Advanced-materials expert Saien Xie has joined the Princeton faculty as an assistant professor of electrical and computer engineering and the Princeton Institute of Materials, adding new breadth in experimentation with thin-film technologies.
Xie specializes in creating substances that are at once hard and soft. These crystalline thin films form the basis for optical, electronic and optoelectronic devices. Xie is most interested in two-dimensional layered materials — only a few atoms thick — with tunable properties that can do the work of traditional, rigid semiconductors but also bend and deform in ways that meet modern demands. In particular, Xie works with a class of materials called transition metal chalcogenides, which possess novel electronic and optical properties.
His research focuses not only on the development of these materials and the discovery of their electronic and optical properties but also on how well they might translate to successive generations of functional devices. "I want to push materials to work on a technologically relevant scale," Xie said.
To do that, he aims to collaborate widely across the Princeton campus and cultivate interdisciplinary teams that can study both the theoretical underpinnings of these ultra-thin materials and their functionality in real systems. In addition to working with a swath of ECE and PRISM students and colleagues, he will connect with researchers from various departments including physics, chemistry, mechanical and aerospace engineering.
Xie's penchant for tinkering began at an early age. Growing up, surrounded by a culture that was rich in science and technology, he became fascinated with small machines of all kinds. "My passion for building stuff has been a driving force," he said.
He turned that passion into a career when he entered Tsinghua University in Beijing, where he distinguished himself in the study of math and physics. As a graduate student at Cornell University, he won several awards for his research on atomically thin materials, publishing influential papers in the journals Science and Nature.
In 2018 he was named a postdoctoral fellow at the Kavli Institute at Cornell for Nanoscale Science, where he mentored a dozen student researchers and developed an articulated approach to teaching. "One of the most satisfying parts of my graduate career was being a TA and having the students reach their 'A ha!' moments. This really makes me happy." He believes a mentor's job is to lead students from their first encounters with a problem through to developing their skills to identify and solve problems. For Xie, the key lies in motivation, and motivating students starts with creating an active and inclusive learning environment.
"I want to relate the scientific concepts to the students' daily lives," he said, "so they can have a more concrete grasp of this knowledge and understand that it's actually useful rather than just some equations or some words in a book."