Degradation of Flexible Cu(In,Ga)Se2 Solar Cells

Untersuchungsgegenstand dieser Arbeit ist die Degradation flexibler Dünnschichtsolarzellen auf Basis von Cu(In,Ga)Se2 Absorbern. Zur beschleunigten Alterung unter Laborbedingungen wurden unverkapselte Solarzellen in Klimaschränken Wärme und Feuchte ausgesetzt. Die Auswirkungen von Wärme und Feuchte auf die Solarzellen wurden zunächst durch Messung von Strom–Spannungs–Kennlinien (IV) und Kapazitäts–Spannungs–Charakteristiken (CV) erschlossen. Mittels in–situ Messungen der IV–Kennlinien der Solarzellen unter Wärme und Feuchte konnte die Degradationskinetik untersucht werden. Es gelang zwei Phasen der Alterung, eine anfängliche Verbesserung und die eigentliche Degradation, zu unterscheiden. Außerdem war es dadurch möglich Degradationsraten zu bestimmen. Die Untersuchung der Stabilität der Flächenkontakte erfolgte im Schichtverbund der Solarzelle und separat. Dann wurde der Einfluss von Natrium, einem Bestandteil der Cu(In,Ga)Se2 Solarzellen, untersucht. Schichtzusammensetzung, Elementprofile und Oberflächenbeschaffenheit wurden mittels Laser–induzierter Plasmaspektroskopie (LIBS), Sekundärionen–Massenspektrometrie (SIMS), Rasterelektronenmikroskopie (SEM) und 3D–Lasermikroskopie gemessen. Die Rolle von Natrium für den Degradationsprozess konnte für zwei unterschiedliche Methoden der Natriumeinbringung in den Absorber (Ko–Verdampfung, Nachbehandlung) beschrieben werden. Schließlich wurde mittels Elektrolumineszenz (EL), Thermographie (DLIT) und der Messung Lichtstrahl–induzierter Ströme (LBIC) die Degradation ortsaufgelöst untersucht und Inhomogenitäten detektiert. Aus spannungsabhängigen Elektrolumineszenzaufnahmen gelang es Serienwiderstandskarten zu errechnen. Die Kombination der genannten Messmethoden erlaubte eine Identifizierung dominanter Degradationsprozesse in den flexiblen Cu(In,Ga)Se2 Solarzellen unter Wärme und Feuchte. Unter anderen wurde die Degradation der Grenzfläche zwischen Absorber und Rückkontakt diskutiert. Die Degradationskinetik konnte beschrieben, Solarzelllebensdauern abgeschätzt, die für die Wärme–Feuchte–Stabilität nachteilige Wirkung von Natrium identifiziert und laterale Inhomogenitäten des Degradationsprozesses aufgezeigt werden. Aus der Diskussion der Ergebnisse wurden Vorschläge zur Verbesserung der Wärme–Feuchte–Stabilität abgeleitet

1992 NASA/ASEE Summer Faculty Fellowship Program

For the 28th consecutive year, a NASA/ASEE Summer Faculty Fellowship Program was conducted at the Marshall Space Flight Center (MSFC). The program was conducted by the University of Alabama and MSFC during the period June 1, 1992 through August 7, 1992. Operated under the auspices of the American Society for Engineering Education, the MSFC program, was well as those at other centers, was sponsored by the Office of Educational Affairs, NASA Headquarters, Washington, DC. The basic objectives of the programs, which are the 29th year of operation nationally, are (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate and exchange ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participants' institutions; and (4) to contribute to the research objectives of the NASA centers

Translational Oncogenomics and Human Cancer Interactome Networks

An overview of translational, human oncogenomics, transcriptomics and cancer interactomic networks is presented together with basic concepts and potential, new applications to Oncology and Integrative Cancer Biology. Novel translational oncogenomics research is rapidly expanding through the application of advanced technology, research findings and computational tools/models to both pharmaceutical and clinical problems. A self-contained presentation is adopted that covers both fundamental concepts and the most recent biomedical, as well as clinical, applications. Sample analyses in recent clinical studies have shown that gene expression data can be employed to distinguish between tumor types as well as to predict outcomes. Potentially important applications of such results are individualized human cancer therapies or, in general, ‘personalized medicine’. Several cancer detection techniques are currently under development both in the direction of improved detection sensitivity and increased time resolution of cellular events, with the limits of single molecule detection and picosecond time resolution already reached. The urgency for the complete mapping of a human cancer interactome with the help of such novel, high-efficiency / low-cost and ultra-sensitive techniques is also pointed out

Development of a novel series interconnect for thin-film photovoltaics

Thin-film photovoltaics (TF-PV) offer possible cost savings from reduced semiconductor usage compared to the incumbent crystalline silicon technology. During manufacture TF-PV devices are deposited onto a large glass panel and split into many, series interconnected, cells in order to obtain a useful electrical output. M-Solv has patented a novel process to do this series interconnection in a single step, One Step Interconnect (OSI), after the deposition of all layers. This has a number of benefits compared to the conventional process including, but not limited to, reduced capital cost by ~30%, reduced panel transit time and reduced energy usage. In this thesis OSI is introduced, the individual processes developed (laser scribing, inkjet printing of insulator and conductor) and working modules manufactured. The electrical performance of the manufactured modules compare favourably with reference material from the same deposition run and modules interconnected in the conventional way. Fill factor (FF) is the principle metric when determining the quality of series interconnection and very high FF, ~80%, have been shown by OSI cells. Preliminary lifetime testing guided by the IEC 61646 specification has been carried out and the results are promising with OSI cells surviving more than double the required number of thermal cycles from -40 to +85°C with no sign of performance degradation

Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 291)

This bibliography lists 131 reports, articles and other documents introduced into the NASA scientific and technical information system in November 1986

Research reports: 1991 NASA/ASEE Summer Faculty Fellowship Program

The basic objectives of the programs, which are in the 28th year of operation nationally, are: (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participants' institutions; and (4) to contribute to the research objectives of the NASA Centers. The faculty fellows spent 10 weeks at MSFC engaged in a research project compatible with their interests and background and worked in collaboration with a NASA/MSFC colleague. This is a compilation of their research reports for summer 1991

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 355)

This bibliography lists 147 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during October, 1991. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance