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Growth of organic semiconductor on heteromolecular layer
Mrhačová, Petra ; Redondo, Jesús (referee) ; Procházka, Pavel (advisor)
Tato diplomová práce se zabývá přípravou a analýzou heteromolekulárních vrstev obsahujících molekuly kyseliny 1,3,5-benzentribenzoové (BTB) nebo kyseliny 4,4'-bifenyl-dikarboxylové (BDA) spolu s pentacenovými molekulami na substrátu Ag(111). Uspořádání molekul v takových vrstvách závisí na několika faktorech, jako je množství deponovaných molekul na povrchu, pořadí, v jakém jsou molekuly deponovány, a míra deprotonace jejich karboxylových skupin. Následně byl studován růst organického polovodiče pentacenu na heterovrstvě obsahující BTB a pentacenové molekuly. Bylo zjištěno, že růst probíhá ve formě velkých ostrůvků, které se rozrůstají dendriticky. Tyto ostrůvky však nejsou kompaktní, ale skládají se z malých molekulových klastrů. Všechny vytvořené vrstvy byly zkoumány v podmínkách ultravysokého vakua (UHV) pomocí nízkoenergetického elektronového mikroskopu (LEEM) a rastrovacího tunelového mikroskopu (STM).
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Organic bicomponent layers formed by electron acceptors and donors on metals
Šebestová, Zuzana ; Průša, Stanislav (referee) ; Krajňák, Tomáš (advisor)
This bachelor thesis is focused on the description of preparation and characterization of bicomponent layers made of organic molecules tetracyanoquinodimethane (TCNQ) and 4,4’-biphenyl dicarboxylic acid (BDA) on Ag(111) substrate under ultra high vacuum (UHV) conditions. The work initially focuses on covering the Ag(111) surface with individual molecules separately, and then on the co-deposition of both molecules simultaneously. The influence of the order and duration of depositions on the resulting mixed structure is examined. This thesis also includes the results of mixed structures formed by fully protonated and deprotonated BDA molecules. A low-energy electron microscope (LEEM) and a scanning tunneling microscope (STM) were used to subsequently characterize the fabricated heteromolecular structures. The measured data of the mixed structures were complemented by reciprocal and real space models with a specified unit cell.
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Characterisation of TCNQ and 5A heteromolecular layers on Ag(100)
Cohl, Alexandr ; Jakub, Zdeněk (referee) ; Stará, Veronika (advisor)
This bachelor thesis deals with the formation and subsequent characterization of mixed phases of pentacene (5A) and tetracyanoquinodimethane (TCNQ) on the surface of a Ag(100) monocrystal. The preparation of these mixed phases was carried out by deposition from an effusion cell in ultra-high vacuum (UHV) conditions. The quality and arrangement of the formed layers were then characterized by low-energy electron microscopy (LEEM) and scanning tunneling microscopy (STM). The behaviour and arrangement of monomolecule layers of both TCNQ and 5A on the surface is also described. Mixed phases with different ratios of 5A and TCNQ and the effect initial coverage and deposition order have on the formation of the final structure are discussed as well. Ultraviolet photoelectron spectroscopy (UPS) measurements are used to compare the electronic properties of the 5A and TCNQ monomolecule layers with the 1:1 mixed phase.
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Growth of organic semiconductors on polycrystalline foils
Weisz, Hugo ; Průša, Stanislav (referee) ; Procházka, Pavel (advisor)
This bachelor thesis is focused on the utilization of silver and copper polycrystalline foils as substrates for the deposition of 4,4’-biphenyl-dicarboxylic acid (BDA). The first part of the experimental work focuses on the cleaning of polycrystalline foils, especially under ultra-high vacuum conditions. Silver and copper polycrystalline films were characterized using photoemission electron microscopy (PEEM) and low-energy electron microscopy (LEEM) before and after molecular deposition.
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Electric and dielectric properties of organic materials for photovoltaic applications
Florián, Pavel ; Nešpůrek, Stanislav (referee) ; Zmeškal, Oldřich (advisor)
Diploma thesis deals with the use of organic materials in photovoltaic applications and the study of their electric and dielectric properties. The theoretical part of thesis deals issue of the use of organic polymeric materials in photovoltaics and their advantages and disadvantages. Next are the results of various studies of organic solar cells by other authors. In the practical part of the work are shown experimental results (volt-ampere characteristics and impedance spectra) of samples of organic semiconductors and their evaluation.
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Organic solar cells for photovoltaic conversion of solar energy
Šedina, Martin ; Zmeškal, Oldřich (referee) ; Weiter, Martin (advisor)
This work is focused to study organic materials for solar energy conversion into electricity and characterization of conversion processes. Materials and their blends with semiconducting properties such as photoconductivity were studied. Thin films of organic materials and their blends were prepared by spin-coating method and characterized by optical methods (UV-VIS and photoluminiscence spectroscopy), by current-voltage characteristics, by impedance spectroscopy method, spectral response measurement of photocurrent and method of transient photoconductivity. Structural factors influences the conversion of solar energy into electricity were observed. Based no these results, the materials and their blends useful for photovoltaic applications were determined. The dependence between photoconductivity of thin films and theirs structure was also discussed.
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Bio-inspired materials for aplications in organic electronics
Meindl, Jiří ; Pospíšilík, Karel (referee) ; Krajčovič, Jozef (advisor)
The bachelor ‘s thesis is a literary research, which summarise perspective bioinspired materials for organic electronic applications. Mainly focused are bioinspired and biocompatible materials in this thesis. The main area of interest is synthesis, characterization and application of these semiconducting materials. The first part of the thesis is focused on indigo, 6,6‘-dibromoindigo and thiophen derivatives of isoindigo copolymers. The second part of the thesis is all about biocompatible materials and applications of these materials in bio-protonic electronics. Malein-chitosan is described in this part as role model substance of bio-protonic electronics.
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Modelling of organic electrochemical transistors
Truksa, Jan ; Omasta, Lukáš (referee) ; Salyk, Ota (advisor)
The topic of this work is the making of a virtual model of a circular organic electrochemical transistor (OECT) and its electric field, and comparison of the computed results to a real system of rotationally symmetrical electrodes. The electric potential field in the transistor was modelled using the finite element method and the electric field and current field were determined using the results. Later, the electric potential field was mapped in a real system of aluminium electrodes, submerged in water. The electric field model of an unusually configured circular OECT is presented in this work. Due to insufficient computing capacity, the model had to be significantly simplified. The computed results agree with the experimentally determined potential field despite the simplification. The deviations of the model output characteristic from real OECT characteristic were caused by simplifying the model in respect to reality.
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