Optical properties of Afterglow Luminescent Particles (ALPs) in mechanoluminescence (ML) and mechanical quenching (MQ) have attracted great attention for diverse technological applications. Recently, a research team led by Professor Sei Kwang Hahn (MSE) and PhD candidate Seong-Jong Kim (MSE) successfully developed a device that implements this phenomenon. The new photonic display technology allows writing and erasure of messages, even underwater. The results of this research were recently published in the international academic journal Advanced Functional Materials.

  When ALPs gradually emit absorbed energy under external physical pressure, they exhibit unique characteristics of ML, where light is produced, and MQ, where light is diminished. Research on light displays utilizing these properties has been actively conducted. However, the exact mechanism has yet to be fully identified.

  In this study, the research team successfully analyzed the impact of recharging and trapped electrons on ML and MQ. They identified the mechanism of both phenomena. Based on these findings, they developed a light display patch capable of manifesting both phenomena. This patch combines ALPs with a very thin polymer material, Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), so the patch can be attached to the skin.

  With just a slight force from a fingertip, this display patch allows for writing and exposing the patch to ultraviolet rays reset the display patch like erasing a sketchbook. Moreover, the display demonstrated excellent moisture resistance, maintaining underwater performance.

  Prof. Hahn stated, “This display can be utilized as an alternative communication tool in situations where existing communication methods were restricted, such as in underwater environments with low light or high humidity. We anticipate its potential application as a wearable photonic display and phototherapy system for detecting changes in extreme environments.”

  Meanwhile, this study was supported by the Basic Science Research Program, the Bio and Medical Technology Development Program, and the National R & D Program of the National Research Foundation, funded by the Ministry of Science and ICT, Korea. This work was also supported by the Korea Medical Device Development Fund grant and POSCO HOLDINGS.