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descripción no proporcionada por scopus, The authors thank the ERC StG 2012-306826 e-GAMES project, the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), the DGI (Spain) project BE-WELL CTQ2013-40480-R, the Generalitat de Catalunya (2014-SGR-17) and the Spanish Ministry of Economy and Competitiveness, through the ‘Severo Ochoa‘ Programme for Centres of Excellence in R&D (SEV- 2015-0496). F.L. gratefully acknowledges the “Juan de la Cierva” programme. The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the Seventh Framework Programme of the European Union (FP7/2007-2013) under REA grant agreement no.600388 (TECNIOSpring programme), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ. Q. Z. acknowledges the China Scholarship Council, the National Natural Science Foundation (NSF) of China (11404266) and the Fundamental Research Funds for the Central Universities (Grant No. XDJK2011C041). Q. Z. is enrolled in the Materials Science PhD Program of Universitat Autònoma de Barcelona. The authors gratefully acknowledge Prof. J. Puigdollers for the useful discussions

The electronic and structural properties of two tetrathiafulvalene derivatives bearing aromatic benzene rings are reported. Thin film transistors of these materials show p-type characteristics with comparable mobility values. It is found that the rigidification of the molecule is beneficial for reducing the reorganisation energy but also has an unfavorable impact on the electronic structure dimensionality., This work was funded by the ERC StG 2012-306826 e-GAMES project, the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), the DGI (Spain) with project BE-WELL CTQ2013-40480-R and CTQ2015-64618-R, Generalitat de Catalunya 2014-SGR-17, 2014SGR97 and XRQTC and Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496). A. C. is enrolled in the Materials Science PhD program of UAB. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).

α-Methyldithiophene–tetrathiafulvalene (α-mDT-TTF), the first alkyl-substituted thiophene–tetrathiafulvalene electronic donor, and some of its charge-transfer salts were explored. The crystal structure of α-mDT-TTF is composed of molecular stacks aligned parallel to each other. Its cyclic voltammetry shows higher electron-donor ability than the unsubstituted analogue. This material was employed as a semiconductor in an organic field-effect transistor and showed a mobility of 4 × 10–4 cm2 V–1 s–1. Two charge-transfer salts of this donor with [M(mnt)2]– anions (mnt = maleonitriledithiolate), M = Co and Au, were obtained by electrocrystallization; they present unusual stoichiometries: (α-mDT-TTF)[Co(mnt)2] and (α-mDT-TTF)3[Au(mnt)2]2. In the cobalt compound, the donor molecules are fully oxidized and the Co complex is dimerized; it presents semiconducting behavior (7 × 10–3 S cm–1). The gold compound is composed of alternating stacks of donor trimers and pairs of anions.

During the last decades, small molecule organic semiconductors have been successfully used as active layer in organic field-effect transistors (OFETs). Despite the high mobility achieved so far with organic molecules, in order to progress in the field it is crucial to find techniques to process them from solution. The device reproducibility is one of the principal weak points of organic electronics for further commercialization. To achieve a high device-to-device reproducibility it is essential to control the morphology and polymorphism of the active layer for OFET application. In this work, the preparation of thin films is reported based on blends of the organic semiconductor dibenzo-tetrathiafulvalene (DB-TTF) and polystyrene by a solution shearing technique compatible with upscaling. Here, it is demonstrated that varying the deposition parameters (i.e., speed and temperature) or the solution formulation (i.e., semiconductor/binder polymer ratio) is possible to control the film morphology and semiconductor polymorphism and, hence, the different intermolecular interactions. It is demonstrated that the control of the thermodynamics and kinetics of the crystallization process is key for the device performance optimization. Further, this is the first time that DB-TTF thin films of the α-polymorph are reported., This work was mainly funded by the European Research Council (ERC) StG 2012-306826 e-GAMES and ERC PoC 2014-640120 LAB-TECH projects. The authors also thank the Networking Research Center on Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN), the Generalitat de Catalunya (2014-SGR-17) and the Spanish Ministry of Economy and Competitiveness, through the projects BE-WELL CTQ 2013-40480-R and FANCY CTQ2016-80030-R, and through the “Severo Ochoa” Programme for Centers of Excellence in R&D (SEV-2015-0496). F.L. gratefully acknowledges the “Juan de la Cierva” programme.

