Ultrafast Laser Micro- and Nano- processing

In the Ultrafast Laser Micro- and Nano- processing (ULMNP) laboratory, Savvas Georgiou, of IESL research is focused on the development of novel ultrafast pulsed laser processing schemes for controlled structuring at micro- and nano- scales of a variety of materials, including biopolymers. By applying ultrafast UV and IR laser pulses novel surface structures with sub-micron sized features are produced while the physical properties of semiconductor, dielectric and metallic surfaces are significantly modified. Developed methods include laser micro/nano surface structuring performed in different media, laser-induced forward transfer deposition and combination of those. Further control over the surface topology is achieved by proper functionalization of the 3D structures obtained with well-defined nanostructures. In particular, the artificial surfaces developed by processing under gaseous environments exhibit controlled dual-scale roughness, that mimics the hierarchical morphology of natural surfaces with exciting properties (i.e. the Lotus leaf), comprising micro-conical structures decorated with nanometre sized protrusions. The biomimetic morphology attained gives rise to notable multifunctional properties when combined with methods of tailoring the surface chemistry. Research shows that appropriate combination of topography and chemistry can lead to artificial surfaces that are: (a) of extremely low surface energy, thus water repellent and self-cleaned (b) smart, i.e show the ability to change their surface properties in response to different external stimuli and (c) functional in the sense that exhibit remarkable physical properties compared to the bulk. The ability to tailor the morphology and chemistry is an important advantage for the use of such structures as models to study the dependence of growth, division and differentiation of cells on the surface energy of the culture substrate and as scaffolds for tissue regeneration. At the same time, ULMNP focuses on the ultrafast laser syntheses of various types of nanomaterials including nanolayers. In particular, laser processing in liquid media results in the formation of self-organized surface nanostructures and colloids of surfactant-free nanoparticles used for photovoltaic applications. Additionally, the exploitation of ultrafast laser processing schemes for the synthesis and functionalization of graphene derivatives and other 2D materials for organic electronic applications is investigated. The ULMNP laboratory of IESL-FORTH is dedicated to the memory of Savvas Georgiou.

Solution processed reduced graphene oxide electrodes for organic photovoltaics
Constantinos Petridis, Dimitrios Konios, Minas M Stylianakis, George Kakavelakis, Maria Sygletou, Kyriaki Savva, Pavlos Tzourmpakis, Miron Krassas, Naoum Vaenas, Emmanuel Stratakis, Emmanuel Kymakis, Nanoscale Horizons, 1, 375-382, 2016

Improving stability of organic devices: a time/space resolved structural monitoring approach applied to plasmonic photovoltaics
Barbara Paci, George Kakavelakis, Amanda Generosi, Jonathan Wright, Claudio Ferrero, Emmanuel Stratakis, Emmanuel Kymakis, Solar Energy Materials and Solar Cells, http://dx.doi.org/10.1016/j.solmat.2016.01.003, 2016

Spatial Non-Uniformity in Exfoliated WS2 Single layers
I Paradisanos, N Pliatsikas, P Patsalas, C Fotakis, E Kymakis, G Kioseoglou, E Stratakis, Nanoscale, 8, 16197-16203, 2016

Graphene and transition metal dichalcogenide nanosheets as charge transport layers for solution processed solar cells
Nikolaos Balis, Emmanuel Stratakis, Emmanuel Kymakis, Materials Today, http://dx.doi.org/10.1016/j.mattod.2016.03.018, 2016

Ripple formation on silver after irradiation with radially polarized ultrashort-pulsed lasers
George D Tsibidis, Emmanuel Stratakis, arXiv, 1605.06630, 2016

Convection roll-driven generation of supra-wavelength periodic surface structures on dielectrics upon irradiation with femtosecond pulsed lasers
George D Tsibidis, Evangelos Skoulas, Antonis Papadopoulos, Emmanuel Stratakis, Physical Review B, 94, 8, 081305, 2016

Laser Generated Nanoparticles Based Photovoltaics
C Petridis, K Savva, E Kymakis, E Stratakis, Journal of Colloid and Interface Science, http://dx.doi.org/10.1016/j.jcis.2016.09.065, 2016

Foundation for Research and Technology - Hellas, Heraklion, Greece