Remote plasma assisted fabrication of functional organic and hybrid thin films and supported nanostructures

In general, functional materials are categorized as those materials which possess particular native properties and functions of their own. Examples of these properties are: ferroelectricity, piezoelectricity, magnetism, temperature variations, pressure variations and optical functions. There exists an immense range of functional materials. For instance, optical materials, including lasers, Raman scattering, fluorescence and phosphorescence, are functional materials. Moreover, electrical, magnetics and dielectrics materials are also examples of functional materials, such as semiconducting devices and superconductors, piezoelectrics, ferroelectrics, optical fibres and liquid crystals. On the other hand, functional materials include ceramics, metals, polymers and organic molecules. In recent years, one of the main goals of materials science is the fabrication of new functional materials because of their applications in electronics, informatics and telecommunications. Its continuous development is based on environmental aspects (energy-efficiency, life-cycle issues, recycling or renewable solutions) and cost reduction aspects (energy saving factors in production). The main objective of this thesis is the development of novel multifunctional thin films and supported nanostructures by using remote plasma processes. The thesis is subdivided into eight chapters. At first, Chapter 1 includes the Introduction to the whole work developed throughouth the thesis. Chapter 2 gathers an overview of the thesis in Spanish language. Chapters 3-4 (¿Conformal dielectric organic thin films for molecular electronics¿ and ¿Wetting and anti-freezing properties of adamantane coatings: from thin films to 3D networks¿) study the processability and applications of organic thin films as coatings through its functionalities. These films are fabricated from a precursor of adamantane (C10H16) by RPAVD technique. Separated Chapters 3-4 provide the analysis of two properties of adamantane RPAVD films: dielectric and anti-freezing properties. Later, Annex 1 (¿Adamantane RPAVD: from thin films to 3D networks¿) shows a complete characterization of these adamantane films. After that, this section establishes the control of properties of this type of films, as well as the development of the synthesis of this precursor as supported nanostructures. In addition, it also illustrated that some properties of the films founded in this work can be extended to whole RPAVD materials. Chapter 5, ¿Multicolored emission and lasing in DCM-Adamantane plasma nanocomposites¿ introduces new RPAVD thin films using the combination of a dye laser (4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran, C19H17N3O) and adamantane as precursors. These films exhibit different functionalities that are related to optical properties. In the first instance, this Chapter studies the chemical characterization of the films grown by the mixture of the two precursors. Later, its optical properties are adjusted for a final processing. Finally, it is presented the achievements in the integration of one type of these films in a laser device. Chapter 6 (¿Soft Plasma processing of Organic Nanowires¿) studies a general procedure for the fabrication of hierarchical and hybrid 1D nanostructures from metalloporphyrin, metallophthalocyanine and perylene diimide by plasma processing. The method also provides a template route for the synthesis of supported metal and metal oxide nanostructures by oxygen plasma treatments. In this way, Chapter 7 (¿Highly porous ZnO thin films and 1D nanostructures by remote plasma processing of Zn-phthalocyanine¿) studies the plasma-assisted oxidation of ZnPc in the form of thin film or nanowires to nanostructured ZnO materials. We analyze the characterization of both thin film and supported nanostructures of these hybrid materials. On the other hand, we also evaluate their applications in connection with Annex 2 where we present ZnO thin films from inorganic precursor (ZnEt2) discussed as photonic sensor of oxygen. It is worth to notice that the end of Annex 1 introduces some advances in the synthesis method of functional RPAVD materials. We have developed a new RPAVD structure named nanofabric. Nanofabric is the result of a combination of two accomplishments performed in the present work: the synthesis of hierarchical nanostructures described in Chapter 6, and the process of adamantane by RPAVD detailed in Chapters 3-4 and this Annex

Supported Porous Nanostructures Developed by Plasma Processing of Metal Phthalocyanines and Porphyrins

The large area scalable fabrication of supported porous metal and metal oxide nanomaterials is acknowledged as one of the greatest challenges for their eventual implementation in on-device applications. In this work, we will present a comprehensive revision and the latest results regarding the pioneering use of commercially available metal phthalocyanines and porphyrins as solid precursors for the plasma-assisted deposition of porous metal and metal oxide films and three-dimensional nanostructures (hierarchical nanowires and nanotubes). The most advanced features of this method relay on its ample general character from the point of view of the porous material composition and microstructure, mild deposition and processing temperature and energy constrictions and, finally, its straightforward compatibility with the direct deposition of the porous nanomaterials on processable substrates and device-architectures. Thus, taking advantage of the variety in the composition of commercially available metal porphyrins and phthalocyanines, we present the development of metal and metal oxides layers including Pt, CuO, Fe2O3, TiO2, and ZnO with morphologies ranging from nanoparticles to nanocolumnar films. In addition, we combine this method with the fabrication by low-pressure vapor transport of single-crystalline organic nanowires for the formation of hierarchical hybrid organic@metal/metal-oxide and @metal/metal-oxide nanotubes. We carry out a thorough characterization of the films and nanowires using SEM, TEM, FIB 3D, and electron tomography. The latest two techniques are revealed as critical for the elucidation of the inner porosity of the layers.Ministerio de Ciencia, Innovación y Universidades MAT2016-79866-R, PID2019- 110430GB-C21Consejería de Economía y Conocimiento, Junta de Andalucía P18- RT-348

Simultaneous quantification of light elements in thin films deposited on Si substrates using proton EBS (Elastic Backscattering Spectroscopy)

