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Interaction of bacteriochlorophyll c and its derivative with titanium dioxide
Ridzoňová, Katarína ; Pšenčík, Jakub (advisor) ; Alster, Jan (referee)
Dye-sensitized solar cells (DSSC) are promising low-cost molecular photovoltaic devices that have a good chance to become a competitor for solar cells based on technology of p-n junction. One of the key components of DSSC is a dye, which is responsible for the capture of light. The main goal of this bachelor thesis is to compare adsorption properties of bacteriochlorophyll c (BChl c) and its modified version referred as bacteriochlorophyllide c (BChlide c) on titanium dioxide (TiO2). In the experimental part of this work interaction of these two sensitizing dyes with TiO2 were investigated by several different methods, including absorption spectroscopy and measuring photo-induced current and current-voltage characteristics of the fabricated DSSC. It has been shown, that BChlide c adsorbs better on the TiO2 layer presumably due to the presence of a carboxylate group. Also the performance of the DSSC based on BChlide c was better than with BChl c.
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Delayed fluorescence of Protoporphyrin IX for medical diagnosis
Vinklárek, Ivo ; Scholz, Marek (advisor) ; Alster, Jan (referee)
The aim of this work is to analyse mechanisms of delayed fluorescence in solutions of protoporphyrin IX mainly through measurements of time-resolved spectroscopy. Delayed fluorescence is a type of fluorescence in which luminophore undergoes reversed intersystem crossing from triplet state to singlet state which is subsequently brought to the ground state by emission of photon. One of the applications of delayed fluorescence is a measurement of oxygen partial tension in mitochondria in vivo. For the right interpretation of the data it is necessary to understand the processes of generation of delayed fluorescence. A new experimental setup for simultaneous time-resolved measurements in infra-red and visible spectral regions was developed and tested as a part of the work. Absorption and fluorescence spectra of protoporphyrin IX were measured under different conditions in dimethylformamide and ethylenglycol solutions. The influence of photodegradation was regarded as well. Then we measured kinetics of protoporphyrin IX with the main focus on the influence of singlet oxygen-sensitized delayed fluorescence. Our research indicates that it participates together with thermal delayed fluorescence, which could be helpful in further interpretation and analysis of the experimental data. The research was carried out in...
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Study of light-harvesting antennae based on bacteriochlorophyll aggregates
Alster, Jan ; Pšenčík, Jakub (advisor) ; Fidler, Vlastimil (referee) ; Balaban, Teodor Silviu (referee)
Title: Study of light-harvesting antennae based on bacteriolorophyll aggregates Author: Jan Alster Department: Department of Chemical Physics and Optics Supervisor of the doctoral thesis: doc. RNDr. Jakub Pšenčík, Ph.D. Abstract: Artificial photosynthesis is a potential future source of renewable energy. e light-to-emical energy conversion process starts with capturing light. Chlorosomes of green phototropic bacteria are probably the most efficient light-harvesting antenna found in the Nature. Moreover, their unique structure based on a self-organised ag- gregate of pigment molecules makes them relatively easy to mimic in vitro. is work explores formation and properties of self-assembled aggregates of bacteriolorophyll molecules in aqueous solvents by means of steady state and time resolved optical spec- troscopy with time resolution in the microsecond to femtosecond range. Various ag- gregation inducing agents have been tested. Isoprenoid quinones introduce a redox- dependent excitation energy quening meanism into the bacteriolorophyll aggre- gates. Carotenoids enhance the light-harvesting properties of the aggregates by cap- turing light in the spectral region where bacteriolorophyll does not and transferring the excitation energy to bacteriolorophyll. e results indicate that self-assembled...
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