Morphology of Polythiophene Films Produced via Surface Polymerization by Ion-Assisted Deposition: A Combined Experimental and Computational Study

Abstract

Control of film morphology is widely recognized as one of the limiting factors in the development of conjugated polymers for photonic and electronic applications. Surface polymerization by ion-assisted deposition (SPIAD) is shown to drive film morphology. A wide variety of structures form in the SPIAD polythiophene films, including islands, lamellar structures, nanoscale crystallites, and fractal-like growth patterns. Density functional theory-molecular dynamic simulations are utilized to illustrate the manner in the incident ions affect polymerization, bond dissociation, and other chemical events in SPIAD. These ion-assisted events mediate thermal processes such as neutral deposition, sublimation, diffusion, and dewetting. However, these thermal processes are on longer timescales that cannot be directly studied by the computational techniques reported here.

Photoresponse of PbS nanoparticles–quaterthiophene films prepared by gaseous deposition as probed by XPS

“…Enhanced bonding in ion-assisted deposition of oligothiophenes has been observed previously [11][12][13] and was predicted by molecular dynamic simulations. 14 Ongoing work is exploring a similar mechanism in which the 4T þ PbS þ ion films display enhanced covalent bonding between the PbS nanoparticles and the 4T phase, induced by ion-assisted modification.…”

“…10 The acetylene ions used in ion-assisted deposition behave both as catalysts and reagents by energetically inducing bonding between condensed phase species and forming adducts with the neutral reagents. [11][12][13][14][15] X-ray photoelectron spectroscopy (XPS) was employed to probe photoconductivity of the PbS nanoparticle-4T composite films. For insulating and semiconducting samples, it has been observed that surface charging can shift the measured binding energies in an X-ray photoelectron (XP) spectrum.…”