High-mobility solution-processed copper phthalocyanine-based organic field-effect transistors

Nandu B Chaure; Andrew N Cammidge; Isabelle Chambrier; Michael J Cook; Markys G Cain; Craig E Murphy; Chandana Pal; Asim K Ray

doi:10.1088/1468-6996/12/2/025001

High-mobility solution-processed copper phthalocyanine-based organic field-effect transistors

Sci Technol Adv Mater. 2011 Mar 15;12(2):025001. doi: 10.1088/1468-6996/12/2/025001. eCollection 2011 Apr.

Authors

Nandu B Chaure¹, Andrew N Cammidge², Isabelle Chambrier², Michael J Cook², Markys G Cain³, Craig E Murphy³, Chandana Pal⁴, Asim K Ray⁴

Affiliations

¹ Department of Physics, University of Pune, Ganeshkhind, Pune 411007, India.
² School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
³ National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK.
⁴ The Wolfson Centre for Materials Processing, Brunel University, Uxbridge, Middlesex UB8 3PH, UK.

Abstract

Solution-processed films of 1,4,8,11,15,18,22,25-octakis(hexyl) copper phthalocyanine (CuPc₆) were utilized as an active semiconducting layer in the fabrication of organic field-effect transistors (OFETs) in the bottom-gate configurations using chemical vapour deposited silicon dioxide (SiO₂) as gate dielectrics. The surface treatment of the gate dielectric with a self-assembled monolayer of octadecyltrichlorosilane (OTS) resulted in values of 4×10^-2 cm² V^-1 s^-1 and 10⁶ for saturation mobility and on/off current ratio, respectively. This improvement was accompanied by a shift in the threshold voltage from 3 V for untreated devices to -2 V for OTS treated devices. The trap density at the interface between the gate dielectric and semiconductor decreased by about one order of magnitude after the surface treatment. The transistors with the OTS treated gate dielectrics were more stable over a 30-day period in air than untreated ones.

Keywords: AFM; field effect mobility; organic thin film transistor; substituted copper phthalocyanine; surface treatment; topology.