NIST Study Proves Thermal Stability of Nanometer-Thick Films for Organic Electronics

A research team from the National Institute of Standards and Technology (NIST) has helped an international research team to verify the stability of an ultrathin membrane using near-edge X-ray absorption fine-structure spectroscopy (NEXAFS).

The ultrathin membrane developed by the international research team can be used as a key component for a new class of flexible, sterilizable organic electronics for use in medical applications. The team is headed by scientists from the University of Tokyo, with members from the Princeton University, Hiroshima University, the Japan Science and Technology Agency, the Max Planck Institute for Solid State Research and Nippon Kayaku, a Tokyo-based company.

The international research team has developed an innovative gate material that enables high-temperature sterilization of organic transistors, thus making them suitable for medical applications such as soft pacemakers and implantable devices. This gate material assembles itself into an ultrathin single layer of tightly packed linear molecules that assemble at a small angle to the surface. The team informed that this self-assembled monolayer (SAM)’s thickness can be down to 2 nm.

Structural measurements of SAM were performed at the NIST low-energy X-ray beam line located at the National Synchrotron Light Source in New York. Samples of the ultrathin film from prior and after heat treatment were tested on the NIST beamline utilizing NEXAFS technique to measure the thermal stability and molecular orientation of the film.

The NEXAFS technique is capable of detecting chemical bonds at the surface and in the interior of the sample. For example, it can show the disparity between a single carbon bond and a double carbon bond within a molecule. The NEXAFS measurements proved that the SAM ultrathin films were able to maintain their integrity and stability even at temperatures above 150°C.

K. Kuribara, H. Wang, N. Uchiyama, K. Fukuda, T. Yokota, U. Zschieschang, C. Jaye, D. Fischer, H. Klauk, T. Yamamoto, K. Takimiya, M. Ikeda, H. Kuwabara, T. Sekitani, Y-L. Loo and T. Someya. Organic transistors with high thermal stability for medical applications. Nature Communications. 3, 723. Mar. 6, 2012. doi:10.1038/ncomms1721

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