Scale up of microwave annealed FA0.83Cs0.17PbI1.8Br1.2 perovskite towards an industrial scale

ABSTRACT: Perovskite solar cells (PSCs) efficiency has rapidly increased from the initial 3.8 to recent 24.2%. This high efficiency has attracted serious worldwide researchers and industry attention due to their low material cost, and simple solution-based fabrication process. However, fundamental studies on PSCs are usually produced through lab-scale actions and carried out on small-area devices (≤1 cm2). Here we present the advances of up-scaling using microwave (MW) annealing of perovskite films on large area specimens (~16 cm2), looking forward the industrial-scale. Morphological, structural and optical characterization were performed to confirm the effectiveness of the scaled up MW annealing.info:eu-repo/semantics/publishedVersio

Synthesis, photophysical and electrochemical properties of π-conjugated pyrene based down-shifting molecules with fluorinated aryl groups

ABSTRACT: Pyrene molecule, with excellent photophysical properties (strong absorption cross section, excellent emission properties and a long-excited state lifetime), excellent thermal and photochemical stability, has been widely used as a building block for the synthesis of pyrene-based fluorophores for optoelectronic applications. In this work, we report the synthesis of two series of pyrene-pi-A compounds, series I (3-6) and II (10-13), in which nitro, cyano, cyanoacrylonitrile and cyanoacrylic acid as electron acceptor groups are connected to the pyrene core via aryl or fluoroaryl pi-conjugating bridges. The incorporation of fluorine atom on the pi-extension bridge cause a slightly red-shift at emission wavelength (lambda em) in solution and polymethylmethacrylate (PMMA) films and in-crease the Stokes shift due to greater stabilization of molecular orbitals in the excited state, especially for series I. Solvatochromic measurements and theoretical computational studies suggest a higher intramolecular charge transfer in the excited state for series II when compared to series I due to their stronger electron acceptor moieties. All pyrene derivatives are stable and exhibited initial mass loss at temperature above 200 degrees C. The good photophysical and thermal properties of the synthesized pyrene derivatives, associated with high molar ab-sorption coefficients in the UV spectrum and good fluorescence emission in the range of 430-480 nm (series I) and 505-567 nm (series II) in PMMA films, make them possible candidates for organic light-emitting diode (OLED) and luminescent down-shifting (LDS) layers for stable perovskite solar cells, respectively.info:eu-repo/semantics/publishedVersio

Synthesis, photophysical and electrochemical properties of perylene dyes

ABSTRACT: Perylene dyes comprising: (i) 4-alkoxyphenylamino moiety in the 9-position as a strong donating group, (ii) cyanoacrylic acid as electron acceptor and anchoring group and (iii) a triple bond as short and rigid linker between perylene core and the acceptor group have been successfully synthesized. Their photophysical (i.e. absorption and emission spectra, molar extinction coefficients, fluorescence quantum yields and lifetime measurements) and electrochemical properties were investigated. The dyes display intense absorption in the visible exhibit high molar absorption coefficients making them good light harvesting materials for ss-DSCs.info:eu-repo/semantics/publishedVersio

Charge transport and recombination of dye sensitized 1D nanostructured-TiO2 films prepared by reactive sputtering

Dye sensitized solar cells (DSCs) are governed by light absorption, charge injection, electron transport and recombination and electrolyte diffusion. One way to improve the efficiency of these devices is by the design of highly ordered nanostructured semiconductor materials.The advantages can be two-fold: Firstly charge transport within the metal-oxide can be enhanced and hence thicker films can be employed and secondly, the complete permeation with a solid-state hole-transport medium of the sensitized metal-oxide can be facilitated. Nanostructured materials should promote vectorial electron diffusion and have as few recombination sights as possible so as to further enhance electron lifetimes and electron collection efficiencies. These materials should also have a high surface area so as to allow for efficient dye-loading and hence light absorption. Highly ordered TiO2 nanostructured films were prepared by reactive sputtering and their charge transport characteristics evaluated in DSCs. These were compared to DSCs employing mesoporous TiO2 films prepared by doctor blade technique using commercial paste. Charge transport characteristics were evaluated by impedance spectroscopy (IS), incident photon to current conversion efficiencies (IPCE) and current-voltage (iV) curves under simulated AM1.5G irradiation. Film morphology and structural properties were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively

