Development of light-emitting film with sensitivity to airborne materials

(Nanowerk News) The National Institute for Materials Science (NIMS) and the Japan Science and Technology Agency (JST) developed an organic-metallic hybrid polymer which displays a vapoluminescent property in response to airborne materials. This result was obtained in research by Dr. Masayoshi Higuchi, Group Leader of the Electronic Functional Materials Group, Polymer Materials Unit, Advanced Key Technologies Division, and Dr. Takashi Sato, a Postdoctoral Researcher in the same group.
Large expectations are placed on materials that emit light in response to external stimuli such as heat, electricity, etc. in applications as display devices and light-emitting sensors with excellent visual human interface properties, and practical application of some materials has begun. For example, materials that emit light when a voltage is applied have already been commercialized as organic EL displays. Materials that display luminescence when the vapor of a substance is detected are called vapoluminescent materials. However, few reports have been published on these materials, and no research envisioning practical applications such as display devices, etc. has been done.
In this work, the NIMS researchers realized a vapoluminescent polymer film which is capable of detecting acidic and alkaline gases using a newly-developed organic-metallic hybrid polymer.
The developed polymer is an organic-metallic hybrid polymer in which organic molecules and ions of the rare earth metal europium form a chainlike structure. Because the polymer itself is amorphous, it can be easily fabricated as a film, for example, by spin coating, etc. and it displays red light emission originating from the europium ion complex. In this research, it was found that the polymer film displays switchable vapoluminescence triggered by acid-base vapors, in which light emission is extinguished by contact with acidic vapors, and then resumes on subsequent contact with an alkaline vapor. The NIMS researchers also succeeded in printing characters that are cyclically displayed and not displayed in response to these vapors. As a result of this invention, great progress is expected in the future in research toward light-emitting sensors that detect and identify substances in the air, and their application to displays.
These research results were obtained as part of the research topic "Electrochromic Color-E-Paper" (Research Representative: Masayoshi Higuchi) in the Research Area "Creation of Nanosystems with Novel Functions through Process Integration" (Research Supervisor: Jun'ichi Sone) of the CREST (Core Research for Evolutional Science and Technology) Program of the Japan Science and Technology Agency (JST). This achievement was announced in the bulletin Chemical Communications of the Royal Society of Chemistry dated May 21 ("A vapoluminescent Eu-based metallo-supramolecular polymer").
Source: NIMS