Elucidating the origins of high preferential crystal orientation in quasi‐2D perovskite solar cells

Incorporating large organic cations to form 2D and mixed 2D/3D structures significantly increases the stability of perovskite solar cells. However, due to their low electron mobility, aligning the organic sheets to ensure unimpeded charge transport is critical to rival the high performances of pure 3D systems. While additives such as methylammonium chloride (MACl) can enable this preferential orientation, so far, no complete description exists explaining how they influence the nucleation process to grow highly aligned crystals. Here, by investigating the initial stages of the crystallization, as well as partially and fully formed perovskites grown using MACl, the origins underlying this favorable alignment are inferred. This mechanism is studied by employing 3-fluorobenzylammonium in quasi-2D perovskite solar cells. Upon assisting the crystallization with MACl, films with a degree of preferential orientation of 94%, capable of withstanding moisture levels of 97% relative humidity for 10 h without significant changes in the crystal structure are achieved. Finally, by combining macroscopic, microscopic, and spectroscopic studies, the nucleation process leading to highly oriented perovskite films is elucidated. Understanding this mechanism will aid in the rational design of future additives to achieve more defect tolerant and stable perovskite optoelectronics

Bericht der AG Primo-Implementierung an die Vollversammlung des österreichischen Bibliothekenverbundes zum möglichen Einsatz des Dienstes Primo Central

Applicability of the discovery service Primo Central for Austrian academic libraries. A Report of the task force PrimoImplementation for the Austrian Library Network. In winter 2010/11 the task force PrimoImplementation of the Austrian Library Network evaluated Primo Central, the Discovery and Delivery Service from Ex Libris, by means of a three month test account and several Q&A sessions with product developers from Ex Libris. Primo Central integrates hundreds of millions of metadata from various data vendors with local holdings. The product was found to be comprehensive in many areas of research (mainly scholarly journal articles), well representing the holdings of a large as well as a medium multi-faculty university library. The lack of national (German) and regional titles severely affects searches for Austrian and German law, it partly affects searches in the fields of economics, psychology and civil engineering, too. Primo Central is updated regularly, but has to be less up-to-date than publisher platforms or PubMed or real time federated search engines like Meta-Lib. Perpetual availability of records from publishers or database vendors cannot be guaranteed by Ex Libris. Currently, metadata of resources indexed in Primo Central mainly do not come from the publishers themselves, but from CrossRef or IngentaConnect. Therefore subject indexing is often missing for these records. Search functionalities and display of relevance ranked search results are comparable to Google Scholar, additional features of Primo Central being faceted search and the opportunity to show only those results available at the particular library. Implementation of Primo Central has been smooth and quick. Preliminaries for the use of Primo Central are the use of Primo as library search engine or MetaLib as federated search engine and a link resolver (not necessarily SFX)

Quality Evaluation for Big Data: A Scalable Assessment Approach and First Evaluation Results

High-quality data is a prerequisite for most types of analysis provided by software systems. However, since data quality does not come for free, it has to be assessed and managed continuously. The increasing quantity, diversity, and velocity that characterize big data today make these tasks even more challenging. We identified challenges that are specific for big data quality assessments with particular emphasis on their usage in smart ecosystems and make a proposal for a scalable cross organizational approach that addresses these challenges. We developed an initial prototype to investigate scalability in a multinode test environment using big data technologies. Based on the observed horizontal scalability behavior, there is an indication that the proposed approach also allows dealing with increasing volumes of heterogeneous data