New coumarin-[60] fullerene dyads connected by an alkynyl linkage: Synthesis and fluorescence studies. Evidence for efficient singlet-singlet energy transfer

Two new coumarin-[60] fullerene dyads, in which an alkyne group covalently links C60 to coumarin, are synthesized via 1,3-dipolar cycloaddition and spectroscopically characterized. Their photophysical properties in apolar (toluene) and polar (THF and benzonitrile) solvents are studied at room temperature, revealing the nature and polarity dependence of the excited-state interactions between the coumarin and C60 moieties. In both dyads and in all solvents, a strong quenching of the coumarin emission by C60 was observed. It mainly results from a fast and efficient singletesinglet resonance energy transfer from the coumarin moiety to the C60 moiety, but an electron transfer contribution, enhanced in polar solvents, also exists. In toluene, the fluorescence emission of the fullerene moiety is increased by the nonradiative energy transfer process, which occurs mainly by a dipoleedipole (FRET) mechanism. In polar solvents (THF and benzonitrile), fast electron transfer from ground-state coumarin to excited fullerene is significant, leading to a partial or complete quenching of the fullerene emission, depending on the dyad

Manual de procedimentos - apoio na gestão da mudança: Trabalho de Projecto

A aproximação dos serviços às populações e a melhoria dos serviços prestados na administração pública leva a que estas organizações tenham de estar constantemente a alterar a sua forma de agir para se conseguirem adequar ao meio onde estão inseridas. É, portanto, necessário um processo de mudança devidamente organizado e gerido. As organizações públicas sentiram a necessidade de adotar sistemas de informação e de controlo de gestão adequados de forma a melhorar as tomadas de decisões, introduzir a avaliação de desempenho e aumentar os índices de eficiência, eficácia e qualidade dos serviços públicos. No entanto, qualquer processo de mudança, por mais necessário e bem preparado que seja, enfrenta sempre resistência, seja ela a nível individual, seja a nível organizacional. É necessário saber gerir estas mudanças, para tal toma-se importante a constituição de uma boa equipa orientadora da mudança, com capacidade de liderança, necessária para uma melhor aceitação por parte dos funcionários envolvidos. Não menos importante é a medição da performance que visa produzir informação relevante para a melhoria da gestão e das tomadas de decisões, contribuindo assim para uma melhoria global dos resultados. O Balanced Scorecard pode ser a ferramenta ideal para trazer inovação aos serviços públicos. Assim, este trabalho de projeto consiste, depois de uma análise às reformas que tem vindo a ocorrer na administração pública bem como aos modelos e ferramentas existentes para a avaliação do desempenho do sector público, na elaboração de um Manual de Procedimentos, que servirá de base na reorganização dos Serviços da Divisão Administrativa da Câmara Municipal de Tomar que se encontra numa fase de mudança, manual esse que servirá também para melhoria do desempenho dos Serviços e para uma possível implementação do Balanced Scorecard. ABSTRACT: The alignment of services to citizens and improve services in public administration means that these organizations have to constantly change their ways if they can adapt to the environment where they operate. It is therefore a necessary process of change properly organized and managed. Public organizations have felt the need for information systems and monitoring of appropriate management to improve decision making, introduce the evaluation of performance and increasing levels of efficiency, effectiveness and quality of public services. However, any process of change, however necessary and well-prepared it is, always face resistance, either individually or at the organizational level. You must know how to manage these changes, for such it is important to set up a good team guiding change, and leadership skills necessary for better acceptance by the employees involved. No less important is the measurement of performance that aims to produce relevant information for improved management and decision making, thus contributing to an overall improvement in results. The Balanced Scorecard can be an ideal tool to bring innovation to public services. Thus, this study design is, after a review of the reforms that have been taking place in public administration and the existing models and tools for evaluating the performance of the public sector, development of a Procedures Manual, which is basic the reorganization of the Administrative Services Division of the City Council to take in a phase of change, that this manual will also serve to improve the performance of services and a possible implementation of the Balanced Scorecard

