Enhanced Mobility and Effective Control of Threshold Voltage in P3HT-Based Field-Effect Transistors via Inclusion of Oligothiophenes

• Published in: ACS applied materials & interfaces Vol. 7; no. 12; pp. 6652 - 6660
• Main Authors: Chu, Ping-Hsun, Zhang, Lei, Colella, Nicholas S, Fu, Boyi, Park, Jung Ok, Srinivasarao, Mohan, Briseño, Alejandro L, Reichmanis, Elsa
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01.04.2015
• Subjects: organic field effect transistors; poly(3-hexylthiophene); threshold voltage; polymer-oligomer blend; charge transport
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/am509090j

Improved organic field-effect transistor (OFET) performance through a polymer-oligomer semiconductor blend approach is demonstrated. Incorporation of 2,5-bis­(3-dodecylthiophen-2-yl)­thieno­[3,2-b]­thiophene (BTTT) into poly­(3-hexylthiophene) (P3HT) thin films leads to approximately a 5-fold increase in charge carrier mobility, a 10-fold increase in current on–off ratio, and concomitantly, a decreased threshold voltage to as low as 1.7 V in comparison to single component thin films. The blend approach required no pre- and/or post treatments, and processing was conducted under ambient conditions. The correlation of crystallinity, surface morphology and photophysical properties of the blend thin films was systematically investigated via X-ray diffraction, atomic force microscopy and optical absorption measurements respectively, as a function of blend composition. The dependence of thin-film morphology on the blend composition is illustrated for the P3HT:BTTT system. The blend approach provides an alternative avenue to combine the advantageous properties of conjugated polymers and oligomers for optimized semiconductor performance.