@article{Ribeiro2025,

title = {Impact of Thin Film Thickness on the Structural, Energetic and Optoelectronic Properties of Two-Dimensional FPEA₂(MAₙ₋₁)PbₙI₃ₙ₊₁ Perovskites},

author = {Israel C. Ribeiro and Felipe D. Picoli and Pedro Ivo R. Moraes and André F. V. Fonseca and Luiz N. Oliveira and Ana Flávia Nogueira and Juarez L. F. Da Silva},

url = {https://doi.org/10.1021/acsaem.4c02800},

doi = {10.1021/acsaem.4c02800},

year  = {2025},

date = {2025-01-01},

journal = {ACS Applied Energy Materials},

publisher = {American Chemical Society},

abstract = {Perovskite solar cell devices, composed of solution-processed perovskite layers with thicknesses of a few hundred angstroms, represent a leading technology in thin-film photovoltaics. Here, we performed a theoretical investigation based on ab initio calculations to explore the role of perovskite thin film thickness, with the general formula FPEA₂(MAₙ₋₁)PbₙI₃ₙ₊₁, where FPEA represents 4-fluorophenylethylammonium cations and n ranges from 1 to 4 layers. Our findings reveal that increasing the thickness of the inorganic layer significantly influences the structural, energetic, and optoelectronic properties. Enhanced charge transfer within the inorganic framework and stronger organic–inorganic interactions are observed as the effective charge distribution shifts with increasing thickness. Exothermic trends in adsorption and interaction energies highlight the stabilizing effects of van der Waals forces and hydrogen bonding. The PbI₆-octahedra play a critical role in determining the optical activity and the formation of valence and conduction bands. Thicker films exhibit more intense absorption, emphasizing the importance of PbI₆-octahedra in driving optical properties. Moreover, the work function (ϕ) decreases with increasing thickness due to reduced quantum confinement effects, while the nature of polar FPEA molecules induces deviations in ϕ, underscoring the interaction between molecular composition and thickness. Band alignment further reveals strong spin–orbit coupling effects on the conduction band minimum (CBM), influenced by charge-transfer variability from FPEA to halides. These findings provide insights into thickness-dependent properties that are essential for optimizing perovskite-based devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{DASILVA2025145852,

title = {Photoelectrochemical Bi2Fe4O9 phase purification – Removing the phase Bi2O3 from Bi2Fe4O9/Bi2O3 thin films},

author = {Bruno Leuzinger Silva and Rafael Alcides Vicente and Pablo Sebastián Fernández and Ana Flávia Nogueira},

url = {https://www.sciencedirect.com/science/article/pii/S0013468625002154},

doi = {https://doi.org/10.1016/j.electacta.2025.145852},

issn = {0013-4686},

year  = {2025},

date = {2025-01-01},

journal = {Electrochimica Acta},

volume = {519},

pages = {145852},

abstract = {Multiferroic photo(electro)catalysts hold significant potential for various applications, including hydrogen generation, water treatment, and sensor development. In this context, mullite-type bismuth ferrite (Bi₂Fe₄O₉) emerges as a promising material due to its stability and suitable bandgap. However, regardless of the chosen and optimized synthesis protocol, the preparation of Bi₂Fe₄O₉ often results in the formation of unwanted secondary phases, such as Bi₂O₃, Bi₂₅FeO₃₉, Fe₂O₃, and BiFeO₃. While considerable efforts have been directed toward improving synthesis procedures, an alternative or complementary strategy lies in the development of an effective purification step—a path that has not been pursued until now. In this study, we successfully removed the Bi₂O₃ phase from Bi₂Fe₄O₉/Bi₂O₃ thin-film photoelectrodes, achieving a pure Bi₂Fe₄O₉ photoelectrode through a straightforward and accessible method that combines voltammetry and glycerol as a cost-effective complexing agent. Our findings highlight the critical role of the complexing agent in preventing the formation of bismuth(III) species, primarily in the forms of Bi₂O₃, Bi(OH)₃, and BiOOH, within the photoelectrode. This simple yet innovative approach provides a promising pathway to eliminate undesirable secondary bismuth phases, paving the way for the efficient purification of bismuth oxide-based electrodes.},

keywords = {Bismuth ferrite (Bi₂Fe₄O₉), Multiferroic materials, Phase purification, Phase transition, Photoelectrocatalysts},

pubstate = {published},

tppubtype = {article}

}

@article{Vale2024c,

title = {Charge Trapping and Detrapping in CsPbBr3 Perovskite Nanocrystals: Implications for Photovoltaic and Photocatalysis Applications},

author = {Brener R. C. Vale and Diego Scolfaro and Claudevan A. Sousa and Andre F. V. Fonseca and Luiz G. Bonato and Ana F. Nogueira and Jefferson Bettini and Lazaro A. Padilha},

url = {https://doi.org/10.1021/acsanm.4c04839},

doi = {10.1021/acsanm.4c04839},

year  = {2024},

date = {2024-11-21},

urldate = {2024-11-21},

journal = {ACS Applied Nano Materials},

volume = {XX},

number = {XX},

issue = {XX},

pages = {XX},

abstract = {Perovskite nanocrystals (PNCs) have emerged as a promising platform for the development of highly efficient nanomaterial-based lighting devices. Although experiments and calculations have shown that defect densities are on the order of 1011–1016 cm–3 in bulk perovskites, this is not true for nanomaterials because they present higher defect densities. To understand the origin and relative contribution of those defects, we employed transient absorption spectroscopy and time-resolved photoluminescence. We scrutinize the exciton dynamics in PNCs for over 7 orders of magnitude in time, and we conclude that, in the ensemble of CsPbBr3 PNCs, excited carriers can take different paths to return to the fundamental level: electron traps (hundreds of picoseconds), surface traps (2–5 ns), direct radiative recombination (∼10 ns), and delayed emission. Our measurements revealed that the excitonic component of PNCs tends to decrease with increasing nanocrystal (NC) size. On the other hand, we observed that the electron trap decay amplitude correlates with the relative delayed emission contribution, suggesting that the recombination of detrapped species comes from electron-trapping sites. Besides, the relative contribution of delayed emission is size-dependent and increases with the NC size, achieving about 80% of reversibility. Although the excitonic contribution of larger NCs is lower compared to the smaller ones, the results suggest that electron traps are reversible and do not decrease the photoluminescence quantum yield of the NCs. These results can be useful for applications that involve charge-carrier extraction, such as photovoltaics and photocatalysis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Scalon2024c,