Emotion regulation and mental health among professionals of long-term care institutions for older adults: The mediating role of work engagement

background This study examined whether work engagement mediated the association between emotion regulation and mental health of professionals working in long-term care institutions for older adults in Brazil. participants and procedure A cross-sectional study with a total of 104 professionals working in 13 long-term care facilities for the elderly in Brazil was conducted. Emotion regulation (expressive suppression and cognitive reappraisal), work engagement (vigor, dedication, and absorption), and mental health (depression, anxiety, and stress) were measured using self-report scales. Multiple mediation models were used to test the mediating role of engagement. results Expressive suppression was associated with more vigor, which in turn was associated with less anxiety and stress; cognitive reappraisal was associated with more vigor, which in turn was associated with less anxiety and stress. No indirect effects were found for depression. conclusions Expressive suppression and cognitive reappraisal strategies to regulate emotions seem to be associated with more vigor in terms of resilience and persistence to deal with work demands in these professionals. These results seem to suggest that workers who are more capable of regulating their emotions (using both expressive suppression and cognitive reappraisal in a flexible way according to work demands) are more likely to be resilient, invest in their profession, and be persistent in the face of difficulties. This, in turn, contributes to protecting them from experiencing anxiety and stress.4317-C2CF-53B0 | Rute Sofia Ribeiro Brites Diasinfo:eu-repo/semantics/publishedVersio

Dye assessment in nanostructured TiO2 sensitized films by microprobe techniques

Dye sensitized solar cells (DSCs) have received considerable attention once this technology offers economic and environmental advantages over conventional photovoltaic (PV) devices. The PV performance of a DSC relies on the characteristics of its photoanode, which typically consists of a nanocrystalline porous TiO2 film, enabled with a large adsorptive surface area. Dye molecules that capture photons from light during device operation are attached to the film nanoparticles. The effective loading of the dye in the TiO2 electrode is of utmost importance for controlling and optimizing solar cell parameters. Relatively few methods are known today for quantitative evaluation of the total dye adsorbed on the film. In this work, a new approach combining microprobe techniques namely, Ion Beam Analytical (IBA) techniques using a micro-ion beam (Rutherford Backscattering Spectrometry (RBS) and Particle Induced X-ray Emission (PIXE)) and Electron Probe Micro-Analysis (EPMA) was carried out to assess dye distribution and depth profile in TiO2 films and the dye load based on Ru/Ti mass ratio. Different 1D nanostructured TiO2 films were prepared, morphologically characterised by SEM, sensitized and analysed by the referred techniques. Dye load evaluation in different TiO2 films by three different techniques (PIXE, RBS and EPMA/ wavelength dispersive spectrometry (WDS)) provided similar results of Ru/Ti mass fraction ratio. Moreover, it was possible to assess dye surface distribution and its depth profile, by means of Ru signal, and to visualise the dye distribution in sample cross-section through X-ray mapping by EPMA/ energy dispersive spectrometry (EDS). PIXE maps of Ru and Ti indicated an homogeneous surface distribution. The assessment of ruthenium depth profile by RBS showed that some films have homogeneous Ru depth distribution while others present different Ru concentration in the top layer (2 ìm thickness). These results are consistent with the EPMA/EDS maps obtained. EPMA (WDS and EDS) together with IBA techniques proved to be powerful tools for functional materials characterisation and provided very promising results in the study of nanostructured TiO2 sensitized films

Assessment of dye distribution in sensitized solar cells by microprobe techniques

