TECHNICAL SUMMARY: The project aims to develop novel nanostructured inorganic materials with programmable physical and chemical properties. The approach involves new chemistry for solution-based fabrication of inorganic functional materials from nanoscale building blocks. Specifically, functional nanostructured phases will be synthesized by combining colloidal inorganic nanomaterials (metal and semiconductor clusters, nanocrystals, nanowires, etc) and molecular metal chalcogenide complexes. Various molecular metal chalcogenide complexes, such as SnS44-, Sn2Se64-, In2Se42-, Ge4S104- will be used to completely replace original hydrocarbon surface ligands at the surface of colloidal metal and semiconductor nanostructures. After formation of a nanostructured assembly, new surface ligands will be converted into an inorganic solid, linking individual nano-building blocks into a macroscopic array of strongly electronically coupled functional modules. The project will combine the development of synthetic methodologies, detailed structural, electronic and optical characterizations of new materials and fabrication of prototype electronic and optoelectronic devices.

NON-TECHNICAL SUMMARY: The project aims to develop a generalized methodology for preparation of nanostructured inorganic materials through ?modular? self-assembly of nanoscale functional building blocks. This approach may lead to a novel class of solution processed semiconductors for the applications ranging from solar cells to thermoelectric heat converters, light-emitting devices and printable electronics. The integration of research and educational components will generate broad outreach and educational activities including participation in the conceptual design and development of the Nanoscience exhibit for Chicago Museum of Science and Industry. The Museum attracts approximately 2 million visitors per year, nearly 280,000 children in school groups and youth organizations visited the Museum in 2007. Aimed at inspiring youth to consider education and careers in the physical and biological sciences, the objective of new exhibit is to convey the excitement of modern scientific research, its multidisciplinary nature, and the synergy between different areas of science and technology.

Project Report

Intellectual merit: Development of synthetic methods for well-defined nanostructures has introduced new approaches for engineering functional materials. Nanomaterials can be used as the building blocks for designing solids with tailored electronic, magnetic, optical and catalytic properties. We have designed different approaches to engineer nanocrystal structure and surface chemistry for various applications. This NSF CAREER project has introduced the concept of inorganic surface ligands for nanomaterials. Obtained results have been summarized in 21 publications in leading scientific journals: J. Am. Chem. Soc.(15), Nature(1), Nature Materials (1), Nature Nanotech.(1), Chem Rev (1), MRS Bulletin (1) and Nano Lett. (1). These publications already collected more than 1000 citations, highlighting a broad interest of scientific community in this topic. Within this NSF CAREER project we worked out ideas for designing nanomaterial surfaces in a way that was very different from everything tried before. Instead of traditionally-used organic surface coatings, we introduced fully inorganic ligands for colloidal nanomaterials. As a first example, we used "metal chalcogenide complexes" (MCCs), shown in Figure 1, which are a rich family of molecular species combining only metals and chalcogens. We found that MCCs have a very high affinity to surfaces of different nanocrystals (NCs) and nanowires (Figure 1B). The nanostructures with attached MCC ligands can be used as all-inorganic building blocks that form stable colloidal solutions. These solutions can be used to form NC layers by printing or spin-coating. The MCC ligands link individual nano-building blocks into an all-inorganic macroscopic assembly of strongly electronically coupled functional modules. We also showed that metal ion linkers can be used to further engineer almost every property of all-inorganic NCs and NC arrays (Figure 1C). With the support from NSF, we explored different approaches to design practical materials from inorganic colloidal NCs. Thus, we demonstrated printable field-effect transistors using NCs capped with MCC and metal-free inorganic ligands. These devices showed record electron mobilities for solution-processed semiconductors (Figure 2A); we also employed MCC-capped nano-heterostructures as sensitive photodetectors (Figure 2B). The combinations of colloidal NCs with MCC ligands resulted in new class of soluble precursors for synthesis of CuIn1-xGaxSe2 (CIS) and Cu2ZnSn(S,Se)4 (CZTS) films for thin-film photovoltaics. We also used NC-MCC chemistry to fabricate thermoelectric Bi2?xSbxTe3 nanostructured (Figure 2C). Broader impacts: Contribution to the development of human resources. This project helped my students and postdocs to develop intellectual leadership in science and engineering. Two high school students have been introduced to research and worked my lab. One of them, Dan Ilyin, was a finalist in the US National Chemistry Olympiad in 2011. Five undergraduate students supported by this Project decided to pursue further education at graduate schools. One of them, Fernando Castro, belongs to an underrepresented minority group. Three graduate students successfully defended their dissertations. Four of postdocs started independent academic careers in leading institutions. Outreach to policy makers and business leaders at the Science and Technology in Society (STS) Forum in Kyoto, Japan. The STS Forums is a platform for dialogue between scientific, industrial and political leaders. In 2011 the Forum participants represented over 90 countries, including 30 Ministers in charge of science and technology policy, 9 Nobel Laureates, over 100 top business executives and 17 Science Academy Presidents. I was selected by the New York Academy of Sciences to represent young scientists of North America. Ten young scientists from Japan, Nigeria, Bangladesh, Singapore, Burundi, Germany, Netherlands and United States prepared the message from "Future Leaders" and delivered it at the Plenary Session to political, scientific and business leaders (Figure 3). In our message to the world leaders, we addressed a range of topics focused around the theme "SCIENTIFIC RESEARCH IS A GLOBAL NECESSITY". Outreach to the general public through Chicago Museum of Science and Industry. The Museum of Science and Industry (MSI) in Chicago offers an ideal platform to go beyond the laboratory and the classroom in order to improve the education of the general public, particularly the high-school students, about the importance and implications of basic research. MSI attracts approximately 2 million visitors per year. Among these visitors, nearly 280,000 are children in school groups and youth organizations. I participated in the conceptual design and development of a new Nanoscience exhibit at MSI. My research group also actively participated in the MSI project "Interactive Periodic Table" which is a part of the "Science Storms" exhibit that opened in 2011. Using the Interactive Periodic Table, MSI visitors can use the drag-and-drop approach to the elements, mixing and matching them in a virtual chemical lab. They can choose elements from a projected periodic table, and pull them into a reaction lab to see what happens. They can bring in more molecules of the same element, throw new ones into the mix or just start over. My students helped to develop a chemical reactions database for this exhibit (Figure 4).

Agency
National Science Foundation (NSF)
Institute
Division of Materials Research (DMR)
Application #
0847535
Program Officer
Michael J. Scott
Project Start
Project End
Budget Start
2009-02-01
Budget End
2014-01-31
Support Year
Fiscal Year
2008
Total Cost
$605,000
Indirect Cost
Name
University of Chicago
Department
Type
DUNS #
City
Chicago
State
IL
Country
United States
Zip Code
60637