This proposal presents an integrated research and education plan in the area of active hybrid nanocrystal-carbon nanotube (CNT) structures for optoelectronic applications. The proposed research program aims to advance the fundamental understanding and the optoelectronic device application of the novel hybrid nanostructures. Specific goals of the project are: (1) to produce various hybrid nanocrystal- CNT structures in a controlled fashion; (2) to probe the electronic transduction mechanism between the nanocrystal and the CNT through the characterization of properties of hybrid nanostructures, particularly electronic and physical interactions between the nanocrystal and the CNT under various gas and optical modulations; (3) to explore the use of hybrid semiconductor nanocrystal or quantum dot (QD)-CNT nanostructures for photovoltaic cells.
Intellectual Merit: The proposed research is potentially transformative and is based on results from the PI?s earlier exploratory studies. Hybrid nanocrystal-CNT structures represent a new class of nanomaterials that could potentially display not only the unique properties of nanocrystals and those of CNTs, but also additional novel properties due to the interaction between the nanocrystal and the CNT. The availability of controlled hybrid nanostructures and their fundamental properties will open up new opportunities for nanoscience and nanotechnology and will accelerate discoveries and inventions. The hybrid nanostructures can respond to stimuli (e.g., light and gas) and thus are " active." The synergistic response from the nanocrystal and the CNT can be harnessed for various innovative device applications, including photovoltaic cells, gas sensors, and biosensors. The generic electrostatic force directed assembly technique to deposit either aerosol or colloidal nanocrystals onto CNTs is facile and flexible in creating desired hybrid nanostructures. Detailed characterization of the hybrid nanostructure properties through a number of techniques will provide physical insights into electronic/physical interactions and the electronic transduction mechanism between nanocrystals and CNTs. The new architecture for photovoltaic cells will take advantage of the high electron mobility in CNTs, efficient electronic transfer between nanocrystals and CNTs, effective charge separation at the CNT-quantum dot (QD) interface, and many virtues of QDs, such as the potential for fine-tuning optical absorption through judiciously selecting QD materials and sizes, and the possibility of multiple electron-hole pair generation per photon. Therefore, this project will also lead to cost-effective solar cells for harvesting abundant, renewable, clean solar energy to help relieve our global energy problem.
Broader Impacts: The broader impacts of this project are far-reaching, as the project results will enable a wide range of innovative applications of hybrid nanocrystal-CNT structures with optimum properties that can be tailored for specific conditions. The new photovoltaic cells will help reduce our dependence on fossil fuels and their associated adverse environmental effects due to greenhouse gas emissions. The proposed research is extensively integrated into educational goals to promote transformative and interdisciplinary engineering education to attract more underrepresented students into science, technology, engineering, and mathematics (STEM) fields, and to broadly disseminate nanotechnology findings. The proposed engineering education plan will help our students to become more adaptive and innovative in rapidly changing environments. The existing NSF REU program and the undergraduate honors in research program at UWM will be leveraged to involve undergraduate researchers. The project will reach the broader student population through a course module on hybrid nanostructures and integration of small nanotechnology projects into existing curricula. Special efforts to inspire underrepresented pre-college students through ?Science Saturdays? and by mentoring science projects will attract more underrepresented students to STEM fields. Additional outreach through a course module to be posted on a high-impact NSF-sponsored National Center for Learning and Teaching Web site, a nanotechnology exhibit in conjunction with Milwaukee Discovery World Museum, and regional science fairs in collaboration with Wisconsin Career Academy, will effectively disseminate nanotechnology to a wide range of audiences.
