Professor Alexandre Reily Rocha

@article{NarcisoPedrosa2025,

title = {Interlayer Excitons and Radiative Lifetimes in MoSe2/SeWS Bilayers: Implications for Light-Emitting Diodes},

author = {Renan Narciso Pedrosa and Cesar E. P. Villegas and Alexandre Reily Rocha and Rodrigo G. Amorim and Wanderlã L. Scopel},

url = {https://pubs.acs.org/doi/full/10.1021/acsanm.4c06994},

doi = {10.1021/acsanm.4c06994},

issn = {2574-0970},

year  = {2025},

date = {2025-03-14},

urldate = {2025-03-14},

journal = {ACS Appl. Nano Mater.},

volume = {8},

number = {10},

pages = {5051--5058},

publisher = {American Chemical Society (ACS)},

abstract = {Interlayer excitons, formed by electrical charge transfer between layers of 2D van der Waals heterostructures, are of the utmost importance for light-detection and light-harvesting applications. In particular, Janus-based heterostructures are promising platforms to observe robust interlayer exciton dynamics due to their intrinsic electric field. Here, we carry out ground- and excited-state first-principles calculations, based on the G0W0 approach and the solution of the Bethe–Salpeter equation, to investigate the energetic, electronic, and excitonic properties of MoSe2/WSSe van der Waals heterobilayers. Our results show that the heterojunction presents features of type-II band alignment and tightly bound, long-lived interlayer excitons. Indeed, the lowest dipole-allowed excitonic state possesses an interlayer character and a slight deviation of 12% in its binding energy compared to the lowest-energy intralayer exciton. Furthermore, the interlayer excitons have transition rates ∼55 times smaller than the intralayer ones, which translates into a longer radiative lifetime of dozens of nanoseconds at room temperature. This is up to 2 orders of magnitude greater than that of the lowest-energy intralayer exciton. The findings emphasize the critical role of Janus-based heterojunctions in influencing interlayer exciton radiative lifetimes, indicating that the system possesses considerable potential for application in optoelectronic devices such as a light-emitting diode (LED) or photodetector.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Lyu2024,

title = {In Situ Solid-State Dewetting of Ag–Au–Pd Alloy: From Macro- to Nanoscale},

author = {Peifen Lyu and Filipe Matusalem and Ece Deniz and Alexandre Reily Rocha and Marina S. Leite},

doi = {10.1021/acsami.4c11397},

issn = {1944-8252},

year  = {2024},

date = {2024-11-13},

urldate = {2024-11-13},

journal = {ACS Appl. Mater. Interfaces},

volume = {16},

number = {45},

pages = {62860--62870},

publisher = {American Chemical Society (ACS)},

abstract = {etal alloy nanostructures represent a promising platform for next-generation nanophotonic devices, surpassing the limitations of pure metals by offering additional “buttons” for tailoring their optical properties by compositional variations. While alloyed nanoparticles hold great potential, their scalability and underexplored optical behavior still limit their application. Here, we establish a systematic approach to quantifying the unique optical behavior of the AgAuPd ternary system while providing a direct comparison with its pure constituent metals. Computationally, we analyze their electronic structure and uncover the transition of Pd d states to Pd/Ag hybridized s states in the bulk form, explaining the similar optical properties observed between Pd and AgAuPd. Experimentally, we fabricate pure metal and fully alloyed nanoparticles through solid-state dewetting, a scalable method. During the process, we trace the optical transition in the systems from the initial thin film stage to the final nanoparticle stage with in situ ellipsometry. We reveal the interplay between optical properties influenced by chemical interdiffusion and localized surface plasmon resonance arising from morphological changes with ex situ surface characterizations. Additionally, we analytically implement a metallic layer derived from the ternary system in a trilayer device, resulting in a single-time and irreversible color filter, to demonstrate an application encompassing a lithography-free and cost-effective route for nanophotonic devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Duarte2024,

title = {Decoding disorder signatures of AuCl3 and vacancies in MoS2 films: from synthetic to experimental inversion},

