Defect passivation in zinc tin oxide: improving the transparency-conductivity trade-off and comparing with indium-based materials

Transparent conductive oxides (TCOs) are essential in technologies coupling light and electricity. Due to their good optoelectronic properties and the production scalability, Sn-doped indium oxide (In2O3:Sn) is the preferred TCO in industrial applications. Nonetheless indium is scarce in the Earth's crust and its availability might be compromised over the next decades. To address this issue, this doctoral project aims to (i) improve the optoelectronic properties of In-free TCOs seeking to match those of In2O3:Sn, and (ii) refine the optoelectronic properties of In2O3-based films to decrease the In consumption in applications. To accomplish this, we investigated the links between the defects, the microstructure and the optoelectronic properties of two families of TCOs, indium- and tin-based oxides. First, we studied the evolution in the optoelectronic properties and microstructure of amorphous zinc tin oxide (a-ZTO) when annealed up to 500C in oxidizing, neutral, and reducing atmospheres. We show that annealing in atmospheric pressure at temperatures > 300C decreases the detrimental subgap absorptance while increasing the electron mobility (mu). Thermal treatments in reducing atmospheres increase the free-carrier density (Ne) and the subgap absorptance. None of the thermal treatments resulted in important changes in the amorphous microstructure. Combining these results and density functional theory (DFT) calculations, oxygen deficiencies (VO) were identified as the source of detrimental subgap absorption. VO can act as donors but also as electron scattering centres. Based on these results, a-ZTO with Ό up to 35 cm2/Vs, is demonstrated by high-temperature defect passivation. Profiting from the microstructure stability of a-ZTO, this material was used as a recombination junction in a tandem solar cell which require a high-temperature step in its processing. The passivation scheme might be problematic for temperature-sensitive technologies. Therefore, we demonstrated an alternative low-temperature passivation method, which relies on co-sputtering a-ZTO with SiO2 . Using two Sn-based oxides with different composition and microstructure: a-ZTO and SnO2 , and results of DFT calculations, we demonstrate that SiO2 contribution is twofold. (i) The oxygen from SiO2 passivate the VO in SnO2 and a-ZTO. (ii) The formation energy of the ionized VO is lowered by the silicon-atoms, enabling defects that do not contribute to the subgap absorptance. This passivation scheme improves the optical properties without affecting the electrical conductivity, overcoming the optoelectronic trade-off in Sn-based TCOs. Finally, we study an In-based high-Ό TCO: Zr-doped In2O3. Films of In2O3:Zr with thickness from 15 nm-100 nm were sputtered in the amorphous state and annealed in different atmospheres. Annealing in air yields fully crystalline films with high transparency and a high-mu limited by phonon and ionized impurity scattering. 15 nm-thick films exhibit an average absorptance of < 0.5 % (between 390 nm-2000 nm) and an mu of 50 cm2/Vs increasing to 105 cm2/Vs for 100 nm-thick films. Alternatively, annealing in a neutral or reducing atmospheres result in higher mu for films thinner than 50 nm as a high Ne is maintained. The demonstration of thickness reduction while keeping high lateral mu makes In2O3:Zr is an alternative to reduce In in applications such as flexible displays, solar cells and light emitting diodes

Zinc tin oxide as high-temperature stable recombination layer for mesoscopic perovskite/silicon monolithic tandem solar cells

Perovskite/crystalline silicon tandem solar cells have the potential to reach efficiencies beyond those of silicon single-junction record devices. However, the high-temperature process of 500 °C needed for state-of-the-art mesoscopic perovskite cells has, so far, been limiting their implementation in monolithic tandem devices. Here, we demonstrate the applicability of zinc tin oxide as a recombination layer and show its electrical and optical stability at temperatures up to 500 °C. To prove the concept, we fabricate monolithic tandem cells with mesoscopic top cell with up to 16% efficiency. We then investigate the effect of zinc tin oxide layer thickness variation, showing a strong influence on the optical interference pattern within the tandem device. Finally, we discuss the perspective of mesoscopic perovskite cells for high-efficiency monolithic tandem solar cells

Analysis of TcdB Proteins within the Hypervirulent Clade 2 Reveals an Impact of RhoA Glucosylation on Clostridium difficile Proinflammatory Activities

