title: Bottom-contact poly(3,3'''-didodecylquaterthiophene) thin-film transistors with gold source-drain electrodes modified by alkanethiol monolayers.
abstract: A series of alkanethiol monolayers (CH 3(CH 2) n-1 SH, n = 4, 6, 8, 10, 12, 14, 16) were used to modify gold source-drain electrode surfaces for bottom-contact poly(3,3'''-didodecylquaterthiophene) (PQT-12) thin-film transistors (TFTs). The device mobilities of TFTs were significantly increased from approximately 0.015 cm (2) V (-1) s (-1) for bare electrode TFTs to a maximum of approximately 0.1 cm (2) V (-1) s (-1) for the n = 8 monolayer devices. The mobilities of devices with alkanethiol-modified Au electrodes varied parabolically with alkyl length with values of 0.06, 0.1, and 0.04 cm (2) V (-1) s (-1) at n = 4, 8, and 16, respectively. Atomic force microscopy investigations reveal that alkanethiol electrode surface modifications promote polycrystalline PQT-12 morphologies at electrode/PQT-12 contacts, which probably increase the density of states of the PQT-12 semiconductor at the interfaces. The contact resistance of TFTs is strongly modulated by the surface modification and strongly varies with the alkanethiol chain length. The surface modifications of electrodes appear to significantly improve the charge injection, with consequent substantial improvement in device performance.
authors.affiliation: Division of Chemical & Biomolecular Engineering, School of Chemical & Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459.
authors.forename: Qin Jia
authors.initials: QJ
authors.lastname: Cai
authors.forename: Mary B
authors.initials: MB
authors.lastname: Chan-Park
authors.forename: Zhi Song
authors.initials: ZS
authors.lastname: Lu
authors.forename: Chang Ming
authors.initials: CM
authors.lastname: Li
authors.forename: Beng S
authors.initials: BS
authors.lastname: Ong
mesh_terms: D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D004867:Equipment Design; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry; D008839:Microelectrodes; D018625:Microscopy, Atomic Force; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry; D009930:Organic Chemicals; D012666:Semiconductors; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties; D014173:Transistors, Electronic
chemical_list: D009930:Organic Chemicals; D013438:Sulfhydryl Compounds; D006046:Gold