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3. Transferable classical force field for pure and mixed metal halide perovskites parameterized from first principles

Author

Seijas-Bellido, Juan Antonio, Samanta, Bipasa, Valadez-Villalobos, Karen, Gallardo, Juan Jesús, Navas, Javier, Balestra, Salvador R. G., Madero-Castro, Rafael María, Vicent-Luna, Jose Manuel, Tao, Shuxia, Toroker, Maytal Caspary, and Anta, Juan Antonio

Subjects
Condensed Matter - Materials Science
Abstract

Many key features in photovoltaic perovskites occur in relatively long time scales and involve mixed compositions. This requires realistic but also numerically simple models. In this work we present a transferable classical force field to describe the mixed hybrid perovskite MA$_x$FA$_{1-x}$Pb(Br$_y$I$_{1-y}$)$_3$ for variable composition ($\forall x,y \in [0,1]$). The model includes Lennard-Jones and Buckingham potentials to describe the interactions between the atoms of the inorganic lattice and the organic molecule, and the AMBER model to describe intramolecular atomic interactions. Most of the parameters of the force field have been obtained by means of a genetic algorithm previously developed to parameterize the CsPb(Br$_x$I$_{1-x}$)$_3$ perovskite. The algorithm finds the best parameter set that simultaneously fits the DFT energies obtained for several crystalline structures with moderate degrees of distortion with respect to the equilibrium configuration. The resulting model reproduces correctly the XRD patterns, the expansion of the lattice upon I/Br substitution and the thermal expansion coefficients. We use the model to run classical molecular dynamics simulations with up to 8600 atoms and simulation times of up to 40~ns. From the simulations we have extracted the ion diffusion coefficient of the pure and mixed perovskites, presenting for the first time these values obtained by a fully dynamical method using a transferable model fitted to first principles calculations. The values here reported can be considered as the theoretical upper limit for ion migration dynamics induced by halide vacancies in photovoltaic perovskite devices under operational conditions.

Published
2021
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5. Water vapour pressure as determining control parameter to fabricate high efficiency perovskite solar cells at ambient conditions

Author

Contreras-Bernal, Lidia, Gallardo, Juan Jesus, Navas, Javier, Idigoras, Jesus, and Anta, Juan A.

Subjects
Physics - Applied Physics
Abstract

Although perovskite solar cells have demonstrated impressive efficiencies in research labs (above 23%), there is a need of experimental procedures that allow their fabrication at ambient conditions, which would decrease substantially manufacturing costs. However, under ambient conditions, a delicate control of the moisture level in the atmosphere has to be enforced to achieve efficient and highly stable devices. In this work, we show that it is the absolute content of water measured in the form of partial water vapour pressure (WVP) the only determining control parameter that needs to be considered during preparation. Following this perspective, MAPbI3 perovskite films were deposited under different WVP by changing the relative humidity (RH) and the lab temperature. We found that efficient and reproducible devices can be obtained at given values of WVP. Furthermore, it is demonstrated that small temperature changes, at the same value of the RH, result in huge changes in performance, due to the non-linear dependence of the WVP on temperature. We have extended the procedure to accomplish high-efficient FA0.83MA0.17PbI3 devices at ambient conditions by adjusting DMSO proportion in precursor solution as a function of WVP only. As an example of the relevance of this paramater, a WVP value of around of 1.6 kPa appears to be an upper limit for safe fabrication of high efficiency devices at ambient conditions, regardless the RH and lab temperature.

Published
2019

9. Thermal Energy Storage in Concrete by Encapsulation of a Nano-Additivated Phase Change Material in Lightweight Aggregates.