Clostridium difficile strains within the hypervirulent clade 2 are responsible for nosocomial outbreaks worldwide. The increased pathogenic potential of these strains has been attributed to several factors but is still poorly understood. During a C. difficile outbreak, a strain from this clade was found to induce a variant cytopathic effect (CPE), different from the canonical arborizing CPE. This strain (NAP1V) belongs to the NAP1 genotype but to a ribotype different from the epidemic NAP1/RT027 strain. NAP1V and NAP1 share some properties, including the overproduction of toxins, the binary toxin, and mutations in tcdC. NAP1V is not resistant to fluoroquinolones, however. A comparative analysis of TcdB proteins from NAP1/RT027 and NAP1V strains indicated that both target Rac, Cdc42, Rap, and R-Ras but only the former glucosylates RhoA. Thus, TcdB from hypervirulent clade 2 strains possesses an extended substrate profile, and RhoA is crucial for the type of CPE induced. Sequence comparison and structural modeling revealed that TcdBNAP1 and TcdBNAP1V share the receptor-binding and autoprocessing activities but vary in the glucosyltransferase domain, consistent with the different substrate profile. Whereas the two toxins displayed identical cytotoxic potencies, TcdBNAP1 induced a stronger proinflammatory response than TcdBNAP1V as determined in ex vivo experiments and animal models. Since immune activation at the level of intestinal mucosa is a hallmark of C. difficile-induced infections, we propose that the panel of substrates targeted by TcdB is a determining factor in the pathogenesis of this pathogen and in the differential virulence potential seen among C. difficile strains.Wellcome Trust, United States a Trevor D Lawley bajo el número 098051Consejo Nacional de Rectores/[803-B1-654]/CONARE/Costa RicaConsejo Nacional de Rectores/[803-B4-652]/CONARE/Costa RicaUniversidad de Costa Rica/[803-B5-107]/UCR/Costa RicaUniversidad de Costa Rica/[803-B5-108]/UCR/Costa RicaConsejo Nacional para Investigaciones Científicas y Tecnológicas/[FV-0004-13. HHS]/CONICIT/Costa RicaNational Institutes of Health/[R01AI095755]/NIH/Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Centro de Investigación en Enfermedades Tropicales (CIET

Brucella abortus Uses a Stealthy Strategy to Avoid Activation of the Innate Immune System during the Onset of Infection

To unravel the strategy by which Brucella abortus establishes chronic infections, we explored its early interaction with innate immunity. Methodology/Principal Findings Brucella did not induce proinflammatory responses as demonstrated by the absence of leukocyte recruitment, humoral or cellular blood changes in mice. Brucella hampered neutrophil (PMN) function and PMN depletion did not influence the course of infection. Brucella barely induced proinflammatory cytokines and consumed complement, and was strongly resistant to bactericidal peptides, PMN extracts and serum. Brucella LPS (BrLPS), NH-polysaccharides, cyclic glucans, outer membrane fragments or disrupted bacterial cells displayed low biological activity in mice and cells. The lack of proinflammatory responses was not due to conspicuous inhibitory mechanisms mediated by the invading Brucella or its products. When activated 24 h post-infection macrophages did not kill Brucella, indicating that the replication niche was not fusiogenic with lysosomes. Brucella intracellular replication did not interrupt the cell cycle or caused cytotoxicity in WT, TLR4 and TLR2 knockout cells. TNF-α-induction was TLR4- and TLR2-dependent for live but not for killed B. abortus. However, intracellular replication in TLR4, TLR2 and TLR4/2 knockout cells was not altered and the infection course and anti-Brucella immunity development upon BrLPS injection was unaffected in TLR4 mutant mice. Conclusion/Significance We propose that Brucella has developed a stealth strategy through PAMPs reduction, modification and hiding, ensuring by this manner low stimulatory activity and toxicity for cells. This strategy allows Brucella to reach its replication niche before activation of antimicrobial mechanisms by adaptive immunity. This model is consistent with clinical profiles observed in humans and natural hosts at the onset of infection and could be valid for those intracellular pathogens phylogenetically related to Brucella that also cause long lasting infections

Filosóficas y Encarnadas. Investigaciones Estéticas en Argentina.

