Evaluation of silk fibroin as hygroscopic gate dielectric for indigo ambipolar Bio-OTFTs

• Main Authors: Tsai, Jen-Ching, 蔡仁靜
• Other Authors: Hwang, Jenn-Chang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/36h75s

碩士 === 國立清華大學 === 材料科學工程學系 === 102 === Silk fibroin is a natural protein extracted from Cocoons of Bombyx mori. Indigo (C16H10N2O2) is a natural dye pigment used extensively on commodities and has been reported to have ambipolar transport characteristics. The objective of this work is to fabricate Bio-organic thin film transistors (Bio-OTFTs) by integrating thermal evaporated indigo thin film and solution-based silk fibroin and to evaluate the performance of ambipolar devices at different relative humidity. The crystal quality of indigo is improved by inserting a TTC (Tetratetracontane, C44H90) interlayer on silk fibroin so that both the p- and n- channel transport appear simultaneously in the indigo ambipolar Bio-OTFT. In vacuum, the operation voltage is up to 100 V and the p- and n- channel field effect mobility (μFE,sat) are respectively ca. 9 × 10−5 and 0.05cm2V−1s−1 in saturation region and the threshold voltages (VTH) are ca. -90 V and 80 V, respectively. In air ambient, the amino acid including Glycine, Serine and Alanine in silk fibroin make silk fibroin a hygroscopic dielectric material. At 30% relative humidity, the indigo ambipolar OTFT exhibits comparable μFE,sat of ca. 10−2cm2V−1s−1 for hole and electron. While the relative humidity increases to ca. 50%, the VTH reduces to ca. ±30 V but with a worse n-channel performance ca. 10−3cm2V−1s−1. Hysteresis shows a higher back scanning current and a larger VTH shift in vacuum than in 55% relative humidity during gate voltage sweep.