@article{pmid31234406,

title = {Progress on Electrolytes Development in Dye-Sensitized Solar Cells},

author = {Haider Iftikhar and Gabriela Gava Sonai and Syed Ghufran Hashmi and Ana Flávia Nogueira and Peter David Lund},

doi = {10.3390/ma12121998},

issn = {1996-1944},

year  = {2019},

date = {2019-06-01},

journal = {Materials (Basel)},

volume = {12},

number = {12},

abstract = {Dye-sensitized solar cells (DSSCs) have been intensely researched for more than two decades. Electrolyte formulations are one of the bottlenecks to their successful commercialization, since these result in trade-offs between the photovoltaic performance and long-term performance stability. The corrosive nature of the redox shuttles in the electrolytes is an additional limitation for industrial-scale production of DSSCs, especially with low cost metallic electrodes. Numerous electrolyte formulations have been developed and tested in various DSSC configurations to address the aforementioned challenges. Here, we comprehensively review the progress on the development and application of electrolytes for DSSCs. We particularly focus on the improvements that have been made in different types of electrolytes, which result in enhanced photovoltaic performance and long-term device stability of DSSCs. Several recently introduced electrolyte materials are reviewed, and the role of electrolytes in different DSSC device designs is critically assessed. To sum up, we provide an overview of recent trends in research on electrolytes for DSSCs and highlight the advantages and limitations of recently reported novel electrolyte compositions for producing low-cost and industrially scalable solar cell technology.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31692661,

title = {Nanoscale mapping of chemical composition in organic-inorganic hybrid perovskite films},

author = {R Szostak and J C Silva and S-H Turren-Cruz and M M Soares and R O Freitas and A Hagfeldt and H C N Tolentino and A F Nogueira},

doi = {10.1126/sciadv.aaw6619},

issn = {2375-2548},

year  = {2019},

date = {2019-01-01},

journal = {Sci Adv},

volume = {5},

number = {10},

pages = {eaaw6619},

abstract = {Lead-based organic-inorganic hybrid perovskite (OIHP) solar cells can attain efficiencies over 20%. However, the impact of ion mobility and/or organic depletion, structural changes, and segregation under operating conditions urge for decisive and more accurate investigations. Hence, the development of analytical tools for accessing the grain-to-grain OIHP chemistry is of great relevance. Here, we used synchrotron infrared nanospectroscopy (nano-FTIR) to map individual nanograins in OIHP films. Our results reveal a spatial heterogeneity of the vibrational activity associated to the nanoscale chemical diversity of isolated grains. It was possible to map the chemistry of individual grains in CsFAMA [CsFAMAPb(IBr)] and FAMA [FAMAPb(IBr)] films, with information on their local composition. Nanograins with stronger nano-FTIR activity in CsFAMA and FAMA films can be assigned to PbI and hexagonal polytype phases, respectively. The analysis herein can be extended to any OIHP films where organic cation depletion/accumulation can be used as a chemical label to study composition.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid29882399,

title = {Humidity-Induced Photoluminescence Hysteresis in Variable Cs/Br Ratio Hybrid Perovskites},

author = {John M Howard and Elizabeth M Tennyson and Sabyasachi Barik and Rodrigo Szostak and Edo Waks and Michael F Toney and Ana F Nogueira and Bernardo R A Neves and Marina S Leite},

doi = {10.1021/acs.jpclett.8b01357},

issn = {1948-7185},

year  = {2018},

date = {2018-06-01},

journal = {J Phys Chem Lett},

volume = {9},

number = {12},

pages = {3463--3469},

abstract = {Hybrid organic-inorganic perovskites containing Cs are a promising new material for light-absorbing and light-emitting optoelectronics. However, the impact of environmental conditions on their optical properties is not fully understood. Here, we elucidate and quantify the influence of distinct humidity levels on the charge carrier recombination in Cs FAPb(I Br) perovskites. Using in situ environmental photoluminescence (PL), we temporally and spectrally resolve light emission within a loop of critical relative humidity (rH) levels. Our measurements show that exposure up to 35% rH increases the PL emission for all Cs (10-17%) and Br (17-38%) concentrations investigated here. Spectrally, samples with larger Br concentrations exhibit PL redshift at higher humidity levels, revealing water-driven halide segregation. The compositions considered present hysteresis in their PL intensity upon returning to a low-moisture environment due to partially reversible hydration of the perovskites. Our findings demonstrate that the Cs/Br ratio strongly influences both the spectral stability and extent of light emission hysteresis. We expect our method to become standard when testing the stability of emerging perovskites, including lead-free options, and to be combined with other parameters known for affecting material degradation, e.g., oxygen and temperature.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid29882410,

title = {Two-Photon Absorption and Two-Photon-Induced Gain in Perovskite Quantum Dots},

author = {Gabriel Nagamine and Jaqueline O Rocha and Luiz G Bonato and Ana F Nogueira and Zhanet Zaharieva and Andrew A R Watt and Carlos H de Brito Cruz and Lazaro A Padilha},

doi = {10.1021/acs.jpclett.8b01127},

issn = {1948-7185},

year  = {2018},

date = {2018-06-01},

journal = {J Phys Chem Lett},

volume = {9},

number = {12},

pages = {3478--3484},

abstract = {Perovskite quantum dots (PQDs) emerged as a promising class of material for applications in lighting devices, including light emitting diodes and lasers. In this work, we explore nonlinear absorption properties of PQDs showing the spectral signatures and the size dependence of their two-photon absorption (2PA) cross-section, which can reach values higher than 10 GM. The large 2PA cross section allows for low threshold two-photon induced amplified spontaneous emission (ASE), which can be as low as 1.6 mJ/cm. We also show that the ASE properties are strongly dependent on the nanomaterial size, and that the ASE threshold, in terms of the average number of excitons, decreases for smaller PQDs. Investigating the PQDs biexciton binding energy, we observe strong correlation between the increasing on the biexciton binding energy and the decreasing on the ASE threshold, suggesting that ASE in PQDs is a biexciton-assisted process.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31458511,

