Steric engineering of metal-halide perovskites with tunable optical band gaps

Owing to their high energy-conversion efficiency and inexpensive fabrication routes, solar cells based on metal-organic halide perovskites have rapidly gained prominence as a disruptive technology. An attractive feature of perovskite absorbers is the possibility of tailoring their properties by changing the elemental composition through the chemical precursors. In this context, rational in silico design represents a powerful tool for mapping the vast materials landscape and accelerating discovery. Here we show that the optical band gap of metal-halide perovskites, a key design parameter for solar cells, strongly correlates with a simple structural feature, the largest metal-halide-metal bond angle. Using this descriptor we suggest continuous tunability of the optical gap from the mid-infrared to the visible. Precise band gap engineering is achieved by controlling the bond angles through the steric size of the molecular cation. Based on these design principles we predict novel low-gap perovskites for optimum photovoltaic efficiency, and we demonstrate the concept of band gap modulation by synthesising and characterising novel mixed-cation perovskites.Comment: This manuscript was submitted for publication on March 6th, 2014. Many of the results presented in this manuscript were presented at the International Conference on Solution processed Semiconductor Solar Cells, held in Oxford, UK, on 10-12 September 2014. The manuscript is 37 pages long and contains 8 figure

Reshaping Cityspace: Studying Spatial Isolation And Perceptions Of Justice In Syracuse’s Southside

On October 3rd, 1929, at nine o’clock in the morning, the national retail giant Sears-Roebuck & Company opened the doors to a new facility strategically located on Syracuse’s South Salina Street and what was formerly known as West Raynor Avenue. This was 1 of 319 store locations opened by Sears that year alone. In 1964 and 1965, the S-R & Co. continued to grow in Central New York with expansion of the Automobile Center at the Salina location and opening of another new store in the Fairmount Fair Shopping Center North of Syracuse. This expansion of Sears’ presence in Syracuse hardly foreshadowed the disinvestment that would occur 19 years later in 1979. Now, approaching 94 years since inception, the original facility still stands in the South Side of Syracuse as a hollowed-out vault used for storing medical archives. The building’s physical existence is a derelict ode to a neighborhood that was once a stable component of a rising local economy here in Syracuse. This intersection of the South Side at South Salina and Mr. Luther King Jr. East/West is a transitional place; the spaces of which stand stagnantly, perpetually arrested by decline after decades of emigration and disinvestment. Urban development processes are the primary vehicles through which the consequential geographies of cityspaces are created. This project is designed to scale down the wider debates of spatial and social justices by examining how cityspace is reshaped here in Syracuse. Beyond looking at the power of space and place, I am hoping to explore the power of perceptions of space, the goal being to sharpen understandings of what factors both drive and stunt urban development processes. The ultimate purpose of this project would be in re-implementing that power of perception to engage stakeholders in re-claiming the lost spaces within cityspace, like those along Syracuse’s South Side. Leveraging the discourses of urban geography, culture, and justice as channels for community empowerment, this project is set to amplify both the historic and contemporary narratives of strategic spatial transformations found in the inner-city neighborhoods of Syracuse. This project explores how certain inner-city spaces in Syracuse are reshaped through urban development, while processes of spatial isolation and injustices seemingly usurp other areas of similar reshaping. I draw on findings from a number of disciplines including urban theory, social & cultural sciences, landscape design and architecture. In depth archival analysis is used to present this former Sears-Roebuck and Company department store as a central research site for the project. Core perception data is further substantiated by qualitative research, conducted in the South Side and surrounding areas of Central New York in order to best develop this argument

Reshaping Cityspace: Studying Spatial Isolation And Perceptions Of Justice In Syracuse’s Southside

