Research topics

Here's some of the many scientific topics that me and my team have been pioneering via experimental development and prototype demonstration, grounded on advanced modelling:

  • Taking more from photonics: outdoor resilience of PV with enhanced stability and self-cleaning


Our pioneering work with light-trapping has shown that there's much more that can be gained with photonic structuring besides photocurrent enhancement in solar cells. Namely, we have demonstrated unprecedented possibilities for: 1) Self-cleaning, due to the super-hydrophibic properties of photonic nano/micro-structures on the devices' front; 2) Stability improvement, particularly in Perovskite solar cells (PSCs), since the structures protect the devices against UV and humidity penetration which are degradating factors. But there's even more amazing properties that we are exploring, namely for building-integrated PV, such as coloured and/or transparent solar cells. See, for instance: P. Centeno et al. Advanced Materials Interfaces.

  • Solar Fuels: Synergetic Photovoltaic-driven Electrochemical Fuel Synthesis

We are developing photovoltaic (PV) systems endowed with energy storage via a synergetic coupling with electrochemistry (EC). This is achieved by a smart combination between the solar cells and EC flow cells in compact devices that store the energy in synthesized fuels (e.g. hydrogen and/or carbon based), enabling >20% solar-to-fuel efficiency with high operation stability, by capitalizing on: a) high voltage per junction of our PV technology, which is favourable to drive the EC reactions; b) thermal coupling between PV and EC, which naturally provides heat management of both systems, greatly improving their thermal performance. If carbon-based fuels are targeted this will assist in closing the carbon cycle, since CO2 is used as feedstock for the fuel production, in a photosynthesis-like process. See, for instance: A. Lourenço et. al. Materials Today Energy.

  • Wave-optical front structuring for light management in solar cells 

Experimental development, guided by opto-electronic modelling with Lumerical, of optimized photonic front structures, composed of high-index (e.g. TiO2) and/or TCO (transparent conductive oxide) materials produced by our innovative Colloidal-Lithography soft-patterning method. We have demonstrated that such wavelenght-sized micro-structures provide not only strong light-trapping (LT) effects in thin-film Silicon or Perovskite solar cells, but also decrease the sheet resistance of their front electrode. Both effects result in remarkable efficiency enhancements from 20-30% at normal incidence to >50% at oblique incidence (since angular acceptance is also improved). See, for instance: M. J. Mendes et al. Nano Energy.

  • Thin-film silicon solar cells improved with plasmonic back reflectors (PBRs) 

Results of optimized plasmonic back reflectors (PBRs), fabricated by an innovative colloidal wet-coating method developed by myself in IMM-CNR, applied on the rear contact of thin film silicon solar cells produced in CENIMAT-UNINOVA. (a) and (b) show, respectively, a depiction and cross-sectional SEM of the devices with the colloidal metal (Au) nanoparticles (NPs) at the rear, which enable the pronounced broadband photocurrent enhancements observed in the spectral response of the solar cells (c). See, for instance: M. J. Mendes et al. Nanoscale.

  • Plasmonic-enhanced intermediate-band solar cells (IBSCs) 

My PhD work addressed, for the first time, the application of near-field plasmonic effects to boost the absorption in quantum-dot (QD) electronic systems. The strong electric field produced next to the equator of metal nanoparticles sustaining localized surface plasmons can be used to enhance the light absorption in nearby QDs, as depicted in (a). This unprecedented idea can unlock the extraordinary potential of QD intermediate band solar cells (IBSCs), with energy band diagram sketched in (b), since the absorption of the intermediate transitions via the dots can be amplified by more than 2 orders of magnitude when the energy of such transitions matches that of the plasmon resonance, as shown in (c). The results of this work led to a patent (US2013/0092221) and to several publications and presentations.