ACS Award In The Chemistry Of Materials

Sponsored by E. I. du Pont de Nemours & Co.

Semiconductor nanocrystals are one of today’s hottest topics in materials chemistry. As a result of their size-dependent optical and electronic properties, these microscopic bits of matter, which are also known as quantum dots and include materials such as CdSe, CdS, and PbSe, have captured the attention of researchers worldwide. Scores of scientists are working to develop ways to synthesize custom quantum dots, to understand their basic properties, and to use these crystals in low-cost electronic devices, solar cells, and other applications.

Much of the activity in the quantum dot field today can be traced to the groundbreaking work in the 1990s of University of California, Berkeley, chemistry and materials science and engineering professor A. Paul Alivisatos.

Alivisatos, who is the Samsung Distinguished Professor of Nanoscience & Nanotechnology and serves as director of Lawrence Berkeley National Laboratory, published some of the earliest studies detailing the now well-established dependence of quantum dots’ electronic, optical, and structural properties on particle size. In addition, long before journals were filled with papers reporting the latest quantum dot findings, Alivisatos’s group was devising colloidal chemistry methods for synthesizing defect-free nanocrystals with very narrow size distributions, a key requirement for studying and exploiting their optical properties.

Shortly after those early-1990s developments, Alivisatos’s team showed that quantum dots could be used to fabricate novel light-emitting diodes. Then they demonstrated that fluorescent quantum dots and quantum rods could serve as colorful beacons for imaging cells. Specifically, the team developed methods for binding quantum dots to select organic molecules and delivering them into cells and tissues, where the size-dependent colors of the dots could light up targeted parts of cells.

As Alivisatos’s team became increasingly skilled at controlling the composition, purity, size, and shape of quantum dots, they expanded the materials’ reach to renewable energy applications. One example in this area is the team’s development of inexpensive photovoltaic cells in which thin films of quantum dots control the cells’ light absorption and charge-transport functions. In related work, Alivisatos’s group developed quantum-dot-seeded nanorods and other nanoscale hybrid materials that harness solar energy to produce hydrogen and other fuels.

“Paul is a pioneering materials chemist whose work has made a significant technological impact and whose leadership has benefited the materials chemistry community in many ways,” says UC Berkeley chemistry professor Omar M. Yaghi. Backing up that assertion, Yaghi notes that Alivisatos has mentored more than 130 graduate students and postdoctoral researchers, has founded nanotechnology companies, and has been instrumental in establishing a center for nanoscale research. He adds that Alivisatos’s efforts and innovative research have brought health, energy, and economic benefits to society.

Alivisatos, 55, completed his undergraduate education in chemistry at the University of Chicago in 1981 and earned a Ph.D. in chemical physics from UC Berkeley in 1986. He then conducted postdoctoral research at Bell Labs and, in 1988, accepted a faculty position at UC Berkeley. He is a member of the National Academy of Sciences and the American Academy of Arts & Sciences and is co-editor-in-chief of Nano Letters.

Alivisatos will present his award address before the Division of Colloid & Surface Chemistry.