Experimental Study and Statistical Analysis of Solution-Shearing Processed Organic Transistors Based on an Asymmetric Small-Molecule Semiconductor
Electr. Eng. & Center for Integrated Syst., Stanford Univ., Stanford, CA IEEE Transactions on Electron Devices
(Impact Factor: 2.47).
03/2009; 56(2):176 - 185. DOI: 10.1109/TED.2008.2010580
Solution processed organic field-effect transistors (SPOFETs) are crucial for realizing low-cost large-area/ubiquitous flexible electronics. Currently, both soluble high-mobility organic semiconductors and efficient solution processes are in demand. In this paper, we report the systematic experimental study and statistical modeling/analysis for the SPOFETs based on an asymmetric small-molecule organic semiconductor, trimethyl-[2, 2'; 5', 2''; 5'', 2'''] quarter-thiophen-5-yl-silane (4 T-TMS), which was deposited as the active layer through a recently developed low-temperature solution-shearing process. Three-dimensional statistical modeling and analysis bas ed on 46 different processing conditions was used to comprehensively study the solution-shearing process control and optimization for fabricating high-performance 4T-TMS SPOFETs. Various effects including solution concentration effect, shearing speed effect, and deposition temperature effect were investigated and discussed. Under optimized processing conditions, well-oriented crystalline 4 T-TMS thin films were deposited for the SPOFETs, which showed remarkable effective field-effect mobility up to 0.3 cm2/V middots in the saturation region and current on/off ratios over 106. Gaussian fitted uniformity and good air stability of these devices stored and tested under ambient conditions for six months suggest that 4 T-TMS SPOFETs based on the optimized solution-shearing process are promising for applications in organic electronic circuits and displays. Importantly, the systematic experiment design and the corresponding statistical modeling/analysis presented here provide a general guideline for process optimization for fabricating high-performance SPOFETs.
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ABSTRACT: We demonstrate low-voltage, solution-processed organic transistors on rough plastic substrates with a carrier mobility over 0.2 cm2/V s, a turn-on voltage of near 0 V, and a record low subthreshold slope of ∼ 80 mV/decade in ambient conditions. These exceptional characteristics are attributed to (1) a device stacking architecture with a conducting polymeric gate and a double layered dielectric composed of low-temperature cross-linked poly(4-vinylphenol), (2) a low interface trap density achieved by modifying the dielectric surface with a phenyl-terminated self-assembled monolayer from 4-phenylbutyltrichlorosilane, and (3) controlled crystallization of a small-molecule organic semiconductor film with favorable charge transport microstructure and a low bulk trap density as deposited by an optimized solution-shearing process. The device performance under different operating voltages was also examined and discussed.
Applied Physics Letters 05/2009; 94(20):203301-203301-3. DOI:10.1063/1.3133902 · 3.30 Impact Factor
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ABSTRACT: A new solution processed organic field-effect transistors (OFETs) having the strong steric effect and intermolecular force between SAMs and the fused ring aromatic based polymeric semiconductor has been demonstrated. The devices have good film coverage for the soluble organic semiconductor, which in turn improves a high current on/off after OTS and PTCS SAMs treatment because of highly packed crystalline films and drastic decrease of peripheral leakage path. a hydrophobic surface can be easily obtained by using a long methyl group based OTS SAMs. This new SAMs manipulation for polymeric semiconductors can provide not only the high crystalline thin-film and coating uniformity along a channel area, but also the improved current on/off ratio and fieldeffect mobility, which allow scaling of the fabrication method to large-area flexible organic electronics while achieving good device uniformity and yield.
Journal of Materials Science 01/2010; 45(2):566-569. DOI:10.1007/s10853-009-4047-x · 2.37 Impact Factor
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