Master the Surface and Interface: Pioneering Future-Oriented Organic Semiconductor Devices

MURATA Laboratory
Senior Lecturer：EGUCHI Keitaro

E-mail：
［Research areas］
Surface Physical Chemistry, Organic electronics
［Keywords］
Organic thin film, Operando measurement, Organic memory device, nanotechnology

Skills and background we are looking for in prospective students

Students who have majored in chemistry or physics or who have worked with vacuum equipment will find it easier to engage in research. However, as the saying goes, “What one likes, one will do well.” If you engage in research that interests you, you will quickly acquire specialized knowledge and skills.

What you can expect to learn in this laboratory

Students will be able to learn the basic concepts of molecular science and solid state physics through research on organic thin films. In addition, through experiments, students will understand the principles of operation of experimental equipment and experimental techniques, and students will learn how to operate them correctly and how to acquire and interpret experimental data correctly. Also, students can improve their technical writing skills, which are necessary for writing scientific papers and reports, and their presentation skills, which are necessary for academic presentations.

【Job category of graduates】 Semiconductor industry, electronics industry, Chemical company

Research outline

“The interface is the device.” is a phrase attributed to Nobel Prize winner in physics Herbert Kroemer. The interface between various materials can be a device with new functions. At the surfaces and interfaces where the environment is different from that of the bulk, new properties of materials that were hidden in the bulk properties may emerge. Our research field is such surfaces and interfaces. We are addressing the creation of functional devices that operate with new mechanisms by precisely designing interfacial materials, interfacial structures, and interfacial electronic states and the development of methods for measuring electronic states under device operating conditions.

Figure. Schematic diagram of the interaction between electric currents flowing through organic semiconductors and ionic liquids.

■ Development of functional organic semiconductor devices

We are developing devices with memory functionality by combining organic semiconductors and ionic liquids. We are trying to control the memory characteristics in 2-terminal devices and 3-terminal field-effect transistors.

■ Elucidation of the electronic structure of organic thin films under device operation conditions

We are developing measurement methods under the device operating environment to evaluate the structure and electronic states of molecular materials in electronic devices under operation. We will deepen our understanding of how electric currents flow through organic thin films by“observing” states that cannot be “observed” in general measurements. We will also clarify how the state of electrons in the inactive and active states of devices is related to device properties, leading to the improvement of device properties and the development of new devices.

Key publications

1. Keitaro Eguchi and Hideyuki Murata, “Evolution of the Ionization energy in Two- and Three-Dimensional Thin Films of Pentacene Grown on Silicon Oxide Surfaces”, The Journal of Physical Chemistry Letters 12, 9407-9412 (2021).
2. Keitaro Eguchi and Hideyuki Murata, “Electronic States of Pentacene Thin Films at Interfaces with Ionic-Liquid Layers Probed by Photoelectron Yield Spectroscopy”, The Journal of Physical Chemistry C 127, 14940-14948 (2023).
3. Keitaro Eguchi and Hideyuki Murata, “The ionization energy of α-sexithiophene and p-sexiphenyl in 2D and 3D thin films grown on silicon oxide surfaces”, Physical Chemistry Chemical Physics 26, 8687-8694 (2024).

Equipment

Ultra-high vacuum system / high-vacuum system, photoelectron yield spectrometer / Inverse photoelectron spectrometer / X-ray photoelectron spectrometer, atomic force microscope, X-ray diffraction meter, electrometer, UV-VIS-NIR spectrometer