2005 Fiscal Year Final Research Report Summary
Development of Organic FET/LD Using Self-Organized Low-Dimensional Crystals
| Project/Area Number |
16350101
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional materials/Devices
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| Research Institution | Kobe University |
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Principal Investigator |
YANAGI Hisao Kobe University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (00220179)
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| Co-Investigator(Kenkyū-buntansha) |
TANIGUCHI Yoshio Shinshu University, Faculty of Textile Science and Technology, Professor, 繊維学部, 教授 (00283242)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Self-organization / Low-dimensional crystals / Field-effect transistor / Laser diode / Stimulated resonance Raman scattering / Optical amplification / P / N junstion / Current-injected emission |
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| Research Abstract |
In this study towards development of organic laser diodes (OLD), we first found that mirror-less laser actions from low-dimensional crystals of thiophene/phenylene co-oligomers (TPCO) based on stimulated resonant Raman scattering (SRRS). This light amplification effects was attributed to coherent molecular vibrations in the uniaxially oriented transition dipoles with large oscillation strength. Since the SRRS phenomena of the TPCO crystals can applicable to development of organic optical amplifiers and OLDs because of their advantages such as wide wavelength tunability with low ASE noise.
In order to apply the superior light-amplification abilities of the TPCO crystals to development of OLDs, we next investigated their carrier injection and transport properties by using organic field-effect transistors (OFET) with P/N heterojunction structures. The OFET devices fabricated with co-evaporated or laminated thin films of N-type C_<60> and P-type TPCO exhibited ambipolar injection of both el
… More
ectrons and holes.
Furthermore, we fabricated top-contact OFET devices with TPCO thin films by depositing Au source and Al:Li drain electrodes. Due to their asymmetric electrode structure with different work-function metals, those devices showed current-injected light emission under application of negative gate voltages. Microscopic observations revealed that the light emission occurred only at the edge of the drain electrode. It suggests that the holes accumulated in the TPCO channel recombine with the electrons at the drain-electrode interface. Therefore, the emission intensity is still low because the electron injection into the TPCO film is not achieved.
For future progress towards development of OLDs, we should continue to find new N-type semiconducting molecules which posses high electron mobilities comparable to the hole mobility of TPCO. Furthermore, we have to improve ambipolar carrier accumulation and recombination efficiencies in the channel layer by controlling the P/N junction OFET structures. Less
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