In this work we report how crucial is the correct design of the porphyrin sensitizers in Dye Sensitized Solar Cells (DSSCs). Only a single atom change switches-onthe efficiency from 2-3% to over 10% ...under standard measurement conditions. We used the 2,1,3-benzothiadazole (BDT) group, as a pi -conjugated linker, for the porphyrin LCVC01, a thiophene moiety for the porphyrin LCVC02 and also the furan group for the LCVC03 porphyrin, as molecular spacers between the BDT fragment and the molecule anchoring group, respectively. These three porphyrins were investigated for their application in DSSC devices. All the devices were characterized and found to achieve a record cell efficiency of 10.5% for LCVC02 but only 3.84% and 2.55% for LCVC01 and LCVC03 respectively. On one hand, the introduction of a thiophene, instead of a furan group, illustrates the importance of introducing a chemical group as a spacer, such as thiophene, between the BDT and the anchoring group. On the other hand, the selection of this group has to be correct because the change of a single atom increases the charge recombination rate and decreases the device performance. These changes can be rationalized by analyzing the dye dipoles and their interactions.
In this work we report how crucial is the correct design of the porphyrin sensitizers in Dye Sensitized Solar Cells (DSSCs). Only a single atom change
switches-on
the efficiency from 2-3% to over 10% ...under standard measurement conditions. We used the 2,1,3-benzothiadazole (BDT) group, as a π-conjugated linker, for the porphyrin
LCVC01
, a thiophene moiety for the porphyrin
LCVC02
and also the furan group for the
LCVC03
porphyrin, as molecular spacers between the BDT fragment and the molecule anchoring group, respectively. These three porphyrins were investigated for their application in DSSC devices. All the devices were characterized and found to achieve a record cell efficiency of 10.5% for
LCVC02
but only 3.84% and 2.55% for
LCVC01
and
LCVC03
respectively. On one hand, the introduction of a thiophene, instead of a furan group, illustrates the importance of introducing a chemical group as a spacer, such as thiophene, between the BDT and the anchoring group. On the other hand, the selection of this group has to be correct because the change of a single atom increases the charge recombination rate and decreases the device performance. These changes can be rationalized by analyzing the dye dipoles and their interactions.
In this work we report how crucial is the correct design of the porphyrin sensitizers in Dye Sensitized Solar Cells (DSSCs).
Two zinc-porphyrin sensitizers, 1a and 1b, bearing triphenylamine donor groups, were synthesized and their efficiencies measured in nanocrystalline TiO sub(2) dye sensitized solar cells employing ...iodide/tri-iodide and tris(1,10-phenanthroline) cobalt electrolytes. Optimized sensitization time for the TiO sub(2) photoanode was found to depend on the electrolyte employed: devices based on iodide/tri-iodide showed better efficiencies with shorter sensitization times (1.5 hours) whereas those based on tris(1,10-phenanthroline) cobalt showed better efficiencies with longer sensitization times (6 hours). From UV-Vis absorption spectra it is estimated that there is roughly twice as much dye loaded onto the TiO sub(2) film sensitized for 6 hours compared to the 1.5 hour film. Interfacial processes were probed using transient photovoltage, transient absorption and fluorescence lifetime measurements. The results indicate that sensitization time does not affect either dye regeneration or interfacial recombination processes in the presence of either electrolyte. However, sensitization time does have a considerable impact on device photocurrent, and moreover, the effect is different for the two electrolytes studied. This work demonstrates how device preparation must be tailored carefully depending on the electrolyte red/ox couple used.
El Cambio Climático, consecuencia de la extralimitación de la contaminación con energía fósil proveniente del crecimiento material de la sociedad humana desde la Revolución Industrial, ha ...desencadenado un cambio de las condiciones conocidas del Ciclo Hidrológico, con manifestaciones regionales particulares. La extralimitación también se ha manifestado directamente en el sector del agua. Esta aguda transformación, según lo indican los más recientes Informes del Intergovernmental Panel of Climate Change (IPCC) pone en una encrucijada la construcción de condiciones sostenibles del Ciclo Urbano del Agua. Se exponen en este trabajo los principales ejes para un enfoque adaptativo de los abastecimientos de agua a las condiciones extremas que acarrea el Cambio Climático; desafíos que se suman a los déficit ya existentes. Se focaliza un caso de referencia para identificar criterios coherentes de diseño de modelos que contribuyan a la toma de decisiones locales sostenibles en condiciones de cambio como las que se exponen.
