Organic electronic devices such as thin-film transistors (TFTs) and light-emitting diodes (LEDs), as well as the development of high-performance materials, have attracted considerable research interest. Recent trend in the research on organic devices is focused on the fabrication of the practical ones based on easy and low-cost process. However, understanding of the operation mechanism in the OFET is still insufficient. The importance of fundamental research is being recognized to improve the performance of organic devices. Since current flowing in the materials is expressed as J=enmE, evaluation of each parameters, i.e., carrier density (en), mobility (m) and electric field (E), is of great importance to discuss the device operation from a fundamental point of view. However, these contributions cannot be discriminated easily by the simple electrical measurements.

On the basis of electric field induced optical second harmonic generation (EFISHG), we have developed a procedure for evaluating electric field distribution in the organic devices [1,2] and a time-resolved measurement (TRM-SHG) for visualizing a carrier motion in organic thin film transistors [3]. Since carrier is the source of the electric field, carrier motion can be traced by following the time-evolution of the electric field distribution in the devices. Direct observation of carrier enables us to evaluate intrinsic carrier mobility in the devices. Thus, the TRM-SHG measurement is a powerful tool to evaluate the carrier dynamics in the OFET [4,5].Recently, we successfully visualize an anisotropic carrier transport in single crystalline grains of TIPS (6,13-Bis(triisopropylsilylethynyl)) pentacene FETs by using thisTRM-SHG measurement.In the presentation, I would like to briefly introduce and discuss details of this TRM-SHG measurement, and show some recent results regarding such anisotropic carrier transport in the organic semiconductor materials.

 

[1] T. Manaka, E. Lim, R. Tamura, D. Yamada, and M.Iwamoto, Appl. Phys. Lett., 89 (2006) 072113.

[2] T. Manaka, M. Nakao, D. Yamada, E. Lim, and M. Iwamoto, Opt. Express, 15 (2007) 15964.

[3] T. Manaka, E. Lim, R. Tamura, and M.Iwamoto, Nature Photonics, 1 (2007) 581.

[4] T. Manaka, F. Liu, M. Weis, and M. Iwamoto, Phys. Rev. B, 78 (2008) 121302.

[5] T. Manaka, F. Liu, M. Weis, and M. Iwamoto, J. Phys. Chem. C, 113(2009) 10279.

[6] T. Manaka, S.Kawashima, and M. Iwamoto, Appl. Phys. Lett., 97 (2010) 113302.

 

 

Organic Electronic Devices, Nonlinear Optics, Organic Material Electronics and Optics, Dielectrics Physics

 

Education:

   1991-95    Tokyo Institute of Technology, Organic and Polymeric Materials (Degree: B.E.)

   1995-97    Tokyo Institute of Technology, Organic and Polymeric Materials (Degree: M.E.)

1997-2000Tokyo institute of Technology, Organic and Polymeric Materials(Degree: D. of Eng.)

   Thesis: Nonlinear-optical spectral characteristics of structure-controlled conjugated molecular films

 

Working Experiences:

1997-2000    Research Fellowship for Young Scientist, JSPS.

2000-2010        Assistant Professor , Tokyo Institute of Technology

2010-present    AssociateProfessor , Tokyo Institute of Technology

   2010.9-2010.12  Visiting Researcher, University of Rennes 1, France

 

Awards:

2001.11Best Presentation Award, The Institute of Electrical Engineers of Japan.

2008.8Tokyo Tech Young Investigator Engineering Award from Tokyo Institute of Technology

2008.9 2008 M&BE Award for Young Researcher, M&BEDivision, Japan Applied Physics Society

  2011.10    Challenging Research President's Honorary Award, Tokyo Institute of Technology

  2012.4    The Young Scientists’ Prize,The Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology

 

International Journals  :

1)        T. Manaka, S. Kawashima, M. Iwamoto, "Charge modulated reflectance topography for probing in-plane carrier distribution in pentacene field-effect transistors", Appl. Phys. Lett., 97(11), 113302, (2010).

2)        T. Manaka, F. Liu, M. Weis and M. Iwamoto, "Studying Transient Carrier Behaviors in Pentacene Field Effect Transistors Using Visualized Electric Field Migration", J. Phys. Chem. C, Vol. 113 (23), pp 10279–10284 (2009).

3)        T. Manaka, F. Liu, W. Weis, M. Iwamoto, ”Diffusionlike electric-field migration in the channel of organic field-effect transistors”, Phys. Rev. B Rapid Commun., Vol. 78, pp.121302-1-4 (2008).

4)        T. Manaka, E. Lim, R. Tamura, M. Iwamoto, ”Direct imaging of carrier motion in organic transistors by optical second-harmonic generation”, Nature Photon., Vol. 1, pp.581-584 (2007).

5)        T. Manaka, E. Lim, R. Tamura, D. Yamada, M. Iwamoto, ” Probing of the electric field distribution in organic field effect transistor channel by microscopic second-harmonic generation”, Appl. Phys. Lett., Vol.89(7), pp.72113-1-3 (2006).

6)        T. Manaka, C.-Q. Li, X.-M. Cheng, and M. Iwamoto, ”Spectroscopic consideration of the surface potential built across phthalocyanine thin films on a metal electrode”, J. Chem. Phys., Vol. 120, pp.7725-7732 (2004).