title = {Three-Dimensional Superlattice of PbS Quantum Dots in Flakes},

author = {Viktor A Ermakov and José Maria Clemente da Silva Filho and Luiz Gustavo Bonato and Naga Vishnu Vardhan Mogili and Fabiano Emmanuel Montoro and Fernando Iikawa and Ana Flavia Nogueira and Carlos Lenz Cesar and Ernesto Jiménez-Villar and Francisco Chagas Marques},

doi = {10.1021/acsomega.7b01791},

issn = {2470-1343},

year  = {2018},

date = {2018-02-01},

journal = {ACS Omega},

volume = {3},

number = {2},

pages = {2027--2032},

abstract = {In the last two decades, many experiments were conducted in self-organization of nanocrystals into two- and three-dimensional (3D) superlattices and the superlattices were synthesized and characterized by different techniques, revealing their unusual properties. Among all characterization techniques, X-ray diffraction (XRD) is the one that has allowed the confirmation of the 3D superlattice formation due to the presence of sharp and intense diffraction peaks. In this work, we study self-organized superlattices of quantum dots of PbS prepared by dropping a monodispersed colloidal solution on a glass substrate at different temperatures. We showed that the intensity of the low-angle XRD peaks depends strongly on the drying time (substrate temperature). We claim that the peaks are originated from the 3D superlattice. Scanning electron microscopy images show that this 3D superlattice (PbS quantum dots) is formed in flake's shape, parallel to the substrate surface and randomly oriented in the perpendicular planes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid29276832,

title = {Surface Photovoltage Measurements on a Particle Tandem Photocatalyst for Overall Water Splitting},

author = {Mauricio A Melo and Zongkai Wu and Benjamin A Nail and Alexandra T De Denko and Ana F Nogueira and Frank E Osterloh},

doi = {10.1021/acs.nanolett.7b04020},

issn = {1530-6992},

year  = {2018},

date = {2018-01-01},

journal = {Nano Lett},

volume = {18},

number = {2},

pages = {805--810},

abstract = {Surface photovoltage spectroscopy (SPS) is used to measure the photopotential across a Ru-SrTiO:Rh/BiVO particle tandem overall water splitting photocatalyst. The tandem is synthesized from Ru-modified SrTiO:Rh nanocrystals and BiVO microcrystals by electrostatic assembly followed by thermal annealing. It splits water into H and O with an apparent quantum efficiency of 1.29% at 435 nm and a solar to hydrogen conversion efficiency of 0.028%. According to SPS, a photovoltage develops above 2.20 eV, the effective band gap of the tandem, and reaches its maximal value of -2.45 V at 435 nm (2.44 mW cm), which corresponds to 96% of the theoretical limit of the photocatalyst film on the fluorine-doped tin-oxide-coated glass (FTO) substrate. Charge separation is 82% reversible with 18% of charge carriers being trapped in defect states. The unusually strong light intensity dependence of the photovoltage (1.16 V per decade) is attributed to depletion layer changes inside of the BiVO microcrystals. These findings promote the understanding of solar energy conversion with inorganic particle photocatalysts.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid28574246,

title = {Gel Electrolytes with Polyamidopyridine Dendron Modified Talc for Dye-Sensitized Solar Cells},

author = {Marcos A Santana Andrade and Armi Tiihonen and Kati Miettunen and Peter Lund and Ana F Nogueira and Heloise O Pastore},

doi = {10.1021/acsami.7b00897},

issn = {1944-8252},

year  = {2017},

date = {2017-06-01},

journal = {ACS Appl Mater Interfaces},

volume = {9},

number = {24},

pages = {20454--20466},

abstract = {Organic-inorganic hybrid layered materials are proposed as additives in a quasi-solid gel electrolyte for dye-sensitized solar cells. Talcs could provide a low-cost and environmentally friendly, as well as abundant, option as gelators. Here, talcs were prepared by functionalizing an organotalc with three polyamidopyridine dendron generations, PAMPy-talc-Gn (n = 1, 2 and 3). PAMPy dendrons grow parallel to the lamellae plane and form an organized structure by intermolecular interactions. In addition, polyiodide-dendron charge-transfer complexes were prepared onto the organotalc by adsorption of iodine. In this work, the effect of the dendron generation of PAMPy-talc and the influence of polyiodide intercalation on solar cell performance and stability were investigated. The best results were reached with the use of lowest-generation PAMPy-talc (η = 4.5 ± 0.3%, V = 710 ± 19 mV, J = 10.4 ± 0.9 mA cm, and FF = 61 ± 2%): 15% higher efficiency compared to similar liquid devices. While some previously studied talcs illustrate very strong absorption of the iodide from the electrolyte, in the case of PAMPy-talc such interfering effects were absent: In a 1000 h light soaking test, the PAMPy-talc cells both with and without polyiodide intercalation demonstrated stable performances. Furthermore, the color analysis of the electrolyte indicated that the color of the electrolyte remained stable after an initial period of stabilization, which is a good indication of the compound being stable and not absorbing charge carriers from the electrolyte. The performance and stability results indicate that PAMPy-talc has potential as a gelling method for electrolytes for dye solar cells.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}