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- Bertoni, M. I., 1967-, et al.
(author)
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Nanoprobe X-ray fluorescence characterization of defects in large-area solar cells
- 2011
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In: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 4, s. 4252-4257
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Journal article (peer-reviewed)abstract
- The performance of centimeter-sized energy devices is regulated by inhomogeneously distributednanoscale defects. To improve device efficiency and reduce cost, accurate characterization of thesenanoscale defects is necessary. However, the multiscale nature of this problem presentsa characterization challenge, as non-destructive techniques often specialize in a single decade of lengthscales, and have difficulty probing non-destructively beneath the surface of materials with sub-micronspatial resolution. Herein, we push the resolution limits of synchrotron-based nanoprobe X-rayfluorescence mapping to 80 nm, to investigate a recombination-active intragranular defect in industrialsolar cells. Our nano-XRF measurements distinguish fundamental differences between benign anddeleterious dislocations in solar cell devices: we observe recombination-active dislocations to containa high degree of nanoscale iron and copper decoration, while recombination-inactive dislocationsappear clean. Statistically meaningful high-resolution measurements establish a connection betweencommercially relevant materials and previous fundamental studies on intentionally contaminatedmodel defect structures, pointing the way towards optimization of the industrial solar cell process.Moreover, this study presents a hierarchical characterization approach that can be broadly extended toother nanodefect-limited energy systems with the advent of high-resolution X-ray imaging beamlines
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- Chigrinova, Ekaterina, et al.
(author)
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Two main genetic pathways lead to the transformation of chronic lymphocytic leukemia to Richter syndrome
- 2013
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In: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 122:15, s. 2673-2682
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Journal article (peer-reviewed)abstract
- Richter syndrome (RS) occurs in up to 15% of patients with chronic lymphocytic leukemia (CLL). Although RS, usually represented by the histologic transformation to a diffuse large B-cell lymphoma (DLBCL), is associated with a very poor outcome, especially when clonally related to the preexisting CLL, the mechanisms leading to RS have not been clarified. To better understand the pathogenesis of RS, we analyzed a series of cases including 59 RS, 28 CLL phase of RS, 315 CLL, and 127 de novo DLBCL. RS demonstrated a genomic complexity intermediate between CLL and DLBCL. Cell-cycle deregulation via inactivation of TP53 and of CDKN2A was a main mechanism in the histologic transformation from CLL phase, being present in approximately one half of the cases, and affected the outcome of the RS patients. A second major subgroup was characterized by the presence of trisomy 12 and comprised one third of the cases. Although RS shared some of the lesions seen in de novo DLBCL, its genomic profile was clearly separate. The CLL phase preceding RS had not a generalized increase in genomic complexity compared with untransformed CLL, but it presented clear differences in the frequency of specific genetic lesions.
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- Bertoni, M. I., et al.
(author)
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Nano-XRF and micro-Raman Studies of Metal Impurity Decoration around Dislocations in Multicrystalline Silicon
- 2012
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In: 2012 38TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC). - New York, USA : IEEE. - 9781467300667 ; , s. 1613-1616
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Conference paper (peer-reviewed)abstract
- We push the resolution limits of synchrotron-based nano-X-ray fluorescence mapping below 100 nm to investigate the fundamental differences between benign and deleterious dislocations in multicystalline silicon solar cells. We observe that after processing recombination-active dislocations contain a high degree of nanoscale iron and copper decoration, while recombination-inactive dislocations appear clean. To study the origins of the distinct metal decorations around different dislocations we analyze as-grown samples as well as specimens at different stages of processing. We complement our X-ray studies with micro-Raman mapping to understand the relationship between metallic decoration and stress fields around dislocations.
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- Chirumalla, Koteshwar, et al.
(author)
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Knowledge Sharing Across Boundaries : Web 2.0 and Product-Service System Development
- 2011
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In: 3rd International Conference on Research into Design ICoRD'11. - Bangalore, India : Research Publishing Services. - 9789810877217
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Conference paper (peer-reviewed)abstract
- In recent years there has been a growing interest among product development organizations to capitalize on engineering knowledge as their core competitive advantage for innovation. Capturing, storing, retrieval, sharing and reusing of engineering knowledge from a wide range of enterprise memory systems have become crucial activities of knowledge management practice in competitive organizations. In light of a changing and dynamic enterprise definition, including a move towards Product-Service System (PSS) development, this paper discusses some of the limitations of current enterprise systems in reusing engineering knowledge across functional and corporate boundaries. Further, the paper illustrates how Web 2.0-based collaborative technologies can leverage cross-functional knowledge for new PSS development projects through an open, bottom-up, and collective sense-making approach to knowledge management.
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- Fenning, D. P., et al.
(author)
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Iron distribution in silicon after solar cell processing: Synchrotron analysis and predictive modelling
- 2011
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 98, s. 162103-
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Journal article (peer-reviewed)abstract
- The evolution during silicon solar cell processing of performance-limiting iron impurities isinvestigated with synchrotron-based x-ray fluorescence microscopy. We find that during industrialphosphorus diffusion, bulk precipitate dissolution is incomplete in wafers with high metal content,specifically ingot border material. Postdiffusion low-temperature annealing is not found to alterappreciably the size or spatial distribution of FeSi2precipitates, although cell efficiency improvesdue to a decrease in iron interstitial concentration. Gettering simulations successfully modelexperiment results and suggest the efficacy of high- and low-temperature processing to reduce bothprecipitated and interstitial iron concentrations, respectively.
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