| Summary: | 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.
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