Li-Fi technology offers enhanced security and speeds 100 times faster than Wi-Fi

Li-Fi (Light Fidelity) is a wireless communication technology that utilizes the visible light spectrum (400–800 THz), similar to LED light, offering speeds up to 100 times faster than existing Wi-Fi (up to 224 Gbps). While it has fewer limitations in available frequency allocation and less radio interference, it is relatively vulnerable to security breaches as anyone can access it.

Korean researchers have now proposed a new Li-Fi platform that overcomes the limitations of conventional optical communication devices and can simultaneously enhance both transmission speed and security.

Professor Himchan Cho’s research team from the Department of Materials Science and Engineering, in collaboration with Dr. Kyung-geun Lim of the Korea Research Institute of Standards and Science under the National Research Council of Science & Technology, has developed on-device encryption optical communication device technology for the utilization of Li-Fi, which is attracting attention as a next-generation ultra-high-speed data communication.

Professor Cho’s team created high-efficiency light-emitting triode devices using eco-friendly quantum dots (low-toxicity and sustainable materials). The device developed by the research team is a mechanism that generates light using an electric field. Specifically, the electric field is concentrated in “tiny holes (pinholes) in the permeable electrode” and transmitted beyond the electrode. This device utilizes this principle to simultaneously process two input data streams.

Using this principle, the research team developed a technology called “on-device encryption optical transmitter.” The core of this technology is that the device itself converts information into light and simultaneously encrypts it. This means that enhanced security data transmission is possible without the need for complex, separate equipment. The study is published in the journal Advanced Materials.

External quantum efficiency (EQE) is an indicator of how efficiently electricity is converted into light, with a general commercialization standard of about 20%. The newly developed device recorded an EQE of 17.4%, and its luminance was 29,000 nit, significantly exceeding the maximum brightness of a smartphone OLED screen, which is 2,000 nit, demonstrating a brightness more than 10 times higher.

Furthermore, to more accurately understand how this device converts information into light, the research team used a method called transient electroluminescence analysis. They analyzed the light-emitting characteristics generated by the device when voltage was instantaneously applied for very short durations.

Through this analysis, they investigated the movement of charges within the device at hundreds of nanoseconds, elucidating the operating mechanism of dual-channel optical modulation implemented within a single device.

Professor Himchan Cho of KAIST stated, “This research overcomes the limitations of existing optical communication devices and proposes a new communication platform that can both increase transmission speed and enhance security.

“This technology, which strengthens security without additional equipment and simultaneously enables encryption and transmission, can be widely applied in various fields where security is crucial in the future.”