Plasmonic light trapping leads to responsivity increase in colloidal quantum dot photodetectors

We report broadband responsivity enhancement in PbS colloidal quantum dot (CQDs) photoconductive photodetectors due to absorption increase offered by a plasmonic scattering layer of Ag metal nanoparticles. Responsivity enhancements are observed in the near infrared with a maximum 2.4-fold increase near the absorption band edge of 1 lm for 400 nm thick devices. Additionally, we study the effect of the mode structure on the efficiency of light trapping provided by random nanoparticle scattering in CQD films and provide insights for plasmonic scattering enhancement in CQD thin films.This research has been partially supported by Fundacio´ Privada Cellex Barcelona. We also acknowledge support from European Commission’s Seventh Framework Programme for Research under contract PIRG06-GA-2009-256355

Design optimization of storage facilities taking into account the domino effect

Storing hazardous substances is a process that entrails high risk, and in which many resources are spent in the planning of safety measures; however, safety could be included at the initial stages of the design of this type of installations, by optimizing the number of tanks that are used to store the substance. The effects and consequences of major accidents are directly proportional to the mass of materials involved in them; therefore, if the mass was divided in more containing units, the consequences at the moment of an accident occurrence would be lesser. However, as more units are used to store a dangerous substance in an installation, the risk of domino effect occurrence at the moment of an accident also increases. The objective of this paper is to develop a methodology that allows finding the optimum number of units that have to be used to store dangerous materials, taking the possibility of domino effect occurrence into account. The proposed methodology is described and applied to a case study as a decision making tool, obtaining results that demonstrate that the design of storage installations can be improved from a risk point of view, by combining quantitative risk analysis and optimization techniques.Postprint (published version

Solution-Processed, Solid-State Solar Cells based on Environmentally Friendly AgBiS2 Nanocrystals

Solution-processed inorganic solar cells are a promising low-cost alternative to firstgeneration solar cells.1,2 Solution processing at low temperatures and the use of nontoxic and abundant elements can help minimize cost and facilitate regulatory acceptance. However, until now there has been no material that exhibits all of these features while demonstrating promising efficiencies. Many of the most promising solution-processed inorganic solar cells contain toxic elements such as lead or cadmium (perovskites,2,3 PbS,4 CdTe,5,6 CdS(Se)7,8) or scarce elements like tellurium or indium (CdTe, CIGS(Se)/CIS9,10). Others require high-temperature processes such as selenization or sintering or rely on vacuum deposition techniques ((Sb2S(Se)3,11–13 SnS,14,15 CZTS(Se)16). Here, we present AgBiS2 nanocrystals as a novel nontoxic,17 earth-abundant18 material for highperformance, solution-processed solar cells fabricated in ambient conditions at low temperatures (≤100°C). The AgBiS2 nanocrystals have favorable properties for solar-cell applications including a near-ideal bandgap and strong, broad absorption. We demonstrate a Newport certified power conversion efficiency of 6.3% with no hysteresis and a remarkably high short-circuit current density of about 22 mA·cm-2 for an active layer thickness of only ~35 nm.Peer ReviewedPostprint (author's final draft

Multi-objective optimization of hazardous substance storage facilities. The decision between risks and costs associated to the project

The design storage installations for dangerous substances can be optimized from a safety and risk point of view by combining quantitative risk analysis and mathematical optimization techniques; the consequences of accidents are directly proportional to the mass involved in them, which means that in a storage installation, if the totality of the stored substance is divided into more tanks, the consequences when an accident occurs in any of the units will be less significant than if all the mass was stored in one tank (in installations where there is low possibility of domino effect occurrence). However, as more tanks are used to store the mass, the economical investment will also increase; then, a situation arises between two conflicting objectives, that can be solved through the use of multi objective optimization.Postprint (published version

Literatura de la migración en España (2001-2008): negociación de las expectativas a través del Bildungsroman

