Lab research
Lab Research on Organic Solar Cells
Renewable energy is the way to a cleaner planet. During the summer of 2022, I interned in the laboratory of Dr. Wei You, Chair of the Department of Chemistry at UNC-Chapel Hill. There I performed research on organic solar cells - I used mini versions of solar panels that can be produced in a laboratory to determine their efficiency with respect to current, voltage, and power, with a specific focus on using organic polymers and chemicals to create sustainable technology.
My Research with ZnO
In the laboratory, I began by researching and reading papers about the kind of chemistry I would be working on. The main chemical I was working with was zinc oxide (ZnO) - a chemical that forms the active layer in the solar cell, allowing the electrons to be transported to the bottom plate. First, I found the best concentration of ZnO for light absorbance, which was 8% for the thickness I was using, which we had determined to be best. Second, I tested "doping" or mixing the ZnO with other chemicals to improve its performance. Using methyl cyanide and NDMBI, I spin- coated these chemicals onto the ZnO layer and annealed them at various temperatures. The first batch I made was inconsistent, so the process was repeated a couple more times. The new batch created a trend where when the annealing time increased, the absorbance of the sample increased as well. Next, I placed the samples in an X-ray diffraction machine and compared my test batch with other ZnO samples. After using the doping method to improve the absorbance, I tested the sol-gel method, which produced similar results. I then tested the role of oxidation, which overall increased absorbance.
Expanding on ZnO
After working with ZnO, I began using aluminum zinc oxide (AZO) which integrated a doping chemical, aluminum, directly into the solution. First, I tested for the optimal concentration and thickness as I did with ZnO originally. Next, I introduced the same doping process I had used previously to the AZO, which improved the light absorbance even more. For most of the experiments, I had been working with ZnO as one layer, but I then started using indium titanium oxide (ITO) as a base layer. This helped with overall efficiency, especially when doped. I had been using absorbance to compare the samples, but now after finding the best combination, I could also test the electric conductivity of the samples. Using the voltage and current values from the now electrode-attached samples, I calculated the resistance and conductivity of the different samples. Of the many experiments I tested, I found that longer annealing time, doping, an ITO base layer, and 150 mm thickness produced the best results in terms of highest efficiency and conductivity of the solar cells.
Sharing my knowledge
After working hands-on with solar technology, I decided to continue learning about this topic and sharing my knowledge about the future of this technology. In April 2023, I published a peer-reviewed paper in the Journal of High School Science about the different and evolving generations of solar cells. I discussed what solar cells are and how they work, the four generations of solar cells created thus far, and the problems and possibilities associated with their future. I also created figures and diagrams to explain the four generations of solar cells and researched many papers about the topic.
FINAL_An Exploration into ZnO.pptxIf you're interested in learning more about solar cell research, check out Dr. You's website at https://www.weiyougroup.org/