Ink-jet printing of organic semiconductor for fabricating organic thin-film transistors: Film uniformity control by ink composition

• Published in: Synthetic metals Vol. 159; no. 13; pp. 1381 - 1385
• Main Authors: Kim, Dongjo, Jeong, Sunho, Lee, Seong Hui, Moon, Jooho, Song, Jun Kwang
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.07.2009; Elsevier
• Subjects: Application fields; Applied sciences; Electronics; Exact sciences and technology; Ink; Ink-jet printing; Organic semiconductor; Organic thin-film transistor; Polymer industry, paints, wood; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Technology of polymers; Transistors; 68.55.am; Ink-jet printing; Organic thin-film transistor; Ink; 61.25.he; 72.80.Le; Organic semiconductor; Solvent effect; Voltage current curve; Surface topography; Oligomer; Experimental study; Property processing relationship; Structure processing relationship; Conjugated polymer; Mixed solvent; Tetramer; Silicon; Thiophene polymer; Thin film transistor; Ink jet printing; Growth from solution
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2009.02.025

We have investigated the influence of solvent chemistry on ink-jet printed semiconductor patterns. Our research focuses on improving the uniformity of an ink-jet printed single dot semiconductor by adjusting the solvent mixture combination. Use of a solvent mixture with one solvent of a lower boiling point and a higher solubility with respect to the semiconductor molecules and another of a higher boiling point and a lower solubility allows us to produce a uniform single dot pattern by ink-jet printing. It was observed that the film uniformity of the semiconductor layer plays an important role in determining the electrical parameters of the transistor. In comparison with uncontrolled ink composition, the OTFT fabricated from the well-controlled ink exhibited better device performance, including a carrier mobility of 8.5 × 10 −3 cm 2 V −1 s −1 in the saturation regime, an on/off current ratio of 10 3, and a threshold voltage of 0.39 V with subthreshold slopes of 0.95 V dec −1.