Electrical characterization of polymer-based FETs fabricated by spin-coating poly(3-alkylthiophene)s

• Published in: IEEE transactions on electron devices 2004-11, Vol.51 (11), p.1892-1901
• Main Authors: Deen, M.J., Kazemeini, M.H., Haddara, Y.M., Jianfei Yu, Vamvounis, G., Holdcroft, S., Woods, W.
• Format: Article
• Language: English
• Subjects: Applied sciences; Carbon materials/devices; Electronics; Exact sciences and technology; FETs; Plastic films; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Thin film transistors; Transistors
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2004.837389

The current-voltage (I-V) characteristics of two different polymer thin-film transistors (TFTs), based on spin-coating of poly(3-hexylthiophene)-P3HT and poly(3-hexadecylthiophene)-P3HDT, are studied. A model is developed to interpret the results and to explain the differences between these two polymers. Various parameters of the semiconducting polymers, including bulk mobility, field-effect mobility, trap density, and unintentional dopant concentration are estimated. The model takes into account the domination of the bulk current over the channel current in the subthreshold regime as well as the effects of the depletion layer as parasitic resistances in series with the channel resistance. Furthermore, the effects of the films thickness on the electrical characteristics of these TFTs are discussed. Compared to the P3HT, the P3HDT-based TFT has a lower subthreshold slope, higher on current ratio, and higher field-effect mobility.