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Summer 2011 Blog - Gloria Lee

Gloria Lee is spending her Cal Energy Corps internship at the Chinese University of Hong Kong.

June 28, 2011

My first day in Hong Kong was tough. The moment I stepped out of the airport, I was assaulted by the 93ºF heat and 82% humidity. My second day wasn’t much better. I managed to amass 55 mosquito bites on my legs in one night. The past couple of weeks, however, have been looking up! The weather has cooled a bit (thank you, Tropical Depression Hyma), mosquito repellent has been bought, and I can now finally focus on saving the world, one organic solar cell at a time.

A view of the Chinese University of Hong Kong campus. I worked in the 
multi-colored building, which housed most of the chemistry and physics 
labs and is affectionately known as the "High Danger Tower." 
(photo courtesy of Bayon Lee)

The purpose of my internship at the Chinese University of Hong Kong is to learn about and try to improve the efficiency of organic solar cells. People are interested in these polymer-based solar cells because, unlike traditional silicon models, many different polymer molecules can be easily created and then “printed” in very thin films onto flexible conducting surfaces, making them much more cost and resource efficient, as well as easier to integrate into items such as clothing or curved building exteriors. Current obstacles to their commercialization, however, include low efficiency (less than 10% compared to 28% for crystalline silicon) and poor stability in air (polymer + oxygen = very bad conductor of electricity). In order to increase stability, my current research involves applying a metal oxide layer above the polymer layer, which seals off the polymers from some of the oxygen in the air and adds another charge transporting layer to the solar cell. We’re then fine-tuning this layer to further increase the solar cell’s efficiency.

The professors and graduate students here are incredibly nice and welcoming. They’ve taken me out to dinner and invited me to play badminton with them. When the graduate student I was working under became buried in his thesis, another student with similar experiments let me help him and showed me how to operate all of the equipment and test the solar cells. The students here also work extremely hard, memorizing speeches so they can give thesis defenses in English, traveling to other universities a couple times a week to attend seminars, sometimes conducting experiments until four in the morning because that’s the only time the equipment is free. I myself will be going into lab tomorrow bright and early at eight to make a second batch of solar cells that hopefully demonstrate greater efficiency than the woefully deficient samples from last Friday’s experiments. Wish me luck!


August 25, 2011

Some images of my organic solar cells. 
In the top right picture, you can see the 
bluish squares of ITO (indium tin oxide), 
a transparent conducting surface that 
acts as the anode of the solar cell. The 
red square is P3HT:PCBM, a blend of 
conducting polymers that forms the active 
layer, and the silvery stripes on top are 
the aluminum cathodes.

Last time I left off hoping for nice experiment results. Well, that batch of solar cells was no good. Neither was the next batch. Nor the one after that. But after several weeks of solid research, where we considered and tweaked every production process and measurement technique, the student I was working with and I managed to create solar cells that consistently operated at efficiencies 50% greater than what he had been able to achieve in the past. This was a breakthrough that he had been working towards for months, and I felt extremely happy to have been able to help him reach a milestone in his work. For me as well, this experience of focusing so exclusively on research all summer was a major stepping stone. Between spending days at a time in lab, reading numerous textbooks and papers (even proofreading my graduate student’s thesis- all 150 pages of it!), and attending relevant talks, I learned to take ownership of my project and became much more comfortable in a lab environment. I think this newfound confidence will help me in any future research endeavors, because I won’t be as afraid of making mistakes or trying to figure out how unfamiliar systems work.

As I traveled around Hong Kong this summer, I was able to meet and interact with many different people. When they inevitably asked what I was doing halfway across the world from home, I was always struck by how interested they were in energy research. A research assistant in my lab believed that developing countries would be ideal places to implement new energy infrastructure and policies. A French patisserie owner complimented my friend and me on the good work we were doing developing such an important technology for the future. A middle school science teacher asked if I thought solar cells could become the main source of the world’s energy, because where she teaches in Texas, people are still very much attached to oil, and “alternative” energy sources are generally met with skepticism. These conversations opened my eyes to how deeply people from all walks of life are concerned about energy and the impact that decisions about how energy is harnessed and used will have on their lives. I am so grateful for the opportunity to work on such an important and interesting problem. It’s given me a lot to think about, and I can’t wait to further explore this new energy frontier!

Here are all the people I worked with this summer! I can't thank them enough for being such amazing friends
and mentors. The graduate student I worked under, Ming Dong Wang, is second from the left in the second
row, and my professors, J.B. Xu and Ni Zhao, are third and fourth from the left in the first row, respectively.

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