Author

Carrillo-Berdugo, Iván, Gallardo, Juan Jesús, Ruiz-Marín, Nazaret, Guillén-Domínguez, Violeta, Alcántara, Rodrigo, Navas, Javier, and Poce-Fatou, Juan Antonio

Subjects
*MINERAL aggregates, *HEAT storage, *LIGHTWEIGHT concrete, *LIGHTWEIGHT materials, *THERMAL comfort
Abstract

This work discusses the applicability of lightweight aggregate-encapsulated n-octadecane with 1.0 wt.% of Cu nanoparticles, for enhanced thermal comfort in buildings by providing thermal energy storage functionality to no-fines concrete. A straightforward two-step procedure (impregnation and occlusion) for the encapsulation of the nano-additivated phase change material in lightweight aggregates is presented. Encapsulation efficiencies of 30–40% are achieved. Phase change behavior is consistent across cycles. Cu nanoparticles provide nucleation points for phase change and increase the rate of progression of phase change fronts due to the enhancement in the effective thermal conductivity of n-octadecane. The effective thermal conductivity of the composites remains like that of regular lightweight aggregates and can still fulfil thermal insulation requirements. The thermal response of no-fines concrete blocks prepared with these new aggregates is also studied. Under artificial sunlight, with a standard 1000 W·m−2 irradiance and AM1.5G filter, concrete samples with the epoxy-coated aggregate-encapsulated n-octadecane-based dispersion of Cu nanoparticles (with a phase change material content below 8% of the total concrete mass) can effectively maintain a significant 5 °C difference between irradiated and non-irradiated sides of the block for ca. 30 min. [ABSTRACT FROM AUTHOR]

Published
2024
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19. Enhanced Thermophysical Properties of the Heat Transfer Fluids for Concentrating Solar Power by Using Metal-Based Nanofluids: An Experimental and Theoretical Overview

Author

Sánchez-Coronilla, Antonio, primary, Navas, Javier, additional, Martín, Elisa I., additional, Gómez-Villarejo, Roberto, additional, Aguilar, Teresa, additional, Gallardo, Juan Jesús, additional, Teruel, Miriam, additional, Alcántara, Rodrigo, additional, and Fernández-Lorenzo, Concha, additional

Published
2019
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22. Tio2/Wo3/Graphene for Photocatalytic H2 Generation and Benzene Removal: Widely Employed Still an Ambiguous System

Author

Koci, Kamila, primary, Chakib, Alaoui, additional, Karmaoui, Mohamed, additional, Bekka, Ahmed, additional, Filip Edelmannova, Miroslava, additional, Gallardo, Juan Jesús, additional, Navas, Javier, additional, Touati, Wassila, additional, Kadi Allah, Imene, additional, Figueiredo, Bruno, additional, António Labrincha, João, additional, and Maria Tobaldi, David, additional

Published
2023
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24. Transferable Classical Force Field for Pure and Mixed Metal Halide Perovskites Parameterized from First-Principles

Author

Seijas-Bellido, Juan Antonio, Samanta, Bipasa, Valadez-Villalobos, Karen, Gallardo, Juan Jesús, Navas, Javier, Balestra, Salvador R.G., Madero Castro, Rafael María, Vicent-Luna, José Manuel, Tao, Shuxia, Toroker, Maytal Caspary, Anta, Juan Antonio, Seijas-Bellido, Juan Antonio, Samanta, Bipasa, Valadez-Villalobos, Karen, Gallardo, Juan Jesús, Navas, Javier, Balestra, Salvador R.G., Madero Castro, Rafael María, Vicent-Luna, José Manuel, Tao, Shuxia, Toroker, Maytal Caspary, and Anta, Juan Antonio

