Organizational culture, leadership style and effectiveness: A case study of middle eastern construction clients

During the last few decades, organizational effectiveness has received a great deal of attention in many industrial sectors. As a result, a variety of models have been formulated which measure organizational performance. In the construction industry, two factors have subsequently captured the imagination and interest of researchers and practitioners alike: the culture of the organization and the leadership style of project managers. This focus places a requirement upon construction organizations to recognize and understand their organizational culture, and equally, to clearly communicate it to their employees as part of their capitalist drive of constantly improving performance, productivity and profit. Traditional ways of conducting construction business require a sound understanding of the technical and managerial demands of executing projects, which in turn, places an increased emphasis upon the management and leadership competencies of individual project managers. The purpose of the research is to explore the relationship between organizational culture, authentic leadership style and effectiveness within the context of a case study investigation centred on Middle Eastern construction clients and their project managers. The outcomes of the investigation, which include the presentation of an explanatory model, indicate that organizational culture is directly and positively related to performance and effectiveness, while project managers' leadership style has an indirect relationship to effectiveness. A strong organizational culture is therefore deemed critical to organizational performance

Light Emission from Zinc Oxide Nanoforest Plasma

Zinc oxide (ZnO) nanorods were grown through chemical bath deposition tech- nique on different substrates, such as highly p-doped silicon microstructures, low p-doped silicon and silicon dioxide. High voltage (up to 80 V) induced plasma formation is reported with high intensity arcs of characteristic blue light. Easy and reproducible plasma formation is obtained on patterned microstructures of highly doped silicon. Both DC stress and AC stress with variable frequency were applied (up to 10 KHz) as well as short duration pulses (from 1 to 100 μs) to the pads of the silicon microstructures causing excitation of free electrons in the plasma and more atomic transitions to be present compared to the DC case

Überwindung des Effizienzverlustes bei der Skalierung organischer Solarzellen vom Labormaßstab zu Rolle-zu-Rolle gedruckten Modulen

Printed photovoltaics technologies saw in the past years an increasing interest in the scientific and industrial communities due to their unique selling points, such as semitransparency, flexibility, easiness of process and relatively high efficiencies. However, a substantial efficiency gap (up to 40%) is usually reported between hero, lab prepared solar cells and large area, roll-to-roll produced modules. In this work we focus on understanding the losses mechanisms via optical and electrical simulations, developing design rules to increase the performances of printed solar modules. Together with the experimental verification of the findings, we show a successful approach for the design of green formulations to allow the proper microstructure formation of the photoactive layer on large area substrates, yielding no additional losses. Finally entirely solution processed modules employing organic semiconductors are presented. The employment of green formulations, together with processing methods roll-to-roll compatible, ultra-fast laser structuring and a module design minimizing the electrical losses yields high efficient modules, with PCEs up to 90% of the reference devices.Das Interesse von Seitens der Industrie und Wissenschaft in gedruckter Photovoltaik erfuhr in den letzten Jahren bedingt durch attraktive Schlüsseleigenschaften wie Semitransparenz, mechanische Flexibilität, Prozessierbarkeit und hoher Wirkungsgrad einen stetigen Anstieg. Allerdings besteht weiterhin eine hohe Diskrepanz zwischen dem Wirkungsgrad von Bauteilen, die auf Laborskala hergestellt werden (aktive Flächen von wenigen mm2) und Bauteilen, die mit grosser, wirtschaftlich relevanter aktiven Fläche auf Rolle-zu-Rolle gedruckt werden (aktive Flächen von mehreren cm2). Die vorliegende Arbeit erarbeitet zunächst das grundlegende Verständnis von Verlustmechanismen über optische und elektrische Simulationen, um dann Designregeln zur Erhöhung des Wirkungsgrades von gedruckten Solarzellen herauszukristallisieren. Die Kombination von Simulation und Experiment erlaubt einen erfolgreichen Zugang in die Entwicklung umweltfreundlicher Formulierungen ohne negativen Einfluss auf die wichtige Mikrostruktur der photoaktiven Schicht und ohne Einbüßen im Wirkungsgrad. Ein Schlüsselergebnis dieser Arbeit ist die Demonstration von vollständig lösungsprozessierten Solarmodulen basierend auf organischen pi-konjugierten Halbleitern im Rolle-zu-Rolle Maßtab. Neuartige Fortschritte basierend auf umweltfreundlichen Formulierungen, Rolle-zu-Rolle Prozessierung, Laserstrukturierung und einem innovativen Layout von Modulen zur Minimierung von elektrischen Verlusten erlauben eine Erhöhung des Wirkungsgrades von bis auf 90% von Rekordzellen im Labormaßstab

Blue and white light emission from zinc oxide nanoforests

Blue and white light emission is observed when high voltage stress is applied using micrometer-separated tungsten probes across a nanoforest formed of ZnO nanorods. The optical spectrum of the emitted light consistently shows three fine peaks with very high amplitude in the 465–485 nm (blue) range, corresponding to atomic transitions of zinc. Additional peaks with smaller amplitudes in the 330–650 nm range and broad spectrum white light is observed depending on the excitation conditions. The spatial and spectral distribution of the emitted light, with pink–orange regions identifying percolation paths in some cases and high intensity blue and white light with center to edge variations in others, indicate that multiple mechanisms lead to light emission. Under certain conditions, the tungsten probe tips used to make electrical contact with the ZnO structures melt during the excitation, indicating that the local temperature can exceed 3422 °C, which is the melting temperature of tungsten. The distinct and narrow peaks in the optical spectra and the abrupt increase in current at high electric fields suggest that a plasma is formed by application of the electrical bias, giving rise to light emission via atomic transitions in gaseous zinc and oxygen. The broad spectrum, white light emission is possibly due to the free electron transitions in the plasma and blackbody radiation from molten silicon. The white light may also arise from the recombination through multiple defect levels in ZnO or due to the optical excitation from solid ZnO. The electrical measurements performed at different ambient pressures result in light emission with distinguishable differences in the emission properties and I–V curves, which also indicate that the dielectric breakdown of ZnO, sublimation, and plasma formation processes are the underlying mechanisms

