Professor Rodrigo Capaz

@article{BENATTO2024109206,

title = {TMM−Sim: A Versatile Tool for Optical Simulation of Thin−Film Solar Cells},

author = {Leandro Benatto and Omar Mesquita and Kaike R. M. Pacheco and Lucimara S. Roman and Marlus Koehler and Rodrigo B. Capaz and Graziâni Candiotto},

url = {https://www.sciencedirect.com/science/article/pii/S0010465524001292},

doi = {https://doi.org/10.1016/j.cpc.2024.109206},

issn = {0010-4655},

year  = {2024},

date = {2024-04-16},

urldate = {2024-01-01},

journal = {Computer Physics Communications},

pages = {109206},

abstract = {The Transfer Matrix Method (TMM) has become a prominent tool for the optical simulation of thin−film solar cells, particularly among researchers specializing in organic semiconductors and perovskite materials. As the commercial viability of these solar cells continues to advance, driven by rapid developments in materials and production processes, the importance of optical simulation has grown significantly. By leveraging optical simulation, researchers can gain profound insights into photovoltaic phenomena, empowering the implementation of device optimization strategies to achieve enhanced performance. However, existing TMM−based packages exhibit limitations, such as requiring programming expertise, licensing fees, or lack of support for bilayer device simulation. In response to these gaps and challenges, we present the TMM Simulator (TMM−Sim), an intuitive and user−friendly tool to calculate essential photovoltaic parameters, including the optical electric field profile, exciton generation profile, fraction of light absorbed per layer, photocurrent, external quantum efficiency, internal quantum efficiency, and parasitic losses. An additional advantage of TMM−Sim lies in its capacity to generate outcomes suitable as input parameters for electro−optical device simulations. In this work, we offer a comprehensive guide, outlining a step−by−step process to use TMM−Sim, and provide a thorough analysis of the results. TMM−Sim is freely available, accessible through our web server (nanocalc.org), or downloadable from the TMM−Sim repository (for Unix, Windows, and macOS) on GitHub. With its user−friendly interface and powerful capabilities, TMM−Sim aims to facilitate and accelerate research in thin−film solar cells, fostering advancements in renewable energy technologies.},

keywords = {Optical Simulation, Refractive index, Software, Solar cell, Transfer matrix method},

pubstate = {published},

tppubtype = {article}

}

@article{FIUZA2024101828,

title = {Visualization of electron beam-induced desintering of nanostructured ceramics at the atomic scale},

author = {Tanna E. R. Fiuza and Bruno Focassio and Jefferson Bettini and Gabriel R. Schleder and Murillo H. M. Rodrigues and João B. Souza Junior and Adalberto Fazzio and Rodrigo B. Capaz and Edson R. Leite},

url = {https://www.sciencedirect.com/science/article/pii/S2666386424000535},

doi = {https://doi.org/10.1016/j.xcrp.2024.101828},

issn = {2666-3864},

year  = {2024},

date = {2024-02-12},

urldate = {2024-01-01},

journal = {Cell Reports Physical Science},

pages = {101828},

abstract = {Summary 

Mass diffusion and local tensile stress associated with electron beam irradiation can favor the desintering process. Here, we report the electron beam-induced desintering of ZrO2 thin films at the atomic scale with unprecedented spatial resolution using high-resolution transmission electron microscopy (HRTEM). Our results confirm earlier works in which desintering is driven by tensile stress acting on the bridge if an external stimulus, such as irradiation, triggers atom mobility. Additionally, we find departures from classical microscopic descriptions: a very stable nanobridge is formed and evolves until rupture with a constant dihedral angle instead of a brittle rupture. An adapted model for desintering at the nanoscale is proposed using the experimental findings. This work provides insights that may improve the knowledge of the rupture of ceramic materials at the nano and atomic scales, contributing to a better knowledge of materials’ behavior.},