Abstract

Many key features in photovoltaic perovskites occur in relatively long time scales and involve mixed compositions. This requires realistic but also numerically simple models. In this work we present a transferable classical force field to describe the mixed hybrid perovskite MAxFA1-xPb(BryI1-y)3 for variable composition (∀x, y ∈ [0, 1]). The model includes Lennard-Jones and Buckingham potentials to describe the interactions between the atoms of the inorganic lattice and the organic molecule, and the AMBER model to describe intramolecular atomic interactions. Most of the parameters of the force field have been obtained by means of a genetic algorithm previously developed to parametrize the CsPb(BrxI1-x)3 perovskite (Balestra et al. J. Mater. Chem. A. 2020, DOI: 10.1039/d0ta03200j). The algorithm finds the best parameter set that simultaneously fits the DFT energies obtained for several crystalline structures with moderate degrees of distortion with respect to the equilibrium configuration. The resulting model reproduces correctly the XRD patterns, the expansion of the lattice upon I/Br substitution, and the thermal expansion coefficients. We use the model to run classical molecular dynamics simulations with up to 8600 atoms and simulation times of up to 40 ns. From the simulations we have extracted the ion diffusion coefficient of the pure and mixed perovskites, presenting for the first time these values obtained by a fully dynamical method using a transferable model fitted to first-principles calculations. The values here reported can be considered as the theoretical upper limit, that is, without grain boundaries or other defects, for ion migration dynamics induced by halide vacancies in photovoltaic perovskite devices under operational conditions.

Published
2022

25. Transferable Classical Force Field for Pure and Mixed Metal Halide Perovskites Parameterized from First-Principles

Author

Seijas-Bellido, Juan Antonio, primary, Samanta, Bipasa, additional, Valadez-Villalobos, Karen, additional, Gallardo, Juan Jesús, additional, Navas, Javier, additional, Balestra, Salvador R. G., additional, Madero Castro, Rafael María, additional, Vicent-Luna, José Manuel, additional, Tao, Shuxia, additional, Toroker, Maytal Caspary, additional, and Anta, Juan Antonio, additional

Published
2022
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34. Towards the improvement of the global efficiency of concentrating solar power plants by using Pt-based nanofluids: The internal molecular structure effect

Author

Gómez-Villarejo, Roberto, primary, Martín, Elisa I., additional, Sánchez-Coronilla, Antonio, additional, Aguilar, Teresa, additional, Gallardo, Juan Jesús, additional, Martínez-Merino, Paloma, additional, Carrillo-Berdugo, Iván, additional, Alcántara, Rodrigo, additional, Fernández-Lorenzo, Concha, additional, and Navas, Javier, additional

Published
2018
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37. Homeopathic Perovskite Solar Cells: Effect of Humidity during Fabrication on the Performance and Stability of the Device

Author

Contreras-Bernal, Lidia, primary, Aranda, Clara, additional, Valles-Pelarda, Marta, additional, Ngo, Thi Tuyen, additional, Ramos-Terrón, Susana, additional, Gallardo, Juan Jesús, additional, Navas, Javier, additional, Guerrero, Antonio, additional, Mora-Seró, Iván, additional, Idígoras, Jesús, additional, and Anta, Juan A., additional

Published
2018
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38. MoS2 nanosheets vs. nanowires: preparation and a theoretical study of highly stable and efficient nanofluids for concentrating solar power

Author

Navas, Javier, primary, Martínez-Merino, Paloma, additional, Sánchez-Coronilla, Antonio, additional, Gallardo, Juan Jesús, additional, Alcántara, Rodrigo, additional, Martín, Elisa I., additional, Piñero, José C., additional, León, Juan R., additional, Aguilar, Teresa, additional, Toledo, José Hidalgo, additional, and Fernández-Lorenzo, Concha, additional

Published
2018
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39. Experimental and theoretical analysis of nanofluids based on high temperature-heat transfer fluid with enhanced thermal properties

Author

Navas, Javier, primary, Sánchez-Coronilla, Antonio, additional, Martín, Elisa I., additional, Gómez-Villarejo, Roberto, additional, Teruel, Miriam, additional, Gallardo, Juan Jesús, additional, Aguilar, Teresa, additional, Alcántara, Rodrigo, additional, Fernández-Lorenzo, Concha, additional, and Martín-Calleja, Joaquín, additional

Published
2017
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40. The Role of Surfactants in the Stability of NiO Nanofluids: An Experimental and DFT Study

