We proposed a flexible electronics with functional poly (arylene ether)s and discotic liquid crystal. Firstly, we provided a series of the PAE polymer with remarkable thermal stability and high optical transmittance. The PAEs were synthesized via nucleophilic displacement as polymerization on a 2-trifluoromethyl-activated bisfluoro monomer, which reacted with bisphenols. Thermal analysis indicated the PAEs possessed a high glass transition point of ~300¢J and the decomposition temperature Td=500¢J at a weight loss of 5%. Additionally, high transmittance of 85%, low dielectric constant of ~2.0, and well mechanical property of the PAE films were experimentally verified, as a high potential substrate for flexible electronics. Two kind of device structure has been prepared, were organic thin film solar cell and Dye sensitized solar cell. Furthermore, we provided the self-assembled triphenylene-based liquid crystal and its polymer derivative to apply for photovoltics. The 2, 3, 6, 7-tetra-6-octyloxydibenzo[a,c]phenazine-11-carboxylic group and the polymer of merging with disc-unit and polyacrylamide. Both show a highly isotropic phase transition point of ~270¢J and the decomposition temperature Td~450¢J at a weight loss of 5%. The specific absorption in visible light region was at 200 - 450 nm. A distinct self-arrangement of columnar array was investigated by optical textures. The self-arranged pathway enhanced carrier mobility due to £k-£k conjugation in hexagonal column stacking. Finally, the PAEs and DLC materials applied to thin film solar cell (ITO/PEDOT:PSS/DLC-PAM/P3HT:PCBM/Al) as hole transporting layer. The photo-conversion efficiency was strong depending on organic compounds, such as molecular structure, photo-physic and chemical properties. On the basis of integrated characteristics, it suggested a high potential as flexible electronics for photovoltics.

We take 5,6,11,12,17,18-hexaaztrinaphthylene and dibenzo[a,c]phenazine as our central core that with dove-tailed side chains. It is shown that the size-related increase of steric interactions among the peripheral side chains substituted to the aromatic core leads to a dramatically lowered isotropization temperature.

We take the electron deficient heterocyclic hexaazatriphenylene (HAT) as our central core and readily synthesized by the condensation of hexaketo- cyclohexane with the respective 1,2-bis-alk-oxy-4,5-diaminobenzene. We use the polarised optical microscopy (POM) and differential scanning calorimetry (DSC) to study the mesophase range.These mesophases are identified as columnar phases by diffraction (XRD).

In this PhD thesis, there are two major motifs: dibenzo[a,c]phenazine- and 2,3-diphenylquinoxaline novel discogens and fluorous polycatenar liquid crystals. The thermo properties of these new compounds were elucidated using optical microscopy, differential scanning calorimetry and powder X-ray diffraction. In the phenanthroline series (Chapter 2), 1,10-phenanthroline core incorporated into dibenzo[a,c]phenazine structure exhibit columnar mesophases with extremely wide width. X-ray diffraction study pinpoints to that half-shaped mesogens with reduced symmetry has preferential intra-molecular parallel conformation in the mesophase. This molecule has gel ability with different solvents. In dimeric crown ether series (Chapter 3A), 2,3-diphenylquinoxaline-based mesogens containing dibenzo-18-crown-6 has hexagonal columnar mesophase with extremely narrow width. Incorporation potassium metal ion into crown moiety dramatically enhanced mesomorphic stability and for metal complexes, as side chain increases, hexagonal mesophases predominate over rectangular mesophases. Furthermore, both in hexagon or rectangle, per columnar slice consist of two molecules. All of prolonged long glassy formation up to one year at room temperature. In monomeric crown ether series (Chapter 3B), metal-free molecules fail to be mesomorphic, but complexation with lithium and sodium metals enhanced thermo stability and rectangular mesophase (C2mm) were found. Also, per columnar slice was comprised of four molecules. Last (Chapter 4), a series of tri- and tetra-catenar mesogens containing various combinations of hydrocarbon and semiperfluorocarbon chains has been prepared to elucidate the fluorophlic-fluorophobic effect on mesomorphism. Tricatenar with one terminal semiperfluoro- and two hydrocarbon chains are aligned into lamellar periodicity driven by the mutual incompatibility of the hydrocarbon and fluorocarbon portions. But unsymmetric tetracatenar mesogens show rectangular mesophase.

Discotic liquid crystals (DLC) have been reported with a large number of discoid cores to improve the degree of intermolecular ordering because the liquid crystals own to self-assembly into columnar stacking and self¡Vhealing ability. In my research, a series of disc-like £k-conjugated molecules based on aromatic rigid cores have been newly synthesized. I focus on the hexaazatrinaphthylene (HATN) and dibenzo-[a,c]- phenazine as aromatic cores, changing different side chains to control the mesomorphic behavior and their supermolecular assembly.

Unsymmetrical discotic liquid crystals based on hexaazatriphenylene(HAT) have not been published until today.We have used tetrahydoxyquinone as the starting material to synthesis unsymmetrical discotic liquid crystals based on HAT and investigate their properties of liquid crystal.

