Examinando por Autor "Vergaz, Rcardo"

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Identification of Degradation Mechanisms in Slot-Die-Coated Nonfullerene ITO-Free Organic Solar Cells Using Different Illumination Spectra
(ACS, 2020-07-27) Arredondo, Belén; del Pozo, Gonzalo; Hernández-Balaguera, Enrique; Martin-Martin, Diego; López-Gonzalez, Maria del Carmen; Romero, Beatriz; Lopez-Fraguas, Eduardo; Vergaz, Rcardo; Quintana, Xabier; Lamminaho, Jani; Destouesse, Elodie; Ahmadpour, Mehrdad; Turkovic, Vida; Madsen, Morten
In this work, we have studied degradation mechanisms of nonfullerene-based organic solar cells with PET/Ag/ZnO/ PBDTB-T:ITIC/PEDOT:PSS/CPP PEDOT:PSS device structure. We compare pristine and degraded samples that were subjected to outdoor degradation following the standard ISOS-O2 protocol. The ideality factors for different incident wavelengths obtained from open-circuit voltage vs irradiation level and current density-voltage (J-V) measurements at different temperatures indicate that for aged samples recombination is governed by the Shockley-Read-Hall mechanism occurring in a region near the anode. Samples were also characterized using impedance spectroscopy (IS) and fitted to an electrical model. Impedance parameters were used to obtain mobility, indicating a clear degradation of the active layer blend for aged samples. The change in the chemical capacitance also reveals a worsening in carrier extraction. Finally, two-dimensional (2D) numerical simulations and fits to experimental J-V curves confirm the existence of a layer near the anode contact with poorer mobility and a decrease in the anode work function (WF) for the degraded samples.
Visible Light Communication system using an organic emitter and a perovskite photodetector
(Elsevier, 2019-10-01) Lopez-Fraguas, Eduardo; Arredondo, Belén; Vega-Colado, Cesar; del Pozo, Gonzalo; Najafi, Mehrdad; Martin-Martin, Diego; Galagan, Yulia; Sanchez-Pena, José Manuel; Vergaz, Rcardo; Romero, Beatriz
The past few years have seen a great increase in the development of Visible Light Communication systems (VLC), mainly triggered by the wide variety of situations they can be used in. These communication systems have traditionally employed inorganic light emitters and photodetectors. In this work, we present a VLC system using an organic emitter and a perovskite photodetector, both fabricated using low cost processing techniques. Perovskite devices have been widely studied as photovoltaics cells since they have achieved great efficiencies, and, in the recent years, there is also an intense research of these devices as photodetectors. In this work, we have fabricated and characterized a perovskite photodetector with layer structure ITO/PTAA/Perovskite/PCBM/ BCP/Cu, and integrated it in a visible communication system to successfully link an audio signal.