A team has created printable, highly effective light-emitting metasurfaces.
In relationships, sharing closer spaces naturally deepens the connection as bonds form and strengthen through increasing shared memories. This principle applies not only to human interactions but also to engineering. An interesting study was recently published showing the use of quantum dots to make metasurfaces, allowing two objects to coexist in the same space. Professor Junsuk Rho from the Department of Mechanical Engineering, the Department of Chemical Engineering, and the Department of ElecElectrical Engineering, PhD candidates Minsu Jeong, Byoungsu Ko, and Jaekyung Kim from the Department of Mechanical Engineering, and Chunghwan Jung, a PhD candidate, from the Department of Chemical Engineering at Pohang University of Science and Technology (POSTECH) utilized Nanoimprint Lithography (NIL) to create metasurfaces embedded with quantum dots, improving their luminescence efficiency. Their study was recently featured in the online edition of Nano Letters.
NIL, a technique for producing optical metasurfaces, makes use of patterned stamps to efficiently transfer intricate patterns at the nanometer (nm) scale. This approach offersLaser processing has cost benefits compared to electron beam lithography and other methods, and it also allows for the production of metasurfaces using materials that are not typically available in traditional processes.
Metasurfaces have recently been heavily researched for their capacity to manipulate the polarization and emission direction of light from quantum dots. Quantum dots are tiny semiconductor particles that efficiently emit light at specific wavelengths, making them crucial for applications like QLEDs and quantum computing. However, traditional processes are unable to incorporate quantum dots.
Research in the field of metasurfaces has often focused on creating metasurfaces and quantum dots separately and then combining them, leading to limitations in controlling the luminescence of the quantum dots. However, in this study, researchers integrated quantum dots with titanium dioxide (TiO2), a material used in the NIL process, to form a metasurface. Unlike traditional methods, this approach involves embedding the quantum dots directly within the metasurface during its creation, rather than fabricating them separately and then combining them. The resulting metasurface effectively enhances the proportion of light emitted by the quantum dots.
The utilization of photons produced by the quantum dots that interact with the resonance mode of the metasurface has been improved, allowing for better control over the specific direction of light emitted from the quantum dots compared to previous methods.
Experiments showed that the greater the number of photons emitted from the quantum dots, which were linked to the resonant modes of the metasurface, the higher the luminescence efficiency. The team’s metasurface achieved up to 25 times greater luminescence efficiency compared to a simple coating of quantum dots.
Professor Junsuk Rho of POSTECH, who led the research, said, “The utilization of luminescence-controlled metasurfaces will enable improved and more accurate displays and biosensing technology. Further studies will help regulate luminescence more efficiently, resulting in advancements in nano-optical sensors, optoelectronic devices, and quantum dot displays.” The research received support from POSCO N.EX.T IMPACT, the Samsung Future Technology Incubation Program, and the Mid-Career Researcher Program of the Ministry of Science and ICT and the National Research Foundation of Korea.
