A New Approach to Improving Carrier Mobility of Organic Thin Film Transistors

• Main Authors: Cheng-yi Jiang, 江晟鎰
• Other Authors: John Cheng
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/67565463443835854450

碩士 === 國立中正大學 === 機械工程所 === 94 === Recently, organic thin film transistors (OTFTs) have been widely studied due to their potentials in large area, low cost manufacture and flexible electronic devices. However, the carrier mobilities of all reported OTFTs are too low to be useful for high-speed electronics or integrated circuits. How to improve the carrier mobility becomes the most urgent challenge of the OTFT research. One way to improve the carrier mobility is to enhance the structural order of the active semiconductive layer of the OTFT. The device would have high carrier mobility if its active layer had highly ordered crystalline structures. Traditional deposition methods such as the spin-coating, dip-coating, and contact printing all fail to provide orderly structures in the organic active layer. In this thesis, we propose a new approach to fabricating active layer with high structural order. The new approach is named the “Controlled Electrically Polymerization (CEP),” taking advantage of the fact that monomers in electrolyte tend to align along the electrical field while being electropolymerized. The key to the success of the approach is our maintaining the electrical field until complete evaporation of the electrolyte, consequently, giving rise to a stably well-regulated alignment of the electropolymerized polymers. To evaluate the effectiveness of the proposed approach, the fabricated OTFTs have been characterized and investigated using the UV-vis spectrometer, atomic force microscopy (AFM), and semiconductive parameter analyzer. By AFM phase images, ordered structures and crystalline domain in the electrically controlled polymerized active layer are apparent. Data collected using the semiconductive parameter analyzer to confirm the effectiveness of the proposed “Controlled Electrically Polymerization (CEP)” approach in improvement of the carrier mobility of the OTFT.