1,353 research outputs found

    Containership Flag Selection: The Opening of Direct Shipping between Taiwan and China

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    The signature of the cross-strait sea transport (CST) Agreement in 2008 has not only established the cross-strait direct shipping link, but also lifted the ban on the involvement of Taiwanese flagged ships to call at China’s ports. This paper focuses on the flag selection for Taiwanese container shipping companies under the provisions of the CST Agreement, and embraces the empirical investigation based on the Analytic Hierarchy Process (AHP) and Grey Relation Analysis (GRA) with the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). The results show Hong Kong is the optimal choice rather than China and Taiwan. Although cross-strait shipping is highly controlled by both sides of the strait, economic factors are still taken seriously in commercial activities. Further, to assist shipping companies to get direct shipping approvals from China and revising a package of financial measures under current shipping policies are recommended for the Taiwanese government

    Parylene-strengthened thermal isolation technology for microfluidic system-on-chip applications

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    Here we reported a novel technology using parylene-cross-linking structure to achieve on-chip air-gap thermal isolation for microfluidic system-on-chip (SOC) applications. Two applications based on this technology, on-chip continuous-flow polymerase chain reaction (PCR) and on-chip temperature gradient liquid chromatography (LC) were successfully demonstrated. Device thermal performance in each example was characterized. Results showed that our technology not only provides excellent on-chip thermal isolation but also its simplicity of integration with other on-chip components makes versatile microfluidic SOC applications feasible

    Lateral charge carrier transport in Cu(In,Ga)Se2 studied by time-resolved photoluminescence mapping

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    Electronic transport in a semiconductor is key for the development of more efficient devices. In particular, the electronic transport parameters carrier lifetime and mobility are of paramount importance for the modeling, characterization, and development of new designs for solar cells and optoelectronic devices. Herein, time-resolved photoluminescence mapping under low injection and wide-field illumination conditions is used to measure the carrier lifetime and analyze the lateral charge carrier transport in Cu(In,Ga)Se2 absorbers grown at different temperatures, on different substrates, and subject to different postdeposition treatments (PDT) with light or heavy alkalis. To estimate the carrier mobility, numerical simulations of carrier diffusion transport to areas of increased recombination (defects) are used, similarly as observed experimentally. Mobilities are found in the range of 10–50 cm2 V−1 s−1, and effective minority carrier lifetime between 100 and 800 ns resulting in carrier diffusion lengths of 2–9 μm depending on the sample. Finally, the factors limiting carrier mobility and the implications of carrier diffusion on the measured carrier lifetimes are discussed.This work received financial support partially from the Swiss State Secretary for Education, Research and Innovation (SERI) under contract number 17.00105 (EMPIR project HyMet) and from the Swiss Federal Office of Energy (SFOE) (SI/501614-01 ‘‘ImproCIS’’). The EMPIR program was cofinanced by the Participating States and by the European Union's Horizon 2020 research and innovation program

    Charge carrier lifetime fluctuations and performance evaluation of Cu(In,Ga)Se2 absorbers via time-resolved-photoluminescence microscopy

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    The open-circuit voltage (VOC) is the main limitation to higher efficiencies of Cu(In,Ga)Se2 solar cells. One of the most critical parameters directly affecting VOC is the charge carrier lifetime. Therefore, it is essential to evaluate the extent to which inhomogeneities in material properties limit the carrier lifetime and how postdeposition treatments (PDTs) and growth conditions affect material properties. Time-resolved photoluminescence (TRPL) microscopy is employed at conditions similar to one sun to study carrier lifetime fluctuations in Cu(In,Ga)Se2 with light (Na) and heavy (Rb) alkalis, different substrates, and grown at different temperatures. PDT lowers the amplitude of minority carrier lifetime fluctuations, especially for Rb-treated samples. Upon PDT, the grains’ carrier lifetime increases, and the analysis suggests a reduction in grain boundary recombination. Furthermore, lifetime fluctuations have a small impact on device performance, whereas VOC calculated from TRPL (and continuous-wave PL) agrees with device values within the limits of investigated PDT samples. Finally, up to about half a per cent external radiative efficiencies are experimentally determined from TRPL metrics, and internal radiative efficiencies are approximated. The findings demonstrate that the highest absorber material quality investigated is still limited by nonradiative recombination (grain or grain boundary) and is comparable to state-of-the-art absorbers.This work received financial support in part from the Swiss State Secretary for Education, Research and Innovation (SERI) under Contract No. 17.00105 (EMPIR project HyMet) and from the Swiss Federal Office of Energy (SFOE) (SI/501614-01 ‘‘ImproCIS''). The EMPIR programme was cofinanced by the Participating States and by the European Union's Horizon 2020 research and innovation programme

