Browsing by Subject "Light harvesting"

Now showing 1 - 4 of 4

Open Access
Ion sensing, light harvesting, energy conversion & self-assembly in rationally designed molecular constructs
(2013) Büyükçakır, Onur
In this thesis, we have constructed rationally designed functional supramolecular systems. In the first chapter, we reported two Bodipy based chemodosimeters to detect fluoride both in solution and in polymethylmethaacraylate (PMMA) matrix. In the second part, we synthesized tetrastyrl-Bodipy derivatives by condensing methyl substituents of 1,3,5,7-tetramethyl-Bodipy dyes with different aromatic aldehydes. The resulting dyes have sharp and intense emission maxima in the near-IR region and they are robust candidates for functional supramolecular systems because of their outstanding properties. In next chapter, we investigated light harvesting properties of these new generation near-IR emissive dyes. In designed light harvesters, a near-IR emissive tetrastyrl-Bodipy dye which was decorated with short wavelength Bodipy fluorophores function as antenna units. In the forth chapter, we reported a Cu(I)-diimine complex as a photosensitizer for dye-sensitized solar cells (DSSC). It was demonstrated that Cu(I) diimine complex with capability of ultrafast electron injection to TiO2 nanoparticles can be a very good candidate for replacing ruthenium based polypyridyl complexes with a much lower cost. This research potentially can generate significant impact for those working on solar energy conversion and DSSC. In the final chapter, we propose to utilize oscillations in pH to move the two components of pseudorotoxane in relation to each other and this is the first example of a pseudorotaxane in which the mobile component is shuttling autonomously.
Open Access
Physics of nonradiative energy transfer in the complex media of 0D, 2D and 3D materials
(2016-07) Yeltik, Aydan
Quantum-confined colloidal nanostructures with strong excitonic properties have emerged as promising light harvesting components in photonics and optoelectronics over the past 20 years. With their favorable photophysical characteristics, three-dimensional-confined colloidal quantum dots and 2D-confined colloidal quantum wells have garnered great attention in the fields ranging from biology and chemistry to physics and engineering. It is technologically significant to utilize the key characteristics of these brightly luminescent nanomaterials through hybridizing and/or interfacing with various technological materials including 3D bulk silicon, graphene based 2D structures such as graphene oxide and reduced graphene oxide, and 2D layered transition metal dichalcogenides such as molybdenum disulphide. Compelling partnership of these appealing materials can be achieved through the nonradiative energy transfer (NRET), which is a phenomenon involving both the exciton and charge transfer mechanisms. Along with the hybrids of low dimensional particles with the conventional bulk materials, the closely interacting structures of these colloidal and layered nanomaterials have widespread interest at both the fundamental science and application levels. From these physical and technological points of view, in this thesis, we addressed important scientific problems and proposed innovative solutions including both the experimental and theoretical approaches in interfacing complex media of 0D, 2D and 3D materials and showing strong NRET interactions. Our key achievements include high excitonic enhancement in silicon and graphene based materials with the integration of nanoparticles, comprehensive photophysical investigation of the newly emerging nanomaterials and successful tailoring of the colloidal nanostructures to the next-generation optoelectronic applications.
Open Access
Synthesis and characterization of near-ir emissive tetra styryl-BODIPY based light harvesting energy transfer cassettes
(2011) Köstereli, Ziya
Light harvesting antenna systems are being used to harvest light through its antenna units. Using these systems, light is channeled into an acceptor chromophore and much more concentrated energy is obtained in acceptor unit with a specific wavelength. In this study, we have rationally designed and synthesized two different novel Förster-type light harvesting energy transfer cassettes which have large stokes shifts and emit in near-IR region. The first cassette has four boradiazaindacene (BODIPY) as donor groups and one tetrastyryl-BODIPY as an acceptor group. The second cassette has four distyryl-BODIPY units as donor groups and one tetrastyryl-BODIPY as an acceptor group. Click chemistry is successfully used to combine donor and acceptor groups to each other. Efficient energy transfer from donor groups to acceptor group in both cassettes was observed and characterized using emission spectrum, quantum yields and lifetimes. Energy transfer efficiencies and rate of energy transfer were calculated and it is demonstrated that there is more efficient energy transfer in cassette that has better overlap in donor emission and acceptor absorption spectrum which is in accordiance with expected behaviour for Förster-type of energy transfer cassettes.
Open Access
Towards unimolecular luminescent solar concentrators: bodipy-based dendritic energy-transfer cascade with panchromatic absorption and monochromatized emission
(2011) Bozdemir, O. A.; Erbas-Cakmak, S.; Ekiz, O. O.; Dana, A.; Akkaya, E. U.
A polymer-embedded dendritic, bodipy-based panchromatic absorber with a built-in energy gradient concentrates incident solar radiation at a terminal chromophore, resulting in a monochromatized emission directed to the sides of the polymer waveguide (see picture). This particular design minimizes self-absorption losses from the peripheral antenna units with an impressive S factor of 10 000.