Have you ever shuddered at the tinny quality of light-emitting diodes (LEDs)? Despite their harsh and unflattering glare, you likely nevertheless screw them into your lamps because you know they last a lot longer and use far less energy than conventional incandescent bulbs and fluorescent tubes. If Peifen Zhu has her way, however, one day we might all be happily basking in the glow of LED lamplight that is calm, cool and doesn’t make your skin crawl.
Zhu is an assistant professor of physics and engineering physics at The University of Tulsa. Earlier this year, the National Science Foundation (NSF) awarded to Zhu a five-year Faculty Early Career Development (CAREER) grant to support her investigation of lead-free pseudohalide/halide perovskites for next-generation white LEDs. Metal halide perovskites, she explained, are promising semiconductor materials for potential application in optoelectronic devices – that is, devices that either emit or detect light.
“LED technology based on metal halide perovskites is still in its early stage,” noted Zhu. “Two of the main barriers to its practical applications are problems with stability and the common inclusion of lead. Continued innovation and breakthroughs are needed to achieve LED’s full potential.”
The objective of Zhu’s research on solid-state lighting technology is to develop highly efficient, environmentally friendly luminescent materials by using earth-abundant elements (e.g., carbon, nitrogen, oxygen) and low-cost, large-scale methods to replace the yellow phosphors that make conventional LEDs cast such unpleasant light. “My hope,” Zhu said, “is that this theoretical and experimental work will, ultimately, boost the widespread adoption of white LEDs that have superior color quality and, thereby, reduce our energy consumption.”
Training future scientists
Built into Zhu’s research program is educational training for undergraduate and graduate TU students in physics, material science, electrical engineering and mechanical engineering. Currently, four graduate students and one undergraduate student are collaborating with Zhu her Lab for Emerging Materials and Devices. In fact, Zhu and her students have been working on the LED project since before the NSF grant. The team has been nothing if not prolific, and their findings have been published in several prestigious journals, including Advanced Optical Materials, ACS Applied Materials & Interfaces, Nano Research, Journal of Colloid and Interface Science, Optics Express and Journal of Physical Chemistry.
“I have been working with Professor Zhu since June 2017,” said Gopi Adhikari, a doctoral candidate in physics at TU. “Dr. Zhu has been instrumental in my development as a scientist. She is dynamic, enthusiastic and always ready to help students without hesitation as both a teacher and research mentor. Two of the things that stand out for me particularly strongly are Dr. Zhu’s respect for each student and her passion for their success. I have learned so much from her and I am grateful to be involved in the research she is carrying out.”
One of the novel aspects of Zhu’s program is that it will involve students from local middle and secondary schools. “I plan to invite budding scientists to conduct experimental work at TU during the summer,” noted Zhu, “thereby giving them hands-on experience in photonic research methodologies before they ever set foot at university.”
In fact, Zhu has some history mentoring such students. During the summers of 2017 and 2018, a high school student named William Wang undertook experimental work in her lab. Not only did this lead to scholarly publications and presentations, but Wang also won several national and international competitions, including the Google Science Fair. Today, he is an undergraduate student at Stanford University.
Does research in the most fundamental of the sciences interest you? If so, learn more about the pathways and opportunities offered by TU’s Department of Physics and Engineering Physics.