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Growth of organic semiconductor on heteromolecular layer
Mrhačová, Petra ; Redondo, Jesús (oponent) ; Procházka, Pavel (vedoucí práce)
This master's thesis focuses on the preparation and analysis of heteromolecular layers containing molecules of 1,3,5-benzenetribenzoic acid (BTB) or 4,4'-biphenyl-dicarboxy-lic acid (BDA) along with pentacene molecules on an Ag(111) substrate. the arrangement of molecules in such layers depends on several factors, including the amount of deposited molecules on the surface, the order in which the molecules are deposited, and the degree of deprotonation of their carboxylic groups. Subsequently, the growth of the organic semiconductor pentacene on the heterolayer containing BTB and pentacene molecules was studied. It was observed that the growth occurs in the form of large islands that grow dendritically. However, these islands are not compact but consist of small molecular clusters. All fabricated layers were examined under ultrahigh vacuum (UHV) conditions using a low-energy electron microscope (LEEM) and scanning tunneling microscope (STM).
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Electrical transport properties of molecular materials for smart applications
Ivancová, Anna ; Vala, Martin (oponent) ; Přikryl, Radek (vedoucí práce)
This master´s thesis deals with possibilities of application of new organic molecular materials for electronic devices. Nowadays it is a very attractive field of research, because of the tendencies in industry to miniaturize, reduce production costs and develop new, eco-friendlier, processes of production. The theoretical part of the thesis provides a short overview of organic materials suitable for smart applications and thin films issues including their characterization. The experimental part is dedicated to means how to prepare thin-film electronic components to silicon wafers for thin films field effect transistors. The obtained results in the last part of thesis are discussed about properties of prepared thin films, in the concrete about the electrical transport properties, in the connection with the condition of preparation.
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The synthesis of organic -conjugated systems for advanced photonic applications
Prekopová, Terézia ; Richtár, Jan (oponent) ; Krajčovič, Jozef (vedoucí práce)
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.
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Growth of organic heterostructures on metal surfaces
Kugler, David ; Novák,, Jiří (oponent) ; Procházka, Pavel (vedoucí práce)
Deposition of organic molecules on metal substrate often results in their spontaneous arrangement driven by intermolecular and molecular-substrate interactions. This phenomenon is called self-assembly and can be used to create functional structures with atomic precision. In particular, thin films of organic semiconductors are of growing interest for their potential application in the semiconductor industry. However, the efficiency of such devices is related to the interfacial resistivity at the metal-organic interface. Therefore, the study of the growth type of organic semiconductors on metal substrates is crucial for their future applications. This diploma thesis focuses on the formation of a cover layer of well-ordered 1,3,5-benzene-tricarboxylic acid (BTB) molecules on Ag(111). The main objective of the thesis is to use this cover layer as a substrate for the subsequent growth of pentacene layers, one of the intensively studied organic semiconductors. Coverage by an ordered layer of pentacene with an area suitable for practical applications was achieved. Low-energy electron microscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy were used to study the growth and properties of molecular layers.
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The synthesis of organic -conjugated systems for advanced photonic applications
Prekopová, Terézia ; Richtár, Jan (oponent) ; Krajčovič, Jozef (vedoucí práce)
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.
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Electrical transport properties of molecular materials for smart applications
Ivancová, Anna ; Vala, Martin (oponent) ; Přikryl, Radek (vedoucí práce)
This master´s thesis deals with possibilities of application of new organic molecular materials for electronic devices. Nowadays it is a very attractive field of research, because of the tendencies in industry to miniaturize, reduce production costs and develop new, eco-friendlier, processes of production. The theoretical part of the thesis provides a short overview of organic materials suitable for smart applications and thin films issues including their characterization. The experimental part is dedicated to means how to prepare thin-film electronic components to silicon wafers for thin films field effect transistors. The obtained results in the last part of thesis are discussed about properties of prepared thin films, in the concrete about the electrical transport properties, in the connection with the condition of preparation.
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