Color Change According to Carbon Dot Concentration... Demonstrating the Applicability of Optical Sensors

Demonstration of Concentration-Dependent Luminescence Properties of Carbon Dot
Proving Potential Applications in Sensing as a Luminescent Material

Image showing the change in luminescence characteristics of carbon dots exhibiting dual emission depending on concentration

[Asia Economy Reporter Junho Hwang] The luminescence mechanism of carbon dots, a next-generation luminescent material attracting attention as a replacement for quantum dot displays, has been unveiled by a domestic research team. On the 5th, the research team led by Dohyun Kim, a professor in the Department of Biological and Chemical Engineering at the Korea Advanced Institute of Science and Technology (KAIST), announced that they identified the mechanism behind the concentration-dependent luminescence characteristic changes of dual-emission carbon dots, a next-generation luminescent material. The related research findings were recently published in the international journal 'Physical Chemistry Chemical Physics.'

Luminescence Color Changes According to Carbon Dot Concentration

Graphs showing the existence of a critical concentration favorable for red emission and the effect of the dispersion of carbon dot particles in different solvents on the emission color.

Carbon dots are carbon-based luminescent materials with advantages such as abundant raw materials, low toxicity, and eco-friendliness. In particular, carbon dots can incorporate various types of luminescent sources internally.

The research team synthesized dual-emission carbon dots that emit two colors to observe changes in their characteristics. By synthesizing carbon dots that emit both blue and red light and observing the luminescence characteristic changes according to concentration, they confirmed that at a critical concentration, the particle-to-particle distance forms an optimal spacing for red luminescence. Around this concentration, blue luminescence intensifies, resulting in changes in the dual-emission characteristics of carbon dots depending on their concentration.

Based on this, the team conducted spectroscopic analysis to distinguish the two luminescent sources as surface functional groups and core bonding structures, respectively. Through this, they confirmed that the contribution of each luminescent source to the dual emission changes with concentration. Notably, the team also identified the principle that in the high concentration range, the dual-emission characteristics are controlled due to changes in the particle-to-particle distance between the two luminescent sources.

A New Perspective on Carbon Dot Luminescence

Dr. Yoo Hyojeong, KAIST PhD candidate (from left), Gwak Byeongeun, integrated master's and doctoral course, Professor Kim Dohyun

Additionally, the research team succeeded in implementing a white LED close to pure white by controlling the concentration of dual-emission carbon dots. They also demonstrated the application of pH sensing through color changes, proving that pH estimation is possible by observing the relative luminescence intensity changes of blue and red according to pH.

The research team evaluated, "This study once again proves the potential for carbon dots to be used as luminescent materials with advanced functionalities."

Yoo Hyojung, a doctoral student and first author, stated, "The interpretation that interactions between luminescent sources occur depending on the particle-to-particle distance of carbon dots, causing changes in luminescence characteristics according to concentration, was overlooked in previous studies. Along with the analysis of the dual-emission phenomenon, this research result presents a new perspective on elucidating the luminescence phenomenon of carbon dots."

This content was produced with the assistance of AI translation services.