High-performance ternary organic solar cells with thick active layer exceeding 11% efficiency

We present a novel ternary organic solar cell with an uncommonly thick active layer (similar to 300 nm), featuring thickness invariant charge carrier recombination and delivering 11% power conversion efficiency (PCE). A ternary blend was used to demonstrate photovoltaicmodules of high technological relevance both on glass and flexible substrates, yielding 8.2% and 6.8% PCE, respectively

Towards photovoltaic windows: scalable fabrication of semitransparent modules based on non-fullerene acceptors via laser-patterning

Semitransparent organic photovoltaics (OPV) possess unique properties that make them highly appealing for their integration into semitransparent architectonic elements such as windows or glazings. In order to provide sufficient transparency, non-opaque electrodes and thin photoactive layers are typically used, thus limiting the light-harvesting capacity. This can be partially overcome by using materials that absorb light mostly in the infrared region. On the other hand, the use of scalable techniques for the fabrication of semitransparent devices is often disregarded. In this work, we combine the blue, low-bandgap polymer PBTZT-stat-BDTT-8 with the near-infrared absorbing non-fullerene acceptor 4TICO, adapting the module fabrication to low-cost manufacturing processes that are compatible with large-scale production. Fully solution-processed semitransparent solar cells over 4.7% performance are prepared from non-chlorinated formulations, in air and using scalable techniques such as blade coating. Our prototypes of semitransparent laser-patterned OPV modules exceed 30% of transparency (measured as human perception transmittance, HPT) and yield efficiencies in the range of 4%, geometrical fill factors surpassing 90% and an active area above 1 cm2. We verify the quality of cell-to-cell interconnection and optimise the geometry of the modules with the help of local optoelectronic imaging techniques. This work highlights the relevance of non-fullerene acceptors with strong absorption in the near-infrared, as they can meet industrial and technical requirements for the upscaling and integration of high-performance semitransparent OPV modules with low production costs.This work was supported by the Spanish Ministerio de Economía y Competitividad (MINECO) under Grant PGC2018-095411-B-I00 and No. SEV-2015-0496 in the framework of the Spanish Severo Ochoa Centre of Excellence and by EURECAT Technological Centre. We acknowledge financial support from European Research Council through project ERC CoG 648901 and H2020 Marie Curie actions through the SEPOMO project (Grant number 722651). E.P.-S.-J. wants to thank Mr Pierluigi Mondelli for his help in the laser patterning experimental setup and Mrs Léa Silvestre for her help manufacturing devices. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe

Flexible organic tandem solar modules: a story of up-scaling

The competition in the field of solar energy between Organic Photovoltaics (OPVs) and several Inorganic Photovoltaic technologies is continuously increasing to reach the ultimate purpose of energy supply from inexpensive and easily manufactured solar cell units. Solution-processed printing techniques on flexible substrates attach a tremendous opportunity to the OPVs for the accomplishment of low-cost and large area applications. Furthermore, tandem architectures came to boost up even more OPVs by increasing the photon-harvesting properties of the device. In this work, we demonstrate the road of realizing flexible organic tandem solar modules constructed by a fully roll-to-roll compatible processing. The modules exhibit an efficiency of 5.4% with geometrical fill factors beyond 80% and minimized interconnection-resistance losses. The processing involves low temperature (<70 degrees C), coating methods compatible with slot die coating and high speed and precision laser patterning

Large area slot-die coated organic solar cells on flexible substrates with non-halogenated solution formulations

The transfer from lab scale to industrial application is one of the challenges for organic photovoltaics. For this, non halogenated formulations are a decisive need for the upscaling process, as are roll-to-toll (R2R) compatible methods. Devices processed with o-xylene using slot-die coating as a sheet-to-sheet technique show a reduced efficiency on a larger scale compared to lab scale solar cells. By using a mixture of high and low volatile solvents which selectively dissolve one component, the film homogeneity and the efficiency is dramatically improved. The slot-die coated active layers for solar cells processed from non-halogenated solvents show device efficiencies above 3% on flexible substrates. (C) 2014 Elsevier B.V. All rights reserved

Tailoring green formulation : printing and upscaling of inverted organic solar cells

By tailoring the solvents of active organic solar cell layers regarding their solubility (Hansen parameters), non-halogenated solvents and solvent mixtures can be used to print the active layers of organic solar cells. Similar efficiencies to other typical laboratory methods as spin-coating can be reached. Furthermore, using sheet-to-sheet printing or coating techniques compatible to mass-manufacturing and structuring by laser ablation, we can upscale to 10x20 cm(2) and manufacture modules on plastic substrates. This is a breakthrough for organic solar cells and the next important step on the way to utilize organic solar cells for industrial manufacturing