Four-Terminal Perovskite-CIGS Tandem Solar Cells with Improved Near-Infrared Response

Perowskit-CIGS-Tandem-Solarzellen zeigen großes Potenzial Wirkungsgrade von über 30% zu erreichen und damit die Kommerzialisierung der Dünnschicht-Photovoltaik zu revolutionieren. Parasitäre Verlustmechanismen wie etwa eine unerwünschte Absorption von langwelligem Licht in den Kontaktschichten limitieren jedoch die maximale Effizienz der Tandem-Solarzellen. Diese Dissertation beschäftigt sich mit der Entwicklung hocheffizienter, semitransparenter Perowskitsolarzellen, der Minimierung parasitärer Verluste in deren Kontaktschichten und mit der Herstellung von gestapelten Tandem-Solarzellen mit CIGS als Partnerzelle. Dafür wird zunächst die Effizienz von opaken Perowskitsolarzellen durch die Implementierung einer zusätzlichen Fulleren-basierten Elektronenleiterschicht optimiert, was durch die Entwicklung eines neuartigen Nanopartikel-basierten Verfahrens zur Verbesserung der Benetzbarkeit unterstützt wird. Die Entwicklung spezieller transparenter Kontaktschichten aus Wasserstoff-dotiertem Indiumoxid (IO:H) und Indiumzinkoxid (IZO) erfolgt durch Kathodenzerstäubung unter variabler Zugabe von Sauerstoff- bzw. Wasserstoffgas. Die nachträgliche Kristallisation von amorphem IO:H führt zu besonders niedrigen Absorptionseigenschaften im nahen Infrarotbereich, was für die Anwendung in Tandem-Solarzellen von entscheidendem Vorteil ist. Semitransparente Perowskitzellen, die mit diesen Kontakten ausgestattet sind, erreichen hohe Effizienzen von über 15%und ermöglichen eine Steigerung der mittleren Zell-Transmission von 55% auf 75% verglichen mit kommerziellen Kontaktschichten wie Indiumzinnoxid (ITO). Durch diese Transmissionssteigerung werden Tandem-Solarzellen realisiert, die eine gemeinsame Zellfläche von 0,5 cm² und einen verbesserten Wirkungsgrad von bis zu 23,0% aufweisen. Die Analyse der optischen Verlustmechanismen der verschiedenen Tandem-Solarzellen mittels Simulations-gestützter Methoden zeigt unter anderem auf, dass der Beitrag der Kontaktschichten zu den parasitären Gesamtabsorptionsverlusten von ca. 60% auf 40% gesenkt werden kann

Ultrastructural characterization of ultraviolet induced corneal disease : an animal model

The majority of ancient people worshipped the sun and viewed it as a health - bringing deity. During the eighteenth and nineteenth century therapeutic benefits of sunlight exposure were beginning to be understood and by the end of the nineteenth century the importance of ultraviolet radiation was being realized. Danish physician Niels Finsen, whom many regard as the father of ultraviolet phototherapy, also stressed that it was ultraviolet radiation in the solar spectrum which cause sunburn. We now recognize that the small portion of ultraviolet radiation which reaches the earth's surface is not necessarily therapeutic, but in fact could be harmful to humans. There are numerous accounts of the harmful effects of UV radiation to the skin and the eye as a whole. These effects may be caused by either acute or chronic exposure to UV radiation. For example, some acute effects of UV-B radiation include conjunctivitis and photokeratitis. "Snow blindness" and "arc welders eye" are further examples of acute ultraviolet damage specifically to the surface of the cornea. On the other hand, chronic exposure to ultraviolet radiation is thought to be responsible for pterygia, climatic droplet keratopathy Hill and Maske (1989), cancers of the external eye, cataracts and various types of retinal diseases. The present study is an extension of ongoing studies on ultraviolet radiation damage to the cornea in the Department of Ophthalmology, University of Cape Town and Groote Schuur Hospital. Their specific interest lies in the causes and treatment of climatic droplet keratopathy. The aims of the present study are: 1) Establish a possible role of ultraviolet B radiation in human corneal diseases such as climatic droplet keratopathy and pterygium using the rabbit as an animal model. 2) Determine by means of SEM the initial effects and subsequent recovery of the epithelium after a 3-hour dose of ultraviolet B radiation. We refer to this study as "acute" response to ultraviolet B radiation. 3) To try and confirm the effects observed by SEM with ultrastructural studies using TEM. 4) In addition, we are also looking at the possible effects after exposing rabbit cornea to a daily dose of low level ultraviolet B radiation, over a long period of time. We refer to this as chronic exposure to ultraviolet B radiation. It is hoped that by exposing rabbits to ultraviolet light, principally ultraviolet B radiation, diseases similar to those found in humans could be simulated and disease progression studied. People are generally exposed to substantial amounts of UV radiation for a very long time. Since people generally live longer they will be exposed to an ever-increasing amount of solar UV radiation and subsequently, there is an increasing risk of developing corneal diseases. The possible threat to the ozone is also a real possibility and could lead to increased levels of ultraviolet radiation reaching the earth's surface. This will require a greater understanding of the very nature of corneal damage due to acute and chronic exposure. This study focusses mainly on the acute response to UV-B radiation since most studies have investigated effects of prolonged exposure to UV light. Accordingly, much less is known about acute exposure. Many people suffering from acute UV B radiation effects probably never visit the ophthalmologist or wait for a couple of days. This could also contribute to the fact that effects of short-term damage is not well documented

Route Planning in Road Networks

We present various speedup techniques for route planning in road networks. After performing some preprocessing steps, we can compute accurate quickest-path lengths in a few microseconds on a 2.0 GHz machine, using real-world road networks with several million nodes. In addition to dealing with the static point-to-point problem, we also handle dynamic scenarios (like traffic jams) and many-to-many instances

Any Gods Out There? Perceptions of Religion from Star Wars and Star Trek

Hollywood films and religion have an ongoing rocky relationship, especially in the realm of science fiction. A brief comparison study of the two giants of mainstream sci-fi, Star Wars and Star Trek reveals the differing attitudes toward religion expressed in the genre. Star Trek presents an evolving perspective, from critical secular humanism to begrudging personalized faith, while Star Wars presents an ambiguous mythological foundation for mystical experience that is in more ways universal

On the Margins of Religion/On the Forefront of Culture: The Image of the Matka Polka (Polish Mother) in Contemporary Poland

As Jane Bayes and Nayareh Tohidi point out in their introduction to Globalization, Gender, and Religion, one of the main issues that came up at the 1995 UN Fourth World Conference on Women in Beijing was the conflict between women’s rights and gender norms based on myths present in their religions, nations, and cultures. While these myths are constructs of patriarchal society, feminists argue that women often fall victim to “false consciousness” resulting from their hegemonic nature. Moreover, women raised in ethnic communities struggle with an even more difficult task—bridging their personal needs with their desire for community affiliation -religious or cultural. Within the Polish culture, the image of the traditional Polish mother, otherwise known as the Matka Polka, has shaped what it means to be a woman in Poland in terms of her duty toward family and country. Dating back tothe Renaissance and the Holy Mother, who was supposed to watch over Poland and not let it fall in the hands of partitioning nations, the Polish Mother functions on the margins of the intersecting fields of religion, nation, and gender. This paper willattempt to analyze how the Matka Polka is defined in these terms and her impact on Polish women in relation to the roles ascribed to them by their ethnicity and culture