Improved prediction of the optical properties in pi-conjugated polymers: the case of benzochalcogenodiazole-based copolymers with different heteroatom substitution

Donor−acceptor (D−A) approach to conjugated polymer design has become a widely used method for preparing conjugated polymers with narrow band gaps.1 One outstanding D−A polymer is poly(cyclopentadithiophene)benzothiadiazole, PCPDTBT (P1 in Figure 1), for which power conversion efficiencies in solar cells of 4.5-5.5% are reported.2 In this work, we use resonance Raman (RR) and density functional theory (DFT) calculations to investigate the tuning of the electronic and structural properties of cyclopentadithiophene-benzochalcogenodiazole D−A polymers, wherein a single atom in the benzochalcogenodiazole unit is varied from sulfur to selenium to tellurium (Fig. 1).3 Sophisticated DFT calculations have been carried out using long-range corrected functionals, considering both tuned and default range-separation parameters, aiming at predicting their optical and charge transport properties. In addition, the nature of the electronic excitation is described by analyzing the enhancement pattern in the RR spectra using Raman excitation wavelengths coincident with the various transitions in the copolymers.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Modelling the optical properties of Benzochalcogenodiazole-based Copolymers using Tuned Range-Separated Hybrid Functionals

Since the discovery of organic semiconductors, these systems have been deeply investigated and many strategies to module their optical and electronic properties have been established. In this sense, Donor-acceptor (D−A) approach to conjugated polymer design has become a widely used method for preparing conjugated polymers with narrow band gaps. This approach involves synthesizing a polymer with a delocalized π-electron system that comprises alternating electron-rich (donor) and electron-deficient (acceptor) repeat units. The combination of high-lying HOMO levels (residing on the donor units) and low-lying LUMO levels (residing on the acceptor units) results in an overall narrow band gap for the polymer. In this sense, poly(cyclopentadithiophene)benzothiadiazole is a D−A polymer for which power conversion efficiencies in solar cells of 5 6 % are reported. In this work, we use density functional theory (DFT) calculations to investigate the tuning of the electronic and structural properties of cyclopentadithiophene ben zochalcogenodiazole D−A polymers, wherein a single atom in the benzochalcogenodiazole unit is varied from sulfur to selenium to tellurium. Resonance Raman (RR) spectroscopy is also used to describe the nature of the electronic excitations. Improved prediction of the optical properties h as been obtained by using long range corrected functionals functionals, considering both tuned and default range separation parameters, aiming at predicting their optical and charge transport properties.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

GEODIVULGAR: Geología y Sociedad

Fac. de Ciencias GeológicasFALSEsubmitte

EDOT-Based Copolymers with Pendant Anthraquinone Units: Analysis of Their Optoelectronic Properties within the Double-Cable Context

Here we present the synthesis and optical and structural characterization of a new series of alternating donor–acceptor copolymers based on 3,4-ethylenedioxythiophene (EDOT). The donor consists of phenylene, alkylated fluorene, or diethynyl-1,4-phenylene as the aryl units copolymerized with the EDOT group with and without a 9,10-anthraquinone (AQ) side chain as the acceptor group, namely, as <b>PEX</b>-<b>AQ</b> and <b>PEX</b>, respectively. The changes in the electronic absorption/emission spectra and redox properties are analyzed in detail as a function of (i) the composition of the copolymers and (ii) the inclusion of the pendant 9,10-anthraquinone. Density functional theory calculations are used to interpret the experimental results. Special emphasis is placed on the flexibility of the phenylene-based copolymer spine which favors the tendency toward aggregation and confers interesting solvathocromic, thermochromic, and sonochromic properties when applying external stimuli. This is explained by means of an order–disorder conformational transformation (driven by π–π stacking) in solution upon ultrasonication, temperature changes, and the nature of the solvents. A comparison of the transient triplet–triplet absorption spectra of the phenylene-based <b>PEB</b> copolymer in the unaggregated and aggregated forms reveals the formation of accessible triplet excited states whose nature is discussed in connection with the molecular flexibility of the copolymer backbone. These studies highlight the relevance of the precise control of the polymer architecture (donor–acceptor strategy in <b>PEX</b> versus double-cable concept in <b>PEX</b>-<b>AQ</b>) for suitable tunability of the optical and electronic properties of processable conjugated polymers for organic electronics

Memorias del I Congreso Internacional de Bioingeniería y Sistemas Inteligentes de Rehabilitación - CIBSIR 2017

