A polymer gate insulator is an important part in thin film transistor (TFT) to the development of flexible electronics. However, the flexible TFT with the polymer gate insulator can be break or delaminate during use, which occurs whole device failure. Here, a novel self-healing polymer gate insulator has been fabricated for flexible TFTs. The gate insulator with self-healing capability is composed of an ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and a random copolymer, p(MMA-co-DMA), combining methyl methacrylate and dopamine methacrylamide. In this combination, the ionic liquid in the polymer matrix acts as a plasticizer and lowers the glass transition temperature (Tg) of the polymer by interacting with the polymer chains. Therefore, damaged areas of ionic liquid-polymer matrix were successfully healed by heating the matrix above the Tg via the diffusion and re-entanglement of polymer chain. Also, due to the sufficient movement of ionic liquid molecules, the self-healing polymer gate insulator has a high capacitance value of ~1 μF cm-2 at a low frequency, 20 Hz. Using this gate insulator, top-gate ZnO TFTs operated well at a low gate bias voltage (VG=3 V) with a high field-effect mobility. The performance of the TFTs in terms of the field-effect mobility, on/off ratio, and threshold voltage was maintained after breaking and healing of TFT devices. The self-healing phenomena and characteristics of the TFT device will be discussed in detail.

Self-healing polymer gate insulator as high-capacitance gate dielectrics

251st National Meeting (2016)

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