Author

Sánchez‐Coronilla, Antonio, primary, Navas, Javier, additional, Aguilar, Teresa, additional, Martín, Elisa I., additional, Gallardo, Juan Jesús, additional, Gómez‐Villarejo, Mr. Roberto, additional, Carrillo‐Berdugo, Mr. Iván, additional, Alcántara, Rodrigo, additional, Fernández‐Lorenzo, Concha, additional, and Martín‐Calleja, Joaquín, additional

Published
2017
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41. Preparation of Au nanoparticles in a non-polar medium: obtaining high-efficiency nanofluids for concentrating solar power. An experimental and theoretical perspective

Author

Gómez-Villarejo, Roberto, primary, Navas, Javier, additional, Martín, Elisa I., additional, Sánchez-Coronilla, Antonio, additional, Aguilar, Teresa, additional, Gallardo, Juan Jesús, additional, De los Santos, Desiré, additional, Alcántara, Rodrigo, additional, Fernández-Lorenzo, Concha, additional, and Martín-Calleja, Joaquín, additional

Published
2017
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43. Revealing the role of Pb 2+ in the stability of organic–inorganic hybrid perovskite CH 3 NH 3 Pb 1− x Cd x I 3: an experimental and theoretical study

Author

Navas, Javier, Sánchez Coronilla, Antonio, Gallardo, Juan Jesús, Martín Fernández, Elisa Isabel, Cruz Hernández, Norge, Alcántara, Rodrigo, Fernández Lorenzo, Concha, Martín Calleja, Joaquín, Universidad de Sevilla. Departamento de Ingeniería Química, Universidad de Sevilla. Departamento de Física Aplicada I, Universidad de Sevilla. Departamento de Química Física, and Universidad de Sevilla. Grupo de Investigación: FQM-166 Simulación, Caracterización y Evolución de Materiales

Abstract

This paper presents the synthesis of organic–inorganic hybrid perovskite CH3NH3Pb1−xCdxI3. The effect of incorporating Cd2+ or Pb2+ on the stability of the perovskite structure was analysed from a theoretical and experimental viewpoint. The XRD results showed that the tetragonal perovskite structure was formed for x values of up to 0.5, which seems to indicate that the presence of a considerable amount of Pb2+ is necessary to stabilise the structure. In turn, UV-Vis spectroscopy showed how the presence of Cd2+ led to a reduction in the optical band gap of the perovskite structure of up to 9% for CH3NH3Pb0.5Cd0.5I3 with regard to the MAPbI3 structure. Moreover, periodic-DFT calculations were performed to understand the effect of the increased concentration of Cd on the structural and electronic properties of MAPbI3 perovskites. The analysis of both the ELF and the non-covalent interaction (NCI) index show the important role played by the Pb2+ ions in stabilizing this kind of hybrid perovskite structures. Finally, the DOS analysis confirmed the experimental results obtained using UV-Vis spectroscopy. The theoretical band gap values decreased as the concentration of Cd increased. Junta de Andalucía (P09- FQM-04938) Fondo Europeo de Desarrollo Regional (FEDER) Centro Informático Científico de Andalucía (CICA)

Published
2015

45. Revealing the role of Pb 2+ in the stability of organic–inorganic hybrid perovskite CH 3 NH 3 Pb 1− x Cd x I 3: an experimental and theoretical study

Author

Universidad de Sevilla. Departamento de Ingeniería Química, Universidad de Sevilla. Departamento de Física Aplicada I, Universidad de Sevilla. Departamento de Química Física, Universidad de Sevilla. Grupo de Investigación: FQM-166 Simulación, Caracterización y Evolución de Materiales, Navas, Javier, Sánchez Coronilla, Antonio, Gallardo, Juan Jesús, Martín Fernández, Elisa Isabel, Cruz Hernández, Norge, Alcántara, Rodrigo, Fernández Lorenzo, Concha, Martín Calleja, Joaquín, Universidad de Sevilla. Departamento de Ingeniería Química, Universidad de Sevilla. Departamento de Física Aplicada I, Universidad de Sevilla. Departamento de Química Física, Universidad de Sevilla. Grupo de Investigación: FQM-166 Simulación, Caracterización y Evolución de Materiales, Navas, Javier, Sánchez Coronilla, Antonio, Gallardo, Juan Jesús, Martín Fernández, Elisa Isabel, Cruz Hernández, Norge, Alcántara, Rodrigo, Fernández Lorenzo, Concha, and Martín Calleja, Joaquín