author = {F R Duarte and F Matusalem and D Grasseschi and Alexandre Reily Rocha and Leandro Seixas and Christiano J S de Matos and S Mukim and M S Ferreira},

url = {https://iopscience.iop.org/article/10.1088/1361-648X/ad7568},

doi = {10.1088/1361-648x/ad7568},

issn = {1361-648X},

year  = {2024},

date = {2024-09-01},

urldate = {2024-12-11},

journal = {J. Phys.: Condens. Matter},

volume = {36},

number = {49},

publisher = {IOP Publishing},

abstract = {This study investigates the scope of application of a recently designed inversion methodology that is capable of obtaining structural information about disordered systems through the analysis of their conductivity response signals. Here we demonstrate that inversion tools of this type are capable of sensing the presence of disorderly distributed defects and impurities even in the case where the scattering properties of the device are only weakly affected. This is done by inverting the DC conductivity response of monolayered MoS2 films containing a minute amount of AuCl3 coordinated complexes. Remarkably, we have successfully extracted detailed information about the concentration of AuCl3 by decoding its signatures on the transport features of simulated devices. In addition to the case of theoretically generated Hamiltonians, we have also carried out a full inversion procedure from experimentally measured signals of similar structures. Based on experimental input signals of MoS2 with naturally occurring vacancies, we were able to quantify the vacancy concentration contained in the samples, which indicates that the inversion methodology has experimental applicability as long as the input signal is able to resolve the characteristic contributions of the type of disorder in question. Being able to handle more complex, realistic scenarios unlocks the method's applicability for designing and engineering even more elaborate materials.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Marinho2024,

title = {Many-Body Effects on Electronic Properties and Optical Response of Single-Layer Penta-NiN2 for Infrared Optoelectronics},

author = {Enesio Marinho and Cesar E. P. Villegas and Pedro Venezuela and Alexandre Reily Rocha},

url = {https://pubs.acs.org/doi/full/10.1021/acsanm.4c03019},

doi = {10.1021/acsanm.4c03019},

issn = {2574-0970},

year  = {2024},

date = {2024-08-15},

urldate = {2024-08-15},

journal = {ACS Appl. Nano Mater.},

publisher = {American Chemical Society (ACS)},

abstract = {We present a comprehensive first-principles study on the optoelectronic properties of the single-layer nickel diazenide (penta-NiN2), a pentagon-based 2D semiconductor with ideal Cairo tessellation, whose bulk counterpart has been recently synthesized. To address its quasiparticle band structure and excitonic effects on its optical absorption spectrum, we carry out ab initio calculations based on many-body perturbation theory within the GW-Bethe–Salpeter equation (BSE) framework. Our results reveal a quasiparticle band gap of 1.05 eV by employing the eigenvalue self-consistent GW approach, corroborating its potential in optoelectronics. The band gap exhibits an anomalous negative dependence on temperature, verified through the band gap pressure coefficient. Acoustic phonon-limited scattering analyses indicate an ultrahigh hole mobility of ∼87 × 104 cm2 V–1 s–1 along the [010] direction. The most prominent absorption peak of monolayer penta-NiN2 is associated with resonant excitons, corresponding to transitions from the valence band maximum to conduction band minimum + 2, which is explained by analyzing the state symmetry of the band edges. Hence, this pentagonal 2D semiconductor exhibits compelling and promising properties deserving deeper exploration in infrared optoelectronics and high-speed devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{santos2024simulating,

title = {Simulating graphene-based single-electron transistor: incoherent current effects due to the presence of electron-electron interaction},