Los trabajos reunidos en el presente volumen son el resultado de una selección de las ponencias presentadas en las III Jornadas Nacionales y VII Encuentro de investigadores "Estética y Filosofía del Arte", que tuvo lugar en la Facultad de Ciencias de la Comunicación de la Universidad Nacional de Córdoba los días 1, 2, 3 y 4 de agosto de 2017. Las Jornadas fueron organizadas por el grupo de investigación “Modernidad estética y teoría crítica” (Secyt/UNC). Los textos han sido revisados a fin de adaptarlos al formato de libro y aEl presente volumen recoge los recientes avances en materia de estética producidas por diversos investigadores y equipos de investigación en Argentina. La diversidad de perspectivas oriundas de tradiciones disímiles y de objetos de reflexión de múltiples naturalezas configuran un horizonte amplio y complejo de la pregunta filosófica por el arte. El libro plantea dos vías de aproximación a este horizonte multidimensional, que atiende al modo material en que la pregunta estética se despliega en cada uno de los textos: estéticas filosóficas, que reflexionan las propias categorías de la estética en otros autores, y estéticas encarnadas, que junto a otros autores reflexionan sobre producciones artísticas concretas. Ambos modos de la estética no se platean como excluyentes ni contrapuestos sino que, como exponen las conexiones cruzadas entre los textos, constituyen prácticas teóricas en constante situación de complementariedad , diálogo e intercambio.Fil: Albín, Juan. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Altamiranda, Verónica. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Baigorria, Martín. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Belenguer, Celeste. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Bidón Chanal, Lucas. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Bohlman, Tamara. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Cabrera, Gustavo Javier. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Cangui, Adrian. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Casullo, Mariana. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Conti, Romina. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Coschica, Fernando. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Cristobo, Matías. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: De Angelis, Javier. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Galfione, María Verónica. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: García, Pilmaiquén. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Gonzalez, Alejandra. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Guzzi, José. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Isidori, Julia. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Juárez, Esteban Alejandro. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Laurenzi, Adriana. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Ledesma, Jerónimo. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: López Piñeyro, Hernán. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Palazzo, Valeria. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Perié, Alejandra. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Podestá, Florencia. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Poenitz, Paula Beatriz. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Reduello, María Eugenia. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Rivulgo, Moira Ailín. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Roldán, Eugenia. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Rossi, María José. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Rossi, María Sol. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Rucavado Rojas, Mario. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología.Fil: Tomás, Silvia Inés. Universidad Nacional de Córdoba, Facultad de Ciencias de la Comunicación, Secretaría de Ciencia y Tecnología

High performance amorphous Zn-Sn-O: impact of composition, microstructure, and thermal treatments in the optoelectronic properties

Zinc and tin oxides are both earth-abundant materials with demonstrated applicability as electrodes in several optoelectronic devices. The presence of grain boundaries in these polycrystalline films generally limits the electron mobility. By a combinatorial study of ZnO and SnO2, a transparent conducting amorphous zinc tin oxide (ZTO) electrode, free of grain boundaries, with a dense (void-free) microstructure has been developed. We show how tuning the stoichiometry (Zn4.5Sn30.2O65.3) and film's microstructure during sputtering deposition, allows achieving electron mobilities up to 25 cm(2)/Vs and free carrier concentrations of similar to 7 x 10(19) cm(-3). The effects of post-deposition thermal treatments are furthermore studied. The ZTO films keep their dense amorphous microstructure upon annealing up to 500 degrees C, as confirmed by cross-section TEM and XRD, while presenting a clear improvement in electron mobility up to 35 cm(2)/Vs when annealed in oxygen-rich atmospheres

Highly Conductive and Broadband Transparent Zr-Doped In2O3 as Front Electrode for Solar Cells (vol 8, pg 1202, 2018)

In the paper [1], the reported values of the oxygen to total flow ratio, defined as r(O2) in %, should be multiplied by a factor of 3 ± 0.1, which corresponds to the correct calibration factor for the mass flow controllers. This correction should be applied consistently throughout the paper where the r(O2) (%) is mentioned. It is important to note that this correction does not change the conclusion of the article, and all the results presented remains valid

Zr-doped indium oxide electrodes: Annealing and thickness effects on microstructure and carrier transport

Zr-doped indium oxide (In2O3:Zr) has been shown to satisfy the requirements of low resistance, wide band gap, and high infrared transmittance for application as a front contact in broadband solar cells. However, the reduction of indium usage in front of transparent electrodes is still an unsatisfied requirement. With the goal of reducing the amount of indium while leveraging its properties, in this work, In2O3 :Zr films with reduced thickness compared to those standardly used in solar cells are studied. 100 to 15-nm-thick films were sputtered at room temperature and annealed in distinct atmospheres to study the links between thickness, microstructure, and optoelectronic properties. As-deposited films exhibit an amorphous microstructure embedding bixbyite In2O3 nanocrystals. Annealing in neutral (N-2) or reducing atmosphere (H-2) allows a slight growth of these crystallites but the layers remain mostly amorphous. Whereas annealing in air results in polycrystalline films with an average grain lateral size ranging from 350 to 500 nm. The large crystalline grains formed during air annealing lead to increased electron mobility for all thickness: up to 100 cm(2)V(-1)s(-1) for 100-nm-thick films and up to 50 cm(2)V(-1)s(-1) for 15-nm-thick films, which is remarkable for such thin polycrystalline films. Conversely, H-2 annealing ensures high free-carrier densities (>1 x 10(20) cm(-3)) but not high mobilities, still achieving conductivities between 1000 and 2000 S cm(-1), with the films less than 50-nm-thick keeping high broadband transmittance. The possibility of thinning down In2O3:Zr to a few tens of nanometers while keeping both high lateral conductivity and good transparency makes this material a promising candidate to reduce the amount of indium in optoelectronic applications, such as flexible touch screens and solar cells