keywords = {atom mobility, ceramics, desintering, HRTEM, thin films, ZrO},

pubstate = {published},

tppubtype = {article}

}

@article{BENATTO2024109100,

title = {RI−Calc: A user friendly software and web server for refractive index calculation},

author = {Leandro Benatto and Omar Mesquita and Lucimara S. Roman and Marlus Koehler and Rodrigo B. Capaz and Graziâni Candiotto},

url = {https://www.sciencedirect.com/science/article/pii/S0010465524000237},

doi = {https://doi.org/10.1016/j.cpc.2024.109100},

issn = {0010-4655},

year  = {2024},

date = {2024-01-26},

urldate = {2024-01-01},

journal = {Computer Physics Communications},

volume = {298},

pages = {109100},

abstract = {The refractive index of an optical medium is essential for studying a variety of physical phenomena. One useful method for determining the refractive index of scalar materials (i.e., materials which are characterized by a scalar dielectric function) is to employ the Kramers−Kronig (K−K) relations. The K−K method is particularly useful in cases where ellipsometric measurements are unavailable, a situation that frequently occurs in many laboratories. Although some packages can perform this calculation, they usually lack a graphical interface and are complex to implement and use. Those deficiencies inhibit their utilization by a plethora of researchers unfamiliar with programming languages. To address the aforementioned gap, we have developed the Refractive Index Calculator (RI−Calc) program that provides an intuitive and user−friendly interface. The RI−Calc program allows users to input the absorption coefficient spectrum and then easily calculate the complex refractive index and the complex relative permittivity of a broad range of thin films, including of molecules, polymers, blends, and perovskites. The program has been thoroughly tested, taking into account the Lorentz oscillator model and experimental data from a materials' refractive index database, demonstrating consistent outcomes. It is compatible with Windows, Unix, and macOS operating systems. You can download the RI−Calc binaries from our GitHub repository or conveniently access the program through our dedicated web server at nanocalc.org.},

keywords = {Absorption coefficient, Kramers−Kronig, Lorentz oscillator model, Refractive index},

pubstate = {published},

tppubtype = {article}

}

@article{Merces_2021,

title = {Reorganization Energy upon Controlled Intermolecular Charge‐Transfer Reactions in Monolithically Integrated Nanodevices},

author = {Leandro Merces and Graziâni Candiotto and Letícia Mariê Minatogau Ferro and Anerise Barros and Carlos Vinícius Santos Batista and Ali Nawaz and Antonio Riul and Rodrigo B. Capaz and Carlos César Bof Bufon},

url = {http://dx.doi.org/10.1002/smll.202103897},

doi = {10.1002/smll.202103897},

issn = {1613-6829},

year  = {2023},

date = {2023-12-04},

urldate = {2021-10-01},

journal = {Small},

volume = {17},

number = {45},

publisher = {Wiley},

abstract = {Intermolecular charge transfer reactions are key processes in physical chemistry. The electron-transfer rates depend on a few system's parameters, such as temperature, electromagnetic field, distance between adsorbates and, especially, the molecular reorganization energy. This microscopic greatness is the energetic cost to rearrange each single−molecule and its surrounding environment when a charge is transferred. Reorganization energies are measured by electrochemistry and spectroscopy techniques as well as at the single-molecule limit using atomic force microscopy approaches, but not from temperature−dependent charge transport measurements nor in a monolithically−integrated molecular device. Nowadays self−rolling nanomembrane (rNM) devices, with strain−engineered mechanical properties, on−a−chip monolithic integration, and operable in distinct environments, overcome those challenges. Here, we investigate the charge transfer reactions occurring within a ca. 6 nm thick copper−phthalocyanine (CuPc) film employed as electrode-spacer in a monolithically integrated nanocapacitor. Employing the rNM technology allows us to measure the molecules' charge−transport dependence on temperature for different electric fields. Thereby, the CuPc reorganization energy is determined as (930 ± 40) meV, whereas density functional theory (DFT) calculations support our findings with the atomistic picture of the CuPc charge transfer reaction. Our approach presents a consistent route towards electron transfer reaction characterization using current−voltage spectroscopy and provides insight into the role of the molecular reorganization energy when it comes to electrochemical nanodevices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{BENATTO2024109015,