Abstract

This paper presents the synthesis of organic–inorganic hybrid perovskite CH3NH3Pb1−xCdxI3. The effect of incorporating Cd2+ or Pb2+ on the stability of the perovskite structure was analysed from a theoretical and experimental viewpoint. The XRD results showed that the tetragonal perovskite structure was formed for x values of up to 0.5, which seems to indicate that the presence of a considerable amount of Pb2+ is necessary to stabilise the structure. In turn, UV-Vis spectroscopy showed how the presence of Cd2+ led to a reduction in the optical band gap of the perovskite structure of up to 9% for CH3NH3Pb0.5Cd0.5I3 with regard to the MAPbI3 structure. Moreover, periodic-DFT calculations were performed to understand the effect of the increased concentration of Cd on the structural and electronic properties of MAPbI3 perovskites. The analysis of both the ELF and the non-covalent interaction (NCI) index show the important role played by the Pb2+ ions in stabilizing this kind of hybrid perovskite structures. Finally, the DOS analysis confirmed the experimental results obtained using UV-Vis spectroscopy. The theoretical band gap values decreased as the concentration of Cd increased.

Published
2015

48. New insights into organic–inorganic hybrid perovskite CH3NH3PbI3nanoparticles. An experimental and theoretical study of doping in Pb2+sites with Sn2+, Sr2+, Cd2+and Ca2+

Author

Navas, Javier, primary, Sánchez-Coronilla, Antonio, additional, Gallardo, Juan Jesús, additional, Cruz Hernández, Norge, additional, Piñero, Jose Carlos, additional, Alcántara, Rodrigo, additional, Fernández-Lorenzo, Concha, additional, De los Santos, Desireé M., additional, Aguilar, Teresa, additional, and Martín-Calleja, Joaquín, additional

Published
2015
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50. Hybrid Perovskite, CH3NH3PbI3, for Solar Applications: An Experimental and Theoretical Analysis of Substitution in A and B Sites.

Author

Sánchez-Coronilla, Antonio, Navas, Javier, Gallardo, Juan Jesús, Martín, Elisa I., De los Santos, Desireé, Hernández, Norge C., Alcántara, Rodrigo, Toledo, José Hidalgo, and Fernández-Lorenzo, Concha

Subjects
PEROVSKITE, METHYLAMMONIUM, LEAD iodide, SOLAR cells, BAND gaps
Abstract

The effect of the incorporation of NH4+ into the CH3NH3+ sites of the tetragonal perovskite CH3NH3PbI3 is analysed. Also, how it affects the introduction of Cd2+ cations into Pb2+ sites for a perovskite with 25 at.% of NH4+ is addressed. The incorporation of NH4+ into perovskite leads to a dramatic loss of crystallinity and to the presence of other phases. Moreover, the NH4PbI3 was not found. The less formation of perovskite when NH4+ is incorporated is due to geometrical factors and not changes in the chemical state bonding of the ions. Also, the samples where perovskite is formed show similar band gap values. A slight increase is observed for samples with x=0.5 and 0.75. For the sample with x=1, a drastic increase of the band gap is obtained. Periodic-DFT calculations agree with the experimental structural tendency when NH4+ is incorporated and the density of states analysis confirmed the experimental band gap. The perovskite with 25 at.% of NH4+ was selected for studying the effect of the concentration of Cd on the structural and electronic properties. The theoretical band gap values decreased with the Cd concentration where the narrowing of Cd s-states in the conduction band plays an important role. [ABSTRACT FROM AUTHOR]

Published
2017
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