Browsing by Author "Lodeiro, Lucas"

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    Effective Interfaces between Fullerene Derivatives and CH3NH3PbI3 to Improve Perovskite Solar Cell Performance
    (2023) Montero-Alejo, Ana L.; Barria-Caceres, Felipe; Lodeiro, Lucas; Menendez-Proupin, Eduardo
    Inverted hybrid perovskite solar cells using fullerene derivatives as an electron transport layer show high energy photo conversion efficiency and improvements in stability. In practice, a wide variety of fullerene derivative functional groups have been proposed, but there is still no clear understanding of the influence of this structure on solar cell behavior. Using density functional theory calculations, we study the conditions that allow the transport of electrons without energetic barriers in the interface formed between the surfaces of CH3NH3PbI3 and the derivatives of fulleropyrrolidine and PCBM. Representative atomistic models of the interfaces are provided, and the self-consistent electronic structures obtained with hybrid functionals were analyzed. It is shown that only the perovskite surface terminated in a layer rich in methylammonium iodide offers electron transport without energy barriers for fullerene derivatives. Moreover, the lead iodide (PbI2)-terminated surface is not passivated with fullerene derivatives. The surface state disappears if the PbI2-terminated surface is treated with ammonium salts or zwitterionic compounds, such as methylammonium chloride and sulfamic acid. Therefore, these modified surfaces favor the performance of the solar cells if the interfaces remain aligned, without barriers, for the transport of electrons. Our study offers these interface models to contribute to the optimal design of perovskite solar cells.
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    Functionalization of Gold Nanostars with Cationic β-Cyclodextrin-Based Polymer for Drug Co-Loading and SERS Monitoring
    (2021) Donoso-Gonzalez, Orlando; Lodeiro, Lucas; Aliaga, Alvaro E.; Laguna-Bercero, Miguel A.; Bollo, Soledad; Kogan, Marcelo J.; Yutronic, Nicolas; Sierpe, Rodrigo
    Gold nanostars (AuNSs) exhibit modulated plasmon resonance and have a high SERS enhancement factor. However, their low colloidal stability limits their biomedical application as a nanomaterial. Cationic beta-cyclodextrin-based polymer (CCD/P) has low cytotoxicity, can load and transport drugs more efficiently than the corresponding monomeric form, and has an appropriate cationic group to stabilize gold nanoparticles. In this work, we functionalized AuNSs with CCD/P to load phenylethylamine (PhEA) and piperine (PIP) and evaluated SERS-based applications of the products. PhEA and PIP were included in the polymer and used to functionalize AuNSs, forming a new AuNS-CCD/P-PhEA-PIP nanosystem. The system was characterized by UV-VIS, IR, and NMR spectroscopy, TGA, SPR, DLS, zeta potential analysis, FE-SEM, and TEM. Additionally, Raman optical activity, SERS analysis and complementary theoretical studies were used for characterization. Minor adjustments increased the colloidal stability of AuNSs. The loading capacity of the CCD/P with PhEA-PIP was 95 +/- 7%. The physicochemical parameters of the AuNS-CCD/P-PhEA-PIP system, such as size and Z potential, are suitable for potential biomedical applications Raman and SERS studies were used to monitor PhEA and PIP loading and their preferential orientation upon interaction with the surface of AuNSs. This unique nanomaterial could be used for simultaneous drug loading and SERS-based detection.