In this paper a Dynamic Simulation Model has been used to present the likely responses of the electricity industries’ latest perturbations such as: changes in environmental regulations, international ...fuel market evolution, restriction on fuel supply and increase on fuel prices, liberalisation of the European Electricity Market, and the results of applying energy policies and official tools such as taxes and emission allowances.
The case under study refers to the Teruel Power Plant, built after the 1970s oil crisis to ensure national electricity supply; burning domestically produced coal in order to ensure local mining activity. The Teruel Power Plant has made relevant investments in order to meet emission limits, such as a Flue Gas Desulphurisation Plant. The economic viability of the power stations has to be analysed after environmental costs have been internalised.
A system is defined that studies the coal-firing Electric Power Plant selling energy to the free electricity market, whenever the generation cost is competitive. A Dynamic Simulation Model would appear to be an accurate tool to optimise power station management within different frameworks.
La huella ecológica es un indicador de sostenibilidad de índice único, desarrollado por Rees y Wackernagel en 1996, que mide todos los impactos que produce una población, expresados en hectáreas de ...ecosistemas o “naturaleza”. Utilizada habitualmente para regiones o países (…) hemos constatado que dicho indicador podía utilizarse también en las empresas y en cualquier tipo de organización (Doménech, 2006). En este trabajo se calcula la Huella Ecológica Corporativa de una empresa del sector comercial, concretamente un concesionario de automóviles del este español, a partir de los consumos anuales efectuados por la empresa. A continuación se recalculan determinados índices para la conversión de consumo de materiales a hectáreas, siguiendo la misma metodología empleada por J.L. Doménech en el cálculo de la huella de la Autoridad Portuaria de Gijón. Finalmente se proponen nuevos índices en sustitución de los anteriores y se diseña una nueva herramienta (hoja de cálculo) para el cálculo de la Huella Ecológica Corporativa.
Emotional response in aging is typically studied using the dimensional or the discrete models of emotion. Moreover, it is typically studied using subjective or physiological variables but not using ...both perspectives simultaneously. Additionally, tenderness is neglected in emotion induction procedures with older adults, with the present work being the first to include the study of physiological tenderness using film clips. This study integrated two separate approaches to emotion research, comparing 68 younger and 39 older adults and using a popular set of film clips to induce tenderness, amusement, anger, fear, sadness and disgust emotions. The direction of subjective emotional patterns was evaluated with self-reports and that of physiological emotional patterns was evaluated with a wearable emotion detection system. The findings suggest a dual-process framework between subjective and physiological responses, manifested differently in young and older adults. In terms of arousal, the older adults exhibited higher levels of subjective arousal in negative emotions and tenderness while young adults showed higher levels of physiological arousal in these emotions. These findings yield information on the multidirectionality of positive and negative emotions, corroborating that emotional changes in the adult lifespan appear to be subject to the relevance of the emotion elicitor to each age group.
Negative stress, also named distress, is nowadays one of the most studied emotional states due to its high impact on advanced societies. Its automatic identification from physiological recordings can ...be extremely useful to prevent concomitant physical health problems as well as other mental disorders. However, this task is still an unresolved challenge. Recently, quadratic sample entropy (QSE) applied to the electroencephalogram signal has proven to be the most promising single metric to discern between emotional states of calm and negative stress. This index estimates repetitive patterns in a time series without considering time data order within each one, thus ignoring some relevant dynamics. Hence, in this work conditional entropy (CEn) and its correction (CCEn) are studied to complement and improve QSE ability in detection of distress. Both CEn and CCEn symbolize original time series to consider ordinal patterns and, thus, quantify accurately data predictability. Results obtained from 279 samples (146 associated with calm and 133 to distress) provide a similar discriminant power, about 65%, both for conditional entropies and QSE. More interestingly, these metrics also reveal the presence of complementary brain dynamics under a emotional state of distress. Thus, CCEn and QSE suggest a synchronization between opposite frontal and parietal brain regions from both hemispheres, such that when the level of negative stress increases, a more irregular activity is found in left frontal and right parietal areas. Simultaneously, more predictable activity is noticed in right frontal and left parietal regions. These findings agree with previous neurophysiological studies and allow to improve the identification of distress. Precisely, a very simple discriminant model based on CCEn and QSE is able to discern more than 80% of samples, thus overcoming slightly the results reported by previous works, where dozens or hundreds of variables have to be combined with advanced classifiers.
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