Examinando por Autor "Dalchiele, Enrique A."

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    Ítem
    Comparative analysis between nanorods and nanowires by using depolarized and diffuse light
    (Elsevier, 2021) Valente, Paulo; Seré, Andrés; Pereyra, Carlos J.; Campo, Lucía; Spera, Enzo; Castillo, Judith; Helvia, Samuel A.; del Río, Rodrigo; Ramírez, Daniel; Riveros, Gonzalo; Álvarez, Katherine; González, Bárbara; Marotti, Ricardo E.; Dalchiele, Enrique A.
    Changes in the polarization state of light due to its interaction (reflection and transmission) with samples of CuSCN nanorod and ZnO nanowire arrays are analyzed and compared following a recently proposed technique (Valente et al., 2019). The determination of the degree of polarization and measurements of diffusive light are used to investigate the influence of the morphology of nanorods and nanowires on the optical properties. It is shown that the CuSCN nanorods are better than ZnO nanowires to preserve polarization, although the degree of polarization decreases with the lengths for both materials. It is shown that the degree of polarization correlate with the diffusive light, which allow an estimation of the large scale uniformity of the samples. However, it is also shown that the loss of polarization quality can be present even in absence of diffusion, which indicates that the interferometric effect on the nanoscale should be an important cause of the depolarizing effect.
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    Ítem
    Electrochemically Assisted Growth of CsPbBr3-Based Solar Cells Without Selective Contacts
    (European Chemical Societies Publishing, 2020) Ramírez, Daniel; Riveros, Gonzalo; Díaz, Patricia; Verdugo, Javier; Núñez, Gerard; Lizama, Susy; Lazo, Pamela; Contreras-Bernal, Lidia; Riquelme, Antonio; Idigoras, Jesús; Dalchiele, Enrique A.; Gau, Daniel L.; Marotti, Ricardo E.; Anta, Juan A.
    In this work we report a simple and cost-effective CsPbBr3- based solar cell without ordinary selective contacts. To do so we follow an electrochemical approach consisting of three successive steps: (1) electrodeposition of PbO2 directly on top of FTO substrates, (2) heterogeneous phase reaction with gaseous HBr and (3) spin-coating of methanolic CsBr solutions followed by annealing. This method is more adequate for large- scale environmentally friendly production as it reduces chemical waste, particularly toxic lead. The resulting films were structurally and optically characterized showing good coverage of the FTO substrates, absence of defects such as pinholes and orthorhombic structure. Photovoltaic and impedance characterization was carried out by pressing a carbon coated metal spring onto the CsPbBr3 film until obtaining maximized opencircuit potential (Voc) and short-circuit photocurrent density (jsc) under simulated sunlight. The stabilized current at fixed voltage (SCFV) technique gave a maximum PCE value of 2.70% close to devices with similar configuration. Impedance measurements demonstrated analogous behavior to that of state-of-art CsPbBr3 based solar cells, comprising a recombination arc at midhigh frequencies, geometrical capacitance and ideality factors closed to 2, typical of SRH recombination in the perovskite bulk.
  • Miniatura
    Ítem
    Study of the Nucleation and Growth Mechanisms of Copper Electrodeposition on Bare and Nitrogen-Doped Reduced Graphene Oxide Modified SnO2:F/glass Substrates
    (The Electrochemical Society, 2020) Riveros, G.; León, M.; Ramírez, D.; Hernández, L.; Martín, F.; Romero, R.; Dalchiele, Enrique A.
    In this article, the influence of a nitrogen-doped electrochemically reduced graphene oxide layer on the nucleation and growth mechanisms of copper electrodeposition was studied. Thus, copper electrodeposition from an acidic solution was evaluated using two different substrates: fluorine-doped tin oxide (FTO), and fluorine-doped tin oxide covered with a nitrogen-doped reduced graphene oxide layer (FTO/N-ERGO). In both cases, chronoamperometric curves were obtained, which were analyzed and deconvoluted using pre-established models and equations, where the different contribution and nucleation parameters were determined. Field emission scanning electron microscopy (FESEM) images were acquired in order to observe the morphology and verify the nuclei density for each case considered in this study. In the case of copper electrodeposition onto FTO, an instantaneous three-dimensional nucleation was observed, together with a proton reduction reaction. When FTO/N-ERGO was used as a substrate, a new instantaneous two-dimensional nucleation process was observed in addition to the processes previously described. Furthermore, the increased density of active sites and the changes in copper morphology are directly related with the N-ERGO layer, which also increased the kinetic constant for the proton reduction reaction and the nucleation rate per active site during the copper electrodeposition process.