National Repository of Grey Literature 4 records found  Search took 0.00 seconds. 
The synthesis of organic -conjugated systems for advanced photonic applications
Prekopová, Terézia ; Richtár, Jan (referee) ; Krajčovič, Jozef (advisor)
This diploma thesis is focused on the synthesis of new, organic, -conjugated systems with potential use in the field of singlet fission (SF). It is one of the most efficient multiexciton generation processes studied so far, which offers the potential to increase the efficiency of solar cells. The theoretical part focuses on the description of SF and the molecules providing this phenomenon. The first aim of the experimental part is focused on the synthesis of target pentacene and anthracene derivatives. The work presents and verifies three synthetic approaches to the preparation of these molecules, of which only one has proven to be successful. The second aim deals with the synthesis of intermediates that are crucial for the preparation of target pyrene fused pyrazaacenes. The synthesis consists of the oxidation of pyrene and the condensation of 4,5-diketone or 4,5,9,10-tetraketone with commercially available diamines or diamines prepared by us. A basic optical characterization was performed on these derivatives, which showed the effect of substitution on excimer emission. Assuming the same quantum fluorescence yield for all molecules and comparing the spectral measurements, it was found that the solid phase excimer emission is significantly higher than in solution.
(Spectro) Electrochemical Study of Cibalackrot Derivatives – Potential Chromophores for Singlet Fission\n
Šimková, Ludmila ; Lušpai, Karol ; Klíma, Jiří ; Ludvík, Jiří
Recently, substantial attention has been paid to the search for suitable chromophores for singlet fission. This photophysical effect promises to increase the maximum of theoretical efficiency of solar cells. One type of candidates are derivatives of cibalackrot. Redox properties are critical for their use. Our electrochemical work is focused on the study of oxidation and reduction of a series of substituted cibalackrot derivatives using classic voltammetric techniques and their combination with in situ UV-vis and EPR spectroscopy. The results show the reversible formation of the radical anion (cation) in the first reduction (oxidation) step enabling determination of ´´electrochemical´´ HOMO-LUMO gap.
The synthesis of organic -conjugated systems for advanced photonic applications
Prekopová, Terézia ; Richtár, Jan (referee) ; Krajčovič, Jozef (advisor)
This diploma thesis is focused on the synthesis of new, organic, -conjugated systems with potential use in the field of singlet fission (SF). It is one of the most efficient multiexciton generation processes studied so far, which offers the potential to increase the efficiency of solar cells. The theoretical part focuses on the description of SF and the molecules providing this phenomenon. The first aim of the experimental part is focused on the synthesis of target pentacene and anthracene derivatives. The work presents and verifies three synthetic approaches to the preparation of these molecules, of which only one has proven to be successful. The second aim deals with the synthesis of intermediates that are crucial for the preparation of target pyrene fused pyrazaacenes. The synthesis consists of the oxidation of pyrene and the condensation of 4,5-diketone or 4,5,9,10-tetraketone with commercially available diamines or diamines prepared by us. A basic optical characterization was performed on these derivatives, which showed the effect of substitution on excimer emission. Assuming the same quantum fluorescence yield for all molecules and comparing the spectral measurements, it was found that the solid phase excimer emission is significantly higher than in solution.
Redox Properties of Quasi Dimer of 1,3-diphenylisobenzofuran for Singlet Fission
Šimková, Ludmila ; Ludvík, Jiří
Molecules on the base of 1,3-diphenylisobenzofuran attract an interest because of their\npossible efficiency for singlet fission This study is focused on electrochemical behaviour of\nthe „quasi dimer“ of 1,3-diphenylisobenzofuran. For characterization of reduction mechanism\nin situ UV-vis and EPR spectroscopy were used. The monomer 1,3-diphenylisobenzofuran\nand its CH2 dimer were added to this study for comparison. The redox properties of both\ncompared molecules are similar. The location and the nature of the covalent bridging unit in\nCH2dimer have small effect onthe redox potentials. But the pi-conjugation in the molecule of\nquasi dimer causes approximately 0.2 V easier oxidization and reduction.

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