1,720,981 research outputs found
Tailoring CZTSSe Solar Cell Performance: Comparison of Flexible Molybdenum Foil and Sputtered Molybdenum Back Contacts
No full textFlexible CZTSSe (CuZnSn(S,Se)) solar cells on flexible molybdenum foil (MF) substrates are showing promise for being a candidate for the next-generation large-area and lightweight solar technologies. However, the nature of the back contact continues to be a decisive factor influencing absorber morphology, crystallinity, and the ultimate final device performance. In this work, we provide a comprehensive analysis and comparison of a variety of back contact configurations of flexible and rigid Mo substrates. We analyze four configurations in detail: MF, sputtered Mocoated MF, 10 nm NaF-coated MF, and MoOx-interlayered MF. We compare these with standard rigid devices on sputtered Mo on soda-lime glass (SLG) substrates.The work examines the impact of each back contact on the CZTSSe absorber growth behavior based on grain size, grain distribution, and defect passivation. Furthermore, solar devices are also prepared and examined to find the impact of back contact engineering on the main performance characteristics
Photoconductivity of tellurium-poly(methyl methacrylate) in the ultraviolet–visible-near infrared range
No full textFine powders composed of tellurium grains of average size<10 nm were produced by dry vibration milling
combined with liquid-phase sedimentation techniques, starting from polycrystalline powders with average grain diameter of ca. 30 μm. Nanocomposite films were obtained by binding the nanosized tellurium grains with poly (methyl methacrylate). Raman spectroscopy revealed that the films were based on the coexistence of tellurium and tellurium oxide crystalline phases due to a partial oxidation in air of the grains. The optical measurements of the fabricated material showed that the absorbance was nearly constant in the 310–2200 nm range and that a typical UV absorption peak of the nanostructured tellurium was centered at around 260 nm. An extensive characterization of the photoconductivity properties was carried out by illuminating the tellurium-poly(methyl methacrylate) films with white light or radiations of different spectral composition selected from the UV–Vis-NIR region. Data analysis has allowed to demonstrate that the photoresponse is closely related to the optical absorption and is independent of the spectral composition of the incident radiation in the wavelength range from 310 to 2200 nm, while the photocurrent increases linearly as a function of the optical power density over about three orders of magnitude
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
How the selenium is affecting the physical and electrical properties of ultra-thin CdSeTe/CdTe solar cells
Full text linkThe incorporation of selenium into the CdTe has recently enhanced the performance of the solar cells to 23.1 %. The narrower band gap of the CdSeTe/CdTe absorber boosts the short-circuit current density; also, Se introduction increases the carrier's lifetime. Optimizing CdSexTe1-x band-grading is crucial for achieving highperformance CdTe photovoltaics. Another current goal is to reduce the thickness of the absorber to further reduce production costs and environmental impact. Thus, studying the effects of Se introduction in ultra-thin CdTe absorbers is essential. To investigate Se concentration's impact on ultra-thin CdTe, we fabricated CdSeTe/CdTe devices with an absorber thickness of 0.8 mu m by depositing different CdSe/CdTe ratios. Our 0.8 mu m thick cells have currently achieved an efficiency of 12.8 %, but most important this study shows that Se introduction in ultra-thin CdTe results in structural properties different from those of thicker absorbers, impacting the device performance
In-depth photoluminescence spectra of pure CIGS thin films
No full textPhotoluminescence spectra of pure CIGS thin films with different Ga in-depth gradients are systematically
investigated. Pure Na-free films are prepared with an innovative hybrid deposition technique, whose optical
luminescence emission is analyzed as a function of the depth and is correlated to the radiative intrinsic defects
of the material. Finally, the highlighted features are correlated with the performances of test solar cells prepared
with the same growths
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