Large Stokes shift downshifting organolanthanide complex, Eu(tta)(3)phen, is examined for inclusion in polymeric layers to replace the UV blocking layer in dye sensitized solar cell (DSSC) technology. The UV blocking layer increases stability but power conversion efficiency decreases as incident UV photons are not converted into photocurrent. Eu(tta) 3phen doped polymeric film are prepared and attached to DSSC devices following optimized thickness and concentration from a ray-trace numerical model for the specific DSSC. External quantum efficiency is significantly increased in the UV spectral region compared to DSSCs utilizing a passive, non-luminescent, UV-BL. High Eu(tta)(3)phen film transparency in the visible range minimizes DSSC EQE losses at visible wavelengths. Short-circuit current (I-sc) enhancement due to downshifting is demonstrated (similar to 1%) in small-scale DSSC prototypes, where the specific geometry limits the photon collection efficiency and overall enhancement. Model predictions indicate that 2%-3% I-sc enhancement is realizable in flexible single DSSC compared to, non-luminescent, UV-BL. Added to this, in outdoor conditions taking into account diffuse light, the increment in Isc can increase 50% more. Although photostability of the blended LSS-DS polymer films is not sufficient to be useful for medium-long term outdoor PV applications, the results demonstrate that significant efficiency enhancement can be realized. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This work studies the charge carrier collection efficiency in organic bulk-heterojunction solar cells based on polymer:fullerene blends. An equivalent circuit with a specific recombination term is proposed to describe the behavior of this type of devices. It is experimentally shown that this recombination term determines the slope of the current–voltage characteristic at the short-circuit condition. The variation of this dynamic resistance with the light intensity can be interpreted considering a dominant first-order recombination process. Finally, an analytical model under a constant electric field approximation is presented that can be used to calculate the charge carrier collection efficiency of the device. This model can be also used to estimate an effective mobility–lifetime product, which is characteristic of the quality of the active layer.

In the last few years exciting advances have been achieved in developing printing techniques for organic semiconductors, and impressive mobility values have been reported for the resulting organic field-effect transistors (OFETs). However, not all these techniques are scalable and some of them require additional crystallization steps. This study reports on the fabrication of OFETs employing blends of four benchmark organic semiconductors with polystyrene and demonstrates that applying the same formulation and experimental conditions for printing them, highly reproducible and uniform crystalline films exhibiting high OFET performance are successfully achieved. It is noted that the mobility values achieved here are not the highest reported for the studied materials; however, they are state-of-the-art values and could be regarded as exceptional considering the low cost and fast speed of the fabrication process involved here., This work was mainly funded by the ERC StG 2012 306826 e GAMES and ERC PoC 2014 640120 LAB TECH projects. The authors also thank the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER BBN), the DGI (Spain) project BE WELL CTQ2013 40480 R, the Generalitat de Catalunya (2014 SGR 17) and the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV 2015 0496). The authors would like to thank the ICTS "NANBIOSIS", more specifically to the Nanotechnology Platform, unit of CIBER BBN at the Institute for Bioengineering of Catalonia (IBEC) for their assistance in ToF SIMS analyses. I. T. acknowledges FPU fellowship from the Ministery and the Materials Science PhD Program of Universitat Autònoma de Barcelona. F. G. D. P. thanks Universidad Técnica de Ambato and Secretaría de Educación Superior, Ciencia, Tecnología e Innovación for funding through a doctoral scholarship “Convocatoria abierta 2010”.

