Solution-processible TIPS-pentacene otft with low voltage driving by self-assembled monolayer gate dielectric

Abstract

Organic thin-film transistors, OTFTs have been attracting a great attention because they have many ad-vantages such as various synthetic method of organic materials, simple and easy process, low cost, and possibil-ity to realize flexible devices. The device performance of OTFTs was dramatically increased and the state-of-the-art OTFT device performance was comparable to the existing amorphous silicon TFTs used in active-matrix liquid crystal display, AMLCD. Therefore, application of OTFTs in AMLCD, AMOLED, e-paper, RFID, and sensors would be very promising. In OTFTs, pentacene, an organic semiconducting material for an active layer have been used for fabrication of OTFTs since it shows superior performance in terms of high mobility. Howev-er, pentacene has significantly low solubility into most organic solvents so that solution process with it is nearly impossible. Therefore, TIPS-pentacene with bulky side groups on pentacene was synthesized to be used with solution process. Also, SiO2 have been widely used for the gate dielectric for OTFT devices due to easy process and good electrical properties. However, the thickness of SiO2 layer is very thick in order to decrease gate leak-age. Consequently, it brings low capacitive coupling and subsequent operation voltage is not able to be low. One of strong candidate to realize low-voltage operation is using self-assembled monolayer (SAM) gate dielectric. The SAM layer is formed in a simple solution process and brings ultra low driving voltage due to its thin thick-ness. However, usual solution process on SAM layer is problematic because the surface tension of SAM layer is too low so that most organic solvents do not wet on it. In this work, pentacene-based OTFTs on SAM gate dielectric layer were fabricated for optimization of SAM layer prior to main research. Pentacene thin-film was found to have the best quality when the substrate temperature during deposition was 90℃. Also, SAM layer was optimized by varying O2-pl...