Browsing by Author "Ángel Figueroa, Felipe Alfonso"

Now showing 1 - 6 of 6
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    Benzodithiophene-based small molecules for vacuum-processed organic photovoltaic devices
    (2020) Yagui, J.; Ángel Figueroa, Felipe Alfonso
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    Doped Poly(3-hexylthiophene) Coatings onto Chitosan: A Novel Approach for Developing a Bio-Based Flexible Electronic
    (2020) Bonardd Salvador, Sebastián Ignacio; Morales, Natalia; Gence, Loik; Saldías Barros, César Antonio; Ángel Figueroa, Felipe Alfonso; Kortaberria, G.; Leiva Campusano, Ángel
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    Effect of Alkyl Side Chains in BDT and 2D-BDT Small-Molecules as Donor Materials for Vacuum-Processed Organic Photovoltaic Devices
    (WILEY-V C H VERLAG GMBH, 2024) Antoine Ortiz, Cristian Miguel Luis; Vilches Astudillo, Diego Pablo; Preuss, Paulo; Ángel Figueroa, Felipe Alfonso
    Nine molecules based on benzo[1,2-b:4,5-b ']dithiophene (BDT) and 2D-BDT derivatives are studied as donor materials in organic photovoltaic (OPV) devices fabricated by thermal evaporation, aiming to understand how different alkyl lateral substituents affect the molecular packing, the charge transport, and, subsequently, the device performance. Synthesis of the molecules is followed by a comprehensive characterization using thermal and differential scanning calorimetry analyses, which confirm their thermal stability and suitability for vacuum-processed OPV devices. Thermal analysis also demonstrates a strong correlation between the melting point reduction of the molecules and the disorder caused by the alkyl chains. As the synthesized molecules present similar optical properties, the differences in the device performance are caused by the different substituents. BDT derivatives with low melting point temperatures produce reduced current density, hole mobility, and overall device performance, which are attributed to poor molecular packing. Additionally, energy-dispersive X-ray spectroscopy analysis suggests phase separation with fullerene, further impacting the efficiency of the devices. The findings indicate that the photovoltaic performance of BDT-based molecules can be modulated by avoiding aliphatic substituents, providing a strategy for the design of more efficient materials, with thermal evaporation as an ideal method to evaluate and decouple molecular packing from solubility.
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    Micro-estructuración de películas delgadas para la fabricación de celdas fotovoltaicas orgánicas flexibles. Aplicación a ánodos de óxido de indio y estaño (ITO)
    (2024) Soto Pérez, Claudia Paloma; Ángel Figueroa, Felipe Alfonso; Pontificia Universidad Católica de Chile. Instituto de Física
    En este trabajo de tesis se estudió el uso de óxido de indio y estaño (ITO) microestructurado en forma de malla como ánodo en celdas fotovoltaicas orgánicas flexibles. El sustrato usado es tereftalato de polietileno (PET). Se estudió el cambio de la resistencia eléctrica al doblar electrodos de ITO microestructurado con sustrato de PET. Se caracterizó la celda orgánica con estos ánodos en sustrato de vidrio y de PET. Finalmente, se analizó la flexibilidad de las celdas doblándolas y cómo mejorar el experimento. Por medio de litografía óptica, se trabajó con estructuras tan pequeñas como ventanas cuadradas de 2 x 2 µm2 y se logró estructuras con pérdida de 0,7 µm en el ancho de las líneas en vidrio y 0,2 µm en PET. El grabado del ITO en vidrio resultó no ser suficiente, quedando una fina película en las ventanas. Por otro lado, el grabado del ITO sobre PET resultó exitoso. En la prueba de flexibilidad se descubrió que los patrones de malla con ventanas con arista corta (en el sentido del doblado) y de esquinas redondeadas son las que su resistencia eléctrica crece menos, sobre todo los patrones con ventanas y líneas más pequeñas (< 10 µm). Las celdas con sustrato de vidrio tuvieron en promedio: 6,17 ± 0,3 mA/cm2 de densidad de corriente de corto circuito, 0,79 ± 0,03 V de voltaje de circuito abierto y factor de llenado 0,29 ± 0,02. Las celdas con sustrato de PET se fabricaron en dos tandas de evaporación distinta, por lo que las celdas con ITO microestructurado se comparan con la celda de referencia (en PET) de su respectiva tanda. Se llega a tener una diferencia de menos del 3% en la densidad de corriente de corto circuito entre las celdas con ITO microestructurado y su referencia. Después de doblar las celdas, la dos referencias de PET, cuyo ITO es plano, ven su densidad de corriente de corto circuito disminuida un 35% y un 51%. Con ITO microestructurado, disminuye un 99,9% en todas las celdas. Se desconoce cómo y cuánto afecta el patrón en la salud de la capa activa.
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    Thermally evaporated cspbbr3 for green perovskite light-emitting diodes: challenges and perspectives
    (2025) Sosa Acosta, Anabel; Ángel Figueroa, Felipe Alfonso
    Semiconductors based on metal halide perovskites have been extensively studied recently due to their potential as materials for optoelectronic applications. In the realm of cesium-based inorganic perovskite light-emitting diodes (PeLEDs), several aspects are of paramount importance to achieve high photoluminescence (PL) and electroluminescence (EL) of the PeLEDs. The fabrication of CsPbBr3 via thermal evaporation, employing different ratios and stoichiometries, has demonstrated an efficient PL performance in films at high CsBr concentrations. Interface engineering approaches and defect-passivating additives can promote the growth of uniform and high-quality perovskite films. However, such strategies may lead to device degradation, resulting in low stability. Currently, obtaining defect-free thin films is a crucial prerequisite. From a materials perspective, this critical review article covers the composition of the active layer and its effect on the PL and, from the device, the role of additives in obtaining uniform films, assuring optimal charge transport, and electrical injection to achieve high EL.
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    Validation of spectroscopy quantitative method for the synthesis of compositionally-modulated FAPbI3 perovskite films by thermal evaporation
    (Elsevier B.V., 2024) Barria Cáceres ,Felipe Hernán; Ángel Figueroa, Felipe Alfonso
    Aiming at the formation of graded junctions, specifically the utilization of perovskite-perovskite homojunctions, we have successfully developed a reproducible methodology for synthesizing perovskite films using dual deposition of organic and inorganic precursors through vacuum thermal evaporation, forming compositionally modulated FAPbI3-based perovskite materials. These homojunctions leverage the self-compositional doping of perovskite materials, incorporating both n-doped and p-doped films. We employed complementary techniques such as energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and glow discharge optical emission spectroscopy (GDOES) to characterize these films. The combination of our deposition technique and comprehensive spectroscopic analysis provides valuable insights into the composition and properties of the resulting films. By employing this novel methodology, we aim to advance the development of new processing methods for the synthesis of compositionally doped perovskite films and paving the way for their potential applications to fabricate solar cells that include perovskite-perovskite homojunctions, enhancing charge extraction at the interface.