In electronics, the fi eld-effect transistor (FET) is a crucial cornerstone and successful integration of this semiconductor device into circuit applications requires stable and ideal electrical characteristics over a wide range of temperatures and environments. Solution processing, using printing or coating techniques, has been explored to manufacture organic fi eld-effect transistors (OFET) on fl exible carriers, enabling radically novel electronics applications. Ideal electrical characteristics, in organic materials, are typically only found in single crystals. Tiresome growth and manipulation of these hamper practical production of fl exible OFETs circuits. To date, neither devices nor any circuits, based on solution-processed OFETs, has exhibited an ideal set of characteristics similar or better than today’s FET technology based on amorphous silicon. Here, bar-assisted meniscus shearing of dibenzo-tetrathiafulvalene to coat-process self-organized crystalline organic semiconducting domains with high reproducibility is reported. Including these coatings as the channel in OFETs, electric fi eld and temperature-independent charge carrier mobility and no bias stress effects are observed. Furthermore, record-high gain in OFET inverters and exceptional operational stability in both air and water are measured., The authors thank the ERC StG 2012-306826 e-GAMES project, the Networking Research Center on Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN), the DGI (Spain) project BE-WELL CTQ2013-40480-R, and the Generalitat de Catalunya (2014-SGR- 17). Research in Sweden was fi nancially supported by the Advanced Functional Materials Center at Linköping University, the Önnesjö Foundation, the Knut and Alice Wallenberg Foundation (Power Paper project, scholars), the Swedish Foundation for Strategic Research (SSF, Synergi project). F.G.D.P. thanks Universidad Técnica de Ambato and Secretaría de Educación Superior, Ciencia, Tecnología e Innovación for funding through a doctoral scholarship “Convocatoria abierta 2010.” The authors also thank Witold Tatkiewicz for his help with the ImageJ software.

Organic thin films based on composite materials of semiconducting dibenzo-tetrathiafulvalene (DB-TTF) and insulating styrenic matrices (Polystyrene (PS10k) and Poly-alpha methylstyrene (PAMS10k) ) have been fabricated by the wire-bar coating technique in ambient conditions (air, light, humidity) and contrasted with the ones prepared by thermally evaporating the organic semiconductor. The transistors fabricated with DB-TTF:PS10k composites show a clear fieldeffect behavior with p-type characteristics, exhibiting charge carriers mobilities in the range of 0.01 cm2/Vs, fully comparable with the films obtained by thermal evaporation. However, while the thermally evaporated films show poor stability in air, the wire-bar coated composites films and devices are highly reproducible and exhibit lower threshold voltage values. Thus, we demonstrate the suitability of the wire-bar technique for manufacturing large area devices., The authors thank the ERC StG 2012-306826 e-GAMES project, the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), the DGI (Spain) with project BE-WELL CTQ2013-40480-R, and the Generalitat de Catalunya (2014-SGR-17). F. G. D. P. thanks Universidad Técnica de Ambato and Secretaría de Educación Superior, Ciencia, Tecnología e Innovación for funding through a doctoral scholarship “Convocatoria abierta 2010”.

In this paper we study the density of states in n-type N,N’-ditridecylperylene-3,4,9,10-tetracarboxylic diimide organic semiconductor using two different methods. The first one is based on the temperature dependence of the channel conductance in field-effect transistors. The second one is based on the subgap optical absorption coefficient measured using the Photothermal Deflection Spectroscopy technique. Both techniques allow estimating the distribution of localized states in the band gap of the semiconductor.

The effective mobility-lifetime product, a figure of merit for charge carrier transport in a photovoltaic device, was determined for small-molecule bulk heterojunction organic solar cells by means of a simplified methodology comprising variable light intensity measurements. The recombination losses within the intrinsic active layer, accounted by a recombination current that reduces the generated photocurrent, were correlated to lower mobility-lifetime values that reduce device performance.

In this work, zinc indium tin oxide layers with different compositions are used as the active layer of thin film transistors. This multicomponent transparent conductive oxide is gaining great interest due to its reduced content of the scarce indium element. Experimental data indicate that the incorporation of zinc promotes the creation of oxygen vacancies, which results in a higher free carrier density. In thin-film transistors this effect leads to a higher off current and threshold voltage values. The field-effect mobility is also strongly degraded, probably due to coulomb scattering by ionized defects. A post deposition annealing in air reduces the density of oxygen vacancies and improves the field-effect mobility by orders of magnitude. Finally, the electrical characteristics of the fabricated thin-film transistors have been analyzed to estimate the density of states in the gap of the active layers. These measurements reveal a clear peak located at 0.3 eV from the conduction band edge that could be attributed to oxygen vacancies. (C) 2013 Elsevier B.V. All rights reserved.