Arranjo supramolecular em filmes finos de perileno: dependência com a estrutura molecular e com a temperatura e efeito sobre as propriedades ópticas
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Data
2021-10-13
Autores
Fernandes, Jose Diego
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Universidade Estadual Paulista (Unesp)
Resumo
Filmes finos de materiais orgânicos vêm sendo utilizados em diversas aplicações e seu arranjo supramolecular (espessura, organização molecular, morfologia, cristalinidade e agregados) é um fator determinante para suas propriedades ópticas e elétricas, implicando na escolha da aplicação tecnológica. Nesta tese de doutorado, filmes finos de dois derivados de perileno (bis butilimido perileno - acrônimo BuPTCD - e bis fenetilimido perileno - acrônimo PhPTCD) foram fabricados pelas técnicas de deposição física a vapor (PVD, do inglês Physical Vapor Deposition) e Langmuir-Shaefer (LS). Os objetivos foram investigar a influência da estrutura química das moléculas de BuPTCD e PhPTCD sobre o arranjo supramolecular nos filmes PVD e LS, e determinar como este arranjo influencia as propriedades ópticas (absorção e emissão) dos filmes finos. Os resultados obtidos neste trabalho indicam que diferenças na estrutura química molecular produz arranjos supramoleculares distintos e, consequentemente, influencia as propriedades ópticas dos filmes finos. Os filmes PVD e LS de BuPTCD apresentaram maior quantidade de agregados H, são mais cristalinos e têm menores valores de rugosidade quando comparados aos filmes PVD e LS, respectivamente, de PhPTCD. Ao comparar os filmes fabricados pela mesma técnica, foi verificado que a eficiência radiativa (ER) dos filmes fabricados com o BuPTCD é maior que do PhPTCD. Os resultados indicaram que a ER não depende apenas dos agregados J (agregados emissores), mas também de outros tipos de agregados moleculares e da cristalinidade. Complementarmente, verificou-se que a conversão interna (CI) entre os estados eletrônicos S2→S1 diminui nos filmes quando agregados moleculares e cristalinidade são favorecidos. Portanto, este trabalho demostrou que conhecer o arranjo supramolecular e sua influência sobre as propriedades ópticas é fundamental para a otimização de dispositivos optico-eletrônicos.
Thin films of organic materials have been used in several applications and their supramolecular arrangement (thickness, molecular organization, morphology, crystallinity and aggregates) is a determining factor for their optical and electrical properties, implying the choice of technological application. In this PhD thesis, thin films of two perylene derivatives ((bis(butylimido)perylene - BuPTCD - and bis(phenetylimido)perylene - PhPTCD)) were produced by physical vapor deposition (PVD) and Langmuir-Shaefer (LS) techniques. The objectives were to investigate the influence of the chemical structure of the BuPTCD and PhPTCD molecules on the supramolecular arrangement of the PVD and LS films, and to determine how this supramolecular arrangement influences the optical properties (absorption and emission) of thin films. The PVD and LS films of BuPTCD showed a higher amount of H aggregates, greater crystallinity and lower values of roughness when compared with PVD and LS films, respectively, of PhPTCD. When comparing films made using the same technique, it was found that the radiative efficiency (ER) of films made with BuPTCD is greater than that of PhPTCD. The results indicated that the RE depends not only on J aggregates (emitting aggregates), but also on other types of molecular aggregates and crystallinity. In addition, it was found that the internal conversion (CI) between S2 → S1 decreases in films when molecular aggregates and crystallinity are favored. Therefore, this work demonstrated that knowing the supramolecular arrangement and its influence on optical properties is fundamental for the optimization of optical-electronic devices.
Thin films of organic materials have been used in several applications and their supramolecular arrangement (thickness, molecular organization, morphology, crystallinity and aggregates) is a determining factor for their optical and electrical properties, implying the choice of technological application. In this PhD thesis, thin films of two perylene derivatives ((bis(butylimido)perylene - BuPTCD - and bis(phenetylimido)perylene - PhPTCD)) were produced by physical vapor deposition (PVD) and Langmuir-Shaefer (LS) techniques. The objectives were to investigate the influence of the chemical structure of the BuPTCD and PhPTCD molecules on the supramolecular arrangement of the PVD and LS films, and to determine how this supramolecular arrangement influences the optical properties (absorption and emission) of thin films. The PVD and LS films of BuPTCD showed a higher amount of H aggregates, greater crystallinity and lower values of roughness when compared with PVD and LS films, respectively, of PhPTCD. When comparing films made using the same technique, it was found that the radiative efficiency (ER) of films made with BuPTCD is greater than that of PhPTCD. The results indicated that the RE depends not only on J aggregates (emitting aggregates), but also on other types of molecular aggregates and crystallinity. In addition, it was found that the internal conversion (CI) between S2 → S1 decreases in films when molecular aggregates and crystallinity are favored. Therefore, this work demonstrated that knowing the supramolecular arrangement and its influence on optical properties is fundamental for the optimization of optical-electronic devices.
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Palavras-chave
Arranjo supramolecular,, Derivado de perileno, Filmes finos, Propriedades ópticas, Supramolecular arrangement, Perylene derivative, Thin film, Optical propertie