title = {2D Phase Formation on 3D Perovskite: Insights from Molecular Stiffness},

author = {Lucas Scalon and Charles Alves Nogueira and André Felipe Vale Fonseca and Paulo E. Marchezi and Raphael Fernando Moral and Giulia Grancini and Tim Kodalle and Carolin M. Sutter-Fella and Caio Costa Oliveira and Luiz F. Zagonel and Ana F. Nogueira},

url = {https://doi.org/10.1021/acsami.4c11394},

doi = {10.1021/acsami.4c11394},

isbn = {1944-8244},

year  = {2024},

date = {2024-09-13},

urldate = {2024-09-13},

journal = {ACS Applied Materials and Interfaces},

abstract = {Several studies have demonstrated that low-dimensional structures (e.g., two-dimensional (2D)) associated with three-dimensional (3D) perovskite films enhance the efficiency and stability of perovskite solar cells. Here, we aim to track the formation sites of the 2D phase on top of the 3D perovskite and to establish correlations between molecular stiffness and steric hindrance of the organic cations and their influence on the formation and crystallization of 2D/3D. Using cathodoluminescence combined with a scanning electron microscopy technique, we verified that the formation of the 2D phase occurs preferentially on the grain boundaries of the 3D perovskite. This helps explain some passivation mechanisms conferred by the 2D phase on 3D perovskite films. Furthermore, by employing in situ grazing-incidence wide-angle X-ray scattering, we monitored the formation and crystallization of the 2D/3D perovskite using three cations with varying molecular stiffness. In this series of molecules, the formation and crystallization of the 2D phase are found to be dependent on both steric hindrance around the ammonium group and molecular stiffness. Finally, we employed a 2D/3D perovskite heterointerface in a solar cell. The presence of the 2D phase, particularly those formed from flexible cations, resulted in a maximum power conversion efficiency of 21.5%. This study provides insight into critical aspects related to how bulky organic cations’ stiffness and steric hindrance influence the formation, crystallization, and distribution of 2D perovskite phases.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fonseca2024b,

title = {\textit{In Situ} PL Tracking of Halide Exchange at 3D/QD Heterojunction Perovskite Solar Cells},

author = {André F. V. Fonseca and Lucas Scalon and Brener R. C. Vale and Maria G. D. Guaita and Jefferson Bettini and Zeno C. Brandão and Luiz F. Zagonel and Lázaro A. Padilha and Ana F. Nogueira},

doi = {10.1021/acsenergylett.4c01268},

issn = {2380-8195},

year  = {2024},

date = {2024-06-14},

journal = {ACS Energy Lett.},

volume = {9},

number = {6},

pages = {3177--3186},

publisher = {American Chemical Society (ACS)},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Scalon2024b,

title = {Understanding and Controlling the Photoluminescence Line Shapes of 2D Perovskites with Chiral Methylbenzylammonium-Based Cations},

author = {Lucas Scalon and Arianne New and Ziyuan Ge and Navendu Mondal and Raquel Dantas Campos and Claudio Quarti and David Beljonne and Ana Flávia Nogueira and Artem A. Bakulin and Yana Vaynzof},

doi = {10.1021/acs.chemmater.3c03234},

issn = {1520-5002},

year  = {2024},

date = {2024-05-14},

journal = {Chem. Mater.},

volume = {36},

number = {9},

pages = {4331--4342},

publisher = {American Chemical Society (ACS)},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Mota2024,

title = {Effect of different side chains on alternating copolymers of benzodithiophene and thiophene in organic solar cells},

author = {Isabela Custódio Mota and Jonathan Rubio Arias and Francineide Lopes de Araújo and Ana Flávia Nogueira and Maria de Fátima Vieira Marques},

doi = {10.1002/app.55283},

issn = {1097-4628},

year  = {2024},

date = {2024-05-05},

journal = {J of Applied Polymer Sci},

volume = {141},

number = {17},

publisher = {Wiley},

abstract = {AbstractPolymeric semiconductors offer the dual advantages of lightness and flexibility, facilitating the large‐scale production of organic electronic devices. In the present research, electron donor polymers were synthesized incorporating high electron density aromatic units, specifically benzodithiophene (BDT) and thiophene (Th), to explore their efficacy in organic electronics. This systematic study focused on evaluating the impact of varying side chains on the material properties of these polymers. It was found that polymers with Th side chains exhibited significantly enhanced thermal stability, approximately 100°C higher than their alkoxide side chain counterparts. For the polymer PEHO‐BDT3HT, a bandgap value of around 1.6 eV was obtained. Furthermore, binary devices were developed using these novel copolymers, among which PDT‐BDT3HT demonstrated superior photovoltaic performance, achieving a power conversion efficiency of 1.56% without any optimization. This work not only sheds light on the influence of side chain variations in polymer properties but also showcases the potential of BDT and Th‐based copolymers in the field of organic electronics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}