High hole-mobility of rrP3HT in organic field-effect transistors using low-polarity polyurethane gate dielectric

• Published in: Organic electronics 2018-07, Vol.58, p.33-37
• Main Authors: Avila, Harold C., Serrano, Pablo, Barreto, Arthur R.J., Ahmed, Zubair, Gouvêa, Cristol de P., Vilani, Cecilia, Capaz, Rodrigo B., Marchiori, Cleber F.N., Cremona, Marco
• Format: Article
• Language: English
• Subjects: Charge carrier mobility; OFETs; Organic semiconductor; Poly-(3-hexylthiphene); Polyurethane
• ISSN: 1566-1199; 1878-5530; 1878-5530
• DOI: 10.1016/j.orgel.2018.03.033

We report unusually high charge carrier mobilities for regioregular poly(3-hexyltiophene) (rrP3HT) in organic field-effect transistors (OFETs) using polyurethane (PU) as dielectric layer. Our devices display hole mobilities up to 1.37 cm2/V in the saturation regime and an ON/OFF current ratio higher than 103, operating at voltages as low as −10 V, with a high IDS current of 1.5 μA. We assign the measured high mobilities mainly to the low density of randomly-oriented electric dipoles at the semiconductor/dielectric interface, which leads to a narrow energy distribution of the electronic levels available for charge transport in rrP3HT. This is confirmed by experimental and theoretical techniques: (1) temperature-dependent transport measurements for extraction of disorder-induced distribution of electronic levels; (2) density functional theory (DFT) calculations of electric dipole moments of PU; and (3) liquid contact-angle measurements for the dipolar component of dielectric surface tension. [Display omitted] •Low operation voltage and a hole mobility of 1.37 cm2/V were achieved.•The low energetic disorder at the rrP3HT/PU interface improves the OFET performance.•Transistors show remarkable low leakage current when compared with previous works.