Ltd.}, abstract = {

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{\textendash}1000{\texttimes}). 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 {\textcopyright} 2011 John Wiley {\&} Sons, Ltd.

}, keywords = {absorption enhancement, Diffraction gratings, light trapping}, isbn = {1099-159X}, doi = {10.1002/pip.1086}, url = {http://dx.doi.org/10.1002/pip.1086}, author = {Mellor, A and Tob{\'\i}as, I and Mart{\'\i}, A and Mendes, MJ and Luque, A} } @conference {Mendes2010a, title = {{Embedment of metal nanoparticles in GaAs and Si for plasmonic absorption enhancement in intermediate band solar cells}}, booktitle = {25th European Photovoltaic Solar Energy Conference and Exhibition - 5th World Conference on Photovoltaic Energy Conversion}, year = {2010}, note = {n/a}, pages = {218{\textendash}222}, address = {Valencia, Spain}, abstract = {n/a}, author = {Mendes, MJ and Hern{\'a}ndez, E and Tob{\'\i}as, I and Mart{\'\i}, A and Luque, A} } @article {Mendes2010, title = {{Near-field scattering by dielectric spheroidal particles with sizes on the order of the illuminating wavelength}}, journal = {J. Opt. Soc. Am. B}, volume = {27}, number = {6}, year = {2010}, note = {n/a}, pages = {1221{\textendash}1231}, publisher = {OSA}, abstract = {n/a}, keywords = {Electromagnetic optics, Energy Transfer, particles, Scattering}, url = {http://josab.osa.org/abstract.cfm?URI=josab-27-6-1221}, author = {Mendes, Manuel J and Tob{\'\i}as, Ignacio and Mart{\'\i}, Antonio and Luque, Antonio} } @conference {Marti2009, title = {{IBPOWER: Intermediate band materials and solar cells for photovoltaics with high efficiency and reduced cost}}, booktitle = {Conference Record of the IEEE Photovoltaic Specialists Conference}, year = {2009}, note = {n/a}, abstract = {n/a}, doi = {10.1109/PVSC.2009.5411265}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77951549336{\&}partnerID=MN8TOARS}, author = {Mart{\'\i}, A and Antol{\'\i}n, E and Linares, P G and C{\'a}novas, E and {Fuertes Marr{\'o}n}, D and Tablero, C and Mendes, M and Mellor, A and Tob{\'\i}as, I and Levy, M Y and Hern{\'a}ndez, E and Luque, A and Farmer, C D and Stanley, C R and Campion, R P and Hall, J L and Novikov, S V and Foxon, C T and Scheer, R and Marsen, B and Schock, H W and Picault, M and Chaix, C} } @article {Mendes2009, title = {{Plasmonic light enhancement in the near-field of metallic nanospheroids for application in intermediate band solar cells}}, journal = {Applied Physics Letters}, volume = {95}, number = {7}, year = {2009}, note = {n/a}, pages = {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.

}, keywords = {APL, CURRENTS, EFFICIENCY, energy gap, nanoparticles, PHOTONS, Plasmonics, Solar cells, Surface plasmons}, isbn = {0003-6951}, doi = {071105 10.1063/1.3205470}, author = {Mendes, MJ and Luque, A and Tobias, I and Marti, A} } @article {Mendes2008a, title = {{Brownian dynamics simulations of single-wall carbon nanotube separation by type using dielectrophoresis}}, journal = {Journal of Physical Chemistry B}, year = {2008}, note = {n/a}, abstract = {n/a}, doi = {10.1021/jp711450w}, url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2{\&}SrcAuth=ORCID{\&}SrcApp=OrcidOrg{\&}DestLinkType=FullRecord{\&}DestApp=WOS{\_}CPL{\&}KeyUT=WOS:000256919800018{\&}KeyUID=WOS:000256919800018}, author = {Mendes, Manuel J and Schmidt, Howard K and Pasquali, Matteo} } @article {Luque2008, title = {{Light absorption in the near field around surface plasmon polaritons}}, journal = {Journal of Applied Physics}, volume = {104}, number = {11}, year = {2008}, note = {n/a}, pages = {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]

}, keywords = {atom, EFFICIENCY, QUANTUM DOTS, SHAPE, SOLAR-CELLS, SPONTANEOUS-EMISSION}, isbn = {0021-8979}, doi = {113118 10.1063/1.3014035}, author = {Luque, A and Marti, A and Mendes, MJ and Tobias, I} } @article {Guedes2006, title = {{Study of synthetic ferrimagnet-synthetic antiferromagnet structures for magnetic sensor application}}, journal = {Journal of Applied Physics}, year = {2006}, note = {n/a}, abstract = {n/a}, doi = {10.1063/1.2162817}, url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2{\&}SrcAuth=ORCID{\&}SrcApp=OrcidOrg{\&}DestLinkType=FullRecord{\&}DestApp=WOS{\_}CPL{\&}KeyUT=WOS:000237404200143{\&}KeyUID=WOS:000237404200143}, author = {Guedes, A and Mendes, MJ and Freitas, P.P. and Martins, J L} }