author = {Washington F. Santos and Felippe Amorim and Alexandre Reily Rocha},

url = {https://arxiv.org/abs/2405.14003v1},

doi = { https://doi.org/10.48550/arXiv.2405.14003},

year  = {2024},

date = {2024-05-22},

urldate = {2024-01-01},

abstract = {Carbon-based nanostructures have unparalleled electronic properties. At the same time, using an allotrope of carbon as the contacts can yield better device control and reproducibility. In this work, we simulate a single-electron transistor composed of a segment of a graphene nanoribbon coupled to carbon nanotubes electrodes. Using the non-equilibrium Green's function formalism we atomistically describe the electronic transport properties of the system including electron-electron interactions. Using this methodology we are able to recover experimentally observed phenomena, such as the Coulomb blockade, as well as the corresponding Coulomb diamonds. Furthermore, we are able to separate the different contributions to transport and show that incoherent effects due to the interaction play a crucial role in the transport properties depending on the region of the stability diagram being considered.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{villegas2024static,

title = {Static dielectric response and screening in solid state physics: Why dimensionality matters in dielectrics},

author = {Cesar EP Villegas and Aider Vasquez-Marcani and Alexandre Reily Rocha},

url = {https://pubs.aip.org/aapt/ajp/article-abstract/92/5/360/3283200/Static-dielectric-response-and-screening-in-solid?redirectedFrom=fulltext},

doi = {https://doi.org/10.1119/5.0122288},

year  = {2024},

date = {2024-05-01},

urldate = {2024-01-01},

journal = {American Journal of Physics},

volume = {92},

number = {5},

pages = {360–366},

publisher = {AIP Publishing},

abstract = {Textbooks often present the phenomenon of screening within the Thomas–Fermi model for three-dimensional free electron gases, but obtaining the dielectric response function and screening potential for dielectric systems of reduced dimensionality is also of pedagogical interest. In this work, we introduce a simple approach to investigate static screening in dielectric systems in the presence of an impurity charge for different dimensionalities. This approach is applicable to semiconductors and insulators alike. We demonstrate that, in 3D systems, the macroscopic dielectric function in reciprocal space is a constant, while in 2D and 1D systems, it strongly depends on the momentum transferred to the electrons in the dielectric. Through the proposed dielectric screening model, one can also determine binding energies in a hydrogenic model that can be used to describe excitations in real semiconductor systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{D3CP05949A,

title = {Optical spectra and exciton radiative lifetimes in bulk transition metal dichalcogenides},

author = {Cesar E. P. Villegas and Enesio Marinho and Pedro Venezuela and Alexandre Reily Rocha},

url = {http://dx.doi.org/10.1039/D3CP05949A},

doi = {10.1039/D3CP05949A},

year  = {2024},

date = {2024-04-16},

urldate = {2024-01-01},

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

pages = {-},

publisher = {The Royal Society of Chemistry},

abstract = {The optical response of layered transition metal dichalcogenides (TMDCs) exhibits remarkable excitonic properties which are important from both fundamental and device application viewpoints. One of these phenomena is the observation of intralayer/interlayer excitons. While much effort has been done to characterize excitons in monolayer TMDCs and their heterostructures, a quite limited number of works have addressed the exciton spectra of their bulk counterparts. In this work, we employ ab initio many-body perturbation calculations to investigate the exciton dynamics and spectra of bulk 2H-MX2 (M = Mo, W, and X = S, Se). For molybdenum-based systems, we find the presence of interlayer excitons at energies higher than the first bright exciton (XA), with non-negligible strength intensity. Our results also show that interlayer excitons in tungsten-based systems are almost degenerate in energy with XA and possess very small oscillator strengths when compared with molybdenum-based systems. At room temperature, and considering the thermal exciton fine-structure population for the XA-exciton, we estimate effective radiative lifetimes in the range of ∼4–14 ns. For higher energy excitons we predict longer effective lifetimes of tens of nanoseconds.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pedrosa2024optical,

title = {Optical properties enhancement via WSSe/silicene solar cell junctions},

author = {Renan Narciso Pedrosa and Cesar EP Villegas and Alexandre Reily Rocha and Rodrigo G. Amorim and Wanderlã L. Scopel},