title = {PLQ−sim: A computational tool for simulating photoluminescence quenching dynamics in organic donor/acceptor blends},

author = {Leandro Benatto and Omar Mesquita and Lucimara S. Roman and Rodrigo B. Capaz and Graziâni Candiotto and Marlus Koehler},

url = {https://www.sciencedirect.com/science/article/pii/S0010465523003600},

doi = {https://doi.org/10.1016/j.cpc.2023.109015},

issn = {0010-4655},

year  = {2023},

date = {2023-11-24},

urldate = {2023-11-24},

journal = {Computer Physics Communications},

volume = {296},

pages = {109015},

abstract = {Photoluminescence Quenching Simulator (PLQ−Sim) is a user−friendly software to study the photoexcited state dynamics at the interface between two organic semiconductors forming a blend: an electron donor (D), and an electron acceptor (A). Its main function is to provide substantial information on the photophysical processes relevant to organic photovoltaic and photothermal devices, such as charge transfer state formation and subsequent free charge generation or exciton recombination. From input parameters provided by the user, the program calculates the transfer rates of the D/A blend and employs a kinetic model that provides the photoluminescence quenching efficiency for initial excitation in the donor or acceptor. When calculating the rates, the user can choose to use disorder parameters to better describe the system. In addition, the program was developed to address energy transfer phenomena that are commonly present in organic blends. The time evolution of state populations is also calculated providing relevant information for the user. In this article, we present the theory behind the kinetic model, along with suggestions for methods to obtain the input parameters. A detailed demonstration of the program, its applicability, and an analysis of the outputs are also presented. PLQ−Sim is license free software that can be run via dedicated webserver nanocalc.org or downloading the program executables (for Unix, Windows, and macOS) from the PLQ-Sim repository on GitHub.},

keywords = {Charge transfer, Energy transfer, Exciton, Organic semiconductor, Photoluminescence quenching, Software},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acsami.3c10868,

title = {Unlocking the Potential of Nanoribbon-Based Sb2S3/Sb2Se3 van-der-Waals Heterostructure for Solar-Energy-Conversion and Optoelectronics Applications},

author = {Vinícius G. Garcia and Nathanael N. Batista and Diego A. Aldave and Rodrigo B. Capaz and Juan José Palacios and Marcos G. Menezes and Wendel S. Paz},

url = {https://doi.org/10.1021/acsami.3c10868},

doi = {10.1021/acsami.3c10868},

year  = {2023},

date = {2023-11-15},

journal = {ACS Applied Materials & Interfaces},

volume = {0},

number = {0},

pages = {null},

abstract = {High-performance nanosized optoelectronic devices based on van der Waals (vdW) heterostructures have significant potential for use in a variety of applications. However, the investigation of nanoribbon-based vdW heterostructures are still mostly unexplored. In this study, based on first-principles calculations, we demonstrate that a Sb2S3/Sb2Se3 vdW heterostructure, which is formed by isostructural nanoribbons of stibnite (Sb2S3) and antimonselite (Sb2Se3), possesses a direct band gap with a typical type-II band alignment, which is suitable for optoelectronics and solar energy conversion. Optical absorption spectra show broad profiles in the visible and UV ranges for all of the studied configurations, indicating their suitability for photodevices. Additionally, in 1D nanoribbons, we see sharp peaks corresponding to strongly bound excitons in a fashion similar to that of other quasi-1D systems. The Sb2S3/Sb2Se3 heterostructure is predicted to exhibit a remarkable power conversion efficiency (PCE) of 28.2%, positioning it competitively alongside other extensively studied two-dimensional (2D) heterostructures.},

note = {PMID: 37967344},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acsaem.3c02371,

title = {Enhancing the Chemical Stability and Photovoltaic Properties of Highly Efficient Nonfullerene Acceptors by Chalcogen Substitution: Insights from Quantum Chemical Calculations},

