FONDECYT 11130501
FONDECYT Iniciación “Developing methodologies based on computational techniques to study reconstruction and field evaporation in Atom Probe Tomography“.
Joaquín Peralta (PI)
This project aims to develop new techniques and models relating field evaporation experiments and phenomenology with computational simulations, based in classical and quantum physics. In particular we focus on two main goals: i) the use of computational techniques to improve the reconstruction process provided by Atom Probe Tomography; and ii) the implementation of models that describe the effect of high electric field in the degradation of materials, focusing primarily on metallic compounds.
FONDECYT 1181840
FONDECYT Regular (2018-2021): “Biomimetic Catalysts for the Oxygen Reduction Reaction“
Federico Tasca (PI, USACH) and W. Orellana (Co-PI)
In this proposal we show preliminary results that indicate we can obtain even better catalysts optimizing the electron withdrawing character of the pyridine axial ligand. For example instead of a pyridine axial ligand we used 3-nitropyridine and 2,6-dichloropyridine. We believe that the increased activity and stability of FeN5 is correlated to a low spin state of the Fe electrons because of an empty 3dz2 orbital and the following easiness for the interaction with O2. To confirm the spin state of the electron in the FeN5, EPR experiments and DFT calculations are planned. Also we are applying for XAS experiments at the LNLS beamlines to probe the binding energy of the O2-FeN5.
A good catalyst for the ORR should be also a good catalyst for the opposite reaction, which is the oxygen evolution reaction. In nature those catalysts exists and employ either a Fe – Cu metal centers or 3 Cu clusters. Within the aims of the proposal we want to reproduce those sites by N coordination of various phthalocyanines. Finally those catalysts will be also evaluated for the ORR and OER. The last reaction of interest for our group is the CO2 reduction. Many research groups have reported that MN4 catalysts are very active for this reaction and therefore the MN5 catalysts will be evaluated also for this reaction.
FONDECYT 11180590
FONDECYT Iniciación First principles study of hexagonal strain for materials-bydesign and novel phenomena
Sebastian E. Reyes-Lillo (PI)
Transition metal oxides display a wide range of technological properties including ferroelectricity, magnetism, photocatalysis, superconductivity and topological phases. Previous experimental and theoretical work, mostly focused on perovskites, has shown that cubic (001) epitaxial strain can stabilize metastable phases, induce coupling mechanisms between structural, electronic and magnetic degrees of freedom, and enhance functional properties. Our hypothesis is that hexagonal (111) epitaxial strain, a type of anisotropic strain that has received considerable less attention among perovskites, is fundamentally different than the (001) case, and can lead to the design of new functional materials and the discovery of new physical phenomena.
FONDECYT 1170480
FONDECYT Regular (2017-2020): Metal-organic 2D materials for clean energy conversion: First-principles calculations
Walter Orellana (PI)
In this proposal we will investigate, from a theoretical/computational point of view, two-dimensional metal-organic structures based on metallophthalocyanine and metalloporphyrin for light-harvesting applications. The same structures will be also investigated as catalysts for key energy conversion processes. The main goal of this proposal is the generation of advanced knowledge in low-cost materials toward solar energy conversion. Our Specific goals of this proposal are:
- Study the stability, electronic and optical absorption properties of metal-organic 2D polymeric structures based on metalloporphyrin and metallophthalocyanine oligomers, considering different metal centers.
- Investigate the electronic and optical absorption properties of selected metal-organic 2D structures adsorbed on semiconducting TiO2 and ZnO surfaces, suggesting functional materials for organic/inorganic solar cells.
- Investigate the electrocatalytic activity of selected metal-organic 2D structure toward oxygen reduction and water oxidation, looking for low-energy reaction pathways.
User proposal #5100
Molecular Foundry User Proposal “First principles study of facet-dependent photovoltaic efficiency in hybrid halide perovskites“
Sebastian E. Reyes-Lillo (PI) and Jeffrey B. Neaton
Abstract:
Hybrid organic-inorganic halide perovskites, e.g. MAPbI3, (MA = CH3NH3), are a promising class of materials for photovoltaic (PV) applications due to outstanding power conversion efficiencies and low fabrication costs. In a recent work, the PV efficiency of MAPbI3-xClxsolar cells were locally probed and mapped at nanometer atomic-scale using unique capabilities at the Molecular Foundry. Photoconductive measurements on MAPbI3-xClxcrystals revealed a strong intra-gain and inter-grain heterogeneity and spatial correlation between different crystal facets. The heterogeneity has a direct impact on the overall efficiency of the device and was attributed to variations on surface trap densities with crystal orientation. The atomic origin of the heterogeneity remains largely unexplored, and further investigation of the relation between PV performance and crystal orientation can lead to higher PV efficiency and the discovery of new physical phenomena.
In this work, in collaboration with Jeffrey B. Neaton, we propose to build upon our previous work and use first principles DFT-methods to investigate the facet-dependent PV efficiency of MAPbI3. The measured heterogeneity is likely to arise due to the relative stability of localized charged defects states (e.g. vacancies and polarons) with different crystal orientations. We therefore propose to study the impact of lattice strain, crystal orientation and surface termination on the structural and optoelectronic properties of bulk and surface charged defects of halide perovskites. The aim of this work is to ultimately guide experimental growth techniques to increase the efficiency of this class of materials.
Proyectos Finalizados Recientemente
2017
FONDECYT Regular (2013-2017): “Study of impurities, complex defects, and boundaries in CdTe thin films using computer simulation at the atomic scale“, Eduardo Menéndez (PI, UChile) and W. Orellana (Co-Pi)
2016
Proyecto ANILLO CONICYT ACT-1107 (2013-2016): “Integration of structural biology to the development of bionanotechnology“, W. Orellana (Investigador Principal)
Departamento de Ciencias Físicas
Facultad de Ciencias Exactas,
Sazie 2212, Piso 7, Santiago, Chile
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