Deposição de filmes de TiO2 via sol-gel-dip-coating por um método que envolve duas fases, e a montagem de heteroestrutura com SnO2
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Data
2022-03-04
Autores
Pedrini, Luiz Felipe Kaezmarek
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Filmes finos possuem uma variedade de aplicações em diversos campos e tecnologias e uma multitude de formas de serem preparados para tais aplicações. O conhecimento e aplicação de diferentes métodos permite maior controle sobre as propriedades do produto final. Dentre os diversos métodos de preparação, os métodos sol-gel são simples e requerem baixo investimento em equipamento e treinamento na produção de filmes óxidos, o que torna este método interessante para preparação de filmes em diversas escalas, de industrial à acadêmica. Os resultados apresentados aqui, focaram na preparação de filmes de TiO2 , assim como heteroestruturas deste óxido acoplado a SnO2 . A literatura existente sobre esses materiais é extensa e forneceu ampla base a partir da qual foi desenvolvido o método proposto. O método proposto envolveu o controle de parâmetros como escolha de solventes, composição e concentração das fases, viscosidade, pH, velocidade de deposição, tipo de substrato, entre outros para preparação do sistema de duas fases, e o estudo dos efeitos desse método sobre as características elétricas e estruturais dos filmes produzidos são inéditos. Na aplicação de filmes de TiO2 em fotocatálise, filmes depositados pelo método proposto atingiram uma maior eficiência na degradação de azul de metileno devido a mudança em mecânismos de drenagem e à formação de canais eletrônicos em heterojunções formadas, observadas também em heteroestruturas. Investigações de filmes de TiO2 dopados com lantanídeos revelaram novo mecanismo de controle da transição anatase-rutilo assim como um aumento da energia de Urbach relacionado à presença de estados intrabandgap. O método de deposição proposto ainda complementa o método convencional com nova gama de parâmetros para elaboração e desenvolvimento em áreas de sensoriamento de gás, com melhor manipulação de sua superfície, dispositivos eletrônicos transparentes tais como transistores de efeito de campo (FETs) e capacitores.
Thin films posses a variety of applications in many fields and technologies and a multitude of methods to prepare such films for these applications. The sol-gel methods have as advantages its simplicity in the production of oxide films and a lower budget requirement for equipment, becoming interesting as deposition method for films in an industrial scale as well as in academic research. The goal of this work was to study the effects and possible advantages and disadvantages of dip-coating deposition via a two-phase system, applying this proposed method to prepare TiO2 films as well as heterostructures comprised of SnO2 and TiO2 as well as explore this method as a doping procedure. The existing literature developed around these materials is extensive and provides ample base from which to experiment with the proposed method. Aiming for the development of a deposition method that may allow for greater control of thin film properties, several parameters were varied such as: solvent choice, composition and concentration of material in phases, viscosity, pH, deposition speed, substrate, and others. The study of the effects of such method in the films electrical and morphological properties is new and results have shown an increased efficiency on the photocatalitical degradation of methylene blue, with draining regimen changing without a change in deposition speed. The investigation of TiO2 thin films doped with lanthanides has shown a control mechanism in the anatase-rutile transition as well as an increase in the Urbach energy related to intrabandgap states. The proposed deposition method aims to complement the conventional deposition method with a new array of parameters to further develop areas such as gas sensing, with better surface control, and transparent electronic devices, such as field effect transistors (FETs) and capacitors.
Thin films posses a variety of applications in many fields and technologies and a multitude of methods to prepare such films for these applications. The sol-gel methods have as advantages its simplicity in the production of oxide films and a lower budget requirement for equipment, becoming interesting as deposition method for films in an industrial scale as well as in academic research. The goal of this work was to study the effects and possible advantages and disadvantages of dip-coating deposition via a two-phase system, applying this proposed method to prepare TiO2 films as well as heterostructures comprised of SnO2 and TiO2 as well as explore this method as a doping procedure. The existing literature developed around these materials is extensive and provides ample base from which to experiment with the proposed method. Aiming for the development of a deposition method that may allow for greater control of thin film properties, several parameters were varied such as: solvent choice, composition and concentration of material in phases, viscosity, pH, deposition speed, substrate, and others. The study of the effects of such method in the films electrical and morphological properties is new and results have shown an increased efficiency on the photocatalitical degradation of methylene blue, with draining regimen changing without a change in deposition speed. The investigation of TiO2 thin films doped with lanthanides has shown a control mechanism in the anatase-rutile transition as well as an increase in the Urbach energy related to intrabandgap states. The proposed deposition method aims to complement the conventional deposition method with a new array of parameters to further develop areas such as gas sensing, with better surface control, and transparent electronic devices, such as field effect transistors (FETs) and capacitors.
Descrição
Palavras-chave
Filmes finos, Deposição de filmes finos, Dip-coating, Dióxido de titânio, Bifásico, Heteroestruturas, Heterostructure, Biphasic, Titanium dioxide, Thin-films, Photocatalysis