130,467 research outputs found
CIGS thin films prepared by sputtering and selenization by using In2Se3, Ga2Se3 and Cu as sputtering targets
No full textCuInGaSe2/CdS thin film solar cells were prepared by using a novel precursor obtained by depositing in sequence, on top of a Mo covered soda lime glass, In2Se3, Ga2Se3 and Cu. A subsequent few minutes selenization of the precursor in a selenium vapor is sufficient to obtain a good quality CuInGaSe2 film
High efficiency Cu(In,Ga)Se2/CdS thin film solar cells obtained with precursors sputtered from InSe, GaSe and Cu targets
No full text16.2% efficient Cu(In,Ga)Se2/CdS solar cells were prepared with a process which uses only sputtering and selenization. InSe, GaSe and Cu sputtering targets were used for the preparation of precursors. Selenization was done in a vacuum chamber in which pure Se is evaporated from a graphite crucible. CdS was deposited by sputtering in an atmosphere of Ar containing 3% of CHF3. The process is highly reproducible and it is easily scalable to much larger area substrates
Effects of Ultra-Thin Copper Layer on the Performance and Stability of CdTe/CdS Solar Cells
No full textCdTe solar cells have shown high efficiency well above 20%. Despite different copper-free back contacts have been successfully introduced this is still required for very high efficiency devices. On the other hand an excessive amount of copper results in degradation of the device and a suitable concentration is very important for a good trade off between conversion efficiency and stability. A study on how the amount of copper at the back contact affects the performances and the stability of CdTe thin film solar cells is presented. CdTe cells with 0.1 nm Cu layer are compared to devices with 2 nm Cu and the electrical properties are measured. The formation of Cu-Te compounds has been analysed and degradation of cells made with thick and thin Cu layer has been recorded. With different copper thicknesses, different approaches are needed for high efficiencies; moreover devices degrade with different mechanisms
Manufacturing of CdTe thin film photovoltaic modules
No full textAbstract:
The technology to fabricate CdTe/CdS thin film solar cells can be considered mature for a large-scale production of CdTe-based modules. Several reasons contribute to demonstrate this assertion: a stable efficiency of 16.5% has been demonstrated for 1 cm2 laboratory cell and it is expected that an efficiency of 12% can be obtained for 0.6 × 1.2 m2 modules; low cost soda lime float glass can be used as a substrate; the amount of source material is at least 100 times less than that used for single crystal modules and is a negligible part of the overall cost. The fabrication process can be completely automated and a production yield of one module every 2 min can be obtained, which implies a production cost substantially less than 1€/WP. A further cost reduction will render this kind of energy production competitive with the energy obtained from fossil fuels by approaching the so-called grid-parity. Some new companies have recently announced the start of production or plan to do so in the near future. Many of these plants are located in Germany, some in the USA. In Italy, a new company has been constituted in 2008, with the aim of building a factory with a capacity of 18 MW/year. In this article, we will describe and compare the basic principles of CdTe solar cells and modules. We will include an overview of the potentials of these technologies and of the R&D issues under investigation. This paper describes how the large-area mass production of CdTe solar modules is realized in the Italian factory and presents a worldwide overview of the current production activities
Review: The second-generation of CdTe and CuInGaSe2 thin filmPV modules
No full textThe state of the art of the second-generation of solar cells based on the CdTe and CuInGaSe2 thin film
technology will be described. This type of cells reached, on laboratory scale, photovoltaic conversion
efficiencies respectively of 16.5% and 20.3% very close to those obtained with bulk materials. In particular,
the materials, the layer sequences and deposition techniques used for the preparation of these two absorbers
are described. Particular emphasis will be placed on major innovations that have enabled us to achieve high
efficiencies with polycrystalline materials, showing how thin-film technology is mature enough to be
transferred to industrial production. Finally, we will discuss about a project of technology-transfer developed
at Parma University for the production of photovoltaic modules at an industrial level. In the near future, with
our process, Arendi S.p.A. will reach a productivity of 18 MW/year
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Improvement in Processing CdTe/CdS Thin Film Solar Cells
No full textIn order to decrease the thickness of the close-spaced sublimation (CSS) deposited CdTe film, a novelapproach has been used. On top of the CSS-deposited CdTe film, whose thickness was reduced from 6-8 μm to3-4 μm, another CdTe layer was deposited by RF sputtering, with a thickness of 100-200 nm. The purpose of thisapproach was that of filling up the voids, which form when a low thickness CdTe film is deposited by CSS.Surprisingly we observed that solar cells prepared with this CdTe bi-layer exhibit efficiencies higher than 14%. Sincethe sputtered CdTe layer is n-type, while the CSS-deposited one is p-type, we thought to explain these results bysupposing the formation of local p-n junctions at the grain boundaries, which repel the minority carriers in the grains,increasing their lifetime. This approach permitted to reduce the thickness of CdTe films without affecting the cellefficiency. A further improvement in processing CdTe/CdS solar cells has been obtained by making the CdTetreatment in presence of Chlorine with the use of Ar containing 4% HCl mixed with a gas containing Fluorine, suchas CHF3 or C2H2F4
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
CuInGaSe2/CdS thin film solar cells made with new precursors prepared by sputtering
No full textCuInGaSe2/CdS thin film solar cells have been prepared by using only sputtering and selenization in a Se vapour. First of all, a precursor for the formation of a thin film of CuInSe2 is prepared on a one inch square soda-lime glass by sputtering in sequence Mo, In2Se3 and Cu. The staked layers are annealed at 400°C for half an hour and then selenized at 530°C for 10 minutes. In this way, a uniform CuInSe2 film is obtained. In order to get a CuInGaSe2 film, an alloy of Cu-Ga is deposited by sputtering on top of CuInSe2 and the stacked CuInSe2/Cu-Ga is selenized at 530°C for 10 minutes. Solar cells are prepared by depositing in sequence CdS, intrinsic ZnO and Al-doped ZnO. 14% uniform efficiencies on 1 inch square area are easily obtained. Since this process uses only sputtering and selenization techniques, it is suitable to be scaled-up to large area production
- …