    Trickle-Down Technology and Screening of a Durable Goods Monopolist

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    We show that when it takes time for a durable goods monopolist to make its high-end new technology accessible to low-end market (the trickle-down technology constraint), the monopolist's high-end product might have a higher-than-optimum quality. This result differs from conventional screening models, in which the qualities of non-durable goods supplied by a monopolist never exceed the optimum, and only consumers with the highest valuation consume the efficient quality. In another literature discussing a durable goods monopolist who delays the introduction of low-end product as a marketing strategy, but not due to the trickle-down constraint, the qualities will not exceed the optimum either. Our results show that the trickle-down constraint will make the monopolist chooses a higher-than-optimum quality when the difference of the valuations of high demand and low demand consumers are in certain ranges. The intuition follows Spence (1975): the efficient quality is determined by the marginal cost and the average of all consumers' marginal valuations, while the monopolist chooses quality such that the marginal cost equals the marginal consumer's marginal valuation

    Triple-cation perovskite solar cells fabricated by hybrid PVD/blade coating process using green solvents

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    The scalability of highly efficient organic-inorganic perovskite solar cells (PSCs) is one of the remaining challenges of solar module manufacturing. Various scalable methods have been explored to strive for uniform perovskite films of high crystal quality on large-area substrates. However, each of these methods have individual drawbacks, limiting the successful commercialization of perovskite photovoltaics. Here, we report a fully scalable hybrid process, which combines vapor- and solution-based techniques to deposit high quality uniform perovskite films on large-area substrates. This two-step process does not use toxic solvents, and it further allows facile implementation of passivation strategies and additives. We fabricated PSCs based on this process and used blade coating to deposit both charge transporting layers (SnO2 and Spiro-OMeTAD) without hazardous solvents in ambient air. The fabricated PSCs have yielded open-circuit voltage up to 1.16 V and power conversion efficiency of 18.7 % with good uniformity on 5 cm x 5 cm substrates

    Parylene-strengthened thermal isolation technology for microfluidic system-on-chip applications

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    Here we reported a novel technology using parylene-cross-linking structure to achieve on-chip air-gap thermal isolation for microfluidic system-on-chip (SOC) applications. Two applications based on this technology, on-chip continuous-flow polymerase chain reaction (PCR) and on-chip temperature gradient liquid chromatography (LC) were successfully demonstrated. Device thermal performance in each example was characterized. Results showed that our technology not only provides excellent on-chip thermal isolation but also its simplicity of integration with other on-chip components makes versatile microfluidic SOC applications feasible

    Influence of Ga back grading on voltage loss in low-temperature co-evaporated Cu(In,Ga)Se2 thin film solar cells

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    The performance of Cu(In,Ga)Se2 (CIGS) solar cells is limited by the presence of the highly recombinative CIGS/Mo interface. The recombination at the CIGS/Mo interface is influential for the open circuit voltage (VOC) in high quality CIGS absorbers with increased charge carriers diffusion length. A quantitative understanding of the role of the Ga back grading height (ΔGGI) in suppressing back interface recombination is needed. In this work, we take advantage of a low temperature process to modify the ΔGGI while keeping the composition in the notch and front regions almost unchanged. Improvement in both VOC deficit and time-resolved photoluminescence lifetime are observed with increasing ΔGGI. With a combination of back surface modification experiments and numerical simulations, we quantify a voltage loss in ungraded devices of approximately 100 mV solely from the back interface recombination. Nice agreement between simulation and experimental data is reached while constraining the values of possible diffusion lengths. Our results suggest that a ΔGGI of about 0.50 is required to effectively suppress the back interface recombination, highlighting the importance of grading control in high-performance CIGS solar cells and devices.Bundesamt für Energie, Grant/Award Number: SI/501614-01; Horizon 2020 Framework Programme, Grant/Award Number: EMPIR project HyMet; Swiss State Secretary for Education, Research and Innovation (SERI), Grant/Award Number: 17.00105 (EMPIR project HyMet
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