Browsing by Author "Angel, Felipe A."

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    8-hydroxyquinolinato lithium nano-interlayer in tandem OPV devices
    (SPRINGER, 2022) Neculqueo, Gloria; Angel, Felipe A.
    8-hydroxyquinolinato lithium (Liq) nano-interlayer was evaluated as part of the interconnection layer (ICL) system Liq|Al|MoO3 to produce tandem organic photovoltaic (OPV) devices. First, the thickness dependence of Liq on the performance of single-stack OPV devices was studied, along with its stability by exposing the devices to different degradation conditions. The results confirmed the benefits of incorporating Liq, providing even further stability, particularly to devices exposed to air. Then, symmetrical tandem OPV devices were prepared by optimizing the thickness of the Al interlayer to obtain an efficient ICL. Although limited power conversion efficiencies were obtained due to the symmetry of the device architecture, electrical, optical, and lifetime measurements confirmed Liq|Al|MoO3 as a suitable ICL to achieve tandem OPV devices.
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    Computational chemistry advances on benzodithiophene-based organic photovoltaic materials
    (TAYLOR & FRANCIS INC, 2022) Angel, Felipe A.; Camarada, Maria B.; Jessop, Ignacio A.
    Over the past years, highly efficient conjugated polymers and small molecules have led to the development of organic photovoltaics (OPVs) as a promising alternative to conventional solar cells. Among the many designs, benzodithiophene (BDT)-based systems have achieved outstanding power conversion efficiency (PCE), breaking the 10% PCE barrier in the single-junction OPV devices. However, the precise molecular design of BDT-based materials to tune optical and electrochemical properties, morphology, and interaction between layers remains a challenge. At this point, computational chemistry provides an excellent option to supplement traditional characterization methods and, as a vital tool for designing new systems, understanding their structure-property relationship, predicting their performance, and speeding up OPV research. Hence, this review focused on advances in theoretical simulations of BDT-based OPVs during the last decade. First, a brief introduction of theoretical methodologies, including molecular dynamics simulations and quantum-chemical methods, is given. Then, selected examples of BDT-based materials that have shown great potential to generate high-efficiency devices were reviewed, considering DFT, deterministic, and stochastic methods. Finally, prospects and challenges are pointed out for the future design of improved OPVs.
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    Evaluation of electro-synthesized oligothiophenes as donor materials in vacuum-processed organic photovoltaic devices
    (2023) Camarada, Maria Belen; Saldias, Cesar; Castro-Castillo, Carmen; Angel, Felipe A.
    2,2 ':5 ',2 ''-terthiophene (3Th) was utilized as a precursor in the electro-synthesis of oligothiophenes and their further evaluation as donor materials in the active layer of vacuum-processed organic photovoltaic (OPV) devices. Electro-polymerization conditions were optimized to obtain a controlled fraction of polydisperse oligomers, as demonstrated by size exclusion chromatography (SEC). The polydispersity of the material was further decreased during thermal evaporation, where a reduced fraction of the oligomer was deposited, as observed by SEC, absorption spectroscopy, and the characterization of the fabricated devices. Our results demonstrate for the first time the potential of the electro-synthesis of oligothiophenes as active materials for their application in bulk heterojunction for OPV devices.
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    New Benzotriazole and Benzodithiophene-Based Conjugated Terpolymer Bearing a Fluorescein Derivative as Side-Group: In-Ternal Forster Resonance Energy Transfer to Improve Organic Solar Cells
    (MDPI, 2022) Jessop, Ignacio A.; Cutipa, Josefa; Perez, Yasmin; Saldias, Cesar; Fuentealba, Denis; Tundidor-Camba, Alain; Terraza, Claudio A.; Camarada, Maria B.; Angel, Felipe A.
    A new benzodithiophene and benzotriazole-based terpolymer bearing a fluorescein derivative as a side group was synthesized and studied for organic solar cell (OSC) applications. This side group was covalently bounded to the backbone through an n-hexyl chain to induce the intramolecular Forster Resonance Energy Transfer (FRET) process and thus improve the photovoltaic performance of the polymeric material. The polymer exhibited good solubility in common organic chlorinated solvents as well as thermal stability (TDT10% > 360 degrees C). Photophysical measurements demonstrated the occurrence of the FRET phenomenon between the lateral group and the terpolymer. The terpolymer exhibited an absorption band centered at 501 nm, an optical bandgap of 2.02 eV, and HOMO and LUMO energy levels of -5.30 eV and -3.28 eV, respectively. A preliminary study on terpolymer-based OSC devices showed a low power-conversion efficiency (PCE) but a higher performance than devices based on an analogous polymer without the fluorescein derivative. These results mean that the design presented here is a promising strategy to improve the performance of polymers used in OSCs.