Inspiring students’ creativity
Yang values his students’ ideas and encourages them to be bold in their thinking. For example, while drinking coffee, a student remembered that caffeine has a boiling point around 300°C, a level far above the operating temperature of solar cells, and wondered if it might increase the stability of solar cell materials. With Yang’s encouragement, the team painted a chemical solution containing caffeine onto conductive glass to form thin-film perovskite solar cells. After thermally aging them for two months, the team found that the caffeine-containing cells retained 86% of their initial PCE. Meanwhile, the control group cells without caffeine retained only 60% of their initial PCE, proving that caffeine really did increase the stability of perovskite solar cells.
When investigating the reason for this result, the team discovered that caffeine molecules help to stabilize the solar cells’ crystal structure by forming “molecular locks” with ions in the cells. But the team’s research work didn’t stop there. They went on to investigate whether molecules such as theophylline (found in tea) and theobromine (found in chocolate) had a similar effect. “They also tested ginseng. It was kind of fun,” says a smiling Yang. In recent years, scientists have been actively seeking breakthroughs aimed at increasing the thermal stability of perovskite solar cells. The team’s research has moved such cells much closer to commercial development.
Yang says, “When we value students’ talents, educate them, and stimulate their potential, they are very likely to excel. When we treat students as labor to be exploited, they only become workhorses.” Yang patiently guides his students towards research they personally find interesting, and then gives them the freedom to choose topics for themselves. When they pick topics they love, they get into their research for the long haul. As a result, scientists trained in his lab can now be found in universities and major corporations all over the world.
Yang has accumulated numerous accolades over the many decades of his research career, including fellowships in the Royal Society of Chemistry and the Materials Research Society. He has led by example, inspiring others to explore the limitless possibilities of optoelectronics and training up new scientists with the knowledge and skills to change the world.
Yang’s lab makes small perovskite photovoltaic cells to test the performance of different materials and components.
Yang’s students have furthered his influence by going on to work at world-class universities and corporations. In the photo, his students send him birthday wishes.
Yang and his students are continuing their explorations of solar power, leading the rest of us to a brighter future. (photo by Lin Min-hsuan)