Stefania Aivali

Incorporating perylene diimide (PDI) into polymeric structures is a promising strategy to suppress its aggregation‐caused quenching. However, achieving this while maintaining desirable material properties remains a challenge. This work aims to the realization of polymeric fluorophores via the incorporation of perylene diimide (PDI) derivatives onto the main chain of poly(arylene ethers) containing different organic chromophores as comonomers. The potentiality of PDI‐based polymers for the emitting layer of organic light‐emitting diodes is studied herein. Different percentages of the perylene diimide derivative were used to ensure emission from the PDI core components, while minimizing their strong π–π stacking tendency and thus their emission quenching. Two different chromophore combinations were employed with the potential to obtain white light‐emitting copolymers. The first involved the use of two fluorophores, namely, a diacetoxystyrylcarbazole derivative along with the perylene moiety. The latter involved the use of a diacetoxystyryl anthracene moiety to facilitate better energy transfer to the perylene moiety. In both cases, the emission of the perylene core component was observed, providing a synthetic strategy to suppress the aggregation tendency of PDI.

For the first time in dye-sensitized solar cell (DSSC) technology, a di-carbazole-based dye was synthesized and evaluated for its usage as a potential sensitizer for the development of wavelength selective semi-transparent DSSCs for greenhouses-oriented applications. The dye was designed to demonstrate a blue light absorption, allowing a high transmittance in the red region of the visible light, even after its adsorption on the anode semiconductor, which is the most important one for the photosynthetic action of the plants. The application of the new dye to DSSCs was examined using either a high-performance iodide-based electrolyte or a highly transparent iodine-free electrolyte to determine a good balance between electric power generation and device transparency. The spectral engineered DSSCs demonstrated quite promising characteristics, providing a high external quantum efficiency (higher than 70%) in the whole blue–green region of the visible light, while allowing high transparency (up to 55%) in the red region, where the second peak in the absorbance spectrum of chlorophyll is located. Finally, the derived results were discussed under the consideration of important metrics for this niche application, including the transparency of the solar cells in the region of photosynthetic active radiation and the attained crop growth factor. The present work constitutes one of the few comprehensive studies carried out up to now in the direction of the development of 3rd generation “agrivoltaics” for their possible integration as cladding materials in energy-autonomous greenhouses.

Conjugation-break flexible spacers in-between π-conjugated segments were utilized herein, towards processable perylene diimide (PDI) based polymers. Aromatic-aliphatic PDI-based polymers were developed via the two-phase polyetherification of a phenol-difunctional PDI monomer and aliphatic dibromides. These polyethers presented excellent solubility and film-forming ability and deep LUMO levels (-4.0 - -3.85 eV), indicating the preservation of the good electron accepting character, despite the non-conjugated segments. Their thermodynamic properties, local dynamics and ionic conductivity demonstrate the suppression of PDI’s inherent tendency for aggregation and crystallization, suggesting PDI-polyethers as versatile candidates for organic electronic applications. Their dynamics investigation using dielectric spectroscopy revealed weak dipole moments arising from the distortion of the planar perylene cores. Blends of the PDI polyethers (serving as electron acceptors) with P3HT (as a potential electron donor component) showed UV-Vis absorbances from 350nm to 650nm and a tendency of the PDI-polyethers to intertwine with rr-P3HT and restrain its the high crystallization tendency.

Perylene diimide (PDI) is one of the most studied functional dyes due to their structural versatility and fine tuning of the materials properties. Core substituted PDIs are prominent n-type semiconductor materials that could be used as non-fullerene acceptors in organic photovoltaics. Herein, we develop versatile organic building blocks based on PDI by decorating the PDI core with quinoline groups. Styryl and hydroxy phenyl mono and difunctionalized molecules were prepared using mono-nitro and dibromo bay substituted PDIs by Suzuki coupling with the respective boronic acid derivatives. A novel methodology using nitro-PDI under Suzuki coupling conditions as an electrophile partner was successfully tested. Furthermore, the PDI derivatives were used for the synthesis of soluble, electron accepting small molecules combining PDI with weak electron withdrawing quinoline derivatives. The new molecules presented wide absorbance in the visible spectrum from 450 to almost 700 nm while their LUMO levels and their energy levels are in the range of −3.8 to −4.2 eV.

Oligomers of the low-band-gap PCDTBT polymer, based on either 3,6 or 2,7 carbazole units, were modified with vinyl ω-chain end functionalities. The vinyl-functionalized oligomers were used as comonomers in free radical polymerizations with quinoline-based monomers such as 6-vinylphenyl-(2-pyridinyl)-4-phenyl-quinoline (vinyl-QPy), and 6-vinylphenyl-(2-perfluorophenyl)-4-phenyl quinoline (vinyl-5FQ). The co-polymeric materials bearing the vinyl-QPy moiety were developed as potential compatibilizers in polymer electron donor–fullerene acceptor blends for non-covalent interactions with the fullerene part. The co-polymeric materials bearing the vinyl-5FQ moiety were developed for the covalent attachment of carbon nanostructures; specifically, PC₆₁BM. Both copolymers and hybrids, after thorough purification, were characterized in terms of their spectroscopic and optical properties as well as their ability to form nanophased separated films as such, or as additives at various percentages into PCDTBT: PC₇₁BM blends.