Researchers from the University of Illinois at Urbana-Champaign have demonstrated a new approach to modifying the light absorption and stretchability of atomically thin two-dimensional (2D) materials by surface topographic engineering using only mechanical strain.
"We achieved more than an order-of-magnitude enhancement of the optical extinction via the buckled 3D structure, which led to an approximately 400% enhancement in photoresponsivity,” stated Pilgyu Kang, a postdoctoral research associate and first author of the paper, “Crumpled Graphene Photodetector with Enhanced, Strain-tunable and Wavelength-selective Photoresponsivity,” appearing in the journal, Advanced Materials. “The new strain-tunable photoresponsivity resulted in a 100% modulation in photoresponsivity with a 200% applied strain. By integrating colloidal photonic crystal—a strain-tunable optomechanical filter—with the stretchable graphene photodetector, we also demonstrated a unique strain-tunable wavelength selectivity.”
“This work demonstrates a robust approach for stretchable and flexible graphene photodetector devices,” SungWoo Nam, an assistant professor of mechanical science and engineering added. “We are the first to report a stretchable photodetector with stretching capability to 200% of its original length and no limit on detection wavelength. Furthermore, our approach to enhancing photoabsorption by crumpled structures can be applied not only to graphene, but also to other emerging 2D materials.”