Surface-Initiated Synthesis of Poly(3-methylthiophene) from Indium Tin Oxide and its Electrochemical Properties

Abstract

Poly(3-methylthiophene) (P3MT) was synthesized directly from indium tin oxide (ITO) electrodes modified with a phosphonic acid initiator, using Kumada catalyst transfer polymerization (KCTP). This work represents the first time that polymer thickness has been controlled in a surface initiated KCTP reaction, highlighting the utility of KCTP in achieving controlled polymerizations. Polymer film thicknesses were regulated by the variation of the solution monomer concentration and ranged from 30 to 265 nm. Electrochemical oxidative doping of these films was used to manipulate their near surface composition and effective work function. Doped states of the P3MT film are maintained even after the sample is removed from solution and potential control confirming the robustness of the films. Such materials with controllable thicknesses and electronic properties have the potential to be useful as interlayer materials for organic electronic applications.

Self-Assembly and Charge Transport of a Conjugated Polymer on ITO Substrates

“…Assembly of organic species on conducting substrates in the form of molecular wires and molecular assemblies have been widely studied, and within recent years, research have increased in polymer assemblies on varies conducting substrate [3,4,12]. Conjugated polymers end-functionalized with phosphonic acid anchoring groups have been grafted onto oxide substrates such as indium tin oxide (ITO) [5,[13][14][15][16], zinc oxide [17], silicon dioxide (SiO 2 ) [18], titanium dioxide (TiO 2 ) [19,20], and aluminium oxide (Al 2 O 3 ) [21]. Through a dehydration (condensation) reaction, the phosphonic acid group binds to each substrate covalently and possibly electrostatically (via hydrogen bonds), producing several binding modes [15].…”

“…There are a number of methods used to measure electron transfer between the organic species and the conducting substrate, for example, Voltammetric or impedancebased methods [5,6]. Cyclic voltammetry (CV) is an oxidation and reduction method that used to measure the kinetics of charge injection between a contact electrode and the organic material [7].…”

Nanoscale assembly into extended and continuous structures and hybrid materials

“…6,7 These synthetic advances have proven exceptionally useful for preparing P3HT and numerous functional polythiophene derivatives of controlled molecular weight (MW) and low MW distribution, both key features for understanding structure Àproperty relationships. Building on these chemistries, researchers continue to advance polythiophene syntheses, seen for example, in the work of Kiriy 8 and Luscombe, 9,10 in which initiation/propagation kinetics are tuned by balancing steric and electronic interactions of aryl halide initiators and metal catalysts. Such advances enable efficient surface-initiated polymerization for covalent connection of P3HT to plastic, metallic and semiconductor substrates, 10,11 as well as the fabrication of star or branched macromolecular architectures from multifunctional initiators.…”

“…Building on these chemistries, researchers continue to advance polythiophene syntheses, seen for example, in the work of Kiriy 8 and Luscombe, 9,10 in which initiation/propagation kinetics are tuned by balancing steric and electronic interactions of aryl halide initiators and metal catalysts. Such advances enable efficient surface-initiated polymerization for covalent connection of P3HT to plastic, metallic and semiconductor substrates, 10,11 as well as the fabrication of star or branched macromolecular architectures from multifunctional initiators. 8,9,12 The backbone conjugation of P3HT allows charge transport along the chain, while transport between polymer chains is provided by the interchain p-stacking in crystallized nanowires.…”

Endgroup and Sidechain Functionalization of Surface-Initiated ROMP Thin Films: Progress Towards ROMP-Based Molecular Wires

“…1 This addition polymerization technique is functional-group tolerant, uses stable and well-defined catalysts, and in monomers with plenty of ring strain can be coaxed to proceed in a nearly living manner. 2 For this reason, ROMP is a favorite method for surface-initiated polymerization, [3][4][5][6] second only to hidden-radical polymerization techniques such as ATRP. ROMP-based thin films, prepared by metathesis of catalyst in solution with alkene-functionalized surfaces followed by reaction of immobilized catalyst with monomer in solution, have been used to construct a variety of engineered surfaces.…”