In a groundbreaking development that could revolutionize the optoelectronics industry, researchers have demonstrated a novel technique to enhance the photoresponse of WSe2/MoS2 heterobilayer devices through programmable local nanostrain engineering. This innovation, led by Shunyu Chang from the Robotics Institute at Harbin Institute of Technology in China, opens new avenues for wearable and flexible devices, with significant implications for the energy sector.
The challenge of achieving precise, controllable, and permanent nanostrains in two-dimensional materials (2DMs) has long been a hurdle in the industry. Chang and his team drew inspiration from an unlikely source—the swelling caused by mosquito bites—to develop a technique using heated nanotip atomic force microscopy for thermomechanical nanoindentation. This method allows for accurate positioning of localized nanostrain and regulation of the bandgap in WSe2/MoS2 heterobilayers transferred onto a flexible polymethyl methacrylate film.
“The magnitude of strain in the WSe2/MoS2 heterobilayer can be controlled by adjusting the parameters of nanoindentation,” Chang explained. “This leads to a spatially modulated average strain of up to 2.5% on the ring-shaped expansion structure (RES).” The local bandgap of the heterobilayer is spatially regulated through three distinct regions, with the RES exhibiting the largest extent of bandgap modulation, accompanied by a significant change of ∼12 meV.
The implications for the energy sector are profound. The nanostrain significantly enhances the photoresponse speed of the photodetector device. Under illumination from a 405 nm wavelength-laser, the rise time and fall time are reduced by 75% and 87.52%, respectively, compared to the device without strain. Similarly, under illumination from a 532 nm wavelength-laser, the rise time and fall time are reduced by 66.67% and 80.60%, respectively.
“This method serves as a versatile way for improving the photoresponse of optoelectronic devices based on 2DMs,” Chang noted. The research, published in the International Journal of Extreme Manufacturing (translated as “International Journal of Extreme Manufacturing”), represents a significant step forward in the field of nanotechnology and optoelectronics.
The potential applications of this technology are vast, particularly in the development of wearable and flexible devices. The ability to precisely control and modulate the bandgap and photoresponse of 2DMs could lead to more efficient and versatile optoelectronic devices, with implications for solar energy harvesting, photodetectors, and other energy-related technologies.
As the industry continues to explore the potential of 2DMs, this research provides a promising path forward. By leveraging the unique properties of WSe2/MoS2 heterobilayers and the innovative technique of thermomechanical nanoindentation, researchers can push the boundaries of what is possible in optoelectronics and beyond. The work of Chang and his team not only advances our understanding of nanostrain engineering but also paves the way for future developments in the field.