On October 3rd, 1929, at nine o’clock in the morning, the national retail giant Sears-Roebuck & Company opened the doors to a new facility strategically located on Syracuse’s South Salina Street and what was formerly known as West Raynor Avenue. This was 1 of 319 store locations opened by Sears that year alone. In 1964 and 1965, the S-R & Co. continued to grow in Central New York with expansion of the Automobile Center at the Salina location and opening of another new store in the Fairmount Fair Shopping Center North of Syracuse. This expansion of Sears’ presence in Syracuse hardly foreshadowed the disinvestment that would occur 19 years later in 1979. Now, approaching 94 years since inception, the original facility still stands in the South Side of Syracuse as a hollowed-out vault used for storing medical archives. The building’s physical existence is a derelict ode to a neighborhood that was once a stable component of a rising local economy here in Syracuse. This intersection of the South Side at South Salina and Mr. Luther King Jr. East/West is a transitional place; the spaces of which stand stagnantly, perpetually arrested by decline after decades of emigration and disinvestment. Urban development processes are the primary vehicles through which the consequential geographies of cityspaces are created. This project is designed to scale down the wider debates of spatial and social justices by examining how cityspace is reshaped here in Syracuse. Beyond looking at the power of space and place, I am hoping to explore the power of perceptions of space, the goal being to sharpen understandings of what factors both drive and stunt urban development processes. The ultimate purpose of this project would be in re-implementing that power of perception to engage stakeholders in re-claiming the lost spaces within cityspace, like those along Syracuse’s South Side. Leveraging the discourses of urban geography, culture, and justice as channels for community empowerment, this project is set to amplify both the historic and contemporary narratives of strategic spatial transformations found in the inner-city neighborhoods of Syracuse. This project explores how certain inner-city spaces in Syracuse are reshaped through urban development, while processes of spatial isolation and injustices seemingly usurp other areas of similar reshaping. I draw on findings from a number of disciplines including urban theory, social & cultural sciences, landscape design and architecture. In depth archival analysis is used to present this former Sears-Roebuck and Company department store as a central research site for the project. Core perception data is further substantiated by qualitative research, conducted in the South Side and surrounding areas of Central New York in order to best develop this argument

Hello, Janice: The Wartime Letters of Henry Giles

The novels of Janice Holt Giles grew in part from her marriage to Kentuckian Henry Giles. That union and the couple\u27s settling near Henry\u27s boyhood home in Kentucky provided the source and inspiration for Janice\u27s earliest books and influenced much of her later writing. Hello, Janice tells the story of how their marriage came about.https://uknowledge.uky.edu/upk_english_language_and_literature_north_america/1016/thumbnail.jp

Networks as transnational agents of development

The term network has become a hallmark of the development industry. In principle networks have the potential to provide a more flexible and non-hierarchical means of exchange and interaction that is also more innovative, responsive and dynamic whilst overcoming spatial separation and providing scale economies. Although the label networks currently pervades discourses about the relationships between organisations in development, there has been surprisingly little research or theorisation of them. This article is a critical evaluation of the claims of developmental networks from a theoretical perspective. While networks are regarded as a counter hegemonic force we argue that networks are not static entities but must be seen as an ongoing and emergent process. Moreover theory overlooks power relationships within networks and is unable to conceptualise the relationship between power and values. These observations open up a research agenda that the authors are exploring empirically in forthcoming publications

Technology Directions for the 21st Century, volume 1

For several decades, semiconductor device density and performance have been doubling about every 18 months (Moore's Law). With present photolithography techniques, this rate can continue for only about another 10 years. Continued improvement will need to rely on newer technologies. Transition from the current micron range for transistor size to the nanometer range will permit Moore's Law to operate well beyond 10 years. The technologies that will enable this extension include: single-electron transistors; quantum well devices; spin transistors; and nanotechnology and molecular engineering. Continuation of Moore's Law will rely on huge capital investments for manufacture as well as on new technologies. Much will depend on the fortunes of Intel, the premier chip manufacturer, which, in turn, depend on the development of mass-market applications and volume sales for chips of higher and higher density. The technology drivers are seen by different forecasters to include video/multimedia applications, digital signal processing, and business automation. Moore's Law will affect NASA in the areas of communications and space technology by reducing size and power requirements for data processing and data fusion functions to be performed onboard spacecraft. In addition, NASA will have the opportunity to be a pioneering contributor to nanotechnology research without incurring huge expenses