Fabrication and Characterization of Solution-Processed Organic Field-Effect Transistors

• Main Authors: Lo, Jhih-En, 駱智恩
• Other Authors: Masaki Horie
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/16134884081373802108

碩士 === 國立清華大學 === 化學工程學系 === 102 === In order to realize electrical properties of new polymers quickly, we demonstrated a vacuum evaporation-free OFETs fabrication system comprising conducting polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as gate electrode material. All fabrication procedures were completed under ambient condition without clean room or glove box. Thus poly[4,4- bis(hexadecyl)-4H-cyclopenta[2,1-b;3,4-b’]dithiophene-2,6-diyl-alt-2,1,3-benzothiad-iazole-4,7-diyl] (PCPDTBT) was initially selected as a semiconductor material because of its stability. In order to optimize the fabrication procedure, various fabrication conditions were investigated. The best device for PCPDTBT showed hole mobility of μsat = 4.32 × 10-4 cm2 V-1 s-1 with on/off current ratio of 102~103 and threshold voltage of -4 V. This was obtained by NaOH treatment of a patterned ITO glass substrate, without annealing of the ITO, HMDS treatment for ITO, preparation of PCPDTBT layer by spin coating at 2500 rpm from its chlorobenzene solution with a concentration of 10 mg mL-1, without annealing of PCPDTBT, and annealing of poly(methylmethacrylate) (PMMA) layer at 105 C. Morphology of PCPDTBT and PMMA surfaces was analyzed by atomic force microscopy. The optimum condition was applied to other semiconducting polymers, poly(3-hexylthiophene) (P3HT) and poly(9,9-dioctylfluorenyl-2,7-diyl-co-bithiophene) (F8T2), showing the best hole mobilities of 4.59 × 10-2 cm2 V-1 s-1 and 2.47 × 10-4 cm2 V-1 s-1, respectively. A comparison between our method and conventional method has been discussed. This method can be applied to initial screening of semiconducting polymers because the simple solution process reduces fabrication time and cost, without using an expensive evaporator, gold, or silicon wafer substrates.