One-Dimensional Aggregation of Regioregular Polyalkylthiophenes

Abstract

Solvent-induced aggregation of regioregular head-to-tail poly(3-alkylthiophene)s (PATs) have been studied by means of AFM and UV−vis spectroscopy. In hexane, which is a good solvent for alkyl side chains but poor for polythiophene backbones, PAT molecules undergo ordered main-chain collapse driven by solvophobic interaction. Well-pronounced concentration-independent red shift of λ max and good resolved fine vibronic structure in the electronic absorption spectra observed upon addition of hexane indicate that planarization occurs on the singlemolecule level. A helical conformation of the man chain of PATs with 12 thiophene rings per each helical turn has been proposed. At the higher concentration of PATs the collapsed molecules undergo unexpected one-dimensional aggregation. Length of the particles varies from several nanometers to several hundreds nanometers and can be easily adjusted by the solvent composition or concentration of PATs.

Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers

“…Other growth conditions for slow crystallization such as Langmuir-Blodgett method, 33 precipitation in diluted poor solvents, 34,35 post-annealing treatments, 36 and solvent vapor-induced self-assembly 10 also lead to such fibrillarlike microstructures. It is believed that the crystal growth of P3HT tends to favor one-dimensional crystals, 37,38 with a length along the long axis extending from hundreds of nanometers to a few micrometers governed by the strong -stacking interaction between chains. The length of the nanoribbons increases with MW significantly from 15 kD to 29 kD, and soon reaches an apparent plateau in the intermediate MW range ͑between 29 kD to 52 kD͒ followed by a relatively weak MW dependence.…”

Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

“…11,13,17 Polymer crystallization improves the molecular stacking order and planarization of the backbone in the solid state, hence there have been a number of reports linking crystalline order to carrier transport. 7,18,19 Along this line, several strategies have been pursued to control molecular self-assembly and thin film microstructure, including by decreasing chain entanglements in the solution state, 12,13,17 tuning solution-processing conditions, [20][21][22][23][24] surface functionalization with a self-assembled monolayer (SAM) [25][26][27] and applying post-deposition thermal/solvent vapour annealing. [28][29][30] 3…”

Spectroscopic studies of different poly3hexylthiophene chain environments in a polyfluorene matrix

“…Polythiophenes and their regioregular forms are another class of well-known semiconductor polymers known to show complex morphology and morphological controlled pho-2 tophysics, where side chain structure and quality of solvent/environment also plays a significant role in their photophysical properties. [18,19,20] Thus this paring is an ideal test bed to study how blending effects the many possible different interactions between guest-guest, guest-host and host-host. In solution (as in films) the effects of concentration also effect optical properties, i.e.…”