The proposed research is in the field of nanofiber materials, focusing on the development of functional nanofibers for the complementary purposes of energy production and sustainable energy use. Significant opportunities exist in these areas, stemming from the development of several methods in the last decade for higher capacity nanofiber production, as well as the strategic need to find alternatives to current production of energy and its uses. Nanofibers are expected to bring revolutionary advances to these and many other fields of science and technology, including catalysis, filtration, protein separations, tissue engineering, and flexible electronics. We will work on creating such materials with potential applications in multi-exciton photovoltaics and catalysis for energy production. For sustainable energy use, we will develop bioinspired responsive materials and architectures, which would store energy, release it on demand, and act as life-like, efficient, and autonomous entities. Fundamental questions we will address in the research include: How do we tailor semiconductor band structures, as well as achieve nanoscale morphologies for efficient dissociation of photogenerated excitons? Can we develop general predictive rules for the conditions needed to fabricate nanofibers from any polymer solution by liquid shear processing? Can the molecular crystallinity and porosity be controlled in the fibers? What are the simplest life-like, autonomous devices that could be made with synthetic materials?This work will include extensive solution-based synthesis, processing, structural and chemical characterization (by optical and electron microscopy, small angle X-rays), physical property measurements (mechanical, optical, electronic), device fabrication and assembly, and computer simulations. Most of the facilities needed for the research are available in Cambridge, and some will be arranged for through external collaborations.