author = {Leandro Benatto and João Paulo A. Souza and Matheus F. F. Neves and Lucimara S. Roman and Rodrigo B. Capaz and Graziâni Candiotto and Marlus Koehler},

url = {https://doi.org/10.1021/acsaem.3c02371},

doi = {10.1021/acsaem.3c02371},

year  = {2023},

date = {2023-11-07},

journal = {ACS Applied Energy Materials},

volume = {0},

number = {0},

pages = {null},

abstract = {The chemical stability of the nonfullerene acceptor (NFA) is the Achilles’ heel of the research on state-of-the-art organic solar cells (OSC). The fragility of NFA is essentially due to the weak bond that links the central donor core of the molecules with their acceptor moieties at the edges. Here, we proposed the replacement of thiophene at the outer-core position of traditional NFAs for tellurophene, a hitherto unexplored modification. Since tellurium is a distinctive element among chalcogens, the basic features of Te compounds cannot be deduced straightforwardly from the properties of their lighter analogues, S and Se. The modeled Te-based NFAs presented interesting features such as stronger intra- and intermolecular interactions induced by a distinctive secondary bond effect between the end acceptor moiety and the outer chalcogen atom. This design strategy resulted in stiffer molecules with red-shifted absorption spectra and less susceptible to degradation, verified through stress tests and vibrational spectra analysis. Besides that, a weakened exciton binding energy has been found, opening the possibility of blends with a lower driving force. Our results shed light on several aspects of selenation and telluration of traditional NFAs, providing valuable insights into the possible consequences for OSCs applications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{D3CP03320A,

title = {CO adsorption on MgO thin-films: formation and interaction of surface charged defects},

author = {Raphael Silva Alvim and Itamar Borges Jr. and Rita Maria Brito Alves and Rodrigo B. Capaz and Alexandre Amaral Leitão},

url = {http://dx.doi.org/10.1039/D3CP03320A},

doi = {10.1039/D3CP03320A},

year  = {2023},

date = {2023-10-12},

urldate = {2023-01-01},

journal = {Phys. Chem. Chem. Phys.},

pages = {-},

publisher = {The Royal Society of Chemistry},

abstract = {Two-dimensional (2D) materials formed by thin-films of metal oxides that grow on metal supports are commonly used in heterogeneous catalysis and multilayer electronic devices. Despite extensive research on these systems, the effects of charged defects at supported oxides on surface processes are still not clear. In this work, we perform spin-polarized density-functional theory (DFT) calculations to investigate formation and interaction of charged magnesium and oxygen vacancies, and Al dopants on MgO(001)/Ag(001) surface. The results show a sizable interface compressive effect that decreases the metal work function as electrons are added on the MgO surface with a magnesium vacancy. This surface displays a larger formation energy in a water environment (O-rich condition) even with additional Al-doping. Under these conditions, we found that a polar molecule such as CO is more strongly adsorbed on the low-coordination oxygen sites due to a larger contribution of the channeled electronic transport with the silver interface regardless of the surface charge. Therefore, these findings elucidate how surface intrinsic vacancies can influence or contribute to charge transfer, which allows one to explore more specific reactions at different surface topologies for more efficient catalysts for CO2 conversion.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{WATANABE2023155070,

title = {Surface characterization using Friction Force Microscopy and the Jarzynski equality},

