Effect of Al, Ga, and In Doping on the Optical, Structural, and Electric Properties of ZnO Thin Films

ZnO thin films with oxygen vacancies and doped with Al, Ga, and In (Zn1-xMxO1−y (x = 0.03)) have been successfully deposited on soda-lime glass substrates using a simple soft chemical method. The crystalline structure shows a single hexagonal phase of wurtzite with preferred crystal growth along the 002 plane. The surface morphology, characterized by SEM, revealed that the grain shape varies depending on the dopant agent used. Optical measurements displayed an increase in the bandgap values for doped films from 3.29 for ZnO to 3.35, 3.32, and 3.36 for Al, Ga, and In doped films, respectively, and an average transmittance superior to 90% in some cases (in the range between 400 and 800 nm). The electrical response of the films was evaluated with a four-point probe being 229.69, 385.71, and 146.94 Ω/sq for aluminium, gallium, and indium doped films, respectively.We also appreciate the characterization assistance of the Central Service of Scientific Instrumentation (SCIC) at the University Jaume I. We also thank the group of F. Fabregat (INAM-UJI) for the analysis and characterization assistance.This research was funded by Spanish Ministry of Economy and Competitiveness under the program Programa Estatal de I+D+I orientada a los retos de la sociedad (IGNITE Project Ref. ENE2017-87671-C3-3-R) and program Proyectos de I+D+i» de los Programas Estatales de Generación de Conocimiento y Fortalecimiento Científico y Tecnológico del Sistema de I+D+i y de I+D+i Orientada a los Retos de la Sociedad, en el marco del Plan Estatal de Investigación Científica y Técnica y de Innovación 2017-2020 (Ref. PID2020-116719RB-C43)

Optical smoke detector: an approach to semiconductors field for high level education students

Comunicació presentada a EDULEARN2019, 11th International Conference on Education and New Learning Technologies (July 1-3, 2019, Palma, Mallorca, Spain).Nowadays, it is undeniable that the amount of technological devices is having a sharp increase all around us, with important benefits and repercussions for the society. Despite this, students are not used to knowing the basic principles of its operations. Hence, it is of utmost importance to approach undergraduate students to a practical example of a device they can find in their daily life. It is a fact that science is interconnected with multiple disciplines, such as Physics and Solid State Chemistry, Materials Science and Engineering. A good example of it is a smoke detector because it combines both optical and electrical behaviour. Such a device contains a chamber inside which there is an infrared LED (light-emitting diode) and a photodiode (light detector). When the path of light is interrupted by the smoke, according to the principle of light scattering, the smoke will scatter a fraction of light into the photodiode, activating the detector. Thus, detecting low levels of smoke is vital for preventing the fire expansion and occupants can get more time to escape from the premises. The main purpose of this work is to help students to understand the work mechanism of the LED and photodiode in basis of their material composition. In order to do that, a smoke detector is disassembled and its different parts are observed. After that, the microstructure and composition of them are fully analysed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques. With these experiments, students have gained knowledge about semiconductors materials and got a more accurate understanding of their role in these devices. All in all, this experience has allowed them to keep in contact during the whole study with three main concepts of Materials Science: composition, structure and properties. This fact make the work interesting not only from the point of view of students, but also for teachers of Inorganic Chemistry and Materials Science owing to its pedagogical character employing a Problem Based Learning

Photovoltaic Glass Waste Recycling in the Development of Glass Substrates for Photovoltaic Applications

Because of the increasing demand for photovoltaic energy and the generation of end-of-life photovoltaic waste forecast, the feasibility to produce glass substrates for photovoltaic application by recycling photovoltaic glass waste (PVWG) material was analyzed. PVWG was recovered from photovoltaic house roof panels for developing windows glass substrates; PVWG was used as the main material mixed with other industrial waste materials (wSG). The glass was casted by air quenching, annealed, and polished to obtain transparent substrates samples. Fluorine-doped tin oxide (FTO) was deposited as back contact on the glass substrates by spray pyrolysis. The chemical composition of the glass materials was evaluated by X-ray fluorescence (XRF), the thermal stability was measured by differential thermal analysis (DTA) and the transmittance was determined by UV-VIS spectroscopy. The surface of the glass substrates and the deposited FTO were observed by scanning electron microscopy (SEM), the amorphous or crystalline state of the specimens were determined by X-ray diffraction (XRD) and the sheet resistance was evaluated by the four-point probe method. The sheet resistance of the deposited FTO on the wSG substrate was 7.84 ± 3.11 Ω/, lower than that deposited on commercial soda-lime glass (8.48 ± 3.67 Ω/), meaning that this material could present improved conduction of the produced electrons by the photovoltaic effect. This process may represent an alternative to produce glass substrates from waste materials that could be destined for photovoltaic applications, especially the production of ecological photovoltaic windows

