We demonstrate four- and two-terminal perovskite-perovskite tandem solar cells with ideally matched band gaps. We develop an infrared-absorbing 1.2-electron volt band-gap perovskite, FACsSnPbI, that can deliver 14.8% efficiency. By combining this material with a wider-band gap FACsPb(IBr) material, we achieve monolithic two-terminal tandem efficiencies of 17.0% with >1.65-volt open-circuit voltage. We also make mechanically stacked four-terminal tandem cells and obtain 20.3% efficiency. Notably, we find that our infrared-absorbing perovskite cells exhibit excellent thermal and atmospheric stability, not previously achieved for Sn-based perovskites. This device architecture and materials set will enable "all-perovskite" thin-film solar cells to reach the highest efficiencies in the long term at the lowest costs.

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In this paper, we describe two explorations in the use of hybrid user interfaces for collaborative geographic data visualization. Our first interface combines three technologies: augmented reality (AR), immersive virtual reality (VR), and computer vision-based hand and object tracking. Wearing a lightweight display with an attached camera, users can look at a real map and see three-dimensional virtual terrain models overlaid on the map. From this AR interface, they can fly in and experience the model immersively, or use free hand gestures or physical markers to change the data representation. Building on this work, our second interface explores alternative interface techniques, including a zoomable user interface, paddle interactions, and pen annotations. We describe the system hardware and software and the implications for GIS and spatial science applications.

STARLIGHT is an example of a new class of information system expressly designed around a visualization-oriented user-interface. Incorporating more traditional information storage and retrieval technologies into its design, the Starlight system also enables the integrated use of multiple, concurrent visualization techniques to support comparison of content and interrelationship information at several levels of abstraction simultaneously. This approach enables powerful new forms of information analysis, while at the same time easing cognitive workloads by providing a visual context for the information under study. Originally developed for intelligence analysis applications, the Starlight software is intended to support the rapid, concurrent analysis of complex multimedia information, including structured and unstructured text, geographic information, and digital imagery. The system uses novel 3-D visualization techniques that interactively generate easily understandable representations of explicit and implicit relationships contained in information collections of various types. This paper describes the general theory behind our approach, and the design and features of a Windows NT-based operational system.