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Innovation Center for Organic Electronics Yamagata University 4th Symposium (Nobember 15)


Innovation Center for Organic Electronics Yamagata University held 4th symposium in Tokyo and Zoom online

Innovation Center for Organic Electronics Yamagata University (INOEL) held 4th symposium in Tokyo and Zoom online on 15th November, 2024. In this here, two lectures are closed up.

Prof.Morishita reported original organic-TFTs, which was manufactured by printing processes. The research group is researching the ink-jet printing method and reverse off-set printing method mainly. Organic semiconductor film is deposited and patterned by the former, on the other hand, electrodes are deposited and patterned by the latter.

The research group has pilot-produced bottom-gate/bottom contact organic-TFT using 5H-21DNTT organic semiconductor. Its carrier mobility is relatively high sae as 15 cm2/V･s. However, channel length of this TFT is 50 μm. In short, it's difficult to manufacture fine channel length. For this reason, it's not suitable for display device use.

Therefore, the next, the research group has pilot-produced organic-TFT with short channel length (5 - 10 μm) using DTBDT-C6 organic semiconductor as backplane of display. Its carrier mobility is relatively lower same as 2.5 cm2/V･s. However, 50 ppi OLED and 130 ppi e-paper could be driven by this organic-TFT.

High moisture vapor barrier property is ensured by SiNx/Al2O3/SiNx

Assistant Prof. Sugimoto announced moisture vapor barrier technology for OLED and organic series solar cell. Main technology is hybrid use of inorganic film and organic resin. The former is formed by sputtering method and ALD (Atomic Layer Deposition) method, on the other hand, the latter is formed by IJ printing method and spin-coating method.

▲OLED using moisture vapor barrier technology
(reprinted from HP of INOEL)
With respect to inorganic film, sputtering deposited SiNx film, ALD deposited Al2O3 film, and sputtering deposited SiNx film are stacked subsequently. In this structure, water vapor transmission rate is depend on film thickness of Al2O3 film. In case of 90 nm thickness, high barrier property same as approximate 10-5g/m2/day (WVTR) is obtained.

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