url = {https://pubs.rsc.org/en/content/articlehtml/2024/ya/d3ya00529a},

doi = {10.1039/D3YA00529A},

year  = {2024},

date = {2024-03-04},

urldate = {2024-03-04},

journal = {Energy Advances},

volume = {3},

number = {4},

pages = {821–828},

publisher = {Royal Society of Chemistry},

abstract = {2D Janus monolayers exhibit nanoscale asymmetric surface organization along the out-of-plane direction and have recently emerged as a class of 2D materials. In this work, we investigate the energetic, electronic, and optical properties of the vertical van der Waals stack between WSSe and silicene monolayers based on first-principles calculations. The Janus/silicene interface formation is driven by an exothermic process, and charge transfer from the silicene to the Janus monolayer is observed. The intrinsic properties of silicene and Janus are preserved despite the stacking of the parts. The Bethe–Salpeter equation (BSE) was used to understand the contact influence on the optical absorption spectrum of the vertical interface. Our findings reveal that the power conversion energy (PCE) of the heterostructure is boosted 2.42 times higher than that of the Janus monolayer. Thus, due to its PCE and transparent electrical contact, the heterojunction is a promising candidate for use as a photovoltaic device compared to its counterparts.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acs.jpcb.2c09059,

title = {Size and Quality of Quantum Mechanical Data Set for Training Neural Network Force Fields for Liquid Water},

author = {Márcio S. Gomes-Filho and Alberto Torres and Alexandre Reily Rocha and Luana S. Pedroza},

url = {https://doi.org/10.1021/acs.jpcb.2c09059},

doi = {10.1021/acs.jpcb.2c09059},

year  = {2023},

date = {2023-01-01},

journal = {The Journal of Physical Chemistry B},

volume = {127},

number = {6},

pages = {1422-1428},

abstract = {Molecular dynamics simulations have been used in different scientific fields to investigate a broad range of physical systems. However, the accuracy of calculation is based on the model considered to describe the atomic interactions. In particular, ab initio molecular dynamics (AIMD) has the accuracy of density functional theory (DFT) and thus is limited to small systems and a relatively short simulation time. In this scenario, Neural Network Force Fields (NNFFs) have an important role, since they provide a way to circumvent these caveats. In this work, we investigate NNFFs designed at the level of DFT to describe liquid water, focusing on the size and quality of the training data set considered. We show that structural properties are less dependent on the size of the training data set compared to dynamical ones (such as the diffusion coefficient), and a good sampling (selecting data reference for the training process) can lead to a small sample with good precision.},

note = {PMID: 36730848},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{AMORIM2023112207,

title = {Gate voltage enhances the thermoelectric transport of quantum dots in graphene nanoribbons},

author = {Felippe P. Amorim and Alberto Torres and Cesar E. P. Villegas and Alexandre Reily Rocha},

url = {https://www.sciencedirect.com/science/article/pii/S092702562300201X},

doi = {https://doi.org/10.1016/j.commatsci.2023.112207},

issn = {0927-0256},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {Computational Materials Science},

volume = {227},

pages = {112207},

abstract = {Chemically derived graphene nanoribbons and quantum dots are unique nanostructures that offer more possibilities than 2D and 3D systems to tune their electronic properties due to the enhanced quantum confinement effects. This feature make them potential candidates for many technological applications, including thermoelectrics. In this work, we combined density functional theory calculations with the non-equilibrium Green’s function formalism to investigate the electronic and thermoelectric properties of recently synthesized quantum dots in graphene nanoribbons under the presence of an applied gate voltage, and for different temperatures. We find that the electronic states at the band edge are highly localized in the inner region of the quantum dot, and can be lifted to higher energies by applying a gate voltage, which subsequently enhances figure of merit. Moreover, at zero gate voltage and room temperature, we estimate the lower bound for ZT to be approximately 0.25. Interestingly, this lower bound can exceed unity by smoothly increasing the gate voltage for values above 6 V. The overall results regarding the enhancement of ZT suggest that quantum dots in graphene nanoribbons would be promising candidates for thermoelectric applications.},

keywords = {7-14-7 AGNR, Gate voltage enhances, Quantum dots in graphene, Thermoelectric transport},

pubstate = {published},

tppubtype = {article}

}