This dissertation describes the study of organic thin-film solar cells in pursuit of affordable, renewable, and environmentally-friendly energy sources. Particular emphasis is given to the molecular ordering found in liquid crystalline or polycrystalline films as a way to leverage the efficiencies of these types of cells. Maximum efficiencies estimated based on excitonic character of organic solar cells show power conversion efficiencies larger than 10% are possible in principle. However, their performance is often limited due to small exciton diffusion lengths and poor transport properties which may be attributed to the amorphous nature of most organic semiconductors.Discotic liquid crystal (DLC) copper phthalocyanine was investigated as an easily processible building block for solar cells in which ordered molecular arrangements are enabled by a self-organization in its mesophases. An increase in photocurrent and a reduction in series resistance have been observed in a cell which underwent an annealing process. X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements suggest that structural and morphological changes induced after the annealing process are related to these improvements.In an alternative approach, p-type pentacene thin films prepared by physical vapor deposition were incorporated into heterojunction solar cells with C60 as n-type layers. Power conversion efficiencies of 2.7 % under broadband illumination (350-900 nm) with a peak external quantum efficiency of 58 % have been achieved with the broad spectral coverage across the visible spectrum. Analysis using an exciton diffusion model shows this efficient carrier generation is mainly due to the large exciton diffusion length of pentacene films. Joint XRD and AFM studies reveal that the highly crystalline nature of pentacene films can account for the observed large exciton diffusion length. In addition, the electrical characteristics are studied as a function of light intensity using the equivalent circuit model used for inorganic pn-junction solar cells. Dependences of equivalent-circuit parameters on light intensity are further investigated using a modified equivalent circuit model, and their effects on the overall photovoltaic performance are discussed.

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Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-07-21T16:17:26Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) ATUALIZADA DISSERTAÇÃO_ARTHUR_UFPE_.pdf: 6640779 bytes, checksum: 54162674f1fcaee2b4fef8836f21cd72 (MD5) / Made available in DSpace on 2016-07-21T16:17:26Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) ATUALIZADA DISSERTAÇÃO_ARTHUR_UFPE_.pdf: 6640779 bytes, checksum: 54162674f1fcaee2b4fef8836f21cd72 (MD5) Previous issue date: 2016-03-30 / CNPQ / O estudo das propriedades de materiais orgânicos tem chamado atenção devido sua versatilidade estrutural e de composição que podem moldar suas propriedades físicas e químicas. Neste trabalho preparamos seis cromóforos rígidos contendo o heterociclo tiazolo[5,4-d]tiazol (Thz) como espaçador aromático, e grupos terminais piridínicos ou carboxílicos. Desta forma trabalhamos com duas linhas de pesquisa: foto-eletroquímica para os derivados piridínicos e síntese e caracterização de cristais líquidos (CLs). Investigamos as propriedades fotoquímicas e processos redox das bipiridinas X,X'-(tiazolo[5,4-d]tiazol-2,5- dil)bis(piridil) (X,X’ = 2,2’; 3,3’ ou 4,4’). Em solução, apresentaram propriedades acidocrômica via foto- e eletrodissociação de solventes clorados. A seguir, preparamos sais de trifluoracetato dos bipiridínio (viologens), que apresentaram propriedades fotocromáticas via transferência de elétron quando expostos à radiação UVB. Utilizamos os derivados carboxílicos como centros rígidos para a preparação de cristais líquidos. Escolhemos o grupo carboxilato como precursor sintético dos conectores orgânicos: éster, amida e 1,3,4-oxadiazol. Planejamos os cristais líquidos contendo tais conectores e cadeias alquílicas dodeciloxi (-OC12H25), obtendo materiais com estrutura geral: centro rígido + conectores + cadeias alcóxi. De acordo com a estrutura dos centros rígidos, preparamos treze mesógenos calamíticos (ácido tiazolo[5,4- d]tiazol-2,5-dicarboxílico), das quais seis apresentaram mesofases calamítica (comportamento esperados) e três apresentaram mesofases discóticas. O fotocromismo apresentado pelos sais de bipiridinas frente à radiação UVB nos permite sugerir aplicações como dosimetria desta radiação, presente na luz solar. As propriedades mesomórficas ainda estão em estudo. No entanto, conseguimos obter CL’s discóticos a temperatura ambiente e uma mesofase discótica nemática, bastante rara. / The study properties of organic materials has drawn attention due to its structural versatility and composition versatility, which can shape their physical and chemical properties. In this work, we prepared six rigid chromophores containing the heterocycle thiazolo[5,4-d] thiazole (Thz) as aromatic spacers, and pyridyl or carboxylic terminal groups. Hence, we have worked with two research lines: photo-electrochemistry for the pyridine derivatives and synthesis and characterization of liquid crystals (LCs). We investigated the photochemical properties and redox processes of the bipyridines X,X'-(thiazolo[5,4-d] thiazole-2,5-diyl)bis(pyridyl) (X,X' = 2,2 '; 3,3' or 4,4 '). In solution, these compounds showed acidochromic properties via photonand electrodissociantion of chlorinated solvents. Next, we prepare bipyridinium trifluoroacetate salts (viologens), which exhibited photochromic properties through electron transfer when exposed to UVB radiation. We used the carboxylic derivatives as rigid centers for the preparation of liquid crystals. We chose the carboxylate group as a synthetic precursor of organic connectors: esther, amide, and 1,3,5-oxadiazole. We plannned the liquid crystal containing these connectors and the alkoxy chains dodecyloxy (-OC12H25), obtaining materials with general structure: rigid center + connectors + alkoxy chains. According to the rigid center structure, we obtained thirteen calamitic (acid thiazolo [5,4-d] thiazole-2,5-dicarboxylic acid), six of which had mesophases calamítica (expected behavior) and three had discóticas mesophases. The photochromic presented by bipyridinium salts when exposed of UVB radiation allows suggest applications such as dosimetry of sunlight radiation. The mesomorphic properties are still under study. However, we obtained room temperatures discóticos LCs, as well as a nematic discótica mesophase which are quite rare.