Publications by authors named "Juan Ramon Sanchez-Valencia"
Article Synopsis
- The study discusses a new method for creating ultraporous titanium dioxide thin films using plasma deposition and etching, which can be done at room or mild temperatures.
- These films have over 85% porosity, maintain their structure even after high-temperature annealing, and exhibit unique properties like being antireflective and superhydrophilic under UV light.
- The resulting porous films can be used as electrodes in perovskite solar cells and have potential applications in various fields such as energy storage, photonics, and controlled wetting due to their scalable and solvent-free synthesis process.
Article Synopsis
- * It employs finite-difference time-domain simulations to analyze how changing the effective refractive index of phosphor nanocrystal layers impacts decay rates, proposing corrections to previous models.
- * The experimental results validate the model, enabling differentiation between radiative and non-radiative contributions to photoluminescence, and offering methods to adjust the decay rate and improve quantum yield in nanoparticle ensembles.
Article Synopsis
- Polarizers are essential in optoelectronic devices like displays and cameras, but they struggle with significant optical losses when controlling light polarization.
- Organometal halide perovskites (OMHP) offer tunable optical properties and low energy losses, making them ideal for applications in photovoltaics and optoelectronics.
- The study focuses on creating highly aligned methylammonium lead iodide perovskite nanowalls, which enhance light absorption and sensitivity to polarization, paving the way for advanced optoelectronic devices.
Article Synopsis
- A new method for creating tetracene-based nanoribbons using cyclobutadiene linkers was developed through a [2+2] cycloaddition reaction with specially designed precursors.
- Researchers studied the formation process and properties of these structures using various advanced techniques, including scanning tunneling microscopy and atomic force microscopy.
- The findings suggest potential applications in spintronics, as they provide insights into the electronic and magnetic properties of these nanoribbons, which may be useful for future technologies.
Article Synopsis
- * A new method using ultrathin plasma polymer encapsulation at room temperature enhances stability against water and moisture without compromising performance.
- * Encapsulated solar cells show minimal absorbance change even after 30 days in humid conditions and maintain performance when immersed in water, suggesting a significant step toward reliable solar energy technology.
Article Synopsis
- Researchers incorporated a rosamine fluorescent dye into transparent TiO2 and SiO2 thin films using a technique called glancing angle physical vapor deposition (GAPVD).
- They analyzed the dye's adsorption behavior and kinetics through UV-Vis absorption and fluorescence measurements, finding that the process followed a Langmuir isotherm and pseudosecond order kinetics.
- The study revealed the dye's anchoring mechanism and demonstrated that the optimized films showed enhanced sensitivity toward NO2 gas, outperforming other similar films described in previous studies.
Carbon-based nanomaterials such as graphene are at a crucial point in application development, and their promising potential, which has been demonstrated at the laboratory scale, must be translated to an industrial setting for commercialization. Graphene nanoribbons in particular overcome one limitation of graphene in some electronic applications because they exhibit a sizeable bandgap. However, synthesis of bottom-up graphene nanoribbons is most commonly performed under ultra-high vacuum conditions, which are costly and difficult to maintain in a manufacturing environment.
View Article and Find Full Text PDFThe bottom-up approach to synthesize graphene nanoribbons strives not only to introduce a band gap into the electronic structure of graphene but also to accurately tune its value by designing both the width and edge structure of the ribbons with atomic precision. We report the synthesis of an armchair graphene nanoribbon with a width of nine carbon atoms on Au(111) through surface-assisted aryl-aryl coupling and subsequent cyclodehydrogenation of a properly chosen molecular precursor. By combining high-resolution atomic force microscopy, scanning tunneling microscopy, and Raman spectroscopy, we demonstrate that the atomic structure of the fabricated ribbons is exactly as designed.
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- Researchers introduced a new technique called growth assisted by glancing angle deposition (GAGLAD) that combines glancing angle deposition (GLAD) with perpendicular growth of inorganic materials, leading to thin films with a unique microstructure.
- This method allows for better control of microstructure by using materials that typically don't form organized structures through standard GLAD processes, expanding the options for material combinations.
- Examples using silver and zinc oxide demonstrate GAGLAD's capability to create films with remarkable optical properties and highly porous structures, showcasing the technique's versatility and potential applications.
The joining of macroscopic films of vertically aligned multiwalled carbon nanotubes (CNTs) to titanium substrates is demonstrated by active vacuum brazing at 820 °C with a Ag-Cu-Ti alloy and at 880 °C with a Cu-Sn-Ti-Zr alloy. The brazing methodology was elaborated in order to enable the production of highly electrically and thermally conductive CNT/metal substrate contacts. The interfacial electrical resistances of the joints were measured to be as low as 0.
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- * The electronic properties of SWCNTs can switch between metallic and semiconducting states with small structural modifications, making it essential to create 'single-chirality' nanotubes for effective technological applications.
- * This study demonstrates a method to produce targeted monodisperse SWCNTs using molecular precursors and a platinum surface for synthesis, yielding defect-free nanotubes that could enhance technologies like light detectors and transistors.