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Identifier

000402883

Title

Laser development of novel materials and diagnostics for organic photovoltaic applications

Alternative Title

Εφαρμογή τεχνικών laser για την ανάπτυξη νέων υλικών και διαγνωστικών τεχνικών με σκοπό την εφαρμογή τους σε οργανικές φωτοβολταϊκές διατάξεις

Author

Συγλέτου, Μαρία

Thesis advisor

Φωτάκης, Κωνσταντίνος

Reviewer

Τζανετάκης, Παναγιώτης
Κιοσέογλου, Γεώργιος

Abstract

Over the past decade, the need for low-cost and solution-processed materials, ideal for photovoltaic applications, has experienced particular attention in global scientific research. Organic semiconducting materials exhibit large potential for photovoltaic energy conversion. The major attention for organic photovoltaics (OPVs) originates from the fact that organic compounds are of much lower cost than silicon or any of the PV materials available to date, as well as that can be fabricated using low temperature solution processed techniques. In order to become more competitive, organic photovoltaic technologies must overcome two main problems: low efficiency and short lifetime. Further research effort towards increasing PCE as well as improving device lifetime is required. Working in this direction, we studied the effect of the incorporation of surfactant-free metallic nanoparticles into the active layer of OPV cells, on the efficiency and stability of the device. Such systems have demonstrated to be a very promising strategy to enhance the OPV performances, due to localized surface plasmon resonance (LSPR) or multiple LSPR effects, light scattering or multiple light scattering effects, the synergy of those , the plasmonic effects of metal NPs clusters or the utilization of multiple metal NPs, as well as the BHJ blend structure improvement. In this work, the metallic nanoparticles were laser-synthesized with the method of laser ablation of solid in liquid medium. Moreover, laser techniques were developed for the fabrication of hybrid 2D materials with metallic nanoparticles in solution in order to exploit both the contribution of NPs in the light absorption enhancement and the band gap tunability of the 2D materials in order to achieve higher exciton dissociation and charge collection for their potential application in ternary devices. The NS-NPs assemblies were formed under ambient conditions, via a facile, rapid and solution compatible laser assisted process in the presence of a metallic precursor. The resulting hybrid materials have been incorporated into the photoactive layer as the third component in a ternary OPV device along with polymer/fullerene composites. The concept of photochemical synthesis in solution was also used for the fabrication of graphene based materials for their application as electron acceptors in OPV devices. Graphene-based nanostructured materials appear to be attractive alternatives in a range of new energy devices, including organic photovoltaic cells, lithium batteries, fuel cells and supercapacitors. The resulting graphene-based materials have been incorporated into the photoactive layer of OPV devices and have been applied as electron-acceptor materials, replacing the most used fullerene derivative PC₇₁BM. Finally, the structures of the laser synthesized materials used, as well as the optimization of the fabricated OPVs have been evaluated by utilizing various spectroscopy and microscopy analyses, alongside with complementary photovoltaic measurements.

Language

English

Subject

Efficiency

Laser ablation

Laser induced fluorescence spectroscopy

Metallic nanoparticles

Photochemical synthesis of new materials

Photoluminescence spectroscopy

Stability

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