Esta tesis examina la emergencia de la literatura de la migración del primer periodo entre 2001 y 2008 en España y estudia los textos de cuatro escritores "migrantes" como lugares de negociación de las expectativas sociales, culturales y literarias sobre la inmigración tomando como apoyo las pautas temáticas y formales del Bildungsroman. En concreto, analizaremos las novelas "Calella sen saída" de Víctor Omgbá, "Lejos del horizonte perfumado" de Salah Jamal, "Límites y fronteras" de Saïd El Kadaoui y "L'últim patriarca" de Najat El Hachmi. El objetivo es caracterizar la literatura de la migración en España en sus modalidades catalana, gallega y castellana poniéndolas en relación con sus precedentes en otras literaturas del entorno

Charge photogeneration and transport in AgBis2 nanocrystal films for photovoltaics

Solution-processed AgBiS2 nanocrystal films are a promising material for nontoxic, earth-abundant solar cells. While solar cells with good device efficiency are demonstrated, so far, hardly anything is known about charge generation, transport, and recombination processes in these films. Here, a photoinduced time-resolved microwave conductivity study on AgBiS2 nanocrystal films is presented. By modeling the experimental data with density-dependent recombination processes, the product of the temperature-dependent electron and hole quantum yield and mobility, and the electron and hole recombination kinetics are determined

Electrical effects of metal nanoparticles embedded in ultra-thin colloidal quantum dot films

Plasmonic light trapping can increase the absorption of light in thin semiconductor films. We investigate the effect of embedded metal nanoparticle (MNP) arrays on the electrical characteristics of ultra-thin PbS colloidal quantum dot (CQD) photoconductors. We demonstrate that direct contact with the metalnanoparticles can suppress or enhance the photocurrent depending on the work function of the metal, which dominates the optical effects of the particles for ultra-thin films. These results have implications for designing plasmonic CQD optoelectronic devices.This research has been supported by Fundacio0 Privada Cellex Barcelona and the European Commission’s Seventh Framework Programme for Research under contract PIRG06-GA-2009-256355 and the Ministerio de Ciencia e Innovacion under Contract No. TEC2011-24744

Determination of carrier lifetime and mobility in colloidal quantum dot films via impedance spectroscopy

Impedance Spectroscopy (IS) proves to be a powerful tool for the determination of carrier lifetime and majority carrier mobility in colloidal quantum dot films. We employ IS to determine the carrier lifetime in PbS quantum dot Schottky solar cells with Al and we verify the validity of the technique via transient photovoltage. We also present a simple approach based on an RC model that allows the determination of carrier mobility in PbS quantum dot films and we corroborate the results via comparison with space charge limited measurements. In summary, we demonstrate the potential of IS to characterize key-to-photovoltaics optoelectronic properties, carrier lifetime, and mobility, in a facile way

Networks of action situations in point-source pollution : the case of winery wastewater in Aragon, Spain

Unidad de excelencia María de Maeztu CEX2019-000940-MIn this article, we offer an analysis of point-source water pollution governance in the European agri-food sector. Specifically, we tackle the case study of the wine industry in Aragon (Spain) through the lenses of the networks of action situations approach. We unveil key strategic decisions of wine producers in relation to compliance with water discharge regulations and explore the feasibility and effectiveness of potential solutions. According to our quantitative and qualitative analyses, the problem of peak load discharges in the sector can be explained by the strategic behavior of wine producers in the context of enforcement deficits, as well as by particularities of the wine production process, and controversies around the construction and management of public treatment plants. Coordination among wine producers and public treatment plant managers to invest in in-house treatment infrastructure or to smooth discharges out so they fit the capacity of treatment plants would be a promising solution; however, economic incentives and tightened enforcement of discharge regulations would also be necessary

Plasmonic light trapping leads to responsivity increase in colloidal quantum dot photodetectors

We report broadband responsivity enhancement in PbScolloidalquantum dot (CQDs) photoconductive photodetectors due to absorption increase offered by a plasmonicscattering layer of Ag metal nanoparticles. Responsivity enhancements are observed in the near infrared with a maximum 2.4-fold increase near the absorption band edge of ∼1 μm for ∼400 nm thick devices. Additionally, we study the effect of the mode structure on the efficiency of light trapping provided by random nanoparticlescattering in CQD films and provide insights for plasmonicscattering enhancement in CQD thin films