author = {Yasmin Watanabe and Rodrigo B. Capaz and Renata A. Simao},

url = {https://www.sciencedirect.com/science/article/pii/S0169433222025983},

doi = {https://doi.org/10.1016/j.apsusc.2022.155070},

issn = {0169-4332},

year  = {2023},

date = {2023-01-01},

journal = {Applied Surface Science},

volume = {607},

pages = {155070},

abstract = {The Jarzynski equality is a fundamental result from non-equilibrium statistical mechanics that provides the difference in free energy between two states from the work done on the system by processes that can be carried out far from equilibrium. We evaluate the applicability of Jarzynski equality to map the potential energy of a model graphene surface using data from simulated Friction Force Microscopy (FFM). We model the scanning process of the FFM using the Prandtl-Tomlinson model and Langevin dynamics. By varying the simulation parameters, we verify the “stick–slip” and thermolubricity friction regimes, as well as the crossover between them. We then calculate the surface potential energy using the Jarzynski equality for these regimes. A new method for properly evaluating the free energy of the cantilever is introduced. We observe that the applicability of Jarzynski's equality is linked to the friction regimes: For thermolubricity, a very accurate potential energy curve is obtained for relatively few repetitions, but for the “stick–slip” movement, it is only possible to use Jarzynski’s equation in a small fraction of the scanning distance. For the crossover regime, it is possible to obtain a relatively accurate potential energy curve for a sufficiently large number of sampling repetitions.},

keywords = {Friction Force Microscopy, Jarzynski equality, Prandtl-Tomlinson model, Stick-slip, Thermolubricity},

pubstate = {published},

tppubtype = {article}

}

@article{BENATTO2023108715,

title = {FRET–Calc: A free software and web server for Förster Resonance Energy Transfer Calculation},

author = {Leandro Benatto and Omar Mesquita and João L. B. Rosa and Lucimara S. Roman and Marlus Koehler and Rodrigo B. Capaz and Graziâni Candiotto},

url = {https://www.sciencedirect.com/science/article/pii/S0010465523000607},

doi = {https://doi.org/10.1016/j.cpc.2023.108715},

issn = {0010-4655},

year  = {2023},

date = {2023-01-01},

journal = {Computer Physics Communications},

volume = {287},

pages = {108715},

abstract = {Förster Resonance Energy Transfer Calculator (FRET−Calc) is a program and web server that analyzes molar extinction coefficient of the acceptor, emission spectrum of the donor, and the refractive index spectrum of the donor/acceptor blend. Its main function is to obtain important parameters of the FRET process from experimental data, such as: (i) effective refractive index, (ii) overlap integral, (iii) Förster radius, (iii) FRET efficiency and (iv) FRET rate. FRET−Calc is license free software that can be run via dedicated web server (nanocalc.org) or downloading the program executables (for Unix, Windows, and macOS) from the FRET−Calc repository on GitHub. The program features a user−friendly interface, making it suitable for materials research and teaching purposes. In addition, the program is optimized to run on normal computers and is lightweight. An example will be given with the step by step of its use and results obtained.},

keywords = {Energy transfer, Fluorescence, Förster radius, FRET, Organic semiconductor, Software},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acsami.3c04509,

title = {Improved Performance of Organic Light-Emitting Transistors Enabled by Polyurethane Gate Dielectric},

author = {Arthur R. J. Barreto and Graziâni Candiotto and Harold J. C. Avila and Rafael S. Carvalho and Aline Magalhães Santos and Mario Prosa and Emilia Benvenuti and Salvatore Moschetto and Stefano Toffanin and Rodrigo B. Capaz and Michele Muccini and Marco Cremona},

url = {https://doi.org/10.1021/acsami.3c04509},

doi = {10.1021/acsami.3c04509},

year  = {2023},

date = {2023-01-01},

journal = {ACS Applied Materials & Interfaces},

volume = {15},

number = {28},

pages = {33809-33818},

abstract = {Organic light-emitting transistors (OLETs) are multifunctional optoelectronic devices that combine in a single structure the advantages of organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs). However, low charge mobility and high threshold voltage are critical hurdles to practical OLET implementation. This work reports on the improvements obtained by using polyurethane films as a dielectric layer material in place of the standard poly(methyl methacrylate) (PMMA) in OLET devices. It was found that polyurethane drastically reduces the number of traps in the device, thereby improving electrical and optoelectronic device parameters. In addition, a model was developed to rationalize an anomalous behavior at the pinch-off voltage. Our findings represent a step forward to overcome the limiting factors of OLETs that prevent their use in commercial electronics by providing a simple route for low-bias device operation.},