Quantification of light elements content in thin films is an important and difficult issue in many technological fields such as polymeric functional thin films, organic thin film devices, biomaterials, and doped semiconducting structures. Light elements are difficult to detect with techniques based on X-ray emission, such as energy dispersive analysis of X-rays (EDAX). Other techniques, like X-ray photoelectron spectroscopy (XPS), can easily quantify the content of light elements within a surface but often these surface measurements are not representative of the lights elements global composition of the thin film. Standard Rutherford backscattering spectroscopy (RBS), using alpha particles as probe projectiles, is not a good option to measure light elements deposited on heavier substrates composed of heavier elements like Si or glass. Nuclear Reaction Analysis (NRA) offers a good quantification method, but most of the nuclear reactions used are selective for the quantification of only one element, so several reactions and analysis are necessary to measure different elements. In this study, Elastic Backscattering Spectroscopy (EBS) using proton beams of 2.0 MeV simultaneously quantified different light elements (helium, carbon, nitrogen, oxygen, and fluorine) contained in thin films supported on silicon substrates. The capabilities of the proposed quantification method are illustrated with examples of the analysis for a series of thin film samples: amorphous silicon with helium bubbles, fluorinated silica, fluorinated diamond-like carbon and organic thin films. It is shown that this simple and versatile procedure allows the simultaneous quantification of light elements in thin films with thicknesses in the 200-500 nm range and contents lower than 10 at.%.España Mineco CSD2007- 42 CSD2008-00023 MAT2010-21228 MAT2010-1844

A Full Vacuum Approach for the Fabrication of Hybrid White-Light-Emitting Thin Films and Wide-Range In Situ Tunable Luminescent Microcavities

This study shows the fabrication by a dry approach at mild temperature (<150 °C) of a photoluminescence white light emitting hybrid layer. The white light emitter is obtained by evaporation of two photoluminescent small molecules, a blue (1,3,5-triphenyl-2-pyrazoline (TPP)) and an orange (Rubrene) dye within the porous of an SiO host film fabricated by glancing angle deposition. Fluorescence (Föster) resonant energy transfer between the two organic dyes allows the emission of the combined system upon excitation of the TPP molecule at wavelength of 365 nm. The distribution of the organic molecule within the host layer is analyzed as a function of the substrate temperature and vacuum conditions and the required conditions for the white emission determined by finely controlling the TPP:Rubrene ratio. The full vacuum processing of the hybrid layers provides a straightforward route for the incorporation of the white light emitters as optical defect within 1D Bragg microcavities. As a consequence, directional emission of the system is achieved which allows the development of wide-range in situ tunable photoluminescent devices.Junta de Andalucía TEP8067, FQM-6900, P12-FQM-2265Ministerio de Economía y Competitividad MAT2013-40852-R, MAT2013-42900-

Low temperature plasma processing of platinum porphyrins for the development of metal nanostructured layers

This article establishes the bases for a vacuum and plasma supported methodology for the fabrication at mild temperatures of nanostructured platinum in the form of porous layers and nanocolumns using platinum octaethylporphyrin as precursor. In addition, the application of these materials as tunable optical filters and nano-counterelectrodes is proved. On one hand, the transparency in the ultraviolet-visible-near infrared range can be adjusted precisely between 70% and 1% by tuning the deposition and processing conditions, obtaining a high spectral planarity. Deviations of the spectra from an ideal flat filter are below 4%, paving the way to the fabrication of neutral density filters. The transparency limit values yield a sheet resistivity of ¿1350 and 120 ¿ ¿-1, respectively. On the other hand, the catalytic properties of the nanostructures are further demonstrated by their implementation as counterelectrodes of excitonic solar cells surpassing the performance of commercial platinum as counterelectrode in a 20% of the overall cell efficiency due to simultaneous enhancement of short-circuit photocurrent and open-circuit photovoltage. One of the most interesting features of the developed methodology is its straightforward application to other metal porphyrins and phthalocyanines readily sublimable under mild vacuum and temperature conditions.Junta de AndaluciaTEP8067 FQM-6900 FQM 1851 P12-FQM-2265España MinecoMAT2013-40852-R MAT2013-42900-P MAT2013-47192-C3-3-RMAT2016-79866-RMINECO-CSIC 201560E055

Bending Induced Self-Organized Switchable Gratings on Polymeric Substrates

We present a straightforward procedure of self-surface patterning with potential applications as large area gratings, invisible labeling, optomechanical transducers, or smart windows. The methodology is based in the formation of parallel micrometric crack patterns when polydimethylsiloxane foils coated with tilted nanocolumnar SiO2 thin films are manually bent. The SiO2 thin films are grown by glancing angle deposition at room temperature. The results indicate that crack spacing is controlled by the film nanostructure independently of the film thickness and bending curvature. They also show that the in-plane microstructural anisotropy of the SiO2 films due to column association perpendicular to the growth direction determines the anisotropic formation of parallel cracks along two main axes. These self-organized patterned foils are completely transparent and work as customized reversible diffraction gratings under mechanical activation

White Light Emission: A Full Vacuum Approach for the Fabrication of Hybrid White-Light-Emitting Thin Films and Wide-Range In Situ Tunable Luminescent Microcavities

A wide-range in situ tunable 1D Bragg microcavity including a hybrid layer as white light emitter defect is shown by J. R. Sanchez-Valencia, A. Borras, and co-workers on page 1124. White emission is obtained by Förster resonance energy transfer between blue (1,3,5-triphenyl-2-pyrazoline) and orange (rubrene) dyes homogeneously infiltrated within the host nanocolumnar SiO2 film, which is formed by glancing angle deposition. Sequential physical vapor deposition at low temperatures provides the organic dyes localization within the porous nanostructure of the defect layer.Junta de Andalucía TEP8067 FQM-6900 P12-FQM-2265España Mineco MAT2013-40852-R MAT2013-42900-