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- by  Yasi Bahmanabadi

Converting tropical plant dyes—from flowers, leaves and fruit peels—into solar energy? It’s an eco-conscious revelation, and it’s happening in the New College science labs.

The “Natural Dye-Sensitized Solar Cells Project” is a “flower power” experiment that involves New College Assistant Professor of Bioorganic Chemistry Lin Jiang, Ph.D. and student intern Cheyenne Nelson. The two collaborated intensely from May to August on the environmentally-friendly research, which the Community Foundation of Sarasota County funded, and their work has resulted in an exciting outcome.

“This is a highly interdisciplinary project, and it’s a perfect fit for students who are interested in environmental studies, chemistry, biology, botany and nanomaterials,” Jiang said. “Many students are interested in environmental discovery, but synergistically combining environmental chemistry with a daily life component is a key factor to attract the student’s interest. From the project, the student can not only learn basic lab skills but also learn to rethink biowaste management and renewable energy.”

As the public grows more concerned about climate change, the need for sustainable and renewable energy increases, and scientists are busy finding greener options. Aiming to use clean, free, inexhaustible solar energy for both solar cells and biowaste management, Jiang and Nelson conducted an experiment to investigate the potential of colorful natural dyes to harvest the visible energy in solar light. What Jiang and Nelson found was a unique, efficient alternative to other commonly used dyes.

“My student, Cheyenne, is so passionate about this project. She started asking her mom and neighbors for different flowers and leave supplies. That’s one major reason we ended with 51 different screening natural dyes,” Jiang said. “It’s always fun to teach students new knowledge or skills, but it’s definitely more interesting and rewarding to see the student start coming up with her own ideas and designing/rerouting the project.”

And the project was significant, considering the kinds of dyes typically used elsewhere in this research have not been ideal. According to Jiang, TiO2-based dye-sensitized solar cells (DSSCs) have shown great potential as a low-cost green technology, but they require colorful dyes to harvest the visible light energy in the solar light. The currently-used Ruthenium dye N3 and other organic dyes have heavy metals that are not environmentally sustainable.

On the other hand, tropical plant dyes (especially those from biowastes such as fruit peels, flowers and leaves) are proposed to serve as light-harvesting materials adsorbed on modified TiO2 nanomaterials to increase the efficiency of the solar cells.

“The screening’s outcome was considerably promising,” Jiang said. “In this project, we established a systematic and feasible screening method for the biowaste pigments to increase the solar energy conversion efficiency. The expected results will not only increase the DSSCs’ efficiency using environmentally-friendly natural pigments, but also provide directions to reduce and reuse the biowaste. From the 51 different biowaste pigments, three of them showed excellent solar energy conversion efficiency (Delonix regia, orchid and rose leaves).”

The electron produced in the solar cell system can also be used to photodegrade the emerging environmental pollutants, such as pharmaceuticals and personal care products (PPCPs), Jiang said. In other words, the study (if successful with food waste dyes) can provide the treatment of food waste and PPCPs in one process.

The experience also gave Nelson an opportunity to conduct in-depth, graduate-level research as an undergraduate—and to work hand-in-hand with her professor and mentor at New College. The project was just one example of the many ways students and faculty are addressing the global energy crisis, and offering sustainable solutions to the planet’s greatest problems.

Watch one of Jiang’s past research students, Hunter Sullivan, convert simulated sunlight into energy that can power propellers:

Yasi Bahmanabadi is an intern in the Office of Communications & Marketing.