Ciència dels materials: metalls, ceràmiques i polímers

Departament de Química Inorgànica i Orgànica. Assignatura: Ciència dels materials. Grau de Química. Codi d’assignatura: QU0926Ministeri d’Economia, Indústria i Competitivitat: Programa estatal d’investigació, desenvolupament i innovació dirigida cap als reptes de la societat (Projecte IGNITE; ENE2017-87671-C3-3-R

Multifunctional silver-coated transparent TiO2 thin films for photocatalytic and antimicrobial applications

Transparent TiO2 thin films coated with Ag NPs were synthesized using two industrially applicable techniques, pulsed laser ablation (PLAL) and spray pyrolysis without using high vacuum. These transparent thin films were deposited on glass in order to generate glass materials with photocatalytic and antimicrobial properties and a minimum loss of transparency. The structural, morphological and optical properties of the thin films were examined using Grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy, Scanning electron microscopy (SEM) and ultraviolet–visible spectroscopy. Transmission electron microscopy (TEM) was used to identify the NPs on the TiO2 surface. The transmittance value for the thin films was greater than 80%.The thin films thus synthesized were then assessed to determine their photocatalytic capacity by monitoring the degradation of Rhodamine B (RhB) under UV light irradiation. Ag NPs on the TiO2 surface ensures an improvement in the photocatalytic properties, with a 99% degradation of RhB in 210 min under UV light. In addition, these transparent thin films showed high antimicrobial activity on Gram-negative bacteria when irradiated by UV light for 4 h, killing 93% of these bacteria.Funding for open access charge: CRUE-Universitat Jaume

Functional properties of transparent ZnO thin films synthetized by using spray pyrolysis for environmental and biomedical applications

Spray pyrolysis is a promising method for producing thin, transparent films on glass substrates. ZnO thin films synthesized by this method exhibit high crystallinity, adhesion and chemical resistance. They also possess the ability to degrade water pollutants and exhibit antibacterial properties under UV light. The crystalline structure of these films has been studied using grazing X-ray diffraction (GIXRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM), while transmission electron microscopy (TEM) has been used to investigate their composition and purity. Other techniques such as X-ray photoelectron spectroscopy (XPS), Raman spec-troscopy and ultraviolet-visible spectroscopy were also employed. ICP-OES was used to evaluate photocatalyst leaching. These transparent thin films have exceptional optical properties, with a transmittance of 95%. The photocatalytic degradation of 4-Nitrophenol (4-NP) by ZnO thin films showed a degradation rate of 94% in 270 min with a kinetic constant value of 3.1 x 10-3 mM/min. The films are also highly durable and reusable, exhibiting superior performance compared to other ZnO photocatalysts. The bactericidal activity of these transparent films was also evaluated, with a value of 60.6% being obtained using Escherichia coli after irradiating the films with UV light for 3 h.Funding for open access charge: CRUE-Universitat Jaume IFunding for open access charge: CRUE-Universitat Jaume

Synthesis of mono- and bis-imidazolinium salts for the preparation of N-Heterocyclic carbene Au(I) complexes

Treball Final de Grau en Química. Codi: QU0943. Curs acadèmic: 2017/2018The purpose of this current project can be considered twofold. Firstly, it intends to develop a new gold(I) complex. Secondly, it seeks to explore the relationship between the structural features and the catalytic behavior. In order to understand this aim better, it can be divided into the following: - Synthesis of mono- and bis-imidazolinium salts. - Design a family of mono- and bis-imidazolidine ligand precursors, and study their coordination abilities. - Evaluation of the catalytic activities of the resulting metal complexe

