Time: Thursday, May 9th, 10:30 a.m. & Friday, May 10th, 11:00 a.m.
Location: STUDENT UNION THEATER, Room 210
Lectures Are Free And Open To The Public
Perhaps the greatest pleasure of being a scientist is to have an
abstract idea, then to do a series of experiments which demonstrate
that the idea was correct --- To demonstrate that Nature actually
behaves as conceived in the mind of the scientist.
I will start with a story from my childhood illustrating "creativity, discovery and risk" at the age of four. My story which describes an "experiment" with a set of toy soldiers, a toy canon and the use of matches as projectiles was the very first time that I experienced this intense pleasure; the essence of creativity in science.
In science, creativity and discovery are related, but they are not the same. Scientific breakthroughs result from a combination of creativity and discovery. Watson and Crick discovered the structure of DNA, the Secret of Life. Arno Penzias and Robert Wilson made a Marvelous discovery! Their creativity: The invention of very low noise microwave amplifiers. Their discovery: They pointed their low noise amplifier into the night sky ---and discovered the black-body radiation that is the residual of the Big Bang at the creation of the Universe ! Albert Einstein created the idea of curved space-time as equivalent to, and the origin of, gravity. When, during the solar eclipse of 1919, light was observed to actually curve around the sun, Einstein became deservedly famous. Again --- creativity and discovery!
My experiments with the canon and the toy soldiers were the first indications that I might have a future as a scientist. Many years later, Alan MacDiarmid, Hideki Shirakawa and I had the idea that we could make polymers --- “Plastics” --- long chain macromolecules that would conduct electricity and exhibit the electrical and optical properties of metals and semiconductors. Our subsequent discovery of metallic levels of electrical conductivity in polyacetylene demonstrated that our ideas were both true and revolutionary; the field of semiconducting and metallic polymers had been created. Semiconducting and metallic polymers: In the beginning --- dirty materials that were complex and poorly characterized. My physicist friends thought that I was crazy --- thus serious risk. Great discoveries can be found by exploring new directions in interdisciplinary science. Moving into such new directions required going beyond my core knowledge and therefore involved serious Risk. I lived with that risk for 24 years and created a new field at the boundary between physics and chemistry. I was born a physicist. People even tell me that I look like a physicist. But we are what we have become --- with the award of the Nobel Prize in Chemistry in 2000, I became a Chemist.
What is next?
Advice to the Nobel Laureates of the Future.
Dealing with that risk is part of the thrill and satisfaction of living a life in science.
I will describe the discovery of ultrafast photoinduced electron
transfer as the scientific foundation for the creation of a technology for low cost “plastic” solar cells. This initial charge separation occurs at a time scale two orders of magnitude faster than the first step in photosynthesis in green plants.
We demonstrate by a series of transient absorption measurements that the Uncertainty Principle can enable ultrafast (<100 fs) charge transfer over distances of 10-20 nm in the nanoscopically textured material in bulk heterojunction (BHT) solar cells. Because the spatial extent of the initially photoexcitated wavefunction is determined by the Uncertainty Principle, not by the eigenfunctions of the Schrodinger equation describing the disordered nanostructured material, we expect the emergence of new physics in nanoscience.
I will focus on the details of the operating mechanism; the origin of the open circuit voltage (voc), the role of morphology on the charge separation and charge collection at the electrodes, the need for charge selective buffer layers and the origin of the limitations on the fill factor (FF). I will emphasize the importance of the competition between sweep-out and recombination and on studies of recombination mechanism in BHJ solar cells. Recent results on BHJ solar cells using small molecule donors (rather than polymers) will be briefly summarized.
Prof. Alan J. Heeger serves as Professor of Physics and Professor of Materials at the University of California, Santa Barbara and also heads a research group at the university’s Center for Polymers and Organic Solids. He was awarded the Nobel Prize in Chemistry (2000) for his pioneering research in and the co-founding of the field of semiconducting and metallic polymers; his research efforts continue to focus on the science and technology of semiconducting and metallic polymers. Contact: Department of Physics, University of California, Santa Barbara, CA 93106-9530; firstname.lastname@example.org. edu; www.cpos.ucsb.edu