note = {PMID: 37403922},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{MOURA2023118123,

title = {Resonance Raman spectroscopy characterization of linear carbon chains encapsulated by multi-walled carbon nanotubes},

author = {Thiago A. Moura and Wellington Q. Neves and Rafael S. Alencar and Y. A. Kim and M. Endo and Thiago L. Vasconcelos and Deyse G. Costa and Graziâni Candiotto and Rodrigo B. Capaz and Paulo T. Araujo and Antonio G. Souza Filho and Alexandre R. Paschoal},

url = {https://www.sciencedirect.com/science/article/pii/S0008622323003688},

doi = {https://doi.org/10.1016/j.carbon.2023.118123},

issn = {0008-6223},

year  = {2023},

date = {2023-01-01},

journal = {Carbon},

volume = {212},

pages = {118123},

abstract = {The unique electronic and vibrational properties of linear carbon chains (LCCs) have attracted close attention from the scientific community in recent years. Raman spectroscopy addressing the LCC spectral signature around 1850 cm−1 has been widely used to identify the LCC and probe electronic and vibrational properties as a function of carbon length. Despite the number of works available in literature, some aspects of the LCC's aforementioned properties remain unclear. Using a combination of confocal and Tip-enhanced Raman Spectroscopy (TERS), along with different laser lines, this work addresses important aspects of the optical resonance window of LCCs encapsulated by multi-walled carbon nanotubes (MWCNTs) (i.e. LCC@MWCNT) as well as an elusive Raman signature around 1637 cm−1, which is assigned to the LCC's longitudinal acoustic (LA) phonon mode at the X point (zone edge), which becomes Raman active likely due to disorder effects. First-principles calculations endorse our conclusions.},

keywords = {Carbon nanotubes, Linear carbon chains, Raman spectroscopy, TERS},

pubstate = {published},

tppubtype = {article}

}

@article{D3TA04225Ab,

title = {Patterning edge-like defects and tuning defective areas on the basal plane of ultra-large MoS2 monolayers toward hydrogen evolution reaction},

author = {Bianca Rocha Florindo and Leonardo Hideki Hasimoto and Nicolli Freitas and Graziâni Candiotto and Erika Nascimento Lima and Cláudia Lourenço and Ana Beatriz Sorana Araujo and Carlos Ospina and Jefferson Bettini and Edson Roberto Leite and Renato S Lima and Adalberto Fazzio and Rodrigo B. Capaz and Murilo Santhiago},

url = {http://dx.doi.org/10.1039/D3TA04225A},

doi = {10.1039/D3TA04225A},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {J. Mater. Chem. A},

pages = {-},

publisher = {The Royal Society of Chemistry},

abstract = {The catalytic sites of MoS2 monolayers towards hydrogen evolution are well known to be vacancies and edge-like defects. However, it is still very challenging to control the position, size, and propagation of defects on the basal plane of MoS2 monolayers by most of defect-engineering routes. In this work, the fabrication of etched arrays on ultra-large supported and free-standing MoS2 monolayers using focused ion beam (FIB) is reported for the first time. By tuning the Ga+ ion dose, it is possible to confine defects near the etched edges or propagate them over ultra-large areas on the basal plane. The electrocatalytic activity of the arrays toward hydrogen evolution reaction (HER) was measured by fabricating microelectrodes using a new method that preserves the catalytic sites. We demonstrate that the overpotential can be decreased up to 290 mV by assessing electrochemical activity only at the basal plane. High-resolution transmission electron microscopy images obtained on FIB patterned freestanding MoS2 monolayers reveal the presence of amorphous regions and X-ray photoelectron spectroscopy indicates sulfur excess in these regions. Density-functional theory calculations provide identification of catalytic defect sites. Our results demonstrate a new rational control of amorphous-crystalline surface boundaries and future insight for defect optimization in MoS2 monolayers.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}