Cicloadiciones 1-3 dipolares de alquinos y azidas, usando un catalizador de cobre soportado sobre grafeno reducido mediante interacciones no covalentes

Treball final de Màster Universitari en Química Aplicada i Farmacològica. Codi: SIM138. Curs acadèmic: 2018/2019El objetivo de este trabajo es estudiar las propiedades catalíticas de un complejo de cobre e inmovilizarlo sobre la superficie de grafeno reducido por interacciones no covalentes, con el fin de generar un catalizador heterogéneo de la misma especie. Los objetivos concretos se dividen en: - Síntesis y caracterización de las sales de imidazolio utilizadas como precursores de ligandos. - Síntesis del complejo Cu-NHC y caracterización por H RMN, C RMN, difracción de rayosX y MS. - Síntesis y caracterización del material Cu-NHC-rGO mediante HRTEM y ICP. - Estudio de la actividad catalítica del complejo en la cicloadición 1,3 de alquinos a azidas. (“Click reaction”) - Estudio del reciclado y estabilidad del catalizador Cu-NHC-rGO

Enhanced Electrical Properties of Alkali-Doped ZnO Thin Films with Chemical Process

Doped ZnO are among the most attractive transparent conductive oxides for solar cells because they are relatively cheap, can be textured for light trapping, and readily produced for large-scale coatings. Here, we focus on the development of alternative Na and K-doped ZnO prepared by an easy low-cost spray pyrolysis method for conducting oxide application. To enhance the electrical properties of zinc oxide, alkali-doped Zn1−x MxO (x = 0.03) solid solutions were investigated. The resulting layers crystallize in a single hexagonal phase of wurtzite structure with preferred c-axis orientation along a (002) crystal plane. Dense, well attached to the substrate, homogeneous and highly transparent layers were obtained with great optical transmittance higher than 80%. The optical energy band gap of doped ZnO films increase from 3.27 to 3.29 eV by doping with Na and K, respectively. The electrical resistivity of the undoped ZnO could be decreased from 1.03 × 10−1 Ω.cm to 5.64 × 10−2 Ω.cm (K-doped) and 3.18 × 10−2 (Na-doped), respectively. Lastly, the carrier concentrations increased from 5.17 × 1017 (undoped ZnO) to 1 × 1018 (doped ZnO)

ZnO/Ag Nanocomposites with Enhanced Antimicrobial Activity

In this study, ZnO/Ag nanocomposites were synthesized using a facile chemical route involving metallic precursors of zinc acetate dehydrate and silver acetate, and dissolving the two metallic precursors in EtOH. The final concentration of the solution was 0.4 M. The different nanocomposites were synthesized using different atomic percentages of silver to compare the amount of silver nanoparticles with the bactericidal power of the nanocomposites. They were prepared at concentrations of 0, 1, 3, 5, 7, and 10 at%. The as-prepared nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) to study their structural and morphological properties. SEM showed that there is a clear effect of Ag on the size of the ZnO particles, since when silver percentages of 1 at% are included, the grain size obtained is much smaller than that of the ZnO synthesis. The effect is maintained for 3, 5, 7, and 10 at% silver. Transmission electron microscopy (TEM) compositional mapping confirms the presence of spherical nanoparticles in the synthesized samples. The size of the nanoparticles ranges from about 10 to about 30 nm. In addition, UV-Vis and Raman spectroscopy were performed to obtain structural details. The different samples show an increase in the absorption in the visible range due to the incorporation of the silver NPs. Measurement of the antimicrobial activity was tested against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) It is shown that zinc oxide has bactericidal power for these two groups of bacteria and also that when it is used together with silver NP, this effect improves, eliminating more than 90% of inoculated bacteria.The authors would like to acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness under the program Ministerio de Ciencia e Innovación «Proyectos de I+D+i» de los Programas Estatales de Generación de Conocimiento y Fortalecimiento Científico y Tecnológico del Sistema de I+D+i y de I+D+i Orientada a los Retos de la Sociedad, en el marco del Plan Estatal de Investigación Científica y Técnica y de Innovación 2017–2020. Ref. PID2020-116719RB-C43.We also appreciate the characterization assistance provided by the Central Service for Scientific Instrumentation (SCIC) at the Universitat Jaume I. Arnau Pérez Salvador for the help in experimentation during the completion of the final degree project