Realization of transistors using organic electronics

• Main Author: Ng, Vincent Yi Kai.
• Other Authors: Chang Joseph Sylvester
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/53537
• Institution: Nanyang Technological University

The overall objectives of this project are to investigate and realize printed electronics on flexible substrates. Specifically, this project focuses on the realization of organic transistors and a proto-type dual-gate transistor to verify the reliability and lifetime of OTFT due to the presence of the top dielectric layer. Concurrently, circuit simulation of AMOLED backplane driver is done to validate the design. At this juncture, a complete printing methodology based on screen printing has been developed – this is one of the very few reported in the literature. Screen printing is the technology adopted as it is an ‘additive’ printing process where compared to more established subtractive printing, it is ‘green’, more cost effective and is scalable. The competence developed thus far includes the printing of A4-size plastic films with a resolution of 100μm – this resolution is comparable with state of the art screen printing reported in the literature. The printing competence developed further includes modification of the interface between electrodes and semiconductor, and a novel slot die coating method, to print the organic semiconductor layer. Using this developed printing method, the performance of the printed circuits is significantly improved – the mobility of the printed transistors (using TIPS-Pentacene as the p-type semiconductor) features a high mobility of ~1.5cm2/Vs, typically ~10x higher than reported additive printed devices of the same design. This higher mobility has many positive implications to the parameters of the ensuring printed electronics circuits. A proto-type dual-gate transistor has been developed using the printed methods reported above and its top dielectric layer can act as an encapsulation to extend the reliability and lifetime of the OTFT. Circuit simulation of 2-transistor AMOLED backplane driver has been simulated and the latter simulation of the 4-transistor AMOLED backplane driver is able to minimize the non-uniformity current in the threshold voltage and carrier mobility of 2-transistor AMOLED backplane driver. However, both designs were deemed unsuitable to be used as a backplane driver pixel due to its large overall pixel size.