Dye sensitized solar cells (DSCs) have received considerable attention once this technology offers economic and environmental advantages over conventional photovoltaic (PV) devices. The PV performance of a DSC relies on the characteristics of its photoanode, which typically consists of a nanocrystalline porous TiO2 film, enabled with a large adsorptive surface area. Dye molecules that capture photons from light during device operation are attached to the film nanoparticles. The effective loading of the dye in the TiO2 electrode is of paramount relevance for controlling and optimizing solar cell parameters. Relatively few methods are known today for quantitative evaluation of the total dye adsorbed on the film. In this context, microprobe techniques come out as suitable tools to evaluate the dye surface distribution and depth profile in sensitized films. Electron Probe Microanalysis (EPMA) and Ion Beam Analytical (IBA) techniques using a micro-ion beam were used to quantify and to study the distribution of the Ru organometallic dye in TiO2 films, making use of the different penetration depth and beam sizes of each technique. Different 1D nanostructured TiO2 films were prepared, morphologically characterized by SEM, sensitized and analyzed by the referred techniques. Dye load evaluation in different TiO2 films by three different techniques (PIXE, RBS and EPMA/WDS) provided similar results of Ru/Ti mass fraction ratio. Moreover, it was possible to assess dye surface distribution and its depth profile, by means of Ru signal, and to visualize the dye distribution in sample cross-section through X-ray mapping by EPMA/EDS. PIXE maps of Ru and Ti indicated an homogeneous surface distribution. The assessment of Ru depth profile by RBS showed that some films have homogeneous Ru depth distribution while others present different Ru concentration in the top layer (2 lm thickness). These results are consistent with the EPMA/EDS maps obtained

Microscopy techniques for dye distribution in DSCs nanocrystalline TiO2 films

Capture of sunlight has attracted an increasing interest in the scientific community and triggered the development of efficient and cheap photovoltaic devices. Amongst recent generation technologies for solar energy conversion, dye-sensitized solar cells (DSCs) show an optimal trade-off between high-conversion efficiency and low-cost manufacturing. For the last two decades, significant progress has been made and best energy conversion efficiency of the DSC at the laboratory scale has surpassed 12% [1]. A lot of work has focused on the enlargement of surface areas to enhance the amount of adsorbed dyes by reduction of nanoparticle sizes or utilization of novel structures. Nevertheless there remain some crucial details of DSC operation for which limited information is available, namely dye diffusion and adsorption, surface coverage and dye distribution throughout the nc-TiO2 film. Microprobe techniques can be powerful tools to evaluate the dye load, the dye distribution and dye depth profile in sensitized films. Electron Probe Microanalysis (EPMA) and Ion Beam Analytical (IBA) techniques using a micro-ion beam, namely micro-Particle Induced X-ray Emission ( PIXE) and Rutherford Backscattering Spectrometry (RBS), were used to quantify and to study the distribution of the ruthenium organometallic (N719) dye in TiO2 films, profiting from the different penetration depth and beam sizes of each technique. Two different types of films were prepared and sensitized, mesoporous nanoparticles and 1D nanostructured TiO2 films (figure 1). Despite the low concentration of Ru, the high sensitive analytical techniques used allowed to assess the Ru surface distribution and depth profile. Fig. 2 shows the PIXE maps of Ru and Ti indicating an homogeneous surface distribution. The same figure presents the RBS spectra obtained with a 2 MeV proton beam of the same sample showing that a good spectra fit is obtained considering only two sample layers: the first one with a 1.7 ìm thickness; the second one being the SiO2 substrate. The Ru RBS signal also shows that the dye has an homogeneous depth distribution. Due to the fine spatial resolution of the EPMA/WDS (Wavelength Dispersive Spectroscopy) technique it was possible to visualise the dye distribution in sample cross-section (with micrometer or submicrometer dimensions) as presented in Fig. 3 for the elemental mapping of a mesoporous nanoparticle TiO2 film. Dye load evaluation by two different techniques (ìPIXE and EPMA/WDS) provided similar results (Ru/Ti values around 0.5 %). The distribution analysis of the organometallic dye (N719) was done through ruthenium distribution via X-ray mapping. RBS was used to assess the ruthenium depth profile. This assessment can lead to a better understanding of the device performance