Associate Professor, Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Japan

Biography: JIchiro Imae was born in Himeji (Hyogo, Japan) in 1969. He received the Bachelor, Master and Doctor degrees (Engineering) from Osaka University (Osaka, Japan) in 1992, 1994, and 1997, respectively (supervised by Prof. Yasuhiko Shirota). During his doctor course, he worked as a Research Fellow of Japan Society for the Promotion of Science (JSPS) from 1994 to 1997. In 1997, he joined with Japan Advanced Institute of Science and Technology (JAIST) (Ishikawa, Japan) as a Research Associate (Assistant Professor) and collaborated with Prof. Yusuke Kawakami.

Since 2006, he is an Associate Professor of Hiroshima University, Hiroshima, Japan. He is a member of the American Chemical Society (ACS), the Chemical Society of Japan (CSJ), the Society for Polymer Science, Japan (SPSJ), and other several societies. He is mainly interested in the development of novel photo-and electroactive materials based on organic materials and organic-inorganic hybrid materials and their application to thermoelectrics, photovoltaics and displays.

He received the "Presentation Award" from the Chemical Society of Japan in 2005, "Award for Encouragement of Research in Polymer Science" from the Society for Polymer Science, Japan in 2005, "Academic Research Award" from the Hiroshima Bank in 2012, "MMS Award" from the TANAKA Holdings in 2013, and "Education Award" from Hiroshima University in 2015.

Speech Title: Thermoelectric Properties of Regioregular Poly(3-hexylthiophene) Correlated with Doping Level

Aims: Since the pioneering works of thermoelectric (TE) materials based on the conducting polymers were reported at the end of 20 centuries, several types of conducting polymers have been applied to the TE materials due to their advantages of light weight, flexibility, low cost, and low toxicity compared over the inorganic materials. The performance of a TE material is represented by a dimensionless figure-of-merit (ZT) or by a power factor (PF) defined, respectively, by ZT = σS 2 T/κ or PF =σS 2 , where σ is the electrical conductivity, S is the Seebeck coefficient, T is the absolute temperature, and κ is the thermal conductivity. While charge transport mechanisms of conducting polymers have been intensively studied for the last few decades, Seebeck effects of conducing polymers are not well-understood because of their short research history as TE materials. In this paper, we report a correlation between TE properties, S and σ, of regioregular poly(3-hexylthiophene) (P3HT, Fig. 1) and doping level evaluated by a potential-step chronocoulometry (PSC).


Methods: The doping levels of P3HT were measured by the three-electrode system with P3HT-covered Pt-foil, Pt wire and Ag/Ag + in the acetonitrile solution, using a potentiostat/galvanostat and a coulometer.

Results: With increasing the doping levels, the electrical conductivities increased while the Seebeck coefficients decreased, which showed the typical trade-off relation. Interestingly, the log-log plot of Seebeck coefficients against doping levels showed a good linearity, whose slope value was around -1.

Conclusions: We have estimated the doping levels of electrochemically- and chemically-oxidized P3HT by the PSC method, and found for the first time that the double logarithmic plots of Seebeck coefficient and doping level fit a straight line with a slope of unity.