Thats right, molecules can blink.

Hello! My name is Alana Ogata and I am excited to be participating in summer research this year in the Chemistry department. I am a rising junior from Falls Church, Viriginia, and am doing research under the lovely Professor Wustholz.  I had never considered research until this school year, and to be honest didn’t realize William and Mary offered it, and even then I was too intimidated by big crazy words, and images and figures that looked more like abstract art to me. Everything just sounded and looked like a completely different language. It still does, but ever since I joined the lab I have learned so much,  its not like dry, classroom, textbook learning. So I cannot wait to have time devoted to research without the hastle of classes ontop.

My research is in analyzing the efficieny of dye-sensitized solar cells using single molecule spectroscopy. The efficiency of what using what? That was what I first thought when I heard this statement, and you might be thinking the same thing; heres some background information to help you out. In general, this research is linked to solar energy and how sunlight is converted to electricity. So first, solar cells; these are what solar panels are made of and they contain an electrolyte and semi-conductor electrode where electrons are released due to excitation from sunlight. These electrons then get caught in a current, and voila, you have electrcity. Secondly; dye-sensitized. Dyes are pretty colors becuase they flouresce, meaning they are releasing electrons.  Putting a layer of dye on a solar cell can provide even more photoexcitation of electrons, meaning more electricity. The problem is, sometimes these electrons do not reach the semi conductor and simply go back to the dye, aka back electron transfer, meaning no electricity. This has been hypothesized as the reason behind the inefficiency of solar cells.

Our research is focused on determing the mechanism behind back electron transfer; why it happens, how often it happens, and what affects it. So finally we get to single molecule spectroscopy. We have been analyzing dye molecules by hitting them with a laser through a confocal microscope to excite them and measure their flourescence. When the molecules are flourescing, the electrons are going back and forth between an excited and ground state, when they stop flourescing they are “dead” and have lost their electrons. When we focus in on one, yes thats right, one single molecule, we record its blinking. Who knew molecules could blink? Well blinking is when molecules go back forth between flourescing and dead states. These blinking dynamics are key to understanding back electron transfer and is the focus in our research. We have been collecting blinking dynamics of single molecules and analyzing them to try and understand an overall pattern. During the school year we have been collecting blinking dynamics of a rhodamine dye on glass slides. For the summer, we are now focusing on the same rhodamine dye on a semi-conductor, TiO2. The use of TiO2 is to simulate the actual structure of a solar cell. Once we collect enough blinking data, we will work on creating a distribution curve of on and off states and begin experimenting with factors such as orientation, temperature, and atmospheric conditions. In the end, we would like to better understand the ideal environment where the dye molecules have minimum back electron transfer and maximum electricity production.