title: Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates.
abstract: We demonstrate that local and long-range orders of poly(3-hexylthiophene) (P3HT) semicrystalline films can be synergistically improved by combining chemical functionalization of the substrate with solution-state disentanglement and preaggregation of P3HT in a θ solvent, leading to a very significant enhancement of the field effect carrier mobility. The preaggregation and surface functionalization effects combine to enhance the carrier mobility nearly 100-fold as compared with standard film preparation by spin-coating, and nearly 10-fold increase over the benefits of preaggregation alone. In situ quartz crystal microbalance with dissipation (QCM-D) experiments reveal enhanced deposition of preaggregates on surfaces modified with an alkyl-terminated self-assembled monolayer (SAM) in comparison to unaggregated polymer chains in the same conditions. Additional measurements reveal the combined preaggregation and surface functionalization significantly enhances local order of the conjugated polymer through planarization and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining complementary routes, such as well-known preaggregation with substrate chemical functionalization, to enhance the polymer self-assembly and improve its interfacial order with benefits for transport properties.
authors.affiliation: King Abdullah University of Science and Technology (KAUST) , KAUST Solar Center (KSC), and Division of Physical Sciences and Engineering, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Kui
authors.initials: K
authors.lastname: Zhao
authors.affiliation: King Abdullah University of Science and Technology (KAUST) , KAUST Solar Center (KSC), and Division of Physical Sciences and Engineering, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Hadayat Ullah
authors.initials: HU
authors.lastname: Khan
authors.affiliation: King Abdullah University of Science and Technology (KAUST) , KAUST Solar Center (KSC), and Division of Physical Sciences and Engineering, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Ruipeng
authors.initials: R
authors.lastname: Li
authors.affiliation: King Abdullah University of Science and Technology (KAUST) , KAUST Solar Center (KSC), and Division of Physical Sciences and Engineering, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Hanlin
authors.initials: H
authors.lastname: Hu
authors.affiliation: King Abdullah University of Science and Technology (KAUST) , KAUST Solar Center (KSC), and Division of Physical Sciences and Engineering, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Aram
authors.initials: A
authors.lastname: Amassian
keywords: aggregation; charge transport; conjugated polymers; organic thin film transistor; surface functionalization