El I Congreso Internacional de Bioingeniería y Sistemas Inteligentes de Rehabilitación, se celebró en Quito, capital del Ecuador. Su organización estuvo a cargo de profesores e investigadores de la Escuela Politécnica Nacional (EPN), Universidad Politécnica Salesiana (UPS), Universitat Politécnica de Valencia (UPV), Universidad Técnica del Norte (UTN), Escuela Superior Politécnica del Chimborazo (ESPOCH), Universidad de las Fuerzas Armadas (ESPE), Universidad Central del Ecuador (UCE), Escuela Superior Politécnica del Litoral (ESPOL), Universidad San Francisco de Quito (USFQ), Universidad de Las Américas (UDLA) y Universidad Mariana de Colombia. Todas ellas universidades que han trabajado de manera rigurosa para la creación de un programa académico que sirva de marco para la investigación y el intercambio de conocimientos y experiencias, así como para el desarrollo de oportunidades de colaboración para promover la difusión de tecnologías relacionadas con estos campos. Este congreso fue dirigido tanto a académicos como a profesionales y estudiantes interesados en compartir conocimientos y experiencias en las áreas de Bioingeniería y Sistemas Inteligentes de Rehabilitación. En la actualidad, el creciente avance tecnológico dedicado a los campos de la Bioingeniería y Sistemas de Rehabilitación, hace necesaria la disponibilidad de un espacio de difusión para las investigaciones que se han desarrollado en instituciones de educación superior e investigación dedicadas a estos trabajos

GEODIVULGAR: Geología y Sociedad

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasFALSEsubmitte

Geodivulgar: Geología y Sociedad

Depto. de Geodinámica, Estratigrafía y PaleontologíaDepto. de Química InorgánicaDepto. de Didáctica de las Ciencias Experimentales , Sociales y MatemáticasFac. de Ciencias GeológicasFac. de Ciencias QuímicasFac. de EducaciónFALSEsubmitte

The genomic history of the Iberian Peninsula over the past 8000 years

We assembled genome-wide data from 271 ancient Iberians, of whom 176 are from the largely unsampled period after 2000 BCE, thereby providing a high-resolution time transect of the Iberian Peninsula. We document high genetic substructure between northwestern and southeastern hunter-gatherers before the spread of farming. We reveal sporadic contacts between Iberia and North Africa by ~2500 BCE and, by ~2000 BCE, the replacement of 40% of Iberia’s ancestry and nearly 100% of its Y-chromosomes by people with Steppe ancestry. We show that, in the Iron Age, Steppe ancestry had spread not only into Indo-European–speaking regions but also into non-Indo-European–speaking ones, and we reveal that present-day Basques are best described as a typical Iron Age population without the admixture events that later affected the rest of Iberia. Additionally, we document how, beginning at least in the Roman period, the ancestry of the peninsula was transformed by gene flow from North Africa and the eastern Mediterranean.J.M.F., F.J.L.-C., J.I.M., F.X.O., J.D., and M.S.B. were supported by HAR2017-86509-P, HAR2017-87695-P, and SGR2017-11 from the Generalitat de Catalunya, AGAUR agency. C.L.-F. was supported by Obra Social La Caixa and by FEDER-MINECO (BFU2015- 64699-P). L.B.d.L.E. was supported by REDISCO-HAR2017-88035-P (Plan Nacional I+D+I, MINECO). C.L., P.R., and C.Bl. were supported by MINECO (HAR2016-77600-P). A.Esp., J.V.-V., G.D., and D.C.S.-G. were supported by MINECO (HAR2009-10105 and HAR2013-43851-P). D.J.K. and B.J.C. were supported by NSF BCS-1460367. K.T.L., A.W., and J.M. were supported by NSF BCS-1153568. J.F.-E. and J.A.M.-A. were supported by IT622-13 Gobierno Vasco, Diputación Foral de Álava, and Diputación Foral de Gipuzkoa. We acknowledge support from the Portuguese Foundation for Science and Technology (PTDC/EPH-ARQ/4164/2014) and the FEDER-COMPETE 2020 project 016899. P.S. was supported by the FCT Investigator Program (IF/01641/2013), FCT IP, and ERDF (COMPETE2020 – POCI). M.Si. and K.D. were supported by a Leverhulme Trust Doctoral Scholarship awarded to M.B.R. and M.P. D.R. was supported by an Allen Discovery Center grant from the Paul Allen Foundation, NIH grant GM100233, and the Howard Hughes Medical Institute. V.V.-M. and W.H. were supported by the Max Planck Society