As an important type of organic semiconductors, organic small molecule crystals have great potential for low-cost applications such as plastic solar cells (PSC), organic light emitting diodes (OLED) and organic field-effect transistors (OFET). Among numerous molecular crystals, 6, 13-Bis(triisopropylsilylethynyl)pentacene (Tips-pentacene) has aroused much attention because it combines good solubility in common solvents and strong π-π stacking from self-assembly. However, the inability to achieve ordered array of Tips-pentacene prevents the fabrication of high-performance organic integrated circuits. In this work, two new fabrication methods to pattern Tips-pentacene micro- and nano-scale single crystals are proposed. Both methods are facilitated by nanofabrication techniques such as nanoimprint and photolithography. In the first method, the surface of a silicon substrate is treated by surfactant coating and Tips-pentacene single crystals are deposited in squared patterns. In the second method, we made an ordered array of Tips-pentacene single crystals confined in Teflon-AF patterns. In both techniques, the effects of solvent type, processing temperature and template pattern size on crystal morphology and size are systematically studied.

Submitted by MAIZA DA SILVA OZÓRIO null (ozoriounesp@gmail.com) on 2018-02-26T15:23:33Z No. of bitstreams: 1 dissertação_maiza_versão_final_corrigida.pdf: 3955466 bytes, checksum: 08f98a38963076999f04ee08c2e89954 (MD5) / Approved for entry into archive by Claudia Adriana Spindola null (claudia@fct.unesp.br) on 2018-02-26T16:14:51Z (GMT) No. of bitstreams: 1 ozorio_ms_me_prud.pdf: 3955466 bytes, checksum: 08f98a38963076999f04ee08c2e89954 (MD5) / Made available in DSpace on 2018-02-26T16:14:51Z (GMT). No. of bitstreams: 1 ozorio_ms_me_prud.pdf: 3955466 bytes, checksum: 08f98a38963076999f04ee08c2e89954 (MD5) Previous issue date: 2016-06-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Um dos atuais desafios da eletrônica orgânica é a obtenção de semicondutores com alta mobilidade que forme filmes com boa morfologia quando depositado/impresso por solução, resultando em boa uniformidade e reprodutibilidade dos dispositivos. O poli(3- hexiltiofeno) (P3HT) e o 6,13-(triisopropilsililetinil)pentaceno (TP) estão entre os semicondutores orgânicos mais utilizados. O TP tem como característica a formação de estruturas cristalinas, e desse modo, apresenta mobilidade muito maior que o P3HT, no entanto é difícil de obter filmes com boa morfologia e resultados reprodutíveis. Visando um material semicondutor que apresente mobilidade significativamente melhor que a do P3HT e uma morfologia melhor que a do TP, estudou-se compósitos a partir da mistura destes materiais (P3HT:TP) para aplicação em transistores orgânicos de efeito de campo (OFETs), utilizando óxido de alumínio anodizado (Al2O3) tratado com HMDS como dielétrico de gate. Para análise da morfologia dos compósitos semicondutores de P3HT:TP usou-se microscopia eletrônica de varredura (MEV), microscopia de força atômica (AFM) e microscopia óptica (MO). Análise óptica foi feita através de medidas de fotoluminescência (PL) e de tempo de decaimento por fotoluminescência. Espectroscopia Raman e FTIR foram utilizadas para análises estruturais. No modo transistor a caracterização foi feita através de curvas de saída e transferência. Através das caracterizações elétricas determinou-se os parâmetros do semicondutor, tais como, mobilidade, voltagem limiar de chaveamento e razão entre o estado ligado e desligado. A morfologia da blenda semicondutora apresentou características específicas de cada material, ressaltando a formação de aglomerados. Observou-se diferenças bastantes consideráveis na morfologia do compósito em função da variação do solvente e da cinética de deposição dos filmes. Imagens de MEV mostram regiões cristalinas do TP dispersas na matriz polimérica do P3HT, onde o tamanho, forma e distribuição dos cristalitos dependem do tratamento dado à superfície do isolante. O aumento da concentração de TP dificulta a formação de compósitos com boas características. A melhor mobilidade foi obtida com o compósito 50P3HT:50TP, apresentando valores na ordem de 10- 3 cm2V -1 s -1 . / One of the current challenges of organic electronics is the development of semiconductors with high mobility to form films with good morphology when deposited/printed by solution, resulting in good uniformity and reproducibility of the devices. The poly (3-hexylthiophene) (P3HT) and 6,13-(triisopropilsililetinil)pentacene (TP) are among the most widely used organic semiconductors. The TP films are constituted by crystalline lamellar structures, and thus has greater mobility than the P3HT, however, it is difficult handling it to obtain films with good morphology and reproducible results. Targeting a semiconductor material with significantly better mobility than that of P3HT and better morphology than that of TP, we studied composites of these materials (P3HT: TP) for using in organic field effect transistors (OFETs). The transistor was prepared depositing the solution of the semiconductor composite, by spin coating, on the aluminium oxide, obtained by anodization and treated with HMDS, followed by the thermal evaporation of gold on the top, to form the drain and source electrodes. For analysis of the morphology of the composites semiconductors (P3HT: TP) was used scanning electron microscopy (SEM), atomic force microscopy (AFM) and optical microscopy (OM). Optical analysis was performed using photoluminescence (PL) measurements and decay time by photoluminescence. FTIR and Raman spectroscopy were used to structural analysis. In mode transistor, characterization was performed using output and transfer curves. Through the electrical characterizations determined the semiconductor parameters such as mobility, threshold-switching voltage and the ratio between the current in “on” and “off” states. The morphology of the semiconductor composite presented specific characteristics of each material, emphasizing the formation of agglomerates. It has been observed quite considerable differences in the morphology of the composite depending on the solvent and the variation of the film deposition kinetics. SEM images show crystalline regions TP dispersed in the polymeric matrix of P3HT, where the shape, size and distribution of crystallites depend on the treatment of the surface of the dielectric. The increase in TP concentration hinders the formation of composites with good characteristics. The best mobility was obtained with the composite 50P3HT: 50TP, with values in the order of 10- 3 cm2V -1 s -1 .