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The purpose of this thesis is to fabricate pentacene organic thin-film transistors (TFT) on flexible substrate﹐measure and study their electrical characteristics.
Fabricating organic TFT on plastic substrate as switching device is necessary for the flexible display and the so-called electronic paper. Although, displays made from organic materials have been developed and even commercialized in recent years, improvements in some of their characteristics, such as carrier mobility, are still needed.
Conventionally, most TFTs are fabricated on inorganic silicon wafer or glass substrate because silicon or glass substrate can endure high processing temperature. On the other hand, low processing temperature of organic TFTs allows them to be fabricated on plastic substrate.
In this work, we tried to fabricate a OTFT on a flexible substrate, the PET(polythylene terephthalate). According to the literature, organic TFT using pentacene as the active layer can have the highest mobility which is about 3cm2V-1S-1. Therefore, we used pentacene as the active layer for our organic TFT.
In this thesis we successfully demonstrated the fabrication of pentacene organic TFT on PET plastic substrate. The highest mobility of our OTFT is only about μ 0.04 cm2V-1S-1 due to high gate leakage current and the plastic substrate shrinkage during thermal processing.
The substrate shrinkage and gate leakage current are likely to be eliminated by adopting alternative device structure so that high-temperature damage during source/drain evaporation can be avoided, and by carefully performing flexible substrate pre-cleaning process as well as pre-heating the flexible substrate to reduce substrate shrinkage during subsequent processing.
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